Role of the TSG101 gene in Epstein-Barr virus late gene transcription.
Rta, an Epstein-Barr virus (EBV)-encoded immediate-early protein, governs the reactivation of the viral lytic program by transactivating a cascade of lytic gene expression. Cellular transcription factors such as Sp1, ATF2, E2F, and Akt have been demonstrated to mediate Rta transactivation of lytic genes. We report herein that Rta associates with another potent transcription factor, tumor susceptibility gene 101 (TSG101), to promote the activation of EBV late genes. Results from an EBV cDNA array reveal that depletion of TSG101 by siRNA potently inhibits the transcription of five Rta-responsive EBV late genes, BcLF1, BDLF3, BILF2, BLLF1, and BLRF2. Depletion of TSG101 impairs the Rta transactivation of these late promoters severely. Moreover, a concordant augmentation of Rta transactivating activity is observed when TSG101 is overexpressed following ectopic transfection. Mechanistically, Rta interaction with TSG101 causes the latter to accumulate principally in the nuclei, wherein the proteins colocalize and are recruited to the viral promoters. Of note, TSG101 is crucial for the efficient binding of Rta to these late promoters. As a result, cells with defective TSG101 fail to express late viral proteins, leading to a decrease in the yield of virus particles. Thus, the contribution of TSG101 to Rta-mediated late gene activation is of great importance for completion of the EBV productive lytic cycle. These observations consolidate a role for TSG101 in the replication of EBV, a DNA virus, that differs from what is observed for RNA viruses, where TSG101 aids mainly in the endosomal sorting of enveloped late viral proteins for assembly at the plasma membrane.
Chua
Huey-Huey
HH
Graduate Institute of Microbiology, College of Medicine, National Taiwan University, No. 1 Jen-Ai Road 1st section, Taipei 10051, Taiwan.
Lee
Heng-Huan
HH
Chang
Shih-Shin
SS
Lu
Chih-Chung
CC
Yeh
Te-Huei
TH
Hsu
Tsuey-Ying
TY
Cheng
Tzu-Hao
TH
Cheng
Jiin-Tsuey
JT
Chen
Mei-Ru
MR
Tsai
Ching-Hwa
CH
D001483:Base Sequence; D045744:Cell Line, Tumor; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics*; D056827:Endosomal Sorting Complexes Required for Transport; D020031:Epstein-Barr Virus Infections / Q000235:genetics / Q000378:metabolism / Q000821:virology; D005814:Genes, Viral; D004854:Herpesvirus 4, Human / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D034741:RNA, Small Interfering / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D044763:Ubiquitin-Conjugating Enzymes / Q000378:metabolism; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism; D014779:Virus Replication; D000099177:Tsg101 Protein
D004279:DNA, Viral; D004268:DNA-Binding Proteins; D056827:Endosomal Sorting Complexes Required for Transport; D017874:Immediate-Early Proteins; D034741:RNA, Small Interfering; D015534:Trans-Activators; D014157:Transcription Factors; D044763:Ubiquitin-Conjugating Enzymes; D014764:Viral Proteins; D000099177:Tsg101 Protein; C068382:BRLF1 protein, Human herpesvirus 4