Hypomethylation of the rat tyrosine hydroxylase gene correlates with its expression in several cell types.

Changes in the methylation patterns of genes have been implicated in controlling tissue-specific gene expression. Since the mechanism which causes the developmental appearance of tyrosine hydroxylase (TH) is unknown, we examined the extent of DNA methylation in the rat TH gene is PC12, F4 and liver cells, which differ in their expression of TH. Using methylation-sensitive restriction endonucleases, we found that hypomethylation of the TH gene correlated with its expression in these cells.