MicroRNA let-7a and let-7f as novel regulatory factors of the sika deer (Cervus nippon) IGF-1R gene.

MicroRNAs and their roles in rapid antler growth and regeneration have attracted much attention. In the present study, we examined the effects of microRNAs let-7a and let-7f on antler cell proliferation. We used a luciferase reporter screen to demonstrate that insulin-like growth factor 1 receptor (IGF-1R) can be regulated by let-7a and let-7f. MTT assay confirmed that chondrocyte proliferation was inhibited by let-7a and let-7f mimics. In contrast, transfection of let-7a and let-7f inhibitors increased chondrocyte proliferation, indicating that inhibitors can competitively bind to endogenous miRNA, reducing the inhibitory effect of miRNA. Moreover, western blotting analysis further identified that let-7a and let-7f mimics suppressed IGF-1R expression, and that let-7a and let-7f inhibitors increased the expression level of IGF-1R. Taken together, our study demonstrates the important roles of let-7a and let-7f in antler proliferation and its potential application in antler development. let-7a and let-7f may represent novel regulatory factors of IGF-1R expression in deer antler.