Diverse xenobiotic environmental exposures introduce deleterious stress in living cells. DNA damage response (DDR) counteracts the effects of omnipresent genotoxic insult from within and outside cell. The recruitment of an ever-increasing list of factors to damaged genomic sites is not only intricately and inextricably linked but their interplay dictates the nature as well as course of DDR. Due to a wide-ranging inter-molecular crosstalk between DDR components this continuation grant will focus on studying the interaction and influence of relevant overlapping factors of NER and checkpoint signaling pathways. The proposal is based on the premise that UV damage simultaneously activates diverse events impinging on access to damage and repair as well as restoration of epigenetically intact chromatin and normal cell cycling. Specific hypothesis underlying the proposed work is that initial sensors of UV damage, DDB and XPC complexes, are intimately associated with signaling kinases, ATR and ATM, and their interaction, in conjunction with chromatin remodeling factors, histone chaperons and histone modifying proteins, determines all key aspects of DDR related to NER. The proposed work will utilize a relevant plethora of state-of-the art technologies to address following inter-related specific objectives: (1) to demonstrate the function of DDB and XPC in checkpoint activation, (2) to understand the roles of histone ubiquitination and acetylation in checkpoint signaling, (3) to ascertain the influence of chromatin remodeler, INO80, in checkpoint maintenance, and (4) to establish the participation of histone chaperons, ASF1 and NASP, in cell cycle checkpoint recovery. Variety of human cell lines lacking individual protein factors, either constitutively or by siRNA/shRNA mediated gene silencing, will be utilized at select stages of cell cycle to analyze the effects on checkpoint protein markers and reveal their functional interactions through FACS analysis, ChIP, co-immunoprecipitation and/or by co-localization assays. Biochemical characterization of ATR/ATM substrates will be achieved by mutational alterations of SQ/TQ substrate motifs followed by their functional analysis. Select histone modifications will be evaluated in specifically compromised cells to reveal alterations regulating NER and cell cycle progression. Lastly, purified recombinant histones and chaperons will be tested in vitro to delineate their NER, checkpoint and cell cycle specific biochemical roles in vivo. These systematic studies will furnish crucial insights regarding the key events initiated upon xenobiotic exposures of mammalian cells with the ultimate goal of human health risk assessment and management.
DNA damage from exposure to environmental agents provokes highly conserved cellular responses essential for maintaining genetic and epigenetic hallmarks of the human genome. The signals emanating from introduction of genomic damage activate checkpoints for arresting cells cycle, successful completion of DNA repair or elimination of irreparably injured cells through apoptosis. The recruitment of factors mediating these events at or near the damage site is not only intricately and inextricably linked but their interplay dictates the nature as well as course of DNA damage response. The proposed work, on the theme of deciphering the inter-molecular cross-talk between DNA repair and signaling, has important implications to human health risk assessment and management.
|Ding, Nan; Zhu, Qianzheng (2018) Disulfiram combats cancer via crippling valosin-containing protein/p97 segregase adaptor NPL4. Transl Cancer Res 7:S495-S499|
|He, Jinshan; Zhu, Qianzheng; Wani, Gulzar et al. (2017) UV-induced proteolysis of RNA polymerase II is mediated by VCP/p97 segregase and timely orchestration by Cockayne syndrome B protein. Oncotarget 8:11004-11019|
|Zhu, Qianzheng; Wani, Altaf A (2017) Nucleotide Excision Repair: Finely Tuned Molecular Orchestra of Early Pre-incision Events. Photochem Photobiol 93:166-177|
|Zhu, Qianzheng; Wei, Shengcai; Sharma, Nidhi et al. (2017) Human CRL4DDB2 ubiquitin ligase preferentially regulates post-repair chromatin restoration of H3K56Ac through recruitment of histone chaperon CAF-1. Oncotarget 8:104525-104542|
|Rehmani, Nida; Zafar, Atif; Arif, Hussain et al. (2017) Copper-mediated DNA damage by the neurotransmitter dopamine and L-DOPA: A pro-oxidant mechanism. Toxicol In Vitro 40:336-346|
|He, Jinshan; Zhu, Qianzheng; Wani, Gulzar et al. (2016) Valosin-containing Protein (VCP)/p97 Segregase Mediates Proteolytic Processing of Cockayne Syndrome Group B (CSB) in Damaged Chromatin. J Biol Chem 291:7396-408|
|Han, Chunhua; Srivastava, Amit Kumar; Cui, Tiantian et al. (2016) Differential DNA lesion formation and repair in heterochromatin and euchromatin. Carcinogenesis 37:129-38|
|Ray, Alo; Blevins, Chessica; Wani, Gulzar et al. (2016) ATR- and ATM-Mediated DNA Damage Response Is Dependent on Excision Repair Assembly during G1 but Not in S Phase of Cell Cycle. PLoS One 11:e0159344|
|Zhu, Qianzheng; Battu, Aruna; Ray, Alo et al. (2015) Damaged DNA-binding protein down-regulates epigenetic mark H3K56Ac through histone deacetylase 1 and 2. Mutat Res 776:16-23|
|Han, Chunhua; Wani, Gulzar; Zhao, Ran et al. (2015) Cdt2-mediated XPG degradation promotes gap-filling DNA synthesis in nucleotide excision repair. Cell Cycle 14:1103-15|
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