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Calcium Handling in Inherited Cardiac Diseases: A Focus on Catecholaminergic Polymorphic Ventricular Tachycardia and Hypertrophic Cardiomyopathy. Int J Mol Sci 2023; 24:ijms24043365. [PMID: 36834774 PMCID: PMC9963263 DOI: 10.3390/ijms24043365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 02/02/2023] [Accepted: 02/04/2023] [Indexed: 02/10/2023] Open
Abstract
Calcium (Ca2+) is the major mediator of cardiac contractile function. It plays a key role in regulating excitation-contraction coupling and modulating the systolic and diastolic phases. Defective handling of intracellular Ca2+ can cause different types of cardiac dysfunction. Thus, the remodeling of Ca2+ handling has been proposed to be a part of the pathological mechanism leading to electrical and structural heart diseases. Indeed, to ensure appropriate electrical cardiac conduction and contraction, Ca2+ levels are regulated by several Ca2+-related proteins. This review focuses on the genetic etiology of cardiac diseases related to calcium mishandling. We will approach the subject by focalizing on two clinical entities: catecholaminergic polymorphic ventricular tachycardia (CPVT) as a cardiac channelopathy and hypertrophic cardiomyopathy (HCM) as a primary cardiomyopathy. Further, this review will illustrate the fact that despite the genetic and allelic heterogeneity of cardiac defects, calcium-handling perturbations are the common pathophysiological mechanism. The newly identified calcium-related genes and the genetic overlap between the associated heart diseases are also discussed in this review.
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2
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Sevrieva IR, Ponnam S, Yan Z, Irving M, Kampourakis T, Sun YB. Phosphorylation-dependent interactions of myosin-binding protein C and troponin coordinate the myofilament response to protein kinase A. J Biol Chem 2023; 299:102767. [PMID: 36470422 PMCID: PMC9826837 DOI: 10.1016/j.jbc.2022.102767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 11/23/2022] [Accepted: 11/24/2022] [Indexed: 12/12/2022] Open
Abstract
PKA-mediated phosphorylation of sarcomeric proteins enhances heart muscle performance in response to β-adrenergic stimulation and is associated with accelerated relaxation and increased cardiac output for a given preload. At the cellular level, the latter translates to a greater dependence of Ca2+ sensitivity and maximum force on sarcomere length (SL), that is, enhanced length-dependent activation. However, the mechanisms by which PKA phosphorylation of the most notable sarcomeric PKA targets, troponin I (cTnI) and myosin-binding protein C (cMyBP-C), lead to these effects remain elusive. Here, we specifically altered the phosphorylation level of cTnI in heart muscle cells and characterized the structural and functional effects at different levels of background phosphorylation of cMyBP-C and with two different SLs. We found Ser22/23 bisphosphorylation of cTnI was indispensable for the enhancement of length-dependent activation by PKA, as was cMyBP-C phosphorylation. This high level of coordination between cTnI and cMyBP-C may suggest coupling between their regulatory mechanisms. Further evidence for this was provided by our finding that cardiac troponin (cTn) can directly interact with cMyBP-C in vitro, in a phosphorylation- and Ca2+-dependent manner. In addition, bisphosphorylation at Ser22/Ser23 increased Ca2+ sensitivity at long SL in the presence of endogenously phosphorylated cMyBP-C. When cMyBP-C was dephosphorylated, bisphosphorylation of cTnI increased Ca2+ sensitivity and decreased cooperativity at both SLs, which may translate to deleterious effects in physiological settings. Our results could have clinical relevance for disease pathways, where PKA phosphorylation of cTnI may be functionally uncoupled from cMyBP-C phosphorylation due to mutations or haploinsufficiency.
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Affiliation(s)
- Ivanka R Sevrieva
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom.
| | - Saraswathi Ponnam
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Ziqian Yan
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Malcolm Irving
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Thomas Kampourakis
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Yin-Biao Sun
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
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3
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Keyt LK, Duran JM, Bui QM, Chen C, Miyamoto MI, Silva Enciso J, Tardiff JC, Adler ED. Thin filament cardiomyopathies: A review of genetics, disease mechanisms, and emerging therapeutics. Front Cardiovasc Med 2022; 9:972301. [PMID: 36158814 PMCID: PMC9489950 DOI: 10.3389/fcvm.2022.972301] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Accepted: 07/28/2022] [Indexed: 11/17/2022] Open
Abstract
All muscle contraction occurs due to the cyclical interaction between sarcomeric thin and thick filament proteins within the myocyte. The thin filament consists of the proteins actin, tropomyosin, Troponin C, Troponin I, and Troponin T. Mutations in these proteins can result in various forms of cardiomyopathy, including hypertrophic, restrictive, and dilated phenotypes and account for as many as 30% of all cases of inherited cardiomyopathy. There is significant evidence that thin filament mutations contribute to dysregulation of Ca2+ within the sarcomere and may have a distinct pathomechanism of disease from cardiomyopathy associated with thick filament mutations. A number of distinct clinical findings appear to be correlated with thin-filament mutations: greater degrees of restrictive cardiomyopathy and relatively less left ventricular (LV) hypertrophy and LV outflow tract obstruction than that seen with thick filament mutations, increased morbidity associated with heart failure, increased arrhythmia burden and potentially higher mortality. Most therapies that improve outcomes in heart failure blunt the neurohormonal pathways involved in cardiac remodeling, while most therapies for hypertrophic cardiomyopathy involve use of negative inotropes to reduce LV hypertrophy or septal reduction therapies to reduce LV outflow tract obstruction. None of these therapies directly address the underlying sarcomeric dysfunction associated with thin-filament mutations. With mounting evidence that thin filament cardiomyopathies occur through a distinct mechanism, there is need for therapies targeting the unique, underlying mechanisms tailored for each patient depending on a given mutation.
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Affiliation(s)
- Lucas K. Keyt
- Department of Internal Medicine, University of California, San Diego, San Diego, CA, United States
| | - Jason M. Duran
- Department of Cardiology, University of California, San Diego, San Diego, CA, United States
| | - Quan M. Bui
- Department of Cardiology, University of California, San Diego, San Diego, CA, United States
| | - Chao Chen
- Department of Cardiology, University of California, San Diego, San Diego, CA, United States
| | | | - Jorge Silva Enciso
- Department of Cardiology, University of California, San Diego, San Diego, CA, United States
| | - Jil C. Tardiff
- Department of Medicine and Biomedical Engineering, University of Arizona, Tucson, AZ, United States
| | - Eric D. Adler
- Department of Cardiology, University of California, San Diego, San Diego, CA, United States
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4
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De Novo Missense Mutations in TNNC1 and TNNI3 Causing Severe Infantile Cardiomyopathy Affect Myofilament Structure and Function and Are Modulated by Troponin Targeting Agents. Int J Mol Sci 2021; 22:ijms22179625. [PMID: 34502534 PMCID: PMC8431798 DOI: 10.3390/ijms22179625] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/01/2021] [Accepted: 09/02/2021] [Indexed: 01/09/2023] Open
Abstract
Rare pediatric non-compaction and restrictive cardiomyopathy are usually associated with a rapid and severe disease progression. While the non-compaction phenotype is characterized by structural defects and is correlated with systolic dysfunction, the restrictive phenotype exhibits diastolic dysfunction. The molecular mechanisms are poorly understood. Target genes encode among others, the cardiac troponin subunits forming the main regulatory protein complex of the thin filament for muscle contraction. Here, we compare the molecular effects of two infantile de novo point mutations in TNNC1 (p.cTnC-G34S) and TNNI3 (p.cTnI-D127Y) leading to severe non-compaction and restrictive phenotypes, respectively. We used skinned cardiomyocytes, skinned fibers, and reconstituted thin filaments to measure the impact of the mutations on contractile function. We investigated the interaction of these troponin variants with actin and their inter-subunit interactions, as well as the structural integrity of reconstituted thin filaments. Both mutations exhibited similar functional and structural impairments, though the patients developed different phenotypes. Furthermore, the protein quality control system was affected, as shown for TnC-G34S using patient's myocardial tissue samples. The two troponin targeting agents levosimendan and green tea extract (-)-epigallocatechin-3-gallate (EGCg) stabilized the structural integrity of reconstituted thin filaments and ameliorated contractile function in vitro in some, but not all, aspects to a similar degree for both mutations.
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Lopez Davila AJ, Zhu L, Fritz L, Kraft T, Chalovich JM. The Positively Charged C-Terminal Region of Human Skeletal Troponin T Retards Activation and Decreases Calcium Sensitivity. Biochemistry 2020; 59:4189-4201. [PMID: 33074652 DOI: 10.1021/acs.biochem.0c00499] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Calcium binding to troponin C (TnC) activates striated muscle contraction by removing TnI (troponin I) from its inhibitory site on actin. Troponin T (TnT) links TnI with tropomyosin, causing tropomyosin to move from an inhibitory position on actin to an activating position. Positive charges within the C-terminal region of human cardiac TnT limit Ca2+ activation. We now show that the positively charged region of TnT has an even larger impact on skeletal muscle regulation. We prepared one variant of human skeletal TnT that had the C-terminal 16 residues truncated (Δ16) and another with an added C-terminal Cys residue and Ala substituted for the last 6 basic residues (251C-HAHA). Both mutants reduced (based on S1 binding kinetics) or eliminated (based on acrylodan-tropomyosin fluorescence) the first inactive state of actin at <10 nM free Ca2+. 251C-HAHA-TnT and Δ16-TnT mutants greatly increased ATPase activation at 0.2 mM Ca2+, even without high-affinity cross-bridge binding. They also shifted the force-pCa curve of muscle fibers to lower Ca2+ by 0.8-1.2 pCa units (the larger shift for 251C-HAHA-TnT). Shifts in force-pCa were maintained in the presence of para-aminoblebbistatin. The effects of modification of the C-terminal region of TnT on the kinetics of S1 binding to actin were somewhat different from those observed earlier with the cardiac analogue. In general, the C-terminal region of human skeletal TnT is critical to regulation, just as it is in the cardiac system, and is a potential target for modulating activity.
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Affiliation(s)
- Alfredo Jesus Lopez Davila
- Institute of Molecular and Cell Physiology, Hannover Medical School, Carl-Neuberg-Street 1, 103-Block 1-Ebene 03-1010, Hannover 30625, Germany
| | - Li Zhu
- Department of Biochemistry & Molecular Biology, Brody School of Medicine at East Carolina University, Greenville, North Carolina 27834, United States
| | - Leon Fritz
- Institute of Molecular and Cell Physiology, Hannover Medical School, Carl-Neuberg-Street 1, 103-Block 1-Ebene 03-1010, Hannover 30625, Germany
| | - Theresia Kraft
- Institute of Molecular and Cell Physiology, Hannover Medical School, Carl-Neuberg-Street 1, 103-Block 1-Ebene 03-1010, Hannover 30625, Germany
| | - Joseph M Chalovich
- Department of Biochemistry & Molecular Biology, Brody School of Medicine at East Carolina University, Greenville, North Carolina 27834, United States
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López-Dávila AJ, Chalovich JM, Zittrich S, Piep B, Matinmehr F, Málnási-Csizmadia A, Rauscher AÁ, Kraft T, Brenner B, Stehle R. Cycling Cross-Bridges Contribute to Thin Filament Activation in Human Slow-Twitch Fibers. Front Physiol 2020; 11:144. [PMID: 32265723 PMCID: PMC7105683 DOI: 10.3389/fphys.2020.00144] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 02/11/2020] [Indexed: 11/13/2022] Open
Abstract
It has been shown that not only calcium but also strong binding myosin heads contribute to thin filament activation in isometrically contracting animal fast-twitch and cardiac muscle preparations. This behavior has not been studied in human muscle fibers or animal slow-twitch fibers. Human slow-twitch fibers are interesting since they contain the same myosin heavy chain isoform as the human heart. To explore myosin-induced activation of the thin filament in isometrically contracting human slow-twitch fibers, the endogenous troponin complex was exchanged for a well-characterized fast-twitch skeletal troponin complex labeled with the fluorescent dye N-((2-(Iodoacetoxy)ethyl)-N-methyl)amino-7-nitrobenz-2-oxa-1,3-diazole (fsTn-IANBD). The exchange was ≈70% complete (n = 8). The relative contributions of calcium and strong binding cross-bridges to thin filament activation were dissected by increasing the concentration of calcium from relaxing (pCa 7.5) to saturating levels (pCa 4.5) before and after incubating the exchanged fibers in the myosin inhibitor para-aminoblebbistatin (AmBleb). At pCa 4.5, the relative contributions of calcium and strong binding cross-bridges to thin filament activation were ≈69 and ≈31%, respectively. Additionally, switching from isometric to isotonic contraction at pCa 4.5 revealed that strong binding cross-bridges contributed ≈29% to thin filament activation (i.e., virtually the same magnitude obtained with AmBleb). Thus, we showed through two different approaches that lowering the number of strong binding cross-bridges, at saturating calcium, significantly reduced the activation of the thin filament in human slow-twitch fibers. The contribution of myosin to activation resembled that which was previously reported in rat cardiac and rabbit fast-twitch muscle preparations. This method could be applied to slow-twitch human fibers obtained from the soleus muscle of cardiomyopathy patients. Such studies could lead to a better understanding of the effect of point mutations of the cardiac myosin head on the regulation of muscle contraction and could lead to better management by pharmacological approaches.
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Affiliation(s)
| | - Joseph M Chalovich
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Stefan Zittrich
- Institute of Vegetative Physiology, University of Cologne, Cologne, Germany
| | - Birgit Piep
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hanover, Germany
| | - Faramarz Matinmehr
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hanover, Germany
| | - Andras Málnási-Csizmadia
- MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Budapest, Hungary
| | | | - Theresia Kraft
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hanover, Germany
| | - Bernhard Brenner
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hanover, Germany
| | - Robert Stehle
- Institute of Vegetative Physiology, University of Cologne, Cologne, Germany
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Marston S, Zamora JE. Troponin structure and function: a view of recent progress. J Muscle Res Cell Motil 2019; 41:71-89. [PMID: 31030382 PMCID: PMC7109197 DOI: 10.1007/s10974-019-09513-1] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 04/12/2019] [Indexed: 12/15/2022]
Abstract
The molecular mechanism by which Ca2+ binding and phosphorylation regulate muscle contraction through Troponin is not yet fully understood. Revealing the differences between the relaxed and active structure of cTn, as well as the conformational changes that follow phosphorylation has remained a challenge for structural biologists over the years. Here we review the current understanding of how Ca2+, phosphorylation and disease-causing mutations affect the structure and dynamics of troponin to regulate the thin filament based on electron microscopy, X-ray diffraction, NMR and molecular dynamics methodologies.
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Affiliation(s)
- Steven Marston
- NHLI and Chemistry Departments, Imperial College London, W12 0NN, London, UK.
| | - Juan Eiros Zamora
- NHLI and Chemistry Departments, Imperial College London, W12 0NN, London, UK
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Potluri PR, Cordina NM, Kachooei E, Brown LJ. Characterization of the L29Q Hypertrophic Cardiomyopathy Mutation in Cardiac Troponin C by Paramagnetic Relaxation Enhancement Nuclear Magnetic Resonance. Biochemistry 2019; 58:908-917. [PMID: 30620548 DOI: 10.1021/acs.biochem.8b01140] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The key events in regulating muscle contraction involve the troponin (Tn) heterotrimeric protein complex in which the binding to and release of Ca2+ from the highly conserved troponin C (TnC) subunit trigger a series of structural changes within Tn, and the other thin filament proteins, to result in contraction. In the heart, the control of contraction and relaxation events can be altered by many single-point mutations that may result in cardiomyopathy and sometimes sudden cardiac death. Here we have examined the structural effects of one hypertrophic cardiomyopathy mutation, L29Q, on Ca2+-induced structural transitions within whole TnC. This mutation is of particular interest as several physiological and structural studies have indicated that the response of TnC to Ca2+ binding is altered in the presence of the L29Q mutation, but the structural nature of these changes continues to be debated. In addition, little is known about the effect of this mutation in the Ca2+ free state. Here we have used paramagnetic relaxation enhancement nuclear magnetic resonance (PRE-NMR) to assess the structural effects arising from the L29Q mutation. PRE-NMR distances obtained from a nitroxide spin-label at Cys84 showed that the L29Q mutation perturbs the structure of the TnC N-domain in the presence and absence of Ca2+, with a more "open" TnC N-domain observed in the apo form. In addition, binding of Ca2+ to the TnC-L29Q construct triggers a change in the orientation between the two domains of TnC. Together, these structural perturbations, revealed by PRE-NMR, provide insight into the pathogenesis of this mutation.
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Affiliation(s)
- Phani R Potluri
- Department of Molecular Sciences , Macquarie University , Sydney , NSW 2109 , Australia
| | - Nicole M Cordina
- Department of Molecular Sciences , Macquarie University , Sydney , NSW 2109 , Australia
| | - Ehsan Kachooei
- Department of Molecular Sciences , Macquarie University , Sydney , NSW 2109 , Australia
| | - Louise J Brown
- Department of Molecular Sciences , Macquarie University , Sydney , NSW 2109 , Australia
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Cai F, Hwang PM, Sykes BD. Structural Changes Induced by the Binding of the Calcium Desensitizer W7 to Cardiac Troponin. Biochemistry 2018; 57:6461-6469. [DOI: 10.1021/acs.biochem.8b00882] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Fangze Cai
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
| | - Peter M. Hwang
- Department of Medicine, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
| | - Brian D. Sykes
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
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10
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Klein BA, Reiz B, Robertson IM, Irving M, Li L, Sun YB, Sykes BD. Reversible Covalent Reaction of Levosimendan with Cardiac Troponin C in Vitro and in Situ. Biochemistry 2018; 57:2256-2265. [DOI: 10.1021/acs.biochem.8b00109] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Brittney A. Klein
- Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Béla Reiz
- Department of Chemistry, Faculty of Science, University of Alberta, Edmonton, Alberta T6H 2H7, Canada
| | - Ian M. Robertson
- Pharmaceutical and Health Benefits Branch, Ministry of Health, Government of Alberta, Edmonton, Alberta T5J 3Z5, Canada
| | - Malcolm Irving
- Randall Centre for Cell and Molecular Biophysics and British Heart Foundation Centre of Research Excellence, King’s College London, London SE1 1UL, U.K
| | - Liang Li
- Department of Chemistry, Faculty of Science, University of Alberta, Edmonton, Alberta T6H 2H7, Canada
| | - Yin-Biao Sun
- Randall Centre for Cell and Molecular Biophysics and British Heart Foundation Centre of Research Excellence, King’s College London, London SE1 1UL, U.K
| | - Brian D. Sykes
- Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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Stevens CM, Rayani K, Singh G, Lotfalisalmasi B, Tieleman DP, Tibbits GF. Changes in the dynamics of the cardiac troponin C molecule explain the effects of Ca 2+-sensitizing mutations. J Biol Chem 2017; 292:11915-11926. [PMID: 28533433 DOI: 10.1074/jbc.m116.770776] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 05/07/2017] [Indexed: 12/31/2022] Open
Abstract
Cardiac troponin C (cTnC) is the regulatory protein that initiates cardiac contraction in response to Ca2+ TnC binding Ca2+ initiates a cascade of protein-protein interactions that begins with the opening of the N-terminal domain of cTnC, followed by cTnC binding the troponin I switch peptide (TnISW). We have evaluated, through isothermal titration calorimetry and molecular-dynamics simulation, the effect of several clinically relevant mutations (A8V, L29Q, A31S, L48Q, Q50R, and C84Y) on the Ca2+ affinity, structural dynamics, and calculated interaction strengths between cTnC and each of Ca2+ and TnISW Surprisingly the Ca2+ affinity measured by isothermal titration calorimetry was only significantly affected by half of these mutations including L48Q, which had a 10-fold higher affinity than WT, and the Q50R and C84Y mutants, each of which had affinities 3-fold higher than wild type. This suggests that Ca2+ affinity of the N-terminal domain of cTnC in isolation is insufficient to explain the pathogenicity of these mutations. Molecular-dynamics simulation was used to evaluate the effects of these mutations on Ca2+ binding, structural dynamics, and TnI interaction independently. Many of the mutations had a pronounced effect on the balance between the open and closed conformations of the TnC molecule, which provides an indirect mechanism for their pathogenic properties. Our data demonstrate that the structural dynamics of the cTnC molecule are key in determining myofilament Ca2+ sensitivity. Our data further suggest that modulation of the structural dynamics is the underlying molecular mechanism for many disease mutations that are far from the regulatory Ca2+-binding site of cTnC.
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Affiliation(s)
- Charles M Stevens
- Cardiovascular Sciences, British Columbia Children's Hospital Research Institute, Vancouver, British Columbia V5Z 4H4, Canada; Departments of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Kaveh Rayani
- Departments of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Gurpreet Singh
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Bairam Lotfalisalmasi
- Departments of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - D Peter Tieleman
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Glen F Tibbits
- Cardiovascular Sciences, British Columbia Children's Hospital Research Institute, Vancouver, British Columbia V5Z 4H4, Canada; Departments of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada; Departments of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.
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12
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Veltri T, de Oliveira GAP, Bienkiewicz EA, Palhano FL, Marques MDA, Moraes AH, Silva JL, Sorenson MM, Pinto JR. Amide hydrogens reveal a temperature-dependent structural transition that enhances site-II Ca 2+-binding affinity in a C-domain mutant of cardiac troponin C. Sci Rep 2017; 7:691. [PMID: 28386062 PMCID: PMC5429600 DOI: 10.1038/s41598-017-00777-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 03/14/2017] [Indexed: 01/07/2023] Open
Abstract
The hypertrophic cardiomyopathy-associated mutant D145E, in cardiac troponin C (cTnC) C-domain, causes generalised instability at multiple sites in the isolated protein. As a result, structure and function of the mutant are more susceptible to higher temperatures. Above 25 °C there are large, progressive increases in N-domain Ca2+-binding affinity for D145E but only small changes for the wild-type protein. NMR-derived backbone amide temperature coefficients for many residues show a sharp transition above 30–40 °C, indicating a temperature-dependent conformational change that is most prominent around the mutated EF-hand IV, as well as throughout the C-domain. Smaller, isolated changes occur in the N-domain. Cardiac skinned fibres reconstituted with D145E are more sensitive to Ca2+ than fibres reconstituted with wild-type, and this defect is amplified near body-temperature. We speculate that the D145E mutation destabilises the native conformation of EF-hand IV, leading to a transient unfolding and dissociation of helix H that becomes more prominent at higher temperatures. This creates exposed hydrophobic surfaces that may be capable of binding unnaturally to a variety of targets, possibly including the N-domain of cTnC when it is in its open Ca2+-saturated state. This would constitute a potential route for propagating signals from one end of TnC to the other.
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Affiliation(s)
- Tiago Veltri
- Department of Biomedical Sciences, Florida State University College of Medicine, 1115 West Call Street, Tallahassee, FL, 32306-4300, USA.,Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas F° 373, Cidade Universitária, Rio de Janeiro, 21941-902, RJ, Brazil
| | - Guilherme A P de Oliveira
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica, Instituto Nacional de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Ewa A Bienkiewicz
- Department of Biomedical Sciences, Florida State University College of Medicine, 1115 West Call Street, Tallahassee, FL, 32306-4300, USA
| | - Fernando L Palhano
- Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas F° 373, Cidade Universitária, Rio de Janeiro, 21941-902, RJ, Brazil
| | - Mayra de A Marques
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica, Instituto Nacional de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Adolfo H Moraes
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica, Instituto Nacional de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Brazil
| | - Jerson L Silva
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica, Instituto Nacional de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Martha M Sorenson
- Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas F° 373, Cidade Universitária, Rio de Janeiro, 21941-902, RJ, Brazil
| | - Jose R Pinto
- Department of Biomedical Sciences, Florida State University College of Medicine, 1115 West Call Street, Tallahassee, FL, 32306-4300, USA.
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Zhang X, Kampourakis T, Yan Z, Sevrieva I, Irving M, Sun YB. Distinct contributions of the thin and thick filaments to length-dependent activation in heart muscle. eLife 2017; 6. [PMID: 28229860 PMCID: PMC5365314 DOI: 10.7554/elife.24081] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 02/20/2017] [Indexed: 12/02/2022] Open
Abstract
The Frank-Starling relation is a fundamental auto-regulatory property of the heart that ensures the volume of blood ejected in each heartbeat is matched to the extent of venous filling. At the cellular level, heart muscle cells generate higher force when stretched, but despite intense efforts the underlying molecular mechanism remains unknown. We applied a fluorescence-based method, which reports structural changes separately in the thick and thin filaments of rat cardiac muscle, to elucidate that mechanism. The distinct structural changes of troponin C in the thin filaments and myosin regulatory light chain in the thick filaments allowed us to identify two aspects of the Frank-Starling relation. Our results show that the enhanced force observed when heart muscle cells are maximally activated by calcium is due to a change in thick filament structure, but the increase in calcium sensitivity at lower calcium levels is due to a change in thin filament structure. DOI:http://dx.doi.org/10.7554/eLife.24081.001 The heart needs to pump out the same volume of blood that enters it. This is not as simple as it sounds, as changes in heart rate – for example, in response to exercise – alter how hard the heart must pump. When blood flows into the heart it stretches the heart muscle, which consists of units called sarcomeres. Sarcomeres contain two types of protein filament, known as thick filaments and thin filaments. When a heartbeat is triggered by calcium ions flowing into the heart muscle cells, the thick filaments slide over the thin filaments. This causes the heart muscle cell to contract. The Frank–Starling mechanism helps to regulate the contraction of the heart. This mechanism has two aspects. Firstly, as the sarcomere lengthens, its protein filaments are able to contract with more force for a given high level of calcium ions. Secondly, the lengthening of the sarcomere makes the filaments more sensitive to calcium ions, which again causes the heart to contract more forcefully. However, the molecular mechanisms that underlie these effects were not clear. Zhang et al. have now studied rat heart muscle cells using a new fluorescence-based method that can detect structural changes in the thick and thin filaments. The results show that the increased force that is generated when sarcomeres are stretched can be accounted for by changes in the structure of the thick filament. In contrast, the increase in calcium sensitivity that occurs as the sarcomere lengthens is largely due to structural alterations in the thin filament. These two processes can be controlled independently, but work together in the Frank–Starling mechanism. Now that we better understand the molecular basis of the Frank–Starling mechanism, further work could investigate new strategies for designing and testing treatments for heart disease. DOI:http://dx.doi.org/10.7554/eLife.24081.002
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Affiliation(s)
- Xuemeng Zhang
- Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom.,British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Thomas Kampourakis
- Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom.,British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Ziqian Yan
- Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom.,British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Ivanka Sevrieva
- Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom.,British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Malcolm Irving
- Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom.,British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Yin-Biao Sun
- Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom.,British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
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Marques MDA, Pinto JR, Moraes AH, Iqbal A, de Magalhães MTQ, Monteiro J, Pedrote MM, Sorenson MM, Silva JL, de Oliveira GAP. Allosteric Transmission along a Loosely Structured Backbone Allows a Cardiac Troponin C Mutant to Function with Only One Ca 2+ Ion. J Biol Chem 2017; 292:2379-2394. [PMID: 28049727 DOI: 10.1074/jbc.m116.765362] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 12/28/2016] [Indexed: 01/19/2023] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is one of the most common cardiomyopathies and a major cause of sudden death in young athletes. The Ca2+ sensor of the sarcomere, cardiac troponin C (cTnC), plays an important role in regulating muscle contraction. Although several cardiomyopathy-causing mutations have been identified in cTnC, the limited information about their structural defects has been mapped to the HCM phenotype. Here, we used high-resolution electron-spray ionization mass spectrometry (ESI-MS), Carr-Purcell-Meiboom-Gill relaxation dispersion (CPMG-RD), and affinity measurements of cTnC for the thin filament in reconstituted papillary muscles to provide evidence of an allosteric mechanism in mutant cTnC that may play a role to the HCM phenotype. We showed that the D145E mutation leads to altered dynamics on a μs-ms time scale and deactivates both of the divalent cation-binding sites of the cTnC C-domain. CPMG-RD captured a low populated protein-folding conformation triggered by the Glu-145 replacement of Asp. Paradoxically, although D145E C-domain was unable to bind Ca2+, these changes along its backbone allowed it to attach more firmly to thin filaments than the wild-type isoform, providing evidence for an allosteric response of the Ca2+-binding site II in the N-domain. Our findings explain how the effects of an HCM mutation in the C-domain reflect up into the N-domain to cause an increase of Ca2+ affinity in site II, thus opening up new insights into the HCM phenotype.
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Affiliation(s)
- Mayra de A Marques
- From the Programa de Biologia Estrutural, Instituto de Bioquímica Médica, Instituto Nacional de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
| | - Jose Renato Pinto
- the Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida 32304
| | - Adolfo H Moraes
- the Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil, and
| | - Anwar Iqbal
- From the Programa de Biologia Estrutural, Instituto de Bioquímica Médica, Instituto Nacional de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
| | - Mariana T Q de Magalhães
- the Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - Jamila Monteiro
- From the Programa de Biologia Estrutural, Instituto de Bioquímica Médica, Instituto Nacional de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
| | - Murilo M Pedrote
- From the Programa de Biologia Estrutural, Instituto de Bioquímica Médica, Instituto Nacional de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
| | - Martha M Sorenson
- From the Programa de Biologia Estrutural, Instituto de Bioquímica Médica, Instituto Nacional de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
| | - Jerson L Silva
- From the Programa de Biologia Estrutural, Instituto de Bioquímica Médica, Instituto Nacional de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil,
| | - Guilherme A P de Oliveira
- From the Programa de Biologia Estrutural, Instituto de Bioquímica Médica, Instituto Nacional de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil,
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15
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Marques MDA, de Oliveira GAP. Cardiac Troponin and Tropomyosin: Structural and Cellular Perspectives to Unveil the Hypertrophic Cardiomyopathy Phenotype. Front Physiol 2016; 7:429. [PMID: 27721798 PMCID: PMC5033975 DOI: 10.3389/fphys.2016.00429] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 09/09/2016] [Indexed: 12/12/2022] Open
Abstract
Inherited myopathies affect both skeletal and cardiac muscle and are commonly associated with genetic dysfunctions, leading to the production of anomalous proteins. In cardiomyopathies, mutations frequently occur in sarcomeric genes, but the cause-effect scenario between genetic alterations and pathological processes remains elusive. Hypertrophic cardiomyopathy (HCM) was the first cardiac disease associated with a genetic background. Since the discovery of the first mutation in the β-myosin heavy chain, more than 1400 new mutations in 11 sarcomeric genes have been reported, awarding HCM the title of the “disease of the sarcomere.” The most common macroscopic phenotypes are left ventricle and interventricular septal thickening, but because the clinical profile of this disease is quite heterogeneous, these phenotypes are not suitable for an accurate diagnosis. The development of genomic approaches for clinical investigation allows for diagnostic progress and understanding at the molecular level. Meanwhile, the lack of accurate in vivo models to better comprehend the cellular events triggered by this pathology has become a challenge. Notwithstanding, the imbalance of Ca2+ concentrations, altered signaling pathways, induction of apoptotic factors, and heart remodeling leading to abnormal anatomy have already been reported. Of note, a misbalance of signaling biomolecules, such as kinases and tumor suppressors (e.g., Akt and p53), seems to participate in apoptotic and fibrotic events. In HCM, structural and cellular information about defective sarcomeric proteins and their altered interactome is emerging but still represents a bottleneck for developing new concepts in basic research and for future therapeutic interventions. This review focuses on the structural and cellular alterations triggered by HCM-causing mutations in troponin and tropomyosin proteins and how structural biology can aid in the discovery of new platforms for therapeutics. We highlight the importance of a better understanding of allosteric communications within these thin-filament proteins to decipher the HCM pathological state.
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Affiliation(s)
- Mayra de A Marques
- Programa de Biologia Estrutural, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro Rio de Janeiro, Brazil
| | - Guilherme A P de Oliveira
- Programa de Biologia Estrutural, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro Rio de Janeiro, Brazil
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