DNA double-strand breaks (DSB)s are induced by a variety of genotoxic agents, including ionizing radiation and chemicals used for treating cancers. The elimination of DSBs proceeds via distinctive error-free and error-prone pathways. Repair by homologous recombination is largely error-free and mediated by the RAD52 epistasis group genes. Non-homologous end joining (NHEJ) that requires the Ku heterodimer can efficiently rejoin breaks, with occasional loss or gain of DNA information. Emerging evidence has unveiled a novel DNA end-joining mechanism that is independent of Rad52 and Ku proteins. This novel pathway of DSB repair seals DNA breaks by microhomology-mediated base-pairing of DNA single strands, followed by nucleolytic trimming of DNA flaps, DNA gap filling, and DNA ligation, yielding products that are almost always associated with DNA deletion. This highly error-prone DSB repair pathway is termed microhomology-mediated end joining (MMEJ). Dissecting the mechanism of MMEJ is of great interest because of its potential to destabilize the genome through gene deletions. We have developed a Saccharomyces-based biological system to create specific double-strand breaks that are preferentially repaired by MMEJ. The availability of this MMEJ assay presents a unique opportunity to dissect the genetic requirement of this reaction. In fact, this biological system has already allowed us to identify several gene products that affect the efficiency of MMEJ. The focus of this proposal is to delineate the functions of these gene products in MMEJ and to identify additional genes that influence this process. Since the components of DSB repair are conserved from yeast to humans, the insights garnered from our research will be valuable for dissecting the equivalent process in human cells and will be of relevance to public health. ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM071011-02
Application #
6868203
Study Section
Special Emphasis Panel (ZRG1-CDF-2 (90))
Program Officer
Portnoy, Matthew
Project Start
2004-04-01
Project End
2008-03-31
Budget Start
2005-04-01
Budget End
2006-03-31
Support Year
2
Fiscal Year
2005
Total Cost
$240,550
Indirect Cost
Name
University of Texas Health Science Center San Antonio
Department
Other Basic Sciences
Type
Other Domestic Higher Education
DUNS #
800772162
City
San Antonio
State
TX
Country
United States
Zip Code
78229
Wang, Weibin; Daley, James M; Kwon, Youngho et al. (2018) A DNA nick at Ku-blocked double-strand break ends serves as an entry site for exonuclease 1 (Exo1) or Sgs1-Dna2 in long-range DNA end resection. J Biol Chem 293:17061-17069
Eichmiller, Robin; Medina-Rivera, Melisa; DeSanto, Rachel et al. (2018) Coordination of Rad1-Rad10 interactions with Msh2-Msh3, Saw1 and RPA is essential for functional 3' non-homologous tail removal. Nucleic Acids Res 46:5075-5096
Obeidat, Mohammad; McConnell, Kristen A; Li, Xiaolei et al. (2018) DNA double-strand breaks as a method of radiation measurements for therapeutic beams. Med Phys 45:3460-3465
Seol, Ja-Hwan; Holland, Cory; Li, Xiaolei et al. (2018) Distinct roles of XPF-ERCC1 and Rad1-Rad10-Saw1 in replication-coupled and uncoupled inter-strand crosslink repair. Nat Commun 9:2025
Sinha, Supriya; Villarreal, Diana; Shim, Eun Yong et al. (2016) Risky business: Microhomology-mediated end joining. Mutat Res 788:17-24
Liu, Yaqi; Sung, Sihyun; Kim, Youngran et al. (2016) ATP-dependent DNA binding, unwinding, and resection by the Mre11/Rad50 complex. EMBO J 35:743-58
Che, Jun; Smith, Stephanie; Kim, Yoo Jung et al. (2015) Hyper-Acetylation of Histone H3K56 Limits Break-Induced Replication by Inhibiting Extensive Repair Synthesis. PLoS Genet 11:e1004990
Sung, Sihyun; Li, Fuyang; Park, Young Bong et al. (2014) DNA end recognition by the Mre11 nuclease dimer: insights into resection and repair of damaged DNA. EMBO J 33:2422-35
Sarangi, Prabha; Altmannova, Veronika; Holland, Cory et al. (2014) A versatile scaffold contributes to damage survival via sumoylation and nuclease interactions. Cell Rep 9:143-152
Sarangi, Prabha; Bartosova, Zdenka; Altmannova, Veronika et al. (2014) Sumoylation of the Rad1 nuclease promotes DNA repair and regulates its DNA association. Nucleic Acids Res 42:6393-404

Showing the most recent 10 out of 23 publications