ИСТИНА

Many proteins of the nucleolus are considered to be essential for optimal DNA repair. Here, we studied DNA damage-related events in compartment of nucleoli. We focused on nucleolar regions, positive on upstream binding factor 1 (UBF1) protein. After UVA or γ-irradiation, live cells were monitored by time-lapse confocal microscopy, and nucleoli were visualized according to the expression of GFP-UBF1. Thereafter, bioinformatics analyses revealed radiation-caused changes in morphology and local motion of nucleoli. We found that γ radiation induced changes in the area of nucleoli, area of UBF1-positive foci, and number of individual UBF1 foci. We also studied if changes of selected morphological parameters are cell cycle-specific. For such analyses we used HeLa-Fucci cells which are characterized by expression of RFP-tagged-cdt1 in the G1 phase and GFP-tagged geminin in the G2 phase of the cell cycle. This cellular model enable us to find cell cycle dependent nucleolar changes induced by γ-radiation. Together, advanced bioinformatics analyses showed the nucleolus as highly sensitive to genome injury and some morphological parameters of nucleoli are cell cycle-specific.