Epigenetic mechanisms in the 5-lipoxygenase gene regulation

We studied the epigenetic regulation of the 5-lipoxygenase gene and the general epigenetic mechanisms in various mammalian normal tissues and in cultured cell lines.; We used pharmacological tools acting at epigenetic mechanisms. 5-lipoxygenase mRNA levels were assayed with reverse transcription-polymerase chain reaction. Histone acetylation levels were determined by immunochemical staining and by the chromatin immunoprecipitation assay. DNA methylation states were examined by the bisulfite genomic sequencing method and by the enzymatic regional methylase assay that we developed specifically for the purpose of this project.; The results demonstrated that the silenced 5-lipoxygenase gene expression in tumor cell lines is related with DNA hypermethylation of the 5-lipoxygenase promoter region and hyperacetylation of the histone H3 that is associated with the promoter of this gene. In normal tissues the 5-lipoxygenase promoter CpG island was found to be always hypomethylated and its DNA methylation state was not related with tissue-specific and development-specific regulation of the 5-lipoxygenase gene expression. However, the 5-lipoxygenase mRNA levels were modified by pharmacological agents acting at epigenetic mechanisms. The analyses on the multiple CpG islands in the human 5-lipoxygenase gene suggested new regulatory factors and mechanism.; We found the existence of cytosine methylation in CpWpG sequence. It is also demonstrated that histone modification may alter DNA methylation states. This process is probably determined by the specific intercellular epigenetic machinery. In neurons, the components of this machinery may differ from those in proliferating cells.