miR-27a Targeting PIK3R3 Regulates the Proliferation and Apoptosis of Sheep Hair Follicle Stem Cells

SIMPLE SUMMARY: The quality of wool is directly related to the development of hair follicles. The effect of hair follicles on hair growth is related to the processes of proliferation, differentiation and apoptosis of hair follicle stem cells (HFSCs). Therefore, research on HFSCs in agricultural animals is rapidly gaining attention. The microRNA miR-27a has been shown to be involved in several diseases, such as lung cancer, ischemic stroke, neurofibromatosis and acute myocardial infarction, but the role of miR-27a in hair follicle development has not been studied. Here, we revealed that miR-27a is involved in the proliferation and apoptosis of HFSCs through its inhibition of the AKT/MTOR signaling pathway by targeting PIK3R3. We identified an miR-27a/PIK3R3 regulatory network with potential implications for hair follicle development and wool quality. ABSTRACT: Micro RNAs are regulatory factors in tissue development, organ formation, cell growth, apoptosis and other biological processes. In particular, several miRNAs are related to the development of hair follicles. Here, we investigated the effect of the targeting of PIK3R3 by miR-27a on the AKT/MTOR pathway and on the proliferation and apoptosis of hair follicle stem cells (HFSCs) in sheep. Knockdown of the expression of PIK3R3 was found to significantly inhibit the proliferation and promote the apoptosis of HFSCs. Similarly, a miR-27a mimic significantly inhibited the proliferation and promoted the apoptosis of HFSCs. The miR-27a mimic was also shown to significantly inhibit the expression of PIK3R3, AKT, and MTOR and the phosphorylation of AKT and MTOR, while a miR-27a inhibitor increased the expression of these genes. The presence of an miR-27a binding site in the 3′ UTR of PIK3R3 was identified by a bioinformatics analysis, and the interaction was verified with a dual-luciferase reporter assay. The expression of PIK3R3 mRNA and protein was negatively correlated with the presence of miR-27a, which suggests that this interaction may be involved in the biological impacts on proliferation and apoptosis. Thus, this study demonstrates that miR-27a plays a potential role in the proliferation and apoptosis of sheep hair follicle stem cells by targeting PIK3R3, which can be used to design new methods to improve sheep wool.