PLK1-dependent phosphorylation restrains EBNA2 activity and lymphomagenesis in EBV-infected mice

• Published in: EMBO reports 2021-12, Vol.22 (12), p.e53007-n/a
• Main Authors: Zhang, Xiang, Schuhmachers, Patrick, Mourão, André, Giansanti, Piero, Murer, Anita, Thumann, Sybille, Kuklik-Roos, Cornelia, Beer, Sophie, Hauck, Stefanie M, Hammerschmidt, Wolfgang, Küppers, Ralf, Kuster, Bernhard, Raab, Monika, Strebhardt, Klaus, Sattler, Michael, Münz, Christian, Kempkes, Bettina
• Format: Article
• Language: English
• Subjects: Animals; Antigens; B-cell lymphoma; Binding; Biological activity; B‐lymphomagenesis; Cell Cycle Proteins; Cell immortalization; Cell proliferation; EBNA2; EBV; EMBO03; EMBO23; EMBO37; Epstein-Barr virus; Epstein-Barr Virus Infections - complications; Epstein-Barr Virus Nuclear Antigens - genetics; Epstein-Barr Virus Nuclear Antigens - metabolism; Herpesvirus 4, Human - metabolism; humanized mice; Immortalization; Immunodeficiency; Kinases; Latency; Latent infection; Lymphocytes; Lymphocytes B; Lymphoma; Mice; Mutants; Phosphorylation; PLK1; Polo-Like Kinase 1; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Tumors; Virus Latency
• ISSN: 1469-221X; 1469-3178
• DOI: 10.15252/embr.202153007

While Epstein–Barr virus (EBV) establishes a life-long latent infection in apparently healthy human immunocompetent hosts, immunodeficient individuals are at particular risk to develop lymphoproliferative B-cell malignancies caused by EBV. A key EBV protein is the transcription factor EBV nuclear antigen 2 (EBNA2), which initiates B-cell proliferation. Here, we combine biochemical, cellular, and in vivo experiments demonstrating that the mitotic polo-like kinase 1 (PLK1) binds to EBNA2, phosphorylates its transactivation domain, and thereby inhibits its biological activity. EBNA2 mutants that impair PLK1 binding or prevent EBNA2 phosphorylation are gain-of-function mutants. They exhibit enhanced transactivation capacities, accelerate the proliferation of infected B cells, and promote the development of monoclonal B-cell lymphomas in infected mice. Thus, PLK1 coordinates the activity of EBNA2 to attenuate the risk of tumor incidences in favor of the establishment of latency in the infected but healthy host. SYNOPSIS EBNA2 is a key transactivator that initiates B cell immortalization. PLK1 phosphorylates the C- terminal transactivation domain of EBNA2 to attenuate its oncogenic activities and promote the establishment of long term latency in the infected host. CDK1 phosphorylation of EBNA2 (S379) primes PLK1 binding via its polo box domain (PBD). The PLK1 kinase domain (KD) phosphorylates two residues in the EBNA2 transactivation domain (S457/T465). A second PLK1 binding region within the C-terminus of EBNA2 confers weak CDK1 phosphorylation independent binding. Monoclonal B cell lymphomas more frequently arise in mice infected with EBV mutants expressing either EBNA2 (S379A) or EBNA2 (S457A/T465V) in comparison to EBV wild-type infected mice. Graphical Abstract EBNA2 is a key transactivator that initiates B cell immortalization. PLK1 phosphorylates the C- terminal transactivation domain of EBNA2 to attenuate its oncogenic activities and promote the establishment of long term latency in the infected host.