A Contraction Stress Model of Hypertrophic Cardiomyopathy due to Sarcomere Mutations.

Rachel Cohn,Katherine Atamanuk,Emily Meredith,Ketan Thakar,Andre Lowe,Bryan D Huey,Anthony M Pettinato,Feria A Ladha,Robert Romano,J Travis Hinson,Yu-Sheng Chen

doi:10.1016/j.stemcr.2018.11.015

Rachel Cohn, Katherine Atamanuk + Show 9 more

Open Access

https://doi.org/10.1016/j.stemcr.2018.11.015

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Abstract

SummaryThick-filament sarcomere mutations are a common cause of hypertrophic cardiomyopathy (HCM), a disorder of heart muscle thickening associated with sudden cardiac death and heart failure, with unclear mechanisms. We engineered four isogenic induced pluripotent stem cell (iPSC) models of β-myosin heavy chain and myosin-binding protein C3 mutations, and studied iPSC-derived cardiomyocytes in cardiac microtissue assays that resemble cardiac architecture and biomechanics. All HCM mutations resulted in hypercontractility with prolonged relaxation kinetics in proportion to mutation pathogenicity, but not changes in calcium handling. RNA sequencing and expression studies of HCM models identified p53 activation, oxidative stress, and cytotoxicity induced by metabolic stress that can be reversed by p53 genetic ablation. Our findings implicate hypercontractility as a direct consequence of thick-filament mutations, irrespective of mutation localization, and the p53 pathway as a molecular marker of contraction stress and candidate therapeutic target for HCM patients.

Highlights

Hypertrophic cardiomyopathy (HCM) is a human disorder that affects 1 in 500 individuals with uncertain mechanisms (Maron et al, 1995)
Generation of HCM induced pluripotent stem cell (iPSC) and cardiac microtissues (CMTs) Models Using CRISPR/Cas9 We began by identifying two HCM mutations in MYH7, R403Q and V606M, which cause autosomal dominant HCM in both humans (Geisterfer-Lowrance et al, 1990; Marian et al, 1995) and mice (Blankenburg et al, 2014; Geisterfer-Lowrance et al, 1996)
Both mutations are located in subfragment 1 (S1) of MHC-b near the actin-interacting domain (Figure 1A), but R403Q leads to a more severe cardiomyopathy compared with V606M (Blankenburg et al, 2014)

Summary

Introduction

Hypertrophic cardiomyopathy (HCM) is a human disorder that affects 1 in 500 individuals with uncertain mechanisms (Maron et al, 1995). Over the last few decades, the genetic basis of HCM has been demonstrated by inheritance of autosomal dominant mutations in components of the force-producing sarcomere (Maron et al, 2012). About two-thirds of HCM patients harbor heterozygous mutations in one of two sarcomere genes: myosin heavy chain b (MHC-b is encoded by MYH7) or myosin-binding protein C (cMyBP-C is encoded by MYBPC3) (Maron et al, 2012). A prevailing model suggests that HCM mutations alter cardiac force generation through dysregulation of calcium handling (Ashrafian et al, 2011; Lan et al, 2013). Whether MYBPC3 and MYH7 mutations result in HCM by shared or heterogeneous mechanisms remains undetermined

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