scholarly journals Delayed Human Immunodeficiency Virus Type 1-Induced Apoptosis in Cells Expressing Truncated Forms of CD4

1998 ◽  
Vol 72 (3) ◽  
pp. 1754-1761 ◽  
Author(s):  
Claire Guillerm ◽  
Nolwenn Coudronnière ◽  
Véronique Robert-Hebmann ◽  
Christian Devaux
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Death ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Antigen Expression ◽  
Immunodeficiency Virus ◽  
Virus Exposure ◽  
Induced Apoptosis ◽  
Hiv 1

ABSTRACT It has been reported previously that cells expressing a truncated form of CD4 which lacks the cytoplasmic tail of the molecule (truncation at position 402) were not sensitive to human immunodeficiency virus type 1 (HIV-1)-induced apoptosis in an acute-phase model of infection (J. Corbeil, M. Tremblay, and D. D. Richman, J. Exp. Med. 183:39–48, 1996). The role played by the cytoplasmic domain of CD4 in HIV-1-induced apoptosis was reexamined here with clones of A2.01 cells expressing different forms of CD4 and the DNA intercalant YOPRO-1 assay. Six days after virus exposure, we found evidence of apoptosis in A2.01 cells expressing the wild-type CD4 (A2.01/CD4), whereas enhanced apoptosis remained absent in cultures of A2.01/CD4.401 and A2.01/CD4.403 cells (A2.01 cells which express CD4.401 and CD4.403 molecules with truncations at positions 401 and 403, respectively). However, cell death by apoptosis measured with YOPRO-1 was found in cultures of A2.01/CD4.401 and A2.01/CD4.403 cells 15 days after virus exposure. This result was confirmed with a terminal dUTP nick end-labeling assay and propidium iodide staining. The long lag time postinfection required for apoptosis to be observed in cultures of infected cells expressing truncated forms of CD4 was due to the delayed viral replication in these cells, as shown by monitoring of the viral reverse transcriptase activity and HIV-1 p24 gag antigen expression. These results emphasize the relationship between virus replication and cell death by apoptosis.

Human Immunodeficiency Virus Type 1 Nef Protein Sensitizes CD4+ T Lymphoid Cells to Apoptosis via Functional Upregulation of the CD95/CD95 Ligand Pathway

Blood ◽  
1999 ◽  
Vol 93 (3) ◽  
pp. 1000-1010 ◽  
Author(s):  
Giorgio Zauli ◽  
Davide Gibellini ◽  
Paola Secchiero ◽  
Hélène Dutartre ◽  
Daniel Olive ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Death ◽  
T Cell ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Cd95 Ligand ◽  
Immunodeficiency Virus ◽  
Hiv 1

Many viruses have evolved genes encoding proteins that regulate cell death by apoptosis. The human immunodeficiency virus type 1 (HIV-1) Nef protein alters T-cell development and signaling and is required for optimal viral replication and pathogenicity in vivo. To analyze the interference of Nef with cell survival, we used both regulated and constitutively expressed nef alleles in stably transfected T-cell lines. Nef-expressing cells were sensitized to cell death by apoptosis, which was specifically exacerbated by an anti-CD95 IgM monoclonal antibody (MoAb). Flow cytometric analysis showed that the surface expression of both CD95 and CD95 ligand (CD95L) was upregulated by endogenous Nef expression. Nef-mediated apoptosis was almost completely suppressed by the addition in culture of an anti-CD95 Fab′ IgG MoAb, which specifically blocks CD95/CD95L interactions. Lastly, mutation of a proline motif in the core region of the nef gene, which disrupts its ability to interact with cellular kinases and reduces HIV-1 replication in vitro, completely abrogated the Nef-mediated induction of apoptosis as well as its ability to upregulate surface CD95 and CD95L. These findings may provide molecular insight into the role of endogenous Nef in the T-cell depletion observed in vivo, particularly HIV-specific cytotoxic CD8+ T cells.

scholarly journals Fusion-Induced Apoptosis Contributes to Thymocyte Depletion by a Pathogenic Human Immunodeficiency Virus Type 1 Envelope in the Human Thymus

2006 ◽  
Vol 80 (22) ◽  
pp. 11019-11030 ◽  
Author(s):  
Eric G. Meissner ◽  
Liguo Zhang ◽  
S. Jiang ◽  
Lishan Su
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Caspase 3 ◽  
Fusion Inhibitors ◽  
Immunodeficiency Virus ◽  
Induced Apoptosis ◽  
Hiv 1 ◽  
Active Caspase

ABSTRACT The mechanisms of CD4+ T-cell depletion during human immunodeficiency virus type 1 (HIV-1) infection remain incompletely characterized. Of particular importance is how CD4+ T cells are depleted within the lymphoid organs, including the lymph nodes and thymus. Herein we characterize the pathogenic mechanisms of an envelope from a rapid progressor (R3A Env) in the NL4-3 backbone (NL4-R3A) which is able to efficiently replicate and deplete CD4+ thymocytes in the human fetal-thymus organ culture (HF-TOC). We demonstrate that uninterrupted replication is required for continual thymocyte depletion. During depletion, NL4-R3A induces an increase in thymocytes which uptake 7AAD, a marker of cell death, and which express active caspase-3, a marker of apoptosis. While 7AAD uptake is observed predominantly in uninfected thymocytes (p24−), active caspase-3 is expressed in both infected (p24+) and uninfected thymocytes (p24−). When added to HF-TOC with ongoing infection, the protease inhibitor saquinavir efficiently suppresses NL4-R3A replication. In contrast, the fusion inhibitors T20 and C34 allow for sustained HIV-1 production. Interestingly, T20 and C34 effectively prevent thymocyte depletion in spite of this sustained replication. Apoptosis of both p24− and p24+ thymocytes appears to be envelope fusion dependent, as T20, but not saquinavir, is capable of reducing thymocyte apoptosis. Together, our data support a model whereby pathogenic envelope-dependent fusion contributes to thymocyte depletion in HIV-1-infected thymus, correlated with induction of apoptosis in both p24+ and p24− thymocytes.

scholarly journals The CXCR4 Antagonist AMD3100 Efficiently Inhibits Cell-Surface-Expressed Human Immunodeficiency Virus Type 1 Envelope-Induced Apoptosis

2000 ◽  
Vol 44 (1) ◽  
pp. 51-56 ◽  
Author(s):  
Julià Blanco ◽  
Jordi Barretina ◽  
Geoffrey Henson ◽  
Gary Bridger ◽  
Erik De Clercq ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Death ◽  
Cell Surface ◽  
Cell Lines ◽  
Human Immunodeficiency Virus Type ◽  
Immunodeficiency Virus ◽  
Antiapoptotic Activity ◽  
Induced Apoptosis ◽  
Hiv 1

ABSTRACT Infection by human immunodeficiency virus type 1 (HIV-1) has been associated with increased cell death by apoptosis in infected and uninfected cells. The envelope glycoprotein complex ([gp120/gp41]n) of X4 HIV-1 isolates is involved in both infected and uninfected cell death via its interaction with cellular receptors CD4 and CXCR4. We studied the effect of the blockade of CXCR4 receptors by the agonist stromal derived factor (SDF-1α) and the antagonist bicyclam AMD3100 on apoptotic cell death of CD4+cells in different models of HIV infection. In HIV-infected CEM or SUP-T1 cultures, AMD3100 showed antiapoptotic activity even when added 24 h after infection. In contrast, other antiviral agents, such as zidovudine, failed to block apoptosis under these conditions. The antiapoptotic activity of AMD3100 was also studied in coculture of peripheral blood mononuclear cells or CD4+ cell lines with chronically infected H9/IIIB cells. AMD3100 was found to inhibit both syncytium formation and apoptosis induction with 50% inhibitory concentrations ranging from 0.009 to 0.24 μg/ml, depending on the cell type. When compared to SDF-1α, AMD3100 showed higher inhibitory potency in all cell lines tested. Our data indicate that the bicyclam AMD3100 not only inhibits HIV replication but also efficiently blocks cell-surface-expressed HIV-1 envelope-induced apoptosis in uninfected cells.

scholarly journals Human Immunodeficiency Virus Type 1 Vpr Induces Apoptosis through Caspase Activation

2000 ◽  
Vol 74 (7) ◽  
pp. 3105-3111 ◽  
Author(s):  
Sheila A. Stewart ◽  
Betty Poon ◽  
Joo Y. Song ◽  
Irvin S. Y. Chen
Keyword(s):  
Cell Cycle ◽  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Ectopic Expression ◽  
Caspase Activity ◽  
Immunodeficiency Virus ◽  
Induced Apoptosis ◽  
Hiv 1

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) Vpr is a 96-amino-acid protein that is found associated with the HIV-1 virion. Vpr induces cell cycle arrest at the G2/M phase of the cell cycle, and this arrest is followed by apoptosis. We examined the mechanism of Vpr-induced apoptosis and found that HIV-1 Vpr-induced apoptosis requires the activation of a number of cellular cysteinyl aspartate-specific proteases (caspases). We demonstrate that ectopic expression of anti-apoptotic viral proteins, which inhibit caspase activity, and addition of synthetic peptides, which represent caspase cleavage sites, can inhibit Vpr-induced apoptosis. Finally, inhibition of caspase activity and subsequent inhibition of apoptosis results in increased viral expression, suggesting that therapeutic strategies aimed at reducing Vpr-induced apoptosis in vivo require careful consideration.

Human Immunodeficiency Virus Type 1 Nef Protein Sensitizes CD4+ T Lymphoid Cells to Apoptosis via Functional Upregulation of the CD95/CD95 Ligand Pathway

Blood ◽  
1999 ◽  
Vol 93 (3) ◽  
pp. 1000-1010 ◽  
Author(s):  
Giorgio Zauli ◽  
Davide Gibellini ◽  
Paola Secchiero ◽  
Hélène Dutartre ◽  
Daniel Olive ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Death ◽  
T Cell ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Cd95 Ligand ◽  
Immunodeficiency Virus ◽  
Hiv 1

Abstract Many viruses have evolved genes encoding proteins that regulate cell death by apoptosis. The human immunodeficiency virus type 1 (HIV-1) Nef protein alters T-cell development and signaling and is required for optimal viral replication and pathogenicity in vivo. To analyze the interference of Nef with cell survival, we used both regulated and constitutively expressed nef alleles in stably transfected T-cell lines. Nef-expressing cells were sensitized to cell death by apoptosis, which was specifically exacerbated by an anti-CD95 IgM monoclonal antibody (MoAb). Flow cytometric analysis showed that the surface expression of both CD95 and CD95 ligand (CD95L) was upregulated by endogenous Nef expression. Nef-mediated apoptosis was almost completely suppressed by the addition in culture of an anti-CD95 Fab′ IgG MoAb, which specifically blocks CD95/CD95L interactions. Lastly, mutation of a proline motif in the core region of the nef gene, which disrupts its ability to interact with cellular kinases and reduces HIV-1 replication in vitro, completely abrogated the Nef-mediated induction of apoptosis as well as its ability to upregulate surface CD95 and CD95L. These findings may provide molecular insight into the role of endogenous Nef in the T-cell depletion observed in vivo, particularly HIV-specific cytotoxic CD8+ T cells.

scholarly journals Preferential Cytolysis of Peripheral Memory CD4+ T Cells by In Vitro X4-Tropic Human Immunodeficiency Virus Type 1 Infection before the Completion of Reverse Transcription

2008 ◽  
Vol 82 (18) ◽  
pp. 9154-9163 ◽  
Author(s):  
Yan Zhou ◽  
Lin Shen ◽  
Hung-Chih Yang ◽  
Robert F. Siliciano
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cells ◽  
Cell Death ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Reverse Transcription ◽  
Host Cells ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT CD4+ T-cell depletion is the hallmark of AIDS pathogenesis. Multiple mechanisms may contribute to the death of productively infected CD4+ T cells and innocent-bystander cells. In this study, we characterize a novel mechanism in which human immunodeficiency virus type 1 (HIV-1) infection preferentially depletes peripheral memory CD4+ T cells before the completion of reverse transcription. Using a recombinant HIV-1 carrying the green fluorescent protein reporter gene, we demonstrate that memory CD4+ T cells were susceptible to infection-induced cell death at a low multiplicity of infection. Infected memory CD4+ T cells underwent rapid necrotic cell death. Killing of host cells was dependent on X4 envelope-mediated viral fusion, but not on virion-associated Vpr or Nef. In contrast to peripheral resting CD4+ T cells, CD4+ T cells stimulated by mitogen or certain cytokines were resistant to HIV-1-induced early cell death. These results demonstrate that early steps in HIV-1 infection have a detrimental effect on certain subsets of CD4+ T cells. The early cell death may serve as a selective disadvantage for X4-tropic HIV-1 in acute infection but may play a role in accelerated disease progression, which is associated with the emergence of X4-tropic HIV-1 in the late stage of AIDS.

scholarly journals Diazepam-mediated inhibition of human immunodeficiency virus type 1 expression in human brain cells.

1997 ◽  
Vol 41 (11) ◽  
pp. 2566-2569 ◽  
Author(s):  
J R Lokensgard ◽  
G Gekker ◽  
S Hu ◽  
A F Arthur ◽  
C C Chao ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Brain ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Antigen Expression ◽  
Brain Cell ◽  
Immunodeficiency Virus ◽  
P24 Antigen ◽  
Hiv 1

Treatment of acutely infected human brain cell and enriched microglial cell cultures with diazepam inhibited human immunodeficiency virus type 1 (HIV-1) p24 antigen expression. Similarly, diazepam suppressed HIV-1 expression in chronically infected promonocytic (U1) cells and acutely infected monocyte-derived macrophages, and this antiviral activity was associated with decreased activation of nuclear factor kappa B.

scholarly journals Human Immunodeficiency Virus Type 1 Inhibits DNA Damage-Triggered Apoptosis by a Nef-Independent Mechanism

2005 ◽  
Vol 79 (9) ◽  
pp. 5489-5498 ◽  
Author(s):  
Michael Schindler ◽  
Jan Münch ◽  
Frank Kirchhoff
Keyword(s):  
Human Immunodeficiency Virus ◽  
Dna Damage ◽  
Cell Death ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Serum Starvation ◽  
Immunodeficiency Virus ◽  
Independent Mechanism ◽  
Hiv 1

ABSTRACT It is controversial whether the accessory human immunodeficiency virus type 1 (HIV-1) Nef protein inhibits or enhances apoptosis. To address this issue, we investigated the effect of Nef on programmed cell death with vectors or proviral HIV-1 constructs coexpressing Nef and green fluorescent protein from single bicistronic RNAs. This approach allows us to readily identify transfected or infected cells and to correlate cell death directly with Nef expression levels. We demonstrate that Nef does not significantly affect apoptosis in transfected or HIV-1-infected Jurkat T cells or primary human peripheral blood mononuclear cells. Unexpectedly, however, both nef + and nef-defective HIV-1 infection blocked apoptosis in cells treated with UV light or etoposide but not cell death induced by CD95 antibody, TRAIL, Ly294002, or serum starvation. Our results show that HIV-1 infection inhibits DNA damage-induced but not death receptor-dependent cell death by a Nef-independent mechanism.

scholarly journals Human immunodeficiency virus type 1 (HIV-1) Vpr-regulated cell death: insights into mechanism

2005 ◽  
Vol 12 (S1) ◽  
pp. 962-970 ◽  
Author(s):  
K Muthumani ◽  
A Y Choo ◽  
A Premkumar ◽  
D S Hwang ◽  
K P Thieu ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Death ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Regulated Cell Death ◽  
Immunodeficiency Virus ◽  
Hiv 1
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