Tag Archives: lymphoblasts
Relationship between CpG and non-CpG DNA methylation in human lymphocytes assessed with comet assay
M. Chopei, A. Piven, K. Afanasieva, A. Sivolob*
ESC “Institute of Biology and Medicine”,
Taras Shevchenko National University of Kyiv, Ukraine;
*e-mail: sivolob@knu.ua
Received: 21 April 2025; Revised: 26 May 2025;
Accepted: 11 June 2025; Available on-line: 07 July 2025
Tissue-specific DNA methylation plays an important role in the regulation of many functional processes. The methylation level in single cells can be assessed using the comet assay (single-cell gel electrophoresis), a simple and cost-effective technique. The methyl-sensitive comet assay approach has been widely used under the assumption that methylation in the context of CpG dinucleotides is the only type of this modification. However, although CpG is the main methylation target, non-CpG methylation is also widespread. We used the methyl-sensitive comet assay to demonstrate that, in human lymphocytes, non-CpG methylation significantly contributes to the global methylation level. The activation of lymphocyte proliferation results in an increase in non-CpG methylation, and the methyl-sensitive comet assay can be used to assess the ratio between CpG and non-CpG methylation levels.
DNA loop domain rearrangements in blast transformed human lymphocytes and lymphoid leukaemic Jurkat T cells
K. Afanasieva1, V. Olefirenko1, A. Martyniak1,
L. Lukash2, A. Sivolob1*
1Taras Shevchenko National University of Kyiv, Ukraine;
2Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, Kyiv;
*e-mail: sivolob@univ.kiev.ua
Received: 06 April 2020; Accepted: 25 June 2020
Chromatin loops are important elements of both chromatin higher-order structure and transcription regulation system. Our previous works have shown that several features of the loop domain organization could be investigated by single cell gel electrophoresis (the comet assay) using the kinetic approach. In this study we applied this technique to study DNA loop domain organization in lymphoid cells: human lymphocytes, lymphoblasts cultivated during 24 h and 44 h, and T cells of Jurkat cell line. Two features of the loop domain organization were found to depend on the cell functional state. First, DNA fraction in the loops of large sizes (more than ~200 kb) was essentially increased in proliferating (de-differentiated) cells in comparison with terminally differentiated lymphocytes. Second, the linear density of the loops not larger than ~200 kb was decreased in transcriptionally active cells and was increased upon their inactivation.