140 EXPRESSION OF PERILIPIN IN PORCINE OOCYTES AND CUMULUS CELLS AT DIFFERENT STAGES OF IN VITRO MATURATION

Abstract

Perilipin, one of the perilipin adipophilin tail-interacting protein of 47 kDa (PAT) family, has been found to coat the surface of intracellular lipid droplets. It limits the interaction of lipases with intracellular lipid droplets and is involved in the formation and regulation of lipids in various kinds of cells. However, little is known about the effect of perilipin on porcine oocytes and cumulus cells. Therefore, this study aimed to detect the expression of perilipin1 (PLIN1), perilipin2 (PLIN2), perilipin3 (PLIN3), and perilipin4 (PLIN4) in porcine oocytes and cumulus cells at 4 stages of in vitro maturation (IVM) by quantitative real-time PCR (RT-qPCR). Germinal vesicle (GV), germinal vesicle breakdown (GVBD), metaphase I (MI), and metaphase II (MII) stage were found to occur predominantly at 18 to 24 h, after 24 h, 30 to 36 h, and 36 to 44 h of IVM, respectively. Cumulus-oocyte complexes (COC) were cultured in IVM medium and oocytes and cumulus cells were isolated after different durations of IVM (20, 26, 32, and 44 h). The data were analysed by one-way ANOVA using GraphPad Prism 5.0 (GraphPad Software, Sn Diego, CA, USA) and the threshold for statistical significance was set at P < 0.05. Messenger RNA expression of PLIN1 was not detected in either oocytes or cumulus cells during all periods of IVM. PLIN2, on the other hands, showed a significant lower expression in GVBD, MI, and MII oocytes compared with the GV oocytes, but showed no difference in cumulus cells. PLIN3 expression was significantly decreased in oocytes of MI stage, whereas PLIN3 from cumulus cells was expressed significantly lower in GVBD and MII stage compared with GV stage. Expression of PLIN4 was significantly decreased in only cumulus cells of GVBD and MI stage. These findings suggest that PLIN2 may have important roles in lipid metabolism during porcine oocyte maturation, whereas PLIN4 may play a major role in cumulus cells. PLIN3 can be hypothesised as a common lipid droplet-associated protein in both oocytes and cumulus cells. Further studies should be conducted to characterise the expression and distribution of PLIN1, PLIN2, PLIN3, and PLIN4 in porcine oocytes and cumulus cells. This study was supported by Ministry of Trade, Industry and Energy (#10048948), Korea IPET (#311011-05-4-SB010), Research Institute for Veterinary Science, and the BK21 plus program.