EBP2 Plays a Key Role in Epstein-Barr Virus Mitotic Segregation and Is Regulated by Aurora Family Kinases

Abstract

Epstein-Barr virus (EBV) genomes persist indefinitely in latently infected human cells, in part due to their ability to stably segregate during cell division. This process is mediated by the viral EBNA1 protein, which tethers the viral episomes to the cellular mitotic chromosomes. We have previously identified a mitotic chromosomal protein, human EBNA1 binding protein 2 (hEBP2), which binds to EBNA1 and enables EBNA1 to partition EBV-based plasmids in Saccharomyces cerevisiae. Using an RNA silencing approach, we show that hEBP2 is essential for the proliferation of human cells and that repression of hEBP2 severely decreases the ability of EBNA1 and EBV-based plasmids to bind mitotic chromosomes. When expressed in yeast, hEBP2 undergoes the same cell cycle-regulated association with the mitotic chromatin as in human cells, and using yeast temperature-sensitive mutant strains, we found that the attachment of hEBP2 to mitotic chromosomes was dependent on the Ipl1 kinase. Both RNA silencing of the Ipl1 orthologue in human cells (Aurora B) and specific inhibition of the Aurora B kinase activity with a small molecule confirmed a role for this kinase in enabling hEBP2 binding to human mitotic chromosomes, suggesting that this kinase can regulate EBV segregation.

ACKNOWLEDGMENTS

We thank Mark Grunstein for yeast strains expressing histone H3 tail mutants, Lo Kwak Wai and Fei-fei Lui for C666-1 cells, and AstraZeneca UK Limited for ZM447439.

This work was supported by grants from the Canadian Institutes of Health Research to L.F and B.D.L. P.K. is a research student of the National Cancer Institute of Canada, supported with funds provided by the Terry Fox run. L.F. is a Canada Research Chair in Molecular Virology, and B.D.L is a CIHR New Investigator.