Dietary vitamin E deficiency does not affect global and specific DNA methylation patterns in rat liver

The aim of the present study was to determine the effects of a 6-month dietary vitamin E (VE) deficiency on DNA methylation and gene expression in rat liver. Two enzymes, 5-alpha-steroid reductase type 1 (SRD5A1) and the regulatory subunit of gamma-glutamylcysteinyl synthetase (GCLM), which are differentially expressed on the mRNA level, were analysed for promoter methylation in putative cytosine-phospho-guanine (CpG) island regions located at the 5' end using base-specific cleavage and matrix-assisted laser desorption ionisation time-of-flight MS. A twofold increase in the mRNA level of SRD5A1 gene and a twofold decrease in the mRNA level of GCLM gene in VE-deficient animals were not associated with different CpG methylation of the analysed promoter region. Furthermore, global DNA methylation was not significantly different in these two groups. Thus, the present results indicate that the VE-induced regulation of SRD5A1 and GCLM in rat liver is not directly mediated by changes in promoter DNA methylation.