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Myachina TA, Butova XA, Simonova RA, Volzhaninov DA, Kochurova AM, Kopylova GV, Shchepkin DV, Khokhlova AD. The Contractile Function of Ventricular Cardiomyocytes Is More Sensitive to Acute 17β-Estradiol Treatment Compared to Atrial Cardiomyocytes. Cells 2025; 14:561. [PMID: 40277887 PMCID: PMC12026394 DOI: 10.3390/cells14080561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2025] [Revised: 04/03/2025] [Accepted: 04/07/2025] [Indexed: 04/26/2025] Open
Abstract
17β-estradiol (E2) is the most active metabolite of estrogen with a wide range of physiological action on cardiac muscle. Previous studies have reported E2 effects predominantly for the ventricles, while the E2 impact on the atria has been less examined. In this study, we focused on the direct E2 effects on atrial and ventricular contractility at the cellular and molecular levels. Single atrial and ventricular cardiomyocytes (CM) from adult (24 weeks-old) female Wistar rats were incubated with 10 nM E2 for 15 min. Sarcomere length and cytosolic [Ca2+]i transients were measured in mechanically non-loaded CM, and the tension-length relationship was studied in CM mechanically loaded by carbon fibers. The actin-myosin interaction and sarcomeric protein phosphorylation were analyzed using an in vitro motility assay and gel electrophoresis with Pro-Q Diamond phosphoprotein stain. E2 had chamber-specific effects on the contractile function of CM with a pronounced influence on ventricular CM. The characteristics of [Ca2+]i transients did not change in both atrial and ventricular CM. However, in ventricular CM, E2 reduced the amplitude and maximum velocity of sarcomere shortening and decreased the slope of the passive tension-length relationship that was associated with increased TnI and cMyBP-C phosphorylation. E2 treatment accelerated the cross-bridge cycle of both atrial and ventricular myosin that was associated with increased phosphorylation of the myosin essential light chain. This study shows that E2 impairs the mechanical function of the ventricular myocardium while atrial contractility remains mostly preserved. Hormonal replacement therapy (HRT) with estrogen is by far the most effective therapy for treating climacteric symptoms experienced during menopause. Here we found a chamber specificity of myocardial contractile function to E2 that should be taken into account for the potential side effects of HRT.
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Affiliation(s)
- Tatiana A. Myachina
- Institute of Immunology and Physiology UrB RAS, 620049 Yekaterinburg, Russia; (T.A.M.); (R.A.S.); (D.A.V.); (D.V.S.)
| | - Xenia A. Butova
- Institute of Immunology and Physiology UrB RAS, 620049 Yekaterinburg, Russia; (T.A.M.); (R.A.S.); (D.A.V.); (D.V.S.)
| | - Raisa A. Simonova
- Institute of Immunology and Physiology UrB RAS, 620049 Yekaterinburg, Russia; (T.A.M.); (R.A.S.); (D.A.V.); (D.V.S.)
| | - Denis A. Volzhaninov
- Institute of Immunology and Physiology UrB RAS, 620049 Yekaterinburg, Russia; (T.A.M.); (R.A.S.); (D.A.V.); (D.V.S.)
| | - Anastasia M. Kochurova
- Institute of Immunology and Physiology UrB RAS, 620049 Yekaterinburg, Russia; (T.A.M.); (R.A.S.); (D.A.V.); (D.V.S.)
| | - Galina V. Kopylova
- Institute of Immunology and Physiology UrB RAS, 620049 Yekaterinburg, Russia; (T.A.M.); (R.A.S.); (D.A.V.); (D.V.S.)
| | - Daniil V. Shchepkin
- Institute of Immunology and Physiology UrB RAS, 620049 Yekaterinburg, Russia; (T.A.M.); (R.A.S.); (D.A.V.); (D.V.S.)
- Institute of Natural Sciences and Mathematics, Ural Federal University, 620026 Yekaterinburg, Russia
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2
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Yuan S, Kuai Z, Zhao F, Xu D, Wu W. Improving effect of physical exercise on heart failure: Reducing oxidative stress-induced inflammation by restoring Ca 2+ homeostasis. Mol Cell Biochem 2025; 480:2471-2486. [PMID: 39365389 DOI: 10.1007/s11010-024-05124-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2024] [Accepted: 09/20/2024] [Indexed: 10/05/2024]
Abstract
Heart failure (HF) is associated with the occurrence of mitochondrial dysfunction. ATP produced by mitochondria through the tricarboxylic acid cycle is the main source of energy for the heart. Excessive release of Ca2+ from myocardial sarcoplasmic reticulum (SR) in HF leads to excessive Ca2+ entering mitochondria, which leads to mitochondrial dysfunction and REDOX imbalance. Excessive accumulation of ROS leads to mitochondrial structure damage, which cannot produce and provide energy. In addition, the accumulation of a large number of ROS can activate NF-κB, leading to myocardial inflammation. Energy deficit in the myocardium has long been considered to be the main mechanism connecting mitochondrial dysfunction and systolic failure. However, exercise can improve the Ca2+ imbalance in HF and restore the Ca2+ disorder in mitochondria. Similarly, exercise activates mitochondrial dynamics to improve mitochondrial function and reshape intact mitochondrial structure, rebalance mitochondrial REDOX, reduce excessive release of ROS, and rescue cardiomyocyte energy failure in HF. In this review, we summarize recent evidence that exercise can improve Ca2+ homeostasis in the SR and activate mitochondrial dynamics, improve mitochondrial function, and reduce oxidative stress levels in HF patients, thereby reducing chronic inflammation in HF patients. The improvement of mitochondrial dynamics is beneficial for ameliorating metabolic flow bottlenecks, REDOX imbalance, ROS balance, impaired mitochondrial Ca2+ homeostasis, and inflammation. Interpretation of these findings will lead to new approaches to disease mechanisms and treatment.
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Affiliation(s)
- Shunling Yuan
- Provincial University Key Laboratory of Sport and Health Science, School of Physical Education and Sport Sciences, Fujian Normal University, Fuzhou, China
| | - Zhongkai Kuai
- Changsha Hospital of Traditional Chinese Medicine (Changsha Eighth Hospital), Changsha, China
| | - Fei Zhao
- Changsha Hospital of Traditional Chinese Medicine (Changsha Eighth Hospital), Changsha, China.
| | - Diqun Xu
- School of Physical Education, Minnan Normal University, Zhangzhou, China.
| | - Weijia Wu
- Hunan Provincial Key Laboratory of Physical Fitness and Sports Rehabilitation, Hunan Normal University, Changsha, China.
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3
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Sun Z, Lu K, Kamla C, Kameritsch P, Seidel T, Dendorfer A. Synchronous force and Ca 2+ measurements for repeated characterization of excitation-contraction coupling in human myocardium. Commun Biol 2024; 7:220. [PMID: 38388802 PMCID: PMC10884022 DOI: 10.1038/s42003-024-05886-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 02/02/2024] [Indexed: 02/24/2024] Open
Abstract
Dysfunctional Ca2+ signaling affects the myocardial systole and diastole, may trigger arrhythmia and cause transcriptomic and proteomic modifications in heart failure. Thus, synchronous real-time measurement of Ca2+ and force is essential to investigate the relationship between contractility and Ca2+ signaling and the alteration of excitation-contraction coupling (ECC) in human failing myocardium. Here, we present a method for synchronized acquisition of intracellular Ca2+ and contraction force in long-term cultivated slices of human failing myocardium. Synchronous time series of contraction force and intracellular Ca2+ were used to calculate force-calcium loops and to analyze the dynamic alterations of ECC in response to various pacing frequencies, post-pause potentiation, high mechanical preload and pharmacological interventions in human failing myocardium. We provide an approach to simultaneously and repeatedly investigate alterations of contractility and Ca2+ signals in long-term cultured myocardium, which will allow detecting the effects of electrophysiological or pharmacological interventions on human myocardial ECC.
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Affiliation(s)
- Zhengwu Sun
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Kun Lu
- Department of Cardiac Surgery, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
- DZHK (German Center for Cardiovascular Research), Partner site Munich Heart Alliance, Munich, Germany
| | - Christine Kamla
- Department of Cardiac Surgery, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Petra Kameritsch
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Thomas Seidel
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Andreas Dendorfer
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany.
- DZHK (German Center for Cardiovascular Research), Partner site Munich Heart Alliance, Munich, Germany.
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Ananthamohan K, Stelzer JE, Sadayappan S. Hypertrophic cardiomyopathy in MYBPC3 carriers in aging. THE JOURNAL OF CARDIOVASCULAR AGING 2024; 4:9. [PMID: 38406555 PMCID: PMC10883298 DOI: 10.20517/jca.2023.29] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Hypertrophic cardiomyopathy (HCM) is characterized by abnormal thickening of the myocardium, leading to arrhythmias, heart failure, and elevated risk of sudden cardiac death, particularly among the young. This inherited disease is predominantly caused by mutations in sarcomeric genes, among which those in the cardiac myosin binding protein-C3 (MYBPC3) gene are major contributors. HCM associated with MYBPC3 mutations usually presents in the elderly and ranges from asymptomatic to symptomatic forms, affecting numerous cardiac functions and presenting significant health risks with a spectrum of clinical manifestations. Regulation of MYBPC3 expression involves various transcriptional and translational mechanisms, yet the destiny of mutant MYBPC3 mRNA and protein in late-onset HCM remains unclear. Pathogenesis related to MYBPC3 mutations includes nonsense-mediated decay, alternative splicing, and ubiquitin-proteasome system events, leading to allelic imbalance and haploinsufficiency. Aging further exacerbates the severity of HCM in carriers of MYBPC3 mutations. Advancements in high-throughput omics techniques have identified crucial molecular events and regulatory disruptions in cardiomyocytes expressing MYBPC3 variants. This review assesses the pathogenic mechanisms that promote late-onset HCM through the lens of transcriptional, post-transcriptional, and post-translational modulation of MYBPC3, underscoring its significance in HCM across carriers. The review also evaluates the influence of aging on these processes and MYBPC3 levels during HCM pathogenesis in the elderly. While pinpointing targets for novel medical interventions to conserve cardiac function remains challenging, the emergence of personalized omics offers promising avenues for future HCM treatments, particularly for late-onset cases.
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Affiliation(s)
- Kalyani Ananthamohan
- Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Julian E. Stelzer
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH 45267, USA
| | - Sakthivel Sadayappan
- Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cincinnati, OH 45267, USA
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Chaoul V, Hanna R, Hachem P, El Hayek MS, Nour‐Eldine W, Abou‐Khalil P, Abi‐Ramia E, Vandecasteele G, Abi‐Gerges A. Differential changes in cyclic adenosine 3′‐5′ monophosphate (
cAMP
) effectors and major Ca
2+
handling proteins during diabetic cardiomyopathy. J Cell Mol Med 2023; 27:1277-1289. [PMID: 36967707 PMCID: PMC10148055 DOI: 10.1111/jcmm.17733] [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: 11/16/2022] [Revised: 02/23/2023] [Accepted: 03/14/2023] [Indexed: 03/29/2023] Open
Abstract
Diabetic cardiomyopathy (DCM) is associated with differential and time-specific regulation of β-adrenergic receptors and cardiac cyclic nucleotide phosphodiesterases with consequences for total cyclic adenosine 3'-5' monophosphate (cAMP) levels. We aimed to investigate whether these changes are associated with downstream impairments in cAMP and Ca2+ signalling in a type 1 diabetes (T1D)-induced DCM model. T1D was induced in adult male rats by streptozotocin (65 mg/kg) injection. DCM was assessed by cardiac structural and molecular remodelling. We delineated sequential changes affecting the exchange protein (Epac1/2), cAMP-dependent protein kinase A (PKA) and Ca2+ /Calmodulin-dependent kinase II (CaMKII) at 4, 8 and 12 weeks following diabetes, by real-time quantitative PCR and western blot. Expression of Ca2+ ATPase pump (SERCA2a), phospholamban (PLB) and Troponin I (TnI) was also examined. Early upregulation of Epac1 transcripts was noted in diabetic hearts at Week 4, followed by increases in Epac2 mRNA, but not protein levels, at Week 12. Expression of PKA subunits (RI, RIIα and Cα) remained unchanged regardless of the disease stage, whereas CaMKII increased at Week 12 in DCM. Moreover, PLB transcripts were upregulated in diabetic hearts, whereas SERCA2a and TnI gene expression was unchanged irrespective of the disease evolution. PLB phosphorylation at threonine-17 was increased in DCM, whereas phosphorylation of both PLB at serine-16 and TnI at serine-23/24 was unchanged. We show for the first time differential and time-specific regulations in cardiac cAMP effectors and Ca2+ handling proteins, data that may prove useful in proposing new therapeutic approaches in T1D-induced DCM.
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Affiliation(s)
- Victoria Chaoul
- Gilbert and Rose‐Marie Chagoury School of MedicineLebanese American UniversityP.O. Box 36ByblosLebanon
| | - Rita Hanna
- Gilbert and Rose‐Marie Chagoury School of MedicineLebanese American UniversityP.O. Box 36ByblosLebanon
| | - Pia Hachem
- Gilbert and Rose‐Marie Chagoury School of MedicineLebanese American UniversityP.O. Box 36ByblosLebanon
| | - Magali Samia El Hayek
- Signaling and Cardiovascular Pathophysiology, UMR‐S1180Université Paris‐SaclayOrsay91400France
| | - Wared Nour‐Eldine
- Gilbert and Rose‐Marie Chagoury School of MedicineLebanese American UniversityP.O. Box 36ByblosLebanon
| | - Pamela Abou‐Khalil
- Gilbert and Rose‐Marie Chagoury School of MedicineLebanese American UniversityP.O. Box 36ByblosLebanon
| | - Elias Abi‐Ramia
- School of Arts and Sciences, Department of Natural SciencesLebanese American UniversityByblosLebanon
| | - Grégoire Vandecasteele
- Signaling and Cardiovascular Pathophysiology, UMR‐S1180Université Paris‐SaclayOrsay91400France
| | - Aniella Abi‐Gerges
- Gilbert and Rose‐Marie Chagoury School of MedicineLebanese American UniversityP.O. Box 36ByblosLebanon
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Dulce RA, Kanashiro-Takeuchi RM, Takeuchi LM, Salerno AG, Wanschel ACBA, Kulandavelu S, Balkan W, Zuttion MSSR, Cai R, Schally AV, Hare JM. Synthetic growth hormone-releasing hormone agonist ameliorates the myocardial pathophysiology characteristic of heart failure with preserved ejection fraction. Cardiovasc Res 2023; 118:3586-3601. [PMID: 35704032 DOI: 10.1093/cvr/cvac098] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 05/06/2022] [Accepted: 05/25/2022] [Indexed: 02/07/2023] Open
Abstract
AIMS To test the hypothesis that the activation of the growth hormone-releasing hormone (GHRH) receptor signalling pathway within the myocardium both prevents and reverses diastolic dysfunction and pathophysiologic features consistent with heart failure with preserved ejection fraction (HFpEF). Impaired myocardial relaxation, fibrosis, and ventricular stiffness, among other multi-organ morbidities, characterize the phenotype underlying the HFpEF syndrome. Despite the rapidly increasing prevalence of HFpEF, few effective therapies have emerged. Synthetic agonists of the GHRH receptors reduce myocardial fibrosis, cardiomyocyte hypertrophy, and improve performance in animal models of ischaemic cardiomyopathy, independently of the growth hormone axis. METHODS AND RESULTS CD1 mice received 4- or 8-week continuous infusion of angiotensin-II (Ang-II) to generate a phenotype with several features consistent with HFpEF. Mice were administered either vehicle or a potent synthetic agonist of GHRH, MR-356 for 4-weeks beginning concurrently or 4-weeks following the initiation of Ang-II infusion. Ang-II-treated animals exhibited diastolic dysfunction, ventricular hypertrophy, interstitial fibrosis, and normal ejection fraction. Cardiomyocytes isolated from these animals exhibited incomplete relaxation, depressed contractile responses, altered myofibrillar protein phosphorylation, and disturbed calcium handling mechanisms (ex vivo). MR-356 both prevented and reversed the development of the pathological phenotype in vivo and ex vivo. Activation of the GHRH receptors increased cAMP and cGMP in cardiomyocytes isolated from control animals but only cAMP in cardiac fibroblasts, suggesting that GHRH-A exert differential effects on cardiomyocytes and fibroblasts. CONCLUSION These findings indicate that the GHRH receptor signalling pathway(s) represents a new molecular target to counteract dysfunctional cardiomyocyte relaxation by targeting myofilament phosphorylation and fibrosis. Accordingly, activation of GHRH receptors with potent, synthetic GHRH agonists may provide a novel therapeutic approach to management of the myocardial alterations associated with the HFpEF syndrome.
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Affiliation(s)
- Raul A Dulce
- Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, 1501 N.W. 10th Avenue, Room 908, Miami, FL 33136, USA
| | - Rosemeire M Kanashiro-Takeuchi
- Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, 1501 N.W. 10th Avenue, Room 908, Miami, FL 33136, USA.,Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Lauro M Takeuchi
- Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, 1501 N.W. 10th Avenue, Room 908, Miami, FL 33136, USA
| | - Alessandro G Salerno
- Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, 1501 N.W. 10th Avenue, Room 908, Miami, FL 33136, USA
| | - Amarylis C B A Wanschel
- Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, 1501 N.W. 10th Avenue, Room 908, Miami, FL 33136, USA
| | - Shathiyah Kulandavelu
- Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, 1501 N.W. 10th Avenue, Room 908, Miami, FL 33136, USA.,Department of Pediatrics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Wayne Balkan
- Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, 1501 N.W. 10th Avenue, Room 908, Miami, FL 33136, USA.,Department of Medicine, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Marilia S S R Zuttion
- Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, 1501 N.W. 10th Avenue, Room 908, Miami, FL 33136, USA
| | - Renzhi Cai
- Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center, FL 33125, USA
| | - Andrew V Schally
- Department of Medicine, University of Miami Miller School of Medicine, Miami, FL 33136, USA.,Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center, FL 33125, USA.,Division of Hematology/Oncology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Joshua M Hare
- Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, 1501 N.W. 10th Avenue, Room 908, Miami, FL 33136, USA.,Department of Medicine, University of Miami Miller School of Medicine, Miami, FL 33136, USA
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7
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Sun B, Kekenes-Huskey PM. Myofilament-associated proteins with intrinsic disorder (MAPIDs) and their resolution by computational modeling. Q Rev Biophys 2023; 56:e2. [PMID: 36628457 PMCID: PMC11070111 DOI: 10.1017/s003358352300001x] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The cardiac sarcomere is a cellular structure in the heart that enables muscle cells to contract. Dozens of proteins belong to the cardiac sarcomere, which work in tandem to generate force and adapt to demands on cardiac output. Intriguingly, the majority of these proteins have significant intrinsic disorder that contributes to their functions, yet the biophysics of these intrinsically disordered regions (IDRs) have been characterized in limited detail. In this review, we first enumerate these myofilament-associated proteins with intrinsic disorder (MAPIDs) and recent biophysical studies to characterize their IDRs. We secondly summarize the biophysics governing IDR properties and the state-of-the-art in computational tools toward MAPID identification and characterization of their conformation ensembles. We conclude with an overview of future computational approaches toward broadening the understanding of intrinsic disorder in the cardiac sarcomere.
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Affiliation(s)
- Bin Sun
- Research Center for Pharmacoinformatics (The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Department of Medicinal Chemistry and Natural Medicine Chemistry, College of Pharmacy, Harbin Medical University, Harbin 150081, China
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Glaser D, Heinick A, Herting JR, Massing F, Müller FU, Pauls P, Rozhdestvensky TS, Schulte JS, Seidl MD, Skryabin BV, Stümpel F, Kirchhefer U. Impaired myocellular Ca 2+ cycling in protein phosphatase PP2A-B56α knockout mice is normalized by β-adrenergic stimulation. J Biol Chem 2022; 298:102362. [PMID: 35963431 PMCID: PMC9478386 DOI: 10.1016/j.jbc.2022.102362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 07/25/2022] [Accepted: 07/26/2022] [Indexed: 11/24/2022] Open
Abstract
The activity of protein phosphatase 2A (PP2A) is determined by the expression and localization of the regulatory B-subunits. PP2A-B56α is the dominant isoform of the B′-family in the heart. Its role in regulating the cardiac response to β-adrenergic stimulation is not yet fully understood. We therefore generated mice deficient in B56α to test the functional cardiac effects in response to catecholamine administration versus corresponding WT mice. We found the decrease in basal PP2A activity in hearts of KO mice was accompanied by a counter-regulatory increase in the expression of B′ subunits (β and γ) and higher phosphorylation of sarcoplasmic reticulum Ca2+ regulatory and myofilament proteins. The higher phosphorylation levels were associated with enhanced intraventricular pressure and relaxation in catheterized KO mice. In contrast, at the cellular level, we detected depressed Ca2+ transient and sarcomere shortening parameters in KO mice at basal conditions. Consistently, the peak amplitude of the L-type Ca2+ current was reduced and the inactivation kinetics of ICaL were prolonged in KO cardiomyocytes. However, we show β-adrenergic stimulation resulted in a comparable peak amplitude of Ca2+ transients and myocellular contraction between KO and WT cardiomyocytes. Therefore, we propose higher isoprenaline-induced Ca2+ spark frequencies might facilitate the normalized Ca2+ signaling in KO cardiomyocytes. In addition, the application of isoprenaline was associated with unchanged L-type Ca2+ current parameters between both groups. Our data suggest an important influence of PP2A-B56α on the regulation of Ca2+ signaling and contractility in response to β-adrenergic stimulation in the myocardium.
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Affiliation(s)
- Dennis Glaser
- Institute of Pharmacology and Toxicology, University of Münster, Münster, Germany
| | - Alexander Heinick
- Institute of Pharmacology and Toxicology, University of Münster, Münster, Germany
| | - Julius R Herting
- Institute of Pharmacology and Toxicology, University of Münster, Münster, Germany
| | - Fabian Massing
- Institute of Pharmacology and Toxicology, University of Münster, Münster, Germany
| | - Frank U Müller
- Institute of Pharmacology and Toxicology, University of Münster, Münster, Germany
| | - Paul Pauls
- Institute of Pharmacology and Toxicology, University of Münster, Münster, Germany
| | - Timofey S Rozhdestvensky
- Department of Medicine, Core Facility Transgenic Animal and Genetic Engineering Models (TRAM), University of Münster, Münster, Germany
| | - Jan S Schulte
- Institute of Pharmacology and Toxicology, University of Münster, Münster, Germany
| | - Matthias D Seidl
- Institute of Pharmacology and Toxicology, University of Münster, Münster, Germany
| | - Boris V Skryabin
- Department of Medicine, Core Facility Transgenic Animal and Genetic Engineering Models (TRAM), University of Münster, Münster, Germany
| | - Frank Stümpel
- Institute of Pharmacology and Toxicology, University of Münster, Münster, Germany
| | - Uwe Kirchhefer
- Institute of Pharmacology and Toxicology, University of Münster, Münster, Germany.
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9
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Ion Channel Impairment and Myofilament Ca 2+ Sensitization: Two Parallel Mechanisms Underlying Arrhythmogenesis in Hypertrophic Cardiomyopathy. Cells 2021; 10:cells10102789. [PMID: 34685769 PMCID: PMC8534456 DOI: 10.3390/cells10102789] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Revised: 10/07/2021] [Accepted: 10/13/2021] [Indexed: 11/17/2022] Open
Abstract
Life-threatening ventricular arrhythmias are the main clinical burden in patients with hypertrophic cardiomyopathy (HCM), and frequently occur in young patients with mild structural disease. While massive hypertrophy, fibrosis and microvascular ischemia are the main mechanisms underlying sustained reentry-based ventricular arrhythmias in advanced HCM, cardiomyocyte-based functional arrhythmogenic mechanisms are likely prevalent at earlier stages of the disease. In this review, we will describe studies conducted in human surgical samples from HCM patients, transgenic animal models and human cultured cell lines derived from induced pluripotent stem cells. Current pieces of evidence concur to attribute the increased risk of ventricular arrhythmias in early HCM to different cellular mechanisms. The increase of late sodium current and L-type calcium current is an early observation in HCM, which follows post-translation channel modifications and increases the occurrence of early and delayed afterdepolarizations. Increased myofilament Ca2+ sensitivity, commonly observed in HCM, may promote afterdepolarizations and reentry arrhythmias with direct mechanisms. Decrease of K+-currents due to transcriptional regulation occurs in the advanced disease and contributes to reducing the repolarization-reserve and increasing the early afterdepolarizations (EADs). The presented evidence supports the idea that patients with early-stage HCM should be considered and managed as subjects with an acquired channelopathy rather than with a structural cardiac disease.
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10
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Miura M, Hasegawa T, Matsumoto A, Nishiyama M, Someya Y, Satoh W, Kumasaka K, Shindoh C, Sato H. Effect of transient elevation of glucose on contractile properties in non-diabetic rat cardiac muscle. Heart Vessels 2020; 36:568-576. [PMID: 33226494 DOI: 10.1007/s00380-020-01726-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 11/06/2020] [Indexed: 10/22/2022]
Abstract
In non-diabetic patients with severe disease, such as acute myocardial infarction or acute heart failure, admission blood glucose level is associated with their short-term and long-term mortality. We examined whether transient elevation of glucose affects contractile properties in non-diabetic hearts. Force, intracellular Ca2+ ([Ca2+]i), and sarcomere length were measured in trabeculae from rat hearts. To assess contractile properties, maximum velocity of contraction (Max dF/dt) and minimum velocity of relaxation (Min dF/dt) were calculated. The ratio of phosphorylated troponin I (P-TnI) to troponin I (TnI) was measured. One hour after elevation of glucose from 150 to 400 mg/dL, developed force, Max dF/dt, and Min dF/dt were reduced without changes in [Ca2+]i transients at 2.5 Hz stimulation and 2.0 mM [Ca2+]o, while developed force and [Ca2+]i transients showed no changes at 0.5 Hz stimulation and 0.7 mM [Ca2+]o. In the presence of 1 μM KN-93, a Ca2+/calmodulin-dependent protein kinaseII (CaMKII) inhibitor, or 50 μM diazo-5-oxonorleucine, a L-glutamine-D-fructose-6-phosphate amidotransferase inhibitor, the reduction of contractile properties after elevation of glucose was suppressed. Furthermore, 1 h after elevation of glucose to 400 mg/dL at 2.0 mM [Ca2+]o, the ratio of P-TnI to TnI was increased. These results suggest that in non-diabetic hearts under higher Ca2+-load, transient elevation of glucose for 1 h reduces contractile properties probably by activating CaMKII through O-GlcNAcylation. Thus, in the patients with severe disease, transient elevation of blood glucose, such as due to stress, may worsen cardiac function and thereby affect their mortality without known diabetes.
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Affiliation(s)
- Masahito Miura
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan.
| | - Taiki Hasegawa
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Ayana Matsumoto
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Masami Nishiyama
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Yuka Someya
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Wakako Satoh
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Kazunori Kumasaka
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Chiyohiko Shindoh
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Haruka Sato
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
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11
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Miura M, Handoh T, Taguchi Y, Hasegawa T, Takahashi Y, Morita N, Matsumoto A, Shindoh C, Sato H. Transient Elevation of Glucose Increases Arrhythmia Susceptibility in Non-Diabetic Rat Trabeculae With Non-Uniform Contraction. Circ J 2020; 84:551-558. [PMID: 32092718 DOI: 10.1253/circj.cj-19-0715] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND In non-diabetic patients with acute coronary syndrome, stress hyperglycemia occasionally occurs and is related to their mortality. Whether transient elevation of glucose affects arrhythmia susceptibility in non-diabetic hearts with non-uniform contraction was examined. METHODS AND RESULTS Force, intracellular Ca2+([Ca2+]i), and membrane potential were measured in trabeculae from rat hearts. Non-uniform contraction was produced by a jet of paralyzing solution. Ca2+waves and arrhythmias were induced by electrical stimulation (2.0 mmol/L [Ca2+]o). The activity of Ca2+/calmodulin-dependent protein kinaseII (CaMKII) was measured. An elevation of glucose from 150 to 400 mg/dL increased the velocity of Ca2+waves and the number of spontaneous action potentials triggered by electrical stimulation. Besides, the elevation of glucose increased the CaMKII activity. In the presence of 1 μmol/L KN-93, the elevation of glucose did not increase the velocity of Ca2+waves and the number of triggered action potentials. In addition, in the presence of 1 μmol/L autocamtide-2 related inhibitory peptide or 50 μmol/L diazo-5-oxonorleucine, the elevation of glucose did not increase the number of triggered action potentials. Furthermore, the elevation of glucose by adding L-glucose did not increase their number. CONCLUSIONS In non-diabetic hearts with non-uniform contraction, transient elevation of glucose increases the velocity of Ca2+waves by activating CaMKII,probably through glycosylation with O-linked β-N-acetylglucosamine, thereby increasing arrhythmia susceptibility.
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Affiliation(s)
- Masahito Miura
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Tetsuya Handoh
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Yuhto Taguchi
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Taiki Hasegawa
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Yui Takahashi
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Natsuki Morita
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Ayana Matsumoto
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Chiyohiko Shindoh
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Haruka Sato
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
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12
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Rosas PC, Warren CM, Creed HA, Trzeciakowski JP, Solaro RJ, Tong CW. Cardiac Myosin Binding Protein-C Phosphorylation Mitigates Age-Related Cardiac Dysfunction: Hope for Better Aging? JACC Basic Transl Sci 2019; 4:817-830. [PMID: 31998850 PMCID: PMC6978553 DOI: 10.1016/j.jacbts.2019.06.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Revised: 06/14/2019] [Accepted: 06/19/2019] [Indexed: 12/29/2022]
Abstract
Cardiac myosin binding protein-C (cMyBP-C) phosphorylation prevents aging-related cardiac dysfunction. We tested this hypothesis by aging genetic mouse models of hypophosphorylated cMyBP-C, wild-type equivalent, and phosphorylated-mimetic cMyBP-C for 18 to 20 months. Phosphorylated-mimetic cMyBP-C mice exhibited better survival, better preservation of systolic and diastolic functions, and unchanging wall thickness. Wild-type equivalent mice showed decreasing cMyBP-C phosphorylation along with worsening cardiac function and hypertrophy approaching those found in hypophosphorylated cMyBP-C mice. Intact papillary muscle experiments suggested that cMyBP-C phosphorylation increased cross-bridge detachment rates as the underlying mechanism. Thus, phosphorylating cMyBP-C is a novel mechanism with potential to treat aging-related cardiac dysfunction.
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Key Words
- 3SA, mutated 3 serines to 3 alanines to mimic hypophosphorylated cardiac myosin binding protein-C (S273A, S282A, and S302A)
- 3SD, mutated 3 serines to 3 aspartic acids to mimic phosphorylated cMyBP-C (S273D, S282D, and S302D)
- ANOVA, analysis of variance
- EF, ejection fraction
- HF, heart failure
- HFpEF, heart failure with preserved ejection fraction
- HOP, hydroxyproline
- LV, left ventricular
- aging
- cMyBP-C, cardiac myosin binding protein-C
- cTnI, cardiac troponin I
- cardiac myosin binding protein-C
- dyastolic dysfunction
- heart failure
- phosphorylation
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Affiliation(s)
- Paola C. Rosas
- Department of Physiology and Biophysics, Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Chad M. Warren
- Department of Physiology and Biophysics, Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Heidi A. Creed
- Department of Medical Physiology, Texas A and M University Health Science Center, College of Medicine, College Station, Texas
| | - Jerome P. Trzeciakowski
- Department of Medical Physiology, Texas A and M University Health Science Center, College of Medicine, College Station, Texas
| | - R. John Solaro
- Department of Physiology and Biophysics, Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Carl W. Tong
- Department of Medical Physiology, Texas A and M University Health Science Center, College of Medicine, College Station, Texas
- Catholic Health Initiatives-St. Joseph Health, Bryan, Texas
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13
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Is there an effect of ischemic conditioning on myocardial contractile function following acute myocardial ischemia/reperfusion injury? Biochim Biophys Acta Mol Basis Dis 2019; 1865:822-830. [PMID: 30660684 DOI: 10.1016/j.bbadis.2018.12.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 12/18/2018] [Accepted: 12/19/2018] [Indexed: 10/27/2022]
Abstract
Ischemic conditioning induces cardioprotection; the final infarct size following a myocardial ischemic event is reduced. However, whether ischemic conditioning has long-term beneficial effects on myocardial contractile function following such an ischemic event needs further elucidation. To date, ex vivo studies have shown that ischemic conditioning improves the contractile recovery of isolated ventricular papillary muscle or atrial trabeculae following simulated ischemia. However, in vivo animal studies and studies in patients undergoing elective cardiac surgery show conflicting results. At the subcellular level, it is known that ischemic conditioning improved energy metabolism, preserved mitochondrial respiration, ATP production, and Ca2+ homeostasis in isolated mitochondria from the myocardium. Ischemic conditioning also presents with post-translational modifications of proteins in the contractile machinery of the myocardium. The beneficial effects on myocardial contractile function need further elucidation. This article is part of a Special Issue entitled: The power of metabolism: Linking energy supply and demand to contractile function edited by Torsten Doenst, Michael Schwarzer and Christine Des Rosiers.
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14
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Valdés Á, Treuer AV, Barrios G, Ponce N, Fuentealba R, Dulce RA, González DR. NOX Inhibition Improves β-Adrenergic Stimulated Contractility and Intracellular Calcium Handling in the Aged Rat Heart. Int J Mol Sci 2018; 19:ijms19082404. [PMID: 30111689 PMCID: PMC6121436 DOI: 10.3390/ijms19082404] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 07/28/2018] [Accepted: 08/01/2018] [Indexed: 12/26/2022] Open
Abstract
Cardiac aging is characterized by alterations in contractility and intracellular calcium ([Ca2+]i) homeostasis. It has been suggested that oxidative stress may be involved in this process. We and others have reported that in cardiomyopathies the NADPH oxidase (NOX)-derived superoxide is increased, with a negative impact on [Ca2+]i and contractility. We tested the hypothesis that in the aged heart, [Ca2+]i handling and contractility are disturbed by NOX-derived superoxide. For this we used adults (≈5 month-old) and aged (20–24 month-old) rats. Contractility was evaluated in isolated hearts, challenged with isoproterenol. To assess [Ca2+]i, isolated cardiac myocytes were field-stimulated and [Ca2+]i was monitored with fura-2. Cardiac concentration-response to isoproterenol was depressed in aged compared to adults hearts (p < 0.005), but was restored by NOX inhibitors apocynin and VAS2870. In isolated cardiomyocytes, apocynin increased the amplitude of [Ca2+]i in aged myocytes (p < 0.05). Time-50 [Ca2+]i decay was increased in aged myocytes (p < 0.05) and reduced towards normal by NOX inhibition. In addition, we found that myofilaments Ca2+ sensitivity was reduced in aged myocytes (p < 0.05), and was further reduced by apocynin. NOX2 expression along with NADPH oxidase activity was increased in aged hearts. Phospholamban phosphorylation (Ser16/Thr17) after isoproterenol treatment was reduced in aged hearts compared to adults and was restored by apocynin treatment (p < 0.05). In conclusion, β-adrenergic-induced contractility was depressed in aged hearts, and NOX inhibition restored back to normal. Moreover, altered Ca2+ handling in aged myocytes was also improved by NOX inhibition. These results suggest a NOX-dependent effect in aged myocytes at the level of Ca2+ handling proteins and myofilaments.
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Affiliation(s)
- Álvaro Valdés
- Departamento de Ciencias Básicas Biomédicas, Facultad Ciencias de la Salud, Universidad de Talca, Talca 3460000, Chile.
| | - Adriana V Treuer
- Departamento de Ciencias Básicas Biomédicas, Facultad Ciencias de la Salud, Universidad de Talca, Talca 3460000, Chile.
| | - Guillermo Barrios
- Departamento de Ciencias Básicas Biomédicas, Facultad Ciencias de la Salud, Universidad de Talca, Talca 3460000, Chile.
| | - Nikol Ponce
- Departamento de Ciencias Básicas Biomédicas, Facultad Ciencias de la Salud, Universidad de Talca, Talca 3460000, Chile.
| | - Roberto Fuentealba
- Departamento de Ciencias Básicas Biomédicas, Facultad Ciencias de la Salud, Universidad de Talca, Talca 3460000, Chile.
| | - Raul A Dulce
- Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, Miami, FL 33136, USA.
| | - Daniel R González
- Departamento de Ciencias Básicas Biomédicas, Facultad Ciencias de la Salud, Universidad de Talca, Talca 3460000, Chile.
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15
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Calcium-Dependent Interaction Occurs between Slow Skeletal Myosin Binding Protein C and Calmodulin. MAGNETOCHEMISTRY 2017. [DOI: 10.3390/magnetochemistry4010001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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16
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Aboelkassem Y, Campbell SG. Acute Optogenetic Modulation of Cardiac Twitch Dynamics Explored Through Modeling. J Biomech Eng 2017; 138:2552973. [PMID: 27618140 DOI: 10.1115/1.4034655] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Indexed: 11/08/2022]
Abstract
Optogenetic approaches allow cellular membrane potentials to be perturbed by light. When applied to muscle cells, mechanical events can be controlled through a process that could be termed "optomechanics." Besides functioning as an optical on/off switch, we hypothesized that optomechanical control could include the ability to manipulate the strength and duration of contraction events. To explore this possibility, we constructed an electromechanical model of the human ventricular cardiomyocyte while adding a representation of channelrhodopsin-2 (ChR2), a light-activated channel commonly used in optogenetics. Two hybrid stimulus protocols were developed that combined light-based stimuli with traditional electrical current (all-or-none) excitation. The first protocol involved delivery of a subthreshold optical stimulus followed 50-90 ms later by an electrical stimulus. The result was a graded inhibition of peak cellular twitch force in concert with a prolongation of the intracellular Ca2+ transient. The second protocol was comprised of an electrical stimulus followed by a long light pulse (250-350 ms) that acted to prolong the cardiac action potential (AP). This created a pulse duration-dependent prolongation of the intracellular Ca2+ transient that in turn altered the rate of muscle relaxation without changing peak twitch force. These results illustrate the feasibility of acute, optomechanical manipulation of cardiomyocyte contraction and suggest that this approach could be used to probe the dynamic behavior of the cardiac sarcomere without altering its intrinsic properties. Other experimentally meaningful stimulus protocols could be designed by making use of the optomechanical cardiomyocyte model presented here.
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Affiliation(s)
- Yasser Aboelkassem
- Institute for Computational Medicine, Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21218 e-mail:
| | - Stuart G Campbell
- Department of Biomedical Engineering, Yale University, New Haven, CT 06511 e-mail:
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17
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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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18
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Kong LH, Gu XM, Wu F, Jin ZX, Zhou JJ. CaMKII inhibition mitigates ischemia/reperfusion-elicited calpain activation and the damage to membrane skeleton proteins in isolated rat hearts. Biochem Biophys Res Commun 2017; 491:687-692. [PMID: 28754591 DOI: 10.1016/j.bbrc.2017.07.128] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 07/22/2017] [Indexed: 01/03/2023]
Abstract
Ca2+/calmodulin-dependent protein kinase II (CaMKII) has been implicated in myocardial ischemia/reperfusion (IR) injury. The aim of this study was to determine the effect of CaMKII on the damage to membrane skeleton proteins, which is an important cause of IR injury. Isolated rat hearts were subjected to 45-min global ischemia/2-h reperfusion. Both KN-62 and KN-93 were used to inhibit CaMKII. Compared with controls, the hearts in the IR group exhibited remarkable myocardial injury area, LDH release, cell apoptosis and contractile dysfunction, along with an increase in the phosphorylation of CaMKII and its substrate phospholamban. Treatment with either KN-62 or KN-93 mitigated both the heart injury and the phosphorylation of CaMKII and phospholamban. The analysis of cell skeleton proteins revealed that IR injury resulted in an increase in the 150-kDa fragments resulting from the degradation of α-fodrin and dystrophin translocating from the sarcolemmal membrane to the cytosol and a decrease in the 220-kDa isoform of ankyrin-B. As expected, Evans blue dye staining showed an increase in membrane permeability or membrane rupture in the IR group. All of these alterations were alleviated by treatment with either KN-62 or KN-93. In addition, both KN-62 and KN-93 blocked the activity and membrane recruitment of calpain, a key protease responsible for destroying cell skeleton proteins during IR injury. In conclusion, our data provide evidence that damage to membrane skeleton proteins via calpain is a destructive downstream event of CaMKII activation in the setting of myocardial IR injury.
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Affiliation(s)
- Ling-Heng Kong
- Department of Physiology, Fourth Military Medical University, Xi'an, China; Institute of Basic Medical Science, Xi'an Medical College, Xi'an, China
| | - Xiao-Ming Gu
- Department of Physiology, Fourth Military Medical University, Xi'an, China
| | - Feng Wu
- Department of Cardiology, Xi'an, China
| | - Zhen-Xiao Jin
- Department of Cardiovascular Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Jing-Jun Zhou
- Department of Physiology, Fourth Military Medical University, Xi'an, China.
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19
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Wei B, Wei H, Jin JP. Dysferlin deficiency blunts β-adrenergic-dependent lusitropic function of mouse heart. J Physiol 2015; 593:5127-44. [PMID: 26415898 DOI: 10.1113/jp271225] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 09/22/2015] [Indexed: 11/08/2022] Open
Abstract
Dysferlin is a cell membrane bound protein with a role in the repair of skeletal and cardiac muscle cells. Deficiency of dysferlin leads to limb-girdle muscular dystrophy 2B (LGMD2B) and Miyoshi myopathy. In cardiac muscle, dysferlin is located at the intercalated disc and transverse tubule membranes. Loss of dysferlin causes death of cardiomyocytes, notably in ageing hearts, leading to dilated cardiomyopathy and heart failure in LGM2B patients. To understand the primary pathogenesis and pathophysiology of dysferlin cardiomyopathy, we studied cardiac phenotypes of young adult dysferlin knockout mice and found early myocardial hypertrophy with largely compensated baseline cardiac function. Cardiomyocytes isolated from dysferlin-deficient mice showed normal shortening and re-lengthening velocities in the absence of external load with normal peak systolic Ca(2+) but slower Ca(2+) re-sequestration than wild-type controls. The effects of isoproterenol on relaxation velocity, left ventricular systolic pressure and stroke volume were blunted in dysferlin-deficient mouse hearts compared with that in wild-type hearts. Young dysferlin-deficient mouse hearts expressed normal isoforms of myofilament proteins whereas the phosphorylation of ventricular myosin light chain 2 was significantly increased, implying a molecular response to the impaired lusitropic function. These early phenotypes of diastolic cardiac dysfunction and blunted lusitropic response of cardiac muscle to β-adrenergic stimulation indicate a novel pathogenic mechanism of dysferlin cardiomyopathy.
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Affiliation(s)
- Bin Wei
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Hongguang Wei
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - J-P Jin
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, USA
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20
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Guilbert A, Lim HJ, Cheng J, Wang Y. CaMKII-dependent myofilament Ca2+ desensitization contributes to the frequency-dependent acceleration of relaxation. Cell Calcium 2015; 58:489-99. [PMID: 26297240 DOI: 10.1016/j.ceca.2015.08.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 07/06/2015] [Accepted: 08/04/2015] [Indexed: 11/15/2022]
Abstract
BACKGROUND Previous studies suggest that CaMKII activity is required for frequency-dependent acceleration of relaxation (FDAR) in ventricular myocytes. We propose that the underlying mechanism involves CaMKII-dependent regulation of myofilament Ca(2+) sensitivity. METHODS AND RESULTS Cardiac function was measured in mice using murine echo machine. [Ca(2+)]i and sarcomere length were measured by IonOptix Ca(2+) image system. Increasing pacing rate from 0.5 to 4 Hz in left ventricular myocytes induced frequency-dependent myofilament Ca(2+) desensitization (FDMCD) and FDAR. Acute inhibition of PKA or PKC had no effect, whereas CaMKII inhibition abolished both FDMCD and FDAR. Co-immunoprecipitation of CaMKII and troponin I (TnI) has been detected and CaMKII inhibition significantly reduced serine residue phosphorylation of TnI. Finally, chronic inhibition of CaMKII in vivo reduced TnI phosphorylation and abolished both FDAR and FDMCD, leading to impaired diastolic function. CONCLUSIONS Our results suggest that CaMKII-dependent TnI phosphorylation is involved in FDMCD and the consequent FDAR and that CaMKII inhibition removes this mechanism and thus induces diastolic dysfunction.
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Affiliation(s)
| | - Hyun Joung Lim
- Department of Pediatrics, Emory University, Atlanta, USA
| | - Jun Cheng
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan University, China; Department of Pediatrics, Emory University, Atlanta, USA
| | - Yanggan Wang
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan University, China; Department of Pediatrics, Emory University, Atlanta, USA.
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21
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Waddingham MT, Edgley AJ, Tsuchimochi H, Kelly DJ, Shirai M, Pearson JT. Contractile apparatus dysfunction early in the pathophysiology of diabetic cardiomyopathy. World J Diabetes 2015; 6:943-960. [PMID: 26185602 PMCID: PMC4499528 DOI: 10.4239/wjd.v6.i7.943] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 12/30/2014] [Accepted: 03/09/2015] [Indexed: 02/05/2023] Open
Abstract
Diabetes mellitus significantly increases the risk of cardiovascular disease and heart failure in patients. Independent of hypertension and coronary artery disease, diabetes is associated with a specific cardiomyopathy, known as diabetic cardiomyopathy (DCM). Four decades of research in experimental animal models and advances in clinical imaging techniques suggest that DCM is a progressive disease, beginning early after the onset of type 1 and type 2 diabetes, ahead of left ventricular remodeling and overt diastolic dysfunction. Although the molecular pathogenesis of early DCM still remains largely unclear, activation of protein kinase C appears to be central in driving the oxidative stress dependent and independent pathways in the development of contractile dysfunction. Multiple subcellular alterations to the cardiomyocyte are now being highlighted as critical events in the early changes to the rate of force development, relaxation and stability under pathophysiological stresses. These changes include perturbed calcium handling, suppressed activity of aerobic energy producing enzymes, altered transcriptional and posttranslational modification of membrane and sarcomeric cytoskeletal proteins, reduced actin-myosin cross-bridge cycling and dynamics, and changed myofilament calcium sensitivity. In this review, we will present and discuss novel aspects of the molecular pathogenesis of early DCM, with a special focus on the sarcomeric contractile apparatus.
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22
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Dissociation of Calcium Transients and Force Development following a Change in Stimulation Frequency in Isolated Rabbit Myocardium. BIOMED RESEARCH INTERNATIONAL 2015; 2015:468548. [PMID: 25961020 PMCID: PMC4413957 DOI: 10.1155/2015/468548] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 08/01/2014] [Accepted: 08/19/2014] [Indexed: 01/02/2023]
Abstract
As the heart transitions from one exercise intensity to another, changes in cardiac output occur, which are modulated by alterations in force development and calcium handling. Although the steady-state force-calcium relationship at various heart rates is well investigated, regulation of these processes during transitions in heart rate is poorly understood. In isolated right ventricular muscle preparations from the rabbit, we investigated the beat-to-beat alterations in force and calcium during the transition from one stimulation frequency to another, using contractile assessments and confocal microscopy. We show that a change in steady-state conditions occurs in multiple phases: a rapid phase, which is characterized by a fast change in force production mirrored by a change in calcium transient amplitude, and a slow phase, which follows the rapid phase and occurs as the muscle proceeds to stabilize at the new frequency. This second/late phase is characterized by a quantitative dissociation between the calcium transient amplitude and developed force. Twitch timing kinetics, such as time to peak tension and 50% relaxation rate, reached steady-state well before force development and calcium transient amplitude. The dynamic relationship between force and calcium upon a switch in stimulation frequency unveils the dynamic involvement of myofilament-based properties in frequency-dependent activation.
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23
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Rosas PC, Liu Y, Abdalla MI, Thomas CM, Kidwell DT, Dusio GF, Mukhopadhyay D, Kumar R, Baker KM, Mitchell BM, Powers PA, Fitzsimons DP, Patel BG, Warren CM, Solaro RJ, Moss RL, Tong CW. Phosphorylation of cardiac Myosin-binding protein-C is a critical mediator of diastolic function. Circ Heart Fail 2015; 8:582-94. [PMID: 25740839 DOI: 10.1161/circheartfailure.114.001550] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 02/24/2015] [Indexed: 01/06/2023]
Abstract
BACKGROUND Heart failure (HF) with preserved ejection fraction (HFpEF) accounts for ≈50% of all cases of HF and currently has no effective treatment. Diastolic dysfunction underlies HFpEF; therefore, elucidation of the mechanisms that mediate relaxation can provide new potential targets for treatment. Cardiac myosin-binding protein-C (cMyBP-C) is a thick filament protein that modulates cross-bridge cycling rates via alterations in its phosphorylation status. Thus, we hypothesize that phosphorylated cMyBP-C accelerates the rate of cross-bridge detachment, thereby enhancing relaxation to mediate diastolic function. METHODS AND RESULTS We compared mouse models expressing phosphorylation-deficient cMyBP-C(S273A/S282A/S302A)-cMyBP-C(t3SA), phosphomimetic cMyBP-C(S273D/S282D/S302D)-cMyBP-C(t3SD), and wild-type-control cMyBP-C(tWT) to elucidate the functional effects of cMyBP-C phosphorylation. Decreased voluntary running distances, increased lung/body weight ratios, and increased brain natriuretic peptide levels in cMyBP-C(t3SA) mice demonstrate that phosphorylation deficiency is associated with signs of HF. Echocardiography (ejection fraction and myocardial relaxation velocity) and pressure/volume measurements (-dP/dtmin, pressure decay time constant τ-Glantz, and passive filling stiffness) show that cMyBP-C phosphorylation enhances myocardial relaxation in cMyBP-C(t3SD) mice, whereas deficient cMyBP-C phosphorylation causes diastolic dysfunction with HFpEF in cMyBP-C(t3SA) mice. Simultaneous force and [Ca(2+)]i measurements on intact papillary muscles show that enhancement of relaxation in cMyBP-C(t3SD) mice and impairment of relaxation in cMyBP-C(t3SA) mice are not because of altered [Ca(2+)]i handling, implicating that altered cross-bridge detachment rates mediate these changes in relaxation rates. CONCLUSIONS cMyBP-C phosphorylation enhances relaxation, whereas deficient phosphorylation causes diastolic dysfunction and phenotypes resembling HFpEF. Thus, cMyBP-C is a potential target for treatment of HFpEF.
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Affiliation(s)
- Paola C Rosas
- From the Department of Medical Physiology (P.C.R., Y.L., M.I.A., B.M.M., C.W.T.) and Division of Molecular Cardiology, Department of Medicine (C.M.T., R.K., K.M.B.), Texas A&M University Health Science Center, College of Medicine, Temple City; Internal Medicine/Division of Cardiology (D.T.K., C.W.T.) and Department of Surgery (G.F.D., D.M.), Baylor Scott & White Health-Central Texas, Temple City; Department of Cell and Regenerative Biology and Biotechnology Center, University of Wisconsin School of Medicine and Public Health, Madison (P.A.P., D.P.F., R.L.M.); and Department of Physiology and Biophysics and Center for Cardiovascular Research, College of Medicine, University of Illinois, Chicago (B.G.P., C.M.W., R.J.S.)
| | - Yang Liu
- From the Department of Medical Physiology (P.C.R., Y.L., M.I.A., B.M.M., C.W.T.) and Division of Molecular Cardiology, Department of Medicine (C.M.T., R.K., K.M.B.), Texas A&M University Health Science Center, College of Medicine, Temple City; Internal Medicine/Division of Cardiology (D.T.K., C.W.T.) and Department of Surgery (G.F.D., D.M.), Baylor Scott & White Health-Central Texas, Temple City; Department of Cell and Regenerative Biology and Biotechnology Center, University of Wisconsin School of Medicine and Public Health, Madison (P.A.P., D.P.F., R.L.M.); and Department of Physiology and Biophysics and Center for Cardiovascular Research, College of Medicine, University of Illinois, Chicago (B.G.P., C.M.W., R.J.S.)
| | - Mohamed I Abdalla
- From the Department of Medical Physiology (P.C.R., Y.L., M.I.A., B.M.M., C.W.T.) and Division of Molecular Cardiology, Department of Medicine (C.M.T., R.K., K.M.B.), Texas A&M University Health Science Center, College of Medicine, Temple City; Internal Medicine/Division of Cardiology (D.T.K., C.W.T.) and Department of Surgery (G.F.D., D.M.), Baylor Scott & White Health-Central Texas, Temple City; Department of Cell and Regenerative Biology and Biotechnology Center, University of Wisconsin School of Medicine and Public Health, Madison (P.A.P., D.P.F., R.L.M.); and Department of Physiology and Biophysics and Center for Cardiovascular Research, College of Medicine, University of Illinois, Chicago (B.G.P., C.M.W., R.J.S.)
| | - Candice M Thomas
- From the Department of Medical Physiology (P.C.R., Y.L., M.I.A., B.M.M., C.W.T.) and Division of Molecular Cardiology, Department of Medicine (C.M.T., R.K., K.M.B.), Texas A&M University Health Science Center, College of Medicine, Temple City; Internal Medicine/Division of Cardiology (D.T.K., C.W.T.) and Department of Surgery (G.F.D., D.M.), Baylor Scott & White Health-Central Texas, Temple City; Department of Cell and Regenerative Biology and Biotechnology Center, University of Wisconsin School of Medicine and Public Health, Madison (P.A.P., D.P.F., R.L.M.); and Department of Physiology and Biophysics and Center for Cardiovascular Research, College of Medicine, University of Illinois, Chicago (B.G.P., C.M.W., R.J.S.)
| | - David T Kidwell
- From the Department of Medical Physiology (P.C.R., Y.L., M.I.A., B.M.M., C.W.T.) and Division of Molecular Cardiology, Department of Medicine (C.M.T., R.K., K.M.B.), Texas A&M University Health Science Center, College of Medicine, Temple City; Internal Medicine/Division of Cardiology (D.T.K., C.W.T.) and Department of Surgery (G.F.D., D.M.), Baylor Scott & White Health-Central Texas, Temple City; Department of Cell and Regenerative Biology and Biotechnology Center, University of Wisconsin School of Medicine and Public Health, Madison (P.A.P., D.P.F., R.L.M.); and Department of Physiology and Biophysics and Center for Cardiovascular Research, College of Medicine, University of Illinois, Chicago (B.G.P., C.M.W., R.J.S.)
| | - Giuseppina F Dusio
- From the Department of Medical Physiology (P.C.R., Y.L., M.I.A., B.M.M., C.W.T.) and Division of Molecular Cardiology, Department of Medicine (C.M.T., R.K., K.M.B.), Texas A&M University Health Science Center, College of Medicine, Temple City; Internal Medicine/Division of Cardiology (D.T.K., C.W.T.) and Department of Surgery (G.F.D., D.M.), Baylor Scott & White Health-Central Texas, Temple City; Department of Cell and Regenerative Biology and Biotechnology Center, University of Wisconsin School of Medicine and Public Health, Madison (P.A.P., D.P.F., R.L.M.); and Department of Physiology and Biophysics and Center for Cardiovascular Research, College of Medicine, University of Illinois, Chicago (B.G.P., C.M.W., R.J.S.)
| | - Dhriti Mukhopadhyay
- From the Department of Medical Physiology (P.C.R., Y.L., M.I.A., B.M.M., C.W.T.) and Division of Molecular Cardiology, Department of Medicine (C.M.T., R.K., K.M.B.), Texas A&M University Health Science Center, College of Medicine, Temple City; Internal Medicine/Division of Cardiology (D.T.K., C.W.T.) and Department of Surgery (G.F.D., D.M.), Baylor Scott & White Health-Central Texas, Temple City; Department of Cell and Regenerative Biology and Biotechnology Center, University of Wisconsin School of Medicine and Public Health, Madison (P.A.P., D.P.F., R.L.M.); and Department of Physiology and Biophysics and Center for Cardiovascular Research, College of Medicine, University of Illinois, Chicago (B.G.P., C.M.W., R.J.S.)
| | - Rajesh Kumar
- From the Department of Medical Physiology (P.C.R., Y.L., M.I.A., B.M.M., C.W.T.) and Division of Molecular Cardiology, Department of Medicine (C.M.T., R.K., K.M.B.), Texas A&M University Health Science Center, College of Medicine, Temple City; Internal Medicine/Division of Cardiology (D.T.K., C.W.T.) and Department of Surgery (G.F.D., D.M.), Baylor Scott & White Health-Central Texas, Temple City; Department of Cell and Regenerative Biology and Biotechnology Center, University of Wisconsin School of Medicine and Public Health, Madison (P.A.P., D.P.F., R.L.M.); and Department of Physiology and Biophysics and Center for Cardiovascular Research, College of Medicine, University of Illinois, Chicago (B.G.P., C.M.W., R.J.S.)
| | - Kenneth M Baker
- From the Department of Medical Physiology (P.C.R., Y.L., M.I.A., B.M.M., C.W.T.) and Division of Molecular Cardiology, Department of Medicine (C.M.T., R.K., K.M.B.), Texas A&M University Health Science Center, College of Medicine, Temple City; Internal Medicine/Division of Cardiology (D.T.K., C.W.T.) and Department of Surgery (G.F.D., D.M.), Baylor Scott & White Health-Central Texas, Temple City; Department of Cell and Regenerative Biology and Biotechnology Center, University of Wisconsin School of Medicine and Public Health, Madison (P.A.P., D.P.F., R.L.M.); and Department of Physiology and Biophysics and Center for Cardiovascular Research, College of Medicine, University of Illinois, Chicago (B.G.P., C.M.W., R.J.S.)
| | - Brett M Mitchell
- From the Department of Medical Physiology (P.C.R., Y.L., M.I.A., B.M.M., C.W.T.) and Division of Molecular Cardiology, Department of Medicine (C.M.T., R.K., K.M.B.), Texas A&M University Health Science Center, College of Medicine, Temple City; Internal Medicine/Division of Cardiology (D.T.K., C.W.T.) and Department of Surgery (G.F.D., D.M.), Baylor Scott & White Health-Central Texas, Temple City; Department of Cell and Regenerative Biology and Biotechnology Center, University of Wisconsin School of Medicine and Public Health, Madison (P.A.P., D.P.F., R.L.M.); and Department of Physiology and Biophysics and Center for Cardiovascular Research, College of Medicine, University of Illinois, Chicago (B.G.P., C.M.W., R.J.S.)
| | - Patricia A Powers
- From the Department of Medical Physiology (P.C.R., Y.L., M.I.A., B.M.M., C.W.T.) and Division of Molecular Cardiology, Department of Medicine (C.M.T., R.K., K.M.B.), Texas A&M University Health Science Center, College of Medicine, Temple City; Internal Medicine/Division of Cardiology (D.T.K., C.W.T.) and Department of Surgery (G.F.D., D.M.), Baylor Scott & White Health-Central Texas, Temple City; Department of Cell and Regenerative Biology and Biotechnology Center, University of Wisconsin School of Medicine and Public Health, Madison (P.A.P., D.P.F., R.L.M.); and Department of Physiology and Biophysics and Center for Cardiovascular Research, College of Medicine, University of Illinois, Chicago (B.G.P., C.M.W., R.J.S.)
| | - Daniel P Fitzsimons
- From the Department of Medical Physiology (P.C.R., Y.L., M.I.A., B.M.M., C.W.T.) and Division of Molecular Cardiology, Department of Medicine (C.M.T., R.K., K.M.B.), Texas A&M University Health Science Center, College of Medicine, Temple City; Internal Medicine/Division of Cardiology (D.T.K., C.W.T.) and Department of Surgery (G.F.D., D.M.), Baylor Scott & White Health-Central Texas, Temple City; Department of Cell and Regenerative Biology and Biotechnology Center, University of Wisconsin School of Medicine and Public Health, Madison (P.A.P., D.P.F., R.L.M.); and Department of Physiology and Biophysics and Center for Cardiovascular Research, College of Medicine, University of Illinois, Chicago (B.G.P., C.M.W., R.J.S.)
| | - Bindiya G Patel
- From the Department of Medical Physiology (P.C.R., Y.L., M.I.A., B.M.M., C.W.T.) and Division of Molecular Cardiology, Department of Medicine (C.M.T., R.K., K.M.B.), Texas A&M University Health Science Center, College of Medicine, Temple City; Internal Medicine/Division of Cardiology (D.T.K., C.W.T.) and Department of Surgery (G.F.D., D.M.), Baylor Scott & White Health-Central Texas, Temple City; Department of Cell and Regenerative Biology and Biotechnology Center, University of Wisconsin School of Medicine and Public Health, Madison (P.A.P., D.P.F., R.L.M.); and Department of Physiology and Biophysics and Center for Cardiovascular Research, College of Medicine, University of Illinois, Chicago (B.G.P., C.M.W., R.J.S.)
| | - Chad M Warren
- From the Department of Medical Physiology (P.C.R., Y.L., M.I.A., B.M.M., C.W.T.) and Division of Molecular Cardiology, Department of Medicine (C.M.T., R.K., K.M.B.), Texas A&M University Health Science Center, College of Medicine, Temple City; Internal Medicine/Division of Cardiology (D.T.K., C.W.T.) and Department of Surgery (G.F.D., D.M.), Baylor Scott & White Health-Central Texas, Temple City; Department of Cell and Regenerative Biology and Biotechnology Center, University of Wisconsin School of Medicine and Public Health, Madison (P.A.P., D.P.F., R.L.M.); and Department of Physiology and Biophysics and Center for Cardiovascular Research, College of Medicine, University of Illinois, Chicago (B.G.P., C.M.W., R.J.S.)
| | - R John Solaro
- From the Department of Medical Physiology (P.C.R., Y.L., M.I.A., B.M.M., C.W.T.) and Division of Molecular Cardiology, Department of Medicine (C.M.T., R.K., K.M.B.), Texas A&M University Health Science Center, College of Medicine, Temple City; Internal Medicine/Division of Cardiology (D.T.K., C.W.T.) and Department of Surgery (G.F.D., D.M.), Baylor Scott & White Health-Central Texas, Temple City; Department of Cell and Regenerative Biology and Biotechnology Center, University of Wisconsin School of Medicine and Public Health, Madison (P.A.P., D.P.F., R.L.M.); and Department of Physiology and Biophysics and Center for Cardiovascular Research, College of Medicine, University of Illinois, Chicago (B.G.P., C.M.W., R.J.S.)
| | - Richard L Moss
- From the Department of Medical Physiology (P.C.R., Y.L., M.I.A., B.M.M., C.W.T.) and Division of Molecular Cardiology, Department of Medicine (C.M.T., R.K., K.M.B.), Texas A&M University Health Science Center, College of Medicine, Temple City; Internal Medicine/Division of Cardiology (D.T.K., C.W.T.) and Department of Surgery (G.F.D., D.M.), Baylor Scott & White Health-Central Texas, Temple City; Department of Cell and Regenerative Biology and Biotechnology Center, University of Wisconsin School of Medicine and Public Health, Madison (P.A.P., D.P.F., R.L.M.); and Department of Physiology and Biophysics and Center for Cardiovascular Research, College of Medicine, University of Illinois, Chicago (B.G.P., C.M.W., R.J.S.)
| | - Carl W Tong
- From the Department of Medical Physiology (P.C.R., Y.L., M.I.A., B.M.M., C.W.T.) and Division of Molecular Cardiology, Department of Medicine (C.M.T., R.K., K.M.B.), Texas A&M University Health Science Center, College of Medicine, Temple City; Internal Medicine/Division of Cardiology (D.T.K., C.W.T.) and Department of Surgery (G.F.D., D.M.), Baylor Scott & White Health-Central Texas, Temple City; Department of Cell and Regenerative Biology and Biotechnology Center, University of Wisconsin School of Medicine and Public Health, Madison (P.A.P., D.P.F., R.L.M.); and Department of Physiology and Biophysics and Center for Cardiovascular Research, College of Medicine, University of Illinois, Chicago (B.G.P., C.M.W., R.J.S.).
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24
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Tong CW, Wu X, Liu Y, Rosas PC, Sadayappan S, Hudmon A, Muthuchamy M, Powers PA, Valdivia HH, Moss RL. Phosphoregulation of Cardiac Inotropy via Myosin Binding Protein-C During Increased Pacing Frequency or β1-Adrenergic Stimulation. Circ Heart Fail 2015; 8:595-604. [PMID: 25740838 DOI: 10.1161/circheartfailure.114.001585] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 02/24/2015] [Indexed: 11/16/2022]
Abstract
BACKGROUND Mammalian hearts exhibit positive inotropic responses to β-adrenergic stimulation as a consequence of protein kinase A-mediated phosphorylation or as a result of increased beat frequency (the Bowditch effect). Several membrane and myofibrillar proteins are phosphorylated under these conditions, but the relative contributions of these to increased contractility are not known. Phosphorylation of cardiac myosin-binding protein-C (cMyBP-C) by protein kinase A accelerates the kinetics of force development in permeabilized heart muscle, but its role in vivo is unknown. Such understanding is important because adrenergic responsiveness of the heart and the Bowditch effect are both depressed in heart failure. METHODS AND RESULTS The roles of cMyBP-C phosphorylation were studied using mice in which either WT or nonphosphorylatable forms of cMyBP-C [ser273ala, ser282ala, ser302ala: cMyBP-C(t3SA)] were expressed at similar levels on a cMyBP-C null background. Force and [Ca(2+)]in measurements in isolated papillary muscles showed that the increased force and twitch kinetics because increased pacing or β1-adrenergic stimulation were nearly absent in cMyBP-C(t3SA) myocardium, even though [Ca(2+)]in transients under each condition were similar to WT. Biochemical measurements confirmed that protein kinase A phosphorylated ser273, ser282, and ser302 in WT cMyBP-C. In contrast, CaMKIIδ, which is activated by increased pacing, phosphorylated ser302 principally, ser282 to a lesser degree, and ser273 not at all. CONCLUSIONS Phosphorylation of cMyBP-C increases the force and kinetics of twitches in living cardiac muscle. Further, cMyBP-C is a principal mediator of increased contractility observed with β-adrenergic stimulation or increased pacing because of protein kinase A and CaMKIIδ phosphorylations of cMyB-C.
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Affiliation(s)
- Carl W Tong
- From the Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison (C.W.T., P.A.P., R.L.M.); Department of Medical Physiology (C.W.T., Y.L., P.C.R., M.M.) and Neuroscience and Experimental Therapeutics (X.W.), Texas A&M University Health Science Center College of Medicine, Temple; Baylor Scott & White Health, Temple, TX (C.W.T.); Department of Physiology, Loyola University Chicago Stritch School of Medicine, IL (S.S.); Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis (A.H.); and Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor (H.H.V.)
| | - Xin Wu
- From the Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison (C.W.T., P.A.P., R.L.M.); Department of Medical Physiology (C.W.T., Y.L., P.C.R., M.M.) and Neuroscience and Experimental Therapeutics (X.W.), Texas A&M University Health Science Center College of Medicine, Temple; Baylor Scott & White Health, Temple, TX (C.W.T.); Department of Physiology, Loyola University Chicago Stritch School of Medicine, IL (S.S.); Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis (A.H.); and Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor (H.H.V.)
| | - Yang Liu
- From the Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison (C.W.T., P.A.P., R.L.M.); Department of Medical Physiology (C.W.T., Y.L., P.C.R., M.M.) and Neuroscience and Experimental Therapeutics (X.W.), Texas A&M University Health Science Center College of Medicine, Temple; Baylor Scott & White Health, Temple, TX (C.W.T.); Department of Physiology, Loyola University Chicago Stritch School of Medicine, IL (S.S.); Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis (A.H.); and Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor (H.H.V.)
| | - Paola C Rosas
- From the Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison (C.W.T., P.A.P., R.L.M.); Department of Medical Physiology (C.W.T., Y.L., P.C.R., M.M.) and Neuroscience and Experimental Therapeutics (X.W.), Texas A&M University Health Science Center College of Medicine, Temple; Baylor Scott & White Health, Temple, TX (C.W.T.); Department of Physiology, Loyola University Chicago Stritch School of Medicine, IL (S.S.); Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis (A.H.); and Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor (H.H.V.)
| | - Sakthivel Sadayappan
- From the Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison (C.W.T., P.A.P., R.L.M.); Department of Medical Physiology (C.W.T., Y.L., P.C.R., M.M.) and Neuroscience and Experimental Therapeutics (X.W.), Texas A&M University Health Science Center College of Medicine, Temple; Baylor Scott & White Health, Temple, TX (C.W.T.); Department of Physiology, Loyola University Chicago Stritch School of Medicine, IL (S.S.); Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis (A.H.); and Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor (H.H.V.)
| | - Andy Hudmon
- From the Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison (C.W.T., P.A.P., R.L.M.); Department of Medical Physiology (C.W.T., Y.L., P.C.R., M.M.) and Neuroscience and Experimental Therapeutics (X.W.), Texas A&M University Health Science Center College of Medicine, Temple; Baylor Scott & White Health, Temple, TX (C.W.T.); Department of Physiology, Loyola University Chicago Stritch School of Medicine, IL (S.S.); Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis (A.H.); and Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor (H.H.V.)
| | - Mariappan Muthuchamy
- From the Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison (C.W.T., P.A.P., R.L.M.); Department of Medical Physiology (C.W.T., Y.L., P.C.R., M.M.) and Neuroscience and Experimental Therapeutics (X.W.), Texas A&M University Health Science Center College of Medicine, Temple; Baylor Scott & White Health, Temple, TX (C.W.T.); Department of Physiology, Loyola University Chicago Stritch School of Medicine, IL (S.S.); Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis (A.H.); and Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor (H.H.V.)
| | - Patricia A Powers
- From the Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison (C.W.T., P.A.P., R.L.M.); Department of Medical Physiology (C.W.T., Y.L., P.C.R., M.M.) and Neuroscience and Experimental Therapeutics (X.W.), Texas A&M University Health Science Center College of Medicine, Temple; Baylor Scott & White Health, Temple, TX (C.W.T.); Department of Physiology, Loyola University Chicago Stritch School of Medicine, IL (S.S.); Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis (A.H.); and Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor (H.H.V.)
| | - Héctor H Valdivia
- From the Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison (C.W.T., P.A.P., R.L.M.); Department of Medical Physiology (C.W.T., Y.L., P.C.R., M.M.) and Neuroscience and Experimental Therapeutics (X.W.), Texas A&M University Health Science Center College of Medicine, Temple; Baylor Scott & White Health, Temple, TX (C.W.T.); Department of Physiology, Loyola University Chicago Stritch School of Medicine, IL (S.S.); Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis (A.H.); and Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor (H.H.V.)
| | - Richard L Moss
- From the Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison (C.W.T., P.A.P., R.L.M.); Department of Medical Physiology (C.W.T., Y.L., P.C.R., M.M.) and Neuroscience and Experimental Therapeutics (X.W.), Texas A&M University Health Science Center College of Medicine, Temple; Baylor Scott & White Health, Temple, TX (C.W.T.); Department of Physiology, Loyola University Chicago Stritch School of Medicine, IL (S.S.); Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis (A.H.); and Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor (H.H.V.).
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25
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Pfeiffer ER, Tangney JR, Omens JH, McCulloch AD. Biomechanics of cardiac electromechanical coupling and mechanoelectric feedback. J Biomech Eng 2014; 136:021007. [PMID: 24337452 DOI: 10.1115/1.4026221] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 12/12/2013] [Indexed: 11/08/2022]
Abstract
Cardiac mechanical contraction is triggered by electrical activation via an intracellular calcium-dependent process known as excitation-contraction coupling. Dysregulation of cardiac myocyte intracellular calcium handling is a common feature of heart failure. At the organ scale, electrical dyssynchrony leads to mechanical alterations and exacerbates pump dysfunction in heart failure. A reverse coupling between cardiac mechanics and electrophysiology is also well established. It is commonly referred as cardiac mechanoelectric feedback and thought to be an important contributor to the increased risk of arrhythmia during pathological conditions that alter regional cardiac wall mechanics, including heart failure. At the cellular scale, most investigations of myocyte mechanoelectric feedback have focused on the roles of stretch-activated ion channels, though mechanisms that are independent of ionic currents have also been described. Here we review excitation-contraction coupling and mechanoelectric feedback at the cellular and organ scales, and we identify the need for new multicellular tissue-scale model systems and experiments that can help us to obtain a better understanding of how interactions between electrophysiological and mechanical processes at the cell scale affect ventricular electromechanical interactions at the organ scale in the normal and diseased heart.
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26
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Bhatt NM, Aon MA, Tocchetti CG, Shen X, Dey S, Ramirez-Correa G, O'Rourke B, Gao WD, Cortassa S. Restoring redox balance enhances contractility in heart trabeculae from type 2 diabetic rats exposed to high glucose. Am J Physiol Heart Circ Physiol 2014; 308:H291-302. [PMID: 25485897 DOI: 10.1152/ajpheart.00378.2014] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Hearts from type 2 diabetic (T2DM) subjects are chronically subjected to hyperglycemia and hyperlipidemia, both thought to contribute to oxidizing conditions and contractile dysfunction. How redox alterations and contractility interrelate, ultimately diminishing T2DM heart function, remains poorly understood. Herein we tested whether the fatty acid palmitate (Palm), in addition to its energetic contribution, rescues function by improving redox [glutathione (GSH), NAD(P)H, less oxidative stress] in T2DM rat heart trabeculae subjected to high glucose. Using cardiac trabeculae from Zucker Diabetic Fatty (ZDF) rats, we assessed the impact of low glucose (EG) and high glucose (HG), in absence or presence of Palm or insulin, on force development, energetics, and redox responses. We found that in EG ZDF and lean trabeculae displayed similar contractile work, yield of contractile work (Ycw), representing the ratio of force time integral over rate of O2 consumption. Conversely, HG had a negative impact on Ycw, whereas Palm, but not insulin, completely prevented contractile loss. This effect was associated with higher GSH, less oxidative stress, and augmented matrix GSH/thioredoxin (Trx) in ZDF mitochondria. Restoration of myocardial redox with GSH ethyl ester also rescued ZDF contractile function in HG, independently from Palm. These results support the idea that maintained redox balance, via increased GSH and Trx antioxidant activities to resist oxidative stress, is an essential protective response of the diabetic heart to keep contractile function.
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Affiliation(s)
- Niraj M Bhatt
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
| | - Miguel A Aon
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
| | - Carlo G Tocchetti
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
| | - Xiaoxu Shen
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Swati Dey
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
| | - Genaro Ramirez-Correa
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
| | - Brian O'Rourke
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
| | - Wei Dong Gao
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Sonia Cortassa
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
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Biesiadecki BJ, Davis JP, Ziolo MT, Janssen PML. Tri-modal regulation of cardiac muscle relaxation; intracellular calcium decline, thin filament deactivation, and cross-bridge cycling kinetics. Biophys Rev 2014; 6:273-289. [PMID: 28510030 PMCID: PMC4255972 DOI: 10.1007/s12551-014-0143-5] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 06/27/2014] [Indexed: 01/09/2023] Open
Abstract
Cardiac muscle relaxation is an essential step in the cardiac cycle. Even when the contraction of the heart is normal and forceful, a relaxation phase that is too slow will limit proper filling of the ventricles. Relaxation is too often thought of as a mere passive process that follows contraction. However, many decades of advancements in our understanding of cardiac muscle relaxation have shown it is a highly complex and well-regulated process. In this review, we will discuss three distinct events that can limit the rate of cardiac muscle relaxation: the rate of intracellular calcium decline, the rate of thin-filament de-activation, and the rate of cross-bridge cycling. Each of these processes are directly impacted by a plethora of molecular events. In addition, these three processes interact with each other, further complicating our understanding of relaxation. Each of these processes is continuously modulated by the need to couple bodily oxygen demand to cardiac output by the major cardiac physiological regulators. Length-dependent activation, frequency-dependent activation, and beta-adrenergic regulation all directly and indirectly modulate calcium decline, thin-filament deactivation, and cross-bridge kinetics. We hope to convey our conclusion that cardiac muscle relaxation is a process of intricate checks and balances, and should not be thought of as a single rate-limiting step that is regulated at a single protein level. Cardiac muscle relaxation is a system level property that requires fundamental integration of three governing systems: intracellular calcium decline, thin filament deactivation, and cross-bridge cycling kinetics.
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Affiliation(s)
- Brandon J Biesiadecki
- Department of Physiology and Cell Biology and Dorothy M. Davis Heart Lung Institute, College of Medicine, The Ohio State University, 304 Hamilton Hall, 1645 Neil Avenue, Columbus, OH, 43210-1218, USA
| | - Jonathan P Davis
- Department of Physiology and Cell Biology and Dorothy M. Davis Heart Lung Institute, College of Medicine, The Ohio State University, 304 Hamilton Hall, 1645 Neil Avenue, Columbus, OH, 43210-1218, USA
| | - Mark T Ziolo
- Department of Physiology and Cell Biology and Dorothy M. Davis Heart Lung Institute, College of Medicine, The Ohio State University, 304 Hamilton Hall, 1645 Neil Avenue, Columbus, OH, 43210-1218, USA
| | - Paul M L Janssen
- Department of Physiology and Cell Biology and Dorothy M. Davis Heart Lung Institute, College of Medicine, The Ohio State University, 304 Hamilton Hall, 1645 Neil Avenue, Columbus, OH, 43210-1218, USA.
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Ramirez-Correa GA, Frazier AH, Zhu G, Zhang P, Rappold T, Kooij V, Bedja D, Snyder GA, Lugo-Fagundo NS, Hariharan R, Li Y, Shen X, Gao WD, Cingolani OH, Takimoto E, Foster DB, Murphy AM. Cardiac troponin I Pro82Ser variant induces diastolic dysfunction, blunts β-adrenergic response, and impairs myofilament cooperativity. J Appl Physiol (1985) 2014; 118:212-23. [PMID: 25324519 DOI: 10.1152/japplphysiol.00463.2014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Troponin I (TnI) variant Pro82Ser (cTnIP82S) was initially considered a disease-causing mutation; however, later studies suggested the contrary. We tested the hypothesis of whether a causal link exists between cTnIP82S and cardiac structural and functional remodeling, such as during aging or chronic pressure overload. A cardiac-specific transgenic (Tg) mouse model of cTnIP82S was created to test this hypothesis. During aging, Tg cTnIP82S displayed diastolic dysfunction, characterized by longer isovolumetric relaxation time, and impaired ejection and relaxation time. In young, Tg mice in vivo pressure-volume loops and intact trabecular preparations revealed normal cardiac contractility at baseline. However, upon β-adrenergic stimulation, a blunted contractile reserve and no hastening in left ventricle relaxation were evident in vivo, whereas, in isolated muscles, Ca(2+) transient amplitude isoproterenol dose-response was blunted. In addition, when exposed to chronic pressure overload, Tg mice show exacerbated hypertrophy and decreased contractility compared with age-matched non-Tg littermates. At the molecular level, this mutation significantly impairs myofilament cooperative activation. Importantly, this occurs in the absence of alterations in TnI or myosin-binding protein C phosphorylation. The cTnIP82S variant occurs near a region of interactions with troponin T; therefore, structural changes in this region could explain its meaningful effects on myofilament cooperativity. Our data indicate that cTnIP82S mutation modifies age-dependent diastolic dysfunction and impairs overall contractility after β-adrenergic stimulation or chronic pressure overload. Thus cTnIP82S variant should be regarded as a disease-modifying factor for dysfunction and adverse remodeling with aging and chronic pressure overload.
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Affiliation(s)
- Genaro A Ramirez-Correa
- Department of Pediatrics and Division of Pediatric Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Aisha H Frazier
- Department of Pediatrics and Division of Pediatric Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Guangshuo Zhu
- Department of Medicine and Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Pingbo Zhang
- The Hopkins Bayview Proteomics Center, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Thomas Rappold
- The Hopkins Bayview Proteomics Center, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Viola Kooij
- The Hopkins Bayview Proteomics Center, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Djahida Bedja
- Department of Comparative Medicine and Comparative Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Greg A Snyder
- Institute of Human Virology, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Nahyr S Lugo-Fagundo
- Department of Pediatrics and Division of Pediatric Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Raena Hariharan
- Department of Pediatrics and Division of Pediatric Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Yuejin Li
- Department of Pediatrics and Division of Pediatric Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Xiaoxu Shen
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
| | - Wei Dong Gao
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
| | - Oscar H Cingolani
- Department of Medicine and Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Eiki Takimoto
- Department of Medicine and Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - D Brian Foster
- Department of Medicine and Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Anne M Murphy
- Department of Pediatrics and Division of Pediatric Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
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29
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MacDonald JK, Pyle WG, Reitz CJ, Howlett SE. Cardiac contraction, calcium transients, and myofilament calcium sensitivity fluctuate with the estrous cycle in young adult female mice. Am J Physiol Heart Circ Physiol 2014; 306:H938-53. [DOI: 10.1152/ajpheart.00730.2013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
This study established conditions to induce regular estrous cycles in female C57BL/6J mice and investigated the impact of the estrous cycle on contractions, Ca2+ transients, and underlying cardiac excitation-contraction (EC)-coupling mechanisms. Daily vaginal smears from group-housed virgin female mice were stained to distinguish estrous stage (proestrus, estrus, metestrus, diestrus). Ventricular myocytes were isolated from anesthetized mice. Contractions and Ca2+ transients were measured simultaneously (4 Hz, 37°C). Interestingly, mice did not exhibit regular cycles unless they were exposed to male pheromones in bedding added to their cages. Field-stimulated myocytes from mice in estrus had larger contractions (∼2-fold increase), larger Ca2+ transients (∼1.11-fold increase), and longer action potentials (>2-fold increase) compared with other stages. Larger contractions and Ca2+ transients were not observed in estrus myocytes voltage-clamped with shorter action potentials. Voltage-clamp experiments also demonstrated that estrous stage had no effect on Ca2+ current, EC-coupling gain, diastolic Ca2+, sarcoplasmic reticulum (SR) Ca2+ content, or fractional release. Although contractions were largest in estrus, myofilament Ca2+ sensitivity was lowest (EC50 values ∼1.15-fold higher) in conjunction with increased phosphorylation of myosin binding protein C in estrus. Contractions were enhanced in ventricular myocytes from mice in estrus because action potential prolongation increased SR Ca2+ release. These findings demonstrate that cyclical changes in reproductive hormones associated with the estrous cycle can influence myocardial electrical and contractile function and modify Ca2+ homeostasis. However, such changes are unlikely to occur in female mice housed in groups under conventional conditions, since these mice do not exhibit regular estrous cycles.
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Affiliation(s)
| | - W. Glen Pyle
- Cardiovascular Research Group, Department of Biomedical Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - Cristine J. Reitz
- Cardiovascular Research Group, Department of Biomedical Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - Susan E. Howlett
- Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Medicine (Geriatric Medicine), Dalhousie University, Halifax, Nova Scotia, Canada
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30
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Stoehr A, Neuber C, Baldauf C, Vollert I, Friedrich FW, Flenner F, Carrier L, Eder A, Schaaf S, Hirt MN, Aksehirlioglu B, Tong CW, Moretti A, Eschenhagen T, Hansen A. Automated analysis of contractile force and Ca2+ transients in engineered heart tissue. Am J Physiol Heart Circ Physiol 2014; 306:H1353-63. [PMID: 24585781 DOI: 10.1152/ajpheart.00705.2013] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Contraction and relaxation are fundamental aspects of cardiomyocyte functional biology. They reflect the response of the contractile machinery to the systolic increase and diastolic decrease of the cytoplasmic Ca(2+) concentration. The analysis of contractile function and Ca(2+) transients is therefore important to discriminate between myofilament responsiveness and changes in Ca(2+) homeostasis. This article describes an automated technology to perform sequential analysis of contractile force and Ca(2+) transients in up to 11 strip-format, fibrin-based rat, mouse, and human fura-2-loaded engineered heart tissues (EHTs) under perfusion and electrical stimulation. Measurements in EHTs under increasing concentrations of extracellular Ca(2+) and responses to isoprenaline and carbachol demonstrate that EHTs recapitulate basic principles of heart tissue functional biology. Ca(2+) concentration-response curves in rat, mouse, and human EHTs indicated different maximal twitch forces (0.22, 0.05, and 0.08 mN in rat, mouse, and human, respectively; P < 0.001) and different sensitivity to external Ca(2+) (EC50: 0.15, 0.39, and 1.05 mM Ca(2+) in rat, mouse, and human, respectively; P < 0.001) in the three groups. In contrast, no difference in myofilament Ca(2+) sensitivity was detected between skinned rat and human EHTs, suggesting that the difference in sensitivity to external Ca(2+) concentration is due to changes in Ca(2+) handling proteins. Finally, this study confirms that fura-2 has Ca(2+) buffering effects and is thereby changing the force response to extracellular Ca(2+).
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Affiliation(s)
- Andrea Stoehr
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistraße, Hamburg, Germany
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31
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Prasad V, Lorenz JN, Lasko VM, Nieman ML, Al Moamen NJ, Shull GE. Loss of the AE3 Cl(-)/HCO(-) 3 exchanger in mice affects rate-dependent inotropy and stress-related AKT signaling in heart. Front Physiol 2013; 4:399. [PMID: 24427143 PMCID: PMC3875869 DOI: 10.3389/fphys.2013.00399] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Accepted: 12/19/2013] [Indexed: 01/12/2023] Open
Abstract
Cl(-)/HCO(-) 3 exchangers are expressed abundantly in cardiac muscle, suggesting that HCO(-) 3 extrusion serves an important function in heart. Mice lacking Anion Exchanger Isoform 3 (AE3), a major cardiac Cl(-)/HCO(-) 3 exchanger, appear healthy, but loss of AE3 causes decompensation in a hypertrophic cardiomyopathy (HCM) model. Using intra-ventricular pressure analysis, in vivo pacing, and molecular studies we identified physiological and biochemical changes caused by loss of AE3 that may contribute to decompensation in HCM. AE3-null mice had normal cardiac contractility under basal conditions and after β-adrenergic stimulation, but pacing of hearts revealed that frequency-dependent inotropy was blunted, suggesting that AE3-mediated HCO(-) 3 extrusion is required for a robust force-frequency response (FFR) during acute biomechanical stress in vivo. Modest changes in expression of proteins that affect Ca(2+)-handling were observed, but Ca(2+)-transient analysis of AE3-null myocytes showed normal twitch-amplitude and Ca(2+)-clearance. Phosphorylation and expression of several proteins implicated in HCM and FFR, including phospholamban (PLN), myosin binding protein C, and troponin I were not altered in hearts of paced AE3-null mice; however, phosphorylation of Akt, which plays a central role in mechanosensory signaling, was significantly higher in paced AE3-null hearts than in wild-type controls and phosphorylation of AMPK, which is affected by Akt and is involved in energy metabolism and some cases of HCM, was reduced. These data show loss of AE3 leads to impaired rate-dependent inotropy, appears to affect mechanical stress-responsive signaling, and reduces activation of AMPK, which may contribute to decompensation in heart failure.
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Affiliation(s)
- Vikram Prasad
- Departments of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine Cincinnati, OH, USA
| | - John N Lorenz
- Departments of Cellular and Molecular Physiology, University of Cincinnati College of Medicine Cincinnati, OH, USA
| | - Valerie M Lasko
- Departments of Cellular and Molecular Physiology, University of Cincinnati College of Medicine Cincinnati, OH, USA
| | - Michelle L Nieman
- Departments of Cellular and Molecular Physiology, University of Cincinnati College of Medicine Cincinnati, OH, USA
| | - Nabeel J Al Moamen
- Genetic Laboratory, Department of Pathology, Salmaniya Medical Complex Manama, Bahrain
| | - Gary E Shull
- Departments of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine Cincinnati, OH, USA
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Tang M, Yuan W, Fan X, Liu M, Bodmer R, Ocorr K, Wu X. Pygopus maintains heart function in aging Drosophila independently of canonical Wnt signaling. CIRCULATION. CARDIOVASCULAR GENETICS 2013; 6:472-80. [PMID: 24046329 PMCID: PMC3871875 DOI: 10.1161/circgenetics.113.000253] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND Heart function declines with age, but the genetic factors underlying such deterioration are largely unknown. Wnt signaling is known to play a role in heart development, but it has not been shown to be important in adult heart function. We have investigated the nuclear adapter protein encoded by pygopus (pygo), which mediates canonical Wnt signaling, for roles in aging-related cardiac dysfunction. METHODS AND RESULTS Using the Drosophila heart model, we show that cardiac-specific pygo knockdown in adult flies causes a significant (4- to 5-fold) increase in cardiac arrhythmias (P<0.001) that worsened with age and caused a significant decrease in contractility (-54%; P<0.001) with systolic dysfunction. Immunohistochemistry revealed structural abnormalities that worsened with age, and both functional and morphological alterations were ameliorated by pygo overexpression. Unexpectedly, knockdown of 2 other Wnt signaling components, β-cat/armadillo or TCF/pangolin, had relatively milder effects on cardiac function. Double-heterozygous combinations of mutants for pygo and canonical Wnt signaling components had no additional effect on heart function over pygo heterozygotes alone. However, double knockdown of pygo and Ca2+/calmodulin-dependent protein kinase II caused additional arrhythmia compared with pygo knockdown alone, suggesting that some of the effects of pygo are mediated by Ca2+ signaling. In the isoproterenol-induced hypertrophic mouse model, we show that Pygo1 protein levels are increased. CONCLUSIONS Our data indicate that Pygo plays a critical role in adult heart function that is Wnt signaling independent and is likely conserved in mammals.
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Affiliation(s)
- Min Tang
- Development and Aging Program, Sanford-Burnham Medical Research Institute, La Jolla, CA
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33
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Contractile abnormalities and altered drug response in engineered heart tissue from Mybpc3-targeted knock-in mice. J Mol Cell Cardiol 2013; 63:189-98. [PMID: 23896226 DOI: 10.1016/j.yjmcc.2013.07.011] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Revised: 07/08/2013] [Accepted: 07/11/2013] [Indexed: 11/20/2022]
Abstract
Myosin-binding protein C (Mybpc3)-targeted knock-in mice (KI) recapitulate typical aspects of human hypertrophic cardiomyopathy. We evaluated whether these functional alterations can be reproduced in engineered heart tissue (EHT) and yield novel mechanistic information on the function of cMyBP-C. EHTs were generated from cardiac cells of neonatal KI, heterozygous (HET) or wild-type controls (WT) and developed without apparent morphological differences. KI had 70% and HET 20% lower total cMyBP-C levels than WT, accompanied by elevated fetal gene expression. Under standard culture conditions and spontaneous beating, KI EHTs showed more frequent burst beating than WT and occasional tetanic contractions (14/96). Under electrical stimulation (6Hz, 37°C) KI EHTs exhibited shorter contraction and relaxation times and a twofold higher sensitivity to external [Ca(2+)]. Accordingly, the sensitivity to verapamil was 4-fold lower and the response to isoprenaline or the Ca(2+) sensitizer EMD 57033 2- to 4-fold smaller. The loss of EMD effect was verified in 6-week-old KI mice in vivo. HET EHTs were apparently normal under basal conditions, but showed similarly altered contractile responses to [Ca(2+)], verapamil, isoprenaline and EMD. In contrast, drug-induced changes in intracellular Ca(2+) transients (Fura-2) were essentially normal. In conclusion, the present findings in auxotonically contracting EHTs support the idea that cMyBP-C's normal role is to suppress force generation at low intracellular Ca(2+) and stabilize the power-stroke step of the cross bridge cycle. Pharmacological testing in EHT unmasked a disease phenotype in HET. The altered drug response may be clinically relevant.
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34
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de Lange WJ, Grimes AC, Hegge LF, Ralphe JC. Ablation of cardiac myosin-binding protein-C accelerates contractile kinetics in engineered cardiac tissue. ACTA ACUST UNITED AC 2013; 141:73-84. [PMID: 23277475 PMCID: PMC3536521 DOI: 10.1085/jgp.201210837] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Hypertrophic cardiomyopathy (HCM) caused by mutations in cardiac myosin–binding protein-C (cMyBP-C) is a heterogenous disease in which the phenotypic presentation is influenced by genetic, environmental, and developmental factors. Though mouse models have been used extensively to study the contractile effects of cMyBP-C ablation, early postnatal hypertrophic and dilatory remodeling may overshadow primary contractile defects. The use of a murine engineered cardiac tissue (mECT) model of cMyBP-C ablation in the present study permits delineation of the primary contractile kinetic abnormalities in an intact tissue model under mechanical loading conditions in the absence of confounding remodeling events. We generated mechanically integrated mECT using isolated postnatal day 1 mouse cardiac cells from both wild-type (WT) and cMyBP-C–null hearts. After culturing for 1 wk to establish coordinated spontaneous contraction, we measured twitch force and Ca2+ transients at 37°C during pacing at 6 and 9 Hz, with and without dobutamine. Compared with WT, the cMyBP-C–null mECT demonstrated faster late contraction kinetics and significantly faster early relaxation kinetics with no difference in Ca2+ transient kinetics. Strikingly, the ability of cMyBP-C–null mECT to increase contractile kinetics in response to adrenergic stimulation and increased pacing frequency were severely impaired. We conclude that cMyBP-C ablation results in constitutively accelerated contractile kinetics with preserved peak force with minimal contractile kinetic reserve. These functional abnormalities precede the development of the hypertrophic phenotype and do not result from alterations in Ca2+ transient kinetics, suggesting that alterations in contractile velocity may serve as the primary functional trigger for the development of hypertrophy in this model of HCM. Our findings strongly support a mechanism in which cMyBP-C functions as a physiological brake on contraction by positioning myosin heads away from the thin filament, a constraint which is removed upon adrenergic stimulation or cMyBP-C ablation.
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Affiliation(s)
- Willem J de Lange
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA
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35
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Milani-Nejad N, Xu Y, Davis JP, Campbell KS, Janssen PML. Effect of muscle length on cross-bridge kinetics in intact cardiac trabeculae at body temperature. ACTA ACUST UNITED AC 2013; 141:133-9. [PMID: 23277479 PMCID: PMC3536524 DOI: 10.1085/jgp.201210894] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Dynamic force generation in cardiac muscle, which determines cardiac pumping activity, depends on both the number of sarcomeric cross-bridges and on their cycling kinetics. The Frank–Starling mechanism dictates that cardiac force development increases with increasing cardiac muscle length (corresponding to increased ventricular volume). It is, however, unclear to what extent this increase in cardiac muscle length affects the rate of cross-bridge cycling. Previous studies using permeabilized cardiac preparations, sub-physiological temperatures, or both have obtained conflicting results. Here, we developed a protocol that allowed us to reliably and reproducibly measure the rate of tension redevelopment (ktr; which depends on the rate of cross-bridge cycling) in intact trabeculae at body temperature. Using K+ contractures to induce a tonic level of force, we showed the ktr was slower in rabbit muscle (which contains predominantly β myosin) than in rat muscle (which contains predominantly α myosin). Analyses of ktr in rat muscle at optimal length (Lopt) and 90% of optimal length (L90) revealed that ktr was significantly slower at Lopt (27.7 ± 3.3 and 27.8 ± 3.0 s−1 in duplicate analyses) than at L90 (45.1 ± 7.6 and 47.5 ± 9.2 s−1). We therefore show that ktr can be measured in intact rat and rabbit cardiac trabeculae, and that the ktr decreases when muscles are stretched to their optimal length under near-physiological conditions, indicating that the Frank–Starling mechanism not only increases force but also affects cross-bridge cycling kinetics.
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Affiliation(s)
- Nima Milani-Nejad
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
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36
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Donaldson C, Palmer BM, Zile M, Maughan DW, Ikonomidis JS, Granzier H, Meyer M, VanBuren P, LeWinter MM. Myosin cross-bridge dynamics in patients with hypertension and concentric left ventricular remodeling. Circ Heart Fail 2012; 5:803-11. [PMID: 23014131 DOI: 10.1161/circheartfailure.112.968925] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Hypertension (HTN) causes concentric left ventricular remodeling, defined as an increased relative wall thickness or overt left ventricular hypertrophy, and associated diastolic dysfunction. HTN and concentric remodeling are also common precursors to heart failure with a preserved ejection fraction. It is not known whether the myofilament contributes to diastolic dysfunction in patients with concentric remodeling. METHODS AND RESULTS Intraoperative myocardial biopsies were obtained in 15 male patients undergoing coronary bypass grafting, all with normal left ventricular ejection fraction and wall motion. Eight patients had a history of HTN and concentric remodeling. Seven without HTN or remodeling served as controls. Myocardial strips were dissected and demembranated with detergent. Isometric tension was measured and sinusoidal length perturbation analysis performed at sarcomere length 2.2 μm and pCa 8 to 4.5. Sinusoidal analysis provides estimates of cross-bridge dynamics, including rate constants of attachment and detachment and cross-bridge attachment time. The normalized isometric tension-pCa relation was similar in HTN and controls. However, cross-bridge attachment time was significantly prolonged at submaximal [Ca(2+)] (pCa ≥6.5) in HTN patients. Analysis of protein phosphorylation revealed ≈25% reduction in phosphorylation of troponin I in HTN patients (P<0.05). CONCLUSIONS Compared with controls, patients with HTN and concentric remodeling display prolonged cross-bridge attachment time at submaximal [Ca(2+)] without a change in the tension-pCa relation. Prolonged cross-bridge attachment time implicates altered cross-bridge dynamics as a cause of slowed relaxation in these patients. This finding was associated with reduced phosphorylation of troponin I, suggesting decreased phosphorylation of protein kinase A/G sites as a mechanism.
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37
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Wu Y, Luczak ED, Lee EJ, Hidalgo C, Yang J, Gao Z, Li J, Wehrens X, Granzier H, Anderson ME. CaMKII effects on inotropic but not lusitropic force frequency responses require phospholamban. J Mol Cell Cardiol 2012; 53:429-36. [PMID: 22796260 PMCID: PMC3936404 DOI: 10.1016/j.yjmcc.2012.06.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 06/04/2012] [Accepted: 06/29/2012] [Indexed: 11/27/2022]
Abstract
Increasing heart rate enhances cardiac contractility (force frequency relationship, FFR) and accelerates cardiac relaxation (frequency-dependent acceleration of relaxation, FDAR). The positive FFR together with FDAR promotes rapid filling and ejection of blood from the left ventricle (LV) at higher heart rates. Recent studies indicate that the multifunctional Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is involved in regulating FFR and FDAR. We used isolated perfused mouse hearts to study the mechanisms of FFR and FDAR in different genetic models, including transgenic myocardial CaMKII inhibition (AC3-I) and phospholmban knockout (PLN(-/-)). When the rate was increased from 360 beats/min to 630 beats/min in wild type mouse hearts, the LV developed pressure (LVDP) and the maximum rate of increase in pressure (dP/dt max) increased by 37.6 ± 4.7% and 77.0 ± 8.1%, respectively. However, hearts from AC3-I littermates showed no increase of LVDP and a relatively modest (20.4 ± 3.9%) increase in dP/dt max. PLN(-/-) hearts had a negative FFR, and myocardial AC3-I expression did not change the FFR in PLN(-/-) mice. PLN(-/-) mouse hearts did not exhibit FDAR, while PLN(-/-) mice with myocardial AC3-I expression showed further frequency dependent reductions in cardiac relaxation, suggesting that CaMKII targets in addition to PLN were critical to myocardial relaxation. We incubated a constitutively active form of CaMKII with chemically-skinned myocardium and found that several myofilament proteins were phosphorylated by CaMKII. However, CaMKII did not affect myofilament calcium sensitivity. Our study shows that CaMKII plays an important role in modulating FFR and FDAR in murine hearts and suggest that PLN is a critical target for CaMKII effects on FFR, while CaMKII effects on FDAR partially require PLN-alternative targets.
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Affiliation(s)
- Yiming Wu
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA
| | - Elizabeth D Luczak
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA
| | - Eun-Jeong Lee
- Department of Physiology, University of Arizona, Tucson, AZ 85724
| | - Carlos Hidalgo
- Department of Physiology, University of Arizona, Tucson, AZ 85724
| | - Jinying Yang
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA
| | - Zhan Gao
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA
| | - Jingdong Li
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA
| | - Xander Wehrens
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX
| | - Henk Granzier
- Department of Physiology, University of Arizona, Tucson, AZ 85724
| | - Mark E Anderson
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA
- Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA
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Lu Y, Kwan AH, Jeffries CM, Guss JM, Trewhella J. The motif of human cardiac myosin-binding protein C is required for its Ca2+-dependent interaction with calmodulin. J Biol Chem 2012; 287:31596-607. [PMID: 22801425 DOI: 10.1074/jbc.m112.383299] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The N-terminal modules of cardiac myosin-binding protein C (cMyBP-C) play a regulatory role in mediating interactions between myosin and actin during heart muscle contraction. The so-called "motif," located between the second and third immunoglobulin modules of the cardiac isoform, is believed to modulate contractility via an "on-off" phosphorylation-dependent tether to myosin ΔS2. Here we report a novel Ca(2+)-dependent interaction between the motif and calmodulin (CaM) based on the results of a combined fluorescence, NMR, and light and x-ray scattering study. We show that constructs of cMyBP-C containing the motif bind to Ca(2+)/CaM with a moderate affinity (K(D) ∼10 μM), which is similar to the affinity previously determined for myosin ΔS2. However, unlike the interaction with myosin ΔS2, the Ca(2+)/CaM interaction is unaffected by substitution with a triphosphorylated motif mimic. Further, Ca(2+)/CaM interacts with the highly conserved residues (Glu(319)-Lys(341)) toward the C-terminal end of the motif. Consistent with the Ca(2+) dependence, the binding of CaM to the motif is mediated via the hydrophobic clefts within the N- and C-lobes that are known to become more exposed upon Ca(2+) binding. Overall, Ca(2+)/CaM engages with the motif in an extended clamp configuration as opposed to the collapsed binding mode often observed in other CaM-protein interactions. Our results suggest that CaM may act as a structural conduit that links cMyBP-C with Ca(2+) signaling pathways to help coordinate phosphorylation events and synchronize the multiple interactions between cMyBP-C, myosin, and actin during the heart muscle contraction.
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Affiliation(s)
- Yanling Lu
- School of Molecular Bioscience, Building G08, The University of Sydney, New South Wales 2006, Australia
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39
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Staurosporine inhibits frequency-dependent myofilament desensitization in intact rabbit cardiac trabeculae. Biochem Res Int 2012; 2012:290971. [PMID: 22649731 PMCID: PMC3357507 DOI: 10.1155/2012/290971] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 02/22/2012] [Indexed: 11/17/2022] Open
Abstract
Myofilament calcium sensitivity decreases with frequency in intact healthy rabbit trabeculae and associates with Troponin I and Myosin light chain-2 phosphorylation. We here tested whether serine-threonine kinase activity is primarily responsible for this frequency-dependent modulations of myofilament calcium sensitivity. Right ventricular trabeculae were isolated from New Zealand White rabbit hearts and iontophoretically loaded with bis-fura-2. Twitch force-calcium relationships and steady state force-calcium relationships were measured at frequencies of 1 and 4 Hz at 37 °C. Staurosporine (100 nM), a nonspecific serine-threonine kinase inhibitor, or vehicle (DMSO) was included in the superfusion solution before and during the contractures. Staurosporine had no frequency-dependent effect on force development, kinetics, calcium transient amplitude, or rate of calcium transient decline. The shift in the pCa50 of the force-calcium relationship was significant from 6.05 ± 0.04 at 1 Hz versus 5.88 ± 0.06 at 4 Hz under control conditions (vehicle, P < 0.001) but not in presence of staurosporine (5.89 ± 0.08 at 1 Hz versus 5.94 ± 0.07 at 4 Hz, P = NS). Phosphoprotein analysis (Pro-Q Diamond stain) confirmed that staurosporine significantly blunted the frequency-dependent phosphorylation at Troponin I and Myosin light chain-2. We conclude that frequency-dependent modulation of calcium sensitivity is mediated through a kinase-specific effect involving phosphorylation of myofilament proteins.
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40
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Slabaugh JL, Brunello L, Gyorke S, Janssen PML. Contractile parameters and occurrence of alternans in isolated rat myocardium at supra-physiological stimulation frequency. Am J Physiol Heart Circ Physiol 2012; 302:H2267-75. [PMID: 22467303 DOI: 10.1152/ajpheart.01004.2011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The cardiac refractory period prevents the heart from tetanic activation that is typically used in noncardiac striated muscle tissue. To what extent the refractory period prevents successive action potentials to activate the excitation-contraction coupling process and contractile machinery at supra-physiological rates, such as those present during ventricular fibrillation, is unknown. Using multicellular trabeculae isolated from rat hearts, we studied amplitude and kinetics of contraction at rates well above the normal in vivo rat heart range. We show that even at twice the maximal heart rate of the rat, little or no mechanical instability is observed; twitch contractions are at steady state, albeit with an elevated active diastolic force. Although the amplitude of contraction increased within in vivo heart rates (positive force-frequency response), at frequencies beyond the maximal heart rate (10-30 Hz) a steady decline of contractile amplitude is observed. Not until 30 Hz do the majority of the isolated muscle preparations show mechanical alternans, where strong and weak beats alternate. Interestingly, unlike striated limb skeletal muscle, fusing of twitch contractions did not cause a continuous increase in peak force: at frequencies of 10 Hz and above, systolic force declines with relatively little elevation in diastolic force. Contractile kinetics continued to accelerate, from 1 Hz up to 30 Hz, whereas the relative speed of contraction and relaxation remained closely coupled, reflected by a singular linear relationship between the maximal and minimal derivative of force (dF/dt). We conclude that cardiac muscle can produce mechanically stable steady-state contractions at supra-physiological pacing rates, while these contractions continue to decline in amplitude and increase in diastolic force past maximal heart rate.
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Affiliation(s)
- Jessica L Slabaugh
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, 43210-1218, USA
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41
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Sheikh F, Ouyang K, Campbell SG, Lyon RC, Chuang J, Fitzsimons D, Tangney J, Hidalgo CG, Chung CS, Cheng H, Dalton ND, Gu Y, Kasahara H, Ghassemian M, Omens JH, Peterson KL, Granzier HL, Moss RL, McCulloch AD, Chen J. Mouse and computational models link Mlc2v dephosphorylation to altered myosin kinetics in early cardiac disease. J Clin Invest 2012; 122:1209-21. [PMID: 22426213 DOI: 10.1172/jci61134] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Accepted: 01/18/2012] [Indexed: 11/17/2022] Open
Abstract
Actin-myosin interactions provide the driving force underlying each heartbeat. The current view is that actin-bound regulatory proteins play a dominant role in the activation of calcium-dependent cardiac muscle contraction. In contrast, the relevance and nature of regulation by myosin regulatory proteins (for example, myosin light chain-2 [MLC2]) in cardiac muscle remain poorly understood. By integrating gene-targeted mouse and computational models, we have identified an indispensable role for ventricular Mlc2 (Mlc2v) phosphorylation in regulating cardiac muscle contraction. Cardiac myosin cycling kinetics, which directly control actin-myosin interactions, were directly affected, but surprisingly, Mlc2v phosphorylation also fed back to cooperatively influence calcium-dependent activation of the thin filament. Loss of these mechanisms produced early defects in the rate of cardiac muscle twitch relaxation and ventricular torsion. Strikingly, these defects preceded the left ventricular dysfunction of heart disease and failure in a mouse model with nonphosphorylatable Mlc2v. Thus, there is a direct and early role for Mlc2 phosphorylation in regulating actin-myosin interactions in striated muscle contraction, and dephosphorylation of Mlc2 or loss of these mechanisms can play a critical role in heart failure.
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Affiliation(s)
- Farah Sheikh
- Department of Medicine, UCSD, La Jolla, California 92093-0613C, USA.
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42
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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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43
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Bardswell SC, Cuello F, Kentish JC, Avkiran M. cMyBP-C as a promiscuous substrate: phosphorylation by non-PKA kinases and its potential significance. J Muscle Res Cell Motil 2011; 33:53-60. [PMID: 22089698 DOI: 10.1007/s10974-011-9276-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Accepted: 11/04/2011] [Indexed: 11/26/2022]
Abstract
It is now generally accepted that phosphorylation of cMyBP-C is critically important in maintaining normal cardiac function. Although much of the work to date on phospho-regulation of cMyBP-C has focused on the role of protein kinase A (PKA, also known as cAMP-dependent protein kinase), recent evidence suggests that a number of non-PKA serine/threonine kinases, such as Ca(2+)/calmodulin-dependent protein kinase II, protein kinase C, protein kinase D and the 90-kDa ribosomal S6 kinase are also capable of targeting this key regulatory sarcomeric protein. This article reviews such evidence and proposes a hypothetical role for some of the pertinent signalling pathways in phospho-regulation of cMyBP-C in the setting of heart failure.
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Affiliation(s)
- Sonya C Bardswell
- Cardiovascular Division, King's College London British Heart Foundation Centre of Research Excellence, The Rayne Institute, St Thomas' Hospital, London, UK
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44
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Sarin V, Muthuchamy M, Heaps CL. Ca²⁺ sensitization of cardiac myofilament proteins contributes to exercise training-enhanced myocardial function in a porcine model of chronic occlusion. Am J Physiol Heart Circ Physiol 2011; 301:H1579-87. [PMID: 21856915 DOI: 10.1152/ajpheart.00294.2011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Exercise training has been shown to improve cardiac dysfunction in both patients and animal models of coronary artery disease; however, the underlying cellular and molecular mechanisms have not been completely understood. We hypothesized that exercise training would improve force generation in the myocardium distal to chronic coronary artery occlusion via altered intracellular Ca(2+) concentration ([Ca(2+)](i)) cycling and/or Ca(2+) sensitization of myofilaments. Ameroid occluders were surgically placed around the proximal left circumflex coronary artery of adult female Yucatan pigs. Twenty-two weeks postoperatively, the myocardium was isolated from nonoccluded (left anterior descending artery dependent) and collateral-dependent (formerly left circumflex coronary artery dependent) regions of sedentary (pen confined) and exercise-trained (treadmill run, 5 days/wk for 14 wk) pigs. Force measurements in myocardial strips showed that the percent change in force at stimulation frequencies of 3 and 4 Hz relative to 1 Hz was significantly higher in exercise-trained pigs compared with sedentary pigs. β-Adrenergic stimulation with dobutamine significantly improved force kinetics in myocardial strips of sedentary but not exercise-trained pigs at 1 Hz. Additionally, time to peak and half-decay of intracellular Ca(2+) (340-to-380-nm fluoresence ratio) responses at 1 Hz were significantly decreased in the collateral-dependent region of exercise-trained pigs with no difference in peak [Ca(2+)](i) between groups. Furthermore, the skinned myocardium from exercise-trained pigs showed an increase in Ca(2+) sensitivity compared with sedentary pigs. Immunoblot analysis revealed that the relative levels of cardiac troponin T and β(1)-adrenergic receptors were decreased in hearts from exercise-trained pigs independent of occlusion. Also, the ratio of phosphorylated to total myosin light chain-2, basal phosphorylation levels of cardiac troponin I (Ser(23) and Ser(24)), and cardiac myosin binding protein-C (Ser(282)) were unaltered by occlusion or exercise training. Thus, our data demonstrate that exercise training-enhanced force generation in the nonoccluded and collateral-dependent myocardium was associated with improved Ca(2+) transients, increased Ca(2+) sensitization of myofilament proteins, and decreased expression levels of β(1)-adrenergic receptors and cardiac troponin T.
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Affiliation(s)
- Vandana Sarin
- Michael E. DeBakey Institute for Comparative Cardiovascular Science and Biomedical Devices, Texas A&M University, College Station, Texas 77843, USA
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45
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46
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de Lange WJ, Hegge LF, Grimes AC, Tong CW, Brost TM, Moss RL, Ralphe JC. Neonatal mouse-derived engineered cardiac tissue: a novel model system for studying genetic heart disease. Circ Res 2011; 109:8-19. [PMID: 21566213 PMCID: PMC3123426 DOI: 10.1161/circresaha.111.242354] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Accepted: 05/02/2011] [Indexed: 11/16/2022]
Abstract
RATIONALE Cardiomyocytes cultured in a mechanically active 3-dimensional configuration can be used for studies that correlate contractile performance to cellular physiology. Current engineered cardiac tissue (ECT) models use cells derived from either rat or chick hearts. Development of a murine ECT would provide access to many existing models of cardiac disease and open the possibility of performing targeted genetic manipulation with the ability to directly assess contractile and molecular variables. OBJECTIVE To generate, characterize, and validate mouse ECT with a physiologically relevant model of hypertrophic cardiomyopathy. METHODS AND RESULTS We generated mechanically integrated ECT using isolated neonatal mouse cardiac cells derived from both wild-type and myosin-binding protein C (cMyBP-C)-null mouse hearts. The murine ECTs produced consistent contractile forces that followed the Frank-Starling law and accepted physiological pacing. cMyBP-C-null ECTs showed characteristic acceleration of contraction kinetics. Adenovirus-mediated expression of human cMyBP-C in murine cMyBP-C-null ECT restored contractile properties to levels indistinguishable from those of wild-type ECT. Importantly, the cardiomyocytes used to construct the cMyBP-C(-/-) ECT had yet to undergo the significant hypertrophic remodeling that occurs in vivo. Thus, this murine ECT model reveals a contractile phenotype that is specific to the genetic mutation rather than to secondary remodeling events. CONCLUSIONS Data presented here show mouse ECT to be an efficient and cost-effective platform to study the primary effects of genetic manipulation on cardiac contractile function. This model provides a previously unavailable tool to study specific sarcomeric protein mutations in an intact mammalian muscle system.
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Affiliation(s)
- W J de Lange
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
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47
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Mattera GG, Vanoli E, Martinez V, Luciani M, Falco T, Borsini F. Adrenergic effects on force-frequency relationship: a pivotal role for the cardiac intrinsic systems. Acta Physiol (Oxf) 2011; 202:141-9. [PMID: 21338472 DOI: 10.1111/j.1748-1716.2011.02266.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIM The force-frequency relationship (F-FR) is an important intrinsic regulatory mechanism of cardiac contractility. The involvement of autonomic nervous system in this physiological aspect of cardiac control remains unclear. The aim of the study was to evaluate the role of extrinsic and intrinsic cardiac adrenergic innervations on the heart rate (HR)-related positive inotropic response. METHODS Twenty-four dogs were anesthetized and acutely instrumented to monitor and record ECG, systemic and left ventricular pressures and derivatives, and to pace the heart at 130, 150, 170, 190 and 210 bpm, in order to construct the F-FR curve. Animals were randomly assigned to four groups (n = 6 each): vehicle (V), ganglion-blocked (G-B), β-blocked (β-B) and ganglion-blocked plus β-blocked (G-B + β-B). RESULTS Vehicle treated animals presented the classical F-FR. In the β-B group F-FR was blunted, but never fully suppressed. The G-B treated animals showed a bell-shape response curve of the induced inotropic effect with the zenith at 170 bpm: the first part of the curve resembling the control one, followed by a rapid decline toward baseline value. The co-administration of G-B and β-B agents reversed the contractile response to HR rise with a curve resembling the negative F-FR curve observed in the failing heart. CONCLUSION The F-FR appeared to be constituted by two consecutive mechanisms: first depolarization-rate dependent, and a second catecholamine-dependent. The natural consequence of these observations is that the full expression of F-FR needs an intact adrenergic system.
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Affiliation(s)
- G G Mattera
- Research and Development Sigma-Tau S.p.A., Pomezia, Italy.
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48
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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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49
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Wu X, Chakraborty S, Heaps CL, Davis MJ, Meininger GA, Muthuchamy M. Fibronectin increases the force production of mouse papillary muscles via α5β1 integrin. J Mol Cell Cardiol 2011; 50:203-13. [PMID: 20937283 PMCID: PMC3019265 DOI: 10.1016/j.yjmcc.2010.10.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Revised: 09/30/2010] [Accepted: 10/01/2010] [Indexed: 02/07/2023]
Abstract
The extracellular matrix (ECM) protein-integrin-cytoskeleton axis plays a central role as a mechanotransducing protein assemblage in many cell types. However, how the process of mechanotransduction and the mechanically generated signals arising from this axis affect myofilament function in cardiac muscle are not completely understood. We hypothesize that ECM proteins can regulate cardiac function through integrin binding, and thereby alter the intracellular calcium concentration ([Ca(2+)](i)) and/or modulate myofilament activation processes. Force measurements made in mouse papillary muscle demonstrated that in the presence of the soluble form of the ECM protein, fibronectin (FN), active force was increased significantly by 40% at 1 Hz, 54% at 2 Hz, 35% at 5 Hz and 16% at 9 Hz stimulation frequencies. Furthermore, increased active force in the presence of FN was associated with 12-33% increase in [Ca(2+)](i) and 20-50% increase in active force per unit Ca(2+). A function blocking antibody for α5 integrin prevented the effects of the FN on the changes in force and [Ca(2+)](i), whereas a function blocking α3 integrin antibody did not reverse the effects of FN. The effects of FN were reversed by an L-type Ca(2+) channel blocker, verapamil or PKA inhibitor. Freshly isolated cardiomyocytes exhibited a 39% increase in contraction force and a 36% increase in L-type Ca(2+) current in the presence of FN. Fibers treated with FN showed a significant increase in the phosphorylation of phospholamban; however, the phosphorylation of troponin I was unchanged. These results demonstrate that FN acts via α5β1 integrin to increase force production in myocardium and that this effect is partly mediated by increases in [Ca(2+)](i) and Ca(2+) sensitivity, PKA activation and phosphorylation of phospholamban.
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Affiliation(s)
- Xin Wu
- Department of Systems Biology and Translational Medicine, Texas A&M Health Science Center College of Medicine, College Station, TX 77843, USA
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50
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Boontje NM, Merkus D, Zaremba R, Versteilen A, de Waard MC, Mearini G, de Beer VJ, Carrier L, Walker LA, Niessen HWM, Dobrev D, Stienen GJM, Duncker DJ, van der Velden J. Enhanced myofilament responsiveness upon β-adrenergic stimulation in post-infarct remodeled myocardium. J Mol Cell Cardiol 2010; 50:487-99. [PMID: 21156182 DOI: 10.1016/j.yjmcc.2010.12.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2010] [Revised: 11/19/2010] [Accepted: 12/03/2010] [Indexed: 12/12/2022]
Abstract
Previously we showed that left ventricular (LV) responsiveness to exercise-induced increases in noradrenaline was blunted in pigs with a recent myocardial infarction (MI) [van der Velden et al. Circ Res. 2004], consistent with perturbed β-adrenergic receptor (β-AR) signaling. Here we tested the hypothesis that abnormalities at the myofilament level underlie impaired LV responsiveness to catecholamines in MI. Myofilament function and protein composition were studied in remote LV biopsies taken at baseline and during dobutamine stimulation 3 weeks after MI or sham. Single permeabilized cardiomyocytes demonstrated reduced maximal force (F(max)) and higher Ca(2+)-sensitivity in MI compared to sham. F(max) did not change during dobutamine infusion in sham, but markedly increased in MI. Moreover, the dobutamine-induced decrease in Ca(2+)-sensitivity was significantly larger in MI than sham. Baseline phosphorylation assessed by phosphostaining of β-AR target proteins myosin binding protein C (cMyBP-C) and troponin I (cTnI) in MI and sham was the same. However, the dobutamine-induced increase in overall cTnI phosphorylation and cTnI phosphorylation at protein kinase A (PKA)-sites (Ser23/24) was less in MI compared to sham. In contrast, the dobutamine-induced phosphorylation of cMyBP-C at Ser282 was preserved in MI, and coincided with increased autophosphorylation (at Thr282) of the cytosolic Ca(2+)-dependent calmodulin kinase II (CaMKII-δC). In conclusion, in post-infarct remodeled myocardium myofilament responsiveness to dobutamine is significantly enhanced despite the lower increase in PKA-mediated phosphorylation of cTnI. The increased myofilament responsiveness in MI may depend on the preserved cMyBP-C phosphorylation possibly resulting from increased CaMKII-δC activity and may help to maintain proper diastolic performance during exercise.
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Affiliation(s)
- Nicky M Boontje
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands
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