Evaluation of Epigenetic Age Based on DNA Methylation Analysis of Several CpG Sites in Ukrainian Population

Epigenetic clocks are the models, which use CpG methylation levels for the age prediction of an organism. Although there were several epigenetic clocks developed there is a demand for development and evaluation of the relatively accurate and sensitive epigenetic clocks that can be used for routine research purposes. In this study, we evaluated two epigenetic clock models based on the 4 CpG sites and 2 CpG sites in the human genome using the pyrosequencing method for their methylation level estimation. The study sample included 153 people from the Ukrainian population with the age from 0 to 101. Both models showed a high correlation with the chronological age in our study sample (R² = 0.85 for the 2 CpG model and R² = 0.92 for the 4 CpG model). We also estimated the accuracy metrics of the age prediction in our study sample. For the age group from 18 to 80 MAD was 5.1 years for the 2 CpG model and 4.1 years for the 4 CpG model. In this regard, we can conclude, that the models evaluated in the study have good age predictive accuracy, and can be used for the epigenetic age evaluation due to the relative simplicity and time-effectiveness.

[S-nitrosoglutathione induced nitrosative stress in yeast: modifying role of catalases]

Possible role of catalases in modification of yeast Saccharomyces cerevisiae response to nitrosative stress was studied in the work. Yeast cell of a wild strain and catalase-defective strains were treated with nitric oxide donor S-nitrosoglutathione, then the cell survival rate, and the levels of protein carbonyls and oxidized glutathione were measured. It was shown that S-nitrosoglutathione decreased cells viability of wild and catalase-defective strains. Unexpected, yeast cells defective by both catalases survived successfully as compared with the cells of the wild strain. The intensity of stress was evaluated by measures of oxidative protein modifications and glutathione oxidation. Treatment with S-nitrosoglutathione did not affect the level of protein carbonyls and was lower by about 14 i 22 % in the cells of double mutant strains after treatments with S-nitrosoglutathione in concentrations of 10 and 20 mM. S-nitrosoglutathione induced a strong increase of the level of oxidized glutathione in yeast cells of the wild strain. This stress slightly increased the level of oxidized glutathione in the yeast cells defective by peroxisomal or both catalases. It is interesting, that an increase of oxidized glutathione level was not observed in the yeast cells defective by cytosolic catalase. The obtained results prove that catalases can modify yeast cell response to the nitrosative stress.