Adiponectin is one of the most abundant fat-derived hormones involved in a multitude of metabolism pathways. It acts as an anti-diabetic and anti-atherogenic adipokine. Adiponectin mediates its actions through mainly two receptors, AdipoR1 and AdipoR2. It has been postulated that although AdipoR1 and AdipoR2 consist of seven transmembrane helices, they are distinct from other G protein-coupled receptors. A role of adiponectin in ovarian physiology has been recently suggested. This hormone and its receptors have been identified in different ovarian compartments in various species. Thus, the aim of this study was to determine the effect of an inactivation of AdipoR1 and AdipoR2 mRNA by RNA interference (RNAi) on a human granulosa cell line (KGN cell line). We first observed in a few days the death of R1 cells that express AdipoR1 RNAi. These data were not shown with a control RNAi (scramble RNAi). On the opposite, R2 cells that express AdipoR2 RNAi are viable. Although AdipoR2 expression (mRNA and protein) was strongly reduced in R2 cells, no difference was seen in term of cell proliferation or viability (± IGF-1 (5×10−8 M) or adiponectin (10 (g/ml)) if compared with KGN cells. Progesterone (P4) and Estradiol (E2) secretions were increased in response to IGF-1 or FSH (5×10-8 M) compared to basal state in KGN and R2 cells. However, these levels of steroid hormones in R2 cells were lower in response to FSH and FSH-IGF-1 (P<0.0001) for P4 and E2 and in response to IGF-1 for E2 (P=0.0059). So, in KGN cells, AdipoR2 receptor could modulate steroïdogenesis stimulated by FSH or IGF-1. Lastly, we observed that human adiponectin induced quick and transient activation of the MAPK ERK1/2 pathway in KGN but not R2 cells. Taken together, these data suggest that, in human granulosa cells, AdipoR1 could act on cellular survival and AdipoR2 could regulate steroidogenesis.
25 - 29 Apr 2009
European Society of Endocrinology