CircRNA-1436 mediates miR-29b-5p/RCAN1 axis to promote the apoptosis of secondary hair follicle dermal papilla cells in cashmere goats via m6A modification.

M6A (N6 methyladenosine) modification is a dynamic and reversible post transcriptional chemical modification of RNAs, widely distributed in eukaryotic cells. As an important form of epigenetics, it acts as an RNA switch, regulating RNA processing, degradation, and translation, to affect the biological processes such as cell differentiation, apoptosis, and embryonic development, etc. through binding mechanisms with other RNAs and proteins. This study focuses on Inner Mongolia Albas white cashmere goats, the role of m6A modified circRNA-1436 in SHF DPC apoptosis of cashmere goats was studied through qRT-PCR, FISH, CCK-8 and dual -luciferase reporter experiments, flow cytometry, etc. The results showed that m6A modified circRNA-1436 was mainly expressed in the nucleus of DPCs. The expression levels of m6A modified circRNA-1436 were significant different in the different growth stage skins of cashmere goat SHFs, the expression level was highest in telogen, followed by catagen, and lowest in anagen. Overexpression of m6A modified circRNA-1436 could promote the apoptosis of DPCs, while interference with m6A modified circRNA-1436 inhibited DPCs apoptosis. CircRNA-1436 competitively bound to miR-29b-5p, promoting RCAN1 gene expression and DPC apoptosis. After m6A site mutation, the expression level of circRNA-1436 in DPCs significantly increased, and the number of apoptotic cells decreased, indicating that circRNA-1436 regulates DPC apoptosis by m6A modification. The research results have laid a theoretical foundation for further in-depth study on the regulation mechanism of SHF periodic growth.