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J. Virol., 03 1997, 2004-2012, Vol 71, No. 3
SF Parker, LK Felzien, ND Perkins, MJ Imperiale and GJ Nabel
Transcription of human immunodeficiency virus (HIV) type 1 and other
viruses is regulated by the transcription factor NF-kappaB, which interacts
with the multifunctional cellular protein p300. p300, originally identified
by its ability to bind adenovirus early region 1A (E1A), has also been
shown to regulate HIV transcription through its interaction with NF-kappaB.
The 13S form of E1A activates HIV gene expression, while the 12S form
represses its transcription. In this report, we have investigated whether
these divergent effects of E1A are dependent upon common or distinct
cellular cofactors, including p300, pRb, and the TATA box-binding protein
(TBP). Unlike activation in the absence of E1A, cooperative stimulation of
HIV gene expression by 13S E1A and RelA was independent of the ability of
E1A to bind p300 but was critically dependent on the E1A CR3 region which
associates with TBP. In contrast, inhibition of basal HIV gene expression
by the 12S form of E1A was dependent on p300 but not pRb or TBP.
Interestingly, mutation of the CR2 region of 12S E1A responsible for pRb
binding abolished the repression of HIV transcription stimulated by tumor
necrosis factor alpha, suggesting that repression of cytokine-activated
transcription involves cofactors different from those used in unstimulated
cells. Repression and activation of HIV transcription by different forms of
E1A are mediated by distinct sets of cellular cofactors. These findings
suggest that E1A has evolved to interact by alternative mechanisms with a
transcriptional coactivator and its associated cofactors to differentially
modulate cellular and viral gene expression.
Copyright © 1997, American Society for Microbiology
Distinct domains of adenovirus E1A interact with specific cellular factors to differentially modulate human immunodeficiency virus transcription
Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor 48109-0650, USA.
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