Myocardial infarction in mice alters sarcomeric function via post-translational protein modification

Area of Science:

• Cardiology
• Molecular Biology
• Biochemistry

Background:

• Myocardial physiology post-myocardial infarction (MI) before cardiac remodeling is not well understood.
• Reactive oxygen species (ROS) may play a role in early post-MI cardiac dysfunction.

Purpose of the Study:

• To investigate the effects of MI on cardiac sarcomere structure and function.
• To explore the contribution of protein oxidation to these early post-MI changes.

Main Methods:

• Surgically induced MI in female CD1 mice.
• Echocardiography to assess cardiac function.
• Analysis of detergent-extracted cardiac fiber bundles and myofibrillar preparations.
• Biochemical assays for protein post-translational modifications (phosphorylation, oxidation, S-glutathionylation).

Main Results:

• MI hearts showed ventricular dilatation and systolic dysfunction.
• Increased Ca(2+) sensitivity and decreased cooperativity of activation in cardiac fibers.
• Reduced Ca-ATPase activity in myofilament myosin.
• Decreased phosphorylation of troponin I and myosin light chain 2.
• Oxidation and S-glutathionylation of sarcomeric proteins, including tropomyosin.

Conclusions:

• MI induces significant structural and functional alterations in the cardiac sarcomere shortly after injury.
• Protein oxidation is a key contributor to early sarcomere dysfunction following MI.
• These findings highlight potential therapeutic targets for preserving cardiac function post-MI.