TORC2, a coactivator of cAMP-response element-binding protein, promotes Epstein-Barr virus reactivation from latency through interaction with viral BZLF1 protein

Takayuki Murata, Yoshitaka Sato, Sanae Nakayama, Ayumi Kudoh, Satoko Iwahori, Hiroki Isomura, Masako Tajima, Takayuki Hishiki, Takayuki Ohshima, Makoto Hijikata, Kunitada Shimotohno, Tatsuya Tsurumi

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)8033-8041
Number of pages9
JournalJournal of Biological Chemistry
Volume284
Issue number12
DOIs
Publication statusPublished - 20-03-2009
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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