Changes in loop organization of chromatin at different stages of lymphocyte activation

  • K. S. Afanasieva Taras Shevchenko National University of Kyiv, Ukraine, 01601, Kyiv, Volodimyrska str., 64/13
  • O. V. Lozovik Taras Shevchenko National University of Kyiv, Ukraine, 01601, Kyiv, Volodimyrska str., 64/13
  • V. V. Olefirenko Taras Shevchenko National University of Kyiv, Ukraine, 01601, Kyiv, Volodimyrska str., 64/13
  • A. V. Sivolob Taras Shevchenko National University of Kyiv, Ukraine, 01601, Kyiv, Volodimyrska str., 64/13


Aim. Aim was to investigate possible changes in the DNA loop domain organization upon activation of human lymphocytes. The rational for this task is the knowledge that the chromatin looping plays an important role in transcription regulation and thus may vary depending on cell functional state. Methods. The kinetics of DNA loop migration during single cell gel electrophoresis (the comet assay) was studied for nucleoids obtained from human lymphocytes and lymphoblasts activated to proliferation by interleukin 2. Results. Three part of DNA were observed in nucleoids: DNA on the nucleoid surface, loops up to ~150 kb inside the nucleoid, and larger loops that cannot migrate. An essential redistribution of the loop domains between the inside and surface fractions occurs upon activation (at G1 phase). Later on (at the end of S phase) the inside fraction becomes lower in favor of the large loops. Conclusions. Changes in the cell functional state are accompanied by large-scale changes in the loop domain organization that can be detected by the comet assay.
Keywords: DNA loops, nucleoid, comet assay, lymphocytes, lymphoblasts.


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