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Barefield DY, Alvarez-Arce A, Araujo KN. Mechanisms of Sarcomere Protein Mutation-Induced Cardiomyopathies. Curr Cardiol Rep 2023; 25:473-484. [PMID: 37060436 PMCID: PMC11141690 DOI: 10.1007/s11886-023-01876-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/30/2023] [Indexed: 04/16/2023]
Abstract
PURPOSE OF REVIEW The pace of identifying cardiomyopathy-associated mutations and advances in our understanding of sarcomere function that underlies many cardiomyopathies has been remarkable. Here, we aim to synthesize how these advances have led to the promising new treatments that are being developed to treat cardiomyopathies. RECENT FINDINGS The genomics era has identified and validated many genetic causes of hypertrophic and dilated cardiomyopathies. Recent advances in our mechanistic understanding of sarcomere pathophysiology include high-resolution molecular models of sarcomere components and the identification of the myosin super-relaxed state. The advances in our understanding of sarcomere function have yielded several therapeutic agents that are now in development and clinical use to correct contractile dysfunction-mediated cardiomyopathy. New genes linked to cardiomyopathy include targets with limited clinical evidence and require additional investigation. Large portions of cardiomyopathy with family history remain genetically undiagnosed and may be due to polygenic disease.
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Affiliation(s)
- David Y Barefield
- Department of Cell and Molecular Physiology, Loyola University Chicago, 2160 S. 1st Ave, Maywood, IL, 60153, USA.
| | - Alejandro Alvarez-Arce
- Department of Cell and Molecular Physiology, Loyola University Chicago, 2160 S. 1st Ave, Maywood, IL, 60153, USA
| | - Kelly N Araujo
- Department of Cell and Molecular Physiology, Loyola University Chicago, 2160 S. 1st Ave, Maywood, IL, 60153, USA
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2
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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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3
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Deranek AE, Baldo AP, Lynn ML, Schwartz SD, Tardiff JC. Structure and Dynamics of the Flexible Cardiac Troponin T Linker Domain in a Fully Reconstituted Thin Filament. Biochemistry 2022; 61:1229-1242. [PMID: 35696530 DOI: 10.1021/acs.biochem.2c00091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The structural analysis of large protein complexes has been greatly enhanced through the application of electron microscopy techniques. One such multiprotein complex, the cardiac thin filament (cTF), has cyclic interactions with thick filament proteins to drive contraction of the heart that has recently been the subject of such studies. As important as these studies are, they provide limited or no information on highly flexible regions that in isolation would be characterized as inherently disordered. One such region is the extended cardiac troponin T (cTnT) linker between the regions of cTnT which have been labeled TNT1 and TNT2. It comprises a hinge region (residues 158-166) and a highly flexible region (residues 167-203). Critically, this region modulates the troponin/tropomyosin complex's position across the actin filament. Thus, the cTnT linker structure and dynamics are central to the regulation of the function of cardiac muscles, but up to now, it was ill-understood. To establish the cTnT linker structure, we coupled an atomistic computational cTF model with time-resolved fluorescence resonance energy transfer measurements in both ±Ca2+ conditions utilizing fully reconstituted cTFs. We mapped the cTnT linker's positioning across the actin filament, and by coupling the experimental results to computation, we found mean structures and ranges of motion of this part of the complex. With this new insight, we can now address cTnT linker structural dynamics in both myofilament activation and disease.
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Affiliation(s)
- Andrea E Deranek
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona 85721, United States
| | - Anthony P Baldo
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Melissa L Lynn
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona 85721, United States
| | - Steven D Schwartz
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Jil C Tardiff
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona 85721, United States
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4
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Mason AB, Lynn ML, Baldo AP, Deranek AE, Tardiff JC, Schwartz SD. Computational and biophysical determination of pathogenicity of variants of unknown significance in cardiac thin filament. JCI Insight 2021; 6:154350. [PMID: 34699384 PMCID: PMC8675185 DOI: 10.1172/jci.insight.154350] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 10/22/2021] [Indexed: 11/17/2022] Open
Abstract
Point mutations within sarcomeric proteins have been associated with altered function and cardiomyopathy development. Difficulties remain, however, in establishing the pathogenic potential of individual mutations, often limiting the use of genotype in management of affected families. To directly address this challenge, we utilized our all-atom computational model of the human full cardiac thin filament (CTF) to predict how sequence substitutions in CTF proteins might affect structure and dynamics on an atomistic level. Utilizing molecular dynamics calculations, we simulated 21 well-defined genetic pathogenic cardiac troponin T and tropomyosin variants to establish a baseline of pathogenic changes induced in computational observables. Computational results were verified via differential scanning calorimetry on a subset of variants to develop an experimental correlation. Calculations were performed on 9 independent variants of unknown significance (VUS), and results were compared with pathogenic variants to identify high-resolution pathogenic signatures. Results for VUS were compared with the baseline set to determine induced structural and dynamic changes, and potential variant reclassifications were proposed. This unbiased, high-resolution computational methodology can provide unique structural and dynamic information that can be incorporated into existing analyses to facilitate classification both for de novo variants and those where established approaches have provided conflicting information.
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Affiliation(s)
| | - Melissa L Lynn
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona, USA
| | | | - Andrea E Deranek
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona, USA
| | - Jil C Tardiff
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona, USA
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5
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Barrick SK, Greenberg L, Greenberg MJ. A troponin T variant linked with pediatric dilated cardiomyopathy reduces the coupling of thin filament activation to myosin and calcium binding. Mol Biol Cell 2021; 32:1677-1689. [PMID: 34161147 PMCID: PMC8684737 DOI: 10.1091/mbc.e21-02-0082] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Dilated cardiomyopathy (DCM) is a significant cause of pediatric heart failure. Mutations in proteins that regulate cardiac muscle contraction can cause DCM; however, the mechanisms by which molecular-level mutations contribute to cellular dysfunction are not well understood. Better understanding of these mechanisms might enable the development of targeted therapeutics that benefit patient subpopulations with mutations that cause common biophysical defects. We examined the molecular- and cellular-level impacts of a troponin T variant associated with pediatric-onset DCM, R134G. The R134G variant decreased calcium sensitivity in an in vitro motility assay. Using stopped-flow and steady-state fluorescence measurements, we determined the molecular mechanism of the altered calcium sensitivity: R134G decouples calcium binding by troponin from the closed-to-open transition of the thin filament and decreases the cooperativity of myosin binding to regulated thin filaments. Consistent with the prediction that these effects would cause reduced force per sarcomere, cardiomyocytes carrying the R134G mutation are hypocontractile. They also show hallmarks of DCM that lie downstream of the initial insult, including disorganized sarcomeres and cellular hypertrophy. These results reinforce the importance of multiscale studies to fully understand mechanisms underlying human disease and highlight the value of mechanism-based precision medicine approaches for DCM.
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Affiliation(s)
- Samantha K Barrick
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110
| | - Lina Greenberg
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110
| | - Michael J Greenberg
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110
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6
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Clippinger SR, Cloonan PE, Wang W, Greenberg L, Stump WT, Angsutararux P, Nerbonne JM, Greenberg MJ. Mechanical dysfunction of the sarcomere induced by a pathogenic mutation in troponin T drives cellular adaptation. J Gen Physiol 2021; 153:211992. [PMID: 33856419 PMCID: PMC8054178 DOI: 10.1085/jgp.202012787] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 03/18/2021] [Indexed: 12/15/2022] Open
Abstract
Familial hypertrophic cardiomyopathy (HCM), a leading cause of sudden cardiac death, is primarily caused by mutations in sarcomeric proteins. The pathogenesis of HCM is complex, with functional changes that span scales, from molecules to tissues. This makes it challenging to deconvolve the biophysical molecular defect that drives the disease pathogenesis from downstream changes in cellular function. In this study, we examine an HCM mutation in troponin T, R92Q, for which several models explaining its effects in disease have been put forward. We demonstrate that the primary molecular insult driving disease pathogenesis is mutation-induced alterations in tropomyosin positioning, which causes increased molecular and cellular force generation during calcium-based activation. Computational modeling shows that the increased cellular force is consistent with the molecular mechanism. These changes in cellular contractility cause downstream alterations in gene expression, calcium handling, and electrophysiology. Taken together, our results demonstrate that molecularly driven changes in mechanical tension drive the early disease pathogenesis of familial HCM, leading to activation of adaptive mechanobiological signaling pathways.
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Affiliation(s)
- Sarah R Clippinger
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO
| | - Paige E Cloonan
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO
| | - Wei Wang
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Lina Greenberg
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO
| | - W Tom Stump
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO
| | | | - Jeanne M Nerbonne
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Michael J Greenberg
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO
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7
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Tobacman LS, Cammarato A. Cardiomyopathic troponin mutations predominantly occur at its interface with actin and tropomyosin. J Gen Physiol 2021; 153:e202012815. [PMID: 33492345 PMCID: PMC7836260 DOI: 10.1085/jgp.202012815] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 12/23/2020] [Indexed: 01/09/2023] Open
Abstract
Reversible Ca2+ binding to troponin is the primary on-off switch of the contractile apparatus of striated muscles, including the heart. Dominant missense mutations in human cardiac troponin genes are among the causes of hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy. Structural understanding of troponin action has recently advanced considerably via electron microscopy and molecular dynamics studies of the thin filament. As a result, it is now possible to examine cardiomyopathy-inducing troponin mutations in thin-filament structural context, and from that to seek new insight into pathogenesis and into the troponin regulatory mechanism. We compiled from consortium reports a representative set of troponin mutation sites whose pathogenicity was determined using standardized clinical genetics criteria. Another set of sites, apparently tolerant of amino acid substitutions, was compiled from the gnomAD v2 database. Pathogenic substitutions occurred predominantly in the areas of troponin that contact actin or tropomyosin, including, but not limited to, two regions of newly proposed structure and long-known implication in cardiomyopathy: the C-terminal third of troponin I and a part of the troponin T N terminus. The pathogenic mutations were located in troponin regions that prevent contraction under low Ca2+ concentration conditions. These regions contribute to Ca2+-regulated steric hindrance of myosin by the combined effects of troponin and tropomyosin. Loss-of-function mutations within these parts of troponin result in loss of inhibition, consistent with the hypercontractile phenotype characteristic of HCM. Notably, pathogenic mutations are absent in our dataset from the Ca2+-binding, activation-producing troponin C (TnC) N-lobe, which controls contraction by a multi-faceted mechanism. Apparently benign mutations are also diminished in the TnC N-lobe, suggesting mutations are poorly tolerated in that critical domain.
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Affiliation(s)
- Larry S. Tobacman
- Departments of Medicine and of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL
| | - Anthony Cammarato
- Departments of Medicine and of Physiology, Johns Hopkins University, Baltimore, MD
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8
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Bunch TA, Lepak VC, Bortz KM, Colson BA. A high-throughput fluorescence lifetime-based assay to detect binding of myosin-binding protein C to F-actin. J Gen Physiol 2021; 153:e202012707. [PMID: 33600558 PMCID: PMC7898471 DOI: 10.1085/jgp.202012707] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 01/12/2021] [Indexed: 12/20/2022] Open
Abstract
Binding properties of actin-binding proteins are typically evaluated by cosedimentation assays. However, this method is time-consuming, involves multiple steps, and has a limited throughput. These shortcomings preclude its use in screening for drugs that modulate actin-binding proteins relevant to human disease. To develop a simple, quantitative, and scalable F-actin-binding assay, we attached fluorescent probes to actin's Cys-374 and assessed changes in fluorescence lifetime upon binding to the N-terminal region (domains C0-C2) of human cardiac myosin-binding protein C (cMyBP-C). The lifetime of all five probes tested decreased upon incubation with cMyBP-C C0-C2, as measured by time-resolved fluorescence (TR-F), with IAEDANS being the most sensitive probe that yielded the smallest errors. The TR-F assay was compared with cosedimentation to evaluate in vitro changes in binding to actin and actin-tropomyosin arising from cMyBP-C mutations associated with hypertrophic cardiomyopathy (HCM) and tropomyosin binding. Lifetime changes of labeled actin with added C0-C2 were consistent with cosedimentation results. The HCM mutation L352P was confirmed to enhance actin binding, whereas PKA phosphorylation reduced binding. The HCM mutation R282W, predicted to disrupt a PKA recognition sequence, led to deficits in C0-C2 phosphorylation and altered binding. Lastly, C0-C2 binding was found to be enhanced by tropomyosin and binding capacity to be altered by mutations in a tropomyosin-binding region. These findings suggest that the TR-F assay is suitable for rapidly and accurately determining quantitative binding and for screening physiological conditions and compounds that affect cMyBP-C binding to F-actin for therapeutic discovery.
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Affiliation(s)
| | | | | | - Brett A. Colson
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
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9
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Greenberg MJ, Tardiff JC. Complexity in genetic cardiomyopathies and new approaches for mechanism-based precision medicine. J Gen Physiol 2021; 153:211741. [PMID: 33512404 PMCID: PMC7852459 DOI: 10.1085/jgp.202012662] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Accepted: 01/07/2021] [Indexed: 12/11/2022] Open
Abstract
Genetic cardiomyopathies have been studied for decades, and it has become increasingly clear that these progressive diseases are more complex than originally thought. These complexities can be seen both in the molecular etiologies of these disorders and in the clinical phenotypes observed in patients. While these disorders can be caused by mutations in cardiac genes, including ones encoding sarcomeric proteins, the disease presentation varies depending on the patient mutation, where mutations even within the same gene can cause divergent phenotypes. Moreover, it is challenging to connect the mutation-induced molecular insult that drives the disease pathogenesis with the various compensatory and maladaptive pathways that are activated during the course of the subsequent progressive, pathogenic cardiac remodeling. These inherent complexities have frustrated our ability to understand and develop broadly effective treatments for these disorders. It has been proposed that it might be possible to improve patient outcomes by adopting a precision medicine approach. Here, we lay out a practical framework for such an approach, where patient subpopulations are binned based on common underlying biophysical mechanisms that drive the molecular disease pathogenesis, and we propose that this function-based approach will enable the development of targeted therapeutics that ameliorate these effects. We highlight several mutations to illustrate the need for mechanistic molecular experiments that span organizational and temporal scales, and we describe recent advances in the development of novel therapeutics based on functional targets. Finally, we describe many of the outstanding questions for the field and how fundamental mechanistic studies, informed by our more nuanced understanding of the clinical disorders, will play a central role in realizing the potential of precision medicine for genetic cardiomyopathies.
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Affiliation(s)
- Michael J Greenberg
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO
| | - Jil C Tardiff
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ.,Department of Medicine, University of Arizona, Tucson, AZ
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10
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Powers JD, Kooiker KB, Mason AB, Teitgen AE, Flint GV, Tardiff JC, Schwartz SD, McCulloch AD, Regnier M, Davis J, Moussavi-Harami F. Modulating the tension-time integral of the cardiac twitch prevents dilated cardiomyopathy in murine hearts. JCI Insight 2020; 5:142446. [PMID: 32931484 PMCID: PMC7605524 DOI: 10.1172/jci.insight.142446] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 09/09/2020] [Indexed: 12/13/2022] Open
Abstract
Dilated cardiomyopathy (DCM) is often associated with sarcomere protein mutations that confer reduced myofilament tension–generating capacity. We demonstrated that cardiac twitch tension-time integrals can be targeted and tuned to prevent DCM remodeling in hearts with contractile dysfunction. We employed a transgenic murine model of DCM caused by the D230N-tropomyosin (Tm) mutation and designed a sarcomere-based intervention specifically targeting the twitch tension-time integral of D230N-Tm hearts using multiscale computational models of intramolecular and intermolecular interactions in the thin filament and cell-level contractile simulations. Our models predicted that increasing the calcium sensitivity of thin filament activation using the cardiac troponin C (cTnC) variant L48Q can sufficiently augment twitch tension-time integrals of D230N-Tm hearts. Indeed, cardiac muscle isolated from double-transgenic hearts expressing D230N-Tm and L48Q cTnC had increased calcium sensitivity of tension development and increased twitch tension-time integrals compared with preparations from hearts with D230N-Tm alone. Longitudinal echocardiographic measurements revealed that DTG hearts retained normal cardiac morphology and function, whereas D230N-Tm hearts developed progressive DCM. We present a computational and experimental framework for targeting molecular mechanisms governing the twitch tension of cardiomyopathic hearts to counteract putative mechanical drivers of adverse remodeling and open possibilities for tension-based treatments of genetic cardiomyopathies. Tuning the molecular mechanisms that govern the twitch tension of cardiomyopathic hearts counteracts mechanical drivers of adverse remodeling.
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Affiliation(s)
- Joseph D Powers
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, Washington, USA.,Department of Bioengineering, Jacobs School of Engineering, University of California San Diego, La Jolla, California, USA
| | - Kristina B Kooiker
- Division of Cardiology, School of Medicine, University of Washington, Seattle, Washington, USA
| | - Allison B Mason
- Department of Chemistry and Biochemistry, College of Science, and
| | - Abigail E Teitgen
- Department of Bioengineering, Jacobs School of Engineering, University of California San Diego, La Jolla, California, USA
| | - Galina V Flint
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, Washington, USA
| | - Jil C Tardiff
- Department of Biomedical Engineering, College of Engineering, University of Arizona, Tucson, Arizona, USA
| | | | - Andrew D McCulloch
- Department of Bioengineering, Jacobs School of Engineering, University of California San Diego, La Jolla, California, USA.,Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Michael Regnier
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, Washington, USA
| | - Jennifer Davis
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, Washington, USA.,Department of Laboratory Medicine & Pathology, University of Washington, Seattle, Washington, USA
| | - Farid Moussavi-Harami
- Division of Cardiology, School of Medicine, University of Washington, Seattle, Washington, USA
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11
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Fochi S, Lorenzi P, Galasso M, Stefani C, Trabetti E, Zipeto D, Romanelli MG. The Emerging Role of the RBM20 and PTBP1 Ribonucleoproteins in Heart Development and Cardiovascular Diseases. Genes (Basel) 2020; 11:genes11040402. [PMID: 32276354 PMCID: PMC7230170 DOI: 10.3390/genes11040402] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 04/04/2020] [Accepted: 04/06/2020] [Indexed: 12/17/2022] Open
Abstract
Alternative splicing is a regulatory mechanism essential for cell differentiation and tissue organization. More than 90% of human genes are regulated by alternative splicing events, which participate in cell fate determination. The general mechanisms of splicing events are well known, whereas only recently have deep-sequencing, high throughput analyses and animal models provided novel information on the network of functionally coordinated, tissue-specific, alternatively spliced exons. Heart development and cardiac tissue differentiation require thoroughly regulated splicing events. The ribonucleoprotein RBM20 is a key regulator of the alternative splicing events required for functional and structural heart properties, such as the expression of TTN isoforms. Recently, the polypyrimidine tract-binding protein PTBP1 has been demonstrated to participate with RBM20 in regulating splicing events. In this review, we summarize the updated knowledge relative to RBM20 and PTBP1 structure and molecular function; their role in alternative splicing mechanisms involved in the heart development and function; RBM20 mutations associated with idiopathic dilated cardiovascular disease (DCM); and the consequences of RBM20-altered expression or dysfunction. Furthermore, we discuss the possible application of targeting RBM20 in new approaches in heart therapies.
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12
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Matyushenko AM, Levitsky DI. Molecular Mechanisms of Pathologies of Skeletal and Cardiac Muscles Caused by Point Mutations in the Tropomyosin Genes. BIOCHEMISTRY (MOSCOW) 2020; 85:S20-S33. [PMID: 32087052 DOI: 10.1134/s0006297920140023] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The review is devoted to tropomyosin (Tpm) - actin-binding protein, which plays a crucial role in the regulation of contraction of skeletal and cardiac muscles. Special attention is paid to myopathies and cardiomyopathies - severe hereditary diseases of skeletal and cardiac muscles associated with point mutations in Tpm genes. The current views on the molecular mechanisms of these diseases and the effects of such mutations on the Tpm structure and functions are considered in detail. Besides, some part of the review is devoted to analysis of the properties of Tpm homodimers and heterodimers with myopathic substitutions of amino acid residues in only one of the two chains of the Tpm dimeric molecule.
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Affiliation(s)
- A M Matyushenko
- Bach Institute of Biochemistry, Federal Research Center on Fundamentals of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia.
| | - D I Levitsky
- Bach Institute of Biochemistry, Federal Research Center on Fundamentals of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia. .,Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia
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13
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Lehman W, Rynkiewicz MJ, Moore JR. A new twist on tropomyosin binding to actin filaments: perspectives on thin filament function, assembly and biomechanics. J Muscle Res Cell Motil 2020; 41:23-38. [PMID: 30771202 PMCID: PMC6697252 DOI: 10.1007/s10974-019-09501-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Accepted: 02/07/2019] [Indexed: 02/07/2023]
Abstract
Tropomyosin, best known for its role in the steric regulation of muscle contraction, polymerizes head-to-tail to form cables localized along the length of both muscle and non-muscle actin-based thin filaments. In skeletal and cardiac muscles, tropomyosin, under the control of troponin and myosin, moves in a cooperative manner between blocked, closed and open positions on filaments, thereby masking and exposing actin-binding sites necessary for myosin crossbridge head interactions. While the coiled-coil signature of tropomyosin appears to be simple, closer inspection reveals surprising structural complexity required to perform its role in steric regulation. For example, component α-helices of coiled coils are typically zippered together along a continuous core hydrophobic stripe. Tropomyosin, however, contains a number of anomalous, functionally controversial, core amino acid residues. We argue that the atypical residues at this interface, including clusters of alanines and a charged aspartate, are required for preshaping tropomyosin to readily fit to the surface of the actin filament, but do so without compromising tropomyosin rigidity once the filament is assembled. Indeed, persistence length measurements of tropomyosin are characteristic of a semi-rigid cable, in this case conducive to cooperative movement on thin filaments. In addition, we also maintain that tropomyosin displays largely unrecognized and residue-specific torsional variance, which is involved in optimizing contacts between actin and tropomyosin on the assembled thin filament. Corresponding twist-induced stiffness may also enhance cooperative translocation of tropomyosin across actin filaments. We conclude that anomalous core residues of tropomyosin facilitate thin filament regulatory behavior in a multifaceted way.
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Affiliation(s)
- William Lehman
- Department of Physiology & Biophysics, Boston University School of Medicine, Boston, Massachusetts, U.S.A
| | - Michael J. Rynkiewicz
- Department of Physiology & Biophysics, Boston University School of Medicine, Boston, Massachusetts, U.S.A
| | - Jeffrey R. Moore
- Department of Biological Sciences, University of Massachusetts-Lowell, Lowell, Massachusetts, U.S.A
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14
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Aboelkassem Y, McCabe KJ, Huber GA, Regnier M, McCammon JA, McCulloch AD. A Stochastic Multiscale Model of Cardiac Thin Filament Activation Using Brownian-Langevin Dynamics. Biophys J 2019; 117:2255-2272. [PMID: 31547973 PMCID: PMC6990154 DOI: 10.1016/j.bpj.2019.08.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 07/31/2019] [Accepted: 08/02/2019] [Indexed: 11/16/2022] Open
Abstract
We use Brownian-Langevin dynamics principles to derive a coarse-graining multiscale myofilament model that can describe the thin-filament activation process during contraction. The model links atomistic molecular simulations of protein-protein interactions in the thin-filament regulatory unit to sarcomere-level activation dynamics. We first calculate the molecular interaction energy between tropomyosin and actin surface using Brownian dynamics simulations. This energy profile is then generalized to account for the observed tropomyosin transitions between its regulatory stable states. The generalized energy landscape then served as a basis for developing a filament-scale model using Langevin dynamics. This integrated analysis, spanning molecular to thin-filament scales, is capable of tracking the events of the tropomyosin conformational changes as it moves over the actin surface. The tropomyosin coil with flexible overlap regions between adjacent tropomyosins is represented in the model as a system of coupled stochastic ordinary differential equations. The proposed multiscale approach provides a more detailed molecular connection between tropomyosin dynamics, the trompomyosin-actin interaction-energy landscape, and the generated force by the sarcomere.
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Affiliation(s)
- Yasser Aboelkassem
- Department of Bioengineering, University of California San Diego, La Jolla, California.
| | - Kimberly J McCabe
- Department of Bioengineering, University of California San Diego, La Jolla, California
| | - Gary A Huber
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California
| | - Michael Regnier
- Department of Bioengineering, University of Washington, Seattle, Washington
| | - J Andrew McCammon
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California
| | - Andrew D McCulloch
- Department of Bioengineering, University of California San Diego, La Jolla, California
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15
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Liu L, Fei F, Zhang R, Wu F, Yang Q, Wang F, Sun S, Zhao H, Li Q, Wang L, Wang Y, Gui Y, Wang X. Combinatorial genetic replenishments in myocardial and outflow tract tissues restore heart function in tnnt2 mutant zebrafish. Biol Open 2019; 8:bio.046474. [PMID: 31796423 PMCID: PMC6918781 DOI: 10.1242/bio.046474] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Cardiac muscle troponin T (Tnnt2) mediates muscle contraction in response to calcium ion dynamics, and Tnnt2 mutations are associated with multiple types of cardiomyopathy. Here, we employed a zebrafish model to investigate the genetic replenishment strategies of using conditional and inducible promoters to rescue the deficiencies in the heart. tnnt2a mutations were induced in zebrafish via the CRISPR/Cas9 technique, and the mutants displayed heart arrest and dilated cardiomyopathy-like phenotypes. We first utilized the classic myocardial promoter of the myl7 and TetOn inducible system to restore tnnt2a expression in myocardial tissue in tnnt2a mutant zebrafish. However, this attempt failed to recover normal heart function and circulation, although heart pumping was partially restored. Further analyses via both RNA-seq and immunofluorescence indicated that Tnnt2a, which was also expressed in a novel group of myl7-negative smooth muscle cells on the outflow tract (OFT), was indispensably responsible for the normal mechanical dynamics of OFT. Lastly, tnnt2 expression induced by OFT cells in addition to the myocardial cells successfully rescued heart function and circulation in tnnt2a mutant zebrafish. Together, our results reveal the significance of OFT expression of Tnnt2 for cardiac function and demonstrate zebrafish larva as a powerful and convenient in vivo platform for studying cardiomyopathy and the relevant therapeutic strategies.
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Affiliation(s)
- Lian Liu
- Department of Cardiology, Children's Hospital of Fudan University, Shanghai 201102, China
| | - Fei Fei
- Cancer Metabolism Laboratory, Cancer Institute, Fudan University Shanghai Cancer Center, Shanghai 200032, China.,Key Laboratory of Metabolism and Molecular Medicine, Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai 230002, China
| | - Ranran Zhang
- Department of Pediatrics, the Affiliated Hospital of Qingdao University, Qingdao, Shangdong 266003, China
| | - Fang Wu
- Department of Cardiology, Children's Hospital of Fudan University, Shanghai 201102, China
| | - Qian Yang
- Department of Cardiology, Children's Hospital of Fudan University, Shanghai 201102, China
| | - Feng Wang
- Department of Cardiology, Children's Hospital of Fudan University, Shanghai 201102, China
| | - Shaoyang Sun
- Key Laboratory of Metabolism and Molecular Medicine, Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai 230002, China
| | - Hui Zhao
- Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200032, China
| | - Qiang Li
- Translational Medical Center for Development and Disease, Shanghai Key Laboratory of Birth Defect, Institute of Pediatrics, Children's Hospital of Fudan University, Shanghai 201102, China
| | - Lei Wang
- Key Laboratory of Metabolism and Molecular Medicine, Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai 230002, China
| | - Youhua Wang
- Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200032, China
| | - Yonghao Gui
- Department of Cardiology, Children's Hospital of Fudan University, Shanghai 201102, China
| | - Xu Wang
- Cancer Metabolism Laboratory, Cancer Institute, Fudan University Shanghai Cancer Center, Shanghai 200032, China .,Key Laboratory of Metabolism and Molecular Medicine, Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai 230002, China
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16
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Abdullah S, Lynn ML, McConnell MT, Klass MM, Baldo AP, Schwartz SD, Tardiff JC. FRET-based analysis of the cardiac troponin T linker region reveals the structural basis of the hypertrophic cardiomyopathy-causing Δ160E mutation. J Biol Chem 2019; 294:14634-14647. [PMID: 31387947 DOI: 10.1074/jbc.ra118.005098] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 07/12/2019] [Indexed: 11/06/2022] Open
Abstract
Mutations in the cardiac thin filament (TF) have highly variable effects on the regulatory function of the cardiac sarcomere. Understanding the molecular-level dysfunction elicited by TF mutations is crucial to elucidate cardiac disease mechanisms. The hypertrophic cardiomyopathy-causing cardiac troponin T (cTnT) mutation Δ160Glu (Δ160E) is located in a putative "hinge" adjacent to an unstructured linker connecting domains TNT1 and TNT2. Currently, no high-resolution structure exists for this region, limiting significantly our ability to understand its role in myofilament activation and the molecular mechanism of mutation-induced dysfunction. Previous regulated in vitro motility data have indicated mutation-induced impairment of weak actomyosin interactions. We hypothesized that cTnT-Δ160E repositions the flexible linker, altering weak actomyosin electrostatic binding and acting as a biophysical trigger for impaired contractility and the observed remodeling. Using time-resolved FRET and an all-atom TF model, here we first defined the WT structure of the cTnT-linker region and then identified Δ160E mutation-induced positional changes. Our results suggest that the WT linker runs alongside the C terminus of tropomyosin. The Δ160E-induced structural changes moved the linker closer to the tropomyosin C terminus, an effect that was more pronounced in the presence of myosin subfragment (S1) heads, supporting previous findings. Our in silico model fully supported this result, indicating a mutation-induced decrease in linker flexibility. Our findings provide a framework for understanding basic pathogenic mechanisms that drive severe clinical hypertrophic cardiomyopathy phenotypes and for identifying structural targets for intervention that can be tested in silico and in vitro.
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Affiliation(s)
- Salwa Abdullah
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, 85721
| | - Melissa L Lynn
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona, 85721
| | - Mark T McConnell
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona, 85721
| | - Matthew M Klass
- Department of Physiological Sciences, University of Arizona, Tucson, Arizona, 85721
| | - Anthony P Baldo
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona, 85721
| | - Steven D Schwartz
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona, 85721
| | - Jil C Tardiff
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, 85721 .,Department of Biomedical Engineering, University of Arizona, Tucson, Arizona, 85721.,Department of Physiological Sciences, University of Arizona, Tucson, Arizona, 85721.,Department of Medicine, University of Arizona, Tucson, Arizona 85721
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17
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Thin filament dysfunctions caused by mutations in tropomyosin Tpm3.12 and Tpm1.1. J Muscle Res Cell Motil 2019; 41:39-53. [PMID: 31270709 PMCID: PMC7109180 DOI: 10.1007/s10974-019-09532-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 06/26/2019] [Indexed: 12/14/2022]
Abstract
Tropomyosin is the major regulator of the thin filament. In striated muscle its function is to bind troponin complex and control the access of myosin heads to actin in a Ca2+-dependent manner. It also participates in the maintenance of thin filament length by regulation of tropomodulin and leiomodin, the pointed end-binding proteins. Because the size of the overlap between actin and myosin filaments affects the number of myosin heads which interact with actin, the filament length is one of the determinants of force development. Numerous point mutations in genes encoding tropomyosin lead to single amino acid substitutions along the entire length of the coiled coil that are associated with various types of cardiomyopathy and skeletal muscle disease. Specific regions of tropomyosin interact with different binding partners; therefore, the mutations affect diverse tropomyosin functions. In this review, results of studies on mutations in the genes TPM1 and TPM3, encoding Tpm1.1 and Tpm3.12, are described. The paper is particularly focused on mutation-dependent alterations in the mechanisms of actin-myosin interactions and dynamics of the thin filament at the pointed end.
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18
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Szatkowski L, Lynn ML, Holeman T, Williams MR, Baldo AP, Tardiff JC, Schwartz SD. Proof of Principle that Molecular Modeling Followed by a Biophysical Experiment Can Develop Small Molecules that Restore Function to the Cardiac Thin Filament in the Presence of Cardiomyopathic Mutations. ACS OMEGA 2019; 4:6492-6501. [PMID: 31342001 PMCID: PMC6649307 DOI: 10.1021/acsomega.8b03340] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 03/28/2019] [Indexed: 06/10/2023]
Abstract
This article reports a coupled computational experimental approach to design small molecules aimed at targeting genetic cardiomyopathies. We begin with a fully atomistic model of the cardiac thin filament. To this we dock molecules using accepted computational drug binding methodologies. The candidates are screened for their ability to repair alterations in biophysical properties caused by mutation. Hypertrophic and dilated cardiomyopathies caused by mutation are initially biophysical in nature, and the approach we take is to correct the biophysical insult prior to irreversible cardiac damage. Candidate molecules are then tested experimentally for both binding and biophysical properties. This is a proof of concept study-eventually candidate molecules will be tested in transgenic animal models of genetic (sarcomeric) cardiomyopathies.
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Affiliation(s)
- Lukasz Szatkowski
- Department
of Chemistry and Biochemistry, University
of Arizona, Tucson, Arizona 85721, United States
| | - Melissa L. Lynn
- Department of Physiological
Sciences and Department of Medicine, University of Arizona, Tucson, Arizona 85724, United States
| | - Teryn Holeman
- Department of Physiological
Sciences and Department of Medicine, University of Arizona, Tucson, Arizona 85724, United States
| | - Michael R. Williams
- Department
of Chemistry and Biochemistry, University
of Arizona, Tucson, Arizona 85721, United States
| | - Anthony P. Baldo
- Department
of Chemistry and Biochemistry, University
of Arizona, Tucson, Arizona 85721, United States
| | - Jil C. Tardiff
- Department of Physiological
Sciences and Department of Medicine, University of Arizona, Tucson, Arizona 85724, United States
| | - Steven D. Schwartz
- Department
of Chemistry and Biochemistry, University
of Arizona, Tucson, Arizona 85721, United States
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19
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Moving beyond simple answers to complex disorders in sarcomeric cardiomyopathies: the role of integrated systems. Pflugers Arch 2019; 471:661-671. [PMID: 30848350 DOI: 10.1007/s00424-019-02269-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 03/01/2019] [Indexed: 12/26/2022]
Abstract
The classic clinical definition of hypertrophic cardiomyopathy (HCM) as originally described by Teare is deceptively simple, "left ventricular hypertrophy in the absence of any identifiable cause." Longitudinal studies, however, including a seminal study performed by Frank and Braunwald in 1968, clearly described the disorder much as we know it today, a complex, progressive, and highly variable cardiomyopathy affecting ~ 1/500 individuals worldwide. Subsequent genetic linkage studies in the early 1990s identified mutations in virtually all of the protein components of the cardiac sarcomere as the primary molecular cause of HCM. In addition, a substantial proportion of inherited dilated cardiomyopathy (DCM) has also been linked to sarcomeric protein mutations. Despite our deep understanding of the overall function of the sarcomere as the primary driver of cardiac contractility, the ability to use genotype in patient management remains elusive. A persistent challenge in the field from both the biophysical and clinical standpoints is how to rigorously link high-resolution protein dynamics and mechanics to the long-term cardiovascular remodeling process that characterizes these complex disorders. In this review, we will explore the depth of the problem from both the standpoint of a multi-subunit, highly conserved and dynamic "machine" to the resultant clinical and structural human phenotype with an emphasis on new, integrative approaches that can be widely applied to identify both novel disease mechanisms and new therapeutic targets for these primary biophysical disorders of the cardiac sarcomere.
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20
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Matyushenko AM, Koubassova NA, Shchepkin DV, Kopylova GV, Nabiev SR, Nikitina LV, Bershitsky SY, Levitsky DI, Tsaturyan AK. The effects of cardiomyopathy-associated mutations in the head-to-tail overlap junction of α-tropomyosin on its properties and interaction with actin. Int J Biol Macromol 2018; 125:1266-1274. [PMID: 30240712 DOI: 10.1016/j.ijbiomac.2018.09.105] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Revised: 09/15/2018] [Accepted: 09/17/2018] [Indexed: 10/28/2022]
Abstract
Tropomyosin (Tpm) plays a crucial role in the regulation of muscle contraction by controlling actin-myosin interaction. Tpm coiled-coil molecules bind each other via overlap junctions of their N- and C-termini and form a semi-rigid strand that binds the helical surface of an actin filament. The high bending stiffness of the strand is essential for high cooperativity of muscle regulation. Point mutations M8R and K15N in the N-terminal part of the junction and the A277V one in the C-terminal part are associated with dilated cardiomyopathy, while the M281T and I284V mutations are related to hypertrophic cardiomyopathy. To reveal molecular mechanism(s) underlying these pathologies, we studied the properties of recombinant Tpm carrying these mutations using several experimental approaches and molecular dynamic simulation of the junction. The M8R and K15N mutations weakened the interaction between the N- and C-termini of Tpm in the overlap junction and reduced the Tpm affinity for actin. These changes possibly led to a reduction in the regulation cooperativity. The C-terminal mutations caused only small and controversial changes in properties of Tpm and its complex with actin. Their involvement in disease phenotype is possibly caused by interaction with other sarcomere proteins.
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Affiliation(s)
- Alexander M Matyushenko
- Bach Institute of Biochemistry, Research Centre of Biotechnology of the Russian Academy of Sciences, 33 Leninsky prosp., Moscow 119071, Russia; Institute of Immunology and Physiology, Russian Academy of Sciences, 91 Pervomayskaya ul., Yekaterinburg 620049, Russia
| | - Natalia A Koubassova
- Institute of Immunology and Physiology, Russian Academy of Sciences, 91 Pervomayskaya ul., Yekaterinburg 620049, Russia; Institute of Mechanics, Moscow State University, 1 Mitchurinsky prosp., Moscow 119192, Russia
| | - Daniil V Shchepkin
- Institute of Immunology and Physiology, Russian Academy of Sciences, 91 Pervomayskaya ul., Yekaterinburg 620049, Russia
| | - Galina V Kopylova
- Institute of Immunology and Physiology, Russian Academy of Sciences, 91 Pervomayskaya ul., Yekaterinburg 620049, Russia
| | - Salavat R Nabiev
- Institute of Immunology and Physiology, Russian Academy of Sciences, 91 Pervomayskaya ul., Yekaterinburg 620049, Russia
| | - Larisa V Nikitina
- Institute of Immunology and Physiology, Russian Academy of Sciences, 91 Pervomayskaya ul., Yekaterinburg 620049, Russia
| | - Sergey Y Bershitsky
- Institute of Immunology and Physiology, Russian Academy of Sciences, 91 Pervomayskaya ul., Yekaterinburg 620049, Russia
| | - Dmitrii I Levitsky
- Bach Institute of Biochemistry, Research Centre of Biotechnology of the Russian Academy of Sciences, 33 Leninsky prosp., Moscow 119071, Russia; Belozersky Institute of Physico-Chemical Biology, Moscow State University, 1 Leninskiye Gory bld. 40, Moscow 119234, Russia
| | - Andrey K Tsaturyan
- Institute of Mechanics, Moscow State University, 1 Mitchurinsky prosp., Moscow 119192, Russia.
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21
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Bondue A, Arbustini E, Bianco A, Ciccarelli M, Dawson D, De Rosa M, Hamdani N, Hilfiker-Kleiner D, Meder B, Leite-Moreira AF, Thum T, Tocchetti CG, Varricchi G, Van der Velden J, Walsh R, Heymans S. Complex roads from genotype to phenotype in dilated cardiomyopathy: scientific update from the Working Group of Myocardial Function of the European Society of Cardiology. Cardiovasc Res 2018; 114:1287-1303. [PMID: 29800419 PMCID: PMC6054212 DOI: 10.1093/cvr/cvy122] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 05/05/2018] [Accepted: 05/16/2018] [Indexed: 12/14/2022] Open
Abstract
Dilated cardiomyopathy (DCM) frequently affects relatively young, economically, and socially active adults, and is an important cause of heart failure and transplantation. DCM is a complex disease and its pathological architecture encounters many genetic determinants interacting with environmental factors. The old perspective that every pathogenic gene mutation would lead to a diseased heart, is now being replaced by the novel observation that the phenotype depends not only on the penetrance-malignancy of the mutated gene-but also on epigenetics, age, toxic factors, pregnancy, and a diversity of acquired diseases. This review discusses how gene mutations will result in mutation-specific molecular alterations in the heart including increased mitochondrial oxidation (sarcomeric gene e.g. TTN), decreased calcium sensitivity (sarcomeric genes), fibrosis (e.g. LMNA and TTN), or inflammation. Therefore, getting a complete picture of the DCM patient will include genomic data, molecular assessment by preference from cardiac samples, stratification according to co-morbidities, and phenotypic description. Those data will help to better guide the heart failure and anti-arrhythmic treatment, predict response to therapy, develop novel siRNA-based gene silencing for malignant gene mutations, or intervene with mutation-specific altered gene pathways in the heart.This article is part of the Mini Review Series from the Varenna 2017 meeting of the Working Group of Myocardial Function of the European Society of Cardiology.
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Affiliation(s)
- Antoine Bondue
- Department of Cardiology, CUB Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium
| | - Eloisa Arbustini
- Centre for Inherited Cardiovascular Diseases, IRCCS Foundation, University Hospital Policlinico San Matteo, Pavia, Italy
| | - Anna Bianco
- Department of Translational Medical Sciences, Federico II University, Naples, Italy
- Department of Cardiology, Maastricht University Medical Center & CARIM, Maastricht University, Maastricht, The Netherlands
| | - Michele Ciccarelli
- School of Medicine, Surgery and Dentistry, University of Salerno, Salerno, Italy
| | - Dana Dawson
- School of Medicine and Dentistry, University of Aberdeen, Aberdeen, UK
| | - Matteo De Rosa
- School of Medicine, Surgery and Dentistry, University of Salerno, Salerno, Italy
| | - Nazha Hamdani
- Department of Systems Physiology, Ruhr University Bochum, Bochum, Germany
| | - Denise Hilfiker-Kleiner
- Molecular Cardiology, Department of Cardiology and Angiology, Hannover Medical School, Hannover, Germany
| | - Benjamin Meder
- Department of Cardiology, Heidelberg University, Heidelberg, Germany
- Department of Genetics, Stanford University School of Medicine, Genome Technology Center, Palo Alto, CA, USA
| | - Adelino F Leite-Moreira
- Cardiovascular R&D Unit, Department of Surgery and Physiology, Faculty of Medicine, University of Porto, Porto, Portugal
- Department of Cardiothoracic Surgery, Hospital of S. João, Porto, Portugal
| | - Thomas Thum
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Hannover, Germany
| | - Carlo G Tocchetti
- Department of Translational Medical Sciences, Federico II University, Naples, Italy
| | - Gilda Varricchi
- Department of Translational Medical Sciences, Federico II University, Naples, Italy
| | - Jolanda Van der Velden
- Department of Physiology, VU University Medical Centre, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
- Netherlands Heart Institute, Utrecht, The Netherlands
| | - Roddy Walsh
- Cardiovascular Research Center, Royal Brompton and Harefield NHS Foundation Trust and Imperial College London, London, UK
| | - Stephane Heymans
- Department of Cardiology, Maastricht University Medical Center & CARIM, Maastricht University, Maastricht, The Netherlands
- Netherlands Heart Institute, Utrecht, The Netherlands
- Department of Cardiovascular Sciences, Leuven University, Leuven, Belgium
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22
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Williams MR, Tardiff JC, Schwartz SD. Mechanism of Cardiac Tropomyosin Transitions on Filamentous Actin As Revealed by All-Atom Steered Molecular Dynamics Simulations. J Phys Chem Lett 2018; 9:3301-3306. [PMID: 29863359 PMCID: PMC6019281 DOI: 10.1021/acs.jpclett.8b00958] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The three-state model of tropomyosin (Tm) positioning along filamentous actin allows for Tm to act as a gate for myosin head binding with actin. The blocked state of Tm prevents myosin binding, while the open state allows for strong binding. Intermediate to this transition is the closed state. The details of the transition from the blocked to the closed state and then finally to the open state by Tm have not been fully accessible to experiment. Utilizing steered molecular dynamics, we investigate the work required to move the Tm strand through the extant set of proposed transitions. We find that an azimuthal motion around the actin filament by Tm is most probable in spite of increased initial energy barrier from the topographical landscape of actin.
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Affiliation(s)
- Michael R. Williams
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, United States
| | - Jil C. Tardiff
- Department of Medicine, The University of Arizona, Tucson, Arizona 85724, United States
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona 85724, United States
| | - Steven D. Schwartz
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, United States
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23
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Abstract
This article focuses on three "bins" that comprise sets of biophysical derangements elicited by cardiomyopathy-associated mutations in the myofilament. Current therapies focus on symptom palliation and do not address the disease at its core. We and others have proposed that a more nuanced classification could lead to direct interventions based on early dysregulation changing the trajectory of disease progression in the preclinical cohort. Continued research is necessary to address the complexity of cardiomyopathic progression and develop efficacious therapeutics.
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Affiliation(s)
- Melissa L Lynn
- Department of Medicine, University of Arizona, Room 317, 1656 East Mabel Street, Tucson, AZ 85724, USA
| | - Sarah J Lehman
- Department of Physiological Sciences, University of Arizona, Room 317, 1656 East Mabel Street, Tucson, AZ 85724, USA
| | - Jil C Tardiff
- Department of Medicine, University of Arizona, Room 312, 1656 East Mabel Street, Tucson, AZ 85724, USA.
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