HEAT-INDUCED MODIFICATIONS IN THE ASSOCIATION OF SPECIFIC PROTEINS WITH THE NUCLEAR MATRIX

Nuclei isolated from heat-shocked mammalian cells have an increased pr otein content which reflects an enhanced protein binding to nuclear st ructures. These nuclear changes are correlated with cell survival and inhibition of DNA replication, transcription and repair of DNA damage. It appears that most of the altered protein binding occurs in associa tion with the nuclear matrix. The present study was conducted to deter mine if measurements of specific proteins in isolated nuclei reflect c hanges that occur at the nuclear matrix. The amounts of various protei ns associated with HeLa cell nuclei and nuclear matrices after heat sh ock were measured by (1) densitometric scans of Coomassie blue-stained gels, (2) immunoblotting with antibodies to nuclear proteins and (3) antisera raised against nuclear matrix proteins from heated cells. The se measurements revealed heat-induced increases in the levels of many nuclear matrix proteins. While a number of proteins show similar chang es in both nuclei and nuclear matrices, for many the extent of increas ed association with the nuclear matrix is not reflected in the measure d changes in the nuclei. These results are essential for understanding and studying further the relationships between the cellular response to hyperthermia and heat-altered associations of specific proteins wit h either nuclei or nuclear matrices. (C) 1996 by Radiation Research So ciety