Effect of the LIF gene on the cell cycle and apoptosis of ovarian granulosa cells in white Muscovy ducks

Leukaemia inhibitory factor (LIF), a member of the interleukin-6 (IL-6) family, is a multifunctional cytokine. The maturation-to-ovulation process of poultry follicles is determined by granulosa cell proliferation and differentiation. Granulosa cell apoptosis and degeneration lead to follicular atresia, which reduces the number of normally developing follicles and leads to a decrease in the poultry egg production rate, thus affecting the large-scale development of poultry breeding. In this study, the LIF gene overexpression vector pCDH-CMV-LIF and a siRNA that inhibits LIF gene expression were transfected into primary granulosa cells from white Muscovy duck ovaries for functional study. Compared with that in the control group, LIF gene expression was confirmed to be significantly decreased or increased in the transfection groups (P < 0.01). After LIF overexpression, the expression of the cell cycle-related genes CCND1, CDK-1 and PCNA was decreased (P < 0.05); apoptosis was promoted; the proapoptotic genes Bax and caspase-3 were significantly upregulated (P < 0.01); and the antiapoptotic gene Bcl-2 was significantly downregulated (P < 0.01). After LIF interference, the expression of the cell cycle-related genes CCND1, CCNE1, CDK-1 and PCNA and the antiapoptotic gene Bcl-2 significantly increased (P < 0.01), whereas the expression of the proapoptotic genes Bax, caspase-3 and caspase-9 significantly decreased (P < 0.01). In summary, the LIF gene is involved in regulating the biological function of ovarian granulosa cells in white Muscovy ducks. LIF gene expression promotes granulosa cell apoptosis and inhibits cell cycle progression. These experimental results provide insights into the follicular development mechanism of white Muscovy ducks.