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J. Virol., 03 1995, 1500-1509, Vol 69, No. 3
JA McElhinny, WS MacMorran, GD Bren, RM Ten, A Israel and CV Paya
The mechanisms regulating human immunodeficiency virus (HIV) persistence in
human monocytes/macrophages are partially understood. Persistent HIV
infection of U937 monocytic cells results in NF-kappa B activation. Whether
virus-induced NF-kappa B activation is a mechanism that favors continuous
viral replication in macrophages remains unknown. To further delineate the
molecular mechanisms involved in the activation of NF-kappa B in
HIV-infected monocytes and macrophages, we have focused on the regulation
of the I kappa B molecules. First, we show that persistent HIV infection
results in the activation of NF- kappa B not only in monocytic cells but
also in macrophages. In HIV- infected cells, I kappa B alpha protein levels
are decreased secondary to enhanced protein degradation. This parallels the
increased I kappa B alpha synthesis secondary to increased I kappa B alpha
gene transcription, i.e., increased RNA and transcriptional activity of its
promoter-enhancer. Another protein with I kappa B function, p105, is also
modified in HIV-infected cells: p105 and p50 steady-state protein levels
are increased as a result of increased synthesis and proteolytic processing
of p105. Transcriptional activity of p105 is also increased in infected
cells and is also mediated by NF-kappa B through a specific kappa B motif.
These results demonstrate the existence of a triple autoregulatory loop in
monocytes and macrophages involving HIV, p105 and p50, and MAD3, with the
end result of persistent NF-kappa B activation and viral persistence.
Furthermore, persistent HIV infection of monocytes and macrophages provides
a useful model with which to study concomitant modifications of different I
kappa B molecules.
Copyright © 1995, American Society for Microbiology
Regulation of I kappa B alpha and p105 in monocytes and macrophages persistently infected with human immunodeficiency virus
Department of Immunology, Mayo Clinic, Rochester, Minnesota 55905.
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