Heat-induced changes in nuclear-associated proteins in normal and thermotolerant HeLa cells

In the present study we used one-dimensional 7-10% gradient SDS polyacrylamide gels to resolve the proteins associated with nuclei isolated from normal and heat-shocked cells. By analyzing the relative optical density of 27-30 polypeptide bands as a function of the duration of the heat shock or the time of incubation after heating, we were able to observe the following regarding heat-induced alterations in nuclear protein binding. Various proteins show an increased nuclear association in terms of their nuclear protein content, but the kinetics of this association is not identical for individual proteins. Moreover, the changes in these associations are differentially affected in nuclei from thermotolerant cells. This type of analysis demonstrates the possibility that the cellular effects of hyperthermia could be correlated with the altered binding and/or increased presence of specific proteins associated with the nucleus in heated cells.