title: Role of RNF4 in the ubiquitination of Rta of Epstein-Barr virus.
abstract: Epstein-Barr virus (EBV) encodes a transcription factor, Rta, which is required to activate the transcription of EBV lytic genes. This study demonstrates that treating P3HR1 cells with a proteasome inhibitor, MG132, causes the accumulation of SUMO-Rta and promotes the expression of EA-D. GST pulldown and coimmunoprecipitation studies reveal that RNF4, a RING-domain-containing ubiquitin E3 ligase, interacts with Rta. RNF4 also targets SUMO-2-conjugated Rta and promotes its ubiquitination in vitro. Additionally, SUMO interaction motifs in RNF4 are important to the ubiquitination of Rta because the RNF4 mutant with a mutation at the motifs eliminates ubiquitination. The mutation of four lysine residues on Rta that abrogated SUMO-3 conjugation to Rta also decreases the enhancement of the ubiquitination of Rta by RNF4. This finding demonstrates that RNF4 is a SUMO-targeted ubiquitin E3 ligase of Rta. Finally, knockdown of RNF4 enhances the expression of Rta and EA-D, subsequently promoting EBV lytic replication and virions production. Results of this study significantly contribute to efforts to elucidate a SUMO-targeted ubiquitin E3 ligase that regulates Rta ubiquitination to influence the lytic development of EBV.
authors.affiliation: Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei, 106, Taiwan.
authors.forename: Ya-Chun
authors.initials: YC
authors.lastname: Yang
authors.forename: Yushi
authors.initials: Y
authors.lastname: Yoshikai
authors.forename: Shih-Wei
authors.initials: SW
authors.lastname: Hsu
authors.forename: Hisato
authors.initials: H
authors.lastname: Saitoh
authors.forename: Li-Kwan
authors.initials: LK
authors.lastname: Chang
mesh_terms: D020816:Amino Acid Motifs; D002460:Cell Line; D020031:Epstein-Barr Virus Infections / Q000235:genetics / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D004854:Herpesvirus 4, Human / Q000502:physiology*; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D025841:Small Ubiquitin-Related Modifier Proteins / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination; D014452:Ubiquitins / Q000235:genetics / Q000378:metabolism; D014779:Virus Replication / Q000502:physiology*
chemical_list: C068382:BRLF1 protein, Human herpesvirus 4; D017874:Immediate-Early Proteins; D009687:Nuclear Proteins; C114070:RNF4 protein, human; C117909:SUMO2 protein, human; C492189:SUMO3 protein, human; D025841:Small Ubiquitin-Related Modifier Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D014452:Ubiquitins
keywords: DNA Viruses; E3 Ubiquitin Ligase; Epstein-Barr Virus; Protein Degradation; RNF4; Rta; Sumoylation; Ubiquitination