Tumorigenesis is known to result from multiple genetic changes, which are often manifested as gross chromosome abnormalities. These can involve a single chromosomal translocation or be manifested as massive genome-wide instability. Although endogenous and environmental insults can damage DNA, robust cellular mechanisms exist to repair various forms of damage or to eliminate those cells that have been irreparably damaged. Hence, the accumulation of numerous genetic changes that would lead to cancer in normal cells is extremely rare. Nevertheless, disruption of a DNA repair pathway has the potential to expedite tumorigenesis by resulting in a cell that is hypermutable. DNA damage in the form of chromosomal double-strand breaks (DSBs) occurs spontaneously as a result of normal DNA metabolism and after exposure to exogenous DNA damaging agents, such as ionizing radiation. We demonstrated that a major pathway involved in DSB repair is homologous recombination in which an unbroken sequence templates the repair of a broken sequence to which it is homologous (i.e., homology-directed repair, or HDR). Other major DSB repair pathways are non-homologous end-joining (NHEJ), in which broken ends are rejoined using little or no sequence homology, and single-strand annealing. Recently, it has become clear that HDR and NHEJ mutants exhibit chromosome instability, both spontaneously and damage induced.
Our aim i s to begin to understand the contribution of different repair pathways in normal cells to DSB repair, and how this is altered in DSB repair mutants.
In Specific Aim 1, the contributions of DSB repair pathways in mouse embryonic stem cells will be examined and compared with repair in fibroblasts, as the reliance on repair factors for IR sensitivity varies in these cell types.
In Specific Aim 2, we will determine if an NHEJ mutant demonstrates a genetic dependence on a factor involved in HDR by constructing double mutants of the Rad54 and Ku80 genes, which are involved in HDR and NHEJ, respectively.
In Specific Aim 3, the effect of NHEJ mutations on molecular mechanisms of chromosomal translocations will be examined. We will exploit a system we have recently developed to induce chromosomal translocations and examine the effect of NHEJ mutations on the frequency and outcomes of these events.
In Specific Aim 4, we will examine the dynamics of DSB repair. We have thus far focused on the outcome of DSB repair after I-Scel cleavage of a chromosome. In this aim we will develop the DSB induction system to understand the dynamics of DSB repair in terms of the proteins associated with the repair process, the relative kinetics of different DSB repair processes, and initial processing steps at a DSB.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM054668-06
Application #
6622137
Study Section
Radiation Study Section (RAD)
Program Officer
Wolfe, Paul B
Project Start
1998-01-01
Project End
2005-12-31
Budget Start
2003-01-01
Budget End
2003-12-31
Support Year
6
Fiscal Year
2003
Total Cost
$358,600
Indirect Cost
Name
Sloan-Kettering Institute for Cancer Research
Department
Type
DUNS #
064931884
City
New York
State
NY
Country
United States
Zip Code
10065
Vriend, Lianne E M; Prakash, Rohit; Chen, Chun-Chin et al. (2016) Distinct genetic control of homologous recombination repair of Cas9-induced double-strand breaks, nicks and paired nicks. Nucleic Acids Res 44:5204-17
Browning, Cynthia L; Qin, Qin; Kelly, Deborah F et al. (2016) Prolonged Particulate Hexavalent Chromium Exposure Suppresses Homologous Recombination Repair in Human Lung Cells. Toxicol Sci 153:70-8
Jasin, Maria; Haber, James E (2016) The democratization of gene editing: Insights from site-specific cleavage and double-strand break repair. DNA Repair (Amst) 44:6-16
Prakash, Rohit; Zhang, Yu; Feng, Weiran et al. (2015) Homologous recombination and human health: the roles of BRCA1, BRCA2, and associated proteins. Cold Spring Harb Perspect Biol 7:a016600
Goglia, Alexander G; Delsite, Robert; Luz, Antonio N et al. (2015) Identification of novel radiosensitizers in a high-throughput, cell-based screen for DSB repair inhibitors. Mol Cancer Ther 14:326-42
Vriend, Lianne E M; Jasin, Maria; Krawczyk, Przemek M (2014) Assaying break and nick-induced homologous recombination in mammalian cells using the DR-GFP reporter and Cas9 nucleases. Methods Enzymol 546:175-91
Renouf, Benjamin; Piganeau, Marion; Ghezraoui, Hind et al. (2014) Creating cancer translocations in human cells using Cas9 DSBs and nCas9 paired nicks. Methods Enzymol 546:251-71
Zhang, Yu; Vanoli, Fabio; LaRocque, Jeannine R et al. (2014) Biallelic targeting of expressed genes in mouse embryonic stem cells using the Cas9 system. Methods 69:171-178
Ghezraoui, Hind; Piganeau, Marion; Renouf, Benjamin et al. (2014) Chromosomal translocations in human cells are generated by canonical nonhomologous end-joining. Mol Cell 55:829-842
Jasin, Maria; Rothstein, Rodney (2013) Repair of strand breaks by homologous recombination. Cold Spring Harb Perspect Biol 5:a012740

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