Dihydrotestosterone Promotes Hetian Sheep Dermal Papilla Cell Proliferation by Inhibiting the TGF-β/Smad Signalling Pathway.

Hair follicles, as key accessory organs in mammalian skin, are precisely regulated for growth and development influenced by genetic factors, hormones, and the local microenvironment. This study investigated the effect of dihydrotestosterone (DHT) on the proliferation of dermal papilla cells (DPCs) from Xinjiang Hetian sheep and its regulatory relationship with the TGF-β/Smad signalling pathway. DPCs were isolated from the back skin tissue of newborn Hetian sheep by collagenase II digestion, and their characteristics were identified by primary culture, passage, and double immunofluorescence staining with α-SMA and CD133 labelling. CCK-8 and EdU assays were used to evaluate the effect of varying DHT concentrations (0, 1, 10, 100, and 1000 nM) on DPC proliferation. The results showed that with the increased DHT concentration, cell proliferation also increased, and the highest rate was observed at 1000 nM. Furthermore, qPCR analysis revealed that 1000 nM DHT significantly upregulated Smad6 gene expression (p < 0.05), while it inhibited the expression of TGF-β1, TGF-βRII, and Smad5 (p < 0.05). These findings suggest that high DHT concentrations may promote DPC proliferation by inhibiting the TGF-β/Smad signalling pathway. This suggests a critical role of this pathway in regulating hair follicle development and hormone-dependent hair growth, providing evidence for the molecular mechanism of androgen action on dermal papilla cell function.