Latency-Associated Nuclear Antigen E3 Ubiquitin Ligase Activity Impacts Gammaherpesvirus-Driven Germinal Center B Cell Proliferation.
Viruses have evolved mechanisms to hijack components of cellular E3 ubiquitin ligases, thus modulating the ubiquitination pathway. However, the biological relevance of such mechanisms for viral pathogenesis in vivo remains largely unknown. Here, we utilized murid herpesvirus 4 (MuHV-4) infection of mice as a model system to address the role of MuHV-4 latency-associated nuclear antigen (mLANA) E3 ligase activity in gammaherpesvirus latent infection. We show that specific mutations in the mLANA SOCS box (V199A, V199A/L202A, or P203A/P206A) disrupted mLANA's ability to recruit Elongin C and Cullin 5, thereby impairing the formation of the Elongin BC/Cullin 5/SOCS (EC5S(mLANA)) complex and mLANA's E3 ligase activity on host NF-κB and Myc. Although these mutations resulted in considerably reduced mLANA binding to viral terminal repeat DNA as assessed by electrophoretic mobility shift assay (EMSA), the mutations did not disrupt mLANA's ability to mediate episome persistence. In vivo, MuHV-4 recombinant viruses bearing these mLANA SOCS box mutations exhibited a deficit in latency amplification in germinal center (GC) B cells. These findings demonstrate that the E3 ligase activity of mLANA contributes to gammaherpesvirus-driven GC B cell proliferation. Hence, pharmacological inhibition of viral E3 ligase activity through targeting SOCS box motifs is a putative strategy to control gammaherpesvirus-driven lymphoproliferation and associated disease.



The gammaherpesviruses Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) cause lifelong persistent infection and play causative roles in several human malignancies. Colonization of B cells is crucial for virus persistence, and access to the B cell compartment is gained by virus-driven proliferation in germinal center (GC) B cells. Infection of B cells is predominantly latent, with the viral genome persisting as a multicopy episome and expressing only a small subset of viral genes. Here, we focused on latency-associated nuclear antigen (mLANA) encoded by murid herpesvirus-4 (MuHV-4), which exhibits homology in sequence, structure, and function to KSHV LANA (kLANA), thereby allowing the study of LANA-mediated pathogenesis in mice. Our experiments show that mLANA's E3 ubiquitin ligase activity is necessary for efficient expansion of latency in GC B cells, suggesting that the development of pharmacological inhibitors of LANA E3 ubiquitin ligase activity may allow strategies to interfere with gammaherpesvirus-driven lymphoproliferation and associated disease.
Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.
Sofia A
SA
Cerqueira
Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.
Min
M
Tan
Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.
Shijun
S
Li
Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.
Franceline
F
Juillard
Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal.
Colin E
CE
McVey
Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA kkaye@bwh.harvard.edu psimas@medicina.ulisboa.p.
Kenneth M
KM
Kaye
Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal kkaye@bwh.harvard.edu psimas@medicina.ulisboa.p.
J Pedro
JP
Simas
D000818:Animals; D000956:Antigens, Viral / Q000235:genetics / Q000378:metabolism*; D001402:B-Lymphocytes / Q000502:physiology*; D049109:Cell Proliferation; D004252:DNA Mutational Analysis; D004279:DNA, Viral / Q000378:metabolism; D018858:Germinal Center / Q000166:cytology*; D054884:Host-Pathogen Interactions; D051379:Mice; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D018144:Rhadinovirus / Q000502:physiology*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
D000956:Antigens, Viral; D004279:DNA, Viral; D050505:Mutant Proteins; D009687:Nuclear Proteins; C109540:latency-associated nuclear antigen; D044767:Ubiquitin-Protein Ligases