title: Cell cycle-dependent association of Rad51 with the nuclear matrix.
abstract: Progression of the cells through the S phase of the cell cycle is connected with accumulation of stalled and collapsed replication forks that are repaired by homologous recombination. To investigate the temporal order of homologous recombination events during the S phase, HeLa cells synchronized at the G1/S phase boundary with mimosine were released to progress into the S phase and the phosphorylation of the histone variant H2AX, the appearance of Rad51 nuclear foci and the subcellular redistribution of Rad51 were followed. The results showed that there was gradual accumulation of double-strand breaks as judged by the increase in the phosphorylation of H2AX during the S phase. Rad51 nuclear foci did not appear until middle S phase, and this was accompanied by an increase in the chromatin- and nuclear matrix-bound Rad51 in the middle to late S phase. To determine the role of the intra S phase checkpoint in the S phase-dependent redistribution of Rad51 the cells were released in the S phase in the presence of the protein kinase inhibitors caffeine and wortmannin. The results suggest that the association of Rad51 with the nuclear matrix is regulated by activation of the intra S phase ATR-dependent checkpoint pathway.
authors.affiliation: Institute of Molecular Biology, Bulgarian Academy of Sciences, Sofia, Bulgaria.
authors.forename: Emil
authors.initials: E
authors.lastname: Mladenov
authors.forename: Irina
authors.initials: I
authors.lastname: Tsaneva
authors.forename: Boyka
authors.initials: B
authors.lastname: Anachkova
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis; D053903:DNA Breaks, Double-Stranded; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000502:physiology; D006367:HeLa Cells; D006657:Histones / Q000378:metabolism*; D006801:Humans; D015530:Nuclear Matrix / Q000502:physiology*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D051135:Rad51 Recombinase / Q000378:metabolism / Q000502:physiology*; D016196:S Phase / Q000502:physiology*; D025521:Tumor Suppressor Proteins / Q000502:physiology
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C468783:H2AX protein, human; D006657:Histones; D025521:Tumor Suppressor Proteins; D004247:DNA; C576324:ATM protein, human; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; C495153:RAD51 protein, human; D051135:Rad51 Recombinase