Simple Summary Inner Mongolia Albas white cashmere goat is a unique biological resource in Northwest China, and the cashmere produced by goat is sold well at home and abroad because of its softness and warmth. Cashmere is the product of the growth and development of secondary hair follicles, and dermal papilla cells (DPCs) are the seeds of hair follicle growth and development, which are regulated by a variety of factors in growth and development. At present, the regulation mechanism of Shh gene on DPCs of secondary hair follicles in cashmere goats is not clear. In this study, we found that Shh gene expression was significantly higher in anagen than in catagen and telogen in the secondary hair follicles of cashmere goats, and the proliferation and viability of DPCs after overexpressing Shh gene were increased, whereas the apoptosis of DPCs after interfering with Shh gene was elevated. In addition to this, we demonstrated that Shh gene promotes the expression of the related genes Ptched (Ptch), Smoothened (Smo), and GLI Family Zinc Finger 2 (Gli2) in the Hedgehog signaling pathway. Therefore, this study reveals that Shh regulates the genes related to the Hedgehog signaling pathway to affect the proliferation and apoptosis of dermal papilla cells, leading to the differential expression of the Shh gene in the secondary hair follicle growth cycle of cashmere goats. The result is of great significance for the study of the pathway regulation mechanism of secondary hair follicles in cashmere goat and provides a theoretical direction for the positive development of the cashmere industry.Abstract Sonic hedgehog (Shh) is a component of the Hedgehog signaling pathway, playing an important role in regulating cell proliferation, differentiation, apoptosis, and the repair of damaged organisms. To further clarify the expression pattern of Shh gene in the secondary hair follicle growth cycle of cashmere goats and its mechanism of action on secondary hair follicle papilla cells, and improve cashmere quality, in this study, we took Inner Mongolia Albas white cashmere goats as the research objects and collected skin samples at different growth stages to obtain secondary hair follicles, detected Shh and its gene expression by RT-qPCR, Western blot, immunohistochemistry, and other techniques, while we also cultured DPCs in vitro. Shh gene overexpression and interference vectors were constructed, and the effects of Shh gene on the proliferation and apoptosis of DPCs were studied through cell transfection technology. The results showed that there are significant differences in Shh and its gene expression in the secondary hair follicle growth cycle skins of cashmere goats, with the highest expression level in anagen, followed by catagen, and the lowest expression level in telogen. Shh was mainly expressed in the inner root sheath, outer root sheath, and secondary hair follicle papilla. After the overexpression of Shh gene, the proliferation and vitality of the hair papilla cells were enhanced compared to the interference group. After Shh gene interference, the apoptosis rate of the cells increased, indicating that Shh gene can regulate downstream Ptch, Smo, and Gli2 gene expression to promote the proliferation of DPCs, and thus form its expression pattern in the secondary hair follicle growth cycle of cashmere goats.
