Experimental studies to determine the distribution and localization of proteins in cells. Final progress report, April 1, 1992--March 31, 1993

摘要

We previously demonstrated the existence of a region of DNA hypersensitive to hydrolysis by DNAse I (exposed DNA) around the periphery of the nucleus in all normal cell tested but in none of 16 different cancers. To achieve molecular understanding of this process, experiments were now undertaken to identify the role of proteins in the genome exposure reaction. Immunofluorescence experiments were carried out with antibodies to a variety of proteins. Of these, it was demonstrated that the lamins and topoisomerase II alone exhibit a distribution in the nucleus resembling that if the exposed DNA. Studies were carried out to determine differences in cytoskeletal proteins in normal and transformed cells. It was found that treatment of transformed CHO K1 cells with cyclic AMP so as to bring about reverse transformation and normal genome exposure will, on prolonged interaction, also produce apoptosis. The existence of DNA in exposed and sequestered forms in the nucleus suggests that sequestered forms might be more susceptible to mutagenesis by alpha rays or by chemical mutagens but not by high energy gamma radiation than sequestered forms which presumably may enjoy some protection from their protein interaction.