DNA EXCISION REPAIR AND DNA DAMAGE CHECKPOINTS Nucleotide excision repair and DNA damage checkpoints are two major cellular responses to DNA damage that are essential for genomic stability. The goal of our research is to understand the molecular mechanisms of these systems and to use this information to develop cancer prevention and treatment strategies. To accomplish this goal we will perform the following experiments.
Aim 1. Nucleotide Excision Repair and Skin Cancer Development as a Function of the Circadian Clock. Our studies on the regulation of nucleotide excision repair in mammals have revealed that excision repair exhibits high amplitude oscillation with a daily periodicity in most mouse tissues. We will analyze the daily variability of excision repair of UV photoproducts in skin and determine whether this variability is associated with carcinogenicity of UV light delivered at different times of the day. The results of this study will enable us to make specific recommendations to lower the incidence of skin cancer induced by sunlight and other UV sources.
Aim 2. Biochemical Analysis of the UV-Induced DNA Damage Checkpoint. We will purify and characterize the proteins involved in ATR kinase-mediated DNA damage checkpoint response which is the primary checkpoint pathway activated by UV and UV-mimetic chemical agents. We will reconstitute this checkpoint system from highly purified components in vitro and analyze the coupling of nucleotide excision repair with the ATR checkpoint signaling pathway. Understanding this DNA damage signaling pathway should facilitate the design of novel chemotherapeutic approaches to treat cancer.

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PROJECT NARRATIVE We propose to carry out experiments on two major cellular responses to UV- and UV-mimetic drug- induced DNA damage: Translational research on nucleotide excision repair in mice and mechanistic research on ATR-mediated DNA damage checkpoints. We will use biochemical, cell biological, genetic, and animal model systems in our research and provide mechanistic and animal model data for cancer prevention and treatment.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Molecular Genetics A Study Section (MGA)
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Janes, Daniel E
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University of North Carolina Chapel Hill
Schools of Medicine
Chapel Hill
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Kemp, Michael G; Gaddameedhi, Shobhan; Choi, Jun-Hyuk et al. (2014) DNA repair synthesis and ligation affect the processing of excised oligonucleotides generated by human nucleotide excision repair. J Biol Chem 289:26574-83
Choi, Jun-Hyuk; Gaddameedhi, Shobhan; Kim, So-Young et al. (2014) Highly specific and sensitive method for measuring nucleotide excision repair kinetics of ultraviolet photoproducts in human cells. Nucleic Acids Res 42:e29
Lindsey-Boltz, Laura A; Kemp, Michael G; Reardon, Joyce T et al. (2014) Coupling of human DNA excision repair and the DNA damage checkpoint in a defined in vitro system. J Biol Chem 289:5074-82
Hassan, Bachar H; Lindsey-Boltz, Laura A; Kemp, Michael G et al. (2013) Direct role for the replication protein treslin (Ticrr) in the ATR kinase-mediated checkpoint response. J Biol Chem 288:18903-10
Ozkan-Dagliyan, Irem; Chiou, Yi-Ying; Ye, Rui et al. (2013) Formation of Arabidopsis Cryptochrome 2 photobodies in mammalian nuclei: application as an optogenetic DNA damage checkpoint switch. J Biol Chem 288:23244-51
Lee, Jin Hyup; Gaddameedhi, Shobhan; Ozturk, Nuri et al. (2013) DNA damage-specific control of cell death by cryptochrome in p53-mutant ras-transformed cells. Cancer Res 73:785-91
Hu, Jinchuan; Choi, Jun-Hyuk; Gaddameedhi, Shobhan et al. (2013) Nucleotide excision repair in human cells: fate of the excised oligonucleotide carrying DNA damage in vivo. J Biol Chem 288:20918-26
Sercin, Ozdemirhan; Kemp, Michael G (2011) Characterization of functional domains in human Claspin. Cell Cycle 10:1599-606
Lindsey-Boltz, Laura A; Sancar, Aziz (2011) Tethering DNA damage checkpoint mediator proteins topoisomerase IIbeta-binding protein 1 (TopBP1) and Claspin to DNA activates ataxia-telangiectasia mutated and RAD3-related (ATR) phosphorylation of checkpoint kinase 1 (Chk1). J Biol Chem 286:19229-36
Lee, Jin Hyup; Sancar, Aziz (2011) Regulation of apoptosis by the circadian clock through NF-kappaB signaling. Proc Natl Acad Sci U S A 108:12036-41

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