Project 3: Fanconi Anemia and Repair of DNA-Protein Crosslinks

项目摘要 范可尼贫血（FA）是一种由DNA损伤修复缺陷引起的隐性遗传性疾病。FA患者表现出 再生障碍性贫血、先天性畸形和癌症发生率的显著升高。来自FA的细胞 患者对DNA交联剂过敏，对染色体断裂高度敏感 基因毒性压力下。迄今为止，17个常染色体和1个X连锁基因被指定为致病基因， FA，但FA途径的分子结构仍然很大程度上不清楚。缺乏明确的遗传模型 系统和缺乏可识别的蛋白质结构域在大多数FA蛋白是其中的主要障碍 阻碍了FA生物学的发展。最近在尼斯进行的遗传学研究揭示了FA与 途径和醛代谢和牵连的DNA-蛋白质交联（DPC）作为一种生理 相关内源性病变。许多DNA链间交联（ICL）剂，如醛和顺铂， 也能诱导DPC。电离辐射和紫外线照射也会产生大量的核DPC。因此，我们认为， DPC是一种重要的DNA损伤类型。由于DPC和ICL都是DNA的强障碍物， 一组哺乳动物DNA修复突变体表现出共同的ICL和DPC敏感性， 这两种类型病变的修复在利用病变旁路时可能具有相似的分子机制 合成、核苷酸切除修复和FA途径组分。项目3的主要目的是研究 细胞如何通过蛋白水解和溶核机制修复DPC，并确定 FA通路功能与可能由基因转录产生的内源性DPC之间的关系 重新编程这些目标将通过两个具体目标来实现：（1）确定因素和途径 参与DPC修复和（2）定义FA途径在对抗内源性DNA交联中的功能 病变阐明DPC修复机制将解决DNA修复生物学中的关键知识缺口。 这也可能揭示FA患者造血表现的潜在机制。英足总 途径主要在解决复制叉阻断DNA损伤中起作用。这种类型的病变是典型的 通过DNA交联，最常由双功能烷基化化疗方式产生，例如 顺铂和美法仑，以及电离辐射高频率产生的DNA-蛋白质交联 exposure.例如，许多卵巢癌对顺铂治疗的临床反应由其FA决定 路径状态。总之，本项目旨在阐明肝硬化的分子病理机制， 范可尼贫血的直接好处是发现新的治疗靶点，以改善癌症 治疗结果。

PROJECT SUMMARY Fanconi anemia (FA) is a recessive disorder caused by deficient DNA damage repair. FA patients exhibit aplastic anemia, congenital abnormalities, and profoundly elevated cancer occurrence. Cells derived from FA patients are hypersensitivity to DNA crosslinking agents and highly susceptible to chromosome breakage under genotoxic stress. To date, 17 autosomal and 1 X-linked genes are designated as causative genes for FA, but the molecular structure of the FA pathway remains largely unclear. Lack of defined genetic model systems and a scarcity of recognizable protein domains in most FA proteins are among the major obstacles impeding the advance of FA biology. Recent genetic studies in nice revealed an intriguing link between the FA pathways and aldehyde metabolism and implicated DNA-protein crosslinks (DPCs) as a physiologically relevant endogenous lesion. Many DNA interstrand crosslinking (ICL) agents, such as aldehydes and cisplatin, also induce DPCs. Ionizing radiation and UV exposure also generate abundant nuclear DPCs. Therefore, DPCs is a significant type of DNA damage. Given that DPCs and ICLs are both strong obstacles of DNA transactions and that a cohort of mammalian DNA repair mutants exhibit shared ICL and DPC sensitivities, it is likely that repair of these two types of lesions assumes similar molecular mechanisms in utilizing lesion bypass synthesis, nucleotide excision repair, and FA pathway components. The main objective of Project 3 is to study how cells repair DPCs via a combined proteolytic and nucleolytic mechanisms and to determine the link between FA pathway function and endogenous DPCs potentially arisen from gene transcription reprogramming. These objectives will be achieved with two specific aims: (1) Define factors and pathways involved in DPC repair and (2) Define FA pathway function in countering endogenous DNA-crosslinking lesions. Elucidation of the DPC repair mechanism will address a critical knowledge gap in DNA repair biology. It may also reveal the underlying mechanism of the hematopoietic manifestation of FA patients. The FA pathway functions primarily in resolving replication fork-blocking DNA lesions. This type of lesion is exemplified by DNA crosslinks most frequently generated by bifunctional alkylating chemotherapeutic modalities, such as cisplatin and melphalan, and by DNA-protein crosslinks produced with high frequency from ionizing radiation exposure. For example, clinical response of many ovarian cancers to cisplatin treatment is dictated by their FA pathway status. In summary, this project is aimed at delineating the molecular pathological mechanism of Fanconi anemia with the immediate benefit of uncovering novel therapeutic targets to improve cancer treatment outcomes.