Nucleolar localization and dynamic roles of flap endonuclease 1 in ribosomal DNA replication and damage repair
Nucleolar localization and dynamic roles of flap endonuclease 1 in ribosomal DNA replication and damage repair
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DOI：
10.1128/mcb.00200-08
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发表时间：
2008-07-01
影响因子：
5.3
通讯作者：
Shen, Binghui
中科院分区：
文献类型：
--
作者：
Guo, Zhigang;Qian, Limin;Shen, Binghui
尽管有丰富的信息提供的生化功能和我们最近的发现，其在基因组稳定性和癌症避免的结构特异性皮瓣核酸内切酶1（FEN 1）的作用，其细胞区室化和动力学相应的参与各种DNA代谢途径尚未阐明。几年前，我们证明了FEN 1在DNA损伤和某些细胞周期条件下迁移到细胞核中。在目前的论文中，我们发现FEN 1在核仁中超积累，并在解决在天然复制叉屏障位点形成的停滞DNA复制叉中发挥作用。响应于UV照射和磷酸化，FEN 1迁移到核血浆中参与DNA上LTV交联的解析，最有可能利用其核酸外切酶和缺口依赖性核酸内切酶活性的协同作用。基于酵母互补实验，Ser（187）Asp的突变模拟恒定磷酸化，将FEN 1排除在核仁积累之外。Ser（187）被Ala取代，消除了唯一的磷酸化位点，使FEN 1保留在核仁中。这两种突变都导致LTV敏感性，损害细胞UV损伤修复能力，并降低整体细胞存活率。
Despite the wealth of information available on the biochemical functions and our recent findings of its roles in genome stability and cancer avoidance of the structure-specific flap endonuclease 1 (FEN1), its cellular compartmentalization and dynamics corresponding to its involvement in various DNA metabolic pathways are not yet elucidated. Several years ago, we demonstrated that FEN1 migrates into the nucleus in response to DNA damage and under certain cell cycle conditions. In the current paper, we found that FEN1 is superaccumulated in the nucleolus and plays a role in the resolution of stalled DNA replication forks formed at the sites of natural replication fork barriers. In response to UV irradiation and upon phosphorylation, FEN1 migrates to nuclear plasma to participate in the resolution of LTV cross-links on DNA, most likely employing its concerted action of exonuclease and gap-dependent endonuclease activities. Based on yeast complementation experiments, the mutation of Ser(187)Asp, mimicking constant phosphorylation, excludes FEN1 from nucleolar accumulation. The replacement of Ser(187) by Ala, eliminating the only phosphorylation site, retains FEN1 in nucleoli. Both of the mutations cause LTV sensitivity, impair cellular UV damage repair capacity, and decline overall cellular survivorship.