The human genome is subject to constant attack by endogenous and environmental DNA damaging agents. Ifunrepaired, DNA lesions will give rise to mutations that in turn may lead to cancer formation. Fortunately, acomplex network of DNA repair pathways operates to remove DNA lesions. To assess the biologicalsignificance of exposure to environmental DNA damaging agents, it is necessary to understand the details ofthe complex cellular response to DNA damage. Unlike the conserved LIG1 and LIG4 genes, lower eukaryoteslack a homolog of the mammalian LIG3 gene, which encodes at least three distinct polypeptides. Interestingly,the DNA ligase III -associated proteins, poly (ADP-ribose) polymerase 1 (PARP-1), XRCC1 and DNApolymerase (Pol) , each of which have been implicated in base excision repair and the repair of DNA singlestrand breaks, are also found only in higher eukaryotes. Using a modified yeast two hybrid assay, we haveidentified a series of XRCC1 mutants that are defective in specific protein-protein interactions.
In Specific Aim1, we will utilize these mutants to delineate the functional and biological consequences of protein-proteininteractions between DNA ligase III /XRCC1 and other proteins involved in base excision and single strandbreak repair. Recent studies have increased the repertoire of DNA repair transactions in which DNA ligaseIII /XRCC1 participates.
In Specific Aim 2, we will determine how DNA ligase III /XRCC1 is recruited to theDNA nucleotide excision repair machinery and whether this involves an interaction between XRCC1 andPCNA. In preliminary studies, we have identified an interaction between DNA ligase III /XRCC1 andhRad50/hMre11/Nbs.
In Specific Aim 3, we will determine how DNA damage regulates this interaction andwhether these proteins act together in an error-prone non-homologous end-joining sub pathway that repairsDNA double strand breaks. Interestingly, this error-prone pathway is up-regulated in cancer cells and maycontribute to their characteristic genomic instability.
In Specific Aim 4, we will identify and characterize smallmolecule inhibitors of DNA ligase III. We envision that that these inhibitors will not only be valuable reagentsfor elucidating the cellular functions of the LIG3 gene products but also may serve as lead compounds for thedevelopment of novel anti-cancer agents.

Public Health Relevance

It is well established that genomic instability drives the progression from a normal cell into a cancer cell. Human cells have a complex network of pathways that act together to maintain genome stability. A mechanistic understanding of these pathways will provide fundamental insights into tumor suppression. In addition, genomic instability is a characteristic of tumor cells, indicating that there are differences in the pathways that normally maintain stability. These differences between normal and cancer cells offer an opportunity to develop therapeutic strategies that selectively target cancer cells.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
7R01ES012512-09
Application #
8386726
Study Section
Special Emphasis Panel (ZRG1-ONC-H (02))
Program Officer
Mcallister, Kimberly A
Project Start
2004-04-22
Project End
2014-02-28
Budget Start
2011-09-19
Budget End
2012-02-29
Support Year
9
Fiscal Year
2011
Total Cost
$145,101
Indirect Cost
Name
University of New Mexico Health Sciences Center
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
829868723
City
Albuquerque
State
NM
Country
United States
Zip Code
87131
Sallmyr, Annahita; Matsumoto, Yoshihiro; Roginskaya, Vera et al. (2016) Inhibiting Mitochondrial DNA Ligase IIIα Activates Caspase 1-Dependent Apoptosis in Cancer Cells. Cancer Res 76:5431-41
Greco, George E; Matsumoto, Yoshihiro; Brooks, Rhys C et al. (2016) SCR7 is neither a selective nor a potent inhibitor of human DNA ligase IV. DNA Repair (Amst) 43:18-23
Ghezraoui, Hind; Piganeau, Marion; Renouf, Benjamin et al. (2014) Chromosomal translocations in human cells are generated by canonical nonhomologous end-joining. Mol Cell 55:829-42
Tomkinson, Alan E; Sallmyr, Annahita (2013) Structure and function of the DNA ligases encoded by the mammalian LIG3 gene. Gene 531:150-7
Tobin, L A; Robert, C; Rapoport, A P et al. (2013) Targeting abnormal DNA double-strand break repair in tyrosine kinase inhibitor-resistant chronic myeloid leukemias. Oncogene 32:1784-93
Tomkinson, Alan E; Howes, Timothy R L; Wiest, Nathaniel E (2013) DNA ligases as therapeutic targets. Transl Cancer Res 2:
Dey, Sanjib; Maiti, Amit K; Hegde, Muralidhar L et al. (2012) Increased risk of lung cancer associated with a functionally impaired polymorphic variant of the human DNA glycosylase NEIL2. DNA Repair (Amst) 11:570-8
Della-Maria, Julie; Hegde, Muralidhar L; McNeill, Daniel R et al. (2012) The interaction between polynucleotide kinase phosphatase and the DNA repair protein XRCC1 is critical for repair of DNA alkylation damage and stable association at DNA damage sites. J Biol Chem 287:39233-44
Tobin, Lisa A; Robert, Carine; Nagaria, Pratik et al. (2012) Targeting abnormal DNA repair in therapy-resistant breast cancers. Mol Cancer Res 10:96-107
Goula, Agathi-Vasiliki; Pearson, Christopher E; Della Maria, Julie et al. (2012) The nucleotide sequence, DNA damage location, and protein stoichiometry influence the base excision repair outcome at CAG/CTG repeats. Biochemistry 51:3919-32

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