Homologous recombination (HR) and non-homologous end joining (NHEJ) are conserved pathways for the repair of DNA double stranded breaks (DSBs) induced by ionizing radiation and genotoxic chemicals. HR utilizes a homologous template strand to repair damaged DNA in an error-free manner. NHEJ, which entails processing of the broken chromosome ends and their ligation, is often error-prone. HR is initiated by nucleolytic processing of the DNA break to yield 3'ssDNA tails for the recruitment of the repair machinery. Studies in the model eukaryote Saccharomyces cerevisiae have revealed multiple pathways of DNA break resection, two of which are responsible for long-range resection. DNA break processing is regulated during the cell cycle. Specifically, NHEJ proteins suppress it in G1, but this suppression is relieved during S and G2. In the K99 phase of this project, the candidate will determine the mechanisms of polarity control and DNA end engagement during the end resection process. In the R00 phase, the candidate will elucidate the functional crosstalk between the long-range resection paths that are dependent on Sgs1/Dna2 and Exo1 and will also examine how the restriction imposed by NHEJ proteins is overcome by DNA motor proteins in conjunction with the Mre11 complex. Given the remarkable degree of conservation of the DNA end resection mechanisms, the results from this project should provide a valuable experimental framework to guide similar endeavors in other eukaryotes, including humans. Public Health Relevance: DNA damaging agents induce genetic mutations and genome rearrangements. The proposed studies will delineate the mechanism by which DNA breaks resulting from exposure to radiation and genotoxic chemicals are nucleolytically processed in order to activate the DNA damage checkpoint and to prepare for damage repair by homologous recombination. The results from the research endeavors have direct relevance to understanding the relevance of DNA repair in health and disease.

Public Health Relevance

DNA damaging agents induce genetic mutations and genome rearrangements. The proposed studies will delineate the mechanism by which DNA breaks resulting from exposure to radiation and genotoxic chemicals are nucleolytically processed in order to activate the DNA damage checkpoint and to prepare for damage repair by homologous recombination. The results from our research endeavors have direct relevance to understanding the relevance of DNA repair in health and disease. !

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Career Transition Award (K99)
Project #
1K99ES021441-01
Application #
8278904
Study Section
Special Emphasis Panel (ZES1-LKB-D (D))
Program Officer
Shreffler, Carol K
Project Start
2012-05-10
Project End
2014-04-30
Budget Start
2012-05-10
Budget End
2013-04-30
Support Year
1
Fiscal Year
2012
Total Cost
$90,000
Indirect Cost
$6,667
Name
Yale University
Department
Biochemistry
Type
Schools of Medicine
DUNS #
043207562
City
New Haven
State
CT
Country
United States
Zip Code
06520
Daley, James M; Chiba, Tamara; Xue, Xiaoyu et al. (2014) Multifaceted role of the Topo III?-RMI1-RMI2 complex and DNA2 in the BLM-dependent pathway of DNA break end resection. Nucleic Acids Res 42:11083-91
Potenski, Catherine J; Niu, Hengyao; Sung, Patrick et al. (2014) Avoidance of ribonucleotide-induced mutations by RNase H2 and Srs2-Exo1 mechanisms. Nature 511:251-4