过表达PHD2在缺氧诱导黄体细胞VEGF表达中的作用

Vascular endothelial growth factor (VEGF)-dependent angiogenesis plays a crucial role in the corpus leteum formation and their functional maintenances in mammalian ovaries. We recently reported that activation of hypoxia-inducible factor (HIF)-1alpha signaling contributes to the regulation of VEGF expression in the letueal cells (LCs) in response to hypoxia and human chorionic gonadotropin. The present study was designed to test the hypothesis that HIF prolyl-dydoxylases (PHDs) express in LCs and overexpression of PHD2 attenuates the expression of VEGF induced by hypoxia in LCs. By real-time PCR and western blot analysis, we examined the expression of PHDs, confirmed the plasmid transfection and their expression, and also investigated the changes of HIF-1alpha and VEGF expression after treatment with hypoxia and PHD2 transgenes. PHD2 expression is significantly higher than the other two PHD isoforms, indicating its main roles in LCs. Moreover, a significant increase of VEGF mRNA was found after hypoxia treatment, while this increased VEGF mRNA was also attenuated by PHD2 overexpression in LCs. Further analysis also found that this hypoxia-induced increase of VEGF mRNA was consistent with the level of HIF-1alha protein, which is regulated by HIF prolyl-dydoxylase -mediated degradation. Taken together, our results indicated that PHD2 mainly expresses in LCs and hypoxia-induced VEGF expression can be attenuated by PHD2 overexpression through HIF-1alpha-mediated mechanism in LCs. This PHD2-mediated transcriptional activation may be one of the important mechanisms regulating VEGF expression in LCs during mammalian corpus leteum development. ?????