The cellular response to induction of the p21 c-Ha-ras oncoprotein includes stimulation of jun gene expression.
We have studied the effects of c-Ha-ras oncogene in mouse NIH 3T3 fibroblasts by DNA transfection and analysis of gene expression at the mRNA and protein level in a heat- and heavy metal-inducible model system. The human c-Ha-ras proto-oncogene and oncogene were cloned under the hsp70 heat-shock promoter. Clonal lines of cells with negligible basal expression of the hsp-c-Ha-ras oncogene construct were chosen on the basis of the inducibility of p21c-Ha-ras protein and several transformation parameters. We demonstrate that the expression of ornithine decarboxylase (ODC) mRNA is enhanced approximately 4-6 h after the induction of the p21c-Ha-ras oncoprotein. This increase was reversible upon cessation of c-Ha-ras mRNA and protein synthesis, while constitutively elevated ODC was characteristic for stably c-Ha-ras-transformed cells. The high-level expression of ODC in ras-transformed cells was insensitive to tumour promoter stimulation. A similar mRNA induction by c-Ha-rasVal-12 was also observed for two other serum- and tumour promoter-regulated genes associated with the transformed phenotype: transin (stromelysin) and the glucose transporter. This prompted us to examine also potential changes in the expression of the serum- and tumour promoter-induced transcription factor genes junB and c-jun after induction of the hsp--c-Ha-ras construct. The junB mRNA was enhanced approximately 10-fold and the c-jun oncogene mRNA to a lesser degree in the hsp--c-Ha-ras-transfected cells after zinc activation of the hsp70 promoter. These effects were not seen in similarly treated control cells.(ABSTRACT TRUNCATED AT 250 WORDS)
Sistonen
L
L
Department of Virology, University of Helsinki, Finland.
Hölttä
E
E
Mäkelä
T P
TP
Keski-Oja
J
J
Alitalo
K
K
D000818:Animals; D002461:Cell Line, Transformed; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D005786:Gene Expression Regulation; D006360:Heat-Shock Proteins / Q000235:genetics; D006801:Humans; D019278:Matrix Metalloproteinase 3; D008666:Metalloendopeptidases / Q000235:genetics; D051379:Mice; D009004:Monosaccharide Transport Proteins / Q000235:genetics; D009955:Ornithine Decarboxylase / Q000235:genetics; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics*; D016755:Proto-Oncogene Proteins c-jun; D016283:Proto-Oncogene Proteins p21(ras); D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics*
D004268:DNA-Binding Proteins; D006360:Heat-Shock Proteins; C000715470:MAS1 protein, human; D009004:Monosaccharide Transport Proteins; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D014157:Transcription Factors; D008666:Metalloendopeptidases; D019278:Matrix Metalloproteinase 3; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras); D009955:Ornithine Decarboxylase; D013755:Tetradecanoylphorbol Acetate