title: Stat3-mediated transformation of NIH-3T3 cells by the constitutively active Q205L Galphao protein.
abstract: Expression of Q205L Galphao (Galphao*), an alpha subunit of heterotrimeric guanine nucleotide-binding proteins (G proteins) that lacks guanosine triphosphatase (GTPase) activity in NIH-3T3 cells, results in transformation. Expression of Galphao* in NIH-3T3 cells activated signal transducer and activator of transcription 3 (Stat3) but not mitogen-activated protein (MAP) kinases 1 or 2. Coexpression of dominant negative Stat3 inhibited Galphao*-induced transformation of NIH-3T3 cells and activation of endogenous Stat3. Furthermore, Galphao* expression increased activity of the tyrosine kinase c-Src, and the Galphao*-induced activation of Stat3 was blocked by expression of Csk (carboxyl-terminal Src kinase), which inactivates c-Src. The results indicate that Stat3 can function as a downstream effector for Galphao* and mediate its biological effects.
authors.affiliation: Department of Pharmacology, Immunobiology Center, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029, USA. ramp01@doc.mssm.edu
authors.forename: P T
authors.initials: PT
authors.lastname: Ram
authors.forename: C M
authors.initials: CM
authors.lastname: Horvath
authors.forename: R
authors.initials: R
authors.lastname: Iyengar
mesh_terms: D016475:3T3 Cells; D000818:Animals; D000081247:CSK Tyrosine-Protein Kinase; D002461:Cell Line, Transformed; D002471:Cell Transformation, Neoplastic; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004789:Enzyme Activation; D044385:GTP-Binding Protein alpha Subunits; D017930:Genes, Reporter; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016501:Neurites / Q000502:physiology; D009473:Neuronal Plasticity; D009474:Neurons / Q000378:metabolism / Q000502:physiology; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D050796:STAT3 Transcription Factor; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism*; D014162:Transfection; D019061:src-Family Kinases
chemical_list: D004268:DNA-Binding Proteins; D044385:GTP-Binding Protein alpha Subunits; D050796:STAT3 Transcription Factor; C494087:Stat3 protein, mouse; D015534:Trans-Activators; C084618:olfactory G protein subunit alpha olf; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases; D020962:Heterotrimeric GTP-Binding Proteins