Lin28B overexpression decreases let-7b and let-7g levels and increases proliferation and estrogen secretion in Dolang sheep ovarian granulosa cells

Although ovine puberty initiation has been previously studied, the mechanism by which the RNA-binding protein Lin28B affects this process has not been investigated. The present study aimed to investigate the effects of Lin28B overexpression on let-7b, let-7g, cell proliferation, and estrogen secretion in Dolang sheep ovine ovarian granulosa cells. In this study, a Lin28B vector was constructed and transfected into ovarian granulosa cells using liposomes. After 24, 48, and 72 h of overexpression, quantitative real-time PCR (qRT-PCR) was used for measuring let-7b and let-7g microRNA (miRNA) levels, and estrogen secretion was measured using the enzyme-linked immunosorbent assay (ELISA). A CCK-8 (Cell Counting Kit-8) kit was used for evaluating cell viability and proliferation in response to Lin28B overexpression at 24 h. The results showed that the expression of let-7b and let-7g decreased significantly after Lin28B overexpression, and the difference was consistent over different periods. The result of ELISA showed that estradiol (E2) levels significantly increased following Lin28B overexpression. Additionally, Lin28B overexpression significantly increased the cell viability and proliferation. Therefore, the Lin28B–let-7 family axis may play a key role in the initiation of female ovine puberty.