Mechanisms by which missense variants in myosin and myosin binding protein C alter cellular contractility in genetic cardiomyopathies. (360G-Wellcome-206466_Z_17_Z)

Summary: The cardiac sarcomere is a multi-protein complex essential to cardiac contractile function. Hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) are caused by pathogenic variants (PV) in sarcomere protein genes. Variants in genes directly involved in cellular contractility MYH7 (beta-myosin heavy chain), MYH6 (alpha-myosin heavy chain), and MYBPC3 (Myosin binding protein C) are either known or hypothesised to cause disease. Previous analyses of the mechanisms by which variants cause disease have relied on rodent models and extrapolation from clinical data. The introduction of clinically defined mutations into human iPSC-CMs using CRISPR/Cas-9 would allow the interrogation of these cellular phenotypes in a human background using molecular and mechanical strategies, adding clarity to the uncertainties of variant-phenotype relationships in these genes. Key goals: i) Interrogation of the molecular and biophysical (contraction and relaxation) mechanisms by which PVs in MYH7, MYH6, and MYBPC3 cause either HCM or DCM. ii) Define the contractile mechanism of MYH6 and MYH7 PVs to establish if they mirror one another. iii) Investigate if high throughput functional analyses of iPSC-CMs can be used to test individual variants of unknown clinical significance (VUS) to discriminate between those that are disease causing versus ‘benign’.