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1
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Yigit G, Kaulfuß S, Wollnik B. Understanding inherited cardiomyopathies: clinical aspects and genetic determinants. MED GENET-BERLIN 2025; 37:103-111. [PMID: 40207042 PMCID: PMC11976403 DOI: 10.1515/medgen-2025-2007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2025]
Abstract
Cardiomyopathies (CMs) are a clinically heterogeneous group of cardiovascular diseases characterized by structural and functional abnormalities of the heart muscle in the absence of coronary artery disease, hypertension, valve disease, or congenital heart disease as a leading cause. The phenotypic spectrum of CMs ranges from silent heart failure to symptomatic heart failure and sudden cardiac death, and CMs are one of the leading causes of cardiovascular morbidity worldwide. CMs are highly heritable, although a clear distinction between inherited and acquired forms remains challenging, particularly due to observed incomplete penetrance and variable expressivity of inherited CMs. Based on their specific morphological phenotypes and functional characteristics, CMs can be divided into at least 5 different subgroups: hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), arrhythmogenic cardiomyopathy (ACM), restrictive cardiomyopathy (RCM), and (left ventricular) non-compaction cardiomyopathy (LVNC), which show both clinical as well as genetic overlap. Since the identification of pathogenic variants in MYH7 as a genetic cause of HCM in 1990, enormous progress has been made in understanding genetic factors contributing to cardiomyopathies. Currently, over 100 genes have been associated with at least one of the CM subtypes, providing a deeper understanding of the cellular basis of genetic heart failure syndromes, unveiling new insights into the molecular biology of heart function in both health and disease, and, thereby, facilitating the development of novel therapeutic strategies and personalized treatment approaches.
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Affiliation(s)
- Gökhan Yigit
- Institute of Human GeneticsUniversity Medical Center GöttingenHeinrich-Düker-Weg 1237073GöttingenGermany
| | - Silke Kaulfuß
- Institute of Human GeneticsUniversity Medical Center GöttingenHeinrich-Düker-Weg 1237073GöttingenGermany
| | - Bernd Wollnik
- Georg-August University GöttingenInstitute of Human GeneticsHeinrich-Düker-Weg 1237073GöttingenGermany
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2
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Elst T, Weidner S, Tomalka A, Hahn D, Paternoster FK, Seiberl W, Siebert T. Consecutive SSCs increase the SSC effect in skinned rat muscle fibres. Pflugers Arch 2025; 477:873-888. [PMID: 40338284 DOI: 10.1007/s00424-025-03088-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2024] [Revised: 04/03/2025] [Accepted: 04/22/2025] [Indexed: 05/09/2025]
Abstract
Muscle function is essential for generating force and movement, with stretch-shortening cycles (SSCs) playing a fundamental role in the economy of everyday locomotion. Compared with pure shortening contractions, the SSC effect is characterised by increased force, work, and power output during the SSC shortening phase. Few studies have investigated whether SSC effects transfer across consecutive SSCs. Therefore, we investigated SSC effects over three consecutive SSCs in skinned rat muscle fibres by analysing the isometric force immediately before stretch onset (Fonset), the peak force at the end of stretching (Fpeak), and the minimum force at the end of shortening (Fmin), along with mechanical (WorkSSC) and shortening work (WorkSHO) at different activation levels (20%, 60%, and 100%). Each SSC was followed by an isometric hold phase, allowing force to return to a steady state. Results indicated an increase in both Fpeak (20.3%) and WorkSSC (60.9%) from SSC1 to SSC3 across all activation levels tested. At 20% and 60% activation, Fonset, Fmin, and WorkSHO increased (range: 4.5-28.5%) from SSC1 to SSC3. However, at 100% activation, Fonset and WorkSHO remained unchanged, while Fmin decreased (- 8.5%) from SSC1 to SSC3. These results suggest that the increase in SSC effects at submaximal activation may be primarily due to increased cross-bridge forces. The absence of increases in Fonset, Fmin, and WorkSHO at 100% activation suggests that increases in Fpeak and WorkSSC may not be attributed to increased cross-bridge force but could instead be caused by additional effects, possibly involving modulation of non-cross-bridge structures, likely titin, and their stiffness.
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Affiliation(s)
- Tobias Elst
- Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany.
| | - Sven Weidner
- Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - André Tomalka
- Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Daniel Hahn
- Human Movement Science, Faculty of Sports Science, Ruhr University Bochum, Bochum, Germany
- School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, QLD, Australia
| | - Florian Kurt Paternoster
- Biomechanics in Sports, Department of Sport and Health Sciences, Technical University of Munich, Munich, Germany
| | - Wolfgang Seiberl
- Human Movement Science, University of the Bundeswehr Munich, Neubiberg, Germany
| | - Tobias Siebert
- Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
- Stuttgart Center for Simulation Science, University of Stuttgart, Stuttgart, Germany
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3
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Kellermayer D, Șulea CM, Tordai H, Benke K, Pólos M, Ágg B, Stengl R, Csonka M, Radovits T, Merkely B, Szabolcs Z, Kellermayer M, Kiss B. Marfan syndrome cardiomyocytes show excess of titin isoform N2BA and extended sarcomeric M-band. J Gen Physiol 2025; 157:e202413690. [PMID: 40062891 PMCID: PMC11893164 DOI: 10.1085/jgp.202413690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2024] [Revised: 12/09/2024] [Accepted: 01/21/2025] [Indexed: 05/13/2025] Open
Abstract
Marfan syndrome (MFS) is an autosomal dominant disease caused by mutations in the gene (FBN1) of fibrillin-1, a major determinant of the extracellular matrix (ECM). Functional impairment in the cardiac left ventricle (LV) of these patients is usually a consequence of aortic valve disease. However, LV passive stiffness may also be affected by chronic changes in mechanical load and ECM dysfunction. Passive stiffness is determined by the giant sarcomeric protein titin that has two main cardiac splice isoforms: the shorter and stiffer N2B and the longer and more compliant N2BA. Their ratio is thought to reflect myocardial response to pathologies. Whether this ratio and titin's sarcomeric layout is altered in MFS is currently unknown. Here, we studied LV samples from MFS patients carrying FBN1 mutation, collected during aortic root replacement surgery. We found that the N2BA:N2B titin ratio was elevated, indicating a shift toward the more compliant isoform. However, there were no alterations in the total titin content compared with healthy humans based on literature data. Additionally, while the gross sarcomeric structure was unaltered, the M-band was more extended in the MFS sarcomere. We propose that the elevated N2BA:N2B titin ratio reflects a general adaptation mechanism to the increased volume overload resulting from the valvular disease and the direct ECM disturbances so as to reduce myocardial passive stiffness and maintain diastolic function in MFS.
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Affiliation(s)
- Dalma Kellermayer
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
- Heart and Vascular Center, Semmelweis University, Budapest, Hungary
| | - Cristina M. Șulea
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
- Heart and Vascular Center, Semmelweis University, Budapest, Hungary
- Hungarian Marfan Foundation, Budapest, Hungary
| | - Hedvig Tordai
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - Kálmán Benke
- Heart and Vascular Center, Semmelweis University, Budapest, Hungary
- Hungarian Marfan Foundation, Budapest, Hungary
| | - Miklós Pólos
- Heart and Vascular Center, Semmelweis University, Budapest, Hungary
- Hungarian Marfan Foundation, Budapest, Hungary
| | - Bence Ágg
- Heart and Vascular Center, Semmelweis University, Budapest, Hungary
- Hungarian Marfan Foundation, Budapest, Hungary
- Center for Pharmacology and Drug Research and Development, Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
| | - Roland Stengl
- Heart and Vascular Center, Semmelweis University, Budapest, Hungary
- Hungarian Marfan Foundation, Budapest, Hungary
| | - Máté Csonka
- Heart and Vascular Center, Semmelweis University, Budapest, Hungary
- Hungarian Marfan Foundation, Budapest, Hungary
| | - Tamás Radovits
- Heart and Vascular Center, Semmelweis University, Budapest, Hungary
| | - Béla Merkely
- Heart and Vascular Center, Semmelweis University, Budapest, Hungary
| | - Zoltán Szabolcs
- Heart and Vascular Center, Semmelweis University, Budapest, Hungary
- Hungarian Marfan Foundation, Budapest, Hungary
| | - Miklós Kellermayer
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
- HUN-REN-SU Biophysical Virology Research Group, Budapest, Hungary
| | - Balázs Kiss
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
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Wang Y, Ye J, Liu X, Zhang Z, Shang F, Qi X, Zhang Y, Du J, Sun H, Xu J, Chen H, Yu M, Le S. Mechanically weak and highly dynamic state of mechanosensitive titin Ig domains induced by proline isomerization. Nat Commun 2025; 16:2771. [PMID: 40113761 PMCID: PMC11926396 DOI: 10.1038/s41467-025-57989-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2024] [Accepted: 03/07/2025] [Indexed: 03/22/2025] Open
Abstract
Titin, essential for mechano-homeostasis in cardiac and skeletal sarcomere, contains numerous mechanosensitive immunoglobulin-like (Ig) domains in its I-band region. However, how proline isomerization and cysteine-mediated disulfide bond collectively regulate Ig domain dynamics within the physiological force range remains unclear. Here, we use single-molecule force spectroscopy to quantify the proximal Ig1 domain, revealing that proline isomerization leads to two native states-trans and cis states-with distinct mechanical and thermal stabilities. The trans-Ig1 unfolds at forces of ~ 5 pN, which is over 50 pN lower than that of cis-Ig1, and unfolds 1000 times faster under physiological forces. Furthermore, such proline induced dual-state is likely shared feature across majority of I-band Ig domains. Additionally, reduced cis- and trans-Ig1 exhibit catch-slip bond unfolding, while oxidized forms display slip-catch-slip unfolding. This study offers insight into effective modulation of proline isomerization and disulfide bond in regulating mechanosensitive proteins within the physiological force range.
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Affiliation(s)
- Yukai Wang
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Xiamen University, Xiamen, China
- Department of Biochemistry and Division of Orthopaedic Surgery of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Jiaqing Ye
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Xiamen University, Xiamen, China
| | - Xian Liu
- Department of Biochemistry and Division of Orthopaedic Surgery of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Zhuwei Zhang
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Xiamen University, Xiamen, China
| | - Fei Shang
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Xiamen University, Xiamen, China
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, China
| | - Xingyu Qi
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Xiamen University, Xiamen, China
| | - Yuhang Zhang
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Xiamen University, Xiamen, China
| | - Jingyi Du
- Department of Biochemistry and Division of Orthopaedic Surgery of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Hao Sun
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Xiamen University, Xiamen, China
- Center of Biomedical Physics, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, China
| | - Jiashu Xu
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Xiamen University, Xiamen, China
| | - Hu Chen
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Xiamen University, Xiamen, China.
- Center of Biomedical Physics, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, China.
| | - Miao Yu
- Department of Biochemistry and Division of Orthopaedic Surgery of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
| | - Shimin Le
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Xiamen University, Xiamen, China.
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Stańczak M, Swinnen B, Kacprzak B, Pacek A, Surmacz J. Neurophysiology of ACL Injury. Orthop Rev (Pavia) 2025; 17:129173. [PMID: 39980496 PMCID: PMC11842161 DOI: 10.52965/001c.129173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2024] [Accepted: 12/06/2024] [Indexed: 02/22/2025] Open
Abstract
The neurophysiology of ACL injury extends beyond the mechanical rupture of the ligament to encompass profound alterations in the central and peripheral nervous systems, impacting sensorimotor integration and neuromuscular control. The ACL, densely populated with mechanoreceptors, plays a critical role in joint proprioception, dynamically regulating knee stability through complex neural circuits that connect to the spinal cord and brain. When disrupted by injury, these neural pathways contribute to delayed muscular activation, altered motor planning, and compromised joint stability. Such neuromechanical deficits increase the likelihood of reinjury and highlight the need for comprehensive neuroplastic rehabilitation. Neuroplastic therapy, employing tools like external focus strategies, stroboscopic glasses, smartboards, and virtual reality, aims to restore and enhance neural connectivity, sensory integration, and motor coordination. These advanced tools target distinct phases of motor learning, promoting automaticity and resilience in movement patterns. By integrating visual-cognitive, proprioceptive, and reflexive controls, this therapeutic approach not only accelerates recovery but also optimizes performance and reduces the risk of re-injury, representing a paradigm shift in ACL rehabilitation.
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Affiliation(s)
- Mikołaj Stańczak
- AECC University College, Bournemouth, United Kingdom
- Rehab Performance, Lublin, Poland
| | - Bram Swinnen
- Integrated Performance Training, Hasselt, Belgium
| | | | - Artur Pacek
- University of Zielona Góra, Zielona Góra, Poland
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Lee S, Jo K, Choi YS, Jung S. Tracking bioactive peptides and their origin proteins during the in vitro digestion of meat and meat products. Food Chem 2024; 454:139845. [PMID: 38820629 DOI: 10.1016/j.foodchem.2024.139845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Revised: 05/17/2024] [Accepted: 05/24/2024] [Indexed: 06/02/2024]
Abstract
Existing reviews address bioactive peptides of meat proteins; however, comprehensive reviews summarizing the released sequences and their corresponding parent meat proteins in the digesta are limited. This review explores the bioactive peptides released during the in vitro gastrointestinal (GI) digestion of meat, connecting with parent proteins. The primary bioactivities of meat-derived peptides include angiotensin-converting enzyme (ACE) and dipeptidyl peptidase (DPP)-IV inhibition and antioxidant effects. Myofibrillar, sarcoplasmic, and stromal proteins play a significant role in peptide release during digestion. The release of bioactive peptides varies according to the parent protein and cryptides had short chains, non-toxicity, and great bioavailability and GI absorption scores. Moreover, the structural stability and bioactivities of peptides can be influenced by the digestive properties and amino acid composition of parent proteins. Investigating the properties and origins of bioactive peptides provides insights for enhancing the nutritional quality of meat and understanding its potential health benefits.
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Affiliation(s)
- Seonmin Lee
- Division of Animal and Dairy Science, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Kyung Jo
- Division of Animal and Dairy Science, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Yun-Sang Choi
- Research Group of Food Processing, Korea Food Research Institute, Wanju 55365, Republic of Korea
| | - Samooel Jung
- Division of Animal and Dairy Science, Chungnam National University, Daejeon 34134, Republic of Korea.
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7
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Kodali N, Alomary S, Bhattaru A, Eldaboush A, Schwartz RA, Lipner SR. Gender and melanoma subtype-based prognostic implications of MUC16 and TTN co-occurrent mutations in melanoma: A retrospective multi-study analysis. Cancer Med 2024; 13:e70199. [PMID: 39240165 PMCID: PMC11378355 DOI: 10.1002/cam4.70199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 08/22/2024] [Accepted: 08/26/2024] [Indexed: 09/07/2024] Open
Abstract
BACKGROUND Most primary cutaneous melanomas have pathogenesis driven by ultraviolet exposure and genetic mutations, whereas acral lentiginous melanoma (ALM) and metastatic melanoma are much less, if at all, linked with the former. Thus, we evaluated both ultraviolet related and non-ultraviolet related melanomas. Mutations in the MUC16 and TTN genes commonly occur concurrently in these melanoma patients, but their combined prognostic significance stratified by gender and cancer subtype remains unclear. METHODS The cBioPortal database was queried for melanoma studies and returned 16 independent studies. Data from 2447 melanoma patients were utilized including those with ALM, cutaneous melanoma (CM), and melanoma of unknown primary (MUP). Patients were grouped based on the presence or absence of MUC16 and TTN mutations. Univariate Cox regression and Student's t-tests were used to analyze hazard ratios and total mutation count comparisons, respectively. RESULTS TTN mutations, either alone or concurrently with MUC16 mutations, significantly correlated with worse prognosis overall, in both genders, and in CM patients. ALM patients with both mutations had better prognoses than CM patients, while ALM patients with neither mutation had worse prognosis than CM patients. For MUP patients, only MUC16 mutations correlated with worse prognosis. ALM patients with neither MUC16 nor TTN mutations had significantly more total mutations than MUP patients, followed by CM patients. CONCLUSION TTN mutations are a potential marker of poor prognosis in melanoma, which is amplified in the presence of concurrent MUC16 mutations. ALM patients with neither gene mutations had worse prognosis, suggesting a protective effect of having both MUC16 and TTN mutations. Only MUC16 mutations conferred a worse prognosis for MUP patients. Comprehensive genetic profiling in melanoma patients may facilitate personalized treatment strategies to optimize patient outcomes.
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Affiliation(s)
- Nilesh Kodali
- Rutgers New Jersey Medical SchoolNewarkNew JerseyUSA
| | | | | | - Ahmed Eldaboush
- Department of DermatologyPerelman School of Medicine, University of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | | | - Shari R. Lipner
- Department of DermatologyWeill Cornell MedicineNew YorkNew YorkUSA
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Stroik D, Gregorich ZR, Raza F, Ge Y, Guo W. Titin: roles in cardiac function and diseases. Front Physiol 2024; 15:1385821. [PMID: 38660537 PMCID: PMC11040099 DOI: 10.3389/fphys.2024.1385821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Accepted: 03/25/2024] [Indexed: 04/26/2024] Open
Abstract
The giant protein titin is an essential component of muscle sarcomeres. A single titin molecule spans half a sarcomere and mediates diverse functions along its length by virtue of its unique domains. The A-band of titin functions as a molecular blueprint that defines the length of the thick filaments, the I-band constitutes a molecular spring that determines cell-based passive stiffness, and various domains, including the Z-disk, I-band, and M-line, serve as scaffolds for stretch-sensing signaling pathways that mediate mechanotransduction. This review aims to discuss recent insights into titin's functional roles and their relationship to cardiac function. The role of titin in heart diseases, such as dilated cardiomyopathy and heart failure with preserved ejection fraction, as well as its potential as a therapeutic target, is also discussed.
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Affiliation(s)
- Dawson Stroik
- Cellular and Molecular Pathology Program, Department of Pathology and Laboratory Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
- Department of Animal and Dairy Sciences, College of Agriculture and Life Science, University of Wisconsin-Madison, Madison, WI, United States
| | - Zachery R. Gregorich
- Department of Animal and Dairy Sciences, College of Agriculture and Life Science, University of Wisconsin-Madison, Madison, WI, United States
| | - Farhan Raza
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
| | - Ying Ge
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
| | - Wei Guo
- Cellular and Molecular Pathology Program, Department of Pathology and Laboratory Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
- Department of Animal and Dairy Sciences, College of Agriculture and Life Science, University of Wisconsin-Madison, Madison, WI, United States
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ElSaygh J, Zaher A, Peterson SJ, Parikh MA, Frishman WH. Titin: The Missing Link in Cardiac Physiology. Cardiol Rev 2024:00045415-990000000-00209. [PMID: 38334419 DOI: 10.1097/crd.0000000000000656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
Titin, an extraordinary protein known for its colossal size and multifaceted roles, is a cornerstone in the structural and functional dynamics of striated muscle tissues, including the heart and skeletal muscles. Its sheer enormity, with a molecular weight exceeding 3000 kDa, is paralleled only by the immense influence it exerts on muscle physiology. This review will delve into the remarkable structural organization of Titin and the genetics of this molecule, including the common mutations resulting in various cardiomyopathies. We will delve deeper into its role in dilated cardiomyopathy, familial restrictive cardiomyopathy, hypertrophic cardiomyopathy, and left ventricular noncompaction cardiomyopathy. This review culminates by discussing the prospects of therapeutic strategies targeting Titin. While these interventions remain primarily theoretical, the possibilities are intriguing. Patients with Titin truncation mutations present unique challenges, but innovative approaches like gene therapy or preemptive treatments with drugs such as angiotensin-converting enzyme inhibitors or beta-blockers offer hope. This multi-pronged approach highlights the significance of understanding Titin's multifaceted role and its potential as a target for future therapeutic interventions.
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Affiliation(s)
- Jude ElSaygh
- From the Department of Medicine, New York Presbyterian Brooklyn Methodist Hospital, Brooklyn, NY
| | - Anas Zaher
- From the Department of Medicine, New York Presbyterian Brooklyn Methodist Hospital, Brooklyn, NY
| | - Stephen J Peterson
- From the Department of Medicine, New York Presbyterian Brooklyn Methodist Hospital, Brooklyn, NY
- Weill Department of Medicine, Weill Cornell Medicine, NY
| | - Manish A Parikh
- From the Department of Medicine, New York Presbyterian Brooklyn Methodist Hospital, Brooklyn, NY
- Weill Department of Medicine, Weill Cornell Medicine, NY
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10
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Kellermayer D, Tordai H, Kiss B, Török G, Péter DM, Sayour AA, Pólos M, Hartyánszky I, Szilveszter B, Labeit S, Gángó A, Bedics G, Bödör C, Radovits T, Merkely B, Kellermayer MS. Truncated titin is structurally integrated into the human dilated cardiomyopathic sarcomere. J Clin Invest 2024; 134:e169753. [PMID: 37962957 PMCID: PMC10763722 DOI: 10.1172/jci169753] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 11/08/2023] [Indexed: 11/16/2023] Open
Abstract
Heterozygous (HET) truncating variant mutations in the TTN gene (TTNtvs), encoding the giant titin protein, are the most common genetic cause of dilated cardiomyopathy (DCM). However, the molecular mechanisms by which TTNtv mutations induce DCM are controversial. Here, we studied 127 clinically identified DCM human cardiac samples with next-generation sequencing (NGS), high-resolution gel electrophoresis, Western blot analysis, and super-resolution microscopy in order to dissect the structural and functional consequences of TTNtv mutations. The occurrence of TTNtv was found to be 15% in the DCM cohort. Truncated titin proteins matching, by molecular weight, the gene sequence predictions were detected in the majority of the TTNtv+ samples. Full-length titin was reduced in TTNtv+ compared with TTNtv- samples. Proteomics analysis of washed myofibrils and stimulated emission depletion (STED) super-resolution microscopy of myocardial sarcomeres labeled with sequence-specific anti-titin antibodies revealed that truncated titin was structurally integrated into the sarcomere. Sarcomere length-dependent anti-titin epitope position, shape, and intensity analyses pointed at possible structural defects in the I/A junction and the M-band of TTNtv+ sarcomeres, which probably contribute, possibly via faulty mechanosensor function, to the development of manifest DCM.
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Affiliation(s)
- Dalma Kellermayer
- Heart and Vascular Center
- Department of Biophysics and Radiation Biology, and
- 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary
| | | | - Balázs Kiss
- Department of Biophysics and Radiation Biology, and
| | - György Török
- Department of Biophysics and Radiation Biology, and
| | | | | | | | | | | | - Siegfried Labeit
- DZHK Partnersite Mannheim-Heidelberg, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Ambrus Gángó
- 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary
| | - Gábor Bedics
- 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary
| | - Csaba Bödör
- 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary
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11
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Dassanayake Mudiyanselage SP, Gage MJ. Regulation of Poly-E Motif Flexibility by pH, Ca 2+ and the PPAK Motif. Int J Mol Sci 2022; 23:ijms23094779. [PMID: 35563177 PMCID: PMC9100103 DOI: 10.3390/ijms23094779] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 04/18/2022] [Accepted: 04/22/2022] [Indexed: 12/04/2022] Open
Abstract
The disordered PEVK region of titin contains two main structural motifs: PPAK and poly-E. The distribution of these motifs in the PEVK region contributes to the elastic properties of this region, but the specific mechanism of how these motifs work together remains unclear. Previous work from our lab has demonstrated that 28-amino acid peptides of the poly-E motif are sensitive to shifts in pH, becoming more flexible as the pH decreases. We extend this work to longer poly-E constructs, including constructs containing PPAK motifs. Our results demonstrate that longer poly-E motifs have a much larger range of pH sensitivity and that the inclusion of the PPAK motif reduces this sensitivity. We also demonstrate that binding calcium can increase the conformational flexibility of the poly-E motif, though the PPAK motif can block this calcium-dependent change. The data presented here suggest a model where PPAK and calcium can alter the stiffness of the poly-E motif by modulating the degree of charge repulsion in the glutamate clusters.
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Affiliation(s)
| | - Matthew J. Gage
- Department of Chemistry, University of Massachusetts Lowell, Lowell, MA 01854, USA;
- UMass Movement Center (UMOVE), University of Massachusetts Lowell, Lowell, MA 01854, USA
- Correspondence:
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12
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Comparative Transcriptome Profiling of Young and Old Brown Adipose Tissue Thermogenesis. Int J Mol Sci 2021; 22:ijms222313143. [PMID: 34884947 PMCID: PMC8658479 DOI: 10.3390/ijms222313143] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 12/02/2021] [Accepted: 12/03/2021] [Indexed: 12/13/2022] Open
Abstract
Brown adipose tissue (BAT) is a major site for uncoupling protein 1 (UCP1)-mediated non-shivering thermogenesis. BAT dissipates energy via heat generation to maintain the optimal body temperature and increases energy expenditure. These energetic processes in BAT use large amounts of glucose and fatty acid. Therefore, the thermogenesis of BAT may be harnessed to treat obesity and related diseases. In mice and humans, BAT levels decrease with aging, and the underlying mechanism is elusive. Here, we compared the transcriptomic profiles of both young and aged BAT in response to thermogenic stimuli. The profiles were extracted from the GEO database. Intriguingly, aging does not cause transcriptional changes in thermogenic genes but upregulates several pathways related to the immune response and downregulates metabolic pathways. Acute severe CE upregulates several pathways related to protein folding. Chronic mild CE upregulates metabolic pathways, especially related to carbohydrate metabolism. Our findings provide a better understanding of the effects of aging and metabolic responses to thermogenic stimuli in BAT at the transcriptome level.
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13
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Kelly C, Gage MJ. Protein Unfolding: Denaturant vs. Force. Biomedicines 2021; 9:biomedicines9101395. [PMID: 34680512 PMCID: PMC8533514 DOI: 10.3390/biomedicines9101395] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 09/20/2021] [Accepted: 09/28/2021] [Indexed: 11/16/2022] Open
Abstract
While protein refolding has been studied for over 50 years since the pioneering work of Christian Anfinsen, there have been a limited number of studies correlating results between chemical, thermal, and mechanical unfolding. The limited knowledge of the relationship between these processes makes it challenging to compare results between studies if different refolding methods were applied. Our current work compares the energetic barriers and folding rates derived from chemical, thermal, and mechanical experiments using an immunoglobulin-like domain from the muscle protein titin as a model system. This domain, I83, has high solubility and low stability relative to other Ig domains in titin, though its stability can be modulated by calcium. Our experiments demonstrated that the free energy of refolding was equivalent with all three techniques, but the refolding rates exhibited differences, with mechanical refolding having slightly faster rates. This suggests that results from equilibrium-based measurements can be compared directly but care should be given comparing refolding kinetics derived from refolding experiments that used different unfolding methods.
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Affiliation(s)
- Colleen Kelly
- Department of Chemistry, University of Massachusetts Lowell, Lowell, MA 01854, USA;
| | - Matthew J. Gage
- Department of Chemistry, University of Massachusetts Lowell, Lowell, MA 01854, USA;
- UMass Movement Center (UMOVE), University of Massachusetts Lowell, Lowell, MA 01854, USA
- Correspondence:
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14
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Ng YH, Okolo CA, Erickson JR, Baldi JC, Jones PP. Protein O-GlcNAcylation in the heart. Acta Physiol (Oxf) 2021; 233:e13696. [PMID: 34057811 DOI: 10.1111/apha.13696] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 05/25/2021] [Accepted: 05/27/2021] [Indexed: 12/30/2022]
Abstract
O-GlcNAcylation is a ubiquitous post-translational modification that is extremely labile and plays a significant role in physiology, including the heart. Sustained activation of cardiac O-GlcNAcylation is frequently associated with alterations in cellular metabolism, leading to detrimental effects on cardiovascular function. This is particularly true during conditions such as diabetes, hypertension, cardiac remodelling, heart failure and arrhythmogenesis. Paradoxically, transient elevation of cardiac protein O-GlcNAcylation can also exert beneficial effects in the heart. There is compelling evidence to suggest that a complex interaction between O-GlcNAcylation and phosphorylation also exists in the heart. Beyond direct functional consequences on cardiomyocytes, O-GlcNAcylation also acts indirectly by altering the function of transcription factors that affect downstream signalling. This review focuses on the potential cardioprotective role of protein O-GlcNAcylation during ischaemia-reperfusion injury, the deleterious consequences of chronically elevated O-GlcNAc levels, the interplay between O-GlcNAcylation and phosphorylation in the cardiomyocytes and the effects of O-GlcNAcylation on other major non-myocyte cell types in the heart.
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Affiliation(s)
- Yann Huey Ng
- Department of Medicine and HeartOtago University of Otago Dunedin New Zealand
| | - Chidinma A. Okolo
- Department of Physiology and HeartOtago University of Otago Dunedin New Zealand
- Life Sciences Division Diamond Light Source LtdHarwell Science and Innovation Campus Didcot UK
| | - Jeffrey R. Erickson
- Department of Physiology and HeartOtago University of Otago Dunedin New Zealand
| | - James C. Baldi
- Department of Medicine and HeartOtago University of Otago Dunedin New Zealand
| | - Peter P. Jones
- Department of Physiology and HeartOtago University of Otago Dunedin New Zealand
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15
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Yu M, Lu JH, Le S, Yan J. Unexpected Low Mechanical Stability of Titin I27 Domain at Physiologically Relevant Temperature. J Phys Chem Lett 2021; 12:7914-7920. [PMID: 34384021 DOI: 10.1021/acs.jpclett.1c01309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The extensively studied immunoglobulin (Ig) domain I27 of the giant force-bearing protein titin has provided a basis for our current understanding of the structural stability, dynamics, and function of the numerous mechanically stretched Ig domains in the force-bearing I-band of titin. The current consensus is that titin I27 has a high mechanical stability characterized by very low unfolding rate (<10-3 s-1) in physiological force range and high unfolding forces (>100 pN) at typical physiological force loading rates from experiments at typical laboratory temperatures. Here, we report that when the temperature is increased from 23 to 37 °C, the unfolding rate of I27 drastically increases by ∼100-fold at the physiological level of forces, indicating a low mechanical stability of I27 at physiological conditions. The result provides new insights into the structural states and the associated functions of I27 and other similar titin I-band Ig domains.
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Affiliation(s)
- Miao Yu
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore
| | - Jung-Hsuan Lu
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Shimin Le
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Jie Yan
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
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16
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Lieber RL, Binder-Markey B. Biochemical and structural basis of the passive mechanical properties of whole skeletal muscle. J Physiol 2021; 599:3809-3823. [PMID: 34101193 PMCID: PMC8364503 DOI: 10.1113/jp280867] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 05/06/2021] [Indexed: 01/18/2023] Open
Abstract
Passive mechanical properties of whole skeletal muscle are not as well understood as active mechanical properties. Both the structural basis for passive mechanical properties and the properties themselves are challenging to determine because it is not clear which structures within skeletal muscle actually bear passive loads and there are not established standards by which to make mechanical measurements. Evidence suggests that titin bears the majority of the passive load within the single muscle cell. However, at larger scales, such as fascicles and muscles, there is emerging evidence that the extracellular matrix bears the major part of the load. Complicating the ability to quantify and compare across size scales, muscles and species, definitions of muscle passive properties such as stress, strain, modulus and stiffness can be made relative to many reference parameters. These uncertainties make a full understanding of whole muscle passive mechanical properties and modelling these properties very difficult. Future studies defining the specific load bearing structures and their composition and organization are required to fully understand passive mechanics of the whole muscle and develop therapies to treat disorders in which passive muscle properties are altered such as muscular dystrophy, traumatic laceration, and contracture due to upper motor neuron lesion as seen in spinal cord injury, stroke and cerebral palsy.
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Affiliation(s)
- Richard L. Lieber
- Shirley Ryan AbilityLab
- Departments of Physical Medicine and Rehabilitation and
Biomedical Engineering, Northwestern University, Chicago, IL, USA
- Edward Hines V.A. Medical Center, Hines, IL USA
| | - Ben Binder-Markey
- Department of Physical Therapy and Rehabilitation Sciences
and School of Biomedical Engineering, Sciences and Health Systems, Drexel
University, Philadelphia, PA USA
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17
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The Sarcomeric Spring Protein Titin: Biophysical Properties, Molecular Mechanisms, and Genetic Mutations Associated with Heart Failure and Cardiomyopathy. Curr Cardiol Rep 2021; 23:121. [PMID: 34269900 DOI: 10.1007/s11886-021-01550-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/07/2021] [Indexed: 01/06/2023]
Abstract
PURPOSE OF REVIEW The giant protein titin forms the "elastic" filament of the sarcomere, essential for the mechanical compliance of the heart muscle. Titin serves a biological spring, and therefore structural modifications of titin affect function of the myocardium and are associated with heart failure and cardiomyopathy. RECENT FINDINGS In this review, we discuss the current understanding of titin's biophysical properties and how modifications contribute to cardiac function and heart failure. In addition, we review the most recent data on the clinical impact and phenotype heterogeneity of TTN truncating variants, including diseases involving striated muscles, and prospects for future therapies. Because of the giant structure of the titin protein and the complexity of its function, titin's role in health and disease is not yet completely understood. Future research efforts need to focus on novel therapeutic approaches able to modulate titin transcriptional and post-translational modification.
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18
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The Metabolic Relevance of Type of Locomotion in Anaerobic Testing: Bosco Continuous Jumping Test Versus Wingate Anaerobic Test of the Same Duration. Int J Sports Physiol Perform 2021; 16:1663-1669. [PMID: 33887701 DOI: 10.1123/ijspp.2020-0669] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 01/08/2021] [Accepted: 01/15/2021] [Indexed: 11/18/2022]
Abstract
PURPOSE To evaluate the metabolic relevance of type of locomotion in anaerobic testing by analyzing and comparing the metabolic profile of the Bosco Continuous Jumping Test (CJ30) with the corresponding profile of the Wingate Anaerobic Test (WAnT). METHODS A total of 11 well-trained, male team-sport athletes (age = 23.7 [2.2] y, height = 184.1 [2.8] cm, weight = 82.4 [6.4] kg) completed a CJ30 and WAnT each. During the WAnT, power data and revolutions per minute were recorded, and during the CJ30, jump height and jumping frequency were recorded. In addition, oxygen uptake and blood lactate concentration were assessed, and metabolic profiles were determined via the PCr-LA-O2 method. RESULTS In the CJ30, metabolic energy was lower (109.3 [18.0] vs 143.0 [13.1] kJ, P < .001, d = -2.302), while peak power (24.8 [4.4] vs 11.8 [0.5] W·kg-1, P < .001, d = 3.59) and mean power (20.8 [3.6] vs 9.1 [0.5] W·kg-1, P < .001, d = 4.14) were higher than in the WAnT. The metabolic profiles of the CJ30 (aerobic energy = 20.00% [4.7%], anaerobic alactic energy [WPCr] = 45.6% [4.5%], anaerobic lactic energy = 34.4% [5.2%]) and the WAnT (aerobic energy = 16.0% [3.0%], anaerobic alactic WPCr = 34.5% [5.0%], anaerobic lactic energy = 49.5% [3.3%]) are highly anaerobic. Absolute energy contribution for the CJ30 and WAnT was equal in WPCr (49.9 [11.1] vs 50.2 [11.2] kJ), but anaerobic lactic energy (37.7 [7.7] vs 69.9 [5.3] kJ) and aerobic energy (20.6 [5.7] vs 23.0 [4.0] kJ) were higher in the WAnT. Mechanical efficiency was substantially higher in the CJ30 (37.9% [4.5%] vs 15.6% [1.0%], P < .001, d = 6.86), while the fatigue index was lower (18.5% [3.8%] vs 23.2% [3.1%], P < .001, d = -1.38) than in the WAnT. CONCLUSIONS Although the anaerobic share in both tests is similar and predominant, the CJ30 primarily taxes the WPCr system, while the WAnT more strongly relies on the glycolytic pathway. Thus, the 2 tests should not be used interchangeably, and the type of locomotion seems crucial when choosing an anaerobic test for a specific sport.
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19
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Maimaiti R, Zhu C, Zhang Y, Ding Q, Guo W. RBM20-Mediated Pre-mRNA Splicing Has Muscle-Specificity and Differential Hormonal Responses between Muscles and in Muscle Cell Cultures. Int J Mol Sci 2021; 22:2928. [PMID: 33805770 PMCID: PMC7999644 DOI: 10.3390/ijms22062928] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 03/10/2021] [Accepted: 03/11/2021] [Indexed: 11/16/2022] Open
Abstract
Pre-mRNA splicing plays an important role in muscle function and diseases. The RNA binding motif 20 (RBM20) is a splicing factor that is predominantly expressed in muscle tissues and primarily regulates pre-mRNA splicing of Ttn, encoding a giant muscle protein titin that is responsible for muscle function and diseases. RBM20-mediated Ttn splicing has been mostly studied in heart muscle, but not in skeletal muscle. In this study, we investigated splicing specificity in different muscle types in Rbm20 knockout rats and hormonal effects on RBM20-mediated splicing both in cellulo and in vivo studies. The results revealed that RBM20 is differentially expressed across muscles and RBM20-mediated splicing is muscle-type specific. In the presence of RBM20, Ttn splicing responds to hormones in a muscle-type dependent manner, while in the absence of RBM20, Ttn splicing is not affected by hormones. In differentiated and undifferentiated C2C12 cells, RBM20-mediated splicing in response to hormonal effects is mainly through genomic signaling pathway. The knowledge gained from this study may help further understand muscle-specific gene splicing in response to hormone stimuli in different muscle types.
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Affiliation(s)
- Rexiati Maimaiti
- Animal Science Department, University of Wyoming, Laramie, WY 82071, USA; (R.M.); (C.Z.)
| | - Chaoqun Zhu
- Animal Science Department, University of Wyoming, Laramie, WY 82071, USA; (R.M.); (C.Z.)
| | - Yanghai Zhang
- Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA; (Y.Z.); (Q.D.)
| | - Qiyue Ding
- Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA; (Y.Z.); (Q.D.)
| | - Wei Guo
- Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA; (Y.Z.); (Q.D.)
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20
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Dysregulated ribonucleoprotein granules promote cardiomyopathy in RBM20 gene-edited pigs. Nat Med 2020; 26:1788-1800. [PMID: 33188278 PMCID: PMC9270981 DOI: 10.1038/s41591-020-1087-x] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 08/21/2020] [Indexed: 12/12/2022]
Abstract
Ribonucleoprotein (RNP) granules are biomolecular condensates-liquid-liquid phase-separated droplets that organize and manage messenger RNA metabolism, cell signaling, biopolymer assembly, biochemical reactions and stress granule responses to cellular adversity. Dysregulated RNP granules drive neuromuscular degenerative disease but have not previously been linked to heart failure. By exploring the molecular basis of congenital dilated cardiomyopathy (DCM) in genome-edited pigs homozygous for an RBM20 allele encoding the pathogenic R636S variant of human RNA-binding motif protein-20 (RBM20), we discovered that RNP granules accumulated abnormally in the sarcoplasm, and we confirmed this finding in myocardium and reprogrammed cardiomyocytes from patients with DCM carrying the R636S allele. Dysregulated sarcoplasmic RBM20 RNP granules displayed liquid-like material properties, docked at precisely spaced intervals along cytoskeletal elements, promoted phase partitioning of cardiac biomolecules and fused with stress granules. Our results link dysregulated RNP granules to myocardial cellular pathobiology and heart failure in gene-edited pigs and patients with DCM caused by RBM20 mutation.
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21
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Honar H, Liu H, Zhang ML, Glenn TK, Ter Keurs HEDJ, Lee SS. Impaired myosin isoform shift and calcium transients contribute to cellular pathogenesis of rat cirrhotic cardiomyopathy. Liver Int 2020; 40:2808-2819. [PMID: 32654385 DOI: 10.1111/liv.14599] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 06/28/2020] [Accepted: 07/04/2020] [Indexed: 02/13/2023]
Abstract
BACKGROUND & AIMS Cirrhotic cardiomyopathy is a recently recognized entity, but detailed cellular and molecular mechanisms remain unclarified. We aimed to elucidate the role of myosin heavy chain isoform shifts and their relation to calcium transients in the contractile kinetics of cirrhotic rats. METHODS Cirrhosis was induced in male Lewis Brown-Norway rats by bile duct ligation (BDL). Myosin heavy chain (MHC) isoform distribution was evaluated by gel electrophoresis. Contractile force, Ca2+ transients and cell shortening were studied at varied frequency and extracellular [Ca2+ ]. T-tubular integrity was analysed by power spectrum analysis of images of myocytes stained with di-8-ANEPPS. RESULTS Compared with sham controls, the phenotypes of cirrhotic rats were as follows: (a) alpha-myosin heavy chain shifted to beta-MHC isoform; (b) mild loss of T-tubular integrity in myocytes; (c) a reduced maximum and rate of rise of the Ca2+ transient (max F/Fo ); (d) a reduction in both the rate of rise and fall of contraction; (e) decreased maximal force-generating capacity; (f) loss of the inotropic effect of increased stimulus frequency; (g) unchanged sensitivity of force development to varied extracellular [Ca2+ ] and (h) increased spontaneous diastolic sarcomere length fluctuations. CONCLUSION Cardiomyocytes and ventricular trabeculae in a cirrhotic rat model showed features of typical heart failure including systolic and diastolic prolongation, impaired force-frequency relation and decreased force-generating capacity. Impaired myosin isoform shift and calcium transients are important contributory mechanisms underlying the pathogenesis of the heart failure phenotype seen in cirrhosis.
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Affiliation(s)
- Hooman Honar
- Liver Unit, University of Calgary Cumming School of Medicine, Calgary, AB, Canada
| | - Hongqun Liu
- Liver Unit, University of Calgary Cumming School of Medicine, Calgary, AB, Canada
| | - Mei L Zhang
- Department of Cardiac Sciences of the Libin Institute, University of Calgary Cumming School of Medicine, Calgary, AB, Canada
| | - Tamara K Glenn
- Liver Unit, University of Calgary Cumming School of Medicine, Calgary, AB, Canada
| | - Henk E D J Ter Keurs
- Department of Cardiac Sciences of the Libin Institute, University of Calgary Cumming School of Medicine, Calgary, AB, Canada
| | - Samuel S Lee
- Liver Unit, University of Calgary Cumming School of Medicine, Calgary, AB, Canada
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22
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Fan Y, Yu Z, Zhao W, Ding L, Zheng F, Li J, Liu J. Identification and molecular mechanism of angiotensin-converting enzyme inhibitory peptides from Larimichthys crocea titin. FOOD SCIENCE AND HUMAN WELLNESS 2020. [DOI: 10.1016/j.fshw.2020.04.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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23
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Abstract
Muscle stiffness, muscle elasticity and explosive strength are the main components of athletes' performance and they show a sex-based as well as ethnicity variation. Muscle stiffness is thought to be one of the risk factors associated with sports injuries and is less common in females than in males. These observations may be explained by circulating levels of sex hormones and their specific receptors. It has been shown that higher levels of estrogen are associated with lower muscle stiffness responsible for suppression of collagen synthesis. It is thought that these properties, at least in part, depend on genetic factors. Particularly, the gene encoding estrogen receptor 1 (ESR1) is one of the candidates that may be associated with muscle stiffness. Muscle elasticity increases with aging and there is evidence suggesting that titin (encoded by the TTN gene), a protein that is expressed in cardiac and skeletal muscles, is one of the factors responsible for elastic properties of the muscles. Mutations in the TTN gene result in some types of muscular dystrophy or cardiomyopathy. In this context, TTN may be regarded as a promising candidate for studying the elastic properties of muscles in athletes. The physiological background of explosive strength depends not only on the muscle architecture and muscle fiber composition, but also on the central nervous system and functionality of neuromuscular units. These properties are, at least partly, genetically determined. In this context, the ACTN3 gene code for α-actinin 3 has been widely researched.
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24
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Chatziefthimiou SD, Hornburg P, Sauer F, Mueller S, Ugurlar D, Xu ER, Wilmanns M. Structural diversity in the atomic resolution 3D fingerprint of the titin M-band segment. PLoS One 2019; 14:e0226693. [PMID: 31856237 PMCID: PMC6922384 DOI: 10.1371/journal.pone.0226693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 12/02/2019] [Indexed: 11/18/2022] Open
Abstract
In striated muscles, molecular filaments are largely composed of long protein chains with extensive arrays of identically folded domains, referred to as “beads-on-a-string”. It remains a largely unresolved question how these domains have developed a unique molecular profile such that each carries out a distinct function without false-positive readout. This study focuses on the M-band segment of the sarcomeric protein titin, which comprises ten identically folded immunoglobulin domains. Comparative analysis of high-resolution structures of six of these domains ‒ M1, M3, M4, M5, M7, and M10 ‒ reveals considerable structural diversity within three distinct loops and a non-conserved pattern of exposed cysteines. Our data allow to structurally interpreting distinct pathological readouts that result from titinopathy-associated variants. Our findings support general principles that could be used to identify individual structural/functional profiles of hundreds of identically folded protein domains within the sarcomere and other densely crowded cellular environments.
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Affiliation(s)
| | - Philipp Hornburg
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Florian Sauer
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Simone Mueller
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Deniz Ugurlar
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Emma-Ruoqi Xu
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Matthias Wilmanns
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
- University Hamburg Medical Centre Hamburg-Eppendorf, Hamburg, Germany
- * E-mail:
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25
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Arrhythmogenic Ventricular Cardiomyopathy Associated With Fibromuscular Dysplasia of Ostial Right Main Coronary Artery. Am J Forensic Med Pathol 2019; 40:183-187. [PMID: 30844837 DOI: 10.1097/paf.0000000000000469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In this article, we report the autopsy findings of a 23-year-old woman, who was found unconscious at home by her relatives. During the transportation to the hospital, the woman was handed over to the ambulance personnel, who were the first to provide cardiopulmonary resuscitation. In the hospital, after an hour-lasting asystole, the heart activity was restored. Prolonged cardiac arrest led to hypoxic brain injury, which resulted in a persistent coma. Examinations carried out during hospitalization detected hypokinetic interventricular septum, frequent ventricular extrasystoles and ventricular fibrillation. The patient died within 35 hours of admission to the hospital. Gross findings of the heart included a noticeable increase of the adipose tissue in the right ventricular wall, where histologically focal myocardial atrophy with focal transmural lipomatosis reaching endocardium were detected. Death was attributed to arrhythmogenic ventricular cardiomyopathy. Pathogenic variants in JUP gene and KCNH2 gene confirmed the diagnosis. Other finding of note was fibromuscular dysplasia of ostial right main coronary artery causing a significant luminal narrowing.
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26
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Pastore A, Martin SR, Temussi PA. Generalized View of Protein Folding: In Medio Stat Virtus. J Am Chem Soc 2019; 141:2194-2200. [PMID: 30566837 DOI: 10.1021/jacs.8b10779] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Proteins are often described in textbooks as being only "marginally stable" but many proteins, specifically those with a high free energy of unfolding are, in fact, so stable that they exist only in the fully folded state except under harsh denaturing conditions. Proteins that are truly only marginally stable, those with a low free energy of unfolding, exist as an equilibrium mixture of folded and unfolded forms under "normal" conditions. To some extent such proteins have some features in common with "intrinsically disordered" proteins. We analyzed the relationship between these marginally stable proteins and intrinsically disordered proteins in order to fully understand the twilight zone that distinguishes the two ensembles in the hope of clarifying the fuzzy borders of the current classification that divides the protein world into folded and intrinsically disordered ones. Our analysis suggests that the division may be too drastic and misleading, because it puts within the same category proteins with very different behaviors. We propose a restricted, albeit operational, definition of "marginally stable proteins", referring by this term only to proteins whose free energy difference between the folded and unfolded states falls in the interval 0-3 kcal/mol. These proteins have special features because they normally exist as equilibrium mixtures of folded and unfolded species or as molten globule states. This coexistence makes marginally stable proteins ideal tools to study even small environmental changes to which they may behave as natural sensors.
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Affiliation(s)
- Annalisa Pastore
- The Wohl Institute, King's College London , 5 Cutcombe Road , London SE59RT , United Kingdom.,Department of Molecular Medicine , University of Pavia , Pavia 27100 , Italy
| | - Stephen R Martin
- Structural Biology Science Technology Platform, The Francis Crick Institute , 1 Midland Road , London NW1 1AT , United Kingdom
| | - Piero Andrea Temussi
- The Wohl Institute, King's College London , 5 Cutcombe Road , London SE59RT , United Kingdom.,Dipartimento di Scienze Chimiche , Universita' di Napoli Federico II , Napoli 80126 , Italy
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27
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Chen Z, Maimaiti R, Zhu C, Cai H, Stern A, Mozdziak P, Ge Y, Ford SP, Nathanielsz PW, Guo W. Z-band and M-band titin splicing and regulation by RNA binding motif 20 in striated muscles. J Cell Biochem 2018; 119:9986-9996. [PMID: 30133019 PMCID: PMC6218289 DOI: 10.1002/jcb.27328] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 06/28/2018] [Indexed: 12/12/2022]
Abstract
Titin (TTN) has multifunctional roles in sarcomere assembly, mechanosignaling transduction, and muscle stiffness. TTN splicing generates variable protein sizes with different functions. Therefore, understanding TTN splicing is important to develop a novel treatment for TTN-based diseases. The I-band TTN splicing regulated by RNA binding motif 20 (RBM20) has been extensively studied. However, the Z- and M-band splicing and regulation remain poorly understood. Herein, we aimed to define the Z- and M-band splicing in striated muscles and determined whether RBM20 regulates the Z- and M-band splicing. We discovered four new Z-band TTN splicing variants, and one of them dominates in mouse, rat, sheep, and human hearts. But only one form can be detected in frog and chicken hearts. In skeletal muscles, three new Z repeats (Zr) were detected, and Zr4 to 6 exclusion dominates in the fast muscles, whereas Zr4 skipping dominates in the slow muscle. No developmental changes were detected in the Z-band. In the M-band, two new variants were discovered with alternative 3' splice site in exon363 (Mex5) and alternative 5' splice site in intron 362. However, only the sheep heart expresses two new variants rather than other species. Skeletal muscles express three M-band variants with altered ratios of Mex5 inclusion to Mex5 exclusion. Finally, we revealed that RBM20 does not regulate the Z- and M-band splicing in the heart, but does in skeletal muscles. Taken together, we characterized the Z- and M-band splicing and provided the first evidence of the role of RBM20 in the Z- and M-band TTN splicing.
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Affiliation(s)
- Zhilong Chen
- Department of Animal Science, College of Animal Science and Technology, Northwest A&F University, Yangling, Shanxi, China
- Department of Animal Science, University of Wyoming, Laramie, Wyoming
| | - Rexiati Maimaiti
- Department of Animal Science, University of Wyoming, Laramie, Wyoming
| | - Chaoqun Zhu
- Department of Animal Science, University of Wyoming, Laramie, Wyoming
| | - Hanfang Cai
- Department of Animal Science, College of Animal Science and Technology, Northwest A&F University, Yangling, Shanxi, China
- Department of Animal Science, University of Wyoming, Laramie, Wyoming
| | - Allysa Stern
- Prestage Department of Poultry Science, North Carolina State University, Raleigh, North Carolina
| | - Paul Mozdziak
- Prestage Department of Poultry Science, North Carolina State University, Raleigh, North Carolina
| | - Ying Ge
- Department of Cell and Regenerative Biology, Human Proteomics Program, University of Wisconsin, Madison, Wisconsin
- Department of Chemistry, Human Proteomics Program, University of Wisconsin, Madison, Wisconsin
| | - Stephen P Ford
- Department of Animal Science, University of Wyoming, Laramie, Wyoming
| | | | - Wei Guo
- Department of Animal Science, University of Wyoming, Laramie, Wyoming
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28
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Abstract
The concept of cell signaling in the context of nonenzyme-assisted protein modifications by reactive electrophilic and oxidative species, broadly known as redox signaling, is a uniquely complex topic that has been approached from numerous different and multidisciplinary angles. Our Review reflects on five aspects critical for understanding how nature harnesses these noncanonical post-translational modifications to coordinate distinct cellular activities: (1) specific players and their generation, (2) physicochemical properties, (3) mechanisms of action, (4) methods of interrogation, and (5) functional roles in health and disease. Emphasis is primarily placed on the latest progress in the field, but several aspects of classical work likely forgotten/lost are also recollected. For researchers with interests in getting into the field, our Review is anticipated to function as a primer. For the expert, we aim to stimulate thought and discussion about fundamentals of redox signaling mechanisms and nuances of specificity/selectivity and timing in this sophisticated yet fascinating arena at the crossroads of chemistry and biology.
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Affiliation(s)
- Saba Parvez
- Department of Pharmacology and Toxicology, College of
Pharmacy, University of Utah, Salt Lake City, Utah, 84112, USA
- Department of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York, 14853, USA
| | - Marcus J. C. Long
- Department of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York, 14853, USA
| | - Jesse R. Poganik
- Ecole Polytechnique Fédérale de Lausanne,
Institute of Chemical Sciences and Engineering, 1015, Lausanne, Switzerland
- Department of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York, 14853, USA
| | - Yimon Aye
- Ecole Polytechnique Fédérale de Lausanne,
Institute of Chemical Sciences and Engineering, 1015, Lausanne, Switzerland
- Department of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York, 14853, USA
- Department of Biochemistry, Weill Cornell Medicine, New
York, New York, 10065, USA
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29
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McCartney CSE, Ye Q, Campbell RL, Davies PL. Insertion sequence 1 from calpain-3 is functional in calpain-2 as an internal propeptide. J Biol Chem 2018; 293:17716-17730. [PMID: 30254072 DOI: 10.1074/jbc.ra118.004803] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 09/18/2018] [Indexed: 11/06/2022] Open
Abstract
Calpains are intracellular, calcium-activated cysteine proteases. Calpain-3 is abundant in skeletal muscle, where its mutation-induced loss of function causes limb-girdle muscular dystrophy type 2A. Unlike the small subunit-containing calpain-1 and -2, the calpain-3 isoform homodimerizes through pairing of its C-terminal penta-EF-hand domain. It also has two unique insertion sequences (ISs) not found in the other calpains: IS1 within calpain-3's protease core and IS2 just prior to the penta-EF-hand domain. Production of either native or recombinant full-length calpain-3 to characterize the function of these ISs is challenging. Therefore, here we used recombinant rat calpain-2 as a stable surrogate and inserted IS1 into its equivalent position in the protease core. As it does in calpain-3, IS1 occupied the catalytic cleft and restricted the enzyme's access to substrate and inhibitors. Following activation by Ca2+, IS1 was rapidly cleaved by intramolecular autolysis, permitting the enzyme to freely accept substrate and inhibitors. The surrogate remained functional until extensive intermolecular autoproteolysis inactivated the enzyme, as is typical of calpain-2. Although the small-molecule inhibitors E-64 and leupeptin limited intermolecular autolysis of the surrogate, they did not block the initial intramolecular cleavage of IS1, establishing its role as a propeptide. Surprisingly, the large-molecule calpain inhibitor, calpastatin, completely blocked enzyme activity, even with IS1 intact. We suggest that calpastatin is large enough to oust IS1 from the catalytic cleft and take its place. We propose an explanation for why calpastatin can inhibit calpain-2 bearing the IS1 insertion but cannot inhibit WT calpain-3.
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Affiliation(s)
- Christian-Scott E McCartney
- From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Qilu Ye
- From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Robert L Campbell
- From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Peter L Davies
- From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada.
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30
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Galior K, Ma VPY, Liu Y, Su H, Baker N, Panettieri RA, Wongtrakool C, Salaita K. Molecular Tension Probes to Investigate the Mechanopharmacology of Single Cells: A Step toward Personalized Mechanomedicine. Adv Healthc Mater 2018; 7:e1800069. [PMID: 29785773 PMCID: PMC6105437 DOI: 10.1002/adhm.201800069] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 03/15/2018] [Indexed: 01/03/2023]
Abstract
Given that dysregulation of mechanics contributes to diseases ranging from cancer metastasis to lung disease, it is important to develop methods for screening the efficacy of drugs that target cellular forces. Here, nanoparticle-based tension sensors are used to quantify the mechanical response of individual cells upon drug treatment. As a proof-of-concept, the activity of bronchodilators is tested on human airway smooth muscle cells derived from seven donors, four of which are asthmatic. It is revealed that airway smooth muscle cells isolated from asthmatic donors exhibit greater traction forces compared to the control donors. Additionally, the mechanical signal is abolished using myosin inhibitors or further enhanced in the presence of inflammatory inducers, such as nicotine. Using the signal generated by the probes, single-cell dose-response measurements are performed to determine the "mechano" effective concentration (mechano-EC50 ) of albuterol, a bronchodilator, which reduces integrin forces by 50%. Mechano-EC50 values for each donor present discrete readings that are differentially enhanced as a function of nicotine treatment. Importantly, donor mechano-EC50 values varied by orders of magnitude, suggesting significant variability in their sensitivity to nicotine and albuterol treatment. To the best of the authors' knowledge, this is the first study harnessing a piconewton tension sensor platform for mechanopharmacology.
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Affiliation(s)
- Kornelia Galior
- Department of Chemistry, Emory University, Atlanta, GA, 30322, USA
| | | | - Yang Liu
- Department of Chemistry, Emory University, Atlanta, GA, 30322, USA
| | - Hanquan Su
- Department of Chemistry, Emory University, Atlanta, GA, 30322, USA
| | - Nusaiba Baker
- Emory University School of Medicine, Emory University, Atlanta, GA, 30307, USA
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, 30332, USA
| | - Reynold A Panettieri
- Rutgers Institute for Translational Medicine and Science, Rutgers, The State University of New Jersey, New Brunswick, NJ, 08901, USA
| | - Cherry Wongtrakool
- Emory University School of Medicine, Emory University, Atlanta, GA, 30307, USA
- Atlanta Veterans Affairs Medical Center, Decatur, GA, 30033, USA
| | - Khalid Salaita
- Department of Chemistry, Emory University, Atlanta, GA, 30322, USA
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, 30332, USA
- Winship Cancer Institute, Emory University, Atlanta, GA, 30322, USA
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31
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Abstract
The human genome is generally organized into stable chromosomes, and only tumor cells are known to accumulate kilobase (kb)-sized extrachromosomal circular DNA elements (eccDNAs). However, it must be expected that kb eccDNAs exist in normal cells as a result of mutations. Here, we purify and sequence eccDNAs from muscle and blood samples from 16 healthy men, detecting ~100,000 unique eccDNA types from 16 million nuclei. Half of these structures carry genes or gene fragments and the majority are smaller than 25 kb. Transcription from eccDNAs suggests that eccDNAs reside in nuclei and recurrence of certain eccDNAs in several individuals implies DNA circularization hotspots. Gene-rich chromosomes contribute to more eccDNAs per megabase and the most transcribed protein-coding gene in muscle, TTN (titin), provides the most eccDNAs per gene. Thus, somatic genomes are rich in chromosome-derived eccDNAs that may influence phenotypes through altered gene copy numbers and transcription of full-length or truncated genes. Somatic cells can accumulate structural variations such as deletions. Here, Møller et al. show that normal human cells generate large extrachromosomal circular DNAs (eccDNAs), most likely the products of excised DNA, that can be transcriptionally active and, thus, may have phenotypic consequences.
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32
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Yehia L, Ni Y, Eng C. Germline TTN variants are enriched in PTEN-wildtype Bannayan-Riley-Ruvalcaba syndrome. NPJ Genom Med 2017; 2:37. [PMID: 29263846 PMCID: PMC5735137 DOI: 10.1038/s41525-017-0039-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 11/06/2017] [Accepted: 11/27/2017] [Indexed: 12/25/2022] Open
Abstract
Bannayan–Riley–Ruvalcaba syndrome (BRRS) is a rare congenital disorder classically characterized by macrocephaly in combination with intestinal hamartomatous polyposis, vascular malformations, lipomas, and genital lentiginosis. Germline PTEN mutations have been reported in up to 60% of BRRS patients. The remaining cases are of unknown genetic etiology. We exome-sequenced 35 unrelated PTEN-wildtype patients with classic presentation of BRRS and identified TTN germline missense variants in 12/35 (34%) patients. TTN encodes TITIN, a key structural and functional muscle protein. Exome and TTN-targeted sequencing in an additional unrelated series of 231 BRRS-like patients revealed 37 (16%) additional patients with germline TTN variants. All variants were predicted to be deleterious and equally distributed between the A-band and I-band protein domains. Rare TTN variants (MAF ≤ 0.0001) are enriched in classic BRRS patients compared to BRRS-like (OR = 2.7, 95% CI 1.21-5.94, p = 1.6 × 10-2) and multiple population controls (OR = 2.2, 95% CI 1.01-4.20, p = 4.7 × 10-2). Germline TTN mutations of different genotypes, inheritance patterns, and protein domain enrichment have been identified in multiple cardiac and/or skeletal muscular disorders. Functional interrogation of I-band variant p.Cys5096Arg identified in one of our classic BRRS patients, using CRISPR-Cas9 genome-edited cell lines, reveals an increased growth and lack of contact inhibition phenotype associated with increased levels of or phosphorylation of focal adhesion kinase (FAK) in mutant cells. These findings suggest that TITIN could play a role in overgrowth-relevant pathways and phenotypes. In summary, our observations suggest TTN as a candidate predisposing gene in classic PTEN-wildtype BRRS patients, perhaps suggesting this syndrome join the growing list of Titinopathies. TTN variants seem to explain many cases of a rare hereditary condition previously linked only to mutations in the unrelated gene PTEN. Charis Eng and team from the Cleveland Clinic, Ohio, USA, sequenced the protein-coding DNA from 35 patients with Bannayan-Riley-Ruvalcaba syndrome (BRRS), a disease characterized by large head size, tumors and other overgrowth problems. All of these individuals showed no mutations in PTEN, a tumor suppressor that explains 60% of BRRS cases. However, one-third had variants in TTN, which encodes a protein called TITIN that’s involved in muscle elasticity. Additional testing revealed more BRRS-like patients with TTN variants, and lab experiments indicated one possibility of how TTN variants lead to increased cellular growth. The authors suggest BRRS could be considered a “titinopathy” along with other cardiac and skeletal diseases caused by TTN mutations.
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Affiliation(s)
- Lamis Yehia
- Genomic Medicine Institute, Cleveland Clinic, Cleveland, OH 44195 USA.,Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195 USA.,Department of Pathology, Case Western Reserve University, Cleveland, OH 44106 USA
| | - Ying Ni
- Genomic Medicine Institute, Cleveland Clinic, Cleveland, OH 44195 USA.,Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195 USA.,Center for Clinical Genomics, Cleveland Clinic, Cleveland, OH 44106 USA
| | - Charis Eng
- Genomic Medicine Institute, Cleveland Clinic, Cleveland, OH 44195 USA.,Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195 USA.,Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH 44195 USA.,Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106 USA.,Germline High Risk Focus Group, CASE Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH 44106 USA
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33
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Shen Y, Cheng Y, Uyeda TQP, Plaza GR. Cell Mechanosensors and the Possibilities of Using Magnetic Nanoparticles to Study Them and to Modify Cell Fate. Ann Biomed Eng 2017; 45:2475-2486. [PMID: 28744841 DOI: 10.1007/s10439-017-1884-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Accepted: 07/07/2017] [Indexed: 12/13/2022]
Abstract
The use of magnetic nanoparticles (MNPs) is a promising technique for future advances in biomedical applications. This idea is supported by the availability of MNPs that can target specific cell components, the variety of shapes of MNPs and the possibility of finely controlling the applied magnetic forces. To examine this opportunity, here we review the current developments in the use of MNPs to mechanically stimulate cells and, specifically, the cell mechanotransduction systems. We analyze the cell components that may act as mechanosensors and their effect on cell fate and we focus on the promising possibilities of controlling stem-cell differentiation, inducing cancer-cell death and treating nervous-system diseases.
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Affiliation(s)
- Yajing Shen
- The Institute for Translational Nanomedicine, Shanghai East Hospital, The Institute for Biomedical Engineering & Nano Science, Tongji University School of Medicine, Shanghai, 200120, China
| | - Yu Cheng
- The Institute for Translational Nanomedicine, Shanghai East Hospital, The Institute for Biomedical Engineering & Nano Science, Tongji University School of Medicine, Shanghai, 200120, China.
| | - Taro Q P Uyeda
- The Institute for Translational Nanomedicine, Shanghai East Hospital, The Institute for Biomedical Engineering & Nano Science, Tongji University School of Medicine, Shanghai, 200120, China.,Department of Physics, Faculty of Science and Engineering, Waseda University, Tokyo, 169-8555, Japan
| | - Gustavo R Plaza
- The Institute for Translational Nanomedicine, Shanghai East Hospital, The Institute for Biomedical Engineering & Nano Science, Tongji University School of Medicine, Shanghai, 200120, China. .,Center for Biomedical Technology, Universidad Politécnica de Madrid, 28223, Pozuelo de Alarcón, Spain.
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34
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Ait-Mou Y, Zhang M, Martin JL, Greaser ML, de Tombe PP. Impact of titin strain on the cardiac slow force response. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017. [PMID: 28648628 DOI: 10.1016/j.pbiomolbio.2017.06.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Stretch of myocardium, such as occurs upon increased filling of the cardiac chamber, induces two distinct responses: an immediate increase in twitch force followed by a slower increase in twitch force that develops over the course of several minutes. The immediate response is due, in part, to modulation of myofilament Ca2+ sensitivity by sarcomere length (SL). The slowly developing force response, termed the Slow Force Response (SFR), is caused by a slowly developing increase in intracellular Ca2+ upon sustained stretch. A blunted immediate force response was recently reported for myocardium isolated from homozygous giant titin mutant rats (HM) compared to muscle from wild-type littermates (WT). Here, we examined the impact of titin isoform on the SFR. Right ventricular trabeculae were isolated and mounted in an experimental chamber. SL was measured by laser diffraction. The SFR was recorded in response to a 0.2 μm SL stretch in the presence of [Ca2+]o = 0.4 mM, a bathing concentration reflecting ∼50% of maximum twitch force development at 25 °C. Presence of the giant titin isoform (HM) was associated with a significant reduction in diastolic passive force upon stretch, and ∼50% reduction of the magnitude of the SFR; the rate of SFR development was unaffected. The sustained SL stretch was identical in both muscle groups. Therefore, our data suggest that cytoskeletal strain may underlie directly the cellular mechanisms that lead to the increased intracellular [Ca2+]i that causes the SFR, possibly by involving cardiac myocyte integrin signaling pathways.
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Affiliation(s)
- Younss Ait-Mou
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, 2160 South First Ave, Maywood, IL 60153, United States
| | - Mengjie Zhang
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, 2160 South First Ave, Maywood, IL 60153, United States
| | - Jody L Martin
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, 2160 South First Ave, Maywood, IL 60153, United States
| | - Marion L Greaser
- Department of Animal Sciences, Muscle Biology Laboratory, University of Wisconsin - Madison, 1450 Linden Drive, Madison, WI 53706, United States
| | - Pieter P de Tombe
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, 2160 South First Ave, Maywood, IL 60153, United States.
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35
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Abstract
Myotilin is a component of the sarcomere where it plays an important role in organisation and maintenance of Z-disk integrity. This involves direct binding to F-actin and filamin C, a function mediated by its Ig domain pair. While the structures of these two individual domains are known, information about their relative orientation and flexibility remains limited. We set on to characterise the Ig domain pair of myotilin with emphasis on its molecular structure, dynamics and phylogeny. First, sequence conservation analysis of myotilin shed light on the molecular basis of myotilinopathies and revealed several motifs in Ig domains found also in I-band proteins. In particular, a highly conserved Glu344 mapping to Ig domain linker, was identified as a critical component of the inter-domain hinge mechanism. Next, SAXS and molecular dynamics revealed that Ig domain pair exists as a multi-conformation species with dynamic exchange between extended and compact orientations. Mutation of AKE motif to AAA further confirmed its impact on inter-domain flexibility. We hypothesise that the conformational plasticity of the Ig domain pair in its unbound form is part of the binding partner recognition mechanism.
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36
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Zhang N, Xie XJ, Wang JA. Multifunctional protein: cardiac ankyrin repeat protein. J Zhejiang Univ Sci B 2017; 17:333-41. [PMID: 27143260 DOI: 10.1631/jzus.b1500247] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cardiac ankyrin repeat protein (CARP) not only serves as an important component of muscle sarcomere in the cytoplasm, but also acts as a transcription co-factor in the nucleus. Previous studies have demonstrated that CARP is up-regulated in some cardiovascular disorders and muscle diseases; however, its role in these diseases remains controversial now. In this review, we will discuss the continued progress in the research related to CARP, including its discovery, structure, and the role it plays in cardiac development and heart diseases.
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Affiliation(s)
- Na Zhang
- Cardiovascular Key Lab of Zhejiang Province, Department of Cardiology, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China
| | - Xiao-Jie Xie
- Cardiovascular Key Lab of Zhejiang Province, Department of Cardiology, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China
| | - Jian-An Wang
- Cardiovascular Key Lab of Zhejiang Province, Department of Cardiology, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China
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37
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Gu Q, Mendsaikhan U, Khuchua Z, Jones BC, Lu L, Towbin JA, Xu B, Purevjav E. Dissection of Z-disc myopalladin gene network involved in the development of restrictive cardiomyopathy using system genetics approach. World J Cardiol 2017; 9:320-331. [PMID: 28515850 PMCID: PMC5411966 DOI: 10.4330/wjc.v9.i4.320] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 02/09/2017] [Accepted: 02/28/2017] [Indexed: 02/07/2023] Open
Abstract
AIM To investigate the regulation of Myopalladin (Mypn) and identify its gene network involved in restrictive cardiomyopathy (RCM). METHODS Gene expression values were measured in the heart of a large family of BXD recombinant inbred (RI) mice derived from C57BL/6J and DBA/2J. The proteomics data were collected from Mypn knock-in and knock-out mice. Expression quantitative trait locus (eQTL) mapping methods and gene enrichment analysis were used to identify Mypn regulation, gene pathway and co-expression networks. RESULTS A wide range of variation was found in expression of Mypn among BXD strains. We identified upstream genetic loci at chromosome 1 and 5 that modulate the expression of Mypn. Candidate genes within these loci include Ncoa2, Vcpip1, Sgk3, and Lgi2. We also identified 15 sarcomeric genes interacting with Mypn and constructed the gene network. Two novel members of this network (Syne1 and Myom1) have been confirmed at the protein level. Several members in this network are already known to relate to cardiomyopathy with some novel genes candidates that could be involved in RCM. CONCLUSION Using systematic genetics approach, we constructed Mypn co-expression networks that define the biological process categories within which similarly regulated genes function. Through this strategy we have found several novel genes that interact with Mypn that may play an important role in the development of RCM.
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Affiliation(s)
- Qingqing Gu
- Qingqing Gu, Biao Xu, Department of Cardiology, Drum Tower Clinic Hospital, Nanjing Medical University, Nanjing 211166, Jiangsu Province, China
| | - Uzmee Mendsaikhan
- Qingqing Gu, Biao Xu, Department of Cardiology, Drum Tower Clinic Hospital, Nanjing Medical University, Nanjing 211166, Jiangsu Province, China
| | - Zaza Khuchua
- Qingqing Gu, Biao Xu, Department of Cardiology, Drum Tower Clinic Hospital, Nanjing Medical University, Nanjing 211166, Jiangsu Province, China
| | - Byron C Jones
- Qingqing Gu, Biao Xu, Department of Cardiology, Drum Tower Clinic Hospital, Nanjing Medical University, Nanjing 211166, Jiangsu Province, China
| | - Lu Lu
- Qingqing Gu, Biao Xu, Department of Cardiology, Drum Tower Clinic Hospital, Nanjing Medical University, Nanjing 211166, Jiangsu Province, China
| | - Jeffrey A Towbin
- Qingqing Gu, Biao Xu, Department of Cardiology, Drum Tower Clinic Hospital, Nanjing Medical University, Nanjing 211166, Jiangsu Province, China
| | - Biao Xu
- Qingqing Gu, Biao Xu, Department of Cardiology, Drum Tower Clinic Hospital, Nanjing Medical University, Nanjing 211166, Jiangsu Province, China
| | - Enkhsaikhan Purevjav
- Qingqing Gu, Biao Xu, Department of Cardiology, Drum Tower Clinic Hospital, Nanjing Medical University, Nanjing 211166, Jiangsu Province, China
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38
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Hastings R, de Villiers CP, Hooper C, Ormondroyd L, Pagnamenta A, Lise S, Salatino S, Knight SJL, Taylor JC, Thomson KL, Arnold L, Chatziefthimiou SD, Konarev PV, Wilmanns M, Ehler E, Ghisleni A, Gautel M, Blair E, Watkins H, Gehmlich K. Combination of Whole Genome Sequencing, Linkage, and Functional Studies Implicates a Missense Mutation in Titin as a Cause of Autosomal Dominant Cardiomyopathy With Features of Left Ventricular Noncompaction. ACTA ACUST UNITED AC 2016; 9:426-435. [PMID: 27625337 PMCID: PMC5068189 DOI: 10.1161/circgenetics.116.001431] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 08/31/2016] [Indexed: 11/16/2022]
Abstract
Supplemental Digital Content is available in the text. Background— High throughput next-generation sequencing techniques have made whole genome sequencing accessible in clinical practice; however, the abundance of variation in the human genomes makes the identification of a disease-causing mutation on a background of benign rare variants challenging. Methods and Results— Here we combine whole genome sequencing with linkage analysis in a 3-generation family affected by cardiomyopathy with features of autosomal dominant left ventricular noncompaction cardiomyopathy. A missense mutation in the giant protein titin is the only plausible disease-causing variant that segregates with disease among the 7 surviving affected individuals, with interrogation of the entire genome excluding other potential causes. This A178D missense mutation, affecting a conserved residue in the second immunoglobulin-like domain of titin, was introduced in a bacterially expressed recombinant protein fragment and biophysically characterized in comparison to its wild-type counterpart. Multiple experiments, including size exclusion chromatography, small-angle x ray scattering, and circular dichroism spectroscopy suggest partial unfolding and domain destabilization in the presence of the mutation. Moreover, binding experiments in mammalian cells show that the mutation markedly impairs binding to the titin ligand telethonin. Conclusions— Here we present genetic and functional evidence implicating the novel A178D missense mutation in titin as the cause of a highly penetrant familial cardiomyopathy with features of left ventricular noncompaction. This expands the spectrum of titin’s roles in cardiomyopathies. It furthermore highlights that rare titin missense variants, currently often ignored or left uninterpreted, should be considered to be relevant for cardiomyopathies and can be identified by the approach presented here.
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39
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Mihailov E, Nikopensius T, Reigo A, Nikkolo C, Kals M, Aruaas K, Milani L, Seepter H, Metspalu A. Whole-exome sequencing identifies a potential TTN mutation in a multiplex family with inguinal hernia. Hernia 2016; 21:95-100. [PMID: 27115767 PMCID: PMC5281683 DOI: 10.1007/s10029-016-1491-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 04/06/2016] [Indexed: 11/28/2022]
Abstract
Purpose Inguinal hernia repair is one of the most common procedures in general surgery. Males are seven times more likely than females to develop a hernia and have a 27 % lifetime ‘risk’ of inguinal hernia repair. Several studies have demonstrated that a positive family history is an important risk factor for the development of primary inguinal hernia, which indicates that genetic factors may play important roles in the etiology of the disease. So far, the contribution of genetic factors and underlying mechanisms for inguinal hernia remain largely unknown. The aim of this study was to investigate a multiplex Estonian family with inguinal hernia across four generations. Methods The whole-exome sequencing was carried out in three affected family members and subsequent mutation screening using Sanger sequencing was performed in ten family members (six affected and four unaffected). Results Whole-exome sequencing in three affected family members revealed a heterozygous missense mutation c.88880A>C (p.Lys29627Thr; RefSeq NM_001256850.1) in the highly conserved myosin-binding A-band of the TTN gene. Sanger sequencing demonstrated that this mutation cosegregated with the disease in this family and was not present in ethnically matched control subjects. Conclusion We report that missense variant in the A-band of TTN is the strongest candidate mutation for autosomal-dominant inguinal hernia with incomplete penetrance. Electronic supplementary material The online version of this article (doi:10.1007/s10029-016-1491-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- E Mihailov
- Estonian Genome Center, University of Tartu, 23b Riia Street, 51010, Tartu, Estonia.
| | - T Nikopensius
- Estonian Genome Center, University of Tartu, 23b Riia Street, 51010, Tartu, Estonia
| | - A Reigo
- Estonian Genome Center, University of Tartu, 23b Riia Street, 51010, Tartu, Estonia
| | - C Nikkolo
- Surgery Clinic, Tartu University Hospital, 8 Puusepa Street, 51014, Tartu, Estonia
| | - M Kals
- Estonian Genome Center, University of Tartu, 23b Riia Street, 51010, Tartu, Estonia
| | - K Aruaas
- Institute of Molecular and Cell Biology, University of Tartu, 23 Riia Street, 51010, Tartu, Estonia
| | - L Milani
- Estonian Genome Center, University of Tartu, 23b Riia Street, 51010, Tartu, Estonia
| | - H Seepter
- Surgery Clinic, Tartu University Hospital, 8 Puusepa Street, 51014, Tartu, Estonia
| | - A Metspalu
- Estonian Genome Center, University of Tartu, 23b Riia Street, 51010, Tartu, Estonia.,Institute of Molecular and Cell Biology, University of Tartu, 23 Riia Street, 51010, Tartu, Estonia
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40
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An eccentric calpain, CAPN3/p94/calpain-3. Biochimie 2016; 122:169-87. [DOI: 10.1016/j.biochi.2015.09.010] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 09/07/2015] [Indexed: 01/09/2023]
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Sequeira V, van der Velden J. Historical perspective on heart function: the Frank-Starling Law. Biophys Rev 2015; 7:421-447. [PMID: 28510104 DOI: 10.1007/s12551-015-0184-4] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 09/21/2015] [Indexed: 12/18/2022] Open
Abstract
More than a century of research on the Frank-Starling Law has significantly advanced our knowledge about the working heart. The Frank-Starling Law mandates that the heart is able to match cardiac ejection to the dynamic changes occurring in ventricular filling and thereby regulates ventricular contraction and ejection. Significant efforts have been attempted to identify a common fundamental basis for the Frank-Starling heart and, although a unifying idea has still to come forth, there is mounting evidence of a direct relationship between length changes in individual constituents (cardiomyocytes) and their sensitivity to Ca2+ ions. As the Frank-Starling Law is a vital event for the healthy heart, it is of utmost importance to understand its mechanical basis in order to optimize and organize therapeutic strategies to rescue the failing human heart. The present review is a historic perspective on cardiac muscle function. We "revive" a century of scientific research on the heart's fundamental protein constituents (contractile proteins), to their assemblies in the muscle (the sarcomeres), culminating in a thorough overview of the several synergistically events that compose the Frank-Starling mechanism. It is the authors' personal beliefs that much can be gained by understanding the Frank-Starling relationship at the cellular and whole organ level, so that we can finally, in this century, tackle the pathophysiologic mechanisms underlying heart failure.
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Affiliation(s)
- Vasco Sequeira
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center, Van der Boechorststraat 7, 1081 BT, Amsterdam, The Netherlands.
| | - Jolanda van der Velden
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center, Van der Boechorststraat 7, 1081 BT, Amsterdam, The Netherlands.,ICIN- Netherlands Heart Institute, Utrecht, The Netherlands
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42
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Physiological and Neural Adaptations to Eccentric Exercise: Mechanisms and Considerations for Training. BIOMED RESEARCH INTERNATIONAL 2015; 2015:193741. [PMID: 26543850 PMCID: PMC4620252 DOI: 10.1155/2015/193741] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 01/13/2015] [Accepted: 02/09/2015] [Indexed: 11/08/2022]
Abstract
Eccentric exercise is characterized by initial unfavorable effects such as subcellular muscle damage, pain, reduced fiber excitability, and initial muscle weakness. However, stretch combined with overload, as in eccentric contractions, is an effective stimulus for inducing physiological and neural adaptations to training. Eccentric exercise-induced adaptations include muscle hypertrophy, increased cortical activity, and changes in motor unit behavior, all of which contribute to improved muscle function. In this brief review, neuromuscular adaptations to different forms of exercise are reviewed, the positive training effects of eccentric exercise are presented, and the implications for training are considered.
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The sarcomeric M-region: a molecular command center for diverse cellular processes. BIOMED RESEARCH INTERNATIONAL 2015; 2015:714197. [PMID: 25961035 PMCID: PMC4413555 DOI: 10.1155/2015/714197] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 02/08/2015] [Indexed: 02/07/2023]
Abstract
The sarcomeric M-region anchors thick filaments and withstands the mechanical stress of contractions by deformation, thus enabling distribution of physiological forces along the length of thick filaments. While the role of the M-region in supporting myofibrillar structure and contractility is well established, its role in mediating additional cellular processes has only recently started to emerge. As such, M-region is the hub of key protein players contributing to cytoskeletal remodeling, signal transduction, mechanosensing, metabolism, and proteasomal degradation. Mutations in genes encoding M-region related proteins lead to development of severe and lethal cardiac and skeletal myopathies affecting mankind. Herein, we describe the main cellular processes taking place at the M-region, other than thick filament assembly, and discuss human myopathies associated with mutant or truncated M-region proteins.
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Torre I, González-Tendero A, García-Cañadilla P, Crispi F, García-García F, Bijnens B, Iruretagoyena I, Dopazo J, Amat-Roldán I, Gratacós E. Permanent cardiac sarcomere changes in a rabbit model of intrauterine growth restriction. PLoS One 2014; 9:e113067. [PMID: 25402351 PMCID: PMC4234642 DOI: 10.1371/journal.pone.0113067] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 10/19/2014] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Intrauterine growth restriction (IUGR) induces fetal cardiac remodelling and dysfunction, which persists postnatally and may explain the link between low birth weight and increased cardiovascular mortality in adulthood. However, the cellular and molecular bases for these changes are still not well understood. We tested the hypothesis that IUGR is associated with structural and functional gene expression changes in the fetal sarcomere cytoarchitecture, which remain present in adulthood. METHODS AND RESULTS IUGR was induced in New Zealand pregnant rabbits by selective ligation of the utero-placental vessels. Fetal echocardiography demonstrated more globular hearts and signs of cardiac dysfunction in IUGR. Second harmonic generation microscopy (SHGM) showed shorter sarcomere length and shorter A-band and thick-thin filament interaction lengths, that were already present in utero and persisted at 70 postnatal days (adulthood). Sarcomeric M-band (GO: 0031430) functional term was over-represented in IUGR fetal hearts. CONCLUSION The results suggest that IUGR induces cardiac dysfunction and permanent changes on the sarcomere.
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Affiliation(s)
- Iratxe Torre
- BCNatal – Barcelona Center for Maternal-Fetal and Neonatal Medicine (Hospital Clínic and Hospital Sant Joan de Deu), IDIBAPS, University of Barcelona, and Centre for Biomedical Research on Rare Diseases (CIBER-ER), Barcelona, Spain
| | - Anna González-Tendero
- BCNatal – Barcelona Center for Maternal-Fetal and Neonatal Medicine (Hospital Clínic and Hospital Sant Joan de Deu), IDIBAPS, University of Barcelona, and Centre for Biomedical Research on Rare Diseases (CIBER-ER), Barcelona, Spain
| | - Patricia García-Cañadilla
- BCNatal – Barcelona Center for Maternal-Fetal and Neonatal Medicine (Hospital Clínic and Hospital Sant Joan de Deu), IDIBAPS, University of Barcelona, and Centre for Biomedical Research on Rare Diseases (CIBER-ER), Barcelona, Spain
- Physense, Departament de Tecnologies de la Informació i les Comunicacions (DTIC), Universitat Pompeu Fabra, Barcelona, Spain
| | - Fátima Crispi
- BCNatal – Barcelona Center for Maternal-Fetal and Neonatal Medicine (Hospital Clínic and Hospital Sant Joan de Deu), IDIBAPS, University of Barcelona, and Centre for Biomedical Research on Rare Diseases (CIBER-ER), Barcelona, Spain
| | - Francisco García-García
- Bioinformatics Department, Centro de Investigación Principe Felipe (CIPF), Valencia, Spain
- Functional Genomics Node, INB, CIPF, Valencia, Spain
| | - Bart Bijnens
- ICREA, Universitat Pompeu Fabra, Barcelona, Spain
| | - Igor Iruretagoyena
- BCNatal – Barcelona Center for Maternal-Fetal and Neonatal Medicine (Hospital Clínic and Hospital Sant Joan de Deu), IDIBAPS, University of Barcelona, and Centre for Biomedical Research on Rare Diseases (CIBER-ER), Barcelona, Spain
| | - Joaquin Dopazo
- Bioinformatics Department, Centro de Investigación Principe Felipe (CIPF), Valencia, Spain
- Functional Genomics Node, INB, CIPF, Valencia, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), CIPF, Valencia, Spain
| | - Ivan Amat-Roldán
- BCNatal – Barcelona Center for Maternal-Fetal and Neonatal Medicine (Hospital Clínic and Hospital Sant Joan de Deu), IDIBAPS, University of Barcelona, and Centre for Biomedical Research on Rare Diseases (CIBER-ER), Barcelona, Spain
| | - Eduard Gratacós
- BCNatal – Barcelona Center for Maternal-Fetal and Neonatal Medicine (Hospital Clínic and Hospital Sant Joan de Deu), IDIBAPS, University of Barcelona, and Centre for Biomedical Research on Rare Diseases (CIBER-ER), Barcelona, Spain
- * E-mail:
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Abstract
Ca²⁺ plays a crucial role in connecting membrane excitability with contraction in myocardium. The hallmark features of heart failure are mechanical dysfunction and arrhythmias; defective intracellular Ca²⁺ homeostasis is a central cause of contractile dysfunction and arrhythmias in failing myocardium. Defective Ca²⁺ homeostasis in heart failure can result from pathological alteration in the expression and activity of an increasingly understood collection of Ca²⁺ homeostatic and structural proteins, ion channels, and enzymes. This review focuses on the molecular mechanisms of defective Ca²⁺ cycling in heart failure and considers how fundamental understanding of these pathways may translate into novel and innovative therapies.
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Affiliation(s)
- Min Luo
- Division of Cardiovascular Medicine, Department of Internal Medicine, Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
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Guo CL, Harris NC, Wijeratne SS, Frey EW, Kiang CH. Multiscale mechanobiology: mechanics at the molecular, cellular, and tissue levels. Cell Biosci 2013; 3:25. [PMID: 23731596 PMCID: PMC3681589 DOI: 10.1186/2045-3701-3-25] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 04/24/2013] [Indexed: 11/10/2022] Open
Abstract
Mechanical force is present in all aspects of living systems. It affects the conformation of molecules, the shape of cells, and the morphology of tissues. All of these are crucial in architecture-dependent biological functions. Nanoscience of advanced materials has provided knowledge and techniques that can be used to understand how mechanical force is involved in biological systems, as well as to open new avenues to tailor-made bio-mimetic materials with desirable properties. In this article, we describe models and show examples of how force is involved in molecular functioning, cell shape patterning, and tissue morphology.
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Affiliation(s)
- Chin-Lin Guo
- Department of Bioengineering and Department of Applied Physics, California Institute of Technology, MC 138-78, Pasadena, CA 91125, USA.
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Ayme-Southgate AJ, Turner L, Southgate RJ. Molecular analysis of the muscle protein projectin in Lepidoptera. JOURNAL OF INSECT SCIENCE (ONLINE) 2013; 13:88. [PMID: 24206568 PMCID: PMC3835035 DOI: 10.1673/031.013.8801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Accepted: 05/08/2012] [Indexed: 06/02/2023]
Abstract
Striated muscles of both vertebrates and insects contain a third filament composed of the giant proteins, namely kettin and projectin (insects) and titin (vertebrates). All three proteins have been shown to contain several domains implicated in conferring elasticity, in particular a PEVK segment. In this study, the characterization of the projectin protein in the silkmoth, Bombyx mori L. (Lepidoptera: Bombycidae), and the monarch butterfly, Danaus plexippus L. (Lepidoptera: Nymphalidae), as well as a partial characterization in the Carolina sphinx, Manduca sexta L. (Lepidoptera: Sphingidae), are presented. This study showed that, similar to other insects, projectin's overall modular organization was conserved, but in contrast, the PEVK region had a highly divergent sequence. The analysis of alternative splicing in the PEVK region revealed a small number of possible isoforms and the lack of a flight-muscle specific variant, both characteristics being in sharp contrast with findings from other insects. The possible correlation with difference in flight muscle stiffness and physiology between Lepidoptera and other insect orders is discussed.
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Affiliation(s)
- A. J. Ayme-Southgate
- Department of Biology, College of Charleston, 66 George Street, Charleston, SC 29401
| | - L. Turner
- Department of Biology, College of Charleston, 66 George Street, Charleston, SC 29401
- Current address: Central Carolina Technical College, Sumter, SC
| | - R. J. Southgate
- Department of Biology, College of Charleston, 66 George Street, Charleston, SC 29401
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Huber T, Grama L, Hetényi C, Schay G, Fülöp L, Penke B, Kellermayer MSZ. Conformational dynamics of titin PEVK explored with FRET spectroscopy. Biophys J 2012; 103:1480-9. [PMID: 23062340 DOI: 10.1016/j.bpj.2012.08.042] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 08/03/2012] [Accepted: 08/09/2012] [Indexed: 01/05/2023] Open
Abstract
The proline-, glutamate-, valine-, and lysine-rich (PEVK) domain of the giant muscle protein titin is thought to be an intrinsically unstructured random-coil segment. Various observations suggest, however, that the domain may not be completely devoid of internal interactions and structural features. To test the validity of random polymer models for PEVK, we determined the mean end-to-end distances of an 11- and a 21-residue synthetic PEVK peptide, calculated from the efficiency of the fluorescence resonance energy transfer (FRET) between an N-terminal intrinsic tryptophan donor and a synthetically added C-terminal IAEDANS acceptor obtained in steady-state and time-resolved experiments. We find that the contour-length scaling of mean end-to-end distance deviates from predictions of a purely statistical polymer chain. Furthermore, the addition of guanidine hydrochloride decreased, whereas the addition of salt increased the FRET efficiency, pointing at the disruption of structure-stabilizing interactions. Increasing temperature between 10 and 50°C increased the normalized FRET efficiency in both peptides but with different trajectories, indicating that their elasticity and conformational stability are different. Simulations suggest that whereas the short PEVK peptide displays an overall random structure, the long PEVK peptide retains residual, loose helical configurations. Transitions in the local structure and dynamics of the PEVK domain may play a role in the modulation of passive muscle mechanics.
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Affiliation(s)
- Tamás Huber
- Department of Biophysics and Radiation Biology and MTA-SE Molecular Biophysics Research Group, Semmelweis University, Budapest, Hungary
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Edman KAP. Residual force enhancement after stretch in striated muscle. A consequence of increased myofilament overlap? J Physiol 2012; 590:1339-45. [PMID: 22331422 DOI: 10.1113/jphysiol.2011.222729] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
When skeletal muscle is stretched above optimal sarcomere length during tetanic activity there is an increase in force that stays above the isometric force level throughout the activity period. This long-lasting increase in contractile force, generally referred to as 'residual force enhancement after stretch' (FE(resid)), has been studied in great detail in various muscle preparations over more than half a century. Substantial evidence has been presented to show that non-uniform sarcomere behaviour plays a major part in the development of FE(resid). However, in a great number of recent studies the role of sarcomere non-uniformity has been challenged and alternative mechanisms have instead been proposed to explain the increase in force such as enhancement of cross-bridge function and/or strengthening of parallel elastic elements along the muscle fibres. This article presents a short review of the salient features of FE(resid) and provides evidence that non-uniform sarcomere behaviour is indeed likely to play a major role in the development of FE(resid). Electron microscopical studies of fibres rapidly fixed after active stretch demonstrate that, dispersed in the preparation, there are assymetrical length changes within the two halves of myofibrillar sarcomeres resulting in greater filament overlap in one half of the sarcomere than in the opposite sarcomere half. Sarcomere halves with increased filament overlap will consequently be in a situation where they are able to produce a greater force than that recorded in the isometric control. Weaker regions in series will be able to keep the enhanced force by recruitment of elastic elements.
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Affiliation(s)
- K A P Edman
- Department of Experimental Medical Science, Biomedical Centre, F11, University of Lund, S-221 84 Lund, Sweden.
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Glenn TK, Honar H, Liu H, ter Keurs HEDJ, Lee SS. Role of cardiac myofilament proteins titin and collagen in the pathogenesis of diastolic dysfunction in cirrhotic rats. J Hepatol 2011; 55:1249-55. [PMID: 21703204 DOI: 10.1016/j.jhep.2011.02.030] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Revised: 02/01/2011] [Accepted: 02/16/2011] [Indexed: 02/09/2023]
Abstract
BACKGROUND & AIMS Significance of diastolic dysfunction in cirrhotic cardiomyopathy has been brought to the forefront with several reports of unexpected heart failure following liver transplantation and transjugular intrahepatic portosystemic stent-shunt, but the etiology remains unclear. The present study investigated the role of passive tension regulators - titin and collagen - in the pathogenesis of this condition. METHODS Cirrhosis was induced by bile duct ligation (BDL) in rats, while controls underwent bile duct inspection with no ligation. Four weeks after operation, cardiac mRNA and protein levels of titin, collagen, and protein kinase A (PKA) were determined. Diastolic function was examined in isolated right ventricular cardiomyocytes, while passive tension was examined in right ventricular trabeculae muscles. RESULTS In BDL animals, diastolic return velocity was significantly decreased, relaxation time increased and passive tension increased. However, no significant difference in mRNA and protein levels of titin was observed. PKA mRNA and protein levels were significantly decreased in BDL animals. Collagen levels were also significantly altered in the BDL group. CONCLUSIONS Therefore, diastolic dysfunction exists in cirrhosis with alterations in titin modulation, PKA levels, and collagen configuration contributing to the pathogenesis of this condition.
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