Polyubiquitination of proliferating cell nuclear antigen by HLTF and SHPRH prevents genomic instability from stalled replication forks
Polyubiquitination of proliferating cell nuclear antigen by HLTF and SHPRH prevents genomic instability from stalled replication forks
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DOI：
10.1073/pnas.0805685105
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发表时间：
2008-08-26
影响因子：
11.1
通讯作者：
Myung, Kyungjae
中科院分区：
文献类型：
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作者：
Motegi, Akira;Liaw, Hung-Jiun;Myung, Kyungjae
由DNA损伤引起的DNA复制叉的慢性停滞可导致基因组不稳定。细胞已经进化出病变旁路途径，如复制后修复（PRR），以解决这些被捕叉。在酵母中，PRR的一个分支涉及由Rad 5-Ubc 13-Mms 2复合物介导的增殖细胞核抗原（PCNA）多聚泛素化，其允许通过模板转换机制绕过DNA损伤。在此之前，我们鉴定了人SHPRH作为酵母Rad 5的功能同源物，并揭示了在人类细胞中存在Rad 5样途径。在这里，我们报告HLTF作为第二个在人类细胞中的RAD 5同源物的鉴定。HLTF与SHPRH一样，与Rad 5共享独特的结构域结构，并促进PCNA的赖氨酸63连接的多聚泛素化。类似于酵母Rad 5，HLTF能够与UBC 13和PCNA以及SHPRH相互作用;并且SHPRH或HLTF表达的减少增强自发突变。此外，HItf缺陷小鼠胚胎成纤维细胞表现出升高的染色体断裂和融合后，甲基甲烷磺酸盐处理。我们的研究结果表明，HLTF和SHPRH是酵母Rad 5的功能同源物，协同介导PCNA聚泛素化并维持基因组稳定性。
Chronic stalling of DNA replication forks caused by DNA damage can lead to genomic instability. Cells have evolved lesion bypass pathways such as postreplication repair (PRR) to resolve these arrested forks. In yeast, one branch of PRR involves proliferating cell nuclear antigen (PCNA) polyubiquitination mediated by the Rad5-Ubc13-Mms2 complex that allows bypass of DNA lesion by a template-switching mechanism. Previously, we identified human SHPRH as a functional homologue of yeast Rad5 and revealed the existence of RAD5-like pathway in human cells. Here we report the identification of HLTF as a second RAD5 homologue in human cells. HLTF, like SHPRH, shares a unique domain architecture with Rad5 and promotes lysine 63-linked polyubiquitination of PCNA. Similar to yeast Rad5, HLTF is able to interact with UBC13 and PCNA, as well as SHPRH; and the reduction of either SHPRH or HLTF expression enhances spontaneous mutagenesis. Moreover, HItf-deficient mouse embryonic fibroblasts show elevated chromosome breaks and fusions after methyl methane sulfonate treatment. Our results suggest that HLTF and SHPRH are functional homologues of yeast Rad5 that cooperatively mediate PCNA polyubiquitination and maintain genomic stability.