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Chapman EA, Roberts DS, Tiambeng TN, Andrews J, Wang MD, Reasoner EA, Melby JA, Li BH, Kim D, Alpert AJ, Jin S, Ge Y. Structure and dynamics of endogenous cardiac troponin complex in human heart tissue captured by native nanoproteomics. Nat Commun 2023; 14:8400. [PMID: 38110393 PMCID: PMC10728164 DOI: 10.1038/s41467-023-43321-z] [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: 07/04/2023] [Accepted: 11/07/2023] [Indexed: 12/20/2023] Open
Abstract
Protein complexes are highly dynamic entities that display substantial diversity in their assembly, post-translational modifications, and non-covalent interactions, allowing them to play critical roles in various biological processes. The heterogeneity, dynamic nature, and low abundance of protein complexes in their native states present challenges to study using conventional structural biology techniques. Here we develop a native nanoproteomics strategy for the enrichment and subsequent native top-down mass spectrometry (nTDMS) analysis of endogenous cardiac troponin (cTn) complex directly from human heart tissue. The cTn complex is enriched and purified using peptide-functionalized superparamagnetic nanoparticles under non-denaturing conditions to enable the isotopic resolution of cTn complex, revealing their complex structure and assembly. Moreover, nTDMS elucidates the stoichiometry and composition of the cTn complex, localizes Ca2+ binding domains, defines cTn-Ca2+ binding dynamics, and provides high-resolution mapping of the proteoform landscape. This native nanoproteomics strategy opens a paradigm for structural characterization of endogenous native protein complexes.
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Affiliation(s)
- Emily A Chapman
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - David S Roberts
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Timothy N Tiambeng
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Jãán Andrews
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Man-Di Wang
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Emily A Reasoner
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Jake A Melby
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Brad H Li
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Donguk Kim
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | | | - Song Jin
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA.
| | - Ying Ge
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA.
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, 53705, USA.
- Human Proteomics Program, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53705, USA.
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Chapman EA, Roberts DS, Tiambeng TN, Andrews J, Wang MD, Reasoner EA, Melby JA, Li BH, Kim D, Alpert AJ, Jin S, Ge Y. Structure and dynamics of endogenous protein complexes in human heart tissue captured by native nanoproteomics. RESEARCH SQUARE 2023:rs.3.rs-3108087. [PMID: 37461709 PMCID: PMC10350235 DOI: 10.21203/rs.3.rs-3108087/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
Protein complexes are highly dynamic entities that display substantial diversity in their assembly, post-translational modifications, and non-covalent interactions, allowing them to play critical roles in various biological processes. The heterogeneity, dynamic nature, and low abundance of protein complexes in their native states present tremendous challenges to study using conventional structural biology techniques. Here we develop a "native nanoproteomics" strategy for the native enrichment and subsequent native top-down mass spectrometry (nTDMS) of low-abundance protein complexes. Specifically, we demonstrate the first comprehensive characterization of the structure and dynamics of cardiac troponin (cTn) complexes directly from human heart tissue. The endogenous cTn complex is effectively enriched and purified using peptide-functionalized superparamagnetic nanoparticles under non-denaturing conditions to enable the isotopic resolution of cTn complexes, revealing their complex structure and assembly. Moreover, nTDMS elucidates the stoichiometry and composition of the heterotrimeric cTn complex, localizes Ca2+ binding domains (II-IV), defines cTn-Ca2+ binding dynamics, and provides high-resolution mapping of the proteoform landscape. This native nanoproteomics strategy opens a new paradigm for structural characterization of low-abundance native protein complexes.
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Affiliation(s)
- Emily A. Chapman
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - David S. Roberts
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Timothy N. Tiambeng
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Jãán Andrews
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Man-Di Wang
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Emily A. Reasoner
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Jake A. Melby
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Brad H. Li
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Donguk Kim
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | | | - Song Jin
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Ying Ge
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA
- Human Proteomics Program, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA
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3
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Chapman EA, Roberts DS, Tiambeng TN, Andrews J, Wang MD, Reasoner EA, Melby JA, Li BH, Kim D, Alpert AJ, Jin S, Ge Y. Structure and dynamics of endogenous protein complexes in human heart tissue captured by native nanoproteomics. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.13.544817. [PMID: 37398031 PMCID: PMC10312745 DOI: 10.1101/2023.06.13.544817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Protein complexes are highly dynamic entities that display substantial diversity in their assembly, post-translational modifications, and non-covalent interactions, allowing them to play critical roles in various biological processes. The heterogeneity, dynamic nature, and low abundance of protein complexes in their native states present tremendous challenges to study using conventional structural biology techniques. Here we develop a "native nanoproteomics" strategy for the native enrichment and subsequent native top-down mass spectrometry (nTDMS) of low-abundance protein complexes. Specifically, we demonstrate the first comprehensive characterization of the structure and dynamics of cardiac troponin (cTn) complexes directly from human heart tissue. The endogenous cTn complex is effectively enriched and purified using peptide-functionalized superparamagnetic nanoparticles under non-denaturing conditions to enable the isotopic resolution of cTn complexes, revealing their complex structure and assembly. Moreover, nTDMS elucidates the stoichiometry and composition of the heterotrimeric cTn complex, localizes Ca2+ binding domains (II-IV), defines cTn-Ca2+ binding dynamics, and provides high-resolution mapping of the proteoform landscape. This native nanoproteomics strategy opens a new paradigm for structural characterization of low-abundance native protein complexes.
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Dewan S, Witayavanitkul N, Kumar M, Mayer BJ, Betancourt L, Cazorla O, de Tombe PP. Depressed myocardial cross-bridge cycling kinetics in a female guinea pig model of diastolic heart failure. J Gen Physiol 2023; 155:e202213288. [PMID: 37102986 PMCID: PMC10140646 DOI: 10.1085/jgp.202213288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 02/10/2023] [Accepted: 04/17/2023] [Indexed: 04/28/2023] Open
Abstract
Cardiac hypertrophy is associated with diastolic heart failure (DHF), a syndrome in which systolic function is preserved but cardiac filling dynamics are depressed. The molecular mechanisms underlying DHF and the potential role of altered cross-bridge cycling are poorly understood. Accordingly, chronic pressure overload was induced by surgically banding the thoracic ascending aorta (AOB) in ∼400 g female Dunkin Hartley guinea pigs (AOB); Sham-operated age-matched animals served as controls. Guinea pigs were chosen to avoid the confounding impacts of altered myosin heavy chain (MHC) isoform expression seen in other small rodent models. In vivo cardiac function was assessed by echocardiography; cardiac hypertrophy was confirmed by morphometric analysis. AOB resulted in left ventricle (LV) hypertrophy and compromised diastolic function with normal systolic function. Biochemical analysis revealed exclusive expression of β-MHC isoform in both sham control and AOB LVs. Myofilament function was assessed in skinned multicellular preparations, skinned single myocyte fragments, and single myofibrils prepared from frozen (liquid N2) LVs. The rates of force-dependent ATP consumption (tension-cost) and force redevelopment (Ktr), as well as myofibril relaxation time (Timelin) were significantly blunted in AOB, indicating reduced cross-bridge cycling kinetics. Maximum Ca2+ activated force development was significantly reduced in AOB myocytes, while no change in myofilament Ca2+ sensitivity was observed. Our results indicate blunted cross-bridge cycle in a β-MHC small animal DHF model. Reduced cross-bridge cycling kinetics may contribute, at least in part, to the development of DHF in larger mammals, including humans.
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Affiliation(s)
- Sukriti Dewan
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA
| | - Namthip Witayavanitkul
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA
| | - Mohit Kumar
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA
| | - Beth J Mayer
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA
| | - Lauren Betancourt
- Phymedexp INSERM, CNRS, University of Montpellier , Montpellier, France
| | - Olivier Cazorla
- Phymedexp INSERM, CNRS, University of Montpellier , Montpellier, France
| | - Pieter P de Tombe
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA
- Phymedexp INSERM, CNRS, University of Montpellier , Montpellier, France
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Valtonen J, Prajapati C, Cherian RM, Vanninen S, Ojala M, Leivo K, Heliö T, Koskenvuo J, Aalto-Setälä K. The Junctophilin-2 Mutation p.(Thr161Lys) Is Associated with Hypertrophic Cardiomyopathy Using Patient-Specific iPS Cardiomyocytes and Demonstrates Prolonged Action Potential and Increased Arrhythmogenicity. Biomedicines 2023; 11:1558. [PMID: 37371654 DOI: 10.3390/biomedicines11061558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 05/25/2023] [Accepted: 05/26/2023] [Indexed: 06/29/2023] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is one of the most common genetic cardiac diseases; it is primarily caused by mutations in sarcomeric genes. However, HCM is also associated with mutations in non-sarcomeric proteins and a Finnish founder mutation for HCM in non-sarcomeric protein junctophilin-2 (JPH2) has been identified. This study aimed at assessing the issue of modelling the rare Finnish founder mutation in cardiomyocytes (CMs) differentiated from iPSCs; therefore, presenting the same cardiac abnormalities observed in the patients. To explore the abnormal functions in JPH2-HCM, skin fibroblasts from a Finnish patient with JPH2 p.(Thr161Lys) were reprogrammed into iPSCs and further differentiated into CMs. As a control line, an isogenic counterpart was generated using the CRISPR/Cas9 genome editing method. Finally, iPSC-CMs were evaluated for the morphological and functional characteristics associated with JPH2 mutation. JPH2-hiPSC-CMs displayed key HCM hallmarks (cellular hypertrophy, multi-nucleation, sarcomeric disarray). Moreover, JPH2-hiPSC-CMs exhibit a higher degree of arrhythmia and longer action potential duration associated with slower inactivation of calcium channels. Functional evaluation supported clinical observations, with differences in beating characteristics when compared with isogenic-hiPSC-CMs. Thus, the iPSC-derived, disease-specific cardiomyocytes could serve as a translationally relevant platform to study genetic cardiac diseases.
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Affiliation(s)
- Joona Valtonen
- Heart Group, Faculty of Medicine and Health Technology, Tampere University, 33520 Tampere, Finland
| | - Chandra Prajapati
- Heart Group, Faculty of Medicine and Health Technology, Tampere University, 33520 Tampere, Finland
| | - Reeja Maria Cherian
- Heart Group, Faculty of Medicine and Health Technology, Tampere University, 33520 Tampere, Finland
| | - Sari Vanninen
- Tampere University Heart Hospital, 33520 Tampere, Finland
| | - Marisa Ojala
- Heart Group, Faculty of Medicine and Health Technology, Tampere University, 33520 Tampere, Finland
| | - Krista Leivo
- Heart and Lung Center, Helsinki University Hospital, University of Helsinki, 00290 Helsinki, Finland
| | - Tiina Heliö
- Heart and Lung Center, Helsinki University Hospital, University of Helsinki, 00290 Helsinki, Finland
| | | | - Katriina Aalto-Setälä
- Heart Group, Faculty of Medicine and Health Technology, Tampere University, 33520 Tampere, Finland
- Tampere University Heart Hospital, 33520 Tampere, Finland
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6
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Greenman AC, Diffee GM, Power AS, Wilkins GT, Gold OMS, Erickson JR, Baldi JC. Treadmill running increases the calcium sensitivity of myofilaments in diabetic rats. J Appl Physiol (1985) 2022; 132:1350-1360. [PMID: 35482324 DOI: 10.1152/japplphysiol.00785.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The cardiovascular benefits of regular exercise are unequivocal, yet patients with type 2 diabetes respond poorly to exercise due to a reduced cardiac reserve. The contractile response of diabetic cardiomyocytes to beta-adrenergic stimulation is attenuated, which may result in altered myofilament calcium sensitivity and post-translational modifications of cardiac troponin I (cTnI). Treadmill running increases myofilament calcium sensitivity in non‑diabetic rats, and thus we hypothesized that endurance training would increase calcium sensitivity of diabetic cardiomyocytes and alter site-specific phosphorylation of cTnI. Calcium sensitivity, or pCa50, was measured in Zucker Diabetic Fatty (ZDF) non-diabetic (nDM) and diabetic (DM) rat hearts after 8 weeks of either a sedentary (SED) or progressive treadmill running (TR) intervention. Skinned cardiomyocytes were connected to a capacitance-gauge transducer and a torque motor to measure force as a function of pCa (‑log[Ca2+]). Specific phospho-sites on cTnI and O‑GlcNAcylation were quantified by immunoblot and total protein phosphorylation by fluorescent gel staining (ProQ Diamond). The novel finding in this study was that training increased pCa50 in both DM and nDM cardiomyocytes (p = 0.009). Phosphorylation of cTnI amino acid residues Ser23/24, a crucial protein kinase A site, and Threonine (Thr)144, was lower in DM hearts, but there was no effect of training on site-specific phosphorylation. Additionally, total phosphorylation and O-GlcNAcylation levels were not different between SED and TR groups. These findings suggest that regular exercise may benefit the diabetic heart by specifically targeting myofilament contractile function.
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Affiliation(s)
- Angela Claire Greenman
- Department of Medicine, Otago Medical School, University of Otago, Dunedin, New Zealand.,Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,HeartOtago, University of Otago, Dunedin, New Zealand
| | - Gary M Diffee
- Department of Kinesiology, University of Wisconsin-Madison, Madison, WI
| | - Amelia S Power
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,HeartOtago, University of Otago, Dunedin, New Zealand
| | - Gerard T Wilkins
- Department of Medicine, Otago Medical School, University of Otago, Dunedin, New Zealand.,HeartOtago, University of Otago, Dunedin, New Zealand
| | - Olivia M S Gold
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,HeartOtago, University of Otago, Dunedin, New Zealand
| | - Jeffrey R Erickson
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,HeartOtago, University of Otago, Dunedin, New Zealand
| | - James C Baldi
- Department of Medicine, Otago Medical School, University of Otago, Dunedin, New Zealand.,HeartOtago, University of Otago, Dunedin, New Zealand
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Lin YS, Chang TH, Ho WC, Chang SF, Chen YL, Chang ST, Chen HC, Pan KL, Chen MC. Sarcomeres Morphology and Z-Line Arrangement Disarray Induced by Ventricular Premature Contractions through the Rac2/Cofilin Pathway. Int J Mol Sci 2021; 22:11244. [PMID: 34681906 PMCID: PMC8541677 DOI: 10.3390/ijms222011244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Revised: 10/11/2021] [Accepted: 10/12/2021] [Indexed: 11/17/2022] Open
Abstract
The most common ventricular premature contractions (VPCs) originate from the right ventricular outflow tract (RVOT), but the molecular mechanisms of altered cytoskeletons of VPC-induced cardiomyopathy remain unexplored. We created a RVOT bigeminy VPC pig model (n = 6 in each group). Echocardiography was performed. The histopathological alternations in the LV myocardium were analyzed, and next generation sequencing (NGS) and functional enrichment analyses were employed to identify the differentially expressed genes (DEGs) responsible for the histopathological alternations. Finally, a cell silencing model was used to confirm the key regulatory gene and pathway. VPC pigs had increased LV diameters in the 6-month follow-up period. A histological study showed more actin cytoskeleton disorganization and actin accumulation over intercalated disc, Z-line arrangement disarray, increased β-catenin expression, and cardiomyocyte enlargement in the LV myocardium of the VPC pigs compared to the control pigs. The NGS study showed actin cytoskeleton signaling, RhoGDI signaling, and signaling by Rho Family GTPases and ILK Signaling presented z-scores with same activation states. The expressions of Rac family small GTPase 2 (Rac2), the p-cofilin/cofilin ratio, and the F-actin/G-actin ratio were downregulated in the VPC group compared to the control group. Moreover, the intensity and number of actin filaments per cardiomyocyte were significantly decreased by Rac2 siRNA in the cell silencing model. Therefore, the Rac2/cofilin pathway was found to play a crucial role in the sarcomere morphology and Z-line arrangement disarray induced by RVOT bigeminy VPCs.
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Affiliation(s)
- Yu-Sheng Lin
- Division of Cardiology, Chang Gung Memorial Hospital, Chiayi 61363, Taiwan; (Y.-S.L.); (W.-C.H.); (S.-T.C.); (K.-L.P.)
- Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Taoyuan 33305, Taiwan
| | - Tzu-Hao Chang
- Graduate Institute of Biomedical Informatics, Taipei Medical University, Taipei 11031, Taiwan;
| | - Wan-Chun Ho
- Division of Cardiology, Chang Gung Memorial Hospital, Chiayi 61363, Taiwan; (Y.-S.L.); (W.-C.H.); (S.-T.C.); (K.-L.P.)
| | - Shun-Fu Chang
- Department of Medical Research and Development, Chiayi Chang Gung Memorial Hospital, Chiayi 61363, Taiwan;
| | - Yung-Lung Chen
- Division of Cardiology, Department of Internal Medicine, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung 83301, Taiwan; (Y.-L.C.); (H.-C.C.)
| | - Shih-Tai Chang
- Division of Cardiology, Chang Gung Memorial Hospital, Chiayi 61363, Taiwan; (Y.-S.L.); (W.-C.H.); (S.-T.C.); (K.-L.P.)
| | - Huang-Chung Chen
- Division of Cardiology, Department of Internal Medicine, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung 83301, Taiwan; (Y.-L.C.); (H.-C.C.)
| | - Kuo-Li Pan
- Division of Cardiology, Chang Gung Memorial Hospital, Chiayi 61363, Taiwan; (Y.-S.L.); (W.-C.H.); (S.-T.C.); (K.-L.P.)
| | - Mien-Cheng Chen
- Division of Cardiology, Department of Internal Medicine, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung 83301, Taiwan; (Y.-L.C.); (H.-C.C.)
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Caporizzo MA, Prosser BL. Need for Speed: The Importance of Physiological Strain Rates in Determining Myocardial Stiffness. Front Physiol 2021; 12:696694. [PMID: 34393820 PMCID: PMC8361601 DOI: 10.3389/fphys.2021.696694] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Accepted: 07/06/2021] [Indexed: 01/07/2023] Open
Abstract
The heart is viscoelastic, meaning its compliance is inversely proportional to the speed at which it stretches. During diastolic filling, the left ventricle rapidly expands at rates where viscoelastic forces impact ventricular compliance. In heart disease, myocardial viscoelasticity is often increased and can directly impede diastolic filling to reduce cardiac output. Thus, treatments that reduce myocardial viscoelasticity may provide benefit in heart failure, particularly for patients with diastolic heart failure. Yet, many experimental techniques either cannot or do not characterize myocardial viscoelasticity, and our understanding of the molecular regulators of viscoelasticity and its impact on cardiac performance is lacking. Much of this may stem from a reliance on techniques that either do not interrogate viscoelasticity (i.e., use non-physiological rates of strain) or techniques that compromise elements that contribute to viscoelasticity (i.e., skinned or permeabilized muscle preparations that compromise cytoskeletal integrity). Clinically, cardiac viscoelastic characterization is challenging, requiring the addition of strain-rate modulation during invasive hemodynamics. Despite these challenges, data continues to emerge demonstrating a meaningful contribution of viscoelasticity to cardiac physiology and pathology, and thus innovative approaches to characterize viscoelasticity stand to illuminate fundamental properties of myocardial mechanics and facilitate the development of novel therapeutic strategies.
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Affiliation(s)
- Matthew A Caporizzo
- Department of Physiology, Perelman School of Medicine, The University of Pennsylvania, Philadelphia, PA, United States
| | - Benjamin L Prosser
- Department of Physiology, Perelman School of Medicine, The University of Pennsylvania, Philadelphia, PA, United States
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Mahmud Z, Dhami PS, Rans C, Liu PB, Hwang PM. Dilated Cardiomyopathy Mutations and Phosphorylation disrupt the Active Orientation of Cardiac Troponin C. J Mol Biol 2021; 433:167010. [PMID: 33901537 DOI: 10.1016/j.jmb.2021.167010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 04/07/2021] [Accepted: 04/20/2021] [Indexed: 11/28/2022]
Abstract
Cardiac troponin (cTn) is made up of three subunits, cTnC, cTnI, and cTnT. The regulatory N-terminal domain of cTnC (cNTnC) controls cardiac muscle contraction in a calcium-dependent manner. We show that calcium-saturated cNTnC can adopt two different orientations, with the "active" orientation consistent with the 2020 cryo-EM structure of the activated cardiac thin filament by Yamada et al. Using solution NMR 15N R2 relaxation analysis, we demonstrate that the two domains of cTnC tumble independently (average R2 10 s-1), being connected by a flexible linker. However, upon addition of cTnI1-77, the complex tumbles as a rigid unit (R2 30 s-1). cTnI phosphomimetic mutants S22D/S23D, S41D/S43D and dilated cardiomyopathy- (DCM-)associated mutations cTnI K35Q, cTnC D75Y, and cTnC G159D destabilize the active orientation of cNTnC, with intermediate 15N R2 rates (R2 17-23 s-1). The active orientation of cNTnC is stabilized by the flexible tails of cTnI, cTnI1-37 and cTnI135-209. Surprisingly, when cTnC is incorporated into complexes lacking these tails (cTnC-cTnI38-134, cTnC-cTnT223-288, or cTnC-cTnI38-134-cTnT223-288), the cNTnC domain is still immobilized, revealing a new interaction between cNTnC and the IT-arm that stabilizes a "dormant" orientation. We propose that the calcium sensitivity of the cardiac troponin complex is regulated by an equilibrium between active and dormant orientations, which can be shifted through post-translational modifications or DCM-associated mutations.
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Affiliation(s)
- Zabed Mahmud
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Prabhpaul S Dhami
- Department of Medicine, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Caleb Rans
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Philip B Liu
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Peter M Hwang
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2R3, Canada; Department of Medicine, University of Alberta, Edmonton, AB T6G 2R3, Canada.
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10
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Meng T, Ren X, Chen X, Yu J, Agrimi J, Paolocci N, Gao WD. Anesthetic Agents Isoflurane and Propofol Decrease Maximal Ca 2+-Activated Force and Thus Contractility in the Failing Myocardium. J Pharmacol Exp Ther 2019; 371:615-623. [PMID: 31515443 DOI: 10.1124/jpet.119.259556] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 09/11/2019] [Indexed: 01/16/2023] Open
Abstract
In the normal heart, frequently used anesthetics such as isoflurane and propofol can reduce inotropy. However, the impact of these agents on the failing myocardium is unclear. Here, we examined whether and how isoflurane and propofol influence cardiac contractility in intact cardiac muscles from rats treated with monocrotaline to induce heart failure. We measured force and intracellular Ca2+ ([Ca2 +]i) in trabeculae from the right ventricles of the rats in the absence or presence of propofol or isoflurane. At low to moderate concentrations, both propofol and isoflurane dose-dependently depressed cardiac force generation in failing trabeculae without altering [Ca2+]i At high doses, propofol (but not isoflurane) also decreased amplitude of [Ca2+]i transients. During steady-state activation, both propofol and isoflurane impaired maximal Ca2+-activated force (Fmax) while increasing the amount of [Ca2+]i required for 50% of maximal activation (Ca50). These events occurred without apparent change in the Hill coefficient, suggesting no impairment of cooperativity. Exposing these same muscles to the anesthetics after fiber skinning resulted in a similar decrement in Fmax and rise in Ca50 but no change in the myofibrillar ATPase-Ca2+ relationship. Thus, our study demonstrates that challenging the failing myocardium with commonly used anesthetic agents such as propofol and isoflurane leads to reduced force development as a result of lowered myofilament responsiveness to Ca2+ SIGNIFICANCE STATEMENT: Commonly used anesthetics such as isoflurane and propofol can impair myocardial contractility in subjects with heart failure by lowering myofilament responsiveness to Ca2+. High doses of propofol can also reduce the overall amplitude of the intracellular Ca2+ transient. These findings may have important implications for the safety and quality of intra- and perioperative care of patients with heart failure and other cardiac disorders.
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Affiliation(s)
- Tao Meng
- Department of Anesthesiology, Qilu Hospital of Shandong University, Jinan, Shangdong, China (T.M., J.Y.); Department of Anesthesiology, China-Japan Friendship Hospital, Beijing, China (X.R.); Department of Cardiac Surgery, Tongji University Medical Center, Wuhan, China (X.C.); Division of Cardiology (J.A., N.P.) and Department of Anesthesiology and Critical Care Medicine (W.D.G.), Johns Hopkins University School of Medicine, Baltimore, Maryland, USA; and Department of Biomedical Sciences, University of Padova, Padova, Italy (N.P.)
| | - Xianfeng Ren
- Department of Anesthesiology, Qilu Hospital of Shandong University, Jinan, Shangdong, China (T.M., J.Y.); Department of Anesthesiology, China-Japan Friendship Hospital, Beijing, China (X.R.); Department of Cardiac Surgery, Tongji University Medical Center, Wuhan, China (X.C.); Division of Cardiology (J.A., N.P.) and Department of Anesthesiology and Critical Care Medicine (W.D.G.), Johns Hopkins University School of Medicine, Baltimore, Maryland, USA; and Department of Biomedical Sciences, University of Padova, Padova, Italy (N.P.)
| | - Xinzhong Chen
- Department of Anesthesiology, Qilu Hospital of Shandong University, Jinan, Shangdong, China (T.M., J.Y.); Department of Anesthesiology, China-Japan Friendship Hospital, Beijing, China (X.R.); Department of Cardiac Surgery, Tongji University Medical Center, Wuhan, China (X.C.); Division of Cardiology (J.A., N.P.) and Department of Anesthesiology and Critical Care Medicine (W.D.G.), Johns Hopkins University School of Medicine, Baltimore, Maryland, USA; and Department of Biomedical Sciences, University of Padova, Padova, Italy (N.P.)
| | - Jingui Yu
- Department of Anesthesiology, Qilu Hospital of Shandong University, Jinan, Shangdong, China (T.M., J.Y.); Department of Anesthesiology, China-Japan Friendship Hospital, Beijing, China (X.R.); Department of Cardiac Surgery, Tongji University Medical Center, Wuhan, China (X.C.); Division of Cardiology (J.A., N.P.) and Department of Anesthesiology and Critical Care Medicine (W.D.G.), Johns Hopkins University School of Medicine, Baltimore, Maryland, USA; and Department of Biomedical Sciences, University of Padova, Padova, Italy (N.P.)
| | - Jacopo Agrimi
- Department of Anesthesiology, Qilu Hospital of Shandong University, Jinan, Shangdong, China (T.M., J.Y.); Department of Anesthesiology, China-Japan Friendship Hospital, Beijing, China (X.R.); Department of Cardiac Surgery, Tongji University Medical Center, Wuhan, China (X.C.); Division of Cardiology (J.A., N.P.) and Department of Anesthesiology and Critical Care Medicine (W.D.G.), Johns Hopkins University School of Medicine, Baltimore, Maryland, USA; and Department of Biomedical Sciences, University of Padova, Padova, Italy (N.P.)
| | - Nazareno Paolocci
- Department of Anesthesiology, Qilu Hospital of Shandong University, Jinan, Shangdong, China (T.M., J.Y.); Department of Anesthesiology, China-Japan Friendship Hospital, Beijing, China (X.R.); Department of Cardiac Surgery, Tongji University Medical Center, Wuhan, China (X.C.); Division of Cardiology (J.A., N.P.) and Department of Anesthesiology and Critical Care Medicine (W.D.G.), Johns Hopkins University School of Medicine, Baltimore, Maryland, USA; and Department of Biomedical Sciences, University of Padova, Padova, Italy (N.P.)
| | - Wei Dong Gao
- Department of Anesthesiology, Qilu Hospital of Shandong University, Jinan, Shangdong, China (T.M., J.Y.); Department of Anesthesiology, China-Japan Friendship Hospital, Beijing, China (X.R.); Department of Cardiac Surgery, Tongji University Medical Center, Wuhan, China (X.C.); Division of Cardiology (J.A., N.P.) and Department of Anesthesiology and Critical Care Medicine (W.D.G.), Johns Hopkins University School of Medicine, Baltimore, Maryland, USA; and Department of Biomedical Sciences, University of Padova, Padova, Italy (N.P.)
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11
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Kagemoto T, Oyama K, Yamane M, Tsukamoto S, Kobirumaki-Shimozawa F, Li A, Dos Remedios C, Fukuda N, Ishiwata S. Sarcomeric Auto-Oscillations in Single Myofibrils From the Heart of Patients With Dilated Cardiomyopathy. Circ Heart Fail 2019; 11:e004333. [PMID: 29980594 DOI: 10.1161/circheartfailure.117.004333] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 05/31/2018] [Indexed: 01/30/2023]
Abstract
BACKGROUND Left ventricular wall motion is depressed in patients with dilated cardiomyopathy (DCM). However, whether or not the depressed left ventricular wall motion is caused by impairment of sarcomere dynamics remains to be fully clarified. METHODS AND RESULTS We analyzed the mechanical properties of single sarcomere dynamics during sarcomeric auto-oscillations (calcium spontaneous oscillatory contractions [Ca-SPOC]) that occurred at partial activation under the isometric condition in myofibrils from donor hearts and from patients with severe DCM (New York Heart Association classification III-IV). Ca-SPOC reproducibly occurred in the presence of 1 μmol/L free Ca2+ in both nonfailing and DCM myofibrils, and sarcomeres exhibited a saw-tooth waveform along single myofibrils composed of quick lengthening and slow shortening. The period of Ca-SPOC was longer in DCM myofibrils than in nonfailing myofibrils, in association with prolonged shortening time. Lengthening time was similar in both groups. Then, we performed Tn (troponin) exchange in myofibrils with a DCM-causing homozygous mutation (K36Q) in cTnI (cardiac TnI). On exchange with the Tn complex from healthy porcine ventricles, period, shortening time, and shortening velocity in cTnI-K36Q myofibrils became similar to those in Tn-reconstituted nonfailing myofibrils. Protein kinase A abbreviated period in both Tn-reconstituted nonfailing and cTnI-K36Q myofibrils, demonstrating acceleration of cross-bridge kinetics. CONCLUSIONS Sarcomere dynamics was found to be depressed under loaded conditions in DCM myofibrils because of impairment of thick-thin filament sliding. Thus, microscopic analysis of Ca-SPOC in human cardiac myofibrils is beneficial to systematically unveil the kinetic properties of single sarcomeres in various types of heart disease.
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Affiliation(s)
- Tatsuya Kagemoto
- Department of Physics, Faculty of Science and Engineering, Waseda University, Tokyo, Japan (T.K., M.Y., S.I.)
| | - Kotaro Oyama
- Department of Cell Physiology, The Jikei University School of Medicine, Tokyo, Japan (K.O., S.T., F.K.-S., N.F.)
| | - Mitsunori Yamane
- Department of Physics, Faculty of Science and Engineering, Waseda University, Tokyo, Japan (T.K., M.Y., S.I.)
| | - Seiichi Tsukamoto
- Department of Cell Physiology, The Jikei University School of Medicine, Tokyo, Japan (K.O., S.T., F.K.-S., N.F.)
| | - Fuyu Kobirumaki-Shimozawa
- Department of Cell Physiology, The Jikei University School of Medicine, Tokyo, Japan (K.O., S.T., F.K.-S., N.F.)
| | - Amy Li
- School of Medical Sciences, Bosch Institute, The University of Sydney, Australia (A.L., C.D.R.)
| | - Cristobal Dos Remedios
- School of Medical Sciences, Bosch Institute, The University of Sydney, Australia (A.L., C.D.R.)
| | - Norio Fukuda
- Department of Cell Physiology, The Jikei University School of Medicine, Tokyo, Japan (K.O., S.T., F.K.-S., N.F.).
| | - Shin'ichi Ishiwata
- Department of Physics, Faculty of Science and Engineering, Waseda University, Tokyo, Japan (T.K., M.Y., S.I.).
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12
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Blice-Baum AC, Guida MC, Hartley PS, Adams PD, Bodmer R, Cammarato A. As time flies by: Investigating cardiac aging in the short-lived Drosophila model. Biochim Biophys Acta Mol Basis Dis 2019; 1865:1831-1844. [PMID: 30496794 PMCID: PMC6527462 DOI: 10.1016/j.bbadis.2018.11.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 11/05/2018] [Accepted: 11/13/2018] [Indexed: 02/06/2023]
Abstract
Aging is associated with a decline in heart function across the tissue, cellular, and molecular levels. The risk of cardiovascular disease grows significantly over time, and as developed countries continue to see an increase in lifespan, the cost of cardiovascular healthcare for the elderly will undoubtedly rise. The molecular basis for cardiac function deterioration with age is multifaceted and not entirely clear, and there is a limit to what investigations can be performed on human subjects or mammalian models. Drosophila melanogaster has emerged as a useful model organism for studying aging in a short timeframe, benefitting from a suite of molecular and genetic tools and displaying highly conserved traits of cardiac senescence. Here, we discuss recent advances in our understanding of cardiac aging and how the fruit fly has aided in these developments.
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Affiliation(s)
| | - Maria Clara Guida
- Development, Aging and Regeneration Program, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA.
| | - Paul S Hartley
- Bournemouth University, Department of Life and Environmental Science, Talbot Campus, Fern Barrow, Poole, Dorset BH12 5BB, UK.
| | - Peter D Adams
- Development, Aging and Regeneration Program, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA.
| | - Rolf Bodmer
- Development, Aging and Regeneration Program, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA.
| | - Anthony Cammarato
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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13
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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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14
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Pabel S, Wagner S, Bollenberg H, Bengel P, Kovács Á, Schach C, Tirilomis P, Mustroph J, Renner A, Gummert J, Fischer T, Van Linthout S, Tschöpe C, Streckfuss-Bömeke K, Hasenfuss G, Maier LS, Hamdani N, Sossalla S. Empagliflozin directly improves diastolic function in human heart failure. Eur J Heart Fail 2018; 20:1690-1700. [PMID: 30328645 DOI: 10.1002/ejhf.1328] [Citation(s) in RCA: 138] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 08/30/2018] [Accepted: 09/03/2018] [Indexed: 12/19/2022] Open
Abstract
AIMS Empagliflozin, a clinically used oral antidiabetic drug that inhibits the sodium-dependent glucose co-transporter 2, has recently been evaluated for its cardiovascular safety. Surprisingly, empagliflozin reduced mortality and hospitalization for heart failure (HF) compared to placebo. However, the underlying mechanisms remain unclear. Therefore, our study aims to investigate whether empagliflozin may cause direct pleiotropic effects on the myocardium. METHODS AND RESULTS In order to assess possible direct myocardial effects of empagliflozin, we performed contractility experiments with in toto-isolated human systolic end-stage HF ventricular trabeculae. Empagliflozin significantly reduced diastolic tension, whereas systolic force was not changed. These results were confirmed in murine myocardium from diabetic and non-diabetic mice, suggesting independent effects from diabetic conditions. In human HF cardiomyocytes, empagliflozin did not influence calcium transient amplitude or diastolic calcium level. The mechanisms underlying the improved diastolic function were further elucidated by studying myocardial fibres from patients and rats with diastolic HF (HF with preserved ejection fraction, HFpEF). Empagliflozin beneficially reduced myofilament passive stiffness by enhancing phosphorylation levels of myofilament regulatory proteins. Intravenous injection of empagliflozin in anaesthetized HFpEF rats significantly improved diastolic function measured by echocardiography, while systolic contractility was unaffected. CONCLUSION Empagliflozin causes direct pleiotropic effects on the myocardium by improving diastolic stiffness and hence diastolic function. These effects were independent of diabetic conditions. Since pharmacological therapy of diastolic dysfunction and HF is an unmet need, our results provide a rationale for new translational studies and might also contribute to the understanding of the EMPA-REG OUTCOME trial.
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Affiliation(s)
- Steffen Pabel
- Department of Internal Medicine II, University Medical Center Regensburg, Regensburg, Germany.,Clinic for Cardiology & Pneumology, Georg-August University Goettingen, and German Center for Cardiovascular Research (DZHK), partner site Goettingen, Germany
| | - Stefan Wagner
- Department of Internal Medicine II, University Medical Center Regensburg, Regensburg, Germany
| | - Hannah Bollenberg
- Clinic for Cardiology & Pneumology, Georg-August University Goettingen, and German Center for Cardiovascular Research (DZHK), partner site Goettingen, Germany
| | - Philipp Bengel
- Clinic for Cardiology & Pneumology, Georg-August University Goettingen, and German Center for Cardiovascular Research (DZHK), partner site Goettingen, Germany
| | - Árpád Kovács
- Department of Systems Physiology, Ruhr University Bochum, Bochum, Germany
| | - Christian Schach
- Department of Internal Medicine II, University Medical Center Regensburg, Regensburg, Germany
| | - Petros Tirilomis
- Clinic for Cardiology & Pneumology, Georg-August University Goettingen, and German Center for Cardiovascular Research (DZHK), partner site Goettingen, Germany
| | - Julian Mustroph
- Department of Internal Medicine II, University Medical Center Regensburg, Regensburg, Germany
| | - André Renner
- Department of Thoracic, Cardiac and Vascular Surgery (Heart and Diabetes Center), North Rhine Westphalia, Bad Oeynhausen, Germany
| | - Jan Gummert
- Department of Thoracic, Cardiac and Vascular Surgery (Heart and Diabetes Center), North Rhine Westphalia, Bad Oeynhausen, Germany
| | - Thomas Fischer
- Clinic for Cardiology & Pneumology, Georg-August University Goettingen, and German Center for Cardiovascular Research (DZHK), partner site Goettingen, Germany
| | - Sophie Van Linthout
- Department of Internal Medicine and Cardiology, Charité University Medicine Berlin, Berlin-Brandenburg Center for Regenerative Therapies and German Center for Cardiovascular Research (DZHK), partner site Berlin, Berlin, Germany
| | - Carsten Tschöpe
- Department of Internal Medicine and Cardiology, Charité University Medicine Berlin, Berlin-Brandenburg Center for Regenerative Therapies and German Center for Cardiovascular Research (DZHK), partner site Berlin, Berlin, Germany
| | - Katrin Streckfuss-Bömeke
- Clinic for Cardiology & Pneumology, Georg-August University Goettingen, and German Center for Cardiovascular Research (DZHK), partner site Goettingen, Germany
| | - Gerd Hasenfuss
- Clinic for Cardiology & Pneumology, Georg-August University Goettingen, and German Center for Cardiovascular Research (DZHK), partner site Goettingen, Germany
| | - Lars S Maier
- Department of Internal Medicine II, University Medical Center Regensburg, Regensburg, Germany
| | - Nazha Hamdani
- Department of Systems Physiology, Ruhr University Bochum, Bochum, Germany
| | - Samuel Sossalla
- Department of Internal Medicine II, University Medical Center Regensburg, Regensburg, Germany.,Clinic for Cardiology & Pneumology, Georg-August University Goettingen, and German Center for Cardiovascular Research (DZHK), partner site Goettingen, Germany
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15
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Ji Y, Wang T, Zhang X, Li L, Li L, Guo Y, Yang B, Wang Y, Zhu T. Astragalosides increase the cardiac diastolic function and regulate the "Calcium sensing receptor-protein kinase C-protein phosphatase 1" pathway in rats with heart failure. Biomed Pharmacother 2018; 103:838-843. [PMID: 29710499 DOI: 10.1016/j.biopha.2018.04.111] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 04/11/2018] [Accepted: 04/13/2018] [Indexed: 02/06/2023] Open
Abstract
This study was designed to investigate the effects of astragalosides on cardiac diastolic function, and an emphasis was placed on the variation of the upstream molecular regulators of phospholamban. Chronic heart failure (CHF) rats were induced by ligaturing the left anterior coronary artery, and rats in the therapeutic groups were treated with either a 50 mg/kg dose of captopril, 10 mg/kg dose of astragalosides or 20 mg/kg dose of astragalosides. Four weeks after treatment, the ratio of the early and atrial peak filling velocities (E/A) and maximal slope diastolic pressure decrement (-dp/dt) both decreased in CHF rats (by 30.3% and 25.5%, respectively) and significantly increased in 20 mg/kg astragalosides and captopril-treated rats. The protein phosphatase-1 activity was lower in the 20 mg/kg astragalosides group than in the CHF group (0.22 vs 0.44, P < 0.01), and the inhibitor-1 levels in the astragalosides and captopril-treated groups were increased. Chronic heart failure increased expression of protein kinase C-α and calcium-sensing receptor, and these changes were attenuated by astragalosides therapy. Astragalosides restored the diastolic dysfunction of chronic heart failure rats, possibly by downregulation of calcium-sensing receptor and protein kinase C-α, which in turn augmented inhibitor-1 expression, reduced protein phosphatase-1 activity and increased phospholamban phosphorylation.
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Affiliation(s)
- Yansu Ji
- Affiliated Hospital of Logistics University of Chinese People's Armed Police Force, Tianjin 300162, China
| | - Tianqi Wang
- Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin 300193, China
| | - Xiting Zhang
- Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin 300193, China
| | - Lailai Li
- Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin 300193, China
| | - Liang Li
- Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Yisha Guo
- Affiliated Hospital of Logistics University of Chinese People's Armed Police Force, Tianjin 300162, China
| | - Bo Yang
- Affiliated Hospital of Logistics University of Chinese People's Armed Police Force, Tianjin 300162, China
| | - Yi Wang
- Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin 300193, China
| | - Tieliang Zhu
- Affiliated Hospital of Logistics University of Chinese People's Armed Police Force, Tianjin 300162, China.
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16
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Martin-Garrido A, Biesiadecki BJ, Salhi HE, Shaifta Y, Dos Remedios CG, Ayaz-Guner S, Cai W, Ge Y, Avkiran M, Kentish JC. Monophosphorylation of cardiac troponin-I at Ser-23/24 is sufficient to regulate cardiac myofibrillar Ca 2+ sensitivity and calpain-induced proteolysis. J Biol Chem 2018; 293:8588-8599. [PMID: 29669813 PMCID: PMC5986213 DOI: 10.1074/jbc.ra117.001292] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 04/04/2018] [Indexed: 01/03/2023] Open
Abstract
The acceleration of myocardial relaxation produced by β-adrenoreceptor stimulation is mediated in part by protein kinase A (PKA)-mediated phosphorylation of cardiac troponin-I (cTnI), which decreases myofibrillar Ca2+ sensitivity. Previous evidence suggests that phosphorylation of both Ser-23 and Ser-24 in cTnI is required for this Ca2+ desensitization. PKA-mediated phosphorylation also partially protects cTnI from proteolysis by calpain. Here we report that protein kinase D (PKD) phosphorylates only one serine of cTnI Ser-23/24. To explore the functional consequences of this monophosphorylation, we examined the Ca2+ sensitivity of force production and susceptibility of cTnI to calpain-mediated proteolysis when Ser-23/24 of cTnI in mouse cardiac myofibrils was nonphosphorylated, mono-phosphorylated, or bisphosphorylated (using sequential incubations in λ-phosphatase, PKD, and PKA, respectively). Phos-tag gels, Western blotting, and high-resolution MS revealed that PKD produced >90% monophosphorylation of cTnI, primarily at Ser-24, whereas PKA led to cTnI bisphosphorylation exclusively. PKD markedly decreased the Ca2+ sensitivity of force production in detergent-permeabilized ventricular trabeculae, whereas subsequent incubation with PKA produced only a small further fall of Ca2+ sensitivity. Unlike PKD, PKA also substantially phosphorylated myosin-binding protein-C and significantly accelerated cross-bridge kinetics (ktr). After phosphorylation by PKD or PKA, cTnI in isolated myofibrils was partially protected from calpain-mediated degradation. We conclude that cTnI monophosphorylation at Ser-23/24 decreases myofibrillar Ca2+ sensitivity and partially protects cTnI from calpain-induced proteolysis. In healthy cardiomyocytes, the basal monophosphorylation of cTnI may help tonically regulate myofibrillar Ca2+ sensitivity.
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Affiliation(s)
- Abel Martin-Garrido
- From the King's College London British Heart Foundation Centre of Excellence, School of Cardiovascular Medicine and Sciences, London SE1 7EH, United Kingdom
| | - Brandon J Biesiadecki
- the Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, Ohio State University, Columbus, Ohio 43210
| | - Hussam E Salhi
- the Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, Ohio State University, Columbus, Ohio 43210
| | - Yasin Shaifta
- From the King's College London British Heart Foundation Centre of Excellence, School of Cardiovascular Medicine and Sciences, London SE1 7EH, United Kingdom
| | - Cristobal G Dos Remedios
- the Bosch Institute, Discipline of Anatomy and Histology, University of Sydney, New South Wales 2006, Australia, and
| | | | - Wenxuan Cai
- the Departments of Cell and Regenerative Biology and.,Molecular and Cellular Pharmacology Training Program, and
| | - Ying Ge
- the Departments of Cell and Regenerative Biology and.,Human Proteomics Program, University of Wisconsin, Madison, Wisconsin 53705.,Chemistry
| | - Metin Avkiran
- From the King's College London British Heart Foundation Centre of Excellence, School of Cardiovascular Medicine and Sciences, London SE1 7EH, United Kingdom,
| | - Jonathan C Kentish
- From the King's College London British Heart Foundation Centre of Excellence, School of Cardiovascular Medicine and Sciences, London SE1 7EH, United Kingdom,
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17
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Dong J, Gao C, Liu J, Cao Y, Tian L. TSH inhibits SERCA2a and the PKA/PLN pathway in rat cardiomyocytes. Oncotarget 2018; 7:39207-39215. [PMID: 27206677 PMCID: PMC5129926 DOI: 10.18632/oncotarget.9393] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 04/16/2016] [Indexed: 11/25/2022] Open
Abstract
Elevated thyroid-stimulating hormone (TSH) levels often accompany impaired LV diastolic function and subtle systolic dysfunction in subclinical hypothyroidism (sHT). These cardiac dysfunctions are characterized by increases in mean aortic acceleration and pre-ejection/ejection time ratios. To explore the mechanism underlying these pathologies, we investigated the effects of TSH on sarcoplasmic reticulum calcium ATPase (SERCA2a) activity and expression in neonatal rat cardiomyocytes. TSH inhibited SERCA2a activity and expression by binding to TSH receptors in cardiomyocyte membranes and inhibiting the protein kinase A/phoshpolamban (PKA/PLN) signaling pathway. These results suggest that increases in serum TSH levels contribute to the development of cardiac diastolic and systolic dysfunction.
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Affiliation(s)
- Jiajia Dong
- Department of Endocrinology, Gansu Provincial Hospital, Lanzhou, Gansu, China
| | - Cuixia Gao
- Department of Ultrasonic Diagnosis, Gansu Provincial Hospital, Lanzhou, Gansu, China
| | - Jing Liu
- Department of Endocrinology, Gansu Provincial Hospital, Lanzhou, Gansu, China
| | - Yunshan Cao
- Department of Cardiology, Gansu Provincial Hospital, Lanzhou, Gansu, China
| | - Limin Tian
- Department of Endocrinology, Gansu Provincial Hospital, Lanzhou, Gansu, China
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18
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van Eldik W, den Adel B, Monshouwer-Kloots J, Salvatori D, Maas S, van der Made I, Creemers EE, Frank D, Frey N, Boontje N, van der Velden J, Steendijk P, Mummery C, Passier R, Beqqali A. Z-disc protein CHAPb induces cardiomyopathy and contractile dysfunction in the postnatal heart. PLoS One 2017; 12:e0189139. [PMID: 29206857 PMCID: PMC5716575 DOI: 10.1371/journal.pone.0189139] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 11/20/2017] [Indexed: 12/17/2022] Open
Abstract
Aims The Z-disc is a crucial structure of the sarcomere and is implicated in mechanosensation/transduction. Dysregulation of Z-disc proteins often result in cardiomyopathy. We have previously shown that the Z-disc protein Cytoskeletal Heart-enriched Actin-associated Protein (CHAP) is essential for cardiac and skeletal muscle development. Furthermore, the CHAP gene has been associated with atrial fibrillation in humans. Here, we studied the misregulated expression of CHAP isoforms in heart disease. Methods and results Mice that underwent transverse aortic constriction and calcineurin transgenic (Tg) mice, both models of experimental heart failure, displayed a significant increase in cardiac expression of fetal isoform CHAPb. To investigate whether increased expression of CHAPb postnatally is sufficient to induce cardiomyopathy, we generated CHAPb Tg mice under the control of the cardiac-specific αMHC promoter. CHAPb Tg mice displayed cardiac hypertrophy, interstitial fibrosis and enlargement of the left atrium at three months, which was more pronounced at the age of six months. Hypertrophy and fibrosis were confirmed by evidence of activation of the hypertrophic gene program (Nppa, Nppb, Myh7) and increased collagen expression, respectively. Connexin40 and 43 were downregulated in the left atrium, which was associated with delayed atrioventricular conduction. Tg hearts displayed both systolic and diastolic dysfunction partly caused by impaired sarcomere function evident from a reduced force generating capacity of single cardiomyocytes. This co-incided with activation of the actin signalling pathway leading to the formation of stress fibers. Conclusion This study demonstrated that the fetal isoform CHAPb initiates progression towards cardiac hypertrophy, which is accompanied by delayed atrioventricular conduction and diastolic dysfunction. Moreover, CHAP may be a novel therapeutic target or candidate gene for screening in cardiomyopathies and atrial fibrillation.
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Affiliation(s)
- Willemijn van Eldik
- Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, The Netherlands
- Interuniversity Cardiology Institute of the Netherlands (ICIN), Utrecht, The Netherlands
| | - Brigit den Adel
- Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Daniela Salvatori
- Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, The Netherlands
- Central Laboratory Animal Facility, Leiden University Medical Center, Leiden, The Netherlands
| | - Saskia Maas
- Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, The Netherlands
- Central Laboratory Animal Facility, Leiden University Medical Center, Leiden, The Netherlands
| | - Ingeborg van der Made
- Department of Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Esther E. Creemers
- Department of Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Derk Frank
- Department of Cardiology and Angiology, Universitätsklinikum Schleswig-Holstein (UKSH), University of Kiel, Kiel, Germany
| | - Norbert Frey
- Department of Cardiology and Angiology, Universitätsklinikum Schleswig-Holstein (UKSH), University of Kiel, Kiel, Germany
| | - Nicky Boontje
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands
| | - Jolanda van der Velden
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands
| | - Paul Steendijk
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Christine Mummery
- Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Robert Passier
- Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Abdelaziz Beqqali
- Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, The Netherlands
- Department of Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands
- * E-mail:
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Soetkamp D, Raedschelders K, Mastali M, Sobhani K, Bairey Merz CN, Van Eyk J. The continuing evolution of cardiac troponin I biomarker analysis: from protein to proteoform. Expert Rev Proteomics 2017; 14:973-986. [PMID: 28984473 DOI: 10.1080/14789450.2017.1387054] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
INTRODUCTION The troponin complex consists of three proteins that fundamentally couple excitation with contraction. Circulating cardiac-specific Troponin I (cTnI) serves as diagnostic biomarker tools for risk stratification of acute coronary syndromes and acute myocardial infarction (MI). Within the heart, cTnI oscillates between inactive and active conformations to either block or disinhibit actinomyosin formation. This molecular mechanism is fine-tuned through extensive protein modifications whose profiles are maladaptively altered with co-morbidities including hypertrophic cardiomyopathy, diabetes, and heart failure. Technological advances in analytical platforms over the last decade enable routine baseline cTnI analysis in patients without cardiovascular complications, and hold potential to expand cTnI readouts that include modified cTnI proteoforms. Areas covered: This review covers the current state, advances, and prospects of analytical platforms that now enable routine baseline cTnI analysis in patients. In parallel, improved mass spectrometry instrumentation and workflows already reveal an array of modified cTnI proteoforms with promising diagnostic implications. Expert commentary: New analytical capabilities provide clinicians and researchers with an opportunity to address important questions surrounding circulating cTnI in the improved diagnosis of specific patient cohorts. These techniques also hold considerable promise for new predictive and prescriptive applications for individualized profiling and improve patient care.
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Affiliation(s)
- Daniel Soetkamp
- a Heart Institute , Cedars-Sinai Medical Center , Los Angeles , CA , USA
| | - Koen Raedschelders
- a Heart Institute , Cedars-Sinai Medical Center , Los Angeles , CA , USA
| | - Mitra Mastali
- a Heart Institute , Cedars-Sinai Medical Center , Los Angeles , CA , USA
| | - Kimia Sobhani
- b Pathology and Laboratory Medicine , Cedars-Sinai Medical Center , Los Angeles , CA , USA
| | - C Noel Bairey Merz
- c Women's Heart Center , Cedars-Sinai Medical Center , Los Angeles , CA , USA
| | - Jennifer Van Eyk
- a Heart Institute , Cedars-Sinai Medical Center , Los Angeles , CA , USA
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Gresham KS, Stelzer JE. The contributions of cardiac myosin binding protein C and troponin I phosphorylation to β-adrenergic enhancement of in vivo cardiac function. J Physiol 2016; 594:669-86. [PMID: 26635197 DOI: 10.1113/jp270959] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 11/30/2015] [Indexed: 01/12/2023] Open
Abstract
KEY POINTS β-adrenergic stimulation increases cardiac myosin binding protein C (MyBP-C) and troponin I phosphorylation to accelerate pressure development and relaxation in vivo, although their relative contributions remain unknown. Using a novel mouse model lacking protein kinase A-phosphorylatable troponin I (TnI) and MyBP-C, we examined in vivo haemodynamic function before and after infusion of the β-agonist dobutamine. Mice expressing phospho-ablated MyBP-C displayed cardiac hypertrophy and prevented full acceleration of pressure development and relaxation in response to dobutamine, whereas expression of phosphor-ablated TnI alone had little effect on the acceleration of contractile function in response to dobutamine. Our data demonstrate that MyBP-C phosphorylation is the principal mediator of the contractile response to increased β-agonist stimulation in vivo. These results help us understand why MyBP-C dephosphorylation in the failing heart contributes to contractile dysfunction and decreased adrenergic reserve in response to acute stress. β-adrenergic stimulation plays a critical role in accelerating ventricular contraction and speeding relaxation to match cardiac output to changing circulatory demands. Two key myofilaments proteins, troponin I (TnI) and myosin binding protein-C (MyBP-C), are phosphorylated following β-adrenergic stimulation; however, their relative contributions to the enhancement of in vivo cardiac contractility are unknown. To examine the roles of TnI and MyBP-C phosphorylation in β-adrenergic-mediated enhancement of cardiac function, transgenic (TG) mice expressing non-phosphorylatable TnI protein kinase A (PKA) residues (i.e. serine to alanine substitution at Ser23/24; TnI(PKA-)) were bred with mice expressing non-phosphorylatable MyBP-C PKA residues (i.e. serine to alanine substitution at Ser273, Ser282 and Ser302; MyBPC(PKA-)) to generate a novel mouse model expressing non-phosphorylatable PKA residues in TnI and MyBP-C (DBL(PKA-)). MyBP-C dephosphorylation produced cardiac hypertrophy and increased wall thickness in MyBPC(PKA-) and DBL(PKA-) mice, and in vivo echocardiography and pressure-volume catheterization studies revealed impaired systolic function and prolonged diastolic relaxation compared to wild-type and TnI(PKA-) mice. Infusion of the β-agonist dobutamine resulted in accelerated rates of pressure development and relaxation in all mice; however, MyBPC(PKA-) and DBL(PKA-) mice displayed a blunted contractile response compared to wild-type and TnI(PKA-) mice. Furthermore, unanaesthesized MyBPC(PKA-) and DBL(PKA-) mice displayed depressed maximum systolic pressure in response to dobutamine as measured using implantable telemetry devices. Taken together, our data show that MyBP-C phosphorylation is a critical modulator of the in vivo acceleration of pressure development and relaxation as a result of enhanced β-adrenergic stimulation, and reduced MyBP-C phosphorylation may underlie depressed adrenergic reserve in heart failure.
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Affiliation(s)
- Kenneth S Gresham
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Julian E Stelzer
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
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21
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Panizzolo FA, Maiorana AJ, Naylor LH, Dembo LG, Lloyd DG, Green DJ, Rubenson J. Muscle size explains low passive skeletal muscle force in heart failure patients. PeerJ 2016; 4:e2447. [PMID: 27672504 PMCID: PMC5028761 DOI: 10.7717/peerj.2447] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Accepted: 08/14/2016] [Indexed: 01/23/2023] Open
Abstract
Background Alterations in skeletal muscle function and architecture have been linked to the compromised exercise capacity characterizing chronic heart failure (CHF). However, how passive skeletal muscle force is affected in CHF is not clear. Understanding passive force characteristics in CHF can help further elucidate the extent to which altered contractile properties and/or architecture might affect muscle and locomotor function. Therefore, the aim of this study was to investigate passive force in a single muscle for which non-invasive measures of muscle size and estimates of fiber force are possible, the soleus (SOL), both in CHF patients and age- and physical activity-matched control participants. Methods Passive SOL muscle force and size were obtained by means of a novel approach combining experimental data (dynamometry, electromyography, ultrasound imaging) with a musculoskeletal model. Results We found reduced passive SOL forces (∼30%) (at the same relative levels of muscle stretch) in CHF vs. healthy individuals. This difference was eliminated when force was normalized by physiological cross sectional area, indicating that reduced force output may be most strongly associated with muscle size. Nevertheless, passive force was significantly higher in CHF at a given absolute muscle length (non length-normalized) and likely explained by the shorter muscle slack lengths and optimal muscle lengths measured in CHF compared to the control participants. This later factor may lead to altered performance of the SOL in functional tasks such gait. Discussion These findings suggest introducing exercise rehabilitation targeting muscle hypertrophy and, specifically for the calf muscles, exercise that promotes muscle lengthening.
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Affiliation(s)
- Fausto Antonio Panizzolo
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, United States; The School of Sport Science, Exercise and Health, The University of Western Australia, Crawley, WA, Australia
| | - Andrew J Maiorana
- Advanced Heart Failure and Cardiac Transplant Service, Royal Perth Hospital, Perth, WA, Australia; School of Physiotherapy and Exercise Science, Curtin University, Perth, WA, Australia
| | - Louise H Naylor
- The School of Sport Science, Exercise and Health, The University of Western Australia , Crawley , WA , Australia
| | | | - David G Lloyd
- Centre for Musculoskeletal Research, Griffith Health Institute, Griffith University , Gold Coast , QLD , Australia
| | - Daniel J Green
- The School of Sport Science, Exercise and Health, The University of Western Australia, Crawley, WA, Australia; Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom
| | - Jonas Rubenson
- The School of Sport Science, Exercise and Health, The University of Western Australia, Crawley, WA, Australia; Biomechanics Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, PA, United States
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22
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Wen DT, Zheng L, Ni L, Wang H, Feng Y, Zhang M. The expression of CG9940 affects the adaptation of cardiac function, mobility, and lifespan to exercise in aging Drosophila. Exp Gerontol 2016; 83:6-14. [PMID: 27448710 DOI: 10.1016/j.exger.2016.07.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 06/15/2016] [Accepted: 07/14/2016] [Indexed: 02/06/2023]
Abstract
The CG9940 gene, which encodes the NAD(+) synthase protein in Drosophila, is conserved in human, zebra fish, and mosquito. NAD(+) synthase is a homodimer, which catalyzes the final step in de novo nicotinamide adenine dinucleotide (NAD(+)) biosynthesis, an amide transfer from either ammonia or glutamine to nicotinic acid adenine dinucleotide (NaAD). Both the CG9940 and exercise are closely relative to NAD(+) level, and NAD(+) plays important roles not only in energy metabolism and mitochondrial functions but also in aging. In our study, the expression of CG9940 was changed by UAS/GAL4 system in Drosophila. Flies were trained by a training device. Cardiac function was analyzed by M-mode traces, climbing index was measured through negative geotaxis assay, and lifespan was measured via lifespan assays. The important new findings from our present study included the following: (1) the expression of the CG9940 could affect cardiac function, mobility, and lifespan in Drosophila. Over-expression of the CG9940 gene had positive effects on Drosophila, such as enhanced aging cardiac output, reduced heart failure, delayed age-related mobility decline, and prolonged lifespan, but lower-expression of the CG9940 had negative effects on them. (2) Different expressions of the CG9940 resulted in different influences on the adaptation of cardiac function, mobility, and lifespan to exercise in aging Drosophila. Both normal-expression and over-expression of the CG9940 resulted in positive influences on the adaptation of cardiac functions, mobility, and lifespan to exercise in aging Drosophila such as exercise slowed age-related decline of cardiac function, mobility and extent of lifespan in these flies, while lower-expression of the CG9940 led to negative impacts on the adaptation of mobility and lifespan to exercise in Drosophila.
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Affiliation(s)
- Deng-Tai Wen
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, Chang Sha 410012, Hunan, China
| | - Lan Zheng
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, Chang Sha 410012, Hunan, China.
| | - Liu Ni
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, Chang Sha 410012, Hunan, China
| | - Hui Wang
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, Chang Sha 410012, Hunan, China
| | - Yue Feng
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, Chang Sha 410012, Hunan, China
| | - Min Zhang
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, Chang Sha 410012, Hunan, China
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Abstract
Prostaglandins are ubiquitous signaling molecules in the body that produce autocrine/paracrine effects on target cells in response to mechanical or chemical signals. In the heart, long-term exposure to prostaglandin (PG) F2α has been linked to the development of hypertrophy; however, there is no consensus on the acute effect of PGF2α. Our aim was to determine the response to exogenous PGF2α in isolated trabeculae from rat hearts. PGF2α (1 μM) increased both the Ca transients and the isometric stress in trabeculae, reaching steady state after 10-15 minutes, without altering the time course of Ca transient decay. The precursor of PGF2α, arachidonic acid, also stimulated a similar response. The positive inotropic effect of PGF2α was mediated through a protein kinase C signaling pathway that involved activation of the sarcolemmal Na/H exchanger. We also found that the slow force response to stretch was attenuated in the presence of PGF2α and by addition of indomethacin, a blocker of prostaglandin synthesis. In conclusion, PGF2α was positively inotropic when acutely applied to trabeculae and contributed to the increased Ca transients during the slow force response to stretch. Together, these data suggest that PGF2α is important in maintaining homeostasis during volume loading in healthy hearts.
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24
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Campbell KS, Sorrell VL. Cell- and molecular-level mechanisms contributing to diastolic dysfunction in HFpEF. J Appl Physiol (1985) 2015; 119:1228-32. [PMID: 25911687 DOI: 10.1152/japplphysiol.01168.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Accepted: 04/12/2015] [Indexed: 02/08/2023] Open
Abstract
Heart failure with preserved ejection fraction (HFpEF) is the default diagnosis for patients who have symptoms of heart failure, an ejection fraction >0.5, and evidence of diastolic dysfunction. The clinical condition, which was largely unrecognized 30 years ago, is now a major health problem and currently accounts for 50% of all patients with heart failure. Clinical studies show that patients with HFpEF exhibit increased passive stiffness of the ventricles and a slower rate of pressure decline during diastole. This review discusses some of the cell- and molecular-level mechanisms that contribute to these effects and focuses on data obtained using human samples. Collagen cross linking, modulation of protein kinase G-related pathways, Ca(2+) handling, and strain-dependent detachment of cross bridges are highlighted as potential factors that could be modulated to improve ventricular function in patients with HFpEF.
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Affiliation(s)
- Kenneth S Campbell
- Department of Physiology and Center for Muscle Biology, Linda and Jack Gill Heart Institute, University of Kentucky, Lexington, Kentucky; and
| | - Vincent L Sorrell
- Division of Cardiovascular Medicine, Linda and Jack Gill Heart Institute, University of Kentucky, Lexington, Kentucky
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25
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Stienen GJM. Pathomechanisms in heart failure: the contractile connection. J Muscle Res Cell Motil 2014; 36:47-60. [PMID: 25376563 DOI: 10.1007/s10974-014-9395-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Accepted: 10/20/2014] [Indexed: 01/07/2023]
Abstract
Heart failure is a multi-factorial progressive disease in which eventually the contractile performance of the heart is insufficient to meet the demands of the body, even at rest. A distinction can be made on the basis of the cause of the disease in genetic and acquired heart failure and at the functional level between systolic and diastolic heart failure. Here the basic determinants of contractile function of myocardial cells will be reviewed and an attempt will be made to elucidate their role in the development of heart failure. The following topics are addressed: the tension generating capacity, passive tension, the rate of tension development, the rate of ATP utilisation, calcium sensitivity of tension development, phosphorylation of contractile proteins, length dependent activation and stretch activation. The reduction in contractile performance during systole can be attributed predominantly to a loss of cardiomyocytes (necrosis), myocyte disarray and a decrease in myofibrillar density all resulting in a reduction in the tension generating capacity and likely also to a mismatch between energy supply and demand of the myocardium. This leads to a decline in the ejection fraction of the heart. Diastolic dysfunction can be attributed to fibrosis and an increase in titin stiffness which result in an increase in stiffness of the ventricular wall and hampers the filling of the heart with blood during diastole. A large number of post translation modifications of regulatory sarcomeric proteins influence myocardial function by altering calcium sensitivity of tension development. It is still unclear whether in concert these influences are adaptive or maladaptive during the disease process.
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Affiliation(s)
- G J M Stienen
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center, van der Boechorststraat 7, 1081 BT, Amsterdam, The Netherlands,
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26
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Wijnker PJM, Murphy AM, Stienen GJM, van der Velden J. Troponin I phosphorylation in human myocardium in health and disease. Neth Heart J 2014; 22:463-9. [PMID: 25200323 PMCID: PMC4188840 DOI: 10.1007/s12471-014-0590-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Cardiac troponin I (cTnI) is well known as a biomarker for the diagnosis of myocardial damage. However, because of its central role in the regulation of contraction and relaxation in heart muscle, cTnI may also be a potential target for the treatment of heart failure. Studies in rodent models of cardiac disease and human heart samples showed altered phosphorylation at various sites on cTnI (i.e. site-specific phosphorylation). This is caused by altered expression and/or activity of kinases and phosphatases during heart failure development. It is not known whether these (transient) alterations in cTnI phosphorylation are beneficial or detrimental. Knowledge of the effects of site-specific cTnI phosphorylation on cardiomyocyte contractility is therefore of utmost importance for the development of new therapeutic strategies in patients with heart failure. In this review we focus on the role of cTnI phosphorylation in the healthy heart upon activation of the beta-adrenergic receptor pathway (as occurs during increased stress and exercise) and as a modulator of the Frank-Starling mechanism. Moreover, we provide an overview of recent studies which aimed to reveal the functional consequences of changes in cTnI phosphorylation in cardiac disease.
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Affiliation(s)
- P J M Wijnker
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center, Van der Boechorststraat 7, 1081, BT, Amsterdam, the Netherlands,
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The cardiac-specific N-terminal region of troponin I positions the regulatory domain of troponin C. Proc Natl Acad Sci U S A 2014; 111:14412-7. [PMID: 25246568 DOI: 10.1073/pnas.1410775111] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The cardiac isoform of troponin I (cTnI) has a unique 31-residue N-terminal region that binds cardiac troponin C (cTnC) to increase the calcium sensitivity of the sarcomere. The interaction can be abolished by cTnI phosphorylation at Ser22 and Ser23, an important mechanism for regulating cardiac contractility. cTnC contains two EF-hand domains (the N and C domain of cTnC, cNTnC and cCTnC) connected by a flexible linker. Calcium binding to either domain favors an "open" conformation, exposing a large hydrophobic surface that is stabilized by target binding, cTnI[148-158] for cNTnC and cTnI[39-60] for cCTnC. We used multinuclear multidimensional solution NMR spectroscopy to study cTnI[1-73] in complex with cTnC. cTnI[39-60] binds to the hydrophobic face of cCTnC, stabilizing an alpha helix in cTnI[41-67] and a type VIII turn in cTnI[38-41]. In contrast, cTnI[1-37] remains disordered, although cTnI[19-37] is electrostatically tethered to the negatively charged surface of cNTnC (opposite its hydrophobic surface). The interaction does not directly affect the calcium binding affinity of cNTnC. However, it does fix the positioning of cNTnC relative to the rest of the troponin complex, similar to what was previously observed in an X-ray structure [Takeda S, et al. (2003) Nature 424(6944):35-41]. Domain positioning impacts the effective concentration of cTnI[148-158] presented to cNTnC, and this is how cTnI[19-37] indirectly modulates the calcium affinity of cNTnC within the context of the cardiac thin filament. Phosphorylation of cTnI at Ser22/23 disrupts domain positioning, explaining how it impacts many other cardiac regulatory mechanisms, like the Frank-Starling law of the heart.
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28
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Bening C, Mehlhorn U, Conzelmann LO, Stumpf N, Sikand A, Vahl CF. Contractile properties of the right atrial myofilaments in patients with myxomatous mitral valve degeneration. BMC Cardiovasc Disord 2014; 14:119. [PMID: 25227186 PMCID: PMC4169803 DOI: 10.1186/1471-2261-14-119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 09/09/2014] [Indexed: 11/26/2022] Open
Abstract
Background Myxomatous degeneration of the mitral valve is a common pathological finding in mitral valve surgery and the most common reason for severe mitral valve regurgitation. Considering the importance of right ventricular remodeling and global function after mitral valve surgery we tried to elucidate a possible association of myxomatous mitral valve and impairment of right atrial and ventricular function, which might have an impact on global ventricular performance after mitral valve surgery. Methods Right atrial tissue was harvested from 47 patients undergoing mitral valve surgery. We took the trabeculae from the right auricle, which was resected at the right auricle for implementation of extracorporal circulation. The tissue was skinned and prepared in a 24 h-lasting procedure to create small fibers for hinging them in the "muscle machine", an experimental set-up, created for pCa-force measurements. Results Patients without myxomatous mitral valve developed significantly more force (4.0 mN ± 0.8 mN) at the highest step of calcium concentration compared to 2.7 mN ± 0.4 mN in group of patients with myxomatous valve degeneration (p 0.03). Calcium sensitivity in the myxomatous valve group was at pCa 6.0 and in the non-myxomatous group at pCa 5. Furthermore we observed a significant difference in ejection fraction (EF) among the groups: 49% in the non-myxomatous group versus 57% in the myxomatous group (p 0.03). In the non-myxomatous group 5 patients had diastolic dysfunction grade I-II (22,7%), in group I 10 patients (40%). This was also significant (p 0.04). Conclusions Patients with myxomatous mitral valve degeneration seem to have reduced force capacities. Calcium sensitivity is higher compared to the non-myxomatous group, which might be a compensatory mechanism to cover the physiological demand. Furthermore we suggest a higher incidence of diastolic dysfunction in patients with myxomatous mitral valve degeneration, which might have an impact on ventricular remodeling after mitral valve surgery.
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Affiliation(s)
- Constanze Bening
- Department of Cardiothoracic and Vascular Surgery, Medical Centre of the Johannes Gutenberg University Mainz, Langenbeckstr,1, 55131 Mainz, Germany.
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Wijnker PJM, Sequeira V, Witjas-Paalberends ER, Foster DB, dos Remedios CG, Murphy AM, Stienen GJM, van der Velden J. Phosphorylation of protein kinase C sites Ser42/44 decreases Ca(2+)-sensitivity and blunts enhanced length-dependent activation in response to protein kinase A in human cardiomyocytes. Arch Biochem Biophys 2014; 554:11-21. [PMID: 24814372 PMCID: PMC4121669 DOI: 10.1016/j.abb.2014.04.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 04/29/2014] [Accepted: 04/29/2014] [Indexed: 10/25/2022]
Abstract
Protein kinase C (PKC)-mediated phosphorylation of troponin I (cTnI) at Ser42/44 is increased in heart failure. While studies in rodents demonstrated that PKC-mediated Ser42/44 phosphorylation decreases maximal force and ATPase activity, PKC incubation of human cardiomyocytes did not affect maximal force. We investigated whether Ser42/44 pseudo-phosphorylation affects force development and ATPase activity using troponin exchange in human myocardium. Additionally, we studied if pseudo-phosphorylated Ser42/44 modulates length-dependent activation of force, which is regulated by protein kinase A (PKA)-mediated cTnI-Ser23/24 phosphorylation. Isometric force was measured in membrane-permeabilized cardiomyocytes exchanged with human recombinant wild-type troponin or troponin mutated at Ser42/44 or Ser23/24 into aspartic acid (D) or alanine (A) to mimic phosphorylation and dephosphorylation, respectively. In troponin-exchanged donor cardiomyocytes experiments were repeated after PKA incubation. ATPase activity was measured in troponin-exchanged cardiac muscle strips. Compared to wild-type, 42D/44D decreased Ca(2+)-sensitivity without affecting maximal force in failing and donor cardiomyocytes. In donor myocardium, 42D/44D did not affect maximal ATPase activity or tension cost. Interestingly, 42D/44D blunted the length-dependent increase in Ca(2+)-sensitivity induced upon PKA-mediated phosphorylation. Since the drop in Ca(2+)-sensitivity at physiological Ca(2+)-concentrations is relatively large phosphorylation of Ser42/44 may result in a decrease of force and associated ATP utilization in the human heart.
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Affiliation(s)
- Paul J M Wijnker
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands; Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
| | - Vasco Sequeira
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands.
| | - E Rosalie Witjas-Paalberends
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands.
| | - D Brian Foster
- Department of Pediatrics/Division of Cardiology, Johns Hopkins University School of Medicine, Ross Bldg 1144/720 Rutland Avenue, Baltimore, MD 21205, USA.
| | | | - Anne M Murphy
- Department of Pediatrics/Division of Cardiology, Johns Hopkins University School of Medicine, Ross Bldg 1144/720 Rutland Avenue, Baltimore, MD 21205, USA.
| | - Ger J M Stienen
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands; Department of Physics and Astronomy, VU University, Amsterdam, The Netherlands.
| | - Jolanda van der Velden
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands; ICIN-Netherlands Heart Institute, Utrecht, The Netherlands.
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Rain S, Bos DDSG, Handoko ML, Westerhof N, Stienen G, Ottenheijm C, Goebel M, Dorfmüller P, Guignabert C, Humbert M, Bogaard HJ, Remedios CD, Saripalli C, Hidalgo CG, Granzier HL, Vonk-Noordegraaf A, van der Velden J, de Man FS. Protein changes contributing to right ventricular cardiomyocyte diastolic dysfunction in pulmonary arterial hypertension. J Am Heart Assoc 2014; 3:e000716. [PMID: 24895160 PMCID: PMC4309054 DOI: 10.1161/jaha.113.000716] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Background Right ventricular (RV) diastolic function is impaired in patients with pulmonary arterial hypertension (PAH). Our previous study showed that elevated cardiomyocyte stiffness and myofilament Ca2+ sensitivity underlie diastolic dysfunction in PAH. This study investigates protein modifications contributing to cellular diastolic dysfunction in PAH. Methods and Results RV samples from PAH patients undergoing heart‐lung transplantation were compared to non‐failing donors (Don). Titin stiffness contribution to RV diastolic dysfunction was determined by Western‐blot analyses using antibodies to protein‐kinase‐A (PKA), Cα (PKCα) and Ca2+/calmoduling‐dependent‐kinase (CamKIIδ) titin and phospholamban (PLN) phosphorylation sites: N2B (Ser469), PEVK (Ser170 and Ser26), and PLN (Thr17), respectively. PKA and PKCα sites were significantly less phosphorylated in PAH compared with donors (P<0.0001). To test the functional relevance of PKA‐, PKCα‐, and CamKIIδ‐mediated titin phosphorylation, we measured the stiffness of single RV cardiomyocytes before and after kinase incubation. PKA significantly decreased PAH RV cardiomyocyte diastolic stiffness, PKCα further increased stiffness while CamKIIδ had no major effect. CamKIIδ activation was determined indirectly by measuring PLN Thr17phosphorylation level. No significant changes were found between the groups. Myofilament Ca2+ sensitivity is mediated by sarcomeric troponin I (cTnI) phosphorylation. We observed increased unphosphorylated cTnI in PAH compared with donors (P<0.05) and reduced PKA‐mediated cTnI phosphorylation (Ser22/23) (P<0.001). Finally, alterations in Ca2+‐handling proteins contribute to RV diastolic dysfunction due to insufficient diastolic Ca2+ clearance. PAH SERCA2a levels and PLN phosphorylation were significantly reduced compared with donors (P<0.05). Conclusions Increased titin stiffness, reduced cTnI phosphorylation, and altered levels of phosphorylation of Ca2+ handling proteins contribute to RV diastolic dysfunction in PAH.
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Affiliation(s)
- Silvia Rain
- Department of Pulmonology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., D.S.G.B., N.W., H.J.B., A.V.N., F.S.M.) Department of Physiology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., L.H., N.W., G.S., C.O., M.G., J.V., F.S.M.)
| | - Denielli da Silva Goncalves Bos
- Department of Pulmonology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., D.S.G.B., N.W., H.J.B., A.V.N., F.S.M.)
| | - M Louis Handoko
- Department of Physiology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., L.H., N.W., G.S., C.O., M.G., J.V., F.S.M.) Department of Cardiology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (L.H.)
| | - Nico Westerhof
- Department of Pulmonology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., D.S.G.B., N.W., H.J.B., A.V.N., F.S.M.) Department of Physiology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., L.H., N.W., G.S., C.O., M.G., J.V., F.S.M.)
| | - Ger Stienen
- Department of Physiology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., L.H., N.W., G.S., C.O., M.G., J.V., F.S.M.) Department of Physics and Astronomy, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (G.S.)
| | - Coen Ottenheijm
- Department of Physiology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., L.H., N.W., G.S., C.O., M.G., J.V., F.S.M.)
| | - Max Goebel
- Department of Physiology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., L.H., N.W., G.S., C.O., M.G., J.V., F.S.M.)
| | - Peter Dorfmüller
- Faculté de Médecine, Université Paris-Sud, Le Kremlin-Bicêtre, France (P.D., C.G., M.H.) Inserm U999, LabEx LERMIT, Centre Chirurgical Marie Lannelongue, Le Plessis Robinson, France (P.D., C.G., M.H.)
| | - Christophe Guignabert
- Faculté de Médecine, Université Paris-Sud, Le Kremlin-Bicêtre, France (P.D., C.G., M.H.) Inserm U999, LabEx LERMIT, Centre Chirurgical Marie Lannelongue, Le Plessis Robinson, France (P.D., C.G., M.H.)
| | - Marc Humbert
- Faculté de Médecine, Université Paris-Sud, Le Kremlin-Bicêtre, France (P.D., C.G., M.H.) Inserm U999, LabEx LERMIT, Centre Chirurgical Marie Lannelongue, Le Plessis Robinson, France (P.D., C.G., M.H.) Service d'Anatomie Pathologique, Centre Chirurgical Marie Lannelongue, Le Plessis Robinson, France (M.H.) Assistance Publique-Hôspitaux de Paris, Service de Pneumologie, Département Hôspital Universitaire, Thorax innovation, (DHU-TORINO), Hôpital Bicêtre, France (M.H.)
| | - Harm-Jan Bogaard
- Department of Pulmonology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., D.S.G.B., N.W., H.J.B., A.V.N., F.S.M.)
| | - Cris Dos Remedios
- Muscle Research Unit, Discipline of Anatomy & Histology, Bosch Institute, The University of Sydney, Sydney, Australia (C.R.)
| | - Chandra Saripalli
- Sarver Molecular Cardiovascular Research Program, Department of Physiology, University of Arizona, Tucson, AZ, The Netherlands (C.S., C.G.H., H.L.G.)
| | - Carlos G Hidalgo
- Sarver Molecular Cardiovascular Research Program, Department of Physiology, University of Arizona, Tucson, AZ, The Netherlands (C.S., C.G.H., H.L.G.)
| | - Henk L Granzier
- Sarver Molecular Cardiovascular Research Program, Department of Physiology, University of Arizona, Tucson, AZ, The Netherlands (C.S., C.G.H., H.L.G.)
| | - Anton Vonk-Noordegraaf
- Department of Pulmonology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., D.S.G.B., N.W., H.J.B., A.V.N., F.S.M.)
| | - Jolanda van der Velden
- Department of Physiology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., L.H., N.W., G.S., C.O., M.G., J.V., F.S.M.) ICIN - The Netherlands Heart Institute, Amsterdam, The Netherlands (J.V.)
| | - Frances S de Man
- Department of Pulmonology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., D.S.G.B., N.W., H.J.B., A.V.N., F.S.M.) Department of Physiology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., L.H., N.W., G.S., C.O., M.G., J.V., F.S.M.)
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Segers VFM, De Keulenaer GW. Pathophysiology of diastolic dysfunction in chronic heart failure. Future Cardiol 2014; 9:711-20. [PMID: 24020672 DOI: 10.2217/fca.13.53] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Chronic heart failure is a disease with high morbidity and mortality, and its incidence is increasing rapidly worldwide. New therapies are needed that can halt or even reverse the progression of heart failure, but little progress has been made in the last 20 years. This is partly due to the fact that chronic heart failure is a heterogeneous disease with many different etiologies and clinical phenotypes. At present, a pathophysiological concept to unify these different phenotypes is missing. A prominent pathophysiological feature of chronic heart failure is diastolic dysfunction, which is almost universally present in heart failure patients. This review will examine the role and mechanisms of diastolic dysfunction in heart failure. We will study diastolic dysfunction at different levels of complexity of organization: the cardiovascular system, the heart as an organ, the myocardium as a tissue, the myocyte as a cell and the molecular aspects of diastolic dysfunction.
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Affiliation(s)
- Vincent F M Segers
- University of Antwerp, Universiteitsplein 1, Campus Drie Eiken, Bldg T, 2nd Floor, 2610 Wilrijk, Belgium
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32
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Alibhai FJ, Tsimakouridze EV, Chinnappareddy N, Wright DC, Billia F, O'Sullivan ML, Pyle WG, Sole MJ, Martino TA. Short-term disruption of diurnal rhythms after murine myocardial infarction adversely affects long-term myocardial structure and function. Circ Res 2014; 114:1713-22. [PMID: 24687134 DOI: 10.1161/circresaha.114.302995] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
RATIONALE Patients in intensive care units are disconnected from their natural environment. Synchrony between environmental diurnal rhythms and intracellular circadian rhythms is essential for normal organ biology; disruption causes pathology. Whether disturbing rhythms after myocardial infarction (MI) exacerbates long-term myocardial dysfunction is not known. OBJECTIVE Short-term diurnal rhythm disruption immediately after MI impairs remodeling and adversely affects long-term cardiac structure and function in a murine model. METHODS AND RESULTS Mice were infarcted by left anterior descending coronary artery ligation (MI model) within a 3-hour time window, randomized to either a normal diurnal or disrupted environment for 5 days, and then maintained under normal diurnal conditions. Initial infarct size was identical. Short-term diurnal disruption adversely affected body metabolism and altered early innate immune responses. In the first 5 days, crucial for scar formation, there were significant differences in cardiac myeloperoxidase, cytokines, neutrophil, and macrophage infiltration. Homozygous clock mutant mice exhibited altered infiltration after MI, consistent with circadian mechanisms underlying innate immune responses crucial for scar formation. In the proliferative phase, 1 week after MI, this led to significantly less blood vessel formation in the infarct region of disrupted mice; by day 14, echocardiography showed increased left ventricular dilation and infarct expansion. These differences continued to evolve with worse cardiac structure and function by 8 weeks after MI. CONCLUSIONS Diurnal rhythm disruption immediately after MI impaired healing and exacerbated maladaptive cardiac remodeling. These preclinical findings suggest that disrupted diurnal rhythms such as found in modern intensive care unit environments may adversely affect long-term patient outcome.
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Affiliation(s)
- Faisal J Alibhai
- From the Cardiovascular Research Group, Department of Biomedical Sciences (F.J.A., E.V.T., N.C., W.G.P., T.A.M.), Department of Human Health and Nutritional Sciences (D.C.W.), and Department of Clinical Studies (M.L.O.), University of Guelph, Guelph, Ontario, Canada; and Division of Cardiology, Peter Munk Cardiac Centre, University Health Network, Toronto, Ontario, Canada (F.B., M.J.S.)
| | - Elena V Tsimakouridze
- From the Cardiovascular Research Group, Department of Biomedical Sciences (F.J.A., E.V.T., N.C., W.G.P., T.A.M.), Department of Human Health and Nutritional Sciences (D.C.W.), and Department of Clinical Studies (M.L.O.), University of Guelph, Guelph, Ontario, Canada; and Division of Cardiology, Peter Munk Cardiac Centre, University Health Network, Toronto, Ontario, Canada (F.B., M.J.S.)
| | - Nirmala Chinnappareddy
- From the Cardiovascular Research Group, Department of Biomedical Sciences (F.J.A., E.V.T., N.C., W.G.P., T.A.M.), Department of Human Health and Nutritional Sciences (D.C.W.), and Department of Clinical Studies (M.L.O.), University of Guelph, Guelph, Ontario, Canada; and Division of Cardiology, Peter Munk Cardiac Centre, University Health Network, Toronto, Ontario, Canada (F.B., M.J.S.)
| | - David C Wright
- From the Cardiovascular Research Group, Department of Biomedical Sciences (F.J.A., E.V.T., N.C., W.G.P., T.A.M.), Department of Human Health and Nutritional Sciences (D.C.W.), and Department of Clinical Studies (M.L.O.), University of Guelph, Guelph, Ontario, Canada; and Division of Cardiology, Peter Munk Cardiac Centre, University Health Network, Toronto, Ontario, Canada (F.B., M.J.S.)
| | - Filio Billia
- From the Cardiovascular Research Group, Department of Biomedical Sciences (F.J.A., E.V.T., N.C., W.G.P., T.A.M.), Department of Human Health and Nutritional Sciences (D.C.W.), and Department of Clinical Studies (M.L.O.), University of Guelph, Guelph, Ontario, Canada; and Division of Cardiology, Peter Munk Cardiac Centre, University Health Network, Toronto, Ontario, Canada (F.B., M.J.S.)
| | - M Lynne O'Sullivan
- From the Cardiovascular Research Group, Department of Biomedical Sciences (F.J.A., E.V.T., N.C., W.G.P., T.A.M.), Department of Human Health and Nutritional Sciences (D.C.W.), and Department of Clinical Studies (M.L.O.), University of Guelph, Guelph, Ontario, Canada; and Division of Cardiology, Peter Munk Cardiac Centre, University Health Network, Toronto, Ontario, Canada (F.B., M.J.S.)
| | - W Glen Pyle
- From the Cardiovascular Research Group, Department of Biomedical Sciences (F.J.A., E.V.T., N.C., W.G.P., T.A.M.), Department of Human Health and Nutritional Sciences (D.C.W.), and Department of Clinical Studies (M.L.O.), University of Guelph, Guelph, Ontario, Canada; and Division of Cardiology, Peter Munk Cardiac Centre, University Health Network, Toronto, Ontario, Canada (F.B., M.J.S.)
| | - Michael J Sole
- From the Cardiovascular Research Group, Department of Biomedical Sciences (F.J.A., E.V.T., N.C., W.G.P., T.A.M.), Department of Human Health and Nutritional Sciences (D.C.W.), and Department of Clinical Studies (M.L.O.), University of Guelph, Guelph, Ontario, Canada; and Division of Cardiology, Peter Munk Cardiac Centre, University Health Network, Toronto, Ontario, Canada (F.B., M.J.S.)
| | - Tami A Martino
- From the Cardiovascular Research Group, Department of Biomedical Sciences (F.J.A., E.V.T., N.C., W.G.P., T.A.M.), Department of Human Health and Nutritional Sciences (D.C.W.), and Department of Clinical Studies (M.L.O.), University of Guelph, Guelph, Ontario, Canada; and Division of Cardiology, Peter Munk Cardiac Centre, University Health Network, Toronto, Ontario, Canada (F.B., M.J.S.).
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33
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Wijnker PJM, Sequeira V, Foster DB, Li Y, Dos Remedios CG, Murphy AM, Stienen GJM, van der Velden J. Length-dependent activation is modulated by cardiac troponin I bisphosphorylation at Ser23 and Ser24 but not by Thr143 phosphorylation. Am J Physiol Heart Circ Physiol 2014; 306:H1171-81. [PMID: 24585778 DOI: 10.1152/ajpheart.00580.2013] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Frank-Starling's law reflects the ability of the heart to adjust the force of its contraction to changes in ventricular filling, a property based on length-dependent myofilament activation (LDA). The threonine at amino acid 143 of cardiac troponin I (cTnI) is prerequisite for the length-dependent increase in Ca(2+) sensitivity. Thr143 is a known target of protein kinase C (PKC) whose activity is increased in cardiac disease. Thr143 phosphorylation may modulate length-dependent myofilament activation in failing hearts. Therefore, we investigated if pseudo-phosphorylation at Thr143 modulates length dependence of force using troponin exchange experiments in human cardiomyocytes. In addition, we studied effects of protein kinase A (PKA)-mediated cTnI phosphorylation at Ser23/24, which has been reported to modulate LDA. Isometric force was measured at various Ca(2+) concentrations in membrane-permeabilized cardiomyocytes exchanged with recombinant wild-type (WT) troponin or troponin mutated at the PKC site Thr143 or Ser23/24 into aspartic acid (D) or alanine (A) to mimic phosphorylation and dephosphorylation, respectively. In troponin-exchanged donor cardiomyocytes experiments were repeated after incubation with exogenous PKA. Pseudo-phosphorylation of Thr143 increased myofilament Ca(2+) sensitivity compared with WT without affecting LDA in failing and donor cardiomyocytes. Subsequent PKA treatment enhanced the length-dependent shift in Ca(2+) sensitivity after WT and 143D exchange. Exchange with Ser23/24 variants demonstrated that pseudo-phosphorylation of both Ser23 and Ser24 is needed to enhance the length-dependent increase in Ca(2+) sensitivity. cTnI pseudo-phosphorylation did not alter length-dependent changes in maximal force. Thus phosphorylation at Thr143 enhances myofilament Ca(2+) sensitivity without affecting LDA, while Ser23/24 bisphosphorylation is needed to enhance the length-dependent increase in myofilament Ca(2+) sensitivity.
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Affiliation(s)
- Paul J M Wijnker
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands
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34
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Heart failure in congenital heart disease: the role of genes and hemodynamics. Pflugers Arch 2014; 466:1025-35. [DOI: 10.1007/s00424-014-1447-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Accepted: 01/07/2014] [Indexed: 12/28/2022]
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35
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Yar S, Monasky MM, Solaro RJ. Maladaptive modifications in myofilament proteins and triggers in the progression to heart failure and sudden death. Pflugers Arch 2014; 466:1189-97. [PMID: 24488009 DOI: 10.1007/s00424-014-1457-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Revised: 01/16/2014] [Accepted: 01/19/2014] [Indexed: 12/25/2022]
Abstract
In this review, we address the following question: Are modifications at the level of sarcomeric proteins in acquired heart failure early inducers of altered cardiac dynamics and signaling leading to remodeling and progression to decompensation? There is no doubt that most inherited cardiomyopathies are caused by mutations in proteins of the sarcomere. We think this linkage indicates that early changes at the level of the sarcomeres in acquired cardiac disorders may be significant in triggering the progression to failure. We consider evidence that there are rate-limiting mechanisms downstream of the trigger event of Ca(2+) binding to troponin C, which control cardiac dynamics. We discuss new perspectives on how modifications in these mechanisms may be of relevance to redox signaling in diastolic heart failure, to angiotensin II signaling via β-arrestin, and to remodeling related to altered structural rigidity of tropomyosin. We think that these new perspectives provide a rationale for future studies directed at a more thorough understanding of the question driving our review.
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Affiliation(s)
- Sumeyye Yar
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, M/C 901, Chicago, IL, 60612, USA
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36
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Katrukha IA. Human cardiac troponin complex. Structure and functions. BIOCHEMISTRY (MOSCOW) 2014; 78:1447-65. [DOI: 10.1134/s0006297913130063] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Thoemmes SF, Stutzke CA, Du Y, Browning MD, Buttrick PM, Walker LA. Characterization and validation of new tools for measuring site-specific cardiac troponin I phosphorylation. J Immunol Methods 2013; 403:66-71. [PMID: 24291343 DOI: 10.1016/j.jim.2013.11.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 10/25/2013] [Accepted: 11/19/2013] [Indexed: 10/26/2022]
Abstract
Phosphorylation of cardiac troponin I is a well established mechanism by which cardiac contractility is modulated. However, there are a number of phosphorylation sites on TnI which contribute singly or in combination to influence cardiac function. Accordingly, methods for accurately measuring site-specific TnI phosphorylation are needed. Currently, two strategies are employed: mass spectrometry, which is costly, difficult and has a low throughput; and Western blotting using phospho-specific antibodies, which is limited by the availability of reagents. In this report, we describe a cohort of new site-specific TnI phosphoantibodies, generated against physiologically relevant phosphorylation sites, that are superior to the current commercially available antibodies: to phospho-serine 22/23 which shows a >5-fold phospho-specificity for phosphorylated TnI; to phospho-serine 43, which has >3-fold phospho-specificity for phosphorylated TnI; and phospho-serine 150 which has >2-fold phospho-specificity for phosphorylated TnI. These new antibodies demonstrated greater sensitivity and specificity for the phosphorylated TnI than the most widely used commercially available reagents. For example, at a protein load of 20 μg of total cardiac extract, a commercially available antibody recognized both phosphorylated and dephosphorylated TnI to the same degree. At the same protein load our phospho-serine 22/23 antibody exhibited no cross-reactivity with dephosphorylated TnI. These new tools should allow a more accurate assessment and a better understanding of the role of TnI phosphorylation in the response of the heart to pathologic stress.
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Affiliation(s)
- Stephen F Thoemmes
- University of Colorado Denver, Dept. of Medicine/Cardiology, Aurora, CO 80045, United States
| | - Crystal A Stutzke
- PhosphoSolutions, Colorado Bioscience Park, 12635 East Montview Blvd., # 213, Aurora, CO 80045, United States
| | - Yanmei Du
- University of Colorado Denver, Dept. of Medicine/Cardiology, Aurora, CO 80045, United States
| | - Michael D Browning
- PhosphoSolutions, Colorado Bioscience Park, 12635 East Montview Blvd., # 213, Aurora, CO 80045, United States
| | - Peter M Buttrick
- University of Colorado Denver, Dept. of Medicine/Cardiology, Aurora, CO 80045, United States
| | - Lori A Walker
- University of Colorado Denver, Dept. of Medicine/Cardiology, Aurora, CO 80045, United States.
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38
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Kaushik G, Zambon AC, Fuhrmann A, Bernstein SI, Bodmer R, Engler AJ, Cammarato A. Measuring passive myocardial stiffness in Drosophila melanogaster to investigate diastolic dysfunction. J Cell Mol Med 2012; 16:1656-62. [PMID: 22225769 PMCID: PMC3326184 DOI: 10.1111/j.1582-4934.2011.01517.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Aging is marked by a decline in LV diastolic function, which encompasses abnormalities in diastolic relaxation, chamber filling and/or passive myocardial stiffness. Genetic tractability and short life span make Drosophila melanogaster an ideal organism to study the effects of aging on heart function, including senescent-associated changes in gene expression and in passive myocardial stiffness. However, use of the Drosophila heart tube to probe deterioration of diastolic performance is subject to at least two challenges: the extent of genetic homology to mammals and the ability to resolve mechanical properties of the bilayered fly heart, which consists of a ventral muscle layer that covers the contractile cardiomyocytes. Here, we argue for widespread use of Drosophila as a novel myocardial aging model by (1) describing diastolic dysfunction in flies, (2) discussing how critical pathways involved in dysfunction are conserved across species and (3) demonstrating the advantage of an atomic force microscopy-based analysis method to measure stiffness of the multilayered Drosophila heart tube versus isolated myocytes from other model systems. By using powerful Drosophila genetic tools, we aim to efficiently alter changes observed in factors that contribute to diastolic dysfunction to understand how one might improve diastolic performance at advanced ages in humans.
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Affiliation(s)
- Gaurav Kaushik
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
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39
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Wijnker PJM, Foster DB, Tsao AL, Frazier AH, dos Remedios CG, Murphy AM, Stienen GJM, van der Velden J. Impact of site-specific phosphorylation of protein kinase A sites Ser23 and Ser24 of cardiac troponin I in human cardiomyocytes. Am J Physiol Heart Circ Physiol 2012; 304:H260-8. [PMID: 23144315 DOI: 10.1152/ajpheart.00498.2012] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
PKA-mediated phosphorylation of contractile proteins upon β-adrenergic stimulation plays an important role in the regulation of cardiac performance. Phosphorylation of the PKA sites (Ser(23)/Ser(24)) of cardiac troponin (cTn)I results in a decrease in myofilament Ca(2+) sensitivity and an increase in the rate of relaxation. However, the relation between the level of phosphorylation of the sites and the functional effects in the human myocardium is unknown. Therefore, site-directed mutagenesis was used to study the effects of phosphorylation at Ser(23) and Ser(24) of cTnI on myofilament function in human cardiac tissue. Serines were replaced by aspartic acid (D) or alanine (A) to mimic phosphorylation and dephosphorylation, respectively. cTnI-DD mimics both sites phosphorylated, cTnI-AD mimics Ser(23) unphosphorylated and Ser(24) phosphorylated, cTnI-DA mimics Ser(23) phosphorylated and Ser(24) unphosphorylated, and cTnI-AA mimics both sites unphosphorylated. Force development was measured at various Ca(2+) concentrations in permeabilized cardiomyocytes in which the endogenous troponin complex was exchanged with these recombinant human troponin complexes. In donor cardiomyocytes, myofilament Ca(2+) sensitivity (pCa(50)) was significantly lower in cTnI-DD (pCa(50): 5.39 ± 0.01) compared with cTnI-AA (pCa(50): 5.50 ± 0.01), cTnI-AD (pCa(50): 5.48 ± 0.01), and cTnI-DA (pCa(50): 5.51 ± 0.01) at ~70% cTn exchange. No effects were observed on the rate of tension redevelopment. In cardiomyocytes from idiopathic dilated cardiomyopathic tissue, a linear decline in pCa(50) with cTnI-DD content was observed, saturating at ~55% bisphosphorylation. Our data suggest that in the human myocardium, phosphorylation of both PKA sites on cTnI is required to reduce myofilament Ca(2+) sensitivity, which is maximal at ~55% bisphosphorylated cTnI. The implications for in vivo cardiac function in health and disease are detailed in the DISCUSSION in this article.
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Affiliation(s)
- Paul J M Wijnker
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands.
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40
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Disease-related cardiac troponins alter thin filament Ca2+ association and dissociation rates. PLoS One 2012; 7:e38259. [PMID: 22675533 PMCID: PMC3366952 DOI: 10.1371/journal.pone.0038259] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Accepted: 05/04/2012] [Indexed: 11/19/2022] Open
Abstract
The contractile response of the heart can be altered by disease-related protein modifications to numerous contractile proteins. By utilizing an IAANS labeled fluorescent troponin C, [Formula: see text], we examined the effects of ten disease-related troponin modifications on the Ca(2+) binding properties of the troponin complex and the reconstituted thin filament. The selected modifications are associated with a broad range of cardiac diseases: three subtypes of familial cardiomyopathies (dilated, hypertrophic and restrictive) and ischemia-reperfusion injury. Consistent with previous studies, the majority of the protein modifications had no effect on the Ca(2+) binding properties of the isolated troponin complex. However, when incorporated into the thin filament, dilated cardiomyopathy mutations desensitized (up to 3.3-fold), while hypertrophic and restrictive cardiomyopathy mutations, and ischemia-induced truncation of troponin I, sensitized the thin filament to Ca(2+) (up to 6.3-fold). Kinetically, the dilated cardiomyopathy mutations increased the rate of Ca(2+) dissociation from the thin filament (up to 2.5-fold), while the hypertrophic and restrictive cardiomyopathy mutations, and the ischemia-induced truncation of troponin I decreased the rate (up to 2-fold). The protein modifications also increased (up to 5.4-fold) or decreased (up to 2.5-fold) the apparent rate of Ca(2+) association to the thin filament. Thus, the disease-related protein modifications alter Ca(2+) binding by influencing both the association and dissociation rates of thin filament Ca(2+) exchange. These alterations in Ca(2+) exchange kinetics influenced the response of the thin filament to artificial Ca(2+) transients generated in a stopped-flow apparatus. Troponin C may act as a hub, sensing physiological and pathological stimuli to modulate the Ca(2+)-binding properties of the thin filament and influence the contractile performance of the heart.
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41
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Zhang J, Shettigar V, Zhang GC, Kindell DG, Liu X, López JJ, Yerrimuni V, Davis GA, Davis JP. Engineering Parvalbumin for the Heart: Optimizing the Mg Binding Properties of Rat β-Parvalbumin. Front Physiol 2011; 2:77. [PMID: 22059076 PMCID: PMC3204457 DOI: 10.3389/fphys.2011.00077] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2011] [Accepted: 10/10/2011] [Indexed: 01/01/2023] Open
Abstract
Parvalbumin (PV), an EF-hand protein family member, is a delayed calcium buffer that exchanges magnesium for calcium to facilitate fast skeletal muscle relaxation. Genetic approaches that express parvalbumin in the heart also enhance relaxation and show promise of being therapeutic against various cardiac diseases where relaxation is compromised. Unfortunately, skeletal muscle PVs have very slow rates of Ca2+ dissociation and are prone to becoming saturated with Ca2+, eventually losing their buffering capability within the constantly beating heart. In order for PV to have a more therapeutic potential in the heart, a PV with faster rates of calcium dissociation and high Mg2+ affinity is needed. We demonstrate that at 35°C, rat β-PV has an ~30-fold faster rate of Ca2+ dissociation compared to rat skeletal muscle α-PV, and still possesses a physiologically relevant Ca2+ affinity (~100 nM). However, rat β-PV will not be a delayed Ca2+ buffer since its Mg2+ affinity is too low (~1 mM). We have engineered two mutations into rat β-PV, S55D and E62D, when observed alone increase Mg2+ affinity up to fivefold, but when combined increase Mg2+ affinity ~13-fold, well within a physiologically relevant affinity. Furthermore, the Mg2+ dissociation rate (172/s) from the engineered S55D, E62D PV is slow enough for delayed Ca2+ buffering. Additionally, the engineered PV retains a high Ca2+ affinity (132 nM) and fast rate of Ca2+ dissociation (64/s). These PV design strategies hold promise for the development of new therapies to remediate relaxation abnormalities in different heart diseases and heart failure.
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Affiliation(s)
- Jianchao Zhang
- Department of Physiology and Cell Biology, The Ohio State University Columbus, OH, USA
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de Tombe PP, Granzier HL. The cytoskeleton and the cellular transduction of mechanical strain in the heart: a special issue. Pflugers Arch 2011; 462:1-2. [PMID: 21594569 DOI: 10.1007/s00424-011-0976-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 05/05/2011] [Accepted: 05/06/2011] [Indexed: 01/15/2023]
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