Genetic Framework and Molecular Mechanism of Fanconi Anemia

项目摘要 Fanconi贫血(FA)是一种由于DNA损伤修复不足而引起的隐性疾病。FA 患者表现为再生障碍性贫血、先天畸形和严重的癌症。 发生了。FA患者来源的细胞对DNA交联剂和 在基因毒性压力下极易发生染色体断裂。到目前为止，有15个常染色体和 1个X连锁基因被认为是FA的致病基因，但其分子结构 FA途径在很大程度上仍不清楚。缺乏明确的遗传模型系统，缺乏 大多数FA蛋白中可识别的蛋白质结构域是阻碍 FA生物学研究进展。这项提议的主要目标是建立遗传框架 研究FA途径，阐明FA关键蛋白的分子功能。我们开始 通过系统构建体细胞基因敲除模型来解决这些问题。我们的 初步研究暗示了一种假设，即不同的FA蛋白形成不同的 完成DNA损伤诱导的FA途径激活的功能模块，其中 使DNA损伤处理酶得以重新招募。我们计划检验这一假设 具体目标有三个：(1)确定经典FA基因产物之间的上位关系， 这将缓解范科尼贫血基因之间明显的遗传联系空白。(2) 解剖含有多个FA的FA核心E3连接酶复合体的功能整合 功能未知的蛋白质。(3)确定DNA-蛋白质交联链是否普遍存在 内源性损伤由FA途径处理。对FA途径的阐明应该有 对促进对基本细胞机制的理解产生重大影响 保护基因组的完整性。更重要的是，FA途径组件是潜在的靶点 治疗性干预。FA途径主要作用于解决复制分叉-- 阻止DNA损伤。这种类型的损伤最常见的例子是DNA交联。 由双功能烷基化化疗方案产生，如顺铂和马法兰， 由电离辐射产生的高频DNA-蛋白质交联物引起。 例如，许多卵巢癌对顺铂治疗的临床反应取决于它们的 FA途径状态。综上所述，本项目的目的是描绘分子病理学。 范可尼贫血的机制及其发现新疗法的直接好处 旨在改善癌症治疗结果的目标。

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, 15 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. The main objective of this proposal is to establish the genetic framework of the FA pathway and to elucidate molecular functions of key FA proteins. We begin to approach these problems by systematically constructing somatic cellular knockout models. Our preliminary investigations insinuate a hypothesis that different FA proteins form distinct functional modules to accomplish the DNA damage-induced FA pathway activation, which enables the recruitment of DNA damage-processing enzymes. We plan to test this hypothesis with three specific aims: (1) Define the epistatic relationships among classic FA gene products, which will mitigate a visible void in genetic connections among Fanconi anemia genes. (2) Dissect the functional integration of the FA core E3 ligase complex which contains several FA proteins with unknown functions. (3) Determine whether DNA-protein crosslinks are prevalent endogenous lesions processed by the FA pathway. Elucidation of the FA pathway should have a significant impact in advancing the understanding of fundamental cellular mechanisms protecting genome integrity. More importantly, FA pathway components are potential target for therapeutic intervention. The FA pathway functions primarily in resolving replication fork- blocking DNA lesions. This type of lesions is exemplified by DNA crosslinks most frequently generated by bifunctional alkylating chemotherapeutic modalities, such 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 the improve cancer treatment outcomes.