范可尼贫血（Fanconi Anemia）基因FANCM在复制后修复中的作用及FA癌症抑制通路的机制研究

Fanconi Anemia pathway and other cancer suppressing pathways form a complicate network to regulate DNA repair and recombination. FANCM, the most conserved one among all the 14 FA proteins, and other seven FA members form the FA core complex，which has the E3 ubiquitination activity and initiate DNA damage repair by mono-ubiquitinating FANCD2 and FANCI. FANCM was found to catalyse branch migration of model Holliday Junctions and replication fork reversal in vitro. From the study of its fission yeast ortholog Fml1, we also learn that Fml1 has at least two roles in homologous recombination repair: promotes Rad51-dependent gene conversion at stalled/blocked replication forks and limits crossing over during mitotic double-strand break repair. Base on these observations, we plan to use HEK293 cell line as our model system, and develop a system base on the episomal replication-based Chromatin IP to investigate FANCM accumulation at interstrand crosslink sites via a time course. We aim to find in vivo evidences for FANCM's activities in catalysing replication fork reversal and D-loop disruption. Therefore, we can further clarify the mechanism of the FA tumor suppressing pathway.

范可尼贫血通路与多种抑癌通路（如乳腺癌BRAC）构成网络对DNA复制和细胞修复过程进行调控。其中FANCM和另外七个蛋白构成了FA核心复合体，具有E3泛素连接酶活性，能够泛素化FANCI和FANCD2。从而起始修复并将修复途径分别导向无错途径的同源重组和容错途径的跨损伤修复。FANCM可以催化同源重组Holliday交叉和复制叉的分支迁移。裂殖酵母中FANCM同系物Fml1在重组修复中的功能有：1）在暂停的复制叉损伤处促进Rad51依赖的基因转化；2）在体细胞DNA双链断裂修复过程中限制片段交换的产生。本课题利用HEK293细胞系为模型，转入特定载体，把限制性内切酶位点多态性引入底物，以eChIP技术实时追踪FANCM在交联修复中的变迁，阐释FANCM在催化复制叉反转和解构D环的作用机制以进一步明确FA通路的作用原理。

FA抑癌通路对DNA无错修复过程及多种复制后修复过程进行调控，并与BRAC等抑癌通路交互作用形成网络。FANCM等17个蛋白构成了FA核心复合体，具有E3泛素连接酶活性，能够泛素化FANCI和FANCD2。从而起始修复并将修复途径分别导向无错途径的同源重组和容错途径的跨损伤修复。FANCM可以催化同源重组Holliday交叉和复制叉的分支迁移。本课题利用人骨髓间充质干细胞为模型，发现FANCM水平在干细胞衰老过程中升高，并通过进一步研究FANCM与ZMPSTE24等蛋白的互作研究FANCM在干细胞衰老过程中的作用。

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