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Bang ML, Bogomolovas J, Chen J. Understanding the molecular basis of cardiomyopathy. Am J Physiol Heart Circ Physiol 2022; 322:H181-H233. [PMID: 34797172 PMCID: PMC8759964 DOI: 10.1152/ajpheart.00562.2021] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 11/16/2021] [Accepted: 11/16/2021] [Indexed: 02/03/2023]
Abstract
Inherited cardiomyopathies are a major cause of mortality and morbidity worldwide and can be caused by mutations in a wide range of proteins located in different cellular compartments. The present review is based on Dr. Ju Chen's 2021 Robert M. Berne Distinguished Lectureship of the American Physiological Society Cardiovascular Section, in which he provided an overview of the current knowledge on the cardiomyopathy-associated proteins that have been studied in his laboratory. The review provides a general summary of the proteins in different compartments of cardiomyocytes associated with cardiomyopathies, with specific focus on the proteins that have been studied in Dr. Chen's laboratory.
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Affiliation(s)
- Marie-Louise Bang
- Institute of Genetic and Biomedical Research (IRGB), National Research Council (CNR), Milan Unit, Milan, Italy
- IRCCS Humanitas Research Hospital, Rozzano (Milan), Italy
| | - Julius Bogomolovas
- Division of Cardiovascular Medicine, Department of Medicine Cardiology, University of California, San Diego, La Jolla, California
| | - Ju Chen
- Division of Cardiovascular Medicine, Department of Medicine Cardiology, University of California, San Diego, La Jolla, California
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2
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Kazmierczak K, Liang J, Yuan CC, Yadav S, Sitbon YH, Walz K, Ma W, Irving TC, Cheah JX, Gomes AV, Szczesna-Cordary D. Slow-twitch skeletal muscle defects accompany cardiac dysfunction in transgenic mice with a mutation in the myosin regulatory light chain. FASEB J 2019; 33:3152-3166. [PMID: 30365366 PMCID: PMC6404564 DOI: 10.1096/fj.201801402r] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Accepted: 10/01/2018] [Indexed: 01/06/2023]
Abstract
Myosin light chain 2 ( MYL2) gene encodes the myosin regulatory light chain (RLC) simultaneously in heart ventricles and in slow-twitch skeletal muscle. Using transgenic mice with cardiac-specific expression of the human R58Q-RLC mutant, we sought to determine whether the hypertrophic cardiomyopathy phenotype observed in papillary muscles (PMs) of R58Q mice is also manifested in slow-twitch soleus (SOL) muscles. Skinned SOL muscles and ventricular PMs of R58Q animals exhibited lower contractile force that was not observed in the fast-twitch extensor digitorum longus muscles of R58Q vs. wild-type-RLC mice, but mutant animals did not display gross muscle weakness in vivo. Consistent with SOL muscle abnormalities in R58Q vs. wild-type mice, myosin ATPase staining revealed a decreased proportion of fiber type I/type II only in SOL muscles but not in the extensor digitorum longus muscles. The similarities between SOL muscles and PMs of R58Q mice were further supported by quantitative proteomics. Differential regulation of proteins involved in energy metabolism, cell-cell interactions, and protein-protein signaling was concurrently observed in the hearts and SOL muscles of R58Q mice. In summary, even though R58Q expression was restricted to the heart of mice, functional similarities were clearly observed between the hearts and slow-twitch skeletal muscle, suggesting that MYL2 mutated models of hypertrophic cardiomyopathy may be useful research tools to study the molecular, structural, and energetic mechanisms of cardioskeletal myopathy associated with myosin RLC.-Kazmierczak, K., Liang, J., Yuan, C.-C., Yadav, S., Sitbon, Y. H., Walz, K., Ma, W., Irving, T. C., Cheah, J. X., Gomes, A. V., Szczesna-Cordary, D. Slow-twitch skeletal muscle defects accompany cardiac dysfunction in transgenic mice with a mutation in the myosin regulatory light chain.
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Affiliation(s)
- Katarzyna Kazmierczak
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Jingsheng Liang
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Chen-Ching Yuan
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Sunil Yadav
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Yoel H. Sitbon
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Katherina Walz
- Dr. John T. Macdonald Foundation Department of Human Genetics, John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Weikang Ma
- Department of Biological Sciences, Illinois Institute of Technology, Chicago, Illinois, USA
| | - Thomas C. Irving
- Department of Biological Sciences, Illinois Institute of Technology, Chicago, Illinois, USA
| | - Jenice X. Cheah
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, California, USA
| | - Aldrin V. Gomes
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, California, USA
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
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3
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Zhou W, Bos JM, Ye D, Tester DJ, Hrstka S, Maleszewski JJ, Ommen SR, Nishimura RA, Schaff HV, Kim CS, Ackerman MJ. Induced Pluripotent Stem Cell–Derived Cardiomyocytes from a Patient with MYL2-R58Q-Mediated Apical Hypertrophic Cardiomyopathy Show Hypertrophy, Myofibrillar Disarray, and Calcium Perturbations. J Cardiovasc Transl Res 2019; 12:394-403. [DOI: 10.1007/s12265-019-09873-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 02/13/2019] [Indexed: 12/31/2022]
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Duggal D, Requena S, Nagwekar J, Raut S, Rich R, Das H, Patel V, Gryczynski I, Fudala R, Gryczynski Z, Blair C, Campbell KS, Borejdo J. No Difference in Myosin Kinetics and Spatial Distribution of the Lever Arm in the Left and Right Ventricles of Human Hearts. Front Physiol 2017; 8:732. [PMID: 29081749 PMCID: PMC5645524 DOI: 10.3389/fphys.2017.00732] [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: 06/06/2017] [Accepted: 09/08/2017] [Indexed: 11/13/2022] Open
Abstract
The systemic circulation offers larger resistance to the blood flow than the pulmonary system. Consequently, the left ventricle (LV) must pump blood with more force than the right ventricle (RV). The question arises whether the stronger pumping action of the LV is due to a more efficient action of left ventricular myosin, or whether it is due to the morphological differences between ventricles. Such a question cannot be answered by studying the entire ventricles or myocytes because any observed differences would be wiped out by averaging the information obtained from trillions of myosin molecules present in a ventricle or myocyte. We therefore searched for the differences between single myosin molecules of the LV and RV of failing hearts In-situ. We show that the parameters that define the mechanical characteristics of working myosin (kinetic rates and the distribution of spatial orientation of myosin lever arm) were the same in both ventricles. These results suggest that there is no difference in the way myosin interacts with thin filaments in myocytes of failing hearts, and suggests that the difference in pumping efficiencies are caused by interactions between muscle proteins other than myosin or that they are purely morphological.
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Affiliation(s)
- Divya Duggal
- Department of Cell Biology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, TX, United States
| | - S Requena
- Department of Cell Biology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, TX, United States
| | - Janhavi Nagwekar
- Department of Cell Biology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, TX, United States
| | - Sangram Raut
- Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX, United States
| | - Ryan Rich
- Department of Mathematics and Physics, Texas Wesleyan University, Fort Worth, TX, United States
| | - Hriday Das
- Center for Neuroscience Discovery, Institute for Healthy Aging, University of North Texas, Health Science Center, Fort Worth, TX, United States
| | - Vipul Patel
- Department of Cell Biology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, TX, United States.,Center of Emphasis in Diabetes and Metabolism, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center El Paso, El Paso, TX, United States
| | - Ignacy Gryczynski
- Department of Cell Biology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, TX, United States
| | - Rafal Fudala
- Department of Cell Biology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, TX, United States
| | - Zygmunt Gryczynski
- Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX, United States
| | - Cheavar Blair
- Department of Physiology, University of Kentucky, Lexington, KY, United States
| | - Kenneth S Campbell
- Department of Physiology, University of Kentucky, Lexington, KY, United States
| | - Julian Borejdo
- Department of Cell Biology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, TX, United States
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5
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Nagwekar J, Duggal D, Midde K, Rich R, Liang J, Kazmierczak K, Huang W, Fudala R, Gryczynski I, Gryczynski Z, Szczesna-Cordary D, Borejdo J. A Novel Method of Determining the Functional Effects of a Minor Genetic Modification of a Protein. Front Cardiovasc Med 2015; 2:35. [PMID: 26664906 PMCID: PMC4671333 DOI: 10.3389/fcvm.2015.00035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 10/30/2015] [Indexed: 11/17/2022] Open
Abstract
Contraction of muscles results from the ATP-coupled cyclic interactions of the myosin cross-bridges with actin filaments. Macroscopic parameters of contraction, such as maximum tension, speed of shortening, or ATPase activity, are unlikely to reveal differences between the wild-type and mutated (MUT) proteins when the level of transgenic protein expression is low. This is because macroscopic measurements are made on whole organs containing trillions of actin and myosin molecules. An average of the information collected from such a large assembly is bound to conceal any differences imposed by a small fraction of MUT molecules. To circumvent the averaging problem, the measurements were done on isolated ventricular myofibril (MF) in which thin filaments were sparsely labeled with a fluorescent dye. We isolated a single MF from a ventricle, oriented it vertically (to be able measure the orientation), and labeled 1 in 100,000 actin monomers with a fluorescent dye. We observed the fluorescence from a small confocal volume containing approximately three actin molecules. During the contraction of a ventricle actin constantly changes orientation (i.e., the transition moment of rigidly attached fluorophore fluctuates in time) because it is repetitively being "kicked" by myosin cross-bridges. An autocorrelation functions (ACFs) of these fluctuations are remarkably sensitive to the mutation of myosin. We examined the effects of Alanine to Threonine (A13T) mutation in the myosin regulatory light chain shown by population studies to cause hypertrophic cardiomyopathy. This is an appropriate example, because mutation is expressed at only 10% in the ventricles of transgenic mice. ACFs were either "Standard" (Std) (decaying monotonically in time) or "Non-standard" (NStd) (decaying irregularly). The sparse labeling of actin also allowed the measurement of the spatial distribution of actin molecules. Such distribution reflects the interaction of actin with myosin cross-bridges and is also remarkably sensitive to myosin mutation. The result showed that the A13T mutation caused 9% ACFs and 9% of spatial distributions of actin to be NStd, while the remaining 91% were Std, suggesting that the NStd performances were executed by the MUT myosin heads and that the Std performances were executed by non-MUT myosin heads. We conclude that the method explored in this study is a sensitive and valid test of the properties of low prevalence mutations in sarcomeric proteins.
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Affiliation(s)
- Janhavi Nagwekar
- Department of Cell Biology, Center for Commercialization of Fluorescence Technologies, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Divya Duggal
- Department of Cell Biology, Center for Commercialization of Fluorescence Technologies, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Krishna Midde
- Department of Cell Biology, Center for Commercialization of Fluorescence Technologies, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Ryan Rich
- Department of Mathematics, Computer Science, and Physics, Texas Wesleyan University, Fort Worth, TX, USA
| | - Jingsheng Liang
- Department of Molecular and Cellular Pharmacology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Katarzyna Kazmierczak
- Department of Molecular and Cellular Pharmacology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Wenrui Huang
- Department of Molecular and Cellular Pharmacology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Rafal Fudala
- Department of Cell Biology, Center for Commercialization of Fluorescence Technologies, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Ignacy Gryczynski
- Department of Cell Biology, Center for Commercialization of Fluorescence Technologies, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Zygmunt Gryczynski
- Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX, USA
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Julian Borejdo
- Department of Cell Biology, Center for Commercialization of Fluorescence Technologies, University of North Texas Health Science Center, Fort Worth, TX, USA
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Wang L, Bahadir A, Kawai M. High ionic strength depresses muscle contractility by decreasing both force per cross-bridge and the number of strongly attached cross-bridges. J Muscle Res Cell Motil 2015; 36:227-41. [PMID: 25836331 DOI: 10.1007/s10974-015-9412-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Accepted: 03/26/2015] [Indexed: 11/24/2022]
Abstract
An increase in ionic strength (IS) lowers Ca(2+) activated tension in muscle fibres, however, its molecular mechanism is not well understood. In this study, we used single rabbit psoas fibres to perform sinusoidal analyses. During Ca(2+) activation, the effects of ligands (ATP, Pi, and ADP) at IS ranging 150-300 mM were studied on three rate constants to characterize elementary steps of the cross-bridge cycle. The IS effects were studied because a change in IS modifies the inter- and intra-molecular interactions, hence they may shed light on the molecular mechanisms of force generation. Both the ATP binding affinity (K1) and the ADP binding affinity (K 0) increased to 2-3x, and the Pi binding affinity (K5) decreased to 1/2, when IS was raised from 150 to 300 mM. The effect on ATP/ADP can be explained by stereospecific and hydrophobic interaction, and the effect on Pi can be explained by the electrostatic interaction with myosin. The increase in IS increased cross-bridge detachment steps (k2 and k-4), indicating that electrostatic repulsion promotes these steps. However, IS did not affect attachment steps (k-2 and k4). Consequently, the equilibrium constant of the detachment step (K2) increased by ~100%, and the force generation step (K4) decreased by ~30%. These effects together diminished the number of force-generating cross-bridges by 11%. Force/cross-bridge (T56) decreased by 26%, which correlates well with a decrease in the Debye length that limits the ionic atmosphere where ionic interactions take place. We conclude that the major effect of IS is a decrease in force/cross-bridge, but a decrease in the number of force generating cross-bridge also takes place. The stiffness during rigor induction did not change with IS, demonstrating that in-series compliance is not much affected by IS.
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Affiliation(s)
- Li Wang
- School of Nursing, Soochow University, Suzhou, 215006, Jiangsu, China,
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7
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Duggal D, Nagwekar J, Rich R, Huang W, Midde K, Fudala R, Das H, Gryczynski I, Szczesna-Cordary D, Borejdo J. Effect of a myosin regulatory light chain mutation K104E on actin-myosin interactions. Am J Physiol Heart Circ Physiol 2015; 308:H1248-57. [PMID: 25770245 DOI: 10.1152/ajpheart.00834.2014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 03/03/2015] [Indexed: 11/22/2022]
Abstract
Familial hypertrophic cardiomyopathy (FHC) is the most common cause of sudden cardiac death in young individuals. Molecular mechanisms underlying this disorder are largely unknown; this study aims at revealing how disruptions in actin-myosin interactions can play a role in this disorder. Cross-bridge (XB) kinetics and the degree of order were examined in contracting myofibrils from the ex vivo left ventricles of transgenic (Tg) mice expressing FHC regulatory light chain (RLC) mutation K104E. Because the degree of order and the kinetics are best studied when an individual XB makes a significant contribution to the overall signal, the number of observed XBs in an ex vivo ventricle was minimized to ∼20. Autofluorescence and photobleaching were minimized by labeling the myosin lever arm with a relatively long-lived red-emitting dye containing a chromophore system encapsulated in a cyclic macromolecule. Mutated XBs were significantly better ordered during steady-state contraction and during rigor, but the mutation had no effect on the degree of order in relaxed myofibrils. The K104E mutation increased the rate of XB binding to thin filaments and the rate of execution of the power stroke. The stopped-flow experiments revealed a significantly faster observed dissociation rate in Tg-K104E vs. Tg-wild-type (WT) myosin and a smaller second-order ATP-binding rate for the K104E compared with WT myosin. Collectively, our data indicate that the mutation-induced changes in the interaction of myosin with actin during the contraction-relaxation cycle may contribute to altered contractility and the development of FHC.
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Affiliation(s)
- D Duggal
- Department of Cell Biology & Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, Texas; and
| | - J Nagwekar
- Department of Cell Biology & Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, Texas; and
| | - R Rich
- Department of Cell Biology & Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, Texas; and
| | - W Huang
- Department of Molecular & Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida; and
| | - K Midde
- Department of Cell Biology & Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, Texas; and
| | - R Fudala
- Department of Cell Biology & Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, Texas; and
| | - H Das
- Department of Cell Biology & Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, Texas; and Department of Pharmacology and Neuroscience, Institute of Aging and Alzheimer's Disease Research, Institute of Cancer Research, Fort Worth, Texas
| | - I Gryczynski
- Department of Cell Biology & Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, Texas; and
| | - D Szczesna-Cordary
- Department of Molecular & Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida; and
| | - J Borejdo
- Department of Cell Biology & Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, Texas; and
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Nagwekar J, Duggal D, Rich R, Raut S, Fudala R, Gryczynski I, Gryczynski Z, Borejdo J. The spatial distribution of actin and mechanical cycle of myosin are different in right and left ventricles of healthy mouse hearts. Biochemistry 2014; 53:7641-9. [PMID: 25488019 PMCID: PMC4262935 DOI: 10.1021/bi501175s] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
![]()
The contraction of the right ventricle
(RV) expels blood into the
pulmonary circulation, and the contraction of the left ventricle (LV)
pumps blood into the systemic circulation through the aorta. The respective
afterloads imposed on the LV and RV by aortic and pulmonary artery
pressures create very different mechanical requirements for the two
ventricles. Indeed, differences have been observed in the contractile
performance between left and right ventricular myocytes in dilated
cardiomyopathy, in congestive heart failure, and in energy usage and
speed of contraction at light loads in healthy hearts. In spite of
these functional differences, it is commonly believed that the right
and left ventricular muscles are identical because there were no differences
in stress development, twitch duration, work performance, or power
among the RV and LV in dogs. This report shows that on a mesoscopic
scale [when only a few molecules are studied (here three to six molecules
of actin) in ex vivo ventricular myofibrils], the
two ventricles in rigor differ in the degree of orientational disorder
of actin within in filaments and during contraction in the kinetics
of the cross-bridge cycle.
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Affiliation(s)
- J Nagwekar
- Department of Cell Biology and Center for Fluorescence Technology and Nanomedicine, University of North Texas Health Science Center , 3500 Camp Bowie Boulevard, Fort Worth, Texas 76107, United States
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Wang L, Ji X, Barefield D, Sadayappan S, Kawai M. Phosphorylation of cMyBP-C affects contractile mechanisms in a site-specific manner. Biophys J 2014; 106:1112-22. [PMID: 24606935 DOI: 10.1016/j.bpj.2014.01.029] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 01/18/2014] [Accepted: 01/23/2014] [Indexed: 01/05/2023] Open
Abstract
Cardiac myosin binding protein-C (cMyBP-C) is a cardiac-specific, thick-filament regulatory protein that is differentially phosphorylated at Ser(273), Ser(282), and Ser(302) by various kinases and modulates contraction. In this study, phosphorylation-site-specific effects of cMyBP-C on myocardial contractility and cross-bridge kinetics were studied by sinusoidal analysis in papillary and trabecular muscle fibers isolated from t/t (cMyBP-C-null) mice and in their counterparts in which cMyBP-C contains the ADA (Ala(273)-Asp(282)-Ala(302)), DAD (Asp(273)-Ala(282)-Asp(302)), and SAS (Ser(273)-Ala(282)-Ser(302)) mutations; the results were compared to those from mice expressing the wild-type (WT) transgene on the t/t background. Under standard activating conditions, DAD fibers showed significant decreases in tension (~50%), stiffness, the fast apparent rate constant 2πc, and its magnitude C, as well as its magnitude H, but an increase in the medium rate constant 2πb, with respect to WT. The t/t fibers showed a smaller drop in stiffness and a significant decrease in 2πc that can be explained by isoform shift of myosin heavy chain. In the pCa-tension study using the 8 mM phosphate (Pi) solution, there was hardly any difference in Ca(2+) sensitivity (pCa50) and cooperativity (nH) between the mutant and WT samples. However, in the solutions without Pi, DAD showed increased nH and slightly decreased pCa50. We infer from these observations that the nonphosphorylatable residue 282 combined with phosphomimetic residues Asp(273) and/or Asp(302) (in DAD) is detrimental to cardiomyocytes by lowering isometric tension and altering cross-bridge kinetics with decreased 2πc and increased 2πb. In contrast, a single change of residue 282 to nonphosphorylatable Ala (SAS), or to phosphomimetic Asps together with the changes of residues 273 and 302 to nonphosphorylatable Ala (ADA) causes minute changes in fiber mechanics.
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Affiliation(s)
- Li Wang
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, Iowa; School of Nursing, Soochow University, Suzhou, Jiangsu, China
| | - Xiang Ji
- Department of Cell and Molecular Physiology, Health Sciences Division, Loyola University Chicago, Maywood, Illinois
| | - David Barefield
- Department of Cell and Molecular Physiology, Health Sciences Division, Loyola University Chicago, Maywood, Illinois
| | - Sakthivel Sadayappan
- Department of Cell and Molecular Physiology, Health Sciences Division, Loyola University Chicago, Maywood, Illinois
| | - Masakata Kawai
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, Iowa.
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Vakrou S, Abraham MR. Hypertrophic cardiomyopathy: a heart in need of an energy bar? Front Physiol 2014; 5:309. [PMID: 25191275 PMCID: PMC4137386 DOI: 10.3389/fphys.2014.00309] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 07/30/2014] [Indexed: 01/08/2023] Open
Abstract
Hypertrophic cardiomyopathy (HCM) has been recently recognized as the most common inherited cardiovascular disorder, affecting 1 in 500 adults worldwide. HCM is characterized by myocyte hypertrophy resulting in thickening of the ventricular wall, myocyte disarray, interstitial and/or replacement fibrosis, decreased ventricular cavity volume and diastolic dysfunction. HCM is also the most common cause of sudden death in the young. A large proportion of patients diagnosed with HCM have mutations in sarcomeric proteins. However, it is unclear how these mutations lead to the cardiac phenotype, which is variable even in patients carrying the same causal mutation. Abnormalities in calcium cycling, oxidative stress, mitochondrial dysfunction and energetic deficiency have been described constituting the basis of therapies in experimental models of HCM and HCM patients. This review focuses on evidence supporting the role of cellular metabolism and mitochondria in HCM.
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Affiliation(s)
- Styliani Vakrou
- Division of Cardiology, School of Medicine, Johns Hopkins University Baltimore, MD, USA
| | - M Roselle Abraham
- Division of Cardiology, School of Medicine, Johns Hopkins University Baltimore, MD, USA
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11
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Bai F, Caster HM, Rubenstein PA, Dawson JF, Kawai M. Using baculovirus/insect cell expressed recombinant actin to study the molecular pathogenesis of HCM caused by actin mutation A331P. J Mol Cell Cardiol 2014; 74:64-75. [PMID: 24793351 DOI: 10.1016/j.yjmcc.2014.04.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 04/21/2014] [Accepted: 04/22/2014] [Indexed: 01/07/2023]
Abstract
Recombinant WT human cardiac actin (WT actin) was expressed using the baculovirus/insect cell expression system, purified, and used to reconstitute the thin-filament of bovine cardiac muscle fibers, together with bovine cardiac tropomyosin (Tm) and troponin (Tn). Effects of [Ca(2+)], [ATP], [phosphate] and [ADP] on tension and tension transients were studied at 25°C by using sinusoidal analysis, and the results were compared with those of native fibers and fibers reconstituted with purified bovine cardiac actin (BVC actin). In actin filament reconstituted fibers (without Tm/Tn), those reconstituted with WT actin showed exactly the same active tension as those reconstituted with purified BVC actin (WT: 0.75±0.06 T0, N=11; BVC: 0.73±0.07 T0, N=12, where T0 is the tension of original fibers before extraction). After Tm/Tn reconstitution, fibers reconstituted with WT actin generated 0.85±0.06 T0 (N=11) compared to 0.98±0.04 T0 (N=12) recovered by those reconstituted with BVC actin. In the presence of Tm/Tn, WT actin reconstituted fibers showed exactly the same Ca(2+) sensitivity as those of the native fibers and BVC actin reconstituted fibers (pCa50: native fibers: 5.69±0.01, N=10; WT: 5.69±0.02, N=11; BVC: 5.68±0.02, N=12). Sinusoidal analysis showed that the cross-bridge kinetics were the same among native fibers, BVC actin reconstituted fibers and WT actin reconstituted fibers, followed by reconstitution of Tm/Tn. These results demonstrate that baculovirus/insect cell expressed actin has no significant differences from tissue purified actin and can be used for thin-filament reconstitution assays. One hypertrophic cardiomyopathy (HCM) causing actin mutant A331P actin was also expressed and studied similarly, and the results were compared to those of the WT actin. In the reconstituted fibers, A331P significantly decreased the tension both in the absence of Tm/Tn (0.55±0.03 T0, N=13) and in their presence (0.65±0.02 T0, N=13) compared to those of the WT (0.75±0.06 T0 and 0.85±0.06 T0, respectively, N=11). A331P also showed decreased pCa50 (5.57±0.03, N=13) compared to that of WT (5.69±0.02, N=11). The cross-bridge kinetics and its distribution were similar between WT and A331P actin reconstituted fibers, indicating that force/cross-bridge was decreased by A331P. In conclusion, A331P causes a weakened cross-bridge force, which leads to a decreased active tension, reduces left-ventricular ejection fraction, and eventually results in the HCM phenotype.
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Affiliation(s)
- Fan Bai
- Department of Anatomy and Cell Biology, The University of Iowa, Iowa City, IA 52242-1109, USA.
| | - Hannah M Caster
- Department of Anatomy and Cell Biology, The University of Iowa, Iowa City, IA 52242-1109, USA.
| | - Peter A Rubenstein
- Department of Biochemistry, The University of Iowa, Iowa City, IA 52242-1109, USA.
| | - John F Dawson
- Department of Molecular & Cellular Biology, University of Guelph, College of Biological Science, Guelph, Ontario N1G 2 W1, Canada.
| | - Masataka Kawai
- Department of Anatomy and Cell Biology, The University of Iowa, Iowa City, IA 52242-1109, USA; Department of Internal Medicine, The University of Iowa, Iowa City, IA 52242-1109, USA.
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Lee WJ, Youm Y, Rhee Y, Park YR, Chu SH, Kim HC. Social network characteristics and body mass index in an elderly Korean population. J Prev Med Public Health 2013; 46:336-45. [PMID: 24349655 PMCID: PMC3859855 DOI: 10.3961/jpmph.2013.46.6.336] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Accepted: 10/17/2013] [Indexed: 11/13/2022] Open
Abstract
Objectives Research has shown that obesity appears to spread through social ties. However, the association between other characteristics of social networks and obesity is unclear. This study aimed to identify the association between social network characteristics and body mass index (BMI, kg/m2) in an elderly Korean population. Methods This cross-sectional study analyzed data from 657 Koreans (273 men, 384 women) aged 60 years or older who participated in the Korean Social Life, Health, and Aging Project. Network size is a count of the number of friends. Density of communication network is the number of connections in the social network reported as a fraction of the total links possible in the personal (ego-centric) network. Average frequency of communication (or meeting) measures how often network members communicate (or meet) each other. The association of each social network measure with BMI was investigated by multiple linear regression analysis. Results After adjusting for potential confounders, the men with lower density (<0.71) and higher network size (4-6) had the higher BMI (β=1.089, p=0.037) compared to the men with higher density (>0.83) and lower size (1-2), but not in the women (p=0.393). The lowest tertile of communication frequency was associated with higher BMI in the women (β=0.885, p=0.049), but not in the men (p=0.140). Conclusions Our study suggests that social network structure (network size and density) and activation (communication frequency and meeting frequency) are associated with obesity among the elderly. There may also be gender differences in this association.
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Affiliation(s)
- Won Joon Lee
- Department of Preventive Medicine, Yonsei University College of Medicine, Seoul, Korea
| | - Yoosik Youm
- Department of Sociology, Yonsei University College of Social Sciences, Seoul, Korea
| | - Yumie Rhee
- Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
| | - Yeong-Ran Park
- Division of Silver Industry, Kangnam University, Yongin, Korea
| | - Sang Hui Chu
- Department of Clinical Nursing Science, Yonsei University College of Nursing, Seoul, Korea
| | - Hyeon Chang Kim
- Department of Preventive Medicine, Yonsei University College of Medicine, Seoul, Korea
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Duggal D, Nagwekar J, Rich R, Midde K, Fudala R, Gryczynski I, Borejdo J. Phosphorylation of myosin regulatory light chain has minimal effect on kinetics and distribution of orientations of cross bridges of rabbit skeletal muscle. Am J Physiol Regul Integr Comp Physiol 2013; 306:R222-33. [PMID: 24285364 DOI: 10.1152/ajpregu.00382.2013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Force production in muscle results from ATP-driven cyclic interactions of myosin with actin. A myosin cross bridge consists of a globular head domain, containing actin and ATP-binding sites, and a neck domain with the associated light chain 1 (LC1) and the regulatory light chain (RLC). The actin polymer serves as a "rail" over which myosin translates. Phosphorylation of the RLC is thought to play a significant role in the regulation of muscle relaxation by increasing the degree of skeletal cross-bridge disorder and increasing muscle ATPase activity. The effect of phosphorylation on skeletal cross-bridge kinetics and the distribution of orientations during steady-state contraction of rabbit muscle is investigated here. Because the kinetics and orientation of an assembly of cross bridges (XBs) can only be studied when an individual XB makes a significant contribution to the overall signal, the number of observed XBs was minimized to ∼20 by limiting the detection volume and concentration of fluorescent XBs. The autofluorescence and photobleaching from an ex vivo sample was reduced by choosing a dye that was excited in the red and observed in the far red. The interference from scattering was eliminated by gating the signal. These techniques decrease large uncertainties associated with determination of the effect of phosphorylation on a few molecules ex vivo with millisecond time resolution. In spite of the remaining uncertainties, we conclude that the state of phosphorylation of RLC had no effect on the rate of dissociation of cross bridges from thin filaments, on the rate of myosin head binding to thin filaments, and on the rate of power stroke. On the other hand, phosphorylation slightly increased the degree of disorder of active cross bridges.
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Affiliation(s)
- Divya Duggal
- Department of Molecular Biology and Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, Texas
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Wang L, Muthu P, Szczesna-Cordary D, Kawai M. Diversity and similarity of motor function and cross-bridge kinetics in papillary muscles of transgenic mice carrying myosin regulatory light chain mutations D166V and R58Q. J Mol Cell Cardiol 2013; 62:153-63. [PMID: 23727233 PMCID: PMC3809071 DOI: 10.1016/j.yjmcc.2013.05.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 05/16/2013] [Accepted: 05/19/2013] [Indexed: 10/26/2022]
Abstract
Mechanical properties of skinned papillary muscle fibers from transgenic mice expressing familial hypertrophic cardiomyopathy associated mutations D166V and R58Q in myosin regulatory light chain were investigated. Elementary steps and the apparent rate constants of the cross-bridge cycle were characterized from the tension transients induced by sinusoidal length changes during maximal Ca(2+) activation, together with ATP, ADP, and Pi studies. The tension-pCa relation was also tested in two sets of solutions with differing Pi and ionic strength. Our results showed that in both mutants the fast apparent rate constant 2πc and the rate constants of the cross-bridge detachment step (k2) were smaller than those of wild type (WT), demonstrating the slower cross-bridge kinetics. D166V showed significantly smaller ATP (K1) and ADP (K0) association constants than WT, displaying weaker ATP binding and easier ADP release, whereas those of R58Q were not significantly different from WT. In tension-pCa study, both D166V and R58Q mutations exhibited increased Ca(2+) sensitivity and less cooperativity. We conclude that, while the two FHC mutations have similar clinical manifestations and prognosis, some of the mechanical parameters of cross-bridges (K0, K1) are differently modified, whereas some others (Ca(2+)-sensitivity, cooperativity, k2) are similarly modified by these two FHC associated mutations.
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Affiliation(s)
- Li Wang
- Departments of Anatomy and Cell Biology, and Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Priya Muthu
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Masataka Kawai
- Departments of Anatomy and Cell Biology, and Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
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15
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Kazmierczak K, Paulino EC, Huang W, Muthu P, Liang J, Yuan CC, Rojas AI, Hare JM, Szczesna-Cordary D. Discrete effects of A57G-myosin essential light chain mutation associated with familial hypertrophic cardiomyopathy. Am J Physiol Heart Circ Physiol 2013; 305:H575-89. [PMID: 23748425 DOI: 10.1152/ajpheart.00107.2013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The functional consequences of the familial hypertrophic cardiomyopathy A57G (alanine-to-glycine) mutation in the myosin ventricular essential light chain (ELC) were assessed in vitro and in vivo using previously generated transgenic (Tg) mice expressing A57G-ELC mutant vs. wild-type (WT) of human cardiac ELC and in recombinant A57G- or WT-protein-exchanged porcine cardiac muscle strips. Compared with the Tg-WT, there was a significant increase in the Ca²⁺ sensitivity of force (ΔpCa₅₀ ≅ 0.1) and an ~1.3-fold decrease in maximal force per cross section of muscle observed in the mutant preparations. In addition, a significant increase in passive tension in response to stretch was monitored in Tg-A57G vs. Tg-WT strips indicating a mutation-induced myocardial stiffness. Consistently, the hearts of Tg-A57G mice demonstrated a high level of fibrosis and hypertrophy manifested by increased heart weight-to-body weight ratios and a decreased number of nuclei indicating an increase in the two-dimensional size of Tg-A57G vs. Tg-WT myocytes. Echocardiography examination showed a phenotype of eccentric hypertrophy in Tg-A57G mice, enhanced left ventricular (LV) cavity dimension without changes in LV posterior/anterior wall thickness. Invasive hemodynamics data revealed significantly increased end-systolic elastance, defined by the slope of the pressure-volume relationship, indicating a mutation-induced increase in cardiac contractility. Our results suggest that the A57G allele causes disease by means of a discrete modulation of myofilament function, increased Ca²⁺ sensitivity, and decreased maximal tension followed by compensatory hypertrophy and enhanced contractility. These and other contributing factors such as increased myocardial stiffness and fibrosis most likely activate cardiomyopathic signaling pathways leading to pathologic cardiac remodeling.
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Affiliation(s)
- Katarzyna Kazmierczak
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida; and
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Midde K, Rich R, Marandos P, Fudala R, Li A, Gryczynski I, Borejdo J. Comparison of orientation and rotational motion of skeletal muscle cross-bridges containing phosphorylated and dephosphorylated myosin regulatory light chain. J Biol Chem 2013; 288:7012-23. [PMID: 23319584 DOI: 10.1074/jbc.m112.434209] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Calcium binding to thin filaments is a major element controlling active force generation in striated muscles. Recent evidence suggests that processes other than Ca(2+) binding, such as phosphorylation of myosin regulatory light chain (RLC) also controls contraction of vertebrate striated muscle (Cooke, R. (2011) Biophys. Rev. 3, 33-45). Electron paramagnetic resonance (EPR) studies using nucleotide analog spin label probes showed that dephosphorylated myosin heads are highly ordered in the relaxed fibers and have very low ATPase activity. This ordered structure of myosin cross-bridges disappears with the phosphorylation of RLC (Stewart, M. (2010) Proc. Natl. Acad. Sci. U.S.A. 107, 430-435). The slower ATPase activity in the dephosporylated moiety has been defined as a new super-relaxed state (SRX). It can be observed in both skeletal and cardiac muscle fibers (Hooijman, P., Stewart, M. A., and Cooke, R. (2011) Biophys. J. 100, 1969-1976). Given the importance of the finding that suggests a novel pathway of regulation of skeletal muscle, we aim to examine the effects of phosphorylation on cross-bridge orientation and rotational motion. We find that: (i) relaxed cross-bridges, but not active ones, are statistically better ordered in muscle where the RLC is dephosporylated compared with phosphorylated RLC; (ii) relaxed phosphorylated and dephosphorylated cross-bridges rotate equally slowly; and (iii) active phosphorylated cross-bridges rotate considerably faster than dephosphorylated ones during isometric contraction but the duty cycle remained the same, suggesting that both phosphorylated and dephosphorylated muscles develop the same isometric tension at full Ca(2+) saturation. A simple theory was developed to account for this fact.
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Affiliation(s)
- Krishna Midde
- Department of Cell Biology and Anatomy, University of North Texas, Health Science Center, Fort Worth, Texas 76107, USA
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17
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Mesoscopic analysis of motion and conformation of cross-bridges. Biophys Rev 2012; 4:299-311. [PMID: 28510208 DOI: 10.1007/s12551-012-0074-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Accepted: 03/15/2012] [Indexed: 01/03/2023] Open
Abstract
The orientation of a cross-bridge is widely used as a parameter in determining the state of muscle. The conventional measurements of orientation, such as that made by wide-field fluorescence microscopy, electron paramagnetic resonance (EPR) or X-ray diffraction or scattering, report the average orientation of 1012-109 myosin cross-bridges. Under conditions where all the cross-bridges are immobile and assume the same orientation, for example in normal skeletal muscle in rigor, it is possible to determine the average orientation from such global measurements. But in actively contracting muscle, where a parameter indicating orientation fluctuates in time, the measurements of the average value provide no information about cross-bridge kinetics. To avoid problems associated with averaging information from trillions of cross-bridges, it is necessary to decrease the number of observed cross-bridges to a mesoscopic value (i.e. the value affected by fluctuations around the average). In such mesoscopic regimes, the averaging of the signal is minimal and dynamic behavior can be examined in great detail. Examples of mesoscopic analysis on skeletal and cardiac muscle are provided.
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Kazmierczak K, Muthu P, Huang W, Jones M, Wang Y, Szczesna-Cordary D. Myosin regulatory light chain mutation found in hypertrophic cardiomyopathy patients increases isometric force production in transgenic mice. Biochem J 2012; 442:95-103. [PMID: 22091967 PMCID: PMC6589164 DOI: 10.1042/bj20111145] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
FHC (familial hypertrophic cardiomyopathy) is a heritable form of cardiac hypertrophy caused by mutations in genes encoding sarcomeric proteins. The present study focuses on the A13T mutation in the human ventricular myosin RLC (regulatory light chain) that is associated with a rare FHC variant defined by mid-ventricular obstruction and septal hypertrophy. We generated heart-specific Tg (transgenic) mice with ~10% of human A13T-RLC mutant replacing the endogenous mouse cardiac RLC. Histopathological examinations of longitudinal heart sections from Tg-A13T mice showed enlarged interventricular septa and profound fibrotic lesions compared with Tg-WT (wild-type), expressing the human ventricular RLC, or non-Tg mice. Functional studies revealed an abnormal A13T mutation-induced increase in isometric force production, no change in the force-pCa relationship and a decreased Vmax of the acto-myosin ATPase. In addition, a fluorescence-based assay showed a 3-fold lower binding affinity of the recombinant A13T mutant for the RLC-depleted porcine myosin compared with WT-RLC. These results suggest that the A13T mutation triggers a hypertrophic response through changes in cardiac sarcomere organization and myosin cross-bridge function leading to abnormal remodelling of the heart. The significant functional changes observed, despite a low level of A13T mutant incorporation into myofilaments, suggest a 'poison-peptide' mechanism of disease.
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Affiliation(s)
- Katarzyna Kazmierczak
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, U.S.A
| | - Priya Muthu
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, U.S.A
| | - Wenrui Huang
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, U.S.A
| | - Michelle Jones
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, U.S.A
| | - Yingcai Wang
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, U.S.A
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, U.S.A
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