EBNA3C-mediated regulation of aurora kinase B contributes to Epstein-Barr virus-induced B-cell proliferation through modulation of the activities of the retinoblastoma protein and apoptotic caspases

J Virol. 2013 Nov;87(22):12121-38. doi: 10.1128/JVI.02379-13. Epub 2013 Aug 28.

Abstract

Epstein-Barr virus (EBV) is an oncogenic gammaherpesvirus that is implicated in several human malignancies, including Burkitt's lymphoma (BL), posttransplant lymphoproliferative disease (PTLD), nasopharyngeal carcinoma (NPC), and AIDS-associated lymphomas. Epstein-Barr nuclear antigen 3C (EBNA3C), one of the essential EBV latent antigens, can induce mammalian cell cycle progression through its interaction with cell cycle regulators. Aurora kinase B (AK-B) is important for cell division, and deregulation of AK-B is associated with aneuploidy, incomplete mitotic exit, and cell death. Our present study shows that EBNA3C contributes to upregulation of AK-B transcript levels by enhancing the activity of its promoter. Further, EBNA3C also increased the stability of the AK-B protein, and the presence of EBNA3C leads to reduced ubiquitination of AK-B. Importantly, EBNA3C in association with wild-type AK-B but not with its kinase-dead mutant led to enhanced cell proliferation, and AK-B knockdown can induce nuclear blebbing and cell death. This phenomenon was rescued in the presence of EBNA3C. Knockdown of AK-B resulted in activation of caspase 3 and caspase 9, along with poly(ADP-ribose) polymerase 1 (PARP1) cleavage, which is known to be an important contributor to apoptotic signaling. Importantly, EBNA3C failed to stabilize the kinase-dead mutant of AK-B compared to wild-type AK-B, which suggests a role for the kinase domain in AK-B stabilization and downstream phosphorylation of the cell cycle regulator retinoblastoma protein (Rb). This study demonstrates the functional relevance of AK-B kinase activity in EBNA3C-regulated B-cell proliferation and apoptosis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis*
  • Aurora Kinase B / antagonists & inhibitors
  • Aurora Kinase B / genetics
  • Aurora Kinase B / metabolism*
  • B-Lymphocytes / cytology*
  • B-Lymphocytes / metabolism
  • B-Lymphocytes / virology
  • Blotting, Western
  • Caspases / genetics
  • Caspases / metabolism*
  • Cell Cycle
  • Cell Nucleus / metabolism
  • Cell Proliferation*
  • Chromatin Immunoprecipitation
  • Epstein-Barr Virus Infections / metabolism*
  • Epstein-Barr Virus Infections / pathology
  • Epstein-Barr Virus Infections / virology
  • Epstein-Barr Virus Nuclear Antigens / chemistry
  • Epstein-Barr Virus Nuclear Antigens / genetics
  • Epstein-Barr Virus Nuclear Antigens / metabolism*
  • Fluorescent Antibody Technique
  • Gene Expression Regulation, Enzymologic
  • Herpesvirus 4, Human / pathogenicity*
  • Humans
  • Immunoprecipitation
  • Phosphorylation
  • RNA, Messenger / genetics
  • RNA, Small Interfering / genetics
  • Real-Time Polymerase Chain Reaction
  • Retinoblastoma Protein / genetics
  • Retinoblastoma Protein / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Ubiquitination

Substances

  • Epstein-Barr Virus Nuclear Antigens
  • RNA, Messenger
  • RNA, Small Interfering
  • Retinoblastoma Protein
  • Aurora Kinase B
  • Caspases