scholarly journals The Pathogenicity of Human Immunodeficiency Virus (HIV) Type 1 Nef in CD4C/HIV Transgenic Mice Is Abolished by Mutation of Its SH3-Binding Domain, and Disease Development Is Delayed in the Absence of Hck

2001 ◽  
Vol 75 (19) ◽  
pp. 9378-9392 ◽  
Author(s):  
Zaher Hanna ◽  
Xiaoduan Weng ◽  
Denis G. Kay ◽  
Johanne Poudrier ◽  
Clifford Lowell ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Molecular Mechanisms ◽  
Surface Expression ◽  
Binding Domain ◽  
Cell Surface Expression ◽  
Disease Development ◽  
Pathogenic Potential ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The human immunodeficiency virus type 1 (HIV-1) Nef protein is an important determinant of AIDS pathogenesis. We have previously reported that HIV-1 Nef is responsible for the induction of a severe AIDS-like disease in CD4C/HIV transgenic (Tg) mice. To understand the molecular mechanisms of this Nef-induced disease, we generated Tg mice expressing a mutated Nef protein in which the SH3 ligand-binding domain (P72XXP75XXP78) was mutated to A72XXA75XXQ78. This mutation completely abolished the pathogenic potential of Nef, although a partial downregulation of the CD4 cell surface expression was still observed in these Tg mice. We also studied whether Hck, one of the effectors previously found to bind to this PXXP motif of Nef, was involved in disease development. Breeding of Tg mice expressing wild-type Nef on an hck −/− (knockout) background did not abolish any of the pathological phenotypes. However, the latency of disease development was prolonged. These data indicate that an intact PXXP domain is essential for inducing an AIDS-like disease in CD4C/HIV Tg mice and suggest that interaction of a cellular effector(s) with this domain is required for the induction of this multiorgan disease. Our findings indicate that Hck is an important, but not an essential, effector of Nef and suggest that another factor(s), yet to be identified, may be more critical for disease development.

scholarly journals Costimulation of Naive CD8+ Lymphocytes Induces CD4 Expression and Allows Human Immunodeficiency Virus Type 1 Infection

1998 ◽  
Vol 72 (11) ◽  
pp. 9054-9060 ◽  
Author(s):  
Scott G. Kitchen ◽  
Yael D. Korin ◽  
Michael D. Roth ◽  
Alan Landay ◽  
Jerome A. Zack
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Rapid Disease Progression ◽  
Cd8 Cells ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) infection requires cell surface expression of CD4. Costimulation of CD8+/CD4− T lymphocytes by anti-CD3 and anti-CD28 antibodies or by allogeneic dendritic cells induced expression of CD4 and rendered these CD8 cells susceptible to HIV-1 infection. Naive CD45RA+ cells responded with greater expression of CD4 than did CD45RO+ cells. CD8+lymphocytes derived from fetal or newborn sources exhibited a greater tendency to express CD4, consistent with their naive states. This mechanism of infection suggests HIV-induced perturbation of the CD8 arm of the immune response and could explain the generally rapid disease progression seen in HIV-infected children.

scholarly journals Effect of Calcium-Modulating Cyclophilin Ligand on Human Immunodeficiency Virus Type 1 Particle Release and Cell Surface Expression of Tetherin

2009 ◽  
Vol 83 (24) ◽  
pp. 13032-13036 ◽  
Author(s):  
Mariana G. Bego ◽  
Mathieu Dubé ◽  
Johanne Mercier ◽  
Éric A. Cohen
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Surface ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Particle Release ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The human immunodeficiency virus type 1 (HIV-1) accessory protein Vpu enhances virus particle release by counteracting a host factor that retains virions at the surfaces of infected cells. It was recently demonstrated that cellular protein BST-2/CD317/Tetherin restricts HIV-1 release in a Vpu-dependent manner. Calcium-modulating cyclophilin ligand (CAML) was also proposed to be involved in this process. We investigated whether CAML is involved in cell surface expression of Tetherin. Here, we show that CAML overexpression in permissive Cos-7 cells or CAML depletion in restrictive HeLa cells has no effect on HIV-1 release or on Tetherin surface expression, indicating that CAML is not required for Tetherin-mediated restriction of HIV-1 release.

scholarly journals Nef-Induced CD4 Endocytosis in Human Immunodeficiency Virus Type 1 Host Cells: Role of p56lck Kinase

2009 ◽  
Vol 83 (14) ◽  
pp. 7117-7128 ◽  
Author(s):  
Nadine Laguette ◽  
Christelle Brégnard ◽  
Jérôme Bouchet ◽  
Alexandre Benmerah ◽  
Serge Benichou ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Surface ◽  
Surface Expression ◽  
Lymphoid Cells ◽  
Cell Surface Expression ◽  
Target Cells ◽  
Immunodeficiency Virus ◽  
Internalization Rate ◽  
Hiv 1

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) Nef interferes with the endocytic machinery to modulate the cell surface expression of CD4. However, the basal trafficking of CD4 is governed by different rules in the target cells of HIV-1: whereas CD4 is rapidly internalized from the cell surface in myeloid cells, CD4 is stabilized at the plasma membrane through its interaction with the p56 lck kinase in lymphoid cells. In this study, we showed that Nef was able to downregulate CD4 in both lymphoid and myeloid cell lines but that an increase in the internalization rate of CD4 could be observed only in lymphoid cells. Expression of p56 lck in nonlymphoid CD4-expressing cells restores the ability of Nef in order to increase the internalization rate of CD4. Concurrent with this observation, the expression of a p56 lck -binding-deficient mutant of CD4 in lymphoid cells abrogates the Nef-induced acceleration of CD4 internalization. We also show that the expression of Nef causes a decrease in the association of p56 lck with cell surface-expressed CD4. Regardless of the presence of p56 lck , the downregulation of CD4 by Nef was followed by CD4 degradation. Our results imply that Nef uses distinct mechanisms to downregulate the cell surface expression levels of CD4 in either lymphoid or myeloid target cells of HIV-1.

scholarly journals DC-SIGN Interactions with Human Immunodeficiency Virus Type 1 and 2 and Simian Immunodeficiency Virus

2001 ◽  
Vol 75 (10) ◽  
pp. 4664-4672 ◽  
Author(s):  
Stefan Pöhlmann ◽  
Frédéric Baribaud ◽  
Benhur Lee ◽  
George J. Leslie ◽  
Melissa D. Sanchez ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Surface ◽  
Lectin Binding ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Virus Binding ◽  
Expression Levels ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Dendritic cells (DCs) efficiently bind and transmit human immunodeficiency virus (HIV) to cocultured T cells and so may play an important role in HIV transmission. DC-SIGN, a novel C-type lectin that is expressed in DCs, has recently been shown to bind R5 HIV type 1 (HIV-1) strains and a laboratory-adapted X4 strain. To characterize the interaction of DC-SIGN with primate lentiviruses, we investigated the structural determinants of DC-SIGN required for virus binding and transmission to permissive cells. We constructed a panel of DC-SIGN mutants and established conditions which allowed comparable cell surface expression of all mutants. We found that R5, X4, and R5X4 HIV-1 isolates as well as simian immunodeficiency and HIV-2 strains bound to DC-SIGN and could be transmitted to CD4/coreceptor-positive cell types. DC-SIGN contains a single N-linked carbohydrate chain that is important for efficient cell surface expression but is not required for DC-SIGN-mediated virus binding and transmission. In contrast, C-terminal deletions removing either the lectin binding domain or the repeat region abrogated DC-SIGN function. Trypsin-EDTA treatment inhibited DC-SIGN mediated infection, indicating that virus was maintained at the surface of the DC-SIGN-expressing cells used in this study. Finally, quantitative fluorescence-activated cell sorting analysis of AU1-tagged DC-SIGN revealed that the efficiency of virus transmission was strongly affected by variations in DC-SIGN expression levels. Thus, variations in DC-SIGN expression levels on DCs could greatly affect the susceptibility of human individuals to HIV infection.

scholarly journals Role for CCR5Δ32 Protein in Resistance to R5, R5X4, and X4 Human Immunodeficiency Virus Type 1 in Primary CD4+ Cells

2004 ◽  
Vol 78 (5) ◽  
pp. 2277-2287 ◽  
Author(s):  
Lokesh Agrawal ◽  
Xihua Lu ◽  
Jin Qingwen ◽  
Zainab VanHorn-Ali ◽  
Ioan Vlad Nicolescu ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Mononuclear Cells ◽  
Genetic Resistance ◽  
Surface Expression ◽  
Mutant Protein ◽  
Cell Surface Expression ◽  
Wild Type ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT CCR5Δ32 is a loss-of-function mutation that abolishes cell surface expression of the human immunodeficiency virus (HIV) coreceptor CCR5 and provides genetic resistance to HIV infection and disease progression. Since CXCR4 and other HIV coreceptors also exist, we hypothesized that CCR5Δ32-mediated resistance may be due not only to the loss of CCR5 function but also to a gain-of-function mechanism, specifically the active inhibition of alternative coreceptors by the mutant CCR5Δ32 protein. Here we demonstrate that efficient expression of the CCR5Δ32 protein in primary CD4+ cells by use of a recombinant adenovirus (Ad5/Δ32) was able to down-regulate surface expression of both wild-type CCR5 and CXCR4 and to confer broad resistance to R5, R5X4, and X4 HIV type 1 (HIV-1). This may be important clinically, since we found that CD4+ cells purified from peripheral blood mononuclear cells of individuals who were homozygous for CCR5Δ32, which expressed the mutant protein endogenously, consistently expressed lower levels of CXCR4 and showed less susceptibility to X4 HIV-1 isolates than cells from individuals lacking the mutation. Moreover, CD4+ cells from individuals who were homozygous for CCR5Δ32 expressed the mutant protein in five of five HIV-exposed, uninfected donors tested but not in either of two HIV-infected donors tested. The mechanism of inhibition may involve direct scavenging, since we were able to observe a direct interaction of CCR5 and CXCR4 with CCR5Δ32, both by genetic criteria using the yeast two-hybrid system and by biochemical criteria using the coimmunoprecipitation of heterodimers. Thus, these results suggest that at least two distinct mechanisms may account for genetic resistance to HIV conferred by CCR5Δ32: the loss of wild-type CCR5 surface expression and the generation of CCR5Δ32 protein, which functions as a scavenger of both CCR5 and CXCR4.

scholarly journals Hemofiltrate CC Chemokine 1[9-74] Causes Effective Internalization of CCR5 and Is a Potent Inhibitor of R5-Tropic Human Immunodeficiency Virus Type 1 Strains in Primary T Cells and Macrophages

2002 ◽  
Vol 46 (4) ◽  
pp. 982-990 ◽  
Author(s):  
Jan Münch ◽  
Ludger Ständker ◽  
Stefan Pöhlmann ◽  
Frédéric Baribaud ◽  
Armin Papkalla ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cells ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Proteolytic Processing ◽  
Cell Surface Expression ◽  
Cc Chemokine ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Proteolytic processing of the abundant plasmatic human CC chemokine 1 (HCC-1) generates a truncated form, HCC-1[9-74], which is a potent agonist of CCR1, CCR3, and CCR5; promotes calcium influx and chemotaxis of T lymphoblasts, monocytes, and eosinophils; and inhibits infection by CCR5-tropic human immunodeficiency virus type 1 (HIV-1) isolates. In the present study we demonstrate that HCC-1[9-74] interacts with the second external loop of CCR5 and inhibits replication of CCR5-tropic HIV-1 strains in both primary T cells and monocyte-derived macrophages. Low concentrations of the chemokine, however, frequently enhanced the replication of CCR5-tropic HIV-1 isolates but not the replication of X4-tropic HIV-1 isolates. Only HCC-1[9-74] and HCC-1[10-74], but not other HCC-1 length variants, displayed potent anti-HIV-1 activities. Fluorescence-activated cell sorter analysis revealed that HCC-1[9-74] caused up to 75% down-regulation of CCR5 cell surface expression, whereas RANTES (regulated on activation, normal T-cell expressed and secreted) achieved a reduction of only about 40%. Studies performed with green fluorescent protein-tagged CCR5 confirmed that both HCC-1[9-74] and RANTES, but not full-length HCC-1, mediated specific internalization of the CCR5 HIV-1 entry cofactor. Our results demonstrate that the interaction with HCC-1[9-74] causes effective intracellular sequestration of CCR5, but they also indicate that the effect of HCC-1[9-74] on viral replication is subject to marked cell donor- and HIV-1 isolate-dependent variations.

scholarly journals Interaction between the Human Immunodeficiency Virus Type 1 Gag Matrix Domain and Phosphatidylinositol-(4,5)-Bisphosphate Is Essential for Efficient Gag Membrane Binding

2007 ◽  
Vol 82 (5) ◽  
pp. 2405-2417 ◽  
Author(s):  
Vineela Chukkapalli ◽  
Ian B. Hogue ◽  
Vitaly Boyko ◽  
Wei-Shau Hu ◽  
Akira Ono
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Molecular Mechanisms ◽  
Membrane Binding ◽  
Particle Assembly ◽  
Immunodeficiency Virus ◽  
The Impact ◽  
Hiv 1

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) particle assembly mediated by the viral structural protein Gag occurs predominantly on the plasma membrane (PM). Although it is known that the matrix (MA) domain of Gag plays a major role in PM localization, molecular mechanisms that determine the location of assembly remain to be elucidated. We observed previously that overexpression of polyphosphoinositide 5-phosphatase IV (5ptaseIV) that depletes PM phosphatidylinositol-(4,5)-bisphosphate [PI(4,5)P2] impairs virus particle production and redirects processed Gag to intracellular compartments. In this study, we examined the impact of PI(4,5)P2 depletion on the subcellular localization of the entire Gag population using Gag-fluorescent protein chimeras. Upon 5ptaseIV overexpression, in addition to perinuclear localization, Gag also showed a hazy cytosolic signal, suggesting that PI(4,5)P2 depletion impairs Gag membrane binding. Indeed, Gag was less membrane bound in PI(4,5)P2-depleted cells, as assessed by biochemical analysis. These observations are consistent with the hypothesis that Gag interacts with PI(4,5)P2. To examine a putative Gag interaction with PI(4,5)P2, we developed an in vitro binding assay using full-length myristoylated Gag and liposome-associated PI(4,5)P2. Using this assay, we observed that PI(4,5)P2 significantly enhances liposome binding of wild-type Gag. In contrast, a Gag derivative lacking MA did not require PI(4,5)P2 for efficient liposome binding. To analyze the involvement of MA in PI(4,5)P2 binding further, we examined MA basic amino acid substitution mutants. These mutants, previously shown to localize in perinuclear compartments, bound PI(4,5)P2-containing liposomes weakly. Altogether, these results indicate that HIV-1 Gag binds PI(4,5)P2 on the membrane and that the MA basic domain mediates this interaction.

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