1
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Arlock P, Li M, Davis B, Lövdahl C, Liao Q, Sjöberg T, Rahman A, Wohlfart B, Steen S, Arner A. Excitation and contraction of cardiac muscle and coronary arteries of brain-dead pigs. FASEB Bioadv 2023; 5:71-84. [PMID: 36816513 PMCID: PMC9927844 DOI: 10.1096/fba.2022-00104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 12/04/2022] [Accepted: 12/09/2022] [Indexed: 12/14/2022] Open
Abstract
Excitability and contraction of cardiac muscle from brain-dead donors critically influence the success of heart transplantation. Membrane physiology, Ca2+-handling, and force production of cardiac muscle and the contractile properties of coronary arteries were studied in hearts of brain-dead pigs. Cardiac muscle and vascular function after 12 h brain death (decapitation between C2 and C3) were compared with properties of fresh tissue. In both isolated cardiomyocytes (whole-cell patch clamp) and trabecular muscle (conventional microelectrodes), action potential duration was shorter in brain dead, compared to controls. Cellular shortening and Ca2+ transients were attenuated in the brain dead, and linked to lower mRNA expression of L-type calcium channels and a slightly lower ICa,L, current, as well as to a lower expression of phospholamban. The current-voltage relationship and the current above the equilibrium potential of the inward K+ (IK1) channel were altered in the brain-dead group, associated with lower mRNA expression of the Kir2.2 channel. Delayed K+ currents were detected (IKr, IKs) and were not different between groups. The transient outward K+ current (Ito) was not observed in the pig heart. Coronary arteries exhibited increased contractility and sensitivity to the thromboxane analogue (U46619), and unaltered endothelial relaxation. In conclusion, brain death involves changes in cardiac cellular excitation which might lower contractility after transplantation. Changes in the inward rectifier K+ channel can be associated with an increased risk for arrhythmia. Increased reactivity of coronary arteries may lead to increased risk of vascular spasm, although endothelial relaxant function was well preserved.
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Affiliation(s)
- Per Arlock
- Department of Clinical SciencesLund, Lund UniversityLundSweden
- Department of Physiology and PharmacologyKarolinska InstitutetStockholmSweden
| | - Mei Li
- Department of Clinical SciencesLund, Lund UniversityLundSweden
- Department of Physiology and PharmacologyKarolinska InstitutetStockholmSweden
| | - Benjamin Davis
- Department of Physiology and PharmacologyKarolinska InstitutetStockholmSweden
| | - Cecilia Lövdahl
- Department of Physiology and PharmacologyKarolinska InstitutetStockholmSweden
| | - Qiuming Liao
- Department of Clinical SciencesLund, Lund UniversityLundSweden
| | - Trygve Sjöberg
- Department of Clinical SciencesLund, Lund UniversityLundSweden
| | - Awahan Rahman
- Department of Physiology and PharmacologyKarolinska InstitutetStockholmSweden
| | - Björn Wohlfart
- Department of Clinical SciencesLund, Lund UniversityLundSweden
| | - Stig Steen
- Department of Clinical SciencesLund, Lund UniversityLundSweden
| | - Anders Arner
- Department of Clinical SciencesLund, Lund UniversityLundSweden
- Department of Physiology and PharmacologyKarolinska InstitutetStockholmSweden
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2
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Hou L, Kumar M, Anand P, Chen Y, El-Bizri N, Pickens CJ, Seganish WM, Sadayappan S, Swaminath G. Modulation of myosin by cardiac myosin binding protein-C peptides improves cardiac contractility in ex-vivo experimental heart failure models. Sci Rep 2022; 12:4337. [PMID: 35288601 PMCID: PMC8921245 DOI: 10.1038/s41598-022-08169-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 03/03/2022] [Indexed: 01/23/2023] Open
Abstract
Cardiac myosin binding protein-C (cMyBP-C) is an important regulator of sarcomeric function. Reduced phosphorylation of cMyBP-C has been linked to compromised contractility in heart failure patients. Here, we used previously published cMyBP-C peptides 302A and 302S, surrogates of the regulatory phosphorylation site serine 302, as a tool to determine the effects of modulating the dephosphorylation state of cMyBP-C on cardiac contraction and relaxation in experimental heart failure (HF) models in vitro. Both peptides increased the contractility of papillary muscle fibers isolated from a mouse model expressing cMyBP-C phospho-ablation (cMyBP-CAAA) constitutively. Peptide 302A, in particular, could also improve the force redevelopment rate (ktr) in papillary muscle fibers from cMyBP-CAAA (nonphosphorylated alanines) mice. Consistent with the above findings, both peptides increased ATPase rates in myofibrils isolated from rats with myocardial infarction (MI), but not from sham rats. Furthermore, in the cMyBP-CAAA mouse model, both peptides improved ATPase hydrolysis rates. These changes were not observed in non-transgenic (NTG) mice or sham rats, indicating the specific effects of these peptides in regulating the dephosphorylation state of cMyBP-C under the pathological conditions of HF. Taken together, these studies demonstrate that modulation of cMyBP-C dephosphorylation state can be a therapeutic approach to improve myosin function, sarcomere contractility and relaxation after an adverse cardiac event. Therefore, targeting cMyBP-C could potentially improve overall cardiac performance as a complement to standard-care drugs in HF patients.
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Affiliation(s)
- Luqia Hou
- Cardiometabolic Department, Merck & Co., Inc., 213 East Grand Ave., South San Francisco, CA, 94080, USA
| | - Mohit Kumar
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, Heart, Lung and Vascular Institute, University of Cincinnati, Cincinnati, OH, 45267, USA
| | - Priti Anand
- Cardiometabolic Department, Merck & Co., Inc., 213 East Grand Ave., South San Francisco, CA, 94080, USA
| | - Yinhong Chen
- Cardiometabolic Department, Merck & Co., Inc., 213 East Grand Ave., South San Francisco, CA, 94080, USA
| | - Nesrine El-Bizri
- Cardiometabolic Department, Merck & Co., Inc., 213 East Grand Ave., South San Francisco, CA, 94080, USA
| | - Chad J Pickens
- Analytical R&D, Merck & Co., Inc., South San Francisco, CA, 94080, USA
| | - W Michael Seganish
- Discovery Chemistry, Merck & Co., Inc., South San Francisco, CA, 94080, USA
| | - Sakthivel Sadayappan
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, Heart, Lung and Vascular Institute, University of Cincinnati, Cincinnati, OH, 45267, USA
| | - Gayathri Swaminath
- Cardiometabolic Department, Merck & Co., Inc., 213 East Grand Ave., South San Francisco, CA, 94080, USA.
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3
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Chen YJ, Chien CS, Chiang CE, Chen CH, Cheng HM. From Genetic Mutations to Molecular Basis of Heart Failure Treatment: An Overview of the Mechanism and Implication of the Novel Modulators for Cardiac Myosin. Int J Mol Sci 2021; 22:6617. [PMID: 34205587 PMCID: PMC8234187 DOI: 10.3390/ijms22126617] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 06/11/2021] [Accepted: 06/17/2021] [Indexed: 02/06/2023] Open
Abstract
Heart failure (HF) is a syndrome encompassing several important etiologies that lead to the imbalance between oxygen demand and supply. Despite the usage of guideline-directed medical therapy for HF has shown better outcomes, novel therapeutic strategies are desirable, especially for patients with preserved or mildly reduced left ventricular ejection fraction. In this regard, understanding the molecular basis for cardiomyopathies is expected to fill in the knowledge gap and generate new therapies to improve prognosis for HF. This review discusses an evolutionary mechanism designed to regulate cardiac contraction and relaxation through the most often genetically determined cardiomyopathies associated with HF. In addition, both the myosin inhibitor and myosin activator are promising new treatments for cardiomyopathies. A comprehensive review from genetic mutations to the molecular basis of direct sarcomere modulators will help shed light on future studies for a better characterization of HF etiologies and potential therapeutic targets.
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Affiliation(s)
- Yu-Jen Chen
- Department of Internal Medicine, Division of Cardiovascular Medicine, Wan Fang Hospital, Taipei Medical University, Taipei 116081, Taiwan;
- Department of Internal Medicine, Division of Cardiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 110301, Taiwan
- Institute of Public Health, National Yang Ming Chiao Tung University, Taipei 112304, Taiwan
| | - Chian-Shiu Chien
- Innovative Cellular Therapy Center, Department of Medical Research, Taipei Veterans General Hospital, Taipei 112201, Taiwan;
| | - Chern-En Chiang
- General Clinical Research Center, Taipei Veterans General Hospital, Taipei 112201, Taiwan;
- Department of Medicine, National Yang Ming Chiao Tung University College of Medicine, Taipei 112304, Taiwan
| | - Chen-Huan Chen
- Department of Medical Education, Taipei Veterans General Hospital, Taipei 112201, Taiwan;
- College of Medicine, National Yang Ming Chiao Tung University, Taipei 112201, Taiwan
| | - Hao-Min Cheng
- Institute of Public Health, National Yang Ming Chiao Tung University, Taipei 112304, Taiwan
- Department of Medicine, National Yang Ming Chiao Tung University College of Medicine, Taipei 112304, Taiwan
- Center for Evidence-Based Medicine, Taipei Veterans General Hospital, Taipei 112201, Taiwan
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4
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Nijenkamp LLAM, Bollen IAE, van Velzen HG, Regan JA, van Slegtenhorst M, Niessen HWM, Schinkel AFL, Krüger M, Poggesi C, Ho CY, Kuster DWD, Michels M, van der Velden J. Sex Differences at the Time of Myectomy in Hypertrophic Cardiomyopathy. Circ Heart Fail 2019; 11:e004133. [PMID: 29853478 DOI: 10.1161/circheartfailure.117.004133] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 04/19/2018] [Indexed: 12/13/2022]
Abstract
BACKGROUND One of the first clinically detectable alterations in heart function in hypertrophic cardiomyopathy (HCM) is a decline in diastolic function. Diastolic dysfunction is caused by changes in intrinsic properties of cardiomyocytes or an increase in fibrosis. We investigated whether clinical and cellular parameters of diastolic function are different between male and female patients with HCM at the time of myectomy. METHODS AND RESULTS Cardiac tissue from the interventricular septum of patients with HCM (27 women and 44 men) was obtained during myectomy preceded by echocardiography. At myectomy, female patients were 7 years older than male patients and showed more advanced diastolic dysfunction than men evident from significantly higher values for E/e' ratio, left ventricular filling pattern, tricuspid regurgitation velocity, and left atrial diameter indexed for body surface. Whereas most male patients (56%) showed mild (grade I) diastolic dysfunction, 50% of female patients showed grade III diastolic dysfunction. Passive tension in HCM cardiomyocytes was comparable with controls, and myofilament calcium sensitivity was higher in HCM compared with controls, but no sex differences were observed in myofilament function. In female patients with HCM, titin was more compliant, and more fibrosis was present compared with men. Differences between female and male patients with HCM remained significant after correction for age. CONCLUSIONS Female patients with HCM are older at the time of myectomy and show greater impairment of diastolic function. Furthermore, left ventricular and left atrial remodeling is increased in women when corrected for body surface area. At a cellular level, HCM women showed increased compliant titin and a larger degree of interstitial fibrosis.
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Affiliation(s)
| | - Ilse A E Bollen
- Department of Physiology (L.L.A.M.N., I.A.E.B., J.A.R., D.W.D.K., J.v.d.V.)
| | - Hannah G van Velzen
- VU University Medical Center, Amsterdam, The Netherlands. Department of Cardiology (H.G.v.V., A.F.L.S., M.M.)
| | - Jessica A Regan
- Department of Physiology (L.L.A.M.N., I.A.E.B., J.A.R., D.W.D.K., J.v.d.V.)
| | | | - Hans W M Niessen
- Department of Pathology and Cardiac Surgery, Amsterdam Cardiovascular Sciences (H.W.M.N.)
| | - Arend F L Schinkel
- VU University Medical Center, Amsterdam, The Netherlands. Department of Cardiology (H.G.v.V., A.F.L.S., M.M.)
| | - Martina Krüger
- Erasmus MC, Rotterdam, The Netherlands. Institute of Cardiovascular Physiology, Heinrich Heine University Düsseldorf, Germany (M.K.)
| | - Corrado Poggesi
- Dipartimento di Medicina Sperimentale e Clinica, Università degli Studi di Firenze, Italy (C.P.)
| | - Carolyn Y Ho
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (C.Y.H.)
| | | | - Michelle Michels
- VU University Medical Center, Amsterdam, The Netherlands. Department of Cardiology (H.G.v.V., A.F.L.S., M.M.)
| | - Jolanda van der Velden
- Department of Physiology (L.L.A.M.N., I.A.E.B., J.A.R., D.W.D.K., J.v.d.V.) .,Netherlands Heart Institute, Utrecht (J.v.d.V.)
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5
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Vikhorev PG, Vikhoreva NN. Cardiomyopathies and Related Changes in Contractility of Human Heart Muscle. Int J Mol Sci 2018; 19:ijms19082234. [PMID: 30065175 PMCID: PMC6121228 DOI: 10.3390/ijms19082234] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Revised: 07/22/2018] [Accepted: 07/27/2018] [Indexed: 02/07/2023] Open
Abstract
About half of hypertrophic and dilated cardiomyopathies cases have been recognized as genetic diseases with mutations in sarcomeric proteins. The sarcomeric proteins are involved in cardiomyocyte contractility and its regulation, and play a structural role. Mutations in non-sarcomeric proteins may induce changes in cell signaling pathways that modify contractile response of heart muscle. These facts strongly suggest that contractile dysfunction plays a central role in initiation and progression of cardiomyopathies. In fact, abnormalities in contractile mechanics of myofibrils have been discovered. However, it has not been revealed how these mutations increase risk for cardiomyopathy and cause the disease. Much research has been done and still much is being done to understand how the mechanism works. Here, we review the facts of cardiac myofilament contractility in patients with cardiomyopathy and heart failure.
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Affiliation(s)
- Petr G Vikhorev
- National Heart and Lung Institute, Imperial College London, London W12 0NN, UK.
| | - Natalia N Vikhoreva
- Heart Science Centre, Magdi Yacoub Institute, Harefield Hospital, London UB9 6JH, UK.
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6
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Bollen IAE, van der Meulen M, de Goede K, Kuster DWD, Dalinghaus M, van der Velden J. Cardiomyocyte Hypocontractility and Reduced Myofibril Density in End-Stage Pediatric Cardiomyopathy. Front Physiol 2017; 8:1103. [PMID: 29312005 PMCID: PMC5743800 DOI: 10.3389/fphys.2017.01103] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 12/13/2017] [Indexed: 12/25/2022] Open
Abstract
Dilated cardiomyopathy amongst children (pediatric cardiomyopathy, pediatric CM) is associated with a high morbidity and mortality. Because little is known about the pathophysiology of pediatric CM, treatment is largely based on adult heart failure therapy. The reason for high morbidity and mortality is largely unknown as well as data on cellular pathomechanisms is limited. Here, we assessed cardiomyocyte contractility and protein expression to define cellular pathomechanisms in pediatric CM. Explanted heart tissue of 11 pediatric CM patients and 18 controls was studied. Contractility was measured in single membrane-permeabilized cardiomyocytes and protein expression was assessed with gel electrophoresis and western blot analysis. We observed increased Ca2+-sensitivity of myofilaments which was due to hypophosphorylation of cardiac troponin I, a feature commonly observed in adult DCM. We also found a significantly reduced maximal force generating capacity of pediatric CM cardiomyocytes, as well as a reduced passive force development over a range of sarcomere lengths. Myofibril density was reduced in pediatric CM compared to controls. Correction of maximal force and passive force for myofibril density normalized forces in pediatric CM cardiomyocytes to control values. This implies that the hypocontractility was caused by the reduction in myofibril density. Unlike in adult DCM we did not find an increase in compliant titin isoform expression in end-stage pediatric CM. The limited ability of pediatric CM patients to maintain myofibril density might have contributed to their early disease onset and severity.
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Affiliation(s)
- Ilse A E Bollen
- Department of Physiology, Amsterdam Cardiovascular Sciences, VU University Medical Center, Amsterdam, Netherlands
| | - Marijke van der Meulen
- Department of Pediatric Cardiology, Erasmus Medical Center, Erasmus University Rotterdam, Rotterdam, Netherlands
| | - Kyra de Goede
- Department of Physiology, Amsterdam Cardiovascular Sciences, VU University Medical Center, Amsterdam, Netherlands
| | - Diederik W D Kuster
- Department of Physiology, Amsterdam Cardiovascular Sciences, VU University Medical Center, Amsterdam, Netherlands
| | - Michiel Dalinghaus
- Department of Pediatric Cardiology, Erasmus Medical Center, Erasmus University Rotterdam, Rotterdam, Netherlands
| | - Jolanda van der Velden
- Department of Physiology, Amsterdam Cardiovascular Sciences, VU University Medical Center, Amsterdam, Netherlands.,Netherlands Heart Institute, Utrecht, Netherlands
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7
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Rajtik T, Goncalvesova E, Varga ZV, Leszek P, Kusmierczyk M, Hulman M, Kyselovic J, Ferdinandy P, Adameova A. Posttranslational modifications of calcium/calmodulin-dependent protein kinase IIδ and its downstream signaling in human failing hearts. Am J Transl Res 2017; 9:3573-3585. [PMID: 28861149 PMCID: PMC5575172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 07/16/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND In human failing hearts (HF) of different origin (coronary artery disease-CAD, dilated-DCM, restrictive and hypertrophic cardiomyopathy-OTHER), we investigated the active forms of Ca2+/calmodulin-dependent protein kinase IIδ (p-Thr287-CaMKIIδ, oxMet281/282-CaMKIIδ) and their role in phenotypes of the disease. METHODS AND RESULTS Although basic diagnostic and clinical markers indicating the attenuated cardiac contractility and remodeling were comparable in HF groups, CaMKIIδ-mediated axis was different. P-Thr287-CaMKIIδ was unaltered in CAD group, whereas it was upregulated in non-ischemic cardiomyopathic groups. No correlation between the upregulated p-Thr287-CaMKIIδ and QT interval prolongation was detected. Unlike in DCM, oxMet281/282-CaMKIIδ did not differ among HF groups. Independently of CaMKIIδ phosphorylation/oxidation, activation of its downstreams-phospholamban and cardiac myosin binding protein-C was significantly downregulated supporting both diminished cardiac lusitropy and inotropy in all hearts. Content of sarcoplasmic reticulum Ca2+-ATPase 2a in all HF was unchanged. Protein phosphatase1β was upregulated in CAD and DCM only, while 2A did not differ among groups. CONCLUSION This is the first demonstration that the posttranslational activation of CaMKIIδ differs in HF depending on etiology. Lower levels of downstream molecular targets of CaMKIIδ do not correlate with either activation of CaMKIIδ or the expression of major protein phosphatases in the HF. Thus, it is unlikely that these mechanisms exclusively underlie failing of the heart.
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Affiliation(s)
- Tomas Rajtik
- Department of Pharmacology & Toxicology, Faculty of Pharmacy, Comenius UniversityBratislava, Slovak Republic
| | - Eva Goncalvesova
- Department of Heart Failure & Transplantation, The National Institute of Cardiovascular DiseasesBratislava, Slovak Republic
| | - Zoltan V Varga
- Department of Pharmacology & Pharmacotherapy, Semmelweis UniversityBudapest, Hungary
| | | | | | - Michal Hulman
- Clinic of Heart Surgery, The National Institute of Cardiovascular DiseasesBratislava, Slovak Republic
| | - Jan Kyselovic
- Department of Pharmacology & Toxicology, Faculty of Pharmacy, Comenius UniversityBratislava, Slovak Republic
| | - Peter Ferdinandy
- Department of Pharmacology & Pharmacotherapy, Semmelweis UniversityBudapest, Hungary
| | - Adriana Adameova
- Department of Pharmacology & Toxicology, Faculty of Pharmacy, Comenius UniversityBratislava, Slovak Republic
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8
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Abstract
Various human diseases can disrupt the balance between muscle contraction and relaxation. Sarcomeric modulators can be used to readjust this balance either indirectly by intervening in signalling pathways or directly through interaction with the muscle proteins that control contraction. Such agents represent a novel approach to treating any condition in which striated muscle function is compromised, including heart failure, cardiomyopathies, skeletal myopathies and a wide range of neuromuscular conditions. Here, we review agents that modulate the mechanical function of the sarcomere, focusing on emerging compounds that target myosin or the troponin complex.
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9
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Witjas-Paalberends ER, Piroddi N, Stam K, van Dijk SJ, Oliviera VS, Ferrara C, Scellini B, Hazebroek M, ten Cate FJ, van Slegtenhorst M, dos Remedios C, Niessen HWM, Tesi C, Stienen GJM, Heymans S, Michels M, Poggesi C, van der Velden J. Mutations in MYH7 reduce the force generating capacity of sarcomeres in human familial hypertrophic cardiomyopathy. Cardiovasc Res 2013; 99:432-41. [PMID: 23674513 DOI: 10.1093/cvr/cvt119] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS Familial hypertrophic cardiomyopathy (HCM), frequently caused by sarcomeric gene mutations, is characterized by cellular dysfunction and asymmetric left-ventricular (LV) hypertrophy. We studied whether cellular dysfunction is due to an intrinsic sarcomere defect or cardiomyocyte remodelling. METHODS AND RESULTS Cardiac samples from 43 sarcomere mutation-positive patients (HCMmut: mutations in thick (MYBPC3, MYH7) and thin (TPM1, TNNI3, TNNT2) myofilament genes) were compared with 14 sarcomere mutation-negative patients (HCMsmn), eight patients with secondary LV hypertrophy due to aortic stenosis (LVHao) and 13 donors. Force measurements in single membrane-permeabilized cardiomyocytes revealed significantly lower maximal force generating capacity (Fmax) in HCMmut (21 ± 1 kN/m²) and HCMsmn (26 ± 3 kN/m²) compared with donor (36 ± 2 kN/m²). Cardiomyocyte remodelling was more severe in HCMmut compared with HCMsmn based on significantly lower myofibril density (49 ± 2 vs. 63 ± 5%) and significantly higher cardiomyocyte area (915 ± 15 vs. 612 ± 11 μm²). Low Fmax in MYBPC3mut, TNNI3mut, HCMsmn, and LVHao was normalized to donor values after correction for myofibril density. However, Fmax was significantly lower in MYH7mut, TPM1mut, and TNNT2mut even after correction for myofibril density. In accordance, measurements in single myofibrils showed very low Fmax in MYH7mut, TPM1mut, and TNNT2mut compared with donor (respectively, 73 ± 3, 70 ± 7, 83 ± 6, and 113 ± 5 kN/m²). In addition, force was lower in MYH7mut cardiomyocytes compared with MYBPC3mut, HCMsmn, and donor at submaximal [Ca²⁺]. CONCLUSION Low cardiomyocyte Fmax in HCM patients is largely explained by hypertrophy and reduced myofibril density. MYH7 mutations reduce force generating capacity of sarcomeres at maximal and submaximal [Ca²⁺]. These hypocontractile sarcomeres may represent the primary abnormality in patients with MYH7 mutations.
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Affiliation(s)
- E Rosalie Witjas-Paalberends
- Laboratory for Physiology, VU University Medical Center, Institute for Cardiovascular Research, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands.
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10
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Hahn NE, Meischl C, Kawahara T, Musters RJP, Verhoef VMJ, van der Velden J, Vonk ABA, Paulus WJ, van Rossum AC, Niessen HWM, Krijnen PAJ. NOX5 expression is increased in intramyocardial blood vessels and cardiomyocytes after acute myocardial infarction in humans. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 180:2222-9. [PMID: 22503554 DOI: 10.1016/j.ajpath.2012.02.018] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Revised: 01/23/2012] [Accepted: 02/21/2012] [Indexed: 12/28/2022]
Abstract
Reactive oxygen species producing NADPH oxidases play important roles under different (patho)physiological conditions. NOX1, NOX2, and NOX4 are important sources of reactive oxygen species in the heart, but knowledge of the calcium-dependent NOX5 in the heart is lacking. The presence of NOX5 was studied via RT-PCR in heart tissue from patients with end-stage heart failure; the tissue was obtained during cardiac transplantation surgery. NOX5 positivity and cellular localization were studied via IHC and digital-imaging microscopy in heart tissues of patients who did not have heart disease and in infarction areas of patients who died of myocardial infarctions of different durations. Furthermore, NOX5 expression was analyzed in vitro by using Western blot analysis. NOX5 RNA was found in the hearts of controls and patients with ischemic cardiomyopathy. In controls, NOX5 localized to the endothelium of a limited number of intramyocardial blood vessels and to a limited number of scattered cardiomyocytes. In infarcted hearts, NOX5 expression increased, especially in infarctions >12 hours, which manifested as an increase in NOX5-positive intramyocardial blood vessels, as well as in endothelium, smooth muscle, and cardiomyocytes. NOX5 was found in cardiomyocyte cytoplasm, plasma membrane, intercalated disks, and cross striations. Western blot analysis confirmed NOX5 expression in isolated human cardiomyocytes. For the first time to our knowledge, we demonstrate NOX5 expression in human intramyocardial blood vessels and cardiomyocytes, with significant increases in the affected myocardium after acute myocardial infarction.
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Affiliation(s)
- Nynke E Hahn
- Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands.
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11
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Kuster DWD, Bawazeer AC, Zaremba R, Goebel M, Boontje NM, van der Velden J. Cardiac myosin binding protein C phosphorylation in cardiac disease. J Muscle Res Cell Motil 2011; 33:43-52. [PMID: 22127559 PMCID: PMC3351594 DOI: 10.1007/s10974-011-9280-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Accepted: 11/23/2011] [Indexed: 12/14/2022]
Abstract
Perturbations in sarcomeric function may in part underlie systolic and diastolic dysfunction of the failing heart. Sarcomeric dysfunction has been ascribed to changes in phosphorylation status of sarcomeric proteins caused by an altered balance between intracellular kinases and phosphatases during the development of cardiac disease. In the present review we discuss changes in phosphorylation of the thick filament protein myosin binding protein C (cMyBP-C) reported in failing myocardium, with emphasis on phosphorylation changes observed in familial hypertrophic cardiomyopathy caused by mutations in MYBPC3. Moreover, we will discuss assays which allow to distinguish between functional consequences of mutant sarcomeric proteins and (mal)adaptive changes in sarcomeric protein phosphorylation.
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MESH Headings
- Animals
- Calcium/metabolism
- Cardiomyopathy, Hypertrophic, Familial/genetics
- Cardiomyopathy, Hypertrophic, Familial/metabolism
- Cardiomyopathy, Hypertrophic, Familial/pathology
- Carrier Proteins/genetics
- Carrier Proteins/metabolism
- Cyclic AMP-Dependent Protein Kinases/metabolism
- Heart Failure, Systolic/metabolism
- Heart Failure, Systolic/pathology
- Humans
- Mice
- Mice, Transgenic
- Mutation
- Myocardium/metabolism
- Myocardium/pathology
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Phosphoric Monoester Hydrolases/metabolism
- Phosphorylation
- Sarcomeres/metabolism
- Sarcomeres/pathology
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Affiliation(s)
- Diederik W D Kuster
- Department of Physiology, VU University Medical Center, Amsterdam, The Netherlands.
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12
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Walker LA, Walker JS, Glazier A, Brown DR, Stenmark KR, Buttrick PM. Biochemical and myofilament responses of the right ventricle to severe pulmonary hypertension. Am J Physiol Heart Circ Physiol 2011; 301:H832-40. [PMID: 21622821 DOI: 10.1152/ajpheart.00249.2011] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Right ventricular (RV) failure is one of the strongest predictors of mortality both in the presence of left ventricular decompensation and in the context of pulmonary vascular disease. Despite this, there is a limited understanding of the biochemical and mechanical characteristics of the pressure-overloaded RV at the level of the cardiac myocyte. To better understand this, we studied ventricular muscle obtained from neonatal calves that were subjected to hypobaric atmospheric conditions, which result in profound pulmonary hypertension. We found that RV pressure overload resulted in significant changes in the phosphorylation of key contractile proteins. Total phosphorylation of troponin I was decreased with pressure overload, predominantly reflecting changes at the putative PKA site at Ser(22/23). Similarly, both troponin T and myosin light chain 2 showed a significant decline in phosphorylation. Desmin was unchanged, and myosin-binding protein C (MyBP-C) phosphorylation was apparently increased. However, the apparent increase in MyBP-C phosphorylation was not due to phosphorylation but rather to an increase in MyBP-C total protein. Importantly, these findings were seen in all regions of the RV and were paralleled by reduced Ca(2+) sensitivity with preserved maximal Ca(2+) saturated developed force normalized to cross-sectional area in isolated skinned right ventricular myocyte fragments. No changes in total force or cooperativity were seen. Taken together, these results suggest that RV failure is mechanistically unique from left ventricular failure.
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Affiliation(s)
- Lori A Walker
- Department of Medicine, University of Colorado-Denver, Aurora, Colorado 80045, USA.
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Diastolic myofilament dysfunction in the failing human heart. Pflugers Arch 2011; 462:155-63. [PMID: 21487693 PMCID: PMC3114087 DOI: 10.1007/s00424-011-0960-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Revised: 03/23/2011] [Accepted: 03/24/2011] [Indexed: 01/06/2023]
Abstract
In recent years, it has become evident that heart failure is not solely due to reduced contractile performance of the heart muscle as impaired relaxation is evident in almost all heart failure patients. In more than half of all heart failure patients, diastolic dysfunction is the major cardiac deficit. These heart failure patients have normal (or preserved) left ventricular ejection fraction, but impaired diastolic function evident from increased left ventricular end-diastolic pressure. Perturbations at the cellular level which cause impaired relaxation of the heart muscle involve changes in Ca(2+)-handling proteins, extracellular matrix components, and myofilament properties. The present review discusses the deficits in myofilament function observed in human heart failure and the most likely underlying causal protein changes. Moreover, the consequences of impaired myofilament function for in vivo diastolic dysfunction are discussed taking into account the reported changes in Ca(2+) handling.
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Tissue procurement strategies affect the protein biochemistry of human heart samples. J Muscle Res Cell Motil 2010; 31:309-14. [PMID: 21184256 DOI: 10.1007/s10974-010-9233-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Accepted: 12/05/2010] [Indexed: 12/30/2022]
Abstract
The ability to analyze the biochemical properties of human cardiac tissue is critical both to an understanding of cardiac pathology and also to the development of novel pharmacotherapies. However current strategies for tissue procurement are not uniform and are potentially biased. In this study we contrasted several commonly used approaches for tissue sampling in order to determine their impact on contractile protein biochemistry. Not surprisingly our results show that different tissue handling strategies have the potential to produce a wide variation in the phosphorylation and proteolysis of selected contractile proteins. However this was not uniform: phosphorylation of troponin I (TnI) and myosin light chain 2 (MLC2) varied significantly depending on approach whereas changes in desmin and myosin binding protein C (MyBP-C) were relatively unaffected. Moreover, some strategies increased whereas others reduced TnI phosphorylation, suggesting a dynamic balance between kinase and phosphatase activities. Overall, procurement strategies that involved maintenance of tissue in cardioplegia solution deviated most dramatically from prompt and rapid tissue immersion in liquid nitrogen.
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Analysis of cardiac myosin binding protein-C phosphorylation in human heart muscle. J Mol Cell Cardiol 2010; 49:1003-11. [PMID: 20850451 DOI: 10.1016/j.yjmcc.2010.09.007] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Revised: 09/06/2010] [Accepted: 09/08/2010] [Indexed: 11/23/2022]
Abstract
A unique feature of MyBP-C in cardiac muscle is that it has multiple phosphorylation sites. MyBP-C phosphorylation, predominantly by PKA, plays an essential role in modulating contractility as part of the cellular response to β-adrenergic stimulation. In vitro studies indicate MyBP-C can be phosphorylated at Serine 273, 282, 302 and 307 (mouse sequence) but little is known about the level of MyBP-C phosphorylation or the sites phosphorylated in heart muscle. Since current methodologies are limited in specificity and are not quantitative we have investigated the use of phosphate affinity SDS-PAGE together with a total anti MyBP-C antibody and a range of phosphorylation site-specific antibodies for the main sites (Ser-273, -282 and -302). With these newly developed methods we have been able to make a detailed quantitative analysis of MyBP-C phosphorylation in heart tissue in situ. We have found that MyBP-C is highly phosphorylated in non-failing human (donor) heart or mouse heart; tris and tetra-phosphorylated species predominate and less than 10% of MyBP-C is unphosphorylated (0, 9.3 ± 1%: 1P, 13.4 ± 2.7%: 2P, 10.5 ± 3.3%: 3P, 28.7 ± 3.7%: 4P, 36.4 ± 2.7%, n=21). Total phosphorylation was 2.7 ± 0.07 mol Pi/mol MyBP-C. In contrast in failing heart and in myectomy samples from HCM patients the majority of MyBP-C was unphosphorylated. Total phosphorylation levels were 23% of normal in failing heart myofibrils (0, 60.1 ± 2.8%: 1P, 27.8 ± 2.8%: 2P, 4.8 ± 2.0%: 3P, 3.7 ± 1.2%: 4P, 2.8 ± 1.3%, n=19) and 39% of normal in myectomy samples. The site-specific antibodies showed a distinctive distribution pattern of phosphorylation sites in the multiple phosphorylation level species. We found that phosphorylated Ser-273, Ser-282 and Ser-302 were all present in the 4P band of MyBP-C but none of them were significant in the 1P band, indicating that there must be at least one other site of MyBP-C phosphorylation in human heart. The pattern of phosphorylation at the three sites was not random, but indicated positive and negative interactions between the three sites. Phosphorylation at Ser-282 was not proportional to the number of sites available. The 2P band contained 302 but not 273; the 3P band contained 273 but not 302.
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