Myosins and MyomiR Network in Patients with Obstructive Hypertrophic Cardiomyopathy

Area of Science:

• Cardiovascular Biology
• Molecular Medicine
• Genetic Diseases

Background:

• Hypertrophic cardiomyopathy (HCM) is a primary genetic heart muscle disorder.
• The molecular underpinnings of HCM's diverse clinical presentations remain unclear.
• Understanding gene and protein regulation in HCM is crucial for therapeutic development.

Purpose of the Study:

• To investigate the relationship between clinical phenotype, cardiac myosin expression, and the MyomiR network in HCM.
• To identify molecular mechanisms contributing to HCM pathophysiology.
• To explore potential therapeutic targets within the myosin/MyomiR axis.

Main Methods:

• Analysis of myocardial biopsies from HCM patients and controls using mass spectrometry and RNA sequencing.
• Laser-capture microdissection to isolate cardiomyocytes for gene expression analysis.
• In vitro studies using induced pluripotent stem cell-derived cardiomyocytes to model MyomiR-gene interactions.

Main Results:

• Reduced cardiac myosin heavy chain 6 (MyHC6) protein in HCM compared to controls.
• Elevated MYH7, MYH7B, and MYLC2 gene expression in HCM, with comparable MYH6 levels.
• Upregulation of Mhrt and specific miR-499 target genes (SOX6, PTBP3) in HCM, with mutations correlating to PTBP3 and SOX6.
• In vitro studies showed a time-dependent link between MyomiRs and myosin genes, mimicking HCM findings.

Conclusions:

• HCM exhibits an uncoupling between myosin protein and gene expression.
• The myosin/MyomiR network plays a modulatory role in HCM myocardium.
• These findings suggest potential therapeutic strategies targeting the MyomiR network for HCM treatment.