tailieunhanh - Báo cáo khoa học: G protein-coupled receptor 30 down-regulates cofactor expression and interferes with the transcriptional activity of glucocorticoid

Gprotein-coupled receptor 30 (GPR30) has previously been described tobe important in steroid-mediatedgrowthand to inhibit cell proliferation. Here we investigated whether the effect of GPR30 on cell growth is dependent on steroid hormone receptors. We stably introduced GPR30 in immortalizednormalmammaryepithelial (HME) cellsusing retroviruses for gene delivery. GPR30 inhibited the growth and proliferation of the cells. They expressed glucocorticoid receptor, but not estrogen or progesterone receptor | Eur. J. Biochem. 271 4159-4168 2004 FEBS 2004 doi G protein-coupled receptor 30 down-regulates cofactor expression and interferes with the transcriptional activity of glucocorticoid Timo Ylikomi1 2 Annika Vienonen1 and Tytti M. Ahola1 1Department of Cell Biology Medical School 33014 University of Tampere Finland department of Clinical Chemistry Tampere University Hospital Tampere Finland G protein-coupled receptor 30 GPR30 has previously been described to be important in steroid-mediated growth and to inhibit cell proliferation. Here we investigated whether the effect of GPR30 on cell growth is dependent on steroid hormone receptors. We stably introduced GPR30 in immortalized normal mammary epithelial HME cells using retroviruses for gene delivery. GPR30 inhibited the growth and proliferation of the cells. They expressed glucocorticoid receptor but not estrogen or progesterone receptor. GPR30 down-regulated the expression of cofactor transcription intermediary factor 2 TIF2 analyzed using quantitative RT-PCR analysis and also diminished the expression of TIF2 at protein level analyzed by Western blotting using nuclear extracts from mammary epithelial cells. When HME cells were transiently transfected with the glucocorticoid response element MMTV-luc reporter plasmid stable expression of GPR30 resulted in the abolition of ligand-induced transactivation of the promoter. In COS cells transient transfection of GPR30 with glucocorticoid receptor a resulted in an abrogation of the MMTV-luc and GRE-luc reporter activities induced by dexamethasone. The results suggest a novel mechanism by which membrane-initiated signaling interferes with steroid signaling. Keywords cofactor glucocorticoid GPR proliferation transcription. Glucocorticoids play a vital role throughout physiology. The physiological response and sensitivity to glucocorticoids varies among species individuals and cell types and during the cell cycle 1 2 . Moreover several .