title: ras-induced c-fos expression and proliferation in living rat fibroblasts involves C-kinase activation and the serum response element pathway.
abstract: We have examined the early events involved in the proliferative activation of quiescent rat embryo fibroblasts by microinjection of oncogenic ras protein. Cells injected with ras show a transient expression of c-fos after 30-60 min visualized by immunofluorescence in the nucleus. This c-fos expression can be specifically suppressed by coinjection of a double-stranded oligonucleotide which corresponds to the serum response element (SRE) present in the c-fos promoter, implying that ras utilizes a pathway which activates the binding of serum response factor(s) (SRF) to SRE to induce c-fos transcription. Inhibition of this pathway also abolished ras-induced DNA synthesis indicating that the proliferative induction by ras requires expression of SRE-regulated genes. Both c-fos induction and DNA synthesis were prevented when ras oncoprotein was injected into quiescent cells together with either antibodies against calcium phospholipid-dependent protein kinase (C-kinase) or a synthetic peptide that specifically inhibits C-kinase. These data demonstrate the involvement of both functional C-kinase and the SRE pathway in the activation of quiescent cells by ras and suggest a potential relationship in their mechanism of action.
authors.affiliation: CRBM, CNRS/INSERM, Montpellier, France.
authors.forename: C
authors.initials: C
authors.lastname: Gauthier-Rouvière
authors.forename: A
authors.initials: A
authors.lastname: Fernandez
authors.forename: N J
authors.initials: NJ
authors.lastname: Lamb
mesh_terms: D000818:Animals; D002460:Cell Line; D004247:DNA / Q000096:biosynthesis; D004789:Enzyme Activation / Q000187:drug effects; D005347:Fibroblasts / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D015870:Gene Expression / Q000187:drug effects*; D008845:Microinjections; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011089:Polydeoxyribonucleotides / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000494:pharmacology*; D016760:Proto-Oncogene Proteins c-fos; D016283:Proto-Oncogene Proteins p21(ras); D051381:Rats; D026362:Serum Response Factor
chemical_list: D009687:Nuclear Proteins; D010750:Phosphoproteins; D011089:Polydeoxyribonucleotides; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D026362:Serum Response Factor; D004247:DNA; D011493:Protein Kinase C; D016283:Proto-Oncogene Proteins p21(ras)