G9a inhibits MEF2C activity to control sarcomere assembly

Area of Science:

• Molecular Biology
• Epigenetics
• Muscle Physiology

Background:

• Sarcomeres are crucial for muscle contraction, and their dysfunction is linked to skeletal muscle diseases.
• The lysine methyltransferase G9a's role in sarcomere organization is not well understood.
• Understanding sarcomere regulation is key to developing treatments for myopathies.

Purpose of the Study:

• To investigate the role of G9a in sarcomere organization.
• To elucidate the regulatory mechanism involving G9a, MEF2C, and HDAC5 in skeletal muscle cells.
• To identify potential therapeutic targets for muscle diseases.

Main Methods:

• Investigated G9a's effect on sarcomere organization and gene expression.
• Utilized protein interaction assays to study G9a, MEF2C, and HDAC5 interactions.
• Examined the impact of calcium signaling and CaMK activation on the regulatory axis.

Main Results:

• G9a represses sarcomere gene expression and disrupts sarcomere integrity.
• G9a inhibits MEF2C transcriptional activity by interacting with MEF2C and HDAC5.
• G9a blocks calcium signaling-dependent HDAC5 export, enhancing MEF2C-HDAC5 association.
• Calcium signaling or CaMK activation rescues G9a-mediated repression.

Conclusions:

• G9a epigenetically controls sarcomere assembly through the MEF2C-HDAC5 axis.
• This study reveals a novel mechanism regulating muscle function.
• Identified potential therapeutic strategies for skeletal and cardiac myopathies.