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Gong K, Wu Q, Xie T, Luo Y, Guo H, Tan Z, Chen J, Yang Y, Xie L. A novel mutation in the tropomyosin 1 gene in a Chinese patient with hypertrophic cardiomyopathy. ALL LIFE 2022. [DOI: 10.1080/26895293.2022.2155711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Ke Gong
- Department of Cardiovascular Surgery, The Second Xiangya Hospital of Central South University, Central South University, Changsha, P.R. People’s Republic of China
| | - Qin Wu
- Department of Cardiovascular Surgery, The Second Xiangya Hospital of Central South University, Central South University, Changsha, P.R. People’s Republic of China
| | - Ting Xie
- Department of Cardiovascular Surgery, The Second Xiangya Hospital of Central South University, Central South University, Changsha, P.R. People’s Republic of China
| | - Yong Luo
- Department of Cardiovascular Surgery, The Second Xiangya Hospital of Central South University, Central South University, Changsha, P.R. People’s Republic of China
| | - Hui Guo
- Department of Cardiovascular Surgery, The Second Xiangya Hospital of Central South University, Central South University, Changsha, P.R. People’s Republic of China
| | - Zhiping Tan
- The Clinical Center for Gene Diagnosis and Therapy of The State Key Laboratory of Medical Genetics, The Second Xiangya Hospital of Central South University, Central South University, Changsha, P.R. People’s Republic of China
| | - Jinlan Chen
- Department of Cardiovascular Surgery, The Second Xiangya Hospital of Central South University, Central South University, Changsha, P.R. People’s Republic of China
| | - Yifeng Yang
- Department of Cardiovascular Surgery, The Second Xiangya Hospital of Central South University, Central South University, Changsha, P.R. People’s Republic of China
| | - Li Xie
- Department of Cardiovascular Surgery, The Second Xiangya Hospital of Central South University, Central South University, Changsha, P.R. People’s Republic of China
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2
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Kaviarasan V, Mohammed V, Veerabathiran R. Genetic predisposition study of heart failure and its association with cardiomyopathy. Egypt Heart J 2022; 74:5. [PMID: 35061126 PMCID: PMC8782994 DOI: 10.1186/s43044-022-00240-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Accepted: 01/12/2022] [Indexed: 12/12/2022] Open
Abstract
Heart failure (HF) is a clinical condition distinguished by structural and functional defects in the myocardium, which genetic and environmental factors can induce. HF is caused by various genetic factors that are both heterogeneous and complex. The incidence of HF varies depending on the definition and area, but it is calculated to be between 1 and 2% in developed countries. There are several factors associated with the progression of HF, ranging from coronary artery disease to hypertension, of which observed the most common genetic cause to be cardiomyopathy. The main objective of this study is to investigate heart failure and its association with cardiomyopathy with their genetic variants. The selected novel genes that have been linked to human inherited cardiomyopathy play a critical role in the pathogenesis and progression of HF. Research sources collected from the human gene mutation and several databases revealed that numerous genes are linked to cardiomyopathy and thus explained the hereditary influence of such a condition. Our findings support the understanding of the genetics aspect of HF and will provide more accurate evidence of the role of changing disease accuracy. Furthermore, a better knowledge of the molecular pathophysiology of genetically caused HF could contribute to the emergence of personalized therapeutics in future.
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Affiliation(s)
- Vaishak Kaviarasan
- Human Cytogenetics and Genomics Laboratory, Faculty of Allied Health Sciences, Chettinad Hospital and Research Institute, Chettinad Academy of Research and Education, Kelambakkam, Tamilnadu, 603103, India
| | - Vajagathali Mohammed
- Human Cytogenetics and Genomics Laboratory, Faculty of Allied Health Sciences, Chettinad Hospital and Research Institute, Chettinad Academy of Research and Education, Kelambakkam, Tamilnadu, 603103, India
| | - Ramakrishnan Veerabathiran
- Human Cytogenetics and Genomics Laboratory, Faculty of Allied Health Sciences, Chettinad Hospital and Research Institute, Chettinad Academy of Research and Education, Kelambakkam, Tamilnadu, 603103, India.
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3
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Cao J, Routh AL, Kuyumcu-Martinez MN. Nanopore sequencing reveals full-length Tropomyosin 1 isoforms and their regulation by RNA-binding proteins during rat heart development. J Cell Mol Med 2021; 25:8352-8362. [PMID: 34302435 PMCID: PMC8419188 DOI: 10.1111/jcmm.16795] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 07/01/2021] [Accepted: 07/06/2021] [Indexed: 12/11/2022] Open
Abstract
Alternative splicing (AS) contributes to the diversity of the proteome by producing multiple isoforms from a single gene. Although short‐read RNA‐sequencing methods have been the gold standard for determining AS patterns of genes, they have a difficulty in defining full‐length mRNA isoforms assembled using different exon combinations. Tropomyosin 1 (TPM1) is an actin‐binding protein required for cytoskeletal functions in non‐muscle cells and for contraction in muscle cells. Tpm1 undergoes AS regulation to generate muscle versus non‐muscle TPM1 protein isoforms with distinct physiological functions. It is unclear which full‐length Tpm1 isoforms are produced via AS and how they are regulated during heart development. To address these, we utilized nanopore long‐read cDNA sequencing without gene‐specific PCR amplification. In rat hearts, we identified full‐length Tpm1 isoforms composed of distinct exons with specific exon linkages. We showed that Tpm1 undergoes AS transitions during embryonic heart development such that muscle‐specific exons are connected generating predominantly muscle‐specific Tpm1 isoforms in adult hearts. We found that the RNA‐binding protein RBFOX2 controls AS of rat Tpm1 exon 6a, which is important for cooperative actin binding. Furthermore, RBFOX2 regulates Tpm1 AS of exon 6a antagonistically to the RNA‐binding protein PTBP1. In sum, we defined full‐length Tpm1 isoforms with different exon combinations that are tightly regulated during cardiac development and provided insights into the regulation of Tpm1 AS by RNA‐binding proteins. Our results demonstrate that nanopore sequencing is an excellent tool to determine full‐length AS variants of muscle‐enriched genes.
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Affiliation(s)
- Jun Cao
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Andrew L Routh
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, USA.,Sealy Centre for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas, USA
| | - Muge N Kuyumcu-Martinez
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, USA.,Institute for Translational Sciences, University of Texas Medical Branch, Galveston, Texas, USA.,Department of Neuroscience, Cell Biology, and Anatomy, University of Texas Medical Branch, Galveston, Texas, USA
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Yao Q, Zhang W, Zhang T. Association of single nucleotide polymorphisms in the 3'UTR region of TPM1 gene with dilated cardiomyopathy: A case-control study. Medicine (Baltimore) 2019; 98:e17710. [PMID: 31689804 PMCID: PMC6946328 DOI: 10.1097/md.0000000000017710] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Tropomyosin 1 (TPM1) is a protein that constitutes the sarcomere filaments and is encoded by the TPM1 gene. The aim of the present study is to investigate the correlation between the 3' untranslated region (3'UTR) single nucleotide polymorphisms (SNPs) of the TPM1 gene and dilated cardiomyopathy (DCM).A total of 245 patients with DCM and 245 healthy controls were recruited with 5 ml of venous blood. Genomic DNA was extracted to analyze the TPM1 gene rs12148828, rs11558748, rs707602, rs6738, rs7178040 loci genotypes, and the plasma miR-21 level was analyzed by reverse transcription-PCR (RT-PCR).The risk of DCM development in the rs6738 locus G allele carriers were 1.69 times more than A allele carriers (95% CI: 1.22-2.33, P = .001). Age and gender had no effect on the association of TPM1 gene SNPs with DCM risk (P > .05). The plasma miR-21 level of TPM1 gene rs6738 locus AA carriers was significantly higher than that of the AG and GG genotypes (P < .001).The SNPs of TPM1 gene rs6738 locus is associated with the risk of DCM, which may be related to the abnormal increase of miR-21 level in DCM patients, but further research is needed to prove the causal relationship between miR-21 level and DCM risk.
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Affiliation(s)
- Qiang Yao
- Department of Cardiology, Zhejiang Chinese Medicine and Western Medicine Integrated Hospital/Hangzhou Red Cross Hospital, Hangzhou Zhejiang
| | - Wei Zhang
- Department of Cardiology, Chengwu county people's hospital, Chengwu County, Shandong Province
| | - Tianjie Zhang
- Department of Cardiology, Tongde Hospital of Zhejiang Province, Hangzhou, Zhejiang, China
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5
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Abstract
The interactions of cytoskeletal actin filaments with myosin family motors are essential for the integrity and function of eukaryotic cells. They support a wide range of force-dependent functions. These include mechano-transduction, directed transcellular transport processes, barrier functions, cytokinesis, and cell migration. Despite the indispensable role of tropomyosins in the generation and maintenance of discrete actomyosin-based structures, the contribution of individual cytoskeletal tropomyosin isoforms to the structural and functional diversification of the actin cytoskeleton remains a work in progress. Here, we review processes that contribute to the dynamic sorting and targeted distribution of tropomyosin isoforms in the formation of discrete actomyosin-based structures in animal cells and their effects on actin-based motility and contractility.
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Selection signatures in four German warmblood horse breeds: Tracing breeding history in the modern sport horse. PLoS One 2019; 14:e0215913. [PMID: 31022261 PMCID: PMC6483353 DOI: 10.1371/journal.pone.0215913] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 04/10/2019] [Indexed: 12/04/2022] Open
Abstract
The study of selection signatures helps to find genomic regions that have been under selective pressure and might host genes or variants that modulate important phenotypes. Such knowledge improves our understanding of how breeding programmes have shaped the genomes of livestock. In this study, 942 stallions were included from four, exemplarily chosen, German warmblood breeds with divergent historical and recent selection focus and different crossbreeding policies: Trakehner (N = 44), Holsteiner (N = 358), Hanoverian (N = 319) and Oldenburger (N = 221). Those breeds are nowadays bred for athletic performance and aptitude for show-jumping, dressage or eventing, with a particular focus of Holsteiner on the first discipline. Blood samples were collected during the health exams of the stallion preselections before licensing and were genotyped with the Illumina EquineSNP50 BeadChip. Autosomal markers were used for a multi-method search for signals of positive selection. Analyses within and across breeds were conducted by using the integrated Haplotype Score (iHS), cross-population Extended Haplotype Homozygosity (xpEHH) and Runs of Homozygosity (ROH). Oldenburger and Hanoverian showed very similar iHS signatures, but breed specificities were detected on multiple chromosomes with the xpEHH. The Trakehner clustered as a distinct group in a principal component analysis and also showed the highest number of ROHs, which reflects their historical bottleneck. Beside breed specific differences, we found shared selection signals in an across breed iHS analysis on chromosomes 1, 4 and 7. After investigation of these iHS signals and shared ROH for potential functional candidate genes and affected pathways including enrichment analyses, we suggest that genes affecting muscle functionality (TPM1, TMOD2-3, MYO5A, MYO5C), energy metabolism and growth (AEBP1, RALGAPA2, IGFBP1, IGFBP3-4), embryonic development (HOXB-complex) and fertility (THEGL, ZPBP1-2, TEX14, ZP1, SUN3 and CFAP61) have been targeted by selection in all breeds. Our findings also indicate selection pressure on KITLG, which is well-documented for influencing pigmentation.
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Iorga B, Schwanke K, Weber N, Wendland M, Greten S, Piep B, Dos Remedios CG, Martin U, Zweigerdt R, Kraft T, Brenner B. Differences in Contractile Function of Myofibrils within Human Embryonic Stem Cell-Derived Cardiomyocytes vs. Adult Ventricular Myofibrils Are Related to Distinct Sarcomeric Protein Isoforms. Front Physiol 2018; 8:1111. [PMID: 29403388 PMCID: PMC5780405 DOI: 10.3389/fphys.2017.01111] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Accepted: 12/15/2017] [Indexed: 01/10/2023] Open
Abstract
Characterizing the contractile function of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) is key for advancing their utility for cellular disease models, promoting cell based heart repair, or developing novel pharmacological interventions targeting cardiac diseases. The aim of the present study was to understand whether steady-state and kinetic force parameters of β-myosin heavy chain (βMyHC) isoform-expressing myofibrils within human embryonic stem cell-derived cardiomyocytes (hESC-CMs) differentiated in vitro resemble those of human ventricular myofibrils (hvMFs) isolated from adult donor hearts. Contractile parameters were determined using the same micromechanical method and experimental conditions for both types of myofibrils. We identified isoforms and phosphorylation of main sarcomeric proteins involved in the modulation of force generation of both, chemically demembranated hESC-CMs (d-hESC-CMs) and hvMFs. Our results indicate that at saturating Ca2+ concentration, both human-derived contractile systems developed forces with similar rate constants (0.66 and 0.68 s−1), reaching maximum isometric force that was significantly smaller for d-hESC-CMs (42 kPa) than for hvMFs (94 kPa). At submaximal Ca2+-activation, where intact cardiomyocytes normally operate, contractile parameters of d-hESC-CMs and hvMFs exhibited differences. Ca2+ sensitivity of force was higher for d-hESC-CMs (pCa50 = 6.04) than for hvMFs (pCa50 = 5.80). At half-maximum activation, the rate constant for force redevelopment was significantly faster for d-hESC-CMs (0.51 s−1) than for hvMFs (0.28 s−1). During myofibril relaxation, kinetics of the slow force decay phase were significantly faster for d-hESC-CMs (0.26 s−1) than for hvMFs (0.21 s−1), while kinetics of the fast force decay were similar and ~20x faster. Protein analysis revealed that hESC-CMs had essentially no cardiac troponin-I, and partially non-ventricular isoforms of some other sarcomeric proteins, explaining the functional discrepancies. The sarcomeric protein isoform pattern of hESC-CMs had features of human cardiomyocytes at an early developmental stage. The study indicates that morphological and ultrastructural maturation of βMyHC isoform-expressing hESC-CMs is not necessarily accompanied by ventricular-like expression of all sarcomeric proteins. Our data suggest that hPSC-CMs could provide useful tools for investigating inherited cardiac diseases affecting contractile function during early developmental stages.
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Affiliation(s)
- Bogdan Iorga
- Department of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany.,Department of Physical Chemistry, Faculty of Chemistry, University of Bucharest, Bucharest, Romania
| | - Kristin Schwanke
- Department of Cardiac, Thoracic, Transplantation and Vascular Surgery, Leibniz Research Laboratories for Biotechnology and Artificial Organs, REBIRTH-Center for Regenerative Medicine, Hannover Medical School, Hannover, Germany
| | - Natalie Weber
- Department of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Meike Wendland
- Department of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Stephan Greten
- Department of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Birgit Piep
- Department of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | | | - Ulrich Martin
- Department of Cardiac, Thoracic, Transplantation and Vascular Surgery, Leibniz Research Laboratories for Biotechnology and Artificial Organs, REBIRTH-Center for Regenerative Medicine, Hannover Medical School, Hannover, Germany
| | - Robert Zweigerdt
- Department of Cardiac, Thoracic, Transplantation and Vascular Surgery, Leibniz Research Laboratories for Biotechnology and Artificial Organs, REBIRTH-Center for Regenerative Medicine, Hannover Medical School, Hannover, Germany
| | - Theresia Kraft
- Department of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Bernhard Brenner
- Department of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
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8
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Dykes IM, van Bueren KL, Scambler PJ. HIC2 regulates isoform switching during maturation of the cardiovascular system. J Mol Cell Cardiol 2018; 114:29-37. [PMID: 29061339 PMCID: PMC5807030 DOI: 10.1016/j.yjmcc.2017.10.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 10/04/2017] [Accepted: 10/19/2017] [Indexed: 12/30/2022]
Abstract
Physiological changes during embryonic development are associated with changes in the isoform expression of both myocyte sarcomeric proteins and of erythrocyte haemoglobins. Cell type-specific isoform expression of these genes also occurs. Although these changes appear to be coordinated, it is unclear how changes in these disparate cell types may be linked. The transcription factor Hic2 is required for normal cardiac development and the mutant is embryonic lethal. Hic2 embryos exhibit precocious expression of the definitive-lineage haemoglobin Hbb-bt in circulating primitive erythrocytes and of foetal isoforms of cardiomyocyte genes (creatine kinase, Ckm, and eukaryotic elongation factor Eef1a2) as well as ectopic cardiac expression of fast-twitch skeletal muscle troponin isoforms. We propose that HIC2 regulates a switching event within both the contractile machinery of cardiomyocytes and the oxygen carrying systems during the developmental period where demands on cardiac loading change rapidly.
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Affiliation(s)
- Iain M Dykes
- Institute of Child Health, University College London, 30 Guilford St, London WC1N 1EH, United Kingdom; Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol Royal Infirmary, Upper Maudlin St, Bristol BS2 8HW, United Kingdom.
| | - Kelly Lammerts van Bueren
- Institute of Child Health, University College London, 30 Guilford St, London WC1N 1EH, United Kingdom
| | - Peter J Scambler
- Institute of Child Health, University College London, 30 Guilford St, London WC1N 1EH, United Kingdom
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9
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Shchepkin DV, Nikitina LV, Bershitsky SY, Kopylova GV. The isoforms of α-actin and myosin affect the Ca 2+ regulation of the actin-myosin interaction in the heart. Biochem Biophys Res Commun 2017. [PMID: 28623140 DOI: 10.1016/j.bbrc.2017.06.043] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Myocardium of mammals contains a wide range of isoforms of proteins that provides contractile function of the heart. These are two isoforms of ventricular and two of atrial myosin, α- and β-tropomyosin, and two isoforms of α-actin: cardiac and skeletal. We believe that the difference in the amino acid sequence of α-actin can affect the calcium regulation of the actin-myosin interaction. To test this hypothesis, we investigated effects of the isoforms of α-actin, cardiac and skeletal, and the isoforms of cardiac myosin on the calcium regulation of the actin-myosin interaction in an in vitro motility assay using reconstructed regulated thin filaments. The results show that isoforms of α-actin and the ratio of α/β-chains of Tpm differently affect the calcium regulation of the actin-myosin interaction in myocardium in dependence on cardiac myosin isoforms.
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Affiliation(s)
- Daniil V Shchepkin
- Institute of Immunology and Physiology, Russian Academy of Sciences, Yekaterinburg 620049, Russia
| | - Larisa V Nikitina
- Institute of Immunology and Physiology, Russian Academy of Sciences, Yekaterinburg 620049, Russia
| | - Sergey Y Bershitsky
- Institute of Immunology and Physiology, Russian Academy of Sciences, Yekaterinburg 620049, Russia
| | - Galina V Kopylova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Yekaterinburg 620049, Russia.
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10
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England J, Granados-Riveron J, Polo-Parada L, Kuriakose D, Moore C, Brook JD, Rutland CS, Setchfield K, Gell C, Ghosh TK, Bu'Lock F, Thornborough C, Ehler E, Loughna S. Tropomyosin 1: Multiple roles in the developing heart and in the formation of congenital heart defects. J Mol Cell Cardiol 2017; 106:1-13. [PMID: 28359939 PMCID: PMC5441184 DOI: 10.1016/j.yjmcc.2017.03.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 03/21/2017] [Accepted: 03/24/2017] [Indexed: 12/03/2022]
Abstract
Tropomyosin 1 (TPM1) is an essential sarcomeric component, stabilising the thin filament and facilitating actin's interaction with myosin. A number of sarcomeric proteins, such as alpha myosin heavy chain, play crucial roles in cardiac development. Mutations in these genes have been linked to congenital heart defects (CHDs), occurring in approximately 1 in 145 live births. To date, TPM1 has not been associated with isolated CHDs. Analysis of 380 CHD cases revealed three novel mutations in the TPM1 gene; IVS1 + 2T > C, I130V, S229F and a polyadenylation signal site variant GATAAA/AATAAA. Analysis of IVS1 + 2T > C revealed aberrant pre-mRNA splicing. In addition, abnormal structural properties were found in hearts transfected with TPM1 carrying I130V and S229F mutations. Phenotypic analysis of TPM1 morpholino-treated embryos revealed roles for TPM1 in cardiac looping, atrial septation and ventricular trabeculae formation and increased apoptosis was seen within the heart. In addition, sarcomere assembly was affected and altered action potentials were exhibited. This study demonstrated that sarcomeric TPM1 plays vital roles in cardiogenesis and is a suitable candidate gene for screening individuals with isolated CHDs. Four mutations identified in the TPM1 gene; IVS1 + 2T > C, I130V, S229F and GATAAA/AATAAA. In vitro analysis of IVS1 + 2T > C revealed aberrant pre-mRNA splicing. I130V and S229F mutations caused abnormal structural properties in the sarcomere. Reduced TPM1 expression during early cardiogenesis causes aberrant gross morphology. Apoptosis, sarcomere assembly and cardiac conduction were also affected.
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Affiliation(s)
| | - Javier Granados-Riveron
- Laboratory of Genomics, Genetics and Bioinformatics, Hospital Infantil de México Federico Gómez, Mexico
| | - Luis Polo-Parada
- Department of Medical Pharmacology and Physiology, School of Medicine, University of Missouri, USA
| | | | | | - J David Brook
- School of Life Sciences, University of Nottingham, UK
| | - Catrin S Rutland
- School of Veterinary Medicine and Science, University of Nottingham, UK
| | | | | | | | - Frances Bu'Lock
- East Midlands Congenital Heart Centre, Glenfield Hospital, Leicester, UK
| | | | - Elisabeth Ehler
- Randall Division of Cell and Molecular Biophysics, The Cardiovascular Division, King's College London, UK
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Gunning PW, Hardeman EC, Lappalainen P, Mulvihill DP. Tropomyosin - master regulator of actin filament function in the cytoskeleton. J Cell Sci 2015; 128:2965-74. [PMID: 26240174 DOI: 10.1242/jcs.172502] [Citation(s) in RCA: 169] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Tropomyosin (Tpm) isoforms are the master regulators of the functions of individual actin filaments in fungi and metazoans. Tpms are coiled-coil parallel dimers that form a head-to-tail polymer along the length of actin filaments. Yeast only has two Tpm isoforms, whereas mammals have over 40. Each cytoskeletal actin filament contains a homopolymer of Tpm homodimers, resulting in a filament of uniform Tpm composition along its length. Evidence for this 'master regulator' role is based on four core sets of observation. First, spatially and functionally distinct actin filaments contain different Tpm isoforms, and recent data suggest that members of the formin family of actin filament nucleators can specify which Tpm isoform is added to the growing actin filament. Second, Tpms regulate whole-organism physiology in terms of morphogenesis, cell proliferation, vesicle trafficking, biomechanics, glucose metabolism and organ size in an isoform-specific manner. Third, Tpms achieve these functional outputs by regulating the interaction of actin filaments with myosin motors and actin-binding proteins in an isoform-specific manner. Last, the assembly of complex structures, such as stress fibers and podosomes involves the collaboration of multiple types of actin filament specified by their Tpm composition. This allows the cell to specify actin filament function in time and space by simply specifying their Tpm isoform composition.
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Affiliation(s)
- Peter W Gunning
- School of Medical Sciences, UNSW Australia, Sydney 2052, Australia
| | - Edna C Hardeman
- School of Medical Sciences, UNSW Australia, Sydney 2052, Australia
| | - Pekka Lappalainen
- Institute of Biotechnology, University of Helsinki, Helsinki, 00014, Finland
| | - Daniel P Mulvihill
- School of Biosciences, Stacey Building, University of Kent, Canterbury, Kent CT2 7NJ, UK
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12
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Instability in the central region of tropomyosin modulates the function of its overlapping ends. Biophys J 2014; 105:2104-13. [PMID: 24209855 DOI: 10.1016/j.bpj.2013.09.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 08/20/2013] [Accepted: 09/17/2013] [Indexed: 12/14/2022] Open
Abstract
The causal link between disparate tropomyosin (Tm) functions and the structural instability in Tm is unknown. To test the hypothesis that the structural instability in the central region of Tm modulates the function of the overlapping ends of contiguous Tm dimers, we used transgenic mice (Tm(DM)) that expressed a mutant α-Tm in the heart; S229E and H276N substitutions induce structural instability in the central region and the overlapping ends of Tm, respectively. In addition, two mouse cardiac troponin T mutants (TnT(1-44Δ) and TnT(45-74Δ)) that have a divergent effect on the overlapping ends of Tm were employed. The S229E-induced instability in the central region of Tm(DM) altered the overlapping ends of Tm(DM), thereby it negated the attenuating effect of H276N on Ca(2+)-activated maximal tension. The rate of cross-bridge detachment (g) decreased in Tm(DM)+TnT(WT) and Tm(H276N)+TnT(WT) fibers but increased in Tm(DM)+TnT(45-74Δ) fibers; however, TnT(45-74Δ) did not alter g, demonstrating that S229E in Tm(DM) had divergent effects on g. The S229E substitution in Tm(DM) ablated the H276N-induced desensitization of myofilament Ca(2+) sensitivity in Tm(DM)+TnT(1-44Δ) fibers. To our knowledge, novel findings from this study show that the structural instability in the central region of Tm modifies cardiac contractile function via its effect on the overlapping ends of contiguous Tm.
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13
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Schulz EM, Wilder T, Chowdhury SAK, Sheikh HN, Wolska BM, Solaro RJ, Wieczorek DF. Decreasing tropomyosin phosphorylation rescues tropomyosin-induced familial hypertrophic cardiomyopathy. J Biol Chem 2013; 288:28925-35. [PMID: 23960072 DOI: 10.1074/jbc.m113.466466] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Studies indicate that tropomyosin (Tm) phosphorylation status varies in different mouse models of cardiac disease. Investigation of basal and acute cardiac function utilizing a mouse model expressing an α-Tm protein that cannot be phosphorylated (S283A) shows a compensated hypertrophic phenotype with significant increases in SERCA2a expression and phosphorylation of phospholamban Ser-16 (Schulz, E. M., Correll, R. N., Sheikh, H. N., Lofrano-Alves, M. S., Engel, P. L., Newman, G., Schultz Jel, J., Molkentin, J. D., Wolska, B. M., Solaro, R. J., and Wieczorek, D. F. (2012) J. Biol. Chem. 287, 44478-44489). With these results, we hypothesized that decreasing α-Tm phosphorylation may be beneficial in the context of a chronic, intrinsic stressor. To test this hypothesis, we utilized the familial hypertrophic cardiomyopathy (FHC) α-Tm E180G model (Prabhakar, R., Boivin, G. P., Grupp, I. L., Hoit, B., Arteaga, G., Solaro, R. J., and Wieczorek, D. F. (2001) J. Mol. Cell. Cardiol. 33, 1815-1828). These FHC hearts are characterized by increased heart:body weight ratios, fibrosis, increased myofilament Ca(2+) sensitivity, and contractile defects. The FHC mice die by 6-8 months of age. We generated mice expressing both the E180G and S283A mutations and found that the hypertrophic phenotype was rescued in the α-Tm E180G/S283A double mutant transgenic animals; these mice exhibited no signs of cardiac hypertrophy and displayed improved cardiac function. These double mutant transgenic hearts showed increased phosphorylation of phospholamban Ser-16 and Thr-17 compared with the α-Tm E180G mice. This is the first study to demonstrate that decreasing phosphorylation of tropomyosin can rescue a hypertrophic cardiomyopathic phenotype.
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Affiliation(s)
- Emily M Schulz
- From the Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267
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In-depth proteomic analysis of human tropomyosin by top-down mass spectrometry. J Muscle Res Cell Motil 2013; 34:199-210. [PMID: 23881156 DOI: 10.1007/s10974-013-9352-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Accepted: 06/27/2013] [Indexed: 01/29/2023]
Abstract
Tropomyosins (Tms) are a family of highly conserved actin-binding proteins that play critical roles in a variety of processes, most notably, in the regulation of muscle contraction and relaxation. It is well known that different Tm isoforms have distinct functions and that altered expression of Tm isoforms could lead to changes in cardiac structure and function. To precisely define Tm isoform expression in the human heart, towards a better understanding of their functional roles, we have employed top-down mass spectrometry for in-depth proteomic characterization of Tm isoforms. Using a minimal amount of human heart tissue from rejected donor organs, we confirmed the presence of multiple Tm isoforms including α-Tm, β-Tm and κ-Tm in the human heart, with α-Tm being the predominant isoform, followed by minor isoforms of β-Tm and κ-Tm. Interestingly, our data revealed regional variations of Tm isoforms and post-translational modifications in the human heart. Specifically, the expression level of κ-Tm was highest in the left atrium but nearly undetectable in the left ventricle. The phosphorylation level of α-Tm (pα-Tm) was significantly higher in the atria than it was in the ventricles. The sequences of all Tm isoforms were characterized and the sites of post-translational modifications were localized. Clearly, top-down mass spectrometry is an attractive method for comprehensive characterization of Tm isoforms and post-translational modifications since it can universally detect and quantify all types of protein modifications without a priori knowledge and without the need for specific antibodies.
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Peng Y, Chen X, Zhang H, Xu Q, Hacker TA, Ge Y. Top-down targeted proteomics for deep sequencing of tropomyosin isoforms. J Proteome Res 2013; 12:187-98. [PMID: 23256820 PMCID: PMC3596867 DOI: 10.1021/pr301054n] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Tropomyosins (Tm) constitute a family of ubiquitous and highly conserved actin-binding proteins, playing essential roles in a variety of biological processes. Tm isoforms produced by multiple Tm encoding genes and alternatively expressed exons along with post-translational modifications (PTMs) regulate Tm function. Therefore, to gain a better understanding of the functional role of Tm, it is essential to fully characterize Tm isoforms. Herein, we developed a top-down high-resolution mass spectrometry (MS)-based targeted proteomics method for comprehensive characterization of Tm isoforms. α-Tm was identified to be the predominant isoform in swine cardiac muscle. We further characterized its sequence and localized the PTMs such as acetylation and phosphorylation as well as amino acid polymorphisms. Interestingly, we discovered a "novel" Tm isoform that does not match with any of the currently available swine Tm sequences. A deep sequencing of this isoform by top-down MS revealed an exact match with mouse β-Tm sequence, suggesting that this "novel" isoform is swine β-Tm which is 100% conserved between swine and mouse. Taken together, we demonstrated that top-down targeted proteomics provides a powerful tool for deep sequencing of Tm isoforms from genetic variations together with complete mapping of the PTM sites.
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Affiliation(s)
- Ying Peng
- Human Proteomics Program, University of Wisconsin-Madison, Madison, WI, 53706
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, 53706
| | - Xin Chen
- Human Proteomics Program, University of Wisconsin-Madison, Madison, WI, 53706
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, 53706
| | - Han Zhang
- Human Proteomics Program, University of Wisconsin-Madison, Madison, WI, 53706
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706
| | - Qingge Xu
- Human Proteomics Program, University of Wisconsin-Madison, Madison, WI, 53706
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, 53706
| | - Timothy A. Hacker
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53706
| | - Ying Ge
- Human Proteomics Program, University of Wisconsin-Madison, Madison, WI, 53706
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, 53706
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706
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Mamidi R, Mallampalli SL, Wieczorek DF, Chandra M. Identification of two new regions in the N-terminus of cardiac troponin T that have divergent effects on cardiac contractile function. J Physiol 2012. [PMID: 23207592 DOI: 10.1113/jphysiol.2012.243394] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Abstract Cardiac troponin T (cTnT) has a highly acidic extended N-terminus, the physiological role of which remains poorly understood. To decipher the physiological role of this unique region, we deleted specific regions within the N-terminus of mouse cTnT (McTnT) to create McTnT1-44 and McTnT45-74 proteins. Contractile function and dynamic force-length measurements were made after reconstituting the McTnT deletion proteins into detergent-skinned cardiac papillary fibres harvested from non-transgenic mice that expressed α-tropomyosin (Tm). To further understand how the functional effects of the N-terminus of cTnT are modulated by Tm isoforms, McTnT deletion proteins were reconstituted into detergent-skinned cardiac papillary fibres harvested from transgenic mice that expressed both α- and β-Tm. McTnT1-44, but not McTnT45-74, attenuated maximal activation of the thin filament. Myofilament Ca(2+) sensitivity, as measured by pCa50 (-log of [Ca(2+)]free required for half-maximal activation), decreased in McTnT1-44 (α-Tm) fibres. The desensitizing effect of McTnT1-44 on pCa50 was ablated in β-Tm fibres. McTnT45-74 enhanced pCa50 in both α- and β-Tm fibres, with β-Tm having a bigger effect. The Hill coefficient of tension development was significantly attenuated by McTnT45-74, suggesting an effect on thin-filament cooperativity. The rate of cross-bridge (XB) detachment and the strained XB-mediated impact on other XBs were augmented by McTnT1-44 in β-Tm fibres. The magnitude of the length-mediated recruitment of XBs was attenuated by McTnT1-44 in β-Tm fibres. Our data demonstrate that the 1-44 region of McTnT is essential for maximal activation, whereas the cardiac-specific 45-74 region of McTnT is essential for augmenting cooperativity. Moreover, our data show that α- and β-Tm isoforms have divergent effects on McTnT deletion mutant's ability to modulate cardiac thin-filament activation and Ca(2+) sensitivity. Our results not only provide the first explicit evidence for the existence of two distinct functional regions within the N-terminus of cTnT, but also offer mechanistic insights into the divergent physiological roles of these regions in mediating cardiac contractile activation.
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Affiliation(s)
- Ranganath Mamidi
- Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman, WA-99164, USA.
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Loong CKP, Badr MA, Chase PB. Tropomyosin flexural rigidity and single ca(2+) regulatory unit dynamics: implications for cooperative regulation of cardiac muscle contraction and cardiomyocyte hypertrophy. Front Physiol 2012; 3:80. [PMID: 22493584 PMCID: PMC3318232 DOI: 10.3389/fphys.2012.00080] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Accepted: 03/18/2012] [Indexed: 01/04/2023] Open
Abstract
Striated muscle contraction is regulated by dynamic and cooperative interactions among Ca2+, troponin, and tropomyosin on the thin filament. While Ca2+ regulation has been extensively studied, little is known about the dynamics of individual regulatory units and structural changes of individual tropomyosin molecules in relation to their mechanical properties, and how these factors are altered by cardiomyopathy mutations in the Ca2+ regulatory proteins. In this hypothesis paper, we explore how various experimental and analytical approaches could broaden our understanding of the cooperative regulation of cardiac contraction in health and disease.
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Affiliation(s)
- Campion K P Loong
- Department of Biological Science, The Florida State University Tallahassee, FL, USA
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Shchepkin D, Kopylova G, Nikitina L. Study of reciprocal effects of cardiac myosin and tropomyosin isoforms on actin–myosin interaction with in vitro motility assay. Biochem Biophys Res Commun 2011; 415:104-8. [DOI: 10.1016/j.bbrc.2011.10.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Accepted: 10/06/2011] [Indexed: 10/16/2022]
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