Transcriptional regulation of @entity19 delta-opioid receptor gene by CpG methylation: involvement of @entity39985 and a methyl-CpG-binding protein, XXXX , in transcriptional repression of @entity19 delta-opioid receptor gene in Neuro2A cells.

@entity19 @entity39985 @entity61663 @entity15320 @entity238
Opioid receptors are expressed in a cell type-specific manner. Here we show that the @entity19 delta-opioid receptor ( @entity15320 ) gene is regulated by promoter region CpG methylation. The @entity15320 promoter containing a putative CpG island is highly methylated in Neuro2A cells, correlating with the repression of this gene in these cells. This is in contrast with the unmethylated state of the @entity15320 promoter in @entity19 cells, which express a high level of @entity15320 . Repression of @entity15320 transcription in Neuro2A cells could be partially relieved by chemically induced demethylation with 5-aza-2'-deoxycytidine. In addition, in vitro methylation of the luciferase reporter gene driven by the @entity15320 promoter resulted in an inhibition of transcription in @entity19 cells. Methyl-CpG-binding protein complex 1 (MeCP1) has been implicated in methylation-mediated transcriptional repression of several genes. Electrophoretic mobility shift assays showed that fully methylated, but not unmethylated, @entity15320 promoter fragment formed a MeCP1-like protein complex that contained @entity61663 ( @entity61663 ) and @entity39985 . Furthermore, the expression level of @entity39985 was decreased when Neuro2A cells were demethylated with 5-aza-2'-deoxycytidine, and increasing @entity39985 levels in Schneider's @entity238 line 2 cells led to the repression of @entity15320 promoter activity when the promoter was methylated. These results demonstrate that @entity39985 and @entity61663 are involved in the transcriptional repression of @entity15320 in Neuro2A cells through binding to the methylated CpG sites in the promoter region and may play a role in the cell type-specific expression of @entity15320 .
