EVIDENCE FOR AN EARLY AND TRANSIENT INVOLVEMENT OF NUCLEAR INOSITOL LIPIDS IN SUBCELLULAR SIGNALING EVENTS RELATED TO DNA-REPAIR PROCESSES

The involvement of nuclear inositol lipids in the processes related to DNA repair upon ionizing radiation has been investigated in Murine Er ythroleukaemia cells. Early changes in the in vitro phosphatidylinosit ol-bisphosphate phosphorylation in isolated nuclei were found to prece de transiently the marked increase in DNA synthesis occurring after ir radiation. Such an increase detected by anti BrdU monoclonal antibodie s has been found to be related mainly to DNA polymerase beta activity as revealed by the kinetic analysis of in vitro DNA synthesis. The res ults here presented allow us to speculate on a possible involvement of nuclear inositol lipids in the cascade of the early events leading to the regulation of DNA repair in the nucleus.