Essential role of RBP-Jkappa in activation of the K8 delayed-early promoter of Kaposi's sarcoma-associated herpesvirus by ORF50/RTA.
KSHV K8 gene is activated by virally encoded transactivator RTA in delayed-early stage of viral reactivation. Three RTA-responsive elements (RREs) were identified in the promoter. Among them, RRE-II was found to be the most critical cis-acting element for RTA transactivation. In this report, the mechanism underlying RTA-mediated activation of the K8 delayed-early promoter was investigated. A DNA affinity purification study demonstrated that RRE-II was bound by cellular protein RBP-Jkappa, a sequence-specific DNA binding protein and a primary target of the Notch signaling pathway. Inspection of the RRE-II sequence revealed a potential recognition sequence for RBP-Jkappa (GTGAGAA) between the nucleotides -102 and -108 relative to the transcription initial site. Removal or mutation of the motif abolished RBP-Jkappa binding to the K8 promoter and as a consequence, RTA failed to bind to and activate the promoter. An essential role of RBP-Jkappa in the transcription of the K8 promoter was demonstrated by diminishment of the promoter activity in RBP-Jkappa-null murine embryonic fibroblasts. Taken together, RTA activates the K8 promoter through an indirect binding mechanism, i.e. being recruited to the K8 promoter through interaction with RBP-Jkappa bound to an RBP-Jkappa motif in the promoter.
Wang
Yan
Y
Department of Microbiology, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
Yuan
Yan
Y
D000818:Animals; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics*; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology; D015967:Gene Expression Regulation, Viral; D019288:Herpesvirus 8, Human / Q000235:genetics* / Q000502:physiology; D006801:Humans; D017874:Immediate-Early Proteins / Q000378:metabolism*; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein / Q000378:metabolism* / Q000502:physiology; D051379:Mice; D016366:Open Reading Frames; D017354:Point Mutation; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics*; D017384:Sequence Deletion; D015534:Trans-Activators / Q000378:metabolism*; D014764:Viral Proteins / Q000235:genetics* / Q000378:metabolism*; D014775:Virus Activation
D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D017874:Immediate-Early Proteins; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; C118265:K8 protein, Human herpesvirus 8; C497570:RBPJ protein, human; D012097:Repressor Proteins; C417604:Rta protein, Human herpesvirus 8; D015534:Trans-Activators; D014764:Viral Proteins