Promotes Sheep Granulosa Cells Proliferation and Reproductive Hormone Secretion and Activates the PI3K/AKT Pathway.

Neurotrophin receptor B (), also named , belongs to the neurotrophic factor family. Previous studies have shown that is associated with high fertility in mammals. However, the molecular mechanism and regulatory pathway of this neurotrophic factor remain unclear. In this study, overexpression and -siRNA were constructed to detect the effects of on the proliferation and hormone secretion of the ovarian granulosa cells (GCs) of sheep. We successfully isolated follicular phase granulosa cells in vitro from the ovaries of sheep in simultaneous estrus, and the immunofluorescence results confirmed that was expressed in the collected cells. Subsequently, the effect of on the proliferation of sheep granulosa cells was examined via cell transfection experiments. The results showed that the expression of and was significantly increased after overexpression, while the opposite trend was observed after the inhibition of expression ( < 0.05). The EdU and CCK-8 assays showed that the proliferation rate of sheep GCs was significantly increased after overexpression, while the opposite trend was observed after the inhibition of expression ( < 0.05). Moreover, significantly increased the expression of steroidogenesis-related genes, including steroidogenic acute regulatory protein () and hydroxy-δ-5-steroid dehydrogenase (), and cytochrome P450 family 19 subfamily A member 1 (). The ELISA results showed that the secretion levels of E and P significantly increased after overexpression, while the opposite trend was observed after the inhibition of expression ( < 0.05). Previous studies had confirmed that gene belongs to the PI3K-AKT signaling pathway and participates in the signaling of this pathway. This was demonstrated by protein-protein interaction analysis and NTRK2 belongs to the PI3K-AKT pathway. The modification of PI3K and AKT, markers of the PI3K-AKT pathway, via phosphorylation was increased after overexpression in the sheep GCs, while the opposite trend was observed after the inhibition of expression ( < 0.05). Overall, these results suggest that the gene regulates the proliferation of GCs and the secretion of steroid hormones in sheep, and that it influences the phosphorylation level of the PI3K/AKT signaling pathway. These findings provided a theoretical basis and new perspectives for exploring the regulation of gene in the development of ovine follicles.