PS48 promotes in vitro maturation and developmental competence of porcine oocytes through activating PI3K/Akt signalling pathway

Oocyte maturation plays a vitally important role in porcine reproduction. Regrettably, the quality of oocytes matured in vitro is weaker than that of in vivo matured oocytes. We collected and cultivated porcine cumulus oocyte complexes (COCs) in vitro with phosphoinositide-dependent kinase 1 (PDK1) activator 5-(4-chloro-phenyl)-3-phenyl-pent-2-enoic acid (PS48), whose concentrations were 0, 2, 5, 10 and 20 µM to investigate whether the phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt) signalling pathway would impact the oocyte quality. The results showed that 10 µM PS48 increased the oocyte proportion of metaphase II (MII) stage and improved the expansion of cumulus cells (CCs). What's more, the activation of PI3K/Akt signalling pathway could regulate the expression of maturation-related genes and proteins. The results of quantitative Real-Time PCR showed that 10 µM PS48 increased the mRNA and protein levels of Akt and regulated maturation-related genes, including cyclin B1, MOS, BMP15, GDF9, CDC2, mTOR, Bax, BCL2 and Caspase-3. The results of Western blot indicated that 10µM PS48 increased the protein abundance of Akt, phosphorylation of Akt Thr308 (p-Akt^Thr308 ) and cyclin B1, but decreased the protein abundance of pro-apoptotic Bax. These results suggested that adding 10 µM PS48 to mature culture medium could promote the maturation of porcine oocytes, potentially through activating the PI3K/Akt signalling pathway.