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Cubuk J, Greenberg L, Greenberg AE, Emenecker RJ, Stuchell-Brereton MD, Holehouse AS, Soranno A, Greenberg MJ. Structural dynamics of the intrinsically disordered linker region of cardiac troponin T. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.30.596451. [PMID: 38853835 PMCID: PMC11160775 DOI: 10.1101/2024.05.30.596451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
The cardiac troponin complex, composed of troponins I, T, and C, plays a central role in regulating the calcium-dependent interactions between myosin and the thin filament. Mutations in troponin can cause cardiomyopathies; however, it is still a major challenge for the field to connect how changes in sequence affect troponin's function. Recent high-resolution structures of the thin filament revealed critical insights into the structure-function relationship of the troponin complex, but there remain large, unresolved segments of troponin, including the troponin-T linker region that is a hotspot for several cardiomyopathy mutations. This unresolved yet functionally-significant linker region has been proposed to be intrinsically disordered, with behaviors that are not well described by traditional structural approaches; however, this proposal has not been experimentally verified. Here, we used a combination of single-molecule Förster resonance energy transfer (FRET), molecular dynamics simulations, and functional reconstitution assays to investigate the troponin-T linker region. We experimentally and computationally show that in the context of both isolated troponin and the fully regulated troponin complex, the linker behaves as a dynamic, intrinsically disordered region. This region undergoes polyampholyte expansion in the presence of high salt and distinct conformational changes during the assembly of the troponin complex. We also examine the ΔE160 hypertrophic cardiomyopathy mutation in the linker, and we demonstrate that this mutation does not affect the conformational dynamics of the linker, rather it allosterically affects interactions with other subunits of the troponin complex, leading to increased molecular contractility. Taken together, our data clearly demonstrate the importance of disorder within the troponin-T linker and provide new insights into the molecular mechanisms controlling the pathogenesis of cardiomyopathies.
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Affiliation(s)
- Jasmine Cubuk
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Ave, 63110, Saint Louis, MO, USA
- Center for Biomolecular Condensates, Washington University in St Louis, 1 Brookings Drive, 63130, Saint Louis, MO, USA
| | - Lina Greenberg
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Ave, 63110, Saint Louis, MO, USA
| | - Akiva E. Greenberg
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Ave, 63110, Saint Louis, MO, USA
| | - Ryan J. Emenecker
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Ave, 63110, Saint Louis, MO, USA
- Center for Biomolecular Condensates, Washington University in St Louis, 1 Brookings Drive, 63130, Saint Louis, MO, USA
| | - Melissa D. Stuchell-Brereton
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Ave, 63110, Saint Louis, MO, USA
- Center for Biomolecular Condensates, Washington University in St Louis, 1 Brookings Drive, 63130, Saint Louis, MO, USA
| | - Alex S. Holehouse
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Ave, 63110, Saint Louis, MO, USA
- Center for Biomolecular Condensates, Washington University in St Louis, 1 Brookings Drive, 63130, Saint Louis, MO, USA
| | - Andrea Soranno
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Ave, 63110, Saint Louis, MO, USA
- Center for Biomolecular Condensates, Washington University in St Louis, 1 Brookings Drive, 63130, Saint Louis, MO, USA
| | - Michael J. Greenberg
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Ave, 63110, Saint Louis, MO, USA
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2
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Jin Y, Xu J, Hua Y, Zhang H, Li Y. Challenging of ECMO application in pediatric restrictive cardiomyopathy: case report of a novel TNNI3 variant. Front Cardiovasc Med 2024; 11:1365209. [PMID: 38854656 PMCID: PMC11157066 DOI: 10.3389/fcvm.2024.1365209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Accepted: 05/10/2024] [Indexed: 06/11/2024] Open
Abstract
Background Restrictive cardiomyopathy (RCM) represents a rare cardiovascular disorder stemming from filament-associated genes. Nonetheless, treating RCM presents considerable challenges, particularly concerning device implantation and mechanical support. Furthermore, elucidating the molecular function of specific variants holds promise in benefiting patients and enhancing prognosis, given the significant heterogeneity among RCM variants. Case presentation The proband, an eight-year-old female, was admitted to our hospital post cardiopulmonary resuscitation due to sudden cardiac arrest. Echocardiography revealed bilateral atrial enlargement. Whole-exome sequencing uncovered a novel heterozygous mutation (c.509G>A, p.R170Q) in TNNI3. Evaluation using the MutationTaster application deemed c.509G>A pathogenic (probability = 0.99). Following clinical manifestations, imaging assessments, and genetic screening, the proband received an RCM diagnosis. ECMO was recommended along with continuous renal replacement therapy. However, persistent atrial flutter ensued post-ECMO withdrawal. Attempts to restore cardiac rhythm with cardioversion, metoprolol, and amiodarone proved futile. Subsequent heart failure led to the patient's demise due to cardiac shock. Based on crystal protein structural analysis, we observed that cTnI-R170Q and R170W exerted similar impacts on protein structural stability and formation. However, both differed significantly from cTnI-R170G, primarily influencing amino acid regions 32-79 and 129-149, involved in TnC and actin binding. Therefore, cTnI-R170Q was revealed to induce RCM via the same molecular mechanism as cTnI-R170W. Conclusion Managing RCM remains a critical challenge. This study underscores the discouragement of device implantations for cardiac pump functional support in RCM, particularly for non-short-term scheduled HTx. Additionally, considering catheter ablation for atrial fibrosis-induced AFs is recommended. Mechanistically, cTnI-R170Q primarily diminishes troponin-actin interactions and destabilizes thin filaments.
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Affiliation(s)
| | | | | | - Haiyang Zhang
- Key Laboratory of Birth Defects and Related Diseases of Women and Children of MOE, Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Yifei Li
- Key Laboratory of Birth Defects and Related Diseases of Women and Children of MOE, Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China
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3
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Janssens JV, Raaijmakers AJA, Weeks KL, Bell JR, Mellor KM, Curl CL, Delbridge LMD. The cardiomyocyte origins of diastolic dysfunction: cellular components of myocardial "stiffness". Am J Physiol Heart Circ Physiol 2024; 326:H584-H598. [PMID: 38180448 DOI: 10.1152/ajpheart.00334.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 12/07/2023] [Accepted: 12/21/2023] [Indexed: 01/06/2024]
Abstract
The impaired ability of the heart to relax and stretch to accommodate venous return is generally understood to represent a state of "diastolic dysfunction" and often described using the all-purpose noun "stiffness." Despite the now common qualitative usage of this term in fields of cardiac patho/physiology, the specific quantitative concept of stiffness as a molecular and biophysical entity with real practical interpretation in healthy and diseased hearts is sometimes obscure. The focus of this review is to characterize the concept of cardiomyocyte stiffness and to develop interpretation of "stiffness" attributes at the cellular and molecular levels. Here, we consider "stiffness"-related terminology interpretation and make links between cardiomyocyte stiffness and aspects of functional and structural cardiac performance. We discuss cross bridge-derived stiffness sources, considering the contributions of diastolic myofilament activation and impaired relaxation. This includes commentary relating to the role of cardiomyocyte Ca2+ flux and Ca2+ levels in diastole, the troponin-tropomyosin complex role as a Ca2+ effector in diastole, the myosin ADP dissociation rate as a modulator of cross bridge attachment and regulation of cross-bridge attachment by myosin binding protein C. We also discuss non-cross bridge-derived stiffness sources, including the titin sarcomeric spring protein, microtubule and intermediate filaments, and cytoskeletal extracellular matrix interactions. As the prevalence of conditions involving diastolic heart failure has escalated, a more sophisticated understanding of the molecular, cellular, and tissue determinants of cardiomyocyte stiffness offers potential to develop imaging and molecular intervention tools.
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Affiliation(s)
- Johannes V Janssens
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, Victoria, Australia
| | - Antonia J A Raaijmakers
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, Victoria, Australia
| | - Kate L Weeks
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, Victoria, Australia
- Baker Department of Cardiometabolic Health, University of Melbourne, Melbourne, Victoria, Australia
- Department of Diabetes, Monash University, Parkville, Victoria, Australia
| | - James R Bell
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, Victoria, Australia
- Department of Microbiology, Anatomy, Physiology and Pharmacology, La Trobe University, Melbourne, Victoria, Australia
| | - Kimberley M Mellor
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, Victoria, Australia
- Department of Physiology, University of Auckland, Auckland, New Zealand
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Claire L Curl
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, Victoria, Australia
| | - Lea M D Delbridge
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, Victoria, Australia
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4
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Juan T, Bellec M, Cardoso B, Athéa H, Fukuda N, Albu M, Günther S, Looso M, Stainier DYR. Control of cardiac contractions using Cre-lox and degron strategies in zebrafish. Proc Natl Acad Sci U S A 2024; 121:e2309842121. [PMID: 38194447 PMCID: PMC10801847 DOI: 10.1073/pnas.2309842121] [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: 06/12/2023] [Accepted: 11/27/2023] [Indexed: 01/11/2024] Open
Abstract
Cardiac contractions and hemodynamic forces are essential for organ development and homeostasis. Control over cardiac contractions can be achieved pharmacologically or optogenetically. However, these approaches lack specificity or require direct access to the heart. Here, we compare two genetic approaches to control cardiac contractions by modulating the levels of the essential sarcomeric protein Tnnt2a in zebrafish. We first recombine a newly generated tnnt2a floxed allele using multiple lines expressing Cre under the control of cardiomyocyte-specific promoters, and show that it does not recapitulate the tnnt2a/silent heart mutant phenotype in embryos. We show that this lack of early cardiac contraction defects is due, at least in part, to the long half-life of tnnt2a mRNA, which masks the gene deletion effects until the early larval stages. We then generate an endogenous Tnnt2a-eGFP fusion line that we use together with the zGRAD system to efficiently degrade Tnnt2a in all cardiomyocytes. Using single-cell transcriptomics, we find that Tnnt2a depletion leads to cardiac phenotypes similar to those observed in tnnt2a mutants, with a loss of blood and pericardial flow-dependent cell types. Furthermore, we achieve conditional degradation of Tnnt2a-eGFP by splitting the zGRAD protein into two fragments that, when combined with the cpFRB2-FKBP system, can be reassembled upon rapamycin treatment. Thus, this Tnnt2a degradation line enables non-invasive control of cardiac contractions with high spatial and temporal specificity and will help further understand how they shape organ development and homeostasis.
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Affiliation(s)
- Thomas Juan
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, Bad Nauheim61231, Germany
- German Centre for Cardiovascular Research (Deutsches Zentrum für Herz- Kreislaufforschung), Bad Nauheim61231, Germany
- Cardio-Pulmonary Institute, Bad Nauheim61231, Germany
| | - Maëlle Bellec
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, Bad Nauheim61231, Germany
- German Centre for Cardiovascular Research (Deutsches Zentrum für Herz- Kreislaufforschung), Bad Nauheim61231, Germany
| | - Bárbara Cardoso
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, Bad Nauheim61231, Germany
- German Centre for Cardiovascular Research (Deutsches Zentrum für Herz- Kreislaufforschung), Bad Nauheim61231, Germany
| | - Héloïse Athéa
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, Bad Nauheim61231, Germany
- German Centre for Cardiovascular Research (Deutsches Zentrum für Herz- Kreislaufforschung), Bad Nauheim61231, Germany
| | - Nana Fukuda
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, Bad Nauheim61231, Germany
- German Centre for Cardiovascular Research (Deutsches Zentrum für Herz- Kreislaufforschung), Bad Nauheim61231, Germany
| | - Marga Albu
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, Bad Nauheim61231, Germany
- German Centre for Cardiovascular Research (Deutsches Zentrum für Herz- Kreislaufforschung), Bad Nauheim61231, Germany
| | - Stefan Günther
- German Centre for Cardiovascular Research (Deutsches Zentrum für Herz- Kreislaufforschung), Bad Nauheim61231, Germany
- Cardio-Pulmonary Institute, Bad Nauheim61231, Germany
- Bioinformatics and Deep Sequencing Platform, Max Planck Institute for Heart and Lung Research, Bad Nauheim61231, Germany
| | - Mario Looso
- German Centre for Cardiovascular Research (Deutsches Zentrum für Herz- Kreislaufforschung), Bad Nauheim61231, Germany
- Cardio-Pulmonary Institute, Bad Nauheim61231, Germany
- Bioinformatics Core Unit, Max Planck Institute for Heart and Lung Research, Bad Nauheim61231, Germany
| | - Didier Y. R. Stainier
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, Bad Nauheim61231, Germany
- German Centre for Cardiovascular Research (Deutsches Zentrum für Herz- Kreislaufforschung), Bad Nauheim61231, Germany
- Cardio-Pulmonary Institute, Bad Nauheim61231, Germany
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5
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Bacharova L, Chevalier P, Gorenek B, Jons C, Li Y, Locati ET, Maanja M, Pérez‐Riera AR, Platonov PG, Ribeiro ALP, Schocken D, Soliman EZ, Svehlikova J, Tereshchenko LG, Ugander M, Varma N, Elena Z, Ikeda T. ISE/ISHNE expert consensus statement on the ECG diagnosis of left ventricular hypertrophy: The change of the paradigm. Ann Noninvasive Electrocardiol 2024; 29:e13097. [PMID: 37997698 PMCID: PMC10770819 DOI: 10.1111/anec.13097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 10/30/2023] [Accepted: 11/01/2023] [Indexed: 11/25/2023] Open
Abstract
The ECG diagnosis of LVH is predominantly based on the QRS voltage criteria. The classical paradigm postulates that the increased left ventricular mass generates a stronger electrical field, increasing the leftward and posterior QRS forces, reflected in the augmented QRS amplitude. However, the low sensitivity of voltage criteria has been repeatedly documented. We discuss possible reasons for this shortcoming and proposal of a new paradigm. The theoretical background for voltage measured at the body surface is defined by the solid angle theorem, which relates the measured voltage to spatial and non-spatial determinants. The spatial determinants are represented by the extent of the activation front and the distance of the recording electrodes. The non-spatial determinants comprise electrical characteristics of the myocardium, which are comparatively neglected in the interpretation of the QRS patterns. Various clinical conditions are associated with LVH. These conditions produce considerable diversity of electrical properties alterations thereby modifying the resultant QRS patterns. The spectrum of QRS patterns observed in LVH patients is quite broad, including also left axis deviation, left anterior fascicular block, incomplete and complete left bundle branch blocks, Q waves, and fragmented QRS. Importantly, the QRS complex can be within normal limits. The new paradigm stresses the electrophysiological background in interpreting QRS changes, i.e., the effect of the non-spatial determinants. This postulates that the role of ECG is not to estimate LV size in LVH, but to understand and decode the underlying electrical processes, which are crucial in relation to cardiovascular risk assessment.
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Affiliation(s)
| | - Philippe Chevalier
- Neuromyogene InstituteClaude Bernard UniversityVilleurbanneFrance
- Service de RythmologieHospices Civils de LyonLyonFrance
| | - Bulent Gorenek
- Eskisehir Osmangazi University Cardiology DepartmentEskisehirTurkey
| | - Christian Jons
- Department of CardiologyRigshospitalet, Copenhagen University HospitalCopenhagenDenmark
| | - Yi‐Gang Li
- Department of Cardiology, Xinhua HospitalShanghai Jiao Tong University School of MedicineShanghaiChina
| | - Emanuela T. Locati
- Department of Arrhythmology and ElectrophysiologyIRCCS Policlinico San DonatoMilanoItaly
| | - Maren Maanja
- Department of Clinical PhysiologyKarolinska University Hospital, and Karolinska InstitutetStockholmSweden
| | | | - Pyotr G. Platonov
- Department of Cardiology, Clinical SciencesLund UniversityLundSweden
| | - Antonio Luiz Pinho Ribeiro
- Internal Medicine, Faculdade de Medicina da Universidade Federal de Minas GeraisBelo HorizonteBrazil
- Telehealth Center, Hospital das Clínicas da Universidade Federal de Minas GeraisBelo HorizonteBrazil
| | - Douglas Schocken
- Division of Cardiology, Department of MedicineDuke University Medical CenterDurhamNorth CarolinaUSA
| | - Elsayed Z. Soliman
- Section on Cardiovascular Medicine, Department of Medicine, Epidemiological Cardiology Research CenterWake Forest University School of MedicineWinston‐SalemNorth CarolinaUSA
| | - Jana Svehlikova
- Institute of Measurement Sciences, Slovak Academy of SciencesBratislavaSlovak Republic
| | - Larisa G. Tereshchenko
- Department of Quantitative Health SciencesLerner Research Institute, Cleveland ClinicClevelandOhioUSA
| | - Martin Ugander
- Faculty of Medicine and HealthThe University of SydneySydneyNew South WalesAustralia
- Department of Clinical PhysiologyKarolinska InstituteStockholmSweden
| | - Niraj Varma
- Cardiac Pacing & ElectrophysiologyHeart and Vascular Institute, Cleveland ClinicClevelandOhioUSA
| | - Zaklyazminskaya Elena
- Medical Genetics LaboratoryPetrovsky National Research Centre of SurgeryMoscowRussia
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6
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Wang S, Zhang Z, He J, Liu J, Guo X, Chu H, Xu H, Wang Y. Comprehensive review on gene mutations contributing to dilated cardiomyopathy. Front Cardiovasc Med 2023; 10:1296389. [PMID: 38107262 PMCID: PMC10722203 DOI: 10.3389/fcvm.2023.1296389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 11/17/2023] [Indexed: 12/19/2023] Open
Abstract
Dilated cardiomyopathy (DCM) is one of the most common primary myocardial diseases. However, to this day, it remains an enigmatic cardiovascular disease (CVD) characterized by ventricular dilatation, which leads to myocardial contractile dysfunction. It is the most common cause of chronic congestive heart failure and the most frequent indication for heart transplantation in young individuals. Genetics and various other factors play significant roles in the progression of dilated cardiomyopathy, and variants in more than 50 genes have been associated with the disease. However, the etiology of a large number of cases remains elusive. Numerous studies have been conducted on the genetic causes of dilated cardiomyopathy. These genetic studies suggest that mutations in genes for fibronectin, cytoskeletal proteins, and myosin in cardiomyocytes play a key role in the development of DCM. In this review, we provide a comprehensive description of the genetic basis, mechanisms, and research advances in genes that have been strongly associated with DCM based on evidence-based medicine. We also emphasize the important role of gene sequencing in therapy for potential early diagnosis and improved clinical management of DCM.
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Affiliation(s)
- Shipeng Wang
- Department of Cardiovascular Medicine, The First Hospital of Jilin University, Changchun, China
| | - Zhiyu Zhang
- Department of Cardiovascular Medicine, The Second People's Hospital of Yibin, Yibin, China
| | - Jiahuan He
- Department of Cardiovascular Medicine, The First Hospital of Jilin University, Changchun, China
| | - Junqian Liu
- Department of Cardiovascular Medicine, The First Hospital of Jilin University, Changchun, China
| | - Xia Guo
- Department of Cardiovascular Medicine, The First Hospital of Jilin University, Changchun, China
| | - Haoxuan Chu
- Department of Cardiovascular Medicine, The First Hospital of Jilin University, Changchun, China
| | - Hanchi Xu
- Department of Cardiovascular Medicine, The First Hospital of Jilin University, Changchun, China
| | - Yushi Wang
- Department of Cardiovascular Medicine, The First Hospital of Jilin University, Changchun, China
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7
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Chumakova OS, Baklanova TN, Milovanova NV, Zateyshchikov DA. Hypertrophic Cardiomyopathy in Underrepresented Populations: Clinical and Genetic Landscape Based on a Russian Single-Center Cohort Study. Genes (Basel) 2023; 14:2042. [PMID: 38002985 PMCID: PMC10671745 DOI: 10.3390/genes14112042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 10/30/2023] [Accepted: 11/02/2023] [Indexed: 11/26/2023] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is a common inherited cardiac disorder characterized by marked clinical and genetic heterogeneity. Ethnic groups underrepresented in studies may have distinctive characteristics. We sought to evaluate the clinical and genetic landscape of Russian HCM patients. A total of 193 patients (52% male; 95% Eastern Slavic origin; median age 56 years) were clinically evaluated, including genetic testing, and prospectively followed to document outcomes. As a result, 48% had obstructive HCM, 25% had HCM in family, 21% were asymptomatic, and 68% had comorbidities. During 2.8 years of follow-up, the all-cause mortality rate was 2.86%/year. A total of 5.7% received an implantable cardioverter-defibrillator (ICD), and 21% had septal reduction therapy. A sequencing analysis of 176 probands identified 64 causative variants in 66 patients (38%); recurrent variants were MYBPC3 p.Q1233* (8), MYBPC3 p.R346H (2), MYH7 p.A729P (2), TPM1 p.Q210R (3), and FLNC p.H1834Y (2); 10 were multiple variant carriers (5.7%); 5 had non-sarcomeric HCM, ALPK3, TRIM63, and FLNC. Thin filament variant carriers had a worse prognosis for heart failure (HR = 7.9, p = 0.007). In conclusion, in the Russian HCM population, the low use of ICD and relatively high mortality should be noted by clinicians; some distinct recurrent variants are suspected to have a founder effect; and family studies on some rare variants enriched worldwide knowledge in HCM.
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Affiliation(s)
- Olga S. Chumakova
- Moscow Healthcare Department, City Clinical Hospital 17, 119620 Moscow, Russia; (T.N.B.); (D.A.Z.)
- E.I. Chazov National Medical Research Center for Cardiology, 121552 Moscow, Russia
| | - Tatiana N. Baklanova
- Moscow Healthcare Department, City Clinical Hospital 17, 119620 Moscow, Russia; (T.N.B.); (D.A.Z.)
| | | | - Dmitry A. Zateyshchikov
- Moscow Healthcare Department, City Clinical Hospital 17, 119620 Moscow, Russia; (T.N.B.); (D.A.Z.)
- E.I. Chazov National Medical Research Center for Cardiology, 121552 Moscow, Russia
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8
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Matyushenko AM, Nefedova VV, Kochurova AM, Kopylova GV, Koubassova NA, Shestak AG, Yampolskaya DS, Shchepkin DV, Kleymenov SY, Ryabkova NS, Katrukha IA, Bershitsky SY, Zaklyazminskaya EV, Tsaturyan AK, Levitsky DI. Novel Mutation Glu98Lys in Cardiac Tropomyosin Alters Its Structure and Impairs Myocardial Relaxation. Int J Mol Sci 2023; 24:12359. [PMID: 37569730 PMCID: PMC10419091 DOI: 10.3390/ijms241512359] [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: 07/01/2023] [Revised: 07/25/2023] [Accepted: 07/30/2023] [Indexed: 08/13/2023] Open
Abstract
We characterized a novel genetic variant c.292G > A (p.E98K) in the TPM1 gene encoding cardiac tropomyosin 1.1 isoform (Tpm1.1), found in a proband with a phenotype of complex cardiomyopathy with conduction dysfunction and slow progressive neuromuscular involvement. To understand the molecular mechanism by which this mutation impairs cardiac function, we produced recombinant Tpm1.1 carrying an E98K substitution and studied how this substitution affects the structure of the Tpm1.1 molecule and its functional properties. The results showed that the E98K substitution in the N-terminal part of the Tpm molecule significantly destabilizes the C-terminal part of Tpm, thus indicating a long-distance destabilizing effect of the substitution on the Tpm coiled-coil structure. The E98K substitution did not noticeably affect Tpm's affinity for F-actin but significantly impaired Tpm's regulatory properties. It increased the Ca2+ sensitivity of the sliding velocity of regulated thin filaments over cardiac myosin in an in vitro motility assay and caused an incomplete block of the thin filament sliding at low Ca2+ concentrations. The incomplete motility block in the absence of Ca2+ can be explained by the loosening of the Tpm interaction with troponin I (TnI), thus increasing Tpm mobility on the surface of an actin filament that partially unlocks the myosin binding sites. This hypothesis is supported by the molecular dynamics (MD) simulation that showed that the E98 Tpm residue is involved in hydrogen bonding with the C-terminal part of TnI. Thus, the results allowed us to explain the mechanism by which the E98K Tpm mutation impairs sarcomeric function and myocardial relaxation.
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Affiliation(s)
- Alexander M. Matyushenko
- A.N. Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow 119071, Russia; (A.M.M.); (V.V.N.); (D.S.Y.); (S.Y.K.)
| | - Victoria V. Nefedova
- A.N. Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow 119071, Russia; (A.M.M.); (V.V.N.); (D.S.Y.); (S.Y.K.)
| | - Anastasia M. Kochurova
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg 620049, Russia; (A.M.K.); (G.V.K.); (D.V.S.); (S.Y.B.)
| | - Galina V. Kopylova
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg 620049, Russia; (A.M.K.); (G.V.K.); (D.V.S.); (S.Y.B.)
| | - Natalia A. Koubassova
- Institute of Mechanics, Moscow State University, Moscow 119192, Russia; (N.A.K.); (A.K.T.)
| | - Anna G. Shestak
- Petrovsky National Research Centre of Surgery, Moscow 119991, Russia; (A.G.S.); (E.V.Z.)
| | - Daria S. Yampolskaya
- A.N. Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow 119071, Russia; (A.M.M.); (V.V.N.); (D.S.Y.); (S.Y.K.)
| | - Daniil V. Shchepkin
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg 620049, Russia; (A.M.K.); (G.V.K.); (D.V.S.); (S.Y.B.)
| | - Sergey Y. Kleymenov
- A.N. Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow 119071, Russia; (A.M.M.); (V.V.N.); (D.S.Y.); (S.Y.K.)
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, Moscow 119334, Russia
| | - Natalia S. Ryabkova
- Department of Biochemistry, Faculty of Biology, Lomonosov Moscow State University, Moscow 119234, Russia; (N.S.R.); (I.A.K.)
- HyTest Ltd., 20520 Turku, Finland
| | - Ivan A. Katrukha
- Department of Biochemistry, Faculty of Biology, Lomonosov Moscow State University, Moscow 119234, Russia; (N.S.R.); (I.A.K.)
- HyTest Ltd., 20520 Turku, Finland
| | - Sergey Y. Bershitsky
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg 620049, Russia; (A.M.K.); (G.V.K.); (D.V.S.); (S.Y.B.)
| | - Elena V. Zaklyazminskaya
- Petrovsky National Research Centre of Surgery, Moscow 119991, Russia; (A.G.S.); (E.V.Z.)
- N.P. Bochkov Research Centre for Medical Genetics, Moscow 20520, Russia
| | - Andrey K. Tsaturyan
- Institute of Mechanics, Moscow State University, Moscow 119192, Russia; (N.A.K.); (A.K.T.)
| | - Dmitrii I. Levitsky
- A.N. Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow 119071, Russia; (A.M.M.); (V.V.N.); (D.S.Y.); (S.Y.K.)
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Tikunova SB, Thuma J, Davis JP. Mouse Models of Cardiomyopathies Caused by Mutations in Troponin C. Int J Mol Sci 2023; 24:12349. [PMID: 37569724 PMCID: PMC10419064 DOI: 10.3390/ijms241512349] [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: 07/01/2023] [Revised: 07/27/2023] [Accepted: 08/01/2023] [Indexed: 08/13/2023] Open
Abstract
Cardiac muscle contraction is regulated via Ca2+ exchange with the hetero-trimeric troponin complex located on the thin filament. Binding of Ca2+ to cardiac troponin C, a Ca2+ sensing subunit within the troponin complex, results in a series of conformational re-arrangements among the thin filament components, leading to an increase in the formation of actomyosin cross-bridges and muscle contraction. Ultimately, a decline in intracellular Ca2+ leads to the dissociation of Ca2+ from troponin C, inhibiting cross-bridge cycling and initiating muscle relaxation. Therefore, troponin C plays a crucial role in the regulation of cardiac muscle contraction and relaxation. Naturally occurring and engineered mutations in troponin C can lead to altered interactions among components of the thin filament and to aberrant Ca2+ binding and exchange with the thin filament. Mutations in troponin C have been associated with various forms of cardiac disease, including hypertrophic, restrictive, dilated, and left ventricular noncompaction cardiomyopathies. Despite progress made to date, more information from human studies, biophysical characterizations, and animal models is required for a clearer understanding of disease drivers that lead to cardiomyopathies. The unique use of engineered cardiac troponin C with the L48Q mutation that had been thoroughly characterized and genetically introduced into mouse myocardium clearly demonstrates that Ca2+ sensitization in and of itself should not necessarily be considered a disease driver. This opens the door for small molecule and protein engineering strategies to help boost impaired systolic function. On the other hand, the engineered troponin C mutants (I61Q and D73N), genetically introduced into mouse myocardium, demonstrate that Ca2+ desensitization under basal conditions may be a driving factor for dilated cardiomyopathy. In addition to enhancing our knowledge of molecular mechanisms that trigger hypertrophy, dilation, morbidity, and mortality, these cardiomyopathy mouse models could be used to test novel treatment strategies for cardiovascular diseases. In this review, we will discuss (1) the various ways mutations in cardiac troponin C might lead to disease; (2) relevant data on mutations in cardiac troponin C linked to human disease, and (3) all currently existing mouse models containing cardiac troponin C mutations (disease-associated and engineered).
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Affiliation(s)
- Svetlana B. Tikunova
- Department of Physiology and Cell Biology, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University, Columbus, OH 43210, USA (J.P.D.)
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Lynn ML, Jimenez J, Castillo RL, Klass MM, Vasquez C, Baldo A, Gibson C, Murphy AM, Tardiff JC. The HCM - Linked Mutation Arg92Leu in TNNT2 Allosterically Alters the cTnC - cTnI Interface and Disrupts the PKA-mediated Regulation of Myofilament Relaxation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.18.549569. [PMID: 37503299 PMCID: PMC10370115 DOI: 10.1101/2023.07.18.549569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Background Impaired left ventricular relaxation, high filling pressures, and dysregulation of Ca 2+ homeostasis are common findings contributing to diastolic dysfunction in hypertrophic cardiomyopathy (HCM). Studies have shown that impaired relaxation is an early observation in the sarcomere-gene-positive preclinical HCM cohort which suggests potential involvement of myofilament regulators of relaxation. Yet, a molecular level understanding of mechanism(s) at the level of the myofilament is lacking. We hypothesized that mutation-specific, allosterically mediated, changes to the cardiac troponin C-cardiac troponin I (cTnC-cTnI) interface can account for the development of early-onset diastolic dysfunction via decreased PKA accessibility to cTnI. Methods HCM mutations R92L-cTnT (Arg92Leu) and Δ160E-cTnT (Glu160 deletion) were studied in vivo , in vitro, and in silico via 2D echocardiography, western blotting, ex vivo hemodynamics, stopped-flow kinetics, time resolved fluorescence resonance energy transfer (TR-FRET), and molecular dynamics simulations. Results The HCM-causative mutations R92L-cTnT and Δ160E-cTnT result in different time-of-onset of diastolic dysfunction. R92L-cTnT demonstrated early-onset diastolic dysfunction accompanied by a localized decrease in phosphorylation of cTnI. Constitutive phosphorylation of cTnI (cTnI-D 23 D 24 ) was sufficient to recover diastolic function to Non-Tg levels only for R92L-cTnT. Mutation-specific changes in Ca 2+ dissociation rates associated with R92L-cTnT reconstituted with cTnI-D 23 D 24 led us to investigate potential involvement of structural changes in the cTnC-cTnI interface as an explanation for these observations. We probed the interface via TR-FRET revealing a repositioning of the N-terminus of cTnI, closer to cTnC, and concomitant decreases in distance distributions at sites flanking the PKA consensus sequence. Implementing TR-FRET distances as constraints into our atomistic model identified additional electrostatic interactions at the consensus sequence. Conclusion These data indicate that the early diastolic dysfunction observed in a subset of HCM is likely attributable to structural changes at the cTnC-cTnI interface that impair accessibility of PKA thereby blunting β-adrenergic responsiveness and identifying a potential molecular target for therapeutic intervention.
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Sorrentino U, Gabbiato I, Canciani C, Calosci D, Rigon C, Zuccarello D, Cassina M. Homozygous TNNI3 Mutations and Severe Early Onset Dilated Cardiomyopathy: Patient Report and Review of the Literature. Genes (Basel) 2023; 14:genes14030748. [PMID: 36981019 PMCID: PMC10048074 DOI: 10.3390/genes14030748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/14/2023] [Accepted: 03/16/2023] [Indexed: 03/22/2023] Open
Abstract
The TNNI3 gene encodes for the cardiac isoform of troponin I, a pivotal component of the sarcomeric structure of the myocardium. While heterozygous TNNI3 missense mutations have long been associated with autosomal dominant hypertrophic and restrictive cardiomyopathies, the role of TNNI3 null mutations has been more debated due to the paucity and weak characterization of reported cases and the low penetrance of heterozygous genotypes. In recent years, however, an increasing amount of evidence has validated the hypothesis that biallelic TNNI3 null mutations cause a severe form of neonatal dilated cardiomyopathy. Here, we expand the case series reporting two unrelated patients afflicted with early onset dilated cardiomyopathy, due to homozygosity for the p.Arg98* TNNI3 variant, which had thus far been documented only in heterozygous patients and apparently healthy carriers, and the recurrent p.Arg69Alafs*8 variant, respectively. A review of previously reported biallelic TNNI3 loss-of-function variants and their associated cardiac phenotypes was also performed.
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Affiliation(s)
- Ugo Sorrentino
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (U.S.); (I.G.); (C.C.); (D.C.); (C.R.); (M.C.)
| | - Ilaria Gabbiato
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (U.S.); (I.G.); (C.C.); (D.C.); (C.R.); (M.C.)
| | - Chiara Canciani
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (U.S.); (I.G.); (C.C.); (D.C.); (C.R.); (M.C.)
| | - Davide Calosci
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (U.S.); (I.G.); (C.C.); (D.C.); (C.R.); (M.C.)
| | - Chiara Rigon
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (U.S.); (I.G.); (C.C.); (D.C.); (C.R.); (M.C.)
| | - Daniela Zuccarello
- Clinical Genetics Unit, University Hospital of Padova, 35128 Padova, Italy
- Correspondence: ; Tel.: +39-0498212524
| | - Matteo Cassina
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (U.S.); (I.G.); (C.C.); (D.C.); (C.R.); (M.C.)
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De Novo Asp219Val Mutation in Cardiac Tropomyosin Associated with Hypertrophic Cardiomyopathy. Int J Mol Sci 2022; 24:ijms24010018. [PMID: 36613463 PMCID: PMC9820293 DOI: 10.3390/ijms24010018] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 12/13/2022] [Accepted: 12/15/2022] [Indexed: 12/24/2022] Open
Abstract
Hypertrophic cardiomyopathy (HCM), caused by mutations in thin filament proteins, manifests as moderate cardiac hypertrophy and is associated with sudden cardiac death (SCD). We identified a new de novo variant, c.656A>T (p.D219V), in the TPM1 gene encoding cardiac tropomyosin 1.1 (Tpm) in a young SCD victim with post-mortem-diagnosed HCM. We produced recombinant D219V Tpm1.1 and studied its structural and functional properties using various biochemical and biophysical methods. The D219V mutation did not affect the Tpm affinity for F-actin but increased the thermal stability of the Tpm molecule and Tpm-F-actin complex. The D219V mutation significantly increased the Ca2+ sensitivity of the sliding velocity of thin filaments over cardiac myosin in an in vitro motility assay and impaired the inhibition of the filament sliding at low Ca2+ concentration. The molecular dynamics (MD) simulation provided insight into a possible molecular mechanism of the effect of the mutation that is most likely a cause of the weakening of the Tpm interaction with actin in the "closed" state and so makes it an easier transition to the “open” state. The changes in the Ca2+ regulation of the actin-myosin interaction characteristic of genetic HCM suggest that the mutation is likely pathogenic.
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