Long Non-coding RNA LOC105611671 Modulates Fibroblast Growth Factor 9 (FGF9) Expression by Targeting Oar-miR-26a to Promote Testosterone Biosynthesis in Hu Sheep

Fibroblast growth factors (FGFs) play crucial roles in early gonadal development and germ cell maturation of mammals; FGF9 is involved in mammalian testis steroidogenesis. However, the upstream regulators of FGF9 in ovine testosterone biosynthesis remain unknown. Long non-coding RNAs (lncRNAs) are crucial regulators of multiple biological functions that act by altering gene expression. In the present study, we analysed the role of LOC105611671, a lncRNA upstream of FGF9, in Hu sheep steroidogenesis. We found that LOC105611671 expression increased significantly in Hu sheep testes during sexual maturation (P<0.05). Moreover, levels of FGF9 and testosterone were decreased by LOC105611671 knockdown in Hu sheep Leydig cells (LCs). Results of transient transfection and luciferase assays revealed that FGF9 is a functional target gene of oar-miR-26a in ovine LCs. Further functional validation experiments revealed that LOC105611671 regulates testosterone biosynthesis by targeting oar-miR-26a. Overall, the present study describes the expression profile of LOC105611671 during sexual maturation and demonstrates that LOC105611671 modulates FGF9 expression by targeting oar-miR-26a to promote testis steroidogenesis in Hu sheep. Our research provides a new theoretical basis for genetic and molecular research on testosterone biosynthesis in sheep.