title: p53 dependence of topoisomerase I recruitment in vivo.
abstract: DNA damage is attended by rapid recruitment of endogenous type I topoisomerase (topo I) into covalent cleavage complexes with genomic DNA in vivo. In contrast, endogenous topoisomerase II alpha and beta are not stimulated by DNA damage. We show that topo I and p53 are able to associate at arrested topo I-genomic DNA covalent complexes in vivo, suggesting that p53 directly stimulates topo I activity and damage to the genome of the afflicted cell. Moreover, cells that express wild-type p53 are most proficient at recruiting topo I after DNA damage; however, the p53 dependence is conditional because topo I recruitment after DNA damage can be restored if p53 mutant cells (containing a single mutant allele) are artificially held in G1. In contrast, p53 null mutants do not recruit topo I after DNA damage under any conditions (although camptothecin-dependent topo I/DNA complexes readily form in the nulls). These results show that topo I activation after DNA damage depends on the p53 status of the cell. It also depends upon the cell cycle in a way that is very different from that observed with DNA replication-dependent, camptothecin-mediated DNA breaks. The data suggest a model where p53 activates topo I, which inflicts additional genomic damage after the initial UV damage events. Topoisomerases therefore contribute to the p53 commitment to apoptosis, and topo I might assist in elimination of DNA-damaged cells as part of the cellular proofreading function inherent in the p53 pathway.
authors.affiliation: Department of Molecular Genetics, The Ohio State University, Columbus 43210, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Mao
authors.forename: S
authors.initials: S
authors.lastname: Okada
authors.forename: L S
authors.initials: LS
authors.lastname: Chang
authors.forename: M T
authors.initials: MT
authors.lastname: Muller
mesh_terms: D000951:Antigens, Neoplasm; D002453:Cell Cycle / Q000502:physiology; D003513:Cycloheximide / Q000494:pharmacology; D004247:DNA / Q000378:metabolism / Q000528:radiation effects; D004249:DNA Damage / Q000502:physiology; D004264:DNA Topoisomerases, Type I / Q000096:biosynthesis / Q000378:metabolism*; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D004268:DNA-Binding Proteins; D018922:HL-60 Cells; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D000951:Antigens, Neoplasm; D004268:DNA-Binding Proteins; D007527:Isoenzymes; D011500:Protein Synthesis Inhibitors; D016159:Tumor Suppressor Protein p53; D004247:DNA; D003513:Cycloheximide; D004264:DNA Topoisomerases, Type I; D004250:DNA Topoisomerases, Type II