title: v-src induces prostaglandin synthase 2 gene expression by activation of the c-Jun N-terminal kinase and the c-Jun transcription factor.
abstract: A consensus cyclic AMP response element (CRE) in the murine prostaglandin synthase-2 (PGS2) promoter is essential for pgs2 gene expression induced by pp60v-src, the v-src oncogene product. In this study, we investigate (i) the transcription factors active at the PGS2 "CRE site" in response to v-src activation and (ii) the signal transduction pathways by which pp60v-src activates these transcription factors. Transient transfection assays with pgs2 promoter/luciferase reporter chimeric genes suggest that c-Jun mediates v-src-induced pgs2 gene expression. Antibody supershift experiments demonstrate that c-Jun can participate in a complex with the pgs2 promoter CRE site. Moreover, in vitro immuno-complex assays demonstrate that pp60v-src expression strongly activates c-Jun N-terminal kinase (JNK1) enzyme activity. Serines 63 and 73, the sites of c-Jun phosphorylation by JNK, are essential for v-src-induced, pgs2 promoter-mediated luciferase expression. Cotransfection studies with plasmids expressing wild-type JNK, dominant-negative JNK, and dominant-negative MEKK-1 confirm that activation of the Ras/MEKK-1/JNK/c-Jun pathway is required for v-src-induced pgs2 gene expression. Overexpression of either wild-type ERK-1 or ERK-2 proteins also potentiate v-src-mediated luciferase expression driven by the pgs2 promoter, and expression of dominant-negative mutants of ERK-1, ERK-2, or Raf-1 attenuate this response. Thus, in response to v-src expression, a Ras/MEKK-1/JNK signal transduction pathway activating c-Jun and a Ras/Raf-1/ERK pathway converge to mediate pgs2 gene expression via the CRE site in the pgs2 promoter.
mesh_terms: D016475:3T3 Cells; D000818:Animals; D001665:Binding Sites; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D017362:Cyclic AMP Response Element-Binding Protein / Q000096:biosynthesis; D004789:Enzyme Activation; D015971:Gene Expression Regulation, Enzymologic; D016391:Genes, src; D007527:Isoenzymes / Q000096:biosynthesis; D048031:JNK Mitogen-Activated Protein Kinases; D008156:Luciferases / Q000096:biosynthesis; D051379:Mice; D020928:Mitogen-Activated Protein Kinases; D008954:Models, Biological; D015688:Oncogene Protein pp60(v-src) / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis*; D011494:Protein Kinases / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D014162:Transfection
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D007527:Isoenzymes; D016755:Proto-Oncogene Proteins c-jun; D011994:Recombinant Proteins; D008156:Luciferases; D011451:Prostaglandin-Endoperoxide Synthases; D011494:Protein Kinases; D015688:Oncogene Protein pp60(v-src); D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases