title: Increased mitogenic responsiveness of Swiss 3T3 cells expressing constitutively active Gs alpha.
abstract: Mutational replacement of glutamine-227 with a leucine residue in the GTP-binding domain of the alpha subunit of GS (Q227L alpha S) reduces its ability to hydrolyse GTP and causes constitutive activation of the mutant protein. Expression in Swiss 3T3 fibroblasts of Q227L alpha S caused markedly increased basal adenylyl cyclase activity, enhanced intracellular cyclic AMP (cAMP) accumulation and increased mitogenic sensitivity in response to forskolin and the potent phosphodiesterase inhibitor Ro 20-1724. These results support a role for cAMP in the regulation of cell proliferation, and suggest that alterations in a G protein can directly modify the ability of cells to respond mitogenically to extracellular factors.
authors.affiliation: University of California, San Francisco 94143.
authors.forename: I
authors.initials: I
authors.lastname: Zachary
authors.forename: S B
authors.initials: SB
authors.lastname: Masters
authors.forename: H R
authors.initials: HR
authors.lastname: Bourne
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D002471:Cell Transformation, Neoplastic / Q000187:drug effects; D000242:Cyclic AMP / Q000378:metabolism; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics; D005973:Glutamine / Q000502:physiology; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000031:analogs & derivatives*; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000235:genetics / Q000378:metabolism; D006868:Hydrolysis; D015151:Immunoblotting; D007930:Leucine / Q000502:physiology; D008934:Mitogens / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009154:Mutation; D013873:Thionucleotides / Q000235:genetics / Q000378:metabolism; D014162:Transfection
chemical_list: D008934:Mitogens; D013873:Thionucleotides; C034882:guanosine 5'-O-(1-thiotriphosphate); D005973:Glutamine; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D000242:Cyclic AMP; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases; D007930:Leucine