Roles of host cell factors in circularization of retroviral DNA
Roles of host cell factors in circularization of retroviral DNA
复制标题
DOI：
10.1016/s0042-6822(03)00455-0
复制
发表时间：
2003-09-15
期刊：
影响因子：
3.7
通讯作者：
Bushman, FD
中科院分区：
文献类型：
--
作者：
Kilzer, JM;Stracker, T;Bushman, FD
在逆转录病毒感染的早期，线性逆转录病毒DNA基因组的一部分被细胞酶循环，从而使基因组失活，以便进一步复制。突出的环状DNA形式包括由DNA末端连接形成的2-长端重复序列(LTR)环，以及部分由同源重组产生的1-LTR环。这些反应为分析脊椎动物细胞中DNA末端连接所涉及的细胞机制提供了一个方便的范例。在以前的研究中，我们发现非同源DNA末端连接(NHEJ)途径的失活成分-特别是Ku、连接酶4或XRCC4-阻止2-LTR环的形成。在这里，我们报告了失活另一个NHEJ成分，DNA依赖的蛋白激酶催化亚单位(DNA-PKcs)，至多对2-LTR环的形成有轻微的影响，提供了与其他末端连接反应相似的信息。我们还分析了突变的细胞的Rad50/Mre11/NBS1核酸酶的组成，发现1-LTR环的相对数量减少，与NHEJ突变的影响相反。在Mre11突变细胞中，位于核酸酶催化位点的Mre11基因突变未能恢复1-LTR环的形成，支持Mre11在1-LTR环形成中的作用模型。没有一个细胞突变表现出对正常整合的强烈影响，这与导致循环的细胞通路不参与生产性整合的观点一致。(C)2003 Elsevier Inc.保留所有权利。
Early during retroviral infection, a fraction of the linear reverse-transcribed viral DNA genomes become circularized by cellular enzymes, thereby inactivating the genomes for further replication. Prominent circular DNA forms include 2-long-terminal repeat (LTR) circles, made by DNA end joining, and 1-LTR circles, produced in part by homologous recombination. These reactions provide a convenient paradigm for analyzing the cellular machinery involved in DNA end joining in vertebrate cells. In previous studies, we found that inactivating components of the nonhomologous DNA end-joining (NHEJ) pathway-specifically Ku, ligase 4, or XRCC4-blocked formation of 2-LTR circles. Here we report that inactivating another NHEJ component, the DNA-dependent protein kinase catalytic subunit (DNA-PKcs), had at most modest effects on 2-LTR circle formation, providing informative parallels with other end-joining reactions. We also analyzed cells mutant in components of the RAD50/MRE11/NBS1 nuclease and found a decrease in the relative amount of 1-LTR circles, opposite to the effects of NHEJ mutants. In MRE11-mutant cells, a MRE11 gene mutant in the nuclease catalytic site failed to restore 1-LTR circle formation, supporting a model for the role of MRE11 in 1-LTR circle formation. None of the cellular mutations showed a strong effect on normal integration, consistent with the idea that the cellular pathways leading to circularization are not involved in productive integration. (C) 2003 Elsevier Inc. All rights reserved.