1
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Irving M. Functional control of myosin motors in the cardiac cycle. Nat Rev Cardiol 2024:10.1038/s41569-024-01063-5. [PMID: 39030271 DOI: 10.1038/s41569-024-01063-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/02/2024] [Indexed: 07/21/2024]
Abstract
Contraction of the heart is driven by cyclical interactions between myosin and actin filaments powered by ATP hydrolysis. The modular structure of heart muscle and the organ-level synchrony of the heartbeat ensure tight reciprocal coupling between this myosin ATPase cycle and the macroscopic cardiac cycle. The myosin motors respond to the cyclical activation of the actin and myosin filaments to drive the pressure changes that control the inflow and outflow valves of the heart chambers. Opening and closing of the valves in turn switches the myosin motors between roughly isometric and roughly isotonic contraction modes. Peak filament stress in the heart is much smaller than in fully activated skeletal muscle, although the myosin filaments in the two muscle types have the same number of myosin motors. Calculations indicate that only ~5% of the myosin motors in the heart are needed to generate peak systolic pressure, although many more motors are needed to drive ejection. Tight regulation of the number of active motors is essential for the efficient functioning of the healthy heart - this control is commonly disrupted by gene variants associated with inherited heart disease, and its restoration might be a useful end point in the development of novel therapies.
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Affiliation(s)
- Malcolm Irving
- Randall Centre for Cell and Molecular Biophysics and BHF Centre for Research Excellence, King's College London, London, UK.
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2
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Hart CC, Lee YI, Xie J, Gao G, Lin BL, Hammers DW, Sweeney HL. Potential limitations of microdystrophin gene therapy for Duchenne muscular dystrophy. JCI Insight 2024; 9:e165869. [PMID: 38713520 DOI: 10.1172/jci.insight.165869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 05/01/2024] [Indexed: 05/09/2024] Open
Abstract
Clinical trials delivering high doses of adeno-associated viruses (AAVs) expressing truncated dystrophin molecules (microdystrophins) are underway for Duchenne muscular dystrophy (DMD). We examined the efficiency and efficacy of this strategy with 4 microdystrophin constructs (3 in clinical trials and a variant of the largest clinical construct), in a severe mouse model of DMD, using AAV doses comparable with those in clinical trials. We achieved high levels of microdystrophin expression in striated muscles with cardiac expression approximately 10-fold higher than that observed in skeletal muscle. Significant, albeit incomplete, correction of skeletal muscle disease was observed. Surprisingly, a lethal acceleration of cardiac disease occurred with 2 of the microdystrophins. The detrimental cardiac effect appears to be caused by variable competition (dependent on microdystrophin design and expression level) between microdystrophin and utrophin at the cardiomyocyte membrane. There may also be a contribution from an overloading of protein degradation. The significance of these observations for patients currently being treated with AAV-microdystrophin therapies is unclear since the levels of expression being achieved in the DMD hearts are unknown. However, these findings suggest that microdystrophin treatments need to avoid excessively high levels of expression in the heart and that cardiac function should be carefully monitored in these patients.
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Affiliation(s)
- Cora C Hart
- Department of Pharmacology & Therapeutics and
- Myology Institute, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Young Il Lee
- Department of Pharmacology & Therapeutics and
- Myology Institute, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Jun Xie
- Horae Gene Therapy Center, University of Massachusetts Medical School, Worchester, Massachusetts, USA
| | - Guangping Gao
- Horae Gene Therapy Center, University of Massachusetts Medical School, Worchester, Massachusetts, USA
| | - Brian L Lin
- Department of Cell Biology, Neurobiology, and Anatomy & Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - David W Hammers
- Department of Pharmacology & Therapeutics and
- Myology Institute, University of Florida College of Medicine, Gainesville, Florida, USA
| | - H Lee Sweeney
- Department of Pharmacology & Therapeutics and
- Myology Institute, University of Florida College of Medicine, Gainesville, Florida, USA
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3
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Jones TLM, Woulfe KC. Considering impact of age and sex on cardiac cytoskeletal components. Am J Physiol Heart Circ Physiol 2024; 326:H470-H478. [PMID: 38133622 PMCID: PMC11219061 DOI: 10.1152/ajpheart.00619.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 12/08/2023] [Accepted: 12/21/2023] [Indexed: 12/23/2023]
Abstract
The cardiac cytoskeletal components are integral to cardiomyocyte function and are responsible for contraction, sustaining cell structure, and providing scaffolding to direct signaling. Cytoskeletal components have been implicated in cardiac pathology; however, less attention has been paid to age-related modifications of cardiac cytoskeletal components and how these contribute to dysfunction with increased age. Moreover, significant sex differences in cardiac aging have been identified, but we still lack a complete understanding to the mechanisms behind these differences. This review summarizes what is known about how key cardiomyocyte cytoskeletal components are modified because of age, as well as reported sex-specific differences. Thorough consideration of both age and sex as integral players in cytoskeletal function may reveal potential avenues for more personalized therapeutics.
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Affiliation(s)
- Timothy L M Jones
- Division of Cardiology, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States
| | - Kathleen C Woulfe
- Division of Cardiology, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States
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4
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Burnham HV, Cizauskas HE, Barefield DY. Fine tuning contractility: atrial sarcomere function in health and disease. Am J Physiol Heart Circ Physiol 2024; 326:H568-H583. [PMID: 38156887 PMCID: PMC11221815 DOI: 10.1152/ajpheart.00252.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 12/20/2023] [Accepted: 12/21/2023] [Indexed: 01/03/2024]
Abstract
The molecular mechanisms of sarcomere proteins underlie the contractile function of the heart. Although our understanding of the sarcomere has grown tremendously, the focus has been on ventricular sarcomere isoforms due to the critical role of the ventricle in health and disease. However, atrial-specific or -enriched myofilament protein isoforms, as well as isoforms that become expressed in disease, provide insight into ways this complex molecular machine is fine-tuned. Here, we explore how atrial-enriched sarcomere protein composition modulates contractile function to fulfill the physiological requirements of atrial function. We review how atrial dysfunction negatively affects the ventricle and the many cardiovascular diseases that have atrial dysfunction as a comorbidity. We also cover the pathophysiology of mutations in atrial-enriched contractile proteins and how they can cause primary atrial myopathies. Finally, we explore what is known about contractile function in various forms of atrial fibrillation. The differences in atrial function in health and disease underscore the importance of better studying atrial contractility, especially as therapeutics currently in development to modulate cardiac contractility may have different effects on atrial sarcomere function.
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Affiliation(s)
- Hope V Burnham
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, United States
| | - Hannah E Cizauskas
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, United States
| | - David Y Barefield
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, United States
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5
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Kochurova AM, Beldiia EA, Nefedova VV, Ryabkova NS, Yampolskaya DS, Matyushenko AM, Bershitsky SY, Kopylova GV, Shchepkin DV. N-Terminal Fragment of Cardiac Myosin Binding Protein C Modulates Cooperative Mechanisms of Thin Filament Activation in Atria and Ventricles. BIOCHEMISTRY. BIOKHIMIIA 2024; 89:116-129. [PMID: 38467549 DOI: 10.1134/s0006297924010073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 12/09/2023] [Accepted: 12/11/2023] [Indexed: 03/13/2024]
Abstract
Cardiac myosin binding protein C (cMyBP-C) is one of the essential control components of the myosin cross-bridge cycle. The C-terminal part of cMyBP-C is located on the surface of the thick filament, and its N-terminal part interacts with actin, myosin, and tropomyosin, affecting both kinetics of the ATP hydrolysis cycle and lifetime of the cross-bridge, as well as calcium regulation of the actin-myosin interaction, thereby modulating contractile function of myocardium. The role of cMyBP-C in atrial contraction has not been practically studied. We examined effect of the N-terminal C0-C1-m-C2 (C0-C2) fragment of cMyBP-C on actin-myosin interaction using ventricular and atrial myosin in an in vitro motility assay. The C0-C2 fragment of cMyBP-C significantly reduced the maximum sliding velocity of thin filaments on both myosin isoforms and increased the calcium sensitivity of the actin-myosin interaction. The C0-C2 fragment had different effects on the kinetics of ATP and ADP exchange, increasing the affinity of ventricular myosin for ADP and decreasing the affinity of atrial myosin. The effect of the C0-C2 fragment on the activation of the thin filament depended on the myosin isoforms. Atrial myosin activates the thin filament less than ventricular myosin, and the C0-C2 fragment makes these differences in the myosin isoforms more pronounced.
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Affiliation(s)
- Anastasia M Kochurova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Yekaterinburg, 620049, Russia
| | - Evgenia A Beldiia
- Institute of Immunology and Physiology, Russian Academy of Sciences, Yekaterinburg, 620049, Russia
- Ural Federal University, Ekaterinburg, 620002, Russia
| | - Victoria V Nefedova
- Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia
| | - Natalia S Ryabkova
- Department of Biochemistry, Faculty of Biology, Lomonosov Moscow State University, Moscow, 119234, Russia
- HyTest Ltd., Turku, 20520, Finland
| | - Daria S Yampolskaya
- Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia
| | - Alexander M Matyushenko
- Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, 119071, 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
| | - Daniil V Shchepkin
- Institute of Immunology and Physiology, Russian Academy of Sciences, Yekaterinburg, 620049, Russia.
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6
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Patel JR, Park KJ, Bradshaw AS, Phan T, Fitzsimons DP. Cooperative mechanisms underlie differences in myocardial contractile dynamics between large and small mammals. J Gen Physiol 2023; 155:e202213315. [PMID: 37725091 PMCID: PMC10509357 DOI: 10.1085/jgp.202213315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 06/08/2023] [Accepted: 08/29/2023] [Indexed: 09/21/2023] Open
Abstract
Ca2+ binding to troponin C (TnC) and myosin cross-bridge binding to actin act in a synergistic cooperative manner to modulate myocardial contraction and relaxation. The responsiveness of the myocardial thin filament to the activating effects of Ca2+ and myosin cross-bridge binding has been well-characterized in small mammals (e.g., mice). Given the nearly 10-fold difference in resting heart rates and twitch kinetics between small and large mammals, it is unlikely that the cooperative mechanisms underlying thin filament activation are identical in these two species. To test this idea, we measured the Ca2+ dependencies of steady-state force and the rate constant of force redevelopment (ktr) in murine and porcine permeabilized ventricular myocardium. While murine myocardium exhibited a steep activation-dependence of ktr, the activation-dependent profile of ktr was significantly reduced in porcine ventricular myocardium. Further insight was attained by examining force-pCa and ktr-pCa relationships. In the murine myocardium, the pCa50 for ktr was right-shifted compared with the pCa50 for force, meaning that increases in steady-state force occurred well before increases in the rate of force redevelopment were observed. In the porcine myocardium, we observed a tighter coupling of the force-pCa and ktr-pCa relationships, as evidenced by near-maximal rates of force redevelopment at low levels of Ca2+ activation. These results demonstrate that the molecular mechanisms underlying the cooperative activation of force are a dynamic property of the mammalian heart, involving, at least in part, the species- and tissue-specific expression of cardiac myosin heavy chain isoforms.
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Affiliation(s)
- Jitandrakumar R. Patel
- Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Kayla J.V. Park
- Department of Animal, Veterinary, and Food Sciences, College of Agricultural and Life Sciences, University of Idaho, Moscow, ID, USA
| | - Aidan S. Bradshaw
- Department of Animal, Veterinary, and Food Sciences, College of Agricultural and Life Sciences, University of Idaho, Moscow, ID, USA
| | - Tuan Phan
- Institute for Modeling Collaboration and Innovation, University of Idaho, Moscow, ID, USA
| | - Daniel P. Fitzsimons
- Department of Animal, Veterinary, and Food Sciences, College of Agricultural and Life Sciences, University of Idaho, Moscow, ID, USA
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7
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Lisin R, Balakin A, Mukhlynina E, Protsenko Y. Differences in Mechanical, Electrical and Calcium Transient Performance of the Isolated Right Atrial and Ventricular Myocardium of Guinea Pigs at Different Preloads (Lengths). Int J Mol Sci 2023; 24:15524. [PMID: 37958508 PMCID: PMC10650485 DOI: 10.3390/ijms242115524] [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: 09/29/2023] [Revised: 10/19/2023] [Accepted: 10/22/2023] [Indexed: 11/15/2023] Open
Abstract
There are only a few studies devoted to the comparative and simultaneous study of the mechanisms of the length-dependent regulation of atrial and ventricular contractility. Therefore, an isometric force-length protocol was applied to isolated guinea pig right atrial (RA) strips and ventricular (RV) trabeculae, with a simultaneous measurement of force (Frank-Starling mechanism) and Ca2+ transients (CaT) or transmembrane action potentials (AP). Over the entire length-range studied, the duration of isometric contraction, CaT and AP, were shorter in the RA myocardium than in the RV myocardium. The RA myocardium was stiffer than the RV myocardium. With the increasing length of the RA and RV myocardium, the amplitude and duration of isometric contraction and CaT increased, as well as the amplitude and area of the "CaT difference curves" (shown for the first time). However, the rates of the tension development and relaxation decreased. No contribution of AP duration to the heterometric regulation of isometric tension was found in either the RA or RV myocardium of the guinea pig. Changes in the degree of overlap of the contractile proteins of the guinea pig RA and RV myocardium mainly affect CaT kinetics but not AP duration.
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Affiliation(s)
| | - Alexandr Balakin
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 106 Pervomayskaya Str., Yekaterinburg 620049, Russia; (R.L.); (E.M.); (Y.P.)
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8
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Shafaattalab S, Li AY, Jayousi F, Maaref Y, Dababneh S, Hamledari H, Baygi DH, Barszczewski T, Ruprai B, Jannati S, Nagalingam R, Cool AM, Langa P, Chiao M, Roston T, Solaro RJ, Sanatani S, Toepfer C, Lindert S, Lange P, Tibbits GF. Mechanisms of Pathogenicity of Hypertrophic Cardiomyopathy-Associated Troponin T (TNNT2) Variant R278C +/- During Development. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.06.542948. [PMID: 37609317 PMCID: PMC10441323 DOI: 10.1101/2023.06.06.542948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Hypertrophic cardiomyopathy (HCM) is one of the most common heritable cardiovascular diseases and variants of TNNT2 (cardiac troponin T) are linked to increased risk of sudden cardiac arrest despite causing limited hypertrophy. In this study, a TNNT2 variant, R278C+/-, was generated in both human cardiac recombinant/reconstituted thin filaments (hcRTF) and human- induced pluripotent stem cells (hiPSCs) to investigate the mechanisms by which the R278C+/- variant affects cardiomyocytes at the proteomic and functional levels. The results of proteomics analysis showed a significant upregulation of markers of cardiac hypertrophy and remodeling in R278C+/- vs. the isogenic control. Functional measurements showed that R278C+/- variant enhances the myofilament sensitivity to Ca2+, increases the kinetics of contraction, and causes arrhythmia at frequencies >75 bpm. This study uniquely shows the profound impact of the TNNT2 R278C+/- variant on the cardiomyocyte proteomic profile, cardiac electrical and contractile function in the early stages of cardiac development.
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Affiliation(s)
- Sanam Shafaattalab
- Cellular and Regenerative Medicine Centre, BC Children’s Hospital Research Institute, Vancouver, BC, V5Z 4H4, Canada
- Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | - Alison Y Li
- Cellular and Regenerative Medicine Centre, BC Children’s Hospital Research Institute, Vancouver, BC, V5Z 4H4, Canada
- Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | - Farah Jayousi
- Cellular and Regenerative Medicine Centre, BC Children’s Hospital Research Institute, Vancouver, BC, V5Z 4H4, Canada
- Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | - Yasaman Maaref
- Cellular and Regenerative Medicine Centre, BC Children’s Hospital Research Institute, Vancouver, BC, V5Z 4H4, Canada
- Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | - Saif Dababneh
- Cellular and Regenerative Medicine Centre, BC Children’s Hospital Research Institute, Vancouver, BC, V5Z 4H4, Canada
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada
| | - Homa Hamledari
- Cellular and Regenerative Medicine Centre, BC Children’s Hospital Research Institute, Vancouver, BC, V5Z 4H4, Canada
- Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | - Dina Hosseini Baygi
- Cellular and Regenerative Medicine Centre, BC Children’s Hospital Research Institute, Vancouver, BC, V5Z 4H4, Canada
- Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | - Tiffany Barszczewski
- Cellular and Regenerative Medicine Centre, BC Children’s Hospital Research Institute, Vancouver, BC, V5Z 4H4, Canada
- Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | - Balwinder Ruprai
- Cellular and Regenerative Medicine Centre, BC Children’s Hospital Research Institute, Vancouver, BC, V5Z 4H4, Canada
- Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | - Shayan Jannati
- Cellular and Regenerative Medicine Centre, BC Children’s Hospital Research Institute, Vancouver, BC, V5Z 4H4, Canada
- Mechanical Engineering, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Raghu Nagalingam
- Cellular and Regenerative Medicine Centre, BC Children’s Hospital Research Institute, Vancouver, BC, V5Z 4H4, Canada
- Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | - Austin M Cool
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH, USA
| | - Paulina Langa
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, 60612, USA
| | - Mu Chiao
- Mechanical Engineering, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Thomas Roston
- Division of Cardiology and Centre for Cardiovascular Innovation, The University of British Columbia 1081 Burrard Street, Level 4 Cardiology Vancouver, BC, V6Z 1Y6, Canada
| | - R John Solaro
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, 60612, USA
| | - Shubhayan Sanatani
- Cellular and Regenerative Medicine Centre, BC Children’s Hospital Research Institute, Vancouver, BC, V5Z 4H4, Canada
| | | | - Steffen Lindert
- Mechanical Engineering, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Philipp Lange
- Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC
- Michael Cuccione Childhood Cancer Research Program, BC Children’s Hospital Research Institute, Vancouver, BC, V5Z 4H4, Canada
| | - Glen F Tibbits
- Cellular and Regenerative Medicine Centre, BC Children’s Hospital Research Institute, Vancouver, BC, V5Z 4H4, Canada
- Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
- Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
- School of Biomedical Engineering, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada
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9
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Galow AM, Brenmoehl J, Hoeflich A. Synergistic effects of hormones on structural and functional maturation of cardiomyocytes and implications for heart regeneration. Cell Mol Life Sci 2023; 80:240. [PMID: 37541969 PMCID: PMC10403476 DOI: 10.1007/s00018-023-04894-6] [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: 04/04/2023] [Revised: 07/18/2023] [Accepted: 07/22/2023] [Indexed: 08/06/2023]
Abstract
The limited endogenous regenerative capacity of the human heart renders cardiovascular diseases a major health threat, thus motivating intense research on in vitro heart cell generation and cell replacement therapies. However, so far, in vitro-generated cardiomyocytes share a rather fetal phenotype, limiting their utility for drug testing and cell-based heart repair. Various strategies to foster cellular maturation provide some success, but fully matured cardiomyocytes are still to be achieved. Today, several hormones are recognized for their effects on cardiomyocyte proliferation, differentiation, and function. Here, we will discuss how the endocrine system impacts cardiomyocyte maturation. After detailing which features characterize a mature phenotype, we will contemplate hormones most promising to induce such a phenotype, the routes of their action, and experimental evidence for their significance in this process. Due to their pleiotropic effects, hormones might be not only valuable to improve in vitro heart cell generation but also beneficial for in vivo heart regeneration. Accordingly, we will also contemplate how the presented hormones might be exploited for hormone-based regenerative therapies.
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Affiliation(s)
- Anne-Marie Galow
- Institute of Genome Biology, Research Institute for Farm Animal Biology (FBN), 18196, Dummerstorf, Germany.
| | - Julia Brenmoehl
- Institute of Genome Biology, Research Institute for Farm Animal Biology (FBN), 18196, Dummerstorf, Germany
| | - Andreas Hoeflich
- Institute of Genome Biology, Research Institute for Farm Animal Biology (FBN), 18196, Dummerstorf, Germany
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10
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Bayne EF, Rossler KJ, Gregorich ZR, Aballo TJ, Roberts DS, Chapman EA, Guo W, Palecek SP, Ralphe JC, Kamp TJ, Ge Y. Top-down proteomics of myosin light chain isoforms define chamber-specific expression in the human heart. J Mol Cell Cardiol 2023; 181:89-97. [PMID: 37327991 PMCID: PMC10528938 DOI: 10.1016/j.yjmcc.2023.06.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 05/27/2023] [Accepted: 06/13/2023] [Indexed: 06/18/2023]
Abstract
Myosin functions as the "molecular motor" of the sarcomere and generates the contractile force necessary for cardiac muscle contraction. Myosin light chains 1 and 2 (MLC-1 and -2) play important functional roles in regulating the structure of the hexameric myosin molecule. Each of these light chains has an 'atrial' and 'ventricular' isoform, so called because they are believed to exhibit chamber-restricted expression in the heart. However, recently the chamber-specific expression of MLC isoforms in the human heart has been questioned. Herein, we analyzed the expression of MLC-1 and -2 atrial and ventricular isoforms in each of the four cardiac chambers in adult non-failing donor hearts using top-down mass spectrometry (MS)-based proteomics. Strikingly, we detected an isoform thought to be ventricular, MLC-2v (gene: MYL2), in the atria and confirmed the protein sequence using tandem MS (MS/MS). For the first time, a putative deamidation post-translation modification (PTM) located on MLC-2v in atrial tissue was localized to amino acid N13. MLC-1v (MYL3) and MLC-2a (MYL7) were the only MLC isoforms exhibiting chamber-restricted expression patterns across all donor hearts. Importantly, our results unambiguously show that MLC-1v, not MLC-2v, is ventricle-specific in adult human hearts. Moreover, we found elevated MLC-2 phosphorylation in male hearts compared to female hearts across each cardiac chamber. Overall, top-down proteomics allowed an unbiased analysis of MLC isoform expression throughout the human heart, uncovering previously unexpected isoform expression patterns and PTMs.
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Affiliation(s)
- Elizabeth F Bayne
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Kalina J Rossler
- Molecular and Cellular Pharmacology Training Program, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Zachery R Gregorich
- Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Timothy J Aballo
- Molecular and Cellular Pharmacology Training Program, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - David S Roberts
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Emily A Chapman
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Wei Guo
- Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Sean P Palecek
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - J Carter Ralphe
- Department of Pediatrics, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Timothy J Kamp
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Medicine, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Ying Ge
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA; Molecular and Cellular Pharmacology Training Program, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53705, USA; Human Proteomics Program, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, USA.
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11
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Nag S, Gollapudi SK, Del Rio CL, Spudich JA, McDowell R. Mavacamten, a precision medicine for hypertrophic cardiomyopathy: From a motor protein to patients. SCIENCE ADVANCES 2023; 9:eabo7622. [PMID: 37506209 DOI: 10.1126/sciadv.abo7622] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 06/23/2023] [Indexed: 07/30/2023]
Abstract
Hypertrophic cardiomyopathy (HCM) is a primary myocardial disorder characterized by left ventricular hypertrophy, hyperdynamic contraction, and impaired relaxation of the heart. These functional derangements arise directly from altered sarcomeric function due to either mutations in genes encoding sarcomere proteins, or other defects such as abnormal energetics. Current treatment options do not directly address this causal biology but focus on surgical and extra-sarcomeric (sarcolemmal) pharmacological symptomatic relief. Mavacamten (formerly known as MYK-461), is a small molecule designed to regulate cardiac function at the sarcomere level by selectively but reversibly inhibiting the enzymatic activity of myosin, the fundamental motor of the sarcomere. This review summarizes the mechanism and translational progress of mavacamten from proteins to patients, describing how the mechanism of action and pharmacological characteristics, involving both systolic and diastolic effects, can directly target pathophysiological derangements within the cardiac sarcomere to improve cardiac structure and function in HCM. Mavacamten was approved by the Food and Drug Administration in April 2022 for the treatment of obstructive HCM and now goes by the commercial name of Camzyos. Full information about the risks, limitations, and side effects can be found at www.accessdata.fda.gov/drugsatfda_docs/label/2022/214998s000lbl.pdf.
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Affiliation(s)
- Suman Nag
- MyoKardia Inc., a wholly owned subsidiary of Bristol Myers Squibb, Brisbane, CA 94005, USA
| | - Sampath K Gollapudi
- MyoKardia Inc., a wholly owned subsidiary of Bristol Myers Squibb, Brisbane, CA 94005, USA
| | - Carlos L Del Rio
- MyoKardia Inc., a wholly owned subsidiary of Bristol Myers Squibb, Brisbane, CA 94005, USA
- Cardiac Consulting, 1630 S Delaware St. #56426, San Mateo, CA 94403, USA
| | | | - Robert McDowell
- MyoKardia Inc., a wholly owned subsidiary of Bristol Myers Squibb, Brisbane, CA 94005, USA
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12
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Telle Å, Bargellini C, Chahine Y, Del Álamo JC, Akoum N, Boyle PM. Personalized biomechanical insights in atrial fibrillation: opportunities & challenges. Expert Rev Cardiovasc Ther 2023; 21:817-837. [PMID: 37878350 PMCID: PMC10841537 DOI: 10.1080/14779072.2023.2273896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Accepted: 10/18/2023] [Indexed: 10/26/2023]
Abstract
INTRODUCTION Atrial fibrillation (AF) is an increasingly prevalent and significant worldwide health problem. Manifested as an irregular atrial electrophysiological activation, it is associated with many serious health complications. AF affects the biomechanical function of the heart as contraction follows the electrical activation, subsequently leading to reduced blood flow. The underlying mechanisms behind AF are not fully understood, but it is known that AF is highly correlated with the presence of atrial fibrosis, and with a manifold increase in risk of stroke. AREAS COVERED In this review, we focus on biomechanical aspects in atrial fibrillation, current and emerging use of clinical images, and personalized computational models. We also discuss how these can be used to provide patient-specific care. EXPERT OPINION Understanding the connection betweenatrial fibrillation and atrial remodeling might lead to valuable understanding of stroke and heart failure pathophysiology. Established and emerging imaging modalities can bring us closer to this understanding, especially with continued advancements in processing accuracy, reproducibility, and clinical relevance of the associated technologies. Computational models of cardiac electromechanics can be used to glean additional insights on the roles of AF and remodeling in heart function.
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Affiliation(s)
- Åshild Telle
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Clarissa Bargellini
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
| | - Yaacoub Chahine
- Division of Cardiology, University of Washington, Seattle, WA, USA
| | - Juan C Del Álamo
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
- Center for Cardiovascular Biology, University of Washington, Seattle, WA, USA
| | - Nazem Akoum
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Division of Cardiology, University of Washington, Seattle, WA, USA
| | - Patrick M Boyle
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Center for Cardiovascular Biology, University of Washington, Seattle, WA, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
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13
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Manilall A, Mokotedi L, Gunter S, Le Roux R, Fourie S, Flanagan CA, Millen AME. Tumor Necrosis Factor-α Mediates Inflammation-induced Early-Stage Left Ventricular Systolic Dysfunction. J Cardiovasc Pharmacol 2023; 81:411-422. [PMID: 37078863 DOI: 10.1097/fjc.0000000000001428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Accepted: 03/28/2023] [Indexed: 04/21/2023]
Abstract
ABSTRACT Elevated systemic inflammation contributes to pathogenesis of heart failure with preserved ejection fraction (HFpEF), but molecular mechanisms are poorly understood. Although left ventricular (LV) diastolic dysfunction is the main cause of HFpEF, subclinical systolic dysfunction also contributes. We have previously shown that rats with collagen-induced arthritis (CIA) have systemic inflammation, LV diastolic dysfunction, and that increased circulating TNF-α contributes to inflammation-induced HFpEF pathogenesis, but does not mediate LV diastolic dysfunction in CIA rats. Contribution of systemic inflammation to dysfunction of the active process of LV diastolic and systolic function are unknown. In the present study, we used the CIA rat model to investigate the effects of systemic inflammation and TNF-α blockade on systolic function, and mRNA expression of genes involved in active diastolic relaxation and of myosin heavy chain (MyHC) isoforms. Collagen inoculation and TNF-α blockade did not affect LV mRNA expression of genes that mediate active LV diastolic function. Collagen-induced inflammation impaired LV global longitudinal strain ( P = 0.03) and velocity ( P = 0.04). This impairment of systolic function was prevented by TNF-α blockade. Collagen inoculation decreased mRNA expression of α-MyHC ( Myh6, P = 0.03) and increased expression of β-MyHC ( Myh7, P = 0.0002), a marker, which is upregulated in failing hearts. TNF-α blockade prevented this MyHC isoform-switch. These results show that increased circulating TNF-α changes the relative expression of MyHC isoforms, favoring β-MyHC, which may underlie changes in contractile function that impair systolic function. Our results indicate that TNF-α initiates early-stage LV systolic, rather than LV diastolic dysfunction.
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Affiliation(s)
- Ashmeetha Manilall
- School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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14
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Pearce NF, Turner MC, Maddock HL, Kim EJ. Development of a novel low-order model for atrial function and a study of atrial mechano-electric feedback. Comput Biol Med 2023; 159:106697. [PMID: 37087301 DOI: 10.1016/j.compbiomed.2023.106697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 02/01/2023] [Accepted: 02/14/2023] [Indexed: 02/19/2023]
Abstract
Numerical models of the cardiovascular system have largely focused on the function of the ventricles, with atrial function often neglected. Furthermore, the time-varying elastance method that prescribes the pressure-volume relationship rather than calculating it consistently is frequently used for the ventricles and atrium. This method has yet to be validated however, so its applicability for cardiac modelling is frequently questioned. To overcome this challenge, we propose a synergistic model of left atrium (LA) and left ventricle (LV) by self-consistently integrating various feedback mechanisms among the electro-mechanical and chemical functions of the micro-scale myofiber, the macro-scale dynamics of the LA and LV, the atrioventricular node (AV), and circulation. The model is tested and shown to reproduce the essential features of the atrium cycling, such as the characteristic figure of eight pressure-volume loops. Our model is further developed to investigate the effect of dysfunctions of the mechanical-electric feedback (MEF) in the atrium. Our model not only successfully reproduces key experimental MEF observations such as prolonged action-potential and increases in action-potential magnitude induced by atrial stretch but also shows how MEF and arrhythmia of the atrium lead to a degradation of cardiac output and pumping power with significant consequences. In particular, MEF reproduces arrhythmia such as ectopic and erratic cycling, missed heart beats and restricted function.
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Affiliation(s)
- Nicholas F Pearce
- Fluids and Complex Systems Center, Faculty of Engineering, Environment and Computing, Coventry University, Coventry, CV1 5FB, UK.
| | - Mark C Turner
- Centre for Sport, Exercise and Life Sciences, Research Institute for Health and Well-being, Coventry University, Coventry, CV1 5FB, UK
| | - Helen L Maddock
- Centre for Sport, Exercise and Life Sciences, Research Institute for Health and Well-being, Coventry University, Coventry, CV1 5FB, UK
| | - Eun-Jin Kim
- Fluids and Complex Systems Center, Faculty of Engineering, Environment and Computing, Coventry University, Coventry, CV1 5FB, UK
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15
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Lookin O, Balakin A, Protsenko Y. Differences in Effects of Length-Dependent Regulation of Force and Ca 2+ Transient in the Myocardial Trabeculae of the Rat Right Atrium and Ventricle. Int J Mol Sci 2023; 24:ijms24108960. [PMID: 37240302 DOI: 10.3390/ijms24108960] [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: 04/17/2023] [Revised: 05/12/2023] [Accepted: 05/15/2023] [Indexed: 05/28/2023] Open
Abstract
The comparative differences in the fundamental mechanisms of contractility regulation and calcium handling of atrial and ventricular myocardium remain poorly studied. An isometric force-length protocol was performed for the entire range of preloads in isolated rat right atrial (RA) and ventricular (RV) trabeculae with simultaneous measurements of force (Frank-Starling mechanism) and Ca2+ transients (CaT). Differences were found between length-dependent effects in RA and RV muscles: (a) the RA muscles were stiffer, faster, and presented with weaker active force than the RV muscles throughout the preload range; (b) the active/passive force-length relationships were almost linear for the RA and RV muscles; (c) the value of the relative length-dependent growth of passive/active mechanical tension did not differ between the RA and RV muscles; (d) the time-to-peak and amplitude of CaT did not differ between the RA and RV muscles; (e) the CaT decay phase was essentially monotonic and almost independent of preload in the RA muscles, but not in the RV muscles. Higher peak tension, prolonged isometric twitch, and CaT in the RV muscle may be the result of higher Ca2+ buffering by myofilaments. The molecular mechanisms that constitute the Frank-Starling mechanism are common in the rat RA and RV myocardium.
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Affiliation(s)
- Oleg Lookin
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 106 Pervomayskaya Str., 620049 Yekaterinburg, Russia
| | - Alexander Balakin
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 106 Pervomayskaya Str., 620049 Yekaterinburg, Russia
| | - Yuri Protsenko
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 106 Pervomayskaya Str., 620049 Yekaterinburg, Russia
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16
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Kopylova GV, Kochurova AM, Yampolskaya DS, Nefedova VV, Tsaturyan AK, Koubassova NA, Kleymenov SY, Levitsky DI, Bershitsky SY, Matyushenko AM, Shchepkin DV. Structural and Functional Properties of Kappa Tropomyosin. Int J Mol Sci 2023; 24:ijms24098340. [PMID: 37176047 PMCID: PMC10179609 DOI: 10.3390/ijms24098340] [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: 03/27/2023] [Revised: 04/27/2023] [Accepted: 05/04/2023] [Indexed: 05/15/2023] Open
Abstract
In the myocardium, the TPM1 gene expresses two isoforms of tropomyosin (Tpm), alpha (αTpm; Tpm 1.1) and kappa (κTpm; Tpm 1.2). κTpm is the result of alternative splicing of the TPM1 gene. We studied the structural features of κTpm and its regulatory function in the atrial and ventricular myocardium using an in vitro motility assay. We tested the possibility of Tpm heterodimer formation from α- and κ-chains. Our result shows that the formation of ακTpm heterodimer is thermodynamically favorable, and in the myocardium, κTpm most likely exists as ακTpm heterodimer. Using circular dichroism, we compared the thermal unfolding of ααTpm, ακTpm, and κκTpm. κκTpm had the lowest stability, while the ακTpm was more stable than ααTpm. The differential scanning calorimetry results indicated that the thermal stability of the N-terminal part of κκTpm is much lower than that of ααTpm. The affinity of ααTpm and κκTpm to F-actin did not differ, and ακTpm interacted with F-actin significantly worse. The troponin T1 fragment enhanced the κκTpm and ακTpm affinity to F-actin. κκTpm differently affected the calcium regulation of the interaction of pig and rat ventricular myosin with the thin filament. With rat myosin, calcium sensitivity of thin filaments containing κκTpm was significantly lower than that with ααTpm and with pig myosin, and the sensitivity did not differ. Thin filaments containing κκTpm and ακTpm were better activated by pig atrial myosin than those containing ααTpm.
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Affiliation(s)
- Galina V Kopylova
- Institute of Immunology and Physiology, Russian Academy of Sciences, 620049 Yekaterinburg, Russia
| | - Anastasia M Kochurova
- Institute of Immunology and Physiology, Russian Academy of Sciences, 620049 Yekaterinburg, Russia
| | - Daria S Yampolskaya
- Research Center of Biotechnology, Russian Academy of Sciences, 119071 Moscow, Russia
| | - Victoria V Nefedova
- Research Center of Biotechnology, Russian Academy of Sciences, 119071 Moscow, Russia
| | | | | | - Sergey Y Kleymenov
- Research Center of Biotechnology, Russian Academy of Sciences, 119071 Moscow, Russia
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, 119334 Moscow, Russia
| | - Dmitrii I Levitsky
- Research Center of Biotechnology, Russian Academy of Sciences, 119071 Moscow, Russia
| | - Sergey Y Bershitsky
- Institute of Immunology and Physiology, Russian Academy of Sciences, 620049 Yekaterinburg, Russia
| | | | - Daniil V Shchepkin
- Institute of Immunology and Physiology, Russian Academy of Sciences, 620049 Yekaterinburg, Russia
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17
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Dozic S, Howden EJ, Bell JR, Mellor KM, Delbridge LMD, Weeks KL. Cellular Mechanisms Mediating Exercise-Induced Protection against Cardiotoxic Anthracycline Cancer Therapy. Cells 2023; 12:cells12091312. [PMID: 37174712 PMCID: PMC10177216 DOI: 10.3390/cells12091312] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 04/25/2023] [Accepted: 04/27/2023] [Indexed: 05/15/2023] Open
Abstract
Anthracyclines such as doxorubicin are widely used chemotherapy drugs. A common side effect of anthracycline therapy is cardiotoxicity, which can compromise heart function and lead to dilated cardiomyopathy and heart failure. Dexrazoxane and heart failure medications (i.e., beta blockers and drugs targeting the renin-angiotensin system) are prescribed for the primary prevention of cancer therapy-related cardiotoxicity and for the management of cardiac dysfunction and symptoms if they arise during chemotherapy. However, there is a clear need for new therapies to combat the cardiotoxic effects of cancer drugs. Exercise is a cardioprotective stimulus that has recently been shown to improve heart function and prevent functional disability in breast cancer patients undergoing anthracycline chemotherapy. Evidence from preclinical studies supports the use of exercise training to prevent or attenuate the damaging effects of anthracyclines on the cardiovascular system. In this review, we summarise findings from experimental models which provide insight into cellular mechanisms by which exercise may protect the heart from anthracycline-mediated damage, and identify knowledge gaps that require further investigation. Improved understanding of the mechanisms by which exercise protects the heart from anthracyclines may lead to the development of novel therapies to treat cancer therapy-related cardiotoxicity.
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Affiliation(s)
- Sanela Dozic
- Central Clinical School, Monash University, Melbourne, VIC 3004, Australia
| | - Erin J Howden
- Central Clinical School, Monash University, Melbourne, VIC 3004, Australia
- Baker Heart and Diabetes Institute, Melbourne, VIC 3004, Australia
- Department of Cardiometabolic Health, The University of Melbourne, Parkville, VIC 3010, Australia
| | - James R Bell
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, VIC 3010, Australia
- Department of Microbiology, Anatomy, Physiology & Pharmacology, La Trobe University, Bundoora, VIC 3086, Australia
| | - Kimberley M Mellor
- Department of Physiology, University of Auckland, Auckland 1023, New Zealand
| | - Lea M D Delbridge
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Kate L Weeks
- Central Clinical School, Monash University, Melbourne, VIC 3004, Australia
- Department of Cardiometabolic Health, The University of Melbourne, Parkville, VIC 3010, Australia
- Department of Anatomy & Physiology, The University of Melbourne, Parkville, VIC 3010, Australia
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18
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Mashali MA, Saad NS, Peczkowski KK, Fanning T, Hare AN, Whitson BA, Mokadam NA, Janssen PM. Mechanical Dyssynchrony of Isolated Left and Right Ventricular Human Myocardium in End-Stage Heart Failure. Circ Heart Fail 2023; 16:e009871. [PMID: 36695183 PMCID: PMC10033321 DOI: 10.1161/circheartfailure.122.009871] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 11/15/2022] [Indexed: 01/26/2023]
Abstract
BACKGROUND The left and right ventricles of the human heart differ in embryology, shape, thickness, and function. Ventricular dyssynchrony often occurs in cases of heart failure. Our objectives were to assess whether differences in contractile properties exist between the left and right ventricles and to evaluate signs of left/right ventricular mechanical synchrony in isolated healthy and diseased human myocardium. METHODS Myocardial left and right ventricular trabeculae were dissected from nonfailing and end-stage failing human hearts. Baseline contractile force and contraction/relaxation kinetics of the left ventricle were compared to those of the right ventricle in the nonfailing group (n=41) and in the failing group (n=29). Correlation analysis was performed to assess the mechanical synchrony between left and right ventricular myocardium isolated from the same heart, in nonfailing (n=41) and failing hearts (n=29). RESULTS The failing right ventricular myocardium showed significantly higher developed force (Fdev; P=0.001; d=0.98), prolonged time to peak (P<0.001; d=1.14), and higher rate of force development (P=0.002; d=0.89) and force decline (P=0.003; d=0.82) compared to corresponding left ventricular myocardium. In healthy myocardium, a strong positive relationship was present between the left and right ventricles in time to peak (r=0.58, P<0.001) and maximal kinetic rate of contraction (r=0.63, P<0.001). These coefficients were much weaker, often nearly absent, in failing myocardium. CONCLUSIONS At the level of isolated cardiac trabeculae, contractile performance, specifically of contractile kinetics, is correlated in the nonfailing myocardium between the left and right ventricles' but this correlation is significantly weaker, or even absent, in end-stage heart failure, suggesting an interventricular mechanical dyssynchrony.
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Affiliation(s)
- Mohammed A. Mashali
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, United States
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States
| | - Nancy S. Saad
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, United States
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States
| | - Kyra K. Peczkowski
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, United States
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States
| | - Tom Fanning
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, United States
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States
| | - Austin N. Hare
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, United States
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States
| | - Bryan A. Whitson
- Division of Cardiac Surgery, College of Medicine, The Ohio State University, Columbus, OH, United States
| | - Nahush A. Mokadam
- Division of Cardiac Surgery, College of Medicine, The Ohio State University, Columbus, OH, United States
| | - Paul M.L. Janssen
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, United States
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States
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19
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Bayne EF, Rossler KJ, Gregorich ZR, Aballo TJ, Roberts DS, Chapman EA, Guo W, Ralphe JC, Kamp TJ, Ge Y. Top-down Proteomics of Myosin Light Chain Isoforms Define Chamber-Specific Expression in the Human Heart. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.26.525767. [PMID: 36747670 PMCID: PMC9900887 DOI: 10.1101/2023.01.26.525767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Myosin functions as the "molecular motor" of the sarcomere and generates the contractile force necessary for cardiac muscle contraction. Myosin light chains 1 and 2 (MLC-1 and -2) play important functional roles in regulating the structure of the hexameric myosin molecule. Each of these light chains has an "atrial" and "ventricular" isoform, so called because they are believed to exhibit chamber-restricted expression in the heart. However, recently the chamber-specific expression of MLC isoforms in the human heart has been questioned. Herein, we analyzed the expression of MLC-1 and -2 atrial and ventricular isoforms in each of the four cardiac chambers in adult non-failing donor hearts using top-down mass spectrometry (MS)-based proteomics. Strikingly, we detected an isoform thought to be ventricular, MLC-2v, in the atria and confirmed the protein sequence using tandem MS (MS/MS). For the first time, a putative deamidation post-translation modification (PTM) located on MLC-2v in atrial tissue was localized to amino acid N13. MLC-1v and MLC-2a were the only MLC isoforms exhibiting chamber-restricted expression patterns across all donor hearts. Importantly, our results unambiguously show that MLC-1v, not MLC-2v, is ventricle-specific in adult human hearts. Overall, top-down proteomics allowed us an unbiased analysis of MLC isoform expression throughout the human heart, uncovering previously unexpected isoform expression patterns and PTMs.
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20
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Yampolskaya DS, Kopylova GV, Shchepkin DV, Nabiev SR, Nikitina LV, Walklate J, Ziganshin RH, Bershitsky SY, Geeves MA, Matyushenko AM, Levitsky DI. Pseudo-phosphorylation of essential light chains affects the functioning of skeletal muscle myosin. Biophys Chem 2023; 292:106936. [PMID: 36436358 DOI: 10.1016/j.bpc.2022.106936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 11/10/2022] [Accepted: 11/18/2022] [Indexed: 11/21/2022]
Abstract
The work aimed to investigate how the phosphorylation of the myosin essential light chain of fast skeletal myosin (LC1) affects the functional properties of the myosin molecule. Using mass-spectrometry, we revealed phosphorylated peptides of LC1 in myosin from different fast skeletal muscles. Mutations S193D and T65D that mimic natural phosphorylation of LC1 were produced, and their effects on functional properties of the entire myosin molecule and isolated myosin head (S1) were studied. We have shown that T65D mutation drastically decreased the sliding velocity of thin filaments in an in vitro motility assay and strongly increased the duration of actin-myosin interaction in optical trap experiments. These effects of T65D mutation in LC1 observed only with the whole myosin but not with S1 were prevented by double T65D/S193D mutation. The T65D and T65D/S193D mutations increased actin-activated ATPase activity of S1 and decreased ADP affinity for the actin-S1 complex. The results indicate that pseudo-phosphorylation of LC1 differently affects the properties of the whole myosin molecule and its isolated head. Also, the results show that phosphorylation of LC1 of skeletal myosin could be one more mechanism of regulation of actin-myosin interaction that needs further investigation.
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Affiliation(s)
- Daria S Yampolskaya
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky prosp. 33, Moscow 119071, Russia
| | - Galina V Kopylova
- Institute of Immunology and Physiology of the Russian Academy of Sciences, Yekaterinburg 620049, Russia
| | - Daniil V Shchepkin
- Institute of Immunology and Physiology of the Russian Academy of Sciences, Yekaterinburg 620049, Russia
| | - Salavat R Nabiev
- Institute of Immunology and Physiology of the Russian Academy of Sciences, Yekaterinburg 620049, Russia
| | - Larisa V Nikitina
- Institute of Immunology and Physiology of the Russian Academy of Sciences, Yekaterinburg 620049, Russia
| | - Jonathan Walklate
- School of Biosciences, University of Kent, Canterbury CT2 7NJ, United Kingdom
| | - Rustam H Ziganshin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, Moscow 117997, Russia
| | - Sergey Y Bershitsky
- Institute of Immunology and Physiology of the Russian Academy of Sciences, Yekaterinburg 620049, Russia
| | - Michael A Geeves
- School of Biosciences, University of Kent, Canterbury CT2 7NJ, United Kingdom
| | - Alexander M Matyushenko
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky prosp. 33, Moscow 119071, Russia
| | - Dmitrii I Levitsky
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky prosp. 33, Moscow 119071, Russia.
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21
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Gerzen OP, Nabiev SR, Klinova SV, Minigalieva IA, Sutunkova MP, Katsnelson BA, Nikitina LV. Molecular mechanisms of mechanical function changes of the rat myocardium under subchronic lead exposure. Food Chem Toxicol 2022; 169:113444. [PMID: 36179994 DOI: 10.1016/j.fct.2022.113444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 09/10/2022] [Accepted: 09/21/2022] [Indexed: 11/26/2022]
Abstract
A moderate degree of lead intoxication was observed in male rats after repeated intraperitoneal injections with two doses of lead acetate three times a week during 5 (12.5 mg of Pb per kg body mass) and 6 (6.01 mg of Pb per kg body mass) weeks. Using an in vitro motility assay, we investigated the impact of this intoxication on the characteristics of actin-myosin interaction and its regulation in the atria, right, and left ventricles. Both lead doses exposure decreased the maximum sliding velocity of reconstituted thin filaments over myosin and fraction of motile filaments in all heart chambers, caused the myosin isoforms shift towards slower β-myosin heavy chains in ventricles and decreased regulatory light chain phosphorylation in atria. No statistically significant difference was found in force and calcium regulation of actin-myosin interaction. A dose-dependent effect of lead on myosin functional characteristics was found in all heart chambers, but the degree of this effect varied depending on the heart chamber.
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Affiliation(s)
- Oksana P Gerzen
- Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia.
| | - Salavat R Nabiev
- Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia
| | - Svetlana V Klinova
- Yekaterinburg Medical Research Center for Prophylaxis and Health Protection in Industrial Workers, Ekaterinburg, Russia
| | - Ilzira A Minigalieva
- Yekaterinburg Medical Research Center for Prophylaxis and Health Protection in Industrial Workers, Ekaterinburg, Russia
| | - Marina P Sutunkova
- Yekaterinburg Medical Research Center for Prophylaxis and Health Protection in Industrial Workers, Ekaterinburg, Russia
| | - Boris A Katsnelson
- Yekaterinburg Medical Research Center for Prophylaxis and Health Protection in Industrial Workers, Ekaterinburg, Russia
| | - Larisa V Nikitina
- Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia
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22
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Yang Y, Fu Z, Zhu W, Hu H, Wang J. Application of optical tweezers in cardiovascular research: More than just a measuring tool. Front Bioeng Biotechnol 2022; 10:947918. [PMID: 36147537 PMCID: PMC9486066 DOI: 10.3389/fbioe.2022.947918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 08/12/2022] [Indexed: 12/04/2022] Open
Abstract
Recent advances in the field of optical tweezer technology have shown intriguing potential for applications in cardiovascular medicine, bringing this laboratory nanomechanical instrument into the spotlight of translational medicine. This article summarizes cardiovascular system findings generated using optical tweezers, including not only rigorous nanomechanical measurements but also multifunctional manipulation of biologically active molecules such as myosin and actin, of cells such as red blood cells and cardiomyocytes, of subcellular organelles, and of microvessels in vivo. The implications of these findings in the diagnosis and treatment of diseases, as well as potential perspectives that could also benefit from this tool, are also discussed.
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Affiliation(s)
- Yi Yang
- Department of Cardiology, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
- Cardiovascular Key Laboratory of Zhejiang Province, Hangzhou, China
| | - Zhenhai Fu
- Quantum Sensing Center, Zhejiang Lab, Hangzhou, China
| | - Wei Zhu
- Department of Cardiology, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
- Cardiovascular Key Laboratory of Zhejiang Province, Hangzhou, China
- *Correspondence: Wei Zhu, ; Huizhu Hu, ; Jian’an Wang,
| | - Huizhu Hu
- Quantum Sensing Center, Zhejiang Lab, Hangzhou, China
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, China
- *Correspondence: Wei Zhu, ; Huizhu Hu, ; Jian’an Wang,
| | - Jian’an Wang
- Department of Cardiology, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
- Cardiovascular Key Laboratory of Zhejiang Province, Hangzhou, China
- *Correspondence: Wei Zhu, ; Huizhu Hu, ; Jian’an Wang,
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23
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Nakanishi T, Oyama K, Tanaka H, Kobirumaki-Shimozawa F, Ishii S, Terui T, Ishiwata S, Fukuda N. Effects of omecamtiv mecarbil on the contractile properties of skinned porcine left atrial and ventricular muscles. Front Physiol 2022; 13:947206. [PMID: 36082222 PMCID: PMC9445838 DOI: 10.3389/fphys.2022.947206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 07/04/2022] [Indexed: 11/13/2022] Open
Abstract
Omecamtiv mecarbil (OM) is a novel inotropic agent for heart failure with systolic dysfunction. OM prolongs the actomyosin attachment duration, which enhances thin filament cooperative activation and accordingly promotes the binding of neighboring myosin to actin. In the present study, we investigated the effects of OM on the steady-state contractile properties in skinned porcine left ventricular (PLV) and atrial (PLA) muscles. OM increased Ca2+ sensitivity in a concentration-dependent manner in PLV, by left shifting the mid-point (pCa50) of the force-pCa curve (ΔpCa50) by ∼0.16 and ∼0.33 pCa units at 0.5 and 1.0 μM, respectively. The Ca2+-sensitizing effect was likewise observed in PLA, but less pronounced with ΔpCa50 values of ∼0.08 and ∼0.22 pCa units at 0.5 and 1.0 μM, respectively. The Ca2+-sensitizing effect of OM (1.0 μM) was attenuated under enhanced thin filament cooperative activation in both PLV and PLA; this attenuation occurred directly via treatment with fast skeletal troponin (ΔpCa50: ∼0.16 and ∼0.10 pCa units in PLV and PLA, respectively) and indirectly by increasing the number of strongly bound cross-bridges in the presence of 3 mM MgADP (ΔpCa50: ∼0.21 and ∼0.08 pCa units in PLV and PLA, respectively). It is likely that this attenuation of the Ca2+-sensitizing effect of OM is due to a decrease in the number of “recruitable” cross-bridges that can potentially produce active force. When cross-bridge detachment was accelerated in the presence of 20 mM inorganic phosphate, the Ca2+-sensitizing effect of OM (1.0 μM) was markedly decreased in both types of preparations (ΔpCa50: ∼0.09 and ∼0.03 pCa units in PLV and PLA, respectively). The present findings suggest that the positive inotropy of OM is more markedly exerted in the ventricle than in the atrium, which results from the strongly bound cross-bridge-dependent allosteric activation of thin filaments.
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Affiliation(s)
- Tomohiro Nakanishi
- Department of Cell Physiology, The Jikei University School of Medicine, Tokyo, Japan
- Department of Anesthesiology, The Jikei University School of Medicine, Tokyo, Japan
| | - Kotaro Oyama
- Department of Cell Physiology, The Jikei University School of Medicine, Tokyo, Japan
- Quantum Beam Science Research Directorate, National Institutes for Quantum Science and Technology, Gunma, Japan
| | - Hiroyuki Tanaka
- Laboratory of Marine Biotechnology and Microbiology, Hokkaido University, Hakodate, Japan
| | | | - Shuya Ishii
- Quantum Beam Science Research Directorate, National Institutes for Quantum Science and Technology, Gunma, Japan
| | - Takako Terui
- Department of Anesthesiology, The Jikei University School of Medicine, Tokyo, Japan
| | - Shin’ichi Ishiwata
- Department of Physics, Faculty of Science and Engineering, Waseda University, Tokyo, Japan
| | - Norio Fukuda
- Department of Cell Physiology, The Jikei University School of Medicine, Tokyo, Japan
- *Correspondence: Norio Fukuda,
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24
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Abramochkin DV, Filatova TS, Pustovit KB, Voronina YA, Kuzmin VS, Vornanen M. Ionic currents underlying different patterns of electrical activity in working cardiac myocytes of mammals and non-mammalian vertebrates. Comp Biochem Physiol A Mol Integr Physiol 2022; 268:111204. [PMID: 35346823 DOI: 10.1016/j.cbpa.2022.111204] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 03/21/2022] [Accepted: 03/22/2022] [Indexed: 12/19/2022]
Abstract
The orderly contraction of the vertebrate heart is determined by generation and propagation of cardiac action potentials (APs). APs are generated by the integrated activity of time- and voltage-dependent ionic channels which carry inward Na+ and Ca2+ currents, and outward K+ currents. This review compares atrial and ventricular APs and underlying ion currents between different taxa of vertebrates. We have collected literature data and attempted to find common electrophysiological features for two or more vertebrate groups, show differences between taxa and cardiac chambers, and indicate gaps in the existing data. Although electrical excitability of the heart in all vertebrates is based on the same superfamily of channels, there is a vast variability of AP waveforms between atrial and ventricular myocytes, between different species of the same vertebrate class and between endothermic and ectothermic animals. The wide variability of AP shapes is related to species-specific differences in animal size, heart rate, stage of ontogenetic development, excitation-contraction coupling, temperature and oxygen availability. Some of the differences between taxa are related to evolutionary development of genomes, which appear e.g. in the expression of different Na+ and K+ channel orthologues in cardiomyocytes of vertebrates. There is a wonderful variability of AP shapes and underlying ion currents with which electrical excitability of vertebrate heart can be generated depending on the intrinsic and extrinsic conditions of animal body. This multitude of ionic mechanisms provides excellent material for studying how the function of the vertebrate heart can adapt or acclimate to prevailing physiological and environmental conditions.
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Affiliation(s)
- Denis V Abramochkin
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia.
| | - Tatiana S Filatova
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia
| | - Ksenia B Pustovit
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia
| | - Yana A Voronina
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia; Laboratory of Cardiac Electrophysiology, National Medical Research Center for Cardiology, 3(rd) Cherepkovskaya str., 15A, Moscow, Russia
| | - Vladislav S Kuzmin
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia; Department of Physiology, Pirogov Russian National Research Medical University, Ostrovityanova str., 1, Moscow, Russia
| | - Matti Vornanen
- Department of Environmental and Biological Sciences, University of Eastern Finland, Joensuu, Finland
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25
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Pioner JM, Vitale G, Gentile F, Scellini B, Piroddi N, Cerbai E, Olivotto I, Tardiff J, Coppini R, Tesi C, Poggesi C, Ferrantini C. Genotype-Driven Pathogenesis of Atrial Fibrillation in Hypertrophic Cardiomyopathy: The Case of Different TNNT2 Mutations. Front Physiol 2022; 13:864547. [PMID: 35514357 PMCID: PMC9062294 DOI: 10.3389/fphys.2022.864547] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 03/28/2022] [Indexed: 11/25/2022] Open
Abstract
Atrial dilation and atrial fibrillation (AF) are common in Hypertrophic CardioMyopathy (HCM) patients and associated with a worsening of prognosis. The pathogenesis of atrial myopathy in HCM remains poorly investigated and no specific association with genotype has been identified. By re-analysis of our cohort of thin-filament HCM patients (Coppini et al. 2014) AF was identified in 10% of patients with sporadic mutations in the cardiac Troponin T gene (TNNT2), while AF occurrence was much higher (25-75%) in patients carrying specific "hot-spot" TNNT2 mutations. To determine the molecular basis of arrhythmia occurrence, two HCM mouse models expressing human TNNT2 variants (a "hot-spot" one, R92Q, and a "sporadic" one, E163R) were selected according to the different pathophysiological pathways previously demonstrated in ventricular tissue. Echocardiography studies showed a significant left atrial dilation in both models, but more pronounced in the R92Q. In E163R atrial trabeculae, in line with what previously observed in ventricular preparations, the energy cost of tension generation was markedly increased. However, no changes of twitch amplitude and kinetics were observed, and there was no atrial arrhythmic propensity. R92Q atrial trabeculae, instead, displayed normal ATP consumption but markedly increased myofilament calcium sensitivity, as previously observed in ventricular preparations. This was associated with reduced inotropic reserve and slower kinetics of twitch contractions and, importantly, with an increased occurrence of spontaneous beats and triggered contractions that represent an intrinsic arrhythmogenic mechanism promoting AF. The association of specific TNNT2 mutations with AF occurrence depends on the mutation-driven pathomechanism (i.e., increased atrial myofilament calcium sensitivity rather than increased myofilament tension cost) and may influence the individual response to treatment.
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Affiliation(s)
| | - Giulia Vitale
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Francesca Gentile
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Beatrice Scellini
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Nicoletta Piroddi
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | | | - Iacopo Olivotto
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Jil Tardiff
- Department of Medicine and Biomedical Engineering, University of Arizona, Tucson, AZ, United States
| | | | - Chiara Tesi
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Corrado Poggesi
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Cecilia Ferrantini
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
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26
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Contractile Behavior of Right Atrial Myocardium of Healthy Rats and Rats with the Experimental Model of Pulmonary Hypertension. Int J Mol Sci 2022; 23:ijms23084186. [PMID: 35457003 PMCID: PMC9029478 DOI: 10.3390/ijms23084186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 03/30/2022] [Accepted: 04/08/2022] [Indexed: 01/27/2023] Open
Abstract
There is a lack of data about the contractile behavior of the right atrial myocardium in chronic pulmonary heart disease. We thoroughly characterized the contractility and Ca transient of isolated right atrial strips of healthy rats (CONT) and rats with the experimental model of monocrotaline-induced pulmonary hypertension (MCT) in steady state at different preloads (isometric force-length), during slow force response to stretch (SFR), and during post-rest potentiation after a period of absence of electrical stimulation (PRP). The preload-dependent changes in the isometric twitch and Ca transient did not differ between CONT and MCT rats while the kinetics of the twitch and Ca transient were noticeably slowed down in the MCT rats. The magnitude of SFR was significantly elevated in the MCT right atrial strips and this was accompanied by the significantly higher elevation of the Ca transient relative amplitude at the end of SFR. The slow changes in the contractility and Ca transient in the PRP protocol did not differ between CONT and MCT. In conclusion, the alterations in the contractility and Ca transient of the right atrial myocardium of monocrotaline-treated rats with pulmonary hypertension mostly concern the elevation in SFR. We hypothesize that this positive inotropic effect in the atrial myocardium may (partly) compensate the systolic deficiency of the right ventricular failing myocardium.
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27
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Prodanovic M, Geeves MA, Poggesi C, Regnier M, Mijailovich SM. Effect of Myosin Isoforms on Cardiac Muscle Twitch of Mice, Rats and Humans. Int J Mol Sci 2022; 23:1135. [PMID: 35163054 PMCID: PMC8835009 DOI: 10.3390/ijms23031135] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 01/16/2022] [Accepted: 01/18/2022] [Indexed: 02/04/2023] Open
Abstract
To understand how pathology-induced changes in contractile protein isoforms modulate cardiac muscle function, it is necessary to quantify the temporal-mechanical properties of contractions that occur under various conditions. Pathological responses are much easier to study in animal model systems than in humans, but extrapolation between species presents numerous challenges. Employing computational approaches can help elucidate relationships that are difficult to test experimentally by translating the observations from rats and mice, as model organisms, to the human heart. Here, we use the spatially explicit MUSICO platform to model twitch contractions from rodent and human trabeculae collected in a single laboratory. This approach allowed us to identify the variations in kinetic characteristics of α- and β-myosin isoforms across species and to quantify their effect on cardiac muscle contractile responses. The simulations showed how the twitch transient varied with the ratio of the two myosin isoforms. Particularly, the rate of tension rise was proportional to the fraction of α-myosin present, while the β-isoform dominated the rate of relaxation unless α-myosin was >50%. Moreover, both the myosin isoform and the Ca2+ transient contributed to the twitch tension transient, allowing two levels of regulation of twitch contraction.
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Affiliation(s)
- Momcilo Prodanovic
- Institute for Information Technologies, University of Kragujevac, 34000 Kragujevac, Serbia;
- Bioengineering Research and Development Center (BioIRC), 34000 Kragujevac, Serbia
- FilamenTech, Inc., Newtown, MA 02458, USA
| | - Michael A. Geeves
- Department of Biosciences, University of Kent, Canterbury CT2 7NJ, Kent, UK;
| | - Corrado Poggesi
- Department of Experimental & Clinical Medicine, University of Florence, 20134 Florence, Italy;
| | - Michael Regnier
- Department of Bioengineering, University of Washington, Seattle, WA 98105, USA;
| | - Srboljub M. Mijailovich
- FilamenTech, Inc., Newtown, MA 02458, USA
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
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