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Manhas N. Computational Model of Complex Calcium Dynamics: Store Operated Ca 2+ Channels and Mitochondrial Associated Membranes in Pancreatic Acinar Cells. Cell Biochem Biophys 2025; 83:519-535. [PMID: 39266873 DOI: 10.1007/s12013-024-01484-6] [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] [Accepted: 08/09/2024] [Indexed: 09/14/2024]
Abstract
This proposed model explores the intricate Ca2+ dynamics within the pancreatic acinar cells (PACs) by emphasizing the role of store-operated Ca2+ entry (SOCE) and the mitochondrial-associated membranes (MAMs) in the secretory region (apical) of the PACs. Traditionally, Ca2+ releases from the endoplasmic reticulum (ER) via calcium-induced calcium release (CICR). It has been shown to be important in regulating functions such as secretion of digestive enzymes in PACs. However, this model posits that upon the depletion of Ca2+ in the ER, the signaling protein stromal interaction molecule (STIM1) is activated. Activated STIM1, then facilitates the opening of Orai channels, allowing Ca2+ influx through the store-operated calcium channels (SOCCs). The model highlights the complexity of the Ca2+ dynamics, and the importance of SOCE and MAMs in the PACs Ca2+ homeostasis. The numerical and bifurcation analysis illustrate how changes in agonist concentrations can lead to the diverse Ca2+ oscillation patterns, such as thin to broader oscillations, sinusoidal patterns, and baseline fluctuations, driven by the feedback mechanisms involving Ca2+ and inositol 1,4,5 trisphosphate (IP3). This understanding could have broader implications for cellular physiology and the development of therapies targeting Ca2+ signaling pathways.
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Affiliation(s)
- Neeraj Manhas
- Department of Mathematics, National Institute of Technology, Raipur, Chhattisgarh, 492010, India.
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2
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Jacobson K, Ellis-Davies GCR. Abraham Patchornik: The Contemporary Relevance of His Work for Chemistry and Biology. JACS AU 2025; 5:3-16. [PMID: 39886589 PMCID: PMC11775701 DOI: 10.1021/jacsau.4c00779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2024] [Revised: 10/09/2024] [Accepted: 10/09/2024] [Indexed: 02/01/2025]
Abstract
Abraham Patchornik was born in 1926 in Ness Ziona, a town in Palestine founded by his great-grandfather Reuben Lehrer in 1883. He started to study chemistry as an undergraduate at the Hebrew University. However, this was interrupted by the war, and he completed his studies in various locations in West Jerusalem. From 1952 to 1956 Patchornik completed his PhD at the (new) Weizmann Institute of Science with Ephraim Katchalski. After a postdoc at the NIH, he returned to the Weizmann in 1958, when he joined the Department of Biophysics. In 1972-1979, he became chairman of the new Department of Organic Chemistry at the Weizmann, and his own research was geared toward applying creative chemistry to solve biological problems. Patchornik passed away in his hometown of Ness Ziona in 2014. Patchornik was a conceptual leader in peptide and polymer chemistry. Given the importance of selective functional group protection for the construction of oligomeric molecules, he became interested in using "nonstandard", orthogonal chemistry for this purpose, i.e. photosensitive protecting groups (PPGs) in place of thermal reactions. It was R.B. Woodward who suggested this strategy to Patchornik in 1965, while Patchornik was on sabbatical leave at Harvard. However, it was not until Patchornik returned to the Weizmann that this idea of a versatile PPG to enable multistep synthesis was realized. Here, we provide an account of the early photosensitive protecting groups that Patchornik and co-workers developed, and the immense impact they have had on various fields. In particular, we survey the use of PPGs in live cell physiology (i.e., caged compounds), and the development of gene chips via light-directed solid-phase synthesis. Further, we highlight recent work applying new PPGs for "photochemical delivery" of drugs, otherwise termed photopharmacology. Finally, we discuss the relationship between caged compounds and how contemporary neuroscience uses genetically encoded chromophores to control cell function.
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Affiliation(s)
- Kenneth
A. Jacobson
- Laboratory
of Bioorganic Chemistry, National Institute of Diabetes & Digestive
& Kidney Diseases, National Institutes
of Health, Bethesda, Maryland 20892, United States
| | - Graham C. R. Ellis-Davies
- Department
of Neuroscience, Icahn School of Medicine
at Mount Sinai, New York, New York 10029, United States
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3
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Hettiarachchi P, Niyangoda S, Shigemoto A, Solowiej IJ, Burdette SC, Johnson MA. Caged Zn 2+ Photolysis in Zebrafish Whole Brains Reveals Subsecond Modulation of Dopamine Uptake. ACS Chem Neurosci 2024; 15:772-782. [PMID: 38301116 PMCID: PMC11036533 DOI: 10.1021/acschemneuro.3c00668] [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] [Indexed: 02/03/2024] Open
Abstract
Free, ionic zinc (Zn2+) modulates neurotransmitter dynamics in the brain. However, the sub-s effects of transient concentration changes of Zn2+ on neurotransmitter release and uptake are not well understood. To address this lack of knowledge, we have combined the photolysis of the novel caged Zn2+ compound [Zn(DPAdeCageOMe)]+ with fast scan cyclic voltammetry (FSCV) at carbon fiber microelectrodes in live, whole brain preparations from zebrafish (Danio rerio). After treating the brain with [Zn(DPAdeCageOMe)]+, Zn2+ was released by application of light that was gated through a computer-controlled shutter synchronized with the FSCV measurements and delivered through a 1 mm fiber optic cable. We systematically optimized the photocage concentration and light application parameters, including the total duration and light-to-electrical stimulation delay time. While sub-s Zn2+ application with this method inhibited DA reuptake, assessed by the first-order rate constant (k) and half-life (t1/2), it had no effect on the electrically stimulated DA overflow ([DA]STIM). Increasing the photocage concentration and light duration progressively inhibited uptake, with maximal effects occurring at 100 μM and 800 ms, respectively. Furthermore, uptake was inhibited 200 ms after Zn2+ photorelease, but no measurable effect occurred after 800 ms. We expect that application of this method to the zebrafish whole brain and other preparations will help expand the current knowledge of how Zn2+ affects neurotransmitter release/uptake in select neurological disease states.
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Affiliation(s)
- Piyanka Hettiarachchi
- Department of Chemistry and R.N. Adams Institute for Bioanalytical Chemistry, University of Kansas, Lawrence, Kansas 66045
| | - Sayuri Niyangoda
- Department of Chemistry and R.N. Adams Institute for Bioanalytical Chemistry, University of Kansas, Lawrence, Kansas 66045
| | - Austin Shigemoto
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, MA 01609
| | - Isabel J. Solowiej
- Department of Chemistry and R.N. Adams Institute for Bioanalytical Chemistry, University of Kansas, Lawrence, Kansas 66045
| | - Shawn C. Burdette
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, MA 01609
| | - Michael A. Johnson
- Department of Chemistry and R.N. Adams Institute for Bioanalytical Chemistry, University of Kansas, Lawrence, Kansas 66045
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Farooq A, Hernandez L, Swain SM, Shahid RA, Romac JMJ, Vigna SR, Liddle RA. Initiation and severity of experimental pancreatitis are modified by phosphate. Am J Physiol Gastrointest Liver Physiol 2022; 322:G561-G570. [PMID: 35293263 PMCID: PMC9054345 DOI: 10.1152/ajpgi.00022.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 02/28/2022] [Accepted: 03/09/2022] [Indexed: 01/31/2023]
Abstract
Proper mitochondrial function and adequate cellular ATP are necessary for normal pancreatic protein synthesis and sorting, maintenance of intracellular organelles and enzyme secretion. Inorganic phosphate is required for generating ATP and its limited availability may lead to reduced ATP production causing impaired Ca2+ handling, defective autophagy, zymogen activation, and necrosis, which are all features of acute pancreatitis. We hypothesized that reduced dietary phosphate leads to hypophosphatemia and exacerbates pancreatitis severity of multiple causes. We observed that mice fed a low-phosphate diet before the induction of pancreatitis by either repeated caerulein administration or pancreatic duct injection as a model of pressure-induced pancreatitis developed hypophosphatemia and exhibited more severe pancreatitis than normophosphatemic mice. Pancreatitis severity was significantly reduced in mice treated with phosphate. In vitro modeling of secretagogue- and pressure-induced pancreatic injury was evaluated in isolated pancreatic acini using cholecystokinin and the mechanoreceptor Piezo1 agonist, Yoda1, under low and normal phosphate conditions. Isolated pancreatic acini were more sensitive to cholecystokinin- and Yoda1-induced acinar cell damage and mitochondrial dysfunction under low-phosphate conditions and improved following phosphate supplementation. Importantly, even mice on a normal phosphate diet exhibited less severe pancreatitis when treated with supplemental phosphate. Thus, hypophosphatemia sensitizes animals to pancreatitis and phosphate supplementation reduces pancreatitis severity. These appear to be direct effects of phosphate on acinar cells through restoration of mitochondrial function. We propose that phosphate administration may be useful in the treatment of acute pancreatitis.NEW & NOTEWORTHY Impaired ATP synthesis disrupts acinar cell homeostasis and is an early step in pancreatitis. We report that reduced phosphate availability impairs mitochondrial function and worsens pancreatic injury. Phosphate supplementation improves mitochondrial function and protects against experimental pancreatitis, raising the possibility that phosphate supplementation may be useful in treating pancreatitis.
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Affiliation(s)
- Ahmad Farooq
- Department of Medicine, Duke University, Durham, North Carolina
| | | | - Sandip M Swain
- Department of Medicine, Duke University, Durham, North Carolina
| | - Rafiq A Shahid
- Department of Medicine, Duke University, Durham, North Carolina
| | | | - Steven R Vigna
- Department of Medicine, Duke University, Durham, North Carolina
| | - Rodger A Liddle
- Department of Medicine, Duke University, Durham, North Carolina
- Veterans Affairs Health Care System, Durham, North Carolina
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5
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Garbincius JF, Elrod JW. Mitochondrial calcium exchange in physiology and disease. Physiol Rev 2022; 102:893-992. [PMID: 34698550 PMCID: PMC8816638 DOI: 10.1152/physrev.00041.2020] [Citation(s) in RCA: 209] [Impact Index Per Article: 69.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 08/16/2021] [Accepted: 10/19/2021] [Indexed: 12/13/2022] Open
Abstract
The uptake of calcium into and extrusion of calcium from the mitochondrial matrix is a fundamental biological process that has critical effects on cellular metabolism, signaling, and survival. Disruption of mitochondrial calcium (mCa2+) cycling is implicated in numerous acquired diseases such as heart failure, stroke, neurodegeneration, diabetes, and cancer and is genetically linked to several inherited neuromuscular disorders. Understanding the mechanisms responsible for mCa2+ exchange therefore holds great promise for the treatment of these diseases. The past decade has seen the genetic identification of many of the key proteins that mediate mitochondrial calcium uptake and efflux. Here, we present an overview of the phenomenon of mCa2+ transport and a comprehensive examination of the molecular machinery that mediates calcium flux across the inner mitochondrial membrane: the mitochondrial uniporter complex (consisting of MCU, EMRE, MICU1, MICU2, MICU3, MCUB, and MCUR1), NCLX, LETM1, the mitochondrial ryanodine receptor, and the mitochondrial permeability transition pore. We then consider the physiological implications of mCa2+ flux and evaluate how alterations in mCa2+ homeostasis contribute to human disease. This review concludes by highlighting opportunities and challenges for therapeutic intervention in pathologies characterized by aberrant mCa2+ handling and by summarizing critical unanswered questions regarding the biology of mCa2+ flux.
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Affiliation(s)
- Joanne F Garbincius
- Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania
| | - John W Elrod
- Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania
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Petersen OH. Electrophysiology of Exocrine Gland Cells. Bioelectricity 2022; 4:48-58. [PMID: 39355562 PMCID: PMC11441361 DOI: 10.1089/bioe.2022.0011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Affiliation(s)
- Ole H Petersen
- School of Biosciences, Cardiff University, Cardiff, Wales, United Kingdom
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7
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Guo L, Yao J, Cao Y. Regulation of pancreatic exocrine in ruminants and the related mechanism: The signal transduction and more. ACTA ACUST UNITED AC 2021; 7:1145-1151. [PMID: 34754956 PMCID: PMC8556483 DOI: 10.1016/j.aninu.2021.09.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Revised: 09/08/2021] [Accepted: 09/27/2021] [Indexed: 12/11/2022]
Abstract
The unique structure of the stomach, including the rumen, reticulum, omasum, and abomasum, indicates the differences between the ruminant and monogastric animals in the digestion of nutrients. This difference is reflected in the majority of dietary nutrients that may be fermented in the rumen. Significant proteins and a certain amount of starch can flow to the small intestine apart from rumen. The initial phase of small intestinal digestion requires pancreatic digestive enzymes. In theory, the enzymatic digestion and utilization efficiency of starch in the small intestine are considerably higher than that in the rumen, but the starch digestibility in the small intestine is quite low in ruminants. Therefore, improving the digestion of nutrients, especially starch in the small intestine is more urgent for high-yield ruminants. Although the pancreas plays a central role in nutrient digestion, the progress of research investigating pancreatic exocrine regulation in the ruminant is slow due to some factors, such as the complex structure of the pancreas, the selection of experimental model and duration, and internal (hormones or ages) and external (diet) influences. The present review is based on the research findings of pancreatic exocrine regulation of dairy animals and expounded from the physiological structure of the ruminant pancreas, the factors affecting the digestion and exocrine processing of carbohydrates, and the regulatory mechanism governing this process. The review aims to better understand the characteristics of enzymatic digestion, thereby advancing pancreatic exocrine research and improving the digestion and utilization of nutrients in ruminants. Additionally, this review provides the theoretical basis for improving nutrient utilization efficiency, reducing wastage of feed resources, and promoting the efficient development of the dairy industry.
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Affiliation(s)
- Long Guo
- College of Animal Science and Technology, Northwest A&F University, Yangling Shaanxi, 712100, China.,State Key Laboratory of Grassland Agro-ecosystems of Lanzhou University, Lanzhou, 730020, China.,College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China
| | - Junhu Yao
- College of Animal Science and Technology, Northwest A&F University, Yangling Shaanxi, 712100, China
| | - Yangchun Cao
- College of Animal Science and Technology, Northwest A&F University, Yangling Shaanxi, 712100, China
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Schnipper J, Dhennin-Duthille I, Ahidouch A, Ouadid-Ahidouch H. Ion Channel Signature in Healthy Pancreas and Pancreatic Ductal Adenocarcinoma. Front Pharmacol 2020; 11:568993. [PMID: 33178018 PMCID: PMC7596276 DOI: 10.3389/fphar.2020.568993] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 09/16/2020] [Indexed: 12/11/2022] Open
Abstract
Pancreatic ductal adenocarcinoma (PDAC) is the fourth most common cause of cancer-related deaths in United States and Europe. It is predicted that PDAC will become the second leading cause of cancer-related deaths during the next decades. The development of PDAC is not well understood, however, studies have shown that dysregulated exocrine pancreatic fluid secretion can contribute to pathologies of exocrine pancreas, including PDAC. The major roles of healthy exocrine pancreatic tissue are secretion of enzymes and bicarbonate rich fluid, where ion channels participate to fine-tune these biological processes. It is well known that ion channels located in the plasma membrane regulate multiple cellular functions and are involved in the communication between extracellular events and intracellular signaling pathways and can function as signal transducers themselves. Hereby, they contribute to maintain resting membrane potential, electrical signaling in excitable cells, and ion homeostasis. Despite their contribution to basic cellular processes, ion channels are also involved in the malignant transformation from a normal to a malignant phenotype. Aberrant expression and activity of ion channels have an impact on essentially all hallmarks of cancer defined as; uncontrolled proliferation, evasion of apoptosis, sustained angiogenesis and promotion of invasion and migration. Research indicates that certain ion channels are involved in the aberrant tumor growth and metastatic processes of PDAC. The purpose of this review is to summarize the important expression, localization, and function of ion channels in normal exocrine pancreatic tissue and how they are involved in PDAC progression and development. As ion channels are suggested to be potential targets of treatment they are furthermore suggested to be biomarkers of different cancers. Therefore, we describe the importance of ion channels in PDAC as markers of diagnosis and clinical factors.
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Affiliation(s)
- Julie Schnipper
- Laboratory of Cellular and Molecular Physiology, UR-4667, University of Picardie Jules Verne, Amiens, France
| | - Isabelle Dhennin-Duthille
- Laboratory of Cellular and Molecular Physiology, UR-4667, University of Picardie Jules Verne, Amiens, France
| | - Ahmed Ahidouch
- Laboratory of Cellular and Molecular Physiology, UR-4667, University of Picardie Jules Verne, Amiens, France.,Department of Biology, Faculty of Sciences, Ibn Zohr University, Agadir, Morocco
| | - Halima Ouadid-Ahidouch
- Laboratory of Cellular and Molecular Physiology, UR-4667, University of Picardie Jules Verne, Amiens, France
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Multipurpose Na + ions mediate excitation and cellular homeostasis: Evolution of the concept of Na + pumps and Na +/Ca 2+ exchangers. Cell Calcium 2020; 87:102166. [PMID: 32006802 DOI: 10.1016/j.ceca.2020.102166] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 01/21/2020] [Indexed: 12/14/2022]
Abstract
Ionic signalling is the most ancient form of regulation of cellular functions in response to environmental challenges. Signals, mediated by Na+ fluxes and spatio-temporal fluctuations of Na+ concentration in cellular organelles and cellular compartments contribute to the most fundamental cellular processes such as membrane excitability and energy production. At the very core of ionic signalling lies the Na+-K+ ATP-driven pump (or NKA) which creates trans-plasmalemmal ion gradients that sustain ionic fluxes through ion channels and numerous Na+-dependent transporters that maintain cellular and tissue homeostasis. Here we present a brief account of the history of research into NKA, Na+ -dependent transporters and Na+ signalling.
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10
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Inhibitory effect of high leucine concentration on α-amylase secretion by pancreatic acinar cells: possible key factor of proteasome. Biosci Rep 2018; 38:BSR20181455. [PMID: 30361293 PMCID: PMC6294628 DOI: 10.1042/bsr20181455] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 10/17/2018] [Accepted: 10/23/2018] [Indexed: 01/13/2023] Open
Abstract
The present study aimed to investigate whether leucine affects the pancreatic exocrine by controlling the antisecretory factor (AF) and cholecystokinin receptor (CCKR) expression as well as the proteasome activity in pancreatic acinar cells of dairy calves. The pancreatic acinar cells were isolated from newborn Holstein bull calves and cultured using the Dulbecco’s modified Eagle’s medium/nutrient mixture F12 Ham’s liquid (DMEM/F12). There were six treatments of leucine dosage including 0 (control), 0.23, 0.45, 1.35, 4.05, and 12.15 mM, respectively. After culture for 3 h, the samples were collected for subsequent analysis. As the leucine concentration increased from 0 to 1.35 mM, the α-amylase activity in media decreased significantly (P<0.05), while further increase in leucine concentration did not show any decrease in α-amylase activity. Addition of leucine inhibited (P<0.05) the expression of AF and CCKR, and decreased the activity of proteasome (P<0.05) by 76%, 63%, 24%, 7%, and 9%, respectively. Correlation analysis results showed α-amylase secretion was negatively correlated with leucine concentration (P<0.01), and positively correlated with proteasome activity (P<0.01) and the expression of CCK1R (P<0.01) and AF (P<0.05). The biggest regression coefficient was showed between α-amylase activity and proteasome (0.7699, P<0.001). After inhibition of proteasome by MG-132, low dosage leucine decreased (P<0.05) the activity of proteasome and α-amylase, as well as the expression of CCK1R. In conclusion, we demonstrated that the high-concentration leucine induced decrease in α-amylase release was mainly by decreasing proteasome activity.
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11
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Jakkampudi A, Jangala R, Reddy BR, Mitnala S, Nageshwar Reddy D, Talukdar R. NF-κB in acute pancreatitis: Mechanisms and therapeutic potential. Pancreatology 2016; 16:477-88. [PMID: 27282980 DOI: 10.1016/j.pan.2016.05.001] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 05/03/2016] [Accepted: 05/04/2016] [Indexed: 12/11/2022]
Abstract
The incidence of acute pancreatitis (AP) is increasing globally and mortality could be high among patients with organ failure and infected necrosis. The predominant factors responsible for the morbidity and mortality of AP are systemic inflammatory response syndrome and multiorgan dysfunction. Even though preclinical studies have shown antisecretory agents (somatostatin), antioxidants (S-adenosyl methionine [SAM], selenium), protease inhibitors, platelet activating factor inhibitor (Lexipafant), and anti-inflammatory immunomodulators (eg. prostaglandin E, indomethacin) to benefit AP in terms of reducing the severity and/or mortality, most of these agents have shown heterogeneous results in clinical studies. Several years of experimental studies have implicated nuclear factor-kappa B (NF-κB) activation as an early and central event in the progression of inflammation in AP. In this manuscript, we review the literature on the role of NF-κB in the pathogenesis of AP, its early intraacinar activation, and how it results in progression of the disease. We also discuss why anti-protease, antisecretory, and anti-inflammatory agents are unlikely to be effective in clinical acute pancreatitis. NF-κB, being a central molecule that links the initial acinar injury to systemic inflammation and perpetuate the inflammation, we propose that more studies be focussed towards targeted inhibition of NF-κB activity. Direct NF-κB inhibition strategies have already been attempted in patients with various cancers. So far, peroxisome proliferator activator receptor gamma (PPAR-γ) ligand, pyrrolidine dithiocarbamate (PDTC), proteasome inhibitor and calpain I inhibitor have been shown to have direct inhibitory effects on NF-κB activation in experimental AP.
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Affiliation(s)
- Aparna Jakkampudi
- Wellcome-DBT Laboratory, Asian Healthcare Foundation, Hyderabad, India
| | - Ramaiah Jangala
- Wellcome-DBT Laboratory, Asian Healthcare Foundation, Hyderabad, India
| | - B Ratnakar Reddy
- Wellcome-DBT Laboratory, Asian Healthcare Foundation, Hyderabad, India
| | - Sasikala Mitnala
- Wellcome-DBT Laboratory, Asian Healthcare Foundation, Hyderabad, India
| | - D Nageshwar Reddy
- Dept. of Medical Gastroenterology, Asian Institute of Gastroenterology, Hyderabad, India
| | - Rupjyoti Talukdar
- Wellcome-DBT Laboratory, Asian Healthcare Foundation, Hyderabad, India; Dept. of Medical Gastroenterology, Asian Institute of Gastroenterology, Hyderabad, India.
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12
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Himeno H, Ito H, Higuchi Y, Hamada T, Shimokawa N, Takagi M. Coupling between pore formation and phase separation in charged lipid membranes. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:062713. [PMID: 26764733 DOI: 10.1103/physreve.92.062713] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Indexed: 06/05/2023]
Abstract
We investigated the effect of charge on the membrane morphology of giant unilamellar vesicles (GUVs) composed of various mixtures containing charged lipids. We observed the membrane morphologies by fluorescent and confocal laser microscopy in lipid mixtures consisting of a neutral unsaturated lipid [dioleoylphosphatidylcholine (DOPC)], a neutral saturated lipid [dipalmitoylphosphatidylcholine (DPPC)], a charged unsaturated lipid [dioleoylphosphatidylglycerol (DOPG((-)))], a charged saturated lipid [dipalmitoylphosphatidylglycerol (DPPG((-)))], and cholesterol (Chol). In binary mixtures of neutral DOPC-DPPC and charged DOPC-DPPG((-))), spherical vesicles were formed. On the other hand, pore formation was often observed with GUVs consisting of DOPG((-))) and DPPC. In a DPPC-DPPG((-)))-Chol ternary mixture, pore-formed vesicles were also frequently observed. The percentage of pore-formed vesicles increased with the DPPG((-))) concentration. Moreover, when the head group charges of charged lipids were screened by the addition of salt, pore-formed vesicles were suppressed in both the binary and ternary charged lipid mixtures. We discuss the mechanisms of pore formation in charged lipid mixtures and the relationship between phase separation and the membrane morphology. Finally, we reproduce the results seen in experimental systems by using coarse-grained molecular dynamics simulations.
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Affiliation(s)
- Hiroki Himeno
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Takamatsu 761-0395, Japan
| | - Hiroaki Ito
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Yuji Higuchi
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - Tsutomu Hamada
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan
| | - Naofumi Shimokawa
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan
| | - Masahiro Takagi
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan
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13
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Cherian OL, Menini A, Boccaccio A. Multiple effects of anthracene-9-carboxylic acid on the TMEM16B/anoctamin2 calcium-activated chloride channel. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1005-13. [PMID: 25620774 DOI: 10.1016/j.bbamem.2015.01.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 01/04/2015] [Accepted: 01/13/2015] [Indexed: 10/24/2022]
Abstract
Ca(2+)-activated Cl(-) currents (CaCCs) play important roles in many physiological processes. Recent studies have shown that TMEM16A/anoctamin1 and TMEM16B/anoctamin2 constitute CaCCs in several cell types. Here we have investigated for the first time the extracellular effects of the Cl(-) channel blocker anthracene-9-carboxylic acid (A9C) and of its non-charged analogue anthracene-9-methanol (A9M) on TMEM16B expressed in HEK 293T cells, using the whole-cell patch-clamp technique. A9C caused a voltage-dependent block of outward currents and inhibited a larger fraction of the current as depolarization increased, whereas the non-charged A9M produced a small, not voltage dependent block of outward currents. A similar voltage-dependent block by A9C was measured both when TMEM16B was activated by 1.5 and 13μM Ca(2+). However, in the presence of 1.5μM Ca(2+) (but not in 13μM Ca(2+)), A9C also induced a strong potentiation of tail currents measured at -100mV after depolarizing voltages, as well as a prolongation of the deactivation kinetics. On the contrary, A9M did not produce potentiation of tail currents, showing that the negative charge is required for potentiation. Our results provide the first evidence that A9C has multiple effects on TMEM16B and that the negative charge of A9C is necessary both for voltage-dependent block and for potentiation. Future studies are required to identify the molecular mechanisms underlying these complex effects of A9C on TMEM16B. Understanding these mechanisms will contribute to the elucidation of the structure and functional properties of TMEM16B channels.
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Affiliation(s)
- O Lijo Cherian
- Neurobiology Group, SISSA, International School for Advanced Studies, Via Bonomea 265, 34136 Trieste, Italy
| | - Anna Menini
- Neurobiology Group, SISSA, International School for Advanced Studies, Via Bonomea 265, 34136 Trieste, Italy
| | - Anna Boccaccio
- Istituto di Biofisica, CNR, Via De Marini 6, 16149 Genova, Italy.
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Li J, Zhou R, Zhang J, Li ZF. Calcium signaling of pancreatic acinar cells in the pathogenesis of pancreatitis. World J Gastroenterol 2014; 20:16146-16152. [PMID: 25473167 PMCID: PMC4239501 DOI: 10.3748/wjg.v20.i43.16146] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 06/09/2014] [Accepted: 07/11/2014] [Indexed: 02/07/2023] Open
Abstract
Pancreatitis is an increasingly common and sometimes severe disease that lacks a specific therapy. The pathogenesis of pancreatitis is still not well understood. Calcium (Ca2+) is a versatile carrier of signals regulating many aspects of cellular activity and plays a central role in controlling digestive enzyme secretion in pancreatic acinar cells. Ca2+ overload is a key early event and is crucial in the pathogenesis of many diseases. In pancreatic acinar cells, pathological Ca2+ signaling (stimulated by bile, alcohol metabolites and other causes) is a key contributor to the initiation of cell injury due to prolonged and global Ca2+ elevation that results in trypsin activation, vacuolization and necrosis, all of which are crucial in the development of pancreatitis. Increased release of Ca2+ from stores in the intracellular endoplasmic reticulum and/or increased Ca2+ entry through the plasma membrane are causes of such cell damage. Failed mitochondrial adenosine triphosphate (ATP) production reduces re-uptake and extrusion of Ca2+ by the sarco/endoplasmic reticulum Ca2+-activated ATPase and plasma membrane Ca2+-ATPase pumps, which contribute to Ca2+ overload. Current findings have provided further insight into the roles and mechanisms of abnormal pancreatic acinar Ca2+ signals in pancreatitis. The lack of available specific treatments is therefore an objective of ongoing research. Research is currently underway to establish the mechanisms and interactions of Ca2+ signals in the pathogenesis of pancreatitis.
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Betto G, Cherian OL, Pifferi S, Cenedese V, Boccaccio A, Menini A. Interactions between permeation and gating in the TMEM16B/anoctamin2 calcium-activated chloride channel. ACTA ACUST UNITED AC 2014; 143:703-18. [PMID: 24863931 PMCID: PMC4035747 DOI: 10.1085/jgp.201411182] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Extracellular anions more permeant than Cl− modulate TMEM16B gating to promote channel opening, whereas less permeant anions favor channel closure. At least two members of the TMEM16/anoctamin family, TMEM16A (also known as anoctamin1) and TMEM16B (also known as anoctamin2), encode Ca2+-activated Cl− channels (CaCCs), which are found in various cell types and mediate numerous physiological functions. Here, we used whole-cell and excised inside-out patch-clamp to investigate the relationship between anion permeation and gating, two processes typically viewed as independent, in TMEM16B expressed in HEK 293T cells. The permeability ratio sequence determined by substituting Cl− with other anions (PX/PCl) was SCN− > I− > NO3− > Br− > Cl− > F− > gluconate. When external Cl− was substituted with other anions, TMEM16B activation and deactivation kinetics at 0.5 µM Ca2+ were modified according to the sequence of permeability ratios, with anions more permeant than Cl− slowing both activation and deactivation and anions less permeant than Cl− accelerating them. Moreover, replacement of external Cl− with gluconate, or sucrose, shifted the voltage dependence of steady-state activation (G-V relation) to more positive potentials, whereas substitution of extracellular or intracellular Cl− with SCN− shifted G-V to more negative potentials. Dose–response relationships for Ca2+ in the presence of different extracellular anions indicated that the apparent affinity for Ca2+ at +100 mV increased with increasing permeability ratio. The apparent affinity for Ca2+ in the presence of intracellular SCN− also increased compared with that in Cl−. Our results provide the first evidence that TMEM16B gating is modulated by permeant anions and provide the basis for future studies aimed at identifying the molecular determinants of TMEM16B ion selectivity and gating.
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Affiliation(s)
- Giulia Betto
- Neurobiology Group, International School for Advanced Studies (SISSA), 34136 Trieste, Italy
| | - O Lijo Cherian
- Neurobiology Group, International School for Advanced Studies (SISSA), 34136 Trieste, Italy
| | - Simone Pifferi
- Neurobiology Group, International School for Advanced Studies (SISSA), 34136 Trieste, Italy
| | - Valentina Cenedese
- Neurobiology Group, International School for Advanced Studies (SISSA), 34136 Trieste, Italy
| | - Anna Boccaccio
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche, 16149 Genova, Italy
| | - Anna Menini
- Neurobiology Group, International School for Advanced Studies (SISSA), 34136 Trieste, Italy
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Sah RP, Garg SK, Dixit AK, Dudeja V, Dawra RK, Saluja AK. Endoplasmic reticulum stress is chronically activated in chronic pancreatitis. J Biol Chem 2014; 289:27551-61. [PMID: 25077966 DOI: 10.1074/jbc.m113.528174] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The pathogenesis of chronic pancreatitis (CP) is poorly understood. Endoplasmic reticulum (ER) stress has now been recognized as a pathogenic event in many chronic diseases. However, ER stress has not been studied in CP, although pancreatic acinar cells seem to be especially vulnerable to ER dysfunction because of their dependence on high ER volume and functionality. Here, we aim to investigate ER stress in CP, study its pathogenesis in relation to trypsinogen activation (widely regarded as the key event of pancreatitis), and explore its mechanism, time course, and downstream consequences during pancreatic injury. CP was induced in mice by repeated episodes of acute pancreatitis (AP) based on caerulein hyperstimulation. ER stress leads to activation of unfolded protein response components that were measured in CP and AP. We show sustained up-regulation of unfolded protein response components ATF4, CHOP, GRP78, and XBP1 in CP. Overexpression of GRP78 and ATF4 in human CP confirmed the experimental findings. We used novel trypsinogen-7 knock-out mice (T(-/-)), which lack intra-acinar trypsinogen activation, to clarify the relationship of ER stress to intra-acinar trypsinogen activation in pancreatic injury. Comparable activation of ER stress was seen in wild type and T(-/-) mice. Induction of ER stress occurred through pathologic calcium signaling very early in the course of pancreatic injury. Our results establish that ER stress is chronically activated in CP and is induced early in pancreatic injury through pathologic calcium signaling independent of trypsinogen activation. ER stress may be an important pathogenic mechanism in pancreatitis that needs to be explored in future studies.
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Affiliation(s)
- Raghuwansh P Sah
- From the Division of Basic and Translational Research, Department of Surgery, University of Minnesota Medical School, Minneapolis, Minnesota 55455
| | - Sushil K Garg
- From the Division of Basic and Translational Research, Department of Surgery, University of Minnesota Medical School, Minneapolis, Minnesota 55455
| | - Ajay K Dixit
- From the Division of Basic and Translational Research, Department of Surgery, University of Minnesota Medical School, Minneapolis, Minnesota 55455
| | - Vikas Dudeja
- From the Division of Basic and Translational Research, Department of Surgery, University of Minnesota Medical School, Minneapolis, Minnesota 55455
| | - Rajinder K Dawra
- From the Division of Basic and Translational Research, Department of Surgery, University of Minnesota Medical School, Minneapolis, Minnesota 55455
| | - Ashok K Saluja
- From the Division of Basic and Translational Research, Department of Surgery, University of Minnesota Medical School, Minneapolis, Minnesota 55455
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17
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Modelling mechanism of calcium oscillations in pancreatic acinar cells. J Bioenerg Biomembr 2014; 46:403-20. [DOI: 10.1007/s10863-014-9561-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 06/24/2014] [Indexed: 01/18/2023]
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18
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Gerasimenko J, Peng S, Gerasimenko O. Role of acidic stores in secretory epithelia. Cell Calcium 2014; 55:346-54. [DOI: 10.1016/j.ceca.2014.04.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 04/05/2014] [Accepted: 04/08/2014] [Indexed: 12/14/2022]
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19
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Manhas N, Sneyd J, Pardasani KR. Modelling the transition from simple to complex Ca²⁺ oscillations in pancreatic acinar cells. J Biosci 2014; 39:463-84. [PMID: 24845510 DOI: 10.1007/s12038-014-9430-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A mathematical model is proposed which systematically investigates complex calcium oscillations in pancreatic acinar cells. This model is based on calcium-induced calcium release via inositol trisphosphate receptors (IPR) and ryanodine receptors (RyR) and includes calcium modulation of inositol (1,4,5) trisphosphate (IP3) levels through feedback regulation of degradation and production. In our model, the apical and the basal regions are separated by a region containing mitochondria, which is capable of restricting Ca2+ responses to the apical region. We were able to reproduce the observed oscillatory patterns, from baseline spikes to sinusoidal oscillations. The model predicts that calcium-dependent production and degradation of IP3 is a key mechanism for complex calcium oscillations in pancreatic acinar cells. A partial bifurcation analysis is performed which explores the dynamic behaviour of the model in both apical and basal regions.
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Affiliation(s)
- Neeraj Manhas
- Department of Mathematics, Maulana Azad National Institute of Technology, Bhopal 462 051, India,
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20
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Lee RJ, Foskett JK. Ca²⁺ signaling and fluid secretion by secretory cells of the airway epithelium. Cell Calcium 2014; 55:325-36. [PMID: 24703093 DOI: 10.1016/j.ceca.2014.02.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 01/31/2014] [Accepted: 02/01/2014] [Indexed: 11/24/2022]
Abstract
Cytoplasmic Ca(2+) is a master regulator of airway physiology; it controls fluid, mucus, and antimicrobial peptide secretion, ciliary beating, and smooth muscle contraction. The focus of this review is on the role of cytoplasmic Ca(2+) in fluid secretion by airway exocrine secretory cells. Airway submucosal gland serous acinar cells are the primary fluid secreting cell type of the cartilaginous conducting airways, and this review summarizes the current state of knowledge of the molecular mechanisms of serous cell ion transport, with an emphasis on their regulation by intracellular Ca(2+). Many neurotransmitters that regulate secretion from serous acinar cells utilize Ca(2+) as a second messenger. Changes in intracellular Ca(2+) concentration regulate the activities of ion transporters and channels involved in transepithelial ion transport and fluid secretion, including Ca(2+)-activated K(+) channels and Cl(-) channels. We also review evidence of interactions of Ca(2+) signaling with other signaling pathways (cAMP, NO) that impinge upon different ion transport pathways, including the cAMP/PKA-activated cystic fibrosis (CF) transmembrane conductance regulator (CFTR) anion channel. A better understanding of Ca(2+) signaling and its targets in airway fluid secretion may identify novel strategies to intervene in airway diseases, for example to enhance fluid secretion in CF airways.
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Affiliation(s)
- Robert J Lee
- Department of Otorhinolaryngology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - J Kevin Foskett
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States; Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States.
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21
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Muallem S, Verkhratsky A. The art of physiology in the hands of the master: the calcium community celebrates the 70th birthday of Ole Holger Petersen. Cell Calcium 2013; 53:303-6. [PMID: 23710829 DOI: 10.1016/j.ceca.2013.05.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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22
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Tseng YC, Yang A, Huang L. How does the cell overcome LCP nanoparticle-induced calcium toxicity? Mol Pharm 2013; 10:4391-5. [PMID: 24032396 DOI: 10.1021/mp400028m] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To address the question of how cells respond to the possible Ca(2+) toxicity caused by the release of Ca(2+) into the cytoplasm by LCP nanoparticles, a series of in vitro and in vivo studies using Ca(2+) pump inhibitors were conducted. The results indicated that two major Ca(2+) pumps on the plasma membrane and the mitochondrial membrane, respectively, were able to rapidly respond to the elevated cytosolic Ca(2+) concentration and prevent Ca(2+)-induced apoptosis or necrosis. However, exposure to specific inhibitors of calcium pumps would cause LCP-treated H460 cells to undergo necrosis both in vitro and in vivo. These results demonstrated that the Ca(2+) delivered by LCP was not toxic to cells when the cells contain functional Ca(2+) pumps.
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Affiliation(s)
- Yu-Cheng Tseng
- Division of Molecular Pharmaceutics and Center for Nanotechnology in Drug Delivery, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-7571, United States
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23
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Orabi AI, Muili KA, Javed TA, Jin S, Jayaraman T, Lund FE, Husain SZ. Cluster of differentiation 38 (CD38) mediates bile acid-induced acinar cell injury and pancreatitis through cyclic ADP-ribose and intracellular calcium release. J Biol Chem 2013; 288:27128-27137. [PMID: 23940051 DOI: 10.1074/jbc.m113.494534] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Aberrant Ca(2+) signals within pancreatic acinar cells are an early and critical feature in acute pancreatitis, yet it is unclear how these signals are generated. An important mediator of the aberrant Ca(2+) signals due to bile acid exposure is the intracellular Ca(2+) channel ryanodine receptor. One putative activator of the ryanodine receptor is the nucleotide second messenger cyclic ADP-ribose (cADPR), which is generated by an ectoenzyme ADP-ribosyl cyclase, CD38. In this study, we examined the role of CD38 and cADPR in acinar cell Ca(2+) signals and acinar injury due to bile acids using pharmacologic inhibitors of CD38 and cADPR as well as mice deficient in Cd38 (Cd38(-/-)). Cytosolic Ca(2+) signals were imaged using live time-lapse confocal microscopy in freshly isolated mouse acinar cells during perifusion with the bile acid taurolithocholic acid 3-sulfate (TLCS; 500 μM). To focus on intracellular Ca(2+) release and to specifically exclude Ca(2+) influx, cells were perifused in Ca(2+)-free medium. Cell injury was assessed by lactate dehydrogenase leakage and propidium iodide uptake. Pretreatment with either nicotinamide (20 mM) or the cADPR antagonist 8-Br-cADPR (30 μM) abrogated TLCS-induced Ca(2+) signals and cell injury. TLCS-induced Ca(2+) release and cell injury were reduced by 30 and 95%, respectively, in Cd38-deficient acinar cells compared with wild-type cells (p < 0.05). Cd38-deficient mice were protected against a model of bile acid infusion pancreatitis. In summary, these data indicate that CD38-cADPR mediates bile acid-induced pancreatitis and acinar cell injury through aberrant intracellular Ca(2+) signaling.
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Affiliation(s)
| | | | | | | | - Thottala Jayaraman
- Departments of Internal Medicine, Children's Hospital of Pittsburgh of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15224
| | - Frances E Lund
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35213
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24
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Nakamura K, Hamada K, Terauchi A, Matsui M, Nakamura T, Okada T, Mikoshiba K. Distinct roles of M1 and M3 muscarinic acetylcholine receptors controlling oscillatory and non-oscillatory [Ca2+]i increase. Cell Calcium 2013; 54:111-9. [PMID: 23747049 DOI: 10.1016/j.ceca.2013.05.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 05/07/2013] [Accepted: 05/10/2013] [Indexed: 10/26/2022]
Abstract
We examined ACh-induced [Ca2+]i dynamics in pancreatic acinar cells prepared from mAChR subtype-specific knockout (KO) mice. ACh did not induce any [Ca2+]i increase in the cells isolated from M1/M3 double KO mice. In the cells from M3KO mice, ACh (0.3-3 μM) caused a monotonic [Ca2+]i increase. However, we found characteristic oscillatory [Ca2+]i increases in cells from M1KO mice in lower concentrations of ACh (0.03-0.3 μM). We investigated the receptor specific pattern of [Ca2+]i increase in COS-7 cells transfected with M1 or M3 receptors. ACh induced the oscillatory [Ca2+]i increase in M3 expressing cells, but not in cells expressing M1, which exhibited monotonic [Ca2+]i increases. IP3 production detected in fluorescent indicator co-transfected cells was higher in M1 than in M3 expressing cells. From the examination of four types of M1/M3 chimera receptors we found that the carboxyl-terminal region of M3 was responsible for the generation of Ca2+ oscillations. The present results suggest that the oscillatory Ca2+ increase in response to M3 stimulation is dependent upon a moderate IP3 increase, which is suitable for causing Ca(2+)-dependent IP3-induced Ca2+ release. The C-terminal domain of M3 may contribute as a regulator of the efficiency of Gq and PLC cooperation.
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Affiliation(s)
- Kyoko Nakamura
- Department of Physiology, Juntendo University Faculty of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
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25
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The Exocrine Pancreas: The Acinar-Ductal Tango in Physiology and Pathophysiology. Rev Physiol Biochem Pharmacol 2013; 165:1-30. [DOI: 10.1007/112_2013_14] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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26
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Orabi AI, Luo Y, Ahmad MU, Shah AU, Mannan Z, Wang D, Sarwar S, Muili KA, Shugrue C, Kolodecik TR, Singh VP, Lowe ME, Thrower E, Chen J, Husain SZ. IP3 receptor type 2 deficiency is associated with a secretory defect in the pancreatic acinar cell and an accumulation of zymogen granules. PLoS One 2012. [PMID: 23185258 PMCID: PMC3504040 DOI: 10.1371/journal.pone.0048465] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Acute pancreatitis is a painful, life-threatening disorder of the pancreas whose etiology is often multi-factorial. It is of great importance to understand the interplay between factors that predispose patients to develop the disease. One such factor is an excessive elevation in pancreatic acinar cell Ca2+. These aberrant Ca2+ elevations are triggered by release of Ca2+ from apical Ca2+ pools that are gated by the inositol 1,4,5-trisphosphate receptor (IP3R) types 2 and 3. In this study, we examined the role of IP3R type 2 (IP3R2) using mice deficient in this Ca2+ release channel (IP3R2−/−). Using live acinar cell Ca2+ imaging we found that loss of IP3R2 reduced the amplitude of the apical Ca2+ signal and caused a delay in its initiation. This was associated with a reduction in carbachol-stimulated amylase release and an accumulation of zymogen granules (ZGs). Specifically, there was a 2-fold increase in the number of ZGs (P<0.05) and an expansion of the ZG pool area within the cell. There was also a 1.6- and 2.6-fold increase in cellular amylase and trypsinogen, respectively. However, the mice did not have evidence of pancreatic injury at baseline, other than an elevated serum amylase level. Further, pancreatitis outcomes using a mild caerulein hyperstimulation model were similar between IP3R2−/− and wild type mice. In summary, IP3R2 modulates apical acinar cell Ca2+ signals and pancreatic enzyme secretion. IP3R-deficient acinar cells accumulate ZGs, but the mice do not succumb to pancreatic damage or worse pancreatitis outcomes.
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Affiliation(s)
- Abrahim I. Orabi
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Yuhuan Luo
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Mahwish U. Ahmad
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Ahsan U. Shah
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Zahir Mannan
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Dong Wang
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Sheharyar Sarwar
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Kamaldeen A. Muili
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Christine Shugrue
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Thomas R. Kolodecik
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Vijay P. Singh
- Department of Internal Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Mark E. Lowe
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Edwin Thrower
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Ju Chen
- Department of Molecular Pathology, University of California San Diego, San Diego, California, United States of America
| | - Sohail Z. Husain
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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27
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Abstract
PURPOSE OF REVIEW In this article, recent advances in the pathogenesis of acute pancreatitis have been reviewed. RECENT FINDINGS Pathologic intra-acinar trypsinogen activation had been hypothesized to be the central mechanism of pancreatitis for over a century. This hypothesis could be explored for the first time with the development of a novel mouse model lacking pathologic intra-acinar trypsinogen activation. It became clear that intra-acinar trypsinogen activation contributes to early acinar injury, but local and systemic inflammation progress independently during pancreatitis. Early intra-acinar nuclear factor kappa B (NFκB) activation, which occurs parallel to but independent of trypsinogen activation, may be crucial in pancreatitis. Although the mechanism of NFκB and trypsinogen activation is not entirely clear, further insights have been made into key pathogenic cellular events such as calcium signaling, mitochondrial dysfunction, endoplasmic reticulum (ER) stress, autophagy and impaired trafficking, and lysosomal and secretory responses. Cellular intrinsic damage-sensing mechanisms that lead to activation of the inflammatory response aimed at repair, but lead to disease when overwhelmed, are beginning to be understood. SUMMARY New findings necessitate a paradigm shift in our understanding of acute pancreatitis. Intra-acinar trypsinogen activation leads to early pancreatic injury, but the inflammatory response of acute pancreatitis develops independently, driven by early activation of inflammatory pathways.
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28
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Kim SO, Ives KL, Wang X, Davey RA, Chao C, Hellmich MR. Raf-1 kinase inhibitory protein (RKIP) mediates ethanol-induced sensitization of secretagogue signaling in pancreatic acinar cells. J Biol Chem 2012; 287:33377-88. [PMID: 22859298 DOI: 10.1074/jbc.m112.367656] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Excessive alcohol consumption is associated with most cases of chronic pancreatitis, a progressive necrotizing inflammatory disease that can result in pancreatic insufficiency due to acinar atrophy and fibrosis and an increased risk of pancreatic cancer. At a cellular level acute alcohol exposure can sensitize pancreatic acinar cells to secretagogue stimulation, resulting in dysregulation of intracellular Ca(2+) homeostasis and premature digestive enzyme activation; however, the molecular mechanisms by which ethanol exerts these toxic effects have remained undefined. In this study we identify Raf-1 kinase inhibitory protein as an essential mediator of ethanol-induced sensitization of cholecystokinin- and carbachol-regulated Ca(2+) signaling in pancreatic acinar cells. We show that exposure of rodent acinar cells to ethanol induces protein kinase C-dependent Raf-1 kinase inhibitory protein phosphorylation, sensitization of cholecystokinin-stimulated Ca(2+) signaling, and potentiation of both basal and cholecystokinin-stimulated extracellular signal-regulated kinase activation. Furthermore, we show that either suppression of Raf-1 kinase inhibitory protein expression using short hairpin RNA or gene ablation prevented the sensitizing effects of ethanol on cholecystokinin- and carbachol-stimulated Ca(2+) signaling and intracellular chymotrypsin activation in pancreatic acinar cells, suggesting that the modulation of Raf-1 inhibitory protein expression may have future therapeutic utility in the prevention or treatment of alcohol-associated pancreatitis.
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Affiliation(s)
- Sung Ok Kim
- Department of Surgery, University of Texas Medical Branch, Galveston, Texas 77555-0722, USA
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29
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Verkhratsky A, Rodríguez JJ, Parpura V. Calcium signalling in astroglia. Mol Cell Endocrinol 2012; 353:45-56. [PMID: 21945602 DOI: 10.1016/j.mce.2011.08.039] [Citation(s) in RCA: 171] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 08/28/2011] [Accepted: 08/31/2011] [Indexed: 12/15/2022]
Abstract
Astroglia possess excitability based on movements of Ca(2+) ions between intracellular compartments and plasmalemmal Ca(2+) fluxes. This "Ca(2+) excitability" is controlled by several families of proteins located in the plasma membrane, within the cytosol and in the intracellular organelles, most notably in the endoplasmic reticulum (ER) and mitochondria. Accumulation of cytosolic Ca(2+) can be caused by the entry of Ca(2+) from the extracellular space through ionotropic receptors and store-operated channels expressed in astrocytes. Plasmalemmal Ca(2+) ATP-ase and sodium-calcium exchanger extrude cytosolic Ca(2+) to the extracellular space; the exchanger can also operate in reverse, depending of the intercellular Na(+) concentration, to deliver Ca(2+) to the cytosol. The ER internal store possesses inositol 1,4,5-trisphosphate receptors which can be activated upon stimulation of astrocytes through a multiple plasma membrane metabotropic G-protein coupled receptors. This leads to release of Ca(2+) from the ER and its elevation in the cytosol, the level of which can be modulated by mitochondria. The mitochondrial uniporter takes up Ca(2+) into the matrix, while free Ca(2+) exits the matrix through the mitochondrial Na(+)/Ca(2+) exchanger as well as via transient openings of the mitochondrial permeability transition pore. One of the prominent consequences of astroglial Ca(2+) excitability is gliotransmission, a release of transmitters from astroglia which can lead to signalling to adjacent neurones.
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30
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Cenedese V, Betto G, Celsi F, Cherian OL, Pifferi S, Menini A. The voltage dependence of the TMEM16B/anoctamin2 calcium-activated chloride channel is modified by mutations in the first putative intracellular loop. ACTA ACUST UNITED AC 2012; 139:285-94. [PMID: 22412191 PMCID: PMC3315145 DOI: 10.1085/jgp.201110764] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Ca2+-activated Cl− channels (CaCCs) are involved in several physiological processes. Recently, TMEM16A/anoctamin1 and TMEM16B/anoctamin2 have been shown to function as CaCCs, but very little information is available on the structure–function relations of these channels. TMEM16B is expressed in the cilia of olfactory sensory neurons, in microvilli of vomeronasal sensory neurons, and in the synaptic terminals of retinal photoreceptors. Here, we have performed the first site-directed mutagenesis study on TMEM16B to understand the molecular mechanisms of voltage and Ca2+ dependence. We have mutated amino acids in the first putative intracellular loop and measured the properties of the wild-type and mutant TMEM16B channels expressed in HEK 293T cells using the whole cell voltage-clamp technique in the presence of various intracellular Ca2+ concentrations. We mutated E367 into glutamine or deleted the five consecutive glutamates 386EEEEE390 and 399EYE401. The EYE deletion did not significantly modify the apparent Ca2+ dependence nor the voltage dependence of channel activation. E367Q and deletion of the five glutamates did not greatly affect the apparent Ca2+ affinity but modified the voltage dependence, shifting the conductance–voltage relations toward more positive voltages. These findings indicate that glutamates E367 and 386EEEEE390 in the first intracellular putative loop play an important role in the voltage dependence of TMEM16B, thus providing an initial structure–function study for this channel.
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Affiliation(s)
- Valentina Cenedese
- Neurobiology Sector, International School for Advanced Studies, and Italian Institute of Technology, SISSA Unit, 34136 Trieste, Italy
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Huai J, Shao Y, Sun X, Jin Y, Wu J, Huang Z. Melatonin ameliorates acute necrotizing pancreatitis by the regulation of cytosolic Ca2+ homeostasis. Pancreatology 2012; 12:257-63. [PMID: 22687382 DOI: 10.1016/j.pan.2012.02.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 02/05/2012] [Accepted: 02/08/2012] [Indexed: 12/11/2022]
Abstract
OBJECTIVES This study aims to investigate the relationship between the protective effects of melatonin in pancreas and the expression of sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA) and Na(+)/Ca(2+) exchanger (NCX) in rats with acute necrotizing pancreatitis (ANP), to verify whether melatonin ameliorates ANP by alleviating calcium overload. METHODS Ninety-six male Sprague-Dawley rats were randomly divided into four groups (sham operation group, ANP group, melatonin treatment group, melatonin contrast group). ANP was induced by the retrograde injection of 4% taurocholate (1 ml/kg body weight) into the biliopancreatic duct. Melatonin (50 mg/kg body weight) was administered 30 min before the induction of ANP in the melatonin treatment group. Rats in each group were euthanized at 1, 4, and 8 h after ANP induction. Pancreatic tissues were removed to measure SERCA and NCX levels and cytosolic calcium ion (Ca(2+)) concentration ([Ca(2+)](i)). RESULTS At each time point, SERCA and NCX levels in the melatonin treatment group were significantly higher than that in the ANP group, and lower than that in the sham group and the melatonin contrast group. These levels did not differ between the 4- and 8-h time points in the ANP group. [Ca(2+)](i) in pancreatic acinar cells was higher in the melatonin treatment group than in the sham group and the melatonin contrast group, but lower than in the ANP group, at each time point. CONCLUSION Melatonin can reduce pancreatic damage via the up-regulation of SERCA and NCX expression, which can alleviate calcium overload in pancreatic acinar cells.
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Affiliation(s)
- Jiaping Huai
- Department of Gastroenterology and Hepatology, First Affiliated Hospital of Wenzhou Medical College, Wenzhou, 325000 Zhejiang, China
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Booth DM, Mukherjee R, Sutton R, Criddle DN. Calcium and reactive oxygen species in acute pancreatitis: friend or foe? Antioxid Redox Signal 2011; 15:2683-98. [PMID: 21861696 PMCID: PMC3183657 DOI: 10.1089/ars.2011.3983] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
SIGNIFICANCE Acute pancreatitis (AP) is a debilitating and, at times, lethal inflammatory disease, the causes and progression of which are incompletely understood. Disruption of Ca(2+) homeostasis in response to precipitants of AP leads to loss of mitochondrial integrity and cellular necrosis. RECENT ADVANCES While oxidative stress has been implicated as a major player in the pathogenesis of this disease, its precise roles remain to be defined. Recent developments are challenging the perception of reactive oxygen species (ROS) as nonspecific cytotoxic agents, suggesting that ROS promote apoptosis that may play a vital protective role in cellular stress since necrosis is avoided. CRITICAL ISSUES Fresh clinical findings have indicated that antioxidant treatment does not ameliorate AP and may actually worsen the outcome. This review explores the complex links between cellular Ca(2+) signaling and the intracellular redox environment, with particular relevance to AP. FUTURE DIRECTIONS Recent publications have underlined the importance of both Ca(2+) and ROS within the pathogenesis of AP, particularly in the determination of cell fate. Future research should elucidate the subtle interplay between Ca(2+) and redox mechanisms that operate to modulate mitochondrial function, with a view to devising strategies for the preservation of organellar function.
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Affiliation(s)
- David M Booth
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, Faculty of Health and Life Sciences, University of Liverpool, Liverpool, United Kingdom
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Petersen OH, Gerasimenko OV, Tepikin AV, Gerasimenko JV. Aberrant Ca(2+) signalling through acidic calcium stores in pancreatic acinar cells. Cell Calcium 2011; 50:193-9. [PMID: 21435718 DOI: 10.1016/j.ceca.2011.02.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Revised: 02/25/2011] [Accepted: 02/27/2011] [Indexed: 12/13/2022]
Abstract
Pancreatic acinar cells possess a very large Ca(2+) store in the endoplasmic reticulum, but also have extensive acidic Ca(2+) stores. Whereas the endoplasmic reticulum is principally located in the baso-lateral part of the cells, although with extensions into the granular area, the acidic stores are exclusively present in the apical part. The two types of stores can be differentiated pharmacologically because the endoplasmic reticulum accumulates Ca(2+) via SERCA pumps, whereas the acidic pools require functional vacuolar H(+) pumps in order to maintain a high intra-organellar Ca(2+) concentration. The human disease acute pancreatitis is initiated by trypsinogen activation in the apical pole and this is mostly due to either complications arising from gall bladder stones or excessive alcohol consumption. Attention has therefore been focussed on assessing the acute effects of bile acids as well as alcohol metabolites. The evidence accumulated so far indicates that bile acids and fatty acid ethyl esters - the non-oxidative products of alcohol and fatty acids - exert their pathological effects primarily by excessive Ca(2+) release from the acidic stores. This occurs by opening of the very same release channels that are also responsible for normal stimulus-secretion coupling, namely inositol trisphosphate and ryanodine receptors. The inositol trisphosphate receptors are of particular importance and the results of gene deletion experiments indicate that the fatty acid ethyl esters mainly utilize sub-types 2 and 3.
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Affiliation(s)
- O H Petersen
- MRC Secretory Control Group, Cardiff School of Biosciences, Cardiff University, Museum Avenue, Cardiff CF10 3AX, Wales, UK.
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Cheng KT, Liu X, Ong HL, Swaim W, Ambudkar IS. Local Ca²+ entry via Orai1 regulates plasma membrane recruitment of TRPC1 and controls cytosolic Ca²+ signals required for specific cell functions. PLoS Biol 2011; 9:e1001025. [PMID: 21408196 PMCID: PMC3050638 DOI: 10.1371/journal.pbio.1001025] [Citation(s) in RCA: 205] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Accepted: 01/27/2011] [Indexed: 11/18/2022] Open
Abstract
Store-operated Ca2+ entry (SOCE) has been associated with two types of channels: CRAC channels that require Orai1 and STIM1 and SOC channels that involve TRPC1, Orai1, and STIM1. While TRPC1 significantly contributes to SOCE and SOC channel activity, abrogation of Orai1 function eliminates SOCE and activation of TRPC1. The critical role of Orai1 in activation of TRPC1-SOC channels following Ca2+ store depletion has not yet been established. Herein we report that TRPC1 and Orai1 are components of distinct channels. We show that TRPC1/Orai1/STIM1-dependent ISOC, activated in response to Ca2+ store depletion, is composed of TRPC1/STIM1-mediated non-selective cation current and Orai1/STIM1-mediated ICRAC; the latter is detected when TRPC1 function is suppressed by expression of shTRPC1 or a STIM1 mutant that lacks TRPC1 gating, STIM1(684EE685). In addition to gating TRPC1 and Orai1, STIM1 mediates the recruitment and association of the channels within ER/PM junctional domains, a critical step in TRPC1 activation. Importantly, we show that Ca2+ entry via Orai1 triggers plasma membrane insertion of TRPC1, which is prevented by blocking SOCE with 1 µM Gd3+, removal of extracellular Ca2+, knockdown of Orai1, or expression of dominant negative mutant Orai1 lacking a functional pore, Orai1-E106Q. In cells expressing another pore mutant of Orai1, Orai1-E106D, TRPC1 trafficking is supported in Ca2+-containing, but not Ca2+-free, medium. Consistent with this, ICRAC is activated in cells pretreated with thapsigargin in Ca2+-free medium while ISOC is activated in cells pretreated in Ca2+-containing medium. Significantly, TRPC1 function is required for sustained KCa activity and contributes to NFκB activation while Orai1 is sufficient for NFAT activation. Together, these findings reveal an as-yet unidentified function for Orai1 that explains the critical requirement of the channel in the activation of TRPC1 following Ca2+ store depletion. We suggest that coordinated regulation of the surface expression of TRPC1 by Orai1 and gating by STIM1 provides a mechanism for rapidly modulating and maintaining SOCE-generated Ca2+ signals. By recruiting ion channels and other signaling pathways, Orai1 and STIM1 concertedly impact a variety of critical cell functions that are initiated by SOCE. Store-operated Ca2+ entry is present in all cell types and determines sustained cytosolic [Ca2+] increases that are critical for regulating a wide variety of physiological functions. This Ca2+ entry mechanism is activated in response to depletion of Ca2+ in the endoplasmic reticulum (ER). When ER [Ca2+] is decreased, the Ca2+-sensor protein STIM1 aggregates in the ER membrane and moves to regions in the periphery of the cells where it interacts with and activates two major types of channels that contribute to store-operated Ca2+ entry: CRAC and SOC. While gating of Orai1 by STIM1 is sufficient for CRAC channel activity, both Orai1 and transient receptor potential channel 1 (TRPC1) contribute to SOC channel function. The molecular composition of SOC channels and the critical role of Orai1 in activation of TRPC1 have not yet been established. In this study, we demonstrate that TRPC1 and Orai1 are components of distinct channels, both of which are regulated by STIM1. Importantly, we show that Orai1-mediated Ca2+ entry triggers plasma membrane insertion of TRPC1 which is then gated by STIM1. Ca2+ entry via functional TRPC1-STIM1 channels provides additional increase in cytosolic [Ca2+] that is required for regulation of specific cell functions such as KCa activation. Together, our findings elucidate the critical role of Orai1 in TRPC1 channel function. We suggest that the regulation of TRPC1 trafficking provides a mechanism for rapidly modulating cytosolic [Ca2+] following Ca2+ store depletion.
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Affiliation(s)
- Kwong Tai Cheng
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, Maryland, United States of America
| | - Xibao Liu
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, Maryland, United States of America
| | - Hwei Ling Ong
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, Maryland, United States of America
| | - William Swaim
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, Maryland, United States of America
| | - Indu S. Ambudkar
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, Maryland, United States of America
- * E-mail:
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Reed AM, Husain SZ, Thrower E, Alexandre M, Shah A, Gorelick FS, Nathanson MH. Low extracellular pH induces damage in the pancreatic acinar cell by enhancing calcium signaling. J Biol Chem 2011; 286:1919-26. [PMID: 21084290 PMCID: PMC3023488 DOI: 10.1074/jbc.m110.158329] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Revised: 11/01/2010] [Indexed: 01/30/2023] Open
Abstract
Low extracellular pH (pHe) occurs in a number of clinical conditions and sensitizes to the development of pancreatitis. The mechanisms responsible for this sensitization are unknown. Because abnormal Ca(2+) signaling underlies many of the early steps in the pathogenesis of pancreatitis, we evaluated the effect of decreasing pHe from 7.4 to 7.0 on Ca(2+) signals in the acinar cell. Low pHe significantly increased the amplitude of cerulein-induced Ca(2+) signals. The enhancement in amplitude was localized to the basolateral region of the acinar cell and was reduced by pretreatment with ryanodine receptor (RYR) inhibitors. Because basolateral RYRs also have been implicated in the pathogenesis of pancreatitis, we evaluated the effects of RYR inhibitors on pancreatitis responses in acidic conditions. RYR inhibitors significantly reduced the sensitizing effects of low pHe on zymogen activation and cellular injury. These findings suggest that enhanced RYR-mediated Ca(2+) signaling in the basolateral region of the acinar cell is responsible for the injurious effects of low pHe on the exocrine pancreas.
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Affiliation(s)
- Anamika M Reed
- Department of Internal Medicine, Section of Digestive Diseases, Yale University, New Haven, Connecticut 06515, USA.
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Abstract
Ca(2+) functions as an important signaling messenger right from beginning of life to the final moments of the end of life. Ca(2+) is needed at several steps of the cell cycle such as early G(1), at the G(1)/S, and G(2)/M transitions. The Ca(2+) signals in the form of time-dependent changes in intracellular Ca(2+) concentrations, [Ca(2+)](i), are presented as brief spikes organized into regenerative Ca(2+) waves. Ca(2+)-mediated signaling pathways have also been shown to play important roles in carcinogenesis such as transformation of normal cells to cancerous cells, tumor formation and growth, invasion, angiogenesis and metastasis. Since the global Ca(2+) oscillations arise from Ca(2+) waves initiated locally, it results in stochastic oscillations because although each cell has many IP(3)Rs and Ca(2+) ions, the law of large numbers does not apply to the initiating event which is restricted to very few IP(3)Rs due to steep Ca(2+) concentration gradients. The specific Ca(2+) signaling information is likely to be encoded in a calcium code as the amplitude, duration, frequency, waveform or timing of Ca(2+) oscillations and decoded again at a later stage. Since Ca(2+) channels or pumps involved in regulating Ca(2+) signaling pathways show altered expression in cancer, one can target these Ca(2+) channels and pumps as therapeutic options to decrease proliferation of cancer cells and to promote their apoptosis. These studies can provide novel insights into alterations in Ca(2+) wave patterns in carcinogenesis and lead to the development of newer technologies based on Ca(2+) waves for the diagnosis and therapy of cancer.
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Affiliation(s)
- Jai Parkash
- Robert Stempel College of Public Health and Social Work, Department of Environmental and Occupational Health, Florida International University, 11200 SW 8th Street, HLS-594, Miami, FL 33199, USA.
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Abstract
Acute pancreatitis (AP) is an important cause of morbidity and mortality worldwide and the annual incidence appears to be increasing. It presents as a mild self-limiting illness in 80% of patients. However, one-fifth of these develop a severe complicated life-threatening disease requiring intensive and prolonged therapeutic intervention. Alcohol and gallstone disease remain the commonest causes of AP but metabolic abnormalities, obesity and genetic susceptibility are thought be increasingly important aetiological factors. The prompt diagnosis of AP and stratification of disease severity is essential in directing rapid delivery of appropriate therapeutic measures. In this review, the range of diagnostic and prognostic assays, severity scoring systems and radiological investigations used in current clinical practice are described, highlighting their strengths and weaknesses. Increased understanding of the complex pathophysiology of AP has generated an array of new potential diagnostic assays and these are discussed. The multidisciplinary approach to management of severe pancreatitis is outlined, including areas of controversy and novel treatments.
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Affiliation(s)
- Simon J F Harper
- Department of Pancreaticobiliar Surgery, Luton & Dunstable NHS Foundation Trust, Lewsey Road, Luton, LU4 0DZ, UK.
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38
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Fernyhough P, Calcutt NA. Abnormal calcium homeostasis in peripheral neuropathies. Cell Calcium 2009; 47:130-9. [PMID: 20034667 DOI: 10.1016/j.ceca.2009.11.008] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Accepted: 11/17/2009] [Indexed: 01/02/2023]
Abstract
Abnormal neuronal calcium (Ca2+) homeostasis has been implicated in numerous diseases of the nervous system. The pathogenesis of two increasingly common disorders of the peripheral nervous system, namely neuropathic pain and diabetic polyneuropathy, has been associated with aberrant Ca2+ channel expression and function. Here we review the current state of knowledge regarding the role of Ca2+ dyshomeostasis and associated mitochondrial dysfunction in painful and diabetic neuropathies. The central impact of both alterations of Ca2+ signalling at the plasma membrane and also intracellular Ca2+ handling on sensory neurone function is discussed and related to abnormal endoplasmic reticulum performance. We also present new data highlighting sub-optimal axonal Ca2+ signalling in diabetic neuropathy and discuss the putative role for this abnormality in the induction of axonal degeneration in peripheral neuropathies. The accumulating evidence implicating Ca2+ dysregulation in both painful and degenerative neuropathies, along with recent advances in understanding of regional variations in Ca2+ channel and pump structures, makes modulation of neuronal Ca2+ handling an increasingly viable approach for therapeutic interventions against the painful and degenerative aspects of many peripheral neuropathies.
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Affiliation(s)
- Paul Fernyhough
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada R3E0T6.
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Criddle DN, Booth DM, Mukherjee R, McLaughlin E, Green GM, Sutton R, Petersen OH, Reeve JR. Cholecystokinin-58 and cholecystokinin-8 exhibit similar actions on calcium signaling, zymogen secretion, and cell fate in murine pancreatic acinar cells. Am J Physiol Gastrointest Liver Physiol 2009; 297:G1085-92. [PMID: 19815626 PMCID: PMC2850092 DOI: 10.1152/ajpgi.00119.2009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The gastrointestinal hormone CCK exists in various molecular forms, with differences in bioactivity between the well-characterized CCK-8 and larger CCK-58 previously reported. We have compared the effects of these peptides on cytosolic calcium concentration ([Ca(2+)](c)), mitochondrial metabolism, enzyme secretion, and cell fate in murine isolated pancreatic acinar cells using fluorescence confocal microscopy and patch-clamp electrophysiology. CCK-58 (1-10 pM) induced transient, oscillatory increases of [Ca(2+)](c), which showed apical to basolateral progression and were associated with a rise of mitochondrial NAD(P)H. CCK-58 (10 pM) induced zymogen exocytosis in isolated cells and amylase secretion from isolated cells and whole tissues. Hyperstimulation with supraphysiological CCK-58 (5 nM) induced a single large increase of [Ca(2+)](c) that declined to a plateau, which remained above the basal level 20 min after application and was dependent on external Ca(2+) entry. In cells dispersed from the same tissues, CCK-8 induced similar patterns of responses to those of CCK-58, with oscillatory increases of [Ca(2+)](c) at lower (pM) concentrations and sustained responses at 5 nM. CCK-58 and CCK-8 exhibited similar profiles of action on cell death, with increases in necrosis at high CCK-58 and CCK-8 (10 nM) that were not significantly different between peptides. The present experiments indicate that CCK-8 and CCK-58 have essentially identical actions on the acinar cell at high and low agonist concentrations, suggesting an action via the same receptor and that the differences observed in an intact rat model may result from indirect effects of the peptides. Our data strengthen the argument that CCK-58 is an important physiological form of this gastrointestinal hormone.
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Affiliation(s)
| | | | - Rajarshi Mukherjee
- 2Liverpool National Institute of Health Research Pancreatic Biomedical Research Unit, Royal Liverpool and Broadgreen University Hospitals, National Health Service Trust, Liverpool, United Kingdom;
| | - Euan McLaughlin
- 2Liverpool National Institute of Health Research Pancreatic Biomedical Research Unit, Royal Liverpool and Broadgreen University Hospitals, National Health Service Trust, Liverpool, United Kingdom;
| | - Gary M. Green
- 3University of Texas Health Science Center, San Antonio, Texas;
| | - Robert Sutton
- 2Liverpool National Institute of Health Research Pancreatic Biomedical Research Unit, Royal Liverpool and Broadgreen University Hospitals, National Health Service Trust, Liverpool, United Kingdom;
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Petersen OH, Tepikin AV, Gerasimenko JV, Gerasimenko OV, Sutton R, Criddle DN. Fatty acids, alcohol and fatty acid ethyl esters: toxic Ca2+ signal generation and pancreatitis. Cell Calcium 2009; 45:634-42. [PMID: 19327825 DOI: 10.1016/j.ceca.2009.02.005] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Revised: 02/17/2009] [Accepted: 02/19/2009] [Indexed: 01/11/2023]
Abstract
Pancreatitis, a potentially fatal disease in which the pancreas digests itself as well as its surroundings, is a well recognized complication of hyperlipidemia. Fatty acids have toxic effects on pancreatic acinar cells and these are mediated by large sustained elevations of the cytosolic Ca(2+) concentration. An important component of the effect of fatty acids is due to inhibition of mitochondrial function and subsequent ATP depletion, which reduces the operation of Ca(2+)-activated ATPases in both the endoplasmic reticulum and the plasma membrane. One of the main causes of pancreatitis is alcohol abuse. Whereas the effects of even high alcohol concentrations on isolated pancreatic acinar cells are variable and often small, fatty acid ethyl esters--synthesized by combination of alcohol and fatty acids--consistently evoke major Ca(2+) release from intracellular stores, subsequently opening Ca(2+) entry channels in the plasma membrane. The crucial trigger for pancreatic autodigestion is intracellular trypsin activation. Although there is still uncertainty about the exact molecular mechanism by which this Ca(2+)-dependent process occurs, progress has been made in identifying a subcellular compartment--namely acid post-exocytotic endocytic vacuoles--in which this activation takes place.
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Affiliation(s)
- O H Petersen
- MRC Secretory Control Research Group, Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Liverpool, UK.
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41
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TMEM16B induces chloride currents activated by calcium in mammalian cells. Pflugers Arch 2009; 458:1023-38. [PMID: 19475416 DOI: 10.1007/s00424-009-0684-9] [Citation(s) in RCA: 179] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2009] [Accepted: 05/13/2009] [Indexed: 10/20/2022]
Abstract
Ca(2+)-activated Cl(-) channels play important physiological roles in various cell types, but their molecular identity is still unclear. Recently, members of the protein family named transmembrane 16 (TMEM16) have been suggested to function as Ca(2+)-activated Cl(-) channels. Here, we report the functional properties of mouse TMEM16B (mTMEM16B) expressed in human embryonic kidney (HEK) 293T cells, measured both in the whole-cell configuration and in inside-out excised patches. In whole cell, a current induced by mTMEM16B was activated by intracellular Ca(2+) diffusing from the patch pipette, released from intracellular stores through activation of a G-protein-coupled receptor, or photoreleased from caged Ca(2+) inside the cell. In inside-out membrane patches, a current was rapidly activated by bath application of controlled Ca(2+) concentrations, indicating that mTMEM16B is directly gated by Ca(2+). Both in the whole-cell and in the inside-out configurations, the Ca(2+)-induced current was anion selective, blocked by the Cl(-) channel blocker niflumic acid, and displayed a Ca(2+)-dependent rectification. In inside-out patches, Ca(2+) concentration for half-maximal current activation decreased from 4.9 microM at -50 mV to 3.3 microM at +50 mV, while the Hill coefficient was >2. In inside-out patches, currents showed a reversible current decrease at -50 mV in the presence of a constant high Ca(2+) concentration and, moreover, an irreversible rundown, not observed in whole-cell recordings, indicating that some unknown modulator was lost upon patch excision. Our results demonstrate that mTMEM16B functions as a Ca(2+)-activated Cl(-) channel when expressed in HEK 293T cells.
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Di Capite J, Ng SW, Parekh AB. Decoding of cytoplasmic Ca(2+) oscillations through the spatial signature drives gene expression. Curr Biol 2009; 19:853-8. [PMID: 19375314 DOI: 10.1016/j.cub.2009.03.063] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 03/19/2009] [Accepted: 03/19/2009] [Indexed: 11/15/2022]
Abstract
Cytoplasmic Ca(2+) oscillations are a universal signaling mode that activates numerous cellular responses [1, 2]. Oscillations are considered the physiological mechanism of Ca(2+) signaling because they occur at low levels of stimulus intensity [3]. Ca(2+) oscillations are proposed to convey information in their amplitude and frequency, leading to activation of specific downstream targets [4-6]. Here, we report that the spatial Ca(2+) gradient within the oscillation is key. Ca(2+) oscillations in mast cells evoked over a range of agonist concentrations in the presence of external Ca(2+) were indistinguishable from those in the absence of Ca(2+) when plasmalemmal Ca(2+) extrusion was suppressed. Nevertheless, only oscillations with accompanying Ca(2+) entry through store-operated CRAC channels triggered gene expression. Increased cytoplasmic Ca(2+) buffering prevented oscillations but not gene activation. Local Ca(2+) influx and not global Ca(2+) oscillations therefore drives gene expression at physiological levels of stimulation. Rather than serving to maintain Ca(2+) oscillations by replenishing stores, we suggest that the role of oscillations might be to activate CRAC channels, thereby ensuring the generation of spatially restricted physiological Ca(2+) signals driving gene activation. Furthermore, we show that the spatial profile of a Ca(2+) oscillation provides a novel mechanism whereby a pleiotropic messenger specifically activates gene expression.
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Affiliation(s)
- Joseph Di Capite
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford OX1 3PT, UK
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Gomez-Pinilla PJ, Camello PJ, Pozo MJ. Pancreatic calcium signaling: role in health and disease. Pancreatology 2009; 9:329-33. [PMID: 19451741 DOI: 10.1159/000213412] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In order to control cell functions, extracellular agents, such as hormones or neurotransmitters among others, generate a diversity of calcium (Ca(2+)) signals in target cells. Here, we review the components involved in Ca(2+) handling and effectors, both members of the known calcium signaling pathways. In the pancreas, Ca(2+) signal appears as local increases, global elevations or Ca(2+) oscillations. Ca(2+) plays a key role in the pancreatic cells, regulating secretion in exocrine cells, a widely used model for studying the coupling between Ca(2+) signaling and secretion, and the release of insulin, glucagon and somatostatin in the exocrine pancreas. Interestingly, Ca(2+) deregulations have been related to pancreatitis and aging of the pancreas, and treatment with melatonin has shown beneficial effects suggesting that melatonin could be an adequate therapeutic approach.
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Affiliation(s)
- Pedro J Gomez-Pinilla
- Department of Physiology, Nursing School, University of Extremadura, Cáceres, Spain.
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44
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Hoffmann EK, Lambert IH, Pedersen SF. Physiology of cell volume regulation in vertebrates. Physiol Rev 2009; 89:193-277. [PMID: 19126758 DOI: 10.1152/physrev.00037.2007] [Citation(s) in RCA: 1061] [Impact Index Per Article: 66.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The ability to control cell volume is pivotal for cell function. Cell volume perturbation elicits a wide array of signaling events, leading to protective (e.g., cytoskeletal rearrangement) and adaptive (e.g., altered expression of osmolyte transporters and heat shock proteins) measures and, in most cases, activation of volume regulatory osmolyte transport. After acute swelling, cell volume is regulated by the process of regulatory volume decrease (RVD), which involves the activation of KCl cotransport and of channels mediating K(+), Cl(-), and taurine efflux. Conversely, after acute shrinkage, cell volume is regulated by the process of regulatory volume increase (RVI), which is mediated primarily by Na(+)/H(+) exchange, Na(+)-K(+)-2Cl(-) cotransport, and Na(+) channels. Here, we review in detail the current knowledge regarding the molecular identity of these transport pathways and their regulation by, e.g., membrane deformation, ionic strength, Ca(2+), protein kinases and phosphatases, cytoskeletal elements, GTP binding proteins, lipid mediators, and reactive oxygen species, upon changes in cell volume. We also discuss the nature of the upstream elements in volume sensing in vertebrate organisms. Importantly, cell volume impacts on a wide array of physiological processes, including transepithelial transport; cell migration, proliferation, and death; and changes in cell volume function as specific signals regulating these processes. A discussion of this issue concludes the review.
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Affiliation(s)
- Else K Hoffmann
- Department of Biology, University of Copenhagen, Copenhagen, Denmark.
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45
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Spät A, Fülöp L, Koncz P, Szanda G. When is high-Ca+ microdomain required for mitochondrial Ca+ uptake? Acta Physiol (Oxf) 2009; 195:139-47. [PMID: 18983456 DOI: 10.1111/j.1748-1716.2008.01928.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ca(2+) release from IP(3)-sensitive stores in the endoplasmic reticulum (ER) induced by Ca(2+)-mobilizing agonists generates high-Ca(2+) microdomains between ER vesicles and neighbouring mitochondria. Here we present a model that describes when such microdomains are required and when submicromolar [Ca(2+)] is sufficient for mitochondrial Ca(2+) uptake. Mitochondrial Ca(2+) uptake rate in angiotensin II-stimulated H295R adrenocortical cells correlates with the proximity between ER vesicles and the mitochondrion, reflecting the uptake promoting effect of high-Ca(2+) peri-mitochondrial microdomains. Silencing or inhibition of p38 mitogen-activated protein kinase (MAPK) or inhibition of the novel isoforms of protein kinase C enhances mitochondrial Ca(2+) uptake and abolishes the positive correlation between Ca(2+) uptake and ER-mitochondrion proximity. Inhibition of protein phosphatases attenuates mitochondrial Ca(2+) uptake and also abolishes its positive correlation with ER-mitochondrion proximity. We postulate that during IP(3)-induced Ca(2+) release, Ca(2+) uptake is confined to ER-close mitochondria, because of the simultaneous activation of the protein kinases. Attenuation of Ca(2+) uptake prevents Ca(2+) overload of mitochondria and thus protects the cell against apoptosis. On the other hand, all the mitochondria accumulate Ca(2+) at a non-inhibited rate during physiological Ca(2+) influx through the plasma membrane. Membrane potential is higher in ER-distant mitochondria, providing a bigger driving force for Ca(2+) uptake. Our model explains why comparable mitochondrial Ca(2+) signals are formed in response to K(+) and angiotensin II (equipotent in respect to global cytosolic Ca(2+) signals), although only the latter generates high-Ca(2+) microdomains.
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Affiliation(s)
- A Spät
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary.
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Abstract
AIM Hydrogen peroxide (H2O2) is produced during liver transplantation. Ischemia/reperfusion induces oxidation and causes intracellular Ca2+ overload, which harms liver cells. Our goal was to determine the precise mechanisms of these processes. METHODS Hepatocytes were extracted from rats. Intracellular Ca2+ concentrations ([Ca2+](i)), inner mitochondrial membrane potentials and NAD(P)H levels were measured using fluorescence imaging. Phospholipase C (PLC) activity was detected using exogenous PIP2. ATP concentrations were measured using the luciferin-luciferase method. Patch-clamp recordings were performed to evaluate membrane currents. RESULTS H2O2 increased intracellular Ca2+ concentrations ([Ca2+](i)) across two kinetic phases. A low concentration (400 micromol/L) of H2O2 induced a sustained elevation of [Ca2+](i) that was reversed by removing extracellular Ca2+. H2O2 increased membrane currents consistent with intracellular ATP concentrations. The non-selective ATP-sensitive cation channel blocker amiloride inhibited H2O2-induced membrane current increases and [Ca2+](i) elevation. A high concentration (1 mmol/L)of H2O2 induced an additional transient elevation of [Ca2+](i), which was abolished by the specific PLC blocker U73122 but was not eliminated by removal of extracellular Ca2+. PLC activity was increased by 1 mmol/L H2O2 but not by 400 micromol/L H2O2. CONCLUSIONS H2O2 mobilizes Ca2+ through two distinct mechanisms. In one, 400 micromol/L H2O2-induced sustained [Ca2+](i) elevation is mediated via a Ca2+ influx mechanism, under which H2O2 impairs mitochondrial function via oxidative stress,reduces intracellular ATP production, and in turn opens ATP-sensitive, non-specific cation channels, leading to Ca2+ influx.In contrast, 1 mmol/L H2O2-induced transient elevation of [Ca2+](i) is mediated via activation of the PLC signaling pathway and subsequently, by mobilization of Ca2+ from intracellular Ca2+ stores.
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Petersen OH. Ca2+ signaling in pancreatic acinar cells: physiology and pathophysiology. Braz J Med Biol Res 2009; 42:9-16. [PMID: 19219293 DOI: 10.1590/s0100-879x2009000100003] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2008] [Accepted: 12/16/2008] [Indexed: 11/22/2022] Open
Abstract
The pancreatic acinar cell is a classical model for studies of secretion and signal transduction mechanisms. Because of the extensive endoplasmic reticulum and the large granular compartment, it has been possible--by direct measurements--to obtain considerable insights into intracellular Ca2+ handling under both normal and pathological conditions. Recent studies have also revealed important characteristics of stimulus-secretion coupling mechanisms in isolated human pancreatic acinar cells. The acinar cells are potentially dangerous because of the high intra-granular concentration of proteases, which become inappropriately activated in the human disease acute pancreatitis. This disease is due to toxic Ca2+ signals generated by excessive liberation of Ca2+ from both the endoplasmic reticulum and the secretory granules.
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Affiliation(s)
- O H Petersen
- MRC Group, Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Liverpool, UK.
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Parekh AB. Local Ca2+ influx through CRAC channels activates temporally and spatially distinct cellular responses. Acta Physiol (Oxf) 2009; 195:29-35. [PMID: 18983453 DOI: 10.1111/j.1748-1716.2008.01919.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Ca(2+) entry through store-operated Ca(2+) release-activated Ca(2+) (CRAC) channels controls a disparate array of key cellular responses. In this review, recent work will be described that shows local Ca(2+) influx through CRAC channels has important spatial and temporal consequences on cell function. A localized Ca(2+) rise below the plasma membrane activates, within tens of seconds, catabolic enzymes resulting in the generation of the intracellular messenger arachidonic acid and the paracrine pro-inflammatory molecule LTC(4). In addition, local Ca(2+) entry can activate gene expression, which develops over tens of minutes. Local Ca(2+) influx through CRAC channels therefore has far-reaching consequences on intra- and intercellular communication.
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Affiliation(s)
- A B Parekh
- Department of Physiology, Anatomy and Genetics, Oxford University, Oxford, UK.
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Alonso MT, Manjarrés IM, García-Sancho J. Modulation of calcium signalling by intracellular organelles seen with targeted aequorins. Acta Physiol (Oxf) 2009; 195:37-49. [PMID: 18983457 DOI: 10.1111/j.1748-1716.2008.01920.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The cytosolic Ca(2+) signals that trigger cell responses occur either as localized domains of high Ca(2+) concentration or as propagating Ca(2+) waves. Cytoplasmic organelles, taking up or releasing Ca(2+) to the cytosol, shape the cytosolic signals. On the other hand, Ca(2+) concentration inside organelles is also important in physiology and pathophysiology. Comprehensive study of these matters requires to measure [Ca(2+)] inside organelles and at the relevant cytosolic domains. Aequorins, the best-known chemiluminescent Ca(2+) probes, are excellent for this end as they do not require stressing illumination, have a large dynamic range and a sharp Ca(2+)-dependence, can be targeted to the appropriate location and engineered to have the proper Ca(2+) affinity. Using this methodology, we have evidenced the existence in chromaffin cells of functional units composed by three closely interrelated elements: (1) plasma membrane Ca(2+) channels, (2) subplasmalemmal endoplasmic reticulum and (3) mitochondria. These Ca(2+)-signalling triads optimize Ca(2+) microdomains for secretion and prevent propagation of the Ca(2+) wave towards the cell core. Oscillatory cytosolic Ca(2+) signals originate also oscillations of mitochondrial Ca(2+) in several cell types. The nuclear envelope slows down the propagation of the Ca(2+) wave to the nucleus and filters high frequencies. On the other hand, inositol-trisphosphate may produce direct release of Ca(2+) to the nucleoplasm in GH(3) pituitary cells, thus providing mechanisms for selective nuclear signalling. Aequorins emitting at different wavelengths, prepared by fusion either with green or red fluorescent protein, permit simultaneous and independent monitorization of the Ca(2+) signals in different subcellular domains within the same cell.
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Affiliation(s)
- M T Alonso
- Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Valladolid, Spain
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Abstract
Cell volume perturbation initiates a wide array of intracellular signalling cascades, leading to protective and adaptive events and, in most cases, activation of volume-regulatory osmolyte transport, water loss, and hence restoration of cell volume and cellular function. Cell volume is challenged not only under physiological conditions, e.g. following accumulation of nutrients, during epithelial absorption/secretion processes, following hormonal/autocrine stimulation, and during induction of apoptosis, but also under pathophysiological conditions, e.g. hypoxia, ischaemia and hyponatremia/hypernatremia. On the other hand, it has recently become clear that an increase or reduction in cell volume can also serve as a specific signal in the regulation of physiological processes such as transepithelial transport, cell migration, proliferation and death. Although the mechanisms by which cell volume perturbations are sensed are still far from clear, significant progress has been made with respect to the nature of the sensors, transducers and effectors that convert a change in cell volume into a physiological response. In the present review, we summarize recent major developments in the field, and emphasize the relationship between cell volume regulation and organism physiology/pathophysiology.
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Affiliation(s)
- I H Lambert
- Department of Biology, University of Copenhagen, Copenhagen, Denmark.
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