去泛素化酶OTUD4调节DNA甲基化损伤修复的机制研究

DNA甲基化损伤修复对正常细胞的基因组至关重要，因为这种损伤将导致细胞毒性和潜在突变。细胞存在至少三种甲基化修复途径：①去甲基化修复；②直接修复；③碱基切除修复。去甲基化酶ALKBH2和ALKBH3介导去甲基化修复途径；甲基转移酶MGMT介导直接修复途径。某些肿瘤高表达，并依赖特定的甲基化修复酶抵抗烷基化药物化疗。如果这些修复酶被抑制或降解，癌细胞将重新对化疗药物敏感。虽然我们对这些修复酶的功能已有所了解，但对其蛋白调控方式仍然知之甚少。本项目将基于申请人的工作基础，系统研究：1）ALKBH2、ALKBH3和MGMT的泛素化调控机制，鉴定其泛素化位点和E3泛素连接酶；2）去泛素化酶OTUD4作为“核心酶”，偶联和调控多种甲基化修复酶的分子机制。本项目预期的研究结果，或能揭示多种甲基化修复酶在某些肿瘤中高表达、帮助癌细胞抵抗烷基化药物化疗的作用机制。

Repair of DNA methylation damage to the genome is critical in all cells, because such damage is cytotoxic and potentially mutagenic. At least three different pathways have been shown to repair such damage, including demethylation by the AlkB family of enzymes, direct reversal by methylguanine methyltransferase（MGMT）, and base-excision repair (BER). While the enzymatic activity of these proteins is generally well understood, their regulation and function, particularly in tumor cells, remain poorly understood. Our recent studies characterized a human Demethylase-Deubiquitinase Complex that functions primarily in certain tumors, particularly prostate adenocarcinoma. In this work, we will characterize the regulation of three DNA methylation repair enzymes (ALKBH2, ALKBH3, and MGMT) by ubiquitination. We will also further characterize the deubiquitinase, OTUD4, which could be a potential targeted therapy option for certain cancers.