Regulation of steroidogenic function of mouse Leydig cells : G-coupled membrane estrogen receptor and peroxisome proliferator-activated receptor partnership

We tested whether G-coupled membrane estrogen receptor (GPER) and peroxisome proliferator activated receptor (PPAR) partnership exists and whether this interaction regulates mouse Leydig cell function. Mature and aged mice were treated with the antagonist of GPER (G-15; 50 \mu g/kg b.w). Leydig cells (MA-10) were treated with G-15 (10 nM) alone or in combination with peroxisome proliferator-activated receptor \alpha or \gamma antagonists, respectively (PPAR\alpha, 10 \mu M; PPAR\gamma, 10 \mu M). GPER blockage affected testis steroidogenic status via changes in lutropin and cholesterol levels as well as protein expression alterations of the lutropin receptor, acute steroidogenesis activating protein, translocator protein, and protein kinase A in mouse Leydig cells both in vivo and in vitro. Inactivation of both GPER and PPAR in vitro revealed expressional modulation of other steroidogenesis-controlling molecules acting on various steps of lipid homeostasis e.g. cytochrome P450scc, perilipin, hormone sensitive lipase, and 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase. Concomitantly, microscopic analysis of cells treated with antagonists showed changes in morphology, migration competences and cytoskeleton structure. In the above processes, the action of GPER and PPAR\alpha was regulated through the PI3K/Akt pathway, while PPAR\gamma was mediated by the Ras/Raf pathway. In addition, GPER and PPARs specifically controlled individual signaling proteins. For the first time, we report here the importance of GPERPPAR\alpha and -PPAR\gamma 'neopartnership' in maintenance of Leydig cell morpho-functional status