Inherited trinucleotide repeat (TNR) instability, (i.e. expansions and deletions/contractions) is associated with more than 40 human familial neurodegenerative diseases and cancer. Non-inherited somatic TNR instability may be involved in the development of these diseases in the general public. No effective treatment for TNR- related diseases is yet available, partially because of a poor understanding of the underlying mechanisms. We have recently discovered that DNA base damage and base excision repair (BER) initiate and modulate somatic CAG repeat expansion and deletion by inducing single-strand DNA (ssDNA) breaks and promoting the formation of GC self-base-pairing hairpins. This indicates a new role of DNA base lesions, ssDNA breaks and BER in modulating TNR instability. To explore the potential of DNA damage and BER as new targets for the prevention and treatment of TNR-related diseases, in this project we seek to understand how environmentally and chemotherapeutically induced ssDNA breaks and their inefficient repair are involved in somatic TNR instability during BER. This goal will be achieved by pursuing three Specific Aims.
Aim 1 is to determine if the accumulation of environmentally and chemotherapeutically induced DNA base lesions and ssDNA breaks can preferentially lead to CAG repeat instability in a site-specific manner. Site-specific accumulation of the ssDNA breaks in CAG/CTG repeat tracts induced by environmental toxicants and chemotherapeutic agents such as vinyl chloride and temozolomide will be determined. The unique patterns of ssDNA break accumulation induced by DNA-damaging agents will be correlated with repeat expansion and deletion to identify damage- specific """"""""position effects"""""""" on CAG repeat instability. The effects will be further examined under imbalanced levels of BER enzymes and cofactors to determine if TNR instability can be modulated by compromised BER efficiency.
Aim 2 is to test the hypothesis that inefficient BER facilitates CAG repeat deletion by promoting the formation of multiple non-B-form DNA structures. This will be done by determining if inefficient DNA synthesis by DNA polymerases (Pol ? genetic variants, Pol ?) can facilitate the accumulation of a template hairpin and promote TNR deletion.
Aim 3 is to determine if TNR expansion and deletion can be prevented by efficiently disrupting non-B-form DNA structures through BER protein-protein interactions and functional coordination. This project addresses the fundamental mechanisms underlying DNA damage-induced somatic TNR instability by dissecting the interplay among environmental and chemotherapeutic DNA damage, BER, and TNR instability. The results will provide important new insights into how exposure to environmental and chemotherapeutic stresses may influence the development and progression of TNR-related human diseases in the general population, and how these adverse effects can be prevented by DNA damage repair. This will help to identify novel targets for prevention, diagnosis, and treatment of TNR-related diseases, and provide new information for risk assessment of environmentally and chemotherapeutically induced genotoxic effects.
Inherited trinucleotide repeat (TNR) expansion-induced familial neurodegenerative diseases affect large numbers of people in the United States and other countries, and non-inherited somatic TNR expansion and deletion in specific genes and tissues induced by environmental, chemotherapeutic and endogenous stresses may result in neurodegeneration and cancer in the general population. This project seeks to understand the molecular mechanisms underlying somatic TNR instability induced by environmental and chemotherapeutic DNA damaging agents, information that is key to identifying targets for the prevention and treatment of TNR- related diseases. The research of the project will provide new insights into the basis of human neurodegeneration and cancer;facilitate the identification of DNA repair proteins as novel targets for the prevention, diagnosis, and treatment of environmentally and chemotherapeutically triggered human diseases;and make new contributions to the risk assessment of environmentally and chemotherapeutically induced genotoxic effects.
|Lai, Yanhao; Weizmann, Yossi; Liu, Yuan (2018) The deoxyribose phosphate lyase of DNA polymerase ? suppresses a processive DNA synthesis to prevent trinucleotide repeat instability. Nucleic Acids Res 46:8940-8952|
|Beaver, Jill M; Lai, Yanhao; Rolle, Shantell J et al. (2018) An oxidized abasic lesion inhibits base excision repair leading to DNA strand breaks in a trinucleotide repeat tract. PLoS One 13:e0192148|
|Suzol, Sazzad H; Howlader, A Hasan; Wen, Zhiwei et al. (2018) Pyrimidine Nucleosides with a Reactive (?-Chlorovinyl)sulfone or (?-Keto)sulfone Group at the C5 Position, Their Reactions with Nucleophiles and Electrophiles, and Their Polymerase-Catalyzed Incorporation into DNA. ACS Omega 3:4276-4288|
|Wen, Zhiwei; Peng, Jufang; Tuttle, Paloma R et al. (2018) Electron-Mediated Aminyl and Iminyl Radicals from C5 Azido-Modified Pyrimidine Nucleosides Augment Radiation Damage to Cancer Cells. Org Lett :|
|Gu, Shiyan; Lai, Yanhao; Chen, Hongyu et al. (2017) miR-155 mediates arsenic trioxide resistance by activating Nrf2 and suppressing apoptosis in lung cancer cells. Sci Rep 7:12155|
|Chen, Wei; Tuladhar, Anupama; Rolle, Shantelle et al. (2017) Brevetoxin-2, is a unique inhibitor of the C-terminal redox center of mammalian thioredoxin reductase-1. Toxicol Appl Pharmacol 329:58-66|
|Luo, Qingyin; Beaver, Jill M; Liu, Yuan et al. (2017) Dynamics of p53: A Master Decider of Cell Fate. Genes (Basel) 8:|
|Chen, Chengzhi; Jiang, Xuejun; Gu, Shiyan et al. (2017) Protection of Nrf2 against arsenite-induced oxidative damage is regulated by the cyclic guanosine monophosphate-protein kinase G signaling pathway. Environ Toxicol 32:2004-2020|
|Ren, Yaou; Lai, Yanhao; Laverde, Eduardo E et al. (2017) Modulation of trinucleotide repeat instability by DNA polymerase ? polymorphic variant R137Q. PLoS One 12:e0177299|
|Lai, Yanhao; Jiang, Zhongliang; Zhou, Jing et al. (2016) AP endonuclease 1 prevents the extension of a T/G mismatch by DNA polymerase ? to prevent mutations in CpGs during base excision repair. DNA Repair (Amst) 43:89-97|
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