A consistent lack of DNA methylation at one or both of two GCGC (Hha I) restriction sites in the 5' region of the HLA-DRA gene has been previously documented by the use of methyl-sensitive restriction enzymes in human cells and tissues, irrespectively of their expression of DRα products. Evidence presently available, however, does not exclude that a lack of methylation in this region, although not sufficient, might be necessary for gene expression. In this report, we show that only one of the 5'-GCGC sites is protected, although less efficiently than in man, from CG→mCG modifications in tissues and cells of transgenic mice carrying an expressed single copy of the HLA-DRA gene/diploid genome. We demonstrate that the two 5'-GCGC sites of the HLA-DRA transgene are fully methylated in DRα- splenocytes (more than 80% T-lymphocytes), while one of them (the most 5' site) is not methylated in a fraction of DRα+ splenocytes (more than 95% B-lymphocytes). These results provide evidence that absence of DNA methylation in the 5' region is not necessary for, but might be associated with and possibly secondary to the expression of the DRA gene.
|Number of pages||8|
|Journal||European Journal of Biochemistry|
|Publication status||Published - 1993|
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