Evidence for a Pathogenic Determinant in HIV-1 Nef Involved in B Cell Dysfunction in HIV/AIDS

Swingler, Simon; Zhou, Jian‐Liang; Swingler, Catherine; Dauphin, Ann; Greenough, Thomas C.; Jolicoeur, Paul; Stevenson, Mario

doi:10.1016/j.chom.2008.05.015

Cited by 70 publications

(60 citation statements)

References 44 publications

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“…1B, red bars), whereas infection of macrophages with Dnef-HIV-1 was slightly higher than infection with wt-HIV-1 (Fig. 1B, gray bars), as previously reported (49). Further analysis of the number of nuclei per cell showed that Dnef-HIV-1-infected macrophages formed fewer cells with a high number of nuclei than wt-HIV-1-infected macrophages (Fig.…”

Section: Nef Is Involved In the Formation Of Mgcs By Hiv-1-infected Hsupporting

confidence: 60%

HIV-1 Nef Triggers Macrophage Fusion in a p61Hck- and Protease-Dependent Manner

Vérollet

Zhang

Cabec

et al. 2010

The Journal of Immunology

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Macrophages are a major target of HIV-1 infection. HIV-1–infected macrophages form multinucleated giant cells (MGCs) using poorly elucidated mechanisms. In this study, we show that MGC formation was reduced when human macrophages were infected with nef-deleted HIV-1. Moreover, expression of Nef, an HIV-1 protein required in several aspects of AIDS, was sufficient to trigger the formation of MGCs in RAW264.7 macrophages. Among Nef molecular determinants, myristoylation was dispensable, whereas the polyproline motif was instrumental for this phenomenon. Nef has been shown to activate hematopoietic cell kinase (Hck), a Src tyrosine kinase specifically expressed in phagocytes, through a well-described polyproline–SH3 interaction. Knockdown approaches showed that Hck is involved in Nef-induced MGC formation. Hck is expressed as two isoforms located in distinct subcellular compartments. Although both isoforms were activated by Nef, only p61Hck mediated the effect of Nef on macrophage fusion. This process was abolished in the presence of a p61Hck kinase-dead mutant or when p61Hck was redirected from the lysosome membrane to the cytosol. Finally, lysosomal proteins including vacuolar adenosine triphosphatase and proteases participated in Nef-induced giant macrophage formation. We conclude that Nef participates in HIV-1–induced MGC formation via a p61Hck- and lysosomal enzyme-dependent pathway. This work identifies for the first time actors of HIV-1–induced macrophage fusion, leading to the formation of MGCs commonly found in several organs of AIDS patients.

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Section: Nef Is Involved In the Formation Of Mgcs By Hiv-1-infected Hsupporting

confidence: 60%

HIV-1 Nef Triggers Macrophage Fusion in a p61Hck- and Protease-Dependent Manner

Vérollet

Zhang

Cabec

et al. 2010

The Journal of Immunology

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“…Macrophages were then infected with different doses of HIV-1 ADA WT or nef-deleted HIV-1 ADA (HIV-1 ADA ⌬Nef) for 4 to 12 days, and the culture supernatant was analyzed every 2 days by enzyme-linked immunosorbent assay for p24 production. As described previously, 31,32 HIV-1 wild-type and nef-deleted variants replicate with similar kinetics in macrophages with a peak of viral production 8 days after infection (supplemental Figure 1B). We therefore infected macrophages for 8 days with HIV-1 ADA WT or HIV-1 ADA ⌬Nef before submitting the cells to phagocytic assays.…”

Section: Inhibition Of Phagocytic Activity Of Primary Human Macrophagmentioning

confidence: 93%

Inhibition of phagocytosis in HIV-1–infected macrophages relies on Nef-dependent alteration of focal delivery of recycling compartments

Mazzolini

Herit

Bouchet

et al. 2010

Blood

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Phagocytosis in macrophages is receptor mediated and relies on actin polymerization coordinated with the focal delivery of intracellular membranes that is necessary for optimal phagocytosis of large particles. Here we show that phagocytosis by various receptors was inhibited in primary human macrophages infected with wild-type HIV-1 but not with a nefdeleted virus. We observed no major perturbation of F-actin accumulation, but adaptor protein 1 (AP1)-positive endosome recruitment was inhibited in HIV-1-infected cells. Expression of negative factor (Nef) was sufficient to inhibit phagocytosis, and myristoylation as well as the LL and DD motifs involved in association of Nef with AP complexes were important for this inhibition. We observed that Nef interferes with AP1 in association with membranes and/or with a cleaved regulatory form of AP1. Finally, an alteration of the recruitment of vesicleassociated membrane protein (VAMP3)-and tumor necrosis factor-␣ (TNF␣)-positive recycling endosomes regulated by AP1, but not of VAMP7-positive late endosomes, was observed in phagocytic cups of HIV-1-infected macrophages. We conclude that HIV-1 impairs optimal phagosome formation through Nefdependent perturbation of the endosomal remodeling relying on AP1. We therefore identified a mechanism of macrophage function down-regulation in infected cells. IntroductionMacrophages play crucial functions at the interface between innate and adaptive immunity. They recognize, take up, and degrade microorganisms and are responsible for clearance of cell debris during developmental processes, elimination of dead red blood cells in the liver, as well as clearance of pathogenic microorganisms. They also participate in the generation of specific adaptive immune responses by presenting microbial-derived peptides associated with major histocompatibility complex class II (MHC II ) to T lymphocytes and by secreting proinflammatory cytokines. 1 Macrophages possess a wide variety of receptors that sense and bind microorganisms, including receptors for surface determinants such as the Toll-like receptors, and receptors for mannose or beta glucans (Dectin-1). Other receptors recognize opsonins, molecules of the immune system covering the surface of microorganisms. Some of these receptors, including receptors for the Fc portion of immunoglobulins (crystallizable fragment receptor [FcR]) and complement receptor 3 (CR3) receptors have strong phagocytic capacities; their stimulation induces the efficient uptake of the bound microorganism. Phagocytosis induced by FcRs is the best characterized pathway. It activates a signaling cascade that involves small guanosine-5Ј-triphosphate-binding proteins of the Rho and adenosine diphosphate-ribosylation factor families and eventually leads to actin polymerization, plasma membrane remodeling, and extension of pseudopods around the particle. [2][3][4][5] Extension of the plasma membrane around large particles is supported by a process of internal membrane delivery that involves the fusion machinery relying on ve...

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“…Indeed, B-cell dysfunction characterized already at early stages of HIV-1 infection by the lack of highaffinity antibodies is increasingly recognized as a hallmark of AIDS pathogenesis (38,39). Nef is suggested to contribute to this phenomenon by impairing antigen presentation and prevention of B-cell class switching following transfer from infected cells (40)(41)(42)(43). The results presented herein, in line with those from other laboratories (44,45), suggest that Nef also suppresses B-cell help by HIV-1-infected T lymphocytes.…”

Section: Discussionmentioning

confidence: 99%

HIV-1 Nef interferes with T-lymphocyte circulation through confined environments in vivo

Stolp

Imle

Coelho

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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HIV-1 negative factor (Nef) elevates virus replication and contributes to immune evasion in vivo. As one of its established in vitro activities, Nef interferes with T-lymphocyte chemotaxis by reducing host cell actin dynamics. To explore Nef’s influence on in vivo recirculation of T lymphocytes, we assessed lymph-node homing of Nef-expressing primary murine lymphocytes and found a drastic impairment in homing to peripheral lymph nodes. Intravital imaging and 3D immunofluorescence reconstruction of lymph nodes revealed that Nef potently impaired T-lymphocyte extravasation through high endothelial venules and reduced subsequent parenchymal motility. Ex vivo analyses of transendothelial migration revealed that Nef disrupted T-lymphocyte polarization and interfered with diapedesis and migration in the narrow subendothelial space. Consistently, Nef specifically affected T-lymphocyte motility modes used in dense environments that pose high physical barriers to migration. Mechanistically, inhibition of lymph node homing, subendothelial migration and cell polarization, but not diapedesis, depended on Nef’s ability to inhibit host cell actin remodeling. Nef-mediated interference with in vivo recirculation of T lymphocytes may compromise T-cell help and thus represents an important mechanism for its function as a HIV pathogenicity factor.

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Evidence for a Pathogenic Determinant in HIV-1 Nef Involved in B Cell Dysfunction in HIV/AIDS

Cited by 70 publications

References 44 publications

HIV-1 Nef Triggers Macrophage Fusion in a p61Hck- and Protease-Dependent Manner

HIV-1 Nef Triggers Macrophage Fusion in a p61Hck- and Protease-Dependent Manner

Inhibition of phagocytosis in HIV-1–infected macrophages relies on Nef-dependent alteration of focal delivery of recycling compartments

HIV-1 Nef interferes with T-lymphocyte circulation through confined environments in vivo

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