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Ye Z, Okamoto R, Ito H, Ito R, Moriwaki K, Ichikawa M, Kimena L, Ali Y, Ito M, Gomez‐Sanchez CE, Dohi K. Myosin Light Chain Phosphatase Plays an Important Role in Cardiac Fibrosis in a Model of Mineralocorticoid Receptor-Associated Hypertension. J Am Heart Assoc 2024; 13:e032828. [PMID: 38420846 PMCID: PMC10944028 DOI: 10.1161/jaha.123.032828] [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: 09/26/2023] [Accepted: 01/24/2024] [Indexed: 03/02/2024]
Abstract
BACKGROUND Myosin phosphatase targeting subunit 2 (MYPT2) is an important subunit of cardiac MLC (myosin light chain) phosphatase, which plays a crucial role in regulating the phosphorylation of MLC to phospho-MLC (p-MLC). A recent study demonstrated mineralocorticoid receptor-related hypertension is associated with RhoA/Rho-associated kinase/MYPT1 signaling upregulation in smooth muscle cells. Our purpose is to investigate the effect of MYPT2 on cardiac function and fibrosis in mineralocorticoid receptor-related hypertension. METHODS AND RESULTS HL-1 murine cardiomyocytes were incubated with different concentrations or durations of aldosterone. After 24-hour stimulation, aldosterone increased CTGF (connective tissue growth factor) and MYPT2 and decreased p-MLC in a dose-dependent manner. MYPT2 knockdown decreased CTGF. Cardiac-specific MYPT2-knockout (c-MYPT2-/-) mice exhibited decreased type 1 phosphatase catalytic subunit β and increased p-MLC. A disease model of mouse was induced by subcutaneous aldosterone and 8% NaCl food for 4 weeks after uninephrectomy. Blood pressure elevation and left ventricular hypertrophy were observed in both c-MYPT2-/- and MYPT2+/+ mice, with no difference in heart weights or nuclear localization of mineralocorticoid receptor in cardiomyocytes. However, c-MYPT2-/- mice had higher ejection fraction and fractional shortening on echocardiography after aldosterone treatment. Histopathology revealed less fibrosis, reduced CTGF, and increased p-MLC in c-MYPT2-/- mice. Basal global radial strain and global longitudinal strain were higher in c-MYPT2-/- than in MYPT2+/+ mice. After aldosterone treatment, both global radial strain and global longitudinal strain remained higher in c-MYPT2-/- mice compared with MYPT2+/+ mice. CONCLUSIONS Cardiac-specific MYPT2 knockout leads to decreased myosin light chain phosphatase and increased p-MLC. MYPT2 deletion prevented cardiac fibrosis and dysfunction in a model of mineralocorticoid receptor-associated hypertension.
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Affiliation(s)
- Zhe Ye
- Department of Cardiology and NephrologyMie University Graduate School of MedicineTsuMieJapan
| | - Ryuji Okamoto
- Department of Cardiology and NephrologyMie University Graduate School of MedicineTsuMieJapan
- Regional Medical Support CenterMie University HospitalTsuMieJapan
- Department of Clinical Training and Career Support CenterMie University HospitalTsuMieJapan
| | - Hiromasa Ito
- Department of Cardiology and NephrologyMie University Graduate School of MedicineTsuMieJapan
| | - Rie Ito
- Department of Cardiology and NephrologyMie University Graduate School of MedicineTsuMieJapan
| | - Keishi Moriwaki
- Department of Cardiology and NephrologyMie University Graduate School of MedicineTsuMieJapan
| | - Mizuki Ichikawa
- Department of Cardiology and NephrologyMie University Graduate School of MedicineTsuMieJapan
| | - Lupiya Kimena
- Department of Cardiology and NephrologyMie University Graduate School of MedicineTsuMieJapan
| | - Yusuf Ali
- Department of Pharmacology and ToxicologyUniversity of Mississippi Medical CenterJacksonMS
| | - Masaaki Ito
- Department of Cardiology and NephrologyMie University Graduate School of MedicineTsuMieJapan
| | - Celso E. Gomez‐Sanchez
- Department of Pharmacology and ToxicologyUniversity of Mississippi Medical CenterJacksonMS
| | - Kaoru Dohi
- Department of Cardiology and NephrologyMie University Graduate School of MedicineTsuMieJapan
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Shen C, Ding X, Ruan J, Ruan F, Hu W, Huang J, He C, Yu Y, Zuo Z. Black phosphorus quantum dots induce myocardial inflammatory responses and metabolic disorders in mice. J Environ Sci (China) 2024; 137:53-64. [PMID: 37980037 DOI: 10.1016/j.jes.2023.01.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 12/30/2022] [Accepted: 01/03/2023] [Indexed: 11/20/2023]
Abstract
As an ultrasmall derivative of black phosphorus (BP) sheets, BP quantum dots (BP-QDs) have been effectively used in many fields. Currently, information on the cardiotoxicity induced by BP-QDs remains limited. We aimed to evaluate BP-QD-induced cardiac toxicity in mice. Histopathological examination of heart tissue sections was performed. Transcriptome sequencing, real-time quantitative PCR (RT‒qPCR), western blotting, and enzyme-linked immunosorbent assay (ELISA) assays were used to detect the mRNA and/or protein expression of proinflammatory cytokines, nuclear factor kappa B (NF-κB), phosphatidylinositol 3 kinase-protein kinase B (PI3K-AKT), peroxisome proliferator-activated receptor gamma (PPARγ), and glucose/lipid metabolism pathway-related genes. We found that heart weight and heart/body weight index (HBI) were significantly reduced in mice after intragastric administration of 0.1 or 1 mg/kg BP-QDs for 28 days. In addition, obvious inflammatory cell infiltration and increased cardiomyocyte diameter were observed in the BP-QD-treated groups. Altered expression of proinflammatory cytokines and genes related to the NF-κB signaling pathway further confirmed that BP-QD exposure induced inflammatory responses. In addition, BP-QD treatment also affected the PI3K-AKT, PPARγ, thermogenesis, oxidative phosphorylation, and cardiac muscle contraction signaling pathways. The expression of genes related to glucose/lipid metabolism signaling pathways was dramatically affected by BP-QD exposure, and the effect was primarily mediated by the PPAR signaling pathway. Our study provides new insights into the toxicity of BP-QDs to human health.
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Affiliation(s)
- Chao Shen
- Department of Nephrology, State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Fujian Clinical Research Center for Chronic Glomerular Disease, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Xiaoyan Ding
- Department of Nephrology, State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Fujian Clinical Research Center for Chronic Glomerular Disease, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Jinpeng Ruan
- Department of Nephrology, State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Fujian Clinical Research Center for Chronic Glomerular Disease, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Fengkai Ruan
- Department of Nephrology, State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Fujian Clinical Research Center for Chronic Glomerular Disease, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Weiping Hu
- Department of Nephrology, State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Fujian Clinical Research Center for Chronic Glomerular Disease, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Jiyi Huang
- Department of Nephrology, State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Fujian Clinical Research Center for Chronic Glomerular Disease, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Chengyong He
- Department of Nephrology, State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Fujian Clinical Research Center for Chronic Glomerular Disease, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Yi Yu
- Department of Nephrology, State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Fujian Clinical Research Center for Chronic Glomerular Disease, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361102, China.
| | - Zhenghong Zuo
- Department of Nephrology, State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Fujian Clinical Research Center for Chronic Glomerular Disease, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361102, China.
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3
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Ma L, Ling C, Hu S, Ye S, Chen C. High-throughput transcriptome sequencing reveals the protective role of adenosine receptor-related genes in paraquat-exposed Caenorhabditis elegans. Toxicol Res (Camb) 2023; 12:564-573. [PMID: 37663816 PMCID: PMC10470339 DOI: 10.1093/toxres/tfad046] [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: 01/29/2023] [Revised: 06/01/2023] [Accepted: 06/02/2023] [Indexed: 09/05/2023] Open
Abstract
This study sought to identify the genes associated with adenosine's protective action against paraquat (PQ)-induced oxidative stress via the adenosine receptor (ADOR-1) in Caenorhabditis elegans (C. elegans). The C. elegans was divided into 3 groups-2 groups exposed to PQ, one in presence, and one in absence of adenosine-and a control group that was not treated. Each group's total RNA was extracted and sequenced. When the transcriptomes of these groups were analyzed, several genes were found to be differently expressed. These differentially expressed genes were significantly enriched in adenosine-response biological processes and pathways, including gene ontology terms related to neuropeptide and kyoto encyclopedia of genes and genomes pathways associated to cAMP pathway regulator activity. Quantitative reverse-transcription PCR confirmed that G-protein-coupled receptors signaling pathway involving dop-1, egl-30, unc-13, kin-1, and goa-1 genes may play crucial roles in modulating adenosine's protective action. Interestingly, there are no significant variations in the expression of the ador-1 gene across the 3 treatments, thereby indicating that adenosine receptor exerts a consistent and stable influence on its related pathways irrespective of the presence or absence of PQ. Furthermore, the wild-type group with ador-1 gene has higher survival rate than that of the ador-1-/RNA interference group while treated with PQ in the presence of adenosine. Conclusively, our study uncovered a number of novel PQ-response genes and adenosine receptor-related genes in C. elegans, which may function as major regulators of PQ-induced oxidative stress and indicate the possible protective effects of adenosine.
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Affiliation(s)
- Lingmei Ma
- College of Life Sciences, Engineering Training Centre/College of Innovation, China Jiliang University, Hangzhou 310018, China
| | - Chunyan Ling
- College of Life Sciences, Engineering Training Centre/College of Innovation, China Jiliang University, Hangzhou 310018, China
| | - Shuning Hu
- College of Life Sciences, Engineering Training Centre/College of Innovation, China Jiliang University, Hangzhou 310018, China
| | - Sudan Ye
- College of Applied Engineering, Zhejiang Institute of Economics and Trade, Hangzhou 310018, China
| | - Chun Chen
- College of Life Sciences, Engineering Training Centre/College of Innovation, China Jiliang University, Hangzhou 310018, China
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Grinzato A, Auguin D, Kikuti C, Nandwani N, Moussaoui D, Pathak D, Kandiah E, Ruppel KM, Spudich JA, Houdusse A, Robert-Paganin J. Cryo-EM structure of the folded-back state of human β-cardiac myosin. Nat Commun 2023; 14:3166. [PMID: 37258552 PMCID: PMC10232470 DOI: 10.1038/s41467-023-38698-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 05/11/2023] [Indexed: 06/02/2023] Open
Abstract
To save energy and precisely regulate cardiac contractility, cardiac muscle myosin heads are sequestered in an 'off' state that can be converted to an 'on' state when exertion is increased. The 'off' state is equated with a folded-back structure known as the interacting-heads motif (IHM), which is a regulatory feature of all class-2 muscle and non-muscle myosins. We report here the human β-cardiac myosin IHM structure determined by cryo-electron microscopy to 3.6 Å resolution, providing details of all the interfaces stabilizing the 'off' state. The structure shows that these interfaces are hot spots of hypertrophic cardiomyopathy mutations that are thought to cause hypercontractility by destabilizing the 'off' state. Importantly, the cardiac and smooth muscle myosin IHM structures dramatically differ, providing structural evidence for the divergent physiological regulation of these muscle types. The cardiac IHM structure will facilitate development of clinically useful new molecules that modulate IHM stability.
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Affiliation(s)
- Alessandro Grinzato
- CM01 beamline. European Synchrotron Radiation Facility (ESRF), Grenoble, France
| | - Daniel Auguin
- Structural Motility, Institut Curie, Paris Université Sciences et Lettres, Sorbonne Université, CNRS UMR144, F-75005, Paris, France
- Laboratoire de Biologie des Ligneux et des Grandes Cultures, Université d'Orléans, UPRES EA 1207, INRA-USC1328, F-45067, Orléans, France
| | - Carlos Kikuti
- Structural Motility, Institut Curie, Paris Université Sciences et Lettres, Sorbonne Université, CNRS UMR144, F-75005, Paris, France
| | - Neha Nandwani
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Dihia Moussaoui
- BM29 BIOSAXS beamline, European Synchrotron Radiation Facility (ESRF), Grenoble, France
| | - Divya Pathak
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Eaazhisai Kandiah
- CM01 beamline. European Synchrotron Radiation Facility (ESRF), Grenoble, France
| | - Kathleen M Ruppel
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA.
- Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, 94305, USA.
| | - James A Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Anne Houdusse
- Structural Motility, Institut Curie, Paris Université Sciences et Lettres, Sorbonne Université, CNRS UMR144, F-75005, Paris, France.
| | - Julien Robert-Paganin
- Structural Motility, Institut Curie, Paris Université Sciences et Lettres, Sorbonne Université, CNRS UMR144, F-75005, Paris, France.
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5
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Grinzato A, Auguin D, Kikuti C, Nandwani N, Moussaoui D, Pathak D, Kandiah E, Ruppel KM, Spudich JA, Houdusse A, Robert-Paganin J. Cryo-EM structure of the folded-back state of human β-cardiac myosin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.15.536999. [PMID: 37131793 PMCID: PMC10153137 DOI: 10.1101/2023.04.15.536999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
During normal levels of exertion, many cardiac muscle myosin heads are sequestered in an off-state even during systolic contraction to save energy and for precise regulation. They can be converted to an on-state when exertion is increased. Hypercontractility caused by hypertrophic cardiomyopathy (HCM) myosin mutations is often the result of shifting the equilibrium toward more heads in the on-state. The off-state is equated with a folded-back structure known as the interacting head motif (IHM), which is a regulatory feature of all muscle myosins and class-2 non-muscle myosins. We report here the human β-cardiac myosin IHM structure to 3.6 Å resolution. The structure shows that the interfaces are hot spots of HCM mutations and reveals details of the significant interactions. Importantly, the structures of cardiac and smooth muscle myosin IHMs are dramatically different. This challenges the concept that the IHM structure is conserved in all muscle types and opens new perspectives in the understanding of muscle physiology. The cardiac IHM structure has been the missing puzzle piece to fully understand the development of inherited cardiomyopathies. This work will pave the way for the development of new molecules able to stabilize or destabilize the IHM in a personalized medicine approach. *This manuscript was submitted to Nature Communications in August 2022 and dealt efficiently by the editors. All reviewers received this version of the manuscript before 9 208 August 2022. They also received coordinates and maps of our high resolution structure on the 18 208 August 2022. Due to slowness of at least one reviewer, this contribution was delayed for acceptance by Nature Communications and we are now depositing in bioRxiv the originally submitted version written in July 2022 for everyone to see. Indeed, two bioRxiv contributions at lower resolution but adding similar concepts on thick filament regulation were deposited this week in bioRxiv, one of the contributions having had access to our coordinates. We hope that our data at high resolution will be helpful for all readers that appreciate that high resolution information is required to build accurate atomic models and discuss implications for sarcomere regulation and the effects of cardiomyopathy mutations on heart muscle function.
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Affiliation(s)
- Alessandro Grinzato
- CM01 beamline. European Synchrotron Radiation Facility (ESRF), Grenoble, France
| | - Daniel Auguin
- Structural Motility, Institut Curie, Paris Université Sciences et Lettres, Sorbonne Université, CNRS UMR144, F-75005 Paris, France
- Laboratoire de Biologie des Ligneux et des Grandes Cultures, Université d’Orléans, UPRES EA 1207, INRA-USC1328, F-45067 Orléans, France
| | - Carlos Kikuti
- Structural Motility, Institut Curie, Paris Université Sciences et Lettres, Sorbonne Université, CNRS UMR144, F-75005 Paris, France
| | - Neha Nandwani
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, United States
| | - Dihia Moussaoui
- BM29 BIOSAXS beamline, European Synchrotron Radiation Facility (ESRF), Grenoble, France
| | - Divya Pathak
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, United States
| | - Eaazhisai Kandiah
- CM01 beamline. European Synchrotron Radiation Facility (ESRF), Grenoble, France
| | - Kathleen M. Ruppel
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, United States
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California 94305, United States
| | - James A. Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, United States
| | - Anne Houdusse
- Structural Motility, Institut Curie, Paris Université Sciences et Lettres, Sorbonne Université, CNRS UMR144, F-75005 Paris, France
| | - Julien Robert-Paganin
- Structural Motility, Institut Curie, Paris Université Sciences et Lettres, Sorbonne Université, CNRS UMR144, F-75005 Paris, France
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Turner KL, Morris HS, Awinda PO, Fitzsimons DP, Tanner BCW. RLC phosphorylation amplifies Ca2+ sensitivity of force in myocardium from cMyBP-C knockout mice. J Gen Physiol 2023; 155:213841. [PMID: 36715675 PMCID: PMC9930131 DOI: 10.1085/jgp.202213250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 11/11/2022] [Accepted: 01/18/2023] [Indexed: 01/31/2023] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is the leading genetic cause of heart disease. The heart comprises several proteins that work together to properly facilitate force production and pump blood throughout the body. Cardiac myosin binding protein-C (cMyBP-C) is a thick-filament protein, and mutations in cMyBP-C are frequently linked with clinical cases of HCM. Within the sarcomere, the N-terminus of cMyBP-C likely interacts with the myosin regulatory light chain (RLC); RLC is a subunit of myosin located within the myosin neck region that modulates contractile dynamics via its phosphorylation state. Phosphorylation of RLC is thought to influence myosin head position along the thick-filament backbone, making it more favorable to bind the thin filament of actin and facilitate force production. However, little is known about how these two proteins interact. We tested the effects of RLC phosphorylation on Ca2+-regulated contractility using biomechanical assays on skinned papillary muscle strips isolated from cMyBP-C KO mice and WT mice. RLC phosphorylation increased Ca2+ sensitivity of contraction (i.e., pCa50) from 5.80 ± 0.02 to 5.95 ± 0.03 in WT strips, whereas RLC phosphorylation increased Ca2+ sensitivity of contraction from 5.86 ± 0.02 to 6.15 ± 0.03 in cMyBP-C KO strips. These data suggest that the effects of RLC phosphorylation on Ca2+ sensitivity of contraction are amplified when cMyBP-C is absent from the sarcomere. This implies that cMyBP-C and RLC act in concert to regulate contractility in healthy hearts, and mutations to these proteins that lead to HCM (or a loss of phosphorylation with disease progression) may disrupt important interactions between these thick-filament regulatory proteins.
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Affiliation(s)
- Kyrah L Turner
- School of Molecular Biosciences & Neuroscience, Washington State University , Pullman, WA, USA
| | - Haley S Morris
- School of Molecular Biosciences & Neuroscience, Washington State University , Pullman, WA, USA
| | - Peter O Awinda
- Department of Integrative Physiology & Neuroscience, Washington State University , Pullman, WA, USA
| | - Daniel P Fitzsimons
- Department of Animal, Veterinary and Food Sciences, University of Idaho , Moscow, ID, USA
| | - Bertrand C W Tanner
- Department of Integrative Physiology & Neuroscience, Washington State University , Pullman, WA, USA
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Coyle-Asbil B, Ogilvie LM, Simpson JA. Emerging roles for estrogen in regulating skeletal muscle physiology. Physiol Genomics 2023; 55:75-78. [PMID: 36622080 DOI: 10.1152/physiolgenomics.00158.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Affiliation(s)
- Bridget Coyle-Asbil
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.,IMPART Investigator Team Canada, Saint John, New Brunswick, Canada
| | - Leslie M Ogilvie
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.,IMPART Investigator Team Canada, Saint John, New Brunswick, Canada
| | - Jeremy A Simpson
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.,IMPART Investigator Team Canada, Saint John, New Brunswick, Canada
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Butova X, Myachina T, Simonova R, Kochurova A, Bozhko Y, Arkhipov M, Solovyova O, Kopylova G, Shchepkin D, Khokhlova A. Peculiarities of the Acetylcholine Action on the Contractile Function of Cardiomyocytes from the Left and Right Atria in Rats. Cells 2022; 11:cells11233809. [PMID: 36497067 PMCID: PMC9737865 DOI: 10.3390/cells11233809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/18/2022] [Accepted: 11/25/2022] [Indexed: 11/30/2022] Open
Abstract
Acetylcholine (ACh) is the neurotransmitter of the parasympathetic nervous system that modulates cardiac function, and its high concentrations may induce atrial fibrillation. We compared the ACh action on the mechanical function of single cardiomyocytes from the left atria (LA) and the right atria (RA). We exposed single rat LA and RA cardiomyocytes to 1, 10, and 100 µM ACh for 10-15 min and measured the parameters of sarcomere shortening-relengthening and cytosolic calcium ([Ca2+]i) transients during cell contractions. We also studied the effects of ACh on cardiac myosin function using an in vitro motility assay and analyzed the phosphorylation level of sarcomeric proteins. In LA cardiomyocytes, ACh decreased the time to peak sarcomere shortening, time to 50% relengthening, and time to peak [Ca2+]i transients. In RA cardiomyocytes, ACh affected the time of shortening and relengthening only at 10 µM. In the in vitro motility assay, ACh reduced to a greater extent the sliding velocity of F-actin over myosin from LA cardiomyocytes, which was accompanied by a more pronounced decrease in phosphorylation of the myosin regulatory light chain (RLC) in LA cardiomyocytes than in RA cardiomyocytes. Our findings indicate that ACh plays an important role in modulating the contractile function of LA and RA, provoking more pronounced changes in the time course of sarcomere shortening-relengthening and the kinetics of actin-myosin interaction in LA cardiomyocytes.
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Affiliation(s)
- Xenia Butova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya Str. 106, 620049 Yekaterinburg, Russia
| | - Tatiana Myachina
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya Str. 106, 620049 Yekaterinburg, Russia
| | - Raisa Simonova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya Str. 106, 620049 Yekaterinburg, Russia
| | - Anastasia Kochurova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya Str. 106, 620049 Yekaterinburg, Russia
| | - Yakov Bozhko
- Department of Therapy, Ural State Medical University, Repina Str. 3, 620028 Yekaterinburg, Russia
| | - Michael Arkhipov
- Department of Therapy, Ural State Medical University, Repina Str. 3, 620028 Yekaterinburg, Russia
| | - Olga Solovyova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya Str. 106, 620049 Yekaterinburg, Russia
- Institute of Natural Sciences and Mathematics, Ural Federal University, Mira 19, 620002 Yekaterinburg, Russia
| | - Galina Kopylova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya Str. 106, 620049 Yekaterinburg, Russia
| | - Daniil Shchepkin
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya Str. 106, 620049 Yekaterinburg, Russia
| | - Anastasia Khokhlova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya Str. 106, 620049 Yekaterinburg, Russia
- Institute of Natural Sciences and Mathematics, Ural Federal University, Mira 19, 620002 Yekaterinburg, Russia
- Correspondence:
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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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10
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Wang T, Spahiu E, Osten J, Behrens F, Grünhagen F, Scholz T, Kraft T, Nayak A, Amrute-Nayak M. Cardiac ventricular myosin and slow skeletal myosin exhibit dissimilar chemomechanical properties despite bearing the same myosin heavy chain isoform. J Biol Chem 2022; 298:102070. [PMID: 35623390 PMCID: PMC9243179 DOI: 10.1016/j.jbc.2022.102070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Revised: 05/12/2022] [Accepted: 05/14/2022] [Indexed: 11/29/2022] Open
Abstract
The myosin II motors are ATP-powered force-generating machines driving cardiac and muscle contraction. Myosin II heavy chain isoform-beta (β-MyHC) is primarily expressed in the ventricular myocardium and in slow-twitch muscle fibers, such as M. soleus. M. soleus–derived myosin II (SolM-II) is often used as an alternative to the ventricular β-cardiac myosin (βM-II); however, the direct assessment of biochemical and mechanical features of the native myosins is limited. By employing optical trapping, we examined the mechanochemical properties of native myosins isolated from the rabbit heart ventricle and soleus muscles at the single-molecule level. We found purified motors from the two tissue sources, despite expressing the same MyHC isoform, displayed distinct motile and ATPase kinetic properties. We demonstrate βM-II was approximately threefold faster in the actin filament–gliding assay than SolM-II. The maximum actomyosin (AM) detachment rate derived in single-molecule assays was also approximately threefold higher in βM-II, while the power stroke size and stiffness of the “AM rigor” crossbridge for both myosins were comparable. Our analysis revealed a higher AM detachment rate for βM-II, corresponding to the enhanced ADP release rates from the crossbridge, likely responsible for the observed differences in the motility driven by these myosins. Finally, we observed a distinct myosin light chain 1 isoform (MLC1sa) that associates with SolM-II, which might contribute to the observed kinetics differences between βM-II and SolM-II. These results have important implications for the choice of tissue sources and justify prerequisites for the correct myosin heavy and light chains to study cardiomyopathies.
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Affiliation(s)
- Tianbang Wang
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Emrulla Spahiu
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Jennifer Osten
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Florentine Behrens
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Fabius Grünhagen
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Tim Scholz
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Theresia Kraft
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Arnab Nayak
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany.
| | - Mamta Amrute-Nayak
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany.
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11
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Khokhlova A, Myachina T, Volzhaninov D, Butova X, Kochurova A, Berg V, Gette I, Moroz G, Klinova S, Minigalieva I, Solovyova O, Danilova I, Sokolova K, Kopylova G, Shchepkin D. Type 1 Diabetes Impairs Cardiomyocyte Contractility in the Left and Right Ventricular Free Walls but Preserves It in the Interventricular Septum. Int J Mol Sci 2022; 23:ijms23031719. [PMID: 35163643 PMCID: PMC8836009 DOI: 10.3390/ijms23031719] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/28/2022] [Accepted: 01/28/2022] [Indexed: 12/14/2022] Open
Abstract
Type 1 diabetes (T1D) leads to ischemic heart disease and diabetic cardiomyopathy. We tested the hypothesis that T1D differently affects the contractile function of the left and right ventricular free walls (LV, RV) and the interventricular septum (IS) using a rat model of alloxan-induced T1D. Single-myocyte mechanics and cytosolic Ca2+ concentration transients were studied on cardiomyocytes (CM) from LV, RV, and IS in the absence and presence of mechanical load. In addition, we analyzed the phosphorylation level of sarcomeric proteins and the characteristics of the actin-myosin interaction. T1D similarly affected the characteristics of actin-myosin interaction in all studied regions, decreasing the sliding velocity of native thin filaments over myosin in an in vitro motility assay and its Ca2+ sensitivity. A decrease in the thin-filament velocity was associated with increased expression of β-myosin heavy-chain isoform. However, changes in the mechanical function of single ventricular CM induced by T1D were different. T1D depressed the contractility of CM from LV and RV; it decreased the auxotonic tension amplitude and the slope of the active tension–length relationship. Nevertheless, the contractile function of CM from IS was principally preserved.
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Affiliation(s)
- Anastasia Khokhlova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya 106, 620049 Yekaterinburg, Russia; (T.M.); (D.V.); (X.B.); (A.K.); (V.B.); (I.G.); (O.S.); (I.D.); (K.S.); (G.K.); (D.S.)
- Institute of Physics and Technology, Ural Federal University, Mira 19, 620002 Yekaterinburg, Russia
- Correspondence:
| | - Tatiana Myachina
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya 106, 620049 Yekaterinburg, Russia; (T.M.); (D.V.); (X.B.); (A.K.); (V.B.); (I.G.); (O.S.); (I.D.); (K.S.); (G.K.); (D.S.)
| | - Denis Volzhaninov
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya 106, 620049 Yekaterinburg, Russia; (T.M.); (D.V.); (X.B.); (A.K.); (V.B.); (I.G.); (O.S.); (I.D.); (K.S.); (G.K.); (D.S.)
| | - Xenia Butova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya 106, 620049 Yekaterinburg, Russia; (T.M.); (D.V.); (X.B.); (A.K.); (V.B.); (I.G.); (O.S.); (I.D.); (K.S.); (G.K.); (D.S.)
| | - Anastasia Kochurova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya 106, 620049 Yekaterinburg, Russia; (T.M.); (D.V.); (X.B.); (A.K.); (V.B.); (I.G.); (O.S.); (I.D.); (K.S.); (G.K.); (D.S.)
| | - Valentina Berg
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya 106, 620049 Yekaterinburg, Russia; (T.M.); (D.V.); (X.B.); (A.K.); (V.B.); (I.G.); (O.S.); (I.D.); (K.S.); (G.K.); (D.S.)
| | - Irina Gette
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya 106, 620049 Yekaterinburg, Russia; (T.M.); (D.V.); (X.B.); (A.K.); (V.B.); (I.G.); (O.S.); (I.D.); (K.S.); (G.K.); (D.S.)
| | - Gleb Moroz
- Institute of Natural Sciences and Mathematics, Ural Federal University, Mira 19, 620002 Yekaterinburg, Russia;
| | - Svetlana Klinova
- Yekaterinburg Medical Research Center for Prophylaxis and Health Protection in Industrial Workers, Popova 30, 620014 Yekaterinburg, Russia; (S.K.); (I.M.)
| | - Ilzira Minigalieva
- Yekaterinburg Medical Research Center for Prophylaxis and Health Protection in Industrial Workers, Popova 30, 620014 Yekaterinburg, Russia; (S.K.); (I.M.)
| | - Olga Solovyova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya 106, 620049 Yekaterinburg, Russia; (T.M.); (D.V.); (X.B.); (A.K.); (V.B.); (I.G.); (O.S.); (I.D.); (K.S.); (G.K.); (D.S.)
- Institute of Physics and Technology, Ural Federal University, Mira 19, 620002 Yekaterinburg, Russia
- Institute of Natural Sciences and Mathematics, Ural Federal University, Mira 19, 620002 Yekaterinburg, Russia;
| | - Irina Danilova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya 106, 620049 Yekaterinburg, Russia; (T.M.); (D.V.); (X.B.); (A.K.); (V.B.); (I.G.); (O.S.); (I.D.); (K.S.); (G.K.); (D.S.)
| | - Ksenia Sokolova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya 106, 620049 Yekaterinburg, Russia; (T.M.); (D.V.); (X.B.); (A.K.); (V.B.); (I.G.); (O.S.); (I.D.); (K.S.); (G.K.); (D.S.)
| | - Galina Kopylova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya 106, 620049 Yekaterinburg, Russia; (T.M.); (D.V.); (X.B.); (A.K.); (V.B.); (I.G.); (O.S.); (I.D.); (K.S.); (G.K.); (D.S.)
| | - Daniil Shchepkin
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya 106, 620049 Yekaterinburg, Russia; (T.M.); (D.V.); (X.B.); (A.K.); (V.B.); (I.G.); (O.S.); (I.D.); (K.S.); (G.K.); (D.S.)
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12
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Abstract
Super-relaxation is a state of muscle thick filaments in which ATP turnover by myosin is much slower than that of myosin II in solution. This inhibited state, in equilibrium with a faster (relaxed) state, is ubiquitous and thought to be fundamental to muscle function, acting as a mechanism for switching off energy-consuming myosin motors when they are not being used. The structural basis of super-relaxation is usually taken to be a motif formed by myosin in which the two heads interact with each other and with the proximal tail forming an interacting-heads motif, which switches the heads off. However, recent studies show that even isolated myosin heads can exhibit this slow rate. Here, we review the role of head interactions in creating the super-relaxed state and show how increased numbers of interactions in thick filaments underlie the high levels of super-relaxation found in intact muscle. We suggest how a third, even more inhibited, state of myosin (a hyper-relaxed state) seen in certain species results from additional interactions involving the heads. We speculate on the relationship between animal lifestyle and level of super-relaxation in different species and on the mechanism of formation of the super-relaxed state. We also review how super-relaxed thick filaments are activated and how the super-relaxed state is modulated in healthy and diseased muscles.
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Affiliation(s)
- Roger Craig
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Chan Medical School, Worcester, MA
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13
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Markandran K, Yu H, Song W, Lam DTUH, Madathummal MC, Ferenczi MA. Functional and Molecular Characterisation of Heart Failure Progression in Mice and the Role of Myosin Regulatory Light Chains in the Recovery of Cardiac Muscle Function. Int J Mol Sci 2021; 23:ijms23010088. [PMID: 35008512 PMCID: PMC8745055 DOI: 10.3390/ijms23010088] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 12/07/2021] [Accepted: 12/14/2021] [Indexed: 02/07/2023] Open
Abstract
Heart failure (HF) as a result of myocardial infarction (MI) is a major cause of fatality worldwide. However, the cause of cardiac dysfunction succeeding MI has not been elucidated at a sarcomeric level. Thus, studying the alterations within the sarcomere is necessary to gain insights on the fundamental mechansims leading to HF and potentially uncover appropriate therapeutic targets. Since existing research portrays regulatory light chains (RLC) to be mediators of cardiac muscle contraction in both human and animal models, its role was further explored In this study, a detailed characterisation of the physiological changes (i.e., isometric force, calcium sensitivity and sarcomeric protein phosphorylation) was assessed in an MI mouse model, between 2D (2 days) and 28D post-MI, and the changes were related to the phosphorylation status of RLCs. MI mouse models were created via complete ligation of left anterior descending (LAD) coronary artery. Left ventricular (LV) papillary muscles were isolated and permeabilised for isometric force and Ca2+ sensitivity measurement, while the LV myocardium was used to assay sarcomeric proteins’ (RLC, troponin I (TnI) and myosin binding protein-C (MyBP-C)) phosphorylation levels and enzyme (myosin light chain kinase (MLCK), zipper interacting protein kinase (ZIPK) and myosin phosphatase target subunit 2 (MYPT2)) expression levels. Finally, the potential for improving the contractility of diseased cardiac papillary fibres via the enhancement of RLC phosphorylation levels was investigated by employing RLC exchange methods, in vitro. RLC phosphorylation and isometric force potentiation were enhanced in the compensatory phase and decreased in the decompensatory phase of HF failure progression, respectively. There was no significant time-lag between the changes in RLC phosphorylation and isometric force during HF progression, suggesting that changes in RLC phosphorylation immediately affect force generation. Additionally, the in vitro increase in RLC phosphorylation levels in 14D post-MI muscle segments (decompensatory stage) enhanced its force of isometric contraction, substantiating its potential in HF treatment. Longitudinal observation unveils potential mechanisms involving MyBP-C and key enzymes regulating RLC phosphorylation, such as MLCK and MYPT2 (subunit of MLCP), during HF progression. This study primarily demonstrates that RLC phosphorylation is a key sarcomeric protein modification modulating cardiac function. This substantiates the possibility of using RLCs and their associated enzymes to treat HF.
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Affiliation(s)
- Kasturi Markandran
- Lee Kong Chian School of Medicine, Nanyang Technological University, Experimental Medicine Building, 59 Nanyang Drive, Singapore 636921, Singapore; (K.M.); (H.Y.); (W.S.); (D.T.U.H.L.); (M.C.M.)
| | - Haiyang Yu
- Lee Kong Chian School of Medicine, Nanyang Technological University, Experimental Medicine Building, 59 Nanyang Drive, Singapore 636921, Singapore; (K.M.); (H.Y.); (W.S.); (D.T.U.H.L.); (M.C.M.)
| | - Weihua Song
- Lee Kong Chian School of Medicine, Nanyang Technological University, Experimental Medicine Building, 59 Nanyang Drive, Singapore 636921, Singapore; (K.M.); (H.Y.); (W.S.); (D.T.U.H.L.); (M.C.M.)
| | - Do Thuy Uyen Ha Lam
- Lee Kong Chian School of Medicine, Nanyang Technological University, Experimental Medicine Building, 59 Nanyang Drive, Singapore 636921, Singapore; (K.M.); (H.Y.); (W.S.); (D.T.U.H.L.); (M.C.M.)
- Laboratory of Precision Disease Therapeutics, Genome Institute of Singapore, 60 Biopolis Street, Singapore 138672, Singapore
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Drive, Singapore 117597, Singapore
| | - Mufeeda Changaramvally Madathummal
- Lee Kong Chian School of Medicine, Nanyang Technological University, Experimental Medicine Building, 59 Nanyang Drive, Singapore 636921, Singapore; (K.M.); (H.Y.); (W.S.); (D.T.U.H.L.); (M.C.M.)
- A*STAR Microscopy Platform—Electron Microscopy, 61 Biopolis Drive, Proteos, Singapore 138673, Singapore
| | - Michael A. Ferenczi
- Lee Kong Chian School of Medicine, Nanyang Technological University, Experimental Medicine Building, 59 Nanyang Drive, Singapore 636921, Singapore; (K.M.); (H.Y.); (W.S.); (D.T.U.H.L.); (M.C.M.)
- Brunel Medical School, Brunel University London, Kingston Lane, Uxbridge UB8 3PH, UK
- Correspondence:
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14
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Markandran K, Xuan JVLE, Yu H, Shun LM, Ferenczi MA. Mn 2+ -Phos-Tag Polyacrylamide for the Quantification of Protein Phosphorylation Levels. Curr Protoc 2021; 1:e221. [PMID: 34411463 DOI: 10.1002/cpz1.221] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This paper provides a guideline for optimizing and utilizing Mn2+ Phos-tag gel technology to separate phosphorylated proteins from their unphosphorylated counterparts. It provides key insights into methods for careful sample preparation and experimental directions for determining the appropriate Phos-tag gel compositions and electrophoresis and western blotting conditions. This protocol has been used to successfully resolve proteins extracted from cardiac and skeletal muscles. The guidelines can be extended for optimizing protocols to resolve proteins from other cells or tissue sources. With this, phosphoproteomics and the elucidation of underlying mechanisms of disease progression can be accelerated. © 2021 The Authors. Current Protocols published by Wiley Periodicals LLC.
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Affiliation(s)
- Kasturi Markandran
- Laboratory of Muscle and Cardiac Biophysics, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Jane Vanetta Lee En Xuan
- Laboratory of Muscle and Cardiac Biophysics, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Haiyang Yu
- Laboratory of Muscle and Cardiac Biophysics, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore.,WuXi Biologics, Wuxi, Jiangsu, China
| | - Lim Meng Shun
- Laboratory of Muscle and Cardiac Biophysics, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Michael A Ferenczi
- Laboratory of Muscle and Cardiac Biophysics, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore.,Brunel Medical School, Brunel University London, Uxbridge, UK
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15
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Disrupting the LINC complex by AAV mediated gene transduction prevents progression of Lamin induced cardiomyopathy. Nat Commun 2021; 12:4722. [PMID: 34354059 PMCID: PMC8342462 DOI: 10.1038/s41467-021-24849-4] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 07/07/2021] [Indexed: 12/28/2022] Open
Abstract
Mutations in the LaminA gene are a common cause of monogenic dilated cardiomyopathy. Here we show that mice with a cardiomyocyte-specific Lmna deletion develop cardiac failure and die within 3-4 weeks after inducing the mutation. When the same Lmna mutations are induced in mice genetically deficient in the LINC complex protein SUN1, life is extended to more than one year. Disruption of SUN1's function is also accomplished by transducing and expressing a dominant-negative SUN1 miniprotein in Lmna deficient cardiomyocytes, using the cardiotrophic Adeno Associated Viral Vector 9. The SUN1 miniprotein disrupts binding between the endogenous LINC complex SUN and KASH domains, displacing the cardiomyocyte KASH complexes from the nuclear periphery, resulting in at least a fivefold extension in lifespan. Cardiomyocyte-specific expression of the SUN1 miniprotein prevents cardiomyopathy progression, potentially avoiding the necessity of developing a specific therapeutic tailored to treating each different LMNA cardiomyopathy-inducing mutation of which there are more than 450.
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16
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Regulatory Light Chains in Cardiac Development and Disease. Int J Mol Sci 2021; 22:ijms22094351. [PMID: 33919432 PMCID: PMC8122660 DOI: 10.3390/ijms22094351] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 04/14/2021] [Accepted: 04/17/2021] [Indexed: 12/18/2022] Open
Abstract
The role of regulatory light chains (RLCs) in cardiac muscle function has been elucidated progressively over the past decade. The RLCs are among the earliest expressed markers during cardiogenesis and persist through adulthood. Failing hearts have shown reduced RLC phosphorylation levels and that restoring baseline levels of RLC phosphorylation is necessary for generating optimal force of muscle contraction. The signalling mechanisms triggering changes in RLC phosphorylation levels during disease progression remain elusive. Uncovering this information may provide insights for better management of heart failure patients. Given the cardiac chamber-specific expression of RLC isoforms, ventricular RLCs have facilitated the identification of mature ventricular cardiomyocytes, opening up possibilities of regenerative medicine. This review consolidates the standing of RLCs in cardiac development and disease and highlights knowledge gaps and potential therapeutic advancements in targeting RLCs.
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17
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Schmid M, Toepfer CN. Cardiac myosin super relaxation (SRX): a perspective on fundamental biology, human disease and therapeutics. Biol Open 2021; 10:bio057646. [PMID: 33589442 PMCID: PMC7904003 DOI: 10.1242/bio.057646] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The fundamental basis of muscle contraction 'the sliding filament model' (Huxley and Niedergerke, 1954; Huxley and Hanson, 1954) and the 'swinging, tilting crossbridge-sliding filament mechanism' (Huxley, 1969; Huxley and Brown, 1967) nucleated a field of research that has unearthed the complex and fascinating role of myosin structure in the regulation of contraction. A recently discovered energy conserving state of myosin termed the super relaxed state (SRX) has been observed in filamentous myosins and is central to modulating force production and energy use within the sarcomere. Modulation of myosin function through SRX is a rapidly developing theme in therapeutic development for both cardiovascular disease and infectious disease. Some 70 years after the first discoveries concerning muscular function, modulation of myosin SRX may bring the first myosin targeted small molecule to the clinic, for treating hypertrophic cardiomyopathy (Olivotto et al., 2020). An often monogenic disease HCM afflicts 1 in 500 individuals, and can cause heart failure and sudden cardiac death. Even as we near therapeutic translation, there remain many questions about the governance of muscle function in human health and disease. With this review, we provide a broad overview of contemporary understanding of myosin SRX, and explore the complexities of targeting this myosin state in human disease.This article has an associated Future Leaders to Watch interview with the authors of the paper.
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Affiliation(s)
- Manuel Schmid
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, UK
| | - Christopher N Toepfer
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, UK
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
- Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
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18
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Abstract
Since the discovery of muscle in the 19th century, myosins as molecular motors have been extensively studied. However, in the last decade, a new functional super-relaxed (SRX) state of myosin has been discovered, which has a 10-fold slower ATP turnover rate than the already-known non-actin-bound, disordered relaxed (DRX) state. These two states are in dynamic equilibrium under resting muscle conditions and are thought to be significant contributors to adaptive thermogenesis in skeletal muscle and can act as a reserve pool that may be recruited when there is a sustained demand for increased cardiac muscle power. This report provides an evolutionary perspective of how striated muscle contraction is regulated by modulating this myosin DRX↔SRX state equilibrium. We further discuss this equilibrium with respect to different physiological and pathophysiological perturbations, including insults causing hypertrophic cardiomyopathy, and small-molecule effectors that modulate muscle contractility in diseased pathology.
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Affiliation(s)
- Suman Nag
- Department of Biology, MyoKardia IncBrisbaneUnited States
| | - Darshan V Trivedi
- Department of Biochemistry, Stanford University School of MedicineStanfordUnited States
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19
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Douglas CM, Hesketh SJ, Esser KA. Time of Day and Muscle Strength: A Circadian Output? Physiology (Bethesda) 2021; 36:44-51. [PMID: 33325817 DOI: 10.1152/physiol.00030.2020] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
For more than 20 years, physiologists have observed a morning-to-evening increase in human muscle strength. Recent data suggest that time-of-day differences are the result of intrinsic, nonneural, muscle factors. We evaluate circadian clock data sets from human and mouse circadian studies and highlight possible mechanisms through which the muscle circadian clock may contribute to time-of-day muscle strength outcomes.
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Affiliation(s)
- Collin M Douglas
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, FloridaMyology Institute, University of Florida, Gainesville, Florida
| | - Stuart J Hesketh
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, FloridaMyology Institute, University of Florida, Gainesville, Florida
| | - Karyn A Esser
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, FloridaMyology Institute, University of Florida, Gainesville, Florida
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20
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Awinda PO, Bishaw Y, Watanabe M, Guglin MA, Campbell KS, Tanner BCW. Effects of mavacamten on Ca 2+ sensitivity of contraction as sarcomere length varied in human myocardium. Br J Pharmacol 2020; 177:5609-5621. [PMID: 32960449 PMCID: PMC7707091 DOI: 10.1111/bph.15271] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 09/08/2020] [Accepted: 09/11/2020] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND AND PURPOSE Heart failure can reflect impaired contractile function at the myofilament level. In healthy hearts, myofilaments become more sensitive to Ca2+ as cells are stretched. This represents a fundamental property of the myocardium that contributes to the Frank-Starling response, although the molecular mechanisms underlying the effect remain unclear. Mavacamten, which binds to myosin, is under investigation as a potential therapy for heart disease. We investigated how mavacamten affects the sarcomere-length dependence of Ca2+ -sensitive isometric contraction to determine how mavacamten might modulate the Frank-Starling mechanism. EXPERIMENTAL APPROACH Multicellular preparations from the left ventricular-free wall of hearts from organ donors were chemically permeabilized and Ca2+ activated in the presence or absence of 0.5-μM mavacamten at 1.9 or 2.3-μm sarcomere length (37°C). Isometric force and frequency-dependent viscoelastic myocardial stiffness measurements were made. KEY RESULTS At both sarcomere lengths, mavacamten reduced maximal force and Ca2+ sensitivity of contraction. In the presence and absence of mavacamten, Ca2+ sensitivity of force increased as sarcomere length increased. This suggests that the length-dependent activation response was maintained in human myocardium, even though mavacamten reduced Ca2+ sensitivity. There were subtle effects of mavacamten reducing force values under relaxed conditions (pCa 8.0), as well as slowing myosin cross-bridge recruitment and speeding cross-bridge detachment under maximally activated conditions (pCa 4.5). CONCLUSION AND IMPLICATIONS Mavacamten did not eliminate sarcomere length-dependent increases in the Ca2+ sensitivity of contraction in myocardial strips from organ donors at physiological temperature. Drugs that modulate myofilament function may be useful therapies for cardiomyopathies.
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Affiliation(s)
- Peter O. Awinda
- Department of Integrative Physiology and NeuroscienceWashington State UniversityPullmanWashingtonUSA
| | - Yemeserach Bishaw
- Department of Integrative Physiology and NeuroscienceWashington State UniversityPullmanWashingtonUSA
| | - Marissa Watanabe
- Department of Integrative Physiology and NeuroscienceWashington State UniversityPullmanWashingtonUSA
| | - Maya A. Guglin
- Division of Cardiovascular MedicineUniversity of KentuckyLexingtonKentuckyUSA
| | - Kenneth S. Campbell
- Department of PhysiologyUniversity of KentuckyLexingtonKentuckyUSA
- Division of Cardiovascular MedicineUniversity of KentuckyLexingtonKentuckyUSA
| | - Bertrand C. W. Tanner
- Department of Integrative Physiology and NeuroscienceWashington State UniversityPullmanWashingtonUSA
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21
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Heling LWHJ, Geeves MA, Kad NM. MyBP-C: one protein to govern them all. J Muscle Res Cell Motil 2020; 41:91-101. [PMID: 31960266 PMCID: PMC7109175 DOI: 10.1007/s10974-019-09567-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 11/29/2019] [Indexed: 12/19/2022]
Abstract
The heart is an extraordinarily versatile pump, finely tuned to respond to a multitude of demands. Given the heart pumps without rest for decades its efficiency is particularly relevant. Although many proteins in the heart are essential for viability, the non-essential components can attract numerous mutations which can cause disease, possibly through alterations in pumping efficiency. Of these, myosin binding protein C is strongly over-represented with ~ 40% of all known mutations in hypertrophic cardiomyopathy. Therefore, a complete understanding of its molecular function in the cardiac sarcomere is warranted. In this review, we revisit contemporary and classical literature to clarify both the current standing of this fast-moving field and frame future unresolved questions. To date, much effort has been directed at understanding MyBP-C function on either thick or thin filaments. Here we aim to focus questions on how MyBP-C functions at a molecular level in the context of both the thick and thin filaments together. A concept that emerges is MyBP-C acts to govern interactions on two levels; controlling myosin access to the thin filament by sequestration on the thick filament, and controlling the activation state and access of myosin to its binding sites on the thin filament. Such affects are achieved through directed interactions mediated by phosphorylation (of MyBP-C and other sarcomeric components) and calcium.
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Affiliation(s)
- L W H J Heling
- School of Biosciences, University of Kent, Canterbury, CT2 7NH, UK
| | - M A Geeves
- School of Biosciences, University of Kent, Canterbury, CT2 7NH, UK
| | - N M Kad
- School of Biosciences, University of Kent, Canterbury, CT2 7NH, UK.
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22
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Vera CD, Johnson CA, Walklate J, Adhikari A, Svicevic M, Mijailovich SM, Combs AC, Langer SJ, Ruppel KM, Spudich JA, Geeves MA, Leinwand LA. Myosin motor domains carrying mutations implicated in early or late onset hypertrophic cardiomyopathy have similar properties. J Biol Chem 2019; 294:17451-17462. [PMID: 31582565 DOI: 10.1074/jbc.ra119.010563] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 09/18/2019] [Indexed: 02/01/2023] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is a common genetic disorder characterized by left ventricular hypertrophy and cardiac hyper-contractility. Mutations in the β-cardiac myosin heavy chain gene (β-MyHC) are a major cause of HCM, but the specific mechanistic changes to myosin function that lead to this disease remain incompletely understood. Predicting the severity of any β-MyHC mutation is hindered by a lack of detailed examinations at the molecular level. Moreover, because HCM can take ≥20 years to develop, the severity of the mutations must be somewhat subtle. We hypothesized that mutations that result in early onset disease would have more severe changes in function than do later onset mutations. Here, we performed steady-state and transient kinetic analyses of myosins carrying one of seven missense mutations in the motor domain. Of these seven, four were previously identified in early onset cardiomyopathy screens. We used the parameters derived from these analyses to model the ATP-driven cross-bridge cycle. Contrary to our hypothesis, the results indicated no clear differences between early and late onset HCM mutations. Despite the lack of distinction between early and late onset HCM, the predicted occupancy of the force-holding actin·myosin·ADP complex at [Actin] = 3 K app along with the closely related duty ratio (the fraction of myosin in strongly attached force-holding states), and the measured ATPases all changed in parallel (in both sign and degree of change) compared with wildtype (WT) values. Six of the seven HCM mutations were clearly distinct from a set of previously characterized DCM mutations.
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Affiliation(s)
- Carlos D Vera
- BioFrontiers Institute and Department of Molecular, Cellular and Developmental Biology, University of Colorado Boulder, Boulder, Colorado 80309
| | - Chloe A Johnson
- School of Biosciences, University of Kent, Canterbury CT2 7NJ, United Kingdom
| | - Jonathan Walklate
- School of Biosciences, University of Kent, Canterbury CT2 7NJ, United Kingdom
| | - Arjun Adhikari
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305
| | | | | | - Ariana C Combs
- BioFrontiers Institute and Department of Molecular, Cellular and Developmental Biology, University of Colorado Boulder, Boulder, Colorado 80309
| | - Stephen J Langer
- BioFrontiers Institute and Department of Molecular, Cellular and Developmental Biology, University of Colorado Boulder, Boulder, Colorado 80309
| | - Kathleen M Ruppel
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305
| | - James A Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305
| | - Michael A Geeves
- School of Biosciences, University of Kent, Canterbury CT2 7NJ, United Kingdom
| | - Leslie A Leinwand
- BioFrontiers Institute and Department of Molecular, Cellular and Developmental Biology, University of Colorado Boulder, Boulder, Colorado 80309
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23
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Spudich JA. Three perspectives on the molecular basis of hypercontractility caused by hypertrophic cardiomyopathy mutations. Pflugers Arch 2019; 471:701-717. [PMID: 30767072 PMCID: PMC6475635 DOI: 10.1007/s00424-019-02259-2] [Citation(s) in RCA: 104] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 01/11/2019] [Accepted: 01/20/2019] [Indexed: 01/10/2023]
Abstract
Several lines of evidence suggest that the primary effect of hypertrophic cardiomyopathy mutations in human β-cardiac myosin is hypercontractility of the heart, which leads to subsequent hypertrophy, fibrosis, and myofilament disarray. Here, I describe three perspectives on the molecular basis of this hypercontractility. The first is that hypercontractility results from changes in the fundamental parameters of the actin-activated β-cardiac myosin chemo-mechanical ATPase cycle. The second considers that hypercontractility results from an increase in the number of functionally accessible heads in the sarcomere for interaction with actin. The final and third perspective is that load dependence of contractility is affected by cardiomyopathy mutations and small-molecule effectors in a manner that changes the power output of cardiac contraction. Experimental approaches associated with each perspective are described along with concepts of therapeutic approaches that could prove valuable in treating hypertrophic cardiomyopathy.
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Affiliation(s)
- James A Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA.
- Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, 94305, USA.
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24
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Toepfer CN, Wakimoto H, Garfinkel AC, McDonough B, Liao D, Jiang J, Tai AC, Gorham JM, Lunde IG, Lun M, Lynch TL, McNamara JW, Sadayappan S, Redwood CS, Watkins HC, Seidman JG, Seidman CE. Hypertrophic cardiomyopathy mutations in MYBPC3 dysregulate myosin. Sci Transl Med 2019; 11:eaat1199. [PMID: 30674652 PMCID: PMC7184965 DOI: 10.1126/scitranslmed.aat1199] [Citation(s) in RCA: 121] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 06/05/2018] [Accepted: 11/30/2018] [Indexed: 12/16/2022]
Abstract
The mechanisms by which truncating mutations in MYBPC3 (encoding cardiac myosin-binding protein C; cMyBPC) or myosin missense mutations cause hypercontractility and poor relaxation in hypertrophic cardiomyopathy (HCM) are incompletely understood. Using genetic and biochemical approaches, we explored how depletion of cMyBPC altered sarcomere function. We demonstrated that stepwise loss of cMyBPC resulted in reciprocal augmentation of myosin contractility. Direct attenuation of myosin function, via a damaging missense variant (F764L) that causes dilated cardiomyopathy (DCM), normalized the increased contractility from cMyBPC depletion. Depletion of cMyBPC also altered dynamic myosin conformations during relaxation, enhancing the myosin state that enables ATP hydrolysis and thin filament interactions while reducing the super relaxed conformation associated with energy conservation. MYK-461, a pharmacologic inhibitor of myosin ATPase, rescued relaxation deficits and restored normal contractility in mouse and human cardiomyocytes with MYBPC3 mutations. These data define dosage-dependent effects of cMyBPC on myosin that occur across the cardiac cycle as the pathophysiologic mechanisms by which MYBPC3 truncations cause HCM. Therapeutic strategies to attenuate cMyBPC activity may rescue depressed cardiac contractility in patients with DCM, whereas inhibiting myosin by MYK-461 should benefit the substantial proportion of patients with HCM with MYBPC3 mutations.
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Affiliation(s)
- Christopher N Toepfer
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, OX3 9DU, UK
- Wellcome Centre for Human Genetics, University of Oxford, OX3 7BN, UK
| | - Hiroko Wakimoto
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
- Department of Cardiology, Children's Hospital Boston, Boston, MA 02115, USA
| | | | | | - Dan Liao
- Department of Biochemistry and Cardiovascular Research Institute (CVRI), Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
| | - Jianming Jiang
- Department of Biochemistry and Cardiovascular Research Institute (CVRI), Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
| | - Angela C Tai
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Joshua M Gorham
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Ida G Lunde
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, 0318 Oslo, Norway
| | - Mingyue Lun
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Thomas L Lynch
- Department of Molecular Pharmacology and Therapeutics, Health Sciences Division, Loyola University Chicago, Maywood, IL 60153, USA
| | - James W McNamara
- Heart, Lung and Vascular Institute, University of Cincinnati, Cincinnati, OH 45219, USA
| | - Sakthivel Sadayappan
- Heart, Lung and Vascular Institute, University of Cincinnati, Cincinnati, OH 45219, USA
| | - Charles S Redwood
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, OX3 9DU, UK
| | - Hugh C Watkins
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, OX3 9DU, UK
- Wellcome Centre for Human Genetics, University of Oxford, OX3 7BN, UK
| | | | - Christine E Seidman
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
- Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
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25
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The Molecular Mechanisms of Mutations in Actin and Myosin that Cause Inherited Myopathy. Int J Mol Sci 2018; 19:ijms19072020. [PMID: 29997361 PMCID: PMC6073311 DOI: 10.3390/ijms19072020] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2018] [Revised: 07/06/2018] [Accepted: 07/08/2018] [Indexed: 12/23/2022] Open
Abstract
The discovery that mutations in myosin and actin genes, together with mutations in the other components of the muscle sarcomere, are responsible for a range of inherited muscle diseases (myopathies) has revolutionized the study of muscle, converting it from a subject of basic science to a relevant subject for clinical study and has been responsible for a great increase of interest in muscle studies. Myopathies are linked to mutations in five of the myosin heavy chain genes, three of the myosin light chain genes, and three of the actin genes. This review aims to determine to what extent we can explain disease phenotype from the mutant genotype. To optimise our chances of finding the right mechanism we must study a myopathy where there are a large number of different mutations that cause a common phenotype and so are likely to have a common mechanism: a corollary to this criterion is that if any mutation causes the disease phenotype but does not correspond to the proposed mechanism, then the whole mechanism is suspect. Using these criteria, we consider two cases where plausible genotype-phenotype mechanisms have been proposed: the actin “A-triad” and the myosin “mesa/IHD” models.
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26
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Piazzesi G, Caremani M, Linari M, Reconditi M, Lombardi V. Thick Filament Mechano-Sensing in Skeletal and Cardiac Muscles: A Common Mechanism Able to Adapt the Energetic Cost of the Contraction to the Task. Front Physiol 2018; 9:736. [PMID: 29962967 PMCID: PMC6010558 DOI: 10.3389/fphys.2018.00736] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 05/28/2018] [Indexed: 11/29/2022] Open
Abstract
A dual regulation of contraction operates in both skeletal and cardiac muscles. The first mechanism, based on Ca2+-dependent structural changes of the regulatory proteins in the thin filament, makes the actin sites available for binding of the myosin motors. The second recruits the myosin heads from the OFF state, in which they are unable to split ATP and bind to actin, in relation to the force during contraction. Comparison of the relevant X-ray diffraction signals marking the state of the thick filament demonstrates that the force feedback that controls the regulatory state of the thick filament works in the same way in skeletal as in cardiac muscles: even if in an isometric tetanus of skeletal muscle force is under the control of the firing frequency of the motor unit, while in a heartbeat force is controlled by the afterload, the stress-sensor switching the motors ON plays the same role in adapting the energetic cost of the contraction to the force. A new aspect of the Frank-Starling law of the heart emerges: independent of the diastolic filling of the ventricle, the number of myosin motors switched ON during systole, and thus the energetic cost of contraction, are tuned to the arterial pressure. Deterioration of the thick-filament regulation mechanism may explain the hyper-contractility related to hypertrophic cardiomyopathy, an inherited heart disease that in 40% of cases is due to mutations in cardiac myosin.
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Affiliation(s)
| | | | - Marco Linari
- PhysioLab, University of Florence, Florence, Italy
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27
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Sarcomeric perturbations of myosin motors lead to dilated cardiomyopathy in genetically modified MYL2 mice. Proc Natl Acad Sci U S A 2018; 115:E2338-E2347. [PMID: 29463717 PMCID: PMC5877945 DOI: 10.1073/pnas.1716925115] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Dilated cardiomyopathy (DCM) is a devastating heart disease that affects about 1 million people in the United States, but the underlying mechanisms remain poorly understood. In this study, we aimed to determine the biomechanical and structural causes of DCM in transgenic mice carrying a novel mutation in the MYL2 gene, encoding the cardiac myosin regulatory light chain. Transgenic D94A (aspartic acid-to-alanine) mice were created and investigated by echocardiography and invasive hemodynamic and molecular structural and functional assessments. Consistent with the DCM phenotype, a significant reduction of the ejection fraction (EF) was observed in ∼5- and ∼12-mo-old male and female D94A lines compared with respective WT controls. Younger male D94A mice showed a more pronounced left ventricular (LV) chamber dilation compared with female counterparts, but both sexes of D94A lines developed DCM by 12 mo of age. The hypocontractile activity of D94A myosin motors resulted in the rightward shift of the force-pCa dependence and decreased actin-activated myosin ATPase activity. Consistent with a decreased Ca2+ sensitivity of contractile force, a small-angle X-ray diffraction study, performed in D94A fibers at submaximal Ca2+ concentrations, revealed repositioning of the D94A cross-bridge mass toward the thick-filament backbone supporting the hypocontractile state of D94A myosin motors. Our data suggest that structural perturbations at the level of sarcomeres result in aberrant cardiomyocyte cytoarchitecture and lead to LV chamber dilation and decreased EF, manifesting in systolic dysfunction of D94A hearts. The D94A-induced development of DCM in mice closely follows the clinical phenotype and suggests that MYL2 may serve as a new therapeutic target for dilated cardiomyopathy.
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28
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Trivedi DV, Adhikari AS, Sarkar SS, Ruppel KM, Spudich JA. Hypertrophic cardiomyopathy and the myosin mesa: viewing an old disease in a new light. Biophys Rev 2017; 10:27-48. [PMID: 28717924 PMCID: PMC5803174 DOI: 10.1007/s12551-017-0274-6] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 06/12/2017] [Indexed: 12/15/2022] Open
Abstract
The sarcomere is an exquisitely designed apparatus that is capable of generating force, which in the case of the heart results in the pumping of blood throughout the body. At the molecular level, an ATP-dependent interaction of myosin with actin drives the contraction and force generation of the sarcomere. Over the past six decades, work on muscle has yielded tremendous insights into the workings of the sarcomeric system. We now stand on the cusp where the acquired knowledge of how the sarcomere contracts and how that contraction is regulated can be extended to an understanding of the molecular mechanisms of sarcomeric diseases, such as hypertrophic cardiomyopathy (HCM). In this review we present a picture that combines current knowledge of the myosin mesa, the sequestered state of myosin heads on the thick filament, known as the interacting-heads motif (IHM), their possible interaction with myosin binding protein C (MyBP-C) and how these interactions can be abrogated leading to hyper-contractility, a key clinical manifestation of HCM. We discuss the structural and functional basis of the IHM state of the myosin heads and identify HCM-causing mutations that can directly impact the equilibrium between the 'on state' of the myosin heads (the open state) and the IHM 'off state'. We also hypothesize a role of MyBP-C in helping to maintain myosin heads in the IHM state on the thick filament, allowing release in a graded manner upon adrenergic stimulation. By viewing clinical hyper-contractility as the result of the destabilization of the IHM state, our aim is to view an old disease in a new light.
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Affiliation(s)
- Darshan V Trivedi
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Arjun S Adhikari
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Saswata S Sarkar
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Kathleen M Ruppel
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA. .,Department of Pediatrics (Cardiology), Stanford University School of Medicine, Stanford, CA, 94305, USA.
| | - James A Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA.
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29
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The myosin mesa and the basis of hypercontractility caused by hypertrophic cardiomyopathy mutations. Nat Struct Mol Biol 2017; 24:525-533. [PMID: 28481356 DOI: 10.1038/nsmb.3408] [Citation(s) in RCA: 149] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 04/05/2017] [Indexed: 12/12/2022]
Abstract
Hypertrophic cardiomyopathy (HCM) is primarily caused by mutations in β-cardiac myosin and myosin-binding protein-C (MyBP-C). Changes in the contractile parameters of myosin measured so far do not explain the clinical hypercontractility caused by such mutations. We propose that hypercontractility is due to an increase in the number of myosin heads (S1) that are accessible for force production. In support of this hypothesis, we demonstrate myosin tail (S2)-dependent functional regulation of actin-activated human β-cardiac myosin ATPase. In addition, we show that both S2 and MyBP-C bind to S1 and that phosphorylation of either S1 or MyBP-C weakens these interactions. Importantly, the S1-S2 interaction is also weakened by four myosin HCM-causing mutations but not by two other mutations. To explain these experimental results, we propose a working structural model involving multiple interactions, including those with myosin's own S2 and MyBP-C, that hold myosin in a sequestered state.
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30
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Gregorich ZR, Cai W, Lin Z, Chen AJ, Peng Y, Kohmoto T, Ge Y. Distinct sequences and post-translational modifications in cardiac atrial and ventricular myosin light chains revealed by top-down mass spectrometry. J Mol Cell Cardiol 2017; 107:13-21. [PMID: 28427997 DOI: 10.1016/j.yjmcc.2017.04.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 04/15/2017] [Indexed: 01/01/2023]
Abstract
Myosin is the principal component of the thick filaments that, through interactions with the actin thin filaments, mediates force production during muscle contraction. Myosin is a hexamer, consisting of two heavy chains, each associated with an essential (ELC) and a regulatory (RLC) light chain, which bind the lever-arm of the heavy chain and play important modulatory roles in striated muscle contraction. Nevertheless, a comprehensive assessment of the sequences of the ELC and RLC isoforms, as well as their post-translational modifications, in the heart remains lacking. Herein, utilizing top-down high-resolution mass spectrometry (MS), we have comprehensively characterized the sequences and N-terminal modifications of the atrial and ventricular isoforms of the myosin light chains from human and swine hearts, as well as the sites of phosphorylation in the swine proteins. In addition to the correction of disparities in the database sequences of the swine proteins, we show for the first time that, whereas the ventricular isoforms of the ELC and RLC are methylated at their N-termini, which is consistent with previous studies, the atrial isoforms of the ELC and RLC from both human and swine are Nα-methylated and Nα-acetylated, respectively. Furthermore, top-down MS with electron capture dissociation enabled localization of the sites of phosphorylation in swine RLC isoforms from the ventricles and atria to Ser14 and Ser22, respectively. Collectively, these results provide new insights into the sequences and modifications of myosin light chain isoforms in the human and swine hearts, which will pave the way for a better understanding of their functional roles in cardiac physiology and pathophysiology.
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Affiliation(s)
- Zachery R Gregorich
- 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
| | - Wenxuan Cai
- 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
| | - Ziqing Lin
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Albert J Chen
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Ying Peng
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Takushi Kohmoto
- Department of Surgery, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Ying Ge
- 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, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA.
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31
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Dhar K, Moulton AM, Rome E, Qiu F, Kittrell J, Raichlin E, Zolty R, Um JY, Moulton MJ, Basma H, Anderson DR, Eudy JD, Lowes BD. Targeted myocardial gene expression in failing hearts by RNA sequencing. J Transl Med 2016; 14:327. [PMID: 27884156 PMCID: PMC5123412 DOI: 10.1186/s12967-016-1083-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 11/14/2016] [Indexed: 11/20/2022] Open
Abstract
Background Myocardial recovery with left ventricular assist device (LVAD) therapy is highly variable and difficult to predict. Next generation ribonucleic acid (RNA) sequencing is an innovative, rapid, and quantitative approach to gene expression profiling in small amounts of tissue. Our primary goal was to identify baseline transcriptional profiles in non-ischemic cardiomyopathies that predict myocardial recovery in response to LVAD therapy. We also sought to verify transcriptional differences between failing and non-failing human hearts. Methods RNA was isolated from failing (n = 16) and non-failing (n = 8) human hearts. RNA from each patient was reverse transcribed and quantitatively sequenced on the personal genome machine (PGM) sequencer (Ion torrent) for 95 heart failure candidate genes. Coverage analysis as well as mapping the reads and alignment was done using the Ion Torrent Browser Suite™. Differential expression analyses were conducted by empirical analysis of digital gene expression data in R (edgeR) to identify differential expressed genes between failing and non-failing groups, and between responder and non-responder groups respectively. Targeted cardiac gene messenger RNA (mRNA) expression was analyzed in proportion to the total number of reads. Gene expression profiles from the PGM sequencer were validated by performing RNA sequencing (RNAseq) with the Illumina Hiseq2500 sequencing system. Results The failing sample population was 75% male with an average age of 50 and a left ventricular ejection fraction (LVEF) of 16%. Myosin light chain kinase (MYLK) and interleukin (IL)-6 genes expression were significantly higher in LVAD responders compared to non-responders. Thirty-six cardiac genes were expressed differentially between failing and non-failing hearts (23 decreased, 13 elevated). MYLK, Beta-1 adrenergic receptor (ADRB1) and myosin heavy chain (MYH)-6 expression were among those significantly decreased in failing hearts compared to non-failing hearts. Natriuretic peptide B (NPPB) and IL-6 were significantly elevated. Targeted gene expression profiles obtained from the Ion torrent PGM sequencer were consistent with those obtained from Illumina HiSeq2500 sequencing system. Conclusions Heart failure is associated with a network of transcriptional changes involving contractile proteins, metabolism, adrenergic receptors, protein phosphorylation, and signaling factors. Myocardial MYLK and IL-6 expression are positively correlated with ejection fraction (EF) response to LVAD placement. Targeted RNA sequencing of myocardial gene expression can be utilized to predict responders to LVAD therapy and to better characterize transcriptional changes in human heart failure.
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Affiliation(s)
- Kajari Dhar
- Department of Internal Medicine, University of Nebraska Medical Center, 982265 Nebraska Medical Center, Omaha, NE, 68198-2265, USA
| | - Alexandra M Moulton
- Department of Internal Medicine, University of Nebraska Medical Center, 982265 Nebraska Medical Center, Omaha, NE, 68198-2265, USA
| | - Eric Rome
- Department of Internal Medicine, University of Nebraska Medical Center, 982265 Nebraska Medical Center, Omaha, NE, 68198-2265, USA
| | - Fang Qiu
- Department of Biostatistics, University of Nebraska Medical Center, Omaha, USA
| | - Jeff Kittrell
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, USA
| | - Eugenia Raichlin
- Department of Internal Medicine, University of Nebraska Medical Center, 982265 Nebraska Medical Center, Omaha, NE, 68198-2265, USA
| | - Ronald Zolty
- Department of Internal Medicine, University of Nebraska Medical Center, 982265 Nebraska Medical Center, Omaha, NE, 68198-2265, USA
| | - John Y Um
- Department of Cardiothoracic Surgery, University of Nebraska Medical Center, Omaha, USA
| | - Michael J Moulton
- Department of Cardiothoracic Surgery, University of Nebraska Medical Center, Omaha, USA
| | - Hesham Basma
- Department of Internal Medicine, University of Nebraska Medical Center, 982265 Nebraska Medical Center, Omaha, NE, 68198-2265, USA
| | - Daniel R Anderson
- Department of Internal Medicine, University of Nebraska Medical Center, 982265 Nebraska Medical Center, Omaha, NE, 68198-2265, USA
| | - James D Eudy
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, USA
| | - Brian D Lowes
- Department of Internal Medicine, University of Nebraska Medical Center, 982265 Nebraska Medical Center, Omaha, NE, 68198-2265, USA.
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32
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Carruth ED, McCulloch AD, Omens JH. Transmural gradients of myocardial structure and mechanics: Implications for fiber stress and strain in pressure overload. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 122:215-226. [PMID: 27845176 DOI: 10.1016/j.pbiomolbio.2016.11.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Although a truly complete understanding of whole heart activation, contraction, and deformation is well beyond our current reach, a significant amount of effort has been devoted to discovering and understanding the mechanisms by which myocardial structure determines cardiac function to better treat patients with cardiac disease. Several experimental studies have shown that transmural fiber strain is relatively uniform in both diastole and systole, in contrast to predictions from traditional mechanical theory. Similarly, mathematical models have largely predicted uniform fiber stress across the wall. The development of this uniform pattern of fiber stress and strain during filling and ejection is due to heterogeneous transmural distributions of several myocardial structures. This review summarizes these transmural gradients, their contributions to fiber mechanics, and the potential functional effects of their remodeling during pressure overload hypertrophy.
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Affiliation(s)
- Eric D Carruth
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.
| | - Andrew D McCulloch
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.
| | - Jeffrey H Omens
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA; Department of Medicine, University of California San Diego, La Jolla, CA, USA.
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Chang AN, Kamm KE, Stull JT. Role of myosin light chain phosphatase in cardiac physiology and pathophysiology. J Mol Cell Cardiol 2016; 101:35-43. [PMID: 27742556 DOI: 10.1016/j.yjmcc.2016.10.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 10/07/2016] [Accepted: 10/10/2016] [Indexed: 11/18/2022]
Abstract
Maintenance of contractile performance of the heart is achieved in part by the constitutive 40% phosphorylation of myosin regulatory light chain (RLC) in sarcomeres. The importance of this extent of RLC phosphorylation for optimal cardiac performance becomes apparent when various mouse models and resultant phenotypes are compared. The absence or attenuation of RLC phosphorylation results in poor performance leading to heart failure, whereas increased RLC phosphorylation is associated with cardiac protection from stresses. Although information is limited, RLC phosphorylation appears compromised in human heart failure which is consistent with data from mouse studies. The extent of cardiac RLC phosphorylation is determined by the balanced activities of cardiac myosin light chain kinases and phosphatases, the regulatory mechanisms of which are now emerging. This review thusly focuses on kinases that may participate in phosphorylating RLC to make the substrate for cardiac myosin light chain phosphatases, in addition to providing perspectives on the family of myosin light chain phosphatases and involved signaling mechanisms. Because biochemical and physiological information about cardiac myosin light chain phosphatase is sparse, such studies represent an emerging area of investigation in health and disease.
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Affiliation(s)
- Audrey N Chang
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Kristine E Kamm
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - James T Stull
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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Toepfer CN, Sikkel MB, Caorsi V, Vydyanath A, Torre I, Copeland O, Lyon AR, Marston SB, Luther PK, Macleod KT, West TG, Ferenczi MA. A post-MI power struggle: adaptations in cardiac power occur at the sarcomere level alongside MyBP-C and RLC phosphorylation. Am J Physiol Heart Circ Physiol 2016; 311:H465-75. [PMID: 27233767 PMCID: PMC5005282 DOI: 10.1152/ajpheart.00899.2015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 05/24/2016] [Indexed: 01/25/2023]
Abstract
Myocardial remodeling in response to chronic myocardial infarction (CMI) progresses through two phases, hypertrophic "compensation" and congestive "decompensation." Nothing is known about the ability of uninfarcted myocardium to produce force, velocity, and power during these clinical phases, even though adaptation in these regions likely drives progression of compensation. We hypothesized that enhanced cross-bridge-level contractility underlies mechanical compensation and is controlled in part by changes in the phosphorylation states of myosin regulatory proteins. We induced CMI in rats by left anterior descending coronary artery ligation. We then measured mechanical performance in permeabilized ventricular trabecula taken distant from the infarct zone and assayed myosin regulatory protein phosphorylation in each individual trabecula. During full activation, the compensated myocardium produced twice as much power and 31% greater isometric force compared with noninfarcted controls. Isometric force during submaximal activations was raised >2.4-fold, while power was 2-fold greater. Electron and confocal microscopy demonstrated that these mechanical changes were not a result of increased density of contractile protein and therefore not an effect of tissue hypertrophy. Hence, sarcomere-level contractile adaptations are key determinants of enhanced trabecular mechanics and of the overall cardiac compensatory response. Phosphorylation of myosin regulatory light chain (RLC) increased and remained elevated post-MI, while phosphorylation of myosin binding protein-C (MyBP-C) was initially depressed but then increased as the hearts became decompensated. These sensitivities to CMI are in accordance with phosphorylation-dependent regulatory roles for RLC and MyBP-C in crossbridge function and with compensatory adaptation in force and power that we observed in post-CMI trabeculae.
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Affiliation(s)
- Christopher N Toepfer
- Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom; Laboratory of Molecular Physiology, National Heart and Lung Institute, National Institutes of Health, Bethesda, Maryland;
| | - Markus B Sikkel
- Department of Cardiac Medicine, National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Valentina Caorsi
- Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom; Laboratoire Physico-Chimie, UMR168, Institute Curie, Paris, France
| | - Anupama Vydyanath
- Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Iratxe Torre
- Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - O'Neal Copeland
- Department of Cardiac Medicine, National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Alexander R Lyon
- Department of Cardiac Medicine, National Heart and Lung Institute, Imperial College London, London, United Kingdom; Nationa Institute of Health Research Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom
| | - Steven B Marston
- Department of Cardiac Medicine, National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Pradeep K Luther
- Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Kenneth T Macleod
- Department of Cardiac Medicine, National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Timothy G West
- Royal Veterinary College London, Structure & Motion Laboratory, North Mymms, United Kingdom; and
| | - Michael A Ferenczi
- Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom; Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
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Toepfer CN, West TG, Ferenczi MA. Revisiting Frank-Starling: regulatory light chain phosphorylation alters the rate of force redevelopment (ktr ) in a length-dependent fashion. J Physiol 2016; 594:5237-54. [PMID: 27291932 PMCID: PMC5023691 DOI: 10.1113/jp272441] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 06/01/2016] [Indexed: 11/24/2022] Open
Abstract
Key points Regulatory light chain (RLC) phosphorylation has been shown to alter the ability of muscle to produce force and power during shortening and to alter the rate of force redevelopment (ktr) at submaximal [Ca2+]. Increasing RLC phosphorylation ∼50% from the in vivo level in maximally [Ca2+]‐activated cardiac trabecula accelerates ktr. Decreasing RLC phosphorylation to ∼70% of the in vivo control level slows ktr and reduces force generation. ktr is dependent on sarcomere length in the physiological range 1.85–1.94 μm and RLC phosphorylation modulates this response. We demonstrate that Frank–Starling is evident at maximal [Ca2+] activation and therefore does not necessarily require length‐dependent change in [Ca2+]‐sensitivity of thin filament activation. The stretch response is modulated by changes in RLC phosphorylation, pinpointing RLC phosphorylation as a modulator of the Frank–Starling law in the heart. These data provide an explanation for slowed systolic function in the intact heart in response to RLC phosphorylation reduction.
Abstract Force and power in cardiac muscle have a known dependence on phosphorylation of the myosin‐associated regulatory light chain (RLC). We explore the effect of RLC phosphorylation on the ability of cardiac preparations to redevelop force (ktr) in maximally activating [Ca2+]. Activation was achieved by rapidly increasing the temperature (temperature‐jump of 0.5–20ºC) of permeabilized trabeculae over a physiological range of sarcomere lengths (1.85–1.94 μm). The trabeculae were subjected to shortening ramps over a range of velocities and the extent of RLC phosphorylation was varied. The latter was achieved using an RLC‐exchange technique, which avoids changes in the phosphorylation level of other proteins. The results show that increasing RLC phosphorylation by 50% accelerates ktr by ∼50%, irrespective of the sarcomere length, whereas decreasing phosphorylation by 30% slows ktr by ∼50%, relative to the ktr obtained for in vivo phosphorylation. Clearly, phosphorylation affects the magnitude of ktr following step shortening or ramp shortening. Using a two‐state model, we explore the effect of RLC phosphorylation on the kinetics of force development, which proposes that phosphorylation affects the kinetics of both attachment and detachment of cross‐bridges. In summary, RLC phosphorylation affects the rate and extent of force redevelopment. These findings were obtained in maximally activated muscle at saturating [Ca2+] and are not explained by changes in the Ca2+‐sensitivity of acto‐myosin interactions. The length‐dependence of the rate of force redevelopment, together with the modulation by the state of RLC phosphorylation, suggests that these effects play a role in the Frank–Starling law of the heart. Regulatory light chain (RLC) phosphorylation has been shown to alter the ability of muscle to produce force and power during shortening and to alter the rate of force redevelopment (ktr) at submaximal [Ca2+]. Increasing RLC phosphorylation ∼50% from the in vivo level in maximally [Ca2+]‐activated cardiac trabecula accelerates ktr. Decreasing RLC phosphorylation to ∼70% of the in vivo control level slows ktr and reduces force generation. ktr is dependent on sarcomere length in the physiological range 1.85–1.94 μm and RLC phosphorylation modulates this response. We demonstrate that Frank–Starling is evident at maximal [Ca2+] activation and therefore does not necessarily require length‐dependent change in [Ca2+]‐sensitivity of thin filament activation. The stretch response is modulated by changes in RLC phosphorylation, pinpointing RLC phosphorylation as a modulator of the Frank–Starling law in the heart. These data provide an explanation for slowed systolic function in the intact heart in response to RLC phosphorylation reduction.
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Affiliation(s)
- Christopher N Toepfer
- Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, London, UK. .,Laboratory of Molecular Physiology, NHLBI, National Institutes of Health, Bethesda, MD, USA.
| | - Timothy G West
- Structure & Motion Laboratory, Royal Veterinary College London, North Mymms, UK
| | - Michael A Ferenczi
- Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, London, UK.,Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
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Milani-Nejad N, Chung JH, Canan BD, Davis JP, Fedorov VV, Higgins RSD, Kilic A, Mohler PJ, Janssen PML. Insights into length-dependent regulation of cardiac cross-bridge cycling kinetics in human myocardium. Arch Biochem Biophys 2016; 601:48-55. [PMID: 26854725 PMCID: PMC4899103 DOI: 10.1016/j.abb.2016.02.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 01/29/2016] [Accepted: 02/02/2016] [Indexed: 11/16/2022]
Abstract
Cross-bridge cycling kinetics play an essential role in the heart's ability to contract and relax. The rate of tension redevelopment (ktr) slows down as a muscle length is increased in intact human myocardium. We set out to determine the effect of rapid length step changes and protein kinase A (PKA) and protein kinase C-βII (PKC-βII) inhibitors on the ktr in ultra-thin non-failing and failing human right ventricular trabeculae. After stabilizing the muscle either at L90 (90% of optimal length) or at Lopt (optimal length), we rapidly changed the length to either Lopt or L90 and measured ktr. We report that length-dependent changes in ktr occur very rapidly (in the order of seconds or faster) in both non-failing and failing muscles and that the length at which a muscle had been stabilized prior to the length change does not significantly affect ktr. In addition, at L90 and at Lopt, PKA and PKC-βII inhibitors did not significantly change ktr. Our results reveal that length-dependent regulation of cross-bridge cycling kinetics predominantly occurs rapidly and involves the intrinsic properties of the myofilament rather than post-translational modifications that are known to occur in the cardiac muscle as a result of a change in muscle/sarcomere length.
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Affiliation(s)
- Nima Milani-Nejad
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, USA; Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, USA; Medical Scientist Training Program and Biomedical Sciences Graduate Program, The Ohio State University Wexner Medical Center, USA
| | - Jae-Hoon Chung
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, USA; Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, USA; Medical Scientist Training Program and Biomedical Sciences Graduate Program, The Ohio State University Wexner Medical Center, USA
| | - Benjamin D Canan
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, USA; Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, USA
| | - Jonathan P Davis
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, USA; Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, USA
| | - Vadim V Fedorov
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, USA; Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, USA
| | - Robert S D Higgins
- Department of Surgery, Division of Cardiac Surgery, The Ohio State University Wexner Medical Center, USA
| | - Ahmet Kilic
- Department of Surgery, Division of Cardiac Surgery, The Ohio State University Wexner Medical Center, USA
| | - Peter J Mohler
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, USA; Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, USA; Department of Internal Medicine, The Ohio State University Wexner Medical Center, USA
| | - Paul M L Janssen
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, USA; Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, USA; Department of Internal Medicine, The Ohio State University Wexner Medical Center, USA.
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Cardiac myosin light chain is phosphorylated by Ca2+/calmodulin-dependent and -independent kinase activities. Proc Natl Acad Sci U S A 2016; 113:E3824-33. [PMID: 27325775 DOI: 10.1073/pnas.1600633113] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The well-known, muscle-specific smooth muscle myosin light chain kinase (MLCK) (smMLCK) and skeletal muscle MLCK (skMLCK) are dedicated protein kinases regulated by an autoregulatory segment C terminus of the catalytic core that blocks myosin regulatory light chain (RLC) binding and phosphorylation in the absence of Ca(2+)/calmodulin (CaM). Although it is known that a more recently discovered cardiac MLCK (cMLCK) is necessary for normal RLC phosphorylation in vivo and physiological cardiac performance, information on cMLCK biochemical properties are limited. We find that a fourth uncharacterized MLCK, MLCK4, is also expressed in cardiac muscle with high catalytic domain sequence similarity with other MLCKs but lacking an autoinhibitory segment. Its crystal structure shows the catalytic domain in its active conformation with a short C-terminal "pseudoregulatory helix" that cannot inhibit catalysis as a result of missing linker regions. MLCK4 has only Ca(2+)/CaM-independent activity with comparable Vmax and Km values for different RLCs. In contrast, the Vmax value of cMLCK is orders of magnitude lower than those of the other three MLCK family members, whereas its Km (RLC and ATP) and KCaM values are similar. In contrast to smMLCK and skMLCK, which lack activity in the absence of Ca(2+)/CaM, cMLCK has constitutive activity that is stimulated by Ca(2+)/CaM. Potential contributions of autoregulatory segment to cMLCK activity were analyzed with chimeras of skMLCK and cMLCK. The constitutive, low activity of cMLCK appears to be intrinsic to its catalytic core structure rather than an autoinhibitory segment. Thus, RLC phosphorylation in cardiac muscle may be regulated by two different protein kinases with distinct biochemical regulatory properties.
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Abstract
The myosin holoenzyme is a multimeric protein complex consisting of heavy chains and light chains. Myosin light chains are calmodulin family members which are crucially involved in the mechanoenzymatic function of the myosin holoenzyme. This review examines the diversity of light chains within the myosin superfamily, discusses interactions between the light chain and the myosin heavy chain as well as regulatory and structural functions of the light chain as a subunit of the myosin holoenzyme. It covers aspects of the myosin light chain in the localization of the myosin holoenzyme, protein-protein interactions and light chain binding to non-myosin binding partners. Finally, this review challenges the dogma that myosin regulatory and essential light chain exclusively associate with conventional myosin heavy chains while unconventional myosin heavy chains usually associate with calmodulin.
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Affiliation(s)
- Sarah M Heissler
- a Laboratory of Molecular Physiology; National Heart, Lung, and Blood Institute; National Institutes of Health ; Bethesda , MD USA
| | - James R Sellers
- a Laboratory of Molecular Physiology; National Heart, Lung, and Blood Institute; National Institutes of Health ; Bethesda , MD USA
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39
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Yu H, Chakravorty S, Song W, Ferenczi MA. Phosphorylation of the regulatory light chain of myosin in striated muscle: methodological perspectives. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2016; 45:779-805. [PMID: 27084718 PMCID: PMC5101276 DOI: 10.1007/s00249-016-1128-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 03/10/2016] [Accepted: 03/23/2016] [Indexed: 12/18/2022]
Abstract
Phosphorylation of the regulatory light chain (RLC) of myosin modulates cellular functions such as muscle contraction, mitosis, and cytokinesis. Phosphorylation defects are implicated in a number of diseases. Here we focus on striated muscle where changes in RLC phosphorylation relate to diseases such as hypertrophic cardiomyopathy and muscular dystrophy, or age-related changes. RLC phosphorylation in smooth muscle and non-muscle cells are covered briefly where relevant. There is much scientific interest in controlling the phosphorylation levels of RLC in vivo and in vitro in order to understand its physiological function in striated muscles. A summary of available and emerging in vivo and in vitro methods is presented. The physiological role of RLC phosphorylation and novel pathways are discussed to highlight the differences between muscle types and to gain insights into disease processes.
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Affiliation(s)
- Haiyang Yu
- Lee Kong Chian School of Medicine, Nanyang Technological University, Experimental Medicine Building, Level 3, 59 Nanyang Drive, Singapore, 636921, Singapore
| | - Samya Chakravorty
- Lee Kong Chian School of Medicine, Nanyang Technological University, Experimental Medicine Building, Level 3, 59 Nanyang Drive, Singapore, 636921, Singapore
| | - Weihua Song
- Lee Kong Chian School of Medicine, Nanyang Technological University, Experimental Medicine Building, Level 3, 59 Nanyang Drive, Singapore, 636921, Singapore
| | - Michael A Ferenczi
- Lee Kong Chian School of Medicine, Nanyang Technological University, Experimental Medicine Building, Level 3, 59 Nanyang Drive, Singapore, 636921, Singapore.
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40
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Heissler SM, Sellers JR. Various Themes of Myosin Regulation. J Mol Biol 2016; 428:1927-46. [PMID: 26827725 DOI: 10.1016/j.jmb.2016.01.022] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 01/12/2016] [Accepted: 01/19/2016] [Indexed: 10/24/2022]
Abstract
Members of the myosin superfamily are actin-based molecular motors that are indispensable for cellular homeostasis. The vast functional and structural diversity of myosins accounts for the variety and complexity of the underlying allosteric regulatory mechanisms that determine the activation or inhibition of myosin motor activity and enable precise timing and spatial aspects of myosin function at the cellular level. This review focuses on the molecular basis of posttranslational regulation of eukaryotic myosins from different classes across species by allosteric intrinsic and extrinsic effectors. First, we highlight the impact of heavy and light chain phosphorylation. Second, we outline intramolecular regulatory mechanisms such as autoinhibition and subsequent activation. Third, we discuss diverse extramolecular allosteric mechanisms ranging from actin-linked regulatory mechanisms to myosin:cargo interactions. At last, we briefly outline the allosteric regulation of myosins with synthetic compounds.
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Affiliation(s)
- Sarah M Heissler
- Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, 50 South Drive, B50/3529, Bethesda, MD 20892-8015, USA.
| | - James R Sellers
- Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, 50 South Drive, B50/3529, Bethesda, MD 20892-8015, USA
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41
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Wang Y, Ajtai K, Kazmierczak K, Szczesna-Cordary D, Burghardt TP. N-Terminus of Cardiac Myosin Essential Light Chain Modulates Myosin Step-Size. Biochemistry 2015; 55:186-98. [PMID: 26671638 DOI: 10.1021/acs.biochem.5b00817] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Muscle myosin cyclically hydrolyzes ATP to translate actin. Ventricular cardiac myosin (βmys) moves actin with three distinct unitary step-sizes resulting from its lever-arm rotation and with step-frequencies that are modulated in a myosin regulation mechanism. The lever-arm associated essential light chain (vELC) binds actin by its 43 residue N-terminal extension. Unitary steps were proposed to involve the vELC N-terminal extension with the 8 nm step engaging the vELC/actin bond facilitating an extra ∼19 degrees of lever-arm rotation while the predominant 5 nm step forgoes vELC/actin binding. A minor 3 nm step is the unlikely conversion of the completed 5 to the 8 nm step. This hypothesis was tested using a 17 residue N-terminal truncated vELC in porcine βmys (Δ17βmys) and a 43 residue N-terminal truncated human vELC expressed in transgenic mouse heart (Δ43αmys). Step-size and step-frequency were measured using the Qdot motility assay. Both Δ17βmys and Δ43αmys had significantly increased 5 nm step-frequency and coincident loss in the 8 nm step-frequency compared to native proteins suggesting the vELC/actin interaction drives step-size preference. Step-size and step-frequency probability densities depend on the relative fraction of truncated vELC and relate linearly to pure myosin species concentrations in a mixture containing native vELC homodimer, two truncated vELCs in the modified homodimer, and one native and one truncated vELC in the heterodimer. Step-size and step-frequency, measured for native homodimer and at two or more known relative fractions of truncated vELC, are surmised for each pure species by using a new analytical method.
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Affiliation(s)
| | | | - Katarzyna Kazmierczak
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine , Miami, Florida 33136, United States
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine , Miami, Florida 33136, United States
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Burghardt TP, Sun X, Wang Y, Ajtai K. In vitro and in vivo single myosin step-sizes in striated muscle. J Muscle Res Cell Motil 2015; 36:463-77. [PMID: 26728749 PMCID: PMC4764389 DOI: 10.1007/s10974-015-9440-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 12/11/2015] [Indexed: 10/22/2022]
Abstract
Myosin in muscle transduces ATP free energy into the mechanical work of moving actin. It has a motor domain transducer containing ATP and actin binding sites, and, mechanical elements coupling motor impulse to the myosin filament backbone providing transduction/mechanical-coupling. The mechanical coupler is a lever-arm stabilized by bound essential and regulatory light chains. The lever-arm rotates cyclically to impel bound filamentous actin. Linear actin displacement due to lever-arm rotation is the myosin step-size. A high-throughput quantum dot labeled actin in vitro motility assay (Qdot assay) measures motor step-size in the context of an ensemble of actomyosin interactions. The ensemble context imposes a constant velocity constraint for myosins interacting with one actin filament. In a cardiac myosin producing multiple step-sizes, a "second characterization" is step-frequency that adjusts longer step-size to lower frequency maintaining a linear actin velocity identical to that from a shorter step-size and higher frequency actomyosin cycle. The step-frequency characteristic involves and integrates myosin enzyme kinetics, mechanical strain, and other ensemble affected characteristics. The high-throughput Qdot assay suits a new paradigm calling for wide surveillance of the vast number of disease or aging relevant myosin isoforms that contrasts with the alternative model calling for exhaustive research on a tiny subset myosin forms. The zebrafish embryo assay (Z assay) performs single myosin step-size and step-frequency assaying in vivo combining single myosin mechanical and whole muscle physiological characterizations in one model organism. The Qdot and Z assays cover "bottom-up" and "top-down" assaying of myosin characteristics.
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Affiliation(s)
- Thomas P Burghardt
- Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester, Rochester, MN, 55905, USA.
- Department of Physiology and Biomedical Engineering, Mayo Clinic Rochester, Rochester, MN, 55905, USA.
| | - Xiaojing Sun
- Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester, Rochester, MN, 55905, USA
| | - Yihua Wang
- Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester, Rochester, MN, 55905, USA
| | - Katalin Ajtai
- Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester, Rochester, MN, 55905, USA
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Ntelios D, Tzimagiorgis G, Efthimiadis GK, Karvounis H. Mechanical aberrations in hypetrophic cardiomyopathy: emerging concepts. Front Physiol 2015; 6:232. [PMID: 26347658 PMCID: PMC4541419 DOI: 10.3389/fphys.2015.00232] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 08/03/2015] [Indexed: 11/13/2022] Open
Abstract
Hypertrophic cardiomyopathy is the most common monogenic disorder in cardiology. Despite important advances in understanding disease pathogenesis, it is not clear how flaws in individual sarcomere components are responsible for the observed phenotype. The aim of this article is to provide a brief interpretative analysis of some currently proposed pathophysiological mechanisms of hypertrophic cardiomyopathy, with a special emphasis on alterations in the cardiac mechanical properties.
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Affiliation(s)
- Dimitrios Ntelios
- Laboratory of Biological Chemistry, Medical School, Aristotle University of Thessaloniki Thessaloniki, Greece ; Department of Cardiology, AHEPA University Hospital Thessaloniki, Greece
| | - Georgios Tzimagiorgis
- Laboratory of Biological Chemistry, Medical School, Aristotle University of Thessaloniki Thessaloniki, Greece
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44
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Karabina A, Kazmierczak K, Szczesna-Cordary D, Moore JR. Myosin regulatory light chain phosphorylation enhances cardiac β-myosin in vitro motility under load. Arch Biochem Biophys 2015; 580:14-21. [PMID: 26116789 PMCID: PMC4790447 DOI: 10.1016/j.abb.2015.06.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 05/27/2015] [Accepted: 06/21/2015] [Indexed: 12/15/2022]
Abstract
Familial hypertrophic cardiomyopathy (HCM) is characterized by left ventricular hypertrophy and myofibrillar disarray, and often results in sudden cardiac death. Two HCM mutations, N47K and R58Q, are located in the myosin regulatory light chain (RLC). The RLC mechanically stabilizes the myosin lever arm, which is crucial to myosin's ability to transmit contractile force. The N47K and R58Q mutations have previously been shown to reduce actin filament velocity under load, stemming from a more compliant lever arm (Greenberg, 2010). In contrast, RLC phosphorylation was shown to impart stiffness to the myosin lever arm (Greenberg, 2009). We hypothesized that phosphorylation of the mutant HCM-RLC may mitigate distinct mutation-induced structural and functional abnormalities. In vitro motility assays were utilized to investigate the effects of RLC phosphorylation on the HCM-RLC mutant phenotype in the presence of an α-actinin frictional load. Porcine cardiac β-myosin was depleted of its native RLC and reconstituted with mutant or wild-type human RLC in phosphorylated or non-phosphorylated form. Consistent with previous findings, in the presence of load, myosin bearing the HCM mutations reduced actin sliding velocity compared to WT resulting in 31-41% reductions in force production. Myosin containing phosphorylated RLC (WT or mutant) increased sliding velocity and also restored mutant myosin force production to near WT unphosphorylated values. These results point to RLC phosphorylation as a general mechanism to increase force production of the individual myosin motor and as a potential target to ameliorate the HCM-induced phenotype at the molecular level.
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Affiliation(s)
- Anastasia Karabina
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA, USA
| | - Katarzyna Kazmierczak
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Jeffrey R Moore
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA, USA.
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Huang W, Liang J, Yuan CC, Kazmierczak K, Zhou Z, Morales A, McBride KL, Fitzgerald-Butt SM, Hershberger RE, Szczesna-Cordary D. Novel familial dilated cardiomyopathy mutation in MYL2 affects the structure and function of myosin regulatory light chain. FEBS J 2015; 282:2379-93. [PMID: 25825243 DOI: 10.1111/febs.13286] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 02/27/2015] [Accepted: 03/26/2015] [Indexed: 01/16/2023]
Abstract
Dilated cardiomyopathy (DCM) is a disease of the myocardium characterized by left ventricular dilatation and diminished contractile function. Here we describe a novel DCM mutation in the myosin regulatory light chain (RLC), in which aspartic acid at position 94 is replaced by alanine (D94A). The mutation was identified by exome sequencing of three adult first-degree relatives who met formal criteria for idiopathic DCM. To obtain insight into the functional significance of this pathogenic MYL2 variant, we cloned and purified the human ventricular RLC wild-type (WT) and D94A mutant proteins, and performed in vitro experiments using RLC-mutant or WT-reconstituted porcine cardiac preparations. The mutation induced a reduction in the α-helical content of the RLC, and imposed intra-molecular rearrangements. The phosphorylation of RLC by Ca²⁺/calmodulin-activated myosin light chain kinase was not affected by D94A. The mutation was seen to impair binding of RLC to the myosin heavy chain, and its incorporation into RLC-depleted porcine myosin. The actin-activated ATPase activity of mutant-reconstituted porcine cardiac myosin was significantly higher compared with ATPase of wild-type. No changes in the myofibrillar ATPase-pCa relationship were observed in wild-type- or D94A-reconstituted preparations. Measurements of contractile force showed a slightly reduced maximal tension per cross-section of muscle, with no change in the calcium sensitivity of force in D94A-reconstituted skinned porcine papillary muscle strips compared with wild-type. Our data indicate that subtle structural rearrangements in the RLC molecule, followed by its impaired interaction with the myosin heavy chain, may trigger functional abnormalities contributing to the DCM phenotype.
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Affiliation(s)
- Wenrui Huang
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Jingsheng Liang
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Chen-Ching Yuan
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Katarzyna Kazmierczak
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Zhiqun Zhou
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Ana Morales
- Division of Human Genetics, Department of Internal Medicine, Wexner Medical Center, Ohio State University, Columbus, OH, USA
| | - Kim L McBride
- Department of Pediatrics Ohio State University, Center for Cardiovascular and Pulmonary Research, Nationwide Children's Hospital, Columbus, OH, USA
| | - Sara M Fitzgerald-Butt
- Department of Pediatrics Ohio State University, Center for Cardiovascular and Pulmonary Research, Nationwide Children's Hospital, Columbus, OH, USA
| | - Ray E Hershberger
- Division of Human Genetics, Department of Internal Medicine, Wexner Medical Center, Ohio State University, Columbus, OH, USA
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, USA
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The R21C Mutation in Cardiac Troponin I Imposes Differences in Contractile Force Generation between the Left and Right Ventricles of Knock-In Mice. BIOMED RESEARCH INTERNATIONAL 2015; 2015:742536. [PMID: 25961037 PMCID: PMC4415466 DOI: 10.1155/2015/742536] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 12/16/2014] [Accepted: 12/19/2014] [Indexed: 01/20/2023]
Abstract
We investigated the effect of the hypertrophic cardiomyopathy-linked R21C (arginine to cysteine) mutation in human cardiac troponin I (cTnI) on the contractile properties and myofilament protein phosphorylation in papillary muscle preparations from left (LV) and right (RV) ventricles of homozygous R21C(+/+) knock-in mice. The maximal steady-state force was significantly reduced in skinned papillary muscle strips from the LV compared to RV, with the latter displaying the level of force observed in LV or RV from wild-type (WT) mice. There were no differences in the Ca(2+) sensitivity between the RV and LV of R21C(+/+) mice; however, the Ca(2+) sensitivity of force was higher in RV-R21C(+/+) compared with RV-WT and lower in LV- R21C(+/+) compared with LV-WT. We also observed partial loss of Ca(2+) regulation at low [Ca(2+)]. In addition, R21C(+/+)-KI hearts showed no Ser23/24-cTnI phosphorylation compared to LV or RV of WT mice. However, phosphorylation of the myosin regulatory light chain (RLC) was significantly higher in the RV versus LV of R21C(+/+) mice and versus LV and RV of WT mice. The difference in RLC phosphorylation between the ventricles of R21C(+/+) mice likely contributes to observed differences in contractile force and the lower tension monitored in the LV of HCM mice.
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47
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Chang AN, Battiprolu PK, Cowley PM, Chen G, Gerard RD, Pinto JR, Hill JA, Baker AJ, Kamm KE, Stull JT. Constitutive phosphorylation of cardiac myosin regulatory light chain in vivo. J Biol Chem 2015; 290:10703-16. [PMID: 25733667 DOI: 10.1074/jbc.m115.642165] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Indexed: 01/03/2023] Open
Abstract
In beating hearts, phosphorylation of myosin regulatory light chain (RLC) at a single site to 0.45 mol of phosphate/mol by cardiac myosin light chain kinase (cMLCK) increases Ca(2+) sensitivity of myofilament contraction necessary for normal cardiac performance. Reduction of RLC phosphorylation in conditional cMLCK knock-out mice caused cardiac dilation and loss of cardiac performance by 1 week, as shown by increased left ventricular internal diameter at end-diastole and decreased fractional shortening. Decreased RLC phosphorylation by conventional or conditional cMLCK gene ablation did not affect troponin-I or myosin-binding protein-C phosphorylation in vivo. The extent of RLC phosphorylation was not changed by prolonged infusion of dobutamine or treatment with a β-adrenergic antagonist, suggesting that RLC is constitutively phosphorylated to maintain cardiac performance. Biochemical studies with myofilaments showed that RLC phosphorylation up to 90% was a random process. RLC is slowly dephosphorylated in both noncontracting hearts and isolated cardiac myocytes from adult mice. Electrically paced ventricular trabeculae restored RLC phosphorylation, which was increased to 0.91 mol of phosphate/mol of RLC with inhibition of myosin light chain phosphatase (MLCP). The two RLCs in each myosin appear to be readily available for phosphorylation by a soluble cMLCK, but MLCP activity limits the amount of constitutive RLC phosphorylation. MLCP with its regulatory subunit MYPT2 bound tightly to myofilaments was constitutively phosphorylated in beating hearts at a site that inhibits MLCP activity. Thus, the constitutive RLC phosphorylation is limited physiologically by low cMLCK activity in balance with low MLCP activity.
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Affiliation(s)
| | | | - Patrick M Cowley
- the Veterans Affairs Medical Center, San Francisco, California 94143, the University of California, San Francisco, California 94143, and
| | | | - Robert D Gerard
- Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Jose R Pinto
- the Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, Florida 32306
| | - Joseph A Hill
- Internal Medicine (Cardiology), and Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Anthony J Baker
- the Veterans Affairs Medical Center, San Francisco, California 94143, the University of California, San Francisco, California 94143, and
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48
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Hortemo KH, Aronsen JM, Lunde IG, Sjaastad I, Lunde PK, Sejersted OM. Exhausting treadmill running causes dephosphorylation of sMLC2 and reduced level of myofilament MLCK2 in slow twitch rat soleus muscle. Physiol Rep 2015; 3:3/2/e12285. [PMID: 25713325 PMCID: PMC4393194 DOI: 10.14814/phy2.12285] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Myosin light chain 2 (MLC2) is a small protein in the myosin complex, regulating muscle contractile function by modulating Ca2+ sensitivity of myofilaments. MLC2 can be modified by phosphorylation and O-GlcNAcylation, two reversible and dynamic posttranslational modifications. The slow isoform of MLC2 (sMLC2) is dephosphorylated in soleus muscle during in situ loaded shortening contractions, which correlates with reduction in shortening capacity. Here, we hypothesize that exhausting in vivo treadmill running induces dephosphorylation of MLC2 in slow twitch soleus, but not in fast twitch EDL muscle, and that there are reciprocal changes in MLC2 O-GlcNAcylation. At rest, both phosphorylation and O-GlcNAcylation of MLC2 were lower in slow than fast twitch muscles. One bout of exhausting treadmill running induced dephosphorylation of sMLC2 in soleus, paralleled by reduced levels of the kinase MLCK2 associated to myofilaments, suggesting that the acute reduction in phosphorylation is mediated by dissociation of MLCK2 from myofilaments. O-GlcNAcylation of MLC2 did not change significantly, and seems of limited importance in the regulation of MLC2 phosphorylation during in vivo running. After 6 weeks of treadmill running, the dephosphorylation of sMLC2 persisted in soleus along with reduction in MLCK2 both in myofilament- and total protein fraction. In EDL on the contrary, phosphorylation of MLC2 was not altered after one exercise bout or after 6 weeks of treadmill running. Thus, in contrast to fast twitch muscle, MLC2 dephosphorylation occurs in slow twitch muscle during in vivo exercise and may be linked to reduced myofilament-associated MLCK2 and reduced shortening capacity.
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Affiliation(s)
- Kristin Halvorsen Hortemo
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway KG Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, Oslo, Norway
| | - Jan Magnus Aronsen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway Bjørknes College, Oslo, Norway
| | - Ida G Lunde
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway KG Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, Oslo, Norway Department of Genetics, Harvard Medical School, Boston, Massachusetts
| | - Ivar Sjaastad
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway KG Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, Oslo, Norway
| | - Per Kristian Lunde
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway KG Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, Oslo, Norway
| | - Ole M Sejersted
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway KG Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, Oslo, Norway
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49
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The role of super-relaxed myosin in skeletal and cardiac muscle. Biophys Rev 2014; 7:5-14. [PMID: 28509977 DOI: 10.1007/s12551-014-0151-5] [Citation(s) in RCA: 111] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 11/16/2014] [Indexed: 01/10/2023] Open
Abstract
The super-relaxed (SRX) state of myosin was only recently reported in striated muscle. It is characterised by a sub-population of myosin heads with a highly inhibited rate of ATP turnover. Myosin heads in the SRX state are bound to each other along the thick filament core producing a highly ordered arrangement. Upon activation, these heads project into the interfilament space where they can bind to the actin filaments. Thus far, the population and lifetimes of myosin heads in the SRX state have been characterised in rabbit cardiac, and fast and slow skeletal muscle, as well as in the skeletal muscle of the tarantula. These studies suggest that the role of SRX in cardiac and skeletal muscle regulation is tailored to their specific functions. In skeletal muscle, the SRX modulates the resting metabolic rate. Cardiac SRX represents a "reserve" of inactive myosin heads that may protect the heart during times of stress, e.g. hypoxia and ischaemia. These heads may also be called up when there is a sustained demand for increased power. The SRX in cardiac muscle provides a potential target for novel therapies.
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50
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Huang W, Liang J, Kazmierczak K, Muthu P, Duggal D, Farman GP, Sorensen L, Pozios I, Abraham TP, Moore JR, Borejdo J, Szczesna-Cordary D. Hypertrophic cardiomyopathy associated Lys104Glu mutation in the myosin regulatory light chain causes diastolic disturbance in mice. J Mol Cell Cardiol 2014; 74:318-29. [PMID: 24992035 PMCID: PMC4115013 DOI: 10.1016/j.yjmcc.2014.06.011] [Citation(s) in RCA: 20] [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: 02/27/2014] [Revised: 06/20/2014] [Accepted: 06/21/2014] [Indexed: 12/20/2022]
Abstract
We have examined, for the first time, the effects of the familial hypertrophic cardiomyopathy (HCM)-associated Lys104Glu mutation in the myosin regulatory light chain (RLC). Transgenic mice expressing the Lys104Glu substitution (Tg-MUT) were generated and the results were compared to Tg-WT (wild-type human ventricular RLC) mice. Echocardiography with pulse wave Doppler in 6month-old Tg-MUT showed early signs of diastolic disturbance with significantly reduced E/A transmitral velocities ratio. Invasive hemodynamics in 6month-old Tg-MUT mice also demonstrated a borderline significant prolonged isovolumic relaxation time (Tau) and a tendency for slower rate of pressure decline, suggesting alterations in diastolic function in Tg-MUT. Six month-old mutant animals had no LV hypertrophy; however, at >13months they displayed significant hypertrophy and fibrosis. In skinned papillary muscles from 5 to 6month-old mice a mutation induced reduction in maximal tension and slower muscle relaxation rates were observed. Mutated cross-bridges showed increased rates of binding to the thin filaments and a faster rate of the power stroke. In addition, ~2-fold lower level of RLC phosphorylation was observed in the mutant compared to Tg-WT. In line with the higher mitochondrial content seen in Tg-MUT hearts, the MUT-myosin ATPase activity was significantly higher than WT-myosin, indicating increased energy consumption. In the in vitro motility assay, MUT-myosin produced higher actin sliding velocity under zero load, but the velocity drastically decreased with applied load in the MUT vs. WT myosin. Our results suggest that diastolic disturbance (impaired muscle relaxation, lower E/A) and inefficiency of energy use (reduced contractile force and faster ATP consumption) may underlie the Lys104Glu-mediated HCM phenotype.
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Affiliation(s)
- Wenrui Huang
- University of Miami, Miller School of Medicine, Miami, FL 33136, United States
| | - Jingsheng Liang
- University of Miami, Miller School of Medicine, Miami, FL 33136, United States
| | | | - Priya Muthu
- University of Miami, Miller School of Medicine, Miami, FL 33136, United States
| | - Divya Duggal
- University of North Texas Health Science Center, Fort Worth, TX 76107, United States
| | - Gerrie P Farman
- Boston University School of Medicine, Boston, MA 02118, United States
| | - Lars Sorensen
- Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States
| | - Iraklis Pozios
- Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States
| | - Theodore P Abraham
- Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States
| | - Jeffrey R Moore
- Boston University School of Medicine, Boston, MA 02118, United States
| | - Julian Borejdo
- University of North Texas Health Science Center, Fort Worth, TX 76107, United States
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