MicroRNA-216b inhibits heat stress-induced cell apoptosis by targeting Fas in bovine mammary epithelial cells.

Heat stress affects milk yield and quality in lactating dairy cows in summer. Bovine mammary epithelial cells (bMECs) play a key role in milk secretion, and microRNAs (miRNAs) regulate numerous functions of bMEC. Previous reports have verified that miR-216b regulated cell apoptosis through repressing target genes in several cancer cells. So, our purpose was to explore the potential involvement of miR-216b in heat stress-induced cell apoptosis in bMECs. Firstly, the heat stress model was constructed and we found that apoptotic rates of bMECs significantly increased under heat stress. The expression of miR-216b, Bax mRNA, and caspase-3 mRNA was upregulated. However, Bcl-2 mRNA level was detected to differentially downregulated. Overexpression of miR-216b remarkably downregulated the expression of caspase-3 and Bax mRNA and protein, and the mRNA and protein level of Bcl-2 was increased. Inhibition of miR-216b increased the activity of caspase-3 and Bax, and the level of Bcl-2 was inhibited. Moreover, Fas was identified as a target gene of miR-216b through bioinformatic analysis and dual-luciferase reporter assay. Fas activity was significantly inhibited and enhanced respectively after transfecting miRNA mimics and inhibitor. Finally, inhibition of Fas via the small interfering RNA (siRNA) also inhibited cell apoptosis induced by heat stress. Taken together, our results indicated that miR-216b exerted as an anti-apoptotic effect under heat stress in bMECs by targeting Fas.