The long-term goal of this research program is to develop a rigorously experimentally validated all-atom computational model of the cardiac thin filament (CTF) bound to myosin S1 which provides a unique and accessible platform to identify novel, high resolution disease mechanisms linked to Hypertrophic Cardiomyopathy (HCM). In the prior funding period, we refined and extended our existing CTF computational model and successfully employed it to identify unique and clinically relevant allosteric disease mechanisms including HCM mutation-induced changes in myofilament Ca2+ kinetics, mutation-specific molecular causes of differential cardiac remodeling and disease progression. This included an in vivo validation via the development of a novel transgenic mouse model of cTnT-linked dilated cardiomyopathy and a predictive algorithm to determine the pathogenicity of cTnT mutations that out-performed existing computational approaches in a preliminary test. The key to these advances has been the ability of the current model to precisely identify and locate allosteric changes caused by mutations throughout all components of the CTF followed by closely coupled experimental validation and eventual in vivo model correlation. We now propose to significantly expand the biological complexity of the model to include myosin S1, the molecular motor that drives contraction and the second most common genetic cause of HCM. This important and challenging advance will facilitate a deeper understanding of disease pathogenesis by, for the first time, incorporating the role of molecular allosteric mechanisms between myosin S1 and thin filament. This new computational ? experimental platform will be used for both mechanistic insight (for example used for the identification of novel myofilament disease targets,) and the development of a comprehensive deep-learning predictive algorithm to assign pathogenicity to both myosin and thin filament HCM mutations. The latter represents the first use of high-resolution structure, dynamics and function to predict HCM disease allele pathogenicity, a central challenge in the clinical management of these complex patients. Both the training and testing components of the deep learning development will utilize data from the highly annotated and curated SHaRe HCM registry thus greatly improving translational power.
Two Specific Aims will be pursued:
Aim 1 will utilize state of the art rare event simulation methods developed in one of our groups and refinement of existing unstructured domains of the CTF via FRET to establish the new model.
Aim 2 will employ an extensive program of computational analysis and subsequent in vitro validation using pathogenic, variants of unknown significance and non- pathogenic HCM alleles derived from SHaRe to provide inputs to the machine learning environment for algorithm development. Novel disease mechanisms for myosin and thin filament HCM that include crosstalk between the two components will also be explored. Elucidation of these mechanisms can be the basis for robust molecular approaches to disease.

Public Health Relevance

Precision medicine and ?molecular? medicine are concepts that aim to employ a patient?s genetic structure to discern the best medical treatments for disease. Hypertrophic cardiomyopathy is a genetic disease that afflicts 1/500 people. This application translates our knowledge of the molecular level effects of cardiac tissue mutation to disease and will aim to lead to eventual treatment.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
2R01HL107046-10
Application #
10071638
Study Section
Cardiac Contractility, Hypertrophy, and Failure Study Section (CCHF)
Program Officer
Adhikari, Bishow B
Project Start
2010-12-15
Project End
2024-07-31
Budget Start
2020-08-15
Budget End
2021-07-31
Support Year
10
Fiscal Year
2020
Total Cost
Indirect Cost
Name
University of Arizona
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
806345617
City
Tucson
State
AZ
Country
United States
Zip Code
85721
Williams, Michael R; Tardiff, Jil C; Schwartz, Steven D (2018) Mechanism of Cardiac Tropomyosin Transitions on Filamentous Actin As Revealed by All-Atom Steered Molecular Dynamics Simulations. J Phys Chem Lett 9:3301-3306
Lynn, M L; Tal Grinspan, L; Holeman, T A et al. (2017) The structural basis of alpha-tropomyosin linked (Asp230Asn) familial dilated cardiomyopathy. J Mol Cell Cardiol 108:127-137
McConnell, Mark; Tal Grinspan, Lauren; Williams, Michael R et al. (2017) Clinically Divergent Mutation Effects on the Structure and Function of the Human Cardiac Tropomyosin Overlap. Biochemistry 56:3403-3413
Williams, Michael R; Lehman, Sarah J; Tardiff, Jil C et al. (2016) Atomic resolution probe for allostery in the regulatory thin filament. Proc Natl Acad Sci U S A 113:3257-62
Tardiff, Jil C (2016) The Role of Calcium/Calmodulin-Dependent Protein Kinase II Activation in Hypertrophic Cardiomyopathy. Circulation 134:1749-1751
Tardiff, Jil C; Carrier, Lucie; Bers, Donald M et al. (2015) Targets for therapy in sarcomeric cardiomyopathies. Cardiovasc Res 105:457-70
Duncker, Dirk J; Bakkers, Jeroen; Brundel, Bianca J et al. (2015) Animal and in silico models for the study of sarcomeric cardiomyopathies. Cardiovasc Res 105:439-48
Moore, Rachel K; Abdullah, Salwa; Tardiff, Jil C (2014) Allosteric effects of cardiac troponin TNT1 mutations on actomyosin binding: a novel pathogenic mechanism for hypertrophic cardiomyopathy. Arch Biochem Biophys 552-553:21-8
Moore, Rachel K; Grinspan, Lauren Tal; Jimenez, Jesus et al. (2013) HCM-linked ?160E cardiac troponin T mutation causes unique progressive structural and molecular ventricular remodeling in transgenic mice. J Mol Cell Cardiol 58:188-98
Tardiff, Jil C (2012) It's never too early to look: subclinical disease in sarcomeric dilated cardiomyopathy. Circ Cardiovasc Genet 5:483-6

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