Silencing of the mouse H-rev107 gene encoding a class II tumor suppressor by CpG methylation.
H-rev107 is a tumor suppressor originally isolated in revertants of H-ras-transformed cell lines. The gene is ubiquitously expressed in normal tissues but down-regulated in primary carcinomas or in many cell lines derived from tumors, including WEHI 7.1 lymphoma cells. Here, we show that unlike in H-rev107-expressing cells or tissues the 5'-end of H-rev107 containing a CpG-rich region of 421 bp is highly methylated in WEHI 7.1 lymphoma cells, correlating with silencing of this gene. Repression of H-rev107 transcription in these cells could be relieved by chemically induced hypomethylation with 5-aza-dC. In addition, upon in vitro methylation, expression of the luciferase reporter gene driven by the H-rev107 promoter decreased by 80% in WEHI 7.1 and 293 cells. Furthermore, co-transfection of the methyl-CpG binding proteins, MeCP2 and MBD2, inhibited H-rev107 promoter activity up to 70% in SL2 cells when the promoter was methylated. By chromatin immunoprecipitation assays, we observed in vivo binding of MeCP2 and MBD2 to the 5'-end of H-rev107 in WEHI 7.1 cells, which was reduced to undetectable levels upon 5-aza-dC treatment, concluding that MeCP2 and MBD2 might be involved in silencing the methylated H-rev107 gene in lymphoma cells and probably certain tumors.
Roder
Karim
K
Department of Nutritional Sciences and Toxicology, University of California, Berkeley, CA 94720, USA.
Latasa
Maria-Jesus
MJ
Sul
Hei Sook
HS
D000818:Animals; D002460:Cell Line; D002868:Chromosomal Proteins, Non-Histone; D018899:CpG Islands / Q000502:physiology*; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000502:physiology; D020868:Gene Silencing; D016147:Genes, Tumor Suppressor; D051783:Methyl-CpG-Binding Protein 2; D051379:Mice; D054512:Phospholipases A2, Calcium-Independent; D011506:Proteins / Q000235:genetics*; D012097:Repressor Proteins; D014158:Transcription, Genetic
D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; C115368:MBD2 protein; C497393:Mecp2 protein, mouse; D051783:Methyl-CpG-Binding Protein 2; D011506:Proteins; D012097:Repressor Proteins; D054512:Phospholipases A2, Calcium-Independent; C490066:Plaat3 protein, mouse