A Contraction Stress Model of Hypertrophic Cardiomyopathy due to Sarcomere Mutations

Area of Science:

• Cardiology
• Molecular Biology
• Stem Cell Research

Background:

• Thick-filament sarcomere mutations are a primary cause of hypertrophic cardiomyopathy (HCM).
• The underlying mechanisms of HCM, including sudden cardiac death and heart failure, remain unclear.
• Understanding these mechanisms is crucial for developing effective treatments.

Purpose of the Study:

• To engineer and analyze induced pluripotent stem cell (iPSC) models of HCM caused by specific mutations.
• To investigate the functional consequences of these mutations in iPSC-derived cardiomyocytes.
• To identify molecular pathways involved in HCM pathogenesis and potential therapeutic targets.

Main Methods:

• Engineered four isogenic iPSC models for β-myosin heavy chain and myosin-binding protein C3 mutations.
• Utilized cardiac microtissue assays to study iPSC-derived cardiomyocyte function.
• Performed RNA sequencing and expression studies to analyze molecular changes.

Main Results:

• All engineered HCM mutations caused hypercontractility with prolonged relaxation kinetics.
• Mutation pathogenicity correlated with the severity of hypercontractility.
• p53 pathway activation, oxidative stress, and cytotoxicity were identified, linked to metabolic stress.
• These molecular changes were reversible upon p53 genetic ablation.

Conclusions:

• Hypercontractility is a direct consequence of thick-filament mutations in hypertrophic cardiomyopathy.
• The p53 pathway serves as a molecular marker for contraction stress in HCM.
• The p53 pathway represents a potential therapeutic target for hypertrophic cardiomyopathy patients.