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Burnham HV, Cizauskas HE, Barefield DY. Fine tuning contractility: atrial sarcomere function in health and disease. Am J Physiol Heart Circ Physiol 2024; 326:H568-H583. [PMID: 38156887 PMCID: PMC11221815 DOI: 10.1152/ajpheart.00252.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 12/20/2023] [Accepted: 12/21/2023] [Indexed: 01/03/2024]
Abstract
The molecular mechanisms of sarcomere proteins underlie the contractile function of the heart. Although our understanding of the sarcomere has grown tremendously, the focus has been on ventricular sarcomere isoforms due to the critical role of the ventricle in health and disease. However, atrial-specific or -enriched myofilament protein isoforms, as well as isoforms that become expressed in disease, provide insight into ways this complex molecular machine is fine-tuned. Here, we explore how atrial-enriched sarcomere protein composition modulates contractile function to fulfill the physiological requirements of atrial function. We review how atrial dysfunction negatively affects the ventricle and the many cardiovascular diseases that have atrial dysfunction as a comorbidity. We also cover the pathophysiology of mutations in atrial-enriched contractile proteins and how they can cause primary atrial myopathies. Finally, we explore what is known about contractile function in various forms of atrial fibrillation. The differences in atrial function in health and disease underscore the importance of better studying atrial contractility, especially as therapeutics currently in development to modulate cardiac contractility may have different effects on atrial sarcomere function.
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Affiliation(s)
- Hope V Burnham
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, United States
| | - Hannah E Cizauskas
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, United States
| | - David Y Barefield
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, United States
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2
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Bening C, Genser B, Keller D, Müller-Altrock S, Radakovic D, Penov K, Hassan M, Aleksic I, Leyh R, Madrahimov N. Impact of estradiol, testosterone and their ratio on left and right auricular myofilament function in male and female patients undergoing coronary artery bypass grafting. BMC Cardiovasc Disord 2023; 23:538. [PMID: 37925416 PMCID: PMC10625250 DOI: 10.1186/s12872-023-03582-4] [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: 12/08/2022] [Accepted: 10/26/2023] [Indexed: 11/06/2023] Open
Abstract
BACKGROUND The impact of sex hormones on right and left auricular contractile apparatus function is largely unknown. We evaluated the impact of sex hormones on left and right heart contractility at the level of myocardial filaments harvested from left and right auricles during elective coronary artery bypass surgery. METHODS 150 patients (132 male; 18 female) were enrolled. Preoperative testosterone and estradiol levels were measured with Immunoassay. Calcium induced force measurements were performed with left- and right auricular myofilaments in a skinned fiber model. Correlation analysis was used for comparison of force values and levels of sex hormones and their ratio. RESULTS Low testosterone was associated with higher top force values in right-sided myofilaments but not in left-sided myofilaments for both sexes (p = 0.000 in males, p = 0.001 in females). Low estradiol levels were associated with higher top force values in right-sided myofilaments (p 0.000) in females and only borderline significantly associated with higher top force values in males (p 0.056). In females, low estradiol levels correlated with higher top force values in left sided myofilaments (p 0.000). In males, higher Estradiol/Testosterone ratio (E/T ratio) was only associated with higher top force values from right auricular myofilaments (p 0.04) In contrast, in females higher E/T ratio was associated with lower right auricular myofilament top force values (p 0.03) and higher top force values in left-sided myofilaments (p 0.000). CONCLUSIONS This study shows that patients' comorbidities influence left and right sided contractility and may blur results concerning influence of sex hormones if not eliminated. A sex hormone dependent influence is obvious with different effects on the left and right ventricle. The E/T ratio and its impact on myofilament top force showed divergent results between genders, and may partially explain gender differences in patients with cardiovascular disease.
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Affiliation(s)
- C Bening
- Department of Thoracic and Cardiovascular Surgery, University Hospital Wuerzburg Zentrum Operative Medizin, Oberduerrbacherstr. 6, 97080, Wuerzburg, Germany.
| | - B Genser
- Medical Faculty Mannheim, Center for Preventive Medicine, Heidelberg University, Digital Health Baden-Württemberg (CPD-BW), Heidelberg , Germany
| | - D Keller
- Department of Thoracic and Cardiovascular Surgery, University Hospital Wuerzburg Zentrum Operative Medizin, Oberduerrbacherstr. 6, 97080, Wuerzburg, Germany
| | - S Müller-Altrock
- Department of Thoracic and Cardiovascular Surgery, University Hospital Wuerzburg Zentrum Operative Medizin, Oberduerrbacherstr. 6, 97080, Wuerzburg, Germany
| | - D Radakovic
- Department of Thoracic and Cardiovascular Surgery, University Hospital Wuerzburg Zentrum Operative Medizin, Oberduerrbacherstr. 6, 97080, Wuerzburg, Germany
| | - K Penov
- Department of Thoracic and Cardiovascular Surgery, University Hospital Wuerzburg Zentrum Operative Medizin, Oberduerrbacherstr. 6, 97080, Wuerzburg, Germany
| | - M Hassan
- Department of Thoracic and Cardiovascular Surgery, University Hospital Wuerzburg Zentrum Operative Medizin, Oberduerrbacherstr. 6, 97080, Wuerzburg, Germany
| | - I Aleksic
- Department of Thoracic and Cardiovascular Surgery, University Hospital Wuerzburg Zentrum Operative Medizin, Oberduerrbacherstr. 6, 97080, Wuerzburg, Germany
| | - R Leyh
- Department of Thoracic and Cardiovascular Surgery, University Hospital Wuerzburg Zentrum Operative Medizin, Oberduerrbacherstr. 6, 97080, Wuerzburg, Germany
| | - N Madrahimov
- Department of Thoracic and Cardiovascular Surgery, University Hospital Wuerzburg Zentrum Operative Medizin, Oberduerrbacherstr. 6, 97080, Wuerzburg, Germany
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Perike S, Gonzalez-Gonzalez FJ, Abu-Taha I, Damen FW, Hanft LM, Lizama KS, Aboonabi A, Capote AE, Aguilar-Sanchez Y, Levin B, Han Z, Sridhar A, Grand J, Martin J, Akar JG, Warren CM, Solaro RJ, Sang-Ging O, Darbar D, McDonald KS, Goergen CJ, Wolska BM, Dobrev D, Wehrens XH, McCauley MD. PPP1R12C Promotes Atrial Hypocontractility in Atrial Fibrillation. Circ Res 2023; 133:758-771. [PMID: 37737016 PMCID: PMC10616980 DOI: 10.1161/circresaha.123.322516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 09/14/2023] [Indexed: 09/23/2023]
Abstract
BACKGROUND Atrial fibrillation (AF)-the most common sustained cardiac arrhythmia-increases thromboembolic stroke risk 5-fold. Although atrial hypocontractility contributes to stroke risk in AF, the molecular mechanisms reducing myofilament contractile function remain unknown. We tested the hypothesis that increased expression of PPP1R12C (protein phosphatase 1 regulatory subunit 12C)-the PP1 (protein phosphatase 1) regulatory subunit targeting MLC2a (atrial myosin light chain 2)-causes hypophosphorylation of MLC2a and results in atrial hypocontractility. METHODS Right atrial appendage tissues were isolated from human patients with AF versus sinus rhythm controls. Western blots, coimmunoprecipitation, and phosphorylation studies were performed to examine how the PP1c (PP1 catalytic subunit)-PPP1R12C interaction causes MLC2a dephosphorylation. In vitro studies of pharmacological MRCK (myotonic dystrophy kinase-related Cdc42-binding kinase) inhibitor (BDP5290) in atrial HL-1 cells were performed to evaluate PP1 holoenzyme activity on MLC2a. Cardiac-specific lentiviral PPP1R12C overexpression was performed in mice to evaluate atrial remodeling with atrial cell shortening assays, echocardiography, and AF inducibility with electrophysiology studies. RESULTS In human patients with AF, PPP1R12C expression was increased 2-fold versus sinus rhythm controls (P=2.0×10-2; n=12 and 12 in each group) with >40% reduction in MLC2a phosphorylation (P=1.4×10-6; n=12 and 12 in each group). PPP1R12C-PP1c binding and PPP1R12C-MLC2a binding were significantly increased in AF (P=2.9×10-2 and 6.7×10-3, respectively; n=8 and 8 in each group). In vitro studies utilizing drug BDP5290, which inhibits T560-PPP1R12C phosphorylation, demonstrated increased PPP1R12C binding with both PP1c and MLC2a and dephosphorylation of MLC2a. Mice treated with lentiviral PPP1R12C vector demonstrated a 150% increase in left atrial size versus controls (P=5.0×10-6; n=12, 8, and 12), with reduced atrial strain and atrial ejection fraction. Pacing-induced AF in mice treated with lentiviral PPP1R12C vector was significantly higher than in controls (P=1.8×10-2 and 4.1×10-2, respectively; n=6, 6, and 5). CONCLUSIONS Patients with AF exhibit increased levels of PPP1R12C protein compared with controls. PPP1R12C overexpression in mice increases PP1c targeting to MLC2a and causes MLC2a dephosphorylation, which reduces atrial contractility and increases AF inducibility. These findings suggest that PP1 regulation of sarcomere function at MLC2a is a key determinant of atrial contractility in AF.
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Affiliation(s)
- Srikanth Perike
- Division of Cardiology, Department of Medicine, College of Medicine, University of Illinois at Chicago
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, University of Illinois at Chicago
- Jesse Brown VA Medical Center, Chicago, IL
| | - Francisco J. Gonzalez-Gonzalez
- Division of Cardiology, Department of Medicine, College of Medicine, University of Illinois at Chicago
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, University of Illinois at Chicago
- Jesse Brown VA Medical Center, Chicago, IL
| | - Issam Abu-Taha
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Germany
| | - Frederick W. Damen
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN
| | - Laurin M. Hanft
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia
| | - Ken S. Lizama
- Division of Cardiology, Department of Medicine, College of Medicine, University of Illinois at Chicago
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, University of Illinois at Chicago
- Jesse Brown VA Medical Center, Chicago, IL
| | - Anahita Aboonabi
- Division of Cardiology, Department of Medicine, College of Medicine, University of Illinois at Chicago
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, University of Illinois at Chicago
| | - Andrielle E. Capote
- Division of Cardiology, Department of Medicine, College of Medicine, University of Illinois at Chicago
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, University of Illinois at Chicago
| | - Yuriana Aguilar-Sanchez
- Department of Integrative Physiology and The Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX
| | | | - Zhenbo Han
- Department of Pharmacology and Regenerative Medicine, College of Medicine,University of Illinois at Chicago
| | - Arvind Sridhar
- Division of Cardiology, Department of Medicine, College of Medicine, University of Illinois at Chicago
| | - Jacob Grand
- Division of Cardiology, Department of Medicine, College of Medicine, University of Illinois at Chicago
| | | | | | - Chad M. Warren
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, University of Illinois at Chicago
| | - R. John Solaro
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, University of Illinois at Chicago
| | - Ong Sang-Ging
- Division of Cardiology, Department of Medicine, College of Medicine, University of Illinois at Chicago
- Department of Pharmacology and Regenerative Medicine, College of Medicine,University of Illinois at Chicago
| | - Dawood Darbar
- Division of Cardiology, Department of Medicine, College of Medicine, University of Illinois at Chicago
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, University of Illinois at Chicago
- Jesse Brown VA Medical Center, Chicago, IL
| | - Kerry S. McDonald
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia
| | - Craig J. Goergen
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN
| | - Beata M. Wolska
- Division of Cardiology, Department of Medicine, College of Medicine, University of Illinois at Chicago
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, University of Illinois at Chicago
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Germany
- Department of Integrative Physiology and The Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX
- Department of Medicine, Montréal Heart Institute and Université de Montréal, Montréal, Canada
| | - Xander H.T. Wehrens
- Department of Integrative Physiology and The Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX
| | - Mark D. McCauley
- Division of Cardiology, Department of Medicine, College of Medicine, University of Illinois at Chicago
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, University of Illinois at Chicago
- Jesse Brown VA Medical Center, Chicago, IL
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Deissler PM, Tran KL, Falk V, Pieske B, Grubitzsch H, Primessnig U, Heinzel FR. Functional reserve and contractile phenotype of atrial myocardium from patients with atrial remodeling without and with atrial fibrillation. Am J Physiol Heart Circ Physiol 2023; 325:H729-H738. [PMID: 37594484 DOI: 10.1152/ajpheart.00355.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 07/26/2023] [Accepted: 08/04/2023] [Indexed: 08/19/2023]
Abstract
Atrial contractility and functional reserve in atrial remodeling (AR) without (AR/-AF) or with atrial fibrillation (AR/+AF) are not well characterized. In this study, functional measurements were performed in right atrial muscle strips (n = 71) obtained from patients (N = 22) undergoing routine cardiac surgery with either no AR [left atrial (LA) diameter < 40 mm and no history of AF (hAF)], AR/-AF (LA diameter ≥ 40 mm, no hAF), or AR/+AF (hAF and LA diameter ≥ 40 mm or LAEF < 45%). AR/-AF and AR/+AF were associated with a prolongation of half-time-to-peak (HTTP, P < 0.001) and time-to-peak (TTP) contraction (P < 0.01) when compared with no AR. This effect was seen at baseline and during β-adrenergic stimulation with isoproterenol (Iso). Early relaxation assessed by half-relaxation time (HRT) was prolonged in AR/-AF (P = 0.03) but not in AR/+AF when compared with no AR at baseline, but this delay in relaxation in AR/-AF was attenuated with Iso. Late relaxation (τ) did not differ between AR/-AF and no AR but was consistently shorter in AR/+AF than no AR before (P = 0.04) and during Iso (P = 0.01), indicating accelerated late relaxation in AR/+AF. Relative force increase during Iso was higher (P = 0.01) and more dispersed (P = 0.047) in patients with AR/+AF. Relative adrenergic response was unaltered in the myocardium of patients with AR/-AF and AR/+AF. In conclusion, AR/-AF and AR/+AF are associated with changes in myocardial inotropic reserve and contractility. The changes are particularly pronounced in patients with AR/+AF, suggesting that the progression from AR/-AF to AR/+AF is associated with progressive alterations in atrial function that may contribute to arrhythmogenesis.NEW & NOTEWORTHY Mechanical alterations in atrial remodeling without (AR/-AF) and with atrial fibrillation (AR/+AF) have not been studied in detail in human atrial tissue preparations. To our knowledge, this is the first study to compare the mechanical phenotype and inotropic reserve in human atrial myocardial preparations from patients with no atrial remodeling, AR/-AF, and AR/+AF. We identify specific patterns of contractile dysfunction and heterogeneity for both, AR/-AF and AR/+AF, indicating the progression of atrial disease.
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Affiliation(s)
- Peter M Deissler
- Department of Cardiology, Angiology and Intensive Care Medicine, Deutsches Herzzentrum der Charité, Berlin, Germany
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Berlin, Germany
- Department of Cardiology, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University Medical Center+, Maastricht, The Netherlands
| | - Khai Liem Tran
- Department of Cardiology, Angiology and Intensive Care Medicine, Deutsches Herzzentrum der Charité, Berlin, Germany
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Berlin, Germany
| | - Volkmar Falk
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Berlin, Germany
- Department of Cardiothoracic and Vascular Surgery, Deutsches Herzzentrum der Charité, Berlin, Germany
| | | | - Herko Grubitzsch
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Berlin, Germany
- Department of Cardiothoracic and Vascular Surgery, Deutsches Herzzentrum der Charité, Berlin, Germany
| | - Uwe Primessnig
- Department of Cardiology, Angiology and Intensive Care Medicine, Deutsches Herzzentrum der Charité, Berlin, Germany
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
| | - Frank R Heinzel
- Department of Cardiology, Angiology and Intensive Care Medicine, Deutsches Herzzentrum der Charité, Berlin, Germany
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
- 2. Medizinische Klinik-Kardiologie, Angiologie, Intensivmedizin, Städtisches Klinikum Dresden, Dresden, Germany
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5
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Wessels JN, van Wezenbeek J, de Rover J, Smal R, Llucià-Valldeperas A, Celant LR, Marcus JT, Meijboom LJ, Groeneveldt JA, Oosterveer FPT, Winkelman TA, Niessen HWM, Goumans MJ, Bogaard HJ, Noordegraaf AV, Strijkers GJ, Handoko ML, Westerhof BE, de Man FS. Right Atrial Adaptation to Precapillary Pulmonary Hypertension: Pressure-Volume, Cardiomyocyte, and Histological Analysis. J Am Coll Cardiol 2023; 82:704-717. [PMID: 37587582 DOI: 10.1016/j.jacc.2023.05.063] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 05/25/2023] [Accepted: 05/31/2023] [Indexed: 08/18/2023]
Abstract
BACKGROUND Precapillary pulmonary hypertension (precPH) patients have altered right atrial (RA) function and right ventricular (RV) diastolic stiffness. OBJECTIVES This study aimed to investigate RA function using pressure-volume (PV) loops, isolated cardiomyocyte, and histological analyses. METHODS RA PV loops were constructed in control subjects (n = 9) and precPH patients (n = 27) using magnetic resonance and catheterization data. RA stiffness (pressure rise during atrial filling) and right atrioventricular coupling index (RA minimal volume / RV end-diastolic volume) were compared in a larger cohort of patients with moderate (n = 39) or severe (n = 41) RV diastolic stiffness. Cardiomyocytes were isolated from RA tissue collected from control subjects (n = 6) and precPH patients (n = 9) undergoing surgery. Autopsy material was collected from control subjects (n = 6) and precPH patients (n = 4) to study RA hypertrophy, capillarization, and fibrosis. RESULTS RA PV loops showed 3 RA cardiac phases (reservoir, passive emptying, and contraction) with dilatation and elevated pressure in precPH. PrecPH patients with severe RV diastolic stiffness had increased RA stiffness and worse right atrioventricular coupling index. Cardiomyocyte cross-sectional area was increased 2- to 3-fold in precPH, but active tension generated by the sarcomeres was unaltered. There was no increase in passive tension of the cardiomyocytes, but end-stage precPH showed reduced number of capillaries per mm2 accompanied by interstitial and perivascular fibrosis. CONCLUSIONS RA PV loops show increased RA stiffness and suggest atrioventricular uncoupling in patients with severe RV diastolic stiffness. Isolated RA cardiomyocytes of precPH patients are hypertrophied, without intrinsic sarcomeric changes. In end-stage precPH, reduced capillary density is accompanied by interstitial and perivascular fibrosis.
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Affiliation(s)
- Jeroen N Wessels
- PHEniX Laboratory, Department of Pulmonary Medicine, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam, the Netherlands; Pulmonary Hypertension and Thrombosis, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands
| | - Jessie van Wezenbeek
- PHEniX Laboratory, Department of Pulmonary Medicine, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam, the Netherlands; Pulmonary Hypertension and Thrombosis, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands
| | - Jari de Rover
- Cardiovascular and Respiratory Physiology, Faculty of Science and Technology, Technical Medical Centre, University of Twente, Enschede, the Netherlands
| | - Rowan Smal
- PHEniX Laboratory, Department of Pulmonary Medicine, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam, the Netherlands; Pulmonary Hypertension and Thrombosis, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands
| | - Aida Llucià-Valldeperas
- PHEniX Laboratory, Department of Pulmonary Medicine, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam, the Netherlands; Pulmonary Hypertension and Thrombosis, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands
| | - Lucas R Celant
- PHEniX Laboratory, Department of Pulmonary Medicine, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam, the Netherlands; Pulmonary Hypertension and Thrombosis, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands
| | - J Tim Marcus
- Pulmonary Hypertension and Thrombosis, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands; Department of Radiology and Nuclear Medicine, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - Lilian J Meijboom
- Pulmonary Hypertension and Thrombosis, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands; Department of Radiology and Nuclear Medicine, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - Joanne A Groeneveldt
- PHEniX Laboratory, Department of Pulmonary Medicine, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam, the Netherlands; Pulmonary Hypertension and Thrombosis, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands
| | - Frank P T Oosterveer
- PHEniX Laboratory, Department of Pulmonary Medicine, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam, the Netherlands; Pulmonary Hypertension and Thrombosis, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands
| | - Toon A Winkelman
- Department of Cardiothoracic Surgery, Amsterdam UMC location University of Amsterdam, Amsterdam, the Netherlands
| | - Hans W M Niessen
- Department of Pathology, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - Marie-José Goumans
- Department of Cell and Chemical Biology, Leiden UMC, Leiden, the Netherlands
| | - Harm Jan Bogaard
- PHEniX Laboratory, Department of Pulmonary Medicine, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam, the Netherlands; Pulmonary Hypertension and Thrombosis, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands
| | - Anton Vonk Noordegraaf
- PHEniX Laboratory, Department of Pulmonary Medicine, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam, the Netherlands; Pulmonary Hypertension and Thrombosis, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands
| | - Gustav J Strijkers
- Department of Biomedical Engineering and Physics, Amsterdam UMC location University of Amsterdam, Amsterdam, the Netherlands
| | - M Louis Handoko
- Pulmonary Hypertension and Thrombosis, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands; Department of Cardiology, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - Berend E Westerhof
- PHEniX Laboratory, Department of Pulmonary Medicine, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam, the Netherlands; Pulmonary Hypertension and Thrombosis, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands
| | - Frances S de Man
- PHEniX Laboratory, Department of Pulmonary Medicine, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam, the Netherlands; Pulmonary Hypertension and Thrombosis, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands.
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6
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Butova X, Myachina T, Simonova R, Kochurova A, Mukhlynina E, Kopylova G, Shchepkin D, Khokhlova A. The inter-chamber differences in the contractile function between left and right atrial cardiomyocytes in atrial fibrillation in rats. Front Cardiovasc Med 2023; 10:1203093. [PMID: 37608813 PMCID: PMC10440706 DOI: 10.3389/fcvm.2023.1203093] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 07/24/2023] [Indexed: 08/24/2023] Open
Abstract
Introduction The left and right atria (LA, RA) work under different mechanical and metabolic environments that may cause an intrinsic inter-chamber diversity in structure and functional properties between atrial cardiomyocytes (CM) in norm and provoke their different responsiveness to pathological conditions. In this study, we assessed a LA vs. RA difference in CM contractility in paroxysmal atrial fibrillation (AF) and underlying mechanisms. Methods We investigated the contractile function of single isolated CM from LA and RA using a 7-day acetylcholine (ACh)-CaCl2 AF model in rats. We compared auxotonic force, sarcomere length dynamics, cytosolic calcium ([Ca2+]i) transients, intracellular ROS and NO production in LA and RA CM, and analyzed the phosphorylation levels of contractile proteins and actin-myosin interaction using an in vitro motility assay. Results AF resulted in more prominent structural and functional changes in LA myocardium, reducing sarcomere shortening amplitude, and velocity of sarcomere relengthening in mechanically non-loaded LA CM, which was associated with the increased ROS production, decreased NO production, reduced myofibrillar content, and decreased phosphorylation of cardiac myosin binding protein C and troponin I. However, in mechanically loaded CM, AF depressed the auxotonic force amplitude and kinetics in RA CM, while force characteristics were preserved in LA CM. Discussion Thus, inter-atrial differences are increased in paroxysmal AF and affected by the mechanical load that may contribute to the maintenance and progression of AF.
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Affiliation(s)
- Xenia Butova
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg, Russian Federation
| | - Tatiana Myachina
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg, Russian Federation
| | - Raisa Simonova
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg, Russian Federation
| | - Anastasia Kochurova
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg, Russian Federation
| | - Elena Mukhlynina
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg, Russian Federation
- Institute of Natural Sciences and Mathematics, Ural Federal University, Yekaterinburg, Russian Federation
| | - Galina Kopylova
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg, Russian Federation
| | - Daniil Shchepkin
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg, Russian Federation
- Institute of Natural Sciences and Mathematics, Ural Federal University, Yekaterinburg, Russian Federation
| | - Anastasia Khokhlova
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg, Russian Federation
- Institute of Physics and Technology, Ural Federal University, Yekaterinburg, Russian Federation
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7
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Perike S, Gonzalez-Gonzalez FJ, Abu-Taha I, Damen FW, Lizama KS, Aboonabi A, Capote AE, Aguilar-Sanchez Y, Levin B, Han Z, Sridhar A, Grand J, Martin J, Akar JG, Warren CM, Solaro RJ, Ong SG, Darbar D, Goergen CJ, Wolska BM, Dobrev D, Wehrens XHT, McCauley MD. Myosin Light Chain Dephosphorylation by PPP1R12C Promotes Atrial Hypocontractility in Atrial Fibrillation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.19.537590. [PMID: 37131731 PMCID: PMC10153354 DOI: 10.1101/2023.04.19.537590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Background Atrial fibrillation (AF), the most common sustained cardiac arrhythmia, increases thromboembolic stroke risk five-fold. Although atrial hypocontractility contributes to stroke risk in AF, the molecular mechanisms reducing myofilament contractile function remain unknown. We tested the hypothesis that increased expression of PPP1R12C, the PP1 regulatory subunit targeting atrial myosin light chain 2 (MLC2a), causes hypophosphorylation of MLC2a and results in atrial hypocontractility. Methods Right atrial appendage tissues were isolated from human AF patients versus sinus rhythm (SR) controls. Western blots, co-immunoprecipitation, and phosphorylation studies were performed to examine how the PP1c-PPP1R12C interaction causes MLC2a de-phosphorylation. In vitro studies of pharmacologic MRCK inhibitor (BDP5290) in atrial HL-1 cells were performed to evaluate PP1 holoenzyme activity on MLC2a. Cardiac-specific lentiviral PPP1R12C overexpression was performed in mice to evaluate atrial remodeling with atrial cell shortening assays, echocardiography, and AF inducibility with EP studies. Results In human patients with AF, PPP1R12C expression was increased two-fold versus SR controls ( P =2.0×10 -2 , n=12,12 in each group) with > 40% reduction in MLC2a phosphorylation ( P =1.4×10 -6 , n=12,12 in each group). PPP1R12C-PP1c binding and PPP1R12C-MLC2a binding were significantly increased in AF ( P =2.9×10 -2 and 6.7×10 -3 respectively, n=8,8 in each group). In vitro studies utilizing drug BDP5290, which inhibits T560-PPP1R12C phosphorylation, demonstrated increased PPP1R12C binding with both PP1c and MLC2a, and dephosphorylation of MLC2a. Lenti-12C mice demonstrated a 150% increase in LA size versus controls ( P =5.0×10 -6 , n=12,8,12), with reduced atrial strain and atrial ejection fraction. Pacing-induced AF in Lenti-12C mice was significantly higher than controls ( P =1.8×10 -2 and 4.1×10 -2 respectively, n= 6,6,5). Conclusions AF patients exhibit increased levels of PPP1R12C protein compared to controls. PPP1R12C overexpression in mice increases PP1c targeting to MLC2a and causes MLC2a dephosphorylation, which reduces atrial contractility and increases AF inducibility. These findings suggest that PP1 regulation of sarcomere function at MLC2a is a key determinant of atrial contractility in AF.
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8
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Alpha and beta myosin isoforms and human atrial and ventricular contraction. Cell Mol Life Sci 2021; 78:7309-7337. [PMID: 34704115 PMCID: PMC8629898 DOI: 10.1007/s00018-021-03971-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 10/03/2021] [Accepted: 10/08/2021] [Indexed: 01/15/2023]
Abstract
Human atrial and ventricular contractions have distinct mechanical characteristics including speed of contraction, volume of blood delivered and the range of pressure generated. Notably, the ventricle expresses predominantly β-cardiac myosin while the atrium expresses mostly the α-isoform. In recent years exploration of the properties of pure α- & β-myosin isoforms have been possible in solution, in isolated myocytes and myofibrils. This allows us to consider the extent to which the atrial vs ventricular mechanical characteristics are defined by the myosin isoform expressed, and how the isoform properties are matched to their physiological roles. To do this we Outline the essential feature of atrial and ventricular contraction; Explore the molecular structural and functional characteristics of the two myosin isoforms; Describe the contractile behaviour of myocytes and myofibrils expressing a single myosin isoform; Finally we outline the outstanding problems in defining the differences between the atria and ventricles. This allowed us consider what features of contraction can and cannot be ascribed to the myosin isoforms present in the atria and ventricles.
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9
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Lu Y, Chen Y, Lin Y, Chen S, Chen Y. Mechanoelectrical feedback in pulmonary vein arrhythmogenesis: Clinical challenges and therapeutic opportunities. J Arrhythm 2020; 36:608-614. [PMID: 32782628 PMCID: PMC7411213 DOI: 10.1002/joa3.12391] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 05/28/2020] [Accepted: 06/04/2020] [Indexed: 12/24/2022] Open
Abstract
Mechanoelectrical feedback is an important factor in the pathophysiology of atrial fibrillation (AF). Ectopic electrical activity originating from pulmonary vein (PV) myocardial sleeves has been found to trigger and maintain paroxysmal AF. Dilated PVs by high stretching force may activate mechanoelectrical feedback, which induces calcium overload and produces afterdepolarization. These results, in turn, increase PV arrhythmogenesis and contribute to initiation of AF. Paracrine factors, effectors of the renin-angiotensin system, membranous channels, or cytoskeleton of PV myocytes may modulate PV arrhythmogenesis directly through mechanoelectrical feedback or indirectly through endocardial/myocardial cross-talk. The purpose of this review is to present laboratory and translational relevance of mechanoelectrical feedback in PV arrhythmogenesis. Targeting mechanoelectrical feedback in PV arrhythmogenesis may shed light on potential opportunities and clinical concerns of AF treatment.
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Affiliation(s)
- Yen‐Yu Lu
- Division of CardiologyDepartment of Internal MedicineSijhih Cathay General HospitalNew Taipei CityTaiwan
- School of MedicineFu‐Jen Catholic UniversityNew Taipei CityTaiwan
| | - Yao‐Chang Chen
- Department of Biomedical Engineering and Institute of PhysiologyNational Defense Medical CenterTaipeiTaiwan
| | - Yung‐Kuo Lin
- Division of Cardiovascular MedicineDepartment of Internal MedicineWan Fang HospitalTaipei Medical UniversityTaipeiTaiwan
- Cardiovacular Research CenterWan Fang HospitalTaipei Medical UniversityTaipeiTaiwan
| | - Shih‐Ann Chen
- Heart Rhythm Center and Division of CardiologyDepartment of MedicineTaipei Veterans General HospitalTaipeiTaiwan
| | - Yi‐Jen Chen
- Division of Cardiovascular MedicineDepartment of Internal MedicineWan Fang HospitalTaipei Medical UniversityTaipeiTaiwan
- Cardiovacular Research CenterWan Fang HospitalTaipei Medical UniversityTaipeiTaiwan
- Graduate Institute of Clinical MedicineCollege of MedicineTaipei Medical UniversityTaipeiTaiwan
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10
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Bektik E, Cowan DB, Wang DZ. Long Non-Coding RNAs in Atrial Fibrillation: Pluripotent Stem Cell-Derived Cardiomyocytes as a Model System. Int J Mol Sci 2020; 21:ijms21155424. [PMID: 32751460 PMCID: PMC7432754 DOI: 10.3390/ijms21155424] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 07/27/2020] [Accepted: 07/28/2020] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation (AF) is a type of sustained arrhythmia in humans often characterized by devastating alterations to the cardiac conduction system as well as the structure of the atria. AF can lead to decreased cardiac function, heart failure, and other complications. Long non-coding RNAs (lncRNAs) have been shown to play important roles in the cardiovascular system, including AF; however, a large group of lncRNAs is not conserved between mouse and human. Furthermore, AF has complex networks showing variations in mechanisms in different species, making it challenging to utilize conventional animal models to investigate the functional roles and potential therapeutic benefits of lncRNAs for AF. Fortunately, pluripotent stem cell (PSC)-derived cardiomyocytes (CMs) offer a reliable platform to study lncRNA functions in AF because of certain electrophysiological and molecular similarities with native human CMs. In this review, we first summarize the broad aspects of lncRNAs in various heart disease settings, then focus on their potential roles in AF development and pathophysiology. We also discuss current uses of PSCs in AF research and describe how these studies could be developed into novel therapeutics for AF and other cardiovascular diseases.
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Affiliation(s)
- Emre Bektik
- Department of Cardiology, Boston Children’s Hospital, Harvard Medical School, 300 Longwood, Boston, MA 02115, USA; (E.B.); (D.B.C.)
| | - Douglas B. Cowan
- Department of Cardiology, Boston Children’s Hospital, Harvard Medical School, 300 Longwood, Boston, MA 02115, USA; (E.B.); (D.B.C.)
| | - Da-Zhi Wang
- Department of Cardiology, Boston Children’s Hospital, Harvard Medical School, 300 Longwood, Boston, MA 02115, USA; (E.B.); (D.B.C.)
- Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
- Correspondence:
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Cardiomyocyte calcium handling in health and disease: Insights from in vitro and in silico studies. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 157:54-75. [PMID: 32188566 DOI: 10.1016/j.pbiomolbio.2020.02.008] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 12/31/2019] [Accepted: 02/29/2020] [Indexed: 02/07/2023]
Abstract
Calcium (Ca2+) plays a central role in cardiomyocyte excitation-contraction coupling. To ensure an optimal electrical impulse propagation and cardiac contraction, Ca2+ levels are regulated by a variety of Ca2+-handling proteins. In turn, Ca2+ modulates numerous electrophysiological processes. Accordingly, Ca2+-handling abnormalities can promote cardiac arrhythmias via various mechanisms, including the promotion of afterdepolarizations, ion-channel modulation and structural remodeling. In the last 30 years, significant improvements have been made in the computational modeling of cardiomyocyte Ca2+ handling under physiological and pathological conditions. However, numerous questions involving the Ca2+-dependent regulation of different macromolecular complexes, cross-talk between Ca2+-dependent regulatory pathways operating over a wide range of time scales, and bidirectional interactions between electrophysiology and mechanics remain to be addressed by in vitro and in silico studies. A better understanding of disease-specific Ca2+-dependent proarrhythmic mechanisms may facilitate the development of improved therapeutic strategies. In this review, we describe the fundamental mechanisms of cardiomyocyte Ca2+ handling in health and disease, and provide an overview of currently available computational models for cardiomyocyte Ca2+ handling. Finally, we discuss important uncertainties and open questions about cardiomyocyte Ca2+ handling and highlight how synergy between in vitro and in silico studies may help to answer several of these issues.
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12
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Sarcomeric Gene Variants and Their Role with Left Ventricular Dysfunction in Background of Coronary Artery Disease. Biomolecules 2020; 10:biom10030442. [PMID: 32178433 PMCID: PMC7175236 DOI: 10.3390/biom10030442] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Accepted: 03/11/2020] [Indexed: 12/18/2022] Open
Abstract
: Cardiovascular diseases are one of the leading causes of death in developing countries, generally originating as coronary artery disease (CAD) or hypertension. In later stages, many CAD patients develop left ventricle dysfunction (LVD). Left ventricular ejection fraction (LVEF) is the most prevalent prognostic factor in CAD patients. LVD is a complex multifactorial condition in which the left ventricle of the heart becomes functionally impaired. Various genetic studies have correlated LVD with dilated cardiomyopathy (DCM). In recent years, enormous progress has been made in identifying the genetic causes of cardiac diseases, which has further led to a greater understanding of molecular mechanisms underlying each disease. This progress has increased the probability of establishing a specific genetic diagnosis, and thus providing new opportunities for practitioners, patients, and families to utilize this genetic information. A large number of mutations in sarcomeric genes have been discovered in cardiomyopathies. In this review, we will explore the role of the sarcomeric genes in LVD in CAD patients, which is a major cause of cardiac failure and results in heart failure.
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13
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Lee SP, Ashley EA, Homburger J, Caleshu C, Green EM, Jacoby D, Colan SD, Arteaga-Fernández E, Day SM, Girolami F, Olivotto I, Michels M, Ho CY, Perez MV. Incident Atrial Fibrillation Is Associated With MYH7 Sarcomeric Gene Variation in Hypertrophic Cardiomyopathy. Circ Heart Fail 2019; 11:e005191. [PMID: 30354366 DOI: 10.1161/circheartfailure.118.005191] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background Although atrial fibrillation (AF) is common in hypertrophic cardiomyopathy (HCM) patients, the relationship between genetic variation and AF has been poorly defined. Characterizing genetic subtypes of HCM and their associations with AF may help to improve personalized medical care. We aimed to investigate the link between sarcomeric gene variation and incident AF in HCM patients. Methods and Results Patients from the multinational Sarcomeric Human Cardiomyopathy Registry were followed for incident AF. Those with likely pathogenic or pathogenic variants in sarcomeric genes were included. The AF incidence was ascertained by review of medical records and electrocardiograms at each investigative site. One thousand forty adult HCM patients, without baseline AF and with likely pathogenic or pathogenic variation in either MYH7 (n=296), MYBPC3 (n=659), or thin filament genes (n=85), were included. Compared with patients with variation in other sarcomeric genes, those with MYH7 variants were younger on first clinical encounter at the Sarcomeric Human Cardiomyopathy Registry site and more likely to be probands than the MYBPC3 variants. During an average follow-up of 7.2 years, 198 incident AF events occurred. Patients with likely pathogenic or pathogenic mutations in MYH7 had the highest incidence of AF after adjusting for age, sex, proband status, left atrial size, maximal wall thickness, and peak pressure gradient (hazard ratio, 1.7; 95% CI, 1.1-2.6; P=0.009). Conclusions During a mean follow-up of 7.2 years, new-onset AF developed in 19% of HCM patients with sarcomeric mutations. Compared with other sarcomeric genes, patients with likely pathogenic or pathogenic variation in MYH7 had a higher rate of incident AF independent of clinical and echocardiographic factors.
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Affiliation(s)
- Seung-Pyo Lee
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University, CA (S.-P.L., E.A.A., M.V.P.).,Department of Internal Medicine, Seoul National University Hospital, South Korea (S.-P.L.)
| | - Euan A Ashley
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University, CA (S.-P.L., E.A.A., M.V.P.).,Stanford Center for Inherited Cardiovascular Disease, Stanford University, CA (E.A.A., C.C., M.V.P.).,Department of Genetics, Stanford University, CA (E.A.A., J.H.)
| | | | - Colleen Caleshu
- Stanford Center for Inherited Cardiovascular Disease, Stanford University, CA (E.A.A., C.C., M.V.P.)
| | | | - Daniel Jacoby
- Section of Cardiovascular Medicine, Yale School of Medicine, New Haven, CT (D.J.)
| | - Steven D Colan
- Department of Cardiology, Boston Children's Hospital, MA (S.D.C.)
| | - Edmundo Arteaga-Fernández
- Laboratory of Genetics and Molecular Cardiology and Cardiomyopathies Unit, Heart Institute (InCor), University of São Paulo, Brazil (E.A.-F.)
| | - Sharlene M Day
- Division of Cardiovascular Medicine, University of Michigan Medical School, Ann Arbor (S.M.D.)
| | - Francesca Girolami
- Referral Center for Cardiomyopathies, Careggi University Hospital, Florence, Italy (F.G., I.O.)
| | - Iacopo Olivotto
- Referral Center for Cardiomyopathies, Careggi University Hospital, Florence, Italy (F.G., I.O.)
| | - Michelle Michels
- Department of Cardiology, Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands (M.M.)
| | - Carolyn Y Ho
- Cardiovascular Division, Brigham and Women's Hospital, Boston, MA (C.Y.H.)
| | - Marco V Perez
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University, CA (S.-P.L., E.A.A., M.V.P.).,Stanford Center for Inherited Cardiovascular Disease, Stanford University, CA (E.A.A., C.C., M.V.P.)
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van der Velden J, Stienen GJM. Cardiac Disorders and Pathophysiology of Sarcomeric Proteins. Physiol Rev 2019; 99:381-426. [PMID: 30379622 DOI: 10.1152/physrev.00040.2017] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The sarcomeric proteins represent the structural building blocks of heart muscle, which are essential for contraction and relaxation. During recent years, it has become evident that posttranslational modifications of sarcomeric proteins, in particular phosphorylation, tune cardiac pump function at rest and during exercise. This delicate, orchestrated interaction is also influenced by mutations, predominantly in sarcomeric proteins, which cause hypertrophic or dilated cardiomyopathy. In this review, we follow a bottom-up approach starting from a description of the basic components of cardiac muscle at the molecular level up to the various forms of cardiac disorders at the organ level. An overview is given of sarcomere changes in acquired and inherited forms of cardiac disease and the underlying disease mechanisms with particular reference to human tissue. A distinction will be made between the primary defect and maladaptive/adaptive secondary changes. Techniques used to unravel functional consequences of disease-induced protein changes are described, and an overview of current and future treatments targeted at sarcomeric proteins is given. The current evidence presented suggests that sarcomeres not only form the basis of cardiac muscle function but also represent a therapeutic target to combat cardiac disease.
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Affiliation(s)
- Jolanda van der Velden
- Amsterdam UMC, Vrije Universiteit Amsterdam, Physiology, Amsterdam Cardiovascular Sciences, Amsterdam , The Netherlands ; and Department of Physiology, Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Ger J M Stienen
- Amsterdam UMC, Vrije Universiteit Amsterdam, Physiology, Amsterdam Cardiovascular Sciences, Amsterdam , The Netherlands ; and Department of Physiology, Kilimanjaro Christian Medical University College, Moshi, Tanzania
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15
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Zile MA, Trayanova NA. Increased thin filament activation enhances alternans in human chronic atrial fibrillation. Am J Physiol Heart Circ Physiol 2018; 315:H1453-H1462. [PMID: 30141984 PMCID: PMC6297809 DOI: 10.1152/ajpheart.00658.2017] [Citation(s) in RCA: 7] [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: 11/10/2017] [Revised: 08/21/2018] [Accepted: 08/21/2018] [Indexed: 11/22/2022]
Abstract
Action potential duration (APD) alternans (APD-ALT), defined as beat-to-beat oscillations in APD, has been proposed as an important clinical marker for chronic atrial fibrillation (cAF) risk when it occurs at pacing rates of 120-200 beats/min. Although the ionic mechanisms for occurrence of APD-ALT in human cAF at these clinically relevant rates have been investigated, little is known about the effects of myofilament protein kinetics on APD-ALT. Therefore, we used computer simulations of single cell function to explore whether remodeling in myofilament protein kinetics in human cAF alters the occurrence of APD-ALT and to uncover how these mechanisms are affected by sarcomere length and the degree of cAF-induced myofilament remodeling. Mechanistically based, bidirectionally coupled electromechanical models of human right and left atrial myocytes were constructed, incorporating both ionic and myofilament remodeling associated with cAF. By comparing results from our electromechanical model with those from the uncoupled ionic model, we found that intracellular Ca2+ concentration buffering of troponin C has a dampening effect on the magnitude of APD-ALT (APD-ANM) at slower rates (150 beats/min) due to the cooperativity between strongly bound cross-bridges and Ca2+-troponin C binding affinity. We also discovered that cAF-induced enhanced thin filament activation enhanced APD-ANM at these clinically relevant heart rates (150 beats/min). In addition, longer sarcomere lengths increased APD-ANM, suggesting that atrial stretch is an important modulator of APD-ALT. Together, these findings demonstrate that myofilament kinetics mechanisms play an important role in altering APD-ALT in human cAF. NEW & NOTEWORTHY Using a single cell simulation approach, we explored how myofilament protein kinetics alter the formation of alternans in action potential duration (APD) in human myocytes with chronic atrial fibrillation remodeling. We discovered that enhanced thin filament activation and longer sarcomere lengths increased the magnitude of APD alternans at clinically important pacing rates of 120-200 beats/min. Furthermore, we found that altered intracellular Ca2+ concentration buffering of troponin C has a dampening effect on the magnitude of APD alternans.
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Affiliation(s)
- Melanie A Zile
- Institute for Computational Medicine and Department of Biomedical Engineering, Johns Hopkins University , Baltimore, Maryland
| | - Natalia A Trayanova
- Institute for Computational Medicine and Department of Biomedical Engineering, Johns Hopkins University , Baltimore, Maryland
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16
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Converse role of class I and class IIa HDACs in the progression of atrial fibrillation. J Mol Cell Cardiol 2018; 125:39-49. [PMID: 30321539 DOI: 10.1016/j.yjmcc.2018.09.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 09/25/2018] [Accepted: 09/26/2018] [Indexed: 12/25/2022]
Abstract
Atrial fibrillation (AF), the most common persistent clinical tachyarrhythmia, is associated with altered gene transcription which underlies cardiomyocyte dysfunction, AF susceptibility and progression. Recent research showed class I and class IIa histone deacetylases (HDACs) to regulate pathological and fetal gene expression, and thereby induce hypertrophy and cardiac contractile dysfunction. Whether class I and class IIa HDACs are involved in AF promotion is unknown. We aim to elucidate the role of class I and class IIa HDACs in tachypacing-induced contractile dysfunction in experimental model systems for AF and clinical AF. METHODS AND RESULTS: Class I and IIa HDACs were overexpressed in HL-1 cardiomyocytes followed by calcium transient (CaT) measurements. Overexpression of class I HDACs, HDAC1 or HDAC3, significantly reduced CaT amplitude in control normal-paced (1 Hz) cardiomyocytes, which was further reduced by tachypacing (5 Hz) in HDAC3 overexpressing cardiomyocytes. HDAC3 inhibition by shRNA or by the specific inhibitor, RGFP966, prevented contractile dysfunction in both tachypaced HL-1 cardiomyocytes and Drosophila prepupae. Conversely, overexpression of class IIa HDACs (HDAC4, HDAC5, HDAC7 or HDAC9) did not affect CaT in controls, with HDAC5 and HDAC7 overexpression even protecting against tachypacing-induced CaT loss. Notably, the protective effect of HDAC5 and HDAC7 was abolished in cardiomyocytes overexpressing a dominant negative HDAC5 or HDAC7 mutant, bearing a mutation in the binding domain for myosin enhancer factor 2 (MEF2). Furthermore, tachypacing induced phosphorylation of HDAC5 and promoted its translocation from the nucleus to cytoplasm, leading to up-regulation of MEF2-related fetal gene expression (β-MHC, BNP). In accord, boosting nuclear localization of HDAC5 by MC1568 or Go6983 attenuated CaT loss in tachypaced HL-1 cardiomyocytes and preserved contractile function in Drosophila prepupae. Findings were expanded to clinical AF. Here, patients with AF showed a significant increase in expression levels and activity of HDAC3, phosphorylated HDAC5 and fetal genes (β-MHC, BNP) in atrial tissue compared to controls in sinus rhythm. CONCLUSION: Class I and class IIa HDACs display converse roles in AF progression. Whereas overexpression of Class I HDAC3 induces cardiomyocyte dysfunction, class IIa HDAC5 overexpression reveals protective properties. Accordingly, HDAC3 inhibitors and HDAC5 nuclear boosters show protection from tachypacing-induced changes and therefore may represent interesting therapeutic options in clinical AF.
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Abstract
There has been a significant progress in our understanding of the molecular mechanisms by which calcium (Ca2+) ions mediate various types of cardiac arrhythmias. A growing list of inherited gene defects can cause potentially lethal cardiac arrhythmia syndromes, including catecholaminergic polymorphic ventricular tachycardia, congenital long QT syndrome, and hypertrophic cardiomyopathy. In addition, acquired deficits of multiple Ca2+-handling proteins can contribute to the pathogenesis of arrhythmias in patients with various types of heart disease. In this review article, we will first review the key role of Ca2+ in normal cardiac function-in particular, excitation-contraction coupling and normal electric rhythms. The functional involvement of Ca2+ in distinct arrhythmia mechanisms will be discussed, followed by various inherited arrhythmia syndromes caused by mutations in Ca2+-handling proteins. Finally, we will discuss how changes in the expression of regulation of Ca2+ channels and transporters can cause acquired arrhythmias, and how these mechanisms might be targeted for therapeutic purposes.
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Affiliation(s)
- Andrew P Landstrom
- From the Section of Cardiology, Department of Pediatrics (A.P.L.), Cardiovascular Research Institute (A.P.L., X.H.T.W.), and Departments of Molecular Physiology and Biophysics, Medicine (Cardiology), Center for Space Medicine (X.H.T.W.), Baylor College of Medicine, Houston, TX; and Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany (D.D.)
| | - Dobromir Dobrev
- From the Section of Cardiology, Department of Pediatrics (A.P.L.), Cardiovascular Research Institute (A.P.L., X.H.T.W.), and Departments of Molecular Physiology and Biophysics, Medicine (Cardiology), Center for Space Medicine (X.H.T.W.), Baylor College of Medicine, Houston, TX; and Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany (D.D.)
| | - Xander H T Wehrens
- From the Section of Cardiology, Department of Pediatrics (A.P.L.), Cardiovascular Research Institute (A.P.L., X.H.T.W.), and Departments of Molecular Physiology and Biophysics, Medicine (Cardiology), Center for Space Medicine (X.H.T.W.), Baylor College of Medicine, Houston, TX; and Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany (D.D.).
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18
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Heijman J, Ghezelbash S, Wehrens XHT, Dobrev D. Serine/Threonine Phosphatases in Atrial Fibrillation. J Mol Cell Cardiol 2017; 103:110-120. [PMID: 28077320 DOI: 10.1016/j.yjmcc.2016.12.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 12/15/2016] [Accepted: 12/20/2016] [Indexed: 12/19/2022]
Abstract
Serine/threonine protein phosphatases control dephosphorylation of numerous cardiac proteins, including a variety of ion channels and calcium-handling proteins, thereby providing precise post-translational regulation of cardiac electrophysiology and function. Accordingly, dysfunction of this regulation can contribute to the initiation, maintenance and progression of cardiac arrhythmias. Atrial fibrillation (AF) is the most common heart rhythm disorder and is characterized by electrical, autonomic, calcium-handling, contractile, and structural remodeling, which include, among other things, changes in the phosphorylation status of a wide range of proteins. Here, we review AF-associated alterations in the phosphorylation of atrial ion channels, calcium-handling and contractile proteins, and their role in AF-pathophysiology. We highlight the mechanisms controlling the phosphorylation of these proteins and focus on the role of altered dephosphorylation via local type-1, type-2A and type-2B phosphatases (PP1, PP2A, and PP2B, also known as calcineurin, respectively). Finally, we discuss the challenges for phosphatase research, potential therapeutic significance of altered phosphatase-mediated protein dephosphorylation in AF, as well as future directions.
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Affiliation(s)
- Jordi Heijman
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Faculty of Health, Medicine, and Life Sciences, Maastricht University, Maastricht, The Netherlands
| | - Shokoufeh Ghezelbash
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
| | - Xander H T Wehrens
- Cardiovascular Research Institute, Department of Molecular Physiology and Biophysics, Department of Medicine (Cardiology), Pediatrics, Baylor College of Medicine, Houston, USA
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany.
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Cañón S, Caballero R, Herraiz-Martínez A, Pérez-Hernández M, López B, Atienza F, Jalife J, Hove-Madsen L, Delpón E, Bernad A. miR-208b upregulation interferes with calcium handling in HL-1 atrial myocytes: Implications in human chronic atrial fibrillation. J Mol Cell Cardiol 2016; 99:162-173. [PMID: 27545043 DOI: 10.1016/j.yjmcc.2016.08.012] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 07/29/2016] [Accepted: 08/17/2016] [Indexed: 01/14/2023]
Abstract
MicroRNAs (miR) have considerable potential as therapeutic tools in cardiac diseases. Alterations in atrial miR are involved in the development of atrial fibrillation (AF), but the molecular mechanism underlying their contribution to atrial remodeling in chronic atrial fibrillation (CAF) is only partially understood. Here we used miR array to analyze the miR profile of atrial biopsies from sinus rhythm (SR) and CAF patients. qRT-PCR identified a distinctive CAF-miR signature and described conserved miR-208b upregulation in human and ovine AF atrial tissue. We used bioinformatics analysis to predict genes and signaling pathways as putative miR-208b targets, which highlighted genes from the cardiac muscle gene program and from canonical WNT, gap-junction and Ca2+ signaling networks. Results from analysis of miR-208b-overexpressing HL-1 atrial myocytes and from myocytes isolated from CAF patients showed that aberrant miR-208b levels reduced the expression and function of L-type Ca2+ channel subunits (CACNA1C and CACNB2) as well as the sarcoplasmic reticulum-Ca2+ pump SERCA2. These findings clearly pointed to CAF-specific upregulated miR-208b as an important mediator in Ca2+ handling impairment during atrial remodeling.
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Affiliation(s)
- Susana Cañón
- Cardiovascular Development and Repair Department, Spanish National Cardiovascular Research Center (CNIC), Madrid, Spain; Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain
| | - Ricardo Caballero
- Department of Pharmacology, School of Medicine, Universidad Complutense, 28040 Madrid, Spain
| | - Adela Herraiz-Martínez
- Cardiovascular Research Centre, CSIC-ICCC, Barcelona, Spain; Instituto de Investigación Biomédica Sant Pau, Hospital de la Santa Creu y Sant Pau, Barcelona, Spain
| | - Marta Pérez-Hernández
- Department of Pharmacology, School of Medicine, Universidad Complutense, 28040 Madrid, Spain
| | - Begoña López
- Program for Cardiovascular Diseases, Centre for Applied Medical Research, University of Navarra, Pamplona, Spain; Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain
| | - Felipe Atienza
- Cardiology Department, Hospital General Universitario Gregorio Marañón, Madrid, Spain
| | - José Jalife
- Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA; Area of Myocardial Pathophysiology, Spanish National Cardiovascular Research Center (CNIC), Madrid, Spain
| | - Leif Hove-Madsen
- Cardiovascular Research Centre, CSIC-ICCC, Barcelona, Spain; Instituto de Investigación Biomédica Sant Pau, Hospital de la Santa Creu y Sant Pau, Barcelona, Spain
| | - Eva Delpón
- Department of Pharmacology, School of Medicine, Universidad Complutense, 28040 Madrid, Spain
| | - Antonio Bernad
- Cardiovascular Development and Repair Department, Spanish National Cardiovascular Research Center (CNIC), Madrid, Spain; Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain.
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Impact of Genotype on the Occurrence of Atrial Fibrillation in Patients With Hypertrophic Cardiomyopathy. Am J Cardiol 2016; 117:1151-9. [PMID: 26869393 DOI: 10.1016/j.amjcard.2015.12.058] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 12/26/2015] [Accepted: 12/26/2015] [Indexed: 12/19/2022]
Abstract
Genes associated with hypertrophic cardiomyopathy (HC) are not uniformly expressed in the atrial myocardium. Whether this may impact susceptibility to atrial fibrillation (AF) is unresolved. To analyze the prevalence and clinical correlates of AF in relation to genotype in a large HC cohort, prevalence and clinical profile of AF were assessed in 237 patients with HC, followed for 14 ± 10 years. Patients were divided into 3 genetic subgroups: (1) MYBPC3 (58%), (2) MYH7 (28%), and (3) "other genotypes" (14%; comprising TNNT2, TNNI3, TPM1, MYL2, complex genotypes, Z-line, and E-C coupling genes). Left atrial size was similar in the 3 subsets. AF occurred in 74 patients with HC (31%), with no difference among groups (31% in MYBPC3, 37% in MYH7 and 18% in other genotypes, p = 0.15), paroxysmal/persistent AF (12%, 18%, and 12%, respectively; p = 0.53), paroxysmal/persistent evolved to permanent (12%, 12%, and 3%, p = 0.36) or permanent AF (7%, 7%, and 3%, p = 0.82). Age at AF onset was younger in the group with other genotypes (37 ± 10 years) compared to the first 2 groups (53 ± 14 and 51 ± 17, respectively; p = 0.05) because of early onset associated with complex genotypes and a specific JPH2 mutation associated with abnormal intracellular calcium handling. At multivariate analysis, independent predictors of AF were atrial diameter (p ≤0.05) and age at diagnosis (p = 0.09), but not genetic subtype (p = 0.35). In conclusion, in patients with HC, genetic testing cannot be used in clinical decision making with regard to management strategies for AF. Genotype is not predictive of onset or severity of AF, which appears rather driven by hemodynamic determinants of atrial dilatation. Exceptions are represented by rare genes suggesting specific molecular pathways for AF in genetic cardiomyopathies.
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Latrunculin B modulates electrophysiological characteristics and arrhythmogenesis in pulmonary vein cardiomyocytes. Clin Sci (Lond) 2016; 130:721-32. [PMID: 26839418 DOI: 10.1042/cs20150593] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 02/02/2016] [Indexed: 01/28/2023]
Abstract
AF (atrial fibrillation) is the most common sustained arrhythmia, and the PVs (pulmonary veins) play a critical role in triggering AF. Stretch causes structural remodelling, including cytoskeleton rearrangement, which may play a role in the genesis of AF. Lat-B (latrunculin B), an inhibitor of actin polymerization, is involved in Ca(2+) regulation. However, it is unclear whether Lat-B directly modulates the electrophysiological characteristics and Ca(2+) homoeostasis of the PVs. Conventional microelectrodes, whole-cell patch-clamp, and the fluo-3 fluorimetric ratio technique were used to record ionic currents and intracellular Ca(2+) within isolated rabbit PV preparations, or within isolated single PV cardiomyocytes, before and after administration of Lat-B (100 nM). Langendorff-perfused rabbit hearts were exposed to acute and continuous atrial stretch, and we studied PV electrical activity. Lat-B (100 nM) decreased the spontaneous electrical activity by 16±4% in PV preparations. Lat-B (100 nM) decreased the late Na(+) current, L-type Ca(2+) current, Na(+)/Ca(2+) exchanger current, and stretch-activated BKCa current, but did not affect the Na(+) current in PV cardiomyocytes. Lat-B reduced the transient outward K(+) current and ultra-rapid delayed rectifier K(+) current, but increased the delayed rectifier K(+) current in isolated PV cardiomyocytes. In addition, Lat-B (100 nM) decreased intracellular Ca(2+) transient and sarcoplasmic reticulum Ca(2+) content in PV cardiomyocytes. Moreover, Lat-B attenuated stretch-induced increased spontaneous electrical activity and trigger activity. The effects of Lat-B on the PV spontaneous electrical activity were attenuated in the presence of Y-27632 [10 μM, a ROCK (Rho-associated kinase) inhibitor] and cytochalasin D (10 μM, an actin polymerization inhibitor). In conclusion, Lat-B regulates PV electrophysiological characteristics and attenuates stretch-induced arrhythmogenesis.
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Najafi A, Sequeira V, Helmes M, Bollen IAE, Goebel M, Regan JA, Carrier L, Kuster DWD, Van Der Velden J. Selective phosphorylation of PKA targets after β-adrenergic receptor stimulation impairs myofilament function in Mybpc3-targeted HCM mouse model. Cardiovasc Res 2016; 110:200-14. [PMID: 26825555 DOI: 10.1093/cvr/cvw026] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 01/22/2016] [Indexed: 12/19/2022] Open
Abstract
AIMS Hypertrophic cardiomyopathy (HCM) has been associated with reduced β-adrenergic receptor (β-AR) signalling, leading downstream to a low protein kinase A (PKA)-mediated phosphorylation. It remained undefined whether all PKA targets will be affected similarly by diminished β-AR signalling in HCM. We aimed to investigate the role of β-AR signalling on regulating myofilament and calcium handling in an HCM mouse model harbouring a gene mutation (G > A transition on the last nucleotide of exon 6) in Mybpc3 encoding cardiac myosin-binding protein C. METHODS AND RESULTS Cardiomyocyte contractile properties and phosphorylation state were measured in left ventricular permeabilized and intact cardiomyocytes isolated from heterozygous (HET) or homozygous (KI) Mybpc3-targeted knock-in mice. Significantly higher myofilament Ca²⁺sensitivity and passive tension were detected in KI mice, which were normalized after PKA treatment. Loaded intact cardiomyocyte force-sarcomere length relation was impaired in both HET and KI mice, suggesting a reduced length-dependent activation. Unloaded cardiomyocyte function revealed an impaired myofilament contractile response to isoprenaline (ISO) in KI, whereas the calcium-handling response to ISO was maintained. This disparity was explained by an attenuated increase in cardiac troponin I (cTnI) phosphorylation in KI, whereas the increase in phospholamban (PLN) phosphorylation was maintained to wild-type values. CONCLUSION These data provide evidence that in the KI HCM mouse model, β-AR stimulation leads to preferential PKA phosphorylation of PLN over cTnI, resulting in an impaired inotropic and lusitropic response.
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Affiliation(s)
- Aref Najafi
- Department of Physiology, Institute for Cardiovascular Research (ICaR-VU), VU University Medical Center Amsterdam, Netherlands ICIN-Netherlands Heart Institute, Utrecht, The Netherlands
| | - Vasco Sequeira
- Department of Physiology, Institute for Cardiovascular Research (ICaR-VU), VU University Medical Center Amsterdam, Netherlands
| | - Michiel Helmes
- Department of Physiology, Institute for Cardiovascular Research (ICaR-VU), VU University Medical Center Amsterdam, Netherlands
| | - Ilse A E Bollen
- Department of Physiology, Institute for Cardiovascular Research (ICaR-VU), VU University Medical Center Amsterdam, Netherlands
| | - Max Goebel
- Department of Physiology, Institute for Cardiovascular Research (ICaR-VU), VU University Medical Center Amsterdam, Netherlands
| | - Jessica A Regan
- Department of Physiology, Institute for Cardiovascular Research (ICaR-VU), VU University Medical Center Amsterdam, Netherlands
| | - Lucie Carrier
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Germany
| | - Diederik W D Kuster
- Department of Physiology, Institute for Cardiovascular Research (ICaR-VU), VU University Medical Center Amsterdam, Netherlands
| | - Jolanda Van Der Velden
- Department of Physiology, Institute for Cardiovascular Research (ICaR-VU), VU University Medical Center Amsterdam, Netherlands ICIN-Netherlands Heart Institute, Utrecht, The Netherlands
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Abstract
Optimal cardiac function depends on proper timing of excitation and contraction in various regions of the heart, as well as on appropriate heart rate. This is accomplished via specialized electrical properties of various components of the system, including the sinoatrial node, atria, atrioventricular node, His-Purkinje system, and ventricles. Here we review the major regionally determined electrical properties of these cardiac regions and present the available data regarding the molecular and ionic bases of regional cardiac function and dysfunction. Understanding these differences is of fundamental importance for the investigation of arrhythmia mechanisms and pharmacotherapy.
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Affiliation(s)
- Daniel C Bartos
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Crystal M Ripplinger
- Department of Pharmacology, University of California Davis, Davis, California, USA
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Harleton E, Besana A, Chandra P, Danilo P, Rosen TS, Rosen MR, Argenziano M, Robinson RB, Feinmark SJ. TASK-1 current is inhibited by phosphorylation during human and canine chronic atrial fibrillation. Am J Physiol Heart Circ Physiol 2014; 308:H126-34. [PMID: 25437921 DOI: 10.1152/ajpheart.00614.2014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Atrial fibrillation (AF) is a common arrhythmia with significant morbidities and only partially adequate therapeutic options. AF is associated with atrial remodeling processes, including changes in the expression and function of ion channels and signaling pathways. TWIK protein-related acid-sensitive K+ channel (TASK)-1, a two-pore domain K+ channel, has been shown to contribute to action potential repolarization as well as to the maintenance of resting membrane potential in isolated myocytes, and TASK-1 inhibition has been associated with the induction of perioperative AF. However, the role of TASK-1 in chronic AF is unknown. The present study investigated the function, expression, and phosphorylation of TASK-1 in chronic AF in atrial tissue from chronically paced canines and in human subjects. TASK-1 current was present in atrial myocytes isolated from human and canine hearts in normal sinus rhythm but was absent in myocytes from humans with AF and in canines after the induction of AF by chronic tachypacing. The addition of phosphatase to the patch pipette rescued TASK-1 current from myocytes isolated from AF hearts, indicating that the change in current is phosphorylation dependent. Western blot analysis showed that total TASK-1 protein levels either did not change or increased slightly in AF, despite the absence of current. In studies of perioperative AF, we have shown that phosphorylation of TASK-1 at Thr383 inhibits the channel. However, phosphorylation at this site was unchanged in atrial tissue from humans with AF or in canines with chronic pacing-induced AF. We conclude that phosphorylation-dependent inhibition of TASK-1 is associated with AF, but the phosphorylation site responsible for this inhibition remains to be identified.
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Affiliation(s)
- Erin Harleton
- Department of Pharmacology, Columbia University Medical Center, New York, New York
| | - Alessandra Besana
- Department of Pharmacology, Columbia University Medical Center, New York, New York
| | - Parag Chandra
- Department of Pharmacology, Columbia University Medical Center, New York, New York
| | - Peter Danilo
- Department of Pharmacology, Columbia University Medical Center, New York, New York
| | - Tove S Rosen
- Department of Pediatrics, Columbia University Medical Center, New York, New York
| | - Michael R Rosen
- Department of Pharmacology, Columbia University Medical Center, New York, New York; Department of Pediatrics, Columbia University Medical Center, New York, New York
| | - Michael Argenziano
- Division of Cardiothoracic Surgery, Department of Surgery, Columbia University Medical Center, New York, New York; and
| | - Richard B Robinson
- Department of Pharmacology, Columbia University Medical Center, New York, New York
| | - Steven J Feinmark
- Department of Pharmacology, Columbia University Medical Center, New York, New York;
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Yin Z, Ren J, Guo W. Sarcomeric protein isoform transitions in cardiac muscle: a journey to heart failure. Biochim Biophys Acta Mol Basis Dis 2014; 1852:47-52. [PMID: 25446994 DOI: 10.1016/j.bbadis.2014.11.003] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 10/27/2014] [Accepted: 11/04/2014] [Indexed: 01/05/2023]
Abstract
Sarcomeric protein isoforms are mainly governed by alternative promoter-driven expression, distinct gene expression, gene mutation and alternative mRNA splicing. The transitions of sarcomeric proteins have been implicated to play a role in the onset and development of human heart failure. In this mini-review, we summarized isoform transitions of several most widely examined sarcomeric proteins including myosin, actin, troponin, tropomyosin, titin and myosin binding protein-C, and the consequence of these abnormal isoform transitions. Even though the isoform transitions of sarcomeric proteins have been described in individual sarcomeric protein reviews, no concise summary of these results has been presented previously. This review is intended to fill this gap and discuss possible future perspectives.
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Affiliation(s)
- Zhiyong Yin
- Animal Science, College of Agriculture and Natural Resources, University of WY, Laramie WY82071, USA; Department of Cardiology, Xi Jing Hospital, Fourth Military Medical University, Xi'an 710032, PR China
| | - Jun Ren
- Center for Cardiovascular Research and Alternative Medicine, College of Health Science, University of WY, Laramie WY82071, USA
| | - Wei Guo
- Animal Science, College of Agriculture and Natural Resources, University of WY, Laramie WY82071, USA; Center for Cardiovascular Research and Alternative Medicine, College of Health Science, University of WY, Laramie WY82071, USA.
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27
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Reiser PJ, Moravec CS. Sex differences in myosin heavy chain isoforms of human failing and nonfailing atria. Am J Physiol Heart Circ Physiol 2014; 307:H265-72. [DOI: 10.1152/ajpheart.00810.2013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mammalian hearts express two myosin heavy chain (MHC) isoforms, which drive contractions with different kinetics and power-generating ability. The expression of the isoform that is associated with more rapid contraction kinetics and greater power output, MHC-α, is downregulated, with a concurrent increase in the relative amount of the slower isoform, MHC-β, during the progression to experimentally induced or disease-related heart failure. This change in protein expression has been well studied in right and left ventricles in heart failure models and in humans with failure. Relatively little quantitative data exists regarding MHC isoform expression shifts in human failing atria. We previously reported significant increases in the relative amount of MHC-β in the human failing left atrium. The results of that study suggested that there might be a sex-related difference in the level of MHC-β in the left atrium, but the number of female subjects was insufficient for statistical analysis. The objective of this study was to test whether there is, in fact, a sex-related difference in the level of MHC-β in the right and left atria of humans with cardiomyopathy. The results indicate that significant differences exist in atrial MHC isoform expression between men and women who are in failure. The results also revealed an unexpected twofold greater amount of MHC-β in the nonfailing left atrium of women, compared with men. The observed sex-related differences in MHC isoform expression could impact ventricular diastolic filling during normal daily activities, as well as during physiologically stressful events.
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Affiliation(s)
- Peter J. Reiser
- Division of Biosciences, College of Dentistry, Ohio State University, Columbus, Ohio; and
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28
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Posttranslational modifications of cardiac troponin T: An overview. J Mol Cell Cardiol 2013; 63:47-56. [DOI: 10.1016/j.yjmcc.2013.07.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 06/18/2013] [Accepted: 07/08/2013] [Indexed: 12/22/2022]
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Platelet-derived growth factor: A promising therapeutic target for atrial fibrillation. Heart Rhythm 2013; 10:1052-3. [DOI: 10.1016/j.hrthm.2013.04.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Indexed: 12/20/2022]
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30
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Musa H, Kaur K, O'Connell R, Klos M, Guerrero-Serna G, Avula UMR, Herron TJ, Kalifa J, Anumonwo JMB, Jalife J. Inhibition of platelet-derived growth factor-AB signaling prevents electromechanical remodeling of adult atrial myocytes that contact myofibroblasts. Heart Rhythm 2013; 10:1044-51. [PMID: 23499624 PMCID: PMC3692578 DOI: 10.1016/j.hrthm.2013.03.014] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Indexed: 02/08/2023]
Abstract
BACKGROUND Persistent atrial fibrillation (PAF) results in electromechanical and structural remodeling by mechanisms that are poorly understood. Myofibroblast proliferation and fibrosis are major sources of structural remodeling in PAF. Myofibroblasts also interact with atrial myocytes via direct physical contact and release of signaling molecules, which may contribute to remodeling. OBJECTIVE To determine whether myofibroblasts contribute to atrial myocyte electromechanical remodeling via direct physical contact and platelet-derived growth factor (PDGF) signaling. METHODS Myofibroblasts and myocytes from adult sheep atria were co-cultured for 24 hours. Alternatively adult sheep atrial myocytes were exposed to 1 ng/mL recombitant PDGF AB peptide for 24 hours. RESULTS Myocytes making contact with myofibroblasts demonstrated significant reduction (P ≤ .05) in peak L-type calcium current density, shortening of action potential duration (APD), and reduction in calcium transients. These effects were blocked by pretreatment with a PDGF-AB neutralizing anti-body. Heterocellular contact also severely disturbed the localization of the L-type calcium channel. Myocytes exposed to recombinant PDGF-AB peptide for 24 hours demonstrated reduced APD50, APD80 and Peak L-type calcium current. Pretreatment with a PDGF-AB neutralizing antibody prevented these effects. Finally, while control atrial myocytes did not respond in a 1:1 manner to pacing frequencies of 3 Hz or higher, atrial myocytes from hearts that were tachypaced for 2 months and normal myocytes treated with PDGF-AB for 24 hours could be paced up to 10 Hz. CONCLUSIONS In addition to leading to fibrosis, atrial myofibroblasts contribute to electromechanical remodeling of myocytes via direct physical contact and release of PDGF-AB, which may be a factor in PAF-induced remodeling.
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Affiliation(s)
- Hassan Musa
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan 48109, USA.
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Protein analysis of atrial fibrosis via label-free proteomics in chronic atrial fibrillation patients with mitral valve disease. PLoS One 2013; 8:e60210. [PMID: 23593175 PMCID: PMC3617171 DOI: 10.1371/journal.pone.0060210] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Accepted: 02/22/2013] [Indexed: 01/21/2023] Open
Abstract
Background Atrial fibrosis, as a hallmark of atrial structure remodeling, plays an important role in maintenance of chronic atrial fibrillation, but interrelationship of atrial fibrosis and atrial fibrillation is uncertain. Label-free proteomics can implement high throughput screening for finding and analyzing pivotal proteins related to the disease.. Therefore, we used label-free proteomics to explore and analyze differentially proteins in chronic atrial fibrillation patients with mitral valve disease. Methods Left and right atrial appendages obtained from patients with mitral valve disease were both in chronic atrial fibrillation (CAF, AF≥6 months, n = 6) and in sinus rhythm (SR, n = 6). One part of the sample was used for histological analysis and fibrosis quantification; other part were analyzed by label-free proteomic combining liquid chromatography with mass spectrometry (LC-MS), we utilized bioinformatics analysis to identify differential proteins. Results Degree of atrial fibrosis was higher in CAF patients than that of SR patients. 223 differential proteins were detected between two groups. These proteins mainly had vital functions such as cell proliferation, stress response, focal adhesion apoptosis. We evaluated that serine/threonine protein kinase N2 (PKN2), dermatopontin(DP), S100 calcium binding protein B(S100B), protein tyrosine kinase 2(PTK2) and discoidin domain receptor tyrosine kinase 2(DDR2) played important roles in fibrotic process related to atrial fibrillation. Conclusion The study presented differential proteins responsible for atrial fibrosis in chronic atrial fibrillation patients through label-free proteomic analysis. We assessed some vital proteins including their characters and roles. These findings may open up new realm for mechanism research of atrial fibrillation.
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Deacon JC, Bloemink MJ, Rezavandi H, Geeves MA, Leinwand LA. Erratum to: Identification of functional differences between recombinant human α and β cardiac myosin motors. Cell Mol Life Sci 2012; 69:4239-55. [PMID: 23001010 PMCID: PMC3685716 DOI: 10.1007/s00018-012-1111-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The myosin isoform composition of the heart is dynamic in health and disease and has been shown to affect contractile velocity and force generation. While different mammalian species express different proportions of α and β myosin heavy chain, healthy human heart ventricles express these isoforms in a ratio of about 1:9 (α:β) while failing human ventricles express no detectable α-myosin. We report here fast-kinetic analysis of recombinant human α and β myosin heavy chain motor domains. This represents the first such analysis of any human muscle myosin motor and the first of α-myosin from any species. Our findings reveal substantial isoform differences in individual kinetic parameters, overall contractile character, and predicted cycle times. For these parameters, α-subfragment 1 (S1) is far more similar to adult fast skeletal muscle myosin isoforms than to the slow β isoform despite 91% sequence identity between the motor domains of α- and β-myosin. Among the features that differentiate α- from β-S1: the ATP hydrolysis step of α-S1 is ~ten-fold faster than β-S1, α-S1 exhibits ~five-fold weaker actin affinity than β-S1, and actin·α-S1 exhibits rapid ADP release, which is >ten-fold faster than ADP release for β-S1. Overall, the cycle times are ten-fold faster for α-S1 but the portion of time each myosin spends tightly bound to actin (the duty ratio) is similar. Sequence analysis points to regions that might underlie the basis for this finding.
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Affiliation(s)
- John C. Deacon
- Department of Molecular, Cellular and Developmental Biology and Biofrontiers Institute, University of Colorado, MCDB, UCB 347, Boulder, CO 80309 USA
| | | | - Heresh Rezavandi
- School of Biosciences, University of Kent, Canterbury, CT2 7NJ UK
| | | | - Leslie A. Leinwand
- Department of Molecular, Cellular and Developmental Biology and Biofrontiers Institute, University of Colorado, MCDB, UCB 347, Boulder, CO 80309 USA
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Affiliation(s)
- Ayesha I. De Souza
- From the Cardiovascular Sciences Research Centre, St. George’s University of London, London, United Kingdom
| | - A. John Camm
- From the Cardiovascular Sciences Research Centre, St. George’s University of London, London, United Kingdom
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Grandi E, Workman AJ, Pandit SV. Altered Excitation-Contraction Coupling in Human Chronic Atrial Fibrillation. J Atr Fibrillation 2012; 4:495. [PMID: 28496736 DOI: 10.4022/jafib.495] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2011] [Revised: 02/10/2012] [Accepted: 03/19/2012] [Indexed: 12/19/2022]
Abstract
This review focuses on the (mal)adaptive processes in atrial excitation-contraction coupling occurring in patients with chronic atrial fibrillation. Cellular remodeling includes shortening of the atrial action potential duration and effective refractory period, depressed intracellular Ca2+ transient, and reduced myocyte contractility. Here we summarize the current knowledge of the ionic bases underlying these changes. Understanding the molecular mechanisms of excitation-contraction-coupling remodeling in the fibrillating human atria is important to identify new potential targets for AF therapy.
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Affiliation(s)
- Eleonora Grandi
- Department of Pharmacology, University of California at Davis, Davis, CA, USA
| | - Antony J Workman
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, UK
| | - Sandeep V Pandit
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, MI, USA
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35
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Deacon JC, Bloemink MJ, Rezavandi H, Geeves MA, Leinwand LA. Identification of functional differences between recombinant human α and β cardiac myosin motors. Cell Mol Life Sci 2012; 69:2261-77. [PMID: 22349210 PMCID: PMC3375423 DOI: 10.1007/s00018-012-0927-3] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2011] [Revised: 12/29/2011] [Accepted: 01/19/2012] [Indexed: 11/24/2022]
Abstract
The myosin isoform composition of the heart is dynamic in health and disease and has been shown to affect contractile velocity and force generation. While different mammalian species express different proportions of α and β myosin heavy chain, healthy human heart ventricles express these isoforms in a ratio of about 1:9 (α:β) while failing human ventricles express no detectable α-myosin. We report here fast-kinetic analysis of recombinant human α and β myosin heavy chain motor domains. This represents the first such analysis of any human muscle myosin motor and the first of α-myosin from any species. Our findings reveal substantial isoform differences in individual kinetic parameters, overall contractile character, and predicted cycle times. For these parameters, α-subfragment 1 (S1) is far more similar to adult fast skeletal muscle myosin isoforms than to the slow β isoform despite 91% sequence identity between the motor domains of α- and β-myosin. Among the features that differentiate α- from β-S1: the ATP hydrolysis step of α-S1 is ~ten-fold faster than β-S1, α-S1 exhibits ~five-fold weaker actin affinity than β-S1, and actin·α-S1 exhibits rapid ADP release, which is >ten-fold faster than ADP release for β-S1. Overall, the cycle times are ten-fold faster for α-S1 but the portion of time each myosin spends tightly bound to actin (the duty ratio) is similar. Sequence analysis points to regions that might underlie the basis for this finding.
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Affiliation(s)
- John C Deacon
- Department of Molecular, Cellular and Developmental Biology and Biofrontiers Institute, University of Colorado, MCDB, Boulder, CO 80309, USA
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Di Martino ES, Bellini C, Schwartzman DS. In vivo porcine left atrial wall stress: Effect of ventricular tachypacing on spatial and temporal stress distribution. J Biomech 2011; 44:2755-60. [DOI: 10.1016/j.jbiomech.2011.09.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Revised: 09/02/2011] [Accepted: 09/04/2011] [Indexed: 10/17/2022]
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Schotten U, Verheule S, Kirchhof P, Goette A. Pathophysiological mechanisms of atrial fibrillation: a translational appraisal. Physiol Rev 2011; 91:265-325. [PMID: 21248168 DOI: 10.1152/physrev.00031.2009] [Citation(s) in RCA: 852] [Impact Index Per Article: 65.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Atrial fibrillation (AF) is an arrhythmia that can occur as the result of numerous different pathophysiological processes in the atria. Some aspects of the morphological and electrophysiological alterations promoting AF have been studied extensively in animal models. Atrial tachycardia or AF itself shortens atrial refractoriness and causes loss of atrial contractility. Aging, neurohumoral activation, and chronic atrial stretch due to structural heart disease activate a variety of signaling pathways leading to histological changes in the atria including myocyte hypertrophy, fibroblast proliferation, and complex alterations of the extracellular matrix including tissue fibrosis. These changes in electrical, contractile, and structural properties of the atria have been called "atrial remodeling." The resulting electrophysiological substrate is characterized by shortening of atrial refractoriness and reentrant wavelength or by local conduction heterogeneities caused by disruption of electrical interconnections between muscle bundles. Under these conditions, ectopic activity originating from the pulmonary veins or other sites is more likely to occur and to trigger longer episodes of AF. Many of these alterations also occur in patients with or at risk for AF, although the direct demonstration of these mechanisms is sometimes challenging. The diversity of etiological factors and electrophysiological mechanisms promoting AF in humans hampers the development of more effective therapy of AF. This review aims to give a translational overview on the biological basis of atrial remodeling and the proarrhythmic mechanisms involved in the fibrillation process. We pay attention to translation of pathophysiological insights gained from in vitro experiments and animal models to patients. Also, suggestions for future research objectives and therapeutical implications are discussed.
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Affiliation(s)
- Ulrich Schotten
- Department of Physiology, University Maastricht, Maastricht, The Netherlands.
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Greiser M, Lederer WJ, Schotten U. Alterations of atrial Ca(2+) handling as cause and consequence of atrial fibrillation. Cardiovasc Res 2010; 89:722-33. [PMID: 21159669 DOI: 10.1093/cvr/cvq389] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Atrial fibrillation (AF) is the most prevalent sustained arrhythmia. As the most important risk factor for embolic stroke, AF is associated with a high morbidity and mortality. Despite decades of research, successful (pharmacological and interventional) 'ablation' of the arrhythmia remains challenging. AF is characterized by a diverse aetiology, including heart failure, hypertension, and valvular disease. Based on this understanding, new treatment strategies that are specifically tailored to the underlying pathophysiology of a certain 'type' of AF are being developed. One important aspect of AF pathophysiology is altered intracellular Ca(2+) handling. Due to the increase in the atrial activation rate and the subsequent initial [Ca(2+)](i) overload, AF induces 'remodelling' of intracellular Ca(2+) handling. Current research focuses on unravelling the contribution of altered intracellular Ca(2+) handling to different types of AF. More specifically, changes in intracellular Ca(2+) homeostasis preceding the onset of AF, in conditions which predispose to AF (e.g. heart failure), appear to be different from changes in Ca(2+) handling developing after the onset of AF. Here we review and critique altered intracellular Ca(2+) handling and its contribution to three specific aspects of AF pathophysiology, (i) excitation-transcription coupling and Ca(2+)-dependent signalling pathways, (ii) atrial contractile dysfunction, and (iii) arrhythmogenicity.
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Affiliation(s)
- Maura Greiser
- Department of Physiology, Maastricht University, Maastricht, The Netherlands
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De Jong AM, Maass AH, Oberdorf-Maass SU, Van Veldhuisen DJ, Van Gilst WH, Van Gelder IC. Mechanisms of atrial structural changes caused by stretch occurring before and during early atrial fibrillation. Cardiovasc Res 2010; 89:754-65. [PMID: 21075756 DOI: 10.1093/cvr/cvq357] [Citation(s) in RCA: 189] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Structural remodelling occurring before, due to the underlying heart disease, and during atrial fibrillation (AF) sets the stage for permanent AF. Current therapy in AF aims to maintain sinus rhythm in symptomatic patients, but outcome is unfortunately poor. Stretch of the atria is a main contributor to atrial remodelling. In this review, we describe different aspects of structural remodelling as seen in animal models and in patients with AF, including atrial enlargement, cellular hypertrophy, dedifferentiation, fibrosis, apoptosis, and loss of contractile elements. In the second part, we describe downstream signals of mechanical stretch and their contribution to AF and structural remodelling. Ultimately, knowledge of mechanisms underlying structural remodelling may help to identify new pharmacological targets for AF prevention.
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Affiliation(s)
- Anne Margreet De Jong
- Department of Experimental Cardiology, University Medical Center Groningen, University of Groningen, The Netherlands
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Atrial contractile protein content and function are preserved in patients with coronary artery disease and atrial fibrillation. Coron Artery Dis 2010; 21:357-62. [DOI: 10.1097/mca.0b013e32833d5fc9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Wakili R, Yeh YH, Yan Qi X, Greiser M, Chartier D, Nishida K, Maguy A, Villeneuve LR, Boknik P, Voigt N, Krysiak J, Kääb S, Ravens U, Linke WA, Stienen GJM, Shi Y, Tardif JC, Schotten U, Dobrev D, Nattel S. Multiple potential molecular contributors to atrial hypocontractility caused by atrial tachycardia remodeling in dogs. Circ Arrhythm Electrophysiol 2010; 3:530-41. [PMID: 20660541 DOI: 10.1161/circep.109.933036] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Atrial fibrillation impairs atrial contractility, inducing atrial stunning that promotes thromboembolic stroke. Action potential (AP)-prolonging drugs are reported to normalize atrial hypocontractility caused by atrial tachycardia remodeling (ATR). Here, we addressed the role of AP duration (APD) changes in ATR-induced hypocontractility. METHODS AND RESULTS ATR (7-day tachypacing) decreased APD (perforated patch recording) by ≈50%, atrial contractility (echocardiography, cardiomyocyte video edge detection), and [Ca(2+)](i) transients. ATR AP waveforms suppressed [Ca(2+)](i) transients and cell shortening of control cardiomyocytes; whereas control AP waveforms improved [Ca(2+)](i) transients and cell shortening in ATR cells. However, ATR cardiomyocytes clamped with the same control AP waveform had ≈60% smaller [Ca(2+)](i) transients and cell shortening than control cells. We therefore sought additional mechanisms of contractile impairment. Whole-cell voltage clamp revealed reduced I(CaL); I(CaL) inhibition superimposed on ATR APs further suppressed [Ca(2+)](i) transients in control cells. Confocal microscopy indicated ATR-impaired propagation of the Ca(2+) release signal to the cell center in association with loss of t-tubular structures. Myofilament function studies in skinned permeabilized cardiomyocytes showed altered Ca(2+) sensitivity and force redevelopment in ATR, possibly due to hypophosphorylation of myosin-binding protein C and myosin light-chain protein 2a (immunoblot). Hypophosphorylation was related to multiple phosphorylation system abnormalities where protein kinase A regulatory subunits were downregulated, whereas autophosphorylation and expression of Ca(2+)-calmodulin-dependent protein kinase IIδ and protein phosphatase 1 activity were enhanced. Recovery of [Ca(2+)](i) transients and cell shortening occurred in parallel after ATR cessation. CONCLUSIONS Shortening of APD contributes to hypocontractility induced by 1-week ATR but accounts for it only partially. Additional contractility-suppressing mechanisms include I(CaL) current reduction, impaired subcellular Ca(2+) signal transmission, and altered myofilament function associated with abnormal myosin and myosin-associated protein phosphorylation. The complex mechanistic basis of the atrial hypocontractility associated with AF argues for upstream therapeutic targeting rather than interventions directed toward specific downstream pathophysiological derangements.
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Affiliation(s)
- Reza Wakili
- Department of Medicine and Research Center, Université de Montréal, Montreal, Quebec, Canada
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Belus A, Piroddi N, Ferrantini C, Tesi C, Cazorla O, Toniolo L, Drost M, Mearini G, Carrier L, Rossi A, Mugelli A, Cerbai E, van der Velden J, Poggesi C. Effects of chronic atrial fibrillation on active and passive force generation in human atrial myofibrils. Circ Res 2010; 107:144-52. [PMID: 20466979 DOI: 10.1161/circresaha.110.220699] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Chronic atrial fibrillation (cAF) is associated with atrial contractile dysfunction. Sarcomere remodeling may contribute to this contractile disorder. OBJECTIVE Here, we use single atrial myofibrils and fast solution switching techniques to directly investigate the impact of cAF on myofilament mechanical function eliminating changes induced by the arrhythmia in atrial myocytes membranes and extracellular components. Remodeling of sarcomere proteins potentially related to the observed mechanical changes is also investigated. METHODS AND RESULTS Myofibrils were isolated from atrial samples of 15 patients in sinus rhythm and 16 patients with cAF. Active tension changes following fast increase and decrease in [Ca(2+)] and the sarcomere length-passive tension relation were determined in the 2 groups of myofibrils. Compared to sinus rhythm myofibrils, cAF myofibrils showed (1) a reduction in maximum tension and in the rates of tension activation and relaxation; (2) an increase in myofilament Ca(2+) sensitivity; (3) a reduction in myofibril passive tension. The slow beta-myosin heavy chain isoform and the more compliant titin isoform N2BA were up regulated in cAF myofibrils. Phosphorylation of multiple myofilament proteins was increased in cAF as compared to sinus rhythm atrial myocardium. CONCLUSIONS Alterations in active and passive tension generation at the sarcomere level, explained by translational and post-translational changes of multiple myofilament proteins, are part of the contractile dysfunction of human cAF and may contribute to the self-perpetuation of the arrhythmia and the development of atrial dilatation.
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Affiliation(s)
- Alexandra Belus
- Center of Molecular Medicine, Department of Physiology, University of Florence, Italy
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García A, Eiras S, Parguiña AF, Alonso J, Rosa I, Salgado-Somoza A, Rico TY, Teijeira-Fernández E, González-Juanatey JR. High-resolution two-dimensional gel electrophoresis analysis of atrial tissue proteome reveals down-regulation of fibulin-1 in atrial fibrillation. Int J Cardiol 2010; 150:283-90. [PMID: 20451270 DOI: 10.1016/j.ijcard.2010.04.036] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Revised: 04/07/2010] [Accepted: 04/10/2010] [Indexed: 11/26/2022]
Abstract
BACKGROUND Atrial fibrillation (AF) is the most common cardiac arrhythmia found in clinical practice. We combined high-resolution two-dimensional gel electrophoresis (2-DE) and mass spectrometry (MS) to compare the atrial proteome of subjects with AF versus controls with sinus rhythm (SR). Our aim was to identify novel differentially regulated proteins that could be related to the development of the arrhythmia. METHODS Human atrial appendage tissue samples from patients undergoing heart surgery with AF or SR were analyzed by high-resolution 2-DE. Proteins of interest were identified by MS and validated by western blotting and inmunohistochemistry. RESULTS Our analysis allowed the detection of over 2300 protein spots per gel. Following differential image analysis, we found 22 spot differences between the AF and SR groups in the 4-7 isoelectric point range, leading to the identification of 15 differentially regulated proteins. The main group of proteins identified was that of heat shock proteins (HSPs), including TRAP-1, HspB3, HspΒ6 and AHA1. Some of the differences detected between AF and SR for the above proteins were due to post-translational modifications. In addition, we identified the structural protein fibulin-1 as down-regulated in atrial tissue from AF patients. CONCLUSIONS High-resolution 2-DE analysis of human atrial tissue revealed that AF is associated with changes in structural proteins and an important number of HSPs. The lower expression of the structural protein fibulin-1 in atrial tissue from AF patients might reflect the myocardial structural changes that take place in the arrhythmia.
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Affiliation(s)
- Angel García
- Departamento de Farmacoloxía, Facultade de Farmacia, Universidade de Santiago de Compostela, Santiago de Compostela, Spain.
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Greiser M, Neuberger HR, Harks E, El-Armouche A, Boknik P, de Haan S, Verheyen F, Verheule S, Schmitz W, Ravens U, Nattel S, Allessie MA, Dobrev D, Schotten U. Distinct contractile and molecular differences between two goat models of atrial dysfunction: AV block-induced atrial dilatation and atrial fibrillation. J Mol Cell Cardiol 2009; 46:385-94. [DOI: 10.1016/j.yjmcc.2008.11.012] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2008] [Revised: 10/21/2008] [Accepted: 11/03/2008] [Indexed: 11/24/2022]
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Hertelendi Z, Tóth A, Borbély A, Galajda Z, van der Velden J, Stienen GJM, Edes I, Papp Z. Oxidation of myofilament protein sulfhydryl groups reduces the contractile force and its Ca2+ sensitivity in human cardiomyocytes. Antioxid Redox Signal 2008; 10:1175-84. [PMID: 18331201 DOI: 10.1089/ars.2007.2014] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
This study sought to characterize the relation between the oxidation of protein sulfhydryl (SH) groups and Ca2+-activated force production in the human myocardium. Triton-permeabilized left ventricular cardiomyocytes from donor hearts were exposed to an oxidative (2,2'-dithiodipyridine, DTDP) agent in vitro, and the changes in isometric force, its Ca2+ sensitivity, the cross-bridge-sensitive rate constant of force redevelopment at saturating [Ca2+] (k(tr,max)), and protein SH oxidation were monitored. DTDP (0.1-10 mM for 2 min) oxidized the myocardial proteins and diminished the Ca2+-activated force with different concentration dependences (EC(50,SH) = 0.17 +/- 0.02 mM and EC(50,force) = 2.46 +/- 0.22 mM; mean +/- SEM). The application of 2.5 mM DTDP decreased the maximal Ca2+-activated force (to 64%), its Ca2+ sensitivity (DeltapCa(50) = 0.22 +/- 0.02), and the steepness of the Ca2+-force relation (n(Hill), from 2.01 +/- 0.08 to 1.76 +/- 0.08). These changes were paralleled by reductions in the free SH content of the proteins (to 15%) and in k(tr,max) (to 75%). SH-specific labeling identified SH oxidation of myosin light chain 1 and actin at DTDP concentrations at which the changes in the contractile parameters occurred. Our data suggest that SH oxidation in selected myofilament proteins diminishes the Ca2+-activated force and its Ca2+ sensitivity through an impaired Ca2+ regulation of the actin-myosin cycle in the human heart.
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Affiliation(s)
- Zita Hertelendi
- Division of Clinical Physiology, University of Debrecen, Debrecen, Hungary
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Hamdani N, Kooij V, van Dijk S, Merkus D, Paulus WJ, Remedios CD, Duncker DJ, Stienen GJM, van der Velden J. Sarcomeric dysfunction in heart failure. Cardiovasc Res 2007; 77:649-58. [PMID: 18055579 DOI: 10.1093/cvr/cvm079] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Sarcomeric dysfunction plays a central role in reduced cardiac pump function in heart failure. This review focuses on the alterations in sarcomeric proteins in diseased myocardium that range from altered isoform expression to post-translational protein changes such as proteolysis and phosphorylation. Recent studies in animal models of heart failure and human failing myocardium converge and indicate that sarcomeric dysfunction, including altered maximum force development, Ca(2+) sensitivity, and increased passive stiffness, largely originates from altered protein phosphorylation, caused by neurohumoral-induced alterations in the kinase-phosphatase balance inside the cardiomyocytes. Novel therapies, which specifically target phosphorylation sites within sarcomeric proteins or the kinases and phosphatases involved, might improve cardiac function in heart failure.
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Affiliation(s)
- Nazha Hamdani
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, van der Boechorststraat 7, Amsterdam, The Netherlands
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Dobrev D. 5-Hydroxytryptamine and atrial arrhythmogenesis: A “culprit mechanism” or bystander in patients with chronic atrial fibrillation? J Mol Cell Cardiol 2007; 42:51-3. [PMID: 17064728 DOI: 10.1016/j.yjmcc.2006.09.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Accepted: 09/21/2006] [Indexed: 11/29/2022]
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