Effects of Growth Differentiation Factor 9 and Bone Morphogenic Protein 15 on the In Vitro Maturation of Porcine Oocytes

다국어 초록 (Multilingual Abstract)

Growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) are members of the transforming growth factor β (TGF-β) family, and their roles in oocyte maturation and cumulus expansion are well known in the mouse and human, but not in the pig. We investigated GDF9 and BMP15 expression in porcine oocytes during in vitro maturation. A significant increase in the mRNA levels of GDF9 and BMP15 was observed at germinal vesicle breakdown, with expression levels peaking at metaphase I (MI) but decreasing at metaphase II (MII). GDF9 and BMP15 protein localized to the oocyte cytoplasm. While treatment with GDF9 and BMP15 increased cumulus expansion and the expression of genes involved in both oocyte maturation (c-mos, cyclinb1, and cdc2) and cumulus expansion (has2, ptgs2, ptx3, and tnfaip6). SB431542 (a TGFβ–GDF9 inhibitor) decreased meiotic maturation at MII. Following parthenogenetic activation, the percentage of blastocysts in SB431542 treatment was lower than in the control (74.4% and 41.3%, respectively). Treatment with GDF9 and BMP15 also increased the mRNA levels of maternal genes such as c-mos (a regulatory subunit of mitogen-activated protein kinase (MAPK)), and cyclinb1 and cdc2 (regulatory subunits of maturation/M phase promoting factor (MPF)); however, SB431-542 significantly decreased their mRNA levels. These data were supported by poly (A)-test PCR and protein activity analyses. Our results show that GDF9 and BMP15 function in cumulus expansion and that they stimulate MPF and MAPK activity in porcine oocytes during in vitro maturation.