Relationship between retroviral DNA-integration-site selection and host cell transcription.
Relationship between retroviral DNA-integration-site selection and host cell transcription.
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逆转录病毒 DNA 整合位点选择与宿主细胞转录之间的关系。
DOI：
10.1073/pnas.0409204102
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发表时间：
2005
影响因子：
11.1
通讯作者：
Coffin,JohnM
中科院分区：
文献类型：
--
作者：
Maxfield,LoriF;Fraize,CamillaD;Coffin,JohnM
逆转录病毒DNA整合发生在整个基因组中;然而，存在局部“热点”，其中看到对某些位点的强烈偏好超过其他位点，并且已经报道了与基因相关的更多全局偏好。我们实验室以前的数据表明，当DNA模板进行活性转录时，与不进行活性转录时相比，整合到DNA模板中的事件较少。因为这些数据是通过使用稳定转染的外源基因，只有弱诱导，我们已经扩展了这一观察结果，通过比较整合事件到一个高度诱导的内源基因下诱导和未诱导的转录状态。为了直接研究转录对位点选择的影响，我们分析了鸟类逆转录病毒DNA整合到金属硫蛋白基因中的频率和分布，在其诱导到高度持续的表达水平之前和之后，通过加入硫酸锌。我们发现在100倍的转录诱导后整合事件减少了6倍。这一结果意味着，尽管逆转录病毒DNA整合到宿主DNA的转录区域的明显偏好，高水平的转录可以抑制整合过程。我们观察到的几种可能的模型如下。首先，当DNA模板进行活性转录时，由于空间位阻，整合可能被RNA聚合酶II复合物阻断。或者，整合酶复合物可能需要DNA处于双链构象，这在主动转录期间不是这种情况。最后，转录可能导致染色质重塑为不利于整合的结构。
Retroviral DNA integration occurs throughout the genome; however, local “hot spots” exist where a strong preference for certain sites over others are seen, and more global preferences associated with genes have been reported. Previous data from our laboratory suggested that there are fewer integration events into a DNA template when it is undergoing active transcription than when it is not. Because these data were generated by using a stably transfected foreign gene that was only weakly inducible, we have extended this observation by comparing integration events into a highly inducible endogenous gene under both induced and uninduced transcriptional states. To examine the influence of transcription on site selection directly, we analyzed the frequency and distribution of integration of avian retrovirus DNA into the metallothionein gene, before and after its induction to a highly sustained level of expression by addition of ZnSO4. We found a 6-fold reduction in integration events after 100-fold induction of transcription. This result implies that, despite an apparent preference for integration of retroviral DNA into transcribed regions of host DNA, high-level transcription can be inhibitory to the integration process. Several possible models for our observation are as follows. First, when a DNA template is undergoing active transcription, integration might be blocked by the RNA polymerase II complex because of steric hindrance. Alternatively, the integrase complex may require DNA to be in a double-stranded conformation, which would not be the case during active transcription. Last, transcription might lead to remodeling of chromatin into a structure that is less favorable for integration.