Mirosława Z. Barciszewska

BACKGROUND: Hypertension is a common disease of the cardiovascular system and one of the main causes of mortality in the world. Its etiopathogenesis and molecular mechanisms are unknown. Epigenetic changes may play a role in its development. Therefore the level of 5-methylcytosine (5mC), a well-known epigenetic marker, was analyzed in DNA from the blood of essential hypertension patients. MATERIAL/METHODS: TLC chromatographic analysis of the DNA nucleotide composition was used to determine 5mC levels in blood DNA samples from 60 patients suffering from essential hypertension (30 with stage 1 and 30 with stage 2 hypertension) and 30 control subjects. RESULTS: The mean levels of 5mC were 1.80 + or - 0.69 in the healthy subjects, 1.14 + or - 0.48 in all the patients with essential hypertension, 1.29 + or - 0.50 in those with stage 1, and 0.99 + or - 0.42 in those with stage 2 of hypertension. Statistically significant differences in 5mC amount in DNA were observed between the control group and the whole patient group, the control group and each subgroup of patients, and the groups of patients with stage 1 and stage 2 of hypertension. The level of 5mC in the DNA of the essential hypertension patients was independent of clinical and biochemical factors. CONCLUSIONS: The level of 5mC in the DNA of patients suffering from essential hypertension is lower than in healthy people and depends of the progression of hypertension.

Recent analyses of the human genome and available data about the other higher eukaryotic genomes have revealed that, in contrast to Eubacteria and Archaea, only a small fraction of the genetic material (ca 1.5%) codes for proteins. Most of genomic DNA and its RNA transcripts are involved in regulation of gene expression, which can be exerted at either the transcriptional level, controlling whether a gene is transcribed and to what extent, or at the post-translational level, regulating the fate of the transcribed RNA molecules, including their stability, efficiency of their translation and subcellular localization. Noncoding RNA genes produce functional RNA molecules (ncRNAs) rather than encoding proteins. These stable RNAs act by multiple mechanisms such as RNA-RNA base pairing, RNA-protein interactions and intrinsic RNA activity, as well as regulate diverse cellular functions, including RNA processing, mRNA stability, translation, protein stability and secretion. Non-protein-coding RNAs are known to play significant roles. Along with transfer RNAs, ribosomal RNAs and mRNAs, ncRNAs contribute to gene splicing, nucleotide modification, protein transport and regulation of gene expression.