Cellular Corepressor TLE2 Inhibits Replication-and-Transcription-Activator-Mediated Transactivation and Lytic Reactivation of Kaposi's Sarcoma-Associated Herpesvirus
Cellular Corepressor TLE2 Inhibits Replication-and-Transcription-Activator-Mediated Transactivation and Lytic Reactivation of Kaposi's Sarcoma-Associated Herpesvirus
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细胞辅阻遏物 TLE2 抑制卡波西肉瘤相关疱疹病毒的复制和转录激活剂介导的反式激活和裂解再激活
DOI：
10.1128/jvi.01984-09
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发表时间：
2010-02-15
影响因子：
5.4
通讯作者：
Lan, Ke
中科院分区：
文献类型：
--
作者：
He, Zhiheng;Liu, Yunhua;Lan, Ke
卡波西肉瘤相关疱疹病毒(KSHV)开放阅读框50(ORF50)编码的复制和转录激活因子(RTA)是启动裂解再激活的必要条件和充分条件。RTA通过与其反应元件高亲和力的直接结合或与细胞因子如RBP-J kappa、AP-1、C/EBP-α和Oct-1的相互作用来激活其靶基因。在本研究中，我们通过酵母双杂交筛选人脾cDNA文库，鉴定出一种新的RTA结合蛋白--转导素样增强子2。谷胱甘肽S转移酶结合实验和免疫共沉淀实验证实了Tle2与Rta的相互作用。免疫荧光分析表明，在KSHV感染的细胞中，TLE2和RTA共定位于同一核室。这种相互作用将TLE2招募到与DNA上的识别位点结合的RTA，并抑制了RTA的自激活和反激活活性。此外，TLE2还抑制了RTA诱导的裂解复制和病毒粒子的产生。我们进一步表明，TLE2的Q(富含Gln)、SP(Ser-Pro-Rich)和WDR(Trp-Asp Repeat)结构域以及RTA的Pro富含结构域是这种相互作用所必需的。RBP-J kappa以前已经被证明与RTA的同一个富含Pro结构域结合，这种结合可以受到TLE2的竞争。此外，TLE2可以与RTA形成复合体，以获得不同启动子上RTA反应元件的同源DNA序列。有趣的是，在裂解再激活过程中，TLE2的转录水平可以被RTA上调。总之，我们鉴定了一种新的RTA结合蛋白TLE2，并证明了TLE2抑制了RTA介导的复制和反式激活。这为通过与宿主蛋白相互作用来维持KSHV病毒潜伏期提供了另一种潜在的重要机制。
Replication and transcription activator (RTA) encoded by open reading frame 50 (ORF50) of Kaposi's sarcoma-associated herpesvirus (KSHV) is essential and sufficient to initiate lytic reactivation. RTA activates its target genes through direct binding with high affinity to its responsive elements or by interaction with cellular factors, such as RBP-J kappa, Ap-1, C/EBP-alpha, and Oct-1. In this study, we identified transducin-like enhancer of split 2 (TLE2) as a novel RTA binding protein by using yeast two-hybrid screening of a human spleen cDNA library. The interaction between TLE2 and RTA was confirmed by glutathione S-transferase (GST) binding and coimmunoprecipitation assays. Immunofluorescence analysis showed that TLE2 and RTA were colocalized in the same nuclear compartment in KSHV-infected cells. This interaction recruited TLE2 to RTA bound to its recognition sites on DNA and repressed RTA auto-activation and transactivation activity. Moreover, TLE2 also inhibited the induction of lytic replication and virion production driven by RTA. We further showed that the Q (Gln-rich), SP (Ser-Pro-rich), and WDR (Trp-Asp repeat) domains of TLE2 and the Pro-rich domain of RTA were essential for this interaction. RBP-J kappa has been shown previously to bind to the same Pro-rich domain of RTA, and this binding can be subject to competition by TLE2. In addition, TLE2 can form a complex with RTA to access the cognate DNA sequence of the RTA-responsive element at different promoters. Intriguingly, the transcription level of TLE2 could be upregulated by RTA during the lytic reactivation process. In conclusion, we identified a new RTA binding protein, TLE2, and demonstrated that TLE2 inhibited replication and transactivation mediated by RTA. This provides another potentially important mechanism for maintenance of KSHV viral latency through interaction with a host protein.