All-trans retinoic acid modulates proliferation and apoptosis of secondary hair follicle–dermal papilla cells in cashmere goats via the TGF-β2/Smad2/3 pathway

Transcriptomic analysis indicated enrich ment of the transforming growth factor-β (TGF-β) signaling pathway. Therefore, mRNA and protein levels of TGF-β2—a follicle growth–related regulator—and Smad2/3 phosphorylation were examined. The TGF-β type I/II receptor inhibitor LY2109761 was used to further validate the involvement of this pathway.

ATRA inhibited SHF-DPC proliferation by inducing G1-phase cell cycle arrest and pro moted apoptosis by upregulating Bax expression while downregulating Bcl-2 protein expression. Transcriptomic analysis showed that ATRA upregulated TGFβ2 expression in SHF-DPCs. Gene Ontology analysis revealed enrichment of genes related to proliferation and apoptosis, such as “cell migration” and “cell cycle.” Kyoto Encyclopedia of Genes and Genomes pathway analysis identified the TGF β signaling pathway as a major regulatory target.

Treatment with LY2109761 par tially reversed ATRA-induced reductions in proliferation, increases in apoptosis, and elevations in Smad2/3 phosphorylation. Overall, ATRA inhibits proliferation and promotes apoptosis in SHF-DPCs, likely through the TGF-β2/Smad2/3 path way. These findings provide novel insights into ATRA-mediated regulation of hair growth and offer a theoretical basis for future research on cashmere goat SHF development.