title: SRF-dependent gene expression is required for PI3-kinase-regulated cell proliferation.
abstract: Recent evidence indicates that phosphatidylinositol 3-kinase (PI3K) is a central regulator of mitosis, apoptosis and oncogenesis. Nevertheless, the mechanisms by which PI3K regulates proliferation are not well characterized. Mitogens stimulate entry into the cell cycle by inducing the expression of immediate early genes (IEGs) that in turn trigger the expression of G(1) cyclins. Here we describe a novel PI3K- regulated transcriptional cascade that is critical for mitogen regulation of the IEG, c-fos. We show that PI3K activates gene expression by transactivating SRF-dependent transcription independently of the previously described Rho and ETS TCF pathways. PI3K-stimulated cell cycle progression requires transactivation of SRF and expression of dominant- negative PI3K blocks mitogen-stimulated cell cycle progression. Furthermore, dominant-interfering SRF mutants attenuate mitogen-stimulated cell cycle progression, but are without effect on MEK-stimulated cell cycle entry. Moreover, expression of constitutively active SRF is sufficient for cell cycle entry. Thus, we delineate a novel SRF-dependent mitogenic cascade that is critical for PI3K- and growth factor-mediated cell cycle progression.
authors.affiliation: Department of Pharmacology, School of Medicine, University of Washington, Seattle, 98195, USA.
authors.forename: S
authors.initials: S
authors.lastname: Poser
authors.forename: S
authors.initials: S
authors.lastname: Impey
authors.forename: K
authors.initials: K
authors.lastname: Trinh
authors.forename: Z
authors.initials: Z
authors.lastname: Xia
authors.forename: D R
authors.initials: DR
authors.lastname: Storm
mesh_terms: D016475:3T3 Cells; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D002453:Cell Cycle; D002455:Cell Division; D002469:Cell Separation; D002867:Chromones / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D019204:GTP-Binding Proteins / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D005799:Genes, Dominant; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D007763:Lac Operon; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D020928:Mitogen-Activated Protein Kinases; D009025:Morpholines / Q000494:pharmacology; D016297:Mutagenesis, Site-Directed; D020932:Nerve Growth Factor / Q000494:pharmacology; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism*; D016716:PC12 Cells; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics* / Q000378:metabolism*; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D026362:Serum Response Factor; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D000077191:Wortmannin; D048051:p38 Mitogen-Activated Protein Kinases; D020741:rho GTP-Binding Proteins / Q000378:metabolism
chemical_list: D000730:Androstadienes; D002867:Chromones; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D009025:Morpholines; D009687:Nuclear Proteins; D016760:Proto-Oncogene Proteins c-fos; D026362:Serum Response Factor; D014157:Transcription Factors; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D020932:Nerve Growth Factor; D008156:Luciferases; D019869:Phosphatidylinositol 3-Kinases; D020797:Receptor, Platelet-Derived Growth Factor beta; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D019204:GTP-Binding Proteins; D020741:rho GTP-Binding Proteins; D000077191:Wortmannin