组蛋白去泛素化酶USP11在DNA双链断裂损伤修复中的转录调控作用及其影响肿瘤发生的机制

DNA双链断裂是危险程度极高的损伤，最终会导致肿瘤发生，破坏基因组的完整性和稳定性。已有报道大都专注于修复期的级联反应，修复后期如何恢复稳态及其转录调控机制如何尚不清晰。申请人前期发现组蛋白去泛素化酶USP11与NuRD形成复合体，参与DNA损伤反应后期，通过发挥H2AK119和H2BK120去泛素化、H3去乙酰化的协同作用，使染色质结构恢复，维持基因组稳定性。本项目预实验显示，USP11对上述修饰在不同基因组区域的富集水平有影响。.本项目的目标是探究USP11/NuRD复合体在DNA双链断裂损伤反应后期的转录调控机制，从而阐释该阶段转录水平如何恢复。利用分子、细胞、动物水平的多种技术方法，深入探究USP11/NuRD复合体在损伤修复中调控的靶基因及下游通路；以USP11或下游分子为靶点，探究DNA损伤后该通路对肿瘤发生的影响，为肿瘤的临床治疗提供新的思路。

Eukaryotic cells evolve highly efficient DNA repair system to guide the integrity of the genome in response to a plethora of exogenous as well as endogenous DNA insults. DNA double-strand breaks (DSBs), which are exceedingly dangerous chromosomal lesions as they entail physical cleavage of the DNA backbone, unrepaired or misrepaired DNA damages can cause gross chromosome rearrangements or mutations at break sites, eventually leading to tumorigenesis. Most of reports focus on the cascade reaction in response to DNA damage, however, restoration during the late stage of DNA repair and the mechanism of its transcriptional regulation is still unclear. We have reported that USP11 acts as a histone deubiquitinase to catalyze H2AK119 and H2BK120 deubiquitination. We showed that USP11 is physically associated with the chromatin remodeling NuRD complex and functionally involved in DNA repair process. We demonstrated that USP11-mediated histone deubiquitination and NuRD-associated histone deacetylation coordinate to allow timely termination of DNA repair and reorganization of the chromatin structure. Our previous work shows that USP11 has an effect on the enrichment of H2AK119ub, H2BK120ub and H3ac levels in different genomic regions. ..The goal of this research is to explore the mechanism of transcriptional regulation in the late stage of DSB, and to improve the transcriptional regulation role of USP11/NuRD complex, so as to explain how the transcription level can be restored. In this research, we will employ ChIP-seq to analyze the transcriptional regulation during DSB, and the target genes as well as downstream pathways regulated by the USP11/NuRD complex during DNA repair. Then, variety of method from molecular, cellular and animal levels will be used for exploration of the role of this pathway. By explaining USP11 as a key protein, functionally linked to efficient DNA repair, targeting USP11 or its downstream, explore its influence on tumorigenesis, which can provide new ideas for the clinical treatment of tumors.