chi-miR-27a-3p Negatively Modulates Dermal Papilla Cell Proliferation and Directly Targets Wnt7B in Inner Mongolia Cashmere Goat: Evidence for a Potential Melatonin–chi-miR-27a-3p–Wnt7B Regulatory Relationship

Background: Melatonin is an important regulator of seasonal hair follicle activity in Inner Mongolia cashmere goats, but the miRNA-mediated mechanisms linking melatonin signaling to dermal papilla cell (DPC) function remain incompletely understood. In the present study, we examined the role of chi-miR-27a-3p in melatonin-treated DPCs. Methods: DPCs were isolated from Inner Mongolia cashmere goats and treated with melatonin or transduced with lentiviral constructs for chi-miR-27a-3p knockdown or overexpression. Cell proliferation was assessed by CCK8 and Ki67 immunofluorescence, cell-cycle distribution and apoptosis by flow cytometry, and the chi-miR-27a-3p–Wnt7B interaction by dual-luciferase reporter assay; the expression of Wnt7B, Wnt10b, β-catenin, SFRP1 and DKK1 was measured by qRT-PCR and Western blotting. Results: Melatonin treatment was accompanied by downregulation of chi-miR-27a-3p. Chi-miR-27a-3p overexpression reduced DPC proliferation and increased apoptosis, whereas its inhibition increased CCK-8 signal and promoted cell-cycle progression while reducing apoptosis; Ki67 fluorescence was not significantly changed in the knockdown group. Dual-luciferase assays showed that chi-miR-27a-3p directly targets the Wnt7B 3′-UTR in a sequence-dependent manner, and chi-miR-27a-3p manipulation was accompanied by reciprocal changes in Wnt7B, Wnt10b, β-catenin, SFRP1 and DKK1 expression. Conclusions: These findings support a potential regulatory relationship between melatonin, chi-miR-27a-3p and Wnt7B in DPCs; however, whether chi-miR-27a-3p is required for melatonin-induced proliferation and whether Wnt7B mediates its cellular effects require further rescue experiments and in vivo validation.