Involvement of activating ERK1/2 through G protein coupled receptor 30 and estrogen receptor α/β in low doses of bisphenol A promoting growth of Sertoli TM4 cells

Abstract

Sertoli cells play a pivotal role in supporting proliferation of germ cells and differentiation during spermatogenesis in mammals. Nanomolar concentrations of Bisphenol A (BPA) can significantly stimulate the proliferation of mouse immature Sertoli (TM4) cells. However, mechanisms by which BPA caused these effects were still unclear. In the present study, an inverse U-shaped curve was observed when treating TM4 cells with increasing doses of BPA: 1 to 10nM BPA significantly stimulated the proliferation of TM4 cells and increased the proportion of cells in S phase; >1μM BPA caused lesser proliferation of cells. Exposure of TM4 cells to G15 or ICI 182,780, which are specific antagonists of GPR30 and estrogen receptor α/β (ERα/β), respectively, abolished BPA-induced proliferation of cells, which suggests that both GPR30 and ERα/β were involved in the observed effects of BPA. Furthermore, exposure to BPA caused rapid (5min) activation of ERK1/2 via both GPR30 and ERα/β. Blocking the GPR30/EGFR signal transduction pathway by antagonists suppressed both phosphorylation of ERK and BPA-induced cell proliferation. BPA up-regulated mRNA and protein expression of GPR30 in a concentration-dependent manner. In summary, the results reported here indicated that activating ERK1/2 through GPR30 and ERα/β is involved in low doses of BPA that promoted growth of Sertoli TM4 cells. The GPR30/EGFR/ERK signal is the downstream transduction pathway in BPA-induced proliferation of TM4 Sertoli cells.