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.
|Qian, J; Pentz, K; Zhu, Q et al. (2015) USP7 modulates UV-induced PCNA monoubiquitination by regulating DNA polymerase eta stability. Oncogene 34:4791-6|
|Sharma, Nidhi; Zhu, Qianzheng; Wani, Gulzar et al. (2014) USP3 counteracts RNF168 via deubiquitinating H2A and ýýH2AX at lysine 13 and 15. Cell Cycle 13:106-14|
|He, Jinshan; Zhu, Qianzheng; Wani, Gulzar et al. (2014) Ubiquitin-specific protease 7 regulates nucleotide excision repair through deubiquitinating XPC protein and preventing XPC protein from undergoing ultraviolet light-induced and VCP/p97 protein-regulated proteolysis. J Biol Chem 289:27278-89|
|Zhao, Ran; Han, Chunhua; Eisenhauer, Eric et al. (2014) DNA damage-binding complex recruits HDAC1 to repress Bcl-2 transcription in human ovarian cancer cells. Mol Cancer Res 12:370-80|
|Ray, Alo; Milum, Keisha; Battu, Aruna et al. (2013) NER initiation factors, DDB2 and XPC, regulate UV radiation response by recruiting ATR and ATM kinases to DNA damage sites. DNA Repair (Amst) 12:273-83|
|Wang, Qi-En; Han, Chunhua; Zhao, Ran et al. (2013) p38 MAPK- and Akt-mediated p300 phosphorylation regulates its degradation to facilitate nucleotide excision repair. Nucleic Acids Res 41:1722-33|
|Wang, Qi-En; Milum, Keisha; Han, Chunhua et al. (2011) Differential contributory roles of nucleotide excision and homologous recombination repair for enhancing cisplatin sensitivity in human ovarian cancer cells. Mol Cancer 10:24|
|Arafa, El-Shaimaa A; Zhu, Qianzheng; Shah, Zubair I et al. (2011) Thymoquinone up-regulates PTEN expression and induces apoptosis in doxorubicin-resistant human breast cancer cells. Mutat Res 706:28-35|
|Battu, Aruna; Ray, Alo; Wani, Altaf A (2011) ASF1A and ATM regulate H3K56-mediated cell-cycle checkpoint recovery in response to UV irradiation. Nucleic Acids Res 39:7931-45|
|Wang, Qi-En; Han, Chunhua; Milum, Keisha et al. (2011) Stem cell protein Piwil2 modulates chromatin modifications upon cisplatin treatment. Mutat Res 708:59-68|
Showing the most recent 10 out of 29 publications