Involvement of estrogen receptor variant ER-alpha36, not GPR30, in nongenomic estrogen signaling.
Accumulating evidence suggested that an orphan G protein-coupled receptor (GPR)30, mediates nongenomic responses to estrogen. The present study was performed to investigate the molecular mechanisms underlying GPR30 function. We found that knockdown of GPR30 expression in breast cancer SK-BR-3 cells down-regulated the expression levels of estrogen receptor (ER)-alpha36, a variant of ER-alpha. Introduction of a GPR30 expression vector into GPR30 nonexpressing cells induced endogenous ER-alpha36 expression, and cotransfection assay demonstrated that GPR30 activated the promoter activity of ER-alpha36 via an activator protein 1 binding site. Both 17beta-estradiol (E2) and G1, a compound reported to be a selective GPR30 agonist, increased the phosphorylation levels of the MAPK/ERK1/2 in SK-BR-3 cells, which could be blocked by an anti-ER-alpha36-specific antibody against its ligand-binding domain. G1 induced activities mediated by ER-alpha36, such as transcription activation activity of a VP16-ER-alpha36 fusion protein and activation of the MAPK/ERK1/2 in ER-alpha36-expressing cells. ER-alpha36-expressing cells, but not the nonexpressing cells, displayed high-affinity, specific E2 and G1 binding, and E2- and G1-induced intracellular Ca(2+) mobilization only in ER-alpha36 expressing cells. Taken together, our results demonstrated that previously reported activities of GPR30 in response to estrogen were through its ability to induce ER-alpha36 expression. The selective G protein-coupled receptor (GPR)30 agonist G1 actually interacts with ER-alpha36. Thus, the ER-alpha variant ER-alpha36, not GPR30, is involved in nongenomic estrogen signaling.
Kang
Lianguo
L
Department of Medical Microbiology and Immunology, Creighton University Medical School, Omaha, Nebraska 68178, USA.
Zhang
Xintian
X
Xie
Yan
Y
Tu
Yaping
Y
Wang
Dong
D
Liu
Zhenming
Z
Wang
Zhao-Yi
ZY
D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002460:Cell Line; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D004958:Estradiol / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000235:genetics / Q000528:radiation effects*; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011960:Receptors, Estrogen; D043562:Receptors, G-Protein-Coupled / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics
D047628:Estrogen Receptor alpha; C109584:GPER1 protein, human; D011960:Receptors, Estrogen; D043562:Receptors, G-Protein-Coupled; D004958:Estradiol; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases