Regulation of the DNA methyltransferase by the Ras-AP-1 signaling pathway.
Using deletion analysis and site-specific mutagenesis to map the 5' regulatory region of the DNA methyltransferase (MeTase) gene, we show that a 106-bp sequence (at -1744 to -1650) bearing three AP-1 sites is responsible for induction of DNA MeTase promoter activity. Using transient cotransfection chloramphenicol acetyl-transferase assays in P19 cells, we show that the DNA MeTase promoter is induced by c-Jun or Ha-Ras but not by a dominant negative mutant of Jun, delta 9. The activation of the DNA MeTase promoter by Jun is inhibited in a ligand dependent manner by the glucocorticoid receptor. Stable expression of Ha-Ras in P19 cells results in induction of transcription of the DNA MeTase mRNA as determined by nuclear run-on assays and the steady state levels of DNA MeTase mRNA as determined by an RNase protection assay. These experiments establish a potential molecular link between nodal cellular signaling pathways and the control of expression of the DNA MeTase gene. This provides us with a possible molecular explanation for the hyperactivation of DNA MeTase in many cancer cells and suggests that DNA MeTase is one possible downstream effector of Ras.
Rouleau
J
J
Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada.
MacLeod
A R
AR
Szyf
M
M
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D017931:DNA Primers; D003850:Deoxyribonuclease I; D011905:Genes, ras; D008780:Methyltransferases / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids; D011401:Promoter Regions, Genetic; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000378:metabolism; D015183:Restriction Mapping; D017384:Sequence Deletion; D015398:Signal Transduction; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection; D018631:ras Proteins / Q000378:metabolism*
D017931:DNA Primers; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D011965:Receptors, Glucocorticoid; D018808:Transcription Factor AP-1; D008780:Methyltransferases; D015500:Chloramphenicol O-Acetyltransferase; D003850:Deoxyribonuclease I; D018631:ras Proteins