G protein-coupled receptor 30 localizes to the endoplasmic reticulum and is not activated by estradiol.
The classical estrogen receptor (ER) mediates genomic as well as rapid nongenomic estradiol responses. In case of genomic responses, the ER acts as a ligand-dependent transcription factor that regulates gene expression in estrogen target tissues. In contrast, nongenomic effects are initiated at the plasma membrane and lead to rapid activation of cytoplasmic signal transduction pathways. Recently, an orphan G protein-coupled receptor, GPR30, has been claimed to bind to and to signal in response to estradiol. GPR30 therefore might mediate some of the nongenomic estradiol effects. The present study was performed to clarify the controversy about the subcellular localization of GPR30 and to gain insight into the in vivo function of this receptor. In transiently transfected cells as well as cells endogenously expressing GPR30, we confirmed that the receptor localized to the endoplasmic reticulum. However, using radioactive estradiol, we observed only saturable, specific binding to the classical ER but not to GPR30. Estradiol stimulation of cells expressing GPR30 had no impact on intracellular cAMP or calcium levels. To elucidate the physiological role of GPR30, we performed in vivo experiments with estradiol and G1, a compound that has been claimed to act as selective GPR30 agonist. In two classical estrogen target organs, the uterus and the mammary gland, G1 did not show any estrogenic effect. Taken together, we draw the conclusion that GPR30 is still an orphan receptor.
Otto
Christiane
C
Therapeutic Research Group Women's Healthcare, Bayer Schering Pharma AG, Müllerstrasse 178, 13342 Berlin, Germany. christiane.otto@bayerhealthcare.com
Rohde-Schulz
Beate
B
Schwarz
Gilda
G
Fuchs
Iris
I
Klewer
Mario
M
Brittain
Dominic
D
Langer
Gernot
G
Bader
Benjamin
B
Prelle
Katja
K
Nubbemeyer
Reinhard
R
Fritzemeier
Karl-Heinrich
KH
D000818:Animals; D019556:COS Cells; D002118:Calcium / Q000378:metabolism; D002522:Chlorocebus aethiops; D000242:Cyclic AMP / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D004958:Estradiol / Q000378:metabolism* / Q000494:pharmacology; D005260:Female; D049452:Green Fluorescent Proteins / Q000235:genetics; D006801:Humans; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D051379:Mice; D010052:Ovariectomy; D011485:Protein Binding / Q000502:physiology; D011960:Receptors, Estrogen; D043562:Receptors, G-Protein-Coupled / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014162:Transfection; D014599:Uterus / Q000187:drug effects / Q000254:growth & development / Q000502:physiology
C109584:GPER1 protein, human; D011960:Receptors, Estrogen; D043562:Receptors, G-Protein-Coupled; D049452:Green Fluorescent Proteins; D004958:Estradiol; D000242:Cyclic AMP; D002118:Calcium