title: The nuclear chaperone nucleophosmin escorts an Epstein-Barr Virus nuclear antigen to establish transcriptional cascades for latent infection in human B cells.
abstract: Epstein-Barr Virus (EBV) is an oncogenic γ-herpesvirus that capably establishes both latent and lytic modes of infection in host cells and causes malignant diseases in humans. Nuclear antigen 2 (EBNA2)-mediated transcription of both cellular and viral genes is essential for the establishment and maintenance of the EBV latency program in B lymphocytes. Here, we employed a protein affinity pull-down and LC-MS/MS analysis to identify nucleophosmin (NPM1) as one of the cellular proteins bound to EBNA2. Additionally, the specific domains that are responsible for protein-protein interactions were characterized as EBNA2 residues 300 to 360 and the oligomerization domain (OD) of NPM1. As in c-MYC, dramatic NPM1 expression was induced in EBV positively infected B cells after three days of viral infection, and both EBNA2 and EBNALP were implicated in the transactivation of the NPM1 promoter. Depletion of NPM1 with the lentivirus-expressed short-hairpin RNAs (shRNAs) effectively abrogated EBNA2-dependent transcription and transformation outgrowth of lymphoblastoid cells. Notably, the ATP-bound state of NPM1 was required to induce assembly of a protein complex containing EBNA2, RBP-Jκ, and NPM1 by stabilizing the interaction of EBNA2 with RBP-Jκ. In a NPM1-knockdown cell line, we demonstrated that an EBNA2-mediated transcription defect was fully restored by the ectopic expression of NPM1. Our findings highlight the essential role of NPM1 in chaperoning EBNA2 onto the latency-associated membrane protein 1 (LMP1) promoters, which is coordinated with the subsequent activation of transcriptional cascades through RBP-Jκ during EBV infection. These data advance our understanding of EBV pathology and further imply that NPM1 can be exploited as a therapeutic target for EBV-associated diseases.
authors.affiliation: Department of Life Sciences, Tzu-Chi University, Hualien, Taiwan.
authors.forename: Cheng-Der
authors.initials: CD
authors.lastname: Liu
authors.forename: Ya-Lin
authors.initials: YL
authors.lastname: Chen
authors.forename: Yi-Li
authors.initials: YL
authors.lastname: Min
authors.forename: Bo
authors.initials: B
authors.lastname: Zhao
authors.forename: Chi-Ping
authors.initials: CP
authors.lastname: Cheng
authors.forename: Myung-Soo
authors.initials: MS
authors.lastname: Kang
authors.forename: Shu-Jun
authors.initials: SJ
authors.lastname: Chiu
authors.forename: Elliott
authors.initials: E
authors.lastname: Kieff
authors.forename: Chih-Wen
authors.initials: CW
authors.lastname: Peng
mesh_terms: D001402:B-Lymphocytes / Q000378:metabolism* / Q000821:virology; D045744:Cell Line, Tumor; D019309:Epstein-Barr Virus Nuclear Antigens / Q000235:genetics / Q000378:metabolism*; D004854:Herpesvirus 4, Human / Q000502:physiology*; D006801:Humans; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D000090243:Nucleophosmin; D017434:Protein Structure, Tertiary; D016271:Proto-Oncogene Proteins c-myc; D014158:Transcription, Genetic; D014763:Viral Matrix Proteins / Q000096:biosynthesis / Q000235:genetics; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D019065:Virus Assembly / Q000502:physiology; D017735:Virus Latency / Q000502:physiology*
chemical_list: C402641:EBNA-2 protein, Human herpesvirus 4; C037662:EBV-associated membrane antigen, Epstein-Barr virus; D019309:Epstein-Barr Virus Nuclear Antigens; C489427:MYC protein, human; D018832:Molecular Chaperones; C000716967:NPM1 protein, human; D009687:Nuclear Proteins; D016271:Proto-Oncogene Proteins c-myc; D014763:Viral Matrix Proteins; D014764:Viral Proteins; D000090243:Nucleophosmin