scholarly journals The human immunodeficiency virus type 1 Rev protein and the Rev-responsive element counteract the effect of an inhibitory 5' splice site in a 3' untranslated region.

1995 ◽  
Vol 15 (6) ◽  
pp. 2962-2971 ◽  
Author(s):  
S K Barksdale ◽  
C C Baker
Keyword(s):  
Gene Expression ◽  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Splice Site ◽  
Untranslated Region ◽  
Expression Vector ◽  
Immunodeficiency Virus ◽  
Responsive Element ◽  
Rev Protein

A 5' splice site located in a 3' untranslated region (3'UTR) has been shown previously to inhibit gene expression. Natural examples of inhibitory 5' splice sites have been identified in the late 3'UTRs of papillomaviruses and are thought to inhibit viral late gene expression at early stages of the viral life cycle. In this study, we demonstrate that the interaction of the human immunodeficiency virus type 1 Rev protein with the Rev-responsive element (RRE) overcomes the inhibitory effects of a 5' splice site located within a 3'UTR. This was studied by using both a bovine papillomavirus type 1 L1 cDNA expression vector and a chloramphenicol acetyltransferase expression vector containing a 5' splice site in the 3'UTR. In both systems, coexpression of Rev enhanced cytoplasmic expression from vectors containing the RRE even when the RRE and the inhibitory 5' splice site were separated by up to 1,000 nucleotides. In addition, multiple copies of a 5' splice site in a 3'UTR were shown to act synergistically, and this effect could also be moderated by the interaction of Rev and the RRE. These studies provide additional evidence that at least one mechanism of Rev action is through interactions with the splicing machinery. We have previously shown that base pairing between the U1 small nuclear RNA and a 3'UTR 5' splice site is required for inhibition of gene expression. However, experiments by J. Kjems and P. A. Sharp (J. Virol. 67:4769-4776, 1993) have suggested that Rev acts on spliceosome assembly at a stage after binding of the U1 small nuclear ribonucleoprotein to the 5' splice site. This finding suggests that binding of additional small nuclear ribonucleoproteins, as well as other splicing factors, may be necessary for the inhibitory action of a 3'UTR 5' splice site. These data also suggest that expression of the papillomavirus late genes in terminally differentiated keratinocytes can be regulated by a viral or cellular Rev-like activity.

scholarly journals Kinetics of Human Immunodeficiency Virus Type 1 Decay following Entry into Resting CD4+ T Cells

2005 ◽  
Vol 79 (4) ◽  
pp. 2199-2210 ◽  
Author(s):  
Yan Zhou ◽  
Haili Zhang ◽  
Janet D. Siliciano ◽  
Robert F. Siliciano
Keyword(s):  
Gene Expression ◽  
Human Immunodeficiency Virus ◽  
T Cells ◽  
Human Immunodeficiency Virus Type ◽  
Reverse Transcription ◽  
Half Life ◽  
Immunodeficiency Virus ◽  
Kinetics Of ◽  
Hiv 1

ABSTRACT In untreated human immunodeficiency virus type 1 (HIV-1) infection, most viral genomes in resting CD4+ T cells are not integrated into host chromosomes. This unintegrated virus provides an inducible latent reservoir because cellular activation permits integration, virus gene expression, and virus production. It remains controversial whether HIV-1 is stable in this preintegration state. Here, we monitored the fate of HIV-1 in resting CD4+ cells by using a green fluorescent protein (GFP) reporter virus carrying an X4 envelope. After virus entry into resting CD4+ T cells, both rescuable virus gene expression, visualized with GFP, and rescuable virion production, assessed by p24 release, decayed with a half-life of 2 days. In these cells, reverse transcription goes to completion over 2 to 3 days, and 50% of the viruses that have entered undergo functional decay before reverse transcription is complete. We distinguished two distinct but closely related factors contributing to loss of rescuable virus. First, some host cells undergo virus-induced apoptosis upon viral entry, thereby reducing the amount of rescuable virus. Second, decay processes directly affecting the virus both before and after the completion of reverse transcription contribute to the loss of rescuable virus. The functional half-life of full-length, integration-competent reverse transcripts is only 1 day. We propose that rapid intracellular decay processes compete with early steps in viral replication in infected CD4+ T cells. Decay processes dominate in resting CD4+ T cells as a result of the slow kinetics of reverse transcription and blocks at subsequent steps. Therefore, the reservoir of unintegrated HIV-1 in recently infected resting CD4+ T cells is highly labile.

Poly(ADP-ribose) polymerase inhibitors suppress UV-induced human immunodeficiency virus type 1 gene expression at the posttranscriptional level

1991 ◽  
Vol 11 (7) ◽  
pp. 3522-3527
Author(s):  
S Yamagoe ◽  
T Kohda ◽  
M Oishi
Keyword(s):  
Gene Expression ◽  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Specific Gene ◽  
Adp Ribosylation ◽  
Immunodeficiency Virus ◽  
Posttranscriptional Level ◽  
Hiv 1

Gene expression of human immunodeficiency virus type 1 (HIV-1) is induced not only by trans activation mediated through a gene product (tat) encoded by the virus but also by treatment of virus-carrying cells with DNA-damaging agents such as UV light. Employing an artificially constructed DNA in which the chloramphenicol acetyltransferase gene was placed under the control of the HIV-1 long terminal repeat, we analyzed the induction process in HeLa cells and found that inhibitors of poly(ADP-ribose) polymerase suppressed UV-induced HIV-1 gene expression but not tat-mediated expression. We also found that suppression occurs at the posttranscriptional level. These results indicate that HIV-1 gene expression is activated by at least two different mechanisms, one of which involves poly-ADP ribosylation. A possible new role of poly-ADP ribosylation in the regulation of specific gene expression is also discussed.

scholarly journals Evidence for Gene Expression by Unintegrated Human Immunodeficiency Virus Type 1 DNA Species

2004 ◽  
Vol 78 (20) ◽  
pp. 11263-11271 ◽  
Author(s):  
Audrey Brussel ◽  
Pierre Sonigo
Keyword(s):  
Gene Expression ◽  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Viral Gene ◽  
Viral Expression ◽  
Molecular Stability ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The integrated form of human immunodeficiency virus type 1 (HIV-1) DNA is classically considered to be the sole template for viral gene expression. However, several studies have suggested that unintegrated viral DNA species could also support transcription. To determine the contribution of the different species of HIV-1 DNA to viral expression, we first monitored intracellular levels of various HIV-1 DNA and RNA species in a single-round infection assay. We observed that, in comparison to the precocity of HIV-1 DNA synthesis, viral expression was delayed, suggesting that only the HIV-1 DNA species that persist for a sufficient period of time would be transcribed efficiently. We next evaluated the transcriptional activity of the circular forms of HIV-1 DNA bearing two long terminal repeats, since these episomes were reported to exhibit an intrinsic molecular stability. Our results support the notion that these circular species of HIV-1 DNA are naturally transcribed during HIV-1 infection, thereby participating in virus replication.

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