Interaction between polyanions and cell nuclei: mechanism of gelatination of nuclei

We investigated the mechanism by which polyanions gelatinized nuclei of some mouse lymphocytes and ruptured these cells. The gel produced by the addition of dextran sulfate (DS) to mouse lymphocyte nuclei was composed of histones (H1, H2A, H2B, H3, and H4), DS, and DNA. Adding DS to the chromatin obtained from nuclei by micrococcal nuclease (MNase) digestion also produced a gel containing a complex of DS-histones-DNA. When this mixture was further digested by MNase, DNA debris of random sizes was observed instead of the 150-bp repeating units of DNA usually observed when normal nucleosomes are digested with MNase. Removal of DS from the chromatin-DS gel resulted in the regeneration of nucleosomes. These results suggest the following: After entering the cells with damaged cellular membrane, DS extracts histones from nucleosomes to form DS-histone complexes, which then aggregate with the liberated DNA to form a macromolecular gel. Finally, the swelling pressure of the gel destroys the cells.