Submitted August 11, 2006
Accepted February 17, 2007
Hsp72 up regulates Epstein-Barr Virus EBNALP co-
activation
with EBNA2
Chih-Wen Peng, Bo Zhao, Hong-Chi Chen, Min-Luen Chou, Chiou-Yan Lai, Shinn-Zong Lin, Hsue-Yin Hsu, and Elliott Kieff*
Department of Life Science and Gene Therapy Division, Tzu-Chi University and Hospital, Hualien, Taiwan
Dept of Medicine & Microbiology & Molecular Genetics, Channing Laboratory, Brigham and Women's Hospital and Harvard University, Boston, MA, United States
Department of neuroscience, Tzu-Chi Hospital, Hualien, Taiwan
* Corresponding author; email: ekieff{at}rics.bwh.harvard.edu.
The Epstein-Barr Virus transcriptional co-activator
EBNALP specifically associates and co-localizes with
Hsp72 in lymphoblastoid cell lines. We now find that
over expression of Hsp72 more than doubled EBNALP co-
activation 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 co-activation 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, co-activated with EBNA2, but was
not affected by Hsp72 over expression, despite Hsp72 up
regulation of wild type EBNALP co-activation with EBNA2
at all levels of EBNALP expression, indicating the
importance of Hsp72 association with EBNALP for Hsp72 up
regulation of co-activation. Importantly, a 90% RNAi
knock down of Hsp72 reduced EBNALP co-activation with
EBNA2 of transfected EBV LMP1 and Cp Promoters by ~50%.
Over expression of the Hsp72 C-terminal interacting and
regulatory protein, CHIP, strongly down regulated EBNALP
co-activation, independently of CHIP ubiquitin ligase
activity. CHIP affects were Hsp72 dependent, indicating
a background down modulating role for CHIP in Hsp72
augmentation of EBNA2 and EBNALP co-activation. Based on
these and other cited data, we favor a model in which
Hsp72 co-chaperones EBNALP shuttling of repressors from
EBNA2 enhanced Promoters.
