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Zhu W, Pan L, Cui X, Russo AC, Ray R, Pederson B, Wei X, Lin LL, Hafner H, Gregg B, Shrestha N, Liu C, Naji A, Arvan P, Sandoval DA, Lindberg I, Qi L, Reinert RB. SEL1L-HRD1 ER-Associated Degradation Facilitates Prohormone Convertase 2 Maturation and Glucagon Production in Islet α Cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2025:2025.03.20.644437. [PMID: 40166183 PMCID: PMC11957139 DOI: 10.1101/2025.03.20.644437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 04/02/2025]
Abstract
Proteolytic cleavage of proglucagon by prohormone convertase 2 (PC2) is required for islet α cells to generate glucagon. However, the regulatory mechanisms underlying this process remain largely unclear. Here, we report that SEL1L-HRD1 endoplasmic reticulum (ER)-associated degradation (ERAD), a highly conserved protein quality control system responsible for clearing misfolded proteins from the ER, plays a key role in glucagon production by regulating turnover of the nascent proform of the PC2 enzyme (proPC2). Using a mouse model with SEL1L deletion in proglucagon-expressing cells, we observed a progressive decline in stimulated glucagon secretion and a reduction in pancreatic glucagon content. Mechanistically, we found that endogenous proPC2 is a substrate of SEL1L-HRD1 ERAD, and that degradation of misfolded proPC2 ensures the maturation of activation-competent proPC2 protein. These findings identify ERAD as a novel regulator of PC2 biology and an essential mechanism for maintaining α cell function.
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Affiliation(s)
- Wenzhen Zhu
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48105, USA
| | - Linxiu Pan
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48105, USA
- Present address: Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
| | - Xianwei Cui
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48105, USA
| | - Anna Chiara Russo
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48105, USA
| | - Rohit Ray
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48105, USA
| | - Brent Pederson
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48105, USA
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48105, USA
| | - Xiaoqiong Wei
- Present address: Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48105, USA
| | - Liangguang Leo Lin
- Present address: Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48105, USA
| | - Hannah Hafner
- Department of Pediatrics, Division of Pediatric Endocrinology, University of Michigan, Ann Arbor, MI 48105, USA
| | - Brigid Gregg
- Department of Pediatrics, Division of Pediatric Endocrinology, University of Michigan, Ann Arbor, MI 48105, USA
- Department of Nutritional Sciences, School of Public Health, University of Michigan, Ann Arbor, MI 48105, USA
| | - Neha Shrestha
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48105, USA
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48105, USA
| | - Chengyang Liu
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Ali Naji
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Peter Arvan
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48105, USA
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48105, USA
| | - Darleen A. Sandoval
- Department of Surgery, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Pediatrics, Nutrition Section, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Iris Lindberg
- Department of Anatomy and Neurobiology, University of Maryland-Baltimore, Baltimore, MD 21201, USA
| | - Ling Qi
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48105, USA
- Present address: Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48105, USA
| | - Rachel B. Reinert
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48105, USA
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Lampinen V, Ojanen MJT, Caro FM, Gröhn S, Hankaniemi MM, Pesu M, Hytönen VP. Experimental VLP vaccine displaying a furin antigen elicits production of autoantibodies and is well tolerated in mice. NANOSCALE ADVANCES 2024:d4na00483c. [PMID: 39430302 PMCID: PMC11485048 DOI: 10.1039/d4na00483c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2024] [Accepted: 10/09/2024] [Indexed: 10/22/2024]
Abstract
Proprotein convertase (PCSK) enzymes serve a wide range of regulatory roles in mammals, for example in metabolism and immunity, and altered activity of PCSKs is associated with disorders, such as cardiovascular disease and cancer. Inhibition of PCSK9 activity with therapeutic antibodies or small interfering RNAs is used in the clinic to lower blood cholesterol, and RNA interference -based silencing of FURIN (PCSK3) is being evaluated in clinical trials as a cancer treatment. Inhibiting these proteins through vaccine-induced autoantibodies could be a patient-friendly way to reduce the frequency of intervention and the overall price of treatment. Here, we show that a self-directed immune response against PCSK9 and furin can be generated in mice by presenting fragments of the proteins on norovirus-like particles (noro-VLPs). We genetically fused three PCSK peptides and the P domain of furin to the SpyCatcher linker protein and covalently conjugated them on noro-VLPs via SpyCatcher/SpyTag linkage. Both PCSK9 peptides and the furin P domain generated antigen specific IgGs even without conventional adjuvants. Importantly, vaccinating against furin did not cause adverse events or immune-mediated inflammatory disease. This study adds further support for the feasibility of VLP-based anti-PCSK9 vaccines and shows that the same principles can be applied to make novel vaccine candidates against other endogenous proteins such as furin. We also demonstrate that the noro-VLP can be used as a vaccine platform for presenting self-antigens.
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Affiliation(s)
- Vili Lampinen
- Faculty of Medicine and Health Technology, Tampere University Tampere Finland
| | - Markus J T Ojanen
- Faculty of Medicine and Health Technology, Tampere University Tampere Finland
| | - Fernanda Muñoz Caro
- Faculty of Medicine and Health Technology, Tampere University Tampere Finland
| | - Stina Gröhn
- Faculty of Medicine and Health Technology, Tampere University Tampere Finland
| | - Minna M Hankaniemi
- Faculty of Medicine and Health Technology, Tampere University Tampere Finland
| | - Marko Pesu
- Faculty of Medicine and Health Technology, Tampere University Tampere Finland
- Fimlab Laboratories Ltd FI-33014 Tampere Finland
| | - Vesa P Hytönen
- Faculty of Medicine and Health Technology, Tampere University Tampere Finland
- Fimlab Laboratories Ltd FI-33014 Tampere Finland
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Teitelman G. A Controversy Regarding the Identity of the Enzyme That Mediates Glucagon-Like Peptide 1 Synthesis in Human Alpha Cells. J Histochem Cytochem 2024; 72:545-550. [PMID: 39248433 PMCID: PMC11425746 DOI: 10.1369/00221554241274879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2024] [Accepted: 06/19/2024] [Indexed: 09/10/2024] Open
Abstract
Processing of proglucagon into glucagon-like peptide-1 (GLP-1) and GLP-2 in intestinal L cells is mediated by the prohormone convertase 1/3 (PC1/3) while PC2 is responsible for the synthesis of glucagon in pancreatic alpha cells. While GLP-1 is also produced by alpha cells, the identity of the convertase involved in its synthesis is still unsettled. It also remains to be determined whether all alpha cells produce the incretin. The aims of this study were first, to elucidate the identity of the proconvertase responsible for GLP-1 production in human alpha cells, and second, to ascertain whether the number of glucagon cells expressing GLP-1 increase during diabetes. To answer these questions, sections of pancreas from donors' non-diabetic controls, type 1 and type 2 diabetes were processed for double-labelled immunostaining of glucagon and GLP-1 and of each hormone and either PC1 or PC2. Stained sections were examined by confocal microscopy. It was found that all alpha cells of islets from those three groups expressed GLP-1 and PC2 but not PC1/3. This observation supports the view that PC2 is the convertase involved in GLP-1 synthesis in all human glucagon cells and suggests that the regulation of its activity may have important clinical application in diabetes.
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Jiang M, Wang N, Zhang Y, Zhang J, Li Y, Yan X, Zhang H, Li C, Guan Y, Liang B, Zhang W, Wu Y. Insulin receptor isoform B is required for efficient proinsulin processing in pancreatic β cells. iScience 2024; 27:110017. [PMID: 39021804 PMCID: PMC11253548 DOI: 10.1016/j.isci.2024.110017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 03/27/2024] [Accepted: 05/14/2024] [Indexed: 07/20/2024] Open
Abstract
The insulin receptor (INSR, IR) has two isoforms, IRA and IRB, through alternative splicing. However, their distinct functions in vivo remain unclear. Here we generated β cell-specific IRB knockout (KO) mice (βIRBKO). The KO mice displayed worsened hyperinsulinemia and hyperproinsulinemia in diet-induced obesity due to impaired proinsulin processing in β cells. Mechanistically, loss of IRB suppresses eukaryotic translation initiation factor 4G1 (eIF4G1) by stabilizing the transcriptional receptor sterol-regulatory element binding protein 1 (SREBP1). Moreover, excessive autocrine proinsulin in βIRBKO mice enhances the activity of extracellular signal-regulated kinase (ERK) through the remaining IRA to further stabilize nuclear SREBP1, forming a feedback loop. Collectively, our study paves the way to dissecting the isoform-specific function of IR in vivo and highlights the important roles of IRB in insulin processing and protecting β cells from lipotoxicity in obesity.
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Affiliation(s)
- Mingchao Jiang
- Institute for Genome Engineered Animal Models of Human Diseases, National Center of Genetically Engineered Animal Models for International Research, Liaoning Provence Key Lab of Genome Engineered Animal Models, Dalian Medical University, Dalian, Liaoning 116000, China
| | - Ning Wang
- Institute for Genome Engineered Animal Models of Human Diseases, National Center of Genetically Engineered Animal Models for International Research, Liaoning Provence Key Lab of Genome Engineered Animal Models, Dalian Medical University, Dalian, Liaoning 116000, China
| | - Yuqin Zhang
- Institute for Genome Engineered Animal Models of Human Diseases, National Center of Genetically Engineered Animal Models for International Research, Liaoning Provence Key Lab of Genome Engineered Animal Models, Dalian Medical University, Dalian, Liaoning 116000, China
| | - Jinjin Zhang
- Shandong Provincial Hospital, School of Laboratory Animal & Shandong Laboratory Animal Center, Science and Technology Innovation Center, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong 250021, China
| | - Youwei Li
- Institute for Genome Engineered Animal Models of Human Diseases, National Center of Genetically Engineered Animal Models for International Research, Liaoning Provence Key Lab of Genome Engineered Animal Models, Dalian Medical University, Dalian, Liaoning 116000, China
- Haidu College, Qingdao Agricultural University, Laiyang, Shandong 265200, China
| | - Xiu Yan
- Institute for Genome Engineered Animal Models of Human Diseases, National Center of Genetically Engineered Animal Models for International Research, Liaoning Provence Key Lab of Genome Engineered Animal Models, Dalian Medical University, Dalian, Liaoning 116000, China
| | - Honghao Zhang
- Institute for Genome Engineered Animal Models of Human Diseases, National Center of Genetically Engineered Animal Models for International Research, Liaoning Provence Key Lab of Genome Engineered Animal Models, Dalian Medical University, Dalian, Liaoning 116000, China
| | - Chengbin Li
- Center for Life Sciences, School of Life Sciences, Yunnan University, Kunming, Yunnan 650091, China
| | - Youfei Guan
- Advanced Institute for Medical Sciences, Dalian Medical University, Dalian 116044, China
| | - Bin Liang
- Center for Life Sciences, School of Life Sciences, Yunnan University, Kunming, Yunnan 650091, China
| | - Weiping Zhang
- Department of Pathophysiology, Naval Medical University, Shanghai 200433, China
| | - Yingjie Wu
- Institute for Genome Engineered Animal Models of Human Diseases, National Center of Genetically Engineered Animal Models for International Research, Liaoning Provence Key Lab of Genome Engineered Animal Models, Dalian Medical University, Dalian, Liaoning 116000, China
- Shandong Provincial Hospital, School of Laboratory Animal & Shandong Laboratory Animal Center, Science and Technology Innovation Center, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong 250021, China
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Hayashi Y. Advances in basic research on glucagon and alpha cells. Diabetol Int 2024; 15:348-352. [PMID: 39101161 PMCID: PMC11291817 DOI: 10.1007/s13340-024-00696-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 01/17/2024] [Indexed: 08/06/2024]
Abstract
The regulation of plasma amino acid levels by glucagon in humans first attracted the attention of researchers in the 1980s. Recent basic research using animal models of glucagon deficiency suggested that a major physiological role of glucagon is the regulation of amino acid metabolism rather than to increase blood glucose levels. In this regard, novel feedback regulatory mechanisms that are mediated by glucagon and amino acids have recently been described between islet alpha cells and the liver. Increasingly, hyperglucagonemia in humans with diabetes and/or nonalcoholic fatty liver diseases is reported to likely be a compensatory response to hepatic glucagon resistance. Severe glucagon resistance due to a glucagon receptor mutation in humans causes hyperaminoacidemia and islet alpha cell expansion combined with pancreatic hypertrophy. Notably, a recent report showed that the restoration of glucagon resistance by liver transplantation resolved not only hyperglucagonemia, but also pancreatic hypertrophy and other metabolic disorders. The mechanisms that regulate islet cell proliferation by amino acids largely remain unelucidated. Clarification of such mechanisms will increase our understanding of the pathophysiology of diseases related to glucagon.
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Affiliation(s)
- Yoshitaka Hayashi
- Department of Endocrinology, Research Institute of Environmental Medicine, Nagoya University, Chikusa-Ku, Nagoya, 464-8601 Japan
- Department of Endocrinology, Nagoya University Graduate School of Medicine, Nagoya University, Nagoya, Japan
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Štepihar D, Florke Gee RR, Hoyos Sanchez MC, Fon Tacer K. Cell-specific secretory granule sorting mechanisms: the role of MAGEL2 and retromer in hypothalamic regulated secretion. Front Cell Dev Biol 2023; 11:1243038. [PMID: 37799273 PMCID: PMC10548473 DOI: 10.3389/fcell.2023.1243038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 08/31/2023] [Indexed: 10/07/2023] Open
Abstract
Intracellular protein trafficking and sorting are extremely arduous in endocrine and neuroendocrine cells, which synthesize and secrete on-demand substantial quantities of proteins. To ensure that neuroendocrine secretion operates correctly, each step in the secretion pathways is tightly regulated and coordinated both spatially and temporally. At the trans-Golgi network (TGN), intrinsic structural features of proteins and several sorting mechanisms and distinct signals direct newly synthesized proteins into proper membrane vesicles that enter either constitutive or regulated secretion pathways. Furthermore, this anterograde transport is counterbalanced by retrograde transport, which not only maintains membrane homeostasis but also recycles various proteins that function in the sorting of secretory cargo, formation of transport intermediates, or retrieval of resident proteins of secretory organelles. The retromer complex recycles proteins from the endocytic pathway back to the plasma membrane or TGN and was recently identified as a critical player in regulated secretion in the hypothalamus. Furthermore, melanoma antigen protein L2 (MAGEL2) was discovered to act as a tissue-specific regulator of the retromer-dependent endosomal protein recycling pathway and, by doing so, ensures proper secretory granule formation and maturation. MAGEL2 is a mammalian-specific and maternally imprinted gene implicated in Prader-Willi and Schaaf-Yang neurodevelopmental syndromes. In this review, we will briefly discuss the current understanding of the regulated secretion pathway, encompassing anterograde and retrograde traffic. Although our understanding of the retrograde trafficking and sorting in regulated secretion is not yet complete, we will review recent insights into the molecular role of MAGEL2 in hypothalamic neuroendocrine secretion and how its dysregulation contributes to the symptoms of Prader-Willi and Schaaf-Yang patients. Given that the activation of many secreted proteins occurs after they enter secretory granules, modulation of the sorting efficiency in a tissue-specific manner may represent an evolutionary adaptation to environmental cues.
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Affiliation(s)
- Denis Štepihar
- School of Veterinary Medicine, Texas Tech University, Amarillo, TX, United States
- Texas Center for Comparative Cancer Research (TC3R), Amarillo, TX, United States
- Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Rebecca R. Florke Gee
- School of Veterinary Medicine, Texas Tech University, Amarillo, TX, United States
- Texas Center for Comparative Cancer Research (TC3R), Amarillo, TX, United States
| | - Maria Camila Hoyos Sanchez
- School of Veterinary Medicine, Texas Tech University, Amarillo, TX, United States
- Texas Center for Comparative Cancer Research (TC3R), Amarillo, TX, United States
| | - Klementina Fon Tacer
- School of Veterinary Medicine, Texas Tech University, Amarillo, TX, United States
- Texas Center for Comparative Cancer Research (TC3R), Amarillo, TX, United States
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Ueno S, Seino Y, Hidaka S, Nakatani M, Hitachi K, Murao N, Maeda Y, Fujisawa H, Shibata M, Takayanagi T, Iizuka K, Yabe D, Sugimura Y, Tsuchida K, Hayashi Y, Suzuki A. Blockade of glucagon increases muscle mass and alters fiber type composition in mice deficient in proglucagon-derived peptides. J Diabetes Investig 2023; 14:1045-1055. [PMID: 37300240 PMCID: PMC10445200 DOI: 10.1111/jdi.14032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 05/02/2023] [Accepted: 05/12/2023] [Indexed: 06/12/2023] Open
Abstract
AIMS/INTRODUCTION Glucagon is secreted from pancreatic α-cells and plays an important role in amino acid metabolism in liver. Various animal models deficient in glucagon action show hyper-amino acidemia and α-cell hyperplasia, indicating that glucagon contributes to feedback regulation between the liver and the α-cells. In addition, both insulin and various amino acids, including branched-chain amino acids and alanine, participate in protein synthesis in skeletal muscle. However, the effect of hyperaminoacidemia on skeletal muscle has not been investigated. In the present study, we examined the effect of blockade of glucagon action on skeletal muscle using mice deficient in proglucagon-derived peptides (GCGKO mice). MATERIALS AND METHODS Muscles isolated from GCGKO and control mice were analyzed for their morphology, gene expression and metabolites. RESULTS GCGKO mice showed muscle fiber hypertrophy, and a decreased ratio of type IIA and an increased ratio of type IIB fibers in the tibialis anterior. The expression levels of myosin heavy chain (Myh) 7, 2, 1 and myoglobin messenger ribonucleic acid were significantly lower in GCGKO mice than those in control mice in the tibialis anterior. GCGKO mice showed a significantly higher concentration of arginine, asparagine, serine and threonine in the quadriceps femoris muscles, and also alanine, aspartic acid, cysteine, glutamine, glycine and lysine, as well as four amino acids in gastrocnemius muscles. CONCLUSIONS These results show that hyperaminoacidemia induced by blockade of glucagon action in mice increases skeletal muscle weight and stimulates slow-to-fast transition in type II fibers of skeletal muscle, mimicking the phenotype of a high-protein diet.
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Affiliation(s)
- Shinji Ueno
- Departments of Endocrinology, Diabetes and MetabolismFujita Health University School of MedicineToyoakeAichiJapan
| | - Yusuke Seino
- Departments of Endocrinology, Diabetes and MetabolismFujita Health University School of MedicineToyoakeAichiJapan
- Yutaka Seino Distinguished Center for Diabetes ResearchKansai Electric Power Medical Research InstituteKyotoKyotoJapan
| | - Shihomi Hidaka
- Departments of Endocrinology, Diabetes and MetabolismFujita Health University School of MedicineToyoakeAichiJapan
| | - Masashi Nakatani
- Faculty of RehabilitationSeijoh UniversityTokaiAichiJapan
- Institute for Comprehensive Medical ScienceFujita Health UniversityToyoakeAichiJapan
| | - Keisuke Hitachi
- Institute for Comprehensive Medical ScienceFujita Health UniversityToyoakeAichiJapan
| | - Naoya Murao
- Departments of Endocrinology, Diabetes and MetabolismFujita Health University School of MedicineToyoakeAichiJapan
- Yutaka Seino Distinguished Center for Diabetes ResearchKansai Electric Power Medical Research InstituteKyotoKyotoJapan
| | - Yasuhiro Maeda
- Open Facility CenterFujita Health UniversityToyoakeAichiJapan
| | - Haruki Fujisawa
- Departments of Endocrinology, Diabetes and MetabolismFujita Health University School of MedicineToyoakeAichiJapan
| | - Megumi Shibata
- Departments of Endocrinology, Diabetes and MetabolismFujita Health University School of MedicineToyoakeAichiJapan
| | - Takeshi Takayanagi
- Departments of Endocrinology, Diabetes and MetabolismFujita Health University School of MedicineToyoakeAichiJapan
| | - Katsumi Iizuka
- Department of Clinical NutritionFujita Health UniversityToyoakeAichiJapan
| | - Daisuke Yabe
- Yutaka Seino Distinguished Center for Diabetes ResearchKansai Electric Power Medical Research InstituteKyotoKyotoJapan
- Department of Diabetes, Endocrinology and MetabolismGifu University Graduate School of MedicineGifuGifuJapan
- Department of Rheumatology and Clinical ImmunologyGifu University Graduate School of MedicineGifuGifuJapan
- Center for One Medicine Innovative Translational ResearchGifu University Graduate School of MedicineGifuGifuJapan
- Center for Healthcare Information TechnologyTokai National Higher Education and Research SystemNagoyaAichiJapan
- Division of Molecular and Metabolic MedicineKobe University Graduate School of MedicineKobeHyogoJapan
| | - Yoshihisa Sugimura
- Departments of Endocrinology, Diabetes and MetabolismFujita Health University School of MedicineToyoakeAichiJapan
| | - Kunihiro Tsuchida
- Institute for Comprehensive Medical ScienceFujita Health UniversityToyoakeAichiJapan
| | - Yoshitaka Hayashi
- Department of Endocrinology, Research Institute of Environmental MedicineNagoya UniversityNagoyaAichiJapan
- Department of EndocrinologyNagoya University Graduate School of MedicineNagoyaAichiJapan
| | - Atsushi Suzuki
- Departments of Endocrinology, Diabetes and MetabolismFujita Health University School of MedicineToyoakeAichiJapan
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Neumann J, Hofmann B, Dhein S, Gergs U. Glucagon and Its Receptors in the Mammalian Heart. Int J Mol Sci 2023; 24:12829. [PMID: 37629010 PMCID: PMC10454195 DOI: 10.3390/ijms241612829] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 07/25/2023] [Accepted: 08/03/2023] [Indexed: 08/27/2023] Open
Abstract
Glucagon exerts effects on the mammalian heart. These effects include alterations in the force of contraction, beating rate, and changes in the cardiac conduction system axis. The cardiac effects of glucagon vary according to species, region, age, and concomitant disease. Depending on the species and region studied, the contractile effects of glucagon can be robust, modest, or even absent. Glucagon is detected in the mammalian heart and might act with an autocrine or paracrine effect on the cardiac glucagon receptors. The glucagon levels in the blood and glucagon receptor levels in the heart can change with disease or simultaneous drug application. Glucagon might signal via the glucagon receptors but, albeit less potently, glucagon might also signal via glucagon-like-peptide-1-receptors (GLP1-receptors). Glucagon receptors signal in a species- and region-dependent fashion. Small molecules or antibodies act as antagonists to glucagon receptors, which may become an additional treatment option for diabetes mellitus. Hence, a novel review of the role of glucagon and the glucagon receptors in the mammalian heart, with an eye on the mouse and human heart, appears relevant. Mouse hearts are addressed here because they can be easily genetically modified to generate mice that may serve as models for better studying the human glucagon receptor.
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Affiliation(s)
- Joachim Neumann
- Institute for Pharmacology and Toxicology, Medical Faculty, Martin Luther University Halle-Wittenberg, Magdeburger Straße 4, D-06097 Halle (Saale), Germany;
| | - Britt Hofmann
- Department of Cardiac Surgery, Mid-German Heart Center, University Hospital Halle, Ernst Grube Straße 40, D-06097 Halle (Saale), Germany;
| | - Stefan Dhein
- Rudolf-Boehm Institut für Pharmakologie und Toxikologie, Universität Leipzig, Härtelstraße 16-18, D-04107 Leipzig, Germany;
| | - Ulrich Gergs
- Institute for Pharmacology and Toxicology, Medical Faculty, Martin Luther University Halle-Wittenberg, Magdeburger Straße 4, D-06097 Halle (Saale), Germany;
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Forsythe SD, Pu T, Andrews SG, Madigan JP, Sadowski SM. Models in Pancreatic Neuroendocrine Neoplasms: Current Perspectives and Future Directions. Cancers (Basel) 2023; 15:3756. [PMID: 37568572 PMCID: PMC10416968 DOI: 10.3390/cancers15153756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 07/21/2023] [Accepted: 07/23/2023] [Indexed: 08/13/2023] Open
Abstract
Pancreatic neuroendocrine neoplasms (pNENs) are a heterogeneous group of tumors derived from multiple neuroendocrine origin cell subtypes. Incidence rates for pNENs have steadily risen over the last decade, and outcomes continue to vary widely due to inability to properly screen. These tumors encompass a wide range of functional and non-functional subtypes, with their rarity and slow growth making therapeutic development difficult as most clinically used therapeutics are derived from retrospective analyses. Improved molecular understanding of these cancers has increased our knowledge of the tumor biology for pNENs. Despite these advances in our understanding of pNENs, there remains a dearth of models for further investigation. In this review, we will cover the current field of pNEN models, which include established cell lines, animal models such as mice and zebrafish, and three-dimensional (3D) cell models, and compare their uses in modeling various disease aspects. While no study model is a complete representation of pNEN biology, each has advantages which allow for new scientific understanding of these rare tumors. Future efforts and advancements in technology will continue to create new options in modeling these cancers.
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Affiliation(s)
- Steven D. Forsythe
- Neuroendocrine Cancer Therapy Section, Surgical Oncology Program, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (S.D.F.); (S.G.A.); (J.P.M.)
| | - Tracey Pu
- Surgical Oncology Program, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA;
| | - Stephen G. Andrews
- Neuroendocrine Cancer Therapy Section, Surgical Oncology Program, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (S.D.F.); (S.G.A.); (J.P.M.)
| | - James P. Madigan
- Neuroendocrine Cancer Therapy Section, Surgical Oncology Program, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (S.D.F.); (S.G.A.); (J.P.M.)
| | - Samira M. Sadowski
- Neuroendocrine Cancer Therapy Section, Surgical Oncology Program, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (S.D.F.); (S.G.A.); (J.P.M.)
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Loss of hypothalamic Furin affects POMC to proACTH cleavage and feeding behavior in high-fat diet-fed mice. Mol Metab 2022; 66:101627. [PMID: 36374777 PMCID: PMC9664468 DOI: 10.1016/j.molmet.2022.101627] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 10/23/2022] [Accepted: 10/28/2022] [Indexed: 11/06/2022] Open
Abstract
OBJECTIVE The hypothalamus regulates feeding and glucose homeostasis through the balanced action of different neuropeptides, which are cleaved and activated by the proprotein convertases PC1/3 and PC2. However, the recent association of polymorphisms in the proprotein convertase FURIN with type 2 diabetes, metabolic syndrome, and obesity, prompted us to investigate the role of FURIN in hypothalamic neurons controlling glucose and feeding. METHODS POMC-Cre+/- mice were bred with Furinfl/fl mice to generate conditional knockout mice with Furin-deletion in neurons expressing proopiomelanocortin (POMCFurKO), and Furinfl/fl mice were used as controls. POMCFurKO and controls were periodically monitored on both normal chow diet and high fat diet (HFD) for body weight and glucose tolerance by established in-vivo procedures. Food intake was measured in HFD-fed FurKO and controls. Hypothalamic Pomc mRNA was measured by RT-qPCR. ELISAs quantified POMC protein and resulting peptides in the hypothalamic extracts of POMCFurKO mice and controls. The in-vitro processing of POMC was studied by biochemical techniques in HEK293T and CHO cell lines lacking FURIN. RESULTS In control mice, Furin mRNA levels were significantly upregulated on HFD feeding, suggesting an increased demand for FURIN activity in obesogenic conditions. Under these conditions, the POMCFurKO mice were hyperphagic and had increased body weight compared to Furinfl/fl mice. Moreover, protein levels of POMC were elevated and ACTH concentrations markedly reduced. Also, the ratio of α-MSH/POMC was decreased in POMCFurKO mice compared to controls. This indicates that POMC processing was significantly reduced in the hypothalami of POMCFurKO mice, highlighting for the first time the involvement of FURIN in the cleavage of POMC. Importantly, we found that in vitro, the first stage in processing where POMC is cleaved into proACTH was achieved by FURIN but not by PC1/3 or the other proprotein convertases in cell lines lacking a regulated secretory pathway. CONCLUSIONS These results suggest that FURIN processes POMC into proACTH before sorting into the regulated secretory pathway, challenging the dogma that PC1/3 and PC2 are the only convertases responsible for POMC cleavage. Furthermore, its deletion affects feeding behaviors under obesogenic conditions.
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11
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Abdalqadir N, Adeli K. GLP-1 and GLP-2 Orchestrate Intestine Integrity, Gut Microbiota, and Immune System Crosstalk. Microorganisms 2022; 10:2061. [PMID: 36296337 PMCID: PMC9610230 DOI: 10.3390/microorganisms10102061] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 10/11/2022] [Accepted: 10/13/2022] [Indexed: 12/15/2022] Open
Abstract
The intestine represents the body's largest interface between internal organs and external environments except for its nutrient and fluid absorption functions. It has the ability to sense numerous endogenous and exogenous signals from both apical and basolateral surfaces and respond through endocrine and neuronal signaling to maintain metabolic homeostasis and energy expenditure. The intestine also harbours the largest population of microbes that interact with the host to maintain human health and diseases. Furthermore, the gut is known as the largest endocrine gland, secreting over 100 peptides and other molecules that act as signaling molecules to regulate human nutrition and physiology. Among these gut-derived hormones, glucagon-like peptide 1 (GLP-1) and -2 have received the most attention due to their critical role in intestinal function and food absorption as well as their application as key drug targets. In this review, we highlight the current state of the literature that has brought into light the importance of GLP-1 and GLP-2 in orchestrating intestine-microbiota-immune system crosstalk to maintain intestinal barrier integrity, inflammation, and metabolic homeostasis.
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Affiliation(s)
- Nyan Abdalqadir
- Molecular Medicine, Research Institute, The Hospital for Sick Children, Toronto, ON M5G 1H3, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5S 1A8, Canada
- Department of Biology, College of Science, University of Sulaimani, Sulaymaniyah 46001, Iraq
| | - Khosrow Adeli
- Molecular Medicine, Research Institute, The Hospital for Sick Children, Toronto, ON M5G 1H3, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5S 1A8, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
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12
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Meier DT, Rachid L, Wiedemann SJ, Traub S, Trimigliozzi K, Stawiski M, Sauteur L, Winter DV, Le Foll C, Brégère C, Guzman R, Odermatt A, Böni-Schnetzler M, Donath MY. Prohormone convertase 1/3 deficiency causes obesity due to impaired proinsulin processing. Nat Commun 2022; 13:4761. [PMID: 35963866 PMCID: PMC9376086 DOI: 10.1038/s41467-022-32509-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 08/03/2022] [Indexed: 12/12/2022] Open
Abstract
Defective insulin processing is associated with obesity and diabetes. Prohormone convertase 1/3 (PC1/3) is an endopeptidase required for the processing of neurotransmitters and hormones. PC1/3 deficiency and genome-wide association studies relate PC1/3 with early onset obesity. Here, we find that deletion of PC1/3 in obesity-related neuronal cells expressing proopiomelanocortin mildly and transiently change body weight and fail to produce a phenotype when targeted to Agouti-related peptide- or nestin-expressing tissues. In contrast, pancreatic β cell-specific PC1/3 ablation induces hyperphagia with consecutive obesity despite uncontrolled diabetes with glucosuria. Obesity develops not due to impaired pro-islet amyloid polypeptide processing but due to impaired insulin maturation. Proinsulin crosses the blood-brain-barrier but does not induce central satiety. Accordingly, insulin therapy prevents hyperphagia. Further, islet PC1/3 expression levels negatively correlate with body mass index in humans. In this work, we show that impaired PC1/3-mediated proinsulin processing, as observed in human prediabetes, promotes hyperphagic obesity. Defective insulin secretion is observed early in the development of diabetes. Here the authors report that β cell-specific deficiency of the insulin prohormone convertase 1/3 (PC1/3) leads not only to hyperglycemia, but also to hyperphagic obesity in mice.
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Affiliation(s)
- Daniel T Meier
- Clinic of Endocrinology, Diabetes and Metabolism, University Hospital Basel, Basel, Switzerland. .,Department of Biomedicine, University of Basel, Basel, Switzerland.
| | - Leila Rachid
- Clinic of Endocrinology, Diabetes and Metabolism, University Hospital Basel, Basel, Switzerland.,Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Sophia J Wiedemann
- Clinic of Endocrinology, Diabetes and Metabolism, University Hospital Basel, Basel, Switzerland.,Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Shuyang Traub
- Clinic of Endocrinology, Diabetes and Metabolism, University Hospital Basel, Basel, Switzerland.,Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Kelly Trimigliozzi
- Clinic of Endocrinology, Diabetes and Metabolism, University Hospital Basel, Basel, Switzerland.,Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Marc Stawiski
- Clinic of Endocrinology, Diabetes and Metabolism, University Hospital Basel, Basel, Switzerland.,Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Loïc Sauteur
- Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Denise V Winter
- Division of Molecular and Systems Toxicology, Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland
| | - Christelle Le Foll
- Institute of Veterinary Physiology, University of Zurich, 8057, Zurich, Switzerland
| | - Catherine Brégère
- Department of Biomedicine, University of Basel, Basel, Switzerland.,Department of Neurosurgery, University of Basel, Basel, Switzerland
| | - Raphael Guzman
- Department of Biomedicine, University of Basel, Basel, Switzerland.,Department of Neurosurgery, University of Basel, Basel, Switzerland
| | - Alex Odermatt
- Division of Molecular and Systems Toxicology, Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland
| | - Marianne Böni-Schnetzler
- Clinic of Endocrinology, Diabetes and Metabolism, University Hospital Basel, Basel, Switzerland.,Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Marc Y Donath
- Clinic of Endocrinology, Diabetes and Metabolism, University Hospital Basel, Basel, Switzerland.,Department of Biomedicine, University of Basel, Basel, Switzerland
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13
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Lu Y, Shi C, Jin X, He J, Yin Z. Domestication of farmed fish via the attenuation of stress responses mediated by the hypothalamus-pituitary-inter-renal endocrine axis. Front Endocrinol (Lausanne) 2022; 13:923475. [PMID: 35937837 PMCID: PMC9353172 DOI: 10.3389/fendo.2022.923475] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 06/29/2022] [Indexed: 12/13/2022] Open
Abstract
Human-directed domestication of terrestrial animals traditionally requires thousands of years for breeding. The most prominent behavioral features of domesticated animals include reduced aggression and enhanced tameness relative to their wild forebears, and such behaviors improve the social tolerance of domestic animals toward both humans and crowds of their own species. These behavioral responses are primarily mediated by the hypothalamic-pituitary-adrenal (inter-renal in fish) (HPA/I) endocrine axis, which is involved in the rapid conversion of neuronal-derived perceptual information into hormonal signals. Over recent decades, growing evidence implicating the attenuation of the HPA/I axis during the domestication of animals have been identified through comprehensive genomic analyses of the paleogenomic datasets of wild progenitors and their domestic congeners. Compared with that of terrestrial animals, domestication of most farmed fish species remains at early stages. The present review focuses on the application of HPI signaling attenuation to accelerate the domestication and genetic breeding of farmed fish. We anticipate that deeper understanding of HPI signaling and its implementation in the domestication of farmed fish will benefit genetic breeding to meet the global demands of the aquaculture industry.
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Affiliation(s)
- Yao Lu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Chuang Shi
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, China
| | - Xia Jin
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Jiangyan He
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Zhan Yin
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, China
- Hubei Hongshan Laboratory, Wuhan, China
- Hainan Yazhou Bay Seed Laboratory, Sanya, China
- *Correspondence: Zhan Yin,
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14
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Kiyozumi D, Ikawa M. Proteolysis in Reproduction: Lessons From Gene-Modified Organism Studies. Front Endocrinol (Lausanne) 2022; 13:876370. [PMID: 35600599 PMCID: PMC9114714 DOI: 10.3389/fendo.2022.876370] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 03/28/2022] [Indexed: 12/17/2022] Open
Abstract
The physiological roles of proteolysis are not limited to degrading unnecessary proteins. Proteolysis plays pivotal roles in various biological processes through cleaving peptide bonds to activate and inactivate proteins including enzymes, transcription factors, and receptors. As a wide range of cellular processes is regulated by proteolysis, abnormalities or dysregulation of such proteolytic processes therefore often cause diseases. Recent genetic studies have clarified the inclusion of proteases and protease inhibitors in various reproductive processes such as development of gonads, generation and activation of gametes, and physical interaction between gametes in various species including yeast, animals, and plants. Such studies not only clarify proteolysis-related factors but the biological processes regulated by proteolysis for successful reproduction. Here the physiological roles of proteases and proteolysis in reproduction will be reviewed based on findings using gene-modified organisms.
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Affiliation(s)
- Daiji Kiyozumi
- Research Institute for Microbial Diseases, Osaka University, Suita, Japan
- PRESTO, Japan Science and Technology Agency, Kawaguchi, Japan
| | - Masahito Ikawa
- Research Institute for Microbial Diseases, Osaka University, Suita, Japan
- The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
- CREST, Japan Science and Technology Agency, Kawaguchi, Japan
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15
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de Souza AA, de Andrade DM, Siqueira FDS, Di Iorio JF, Veloso MP, Coelho CDM, Viegas Junior C, Gontijo VS, Dos Santos MH, Meneghetti MCZ, Nader HB, Tersariol ILDS, Juliano L, Juliano MA, Judice WADS. Semysinthetic biflavonoid Morelloflavone-7,4',7″,3‴,4‴-penta-O-butanoyl is a more potent inhibitor of Proprotein Convertases Subtilisin/Kexin PC1/3 than Kex2 and Furin. Biochim Biophys Acta Gen Subj 2021; 1865:130016. [PMID: 34560176 DOI: 10.1016/j.bbagen.2021.130016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 08/11/2021] [Accepted: 09/17/2021] [Indexed: 11/23/2022]
Abstract
BACKGROUND Garcinia brasiliensis is a species native to the Amazon forest. The white mucilaginous pulp is used in folk medicine as a wound healing agent and for peptic ulcer, urinary, and tumor disease treatments. The activity of the proprotein convertases (PCs) Subtilisin/Kex is associated with the development of viral, bacterial and fungal infections, osteoporosis, hyperglycemia, atherosclerosis, cardiovascular, neurodegenerative and neoplastic diseases. METHODS Morelloflavone (BF1) and semisynthetic biflavonoid (BF2, 3 and 4) from Garcinia brasiliensis were tested as inhibitor of PCs Kex2, PC1/3 and Furin, and determined IC50, Ki, human proinflammatory cytokines secretion in Caco-2 cells, mechanism of inhibition, and performed molecular docking studies. RESULTS Biflavonoids were more effective in the inhibition of neuroendocrine PC1/3 than mammalian Furin and fungal Kex2. BF1 presented a mixed inhibition mechanism for Kex2 and PC1, and competitive inhibition for Furin. BF4 has no good interaction with Kex2 and Furin since carboxypropyl groups results in steric hindrance to ligand-protein interactions. Carboxypropyl groups of BF4 promote steric hindrance with Kex2 and Furin, but effective in the affinity of PC1/3. BF4 was more efficient at inhibiting PCl/3 (IC50 = 1.13 μM and Ki = 0,59 μM, simple linear competitive mechanism of inhibition) than Kex2, Furin. Also, our results strongly suggested that BF4 also inhibits the endogenous cellular PC1/3 activity in Caco-2 cells, since PC1/3 inhibition by BF4 causes a large increase in IL-8 and IL-1β secretion in Caco-2 cells. CONCLUSIONS BF4 is a potent and selective inhibitor of PC1/3. GENERAL SIGNIFICANCE BF4 is the best candidate for further clinical studies on inhibition of PC1/3.
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Affiliation(s)
- Aline Aparecida de Souza
- Centro Interdisciplinar de Investigação Bioquímica, Universidade de Mogi das Cruzes, 08780-911 Mogi das Cruzes, SP, Brazil
| | - Débora Martins de Andrade
- Centro Interdisciplinar de Investigação Bioquímica, Universidade de Mogi das Cruzes, 08780-911 Mogi das Cruzes, SP, Brazil
| | - Fábio da Silva Siqueira
- Centro Interdisciplinar de Investigação Bioquímica, Universidade de Mogi das Cruzes, 08780-911 Mogi das Cruzes, SP, Brazil
| | - Juliana Fortes Di Iorio
- Centro Interdisciplinar de Investigação Bioquímica, Universidade de Mogi das Cruzes, 08780-911 Mogi das Cruzes, SP, Brazil
| | - Marcia Paranho Veloso
- Laboratório de Modelagem Molecular e Simulação Computacional, Faculdade de Ciências Farmacêuticas, Universidade Federal de Alfenas, 37130-001 Alfenas, MG, Brazil
| | - Camila de Morais Coelho
- Laboratório de Modelagem Molecular e Simulação Computacional, Faculdade de Ciências Farmacêuticas, Universidade Federal de Alfenas, 37130-001 Alfenas, MG, Brazil
| | - Claudio Viegas Junior
- Laboratório de Pesquisa em Química Medicinal, Universidade Federal de Alfenas, 37,133-840 Alfenas, MG, Brazil
| | - Vanessa Silva Gontijo
- Laboratório de Pesquisa em Química Medicinal, Universidade Federal de Alfenas, 37,133-840 Alfenas, MG, Brazil
| | | | - Maria Cecília Zorél Meneghetti
- Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, 04044-020 São Paulo, SP, Brazil
| | - Helena Bonciani Nader
- Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, 04044-020 São Paulo, SP, Brazil
| | - Ivarne Luis Dos Santos Tersariol
- Centro Interdisciplinar de Investigação Bioquímica, Universidade de Mogi das Cruzes, 08780-911 Mogi das Cruzes, SP, Brazil; Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, 04044-020 São Paulo, SP, Brazil
| | - Luiz Juliano
- Departamento de Biofísica, Escola Paulista de Medicina, Universidade Federal de São Paulo, 04044-020 São Paulo, SP, Brazil
| | - Maria Aparecida Juliano
- Departamento de Biofísica, Escola Paulista de Medicina, Universidade Federal de São Paulo, 04044-020 São Paulo, SP, Brazil
| | - Wagner Alves de Souza Judice
- Centro Interdisciplinar de Investigação Bioquímica, Universidade de Mogi das Cruzes, 08780-911 Mogi das Cruzes, SP, Brazil.
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16
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Lindberg I, Fricker LD. Obesity, POMC, and POMC-processing Enzymes: Surprising Results From Animal Models. Endocrinology 2021; 162:6333651. [PMID: 34333593 PMCID: PMC8489426 DOI: 10.1210/endocr/bqab155] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Indexed: 11/19/2022]
Abstract
Peptides derived from proopiomelanocortin (POMC) are well-established neuropeptides and peptide hormones that perform multiple functions, including regulation of body weight. In humans and some animals, these peptides include α- and β-melanocyte-stimulating hormone (MSH). In certain rodent species, no β-MSH is produced from POMC because of a change in the cleavage site. Enzymes that convert POMC into MSH include prohormone convertases (PCs), carboxypeptidases (CPs), and peptidyl-α-amidating monooxygenase (PAM). Humans and mice with inactivating mutations in either PC1/3 or carboxypeptidase E (CPE) are obese, which was assumed to result from defective processing of POMC into MSH. However, recent studies have shown that selective loss of either PC1/3 or CPE in POMC-expressing cells does not cause obesity. These findings suggest that defects in POMC processing cannot alone account for the obesity observed in global PC1/3 or CPE mutants. We propose that obesity in animals lacking PC1/3 or CPE activity depends, at least in part, on deficient processing of peptides in non-POMC-expressing cells either in the brain and/or the periphery. Genetic background may also contribute to the manifestation of obesity.
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Affiliation(s)
- Iris Lindberg
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
- Correspondence: I. Lindberg, PhD, Department of Anatomy and Neurobiology, University of Maryland School of Medicine, 20 Penn St, Baltimore, MD 21201, USA.
| | - Lloyd D Fricker
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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17
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Pathak BK, Dey S, Mozumder S, Sengupta J. The role of membranes in function and dysfunction of intrinsically disordered amyloidogenic proteins. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2021; 128:397-434. [PMID: 35034725 DOI: 10.1016/bs.apcsb.2021.08.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Membrane-protein interactions play a major role in human physiology as well as in diseases pathology. Interaction of a protein with the membrane was previously thought to be dependent on well-defined three-dimensional structure of the protein. In recent decades, however, it has become evident that a large fraction of the proteome, particularly in eukaryotes, stays disordered in solution and these proteins are termed as intrinsically disordered proteins (IDPs). Also, a vast majority of human proteomes have been reported to contain substantially long disordered regions, called intrinsically disordered regions (IDRs), in addition to the structurally ordered regions. IDPs exist in an ensemble of conformations and the conformational flexibility enables IDPs to achieve functional diversity. IDPs (and IDRs) are found to be important players in cell signaling, where biological membranes act as anchors for signaling cascades. Therefore, IDPs modulate the membrane architectures, at the same time membrane composition also affects the binding of IDPs. Because of intrinsic disorders, misfolding of IDPs often leads to formation of oligomers, protofibrils and mature fibrils through progressive self-association. Accumulation of amyloid-like aggregates of some of the IDPs is a known causative agent for numerous diseases. In this chapter we highlight recent advances in understanding membrane interactions of some of the intrinsically disordered proteins involved in the pathogenesis of human diseases.
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Affiliation(s)
- Bani Kumar Pathak
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, India
| | - Sandip Dey
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, India
| | - Sukanya Mozumder
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Jayati Sengupta
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India.
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18
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Ramzy A, Kieffer TJ. Altered islet prohormone processing: A cause or consequence of diabetes? Physiol Rev 2021; 102:155-208. [PMID: 34280055 DOI: 10.1152/physrev.00008.2021] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Peptide hormones are first produced as larger precursor prohormones that require endoproteolytic cleavage to liberate the mature hormones. A structurally conserved but functionally distinct family of nine prohormone convertase enzymes (PCs) are responsible for cleavage of protein precursors of which PC1/3 and PC2 are known to be exclusive to neuroendocrine cells and responsible for prohormone cleavage. Differential expression of PCs within tissues define prohormone processing; whereas glucagon is the major product liberated from proglucagon via PC2 in pancreatic α-cells, proglucagon is preferentially processed by PC1/3 in intestinal L cells to produce glucagon-like peptides 1 and 2 (GLP-1, GLP-2). Beyond our understanding of processing of islet prohormones in healthy islets, there is convincing evidence that proinsulin, proIAPP, and proglucagon processing is altered during prediabetes and diabetes. There is predictive value of elevated circulating proinsulin or proinsulin : C-peptide ratio for progression to type 2 diabetes and elevated proinsulin or proinsulin : C-peptide is predictive for development of type 1 diabetes in at risk groups. After onset of diabetes, patients have elevated circulating proinsulin and proIAPP and proinsulin may be an autoantigen in type 1 diabetes. Further, preclinical studies reveal that α-cells have altered proglucagon processing during diabetes leading to increased GLP-1 production. We conclude that despite strong associative data, current evidence is inconclusive on the potential causal role of impaired prohormone processing in diabetes, and suggest that future work should focus on resolving the question of whether altered prohormone processing is a causal driver or merely a consequence of diabetes pathology.
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Affiliation(s)
- Adam Ramzy
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Timothy J Kieffer
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada.,Department of Surgery, University of British Columbia, Vancouver, BC, Canada.,School of Biomedical Engineering, University of British Columbia, Vancouver, BC, Canada
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19
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Fritzsche S, Hunnekuhl VS. Cell-specific expression and individual function of prohormone convertase PC1/3 in Tribolium larval growth highlights major evolutionary changes between beetle and fly neuroendocrine systems. EvoDevo 2021; 12:9. [PMID: 34187565 PMCID: PMC8244231 DOI: 10.1186/s13227-021-00179-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 06/14/2021] [Indexed: 11/15/2022] Open
Abstract
Background The insect neuroendocrine system acts in the regulation of physiology, development and growth. Molecular evolution of this system hence has the potential to allow for major biological differences between insect groups. Two prohormone convertases, PC1/3 and PC2, are found in animals and both function in the processing of neuropeptide precursors in the vertebrate neurosecretory pathway. Whereas PC2-function is conserved between the fly Drosophila and vertebrates, ancestral PC1/3 was lost in the fly lineage and has not been functionally studied in any protostome. Results In order to understand its original functions and the changes accompanying the gene loss in the fly, we investigated PC1/3 and PC2 expression and function in the beetle Tribolium castaneum. We found that PC2 is broadly expressed in the nervous system, whereas surprisingly, PC1/3 expression is restricted to specific cell groups in the posterior brain and suboesophageal ganglion. Both proteases have parallel but non-redundant functions in adult beetles’ viability and fertility. Female infertility following RNAi is caused by a failure to deposit sufficient yolk to the developing oocytes. Larval RNAi against PC2 produced moulting defects where the larvae were not able to shed their old cuticle. This ecdysis phenotype was also observed in a small subset of PC1/3 knockdown larvae and was strongest in a double knockdown. Unexpectedly, most PC1/3-RNAi larvae showed strongly reduced growth, but went through larval moults despite minimal to zero weight gain. Conclusions The cell type-specific expression of PC1/3 and its essential requirement for larval growth highlight the important role of this gene within the insect neuroendocrine system. Genomic conservation in most insect groups suggests that it has a comparable individual function in other insects as well, which has been replaced by alternative mechanisms in flies. Supplementary Information The online version contains supplementary material available at 10.1186/s13227-021-00179-w.
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Affiliation(s)
- Sonja Fritzsche
- Johann-Friedrich-Blumenbach Institute, GZMB, Göttingen University, Göttingen, Germany
| | - Vera S Hunnekuhl
- Johann-Friedrich-Blumenbach Institute, GZMB, Göttingen University, Göttingen, Germany.
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20
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Abstract
The kexin-like proprotein convertases perform the initial proteolytic cleavages that ultimately generate a variety of different mature peptide and proteins, ranging from brain neuropeptides to endocrine peptide hormones, to structural proteins, among others. In this review, we present a general introduction to proprotein convertase structure and biochemistry, followed by a comprehensive discussion of each member of the kexin-like subfamily of proprotein convertases. We summarize current knowledge of human proprotein convertase insufficiency syndromes, including genome-wide analyses of convertase polymorphisms, and compare these to convertase null and mutant mouse models. These mouse models have illuminated our understanding of the roles specific convertases play in human disease and have led to the identification of convertase-specific substrates; for example, the identification of procorin as a specific PACE4 substrate in the heart. We also discuss the limitations of mouse null models in interpreting human disease, such as differential precursor cleavage due to species-specific sequence differences, and the challenges presented by functional redundancy among convertases in attempting to assign specific cleavages and/or physiological roles. However, in most cases, knockout mouse models have added substantively both to our knowledge of diseases caused by human proprotein convertase insufficiency and to our appreciation of their normal physiological roles, as clearly seen in the case of the furin, proprotein convertase 1/3, and proprotein convertase 5/6 mouse models. The creation of more sophisticated mouse models with tissue- or temporally-restricted expression of specific convertases will improve our understanding of human proprotein convertase insufficiency and potentially provide support for the emerging concept of therapeutic inhibition of convertases.
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Affiliation(s)
- Manita Shakya
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Iris Lindberg
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
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21
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Shakya M, White A, Verchere CB, Low MJ, Lindberg I. Mice lacking PC1/3 expression in POMC-expressing cells do not develop obesity. Endocrinology 2021; 162:6167813. [PMID: 33693631 PMCID: PMC8253230 DOI: 10.1210/endocr/bqab055] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Indexed: 02/06/2023]
Abstract
Pro-opiomelanocortin (POMC) neurons form an integral part of the central melanocortin system regulating food intake and energy expenditure. Genetic and pharmacological studies have revealed that defects in POMC synthesis, processing, and receptor signaling lead to obesity. It is well established that POMC is extensively processed by a series of enzymes, including prohormone convertases PC1/3 and PC2, and that genetic insufficiency of both PC1/3 and POMC is strongly associated with obesity risk. However, whether PC1/3-mediated POMC processing is absolutely tied to body weight regulation is not known. To investigate this question, we generated a Pomc-CreER T2; Pcsk1 lox/lox mouse model in which Pcsk1 is specifically and temporally knocked out in POMC-expressing cells of adult mice by injecting tamoxifen at eight weeks of age. We then measured the impact of Pcsk1 deletion on POMC cleavage to ACTH and α-MSH, and on body weight. In whole pituitary, POMC cleavage was significantly impacted by the loss of Pcsk1, while hypothalamic POMC-derived peptide levels remained similar in all genotypes. However, intact POMC levels were greatly elevated in Pomc-CreER T2; Pcsk1 lox/lox mice. Males expressed two-fold greater levels of pituitary PC1/3 protein than females, consistent with their increased POMC cleavage. Past studies show that mice with germline removal of PC1/3 do not develop obesity, while mice expressing mutant PC1/3 forms do develop obesity. We conclude that obesity pathways are not disrupted by PC1/3 loss solely in POMC-expressing cells, further disfavoring the idea that alterations in POMC processing underlie obesity in PCSK1 deficiency.
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Affiliation(s)
- Manita Shakya
- Department of Anatomy and Neurobiology, University of
Maryland-Baltimore, Baltimore, MD 21201,
USA
| | - Surbhi
- Department of Molecular & Integrative Physiology,
University of Michigan, Ann Arbor, MI
481091, USA
| | - Anne White
- Division of Diabetes, Endocrinology and Gastroenterology,
University of Manchester, Manchester, M13
9PT, United Kingdom
| | - C Bruce Verchere
- Departments of Pathology & Laboratory Medicine and
Surgery, University of British Columbia, British
Columbia, V5Z 4H4, Canada
| | - Malcolm J Low
- Department of Molecular & Integrative Physiology,
University of Michigan, Ann Arbor, MI
481091, USA
| | - Iris Lindberg
- Department of Anatomy and Neurobiology, University of
Maryland-Baltimore, Baltimore, MD 21201,
USA
- Correspondence: Iris Lindberg, PhD,
Department of Anatomy and Neurobiology, 20 Penn St., HSF2, S267, University of
Maryland-Baltimore, Baltimore, MD 21201, USA. E-mail:
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22
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Rehfeld JF, Goetze JP. Processing-independent analysis (PIA): a method for quantitation of the total peptide-gene expression. Peptides 2021; 135:170427. [PMID: 33069691 DOI: 10.1016/j.peptides.2020.170427] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 10/06/2020] [Accepted: 10/10/2020] [Indexed: 12/26/2022]
Abstract
The translational product of protein-coding genes undergoes extensive posttranslational modifications. The modifications ensure an increased molecular and functional diversity at protein- and peptide-level. Prohormones are small pro-proteins that are expressed in many cell types, for instance endocrine cells, immune cells, myocytes and neurons. Here they mature to bioactive peptides (cytokines, hormones, growth factors, and neurotransmitters) that are released from the cells in an often regulated manner. The posttranslational processing of prohormones is cell-specific, however, and may vary during evolution and disease. Therefore, it is often inadequate to measure just a single peptide fragment as marker of endocrine, immune, and neuronal functions. In order to meet this challenge, we developed years back a simple "processing-independent analysis" (PIA) for accurate quantification of the total pro-protein product - irrespective of the degree and nature of the posttranslational processing. This review provides an overview of the PIA principle and describes examples of PIA results in different peptide systems.
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Affiliation(s)
- Jens F Rehfeld
- Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Denmark.
| | - Jens P Goetze
- Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Denmark
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23
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Acosta-Montalvo A, Saponaro C, Kerr-Conte J, Prehn JHM, Pattou F, Bonner C. Proglucagon-Derived Peptides Expression and Secretion in Rat Insulinoma INS-1 Cells. Front Cell Dev Biol 2020; 8:590763. [PMID: 33240888 PMCID: PMC7683504 DOI: 10.3389/fcell.2020.590763] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Accepted: 10/20/2020] [Indexed: 11/26/2022] Open
Abstract
Rat insulinoma INS-1 cells are widely used to study insulin secretory mechanisms. Studies have shown that a population of INS-1 cells are bi-hormonal, co-expressing insulin, and proglucagon proteins. They coined this population as immature cells since they co-secrete proglucagon-derived peptides from the same secretory vesicles similar to that of insulin. Since proglucagon encodes multiple peptides including glucagon, glucagon-like-peptide-1 (GLP-1), GLP-2, oxyntomodulin, and glicentin, their specific expression and secretion are technically challenging. In this study, we aimed to focus on glucagon expression which shares the same amino acid sequence with glicentin and proglucagon. Validation of the anti-glucagon antibody (Abcam) by Western blotting techniques revealed that the antibody detects proglucagon (≈ 20 kDa), glicentin (≈ 9 kDa), and glucagon (≈ 3 kDa) in INS-1 cells and primary islets, all of which were absent in the kidney cell line (HEK293). Using the validated anti-glucagon antibody, we showed by immunofluorescence imaging that a population of INS-1 cells co-express insulin and proglucagon-derived proteins. Furthermore, we found that chronic treatment of INS-1 cells with high-glucose decreases insulin and glucagon content, and also reduces the percentage of bi-hormonal cells. In line with insulin secretion, we found glucagon and glicentin secretion to be induced in a glucose-dependent manner. We conclude that INS-1 cells are a useful model to study glucose-stimulated insulin secretion, but not that of glucagon or glicentin. Our study suggests Western blotting technique as an important tool for researchers to study proglucagon-derived peptides expression and regulation in primary islets in response to various metabolic stimuli.
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Affiliation(s)
- Ana Acosta-Montalvo
- INSERM, U1190, Lille, France.,European Genomic Institute for Diabetes, Lille, France.,University of Lille, Lille, France
| | - Chiara Saponaro
- INSERM, U1190, Lille, France.,European Genomic Institute for Diabetes, Lille, France.,University of Lille, Lille, France
| | - Julie Kerr-Conte
- INSERM, U1190, Lille, France.,European Genomic Institute for Diabetes, Lille, France.,University of Lille, Lille, France
| | - Jochen H M Prehn
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - François Pattou
- INSERM, U1190, Lille, France.,European Genomic Institute for Diabetes, Lille, France.,University of Lille, Lille, France.,Chirurgie Endocrinienne et Métabolique, CHU Lille, Lille, France
| | - Caroline Bonner
- INSERM, U1190, Lille, France.,European Genomic Institute for Diabetes, Lille, France.,University of Lille, Lille, France.,Institut Pasteur de Lille, Lille, France
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24
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Ramzy A, Asadi A, Kieffer TJ. Revisiting Proinsulin Processing: Evidence That Human β-Cells Process Proinsulin With Prohormone Convertase (PC) 1/3 but Not PC2. Diabetes 2020; 69:1451-1462. [PMID: 32291281 DOI: 10.2337/db19-0276] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 04/03/2020] [Indexed: 11/13/2022]
Abstract
Insulin is first produced in pancreatic β-cells as the precursor prohormone proinsulin. Defective proinsulin processing has been implicated in the pathogenesis of both type 1 and type 2 diabetes. Though there is substantial evidence that mouse β-cells process proinsulin using prohormone convertase 1/3 (PC1/3) and then prohormone convertase 2 (PC2), this finding has not been verified in human β-cells. Immunofluorescence with validated antibodies revealed that there was no detectable PC2 immunoreactivity in human β-cells and little PCSK2 mRNA by in situ hybridization. Similarly, rat β-cells were not immunoreactive for PC2. In all histological experiments, PC2 immunoreactivity in neighboring α-cells acted as a positive control. In donors with type 2 diabetes, β-cells had elevated PC2 immunoreactivity, suggesting that aberrant PC2 expression may contribute to impaired proinsulin processing in β-cells of patients with diabetes. To support histological findings using a biochemical approach, human islets were used for pulse-chase experiments. Despite inhibition of PC2 function by temperature blockade, brefeldin A, chloroquine, and multiple inhibitors that blocked production of mature glucagon from proglucagon, β-cells retained the ability to produce mature insulin. Conversely, suppression of PC1/3 blocked processing of proinsulin but not proglucagon. By demonstrating that healthy human β-cells process proinsulin by PC1/3 but not PC2, we suggest that there is a need to revise the long-standing theory of proinsulin processing.
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Affiliation(s)
- Adam Ramzy
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Ali Asadi
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Timothy J Kieffer
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia, Canada
- Department of Surgery, The University of British Columbia, Vancouver, British Columbia, Canada
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25
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Tellez K, Hang Y, Gu X, Chang CA, Stein RW, Kim SK. In vivo studies of glucagon secretion by human islets transplanted in mice. Nat Metab 2020; 2:547-557. [PMID: 32694729 PMCID: PMC7739959 DOI: 10.1038/s42255-020-0213-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 04/24/2020] [Indexed: 02/06/2023]
Abstract
Little is known about regulated glucagon secretion by human islet α-cells compared to insulin secretion from β-cells, despite conclusive evidence of dysfunction in both cell types in diabetes mellitus. Distinct insulins in humans and mice permit in vivo studies of human β-cell regulation after human islet transplantation in immunocompromised mice, whereas identical glucagon sequences prevent analogous in vivo measures of glucagon output from human α-cells. Here, we use CRISPR-Cas9 editing to remove glucagon codons 2-29 in immunocompromised NSG mice, preserving the production of other proglucagon-derived hormones. Glucagon knockout NSG (GKO-NSG) mice have metabolic, liver and pancreatic phenotypes associated with glucagon-signalling deficits that revert after transplantation of human islets from non-diabetic donors. Glucagon hypersecretion by transplanted islets from donors with type 2 diabetes revealed islet-intrinsic defects. We suggest that GKO-NSG mice provide an unprecedented resource to investigate human α-cell regulation in vivo.
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Affiliation(s)
- Krissie Tellez
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Yan Hang
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
- Stanford Diabetes Research Center, Stanford University School of Medicine, Stanford, CA, USA
| | - Xueying Gu
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Charles A Chang
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Roland W Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Seung K Kim
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA.
- Stanford Diabetes Research Center, Stanford University School of Medicine, Stanford, CA, USA.
- Department of Medicine (Endocrinology Division), Stanford University School of Medicine, Stanford, CA, USA.
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26
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Marquina-Sanchez B, Fortelny N, Farlik M, Vieira A, Collombat P, Bock C, Kubicek S. Single-cell RNA-seq with spike-in cells enables accurate quantification of cell-specific drug effects in pancreatic islets. Genome Biol 2020; 21:106. [PMID: 32375897 PMCID: PMC7201533 DOI: 10.1186/s13059-020-02006-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 03/27/2020] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Single-cell RNA-seq (scRNA-seq) is emerging as a powerful tool to dissect cell-specific effects of drug treatment in complex tissues. This application requires high levels of precision, robustness, and quantitative accuracy-beyond those achievable with existing methods for mainly qualitative single-cell analysis. Here, we establish the use of standardized reference cells as spike-in controls for accurate and robust dissection of single-cell drug responses. RESULTS We find that contamination by cell-free RNA can constitute up to 20% of reads in human primary tissue samples, and we show that the ensuing biases can be removed effectively using a novel bioinformatics algorithm. Applying our method to both human and mouse pancreatic islets treated ex vivo, we obtain an accurate and quantitative assessment of cell-specific drug effects on the transcriptome. We observe that FOXO inhibition induces dedifferentiation of both alpha and beta cells, while artemether treatment upregulates insulin and other beta cell marker genes in a subset of alpha cells. In beta cells, dedifferentiation and insulin repression upon artemether treatment occurs predominantly in mouse but not in human samples. CONCLUSIONS This new method for quantitative, error-correcting, scRNA-seq data normalization using spike-in reference cells helps clarify complex cell-specific effects of pharmacological perturbations with single-cell resolution and high quantitative accuracy.
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Affiliation(s)
- Brenda Marquina-Sanchez
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, AKH BT 25.3, 1090, Vienna, Austria
| | - Nikolaus Fortelny
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, AKH BT 25.3, 1090, Vienna, Austria
| | - Matthias Farlik
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, AKH BT 25.3, 1090, Vienna, Austria
- Department of Dermatology, Medical University of Vienna, 1090, Vienna, Austria
| | | | | | - Christoph Bock
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, AKH BT 25.3, 1090, Vienna, Austria.
- Department of Laboratory Medicine, Medical University of Vienna, 1090, Vienna, Austria.
| | - Stefan Kubicek
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, AKH BT 25.3, 1090, Vienna, Austria.
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27
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Abstract
Glucagon and its partner insulin are dually linked in both their secretion from islet cells and their action in the liver. Glucagon signaling increases hepatic glucose output, and hyperglucagonemia is partly responsible for the hyperglycemia in diabetes, making glucagon an attractive target for therapeutic intervention. Interrupting glucagon signaling lowers blood glucose but also results in hyperglucagonemia and α-cell hyperplasia. Investigation of the mechanism for α-cell proliferation led to the description of a conserved liver-α-cell axis where glucagon is a critical regulator of amino acid homeostasis. In return, amino acids regulate α-cell function and proliferation. New evidence suggests that dysfunction of the axis in humans may result in the hyperglucagonemia observed in diabetes. This discussion outlines important but often overlooked roles for glucagon that extend beyond glycemia and supports a new role for α-cells as amino acid sensors.
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Affiliation(s)
- E Danielle Dean
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, and Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
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28
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Quesada-Candela C, Tudurí E, Marroquí L, Alonso-Magdalena P, Quesada I, Nadal Á. Morphological and functional adaptations of pancreatic alpha-cells during late pregnancy in the mouse. Metabolism 2020; 102:153963. [PMID: 31593706 DOI: 10.1016/j.metabol.2019.153963] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 08/01/2019] [Accepted: 08/26/2019] [Indexed: 01/18/2023]
Abstract
BACKGROUND Pregnancy represents a major metabolic challenge for the mother, and involves a compensatory response of the pancreatic beta-cell to maintain normoglycemia. However, although pancreatic alpha-cells play a key role in glucose homeostasis and seem to be involved in gestational diabetes, there is no information about their potential adaptations or changes during pregnancy. MATERIAL AND METHODS Non-pregnant (controls) and pregnant C57BL/6 mice at gestational day 18.5 (G18.5) and their isolated pancreatic islets were used for in vivo and ex vivo studies, respectively. The effect of pregnancy hormones was tested in glucagon-secreting α-TC1.9 cells. Immunohistochemical analysis was performed in pancreatic slices. Glucagon gene expression was monitored by RT-qPCR. Glucagon secretion and plasma hormones were measured by ELISA. RESULTS Pregnant mice on G18.5 exhibited alpha-cell hypertrophy as well as augmented alpha-cell area and mass. This alpha-cell mass expansion was mainly due to increased proliferation. No changes in alpha-cell apoptosis, ductal neogenesis, or alpha-to-beta transdifferentiation were found compared with controls. Pregnant mice on G18.5 exhibited hypoglucagonemia. Additionally, in vitro glucagon secretion at low glucose levels was decreased in isolated islets from pregnant animals. Glucagon content was also reduced. Experiments in α-TC1.9 cells indicated that, unlike estradiol and progesterone, placental lactogens and prolactin stimulated alpha-cell proliferation. Placental lactogens, prolactin and estradiol also inhibited glucagon release from α-TC1.9 cells at low glucose levels. CONCLUSIONS The pancreatic alpha-cell in mice undergoes several morphofunctional changes during late pregnancy, which may contribute to proper glucose homeostasis. Gestational hormones are likely involved in these processes.
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Affiliation(s)
- Cristina Quesada-Candela
- Instituto de Biología Molecular y Celular (IBMC), Universitas Miguel Hernández, 03202 Elche, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universitas Miguel Hernández, 03202 Elche, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Spain
| | - Eva Tudurí
- Instituto de Biología Molecular y Celular (IBMC), Universitas Miguel Hernández, 03202 Elche, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universitas Miguel Hernández, 03202 Elche, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Spain
| | - Laura Marroquí
- Instituto de Biología Molecular y Celular (IBMC), Universitas Miguel Hernández, 03202 Elche, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universitas Miguel Hernández, 03202 Elche, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Spain
| | - Paloma Alonso-Magdalena
- Instituto de Biología Molecular y Celular (IBMC), Universitas Miguel Hernández, 03202 Elche, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universitas Miguel Hernández, 03202 Elche, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Spain
| | - Ivan Quesada
- Instituto de Biología Molecular y Celular (IBMC), Universitas Miguel Hernández, 03202 Elche, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universitas Miguel Hernández, 03202 Elche, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Spain.
| | - Ángel Nadal
- Instituto de Biología Molecular y Celular (IBMC), Universitas Miguel Hernández, 03202 Elche, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universitas Miguel Hernández, 03202 Elche, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Spain.
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29
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Müller TD, Finan B, Bloom SR, D'Alessio D, Drucker DJ, Flatt PR, Fritsche A, Gribble F, Grill HJ, Habener JF, Holst JJ, Langhans W, Meier JJ, Nauck MA, Perez-Tilve D, Pocai A, Reimann F, Sandoval DA, Schwartz TW, Seeley RJ, Stemmer K, Tang-Christensen M, Woods SC, DiMarchi RD, Tschöp MH. Glucagon-like peptide 1 (GLP-1). Mol Metab 2019; 30:72-130. [PMID: 31767182 PMCID: PMC6812410 DOI: 10.1016/j.molmet.2019.09.010] [Citation(s) in RCA: 1105] [Impact Index Per Article: 184.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 09/10/2019] [Accepted: 09/22/2019] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND The glucagon-like peptide-1 (GLP-1) is a multifaceted hormone with broad pharmacological potential. Among the numerous metabolic effects of GLP-1 are the glucose-dependent stimulation of insulin secretion, decrease of gastric emptying, inhibition of food intake, increase of natriuresis and diuresis, and modulation of rodent β-cell proliferation. GLP-1 also has cardio- and neuroprotective effects, decreases inflammation and apoptosis, and has implications for learning and memory, reward behavior, and palatability. Biochemically modified for enhanced potency and sustained action, GLP-1 receptor agonists are successfully in clinical use for the treatment of type-2 diabetes, and several GLP-1-based pharmacotherapies are in clinical evaluation for the treatment of obesity. SCOPE OF REVIEW In this review, we provide a detailed overview on the multifaceted nature of GLP-1 and its pharmacology and discuss its therapeutic implications on various diseases. MAJOR CONCLUSIONS Since its discovery, GLP-1 has emerged as a pleiotropic hormone with a myriad of metabolic functions that go well beyond its classical identification as an incretin hormone. The numerous beneficial effects of GLP-1 render this hormone an interesting candidate for the development of pharmacotherapies to treat obesity, diabetes, and neurodegenerative disorders.
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Affiliation(s)
- T D Müller
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany; Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, Tübingen, Germany.
| | - B Finan
- Novo Nordisk Research Center Indianapolis, Indianapolis, IN, USA
| | - S R Bloom
- Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK
| | - D D'Alessio
- Division of Endocrinology, Duke University Medical Center, Durham, NC, USA
| | - D J Drucker
- The Department of Medicine, Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, University of Toronto, Ontario, M5G1X5, Canada
| | - P R Flatt
- SAAD Centre for Pharmacy & Diabetes, Ulster University, Coleraine, Northern Ireland, UK
| | - A Fritsche
- German Center for Diabetes Research (DZD), Neuherberg, Germany; Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany; Division of Endocrinology, Diabetology, Vascular Disease, Nephrology and Clinical Chemistry, Department of Internal Medicine, University of Tübingen, Tübingen, Germany
| | - F Gribble
- Metabolic Research Laboratories and Medical Research Council Metabolic Diseases Unit, Wellcome Trust-Medical Research Council, Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - H J Grill
- Institute of Diabetes, Obesity and Metabolism, Department of Psychology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - J F Habener
- Laboratory of Molecular Endocrinology, Massachusetts General Hospital, Harvard University, Boston, MA, USA
| | - J J Holst
- Novo Nordisk Foundation Center for Basic Metabolic Research, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - W Langhans
- Physiology and Behavior Laboratory, ETH Zurich, Schwerzenbach, Switzerland
| | - J J Meier
- Diabetes Division, St Josef Hospital, Ruhr-University Bochum, Bochum, Germany
| | - M A Nauck
- Diabetes Center Bochum-Hattingen, St Josef Hospital (Ruhr-Universität Bochum), Bochum, Germany
| | - D Perez-Tilve
- Department of Internal Medicine, University of Cincinnati-College of Medicine, Cincinnati, OH, USA
| | - A Pocai
- Cardiovascular & ImmunoMetabolism, Janssen Research & Development, Welsh and McKean Roads, Spring House, PA, 19477, USA
| | - F Reimann
- Metabolic Research Laboratories and Medical Research Council Metabolic Diseases Unit, Wellcome Trust-Medical Research Council, Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - D A Sandoval
- Department of Surgery, University of Michigan Medical School, Ann Arbor, MI, USA
| | - T W Schwartz
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, DL-2200, Copenhagen, Denmark; Department of Biomedical Sciences, University of Copenhagen, DK-2200, Copenhagen, Denmark
| | - R J Seeley
- Department of Surgery, University of Michigan Medical School, Ann Arbor, MI, USA
| | - K Stemmer
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - M Tang-Christensen
- Obesity Research, Global Drug Discovery, Novo Nordisk A/S, Måløv, Denmark
| | - S C Woods
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, OH, USA
| | - R D DiMarchi
- Novo Nordisk Research Center Indianapolis, Indianapolis, IN, USA; Department of Chemistry, Indiana University, Bloomington, IN, USA
| | - M H Tschöp
- German Center for Diabetes Research (DZD), Neuherberg, Germany; Division of Metabolic Diseases, Department of Medicine, Technische Universität München, Munich, Germany; Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
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Jarvela TS, Shakya M, Bachor T, White A, Low MJ, Lindberg I. Reduced Stability and pH-Dependent Activity of a Common Obesity-Linked PCSK1 Polymorphism, N221D. Endocrinology 2019; 160:2630-2645. [PMID: 31504391 PMCID: PMC6892424 DOI: 10.1210/en.2019-00418] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 08/26/2019] [Indexed: 02/06/2023]
Abstract
Common mutations in the human prohormone convertase (PC)1/3 gene (PCKSI) are linked to increased risk of obesity. Previous work has shown that the rs6232 single-nucleotide polymorphism (N221D) results in slightly decreased activity, although whether this decrease underlies obesity risk is not clear. We observed significantly decreased activity of the N221D PC1/3 enzyme at the pH of the trans-Golgi network; at this pH, the mutant enzyme was less stable than wild-type enzyme. Recombinant N221D PC1/3 also showed enhanced susceptibility to heat stress. Enhanced susceptibility to tunicamycin-induced endoplasmic reticulum stress was observed in AtT-20/PC2 cell clones in which murine PC1/3 was replaced by human N221D PC1/3, as compared with wild-type human PC1/3. However, N221D PC1/3-expressing AtT-20/PC2 clones processed proopiomelanocortin to α-MSH similarly to wild-type PC1/3. We also generated a CRISPR-edited mouse line expressing the N221D mutation in the PCKSI gene. When homozygous N221D mice were fed either a standard or a high-fat diet, we found no increase in body weight compared with their wild-type sibling controls. Sexual dimorphism was observed in pituitary ACTH for both genotypes, with females exhibiting lower levels of pituitary ACTH. In contrast, hypothalamic α-MSH content for both genotypes was higher in females compared with males. Hypothalamic corticotropin-like intermediate peptide content was higher in wild-type females compared with wild-type, but not N221D, males. Taken together, these data suggest that the increased obesity risk linked to the N221D allele in humans may be due in part to PC1/3-induced loss of resilience to stressors rather than strictly to decreased enzymatic activity on peptide precursors.
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Affiliation(s)
- Timothy S Jarvela
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Surbhi
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Manita Shakya
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Tomas Bachor
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Anne White
- Division of Diabetes, Endocrinology and Gastroenterology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Malcolm J Low
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Iris Lindberg
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland
- Correspondence: Iris Lindberg, PhD, Department of Anatomy and Neurobiology, University of Maryland School of Medicine, 20 Penn Street, Room S267, Baltimore, Maryland 21210. E-mail:
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Culture in 10% O 2 enhances the production of active hormones in neuro-endocrine cells by up-regulating the expression of processing enzymes. Biochem J 2019; 476:827-842. [PMID: 30787050 DOI: 10.1042/bcj20180832] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 02/17/2019] [Accepted: 02/19/2019] [Indexed: 12/22/2022]
Abstract
To closely mimic physiological conditions, low oxygen cultures have been employed in stem cell and cancer research. Although in vivo oxygen concentrations in tissues are often much lower than ambient 21% O2 (ranging from 3.6 to 12.8% O2), most cell cultures are maintained at 21% O2 To clarify the effects of the O2 culture concentration on the regulated secretion of peptide hormones in neuro-endocrine cells, we examined the changes in the storage and release of peptide hormones in neuro-endocrine cell lines and endocrine tissues cultured in a relatively lower O2 concentration. In both AtT-20 cells derived from the mouse anterior pituitary and freshly prepared mouse pituitaries cultured in 10% O2 for 24 h, the storage and regulated secretion of the mature peptide hormone adrenocorticotropic hormone were significantly increased compared with those in cells and pituitaries cultured in ambient 21% O2, whereas its precursor proopiomelanocortin was not increased in the cells and tissues after being cultured in 10% O2 Simultaneously, the prohormone-processing enzymes PC1/3 and carboxypeptidase E were up-regulated in cells cultured in 10% O2, thus facilitating the conversion of prohormones to their active form. Similarly, culturing the mouse β-cell line MIN6 and islet tissue in 10% O2 also significantly increased the conversion of proinsulin into mature insulin, which was secreted in a regulated manner. These results suggest that culture under 10% O2 is more optimal for endocrine tissues/cells to efficiently generate and secrete active peptide hormones than ambient 21% O2.
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Teitelman G. Heterogeneous Expression of Proinsulin Processing Enzymes in Beta Cells of Non-diabetic and Type 2 Diabetic Humans. J Histochem Cytochem 2019; 67:385-400. [PMID: 30759032 DOI: 10.1369/0022155419831641] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Although there is evidence indicating transcriptional and functional heterogeneity in human beta cells, it is unclear whether this heterogeneity extends to the expression level of the enzymes that process proinsulin to insulin in beta cells. To address this question, the expression levels of prohormone convertases (PC) 1/3, proprotein convertase 2 (PC2), and carboxypeptidase E (CPE) were determined in immune-stained sections of human pancreas. In non-diabetic donors, the level of proprotein convertase 1/3 (PC1/3) expression varied among beta cells of each islet but the average per islet was similar for all islets of each donor. Although the average PC1/3 expression of all islets examined per sample was unique for each pancreas, donors had similar levels of proinsulin/insulin expression. PC2 expression in beta cells showed less pronounced inter- and intraislet variation while CPE levels were fairly constant. The relationship between PC1/3 and PC2 expression levels was variable among different donors. Type 2 diabetes had an uneven effect on the expression levels of all three enzymes as they decrease only in some islets in a section. These findings suggest the presence of intraislet, but not interislet, variation in the expression of the proinsulin processing enzymes in non-diabetic subjects and a heterogeneous effect of type 2 diabetes on enzyme expression in islets.
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Affiliation(s)
- Gladys Teitelman
- Department of Cell Biology, SUNY Downstate Medical Center, Brooklyn, New York
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Harno E, Gali Ramamoorthy T, Coll AP, White A. POMC: The Physiological Power of Hormone Processing. Physiol Rev 2019; 98:2381-2430. [PMID: 30156493 DOI: 10.1152/physrev.00024.2017] [Citation(s) in RCA: 141] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Pro-opiomelanocortin (POMC) is the archetypal polypeptide precursor of hormones and neuropeptides. In this review, we examine the variability in the individual peptides produced in different tissues and the impact of the simultaneous presence of their precursors or fragments. We also discuss the problems inherent in accurately measuring which of the precursors and their derived peptides are present in biological samples. We address how not being able to measure all the combinations of precursors and fragments quantitatively has affected our understanding of the pathophysiology associated with POMC processing. To understand how different ratios of peptides arise, we describe the role of the pro-hormone convertases (PCs) and their tissue specificities and consider the cellular processing pathways which enable regulated secretion of different peptides that play crucial roles in integrating a range of vital physiological functions. In the pituitary, correct processing of POMC peptides is essential to maintain the hypothalamic-pituitary-adrenal axis, and this processing can be disrupted in POMC-expressing tumors. In hypothalamic neurons expressing POMC, abnormalities in processing critically impact on the regulation of appetite, energy homeostasis, and body composition. More work is needed to understand whether expression of the POMC gene in a tissue equates to release of bioactive peptides. We suggest that this comprehensive view of POMC processing, with a focus on gaining a better understanding of the combination of peptides produced and their relative bioactivity, is a necessity for all involved in studying this fascinating physiological regulatory phenomenon.
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Affiliation(s)
- Erika Harno
- Division of Diabetes, Endocrinology and Gastrointestinal Sciences, Faculty of Biology, Medicine and Health, University of Manchester , Manchester , United Kingdom ; and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science , Cambridge , United Kingdom
| | - Thanuja Gali Ramamoorthy
- Division of Diabetes, Endocrinology and Gastrointestinal Sciences, Faculty of Biology, Medicine and Health, University of Manchester , Manchester , United Kingdom ; and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science , Cambridge , United Kingdom
| | - Anthony P Coll
- Division of Diabetes, Endocrinology and Gastrointestinal Sciences, Faculty of Biology, Medicine and Health, University of Manchester , Manchester , United Kingdom ; and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science , Cambridge , United Kingdom
| | - Anne White
- Division of Diabetes, Endocrinology and Gastrointestinal Sciences, Faculty of Biology, Medicine and Health, University of Manchester , Manchester , United Kingdom ; and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science , Cambridge , United Kingdom
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Rivero-Gutierrez B, Haller A, Holland J, Yates E, Khrisna R, Habegger K, Dimarchi R, D'Alessio D, Perez-Tilve D. Deletion of the glucagon receptor gene before and after experimental diabetes reveals differential protection from hyperglycemia. Mol Metab 2018; 17:28-38. [PMID: 30170980 PMCID: PMC6197675 DOI: 10.1016/j.molmet.2018.07.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 07/26/2018] [Accepted: 07/31/2018] [Indexed: 12/16/2022] Open
Abstract
OBJECTIVE Mice with congenital loss of the glucagon receptor gene (Gcgr-/- mice) remain normoglycemic in insulinopenic conditions, suggesting that unopposed glucagon action is the driving force for hyperglycemia in Type-1 Diabetes Mellitus (T1DM). However, chronic loss of GCGR results in a neomorphic phenotype that includes hormonal signals with hypoglycemic activity. We combined temporally-controlled GCGR deletion with pharmacological treatments to dissect the direct contribution of GCGR signaling to glucose control in a common mouse model of T1DM. METHODS We induced experimental T1DM by injecting the beta-cell cytotoxin streptozotocin (STZ) in mice with congenital or temporally-controlled Gcgr loss-of-function using tamoxifen (TMX). RESULTS Disruption of Gcgr expression, using either an inducible approach in adult mice or animals with congenital knockout, abolished the response to a long-acting Gcgr agonist. Mice with either developmental Gcgr disruption or inducible deletion several weeks before STZ treatment maintained normoglycemia. However, mice with inducible knockout of the Gcgr one week after the onset of STZ diabetes had only partial correction of hyperglycemia, an effect that was reversed by GLP-1 receptor blockade. Mice with Gcgr deletion for either 2 or 6 weeks had similar patterns of gene expression, although the changes were generally larger with longer GCGR knockout. CONCLUSIONS These findings demonstrate that the effects of glucagon to mitigate diabetic hyperglycemia are not through acute signaling but require compensations that take weeks to develop.
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Affiliation(s)
- Belen Rivero-Gutierrez
- Department of Internal Medicine, University of Cincinnati, 2180 E. Galbraith Rd, Cincinnati, OH, USA
| | - April Haller
- Department of Internal Medicine, University of Cincinnati, 2180 E. Galbraith Rd, Cincinnati, OH, USA
| | - Jenna Holland
- Department of Internal Medicine, University of Cincinnati, 2180 E. Galbraith Rd, Cincinnati, OH, USA
| | - Emily Yates
- Department of Internal Medicine, University of Cincinnati, 2180 E. Galbraith Rd, Cincinnati, OH, USA
| | - Radha Khrisna
- Department of Medicine, Duke University School of Medicine, NC, USA
| | - Kirk Habegger
- Comprehensive Diabetes Center and Department of Medicine - Endocrinology, Diabetes & and Metabolism, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Richard Dimarchi
- Novo Nordisk Research Center Indianapolis, Indianapolis, IN, USA; Department of Chemistry, Indiana University, Bloomington, IN, USA
| | - David D'Alessio
- Department of Medicine, Duke University School of Medicine, NC, USA
| | - Diego Perez-Tilve
- Department of Internal Medicine, University of Cincinnati, 2180 E. Galbraith Rd, Cincinnati, OH, USA.
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Chen YC, Taylor AJ, Verchere CB. Islet prohormone processing in health and disease. Diabetes Obes Metab 2018; 20 Suppl 2:64-76. [PMID: 30230179 DOI: 10.1111/dom.13401] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 05/30/2018] [Accepted: 05/30/2018] [Indexed: 12/15/2022]
Abstract
Biosynthesis of peptide hormones by pancreatic islet endocrine cells is a tightly orchestrated process that is critical for metabolic homeostasis. Like neuroendocrine peptides, insulin and other islet hormones are first synthesized as larger precursor molecules that are processed to their mature secreted products through a series of proteolytic cleavages, mediated by the prohormone convertases Pc1/3 and Pc2, and carboxypeptidase E. Additional posttranslational modifications including C-terminal amidation of the β-cell peptide islet amyloid polypeptide (IAPP) by peptidyl-glycine α-amidating monooxygenase (Pam) may also occur. Genome-wide association studies (GWAS) have showed genetic linkage of these processing enzymes to obesity, β-cell dysfunction, and type 2 diabetes (T2D), pointing to their important roles in metabolism and blood glucose regulation. In both type 1 diabetes (T1D) and T2D, and in the face of metabolic or inflammatory stresses, islet prohormone processing may become impaired; indeed elevated proinsulin:insulin (PI:I) ratios are a hallmark of the β-cell dysfunction in T2D. Recent studies suggest that genetic or acquired defects in proIAPP processing may lead to the production and secretion of incompletely processed forms of proIAPP that could contribute to T2D pathogenesis, and additionally that impaired processing of both PI and proIAPP may be characteristic of β-cell dysfunction in T1D. In islet α-cells, the prohormone proglucagon is normally processed to bioactive glucagon by Pc2 but may express Pc1/3 under certain conditions leading to production of GLP-1(7-36NH2 ). A better understanding of how β-cell processing of PI and proIAPP, as well as α-cell processing of proglucagon, are impacted by genetic susceptibility and in the face of diabetogenic stresses, may lead to new therapeutic approaches for improving islet function in diabetes.
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Affiliation(s)
- Yi-Chun Chen
- Department of Surgery, BC Children's Hospital Research Institute and University of British Columbia, Vancouver, British Columbia, Canada
- Department of Pathology and Laboratory Medicine, BC Children's Hospital Research Institute and University of British Columbia, Vancouver, British Columbia, Canada
| | - Austin J Taylor
- Department of Surgery, BC Children's Hospital Research Institute and University of British Columbia, Vancouver, British Columbia, Canada
- Department of Pathology and Laboratory Medicine, BC Children's Hospital Research Institute and University of British Columbia, Vancouver, British Columbia, Canada
| | - C Bruce Verchere
- Department of Surgery, BC Children's Hospital Research Institute and University of British Columbia, Vancouver, British Columbia, Canada
- Department of Pathology and Laboratory Medicine, BC Children's Hospital Research Institute and University of British Columbia, Vancouver, British Columbia, Canada
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36
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Maeda Y, Kudo S, Tsushima K, Sato E, Kubota C, Kayamori A, Bochimoto H, Koga D, Torii S, Gomi H, Watanabe T, Hosaka M. Impaired Processing of Prohormones in Secretogranin III-Null Mice Causes Maladaptation to an Inadequate Diet and Stress. Endocrinology 2018; 159:1213-1227. [PMID: 29281094 DOI: 10.1210/en.2017-00636] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Accepted: 12/15/2017] [Indexed: 11/19/2022]
Abstract
Secretogranin III (SgIII), a member of the granin family, binds both to another granin, chromogranin A (CgA), and to a cholesterol-rich membrane that is destined for secretory granules (SGs). The knockdown of SgIII in adrenocorticotropic hormone (ACTH)-producing AtT-20 cells largely impairs the regulated secretion of CgA and ACTH. To clarify the physiological roles of SgIII in vivo, we analyzed hormone secretion and SG biogenesis in newly established SgIII-knockout (KO) mice. Although the SgIII-KO mice were viable and fertile and exhibited no overt abnormalities under ordinary rearing conditions, a high-fat/high-sucrose diet caused pronounced obesity in the mice. Furthermore, in the SgIII-KO mice compared with wild-type (WT) mice, the stimulated secretion of active insulin decreased substantially, whereas the storage of proinsulin increased in the islets. The plasma ACTH was also less elevated in the SgIII-KO mice than in the WT mice after chronic restraint stress, whereas the storage level of the precursor proopiomelanocortin in the pituitary gland was somewhat increased. These findings suggest that the lack of SgIII causes maladaptation of endocrine cells to an inadequate diet and stress by impairing the proteolytic conversion of prohormones in SGs, whereas SG biogenesis and the basal secretion of peptide hormones under ordinary conditions are ensured by the compensatory upregulation of other residual granins or factors.
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Affiliation(s)
- Yoshinori Maeda
- Department of Biotechnology, Laboratory of Molecular Life Sciences, Akita Prefectural University, Akita, Japan
| | - Saki Kudo
- Department of Biotechnology, Laboratory of Molecular Life Sciences, Akita Prefectural University, Akita, Japan
| | - Ken Tsushima
- Department of Biotechnology, Laboratory of Molecular Life Sciences, Akita Prefectural University, Akita, Japan
| | - Eri Sato
- Department of Biotechnology, Laboratory of Molecular Life Sciences, Akita Prefectural University, Akita, Japan
| | - Chisato Kubota
- Biosignal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
- Research Fellow of Japan Society for the Promotion of Science, Tokyo, Japan
| | - Aika Kayamori
- Department of Biotechnology, Laboratory of Molecular Life Sciences, Akita Prefectural University, Akita, Japan
| | - Hiroki Bochimoto
- Health Care Administration Center, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan
| | - Daisuke Koga
- Department of Microscopic Anatomy and Cell Biology, Asahikawa Medical University, Asahikawa, Japan
| | - Seiji Torii
- Biosignal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Hiroshi Gomi
- Department of Veterinary Anatomy, College of Bioresource Sciences, Nihon University, Fujisawa, Japan
| | - Tsuyoshi Watanabe
- Department of Microscopic Anatomy and Cell Biology, Asahikawa Medical University, Asahikawa, Japan
| | - Masahiro Hosaka
- Department of Biotechnology, Laboratory of Molecular Life Sciences, Akita Prefectural University, Akita, Japan
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Suzuki H, Yamamoto T. Localization of amylin-like immunoreactivity in the striped velvet gecko pancreas. Anat Histol Embryol 2018; 47:159-166. [PMID: 29315753 DOI: 10.1111/ahe.12337] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Accepted: 11/22/2017] [Indexed: 12/23/2022]
Abstract
Immunohistochemical techniques were employed to investigate the distribution of amylin-like immunoreactive cells in the pancreas of gecko Homopholis fasciata. Four types of endocrine cells were distinguished: insulin immunoreactive (B cells), pancreatic polypeptide immunoreactive (PP cells), glucagon and pancreatic polypeptide immunoreactive (A/PP cells) and somatostatin immunoreactive cells (D cells). Pancreatic islets contained B, A/PP and D cells, whereas extrainsular regions contained B, D and PP cells. In the pancreatic islets, amylin-like immunoreactive cells corresponded to B cells, but not to A/PP or D cells. In the extrainsular regions, amylin-like immunoreactive cells corresponded to either B or PP cells. Amylin secreted from intrainsular B cells may regulate pancreatic hormone secretion in an autocrine and/or a paracrine fashion. On the other hand, amylin secreted from extrainsular PP and B cells, and/or intrainsular B cells may participate in the modulation of calcium homoeostasis in an endocrine fashion.
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Affiliation(s)
- H Suzuki
- Brain Functions and Neuroscience Unit, Department of Oral Science, Graduate School of Dentistry, Kanagawa Dental University, Yokosuka, Japan.,Department of Biology, University of Teacher Education Fukuoka, Munakata, Fukuoka, Japan
| | - T Yamamoto
- Brain Functions and Neuroscience Unit, Department of Oral Science, Graduate School of Dentistry, Kanagawa Dental University, Yokosuka, Japan
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Hayashi Y, Seino Y. Regulation of amino acid metabolism and α-cell proliferation by glucagon. J Diabetes Investig 2018; 9:464-472. [PMID: 29314731 PMCID: PMC5934249 DOI: 10.1111/jdi.12797] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 12/21/2017] [Indexed: 12/25/2022] Open
Abstract
Both glucagon and glucagon-like peptide-1 (GLP-1) are produced from proglucagon through proteolytic cleavage. Blocking glucagon action increases the circulating levels of glucagon and GLP-1, reduces the blood glucose level, and induces the proliferation of islet α-cells. Glucagon blockade also suppresses hepatic amino acid catabolism and increases the serum amino acid level. In animal models defective in both glucagon and GLP-1, the blood glucose level is not reduced, indicating that GLP-1 is required for glucagon blockade to reduce the blood glucose level. In contrast, hyperplasia of α-cells and hyperaminoacidemia are observed in such animal models, indicating that GLP-1 is not required for the regulation of α-cell proliferation or amino acid metabolism. These findings suggest that the regulation of amino acid metabolism is a more important specific physiological role of glucagon than the regulation of glucose metabolism. Although the effects of glucagon deficiency on glucose metabolism are compensated by the suppression of insulin secretion, the effects on amino acid metabolism are not. Recently, data showing a feedback regulatory mechanism between the liver and islet α-cells, which is mediated by glucagon and amino acids, are accumulating. However, a number of questions on the mechanism of this regulation remain to be addressed. The profile of glucagon as a regulator of amino acid metabolism must be carefully considered for glucagon blockade to be applied therapeutically in the treatment of patients with diabetes.
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Affiliation(s)
- Yoshitaka Hayashi
- Division of Stress Adaptation and ProtectionResearch Institute of Environmental MedicineNagoyaJapan
| | - Yusuke Seino
- Department of Endocrinology and DiabetesNagoya University Graduate School of MedicineNagoya UniversityNagoyaJapan
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Al Rifai O, Chow J, Lacombe J, Julien C, Faubert D, Susan-Resiga D, Essalmani R, Creemers JW, Seidah NG, Ferron M. Proprotein convertase furin regulates osteocalcin and bone endocrine function. J Clin Invest 2017; 127:4104-4117. [PMID: 28972540 DOI: 10.1172/jci93437] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 08/15/2017] [Indexed: 12/12/2022] Open
Abstract
Osteocalcin (OCN) is an osteoblast-derived hormone that increases energy expenditure, insulin sensitivity, insulin secretion, and glucose tolerance. The cDNA sequence of OCN predicts that, like many other peptide hormones, OCN is first synthesized as a prohormone (pro-OCN). The importance of pro-OCN maturation in regulating OCN and the identity of the endopeptidase responsible for pro-OCN cleavage in osteoblasts are still unknown. Here, we show that the proprotein convertase furin is responsible for pro-OCN maturation in vitro and in vivo. Using pharmacological and genetic experiments, we also determined that furin-mediated pro-OCN cleavage occurred independently of its γ-carboxylation, a posttranslational modification that is known to hamper OCN endocrine action. However, because pro-OCN is not efficiently decarboxylated and activated during bone resorption, inactivation of furin in osteoblasts in mice resulted in decreased circulating levels of undercarboxylated OCN, impaired glucose tolerance, and reduced energy expenditure. Furthermore, we show that Furin deletion in osteoblasts reduced appetite, a function not modulated by OCN, thus suggesting that osteoblasts may secrete additional hormones that regulate different aspects of energy metabolism. Accordingly, the metabolic defects of the mice lacking furin in osteoblasts became more apparent under pair-feeding conditions. These findings identify furin as an important regulator of bone endocrine function.
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Affiliation(s)
- Omar Al Rifai
- Integrative and Molecular Physiology Research Unit, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, Québec, Canada.,Molecular Biology Programs of the Faculty of Medicine, Université de Montréal, Québec, Canada
| | - Jacqueline Chow
- Integrative and Molecular Physiology Research Unit, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, Québec, Canada
| | - Julie Lacombe
- Integrative and Molecular Physiology Research Unit, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, Québec, Canada
| | - Catherine Julien
- Integrative and Molecular Physiology Research Unit, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, Québec, Canada
| | | | | | - Rachid Essalmani
- Biochemical Neuroendocrinology Research Unit, IRCM, Québec, Canada
| | | | - Nabil G Seidah
- Biochemical Neuroendocrinology Research Unit, IRCM, Québec, Canada.,Department of Medicine, Université de Montréal, Québec, Canada.,Division of Experimental Medicine, McGill University, Montréal, Québec, Canada
| | - Mathieu Ferron
- Integrative and Molecular Physiology Research Unit, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, Québec, Canada.,Molecular Biology Programs of the Faculty of Medicine, Université de Montréal, Québec, Canada.,Department of Medicine, Université de Montréal, Québec, Canada.,Division of Experimental Medicine, McGill University, Montréal, Québec, Canada
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40
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Winters A, Ramos-Molina B, Jarvela TS, Yerges-Armstrong L, Pollin TI, Lindberg I. Functional analysis of PCSK2 coding variants: A founder effect in the Old Order Amish population. Diabetes Res Clin Pract 2017; 131:82-90. [PMID: 28719828 PMCID: PMC5572827 DOI: 10.1016/j.diabres.2017.06.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 06/27/2017] [Accepted: 06/27/2017] [Indexed: 02/06/2023]
Abstract
AIMS In humans, noncoding variants of PCSK2, the gene encoding prohormone convertase 2 (PC2), have been previously associated with risk for and age of onset of type 2 diabetes (T2D). The aims of this study were to identify coding variants in PCSK2; to determine their possible association with glucose handling; and to determine functional outcomes for coding variants in biochemical studies. METHODS Exome-wide genotyping was performed on 1725 Old Order Amish (OOA) subjects. PCSK2 coding variants were tested for association with diabetes-related phenotypes. In vitro analyses using transfected human PC2-encoding constructs were performed to determine the impact of each mutation on PC2 activity. RESULTS We identified 10 rare missense coding variants in PCSK2 in various genomic databases. R430W (rs200711626) is greatly enriched in the OOA population (MAF 4.3%). This variant is almost twice as common (MAF 7.4%) in OOA individuals with T2D as in OOA individuals with normal or with normal/impaired glucose tolerance (MAF 3.9% and 2.9%, respectively; p=0.25 and p=0.10). In vitro experiments revealed a broadening of the pH optimum for the R430W variant, which may result in increased activity against PCSK2 substrates. CONCLUSIONS Although the association of the R430W variation with T2D in the OOA population did not reach significance, based upon the broadened pH profile of R430W PC2, we speculate that the presence of this substitution may result in altered processing of PCSK2 substrates, ultimately leading to increased conversion to diabetes.
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Affiliation(s)
- Alexandra Winters
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, United States; Division of Endocrinology, Diabetes, and Nutrition, University of Maryland School of Medicine, Baltimore, MD 21201, United States
| | - Bruno Ramos-Molina
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, United States
| | - Timothy S Jarvela
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, United States
| | - Laura Yerges-Armstrong
- Division of Endocrinology, Diabetes, and Nutrition, University of Maryland School of Medicine, Baltimore, MD 21201, United States
| | - Toni I Pollin
- Division of Endocrinology, Diabetes, and Nutrition, University of Maryland School of Medicine, Baltimore, MD 21201, United States
| | - Iris Lindberg
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, United States.
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Courtade JA, Wang EY, Yen P, Dai DL, Soukhatcheva G, Orban PC, Verchere CB. Loss of prohormone convertase 2 promotes beta cell dysfunction in a rodent transplant model expressing human pro-islet amyloid polypeptide. Diabetologia 2017; 60:453-463. [PMID: 27999871 DOI: 10.1007/s00125-016-4174-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 10/03/2016] [Indexed: 01/09/2023]
Abstract
AIMS/HYPOTHESIS A contributor to beta cell failure in type 2 diabetes and islet transplants is amyloid formation by aggregation of the beta cell peptide, islet amyloid polypeptide (IAPP). Similar to the proinsulin processing pathway that generates insulin, IAPP is derived from a prohormone precursor, proIAPP, which requires cleavage by prohormone convertase (PC) 1/3 and PC2 in rodent pancreatic beta cells. We hypothesised that loss of PC2 would promote beta cell death and dysfunction in a rodent model of human beta cell proIAPP overexpression. METHODS We generated an islet transplant model wherein immune-deficient mouse models of diabetes received islets expressing amyloidogenic human proIAPP and lacking PC2, leading to restoration of normoglycaemia accompanied by increased secretion of human proIAPP. Blood glucose levels were analysed for up to 16 weeks in transplant recipients and grafts were assessed for islet amyloid and beta cell number and death. RESULTS Hyperglycaemia (blood glucose >16.9 mmol/l) returned in 94% of recipients of islets expressing human proIAPP and lacking PC2, whereas recipients of islets that express human proIAPP and normal PC2 levels remained normoglycaemic for at least 16 weeks. Islet graft failure was accompanied by a ∼20% reduction in insulin-positive cells, yet the degree of amyloid deposition and beta cell apoptosis was similar to those of controls expressing human proIAPP with functional PC2 levels. CONCLUSIONS/INTERPRETATION PC2 deficiency in transplanted mouse islets expressing human proIAPP promotes beta cell loss and graft failure. Our data suggest that impaired NH2-terminal processing and increased secretion of human proIAPP promote beta cell failure.
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Affiliation(s)
- Jaques A Courtade
- Research Institute, BC Children's Hospital, 950 West 28th Avenue, Vancouver, BC, V5Z 4H4, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Evan Y Wang
- Research Institute, BC Children's Hospital, 950 West 28th Avenue, Vancouver, BC, V5Z 4H4, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Paul Yen
- Research Institute, BC Children's Hospital, 950 West 28th Avenue, Vancouver, BC, V5Z 4H4, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Derek L Dai
- Research Institute, BC Children's Hospital, 950 West 28th Avenue, Vancouver, BC, V5Z 4H4, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Galina Soukhatcheva
- Research Institute, BC Children's Hospital, 950 West 28th Avenue, Vancouver, BC, V5Z 4H4, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Paul C Orban
- Research Institute, BC Children's Hospital, 950 West 28th Avenue, Vancouver, BC, V5Z 4H4, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - C Bruce Verchere
- Research Institute, BC Children's Hospital, 950 West 28th Avenue, Vancouver, BC, V5Z 4H4, Canada.
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.
- Department of Surgery, University of British Columbia, Vancouver, BC, Canada.
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Nillni EA. The metabolic sensor Sirt1 and the hypothalamus: Interplay between peptide hormones and pro-hormone convertases. Mol Cell Endocrinol 2016; 438:77-88. [PMID: 27614022 DOI: 10.1016/j.mce.2016.09.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 09/05/2016] [Accepted: 09/05/2016] [Indexed: 01/11/2023]
Abstract
The last decade had witnessed a tremendous progress in our understanding of the causes of metabolic diseases including obesity. Among the contributing factors regulating energy balance are nutrient sensors such as sirtuins. Sirtuin1 (Sirt1), a NAD + - dependent deacetylase is affected by diet, environmental stress, and also plays a critical role in metabolic health by deacetylating proteins in many tissues, including liver, muscle, adipose tissue, heart, endothelium, and in the complexity of the hypothalamus. Because of its dependence on NAD+, Sirt1 also functions as a nutrient/redox sensor, and new novel data show a function of this enzyme in the maturation of hypothalamic peptide hormones controlling energy balance either through regulation of specific nuclear transcription factors or by regulating specific pro-hormone convertases (PCs) involved in the post-translational processing of pro-hormones. The post-translational processing mechanism of pro-hormones is critical in the pathogenesis of obesity as recently shown that metabolic and physiological triggers affect the biosynthesis and processing of many peptides hormones. Specific regulation of pro-hormone processing is likely another key step where final amounts of bioactive peptides can be tightly regulated. Different factors stimulate or inhibit pro-hormones biosynthesis in concert with an increase in the PCs involved in the maturation of bioactive hormones. Adding more complexity to the system, the new studies describe here suggest that Sirt1 could also regulate the fate of peptide hormone biosynthesis. The present review summarizes the recent progress in hypothalamic SIRT1 research with a particular emphasis on the tissue-specific control of neuropeptide hormone maturation. The series of studies done in mouse and rat models strongly advocate for the first time that a deacetylating enzyme could be a regulator in the maturation of peptide hormones and their processing enzymes. These discoveries are the culmination of the first in-depth understanding of the metabolic role of Sirt1 in the brain. It suggests that Sirt1 behaves differently in the brain than in organs such as the liver and pancreas, where the enzyme has been more commonly studied.
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Affiliation(s)
- Eduardo A Nillni
- The Warren Alpert Medical School, Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI 02912, USA.
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Long-Term GABA Administration Induces Alpha Cell-Mediated Beta-like Cell Neogenesis. Cell 2016; 168:73-85.e11. [PMID: 27916274 DOI: 10.1016/j.cell.2016.11.002] [Citation(s) in RCA: 231] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 08/04/2016] [Accepted: 10/31/2016] [Indexed: 12/11/2022]
Abstract
The recent discovery that genetically modified α cells can regenerate and convert into β-like cells in vivo holds great promise for diabetes research. However, to eventually translate these findings to human, it is crucial to discover compounds with similar activities. Herein, we report the identification of GABA as an inducer of α-to-β-like cell conversion in vivo. This conversion induces α cell replacement mechanisms through the mobilization of duct-lining precursor cells that adopt an α cell identity prior to being converted into β-like cells, solely upon sustained GABA exposure. Importantly, these neo-generated β-like cells are functional and can repeatedly reverse chemically induced diabetes in vivo. Similarly, the treatment of transplanted human islets with GABA results in a loss of α cells and a concomitant increase in β-like cell counts, suggestive of α-to-β-like cell conversion processes also in humans. This newly discovered GABA-induced α cell-mediated β-like cell neogenesis could therefore represent an unprecedented hope toward improved therapies for diabetes.
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Rhyu J, Yu R. Mahvash disease: an autosomal recessive hereditary pancreatic neuroendocrine tumor syndrome. INTERNATIONAL JOURNAL OF ENDOCRINE ONCOLOGY 2016. [DOI: 10.2217/ije-2016-0005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
- Jane Rhyu
- Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Division of Endocrinology, Cedars-Sinai Medical Center, Los Angeles, CA, USA; current address Department of Medicine, UCLA David Geffen School of Medicine, Los Angeles, CA, USA,
| | - Run Yu
- Division of Endocrinology, Cedars-Sinai Medical Center, Los Angeles, CA, USA; current address Department of Medicine, UCLA David Geffen School of Medicine, Los Angeles, CA, USA,
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Iida A, Seino Y, Fukami A, Maekawa R, Yabe D, Shimizu S, Kinoshita K, Takagi Y, Izumoto T, Ogata H, Ishikawa K, Ozaki N, Tsunekawa S, Hamada Y, Oiso Y, Arima H, Hayashi Y. Endogenous GIP ameliorates impairment of insulin secretion in proglucagon-deficient mice under moderate beta cell damage induced by streptozotocin. Diabetologia 2016; 59:1533-1541. [PMID: 27053237 PMCID: PMC4901104 DOI: 10.1007/s00125-016-3935-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/02/2016] [Indexed: 01/06/2023]
Abstract
AIMS/HYPOTHESIS The action of incretin hormones including glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) is potentiated in animal models defective in glucagon action. It has been reported that such animal models maintain normoglycaemia under streptozotocin (STZ)-induced beta cell damage. However, the role of GIP in regulation of glucose metabolism under a combination of glucagon deficiency and STZ-induced beta cell damage has not been fully explored. METHODS In this study, we investigated glucose metabolism in mice deficient in proglucagon-derived peptides (PGDPs)-namely glucagon gene knockout (GcgKO) mice-administered with STZ. Single high-dose STZ (200 mg/kg, hSTZ) or moderate-dose STZ for five consecutive days (50 mg/kg × 5, mSTZ) was administered to GcgKO mice. The contribution of GIP to glucose metabolism in GcgKO mice was also investigated by experiments employing dipeptidyl peptidase IV (DPP4) inhibitor (DPP4i) or Gcg-Gipr double knockout (DKO) mice. RESULTS GcgKO mice developed severe diabetes by hSTZ administration despite the absence of glucagon. Administration of mSTZ decreased pancreatic insulin content to 18.8 ± 3.4 (%) in GcgKO mice, but ad libitum-fed blood glucose levels did not significantly increase. Glucose-induced insulin secretion was marginally impaired in mSTZ-treated GcgKO mice but was abolished in mSTZ-treated DKO mice. Although GcgKO mice lack GLP-1, treatment with DPP4i potentiated glucose-induced insulin secretion and ameliorated glucose intolerance in mSTZ-treated GcgKO mice, but did not increase beta cell area or significantly reduce apoptotic cells in islets. CONCLUSIONS/INTERPRETATION These results indicate that GIP has the potential to ameliorate glucose intolerance even under STZ-induced beta cell damage by increasing insulin secretion rather than by promoting beta cell survival.
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Affiliation(s)
- Atsushi Iida
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Yusuke Seino
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan.
- Department of Metabolic Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan.
| | - Ayako Fukami
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Ryuya Maekawa
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Daisuke Yabe
- Yutaka Seino Distinguished Center for Diabetes Research, Kansai Electric Power Medical Research Institute, Kobe, Japan
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Shinobu Shimizu
- Yutaka Seino Distinguished Center for Diabetes Research, Kansai Electric Power Medical Research Institute, Kobe, Japan
| | - Keita Kinoshita
- Research Center of Health, Physical Fitness and Sports, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
- Department of Genetics, Division of Stress Adaptation and Recognition, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 4648601, Japan
| | - Yusuke Takagi
- Research Center of Health, Physical Fitness and Sports, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
- Department of Genetics, Division of Stress Adaptation and Recognition, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 4648601, Japan
| | - Takako Izumoto
- Department of Oral and Maxillofacial Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hidetada Ogata
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Kota Ishikawa
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Nobuaki Ozaki
- Research Center of Health, Physical Fitness and Sports, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Shin Tsunekawa
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Yoji Hamada
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
- Department of Metabolic Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yutaka Oiso
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Hiroshi Arima
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Yoshitaka Hayashi
- Department of Genetics, Division of Stress Adaptation and Recognition, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 4648601, Japan.
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Prohormone convertase 2 (PC2) null mice have increased mu opioid receptor levels accompanied by altered morphine-induced antinociception, tolerance and dependence. Neuroscience 2016; 329:318-25. [PMID: 27208618 DOI: 10.1016/j.neuroscience.2016.05.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Revised: 05/11/2016] [Accepted: 05/12/2016] [Indexed: 11/23/2022]
Abstract
Chronic morphine treatment increases the levels of prohormone convertase 2 (PC2) in brain regions involved in nociception, tolerance and dependence. Thus, we tested if PC2 null mice exhibit altered morphine-induced antinociception, tolerance and dependence. PC2 null mice and their wild-type controls were tested for baseline hot plate latency, injected with morphine (1.25-10mg/kg) and tested for antinociception 30min later. For tolerance studies, mice were tested in the hot plate test before and 30min following morphine (5mg/kg) on day 1. Mice then received an additional dose so that the final dose of morphine was 10mg/kg on this day. On days 2-4, mice received additional doses of morphine (20, 40 and 80mg/kg on days 1, 2, 3, and 4, respectively). On day 5, mice were tested in the hot plate test before and 30min following morphine (5mg/kg). For withdrawal studies, mice were treated with the escalating doses of morphine (10, 20, 40 and 80mg/kg) for 4days, implanted with a morphine pellet on day 5 and 3 days later injected with naloxone (1mg/kg) and signs of withdrawal were recorded. Morphine dose-dependently induced antinociception and the magnitude of this response was greater in PC2 null mice. Tolerance to morphine was observed in wild-type mice and this phenomenon was blunted in PC2 null mice. Withdrawal signs were also reduced in PC2 null mice. Immunohistochemical studies showed up-regulation of the mu opioid receptor (MOP) protein expression in the periaqueductal gray area, ventral tegmental area, lateral hypothalamus, medial hypothalamus, nucleus accumbens, and somatosensory cortex in PC2 null mice. Likewise, naloxone specific binding was increased in the brains of these mice compared to their wild-type controls. The results suggest that the PC2-derived peptides may play a functional role in morphine-induced antinociception, tolerance and dependence. Alternatively, lack of opioid peptides led to up-regulation of the MOP and altered morphine-induced antinociception, tolerance and dependence.
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Cawley NX, Li Z, Loh YP. 60 YEARS OF POMC: Biosynthesis, trafficking, and secretion of pro-opiomelanocortin-derived peptides. J Mol Endocrinol 2016; 56:T77-97. [PMID: 26880796 PMCID: PMC4899099 DOI: 10.1530/jme-15-0323] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 02/15/2016] [Indexed: 12/15/2022]
Abstract
Pro-opiomelanocortin (POMC) is a prohormone that encodes multiple smaller peptide hormones within its structure. These peptide hormones can be generated by cleavage of POMC at basic residue cleavage sites by prohormone-converting enzymes in the regulated secretory pathway (RSP) of POMC-synthesizing endocrine cells and neurons. The peptides are stored inside the cells in dense-core secretory granules until released in a stimulus-dependent manner. The complexity of the regulation of the biosynthesis, trafficking, and secretion of POMC and its peptides reflects an impressive level of control over many factors involved in the ultimate role of POMC-expressing cells, that is, to produce a range of different biologically active peptide hormones ready for action when signaled by the body. From the discovery of POMC as the precursor to adrenocorticotropic hormone (ACTH) and β-lipotropin in the late 1970s to our current knowledge, the understanding of POMC physiology remains a monumental body of work that has provided insight into many aspects of molecular endocrinology. In this article, we describe the intracellular trafficking of POMC in endocrine cells, its sorting into dense-core secretory granules and transport of these granules to the RSP. Additionally, we review the enzymes involved in the maturation of POMC to its various peptides and the mechanisms involved in the differential processing of POMC in different cell types. Finally, we highlight studies pertaining to the regulation of ACTH secretion in the anterior and intermediate pituitary and POMC neurons of the hypothalamus.
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Affiliation(s)
- Niamh X Cawley
- Section on Cellular NeurobiologyEunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Zhaojin Li
- Section on Cellular NeurobiologyEunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Y Peng Loh
- Section on Cellular NeurobiologyEunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
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Chrétien M, Mbikay M. 60 YEARS OF POMC: From the prohormone theory to pro-opiomelanocortin and to proprotein convertases (PCSK1 to PCSK9). J Mol Endocrinol 2016; 56:T49-62. [PMID: 26762158 DOI: 10.1530/jme-15-0261] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Accepted: 01/04/2016] [Indexed: 12/12/2022]
Abstract
Pro-opiomelanocortin (POMC), is a polyprotein expressed in the pituitary and the brain where it is proteolytically processed into peptide hormones and neuropeptides with distinct biological activities. It is the prototype of multipotent prohormones. The prohormone theory was first suggested in 1967 when Chrétien and Li discovered γ-lipotropin and observed that (i) it was part of β-lipotropin (β-LPH), a larger polypeptide characterized 2 years earlier and (ii) its C-terminus was β-melanocyte-stimulating hormone (β-MSH). This discovery led them to propose that the lipotropins might be related biosynthetically to the biologically active β-MSH in a precursor to end product relationship. The theory was widely confirmed in subsequent years. As we celebrate the 50th anniversary of the sequencing of β-LPH, we reflect over the lessons learned from the sequencing of those proteins; we explain their extension to the larger POMC precursor; we examine how the theory of precursor endoproteolysis they inspired became relevant for vast fields in biology; and how it led, after a long and arduous search, to the novel proteolytic enzymes called proprotein convertases. This family of nine enzymes plays multifaceted functions in growth, development, metabolism, endocrine, and brain functions. Their genetics has provided many insights into health and disease. Their therapeutic targeting is foreseeable in the near future. Thus, what started five decades ago as a theory based on POMC fragments, has opened up novel and productive avenues of biological and medical research, including, for our own current interest, a highly intriguing hypocholesterolemic Gln152His PCSK9 mutation in French-Canadian families.
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Affiliation(s)
- Michel Chrétien
- Laboratory of Functional EndoproteolysisClinical Research Institute of Montreal, Montreal, Quebec, Canada
| | - Majambu Mbikay
- Laboratory of Functional EndoproteolysisClinical Research Institute of Montreal, Montreal, Quebec, Canada
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Damond N, Thorel F, Moyers JS, Charron MJ, Vuguin PM, Powers AC, Herrera PL. Blockade of glucagon signaling prevents or reverses diabetes onset only if residual β-cells persist. eLife 2016; 5. [PMID: 27092792 PMCID: PMC4871705 DOI: 10.7554/elife.13828] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 04/07/2016] [Indexed: 12/15/2022] Open
Abstract
Glucagon secretion dysregulation in diabetes fosters hyperglycemia. Recent studies report that mice lacking glucagon receptor (Gcgr-/-) do not develop diabetes following streptozotocin (STZ)-mediated ablation of insulin-producing β-cells. Here, we show that diabetes prevention in STZ-treated Gcgr-/- animals requires remnant insulin action originating from spared residual β-cells: these mice indeed became hyperglycemic after insulin receptor blockade. Accordingly, Gcgr-/- mice developed hyperglycemia after induction of a more complete, diphtheria toxin (DT)-induced β-cell loss, a situation of near-absolute insulin deficiency similar to type 1 diabetes. In addition, glucagon deficiency did not impair the natural capacity of α-cells to reprogram into insulin production after extreme β-cell loss. α-to-β-cell conversion was improved in Gcgr-/- mice as a consequence of α-cell hyperplasia. Collectively, these results indicate that glucagon antagonism could i) be a useful adjuvant therapy in diabetes only when residual insulin action persists, and ii) help devising future β-cell regeneration therapies relying upon α-cell reprogramming. DOI:http://dx.doi.org/10.7554/eLife.13828.001 After meals, digested food causes sugar to accumulate in the blood. This triggers the release of the hormone insulin from beta cells in the pancreas, which allows liver cells, muscle cells and fat cells to use and store the sugar for energy. Other cells in the pancreas, called alpha cells, release a hormone called glucagon that counteracts the effects of insulin by telling the liver to release sugar into the bloodstream. The balance between the activity of insulin and glucagon keeps blood sugar levels steady. Diabetes results from the body being unable to produce enough insulin or respond to the insulin that is produced, which results in sugar accumulating in the blood. Diabetes also increases the production of glucagon, which further increases blood sugar levels. Recently, some researchers have reported that mice that lack the receptor proteins through which glucagon works do not develop diabetes, even when they are treated with a drug called streptozotocin that wipes out most of their beta cells. This suggests that the high blood sugar levels seen in diabetes result from an excess of glucagon, and not a lack of insulin. Drugs that block the action of glucagon have been found to reduce the symptoms of mild diabetes in mice and are now being tested in humans. However, it is less clear whether this treatment has any benefits in animals with more severe diabetes. Streptozotocin destroys most of a mouse’s beta cells but a significant fraction of them persist, while a different system relying on diphtheria toxin destroys more than 99% of these cells. Damond et al. have now found that treating mice that lack glucagon receptors with diphtheria toxin causes the mice to develop severe diabetes. Mice that lacked glucagon receptors that had been treated with streptozotocin also developed diabetes after they had been treated with an insulin-blocking drug. Further experiments showed that blocking glucagon receptors in typical mice with diabetes reduces blood sugar, but only if there is some insulin left in their bodies. Damond et al. also found that the glucagon receptor-lacking mice have more alpha cells, which have the ability to convert into insulin-producing cells after the widespread destruction of beta cells. Together, the experiments suggest that blocking glucagon could be a useful treatment for diabetes, but only in individuals who still have some insulin-producing cells. Such treatment would help reduce the release of sugar from the liver and increase the production of insulin in converted alpha cells in the pancreas. Damond et al. are now investigating how alpha cells convert into beta cells, with the aim of learning how to make beta cells regenerate more efficiently. DOI:http://dx.doi.org/10.7554/eLife.13828.002
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Affiliation(s)
- Nicolas Damond
- Department of Genetic Medicine and Development of the Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Institute of Genetics and Genomics in Geneva, University of Geneva, Geneva, Switzerland.,Centre facultaire du diabète, University of Geneva, Geneva, Switzerland
| | - Fabrizio Thorel
- Department of Genetic Medicine and Development of the Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Institute of Genetics and Genomics in Geneva, University of Geneva, Geneva, Switzerland.,Centre facultaire du diabète, University of Geneva, Geneva, Switzerland
| | - Julie S Moyers
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, United States
| | - Maureen J Charron
- Departments of Biochemistry, Medicine, and Obstetrics & Gynecology and Women's Health, Albert Einstein College of Medicine, Bronx, United States
| | - Patricia M Vuguin
- Pediatric Endocrinology, Women's and Childrens Health, College of Physicians & Surgeons, Columbia University, New York, United States
| | - Alvin C Powers
- Division of Diabetes, Endocrinology & Metabolism, Department of Medicine, Department of Molecular Physiology, Vanderbilt University, Nashville, United States.,VA Tennessee Valley Healthcare System, Nashville, United States
| | - Pedro L Herrera
- Department of Genetic Medicine and Development of the Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Institute of Genetics and Genomics in Geneva, University of Geneva, Geneva, Switzerland.,Centre facultaire du diabète, University of Geneva, Geneva, Switzerland
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50
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Mojibian M, Glavas MM, Kieffer TJ. Engineering the gut for insulin replacement to treat diabetes. J Diabetes Investig 2016; 7 Suppl 1:87-93. [PMID: 27186362 PMCID: PMC4854511 DOI: 10.1111/jdi.12479] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Accepted: 01/06/2016] [Indexed: 12/11/2022] Open
Abstract
The gut epithelium's large surface area, its direct exposure to ingested nutrients, its vast stem cell population and its immunotolerogenic environment make it an excellent candidate for therapeutic cells to treat diabetes. Thus, several attempts have been made to coax immature gut cells to differentiate into insulin-producing cells by altering the expression patterns of specific transcription factors. Furthermore, because of similarities in enteroendocrine and pancreatic endocrine cell differentiation pathways, other approaches have used genetically engineered enteroendocrine cells to produce insulin in addition to their endogenous secreted hormones. Several studies support the utility of both of these approaches for the treatment of diabetes. Converting a patient's own gut cells into meal-regulated insulin factories in a safe and immunotolerogenic environment is an attractive approach to treat and potentially cure diabetes. Here, we review work on these approaches and indicate where we feel further advancements are required.
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Affiliation(s)
- Majid Mojibian
- Laboratory of Molecular and Cellular Medicine Department of Cellular and Physiological Sciences Life Sciences Institute University of British Columbia Vancouver British Columbia Canada
| | - Maria M Glavas
- Laboratory of Molecular and Cellular Medicine Department of Cellular and Physiological Sciences Life Sciences Institute University of British Columbia Vancouver British Columbia Canada
| | - Timothy J Kieffer
- Laboratory of Molecular and Cellular Medicine Department of Cellular and Physiological Sciences Life Sciences Institute University of British Columbia Vancouver British Columbia Canada
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