CircERCC6 Positively Regulates the Induced Activation of SHF Stem Cells in Cashmere Goats via the miR-412-3p/BNC2 Axis in an m 6 A-Dependent Manner.

Simple Summary: Cashmere goats have been widely raised in northern China, and they have great economic importance to local farmers and herders. The cashmere is one of the main uses of cashmere goats, and it is produced from the secondary hair follicles (SHFs) of cashmere goats. The biological event of induced activation of SHF stem cells by the dermal papilla cell-derived signals is essential to the anagen initiation and reconstruction of cashmere goat SHFs; however, its precise molecular mechanism is still unknown. In the present investigation, the expression level of m⁶A-modified circERCC6 (m⁶A-circERCC6) was found to be significantly higher at anagen SHF bulge than that of telogen. Further, we demonstrated that the circERCC6 positively regulates the induced activation of SHF stem-cells via the miR-412-3p/BNC2 axis in cashmere goats, and the m⁶A modification of circERCC6 is required for its function exertion. The obtained results provided a novel molecular basis for uncovering the intrinsic regulatory mechanisms of the induced activation process of SHF stem cells in cashmere goats. Also, the results will provide significant information for improving the SHF regeneration ability of cashmere goats with the growth of cashmere fibers. The cashmere, a kind of nature protein fiber, is one of the main use of cashmere goats. The induced activation of secondary hair follicle (SHF) stem cells by the dermal papilla cell-derived signals is a key biological process for the morphogenesis and growth of cashmere fiber in cashmere goats. Previously, the circRNA-ERCC6 (circERCC6) was identified from cashmere goat SHFs; however, its biological significance is unclear in the SHF physiology process of cashmere goats. In this study, we found that circERCC6 exhibited significantly higher expression at anagen SHF bulge compared with the counterpart of telogen and harbored three m⁶A modified sites (named m⁶A-685, m⁶A-862, and m⁶A-995) through methylation immunoprecipitation using a real-time quantitative polymerase chain reaction (Me-RIP-qPCR) technique. The knockdown experiments of circERCC6 in SHF stem cells showed that circERCC6 positively regulates the induced activation of SHF stem cells in cashmere goats. Through a dual-luciferase reporter assay, we demonstrated that m⁶A-modified circERCC6 (m⁶A-circERCC6) sponged miR-412-3p to upregulate the expression of BNC2 mRNA in SHFstem cells. Through m⁶A-deficient mutant assay in circERCC6 knockdown SHF stem cells, we further showed that m⁶A modification within circERCC6 is required to mediate the miR-412-3p/BNC2 axis to finally promote the proper induced activation of SHF stem cells in cashmere goats. [ABSTRACT FROM AUTHOR]