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J. Virol., 05 1997, 3563-3573, Vol 71, No. 5
AG Bassuk, RT Anandappa and JM Leiden
The transcriptional regulatory elements of many inducible T-cell genes
contain adjacent or overlapping binding sites for the Ets and NF-
kappaB/NFAT families of transcription factors. Similar arrays of
functionally important NF-kappaB/NFAT and Ets binding sites are present in
the transcriptional enhancers of human immunodeficiency viruses types 1 and
2 (HIV-1 and HIV-2), suggesting that this pattern of nuclear protein
binding sites reflects an evolutionarily conserved mechanism for regulating
inducible T-cell gene expression that has been co-opted during HIV
evolution. Despite these findings, the molecular mechanisms by which Ets
and NF-kappaB/NFAT proteins cooperatively regulate inducible T-cell gene
expression remained unknown. In the studies described in this report, we
demonstrated a physical interaction between multiple Ets and NF-kappaB/NFAT
proteins both in vitro and in activated normal human T cells. This
interaction is mediated by the Ets domain of Ets proteins and the
C-terminal region of the Rel homology domains of NF-kappaB/NFAT proteins.
In addition, the Ets-NF-kappaB/NFAT interaction requires the presence of
DNA binding sites for both proteins, as it is abolished by the DNA
intercalating agents propidium iodide and ethidium bromide and enhanced by
the presence of synthetic oligonucleotides containing binding sites for Ets
and NF-kappaB proteins. A dominant-negative mutant of NF-kappaB p50 that
binds DNA but fails to interact with Ets proteins inhibits the synergistic
activation of the HIV-1 and HIV-2 enhancers by NF-kappaB (p50 + p65) and
Ets-1, suggesting that physical interaction between Ets and NF-kappaB
proteins is required for the transcriptional activity of the HIV-1 and
HIV-2 enhancers. Taken together, these findings suggest that evolutionarily
conserved physical interactions between Ets and NF- kappaB/NFAT proteins
are important in regulating the inducible expression of T-cell genes and
viruses. These interactions represent a potential target for the
development of novel immunosuppressive and antiviral therapies.
Copyright © 1997, American Society for Microbiology
Physical interactions between Ets and NF-kappaB/NFAT proteins play an important role in their cooperative activation of the human immunodeficiency virus enhancer in T cells
Department of Medicine, University of Chicago, Illinois 60637, USA.
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