科研之友
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摘要
Objective. Growing evidence indicates that estrogen's non-genomic effects play important roles in cellular functions and backs up the hypothesis of the existence of a membrane estrogen receptor (mER) in a number of cell types, but little is known about the complementary effects between traditional genomic and novel non-genomic effects of estrogen. The aim of the present study was to explore the non-genomic activation of ERK1/2 mitogen-activated protein kinase (MAPK) by 17 beta-estradiol (E-2) through mER and its role in cell proliferation. Methods. On cultured bovine artery endothelial cells (BAECs) we used the [H-3]thymidine incorporation assay to evaluate the influence of E-2 on cell proliferation and fluorescence microscopy to show the presence of mER on the cell membrane. Scatchard analysis was performed to identify and characterize the mER on a purified membrane fraction of BAECs. Results. E-2 upregulated cyclin D1 protein expression and enhanced cell proliferation. Inhibition of the MAPK cascade with PD98059 or of G protein with pertussis toxin (PTX) completely abolished the above effects, while the estrogen receptor antagonist tamoxifen attenuated E-2-dependent upregulation of cyclin D1 and cell proliferation. Accordingly, E-2 rapidly led to ER1/ERK2 activation, which was prevented by tamoxifen or PTX and was entirely reproduced by membrane-impermeable estradiol-bovine serum albumin conjugate (E(2)coBSA). Immunofluorescent staining with E(2)CoBSA-fluorescein isothiocyanate resulted in a punctuate staining pattern of the plasma membrane and Scatchard analysis of the E-2-binding protein in a purified membrane fraction of BAECs showed that E-2 binds to the membrane fraction with a dissociation constant of 0.2394 nmol/l. Conclusion. Our findings showed that E-2 induces cell proliferation through upregulation of cyclin D I via non-genomic activation of the ERK1/ERK2 pathway mediated by mER and G protein.
- 出版日期2007-3
- 单位中山大学
