Pigment epithelium-derived factor expression and role in follicular development

Research question: What is the involvement of pigment epithelium -derived factor (PEDF), expressed in granulosa cells, in folliculogenesis? Design: mRNA expression of PEDF and other key factors [ Cyp19 , anti-Mu <euro> llerian hormone receptor ( AMHR ) and vascular endothelial growth factor ( VEGF )] in mice follicles was examined in order to typify the expression of PEDF in growing follicles and in human primary granulosa cells (hpGC), and to follow the interplay between PEDF and the other main players in folliculogenesis: FSH and AMH. Results: mRNA expression of PEDF increased through folliculogenesis, although the pattern differed from that of the other examined genes, affecting the follicular angiogenic and oxidative balance. In hpGC, prolonged exposure to FSH stimulated the up -regulation of PEDF mRNA. Furthermore, a negative correlation between AMH and PEDF was observed: AMH stimulation reduced the expression of PEDF mRNA and PEDF stimulation reduced the expression of AMHR mRNA. Conclusions: Folliculogenesis, an intricate process that requires close dialogue between the oocyte and its supporting granulosa cells, is mediated by various endocrine and paracrine factors. The current fi ndings suggest that PEDF, expressed in granulosa cells, is a pro-folliculogenesis player that interacts with FSH and AMH in the process of follicular growth. However, the mechanism of this process is yet to be determined.