Hsp72 up-regulates Epstein-Barr virus EBNALP coactivation with EBNA2.
The Epstein-Barr virus (EBV) transcriptional coactivator EBNALP specifically associates and colocalizes with Hsp72 in lymphoblastoid cell lines. We now find that overexpression of Hsp72 more than doubled EBNALP coactivation with EBNA2 of a transfected EBV LMP1 promoter in B lymphoblasts, did not affect EBNA2 or EBNALP protein levels, and strongly up-regulated EBNA2 and EBNALP coactivation of LMP1 protein expression from the endogenous EBV genome in latency I infected Akata cells. The Hsp72 ATP, protein binding, and the C-terminal regulatory domains were required for full activity. An EBNALP deletion mutant, EBNALPd45, which does not associate with Hsp72, coactivated with EBNA2, but was not affected by Hsp72 overexpression, despite Hsp72 up-regulation of wild-type EBNALP coactivation with EBNA2 at all levels of EBNALP expression, indicating the importance of Hsp72 association with EBNALP for Hsp72 up-regulation of coactivation. Of importance, a 90% RNAi knockdown of Hsp72 reduced EBNALP coactivation with EBNA2 of transfected EBV LMP1 and Cp promoters by approximately 50%. Overexpression of the Hsp72 C-terminal interacting and regulatory protein, CHIP, strongly down-regulated EBNALP coactivation, independently of CHIP ubiquitin ligase activity. CHIP effects were Hsp72 dependent, indicating a background downmodulating role for CHIP in Hsp72 augmentation of EBNA2 and EBNALP coactivation. Based on these and other cited data, we favor a model in which Hsp72 chaperones EBNALP shuttling of repressors from EBNA2-enhanced promoters.
Peng
Chih-Wen
CW
Department of Life Science and Gene Therapy Division, Tzu-Chi University and Hospital, Hualien, Taiwan.
Zhao
Bo
B
Chen
Hong-Chi
HC
Chou
Min-Luen
ML
Lai
Chiou-Yan
CY
Lin
Shinn-Zong
SZ
Hsu
Hsue-Yin
HY
Kieff
Elliott
E
D002460:Cell Line; D020031:Epstein-Barr Virus Infections; D019309:Epstein-Barr Virus Nuclear Antigens / Q000378:metabolism*; D050884:HSP72 Heat-Shock Proteins / Q000378:metabolism / Q000502:physiology*; D004854:Herpesvirus 4, Human / Q000378:metabolism; D006801:Humans; D011401:Promoter Regions, Genetic; D021381:Protein Transport; D015854:Up-Regulation; D014764:Viral Proteins / Q000378:metabolism
C402641:EBNA-2 protein, Human herpesvirus 4; C402640:EBNA-LP protein, Human herpesvirus 4; D019309:Epstein-Barr Virus Nuclear Antigens; D050884:HSP72 Heat-Shock Proteins; D014764:Viral Proteins