Signaling pathways of Periplaneta americana peptide resist HO-induced apoptosis in pig-ovary granulosa cells through FoxO1.

Granulosa cell apoptosis induced by oxidative stress is an important cause of follicular atresia. Our previous studies found that Periplaneta americana peptide (PAP) decreased HO-induced apoptosis of pig-ovary granulosa cells (PGCs) through FoxO1. The aim of this study is to investigate the signaling pathways involved in PAP resistance against HO-induced apoptosis of PGCs. PGCs obtained from the follicles of non-estrous Duroc × Landrace × Yorkshire gilts (5 months old, 50-55 kg) were treated with HO and PAP, or together with inhibitors against PI3K and JNK, and then collected for ROS levels and SOD activities detection, TUNEL staining, qRT-PCR, western blotting, immunofluorescence or coimmunoprecipitation. Results showed that the increased ROS levels and decreased activities of SOD caused by HO stimulation were reversed by PAP. Additionally, PAP downregulated the differential abundance of mRNA of Bax and FasL, thus inhibiting HO-induced apoptosis of PGCs. PAP significantly reduces p-JNK expression and increases the p-FoxO1/FoxO1 expression ratio, thereby decreasing caspase-3 expression and cell apoptosis in HO-induced PGCs. PAP promotes the combination of FoxO1 with the 14-3-3 protein, increases FoxO1 translocation to the cytoplasm, and decreases FoxO1 acetylation. Therefore, PAP regulates FoxO1 expression through the JNK/FoxO1 signaling pathway and effects the translocation of FoxO1 to the cytoplasm by the FoxO1 interaction with 14-3-3, enabling reversal of the HO-induced apoptosis of PGCs. Acetylation of FoxO1 is also involved in the antiapoptotic effect of PAP.