TORC2, a Coactivator of cAMP-response Element-binding Protein, Promotes Epstein-Barr Virus Reactivation from Latency through Interaction with Viral BZLF1 Protein
TORC2, a Coactivator of cAMP-response Element-binding Protein, Promotes Epstein-Barr Virus Reactivation from Latency through Interaction with Viral BZLF1 Protein
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DOI：
10.1074/jbc.m808466200
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发表时间：
2009-03-20
影响因子：
4.8
通讯作者：
Tsurumi, Tatsuya
中科院分区：
文献类型：
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作者：
Murata, Takayuki;Sato, Yoshitaka;Tsurumi, Tatsuya
Epstein-Barr 病毒从潜伏期的重新激活取决于病毒 BZLF1 蛋白的表达。 BZLF1 启动子 (Zp) 通常仅表现出较低的基础活性，但会响应化学诱导剂（例如 12-O-十四烷酰佛波醇-13-乙酸酯和钙离子载体）而被激活。我们在此发现，与 BZLF1 蛋白共表达时，调节 cAMP 响应元件结合蛋白 (CREB) (TORC) 2 的转导器可将 Zp 活性增强 10 倍和 100 倍以上。 Zp 的突变分析表明，TORC 的激活分别依赖于 ZII 和 ZIII 顺式元件、CREB 家族转录因子和 BZLF1 蛋白的结合位点。使用 Gal4-luc 和 Gal4BD-BZLF1 融合蛋白的免疫沉淀、染色质免疫沉淀和报告基因检测表明 TORC2 与 BZLF1 相互作用，并且该复合物被有效地募集到 Zp 上。这些观察结果清楚地表明 TORC2 通过与 BZLF1 蛋白以及 CREB 家族转录因子相互作用来激活启动子。裂解复制的诱导导致TORC2从细胞质易位到细胞核中的病毒复制区室，此外，TORC2对Zp的激活被钙调节磷酸酶、钙调神经磷酸酶增强。通过 RNA 干扰沉默内源 TORC2 基因表达，降低了响应 12-O-tetradecanoylphorbol-13-acetate/ionophore 的 BZLF1 蛋白水平。基于这些结果，我们得出结论，Epstein-Barr 病毒通过 TORC 和 BZLF1 蛋白之间的相互作用利用钙调神经磷酸酶-TORC 信号通路从潜伏期重新激活。
Reactivation of the Epstein-Barr virus from latency is dependent on expression of the viral BZLF1 protein. The BZLF1 promoter (Zp) normally exhibits only low basal activity but is activated in response to chemical inducers such as 12-O-tetradecanoylphorbol-13-acetate and calcium ionophore. We found here that Transducer of Regulated cAMP-response Element-binding Protein (CREB) (TORC) 2 enhances Zp activity 10-fold and more than 100-fold with co-expression of the BZLF1 protein. Mutational analysis of Zp revealed that the activation by TORC is dependent on ZII and ZIII cis elements, binding sites for CREB family transcriptional factors and the BZLF1 protein, respectively. Immunoprecipitation, chromatin immunoprecipitation, and reporter assay using Gal4-luc and Gal4BD-BZLF1 fusion protein indicate that TORC2 interacts with BZLF1, and that the complex is efficiently recruited onto Zp. These observations clearly indicate that TORC2 activates the promoter through interaction with the BZLF1 protein as well as CREB family transcriptional factors. Induction of the lytic replication resulted in the translocation of TORC2 from cytoplasm to viral replication compartments in nuclei, and furthermore, activation of Zp by TORC2 was augmented by calcium-regulated phosphatase, calcineurin. Silencing of endogenous TORC2 gene expression by RNA interference decreased the levels of the BZLF1 protein in response to 12-O-tetradecanoylphorbol-13-acetate/ionophore. Based on these results, we conclude that Epstein-Barr virus exploits the calcineurin-TORC signaling pathway through interactions between TORC and the BZLF1 protein in reactivation from latency.