Kaposi's Sarcoma-associated herpesvirus lytic switch protein stimulates DNA binding of RBP-Jk/CSL to activate the Notch pathway.
Kaposi's sarcoma-associated herpesvirus (KSHV) lytic switch protein, Rta, is a ligand-independent inducer of the Notch signal transduction pathway, and KSHV cannot reactivate from latency in cells null for the Notch target protein RBP-Jk. Here we show that Rta promotes DNA binding of RBP-Jk, a mechanism that is fundamentally different from that established for the RBP-Jk-activating proteins, Notch intracellular domain (NICD) and Epstein-Barr virus EBNA2. Although constitutively active RBP-Jk and NICD do not transactivate KSHV promoters independently, cotransfection of an Rta mutant lacking its transactivation domain robustly restores transcriptional activation. Cooperation requires intact DNA binding sites for Rta and RBP-Jk and trimeric complex formation between the three molecules in vitro. In infected cells, RBP-Jk is virtually undetectable on a series of viral and cellular promoters during KSHV latency but is significantly enriched following Rta expression during viral reactivation. Accordingly, Rta, but not EBNA2 and NICD, reactivates the complete viral lytic cycle.
Carroll
Kyla Driscoll
KD
Department of Microbiology and Molecular Genetics, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark, NJ 07101, USA.
Bu
Wei
W
Palmeri
Diana
D
Spadavecchia
Sophia
S
Lynch
Stephen J
SJ
Marras
Salvatore A E
SA
Tyagi
Sanjay
S
Lukac
David M
DM
D017398:Alternative Splicing / Q000235:genetics; D001483:Base Sequence; D002460:Cell Line; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism*; D015967:Gene Expression Regulation, Viral; D016679:Genome, Viral / Q000235:genetics; D019288:Herpesvirus 8, Human / Q000235:genetics / Q000378:metabolism; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics / Q000378:metabolism*; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein / Q000235:genetics / Q000378:metabolism*; D037102:Lectins / Q000378:metabolism*; D016366:Open Reading Frames / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D051880:Receptors, Notch / Q000378:metabolism*; D015398:Signal Transduction; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
D004279:DNA, Viral; D017874:Immediate-Early Proteins; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; D037102:Lectins; D051880:Receptors, Notch; C417604:Rta protein, Human herpesvirus 8; D015534:Trans-Activators; D014764:Viral Proteins; C059525:cerebellar soluble lectin