Identification of developmental competence-related genes in mature porcine oocytes.

Oocyte competence is a key factor limiting female fertility, yet the underlying molecular mechanisms that contribute to oocyte competence remain unclear. The objective of this study was to elucidate specific genes whose function contributes to oocyte competence. We observed that 6 of 20 target genes examined were differentially expressed between adult (more competent) and prepubertal (less competent) porcine in vitro matured (IVM) oocytes. These genes were the cholesterol synthesis-related gene HMG-CoA reductase (HMGCR), fatty acid oxidation genes acyl-CoA synthetase long-chain family member 3 (ACSL3) and long-chain acyl-CoA dehydrogenase (ACADL), glycolytic genes fructose 1,6 bisphosphate aldolase (ALDOA) and lactate dehydrogenase C (LDHC), and tumor necrosis factor-α (TNF). These 6 genes, as well as 3 other genes [porcine endogenous retrovirus (PERV), transcribed loci 10 (TL10), serine/arginine-rich splicing factor 1 (SRSF1)], were further analyzed by comparing transcript abundance in IVM and in vivo matured (VVM) prepubertal and adult porcine oocytes. Among these 9 target genes, 5 were differentially expressed between IVM and VVM prepubertal oocytes, while 8 genes were differentially expressed between IVM and VVM adult oocytes. No genes were differentially expressed between VVM prepubertal and adult oocytes. A functional study of TNF demonstrated that depletion of endogenous TNF decreased oocyte competence and TNFAIP6 expression in cumulus cells, while TNF in IVM medium regulated TNFAIP6 expression in cumulus cells. Differential expression of the genes identified in this study suggests that these genes may be functionally relevant to oocyte competence.