In-vitro study of gonadotrophin signaling pathways in human granulosa cells in relation to progesterone receptor expression.

In humans, data on gonadotrophin-activated (LH, HCG and FSH) progesterone receptor expression and signalling pathways involved in matrix metalloproteinases (MMPs) expression presumably linked to the follicle rupture, are limited. Our hypothesis is LH, HCG and FSH increase progesterone receptor expression in granulosa cells through different signalling pathways, leading to an increased expression of ADAMTS-1 and MMP3/10, which may mediate follicular rupture through the transcription factor, HIF1A. Human granulosa cells were isolated from follicular aspirates obtained from 22 healthy women participating in our IVF programme for male-factor infertility. Progesterone receptor and HIF1A expression was assessed by immunofluorescence, and PKA-PKC-PI3K- ERK1/2, ADAMTS-1 and MMP3/10 expression by Western blot in pre-ovulatory and in cultured granulosa cells. Results show that HCG, LH and FSH regulate progesterone receptor expression and activate PKA, PKC, PI3K and ERK1/2 signalling pathways in granulosa cells but progesterone receptor expression is only mediated by PKA, PKC and ERK pathways. HCG, FSH and LH regulated MMPs expression through progesterone receptors. Moreover, HCG-progesterone-receptor-dependent HIF1A expression stimulated MMP3/10 expression but not that of ADAMTS-1. These results suggest differential downstream progesterone receptor signalling, as progesterone receptor regulates MMP3/10 expression via HIF1A, which is not involved in ADAMTS-1 expression.