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Journal of Virology, July 1999, p. 5422-5430, Vol. 73, No. 7
Divisions of Human Biology and Basic
Sciences, Fred Hutchinson Cancer Research Center, Seattle,
Washington 98109
Received 9 February 1999/Accepted 25 March 1999
Viral protein R (Vpr) of human immunodeficiency virus type 1 (HIV-1) transiently arrests cells in the G2 phase of the
cell cycle and is a weak transcriptional transactivator. We found that Vpr increased HIV-1 long terminal repeat (LTR) activity in all cells
examined but, when expressed at high levels, decreased HIV-1 LTR
expression due to cytotoxic effects. Moreover, Vpr-mediated enhancement
of HIV-1 LTR-driven transcription was observed in cycling primary human
CD4+ T cells but not in terminally differentiated,
noncycling primary human macrophages. In single-round infection
experiments using primary human CD4+ T cells, proviral
clones expressing either wild-type Vpr or Vpr mutants that retained the
ability to cause a G2 arrest replicated to higher levels
than proviruses lacking Vpr or expressing mutants of Vpr that did not
cause an arrest. In support of the hypothesis that enhancement of HIV-1
LTR transcription by Vpr is an indirect effect of the ability of Vpr to
delay cells in G2, counterflow centrifugal elutriation of
cells into different phases of the cell cycle demonstrated that HIV-1
LTR expression was highest in G2. Finally, the ability of
Vpr to upregulate viral transcription was dependent on a minimal
promoter containing a functional TATA box and an enhancer.
0022-538X/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Cell Cycle- and Vpr-Mediated Regulation of Human Immunodeficiency
Virus Type 1 Expression in Primary and Transformed T-Cell
Lines
*
Corresponding author. Mailing address: Division of
Human Biology, C2-023, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. North, Seattle, WA 98109. Phone: (206) 667-5058. Fax:
(206) 667-6523. E-mail: memerman{at}fhcrc.org.
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