Cell-specific regulation of immediate early gene BZLF1 in Epstein-Barr Virus under mTOR inhibition

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Jason M. Needham (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site: http://library.uncg.edu/
Amy Adamson

Abstract: Epstein-Barr Virus (EBV) is a nearly ubiquitous human herpesvirus which infects epithelial cells and B-lymphocytes. Additionally, long-term EBV latency has been associated with various forms of cancers including Burkitt’s lymphoma, nasopharyngeal carcinoma, and gastric carcinoma. Rapamycin, an mTORC1 inhibitor, has been demonstrated to suppress expression of the immediate-early gene BZLF1 and subsequent lytic replication in B-lymphocytes. Paradoxically, mTOR inhibition has also been reported to increase BZLF1 levels and lytic replication in epithelial cells. In order to identify possible mechanisms for this cell-specific response, a luciferase reporter assay using the BZLF1 promoter was performed in AGS-BX1 epithelial cells under mTOR inhibition. It was found that the removal of terminal YY1-binding domains resulted in the loss of rapamycin-sensitivity of BZLF1 transcription in AGS-BX1 cells. Furthermore, while YY1 was observed to localize to the nucleus of rapamycin-treated Raji B-lymphocytes, little change was observed in YY1 localization in AGS-BX1 cells. These results, in conjunction with those of the luciferase assay, suggest YY1 may play an activating role of BZLF1 transcription in epithelial cells under mTOR inhibition while repressing viral transcription in B-lymphocytes. To test this hypothesis, both AGS-BX1 cells and Raji cells were subject to YY1 knockdown using RNAi transfection and compared using Western Blotting. BZLF1 protein levels under mTOR inhibition in YY1-knockdown AGS-BX1 cells were decreased, while significantly increased in the B-lymphocytes under the same inhibition. These results suggest that YY1, as regulated by the mTOR pathway, may play an important role in the activation of the lytic cycle of EBV in epithelial cells, while simultaneously acting as a repressor to lytic replication in B-lymphocytes.

Additional Information

Language: English
Date: 2016
BZLF1, Epstein-Barr Virus, mTOR, YY1
Epstein-Barr virus

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