Activation of p38/MEF2C pathway by all-trans retinoic acid in cardiac myoblasts

Area of Science:

• Cardiovascular Biology
• Molecular Cell Biology
• Developmental Biology

Background:

• Myocyte enhancer factor 2C (MEF2C) is a key transcription factor in cardiac muscle development.
• The precise mechanisms by which all-trans retinoic acid (atRA) influences MEF2C activity in cardiomyocytes remain incompletely understood.
• Investigating atRA's role in cardiomyocyte signaling is crucial for understanding heart development.

Purpose of the Study:

• To elucidate the regulatory mechanism of atRA on MEF2C activity in H9c2 rat ventricular cells.
• To determine the involvement of the p38 mitogen-activated protein kinase (MAPK) pathway in atRA-mediated MEF2C regulation.
• To explore the subcellular localization and interaction dynamics of p38 MAPK and MEF2C under atRA treatment.

Main Methods:

• Western blot analysis to detect protein phosphorylation.
• Protein kinase assays to assess kinase activity.
• Luciferase reporter assays to measure MEF2C transactivation.
• Confocal microscopy and immunoprecipitation to study protein localization and interaction.
• Pharmacological inhibition using SB202190 to block p38 MAPK nuclear translocation.

Main Results:

• atRA treatment induced phosphorylation of p38 MAPK and MEF2C in H9c2 cells.
• p38 MAPK activity was found to upregulate the transactivation function of MEF2C.
• atRA promoted the nuclear translocation of p38 MAPK, facilitating its interaction with MEF2C.
• Inhibition of p38 MAPK nuclear translocation by SB202190 blocked these effects.

Conclusions:

• atRA activates the p38 MAPK signaling pathway in cardiomyocytes.
• The p38 MAPK pathway mediates atRA-induced MEF2C activation and nuclear translocation.
• These findings suggest that the p38/MEF2C signaling pathway is a key mechanism through which atRA influences heart development.