MiR-376c-3p Targets STRBP mRNA to Regulate Cashmere Goat Hair Follicle Stem Cell Proliferation and Multipotency by Inhibiting the Wnt/β-Catenin and BMP Signaling Pathways.

The quality of cashmere fiber is fundamentally determined by the embryonic morphogenesis of hair follicles, a process highly dependent on the normal function of hair follicle stem cells (HFSCs). MicroRNAs (miRNAs) are key post-transcriptional regulators, but their specific roles in cashmere goat hair follicle development remain unclear. In this study, we identified the differentially expressed miRNA, miR-376c-3p, by analyzing transcriptomic data from embryonic skin (E65, E90, E120) of cashmere goats. Functional assays, including CCK8, crystal violet staining, clonogenic assay, and analysis of proliferation/apoptosis-related proteins (PCNA, CDK4, MKI67, BCL2, CAS3 and CAS9), demonstrated that miR-376c-3p significantly inhibited HFSCs proliferation, induced apoptosis, and blocked the differentiation process, as evidenced by the downregulation of differentiation-associated keratins (KRT4, KRT10, KRT14) and the upregulation of stemness maintenance factors (OCT4, NANOG, SOX9 and KRT15). Mechanistic investigations revealed that miR-376c-3p directly bound to the 3'UTR of STRBP mRNA and inhibited its expression, which was validated by a dual-luciferase reporter assay. Conversely, overexpression of STRBP promoted HFSCs proliferation and differentiation. Further analysis found that STRBP functioned by activating the Wnt/β-catenin and BMP signaling pathways, whereas miR-376c-3p inhibited these same pathways. In summary, this study elucidates a novel regulatory axis: miR-376c-3p influencing the Wnt/β-catenin and BMP signaling cascades in HFSCs by targeting STRBP mRNA, thereby regulating cell fate. This research provides important insights into the molecular mechanisms of miRNA-mediated hair follicle morphogenesis and stem cell biology in cashmere goats.