title: Non-classical testosterone signaling is mediated by a G-protein-coupled receptor interacting with Gnα11.
abstract: Testosterone is known to mediate its effects by two different mechanisms of action. In the so-called "classical" pathway testosterone binds to cytosolic androgen receptors (AR), which essentially function as ligand-activated transcription factors. Once activated, these receptors bind to DNA and activate the expression of target genes. In the "non-classical" pathway, the steroid hormone binds to receptors associated with the plasma membrane and induces signaling cascades mediated through activation of Erk1/2. The precise nature of the membrane-associated AR, however, remains controversial. Although some assume that the membrane and cytosolic AR are identical, others propose that the AR of the membrane is a G-protein-coupled receptor (GPCR). To evaluate these two possibilities we first searched for testosterone-induced signaling cascades in the spermatogenic cell line GC-2. Testosterone was found to cause phosphorylation (activation) of Erk1/2, CREB, and ATF-1, consistent with its non-classical mechanism of action. Silencing of AR expression by means of siRNA did not influence testosterone-induced activation of Erk1/2, CREB, or ATF-1, indicating that this pathway is not activated by the classical cytosolic/nuclear AR. In contrast, when the expression of the G-protein Gnα11 is suppressed, the activation of these signaling molecules is abolished, suggesting that these responses are elicited through a membrane-bound GPCR. The results presented here and the identification of the testosterone-specific GPCR in future investigations will help to reveal and characterize new testosterone-mediated mechanisms associated not only with fertility and reproduction but perhaps also with other physiological processes.
authors.affiliation: Institut für Veterinär-Physiologie und -Biochemie, Fachbereich Veterinärmedizin, Justus-Liebig-Universität Giessen, Germany.
authors.forename: Mazen
authors.initials: M
authors.lastname: Shihan
authors.affiliation: Institut für Veterinär-Physiologie und -Biochemie, Fachbereich Veterinärmedizin, Justus-Liebig-Universität Giessen, Germany.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Bulldan
authors.affiliation: Institut für Veterinär-Physiologie und -Biochemie, Fachbereich Veterinärmedizin, Justus-Liebig-Universität Giessen, Germany. Electronic address: Georgios.Scheiner-Bobis@vetmed.uni-giessen.de.
authors.forename: Georgios
authors.initials: G
authors.lastname: Scheiner-Bobis
mesh_terms: D051697:Activating Transcription Factor 1 / Q000235:genetics / Q000378:metabolism; D000728:Androgens / Q000494:pharmacology*; D000818:Animals; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D011944:Receptors, Androgen / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013090:Spermatocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D013739:Testosterone / Q000494:pharmacology*
chemical_list: D051697:Activating Transcription Factor 1; D000728:Androgens; C497100:Atf1 protein, mouse; C492004:Creb1 protein, mouse; D017362:Cyclic AMP Response Element-Binding Protein; D012333:RNA, Messenger; D011944:Receptors, Androgen; D043562:Receptors, G-Protein-Coupled; D013739:Testosterone; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D043802:GTP-Binding Protein alpha Subunits, Gq-G11
keywords: ATF-1; Androgen receptor; CREB; Erk1/2; GPCR; Gnα11; Signaling; Spermatogenic cell; Testosterone