Ionizing radiation, mutagenic chemicals, and replication of a damaged DNA template can induce DNA double-stranded breaks. If not handled properly, these breaks often lead to gross chromosome rearrangements. Homologous recombination helps eliminate DNA strand breaks in eukaryotes and is needed for tumor suppression in humans. In the homologous repair of a double-stranded break, the ends of the break are subject to exonucleolytic processing to yield 3'single-stranded DNA tails. Nucleation of various recombination factors onto these DNA tails renders them recombinogenic, leading to a search for the chromosomal homolog and the stable pairing of the DNA tails with the homolog to form a DNA joint called """"""""D-loop"""""""". In the later stages, DNA synthesis occurs, followed by the resolution of DNA intermediates to yield mature recombinants and restore the integrity of the injured chromosome. The evolutionarily conserved genes of the RAD52 epistasis group, of which RAD54 and RDH54 are key members, mediate homologous recombination and DNA strand break repair by recombination. Rad54 and Rdh45 are members of the Swi2/Snf2 super-family of DNA motor proteins. Studies to date have unveiled DNA translocase and chromatin remodeling activities in these two recombination factors and have provided an experimental framework for examining the functional interactions of these factors with the Rad51 and Dmc1 recombinases. Herein, we outline strategies for the continuing dissection of the multi-faceted role of Rad54 and Rdh54 in recombination and DNA repair reactions, for the identification and molecular characterization of Rad54 and Rdh54 protein complexes, and for the elucidation of a novel mechanism of recombination regulation that targets the Rad51/Rad54 axis. These planned studies should continue to yield insights into the mechanism of recombination pathways in eukaryotic cells.

Public Health Relevance

Our studies focus on the mechanism by which eukaryotic cells eliminate pre-cancerous lesions, such as DNA double-stranded breaks that are induced by ionizing radiation and chemicals, from chromosomes. Importantly, defective chromosome damage repair is the underlying cause of several cancer-prone diseases (e.g. Bloom's syndrome, Nijmegen breakage syndrome, and Fanconi anemia) and can pre-dispose affected individuals to a variety of cancers, including breast, ovarian, and pancreatic cancers. For these reasons, the studies outlined in the renewal application have direct relevance to cancer biology and public health.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM057814-12
Application #
8100544
Study Section
Radiation Therapeutics and Biology Study Section (RTB)
Program Officer
Janes, Daniel E
Project Start
1999-05-01
Project End
2013-07-31
Budget Start
2011-07-01
Budget End
2013-07-31
Support Year
12
Fiscal Year
2011
Total Cost
$291,972
Indirect Cost
Name
Yale University
Department
Biochemistry
Type
Schools of Medicine
DUNS #
043207562
City
New Haven
State
CT
Country
United States
Zip Code
06520
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Bonner, Jaclyn N; Choi, Koyi; Xue, Xiaoyu et al. (2016) Smc5/6 Mediated Sumoylation of the Sgs1-Top3-Rmi1 Complex Promotes Removal of Recombination Intermediates. Cell Rep 16:368-378
Niu, Hengyao; Potenski, Catherine J; Epshtein, Anastasiya et al. (2016) Roles of DNA helicases and Exo1 in the avoidance of mutations induced by Top1-mediated cleavage at ribonucleotides in DNA. Cell Cycle 15:331-6
Xue, Xiaoyu; Choi, Koyi; Bonner, Jaclyn N et al. (2015) Selective modulation of the functions of a conserved DNA motor by a histone fold complex. Genes Dev 29:1000-5
Xue, Xiaoyu; Sung, Patrick; Zhao, Xiaolan (2015) Functions and regulation of the multitasking FANCM family of DNA motor proteins. Genes Dev 29:1777-88
Daley, James M; Niu, Hengyao; Miller, Adam S et al. (2015) Biochemical mechanism of DSB end resection and its regulation. DNA Repair (Amst) 32:66-74
Krasner, Danielle S; Daley, James M; Sung, Patrick et al. (2015) Interplay between Ku and Replication Protein A in the Restriction of Exo1-mediated DNA Break End Resection. J Biol Chem 290:18806-16
Daley, James M; Gaines, William A; Kwon, YoungHo et al. (2014) Regulation of DNA pairing in homologous recombination. Cold Spring Harb Perspect Biol 6:a017954
Xue, Xiaoyu; Choi, Koyi; Bonner, Jaclyn et al. (2014) Restriction of replication fork regression activities by a conserved SMC complex. Mol Cell 56:436-45
Zhao, Qi; Saro, Dorina; Sachpatzidis, Aristidis et al. (2014) The MHF complex senses branched DNA by binding a pair of crossover DNA duplexes. Nat Commun 5:2987

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