G protein-coupled receptor 30 down-regulates cofactor expression and interferes with the transcriptional activity of glucocorticoid.
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 alpha 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.
Ylikomi
Timo
T
Department of Cell Biology, Medical School, 33014 University of Tampere, Finland.
Vienonen
Annika
A
Ahola
Tytti M
TM
D000818:Animals; D018931:Antineoplastic Agents, Hormonal / Q000494:pharmacology; D015153:Blotting, Western; D019556:COS Cells; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D003907:Dexamethasone / Q000494:pharmacology; D015536:Down-Regulation; D018014:Gene Transfer Techniques; D017930:Genes, Reporter; D005938:Glucocorticoids / Q000737:chemistry / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D008024:Ligands; D051379:Mice; D051958:Nuclear Receptor Coactivator 2; D012313:RNA / Q000737:chemistry; D011960:Receptors, Estrogen; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection
D018931:Antineoplastic Agents, Hormonal; C109584:GPER1 protein, human; D005938:Glucocorticoids; D008024:Ligands; C498001:NCOA2 protein, human; C498002:Ncoa2 protein, mouse; D051958:Nuclear Receptor Coactivator 2; D011960:Receptors, Estrogen; D043562:Receptors, G-Protein-Coupled; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D049452:Green Fluorescent Proteins; D012313:RNA; D003907:Dexamethasone