The ordered disintegration of nuclear DNA as a specific genome reaction accompanying apoptosis, stress response and differentiation

The treatment of agarose embedded nucleaf or cellular preparations with protein denaturing agents resulted in ordered cleavage of intact nuclear DNA into high molecular weight fragments with the pattern of fragmentation being unityped for various eukaryotic representatives. We showed that the set of DNA fragments represents the pre-existing DNA structural domains attributed to the higher levels of chromatin folding, and presented evidence allowing to interpret the nuclear DNA domain organization as a constituent component of topoisomerase II/DNA complex with its ability to mediate the cleavage/ religation reactions. We demonstrated that changes in the integrity of nuclear DNA, recognizable as an altered pattern of SDS-dependent cleavage of nuclear DNA into high molecular weight DNA fragments, took place at the early stage of apoptosis, upon number of stress challenges and in cells showing various proliferative status. The changes in the integrity of nuclear DNA affected by various influences were shown to be prompt and seem to be of transient nature. The results obtained allow to conclude that changes in the integrity of nuclear DNA revealed as an altered pattern of SDS-dependent high molecular weight DNA cleavage may present the specific genome reaction accompanying the physiological changes in the cells during apoptosis, stress response and differentiation*Corespondence address.