To investigate the methylation state of MHC class I sequences, genomic DNAs were digested in parallel with the restriction enzymes MspI and HpaII and subsequently analyzed by Southern blot hybridization. MspI and HpaII both recognize the sequence 5'-CCGG-3', but HpaII will not cut this sequence when the internal cytosine residue is methylated. When DNAs, isolated from the liver and spleen of WAG rats, were compared in this way, differences in the methylation patterns of these two organs were found. The data on the arrangement and methylation state of rat MHC class I sequences imply: haplotype-specific restriction fragment-length polymorphisms and methylation patterns; variation in MHC methylation pattern between organs; and a demethylated state of MHC sequences in tumors. These findings can be considered as a first step to a more complete direct examination of MHC methylation patterns in different tissues of aging rats. Such a study seems relevant in view of the suggestion that the function of DNA methylation in vertebrates is somehow related to the control of gene expression.
|Original language||English (US)|
|Number of pages||3|
|State||Published - Jan 1 1985|
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