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The functional importance of DNA methylation, which is a special case of epigenetic variation, is meant for regulation of many biological processes, ranged from tissue specific gene expression to remodeling of chromatin structure. Disorders of the DNA methylation can cause changes in the cell's phenotype, providing a significant impact on the development of pathology. Both exogenous and endogenous factors are able to cause disruption of DNA methylation, while epigenetic changes usually precede the emergence of clinical and morphological symptoms of pathological process development, consequently the parameters of DNA methylation can be used as sensitive biomarkers to detect adverse effects on the organism. The purpose of the study was to identify genes of the liver, the methylation profile of which changes under the influence of hepatotoxicants of different nature. The experiment was carried out on 60 male Wistar rats with initial body weight (b.w.) 83.3±1.5 g. Animals were randomly divided into 6 groups - 1 control and 5 test groups, with 10 rats in each group. During the first two weeks of the experiment the rats of the 1-5th test groups were administered to aflatoxin B1 (200 Mg/kg b.w.), cadmium chloride 2,5-hydrate (2 mg/kg), monosodium glutamate (1000 mg/kg), epigallocatechin gallate (EGCG) (1000 mg/kg), paracetamol (150 mg/kg), accordingly. Methylation of the liver genes in rats was determined by using high-performance methods, based on bisulfite sequencing of reduced representation. For each sample from 12 to 30 million pairs of reads were received, genes which demonstrated significant changes in methylation when exposed to toxic factors were identified: aflatoxin B1 caused changes in the methylation of 57 genes; cadmium - 54 genes; monosodium glutamate - 39 genes; EGCG -198 genes; paracetamol - 167 genes. The comparison of genes with altered methylation in the experimental groups revealed that none of the genes repeatedly occurred under the influence of each toxicant out of five, the highest number of repeats accounted 3. As a result of the present analysis 7 genes have been selected: methylation change in Fan1 gene was observed when exposed to cadmium, monosodium glutamate, EGCG; gene Lppr2 - under the influence of aflatoxin B1, EGCG, paracetamol; gene Mlh3 - under the influence of aflatoxin B1, cadmium, paracetamol; Sirt7 gene - under the influence of cadmium, EGCG, paracetamol; gene Fbxo15 - when exposed to cadmium, monosodium glutamate, paracetamol; gene E2f1 - when exposed to cadmium, EGCG, paracetamol; gene Mrps16 - when exposed to cadmium, EGCG, paracetamol. On the basis of the received data the project of the panel of genes-biomarkers of toxic effect, including genes Fan1, Lppr2, Mlh3, Sirt7, Fbxo15, E2f1, Mrps16 has been formed. |
