title: Testosterone stimulates intracellular calcium release and mitogen-activated protein kinases via a G protein-coupled receptor in skeletal muscle cells.
abstract: Involvement of intracellular Ca(2+) and ERK1/2 phosphorylation in the fast nongenomic effects of androgens in myotubes was investigated. Testosterone or nandrolone produced fast (<1 min) and transient increases in intracellular Ca(2+) with an oscillatory pattern. Calcium signals were slightly reduced in Ca(2+)-free medium, but lack of oscillations was evident. Signals were blocked by U-73122 and xestospongin B, inhibitors of inositol 1,4,5-trisphosphate (IP(3)) pathway. Furthermore, IP(3) increased transiently 2- to 3-fold 45 sec after hormone addition. Cyproterone neither affected the fast Ca(2+) signal nor the increase in IP(3). Calcium increases could also be induced by the impermeant testosterone conjugated to BSA, and the effect of testosterone was abolished in cells incubated with guanosine 5'-O-(2-thiodiphosphate) or pertussis toxin. Stimulation of myotubes with testosterone, nandrolone, or testosterone conjugated to BSA increased immunodetectable phosphorylation of ERK1/2 within 5 min, and this effect was not inhibited by cyproterone. Phosphorylation was blocked by the use of 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethylester, U-73122, and xestospongin B as well as by dominant negative Ras, MAPK kinase (MEK), or the MEK inhibitor PD-98059. In addition, guanosine 5'-O-(2-thiodiphosphate) or pertussis toxin blocked ERK1/2 phosphorylation. These results are consistent with a fast effect of testosterone, involving a G protein-linked receptor at the plasma membrane, IP(3)-mediated Ca(2+) signal, and the Ras/MEK/ERK pathway in muscle cells.
authors.affiliation: Centro de Estudios Moleculares de la Célula and Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Casilla 70005, Santiago 6530499, Chile.
authors.forename: Manuel
authors.initials: M
authors.lastname: Estrada
authors.forename: Alejandra
authors.initials: A
authors.lastname: Espinosa
authors.forename: Marioly
authors.initials: M
authors.lastname: Müller
authors.forename: Enrique
authors.initials: E
authors.lastname: Jaimovich
mesh_terms: D059002:Androgen Receptor Antagonists; D000728:Androgens / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000502:physiology*; D002614:Chelating Agents / Q000494:pharmacology; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics; D017373:Cyproterone Acetate / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000502:physiology*; D015870:Gene Expression / Q000187:drug effects; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D053496:Inositol 1,4,5-Trisphosphate Receptors; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D009277:Nandrolone / Q000494:pharmacology; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000037:antagonists & inhibitors / Q000502:physiology*; D013739:Testosterone / Q000494:pharmacology*; D014162:Transfection; D018631:ras Proteins / Q000378:metabolism
chemical_list: D059002:Androgen Receptor Antagonists; D000728:Androgens; D015220:Calcium Channels; D002614:Chelating Agents; D017362:Cyclic AMP Response Element-Binding Protein; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D013739:Testosterone; D017373:Cyproterone Acetate; D009277:Nandrolone; D015544:Inositol 1,4,5-Trisphosphate; D017346:Protein Serine-Threonine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D019204:GTP-Binding Proteins; D018631:ras Proteins; D002118:Calcium