HDAC4 regulates satellite cell proliferation and differentiation by targeting P21 and Sharp1 genes

Area of Science:

• Muscle regeneration
• Epigenetics
• Stem cell biology

Background:

• Skeletal muscle regeneration relies on satellite cells, which are regulated by epigenetic mechanisms.
• Histone deacetylase 4 (HDAC4) is implicated in satellite cell proliferation and commitment, but its molecular targets remain unknown.

Purpose of the Study:

• To elucidate the signaling pathways regulated by HDAC4 in satellite cells.
• To identify direct molecular targets of HDAC4 in the context of muscle stem cell function.

Main Methods:

• Generation of tamoxifen-inducible mice with conditional inactivation of HDAC4 in Pax7-expressing cells (HDAC4 KO mice).
• Assessment of satellite cell proliferation and differentiation in HDAC4-deficient cells.
• RNA-sequencing analysis to identify HDAC4 target genes.
• Validation of identified targets by reducing their expression in HDAC4 KO satellite cells.

Main Results:

• Conditional inactivation of HDAC4 in satellite cells compromised their proliferation and differentiation.
• HDAC4 inhibition alone was sufficient to block satellite cell differentiation.
• RNA-sequencing identified P21 and Sharp1 as direct HDAC4 target genes.
• Reducing P21 and Sharp1 expression in HDAC4 KO cells further defined HDAC4-regulated pathways.

Conclusions:

• HDAC4 plays a critical role in the epigenetic regulation of satellite cell expansion and fusion.
• P21 and Sharp1 are key molecular targets mediating HDAC4's function in muscle stem cell biology.
• Understanding HDAC4's targets provides insights into the molecular mechanisms governing skeletal muscle regeneration.