1
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Ruud M, Frisk M, Melleby AO, Norseng PA, Mohamed BA, Li J, Aronsen JM, Setterberg IE, Jakubiczka J, van Hout I, Coffey S, Shen X, Nygård S, Lunde IG, Tønnessen T, Jones PP, Sjaastad I, Gullestad L, Toischer K, Dahl CP, Christensen G, Louch WE. Regulation of cardiomyocyte t-tubule structure by preload and afterload: Roles in cardiac compensation and decompensation. J Physiol 2024. [PMID: 38686538 DOI: 10.1113/jp284566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 04/02/2024] [Indexed: 05/02/2024] Open
Abstract
Mechanical load is a potent regulator of cardiac structure and function. Although high workload during heart failure is associated with disruption of cardiomyocyte t-tubules and Ca2+ homeostasis, it remains unclear whether changes in preload and afterload may promote adaptive t-tubule remodelling. We examined this issue by first investigating isolated effects of stepwise increases in load in cultured rat papillary muscles. Both preload and afterload increases produced a biphasic response, with the highest t-tubule densities observed at moderate loads, whereas excessively low and high loads resulted in low t-tubule levels. To determine the baseline position of the heart on this bell-shaped curve, mice were subjected to mildly elevated preload or afterload (1 week of aortic shunt or banding). Both interventions resulted in compensated cardiac function linked to increased t-tubule density, consistent with ascension up the rising limb of the curve. Similar t-tubule proliferation was observed in human patients with moderately increased preload or afterload (mitral valve regurgitation, aortic stenosis). T-tubule growth was associated with larger Ca2+ transients, linked to upregulation of L-type Ca2+ channels, Na+-Ca2+ exchanger, mechanosensors and regulators of t-tubule structure. By contrast, marked elevation of cardiac load in rodents and patients advanced the heart down the declining limb of the t-tubule-load relationship. This bell-shaped relationship was lost in the absence of electrical stimulation, indicating a key role of systolic stress in controlling t-tubule plasticity. In conclusion, modest augmentation of workload promotes compensatory increases in t-tubule density and Ca2+ cycling, whereas this adaptation is reversed in overloaded hearts during heart failure progression. KEY POINTS: Excised papillary muscle experiments demonstrated a bell-shaped relationship between cardiomyocyte t-tubule density and workload (preload or afterload), which was only present when muscles were electrically stimulated. The in vivo heart at baseline is positioned on the rising phase of this curve because moderate increases in preload (mice with brief aortic shunt surgery, patients with mitral valve regurgitation) resulted in t-tubule growth. Moderate increases in afterload (mice and patients with mild aortic banding/stenosis) similarly increased t-tubule density. T-tubule proliferation was associated with larger Ca2+ transients, with upregulation of the L-type Ca2+ channel, Na+-Ca2+ exchanger, mechanosensors and regulators of t-tubule structure. By contrast, marked elevation of cardiac load in rodents and patients placed the heart on the declining phase of the t-tubule-load relationship, promoting heart failure progression. The dependence of t-tubule structure on preload and afterload thus enables both compensatory and maladaptive remodelling, in rodents and humans.
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Affiliation(s)
- Marianne Ruud
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Michael Frisk
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Arne Olav Melleby
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Per Andreas Norseng
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Belal A Mohamed
- Department of Cardiology and Pneumology, Georg-August-University, Göttingen, Germany
| | - Jia Li
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Jan Magnus Aronsen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
| | - Ingunn E Setterberg
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Joanna Jakubiczka
- Department of Cardiology and Pneumology, Georg-August-University, Göttingen, Germany
| | - Isabelle van Hout
- Department of Physiology, School of Biomedical Sciences and HeartOtago, University of Otago, Dunedin, New Zealand
| | - Sean Coffey
- Department of Medicine and HeartOtago, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - Xin Shen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Ståle Nygård
- Department of Informatics, University of Oslo, Oslo, Norway
| | - Ida G Lunde
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Theis Tønnessen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
- Department of Cardiothoracic Surgery, Oslo University Hospital, Oslo, Norway
| | - Peter P Jones
- Department of Physiology, School of Biomedical Sciences and HeartOtago, University of Otago, Dunedin, New Zealand
| | - Ivar Sjaastad
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Lars Gullestad
- Department of Cardiology, Oslo University Hospital, Oslo, Norway
| | - Karl Toischer
- Department of Cardiology and Pneumology, Georg-August-University, Göttingen, Germany
| | - Cristen P Dahl
- Department of Cardiology, Oslo University Hospital, Oslo, Norway
| | - Geir Christensen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
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2
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Li RG, Li X, Morikawa Y, Grisanti-Canozo FJ, Meng F, Tsai CR, Zhao Y, Liu L, Kim J, Xie B, Klysik E, Liu S, Samee MAH, Martin JF. YAP induces a neonatal-like pro-renewal niche in the adult heart. NATURE CARDIOVASCULAR RESEARCH 2024; 3:283-300. [PMID: 38510108 PMCID: PMC10954255 DOI: 10.1038/s44161-024-00428-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 01/12/2024] [Indexed: 03/22/2024]
Abstract
After myocardial infarction (MI), mammalian hearts do not regenerate, and the microenvironment is disrupted. Hippo signaling loss of function with activation of transcriptional co-factor YAP induces heart renewal and rebuilds the post-MI microenvironment. In this study, we investigated adult renewal-competent mouse hearts expressing an active version of YAP, called YAP5SA, in cardiomyocytes (CMs). Spatial transcriptomics and single-cell RNA sequencing revealed a conserved, renewal-competent CM cell state called adult (a)CM2 with high YAP activity. aCM2 co-localized with cardiac fibroblasts (CFs) expressing complement pathway component C3 and macrophages (MPs) expressing C3ar1 receptor to form a cellular triad in YAP5SA hearts and renewal-competent neonatal hearts. Although aCM2 was detected in adult mouse and human hearts, the cellular triad failed to co-localize in these non-renewing hearts. C3 and C3ar1 loss-of-function experiments indicated that C3a signaling between MPs and CFs was required to assemble the pro-renewal aCM2, C3+ CF and C3ar1+ MP cellular triad.
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Affiliation(s)
- Rich Gang Li
- Cardiomyocyte Renewal Laboratory, Texas Heart Institute, Houston, TX, USA
- McGill Gene Editing Laboratory, Texas Heart Institute, Houston, TX, USA
- These authors contributed equally: Rich Gang Li, Xiao Li
| | - Xiao Li
- McGill Gene Editing Laboratory, Texas Heart Institute, Houston, TX, USA
- These authors contributed equally: Rich Gang Li, Xiao Li
| | - Yuka Morikawa
- Cardiomyocyte Renewal Laboratory, Texas Heart Institute, Houston, TX, USA
| | - Francisco J. Grisanti-Canozo
- Cardiomyocyte Renewal Laboratory, Texas Heart Institute, Houston, TX, USA
- Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, USA
| | - Fansen Meng
- Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, USA
| | - Chang-Ru Tsai
- Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, USA
| | - Yi Zhao
- McGill Gene Editing Laboratory, Texas Heart Institute, Houston, TX, USA
| | - Lin Liu
- McGill Gene Editing Laboratory, Texas Heart Institute, Houston, TX, USA
| | - Jong Kim
- Cardiomyocyte Renewal Laboratory, Texas Heart Institute, Houston, TX, USA
| | - Bing Xie
- Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, USA
| | - Elzbieta Klysik
- Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, USA
| | - Shijie Liu
- Cardiomyocyte Renewal Laboratory, Texas Heart Institute, Houston, TX, USA
| | - Md Abul Hassan Samee
- Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, USA
| | - James F. Martin
- Cardiomyocyte Renewal Laboratory, Texas Heart Institute, Houston, TX, USA
- McGill Gene Editing Laboratory, Texas Heart Institute, Houston, TX, USA
- Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, USA
- Center for Organ Repair and Renewal, Baylor College of Medicine, Houston, TX, USA
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3
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Yoo SH. Circadian regulation of cardiac muscle function and protein degradation. Chronobiol Int 2023; 40:4-12. [PMID: 34521283 PMCID: PMC8918439 DOI: 10.1080/07420528.2021.1957911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 07/12/2021] [Accepted: 07/13/2021] [Indexed: 10/20/2022]
Abstract
The circadian clock plays a fundamental role in physiology. In particular, the heart is a target organ where the clock orchestrates various aspects of cardiac function. At the molecular level, the clock machinery governs daily rhythms of gene expression. Such circadian regulation is in tune with the dynamic nature of heart structure and function, and provides the foundation for chronotherapeutic applications in cardiovascular diseases. In comparison, a regulatory role of the clock in cardiac protein degradation is poorly documented. Sarcomere is the structural and functional unit responsible for cardiac muscle contraction, and sarcomere components are closely regulated by protein folding and proteolysis. Emerging evidence supports a role of the circadian clock in governing sarcomere integrity and function. Particularly, recent studies uncovered a circadian regulation of a core sarcomere component TCAP. It is possible that circadian regulation of the cardiac muscle protein turnover is a key regulatory mechanism underlying cardiac remodeling in response to physiological and environmental stimuli. While the detailed regulatory mechanisms and the molecular links to cardiac (patho)physiology remain to be further studied, therapeutic strategies targeting circadian control in the heart may markedly enhance intervention outcomes against cardiovascular disease.
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Affiliation(s)
- Seung-Hee Yoo
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston, Houston, Texas, USA
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4
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Noureddine M, Gehmlich K. Structural and signaling proteins in the Z-disk and their role in cardiomyopathies. Front Physiol 2023; 14:1143858. [PMID: 36935760 PMCID: PMC10017460 DOI: 10.3389/fphys.2023.1143858] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 02/21/2023] [Indexed: 03/06/2023] Open
Abstract
The sarcomere is the smallest functional unit of muscle contraction. It is delineated by a protein-rich structure known as the Z-disk, alternating with M-bands. The Z-disk anchors the actin-rich thin filaments and plays a crucial role in maintaining the mechanical stability of the cardiac muscle. A multitude of proteins interact with each other at the Z-disk and they regulate the mechanical properties of the thin filaments. Over the past 2 decades, the role of the Z-disk in cardiac muscle contraction has been assessed widely, however, the impact of genetic variants in Z-disk proteins has still not been fully elucidated. This review discusses the various Z-disk proteins (alpha-actinin, filamin C, titin, muscle LIM protein, telethonin, myopalladin, nebulette, and nexilin) and Z-disk-associated proteins (desmin, and obscurin) and their role in cardiac structural stability and intracellular signaling. This review further explores how genetic variants of Z-disk proteins are linked to inherited cardiac conditions termed cardiomyopathies.
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Affiliation(s)
- Maya Noureddine
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- *Correspondence: Maya Noureddine, ; Katja Gehmlich,
| | - Katja Gehmlich
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence Oxford, University of Oxford, Oxford, United Kingdom
- *Correspondence: Maya Noureddine, ; Katja Gehmlich,
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5
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Baraldo M, Zorzato S, Dondjang AHT, Geremia A, Nogara L, Dumitras AG, Canato M, Marcucci L, Nolte H, Blaauw B. Inducible deletion of raptor and mTOR from adult skeletal muscle impairs muscle contractility and relaxation. J Physiol 2022; 600:5055-5075. [PMID: 36255030 DOI: 10.1113/jp283686] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 09/20/2022] [Indexed: 01/05/2023] Open
Abstract
Skeletal muscle weakness has been associated with different pathological conditions, including sarcopenia and muscular dystrophy, and is accompanied by altered mammalian target of rapamycin (mTOR) signalling. We wanted to elucidate the functional role of mTOR in muscle contractility. Most loss-of-function studies for mTOR signalling have used the drug rapamycin to inhibit some of the signalling downstream of mTOR. However, given that rapamycin does not inhibit all mTOR signalling completely, we generated a double knockout for mTOR and for the scaffold protein of mTORC1, raptor, in skeletal muscle. We found that double knockout in mice results in a more severe phenotype compared with deletion of raptor or mTOR alone. Indeed, these animals display muscle weakness, increased fibre denervation and a slower muscle relaxation following tetanic stimulation. This is accompanied by a shift towards slow-twitch fibres and changes in the expression levels of calcium-related genes, such as Serca1 and Casq1. Double knockout mice show a decrease in calcium decay kinetics after tetanus in vivo, suggestive of a reduced calcium reuptake. In addition, RNA sequencing analysis revealed that many downregulated genes, such as Tcap and Fhod3, are linked to sarcomere organization. These results suggest a key role for mTOR signalling in maintaining proper fibre relaxation in skeletal muscle. KEY POINTS: Skeletal muscle wasting and weakness have been associated with different pathological conditions, including sarcopenia and muscular dystrophy, and are accompanied by altered mammalian target of rapamycin (mTOR) signalling. Mammalian target of rapamycin plays a crucial role in the maintenance of muscle mass and functionality. We found that the loss of both mTOR and raptor results in contractile abnormalities, with severe muscle weakness and delayed relaxation following tetanic stimulation. These results are associated with alterations in the expression of genes involved in sarcomere organization and calcium handling and with an impairment in calcium reuptake after contraction. Taken together, these results provide a mechanistic insight into the role of mTOR in muscle contractility.
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Affiliation(s)
- Martina Baraldo
- Venetian Institute of Molecular Medicine (VIMM), Padova, Italy.,Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Sabrina Zorzato
- Venetian Institute of Molecular Medicine (VIMM), Padova, Italy
| | - Achille Homère Tchampda Dondjang
- Venetian Institute of Molecular Medicine (VIMM), Padova, Italy.,Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Alessia Geremia
- Venetian Institute of Molecular Medicine (VIMM), Padova, Italy.,Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Leonardo Nogara
- Venetian Institute of Molecular Medicine (VIMM), Padova, Italy.,Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Ana Georgia Dumitras
- Venetian Institute of Molecular Medicine (VIMM), Padova, Italy.,Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Marta Canato
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Lorenzo Marcucci
- Department of Biomedical Sciences, University of Padova, Padova, Italy.,Center for Biosystems Dynamics Research, RIKEN, Suita, Japan
| | - Hendrik Nolte
- Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany.,Center for Molecular Medicine (CMMC), University of Cologne, Cologne, Germany
| | - Bert Blaauw
- Venetian Institute of Molecular Medicine (VIMM), Padova, Italy.,Department of Biomedical Sciences, University of Padova, Padova, Italy
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6
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Porcine Circovirus type 2 infected myocardial tissue transcriptome signature. Gene 2022; 836:146670. [PMID: 35714796 DOI: 10.1016/j.gene.2022.146670] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 06/03/2022] [Accepted: 06/10/2022] [Indexed: 11/21/2022]
Abstract
The goal of this study was to compare the global gene expression profile in cardiac tissues of pig infected with porcine circovirus 2 (PCV2) to that of healthy cells. Since PCV2 infection causes severe cardiovascular lesions, the myocardial tissue model was chosen for this study. In High-throughput transcriptome analysis, DESeq2 and CLC genomics workbench analyses revealed a total of 196 significantly differentially expressed genes (DEGs) (p-value < 0.05). Furthermore, 194 transcripts were upregulated, while only two were downregulated (HSPA6 and DNAJA1), with fold changes ranging from 16.293 to -10.002. Among the KEGG canonical pathways targeted by the DEGs in the functional analysis, adrenergic signalling in cardiomyocytes, Cardiac Muscle Contraction, Hypertrophic Cardiomyopathy (HCM), and Dilated Cardiomyopathy (DCM) tends to be enriched. The differentially expressed highly connected (DEHC) biomarker genes in pathogenicity of PCV2 infection, such as LDB3, MYOZ2, CASQ2, TNNT2, MLC2V, MYBPC3, ACTC1, TCAP, TNNI3, TRDN, CSRP3, MYL3, RYR2, LMOD2, MYH7, etc., were identified using protein-protein interaction (PPI) network analysis. The study might provide detailed information on the dysregulated genes and biological pathways in infected myocardial tissues that may be essential for PCV2-related heart pathology.
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7
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Lv X, Zhang R, Xu L, Wang G, Yan C, Lin P. Tcap Deficiency in Zebrafish Leads to ROS Production and Mitophagy, and Idebenone Improves its Phenotypes. Front Cell Dev Biol 2022; 10:836464. [PMID: 35372370 PMCID: PMC8964517 DOI: 10.3389/fcell.2022.836464] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 02/22/2022] [Indexed: 11/21/2022] Open
Abstract
Limb-girdle muscular dystrophy 2G (LGMD2G) is a subtype of limb-girdle muscular dystrophy. However, the disease’s mechanisms are still not fully understood, and no established therapeutic targets have been found. Using a morpholino-based knockdown approach, we established an LGMD2G zebrafish model. In this study, we found that the ROS level increased in LGMD2G zebrafish. The expression of the mitophagy-related protein BNIP3L, LC3A-II/LC3A-I, and LAMP1 were increased in LGMD2G zebrafish. The oxygen consumption rate and citrate synthase expression was significantly decreased. Thus, mitophagy was presumed to be involved in the LGMD2G to reduce ROS levels. Then, we administered vitamin C, coenzyme Q10, idebenone, metformin, or dexamethasone to rescue LGMD2G in zebrafish. Idebenone reduced the curly tail phenotype and ROS level. Also, it reduced BNIP3L expression in LGMD2G zebrafish models and improved their motor function. In conclusion, mitophagy might be involved in the LGMD2G, and idebenone ameliorated LGMD2G by downregulating ROS level.
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Affiliation(s)
- Xiaoqing Lv
- Department of Neurology and Research Institute of Neuromuscular and Neurodegenerative Diseases, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Rui Zhang
- Department of Neurology and Research Institute of Neuromuscular and Neurodegenerative Diseases, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Ling Xu
- Department of Neurology and Research Institute of Neuromuscular and Neurodegenerative Diseases, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Guangyu Wang
- Department of Neurology and Research Institute of Neuromuscular and Neurodegenerative Diseases, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Chuanzhu Yan
- Department of Neurology and Research Institute of Neuromuscular and Neurodegenerative Diseases, Qilu Hospital, Shandong University, Jinan, China
| | - Pengfei Lin
- Department of Neurology and Research Institute of Neuromuscular and Neurodegenerative Diseases, Qilu Hospital, Shandong University, Jinan, China
- *Correspondence: Pengfei Lin,
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8
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Kim J, Shanmugasundaram A, Lee DW. Enhancement of cardiac contractility using gold-coated SU-8 cantilevers and their application to drug-induced cardiac toxicity tests. Analyst 2021; 146:6768-6779. [PMID: 34642716 DOI: 10.1039/d1an01337h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Herein, we propose an array of gold (Au)-coated SU-8 cantilevers with microgrooves for improved maturation of cardiomyocytes and describe its applications to drug-induced cardiac toxicity tests. Firstly, we evaluated the effect of cell culture substrates such as polydimethylsiloxane (PDMS), polyimide (PI), and SU-8 on the cardiomyocyte's maturation. Among these, the SU-8 with microgroove structures exhibits improved cardiomyocyte maturation. Further, thin layers of graphene and Au are coated on SU-8 substrates and the effects of these materials on cardiomyocyte maturation are evaluated by analyzing the expression of proteins such as alpha-actinin, Connexin 43 (Cx43), and Vinculin. While both conductive materials enhanced protein expression when compared to bare SU-8, the Au-coated SU-8 substrates demonstrated superior cardiomyocyte maturation. The cantilever structure is constructed using microgroove patterned SU-8 with and without an Au coating. The Au-coated SU-8 cantilever showed maximum displacement of 17.6 ± 0.3 μm on day 21 compared to bare SU-8 (14.2 ± 0.4 μm) owing to improved cardiomyocytes maturation. Verapamil and quinidine are used to characterize drug-induced changes in the contraction characteristics of cardiomyocytes on bare and Au-coated SU-8 cantilevers. The relative contraction forces and beat rates changed according to the calcium and sodium channel related drugs. Matured cardiomyocytes are less influenced by the drugs compared to immature cardiomyocytes and showed reliable IC50 values. These results indicate that the proposed Au-coated SU-8 cantilever array could help improve the accuracy of toxicity screening results by allowing for the use of cardiomyocytes that have been matured on the drug screening platform.
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Affiliation(s)
- Jongyun Kim
- Graduate School of Mechanical Engineering, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Arunkumar Shanmugasundaram
- MEMS and Nanotechnology Laboratory, School of Mechanical Engineering, Chonnam National University, Gwangju 61186, Republic of Korea.
| | - Dong-Weon Lee
- MEMS and Nanotechnology Laboratory, School of Mechanical Engineering, Chonnam National University, Gwangju 61186, Republic of Korea. .,Center for Next-Generation Sensor Research and Development, Chonnam National University, Gwangju 61186, Republic of Korea.,Advanced Medical Device Research Center for Cardiovascular Disease, Chonnam National University, Gwangju 61186, Republic of Korea
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9
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Setterberg IE, Le C, Frisk M, Li J, Louch WE. The Physiology and Pathophysiology of T-Tubules in the Heart. Front Physiol 2021; 12:718404. [PMID: 34566684 PMCID: PMC8458775 DOI: 10.3389/fphys.2021.718404] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 07/07/2021] [Indexed: 12/18/2022] Open
Abstract
In cardiomyocytes, invaginations of the sarcolemmal membrane called t-tubules are critically important for triggering contraction by excitation-contraction (EC) coupling. These structures form functional junctions with the sarcoplasmic reticulum (SR), and thereby enable close contact between L-type Ca2+ channels (LTCCs) and Ryanodine Receptors (RyRs). This arrangement in turn ensures efficient triggering of Ca2+ release, and contraction. While new data indicate that t-tubules are capable of exhibiting compensatory remodeling, they are also widely reported to be structurally and functionally compromised during disease, resulting in disrupted Ca2+ homeostasis, impaired systolic and/or diastolic function, and arrhythmogenesis. This review summarizes these findings, while highlighting an emerging appreciation of the distinct roles of t-tubules in the pathophysiology of heart failure with reduced and preserved ejection fraction (HFrEF and HFpEF). In this context, we review current understanding of the processes underlying t-tubule growth, maintenance, and degradation, underscoring the involvement of a variety of regulatory proteins, including junctophilin-2 (JPH2), amphiphysin-2 (BIN1), caveolin-3 (Cav3), and newer candidate proteins. Upstream regulation of t-tubule structure/function by cardiac workload and specifically ventricular wall stress is also discussed, alongside perspectives for novel strategies which may therapeutically target these mechanisms.
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Affiliation(s)
- Ingunn E Setterberg
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Christopher Le
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Michael Frisk
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Jia Li
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
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10
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Jiang H, Hooper C, Kelly M, Steeples V, Simon JN, Beglov J, Azad AJ, Leinhos L, Bennett P, Ehler E, Kalisch-Smith JI, Sparrow DB, Fischer R, Heilig R, Isackson H, Ehsan M, Patone G, Huebner N, Davies B, Watkins H, Gehmlich K. Functional analysis of a gene-edited mouse model to gain insights into the disease mechanisms of a titin missense variant. Basic Res Cardiol 2021; 116:14. [PMID: 33637999 PMCID: PMC7910237 DOI: 10.1007/s00395-021-00853-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 02/10/2021] [Indexed: 11/03/2022]
Abstract
Titin truncating variants are a well-established cause of cardiomyopathy; however, the role of titin missense variants is less well understood. Here we describe the generation of a mouse model to investigate the underlying disease mechanism of a previously reported titin A178D missense variant identified in a family with non-compaction and dilated cardiomyopathy. Heterozygous and homozygous mice carrying the titin A178D missense variant were characterised in vivo by echocardiography. Heterozygous mice had no detectable phenotype at any time point investigated (up to 1 year). By contrast, homozygous mice developed dilated cardiomyopathy from 3 months. Chronic adrenergic stimulation aggravated the phenotype. Targeted transcript profiling revealed induction of the foetal gene programme and hypertrophic signalling pathways in homozygous mice, and these were confirmed at the protein level. Unsupervised proteomics identified downregulation of telethonin and four-and-a-half LIM domain 2, as well as the upregulation of heat shock proteins and myeloid leukaemia factor 1. Loss of telethonin from the cardiac Z-disc was accompanied by proteasomal degradation; however, unfolded telethonin accumulated in the cytoplasm, leading to a proteo-toxic response in the mice.We show that the titin A178D missense variant is pathogenic in homozygous mice, resulting in cardiomyopathy. We also provide evidence of the disease mechanism: because the titin A178D variant abolishes binding of telethonin, this leads to its abnormal cytoplasmic accumulation. Subsequent degradation of telethonin by the proteasome results in proteasomal overload, and activation of a proteo-toxic response. The latter appears to be a driving factor for the cardiomyopathy observed in the mouse model.
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Affiliation(s)
- He Jiang
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence Oxford, University of Oxford, Oxford, OX3 9DU, UK
| | - Charlotte Hooper
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence Oxford, University of Oxford, Oxford, OX3 9DU, UK
| | - Matthew Kelly
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence Oxford, University of Oxford, Oxford, OX3 9DU, UK
| | - Violetta Steeples
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence Oxford, University of Oxford, Oxford, OX3 9DU, UK
| | - Jillian N Simon
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence Oxford, University of Oxford, Oxford, OX3 9DU, UK
| | - Julia Beglov
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence Oxford, University of Oxford, Oxford, OX3 9DU, UK
| | - Amar J Azad
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence Oxford, University of Oxford, Oxford, OX3 9DU, UK
| | - Lisa Leinhos
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence Oxford, University of Oxford, Oxford, OX3 9DU, UK
| | - Pauline Bennett
- Randall Centre for Cell and Molecular Biophysics, School of Cardiovascular Medicine and Sciences, King's College London BHF Centre of Research Excellence, London, UK
| | - Elisabeth Ehler
- Randall Centre for Cell and Molecular Biophysics, School of Cardiovascular Medicine and Sciences, King's College London BHF Centre of Research Excellence, London, UK
| | | | - Duncan B Sparrow
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Roman Fischer
- Nuffield Department of Clinical Medicine, Target Discovery Institute, University of Oxford, Oxford, UK
| | - Raphael Heilig
- Nuffield Department of Clinical Medicine, Target Discovery Institute, University of Oxford, Oxford, UK
| | - Henrik Isackson
- Department of Medical Sciences, Cardiology, Uppsala University, Uppsala, Sweden
- Department of Medical Cell Biology, Integrative Physiology, Uppsala University, Uppsala, Sweden
| | - Mehroz Ehsan
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence Oxford, University of Oxford, Oxford, OX3 9DU, UK
| | - Giannino Patone
- Max Delbrueck Centre for Molecular Medicine, Berlin, Germany
| | - Norbert Huebner
- Max Delbrueck Centre for Molecular Medicine, Berlin, Germany
| | - Benjamin Davies
- Transgenic Core, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Hugh Watkins
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence Oxford, University of Oxford, Oxford, OX3 9DU, UK
| | - Katja Gehmlich
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence Oxford, University of Oxford, Oxford, OX3 9DU, UK.
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, B15 2TT, UK.
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11
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Mellor NG, Pham T, Tran K, Loiselle DS, Ward M, Taberner AJ, Crossman DJ, Han J. Disruption of transverse-tubular network reduces energy efficiency in cardiac muscle contraction. Acta Physiol (Oxf) 2021; 231:e13545. [PMID: 32757472 DOI: 10.1111/apha.13545] [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: 05/15/2020] [Revised: 07/16/2020] [Accepted: 07/31/2020] [Indexed: 11/29/2022]
Abstract
AIM Altered organization of the transverse-tubular network is an early pathological event occurring even prior to the onset of heart failure. Such t-tubular remodelling disturbs the synchrony and signalling between membranous and intracellular ion channels, exchangers, receptors and ATPases essential in the dynamics of excitation-contraction coupling, leading to ionic abnormality and mechanical dysfunction in heart disease progression. In this study, we investigated whether a disrupted t-tubular network has a direct effect on cardiac mechano-energetics. Our aim was to understand the fundamental link between t-tubular remodelling and impaired energy metabolism, both of which are characteristics of heart failure. We thus studied healthy tissue preparations in which cellular processes are not altered by any disease event. METHODS We exploited the "formamide-detubulation" technique to acutely disrupt the t-tubular network in rat left-ventricular trabeculae. We assessed the energy utilization by cellular Ca2+ cycling and by crossbridge cycling, and quantified the change of energy efficiency following detubulation. For these measurements, trabeculae were mounted in a microcalorimeter where force and heat output were simultaneously measured. RESULTS Following structural disorganization from detubulation, muscle heat output associated with Ca2+ cycling was reduced, indicating impaired intracellular Ca2+ homeostasis. This led to reduced force production and heat output by crossbridge cycling. The reduction in force-length work was not paralleled by proportionate reduction in the heat output and, as such, energy efficiency was reduced. CONCLUSIONS These results reveal the direct energetic consequences of disrupted t-tubular network, linking the energy disturbance and the t-tubular remodelling typically observed in heart failure.
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Affiliation(s)
- Nicholas G. Mellor
- Auckland Bioengineering Institute The University of Auckland Auckland New Zealand
| | - Toan Pham
- Auckland Bioengineering Institute The University of Auckland Auckland New Zealand
| | - Kenneth Tran
- Auckland Bioengineering Institute The University of Auckland Auckland New Zealand
| | - Denis S. Loiselle
- Auckland Bioengineering Institute The University of Auckland Auckland New Zealand
- Department of Physiology The University of Auckland Auckland New Zealand
| | - Marie‐Louise Ward
- Department of Physiology The University of Auckland Auckland New Zealand
| | - Andrew J. Taberner
- Auckland Bioengineering Institute The University of Auckland Auckland New Zealand
- Department of Engineering Science The University of Auckland Auckland New Zealand
| | - David J. Crossman
- Department of Physiology The University of Auckland Auckland New Zealand
| | - June‐Chiew Han
- Auckland Bioengineering Institute The University of Auckland Auckland New Zealand
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12
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Lewis HR, Eminaga S, Gautel M, Avkiran M. Phosphorylation at Serines 157 and 161 Is Necessary for Preserving Cardiac Expression Level and Functions of Sarcomeric Z-Disc Protein Telethonin. Front Physiol 2021; 12:732020. [PMID: 34566695 PMCID: PMC8455888 DOI: 10.3389/fphys.2021.732020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 08/16/2021] [Indexed: 11/13/2022] Open
Abstract
Aims: In cardiac myocytes, the sarcomeric Z-disc protein telethonin is constitutively bis-phosphorylated at C-terminal residues S157 and S161; however, the functional significance of this phosphorylation is not known. We sought to assess the significance of telethonin phosphorylation in vivo, using a novel knock-in (KI) mouse model generated to express non-phosphorylatable telethonin (Tcap S157/161A). Methods and Results: Tcap S157/161A and wild-type (WT) littermates were characterized by echocardiography at baseline and after sustained β-adrenergic stimulation via isoprenaline infusion. Heart tissues were collected for gravimetric, biochemical, and histological analyses. At baseline, Tcap S157/161A mice did not show any variances in cardiac structure or function compared with WT littermates and mutant telethonin remained localized to the Z-disc. Ablation of telethonin phosphorylation sites resulted in a gene-dosage dependent decrease in the cardiac telethonin protein expression level in mice carrying the S157/161A alleles, without any alteration in telethonin mRNA levels. The proteasome inhibitor MG132 significantly increased the expression level of S157/161A telethonin protein in myocytes from Tcap S157/161A mice, but not telethonin protein in myocytes from WT mice, indicating a role for the ubiquitin-proteasome system in the regulation of telethonin protein expression level. Tcap S157/161A mice challenged with sustained β-adrenergic stimulation via isoprenaline infusion developed cardiac hypertrophy accompanied by mild systolic dysfunction. Furthermore, the telethonin protein expression level was significantly increased in WT mice following isoprenaline stimulation but this response was blunted in Tcap S157/161A mice. Conclusion: Overall, these data reveal that telethonin protein turnover in vivo is regulated in a novel phosphorylation-dependent manner and suggest that C-terminal phosphorylation may protect telethonin against proteasomal degradation and preserve cardiac function during hemodynamic stress. Given that human telethonin C-terminal mutations have been associated with cardiac and skeletal myopathies, further research on their potential impact on phosphorylation-dependent regulation of telethonin protein expression could provide valuable mechanistic insight into those myopathies.
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Affiliation(s)
- Hannah R. Lewis
- School of Cardiovascular Medicine and Sciences, St Thomas’ Hospital, King’s College London British Heart Foundation Centre of Research Excellence, London, United Kingdom
| | - Seda Eminaga
- School of Cardiovascular Medicine and Sciences, St Thomas’ Hospital, King’s College London British Heart Foundation Centre of Research Excellence, London, United Kingdom
| | - Mathias Gautel
- School of Basic and Medical Biosciences, Guy’s Hospital, King’s College London British Heart Foundation Centre of Research Excellence, London, United Kingdom
| | - Metin Avkiran
- School of Cardiovascular Medicine and Sciences, St Thomas’ Hospital, King’s College London British Heart Foundation Centre of Research Excellence, London, United Kingdom
- *Correspondence: Metin Avkiran,
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13
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T-tubule remodeling in human hypertrophic cardiomyopathy. J Muscle Res Cell Motil 2020; 42:305-322. [PMID: 33222034 PMCID: PMC8332592 DOI: 10.1007/s10974-020-09591-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 10/22/2020] [Indexed: 11/17/2022]
Abstract
The highly organized transverse T-tubule membrane system represents the ultrastructural substrate for excitation–contraction coupling in ventricular myocytes. While the architecture and function of T-tubules have been well described in animal models, there is limited morpho-functional data on T-tubules in human myocardium. Hypertrophic cardiomyopathy (HCM) is a primary disease of the heart muscle, characterized by different clinical presentations at the various stages of its progression. Most HCM patients, indeed, show a compensated hypertrophic disease (“non-failing hypertrophic phase”), with preserved left ventricular function, and only a small subset of individuals evolves into heart failure (“end stage HCM”). In terms of T-tubule remodeling, the “end-stage” disease does not differ from other forms of heart failure. In this review we aim to recapitulate the main structural features of T-tubules during the “non-failing hypertrophic stage” of human HCM by revisiting data obtained from human myectomy samples. Moreover, by comparing pathological changes observed in myectomy samples with those introduced by acute (experimentally induced) detubulation, we discuss the role of T-tubular disruption as a part of the complex excitation–contraction coupling remodeling process that occurs during disease progression. Lastly, we highlight how T-tubule morpho-functional changes may be related to patient genotype and we discuss the possibility of a primitive remodeling of the T-tubule system in rare HCM forms associated with genes coding for proteins implicated in T-tubule structural integrity, formation and maintenance.
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14
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Turker I, Makiyama T, Ueyama T, Shimizu A, Yamakawa M, Chen P, Vatta M, Horie M, Ai T. Telethonin
variants found in Brugada syndrome, J‐wave pattern ECG, and ARVC reduce peak Na
v
1.5 currents in HEK‐293 cells. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2020; 43:838-846. [DOI: 10.1111/pace.13996] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 06/11/2020] [Accepted: 06/21/2020] [Indexed: 12/15/2022]
Affiliation(s)
- Isik Turker
- Department of Medicine Krannert Institute of Cardiology Indiana University School of Medicine Indianapolis Indiana
| | - Takeru Makiyama
- Cardiovascular Medicine Kyoto University Graduate School of Medicine Kyoto Japan
| | - Takeshi Ueyama
- Department of Cardiology Yamaguchi University School of Medical Science Yamaguchi Japan
| | - Akihiko Shimizu
- Department of Cardiology Yamaguchi University School of Medical Science Yamaguchi Japan
| | - Masaru Yamakawa
- Department of Pediatrics Kobe City Medical Center General Hospital Kobe Japan
| | - Peng‐Sheng Chen
- Department of Medicine Krannert Institute of Cardiology Indiana University School of Medicine Indianapolis Indiana
| | - Matteo Vatta
- Department of Medical and Molecular Genetics Indiana University School of Medicine Indianapolis Indiana
| | - Minoru Horie
- Department of Cardiovascular and Respiratory Medicine Shiga University of Medical Science Shiga Japan
| | - Tomohiko Ai
- Department of Medicine Krannert Institute of Cardiology Indiana University School of Medicine Indianapolis Indiana
- Department of Clinical Laboratory Medicine Juntendo University School of Medicine Tokyo Japan
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15
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Giacomelli E, Meraviglia V, Campostrini G, Cochrane A, Cao X, van Helden RWJ, Krotenberg Garcia A, Mircea M, Kostidis S, Davis RP, van Meer BJ, Jost CR, Koster AJ, Mei H, Míguez DG, Mulder AA, Ledesma-Terrón M, Pompilio G, Sala L, Salvatori DCF, Slieker RC, Sommariva E, de Vries AAF, Giera M, Semrau S, Tertoolen LGJ, Orlova VV, Bellin M, Mummery CL. Human-iPSC-Derived Cardiac Stromal Cells Enhance Maturation in 3D Cardiac Microtissues and Reveal Non-cardiomyocyte Contributions to Heart Disease. Cell Stem Cell 2020; 26:862-879.e11. [PMID: 32459996 PMCID: PMC7284308 DOI: 10.1016/j.stem.2020.05.004] [Citation(s) in RCA: 310] [Impact Index Per Article: 77.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 04/05/2020] [Accepted: 05/01/2020] [Indexed: 12/12/2022]
Abstract
Cardiomyocytes (CMs) from human induced pluripotent stem cells (hiPSCs) are functionally immature, but this is improved by incorporation into engineered tissues or forced contraction. Here, we showed that tri-cellular combinations of hiPSC-derived CMs, cardiac fibroblasts (CFs), and cardiac endothelial cells also enhance maturation in easily constructed, scaffold-free, three-dimensional microtissues (MTs). hiPSC-CMs in MTs with CFs showed improved sarcomeric structures with T-tubules, enhanced contractility, and mitochondrial respiration and were electrophysiologically more mature than MTs without CFs. Interactions mediating maturation included coupling between hiPSC-CMs and CFs through connexin 43 (CX43) gap junctions and increased intracellular cyclic AMP (cAMP). Scaled production of thousands of hiPSC-MTs was highly reproducible across lines and differentiated cell batches. MTs containing healthy-control hiPSC-CMs but hiPSC-CFs from patients with arrhythmogenic cardiomyopathy strikingly recapitulated features of the disease. Our MT model is thus a simple and versatile platform for modeling multicellular cardiac diseases that will facilitate industry and academic engagement in high-throughput molecular screening. Cardiac fibroblasts and endothelial cells induce hiPSC-cardiomyocyte maturation CX43 gap junctions form between cardiac fibroblasts and cardiomyocytes cAMP-pathway activation contributes to hiPSC-cardiomyocyte maturation Patient-derived hiPSC-cardiac fibroblasts cause arrhythmia in microtissues
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Affiliation(s)
- Elisa Giacomelli
- Department of Anatomy and Embryology, Leiden University Medical Center, 2333 Leiden, the Netherlands
| | - Viviana Meraviglia
- Department of Anatomy and Embryology, Leiden University Medical Center, 2333 Leiden, the Netherlands
| | - Giulia Campostrini
- Department of Anatomy and Embryology, Leiden University Medical Center, 2333 Leiden, the Netherlands
| | - Amy Cochrane
- Department of Anatomy and Embryology, Leiden University Medical Center, 2333 Leiden, the Netherlands
| | - Xu Cao
- Department of Anatomy and Embryology, Leiden University Medical Center, 2333 Leiden, the Netherlands
| | - Ruben W J van Helden
- Department of Anatomy and Embryology, Leiden University Medical Center, 2333 Leiden, the Netherlands
| | - Ana Krotenberg Garcia
- Department of Anatomy and Embryology, Leiden University Medical Center, 2333 Leiden, the Netherlands
| | - Maria Mircea
- Leiden Institute of Physics, Leiden University, 2333 Leiden, the Netherlands
| | - Sarantos Kostidis
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 Leiden, the Netherlands
| | - Richard P Davis
- Department of Anatomy and Embryology, Leiden University Medical Center, 2333 Leiden, the Netherlands
| | - Berend J van Meer
- Department of Anatomy and Embryology, Leiden University Medical Center, 2333 Leiden, the Netherlands
| | - Carolina R Jost
- Department of Cell and Chemical Biology, Leiden University Medical Center, 2333 Leiden, the Netherlands
| | - Abraham J Koster
- Department of Cell and Chemical Biology, Leiden University Medical Center, 2333 Leiden, the Netherlands
| | - Hailiang Mei
- Sequencing Analysis Support Core, Leiden University Medical Center, 2333 Leiden, the Netherlands
| | - David G Míguez
- Centro de Biologia Molecular Severo Ochoa, Departamento de Física de la Materia Condensada, Instituto Nicolas Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Aat A Mulder
- Department of Cell and Chemical Biology, Leiden University Medical Center, 2333 Leiden, the Netherlands
| | - Mario Ledesma-Terrón
- Centro de Biologia Molecular Severo Ochoa, Departamento de Física de la Materia Condensada, Instituto Nicolas Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Giulio Pompilio
- Vascular Biology and Regenerative Medicine Unit, Centro Cardiologico Monzino IRCCS, 20138 Milan, Italy; Department of Clinical Sciences and Community Health, Università degli Studi di Milano, 20122 Milan, Italy
| | - Luca Sala
- Department of Anatomy and Embryology, Leiden University Medical Center, 2333 Leiden, the Netherlands
| | - Daniela C F Salvatori
- Central Laboratory Animal Facility, Leiden University Medical Center, 2333 Leiden, the Netherlands
| | - Roderick C Slieker
- Department of Cell and Chemical Biology, Leiden University Medical Center, 2333 Leiden, the Netherlands; Department of Epidemiology and Biostatistics, Amsterdam Public Health Institute, VU University Medical Center, 1007 Amsterdam, the Netherlands
| | - Elena Sommariva
- Vascular Biology and Regenerative Medicine Unit, Centro Cardiologico Monzino IRCCS, 20138 Milan, Italy
| | - Antoine A F de Vries
- Department of Cardiology, Leiden University Medical Center, 2333 Leiden, the Netherlands
| | - Martin Giera
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 Leiden, the Netherlands
| | - Stefan Semrau
- Leiden Institute of Physics, Leiden University, 2333 Leiden, the Netherlands
| | - Leon G J Tertoolen
- Department of Anatomy and Embryology, Leiden University Medical Center, 2333 Leiden, the Netherlands
| | - Valeria V Orlova
- Department of Anatomy and Embryology, Leiden University Medical Center, 2333 Leiden, the Netherlands.
| | - Milena Bellin
- Department of Anatomy and Embryology, Leiden University Medical Center, 2333 Leiden, the Netherlands; Department of Biology, University of Padua, 35121 Padua, Italy; Veneto Institute of Molecular Medicine, 35129 Padua, Italy.
| | - Christine L Mummery
- Department of Anatomy and Embryology, Leiden University Medical Center, 2333 Leiden, the Netherlands; Department of Applied Stem Cell Technologies, University of Twente, 7500 Enschede, the Netherlands.
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16
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Gilbert G, Demydenko K, Dries E, Puertas RD, Jin X, Sipido K, Roderick HL. Calcium Signaling in Cardiomyocyte Function. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a035428. [PMID: 31308143 DOI: 10.1101/cshperspect.a035428] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Rhythmic increases in intracellular Ca2+ concentration underlie the contractile function of the heart. These heart muscle-wide changes in intracellular Ca2+ are induced and coordinated by electrical depolarization of the cardiomyocyte sarcolemma by the action potential. Originating at the sinoatrial node, conduction of this electrical signal throughout the heart ensures synchronization of individual myocytes into an effective cardiac pump. Ca2+ signaling pathways also regulate gene expression and cardiomyocyte growth during development and in pathology. These fundamental roles of Ca2+ in the heart are illustrated by the prevalence of altered Ca2+ homeostasis in cardiovascular diseases. Indeed, heart failure (an inability of the heart to support hemodynamic needs), rhythmic disturbances, and inappropriate cardiac growth all share an involvement of altered Ca2+ handling. The prevalence of these pathologies, contributing to a third of all deaths in the developed world as well as to substantial morbidity makes understanding the mechanisms of Ca2+ handling and dysregulation in cardiomyocytes of great importance.
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Affiliation(s)
- Guillaume Gilbert
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - Kateryna Demydenko
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - Eef Dries
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - Rosa Doñate Puertas
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - Xin Jin
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - Karin Sipido
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - H Llewelyn Roderick
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
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17
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Lipsett DB, Frisk M, Aronsen JM, Nordén ES, Buonarati OR, Cataliotti A, Hell JW, Sjaastad I, Christensen G, Louch WE. Cardiomyocyte substructure reverts to an immature phenotype during heart failure. J Physiol 2019; 597:1833-1853. [PMID: 30707448 PMCID: PMC6441900 DOI: 10.1113/jp277273] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 01/28/2019] [Indexed: 12/16/2022] Open
Abstract
Key points As reactivation of the fetal gene program has been implicated in pathological remodelling during heart failure (HF), we examined whether cardiomyocyte subcellular structure and function revert to an immature phenotype during this disease. Surface and internal membrane structures appeared gradually during development, and returned to a juvenile state during HF. Similarly, dyadic junctions between the cell membrane and sarcoplasmic reticulum were progressively ‘packed’ with L‐type Ca2+ channels and ryanodine receptors during development, and ‘unpacked’ during HF. Despite similarities in subcellular structure, dyads were observed to be functional from early developmental stages, but exhibited an impaired ability to release Ca2+ in failing cardiomyocytes. Thus, while immature and failing cardiomyocytes share similarities in subcellular structure, these do not fully account for the marked impairment of Ca2+ homeostasis observed in HF.
Abstract Reactivation of the fetal gene programme has been implicated as a driver of pathological cardiac remodelling. Here we examined whether pathological remodelling of cardiomyocyte substructure and function during heart failure (HF) reflects a reversion to an immature phenotype. Using scanning electron microscopy, we observed that Z‐grooves and t‐tubule openings at the cell surface appeared gradually during cardiac development, and disappeared during HF. Confocal and super‐resolution imaging within the cell interior revealed similar structural parallels; disorganization of t‐tubules in failing cells was strikingly reminiscent of the late stages of postnatal development, with fewer transverse elements and a high proportion of longitudinal tubules. Ryanodine receptors (RyRs) were observed to be laid down in advance of developing t‐tubules and similarly ‘orphaned’ in HF, although RyR distribution along Z‐lines was relatively sparse. Indeed, nanoscale imaging revealed coordinated packing of L‐type Ca2+ channels and RyRs into dyadic junctions during development, and orderly unpacking during HF. These findings support a ‘last in, first out’ paradigm, as the latest stages of dyadic structural development are reversed during disease. Paired imaging of t‐tubules and Ca2+ showed that the disorganized arrangement of dyads in immature and failing cells promoted desynchronized and slowed Ca2+ release in these two states. However, while developing cells exhibited efficient triggering of Ca2+ release at newly formed dyads, dyadic function was impaired in failing cells despite similar organization of Ca2+ handling proteins. Thus, pathologically deficient Ca2+ homeostasis during HF is only partly linked to the re‐emergence of immature subcellular structure, and additionally reflects lost dyadic functionality. As reactivation of the fetal gene program has been implicated in pathological remodelling during heart failure (HF), we examined whether cardiomyocyte subcellular structure and function revert to an immature phenotype during this disease. Surface and internal membrane structures appeared gradually during development, and returned to a juvenile state during HF. Similarly, dyadic junctions between the cell membrane and sarcoplasmic reticulum were progressively ‘packed’ with L‐type Ca2+ channels and ryanodine receptors during development, and ‘unpacked’ during HF. Despite similarities in subcellular structure, dyads were observed to be functional from early developmental stages, but exhibited an impaired ability to release Ca2+ in failing cardiomyocytes. Thus, while immature and failing cardiomyocytes share similarities in subcellular structure, these do not fully account for the marked impairment of Ca2+ homeostasis observed in HF.
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Affiliation(s)
- D B Lipsett
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
| | - M Frisk
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - J M Aronsen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,Bjørknes College, Oslo, Norway
| | - E S Nordén
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - O R Buonarati
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - A Cataliotti
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - J W Hell
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - I Sjaastad
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - G Christensen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - W E Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
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18
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Jones PP, MacQuaide N, Louch WE. Dyadic Plasticity in Cardiomyocytes. Front Physiol 2018; 9:1773. [PMID: 30618792 PMCID: PMC6298195 DOI: 10.3389/fphys.2018.01773] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 11/23/2018] [Indexed: 11/13/2022] Open
Abstract
Contraction of cardiomyocytes is dependent on sub-cellular structures called dyads, where invaginations of the surface membrane (t-tubules) form functional junctions with the sarcoplasmic reticulum (SR). Within each dyad, Ca2+ entry through t-tubular L-type Ca2+ channels (LTCCs) elicits Ca2+ release from closely apposed Ryanodine Receptors (RyRs) in the SR membrane. The efficiency of this process is dependent on the density and macroscale arrangement of dyads, but also on the nanoscale organization of LTCCs and RyRs within them. We presently review accumulating data demonstrating the remarkable plasticity of these structures. Dyads are known to form gradually during development, with progressive assembly of both t-tubules and junctional SR terminals, and precise trafficking of LTCCs and RyRs. While dyads can exhibit compensatory remodeling when required, dyadic degradation is believed to promote impaired contractility and arrythmogenesis in cardiac disease. Recent data indicate that this plasticity of dyadic structure/function is dependent on the regulatory proteins junctophilin-2, amphiphysin-2 (BIN1), and caveolin-3, which critically arrange dyadic membranes while stabilizing the position and activity of LTCCs and RyRs. Indeed, emerging evidence indicates that clustering of both channels enables "coupled gating", implying that nanoscale localization and function are intimately linked, and may allow fine-tuning of LTCC-RyR crosstalk. We anticipate that improved understanding of dyadic plasticity will provide greater insight into the processes of cardiac compensation and decompensation, and new opportunities to target the basic mechanisms underlying heart disease.
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Affiliation(s)
- Peter P. Jones
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
- HeartOtago, University of Otago, Dunedin, New Zealand
| | - Niall MacQuaide
- Institute of Cardiovascular Sciences, University of Glasgow, Glasgow, United Kingdom
- Clyde Biosciences, Glasgow, United Kingdom
| | - William E. Louch
- Institute for Experimental Medical Research, Oslo University Hospital, University of Oslo, Oslo, Norway
- KG Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
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19
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Crossman DJ, Shen X, Jüllig M, Munro M, Hou Y, Middleditch M, Shrestha D, Li A, Lal S, Dos Remedios CG, Baddeley D, Ruygrok PN, Soeller C. Increased collagen within the transverse tubules in human heart failure. Cardiovasc Res 2018; 113:879-891. [PMID: 28444133 DOI: 10.1093/cvr/cvx055] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 03/20/2017] [Indexed: 12/22/2022] Open
Abstract
Aims In heart failure transverse-tubule (t-tubule) remodelling disrupts calcium release, and contraction. T-tubules in human failing hearts exhibit increased labelling by wheat germ agglutinin (WGA), a lectin that binds to the dystrophin-associated glycoprotein complex. We hypothesized changes in this complex may explain the increased WGA labelling and contribute to t-tubule remodelling in the failing human heart. In this study we sought to identify the molecules responsible for this increased WGA labelling. Methods and results Confocal and super-resolution fluorescence microscopy and proteomic analyses were used to quantify left ventricle samples from healthy donors and patients with idiopathic dilated cardiomyopathy (IDCM). Confocal microscopy demonstrated both WGA and dystrophin were located at t-tubules. Super-resolution microscopy revealed that WGA labelling of t-tubules is largely located within the lumen while dystrophin was restricted to near the sarcolemma. Western blots probed with WGA reveal a 5.7-fold increase in a 140 kDa band in IDCM. Mass spectrometry identified this band as type VI collagen (Col-VI) comprised of α1(VI), α2(VI), and α3(VI) chains. Pertinently, mutations in Col-VI cause muscular dystrophy. Western blotting identified a 2.4-fold increased expression and 3.2-fold increased WGA binding of Col-VI in IDCM. Confocal images showed that Col-VI is located in the t-tubules and that their diameter increased in the IDCM samples. Super-resolution imaging revealed Col-VI was restricted to the t-tubule lumen where increases were associated with displacement in the sarcolemma as identified from dystrophin labelling. Samples were also labelled for type I, III, and IV collagen. Both confocal and super-resolution imaging identified that these collagens were also present within t-tubule lumen. Conclusion Increased expression and labelling of collagen in IDCM samples indicates fibrosis may contribute to t-tubule remodelling in human heart failure.
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Affiliation(s)
- David J Crossman
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland 1023, New Zealand
| | - Xin Shen
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland 1023, New Zealand
| | - Mia Jüllig
- School of Biological Sciences, University of Auckland, 3a Symonds Street, Auckland 1010, New Zealand
| | - Michelle Munro
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland 1023, New Zealand
| | - Yufeng Hou
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland 1023, New Zealand
| | - Martin Middleditch
- School of Biological Sciences, University of Auckland, 3a Symonds Street, Auckland 1010, New Zealand
| | - Darshan Shrestha
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland 1023, New Zealand
| | - Amy Li
- Bosch Institute, University of Sydney, Fisher Road Sydney, NSW 2006, Australia
| | - Sean Lal
- Bosch Institute, University of Sydney, Fisher Road Sydney, NSW 2006, Australia
| | | | - David Baddeley
- Department of Cell Biology, Yale University, West Campus, 300 Heffernan Drive, Haven, CT 06515, USA
| | - Peter N Ruygrok
- Department of Cardiology, Auckland City Hospital, Auckland 1042, New Zealand
| | - Christian Soeller
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland 1023, New Zealand.,Living Systems Institute and Biomedical Physics, University of Exeter, Stocker Road, Exeter EX4QL, UK
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Smith CER, Trafford AW, Caldwell JL, Dibb KM. Physiology and patho-physiology of the cardiac transverse tubular system. CURRENT OPINION IN PHYSIOLOGY 2018. [DOI: 10.1016/j.cophys.2017.11.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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21
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Crossman DJ, Jayasinghe ID, Soeller C. Transverse tubule remodelling: a cellular pathology driven by both sides of the plasmalemma? Biophys Rev 2017; 9:919-929. [PMID: 28695473 DOI: 10.1007/s12551-017-0273-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 06/06/2017] [Indexed: 01/10/2023] Open
Abstract
Transverse (t)-tubules are invaginations of the plasma membrane that form a complex network of ducts, 200-400 nm in diameter depending on the animal species, that penetrates deep within the cardiac myocyte, where they facilitate a fast and synchronous contraction across the entire cell volume. There is now a large body of evidence in animal models and humans demonstrating that pathological distortion of the t-tubule structure has a causative role in the loss of myocyte contractility that underpins many forms of heart failure. Investigations into the molecular mechanisms of pathological t-tubule remodelling to date have focused on proteins residing in the intracellular aspect of t-tubule membrane that form linkages between the membrane and myocyte cytoskeleton. In this review, we shed light on the mechanisms of t-tubule remodelling which are not limited to the intracellular side. Our recent data have demonstrated that collagen is an integral part of the t-tubule network and that it increases within the tubules in heart failure, suggesting that a fibrotic mechanism could drive cardiac junctional remodelling. We examine the evidence that the linkages between the extracellular matrix, t-tubule membrane and cellular cytoskeleton should be considered as a whole when investigating the mechanisms of t-tubule pathology in the failing heart.
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Affiliation(s)
- David J Crossman
- Department of Physiology, University of Auckland, Auckland, New Zealand.
| | | | - Christian Soeller
- Department of Physiology, University of Auckland, Auckland, New Zealand
- Biomedical Physics, University of Exeter, Exeter, UK
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22
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Zuppinger C, Gibbons G, Dutta-Passecker P, Segiser A, Most H, Suter TM. Characterization of cytoskeleton features and maturation status of cultured human iPSC-derived cardiomyocytes. Eur J Histochem 2017; 61:2763. [PMID: 28735524 PMCID: PMC5484009 DOI: 10.4081/ejh.2017.2763] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 06/07/2017] [Accepted: 06/07/2017] [Indexed: 01/01/2023] Open
Abstract
Recent innovations in stem cell technologies and the availability of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have opened new possibilities for studies and drug testing on human cardiomyocytes in vitro. Still, there are concerns about the precise nature of such 'reprogrammed' cells. We have performed an investigation using immunocytochemistry and confocal microscopy on several cellular features using commercially available hiPSC-CMs. For some selected developmentally regulated or cardiac chamber-specific proteins, we have compared the results from hiPSC-derived cardiomyocytes with freshly isolated, ventricular cardiomyocytes from adult rats. The results show that all typical cardiac proteins are expressed in these hiPSC-CMs. Furthermore, intercalated disc-like structures, calcium cycling proteins, and myofibrils are present. However, some of these proteins are only known from early developmental stages of the ventricular myocardium or the diseased adult heart. A heterogeneous expression pattern in the cell population was noted for some muscle proteins, such as for myosin light chains, or incomplete organization in sarcomeres, such as for telethonin. These observations indicate that hiPSC-CMs can be considered genuine human cardiomyocytes of an early developmental state. The here described marker proteins of maturation may become instrumental in future studies attempting the improvement of cardiomyocyte in vitro models.
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23
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Yue X, Zhang R, Kim B, Ma A, Philipson KD, Goldhaber JI. Heterogeneity of transverse-axial tubule system in mouse atria: Remodeling in atrial-specific Na +-Ca 2+ exchanger knockout mice. J Mol Cell Cardiol 2017; 108:50-60. [PMID: 28529049 DOI: 10.1016/j.yjmcc.2017.05.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 05/10/2017] [Accepted: 05/18/2017] [Indexed: 01/20/2023]
Abstract
Transverse-axial tubules (TATs) are commonly assumed to be sparse or absent in atrial myocytes from small animals. Atrial myocytes from rats, cats and rabbits lack TATs, which results in a characteristic "V"-shaped Ca release pattern in confocal line-scan recordings due to the delayed rise of Ca in the center of the cell. To examine TAT expression in isolated mouse atrial myocytes, we loaded them with the membrane dye Di-4-ANEPPS to label TATs. We found that >80% of atrial myocytes had identifiable TATs. Atria from male mice had a higher TAT density than female mice, and TAT density correlated with cell width. Using the fluorescent Ca indicator Fluo-4-AM and confocal imaging, we found that wild type (WT) mouse atrial myocytes generate near-synchronous Ca transients, in contrast to the "V"-shaped pattern typically reported in other small animals such as rat. In atrial-specific Na-Ca exchanger (NCX) knockout (KO) mice, which develop sinus node dysfunction and atrial hypertrophy with dilation, we found a substantial loss of atrial TATs in isolated atrial myocytes. There was a greater loss of transverse tubules compared to axial tubules, resulting in a dominance of axial tubules. Consistent with the overall loss of TATs, NCX KO atrial myocytes displayed a "V"-shaped Ca transient with slower and reduced central (CT) Ca release and uptake in comparison to subsarcolemmal (SS) Ca release. We compared chemically detubulated (DT) WT cells to KO, and found similar slowing of CT Ca release and uptake. However, SS Ca transients in the WT DT cells had faster uptake kinetics than KO cells, consistent with the presence of NCX and normal sarcolemmal Ca efflux in the WT DT cells. We conclude that the remodeling of NCX KO atrial myocytes is accompanied by a loss of TATs leading to abnormal Ca release and uptake that could impact atrial contractility and rhythm.
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Affiliation(s)
- Xin Yue
- Department of Cardiovascular Medicine, First Affiliated Hospital of Xi'an Jiaotong University, No. 277 West Yanta Road, Xi'an, Shaanxi 710061, China; Cedars-Sinai Heart Institute, Division of Applied Cell Biology and Physiology, 8700 Beverly Blvd., Los Angeles, CA 90048, USA
| | - Rui Zhang
- Cedars-Sinai Heart Institute, Division of Applied Cell Biology and Physiology, 8700 Beverly Blvd., Los Angeles, CA 90048, USA
| | - Brian Kim
- Cedars-Sinai Heart Institute, Division of Applied Cell Biology and Physiology, 8700 Beverly Blvd., Los Angeles, CA 90048, USA
| | - Aiqun Ma
- Department of Cardiovascular Medicine, First Affiliated Hospital of Xi'an Jiaotong University, No. 277 West Yanta Road, Xi'an, Shaanxi 710061, China; Key Laboratory of Environment and Genes Related to Diseases of Ministry of Education and Key Laboratory of Molecular Cardiology of Shaanxi Province, 277 Yanta West Road, Xi'an, Shaanxi 710061, China.
| | - Kenneth D Philipson
- Department of Physiology, David Geffen School of Medicine at UCLA, 650 Charles Young Drive South, Los Angeles, CA 90095, USA
| | - Joshua I Goldhaber
- Cedars-Sinai Heart Institute, Division of Applied Cell Biology and Physiology, 8700 Beverly Blvd., Los Angeles, CA 90048, USA.
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24
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Pinali C, Malik N, Davenport JB, Allan LJ, Murfitt L, Iqbal MM, Boyett MR, Wright EJ, Walker R, Zhang Y, Dobryznski H, Holt CM, Kitmitto A. Post-Myocardial Infarction T-tubules Form Enlarged Branched Structures With Dysregulation of Junctophilin-2 and Bridging Integrator 1 (BIN-1). J Am Heart Assoc 2017; 6:e004834. [PMID: 28473402 PMCID: PMC5524063 DOI: 10.1161/jaha.116.004834] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 01/26/2017] [Indexed: 11/16/2022]
Abstract
BACKGROUND Heart failure is a common secondary complication following a myocardial infarction (MI), characterized by impaired cardiac contraction and t-tubule (t-t) loss. However, post-MI nano-scale morphological changes to the remaining t-ts are poorly understood. METHOD AND RESULTS We utilized a porcine model of MI, using a nonlethal microembolization method to generate controlled microinfarcts. Using serial block face scanning electron microscopy, we report that post-MI, after mild left-ventricular dysfunction has developed, t-ts are not only lost in the peri-infarct region, but also the remnant t-ts form enlarged, highly branched disordered structures, containing a dense intricate inner membrane. Biochemical and proteomics analyses showed that the calcium release channel, ryanodine receptor 2 (RyR2), abundance is unchanged, but junctophilin-2 (JP2), important for maintaining t-t trajectory, is depressed (-0.5×) in keeping with the t-ts being disorganized. However, immunolabeling shows that populations of RyR2 and JP2 remain associated with the remodeled t-ts. The bridging integrator 1 protein (BIN-1), a regulator of tubulogensis, is upregulated (+5.4×), consistent with an overdeveloped internal membrane system, a feature not present in control t-ts. Importantly, we have determined that t-ts, in the remote region, are narrowed and also contain dense membrane folds (BIN-1 is up-regulated +3.4×), whereas the t-ts have a radial organization comparable to control JP2 is upregulated +1.7×. CONCLUSIONS This study reveals previously unidentified remodeling of the t-t nano-architecture in the post-MI heart that extends to the remote region. Our findings highlight that targeting JP2 may be beneficial for preserving the orientation of the t-ts, attenuating the development of hypocontractility post-MI.
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Affiliation(s)
- Christian Pinali
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Nadim Malik
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - J Bernard Davenport
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Laurence J Allan
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Lucy Murfitt
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Mohammad M Iqbal
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Mark R Boyett
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Elizabeth J Wright
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Rachel Walker
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Yu Zhang
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Halina Dobryznski
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Cathy M Holt
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Ashraf Kitmitto
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
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25
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Seidel T, Navankasattusas S, Ahmad A, Diakos NA, Xu WD, Tristani-Firouzi M, Bonios MJ, Taleb I, Li DY, Selzman CH, Drakos SG, Sachse FB. Sheet-Like Remodeling of the Transverse Tubular System in Human Heart Failure Impairs Excitation-Contraction Coupling and Functional Recovery by Mechanical Unloading. Circulation 2017; 135:1632-1645. [PMID: 28073805 PMCID: PMC5404964 DOI: 10.1161/circulationaha.116.024470] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 12/14/2016] [Indexed: 01/02/2023]
Abstract
BACKGROUND Cardiac recovery in response to mechanical unloading by left ventricular assist devices (LVADs) has been demonstrated in subgroups of patients with chronic heart failure (HF). Hallmarks of HF are depletion and disorganization of the transverse tubular system (t-system) in cardiomyocytes. Here, we investigated remodeling of the t-system in human end-stage HF and its role in cardiac recovery. METHODS Left ventricular biopsies were obtained from 5 donors and 26 patients with chronic HF undergoing implantation of LVADs. Three-dimensional confocal microscopy and computational image analysis were applied to assess t-system structure, density, and distance of ryanodine receptor clusters to the sarcolemma, including the t-system. Recovery of cardiac function in response to mechanical unloading was assessed by echocardiography during turndown of the LVAD. RESULTS The majority of HF myocytes showed remarkable t-system remodeling, particularly sheet-like invaginations of the sarcolemma. Circularity of t-system components was decreased in HF versus controls (0.37±0.01 versus 0.46±0.02; P<0.01), and the volume/length ratio was increased in HF (0.36±0.01 versus 0.25±0.02 µm2; P<0.0001). T-system density was reduced in HF, leading to increased ryanodine receptor-sarcolemma distances (0.96±0.05 versus 0.64±0.1 µm; P<0.01). Low ryanodine receptor-sarcolemma distances at the time of LVAD implantation predicted high post-LVAD left ventricular ejection fractions (P<0.01) and ejection fraction increases during unloading (P<0.01). Ejection fraction in patients with pre-LVAD ryanodine receptor-sarcolemma distances >1 µm did not improve after mechanical unloading. In addition, calcium transients were recorded in field-stimulated isolated human cardiomyocytes and analyzed with respect to local t-system density. Calcium release in HF myocytes was restricted to regions proximal to the sarcolemma. Local calcium upstroke was delayed (23.9±4.9 versus 10.3±1.7 milliseconds; P<0.05) and more asynchronous (18.1±1.5 versus 8.9±2.2 milliseconds; P<0.01) in HF cells with low t-system density versus cells with high t-system density. CONCLUSIONS The t-system in end-stage human HF presents a characteristic novel phenotype consisting of sheet-like invaginations of the sarcolemma. Our results suggest that the remodeled t-system impairs excitation-contraction coupling and functional recovery during chronic LVAD unloading. An intact t-system at the time of LVAD implantation may constitute a precondition and predictor for functional cardiac recovery after mechanical unloading.
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Affiliation(s)
- Thomas Seidel
- From Nora Eccles Harrison Cardiovascular Research and Training Institute (T.S., A.A., M.T.-F., S.G.D., F.B.S.), Molecular Medicine Program (S.N., N.A.D., D.Y.L., C.H.S.), Department of Bioengineering (A.A., F.B.S.), Division of Cardiovascular Medicine (W.D.X., M.J.B., I.T., D.Y.L., S.G.D.), and Division of Cardiothoracic Surgery (C.H.S.), University of Utah, Salt Lake City. Dr Seidel is currently at the Institute for Cellular and Molecular Physiology, Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Germany.
| | - Sutip Navankasattusas
- From Nora Eccles Harrison Cardiovascular Research and Training Institute (T.S., A.A., M.T.-F., S.G.D., F.B.S.), Molecular Medicine Program (S.N., N.A.D., D.Y.L., C.H.S.), Department of Bioengineering (A.A., F.B.S.), Division of Cardiovascular Medicine (W.D.X., M.J.B., I.T., D.Y.L., S.G.D.), and Division of Cardiothoracic Surgery (C.H.S.), University of Utah, Salt Lake City. Dr Seidel is currently at the Institute for Cellular and Molecular Physiology, Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Germany
| | - Azmi Ahmad
- From Nora Eccles Harrison Cardiovascular Research and Training Institute (T.S., A.A., M.T.-F., S.G.D., F.B.S.), Molecular Medicine Program (S.N., N.A.D., D.Y.L., C.H.S.), Department of Bioengineering (A.A., F.B.S.), Division of Cardiovascular Medicine (W.D.X., M.J.B., I.T., D.Y.L., S.G.D.), and Division of Cardiothoracic Surgery (C.H.S.), University of Utah, Salt Lake City. Dr Seidel is currently at the Institute for Cellular and Molecular Physiology, Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Germany
| | - Nikolaos A Diakos
- From Nora Eccles Harrison Cardiovascular Research and Training Institute (T.S., A.A., M.T.-F., S.G.D., F.B.S.), Molecular Medicine Program (S.N., N.A.D., D.Y.L., C.H.S.), Department of Bioengineering (A.A., F.B.S.), Division of Cardiovascular Medicine (W.D.X., M.J.B., I.T., D.Y.L., S.G.D.), and Division of Cardiothoracic Surgery (C.H.S.), University of Utah, Salt Lake City. Dr Seidel is currently at the Institute for Cellular and Molecular Physiology, Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Germany
| | - Weining David Xu
- From Nora Eccles Harrison Cardiovascular Research and Training Institute (T.S., A.A., M.T.-F., S.G.D., F.B.S.), Molecular Medicine Program (S.N., N.A.D., D.Y.L., C.H.S.), Department of Bioengineering (A.A., F.B.S.), Division of Cardiovascular Medicine (W.D.X., M.J.B., I.T., D.Y.L., S.G.D.), and Division of Cardiothoracic Surgery (C.H.S.), University of Utah, Salt Lake City. Dr Seidel is currently at the Institute for Cellular and Molecular Physiology, Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Germany
| | - Martin Tristani-Firouzi
- From Nora Eccles Harrison Cardiovascular Research and Training Institute (T.S., A.A., M.T.-F., S.G.D., F.B.S.), Molecular Medicine Program (S.N., N.A.D., D.Y.L., C.H.S.), Department of Bioengineering (A.A., F.B.S.), Division of Cardiovascular Medicine (W.D.X., M.J.B., I.T., D.Y.L., S.G.D.), and Division of Cardiothoracic Surgery (C.H.S.), University of Utah, Salt Lake City. Dr Seidel is currently at the Institute for Cellular and Molecular Physiology, Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Germany
| | - Michael J Bonios
- From Nora Eccles Harrison Cardiovascular Research and Training Institute (T.S., A.A., M.T.-F., S.G.D., F.B.S.), Molecular Medicine Program (S.N., N.A.D., D.Y.L., C.H.S.), Department of Bioengineering (A.A., F.B.S.), Division of Cardiovascular Medicine (W.D.X., M.J.B., I.T., D.Y.L., S.G.D.), and Division of Cardiothoracic Surgery (C.H.S.), University of Utah, Salt Lake City. Dr Seidel is currently at the Institute for Cellular and Molecular Physiology, Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Germany
| | - Iosif Taleb
- From Nora Eccles Harrison Cardiovascular Research and Training Institute (T.S., A.A., M.T.-F., S.G.D., F.B.S.), Molecular Medicine Program (S.N., N.A.D., D.Y.L., C.H.S.), Department of Bioengineering (A.A., F.B.S.), Division of Cardiovascular Medicine (W.D.X., M.J.B., I.T., D.Y.L., S.G.D.), and Division of Cardiothoracic Surgery (C.H.S.), University of Utah, Salt Lake City. Dr Seidel is currently at the Institute for Cellular and Molecular Physiology, Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Germany
| | - Dean Y Li
- From Nora Eccles Harrison Cardiovascular Research and Training Institute (T.S., A.A., M.T.-F., S.G.D., F.B.S.), Molecular Medicine Program (S.N., N.A.D., D.Y.L., C.H.S.), Department of Bioengineering (A.A., F.B.S.), Division of Cardiovascular Medicine (W.D.X., M.J.B., I.T., D.Y.L., S.G.D.), and Division of Cardiothoracic Surgery (C.H.S.), University of Utah, Salt Lake City. Dr Seidel is currently at the Institute for Cellular and Molecular Physiology, Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Germany
| | - Craig H Selzman
- From Nora Eccles Harrison Cardiovascular Research and Training Institute (T.S., A.A., M.T.-F., S.G.D., F.B.S.), Molecular Medicine Program (S.N., N.A.D., D.Y.L., C.H.S.), Department of Bioengineering (A.A., F.B.S.), Division of Cardiovascular Medicine (W.D.X., M.J.B., I.T., D.Y.L., S.G.D.), and Division of Cardiothoracic Surgery (C.H.S.), University of Utah, Salt Lake City. Dr Seidel is currently at the Institute for Cellular and Molecular Physiology, Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Germany
| | - Stavros G Drakos
- From Nora Eccles Harrison Cardiovascular Research and Training Institute (T.S., A.A., M.T.-F., S.G.D., F.B.S.), Molecular Medicine Program (S.N., N.A.D., D.Y.L., C.H.S.), Department of Bioengineering (A.A., F.B.S.), Division of Cardiovascular Medicine (W.D.X., M.J.B., I.T., D.Y.L., S.G.D.), and Division of Cardiothoracic Surgery (C.H.S.), University of Utah, Salt Lake City. Dr Seidel is currently at the Institute for Cellular and Molecular Physiology, Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Germany.
| | - Frank B Sachse
- From Nora Eccles Harrison Cardiovascular Research and Training Institute (T.S., A.A., M.T.-F., S.G.D., F.B.S.), Molecular Medicine Program (S.N., N.A.D., D.Y.L., C.H.S.), Department of Bioengineering (A.A., F.B.S.), Division of Cardiovascular Medicine (W.D.X., M.J.B., I.T., D.Y.L., S.G.D.), and Division of Cardiothoracic Surgery (C.H.S.), University of Utah, Salt Lake City. Dr Seidel is currently at the Institute for Cellular and Molecular Physiology, Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Germany.
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α-Actinin/titin interaction: A dynamic and mechanically stable cluster of bonds in the muscle Z-disk. Proc Natl Acad Sci U S A 2017; 114:1015-1020. [PMID: 28096424 DOI: 10.1073/pnas.1612681114] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Stable anchoring of titin within the muscle Z-disk is essential for preserving muscle integrity during passive stretching. One of the main candidates for anchoring titin in the Z-disk is the actin cross-linker α-actinin. The calmodulin-like domain of α-actinin binds to the Z-repeats of titin. However, the mechanical and kinetic properties of this important interaction are still unknown. Here, we use a dual-beam optical tweezers assay to study the mechanics of this interaction at the single-molecule level. A single interaction of α-actinin and titin turns out to be surprisingly weak if force is applied. Depending on the direction of force application, the unbinding forces can more than triple. Our results suggest a model where multiple α-actinin/Z-repeat interactions cooperate to ensure long-term stable titin anchoring while allowing the individual components to exchange dynamically.
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Effects of induced Na+/Ca2+ exchanger overexpression on the spatial distribution of L-type Ca2+ channels and junctophilin-2 in pressure-overloaded hearts. Biochem Biophys Res Commun 2016; 480:564-569. [DOI: 10.1016/j.bbrc.2016.10.090] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 10/24/2016] [Indexed: 02/08/2023]
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Gautel M, Djinović-Carugo K. The sarcomeric cytoskeleton: from molecules to motion. ACTA ACUST UNITED AC 2016; 219:135-45. [PMID: 26792323 DOI: 10.1242/jeb.124941] [Citation(s) in RCA: 143] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Highly ordered organisation of striated muscle is the prerequisite for the fast and unidirectional development of force and motion during heart and skeletal muscle contraction. A group of proteins, summarised as the sarcomeric cytoskeleton, is essential for the ordered assembly of actin and myosin filaments into sarcomeres, by combining architectural, mechanical and signalling functions. This review discusses recent cell biological, biophysical and structural insight into the regulated assembly of sarcomeric cytoskeleton proteins and their roles in dissipating mechanical forces in order to maintain sarcomere integrity during passive extension and active contraction. α-Actinin crosslinks in the Z-disk show a pivot-and-rod structure that anchors both titin and actin filaments. In contrast, the myosin crosslinks formed by myomesin in the M-band are of a ball-and-spring type and may be crucial in providing stable yet elastic connections during active contractions, especially eccentric exercise.
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Affiliation(s)
- Mathias Gautel
- King's College London BHF Centre of Research Excellence, Randall Division for Cell and Molecular Biophysics, and Cardiovascular Division, New Hunt's House, London SE1 1UL, UK
| | - Kristina Djinović-Carugo
- Department of Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Campus Vienna Biocenter 5, Vienna A-1030, Austria Department of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, Ljubljana 1000, Slovenia
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Frisk M, Ruud M, Espe EKS, Aronsen JM, Røe ÅT, Zhang L, Norseng PA, Sejersted OM, Christensen GA, Sjaastad I, Louch WE. Elevated ventricular wall stress disrupts cardiomyocyte t-tubule structure and calcium homeostasis. Cardiovasc Res 2016; 112:443-51. [PMID: 27226008 PMCID: PMC5031949 DOI: 10.1093/cvr/cvw111] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 05/16/2016] [Indexed: 11/13/2022] Open
Abstract
AIMS Invaginations of the cellular membrane called t-tubules are essential for maintaining efficient excitation-contraction coupling in ventricular cardiomyocytes. Disruption of t-tubule structure during heart failure has been linked to dyssynchronous, slowed Ca(2+) release and reduced power of the heartbeat. The underlying mechanism is, however, unknown. We presently investigated whether elevated ventricular wall stress triggers remodelling of t-tubule structure and function. METHODS AND RESULTS MRI and blood pressure measurements were employed to examine regional wall stress across the left ventricle of sham-operated and failing, post-infarction rat hearts. In failing hearts, elevated left ventricular diastolic pressure and ventricular dilation resulted in markedly increased wall stress, particularly in the thin-walled region proximal to the infarct. High wall stress in this proximal zone was associated with reduced expression of the dyadic anchor junctophilin-2 and disrupted cardiomyocyte t-tubular structure. Indeed, local wall stress measurements predicted t-tubule density across sham and failing hearts. Elevated wall stress and disrupted cardiomyocyte structure in the proximal zone were also associated with desynchronized Ca(2+) release in cardiomyocytes and markedly reduced local contractility in vivo. A causative role of wall stress in promoting t-tubule remodelling was established by applying stretch to papillary muscles ex vivo under culture conditions. Loads comparable to wall stress levels observed in vivo in the proximal zone reduced expression of junctophilin-2 and promoted t-tubule loss. CONCLUSION Elevated wall stress reduces junctophilin-2 expression and disrupts t-tubule integrity, Ca(2+) release, and contractile function. These findings provide new insight into the role of wall stress in promoting heart failure progression.
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Affiliation(s)
- Michael Frisk
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Ullevål, Kirkeveien 166, 0424 Oslo, Norway K.G. Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, 0316 Oslo, Norway
| | - Marianne Ruud
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Ullevål, Kirkeveien 166, 0424 Oslo, Norway K.G. Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, 0316 Oslo, Norway
| | - Emil K S Espe
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Ullevål, Kirkeveien 166, 0424 Oslo, Norway K.G. Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, 0316 Oslo, Norway
| | | | - Åsmund T Røe
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Ullevål, Kirkeveien 166, 0424 Oslo, Norway K.G. Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, 0316 Oslo, Norway
| | - Lili Zhang
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Ullevål, Kirkeveien 166, 0424 Oslo, Norway K.G. Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, 0316 Oslo, Norway
| | - Per Andreas Norseng
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Ullevål, Kirkeveien 166, 0424 Oslo, Norway K.G. Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, 0316 Oslo, Norway
| | - Ole M Sejersted
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Ullevål, Kirkeveien 166, 0424 Oslo, Norway K.G. Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, 0316 Oslo, Norway
| | - Geir A Christensen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Ullevål, Kirkeveien 166, 0424 Oslo, Norway K.G. Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, 0316 Oslo, Norway
| | - Ivar Sjaastad
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Ullevål, Kirkeveien 166, 0424 Oslo, Norway K.G. Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, 0316 Oslo, Norway
| | - William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Ullevål, Kirkeveien 166, 0424 Oslo, Norway K.G. Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, 0316 Oslo, Norway
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30
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Roe AT, Frisk M, Louch WE. Targeting cardiomyocyte Ca2+ homeostasis in heart failure. Curr Pharm Des 2015; 21:431-48. [PMID: 25483944 PMCID: PMC4475738 DOI: 10.2174/138161282104141204124129] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Accepted: 08/06/2014] [Indexed: 12/19/2022]
Abstract
Improved treatments for heart failure patients will require the development of novel therapeutic strategies that target basal disease
mechanisms. Disrupted cardiomyocyte Ca2+ homeostasis is recognized as a major contributor to the heart failure phenotype, as it
plays a key role in systolic and diastolic dysfunction, arrhythmogenesis, and hypertrophy and apoptosis signaling. In this review, we outline
existing knowledge of the involvement of Ca2+ homeostasis in these deficits, and identify four promising targets for therapeutic intervention:
the sarcoplasmic reticulum Ca2+ ATPase, the Na+-Ca2+ exchanger, the ryanodine receptor, and t-tubule structure. We discuss
experimental data indicating the applicability of these targets that has led to recent and ongoing clinical trials, and suggest future therapeutic
approaches.
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Affiliation(s)
| | | | - William E Louch
- Institute for Experimental Medical Research, Kirkeveien 166, 4.etg. Bygg 7, Oslo University Hospital Ullevål, 0407 Oslo, Norway.
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31
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Murfitt L, Whiteley G, Iqbal MM, Kitmitto A. Targeting caveolin-3 for the treatment of diabetic cardiomyopathy. Pharmacol Ther 2015; 151:50-71. [PMID: 25779609 DOI: 10.1016/j.pharmthera.2015.03.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 03/09/2015] [Indexed: 12/21/2022]
Abstract
Diabetes is a global health problem with more than 550 million people predicted to be diabetic by 2030. A major complication of diabetes is cardiovascular disease, which accounts for over two-thirds of mortality and morbidity in diabetic patients. This increased risk has led to the definition of a diabetic cardiomyopathy phenotype characterised by early left ventricular dysfunction with normal ejection fraction. Here we review the aetiology of diabetic cardiomyopathy and explore the involvement of the protein caveolin-3 (Cav3). Cav3 forms part of a complex mechanism regulating insulin signalling and glucose uptake, processes that are impaired in diabetes. Further, Cav3 is key for stabilisation and trafficking of cardiac ion channels to the plasma membrane and so contributes to the cardiac action potential shape and duration. In addition, Cav3 has direct and indirect interactions with proteins involved in excitation-contraction coupling and so has the potential to influence cardiac contractility. Significantly, both impaired contractility and rhythm disturbances are hallmarks of diabetic cardiomyopathy. We review here how changes to Cav3 expression levels and altered relationships with interacting partners may be contributory factors to several of the pathological features identified in diabetic cardiomyopathy. Finally, the review concludes by considering ways in which levels of Cav3 may be manipulated in order to develop novel therapeutic approaches for treating diabetic cardiomyopathy.
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Affiliation(s)
- Lucy Murfitt
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, M13 9NT, UK
| | - Gareth Whiteley
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, M13 9NT, UK
| | - Mohammad M Iqbal
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, M13 9NT, UK
| | - Ashraf Kitmitto
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, M13 9NT, UK.
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32
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Ibrahim M, Nader A, Yacoub MH, Terracciano C. Manipulation of sarcoplasmic reticulum Ca(2+) release in heart failure through mechanical intervention. J Physiol 2015; 593:3253-9. [PMID: 25922157 DOI: 10.1113/jp270446] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Accepted: 04/26/2015] [Indexed: 12/24/2022] Open
Abstract
Left ventricular assist devices (LVADs) were developed as a means of temporary circulatory support, but the mechanical unloading they offer also results in significant reverse remodelling. In selected patients, these improvements are sufficient to allow ultimate device explantation without requiring transplantation; this represents a fundamental shift in our understanding of heart failure. Like heart failure itself, LVADs influence multiple biological systems. The transverse tubules are a system of membrane invaginations in ventricular cardiomyocytes which allow rapid propagation of the action potential throughout the cell. Through their dense concentration of L-type Ca(2+) channels in close proximity to intracellular ryanodine receptors, the t-tubules enable synchronous Ca(2+) release throughout the cell. The t-tubules' structure appears to be specifically regulated by mechanical load, such that either the overload of heart failure (or the spontaneously hypertensive rat model) or the profound unloading in a chronically unloaded heart result in impaired t-tubule structure, with ineffective Ca(2+) release. While there are multiple molecular pathways which underpin t-tubule regulation, Telethonin (Tcap) appears to be important in regulating the effect of altered loading on the t-tubule system.
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Affiliation(s)
- Michael Ibrahim
- Integrated Resident in Cardiac Surgery, Division of Cardiovascular Surgery, Hospital of the University of Pennsylvania, Philadelphia, PA, 19104, USA
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33
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Chen B, Zhang C, Guo A, Song LS. In situ single photon confocal imaging of cardiomyocyte T-tubule system from Langendorff-perfused hearts. Front Physiol 2015; 6:134. [PMID: 25999861 PMCID: PMC4422017 DOI: 10.3389/fphys.2015.00134] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 04/15/2015] [Indexed: 12/24/2022] Open
Abstract
Transverse tubules (T-tubules) are orderly invaginations of the sarcolemma in mammalian cardiomyocytes. The integrity of T-tubule architecture is critical for cardiac excitation–contraction coupling function. T-tubule remodeling is recognized as a key player in cardiac dysfunction. Early studies on T-tubule structure were based on electron microscopy, which uncovered important information about the T-tubule architecture. The advent of fluorescent membrane probes allowed the application of confocal microscopy to investigations of T-tubule structure. Studies have now been extended beyond single cardiomyocytes to examine the T-tubule network in intact hearts through in situ confocal imaging of Langendorff-perfused hearts. This technique has allowed visualization of T-tubule organization in their natural habitat, avoiding the damage induced by isolation of cardiomyocytes. Additionally, it is possible to obtain T-tubule images in different subepicardial regions in a single intact heart. We review how this state-of-the-art imaging technique has provided important mechanistic insights into maturation of T-tubules in developing hearts and defined the role of T-tubule remodeling in development and progression of heart failure.
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Affiliation(s)
- Biyi Chen
- Division of Cardiovascular Medicine, Department of Internal Medicine, Francois M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa Iowa City, IA, USA
| | - Caimei Zhang
- Division of Cardiovascular Medicine, Department of Internal Medicine, Francois M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa Iowa City, IA, USA
| | - Ang Guo
- Division of Cardiovascular Medicine, Department of Internal Medicine, Francois M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa Iowa City, IA, USA
| | - Long-Sheng Song
- Division of Cardiovascular Medicine, Department of Internal Medicine, Francois M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa Iowa City, IA, USA
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34
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Balycheva M, Faggian G, Glukhov AV, Gorelik J. Microdomain-specific localization of functional ion channels in cardiomyocytes: an emerging concept of local regulation and remodelling. Biophys Rev 2015; 7:43-62. [PMID: 28509981 PMCID: PMC5425752 DOI: 10.1007/s12551-014-0159-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 12/18/2014] [Indexed: 12/26/2022] Open
Abstract
Cardiac excitation involves the generation of action potential by individual cells and the subsequent conduction of the action potential from cell to cell through intercellular gap junctions. Excitation of the cellular membrane results in opening of the voltage-gated L-type calcium ion (Ca2+) channels, thereby allowing a small amount of Ca2+ to enter the cell, which in turn triggers the release of a much greater amount of Ca2+ from the sarcoplasmic reticulum, the intracellular Ca2+ store, and gives rise to the systolic Ca2+ transient and contraction. These processes are highly regulated by the autonomic nervous system, which ensures the acute and reliable contractile function of the heart and the short-term modulation of this function upon changes in heart rate or workload. It has recently become evident that discrete clusters of different ion channels and regulatory receptors are present in the sarcolemma, where they form an interacting network and work together as a part of a macro-molecular signalling complex which in turn allows the specificity, reliability and accuracy of the autonomic modulation of the excitation-contraction processes by a variety of neurohormonal pathways. Disruption in subcellular targeting of ion channels and associated signalling proteins may contribute to the pathophysiology of a variety of cardiac diseases, including heart failure and certain arrhythmias. Recent methodological advances have made it possible to routinely image the topography of live cardiomyocytes, allowing the study of clustering functional ion channels and receptors as well as their coupling within a specific microdomain. In this review we highlight the emerging understanding of the functionality of distinct subcellular microdomains in cardiac myocytes (e.g. T-tubules, lipid rafts/caveolae, costameres and intercalated discs) and their functional role in the accumulation and regulation of different subcellular populations of sodium, Ca2+ and potassium ion channels and their contributions to cellular signalling and cardiac pathology.
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Affiliation(s)
- Marina Balycheva
- Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College London, 4th Floor National Heart and Lung Institute, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK
- Cardiosurgery Department, University of Verona School of Medicine, Verona, Italy
| | - Giuseppe Faggian
- Cardiosurgery Department, University of Verona School of Medicine, Verona, Italy
| | - Alexey V Glukhov
- Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College London, 4th Floor National Heart and Lung Institute, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK.
| | - Julia Gorelik
- Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College London, 4th Floor National Heart and Lung Institute, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK.
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35
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Guo A, Song LS. AutoTT: automated detection and analysis of T-tubule architecture in cardiomyocytes. Biophys J 2015; 106:2729-36. [PMID: 24940790 DOI: 10.1016/j.bpj.2014.05.013] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 05/06/2014] [Accepted: 05/12/2014] [Indexed: 12/31/2022] Open
Abstract
Cardiac transverse (T)-tubules provide a specialized structure for synchronization and stabilization of sarcoplasmic reticulum Ca(2+) release in healthy cardiomyocytes. The application of laser scanning confocal microscopy and the use of fluorescent lipophilic membrane dyes have boosted the discoveries that T-tubule remodeling is a significant factor contributing to cardiac contractile dysfunction. However, the analysis and quantification of the remodeling of T-tubules have been a challenge and remain inconsistent among different research laboratories. Fast Fourier transformation (FFT) is the major analysis method applied to calculate the spatial frequency spectrum, which is used to represent the regularity of T-tubule systems. However, this approach is flawed because the density of T-tubules as well as non-T-tubule signals in the images influence the spectrum power generated by FFT. Preprocessing of images and topological architecture extracting is necessary to remove non-T-tubule noise from the analysis. In addition, manual analysis of images is time consuming and prone to errors and investigator bias. Therefore, we developed AutoTT, an automated analysis program that incorporates image processing, morphological feature extraction, and FFT analysis of spectrum power. The underlying algorithm is implemented in MATLAB (The MathWorks, Natick, MA). The program outputs the densities of transversely oriented T-tubules and longitudinally oriented T-tubules, power spectrum of the overall T-tubule systems, and averaged spacing of T-tubules. We also combined the density and regularity of T-tubules to give an index of T-tubule integrity (TTint), which provides a global evaluation of T-tubule alterations. In summary, AutoTT provides a reliable, easy to use, and fast approach for analyzing myocyte T-tubules. This program can also be applied to measure the density and integrity of other cellular structures.
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Affiliation(s)
- Ang Guo
- Division of Cardiovascular Medicine, Department of Internal Medicine and Francois M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Long-Sheng Song
- Division of Cardiovascular Medicine, Department of Internal Medicine and Francois M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City, Iowa.
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36
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Barresi R, Morris C, Hudson J, Curtis E, Pickthall C, Bushby K, Davies NP, Straub V. Conserved expression of truncated telethonin in a patient with limb-girdle muscular dystrophy 2G. Neuromuscul Disord 2014; 25:349-52. [PMID: 25724973 DOI: 10.1016/j.nmd.2014.12.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Revised: 12/04/2014] [Accepted: 12/11/2014] [Indexed: 11/19/2022]
Abstract
Limb-girdle muscular dystrophy 2G is caused by mutations in the TCAP gene that encodes for telethonin. Here we describe a 49 year-old male patient of Indian descent presenting a classical LGMD phenotype. He had normal motor milestones but became noticeably slower in his early teens and was wheelchair bound by age 44. The muscle biopsy showed myopathic features and absence of labeling with an antibody to the C-terminal portion of telethonin. Sequence analysis of the TCAP gene revealed a novel homozygous mutation in exon 2, predicted to generate a truncated protein of 81 amino acids. Interestingly, an antibody for the full-length protein showed labeling on sections and a single band of ~10 kDa on Western blot. The truncated protein co-localized with filamin C at the Z-line. Our findings indicate that mutant telethonin can be incorporated into the sarcomere and that other LGMD2G patients with retention of telethonin expression may exist.
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Affiliation(s)
- Rita Barresi
- Rare Diseases Advisory Group Service for Neuromuscular Diseases, Muscle Immunoanalysis Unit, Dental Hospital, Richardson Road, Newcastle upon Tyne, UK; The JW Muscular Dystrophy Research Centre and MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK.
| | - Charlotte Morris
- Rare Diseases Advisory Group Service for Neuromuscular Diseases, Muscle Immunoanalysis Unit, Dental Hospital, Richardson Road, Newcastle upon Tyne, UK
| | - Judith Hudson
- The JW Muscular Dystrophy Research Centre and MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Elizabeth Curtis
- Department of Cellular Pathology, University Hospital of Birmingham NHS Foundation Trust, Birmingham, UK
| | - Clare Pickthall
- The JW Muscular Dystrophy Research Centre and MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Kate Bushby
- The JW Muscular Dystrophy Research Centre and MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Nicholas P Davies
- Department of Neurology, University Hospital of Birmingham NHS Foundation Trust, Birmingham, UK
| | - Volker Straub
- The JW Muscular Dystrophy Research Centre and MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
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37
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Jayasinghe ID, Clowsley AH, Munro M, Hou Y, Crossman DJ, Soeller C. Revealing T-Tubules in Striated Muscle with New Optical Super-Resolution Microscopy Techniquess. Eur J Transl Myol 2014; 25:4747. [PMID: 26913143 PMCID: PMC4748971 DOI: 10.4081/ejtm.2015.4747] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 12/18/2014] [Indexed: 01/03/2023] Open
Abstract
The t-tubular system plays a central role in the synchronisation of calcium signalling and excitation-contraction coupling in most striated muscle cells. Light microscopy has been used for imaging t-tubules for well over 100 years and together with electron microscopy (EM), has revealed the three-dimensional complexities of the t-system topology within cardiomyocytes and skeletal muscle fibres from a range of species. The emerging super-resolution single molecule localisation microscopy (SMLM) techniques are offering a near 10-fold improvement over the resolution of conventional fluorescence light microscopy methods, with the ability to spectrally resolve nanometre scale distributions of multiple molecular targets. In conjunction with the next generation of electron microscopy, SMLM has allowed the visualisation and quantification of intricate t-tubule morphologies within large areas of muscle cells at an unprecedented level of detail. In this paper, we review recent advancements in the t-tubule structural biology with the utility of various microscopy techniques. We outline the technical considerations in adapting SMLM to study t-tubules and its potential to further our understanding of the molecular processes that underlie the sub-micron scale structural alterations observed in a range of muscle pathologies.
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Affiliation(s)
| | | | - Michelle Munro
- Department of Physiology, The University of Auckland , New Zealand
| | - Yufeng Hou
- Department of Physiology, The University of Auckland , New Zealand
| | - David J Crossman
- Department of Physiology, The University of Auckland , New Zealand
| | - Christian Soeller
- Biomedical Physics, University of Exeter, UK, New Zealand; Biomedical Physics, University of Exeter, UK, New Zealand
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38
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Circadian regulation of myocardial sarcomeric Titin-cap (Tcap, telethonin): identification of cardiac clock-controlled genes using open access bioinformatics data. PLoS One 2014; 9:e104907. [PMID: 25121604 PMCID: PMC4133362 DOI: 10.1371/journal.pone.0104907] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 07/17/2014] [Indexed: 12/26/2022] Open
Abstract
Circadian rhythms are important for healthy cardiovascular physiology and are regulated at the molecular level by a circadian clock mechanism. We and others previously demonstrated that 9–13% of the cardiac transcriptome is rhythmic over 24 h daily cycles; the heart is genetically a different organ day versus night. However, which rhythmic mRNAs are regulated by the circadian mechanism is not known. Here, we used open access bioinformatics databases to identify 94 transcripts with expression profiles characteristic of CLOCK and BMAL1 targeted genes, using the CircaDB website and JTK_Cycle. Moreover, 22 were highly expressed in the heart as determined by the BioGPS website. Furthermore, 5 heart-enriched genes had human/mouse conserved CLOCK:BMAL1 promoter binding sites (E-boxes), as determined by UCSC table browser, circadian mammalian promoter/enhancer database PEDB, and the European Bioinformatics Institute alignment tool (EMBOSS). Lastly, we validated findings by demonstrating that Titin cap (Tcap, telethonin) was targeted by transcriptional activators CLOCK and BMAL1 by showing 1) Tcap mRNA and TCAP protein had a diurnal rhythm in murine heart; 2) cardiac Tcap mRNA was rhythmic in animals kept in constant darkness; 3) Tcap and control Per2 mRNA expression and cyclic amplitude were blunted in ClockΔ19/Δ19 hearts; 4) BMAL1 bound to the Tcap promoter by ChIP assay; 5) BMAL1 bound to Tcap promoter E-boxes by biotinylated oligonucleotide assay; and 6) CLOCK and BMAL1 induced tcap expression by luciferase reporter assay. Thus this study identifies circadian regulated genes in silico, with validation of Tcap, a critical regulator of cardiac Z-disc sarcomeric structure and function.
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Abstract
The giant protein titin forms a unique filament network in cardiomyocytes, which engages in both mechanical and signaling functions of the heart. TTN, which encodes titin, is also a major human disease gene. In this review, we cover the roles of cardiac titin in normal and failing hearts, with a special emphasis on the contribution of titin to diastolic stiffness. We provide an update on disease-associated titin mutations in cardiac and skeletal muscles and summarize what is known about the impact of protein-protein interactions on titin properties and functions. We discuss the importance of titin-isoform shifts and titin phosphorylation, as well as titin modifications related to oxidative stress, in adjusting the diastolic stiffness of the healthy and the failing heart. Along the way we distinguish among titin alterations in systolic and in diastolic heart failure and ponder the evidence for titin stiffness as a potential target for pharmacological intervention in heart disease.
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Affiliation(s)
- Wolfgang A Linke
- From the Department of Cardiovascular Physiology, Ruhr University Bochum, Bochum, Germany
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Moench I, Lopatin AN. Ca(2+) homeostasis in sealed t-tubules of mouse ventricular myocytes. J Mol Cell Cardiol 2014; 72:374-83. [PMID: 24787472 DOI: 10.1016/j.yjmcc.2014.04.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Revised: 04/15/2014] [Accepted: 04/18/2014] [Indexed: 10/25/2022]
Abstract
We have recently shown that in mouse ventricular myocytes, t-tubules can be quickly and tightly sealed during the resolution of hyposmotic shock of physiologically relevant magnitude. Sealing of t-tubules is associated with trapping extracellular solution inside the myocytes but the ionic homeostasis of sealed t-tubules and the consequences of potential transtubular ion fluxes remain unknown. In this study we investigated the dynamics of Ca(2+) movements associated with sealing of t-tubules. The data show that under normal conditions sealed t-tubules contain Ca(2+) at concentrations below 100μM. However, blockade of voltage-dependent Ca(2+) channels with 10μM nicardipine, or increasing extracellular concentration of K(+) from 5.4mM to 20mM led to several fold increase in concentration of t-tubular Ca(2+). Alternatively, the release of Ca(2+) from sarcoplasmic reticulum using 10mM caffeine led to the restoration of t-tubular Ca(2+) towards extracellular levels within few seconds. Sealing of t-tubules in the presence of extracellular 1.5mM Ca(2+) and 5.4mM extracellular K(+) led to occasional and sporadic intracellular Ca(2+) transients. In contrast, sealing of t-tubules in the presence of 10mM caffeine was characterized by a significant long lasting increase in intracellular Ca(2+). The effect was completely abolished in the absence of extracellular Ca(2+) and significantly reduced in pre-detubulated myocytes but was essentially preserved in the presence of mitochondrial decoupler dinitrophenol. This study shows that sealed t-tubules are capable of highly regulated transport of Ca(2+) and present a major route for Ca(2+) influx into the cytosol during sealing process.
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Affiliation(s)
- I Moench
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - A N Lopatin
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA.
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41
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Ferrantini C, Crocini C, Coppini R, Vanzi F, Tesi C, Cerbai E, Poggesi C, Pavone FS, Sacconi L. The transverse-axial tubular system of cardiomyocytes. Cell Mol Life Sci 2013; 70:4695-710. [PMID: 23846763 PMCID: PMC11113601 DOI: 10.1007/s00018-013-1410-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 06/03/2013] [Accepted: 06/13/2013] [Indexed: 10/26/2022]
Abstract
A characteristic histological feature of striated muscle cells is the presence of deep invaginations of the plasma membrane (sarcolemma), most commonly referred to as T-tubules or the transverse-axial tubular system (TATS). TATS mediates the rapid spread of the electrical signal (action potential) to the cell core triggering Ca(2+) release from the sarcoplasmic reticulum, ultimately inducing myofilament contraction (excitation-contraction coupling). T-tubules, first described in vertebrate skeletal muscle cells, have also been recognized for a long time in mammalian cardiac ventricular myocytes, with a structure and a function that in recent years have been shown to be far more complex and pivotal for cardiac function than initially thought. Renewed interest in T-tubule function stems from the loss and disorganization of T-tubules found in a number of pathological conditions including human heart failure (HF) and dilated and hypertrophic cardiomyopathies, as well as in animal models of HF, chronic ischemia and atrial fibrillation. Disease-related remodeling of the TATS leads to asynchronous and inhomogeneous Ca(2+)-release, due to the presence of orphan ryanodine receptors that have lost their coupling with the dihydropyridine receptors and are either not activated or activated with a delay. Here, we review the physiology of the TATS, focusing first on the relationship between function and structure, and then describing T-tubular remodeling and its reversal in disease settings and following effective therapeutic approaches.
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Affiliation(s)
- C. Ferrantini
- Division of Physiology, Department of Clinical and Experimental Medicine, University of Florence, Florence, Italy
- Centre of Molecular Medicine (C.I.M.M.B.A.), University of Florence, Florence, Italy
| | - C. Crocini
- European Laboratory for Non-Linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Italy
| | - R. Coppini
- Centre of Molecular Medicine (C.I.M.M.B.A.), University of Florence, Florence, Italy
- Division of Pharmacology, Department “NeuroFarBa”, University of Florence, Florence, Italy
| | - F. Vanzi
- European Laboratory for Non-Linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Italy
- Department of Biology, University of Florence, Florence, Italy
| | - C. Tesi
- Division of Physiology, Department of Clinical and Experimental Medicine, University of Florence, Florence, Italy
- Centre of Molecular Medicine (C.I.M.M.B.A.), University of Florence, Florence, Italy
| | - E. Cerbai
- Centre of Molecular Medicine (C.I.M.M.B.A.), University of Florence, Florence, Italy
- Division of Pharmacology, Department “NeuroFarBa”, University of Florence, Florence, Italy
| | - C. Poggesi
- Division of Physiology, Department of Clinical and Experimental Medicine, University of Florence, Florence, Italy
- Centre of Molecular Medicine (C.I.M.M.B.A.), University of Florence, Florence, Italy
| | - F. S. Pavone
- European Laboratory for Non-Linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Italy
- Department of Physics and Astronomy, University of Florence, Sesto Fiorentino, Italy
- National Institute of Optics (INO), National Research Council (CNR), Florence, Italy
| | - L. Sacconi
- European Laboratory for Non-Linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Italy
- National Institute of Optics (INO), National Research Council (CNR), Florence, Italy
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Candasamy AJ, Haworth RS, Cuello F, Ibrahim M, Aravamudhan S, Krüger M, Holt MR, Terracciano CMN, Mayr M, Gautel M, Avkiran M. Phosphoregulation of the titin-cap protein telethonin in cardiac myocytes. J Biol Chem 2013; 289:1282-93. [PMID: 24280220 PMCID: PMC3894314 DOI: 10.1074/jbc.m113.479030] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Telethonin (also known as titin-cap or t-cap) is a muscle-specific protein whose mutation is associated with cardiac and skeletal myopathies through unknown mechanisms. Our previous work identified cardiac telethonin as an interaction partner for the protein kinase D catalytic domain. In this study, kinase assays used in conjunction with MS and site-directed mutagenesis confirmed telethonin as a substrate for protein kinase D and Ca(2+)/calmodulin-dependent kinase II in vitro and identified Ser-157 and Ser-161 as the phosphorylation sites. Phosphate affinity electrophoresis and MS revealed endogenous telethonin to exist in a constitutively bis-phosphorylated form in isolated adult rat ventricular myocytes and in mouse and rat ventricular myocardium. Following heterologous expression in myocytes by adenoviral gene transfer, wild-type telethonin became bis-phosphorylated, whereas S157A/S161A telethonin remained non-phosphorylated. Nevertheless, both proteins localized predominantly to the sarcomeric Z-disc, where they partially replaced endogenous telethonin. Such partial replacement with S157A/S161A telethonin disrupted transverse tubule organization and prolonged the time to peak of the intracellular Ca(2+) transient and increased its variance. These data reveal, for the first time, that cardiac telethonin is constitutively bis-phosphorylated and suggest that such phosphorylation is critical for normal telethonin function, which may include maintenance of transverse tubule organization and intracellular Ca(2+) transients.
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Affiliation(s)
- Alexandra J Candasamy
- From the Cardiovascular Division, King's College London British Heart Foundation Centre, London SE1 7EH, United Kingdom
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43
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Sequeira V, Nijenkamp LLAM, Regan JA, van der Velden J. The physiological role of cardiac cytoskeleton and its alterations in heart failure. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:700-22. [PMID: 23860255 DOI: 10.1016/j.bbamem.2013.07.011] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 07/01/2013] [Accepted: 07/08/2013] [Indexed: 12/11/2022]
Abstract
Cardiac muscle cells are equipped with specialized biochemical machineries for the rapid generation of force and movement central to the work generated by the heart. During each heart beat cardiac muscle cells perceive and experience changes in length and load, which reflect one of the fundamental principles of physiology known as the Frank-Starling law of the heart. Cardiac muscle cells are unique mechanical stretch sensors that allow the heart to increase cardiac output, and adjust it to new physiological and pathological situations. In the present review we discuss the mechano-sensory role of the cytoskeletal proteins with respect to their tight interaction with the sarcolemma and extracellular matrix. The role of contractile thick and thin filament proteins, the elastic protein titin, and their anchorage at the Z-disc and M-band, with associated proteins are reviewed in physiologic and pathologic conditions leading to heart failure. This article is part of a Special Issue entitled: Reciprocal influences between cell cytoskeleton and membrane channels, receptors and transporters. Guest Editor: Jean Claude Hervé
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Affiliation(s)
- Vasco Sequeira
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands
| | - Louise L A M Nijenkamp
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands
| | - Jessica A Regan
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands; Department of Physiology, Molecular Cardiovascular Research Program, Sarver Heart Center, University of Arizona, Tucson, AZ 85724, USA
| | - Jolanda van der Velden
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands; ICIN-Netherlands Heart Institute, The Netherlands.
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Trafford AW, Clarke JD, Richards MA, Eisner DA, Dibb KM. Calcium signalling microdomains and the t-tubular system in atrial mycoytes: potential roles in cardiac disease and arrhythmias. Cardiovasc Res 2013; 98:192-203. [PMID: 23386275 DOI: 10.1093/cvr/cvt018] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The atria contribute 25% to ventricular stroke volume and are the site of the commonest cardiac arrhythmia, atrial fibrillation (AF). The initiation of contraction in the atria is similar to that in the ventricle involving a systolic rise of intracellular Ca(2+) concentration ([Ca(2+)](i)). There are, however, substantial inter-species differences in the way systolic Ca(2+) is regulated in atrial cells. These differences are a consequence of a well-developed and functionally relevant transverse (t)-tubule network in the atria of large mammals, including humans, and its virtual absence in smaller laboratory species such as the rat. Where T-tubules are absent, the systolic Ca(2+) transient results from a 'fire-diffuse-fire' sequential recruitment of Ca(2+) release sites from the cell edge to the centre and hence marked spatiotemporal heterogeneity of systolic Ca(2+). Conversely, the well-developed T-tubule network in large mammals ensures a near synchronous rise of [Ca(2+)](i). In addition to synchronizing the systolic rise of [Ca(2+)](i), the presence of T-tubules in the atria of large mammals, by virtue of localization of the L-type Ca(2+) channels and Na(+)-Ca(2+) exchanger antiporters on the T-tubules, may serve to, respectively, accelerate changes in the amplitude of the systolic Ca(2+) transient during inotropic manoeuvres and lower diastolic [Ca(2+)](i). On the other hand, the presence of T-tubules and hence wider cellular distribution of the Na(+)-Ca(2+) exchanger may predispose the atria of large mammals to Ca(2+)-dependent delayed afterdepolarizations (DADs); this may be a determining factor in why the atria of large mammals spontaneously develop and maintain AF.
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Affiliation(s)
- Andrew W Trafford
- Unit of Cardiac Physiology, Manchester Academic Health Science Centre, Institute of Cardiovascular Science, University of Manchester, 3.23 Core Technology Facility, 46 Grafton Street, Manchester M13 9PT, UK
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Guo A, Zhang C, Wei S, Chen B, Song LS. Emerging mechanisms of T-tubule remodelling in heart failure. Cardiovasc Res 2013; 98:204-15. [PMID: 23393229 DOI: 10.1093/cvr/cvt020] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Cardiac excitation-contraction coupling occurs primarily at the sites of transverse (T)-tubule/sarcoplasmic reticulum junctions. The orderly T-tubule network guarantees the instantaneous excitation and synchronous activation of nearly all Ca(2+) release sites throughout the large ventricular myocyte. Because of the critical roles played by T-tubules and the array of channels and transporters localized to the T-tubule membrane network, T-tubule architecture has recently become an area of considerable research interest in the cardiovascular field. This review will focus on the current knowledge regarding normal T-tubule structure and function in the heart, T-tubule remodelling in the transition from compensated hypertrophy to heart failure, and the impact of T-tubule remodelling on myocyte Ca(2+) handling function. In the last section, we discuss the molecular mechanisms underlying T-tubule remodelling in heart disease.
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Affiliation(s)
- Ang Guo
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
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46
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Ibrahim M, Terracciano CM. Reversibility of T-tubule remodelling in heart failure: mechanical load as a dynamic regulator of the T-tubules. Cardiovasc Res 2013; 98:225-32. [PMID: 23345265 DOI: 10.1093/cvr/cvt016] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The T-tubule system in ventricular cardiomyocytes is essential for synchronous Ca(2+) handling, and, therefore, efficient contraction. T-tubular remodelling is a common feature of heart disease. In this review, we discuss whether t-tubular remodelling can be reversed and which factors may be implicated in this process. In particular, we focus on the interaction between mechanical load variation and T-tubule structure and function. What is the evidence of this relationship? What is the role of different degrees and durations of mechanical load variation? In what settings might mechanical load variation have detrimental or beneficial effects on T-tubule structure and function? What are the molecular determinants of this interaction? Ultimately this discussion is used to address the question of whether mechanical load variation can provide an understanding to underpin attempts to induce recovery of the T-tubule system. In reviewing these questions, we define what remains to be discovered in understanding T-tubule recovery.
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Affiliation(s)
- Michael Ibrahim
- Laboratory of Cell Electrophysiology, 4th floor, Imperial Centre for Translational and Experimental Medicine, Hammersmith Campus, Du Cane Road, London W12 0NN, UK
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