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Liu YB, Wang Q, Song YL, Song XM, Fan YC, Kong L, Zhang JS, Li S, Lv YJ, Li ZY, Dai JY, Qiu ZK. Abnormal phosphorylation / dephosphorylation and Ca 2+ dysfunction in heart failure. Heart Fail Rev 2024; 29:751-768. [PMID: 38498262 DOI: 10.1007/s10741-024-10395-w] [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] [Accepted: 03/01/2024] [Indexed: 03/20/2024]
Abstract
Heart failure (HF) can be caused by a variety of causes characterized by abnormal myocardial systole and diastole. Ca2+ current through the L-type calcium channel (LTCC) on the membrane is the initial trigger signal for a cardiac cycle. Declined systole and diastole in HF are associated with dysfunction of myocardial Ca2+ function. This disorder can be correlated with unbalanced levels of phosphorylation / dephosphorylation of LTCC, endoplasmic reticulum (ER), and myofilament. Kinase and phosphatase activity changes along with HF progress, resulting in phased changes in the degree of phosphorylation / dephosphorylation. It is important to realize the phosphorylation / dephosphorylation differences between a normal and a failing heart. This review focuses on phosphorylation / dephosphorylation changes in the progression of HF and summarizes the effects of phosphorylation / dephosphorylation of LTCC, ER function, and myofilament function in normal conditions and HF based on previous experiments and clinical research. Also, we summarize current therapeutic methods based on abnormal phosphorylation / dephosphorylation and clarify potential therapeutic directions.
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Affiliation(s)
- Yan-Bing Liu
- Interventional Medical Center, The Affiliated Hospital of Qingdao University, 16 Jiangsu Road, Qingdao, 266003, Shandong Province, China
- Medical College, Qingdao University, Qingdao, China
| | - Qian Wang
- Medical College, Qingdao University, Qingdao, China
| | - Yu-Ling Song
- Department of Pediatrics, Huantai County Hospital of Traditional Chinese Medicine, Zibo, China
| | | | - Yu-Chen Fan
- Medical College, Qingdao University, Qingdao, China
| | - Lin Kong
- Medical College, Qingdao University, Qingdao, China
| | | | - Sheng Li
- Medical College, Qingdao University, Qingdao, China
| | - Yi-Ju Lv
- Medical College, Qingdao University, Qingdao, China
| | - Ze-Yang Li
- Medical College, Qingdao University, Qingdao, China
| | - Jing-Yu Dai
- Department of Oncology, The Affiliated Hospital of Qingdao University, 16 Jiangsu Road, Qingdao, 266003, Shandong Province, China.
| | - Zhen-Kang Qiu
- Interventional Medical Center, The Affiliated Hospital of Qingdao University, 16 Jiangsu Road, Qingdao, 266003, Shandong Province, China.
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2
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Hoh JFY. Developmental, Physiological and Phylogenetic Perspectives on the Expression and Regulation of Myosin Heavy Chains in Craniofacial Muscles. Int J Mol Sci 2024; 25:4546. [PMID: 38674131 PMCID: PMC11050549 DOI: 10.3390/ijms25084546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 04/15/2024] [Accepted: 04/18/2024] [Indexed: 04/28/2024] Open
Abstract
This review deals with the developmental origins of extraocular, jaw and laryngeal muscles, the expression, regulation and functional significance of sarcomeric myosin heavy chains (MyHCs) that they express and changes in MyHC expression during phylogeny. Myogenic progenitors from the mesoderm in the prechordal plate and branchial arches specify craniofacial muscle allotypes with different repertoires for MyHC expression. To cope with very complex eye movements, extraocular muscles (EOMs) express 11 MyHCs, ranging from the superfast extraocular MyHC to the slowest, non-muscle MyHC IIB (nmMyH IIB). They have distinct global and orbital layers, singly- and multiply-innervated fibres, longitudinal MyHC variations, and palisade endings that mediate axon reflexes. Jaw-closing muscles express the high-force masticatory MyHC and cardiac or limb MyHCs depending on the appropriateness for the acquisition and mastication of food. Laryngeal muscles express extraocular and limb muscle MyHCs but shift toward expressing slower MyHCs in large animals. During postnatal development, MyHC expression of craniofacial muscles is subject to neural and hormonal modulation. The primary and secondary myotubes of developing EOMs are postulated to induce, via different retrogradely transported neurotrophins, the rich diversity of neural impulse patterns that regulate the specific MyHCs that they express. Thyroid hormone shifts MyHC 2A toward 2B in jaw muscles, laryngeal muscles and possibly extraocular muscles. This review highlights the fact that the pattern of myosin expression in mammalian craniofacial muscles is principally influenced by the complex interplay of cell lineages, neural impulse patterns, thyroid and other hormones, functional demands and body mass. In these respects, craniofacial muscles are similar to limb muscles, but they differ radically in the types of cell lineage and the nature of their functional demands.
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Affiliation(s)
- Joseph Foon Yoong Hoh
- Discipline of Physiology, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia
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3
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Fu Q, Wang Y, Yan C, Xiang YK. Phosphodiesterase in heart and vessels: from physiology to diseases. Physiol Rev 2024; 104:765-834. [PMID: 37971403 DOI: 10.1152/physrev.00015.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 10/17/2023] [Accepted: 11/08/2023] [Indexed: 11/19/2023] Open
Abstract
Phosphodiesterases (PDEs) are a superfamily of enzymes that hydrolyze cyclic nucleotides, including cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Both cyclic nucleotides are critical secondary messengers in the neurohormonal regulation in the cardiovascular system. PDEs precisely control spatiotemporal subcellular distribution of cyclic nucleotides in a cell- and tissue-specific manner, playing critical roles in physiological responses to hormone stimulation in the heart and vessels. Dysregulation of PDEs has been linked to the development of several cardiovascular diseases, such as hypertension, aneurysm, atherosclerosis, arrhythmia, and heart failure. Targeting these enzymes has been proven effective in treating cardiovascular diseases and is an attractive and promising strategy for the development of new drugs. In this review, we discuss the current understanding of the complex regulation of PDE isoforms in cardiovascular function, highlighting the divergent and even opposing roles of PDE isoforms in different pathogenesis.
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Affiliation(s)
- Qin Fu
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- The Key Laboratory for Drug Target Research and Pharmacodynamic Evaluation of Hubei Province, Wuhan, China
| | - Ying Wang
- Department of Pharmacology, School of Medicine, Southern University of Science and Technology, Shenzhen, China
| | - Chen Yan
- Aab Cardiovascular Research Institute, University of Rochester Medical Center, Rochester, New York, United States
| | - Yang K Xiang
- Department of Pharmacology, University of California at Davis, Davis, California, United States
- Department of Veterans Affairs Northern California Healthcare System, Mather, California, United States
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4
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Hoh JFY. Mechanism of post-tetanic depression of slow muscle fibres. J Comp Physiol B 2024; 194:41-45. [PMID: 38347296 DOI: 10.1007/s00360-024-01536-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 12/04/2023] [Accepted: 01/08/2024] [Indexed: 03/16/2024]
Abstract
A brief tetanic stimulation has a very different effect on the subsequent isometric twitch force of fast and slow skeletal muscles. Fast muscle responds with an enhanced twitch force which doubles that of the pre-tetanic value, whereas slow muscle depresses the post-tetanic twitch by about 20%. Twitch potentiation of fast muscle has long been known to be due to myosin light chain 2 phosphorylation. It is proposed that post-tetanic twitch depression in slow muscle is due to the dephosphorylation of the slow isoform of the thick filament protein, myosin-binding protein-C, by Ca2+/calmodulin-activated phosphatase calcineurin, whilst its phosphorylation underlies the force enhancement due to β-adrenergic stimulation in slow and fast muscle.
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Affiliation(s)
- Joseph Foon Yoong Hoh
- Discipline of Physiology, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, 2006, Australia.
- , A2 Garnet St, Killara, NSW, 2071, Australia.
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5
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Ma W, del Rio CL, Qi L, Prodanovic M, Mijailovich S, Zambataro C, Gong H, Shimkunas R, Gollapudi S, Nag S, Irving TC. Myosin in autoinhibited off state(s), stabilized by mavacamten, can be recruited via inotropic effectors. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.10.536292. [PMID: 37090664 PMCID: PMC10120679 DOI: 10.1101/2023.04.10.536292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Mavacamten is a novel, FDA-approved, small molecule therapeutic designed to regulate cardiac function by selectively but reversibly inhibiting the enzymatic activity of myosin. It shifts myosin towards ordered off states close to the thick filament backbone. It remains unresolved whether mavacamten permanently sequesters these myosin heads in the off state(s) or whether these heads can be recruited in response to physiological stimuli when required to boost cardiac output. We show that cardiac myosins stabilized in these off state(s) by mavacamten are recruitable by Ca2+, increased heart rate, stretch, and β-adrenergic (β-AR) stimulation, all known physiological inotropic effectors. At the molecular level, we show that, in presence of mavacamten, Ca2+ increases myosin ATPase activity by shifting myosin heads from the reserve super-relaxed (SRX) state to the active disordered relaxed (DRX) state. At the myofilament level, both Ca2+ and passive lengthening can shift ordered off myosin heads from positions close to the thick filament backbone to disordered on states closer to the thin filaments in the presence of mavacamten. In isolated rat cardiomyocytes, increased stimulation rates enhanced shortening fraction in mavacamten-treated cells. This observation was confirmed in vivo in telemetered rats, where left-ventricular dP/dtmax, an index of inotropy, increased with heart rate in mavacamten treated animals. Finally, we show that β-AR stimulation in vivo increases left-ventricular function and stroke volume in the setting of mavacamten. Our data demonstrate that the mavacamten-promoted off states of myosin in the thick filament are activable, at least partially, thus leading to preservation of cardiac reserve mechanisms.
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Affiliation(s)
- Weikang Ma
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL, USA
| | - Carlos L. del Rio
- Cardiovascular Drug Discovery, Bristol Myers Squibb, Brisbane, CA 94005
| | - Lin Qi
- Department of Biology, Illinois Institute of Technology, Chicago, IL, USA
| | - Momcilo Prodanovic
- Institute for Information Technologies, University of Kragujevac, Kragujevac, Serbia
- FilamenTech, Inc., Newtown, MA 02458, USA
| | | | | | - Henry Gong
- Department of Biology, Illinois Institute of Technology, Chicago, IL, USA
| | - Rafael Shimkunas
- Cardiovascular Drug Discovery, Bristol Myers Squibb, Brisbane, CA 94005
| | - Sampath Gollapudi
- Cardiovascular Drug Discovery, Bristol Myers Squibb, Brisbane, CA 94005
| | - Suman Nag
- Cardiovascular Drug Discovery, Bristol Myers Squibb, Brisbane, CA 94005
| | - Thomas C. Irving
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL, USA
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6
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Dominic KL, Choi J, Holmes JB, Singh M, Majcher MJ, Stelzer JE. The contribution of N-terminal truncated cMyBPC to in vivo cardiac function. J Gen Physiol 2023; 155:e202213318. [PMID: 37067542 PMCID: PMC10114924 DOI: 10.1085/jgp.202213318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 02/13/2023] [Accepted: 03/24/2023] [Indexed: 04/18/2023] Open
Abstract
Cardiac myosin binding protein C (cMyBPC) is an 11-domain sarcomeric protein (C0-C10) integral to cardiac muscle regulation. In vitro studies have demonstrated potential functional roles for regions beyond the N-terminus. However, the in vivo contributions of these domains are mostly unknown. Therefore, we examined the in vivo consequences of expression of N-terminal truncated cMyBPC (C3C10). Neonatal cMyBPC-/- mice were injected with AAV9-full length (FL), C3C10 cMyBPC, or saline, and echocardiography was performed 6 wk after injection. We then isolated skinned myocardium from virus-treated hearts and performed mechanical experiments. Our results show that expression of C3C10 cMyBPC in cMyBPC-/- mice resulted in a 28% increase in systolic ejection fraction compared to saline-injected cMyBPC-/- mice and a 25% decrease in left ventricle mass-to-body weight ratio. However, unlike expression of FL cMyBPC, there was no prolongation of ejection time compared to saline-injected mice. In vitro mechanical experiments demonstrated that functional improvements in cMyBPC-/- mice expressing C3C10 were primarily due to a 35% reduction in the rate of cross-bridge recruitment at submaximal Ca2+ concentrations when compared to hearts from saline-injected cMyBPC-/- mice. However, unlike the expression of FL cMyBPC, there was no change in the rate of cross-bridge detachment when compared to saline-injected mice. Our data demonstrate that regions of cMyBPC beyond the N-terminus are important for in vivo cardiac function, and have divergent effects on cross-bridge behavior. Elucidating the molecular mechanisms of cMyBPC region-specific function could allow for development of targeted approaches to manipulate specific aspects of cardiac contractile function.
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Affiliation(s)
- Katherine L. Dominic
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Joohee Choi
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Joshua B. Holmes
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Mandeep Singh
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Michael J. Majcher
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Julian E. Stelzer
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
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7
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Salhi HE, Shettigar V, Salyer L, Sturgill S, Brundage EA, Robinett J, Xu Z, Abay E, Lowe J, Janssen PML, Rafael-Fortney JA, Weisleder N, Ziolo MT, Biesiadecki BJ. The lack of Troponin I Ser-23/24 phosphorylation is detrimental to in vivo cardiac function and exacerbates cardiac disease. J Mol Cell Cardiol 2023; 176:84-96. [PMID: 36724829 PMCID: PMC10074981 DOI: 10.1016/j.yjmcc.2023.01.010] [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: 09/08/2022] [Revised: 01/11/2023] [Accepted: 01/24/2023] [Indexed: 01/30/2023]
Abstract
Troponin I (TnI) is a key regulator of cardiac contraction and relaxation with TnI Ser-23/24 phosphorylation serving as a myofilament mechanism to modulate cardiac function. Basal cardiac TnI Ser-23/24 phosphorylation is high such that both increased and decreased TnI phosphorylation may modulate cardiac function. While the effects of increasing TnI Ser-23/24 phosphorylation on heart function are well established, the effects of decreasing TnI Ser-23/24 phosphorylation are not clear. To understand the in vivo role of decreased TnI Ser-23/24 phosphorylation, mice expressing TnI with Ser-23/24 mutated to alanine (TnI S23/24A) that lack the ability to be phosphorylated at these residues were subjected to echocardiography and pressure-volume hemodynamic measurements in the absence or presence of physiological (pacing increasing heart rate or adrenergic stimulation) or pathological (transverse aortic constriction (TAC)) stress. In the absence of pathological stress, the lack of TnI Ser-23/24 phosphorylation impaired systolic and diastolic function. TnI S23/24A mice also had an impaired systolic and diastolic response upon stimulation increased heart rate and an impaired adrenergic response upon dobutamine infusion. Following pathological cardiac stress induced by TAC, TnI S23/24A mice had a greater increase in ventricular mass, worse diastolic function, and impaired systolic and diastolic function upon increasing heart rate. These findings demonstrate that mice lacking the ability to phosphorylate TnI at Ser-23/24 have impaired in vivo systolic and diastolic cardiac function, a blunted cardiac reserve and a worse response to pathological stress supporting decreased TnI Ser23/24 phosphorylation is a modulator of these processes in vivo.
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Affiliation(s)
- Hussam E Salhi
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Vikram Shettigar
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Lorien Salyer
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Sarah Sturgill
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Elizabeth A Brundage
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Joel Robinett
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Zhaobin Xu
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Eaman Abay
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Jeovanna Lowe
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Paul M L Janssen
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Jill A Rafael-Fortney
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Noah Weisleder
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Mark T Ziolo
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Brandon J Biesiadecki
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America.
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8
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Sevrieva IR, Ponnam S, Yan Z, Irving M, Kampourakis T, Sun YB. Phosphorylation-dependent interactions of myosin-binding protein C and troponin coordinate the myofilament response to protein kinase A. J Biol Chem 2023; 299:102767. [PMID: 36470422 PMCID: PMC9826837 DOI: 10.1016/j.jbc.2022.102767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 11/23/2022] [Accepted: 11/24/2022] [Indexed: 12/12/2022] Open
Abstract
PKA-mediated phosphorylation of sarcomeric proteins enhances heart muscle performance in response to β-adrenergic stimulation and is associated with accelerated relaxation and increased cardiac output for a given preload. At the cellular level, the latter translates to a greater dependence of Ca2+ sensitivity and maximum force on sarcomere length (SL), that is, enhanced length-dependent activation. However, the mechanisms by which PKA phosphorylation of the most notable sarcomeric PKA targets, troponin I (cTnI) and myosin-binding protein C (cMyBP-C), lead to these effects remain elusive. Here, we specifically altered the phosphorylation level of cTnI in heart muscle cells and characterized the structural and functional effects at different levels of background phosphorylation of cMyBP-C and with two different SLs. We found Ser22/23 bisphosphorylation of cTnI was indispensable for the enhancement of length-dependent activation by PKA, as was cMyBP-C phosphorylation. This high level of coordination between cTnI and cMyBP-C may suggest coupling between their regulatory mechanisms. Further evidence for this was provided by our finding that cardiac troponin (cTn) can directly interact with cMyBP-C in vitro, in a phosphorylation- and Ca2+-dependent manner. In addition, bisphosphorylation at Ser22/Ser23 increased Ca2+ sensitivity at long SL in the presence of endogenously phosphorylated cMyBP-C. When cMyBP-C was dephosphorylated, bisphosphorylation of cTnI increased Ca2+ sensitivity and decreased cooperativity at both SLs, which may translate to deleterious effects in physiological settings. Our results could have clinical relevance for disease pathways, where PKA phosphorylation of cTnI may be functionally uncoupled from cMyBP-C phosphorylation due to mutations or haploinsufficiency.
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Affiliation(s)
- Ivanka R Sevrieva
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom.
| | - Saraswathi Ponnam
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Ziqian Yan
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Malcolm Irving
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Thomas Kampourakis
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Yin-Biao Sun
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
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Doh C, Dominic KL, Swanberg CE, Bharambe N, Willard BB, Li L, Ramachandran R, Stelzer JE. Identification of Phosphorylation and Other Post-Translational Modifications in the Central C4C5 Domains of Murine Cardiac Myosin Binding Protein C. ACS OMEGA 2022; 7:14189-14202. [PMID: 35573219 PMCID: PMC9089392 DOI: 10.1021/acsomega.2c00799] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 04/05/2022] [Indexed: 05/06/2023]
Abstract
Cardiac myosin binding protein C (cMyBPC) is a critical multidomain protein that modulates myosin cross bridge behavior and cardiac contractility. cMyBPC is principally regulated by phosphorylation of the residues within the M-domain of its N-terminus. However, not much is known about the phosphorylation or other post-translational modification (PTM) landscape of the central C4C5 domains. In this study, the presence of phosphorylation outside the M-domain was confirmed in vivo using mouse models expressing cMyBPC with nonphosphorylatable serine (S) to alanine substitutions. Purified recombinant mouse C4C5 domain constructs were incubated with 13 different kinases, and samples from the 6 strongest kinases were chosen for mass spectrometry analysis. A total of 26 unique phosphorylated peptides were found, representing 13 different phosphorylation sites including 10 novel sites. Parallel reaction monitoring and subsequent mutagenesis experiments revealed that the S690 site (UniProtKB O70468) was the predominant target of PKA and PKG1. We also report 6 acetylation and 7 ubiquitination sites not previously described in the literature. These PTMs demonstrate the possibility of additional layers of regulation and potential importance of the central domains of cMyBPC in cardiac health and disease. Data are available via ProteomeXchange with identifier PXD031262.
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Affiliation(s)
- Chang
Yoon Doh
- Department
of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Katherine L. Dominic
- Department
of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Caitlin E. Swanberg
- Department
of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Nikhil Bharambe
- Department
of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Belinda B. Willard
- Proteomics
and Metabolomics Laboratory, Lerner Research Institute, The Cleveland Clinic Foundation, Cleveland, Ohio 44195, United States
| | - Ling Li
- Proteomics
and Metabolomics Laboratory, Lerner Research Institute, The Cleveland Clinic Foundation, Cleveland, Ohio 44195, United States
| | - Rajesh Ramachandran
- Department
of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Julian E. Stelzer
- Department
of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, United States
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10
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Papadaki M, Kampaengsri T, Barrick SK, Campbell SG, von Lewinski D, Rainer PP, Harris SP, Greenberg MJ, Kirk JA. Myofilament glycation in diabetes reduces contractility by inhibiting tropomyosin movement, is rescued by cMyBPC domains. J Mol Cell Cardiol 2022; 162:1-9. [PMID: 34487755 PMCID: PMC8766917 DOI: 10.1016/j.yjmcc.2021.08.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 07/21/2021] [Accepted: 08/19/2021] [Indexed: 01/17/2023]
Abstract
Diabetes doubles the risk of developing heart failure (HF). As the prevalence of diabetes grows, so will HF unless the mechanisms connecting these diseases can be identified. Methylglyoxal (MG) is a glycolysis by-product that forms irreversible modifications on lysine and arginine, called glycation. We previously found that myofilament MG glycation causes sarcomere contractile dysfunction and is increased in patients with diabetes and HF. The aim of this study was to discover the molecular mechanisms by which MG glycation of myofilament proteins cause sarcomere dysfunction and to identify therapeutic avenues to compensate. In humans with type 2 diabetes without HF, we found increased glycation of sarcomeric actin compared to non-diabetics and it correlated with decreased calcium sensitivity. Depressed calcium sensitivity is pathogenic for HF, therefore myofilament glycation represents a promising therapeutic target to inhibit the development of HF in diabetics. To identify possible therapeutic targets, we further defined the molecular actions of myofilament glycation. Skinned myocytes exposed to 100 μM MG exhibited decreased calcium sensitivity, maximal calcium-activated force, and crossbridge kinetics. Replicating MG's functional affects using a computer simulation of sarcomere function predicted simultaneous decreases in tropomyosin's blocked-to-closed rate transition and crossbridge duty cycle were consistent with all experimental findings. Stopped-flow experiments and ATPase activity confirmed MG decreased the blocked-to-closed transition rate. Currently, no therapeutics target tropomyosin, so as proof-of-principal, we used a n-terminal peptide of myosin-binding protein C, previously shown to alter tropomyosin's position on actin. C0C2 completely rescued MG-induced calcium desensitization, suggesting a possible treatment for diabetic HF.
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Affiliation(s)
- Maria Papadaki
- Department of Cell and Molecular Physiology, Loyola University of Chicago, Maywood, Illinois, USA
| | - Theerachat Kampaengsri
- Department of Cell and Molecular Physiology, Loyola University of Chicago, Maywood, Illinois, USA
| | - Samantha K. Barrick
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, St Louis, Missouri, USA
| | - Stuart G. Campbell
- Department of Bioengineering, Yale University, New Haven, Connecticut, USA
| | | | - Peter P. Rainer
- Division of Cardiology, Medical University of Graz, Graz, Austria
| | - Samantha P. Harris
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA
| | - Michael J. Greenberg
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, St Louis, Missouri, USA
| | - Jonathan A. Kirk
- Department of Cell and Molecular Physiology, Loyola University of Chicago, Maywood, Illinois, USA,Corresponding Author: Jonathan A. Kirk, Ph.D., Department of Cell and Molecular Physiology, Loyola University Chicago Stritch School of Medicine, Center for Translational Research and Education, Room 522, 2160 S. First Ave., Maywood, IL 60153, Ph: 708-216-6348,
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11
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Lv J, Pan Z, Chen J, Xu R, Wang D, Huang J, Dong Y, Jiang J, Yin X, Cheng H, Guo X. Phosphoproteomic Analysis Reveals Downstream PKA Effectors of AKAP Cypher/ZASP in the Pathogenesis of Dilated Cardiomyopathy. Front Cardiovasc Med 2021; 8:753072. [PMID: 34966794 PMCID: PMC8710605 DOI: 10.3389/fcvm.2021.753072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 11/08/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Dilated cardiomyopathy (DCM) is a major cause of heart failure worldwide. The Z-line protein Cypher/Z-band alternatively spliced PDZ-motif protein (ZASP) is closely associated with DCM, both clinically and in animal models. Our earlier work revealed Cypher/ZASP as a PKA-anchoring protein (AKAP) that tethers PKA to phosphorylate target substrates. However, the downstream PKA effectors regulated by AKAP Cypher/ZASP and their relevance to DCM remain largely unknown.Methods and Results: For the identification of candidate PKA substrates, global quantitative phosphoproteomics was performed on cardiac tissue from wild-type and Cypher-knockout mice with PKA activation. A total of 216 phosphopeptides were differentially expressed in the Cypher-knockout mice; 31 phosphorylation sites were selected as candidates using the PKA consensus motifs. Bioinformatic analysis indicated that differentially expressed proteins were enriched mostly in cell adhesion and mRNA processing. Furthermore, the phosphorylation of β-catenin Ser675 was verified to be facilitated by Cypher. This phosphorylation promoted the transcriptional activity of β-catenin, and also the proliferative capacity of cardiomyocytes. Immunofluorescence staining demonstrated that Cypher colocalised with β-catenin in the intercalated discs (ICD) and altered the cytoplasmic distribution of β-catenin. Moreover, the phosphorylation of two other PKA substrates, vimentin Ser72 and troponin I Ser23/24, was suppressed by Cypher deletion.Conclusions: Cypher/ZASP plays an essential role in β-catenin activation via Ser675 phosphorylation, which modulates cardiomyocyte proliferation. Additionally, Cypher/ZASP regulates other PKA effectors, such as vimentin Ser72 and troponin I Ser23/24. These findings establish the AKAP Cypher/ZASP as a signalling hub in the progression of DCM.
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Affiliation(s)
- Jialan Lv
- Department of Cardiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Zhicheng Pan
- Department of Cardiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Jian Chen
- Department of Cardiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Rui Xu
- Department of Cardiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Dongfei Wang
- Department of Cardiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Jiaqi Huang
- Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing, China
| | - Yang Dong
- Department of Cardiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Jing Jiang
- Department of Cardiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Xiang Yin
- Department of Cardiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Hongqiang Cheng
- Department of Pathology and Pathophysiology, Zhejiang University School of Medicine, Hangzhou, China
- *Correspondence: Hongqiang Cheng
| | - Xiaogang Guo
- Department of Cardiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Xiaogang Guo
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12
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Kwon HK, Choi H, Park SG, Park WJ, Kim, DH, Park ZY. Integrated Quantitative Phosphoproteomics and Cell-based Functional Screening Reveals Specific Pathological Cardiac Hypertrophy-related Phosphorylation Sites. Mol Cells 2021; 44:500-516. [PMID: 34158421 PMCID: PMC8334354 DOI: 10.14348/molcells.2021.4002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Accepted: 01/07/2019] [Indexed: 12/29/2022] Open
Abstract
Cardiac hypertrophic signaling cascades resulting in heart failure diseases are mediated by protein phosphorylation. Recent developments in mass spectrometry-based phosphoproteomics have led to the identification of thousands of differentially phosphorylated proteins and their phosphorylation sites. However, functional studies of these differentially phosphorylated proteins have not been conducted in a large-scale or high-throughput manner due to a lack of methods capable of revealing the functional relevance of each phosphorylation site. In this study, an integrated approach combining quantitative phosphoproteomics and cell-based functional screening using phosphorylation competition peptides was developed. A pathological cardiac hypertrophy model, junctate-1 transgenic mice and control mice, were analyzed using label-free quantitative phosphoproteomics to identify differentially phosphorylated proteins and sites. A cell-based functional assay system measuring hypertrophic cell growth of neonatal rat ventricle cardiomyocytes (NRVMs) following phenylephrine treatment was applied, and changes in phosphorylation of individual differentially phosphorylated sites were induced by incorporation of phosphorylation competition peptides conjugated with cell-penetrating peptides. Cell-based functional screening against 18 selected phosphorylation sites identified three phosphorylation sites (Ser-98, Ser-179 of Ldb3, and Ser-1146 of palladin) displaying near-complete inhibition of cardiac hypertrophic growth of NRVMs. Changes in phosphorylation levels of Ser-98 and Ser-179 in Ldb3 were further confirmed in NRVMs and other pathological/physiological hypertrophy models, including transverse aortic constriction and swimming models, using site-specific phospho-antibodies. Our integrated approach can be used to identify functionally important phosphorylation sites among differentially phosphorylated sites, and unlike conventional approaches, it is easily applicable for large-scale and/or high-throughput analyses.
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Affiliation(s)
- Hye Kyeong Kwon
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea
| | - Hyunwoo Choi
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea
| | - Sung-Gyoo Park
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea
| | - Woo Jin Park
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea
| | - Do Han Kim,
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea
| | - Zee-Yong Park
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea
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13
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Abstract
JGP study shows that the phosphorylation state of cMyBPC modulates the ability of omecamtiv mecarbil to enhance myocardial force generation.
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14
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Singh RR, McNamara JW, Sadayappan S. Mutations in myosin S2 alter cardiac myosin-binding protein-C interaction in hypertrophic cardiomyopathy in a phosphorylation-dependent manner. J Biol Chem 2021; 297:100836. [PMID: 34051236 PMCID: PMC8239744 DOI: 10.1016/j.jbc.2021.100836] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 05/18/2021] [Accepted: 05/25/2021] [Indexed: 12/31/2022] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is an inherited cardiovascular disorder primarily caused by mutations in the β-myosin heavy-chain gene. The proximal subfragment 2 region (S2), 126 amino acids of myosin, binds with the C0-C2 region of cardiac myosin-binding protein-C to regulate cardiac muscle contractility in a manner dependent on PKA-mediated phosphorylation. However, it is unknown if HCM-associated mutations within S2 dysregulate actomyosin dynamics by disrupting its interaction with C0-C2, ultimately leading to HCM. Herein, we study three S2 mutations known to cause HCM: R870H, E924K, and E930Δ. First, experiments using recombinant proteins, solid-phase binding, and isothermal titrating calorimetry assays independently revealed that mutant S2 proteins displayed significantly reduced binding with C0-C2. In addition, CD revealed greater instability of the coiled-coil structure in mutant S2 proteins compared with S2Wt proteins. Second, mutant S2 exhibited 5-fold greater affinity for PKA-treated C0-C2 proteins. Third, skinned papillary muscle fibers treated with mutant S2 proteins showed no change in the rate of force redevelopment as a measure of actin–myosin cross-bridge kinetics, whereas S2Wt showed increased the rate of force redevelopment. In summary, S2 and C0-C2 interaction mediated by phosphorylation is altered by mutations in S2, which augment the speed and force of contraction observed in HCM. Modulating this interaction could be a potential strategy to treat HCM in the future.
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Affiliation(s)
- Rohit R Singh
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, Heart, Lung and Vascular Institute, University of Cincinnati, Cincinnati, Ohio, USA
| | - James W McNamara
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, Heart, Lung and Vascular Institute, University of Cincinnati, Cincinnati, Ohio, USA
| | - Sakthivel Sadayappan
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, Heart, Lung and Vascular Institute, University of Cincinnati, Cincinnati, Ohio, USA.
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15
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Mamidi R, Holmes JB, Doh CY, Dominic KL, Madugula N, Stelzer JE. cMyBPC phosphorylation modulates the effect of omecamtiv mecarbil on myocardial force generation. J Gen Physiol 2021; 153:211867. [PMID: 33688929 PMCID: PMC7953254 DOI: 10.1085/jgp.202012816] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 01/27/2021] [Indexed: 01/15/2023] Open
Abstract
Omecamtiv mecarbil (OM), a direct myosin motor activator, is currently being tested as a therapeutic replacement for conventional inotropes in heart failure (HF) patients. It is known that HF patients exhibit dysregulated β-adrenergic signaling and decreased cardiac myosin-binding protein C (cMyBPC) phosphorylation, a critical modulator of myocardial force generation. However, the functional effects of OM in conditions of altered cMyBPC phosphorylation have not been established. Here, we tested the effects of OM on force generation and cross-bridge (XB) kinetics using murine myocardial preparations isolated from wild-type (WT) hearts and from hearts expressing S273A, S282A, and S302A substitutions (SA) in the M domain, between the C1 and C2 domains of cMyBPC, which cannot be phosphorylated. At submaximal Ca2+ activations, OM-mediated force enhancements were less pronounced in SA than in WT myocardial preparations. Additionally, SA myocardial preparations lacked the dose-dependent increases in force that were observed in WT myocardial preparations. Following OM incubation, the basal differences in the rate of XB detachment (krel) between WT and SA myocardial preparations were abolished, suggesting that OM differentially affects the XB behavior when cMyBPC phosphorylation is reduced. Similarly, in myocardial preparations pretreated with protein kinase A to phosphorylate cMyBPC, incubation with OM significantly slowed krel in both the WT and SA myocardial preparations. Collectively, our data suggest there is a strong interplay between the effects of OM and XB behavior, such that it effectively uncouples the sarcomere from cMyBPC phosphorylation levels. Our findings imply that OM may significantly alter the in vivo cardiac response to β-adrenergic stimulation.
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Affiliation(s)
- Ranganath Mamidi
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH
| | - Joshua B Holmes
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH
| | - Chang Yoon Doh
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH
| | - Katherine L Dominic
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH
| | - Nikhil Madugula
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH
| | - Julian E Stelzer
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH
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16
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Liu Y, Chen J, Fontes SK, Bautista EN, Cheng Z. Physiological And Pathological Roles Of Protein Kinase A In The Heart. Cardiovasc Res 2021; 118:386-398. [PMID: 33483740 DOI: 10.1093/cvr/cvab008] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 11/30/2020] [Accepted: 01/08/2021] [Indexed: 12/21/2022] Open
Abstract
Protein kinase A (PKA) is a central regulator of cardiac performance and morphology. Myocardial PKA activation is induced by a variety of hormones, neurotransmitters and stress signals, most notably catecholamines secreted by the sympathetic nervous system. Catecholamines bind β-adrenergic receptors to stimulate cAMP-dependent PKA activation in cardiomyocytes. Elevated PKA activity enhances Ca2+ cycling and increases cardiac muscle contractility. Dynamic control of PKA is essential for cardiac homeostasis, as dysregulation of PKA signaling is associated with a broad range of heart diseases. Specifically, abnormal PKA activation or inactivation contributes to the pathogenesis of myocardial ischemia, hypertrophy, heart failure, as well as diabetic, takotsubo, or anthracycline cardiomyopathies. PKA may also determine sex-dependent differences in contractile function and heart disease predisposition. Here, we describe the recent advances regarding the roles of PKA in cardiac physiology and pathology, highlighting previous study limitations and future research directions. Moreover, we discuss the therapeutic strategies and molecular mechanisms associated with cardiac PKA biology. In summary, PKA could serve as a promising drug target for cardioprotection. Depending on disease types and mechanisms, therapeutic intervention may require either inhibition or activation of PKA. Therefore, specific PKA inhibitors or activators may represent valuable drug candidates for the treatment of heart diseases.
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Affiliation(s)
- Yuening Liu
- Department of Pharmaceutical Sciences, Washington State University, PBS 423, 412 E. Spokane Falls Blvd, ., Spokane, WA, 99202-2131, USA
| | - Jingrui Chen
- Department of Pharmaceutical Sciences, Washington State University, PBS 423, 412 E. Spokane Falls Blvd, ., Spokane, WA, 99202-2131, USA
| | - Shayne K Fontes
- Department of Pharmaceutical Sciences, Washington State University, PBS 423, 412 E. Spokane Falls Blvd, ., Spokane, WA, 99202-2131, USA
| | - Erika N Bautista
- Department of Pharmaceutical Sciences, Washington State University, PBS 423, 412 E. Spokane Falls Blvd, ., Spokane, WA, 99202-2131, USA
| | - Zhaokang Cheng
- Department of Pharmaceutical Sciences, Washington State University, PBS 423, 412 E. Spokane Falls Blvd, ., Spokane, WA, 99202-2131, USA
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17
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Harris SP. Making waves: A proposed new role for myosin-binding protein C in regulating oscillatory contractions in vertebrate striated muscle. J Gen Physiol 2020; 153:211574. [PMID: 33275758 PMCID: PMC7721898 DOI: 10.1085/jgp.202012729] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Myosin-binding protein C (MyBP-C) is a critical regulator of muscle performance that was first identified through its strong binding interactions with myosin, the force-generating protein of muscle. Almost simultaneously with its discovery, MyBP-C was soon found to bind to actin, the physiological catalyst for myosin’s activity. However, the two observations posed an apparent paradox, in part because interactions of MyBP-C with myosin were on the thick filament, whereas MyBP-C interactions with actin were on the thin filament. Despite the intervening decades since these initial discoveries, it is only recently that the dual binding modes of MyBP-C are becoming reconciled in models that place MyBP-C at a central position between actin and myosin, where MyBP-C alternately stabilizes a newly discovered super-relaxed state (SRX) of myosin on thick filaments in resting muscle and then prolongs the “on” state of actin on thin filaments in active muscle. Recognition of these dual, alternating functions of MyBP-C reveals how it is central to the regulation of both muscle contraction and relaxation. The purpose of this Viewpoint is to briefly summarize the roles of MyBP-C in binding to myosin and actin and then to highlight a possible new role for MyBP-C in inducing and damping oscillatory waves of contraction and relaxation. Because the contractile waves bear similarity to cycles of contraction and relaxation in insect flight muscles, which evolved for fast, energetically efficient contraction, the ability of MyBP-C to damp so-called spontaneous oscillatory contractions (SPOCs) has broad implications for previously unrecognized regulatory mechanisms in vertebrate striated muscle. While the molecular mechanisms by which MyBP-C can function as a wave maker or a wave breaker are just beginning to be explored, it is likely that MyBP-C dual interactions with both myosin and actin will continue to be important for understanding the new functions of this enigmatic protein.
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18
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Clark JA, Sewanan LR, Schwan J, Kluger J, Campbell KS, Campbell SG. Fast-relaxing cardiomyocytes exert a dominant role in the relaxation behavior of heterogeneous myocardium. Arch Biochem Biophys 2020; 697:108711. [PMID: 33271148 DOI: 10.1016/j.abb.2020.108711] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 11/05/2020] [Accepted: 11/26/2020] [Indexed: 01/02/2023]
Abstract
Substantial variation in relaxation rate exists among cardiomyocytes within small volumes of myocardium; however, it is unknown how this variability affects the overall relaxation mechanics of heart muscle. In this study, we sought to modulate levels of cellular heterogeneity in a computational model, then validate those predictions using an engineered heart tissue platform. We formulated an in silico tissue model composed of half-sarcomeres with varied relaxation rates, incorporating single-cell cardiomyocyte experimental data. These model tissues randomly sampled relaxation parameters from two offset distributions of fast- and slow-relaxing populations of half-sarcomeres. Isometric muscle twitch simulations predicted a complex relationship between relaxation time and the proportion of fast-versus slow-relaxing cells in heterogeneous tissues. Specifically, a 50/50 mixture of fast and slow cells did not lead to relaxation time that was the mean of the relaxation times associated with the two pure cases. Rather, the mean relaxation time was achieved at a ratio of 70:30 slow:fast relaxing cells, suggesting a disproportionate impact of fast-relaxing cells on overall tissue relaxation. To examine whether this behavior persists in vitro, we constructed engineered heart tissues from two lines of fast- and slow-relaxing human iPSC-derived cardiomyocytes. Cell tracking via fluorescent nanocrystals confirmed the presence of both cell populations in the 50/50 mixed tissues at the time of mechanical characterization. Isometric muscle twitch relaxation times of these mixed-population engineered heart tissues showed agreement with the predictions from the model, namely that the measured relaxation rate of 50/50 mixed tissues more closely resembled that of tissues made with 100% fast-relaxing cells. Our observations suggest that cardiomyocyte diversity can play an important role in determining tissue-level relaxation.
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Affiliation(s)
- J Alexander Clark
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Lorenzo R Sewanan
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Jonas Schwan
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Jonathan Kluger
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Kenneth S Campbell
- Department of Physiology and Division of Cardiovascular Medicine, University of Kentucky, Lexington, KY, USA
| | - Stuart G Campbell
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA; Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT, USA.
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19
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Heinzel FR, Hegemann N, Hohendanner F, Primessnig U, Grune J, Blaschke F, de Boer RA, Pieske B, Schiattarella GG, Kuebler WM. Left ventricular dysfunction in heart failure with preserved ejection fraction-molecular mechanisms and impact on right ventricular function. Cardiovasc Diagn Ther 2020; 10:1541-1560. [PMID: 33224773 DOI: 10.21037/cdt-20-477] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The current classification of heart failure (HF) based on left ventricular (LV) ejection fraction (EF) identifies a large group of patients with preserved ejection fraction (HFpEF) with significant morbidity and mortality but without prognostic benefit from current HF therapy. Co-morbidities and conditions such as arterial hypertension, diabetes mellitus, chronic kidney disease, adiposity and aging shape the clinical phenotype and contribute to mortality. LV diastolic dysfunction and LV structural remodeling are hallmarks of HFpEF, and are linked to remodeling of the cardiomyocyte and extracellular matrix. Pulmonary hypertension (PH) and right ventricular dysfunction (RVD) are particularly common in HFpEF, and mortality is up to 10-fold higher in HFpEF patients with vs. without RV dysfunction. Here, we review alterations in cardiomyocyte function (i.e., ion homeostasis, sarcomere function and cellular metabolism) associated with diastolic dysfunction and summarize the main underlying cellular pathways. The contribution and interaction of systemic and regional upstream signaling such as chronic inflammation, neurohumoral activation, and NO-cGMP-related pathways are outlined in detail, and their diagnostic and therapeutic potential is discussed in the context of preclinical and clinical studies. In addition, we summarize prevalence and pathomechanisms of RV dysfunction in the context of HFpEF and discuss mechanisms connecting LV and RV dysfunction in HFpEF. Dissecting the molecular mechanisms of LV and RV dysfunction in HFpEF may provide a basis for an improved classification of HFpEF and for therapeutic approaches tailored to the molecular phenotype.
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Affiliation(s)
- Frank R Heinzel
- Department of Internal Medicine and Cardiology, Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum, Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, Germany.,Berlin Institute of Health (BIH), Berlin, Germany
| | - Niklas Hegemann
- Department of Internal Medicine and Cardiology, Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum, Berlin, Germany.,Institute of Physiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Felix Hohendanner
- Department of Internal Medicine and Cardiology, Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum, Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, Germany.,Berlin Institute of Health (BIH), Berlin, Germany
| | - Uwe Primessnig
- Department of Internal Medicine and Cardiology, Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum, Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, Germany.,Berlin Institute of Health (BIH), Berlin, Germany
| | - Jana Grune
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, Germany.,Berlin Institute of Health (BIH), Berlin, Germany.,Institute of Physiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Florian Blaschke
- Department of Internal Medicine and Cardiology, Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum, Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, Germany.,Berlin Institute of Health (BIH), Berlin, Germany
| | - Rudolf A de Boer
- Department of Cardiology, Groningen, University Medical Center Groningen, University of Groningen, The Netherlands
| | - Burkert Pieske
- Department of Internal Medicine and Cardiology, Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum, Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, Germany.,Berlin Institute of Health (BIH), Berlin, Germany.,Department of Internal Medicine and Cardiology, German Heart Center, Berlin, Germany
| | | | - Wolfgang M Kuebler
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, Germany.,Berlin Institute of Health (BIH), Berlin, Germany.,Institute of Physiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
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20
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Li J, Mamidi R, Doh CY, Holmes JB, Bharambe N, Ramachandran R, Stelzer JE. AAV9 gene transfer of cMyBPC N-terminal domains ameliorates cardiomyopathy in cMyBPC-deficient mice. JCI Insight 2020; 5:130182. [PMID: 32750038 PMCID: PMC7526450 DOI: 10.1172/jci.insight.130182] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 07/29/2020] [Indexed: 01/05/2023] Open
Abstract
Decreased cardiac myosin-binding protein C (cMyBPC) expression due to inheritable mutations is thought to contribute to the hypertrophic cardiomyopathy (HCM) phenotype, suggesting that increasing cMyBPC content is of therapeutic benefit. In vitro assays show that cMyBPC N-terminal domains (NTDs) contain structural elements necessary and sufficient to modulate actomyosin interactions, but it is unknown if they can regulate in vivo myocardial function. To test whether NTDs can recapitulate the effects of full-length (FL) cMyBPC in rescuing cardiac function in a cMyBPC-null mouse model of HCM, we assessed the efficacy of AAV9 gene transfer of a cMyBPC NTD that contained domains C0C2 and compared its therapeutic potential with AAV9-FL gene replacement. AAV9 vectors were administered systemically at neonatal day 1, when early-onset disease phenotypes begin to manifest. A comprehensive analysis of in vivo and in vitro function was performed following cMyBPC gene transfer. Our results show that a systemic injection of AAV9-C0C2 significantly improved cardiac function (e.g., 52.24 ± 1.69 ejection fraction in the C0C2-treated group compared with 40.07 ± 1.97 in the control cMyBPC–/– group, P < 0.05) and reduced the histopathologic signs of cardiomyopathy. Furthermore, C0C2 significantly slowed and normalized the accelerated cross-bridge kinetics found in cMyBPC–/– control myocardium, as evidenced by a 32.41% decrease in the rate of cross-bridge detachment (krel). Results indicate that C0C2 can rescue biomechanical defects of cMyBPC deficiency and that the NTD may be a target region for therapeutic myofilament kinetic manipulation. Cardiac function improves following AAV9-mediated delivery of the C0C2 domains of cardiac myosin-binding protein C in a mouse model of hypertrophic cardiomyopathy.
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21
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Diurnal Differences in Human Muscle Isometric Force In Vivo Are Associated with Differential Phosphorylation of Sarcomeric M-Band Proteins. Proteomes 2020; 8:proteomes8030022. [PMID: 32859009 PMCID: PMC7565642 DOI: 10.3390/proteomes8030022] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 08/06/2020] [Accepted: 08/25/2020] [Indexed: 12/25/2022] Open
Abstract
We investigated whether diurnal differences in muscle force output are associated with the post-translational state of muscle proteins. Ten physically active men (mean ± SD; age 26.7 ± 3.7 y) performed experimental sessions in the morning (08:00 h) and evening (17:00 h), which were counterbalanced in order of administration and separated by at least 72 h. Knee extensor maximal voluntary isometric contraction (MVIC) force and peak rate of force development (RFD) were measured, and samples of vastus lateralis were collected immediately after exercise. MVIC force was greater in the evening (mean difference of 67 N, 10.2%; p < 0.05). Two-dimensional (2D) gel analysis encompassed 122 proteoforms and discovered 6 significant (p < 0.05; false discovery rate [FDR] = 10%) diurnal differences. Phosphopeptide analysis identified 1693 phosphopeptides and detected 140 phosphopeptides from 104 proteins that were more (p < 0.05, FDR = 22%) phosphorylated in the morning. Myomesin 2, muscle creatine kinase, and the C-terminus of titin exhibited the most robust (FDR < 10%) diurnal differences. Exercise in the morning, compared to the evening, coincided with a greater phosphorylation of M-band-associated proteins in human muscle. These protein modifications may alter the M-band structure and disrupt force transmission, thus potentially explaining the lower force output in the morning.
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22
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Age, Sex and Overall Health, Measured As Frailty, Modify Myofilament Proteins in Hearts From Naturally Aging Mice. Sci Rep 2020; 10:10052. [PMID: 32572088 PMCID: PMC7308399 DOI: 10.1038/s41598-020-66903-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 05/04/2020] [Indexed: 01/10/2023] Open
Abstract
We investigated effects of age, sex and frailty on contractions, calcium transients and myofilament proteins to determine if maladaptive changes associated with aging were sex-specific and modified by frailty. Ventricular myocytes and myofilaments were isolated from middle-aged (~12 mos) and older (~24 mos) mice. Frailty was assessed with a non-invasive frailty index. Calcium transients declined and slowed with age in both sexes, but contractions were largely unaffected. Actomyosin Mg-ATPase activity increased with age in females but not males; this could maintain contractions with smaller calcium transients in females. Phosphorylation of myosin-binding protein C (MyBP-C), desmin, tropomyosin and myosin light chain-1 (MLC-1) increased with age in males, but only MyBP-C and troponin-T increased in females. Enhanced phosphorylation of MyBP-C and MLC-1 could preserve contractions in aging. Interestingly, the age-related decline in Hill coefficients (r = −0.816; p = 0.002) and increase in phosphorylation of desmin (r = 0.735; p = 0.010), tropomyosin (r = 0.779; p = 0.005) and MLC-1 (r = 0.817; p = 0.022) were graded by the level of frailty in males but not females. In these ways, cardiac remodeling at cellular and subcellular levels is graded by overall health in aging males. Such changes may contribute to heart diseases in frail older males, whereas females may be resistant to these effects of frailty.
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Napierski NC, Granger K, Langlais PR, Moran HR, Strom J, Touma K, Harris SP. A Novel "Cut and Paste" Method for In Situ Replacement of cMyBP-C Reveals a New Role for cMyBP-C in the Regulation of Contractile Oscillations. Circ Res 2020; 126:737-749. [PMID: 32078438 DOI: 10.1161/circresaha.119.315760] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE cMyBP-C (cardiac myosin-binding protein-C) is a critical regulator of heart contraction, but the mechanisms by which cMyBP-C affects actin and myosin are only partly understood. A primary obstacle is that cMyBP-C localization on thick filaments may be a key factor defining its interactions, but most in vitro studies cannot duplicate the unique spatial arrangement of cMyBP-C within the sarcomere. OBJECTIVE The goal of this study was to validate a novel hybrid genetic/protein engineering approach for rapid manipulation of cMyBP-C in sarcomeres in situ. METHODS AND RESULTS We designed a novel cut and paste approach for removal and replacement of cMyBP-C N'-terminal domains (C0-C7) in detergent-permeabilized cardiomyocytes from gene-edited Spy-C mice. Spy-C mice express a TEVp (tobacco etch virus protease) cleavage site and a SpyTag (st) between cMyBP-C domains C7 and C8. A cut is achieved using TEVp which cleaves cMyBP-C to create a soluble N'-terminal γC0C7 (endogenous [genetically encoded] N'-terminal domains C0 to C7 of cardiac myosin binding protein-C) fragment and an insoluble C'-terminal SpyTag-C8-C10 fragment that remains associated with thick filaments. Paste of new recombinant (r)C0C7 domains is achieved by a covalent bond formed between SpyCatcher (-sc; encoded at the C'-termini of recombinant proteins) and SpyTag. Results show that loss of γC0C7 reduced myofilament Ca2+ sensitivity and increased cross-bridge cycling (ktr) at submaximal [Ca2+]. Acute loss of γC0C7 also induced auto-oscillatory contractions at submaximal [Ca2+]. Ligation of rC0C7 (exogenous [recombinant] N'-terminal domains C0 to C7 of cardiac myosin binding protein-C)-sc returned pCa50 and ktr to control values and abolished oscillations, but phosphorylated (p)-rC0C7-sc did not completely rescue these effects. CONCLUSIONS We describe a robust new approach for acute removal and replacement of cMyBP-C in situ. The method revealed a novel role for cMyBP-C N'-terminal domains to damp sarcomere-driven contractile waves (so-called spontaneous oscillatory contractions). Because phosphorylated (p)-rC0C7-sc was less effective at damping contractile oscillations, results suggest that spontaneous oscillatory contractions may contribute to enhanced contractility in response to inotropic stimuli.
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Affiliation(s)
- Nathaniel C Napierski
- From the Department of Cellular and Molecular Medicine (N.C.N., K.G., H.R.M, J.S., S.P.H.), University of Arizona College of Medicine, Tucson
| | - Kevin Granger
- From the Department of Cellular and Molecular Medicine (N.C.N., K.G., H.R.M, J.S., S.P.H.), University of Arizona College of Medicine, Tucson
| | - Paul R Langlais
- Division of Endocrinology, Department of Medicine (P.R.L.), University of Arizona College of Medicine, Tucson
| | - Hannah R Moran
- From the Department of Cellular and Molecular Medicine (N.C.N., K.G., H.R.M, J.S., S.P.H.), University of Arizona College of Medicine, Tucson
| | - Joshua Strom
- From the Department of Cellular and Molecular Medicine (N.C.N., K.G., H.R.M, J.S., S.P.H.), University of Arizona College of Medicine, Tucson
| | | | - Samantha P Harris
- From the Department of Cellular and Molecular Medicine (N.C.N., K.G., H.R.M, J.S., S.P.H.), University of Arizona College of Medicine, Tucson
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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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25
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Site-specific phosphorylation of myosin binding protein-C coordinates thin and thick filament activation in cardiac muscle. Proc Natl Acad Sci U S A 2019; 116:15485-15494. [PMID: 31308242 PMCID: PMC6681757 DOI: 10.1073/pnas.1903033116] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Phosphorylation of cardiac myosin binding protein-C (cMyBP-C) is a key regulator of myocardial contractility, and dephosphorylation of cMyBP-C is associated with heart failure. However, the molecular mechanisms underlying contractile regulation by cMyBP-C phosphorylation are poorly understood. We describe the kinase specificity of the multiple phosphorylation sites on cMyBP-C and show that they are interdependent and have distinct effects on the structure of the thin and thick filaments. The results lead to a model of regulation by cMyBP-C phosphorylation through altered affinity of cMyBP-C’s N terminus for thin and thick filaments, as well as their structures and associated regulatory states. Impairment of these mechanisms is likely to underlie the functional effects of mutations in filament proteins associated with cardiomyopathy. The heart’s response to varying demands of the body is regulated by signaling pathways that activate protein kinases which phosphorylate sarcomeric proteins. Although phosphorylation of cardiac myosin binding protein-C (cMyBP-C) has been recognized as a key regulator of myocardial contractility, little is known about its mechanism of action. Here, we used protein kinase A (PKA) and Cε (PKCε), as well as ribosomal S6 kinase II (RSK2), which have different specificities for cMyBP-C’s multiple phosphorylation sites, to show that individual sites are not independent, and that phosphorylation of cMyBP-C is controlled by positive and negative regulatory coupling between those sites. PKA phosphorylation of cMyBP-C’s N terminus on 3 conserved serine residues is hierarchical and antagonizes phosphorylation by PKCε, and vice versa. In contrast, RSK2 phosphorylation of cMyBP-C accelerates PKA phosphorylation. We used cMyBP-C’s regulatory N-terminal domains in defined phosphorylation states for protein–protein interaction studies with isolated cardiac native thin filaments and the S2 domain of cardiac myosin to show that site-specific phosphorylation of this region of cMyBP-C controls its interaction with both the actin-containing thin and myosin-containing thick filaments. We also used fluorescence probes on the myosin-associated regulatory light chain in the thick filaments and on troponin C in the thin filaments to monitor structural changes in the myofilaments of intact heart muscle cells associated with activation of myocardial contraction by the N-terminal region of cMyBP-C in its different phosphorylation states. Our results suggest that cMyBP-C acts as a sarcomeric integrator of multiple signaling pathways that determines downstream physiological function.
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26
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Ahern BM, Levitan BM, Veeranki S, Shah M, Ali N, Sebastian A, Su W, Gong MC, Li J, Stelzer JE, Andres DA, Satin J. Myocardial-restricted ablation of the GTPase RAD results in a pro-adaptive heart response in mice. J Biol Chem 2019; 294:10913-10927. [PMID: 31147441 DOI: 10.1074/jbc.ra119.008782] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 05/16/2019] [Indexed: 12/25/2022] Open
Abstract
Existing therapies to improve heart function target β-adrenergic receptor (β-AR) signaling and Ca2+ handling and often lead to adverse outcomes. This underscores an unmet need for positive inotropes that improve heart function without any adverse effects. The GTPase Ras associated with diabetes (RAD) regulates L-type Ca2+ channel (LTCC) current (ICa,L). Global RAD-knockout mice (gRAD-/-) have elevated Ca2+ handling and increased cardiac hypertrophy, but RAD is expressed also in noncardiac tissues, suggesting the possibility that pathological remodeling is due also to noncardiac effects. Here, we engineered a myocardial-restricted inducible RAD-knockout mouse (RADΔ/Δ). Using an array of methods and techniques, including single-cell electrophysiological and calcium transient recordings, echocardiography, and radiotelemetry monitoring, we found that RAD deficiency results in a sustained increase of inotropy without structural or functional remodeling of the heart. ICa,L was significantly increased, with RAD loss conferring a β-AR-modulated phenotype on basal ICa,L Cardiomyocytes from RADΔ/Δ hearts exhibited enhanced cytosolic Ca2+ handling, increased contractile function, elevated sarcoplasmic/endoplasmic reticulum calcium ATPase 2 (SERCA2a) expression, and faster lusitropy. These results argue that myocardial RAD ablation promotes a beneficial elevation in Ca2+ dynamics, which would obviate a need for increased β-AR signaling to improve cardiac function.
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Affiliation(s)
| | - Bryana M Levitan
- Department of Physiology,; Gill Heart and Vascular Institute, and
| | - Sudhakar Veeranki
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536 and
| | | | - Nemat Ali
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536 and
| | | | | | | | - Jiayang Li
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
| | - Julian E Stelzer
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
| | - Douglas A Andres
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536 and.
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Mamidi R, Li J, Doh CY, Holmes JB, Stelzer JE. Lost in translation: Interpreting cardiac muscle mechanics data in clinical practice. Arch Biochem Biophys 2018; 662:213-218. [PMID: 30576628 DOI: 10.1016/j.abb.2018.12.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 10/25/2018] [Accepted: 12/17/2018] [Indexed: 01/10/2023]
Abstract
Current inotropic therapies improve systolic function in heart failure patients but also elicit undesirable side effects such as arrhythmias and increased intracellular Ca2+ transients. In order to maintain myocyte Ca2+ homeostasis, the increased cytosolic Ca2+ needs to be actively transported back to sarcoplasmic reticulum leading to depleted ATP reserves. Thus, an emerging approach is to design sarcomere-based treatments to correct impaired contractility via a direct and allosteric modulation of myosin's intrinsic force-generating behavior -a concept that potentially avoids the "off-target" effects. To achieve this goal, various biophysical approaches are utilized to investigate the mechanistic impact of sarcomeric modulators but information derived from diverse approaches is not fully integrated into therapeutic applications. This is in part due to the lack of information that provides a coherent connecting link between biophysical data to in vivo function. Hence, our ability to clearly discern the drug-mediated impact on whole-heart function is diminished. Reducing this translational barrier can significantly accelerate clinical progress related to sarcomere-based therapies by optimizing drug-dosing and treatment duration protocols based on information obtained from biophysical studies. Therefore, we attempt to link biophysical mechanical measurements obtained in isolated cardiac muscle and in vivo contractile function.
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Affiliation(s)
- Ranganath Mamidi
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Jiayang Li
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Chang Yoon Doh
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Joshua B Holmes
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Julian E Stelzer
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA.
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Whole-exome sequencing reveals doubly novel heterozygous Myosin Binding Protein C and Titin mutations in a Chinese patient with severe dilated cardiomyopathy. Cardiol Young 2018; 28:1410-1414. [PMID: 30109841 DOI: 10.1017/s1047951118001403] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Dilated Cardiomyopathy is a serious heart disorder that may induce sudden cardiac death and heart failure. Significant progress has been made in understanding the molecular basis of dilated cardiomyopathy. In previous studies, mutations in more than fifty genes have been identified in dilated cardiomyopathy patients. The purpose of this study was to detect the genetic lesion in a family from the central south of China affected by severe dilated cardiomyopathy. METHODS Whole-exome sequencing combined with cardiomyopathy-related genes list were used to analyse the mutations of the proband. Co-segregation analysis was performed by Sanger sequencing.Results and conclusionsTwo novel heterozygous mutations - Myosin Binding Protein C: p.L1014RfsX6 and Titin: p.R9793X - were identified in the proband. The deletion mutation c.3041delT/p.L1014RfsX6 caused a premature stop codon at position 1020 in exon 28 of the Myosin Binding Protein C. The nonsense mutation, c.29377 C>T/ p. R9793X, of Titin was located in the highly evolutionarily conserved domain, resulting in truncation of the Titin protein as well. Co-segregation analysis further revealed that the Myosin Binding Protein C mutation came from his mother and the Titin mutation came from his father. Both mutations are reported in dilated cardiomyopathy patients for the first time. Our study not only provides a unique example of the genes and molecular mechanisms involved in dilated cardiomyopathy but also expands the spectrum of Myosin Binding Protein C and Titin mutations and contributes to the genetic diagnosis and counselling of dilated cardiomyopathy patients.
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29
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Chakouri N, Reboul C, Boulghobra D, Kleindienst A, Nottin S, Gayrard S, Roubille F, Matecki S, Lacampagne A, Cazorla O. Stress-induced protein S-glutathionylation and phosphorylation crosstalk in cardiac sarcomeric proteins - Impact on heart function. Int J Cardiol 2018; 258:207-216. [PMID: 29544934 DOI: 10.1016/j.ijcard.2017.12.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 11/16/2017] [Accepted: 12/01/2017] [Indexed: 11/25/2022]
Abstract
BACKGROUND The interplay between oxidative stress and other signaling pathways in the contractile machinery regulation during cardiac stress and its consequences on cardiac function remains poorly understood. We evaluated the effect of the crosstalk between β-adrenergic and redox signaling on post-translational modifications of sarcomeric regulatory proteins, Myosin Binding Protein-C (MyBP-C) and Troponin I (TnI). METHODS AND RESULTS We mimicked in vitro high level of physiological cardiac stress by forcing rat hearts to produce high levels of oxidized glutathione. This led to MyBP-C S-glutathionylation associated with lower protein kinase A (PKA) dependent phosphorylations of MyBP-C and TnI, increased myofilament Ca2+ sensitivity, and decreased systolic and diastolic properties of the isolated perfused heart. Moderate physiological cardiac stress achieved in vivo with a single 35 min exercise (Low stress induced by exercise, LSE) increased TnI and cMyBP-C phosphorylations and improved cardiac function in vivo (echocardiography) and ex-vivo (isolated perfused heart). High stress induced by exercise (HSE) altered strongly oxidative stress markers and phosphorylations were unchanged despite increased PKA activity. HSE led to in vivo intrinsic cardiac dysfunction associated with myofilament Ca2+ sensitivity defects. To limit protein S-glutathionylation after HSE, we treated rats with N-acetylcysteine (NAC). NAC restored the ability of PKA to modulate myofilament Ca2+ sensitivity and prevented cardiac dysfunction observed in HSE animals. CONCLUSION Under cardiac stress, adrenergic and oxidative signaling pathways work in concert to alter myofilament properties and are key regulators of cardiac function.
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Affiliation(s)
- Nourdine Chakouri
- PHYMEDEXP, INSERM U1046, CNRS UMR9214, Université de Montpellier, CHRU Montpellier, Montpellier, France
| | - Cyril Reboul
- EA 4278, Laboratoire de Pharm-Ecologie Cardiovasculaire, Avignon University, Avignon, France
| | - Doria Boulghobra
- EA 4278, Laboratoire de Pharm-Ecologie Cardiovasculaire, Avignon University, Avignon, France
| | - Adrien Kleindienst
- EA 4278, Laboratoire de Pharm-Ecologie Cardiovasculaire, Avignon University, Avignon, France
| | - Stéphane Nottin
- EA 4278, Laboratoire de Pharm-Ecologie Cardiovasculaire, Avignon University, Avignon, France
| | - Sandrine Gayrard
- EA 4278, Laboratoire de Pharm-Ecologie Cardiovasculaire, Avignon University, Avignon, France
| | - François Roubille
- PHYMEDEXP, INSERM U1046, CNRS UMR9214, Université de Montpellier, CHRU Montpellier, Montpellier, France
| | - Stefan Matecki
- PHYMEDEXP, INSERM U1046, CNRS UMR9214, Université de Montpellier, CHRU Montpellier, Montpellier, France
| | - Alain Lacampagne
- PHYMEDEXP, INSERM U1046, CNRS UMR9214, Université de Montpellier, CHRU Montpellier, Montpellier, France
| | - Olivier Cazorla
- PHYMEDEXP, INSERM U1046, CNRS UMR9214, Université de Montpellier, CHRU Montpellier, Montpellier, France.
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Wang L, Geist J, Grogan A, Hu LYR, Kontrogianni-Konstantopoulos A. Thick Filament Protein Network, Functions, and Disease Association. Compr Physiol 2018; 8:631-709. [PMID: 29687901 DOI: 10.1002/cphy.c170023] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Sarcomeres consist of highly ordered arrays of thick myosin and thin actin filaments along with accessory proteins. Thick filaments occupy the center of sarcomeres where they partially overlap with thin filaments. The sliding of thick filaments past thin filaments is a highly regulated process that occurs in an ATP-dependent manner driving muscle contraction. In addition to myosin that makes up the backbone of the thick filament, four other proteins which are intimately bound to the thick filament, myosin binding protein-C, titin, myomesin, and obscurin play important structural and regulatory roles. Consistent with this, mutations in the respective genes have been associated with idiopathic and congenital forms of skeletal and cardiac myopathies. In this review, we aim to summarize our current knowledge on the molecular structure, subcellular localization, interacting partners, function, modulation via posttranslational modifications, and disease involvement of these five major proteins that comprise the thick filament of striated muscle cells. © 2018 American Physiological Society. Compr Physiol 8:631-709, 2018.
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Affiliation(s)
- Li Wang
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Janelle Geist
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Alyssa Grogan
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Li-Yen R Hu
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
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31
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Mamidi R, Li J, Gresham KS, Verma S, Doh CY, Li A, Lal S, Dos Remedios CG, Stelzer JE. Dose-Dependent Effects of the Myosin Activator Omecamtiv Mecarbil on Cross-Bridge Behavior and Force Generation in Failing Human Myocardium. Circ Heart Fail 2017; 10:CIRCHEARTFAILURE.117.004257. [PMID: 29030372 DOI: 10.1161/circheartfailure.117.004257] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 09/12/2017] [Indexed: 01/10/2023]
Abstract
BACKGROUND Omecamtiv mecarbil (OM) enhances systolic function in vivo by directly binding the myosin cross-bridges (XBs) in the sarcomere. However, the mechanistic details governing OM-induced modulation of XB behavior in failing human myocardium are unclear. METHODS AND RESULTS The effects of OM on steady state and dynamic XB behavior were measured in chemically skinned myocardial preparations isolated from human donor and heart failure (HF) left ventricle. HF myocardium exhibited impaired contractile function as evidenced by reduced maximal force, magnitude of XB recruitment (Pdf), and a slowed rate of XB detachment (krel) at submaximal Ca2+ activations. Ca2+ sensitivity of force generation (pCa50) was higher in HF myocardium when compared with donor myocardium, both prior to and after OM incubations. OM incubation (0.5 and 1.0 μmol/L) enhanced force generation at submaximal Ca2+ activations in a dose-dependent manner. Notably, OM induced a slowing in krel with 1.0 μmol/L OM but not with 0.5 μmol/L OM in HF myocardium. Additionally, OM exerted other differential effects on XB behavior in HF myocardium as evidenced by a greater enhancement in Pdf and slowing in the time course of cooperative XB recruitment (Trec), which collectively prolonged achievement of peak force development (Tpk), compared with donor myocardium. CONCLUSIONS Our findings demonstrate that OM augments force generation but also prolongs the time course of XB transitions to force-bearing states in remodeled HF myocardium, which may extend the systolic ejection time in vivo. Optimal OM dosing is critical for eliciting enhanced systolic function without excessive prolongation of systolic ejection time, which may compromise diastolic filling.
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Affiliation(s)
- Ranganath Mamidi
- From the Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH (R.M., J.L., C.Y.D., J.E.S.); Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (K.S.G); Department of Horticulture Sciences, IFAS, Gulf Coast Research and Education Center, University of Florida, Wimauma (S.V.); Sydney Heart Bank, Discipline of Anatomy & Histology, Bosch Institute, University of Sydney, Australia (A.L., S.L., C.G.d.R.)
| | - Jiayang Li
- From the Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH (R.M., J.L., C.Y.D., J.E.S.); Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (K.S.G); Department of Horticulture Sciences, IFAS, Gulf Coast Research and Education Center, University of Florida, Wimauma (S.V.); Sydney Heart Bank, Discipline of Anatomy & Histology, Bosch Institute, University of Sydney, Australia (A.L., S.L., C.G.d.R.)
| | - Kenneth S Gresham
- From the Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH (R.M., J.L., C.Y.D., J.E.S.); Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (K.S.G); Department of Horticulture Sciences, IFAS, Gulf Coast Research and Education Center, University of Florida, Wimauma (S.V.); Sydney Heart Bank, Discipline of Anatomy & Histology, Bosch Institute, University of Sydney, Australia (A.L., S.L., C.G.d.R.)
| | - Sujeet Verma
- From the Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH (R.M., J.L., C.Y.D., J.E.S.); Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (K.S.G); Department of Horticulture Sciences, IFAS, Gulf Coast Research and Education Center, University of Florida, Wimauma (S.V.); Sydney Heart Bank, Discipline of Anatomy & Histology, Bosch Institute, University of Sydney, Australia (A.L., S.L., C.G.d.R.)
| | - Chang Yoon Doh
- From the Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH (R.M., J.L., C.Y.D., J.E.S.); Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (K.S.G); Department of Horticulture Sciences, IFAS, Gulf Coast Research and Education Center, University of Florida, Wimauma (S.V.); Sydney Heart Bank, Discipline of Anatomy & Histology, Bosch Institute, University of Sydney, Australia (A.L., S.L., C.G.d.R.)
| | - Amy Li
- From the Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH (R.M., J.L., C.Y.D., J.E.S.); Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (K.S.G); Department of Horticulture Sciences, IFAS, Gulf Coast Research and Education Center, University of Florida, Wimauma (S.V.); Sydney Heart Bank, Discipline of Anatomy & Histology, Bosch Institute, University of Sydney, Australia (A.L., S.L., C.G.d.R.)
| | - Sean Lal
- From the Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH (R.M., J.L., C.Y.D., J.E.S.); Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (K.S.G); Department of Horticulture Sciences, IFAS, Gulf Coast Research and Education Center, University of Florida, Wimauma (S.V.); Sydney Heart Bank, Discipline of Anatomy & Histology, Bosch Institute, University of Sydney, Australia (A.L., S.L., C.G.d.R.)
| | - Cristobal G Dos Remedios
- From the Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH (R.M., J.L., C.Y.D., J.E.S.); Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (K.S.G); Department of Horticulture Sciences, IFAS, Gulf Coast Research and Education Center, University of Florida, Wimauma (S.V.); Sydney Heart Bank, Discipline of Anatomy & Histology, Bosch Institute, University of Sydney, Australia (A.L., S.L., C.G.d.R.)
| | - Julian E Stelzer
- From the Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH (R.M., J.L., C.Y.D., J.E.S.); Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (K.S.G); Department of Horticulture Sciences, IFAS, Gulf Coast Research and Education Center, University of Florida, Wimauma (S.V.); Sydney Heart Bank, Discipline of Anatomy & Histology, Bosch Institute, University of Sydney, Australia (A.L., S.L., C.G.d.R.).
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Mickelson AV, Chandra M. Hypertrophic cardiomyopathy mutation in cardiac troponin T (R95H) attenuates length-dependent activation in guinea pig cardiac muscle fibers. Am J Physiol Heart Circ Physiol 2017; 313:H1180-H1189. [PMID: 28842439 DOI: 10.1152/ajpheart.00369.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 08/07/2017] [Accepted: 08/22/2017] [Indexed: 01/14/2023]
Abstract
The central region of cardiac troponin T (TnT) is important for modulating the dynamics of muscle length-mediated cross-bridge recruitment. Therefore, hypertrophic cardiomyopathy mutations in the central region may affect cross-bridge recruitment dynamics to alter myofilament Ca2+ sensitivity and length-dependent activation of cardiac myofilaments. Given the importance of the central region of TnT for cardiac contractile dynamics, we studied if hypertrophic cardiomyopathy-linked mutation (TnTR94H)-induced effects on contractile function would be differently modulated by sarcomere length (SL). Recombinant wild-type TnT (TnTWT) and the guinea pig analog of the human R94H mutation (TnTR95H) were reconstituted into detergent-skinned cardiac muscle fibers from guinea pigs. Steady-state and dynamic contractile measurements were made at short and long SLs (1.9 and 2.3 µm, respectively). Our results demonstrated that TnTR95H increased pCa50 (-log of free Ca2+ concentration) to a greater extent at short SL; TnTR95H increased pCa50 by 0.11 pCa units at short SL and 0.07 pCa units at long SL. The increase in pCa50 associated with an increase in SL from 1.9 to 2.3 µm (ΔpCa50) was attenuated nearly twofold in TnTR95H fibers; ΔpCa50 was 0.09 pCa units for TnTWT fibers but only 0.05 pCa units for TnTR95H fibers. The SL dependency of rate constants of cross-bridge distortion dynamics and tension redevelopment was also blunted by TnTR95H Collectively, our observations on the SL dependency of pCa50 and rate constants of cross-bridge distortion dynamics and tension redevelopment suggest that mechanisms underlying the length-dependent activation cardiac myofilaments are attenuated by TnTR95HNEW & NOTEWORTHY Mutant cardiac troponin T (TnTR95H) differently affects myofilament Ca2+ sensitivity at short and long sarcomere length, indicating that mechanisms underlying length-dependent activation are altered by TnTR95H TnTR95H enhances myofilament Ca2+ sensitivity to a greater extent at short sarcomere length, thus attenuating the length-dependent increase in myofilament Ca2+ sensitivity.
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Affiliation(s)
- Alexis V Mickelson
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington
| | - Murali Chandra
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington
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Mamidi R, Gresham KS, Li J, Stelzer JE. Cardiac myosin binding protein-C Ser 302 phosphorylation regulates cardiac β-adrenergic reserve. SCIENCE ADVANCES 2017; 3:e1602445. [PMID: 28345052 PMCID: PMC5345928 DOI: 10.1126/sciadv.1602445] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 02/02/2017] [Indexed: 05/22/2023]
Abstract
Phosphorylation of cardiac myosin binding protein-C (MyBP-C) modulates cardiac contractile function; however, the specific roles of individual serines (Ser) within the M-domain that are targets for β-adrenergic signaling are not known. Recently, we demonstrated that significant accelerations in in vivo pressure development following β-agonist infusion can occur in transgenic (TG) mouse hearts expressing phospho-ablated Ser282 (that is, TGS282A) but not in hearts expressing phospho-ablation of all three serines [that is, Ser273, Ser282, and Ser302 (TG3SA)], suggesting an important modulatory role for other Ser residues. In this regard, there is evidence that Ser302 phosphorylation may be a key contributor to the β-agonist-induced positive inotropic responses in the myocardium, but its precise functional role has not been established. Thus, to determine the in vivo and in vitro functional roles of Ser302 phosphorylation, we generated TG mice expressing nonphosphorylatable Ser302 (that is, TGS302A). Left ventricular pressure-volume measurements revealed that TGS302A mice displayed no accelerations in the rate of systolic pressure rise and an inability to maintain systolic pressure following dobutamine infusion similar to TG3SA mice, implicating Ser302 phosphorylation as a critical regulator of enhanced systolic performance during β-adrenergic stress. Dynamic strain-induced cross-bridge (XB) measurements in skinned myocardium isolated from TGS302A hearts showed that the molecular basis for impaired β-adrenergic-mediated enhancements in systolic function is due to the absence of protein kinase A-mediated accelerations in the rate of cooperative XB recruitment. These results demonstrate that Ser302 phosphorylation regulates cardiac contractile reserve by enhancing contractile responses during β-adrenergic stress.
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Affiliation(s)
- Ranganath Mamidi
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Kenneth S. Gresham
- Center for Translational Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Jiayang Li
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Julian E. Stelzer
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
- Corresponding author.
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Kriegel AJ, Gartz M, Afzal MZ, de Lange WJ, Ralphe JC, Strande JL. Molecular Approaches in HFpEF: MicroRNAs and iPSC-Derived Cardiomyocytes. J Cardiovasc Transl Res 2016; 10:295-304. [PMID: 28032312 DOI: 10.1007/s12265-016-9723-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 12/15/2016] [Indexed: 01/04/2023]
Abstract
Heart failure with preserved left ventricular ejection fraction (HFpEF) has emerged as one of the largest unmet needs in cardiovascular medicine. HFpEF is increasing in prevalence and causes significant morbidity, mortality, and health care resource utilization. Patients have multiple co-morbidities which contribute to the disease complexity. To date, no effective treatment for HFpEF has been identified. The paucity of cardiac biopsies from this patient population and the absence of well-accepted animal models limit our understanding of the underlying molecular mechanisms of HFpEF. In this review, we discuss combining state-of-the-art technologies of microRNA profiling and human induced pluripotent cell-derived cardiomyocytes (iPSC-CMs) in order to uncover novel molecular pathways that may contribute to the development of HFpEF. Here, we focus the advantages and limitations of microRNA profiling and iPSC-CMs as a disease model system to discover molecular mechanisms in HFpEF.
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Affiliation(s)
- Alison J Kriegel
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Melanie Gartz
- Department of Medicine, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Muhammad Z Afzal
- Department of Medicine, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Willem J de Lange
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - J Carter Ralphe
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Jennifer L Strande
- Department of Medicine, Medical College of Wisconsin, Milwaukee, WI, USA.
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Gresham KS, Mamidi R, Li J, Kwak H, Stelzer JE. Sarcomeric protein modification during adrenergic stress enhances cross-bridge kinetics and cardiac output. J Appl Physiol (1985) 2016; 122:520-530. [PMID: 27909224 DOI: 10.1152/japplphysiol.00306.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 10/21/2016] [Accepted: 11/23/2016] [Indexed: 12/23/2022] Open
Abstract
Molecular adaptations to chronic neurohormonal stress, including sarcomeric protein cleavage and phosphorylation, provide a mechanism to increase ventricular contractility and enhance cardiac output, yet the link between sarcomeric protein modifications and changes in myocardial function remains unclear. To examine the effects of neurohormonal stress on posttranslational modifications of sarcomeric proteins, mice were administered combined α- and β-adrenergic receptor agonists (isoproterenol and phenylephrine, IPE) for 14 days using implantable osmotic pumps. In addition to significant cardiac hypertrophy and increased maximal ventricular pressure, IPE treatment accelerated pressure development and relaxation (74% increase in dP/dtmax and 14% decrease in τ), resulting in a 52% increase in cardiac output compared with saline (SAL)-treated mice. Accelerated pressure development was maintained when accounting for changes in heart rate and preload, suggesting that myocardial adaptations contribute to enhanced ventricular contractility. Ventricular myocardium isolated from IPE-treated mice displayed a significant reduction in troponin I (TnI) and myosin-binding protein C (MyBP-C) expression and a concomitant increase in the phosphorylation levels of the remaining TnI and MyBP-C protein compared with myocardium isolated from saline-treated control mice. Skinned myocardium isolated from IPE-treated mice displayed a significant acceleration in the rate of cross-bridge (XB) detachment (46% increase) and an enhanced magnitude of XB recruitment (43% increase) at submaximal Ca2+ activation compared with SAL-treated mice but unaltered myofilament Ca2+ sensitivity of force generation. These findings demonstrate that sarcomeric protein modifications during neurohormonal stress are molecular adaptations that enhance in vivo ventricular contractility through accelerated XB kinetics to increase cardiac output.NEW & NOTEWORTHY Posttranslational modifications to sarcomeric regulatory proteins provide a mechanism to modulate cardiac function in response to stress. In this study, we demonstrate that neurohormonal stress produces modifications to myosin-binding protein C and troponin I, including a reduction in protein expression within the sarcomere and increased phosphorylation of the remaining protein, which serve to enhance cross-bridge kinetics and increase cardiac output. These findings highlight the importance of sarcomeric regulatory protein modifications in modulating ventricular function during cardiac stress.
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Affiliation(s)
- Kenneth S Gresham
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Ranganath Mamidi
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Jiayang Li
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Hyerin Kwak
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Julian E Stelzer
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio
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Michie KA, Kwan AH, Tung CS, Guss JM, Trewhella J. A Highly Conserved Yet Flexible Linker Is Part of a Polymorphic Protein-Binding Domain in Myosin-Binding Protein C. Structure 2016; 24:2000-2007. [PMID: 27720588 DOI: 10.1016/j.str.2016.08.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2016] [Revised: 08/08/2016] [Accepted: 08/29/2016] [Indexed: 10/20/2022]
Abstract
The nuclear magnetic resonance (NMR) structure of the tri-helix bundle (THB) of the m-domain plus C2 (ΔmC2) of myosin-binding protein C (MyBP-C) has revealed a highly flexible seven-residue linker between the structured THB and C2. Bioinformatics shows significant patterns of conservation across the THB-linker sequence, with the linker containing a strictly conserved serine in all MyBP-C isoforms. Clinically linked mutations further support the functional significance of the THB-linker region. NMR, small-angle X-ray scattering, and binding studies show the THB-linker plus the first ten residues of C2 undergo dramatic changes when ΔmC2 binds Ca2+-calmodulin, with the linker and C2 N-terminal residues contributing significantly to the affinity. Modeling of all available experimental data indicates that the THB tertiary structure must be disrupted to form the complex. These results are discussed in the context of the THB-linker and the N-terminal residues of C2 forming a polymorphic binding domain that could accommodate multiple binding partners in the dynamic sarcomere.
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Affiliation(s)
- Katharine A Michie
- School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
| | - Ann H Kwan
- School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
| | - Chang-Shung Tung
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, NM 87545, USA; Biology Department, University of New Mexico, Albuquerque, NM 87131, USA
| | - J Mitchell Guss
- School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
| | - Jill Trewhella
- School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia.
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Geist J, Kontrogianni-Konstantopoulos A. MYBPC1, an Emerging Myopathic Gene: What We Know and What We Need to Learn. Front Physiol 2016; 7:410. [PMID: 27683561 PMCID: PMC5021714 DOI: 10.3389/fphys.2016.00410] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 08/31/2016] [Indexed: 11/22/2022] Open
Abstract
Myosin Binding Protein-C (MyBP-C) comprises a family of accessory proteins that includes the cardiac, slow skeletal, and fast skeletal isoforms. The three isoforms share structural and sequence homology, and localize at the C-zone of the sarcomeric A-band where they interact with thick and thin filaments to regulate the cycling of actomyosin crossbridges. The cardiac isoform, encoded by MYBPC3, has been extensively studied over the last several decades due to its high mutational rate in congenital hypertrophic and dilated cardiomyopathy. It is only recently, however, that the MYBPC1 gene encoding the slow skeletal isoform (sMyBP-C) has gained attention. Accordingly, during the last 5 years it has been shown that MYBPC1 undergoes extensive exon shuffling resulting in the generation of multiple slow variants, which are co-expressed in different combinations and amounts in both slow and fast skeletal muscles. The sMyBP-C variants are subjected to PKA- and PKC-mediated phosphorylation in constitutive and alternatively spliced sites. More importantly, missense, and nonsense mutations in MYBPC1 have been directly linked with the development of severe and lethal forms of distal arthrogryposis myopathy and muscle tremors. Currently, there is no mammalian animal model of sMyBP-C, but new technologies including CRISPR/Cas9 and xenografting of human biopsies into immunodeficient mice could provide unique ways to study the regulation and roles of sMyBP-C in health and disease.
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Affiliation(s)
- Janelle Geist
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine Baltimore, MD, USA
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Callaghan NI. β-Adrenergic augmentation of cardiac contractility is dependent on PKA-mediated phosphorylation of myosin-binding protein C and troponin I. J Physiol 2016; 594:4707-8. [PMID: 27581566 PMCID: PMC5009792 DOI: 10.1113/jp272333] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 03/26/2016] [Indexed: 11/08/2022] Open
Affiliation(s)
- Neal Ingraham Callaghan
- Department of Chemistry and Biochemistry, Mount Allison University, Sackville, New Brunswick, Canada, E4L 1H3.
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Barbagallo F, Xu B, Reddy GR, West T, Wang Q, Fu Q, Li M, Shi Q, Ginsburg KS, Ferrier W, Isidori AM, Naro F, Patel HH, Bossuyt J, Bers D, Xiang YK. Genetically Encoded Biosensors Reveal PKA Hyperphosphorylation on the Myofilaments in Rabbit Heart Failure. Circ Res 2016; 119:931-43. [PMID: 27576469 DOI: 10.1161/circresaha.116.308964] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2016] [Accepted: 08/29/2016] [Indexed: 01/05/2023]
Abstract
RATIONALE In heart failure, myofilament proteins display abnormal phosphorylation, which contributes to contractile dysfunction. The mechanisms underlying the dysregulation of protein phosphorylation on myofilaments is not clear. OBJECTIVE This study aims to understand the mechanisms underlying altered phosphorylation of myofilament proteins in heart failure. METHODS AND RESULTS We generate a novel genetically encoded protein kinase A (PKA) biosensor anchored onto the myofilaments in rabbit cardiac myocytes to examine PKA activity at the myofilaments in responses to adrenergic stimulation. We show that PKA activity is shifted from the sarcolemma to the myofilaments in hypertrophic failing rabbit myocytes. In particular, the increased PKA activity on the myofilaments is because of an enhanced β2 adrenergic receptor signal selectively directed to the myofilaments together with a reduced phosphodiesterase activity associated with the myofibrils. Mechanistically, the enhanced PKA activity on the myofilaments is associated with downregulation of caveolin-3 in the hypertrophic failing rabbit myocytes. Reintroduction of caveolin-3 in the failing myocytes is able to normalize the distribution of β2 adrenergic receptor signal by preventing PKA signal access to the myofilaments and to restore contractile response to adrenergic stimulation. CONCLUSIONS In hypertrophic rabbit myocytes, selectively enhanced β2 adrenergic receptor signaling toward the myofilaments contributes to elevated PKA activity and PKA phosphorylation of myofilament proteins. Reintroduction of caveolin-3 is able to confine β2 adrenergic receptor signaling and restore myocyte contractility in response to β adrenergic stimulation.
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Affiliation(s)
- Federica Barbagallo
- From the Department of Pharmacology, University of California at Davis (F.B., B.X., G.R.R., T.W., Q.W., Q.F., M.L., Q.S., K.S.G., J.B., D.B., Y.K.X.); Department of Experimental Medicine (F.B., A.M.I.) and Department of Anatomical, Histological, Forensic, and Orthopedic Sciences (F.N.), Sapienza University of Rome, Italy; Department of Medicine and Epidemiology, School of Veterinary Medicine, and Surgical Research Facility, School of Medicine, University of California, Davis (W.F.); VA San Diego Healthcare System, La Jolla, CA (H.H.P.); Department of Anesthesiology, University of California, San Diego, La Jolla (H.H.P.); and VA Northern California Healthcare System, Mather (Y.K.X.)
| | - Bing Xu
- From the Department of Pharmacology, University of California at Davis (F.B., B.X., G.R.R., T.W., Q.W., Q.F., M.L., Q.S., K.S.G., J.B., D.B., Y.K.X.); Department of Experimental Medicine (F.B., A.M.I.) and Department of Anatomical, Histological, Forensic, and Orthopedic Sciences (F.N.), Sapienza University of Rome, Italy; Department of Medicine and Epidemiology, School of Veterinary Medicine, and Surgical Research Facility, School of Medicine, University of California, Davis (W.F.); VA San Diego Healthcare System, La Jolla, CA (H.H.P.); Department of Anesthesiology, University of California, San Diego, La Jolla (H.H.P.); and VA Northern California Healthcare System, Mather (Y.K.X.)
| | - Gopireddy R Reddy
- From the Department of Pharmacology, University of California at Davis (F.B., B.X., G.R.R., T.W., Q.W., Q.F., M.L., Q.S., K.S.G., J.B., D.B., Y.K.X.); Department of Experimental Medicine (F.B., A.M.I.) and Department of Anatomical, Histological, Forensic, and Orthopedic Sciences (F.N.), Sapienza University of Rome, Italy; Department of Medicine and Epidemiology, School of Veterinary Medicine, and Surgical Research Facility, School of Medicine, University of California, Davis (W.F.); VA San Diego Healthcare System, La Jolla, CA (H.H.P.); Department of Anesthesiology, University of California, San Diego, La Jolla (H.H.P.); and VA Northern California Healthcare System, Mather (Y.K.X.)
| | - Toni West
- From the Department of Pharmacology, University of California at Davis (F.B., B.X., G.R.R., T.W., Q.W., Q.F., M.L., Q.S., K.S.G., J.B., D.B., Y.K.X.); Department of Experimental Medicine (F.B., A.M.I.) and Department of Anatomical, Histological, Forensic, and Orthopedic Sciences (F.N.), Sapienza University of Rome, Italy; Department of Medicine and Epidemiology, School of Veterinary Medicine, and Surgical Research Facility, School of Medicine, University of California, Davis (W.F.); VA San Diego Healthcare System, La Jolla, CA (H.H.P.); Department of Anesthesiology, University of California, San Diego, La Jolla (H.H.P.); and VA Northern California Healthcare System, Mather (Y.K.X.)
| | - Qingtong Wang
- From the Department of Pharmacology, University of California at Davis (F.B., B.X., G.R.R., T.W., Q.W., Q.F., M.L., Q.S., K.S.G., J.B., D.B., Y.K.X.); Department of Experimental Medicine (F.B., A.M.I.) and Department of Anatomical, Histological, Forensic, and Orthopedic Sciences (F.N.), Sapienza University of Rome, Italy; Department of Medicine and Epidemiology, School of Veterinary Medicine, and Surgical Research Facility, School of Medicine, University of California, Davis (W.F.); VA San Diego Healthcare System, La Jolla, CA (H.H.P.); Department of Anesthesiology, University of California, San Diego, La Jolla (H.H.P.); and VA Northern California Healthcare System, Mather (Y.K.X.)
| | - Qin Fu
- From the Department of Pharmacology, University of California at Davis (F.B., B.X., G.R.R., T.W., Q.W., Q.F., M.L., Q.S., K.S.G., J.B., D.B., Y.K.X.); Department of Experimental Medicine (F.B., A.M.I.) and Department of Anatomical, Histological, Forensic, and Orthopedic Sciences (F.N.), Sapienza University of Rome, Italy; Department of Medicine and Epidemiology, School of Veterinary Medicine, and Surgical Research Facility, School of Medicine, University of California, Davis (W.F.); VA San Diego Healthcare System, La Jolla, CA (H.H.P.); Department of Anesthesiology, University of California, San Diego, La Jolla (H.H.P.); and VA Northern California Healthcare System, Mather (Y.K.X.)
| | - Minghui Li
- From the Department of Pharmacology, University of California at Davis (F.B., B.X., G.R.R., T.W., Q.W., Q.F., M.L., Q.S., K.S.G., J.B., D.B., Y.K.X.); Department of Experimental Medicine (F.B., A.M.I.) and Department of Anatomical, Histological, Forensic, and Orthopedic Sciences (F.N.), Sapienza University of Rome, Italy; Department of Medicine and Epidemiology, School of Veterinary Medicine, and Surgical Research Facility, School of Medicine, University of California, Davis (W.F.); VA San Diego Healthcare System, La Jolla, CA (H.H.P.); Department of Anesthesiology, University of California, San Diego, La Jolla (H.H.P.); and VA Northern California Healthcare System, Mather (Y.K.X.)
| | - Qian Shi
- From the Department of Pharmacology, University of California at Davis (F.B., B.X., G.R.R., T.W., Q.W., Q.F., M.L., Q.S., K.S.G., J.B., D.B., Y.K.X.); Department of Experimental Medicine (F.B., A.M.I.) and Department of Anatomical, Histological, Forensic, and Orthopedic Sciences (F.N.), Sapienza University of Rome, Italy; Department of Medicine and Epidemiology, School of Veterinary Medicine, and Surgical Research Facility, School of Medicine, University of California, Davis (W.F.); VA San Diego Healthcare System, La Jolla, CA (H.H.P.); Department of Anesthesiology, University of California, San Diego, La Jolla (H.H.P.); and VA Northern California Healthcare System, Mather (Y.K.X.)
| | - Kenneth S Ginsburg
- From the Department of Pharmacology, University of California at Davis (F.B., B.X., G.R.R., T.W., Q.W., Q.F., M.L., Q.S., K.S.G., J.B., D.B., Y.K.X.); Department of Experimental Medicine (F.B., A.M.I.) and Department of Anatomical, Histological, Forensic, and Orthopedic Sciences (F.N.), Sapienza University of Rome, Italy; Department of Medicine and Epidemiology, School of Veterinary Medicine, and Surgical Research Facility, School of Medicine, University of California, Davis (W.F.); VA San Diego Healthcare System, La Jolla, CA (H.H.P.); Department of Anesthesiology, University of California, San Diego, La Jolla (H.H.P.); and VA Northern California Healthcare System, Mather (Y.K.X.)
| | - William Ferrier
- From the Department of Pharmacology, University of California at Davis (F.B., B.X., G.R.R., T.W., Q.W., Q.F., M.L., Q.S., K.S.G., J.B., D.B., Y.K.X.); Department of Experimental Medicine (F.B., A.M.I.) and Department of Anatomical, Histological, Forensic, and Orthopedic Sciences (F.N.), Sapienza University of Rome, Italy; Department of Medicine and Epidemiology, School of Veterinary Medicine, and Surgical Research Facility, School of Medicine, University of California, Davis (W.F.); VA San Diego Healthcare System, La Jolla, CA (H.H.P.); Department of Anesthesiology, University of California, San Diego, La Jolla (H.H.P.); and VA Northern California Healthcare System, Mather (Y.K.X.)
| | - Andrea M Isidori
- From the Department of Pharmacology, University of California at Davis (F.B., B.X., G.R.R., T.W., Q.W., Q.F., M.L., Q.S., K.S.G., J.B., D.B., Y.K.X.); Department of Experimental Medicine (F.B., A.M.I.) and Department of Anatomical, Histological, Forensic, and Orthopedic Sciences (F.N.), Sapienza University of Rome, Italy; Department of Medicine and Epidemiology, School of Veterinary Medicine, and Surgical Research Facility, School of Medicine, University of California, Davis (W.F.); VA San Diego Healthcare System, La Jolla, CA (H.H.P.); Department of Anesthesiology, University of California, San Diego, La Jolla (H.H.P.); and VA Northern California Healthcare System, Mather (Y.K.X.)
| | - Fabio Naro
- From the Department of Pharmacology, University of California at Davis (F.B., B.X., G.R.R., T.W., Q.W., Q.F., M.L., Q.S., K.S.G., J.B., D.B., Y.K.X.); Department of Experimental Medicine (F.B., A.M.I.) and Department of Anatomical, Histological, Forensic, and Orthopedic Sciences (F.N.), Sapienza University of Rome, Italy; Department of Medicine and Epidemiology, School of Veterinary Medicine, and Surgical Research Facility, School of Medicine, University of California, Davis (W.F.); VA San Diego Healthcare System, La Jolla, CA (H.H.P.); Department of Anesthesiology, University of California, San Diego, La Jolla (H.H.P.); and VA Northern California Healthcare System, Mather (Y.K.X.)
| | - Hemal H Patel
- From the Department of Pharmacology, University of California at Davis (F.B., B.X., G.R.R., T.W., Q.W., Q.F., M.L., Q.S., K.S.G., J.B., D.B., Y.K.X.); Department of Experimental Medicine (F.B., A.M.I.) and Department of Anatomical, Histological, Forensic, and Orthopedic Sciences (F.N.), Sapienza University of Rome, Italy; Department of Medicine and Epidemiology, School of Veterinary Medicine, and Surgical Research Facility, School of Medicine, University of California, Davis (W.F.); VA San Diego Healthcare System, La Jolla, CA (H.H.P.); Department of Anesthesiology, University of California, San Diego, La Jolla (H.H.P.); and VA Northern California Healthcare System, Mather (Y.K.X.)
| | - Julie Bossuyt
- From the Department of Pharmacology, University of California at Davis (F.B., B.X., G.R.R., T.W., Q.W., Q.F., M.L., Q.S., K.S.G., J.B., D.B., Y.K.X.); Department of Experimental Medicine (F.B., A.M.I.) and Department of Anatomical, Histological, Forensic, and Orthopedic Sciences (F.N.), Sapienza University of Rome, Italy; Department of Medicine and Epidemiology, School of Veterinary Medicine, and Surgical Research Facility, School of Medicine, University of California, Davis (W.F.); VA San Diego Healthcare System, La Jolla, CA (H.H.P.); Department of Anesthesiology, University of California, San Diego, La Jolla (H.H.P.); and VA Northern California Healthcare System, Mather (Y.K.X.)
| | - Donald Bers
- From the Department of Pharmacology, University of California at Davis (F.B., B.X., G.R.R., T.W., Q.W., Q.F., M.L., Q.S., K.S.G., J.B., D.B., Y.K.X.); Department of Experimental Medicine (F.B., A.M.I.) and Department of Anatomical, Histological, Forensic, and Orthopedic Sciences (F.N.), Sapienza University of Rome, Italy; Department of Medicine and Epidemiology, School of Veterinary Medicine, and Surgical Research Facility, School of Medicine, University of California, Davis (W.F.); VA San Diego Healthcare System, La Jolla, CA (H.H.P.); Department of Anesthesiology, University of California, San Diego, La Jolla (H.H.P.); and VA Northern California Healthcare System, Mather (Y.K.X.)
| | - Yang K Xiang
- From the Department of Pharmacology, University of California at Davis (F.B., B.X., G.R.R., T.W., Q.W., Q.F., M.L., Q.S., K.S.G., J.B., D.B., Y.K.X.); Department of Experimental Medicine (F.B., A.M.I.) and Department of Anatomical, Histological, Forensic, and Orthopedic Sciences (F.N.), Sapienza University of Rome, Italy; Department of Medicine and Epidemiology, School of Veterinary Medicine, and Surgical Research Facility, School of Medicine, University of California, Davis (W.F.); VA San Diego Healthcare System, La Jolla, CA (H.H.P.); Department of Anesthesiology, University of California, San Diego, La Jolla (H.H.P.); and VA Northern California Healthcare System, Mather (Y.K.X.).
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Starr ER, Basuroy T, Fan X, Du S. Phosphorylation of cardiac myosin binding protein-C regulates heart contraction and dilatation in vivo during β-adrenergic receptor activation. J Physiol 2016; 594:4015-6. [PMID: 27417672 DOI: 10.1113/jp272680] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Eric R Starr
- Biomedical Sciences Program in Neurosciences and Neurological Disorders, Department of Neurosciences, College of Medicine and Life Sciences, University of Toledo, 3000 Arlington Avenue, Toledo, OH, 43614, USA.
| | - Tupa Basuroy
- Biomedical Sciences Program in Cancer Biology, Department of Biochemistry and Cancer Biology, College of Medicine and Life Sciences, University of Toledo, 3000 Arlington Avenue, Toledo, OH, 43614, USA
| | - Xiaoming Fan
- Biomedical Sciences Program in Molecular Medicine, Department of Medicine, University of Toledo, College of Medicine and Life Sciences, 3000 Arlington Avenue, Toledo, Ohio, 43614, USA
| | - Shengnan Du
- Biomedical Sciences Program in Cancer Biology, Department of Biochemistry and Cancer Biology, College of Medicine and Life Sciences, University of Toledo, 3000 Arlington Avenue, Toledo, OH, 43614, USA
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Mamidi R, Gresham KS, Verma S, Stelzer JE. Cardiac Myosin Binding Protein-C Phosphorylation Modulates Myofilament Length-Dependent Activation. Front Physiol 2016; 7:38. [PMID: 26913007 PMCID: PMC4753332 DOI: 10.3389/fphys.2016.00038] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 01/28/2016] [Indexed: 11/13/2022] Open
Abstract
Cardiac myosin binding protein-C (cMyBP-C) phosphorylation is an important regulator of contractile function, however, its contributions to length-dependent changes in cross-bridge (XB) kinetics is unknown. Therefore, we performed mechanical experiments to quantify contractile function in detergent-skinned ventricular preparations isolated from wild-type (WT) hearts, and hearts expressing non-phosphorylatable cMyBP-C [Ser to Ala substitutions at residues Ser273, Ser282, and Ser302 (i.e., 3SA)], at sarcomere length (SL) 1.9 μm or 2.1μm, prior and following protein kinase A (PKA) treatment. Steady-state force generation measurements revealed a blunting in the length-dependent increase in myofilament Ca(2+)-sensitivity of force generation (pCa50) following an increase in SL in 3SA skinned myocardium compared to WT skinned myocardium. Dynamic XB behavior was assessed at submaximal Ca(2+)-activations by imposing an acute rapid stretch of 2% of initial muscle length, and measuring both the magnitudes and rates of resultant phases of force decay due to strain-induced XB detachment and delayed force rise due to recruitment of additional XBs with increased SL (i.e., stretch activation). The magnitude (P2) and rate of XB detachment (k rel) following stretch was significantly reduced in 3SA skinned myocardium compared to WT skinned myocardium at short and long SL, and prior to and following PKA treatment. Furthermore, the length-dependent acceleration of k rel due to decreased SL that was observed in WT skinned myocardium was abolished in 3SA skinned myocardium. PKA treatment accelerated the rate of XB recruitment (k df) following stretch at both SL's in WT but not in 3SA skinned myocardium. The amplitude of the enhancement in force generation above initial pre-stretch steady-state levels (P3) was not different between WT and 3SA skinned myocardium at any condition measured. However, the magnitude of the entire delayed force phase which can dip below initial pre-stretch steady-state levels (Pdf) was significantly lower in 3SA skinned myocardium under all conditions, in part due to a reduced magnitude of XB detachment (P2) in 3SA skinned myocardium compared to WT skinned myocardium. These findings demonstrate that cMyBP-C phospho-ablation regulates SL- and PKA-mediated effects on XB kinetics in the myocardium, which would be expected to contribute to the regulation of the Frank-Starling mechanism.
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Affiliation(s)
- Ranganath Mamidi
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University Cleveland, OH, USA
| | - Kenneth S Gresham
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University Cleveland, OH, USA
| | - Sujeet Verma
- Department of Horticultural Science, Institute of Food and Agricultural Sciences Gulf Coast Research and Education Center, University of Florida Wimauma, FL, USA
| | - Julian E Stelzer
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University Cleveland, OH, USA
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