Coordinate Nodal and BMP inhibition directs Baf60c-dependent cardiomyocyte commitment

Area of Science:

• Cardiovascular Biology
• Stem Cell Differentiation
• Epigenetics

Background:

• Cardiomyocyte differentiation is crucial for heart development and regeneration but remains poorly understood at the molecular level.
• Identifying the signaling pathways that commit progenitor cells to the cardiomyocyte lineage is essential for therapeutic applications.

Purpose of the Study:

• To elucidate the molecular mechanisms underlying cardiomyocyte commitment from multipotent progenitors.
• To investigate the role of Cerberus-1 (Cer1) and the SWI/SNF chromatin remodeling complex in cardiac lineage specification.

Main Methods:

• Utilized embryonic stem cell cultures to study progenitor cell differentiation.
• Employed siRNA to inhibit key factors like Cer1, Baf60c, and Brg1.
• Assessed chromatin accessibility using Nkx2.5 early cardiac enhancer assays.
• Performed overexpression studies to rescue differentiation deficits.

Main Results:

• Cerberus-1 (Cer1) antagonizes Nodal and BMP signaling, inducing Brahma-associated factor 60c (Baf60c) in multipotent progenitors.
• Baf60c interacts with cardiac transcription factors Gata4 and Tbx5, facilitating SWI/SNF complex recruitment to cardiomyogenic loci.
• Inhibition of Cer1, Baf60c, or Brg1 impaired chromatin opening and cardiomyocyte differentiation, while Baf60c overexpression rescued these defects.

Conclusions:

• Cerberus-1 (Cer1) acts upstream of Baf60c and SWI/SNF to orchestrate cardiomyocyte differentiation.
• The progenitor cell environment dictates SWI/SNF subunit composition to remodel chromatin for lineage-specific gene activation.
• This study reveals a novel epigenetic mechanism controlling cardiac lineage commitment.