scholarly journals Contact-Induced Mitochondrial Polarization Supports HIV-1 Virological Synapse Formation

2014 ◽  
Vol 89 (1) ◽  
pp. 14-24 ◽  
Author(s):  
Elisabetta Groppelli ◽  
Shimona Starling ◽  
Clare Jolly
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
Virological Synapse ◽  
Cell Contact ◽  
Target Cells ◽  
Cell Contacts ◽  
Cell Spread ◽  
Hiv 1 ◽  
Cell Cell

ABSTRACTRapid HIV-1 spread between CD4 T lymphocytes occurs at retrovirus-induced immune cell contacts called virological synapses (VS). VS are associated with striking T cell polarization and localized virus budding at the site of contact that facilitates cell-cell spread. In addition to this, spatial clustering of organelles, including mitochondria, to the contact zone has been previously shown. However, whether cell-cell contact specifically induces dynamic T cell remodeling during VS formation and what regulates this process remain unclear. Here, we report that contact between an HIV-1-infected T cell and an uninfected target T cell specifically triggers polarization of mitochondria concomitant with recruitment of the major HIV-1 structural protein Gag to the site of cell-cell contact. Using fixed and live-cell imaging, we show that mitochondrial and Gag polarization in HIV-1-infected T cells occurs within minutes of contact with target T cells, requires the formation of stable cell-cell contacts, and is an active, calcium-dependent process. We also find that perturbation of mitochondrial polarization impairs cell-cell spread of HIV-1 at the VS. Taken together, these data suggest that HIV-1-infected T cells are able to sense and respond to contact with susceptible target cells and undergo dynamic cytoplasmic remodeling to create a synaptic environment that supports efficient HIV-1 VS formation between CD4 T lymphocytes.IMPORTANCEHIV-1 remains one of the major global health challenges of modern times. The capacity of HIV-1 to cause disease depends on the virus's ability to spread between immune cells, most notably CD4 T lymphocytes. Cell-cell transmission is the most efficient way of HIV-1 spread and occurs at the virological synapse (VS). The VS forms at the site of contact between an infected cell and an uninfected cell and is characterized by polarized assembly and budding of virions and clustering of cellular organelles, including mitochondria. Here, we show that cell-cell contact induces rapid recruitment of mitochondria to the contact site and that this supports efficient VS formation and consequently cell-cell spread. Additionally, we observed that cell-cell contact induces a mitochondrion-dependent increase in intracellular calcium, indicative of cellular signaling. Taken together, our data suggest that VS formation is a regulated process and thus a potential target to block HIV-1 cell-cell spread.

scholarly journals Requirement for an Intact T-Cell Actin and Tubulin Cytoskeleton for Efficient Assembly and Spread of Human Immunodeficiency Virus Type 1

2007 ◽  
Vol 81 (11) ◽  
pp. 5547-5560 ◽  
Author(s):  
Clare Jolly ◽  
Ivonne Mitar ◽  
Quentin J. Sattentau
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cells ◽  
Plasma Membrane ◽  
T Cell ◽  
Immunodeficiency Virus ◽  
Fixed Cell ◽  
Cell Spread ◽  
Hiv 1 ◽  
Cell Cell

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) infection of CD4+ T cells leads to the production of new virions that assemble at the plasma membrane. Gag and Env accumulate in the context of lipid rafts at the inner and outer leaflets of the plasma membrane, respectively, forming polarized domains from which HIV-1 buds. HIV-1 budding can result in either release of cell-free virions or direct cell-cell spread via a virological synapse (VS). The recruitment of Gag and Env to these plasma membrane caps in T cells is poorly understood but may require elements of the T-cell secretory apparatus coordinated by the cytoskeleton. Using fixed-cell immunofluorescence labeling and confocal microscopy, we observed a high percentage of HIV-1-infected T cells with polarized Env and Gag in capped, lipid raft-like assembly domains. Treatment of infected T cells with inhibitors of actin or tubulin remodeling disrupted Gag and Env compartmentalization within the polarized raft-like domains. Depolymerization of the actin cytoskeleton reduced Gag release and viral infectivity, and actin and tubulin inhibitors reduced Env incorporation into virions. Live- and fixed-cell confocal imaging and assay of de novo DNA synthesis by real-time PCR allowed quantification of HIV-1 cell-cell transfer. Inhibition of actin and tubulin remodeling in infected cells interfered with cell-cell spread across a VS and reduced new viral DNA synthesis. Based on these data, we propose that HIV-1 requires both actin and tubulin components of the T-cell cytoskeleton to direct its assembly and budding and to elaborate a functional VS.

scholarly journals The envelope cytoplasmic tail regulates HIV-1 assembly and spread

2021 ◽  
Author(s):  
Xenia Snetkov ◽  
Tafhima Haider ◽  
Dejan Mesner ◽  
Nicholas Groves ◽  
Schuyler van Engelenburg ◽  
...  
Keyword(s):  
T Cells ◽  
Structural Integrity ◽  
Alpha Helix ◽  
Cytoplasmic Tail ◽  
Virological Synapse ◽  
Cell Contact ◽  
Viral Fusion ◽  
And Function ◽  
Hiv 1 ◽  
Cell Cell

AbstractThe HIV-1 envelope (Env) is an essential determinant of viral infectivity, tropism and spread between T cells. Lentiviral Env contain an unusually long 150 amino acid cytoplasmic tail (EnvCT) but the function of the EnvCT and conserved domains within it remain largely uncharacterised. Here we identified a highly conserved tryptophan motif at position 757 (W757) in the LLP-2 alpha helix of the EnvCT as a key determinant for HIV-1 replication and spread between T cells. Strikingly we find that mutating W757 had wide-ranging consequences including altering Env mobility in the plasma membrane, preventing Env and Gag recruitment to sites of cell-cell contact for virological synapse (VS) formation and cell-cell spread, and impeding viral fusion. Notably, W757 was also required for efficient virus budding, revealing a previously unappreciated role for the EnvCT in regulating HIV-1 assembly and egress. We conclude that W757 is a key residue that stabilises the structural integrity and function of Env, consistent with the recent model that this region of the EnvCT acts as a critical supporting baseplate for Env.

scholarly journals A Conserved Tryptophan in the Envelope Cytoplasmic Tail Regulates HIV-1 Assembly and Spread

Viruses ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 129
Author(s):  
Xenia Snetkov ◽  
Tafhima Haider ◽  
Dejan Mesner ◽  
Nicholas Groves ◽  
Schuyler B. van Engelenburg ◽  
...  
Keyword(s):  
T Cells ◽  
Single Molecule ◽  
Virus Assembly ◽  
Alpha Helix ◽  
Cytoplasmic Tail ◽  
Virological Synapse ◽  
Cell Contact ◽  
Viral Spread ◽  
Hiv 1 ◽  
Cell Cell

The HIV-1 envelope (Env) is an essential determinant of viral infectivity, tropism and spread between T cells. Lentiviral Env contain an unusually long 150 amino acid cytoplasmic tail (EnvCT), but the function of the EnvCT and many conserved domains within it remain largely uncharacterised. Here, we identified a highly conserved tryptophan motif at position 757 (W757) in the LLP-2 alpha helix of the EnvCT as a key determinant for HIV-1 replication and spread between T cells. Alanine substitution at this position potently inhibited HIV-1 cell–cell spread (the dominant mode of HIV-1 dissemination) by preventing recruitment of Env and Gag to sites of cell–cell contact, inhibiting virological synapse (VS) formation and spreading infection. Single-molecule tracking and super-resolution imaging showed that mutation of W757 dysregulates Env diffusion in the plasma membrane and increases Env mobility. Further analysis of Env function revealed that W757 is also required for Env fusion and infectivity, which together with reduced VS formation, result in a potent defect in viral spread. Notably, W757 lies within a region of the EnvCT recently shown to act as a supporting baseplate for Env. Our data support a model in which W757 plays a key role in regulating Env biology, modulating its temporal and spatial recruitment to virus assembly sites and regulating the inherent fusogenicity of the Env ectodomain, thereby supporting efficient HIV-1 replication and spread.

scholarly journals HIV Infection Stabilizes Macrophage-T Cell Interactions To Promote Cell-Cell HIV Spread

2019 ◽  
Vol 93 (18) ◽  
Author(s):  
Paul Lopez ◽  
Wan Hon Koh ◽  
Ryan Hnatiuk ◽  
Thomas T. Murooka
Keyword(s):  
T Cells ◽  
T Cell ◽  
Live Cell Imaging ◽  
Cell Contact ◽  
Cell Infection ◽  
Cell Contacts ◽  
3 Dimensional ◽  
Viral Spread ◽  
Large Numbers ◽  
Cell Cell

ABSTRACTMacrophages are susceptible to HIV infection and play an important role in viral dissemination through cell-cell contacts with T cells. However, our current understanding of macrophage-to-T cell HIV transmission is derived from studies that do not consider the robust migration and cell-cell interaction dynamics between these cells. Here, we performed live-cell imaging studies in 3-dimensional (3D) collagen that allowed CD4+T cells to migrate and to locate and engage HIV-infected macrophages, modeling the dynamic aspects of thein situenvironment in which these contacts frequently occur. We show that HIV+macrophages form stable contacts with CD4+T cells that are facilitated by both gp120-CD4 and LFA-1–ICAM-1 interactions and that prolonged contacts are a prerequisite for efficient viral spread. LFA-1–ICAM-1 adhesive contacts function to restrain highly motile T cells, since their blockade substantially destabilized macrophage-T cell contacts, resulting in abnormal tethering events that reduced cell-cell viral spread. HIV-infected macrophages displayed strikingly elongated podosomal extensions that were dependent on Nef expression but were dispensable for stable cell-cell contact formation. Finally, we observed persistent T cell infection in dynamic monocyte-derived macrophage (MDM)-T cell cocultures in the presence of single high antiretroviral drug concentrations but achieved complete inhibition with combination therapy. Together, our data implicate macrophages as drivers of T cell infection by altering physiological MDM-T cell contact dynamics to access and restrain large numbers of susceptible, motile T cells within lymphoid tissues.IMPORTANCEOnce HIV enters the lymphoid organs, exponential viral replication in T cells ensues. Given the densely packed nature of these tissues, where infected and uninfected cells are in nearly constant contact with one another, efficient HIV spread is thought to occur through cell-cell contactsin vivo. However, this has not been formally demonstrated. In this study, we performed live-cell imaging studies within a 3-dimensional space to recapitulate the dynamic aspects of the lymphoid microenvironment and asked whether HIV can alter the morphology, migration capacity, and cell-cell contact behaviors between macrophages and T cells. We show that HIV-infected macrophages can engage T cells in stable contacts through binding of virus- and host-derived adhesive molecules and that stable macrophage-T cell contacts were required for high viral spread. Thus, HIV alters physiological macrophage-T cell interactions in order to access and restrain large numbers of susceptible, motile T cells, thereby playing an important role in HIV progression.

scholarly journals Visualization of HIV T Cell Virological Synapses and Virus-Containing Compartments by Three-Dimensional Correlative Light and Electron Microscopy

2016 ◽  
Vol 91 (2) ◽  
Author(s):  
Lili Wang ◽  
Edward T. Eng ◽  
Kenneth Law ◽  
Ronald E. Gordon ◽  
William J. Rice ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
T Cell ◽  
Ion Beam ◽  
Light And Electron Microscopy ◽  
Viral Proteins ◽  
Virological Synapse ◽  
Cell Contact ◽  
Target Cells ◽  
Virological Synapses ◽  
Hiv 1

ABSTRACT Virological synapses (VS) are adhesive structures that form between infected and uninfected cells to enhance the spread of HIV-1. During T cell VS formation, viral proteins are actively recruited to the site of cell-cell contact where the viral material is efficiently translocated to target cells into heterogeneous, protease-resistant, antibody-inaccessible compartments. Using correlative light and electron microscopy (CLEM), we define the membrane topography of the virus-containing compartments (VCC) where HIV is found following VS-mediated transfer. Focused ion beam scanning electron microscopy (FIB-SEM) and serial sectioning transmission electron microscopy (SS-TEM) were used to better resolve the fluorescent Gag-containing structures within the VCC. We found that small punctate fluorescent signals correlated with single viral particles in enclosed vesicular compartments or surface-localized virus particles and that large fluorescent signals correlated with membranous Gag-containing structures with unknown pathological function. CLEM imaging revealed distinct pools of newly deposited viral proteins within endocytic and nonendocytic compartments in VS target T cells. IMPORTANCE This study directly correlates individual virus-associated objects observed in light microscopy with ultrastructural features seen by electron microscopy in the HIV-1 virological synapse. This approach elucidates which infection-associated ultrastructural features represent bona fide HIV protein complexes. We define the morphology of some HIV cell-to-cell transfer intermediates as true endocytic compartments and resolve unique synapse-associated viral structures created by transfer across virological synapses.

scholarly journals LFA-1 Engagement Triggers T Cell Polarization at the HIV-1 Virological Synapse

2016 ◽  
Vol 90 (21) ◽  
pp. 9841-9854 ◽  
Author(s):  
Shimona Starling ◽  
Clare Jolly
Keyword(s):  
T Cell ◽  
Cell Polarization ◽  
Cell Contact ◽  
Cell Remodeling ◽  
T Cell Polarization ◽  
Infected Cells ◽  
Virological Synapses ◽  
Cell Spread ◽  
Hiv 1 ◽  
Cell Cell

ABSTRACTHIV-1 efficiently disseminates by cell-cell spread at intercellular contacts called virological synapses (VS), where the virus preferentially assembles and buds. Cell-cell contact triggers active polarization of organelles and viral proteins within infected cells to the contact site to support efficient VS formation and HIV-1 spread; critically, however, which cell surface protein triggers contact-induced polarization at the VS remains unclear. Additionally, the mechanism by which the HIV-1 envelope glycoprotein (Env) is recruited to the VS remains ill defined. Here, we use a reductionist bead-coupled antibody assay as a model of the VS and show that cross-linking the integrin LFA-1 alone is sufficient to induce active T cell polarization and recruitment of the microtubule organizing center (MTOC) in HIV-1-infected cells. Mutant cell lines coupled with inhibitors demonstrated that LFA-1-induced polarization was dependent on the T cell kinase ZAP70. Notably, immunofluorescent staining of viral proteins revealed an accumulation of surface Env at sites of LFA-1 engagement, with intracellular Env localized to a Golgi compartment proximal to the polarized MTOC. Furthermore, blocking LFA-1-induced MTOC polarization through ZAP70 inhibition prevented intracellular Env polarization. Taken together, these data reveal that LFA-1 is a key determinant in inducing dynamic T cell remodeling to the VS and suggest a model in which LFA-1 engagement triggers active polarization of the MTOC and the associated Env-containing secretory apparatus to sites of cell-cell contact to support polarized viral assembly and egress for efficient cell-cell spread.IMPORTANCEHIV-1 causes AIDS by spreading within immune cells and depletion of CD4 T lymphocytes. Rapid spread between these cells occurs by highly efficient cell-cell transmission that takes place at virological synapses (VS). VS are characterized by striking T cell remodeling that is spatially associated with polarized virus assembly and budding at sites of cell contact. Here, we show that the integrin LFA-1 triggers organelle polarization and viral protein recruitment, facilitating formation of the VS, and that this requires the T cell kinase ZAP70. Taken together, these data suggest a mechanism by which HIV-1-infected T cells sense and respond to cell contact to polarize viral egress and promote cell-cell spread. Understanding how cell-cell spread is regulated may help reveal therapeutic targets to specifically block this mode of HIV-1 dissemination.

scholarly journals Productive Infection of Neonatal CD8+ T Lymphocytes by HIV-1

1998 ◽  
Vol 187 (7) ◽  
pp. 1139-1144 ◽  
Author(s):  
Liang Peng Yang ◽  
James L. Riley ◽  
Richard G. Carroll ◽  
Carl H. June ◽  
James Hoxie ◽  
...  
Keyword(s):  
T Cells ◽  
Immune System ◽  
T Cell ◽  
T Lymphocytes ◽  
Hiv Infection ◽  
Cd8 T Cells ◽  
Productive Infection ◽  
Target Cells ◽  
Cd8 T Lymphocytes ◽  
Hiv 1

CD8+ T lymphocytes confer significant but ultimately insufficient protection against HIV infection. Here we report that activated neonatal CD8+ T cells can be productively infected in vitro by macrophage-tropic (M-tropic) HIV-1 isolates, which are responsible for disease transmission, whereas they are resistant to T cell–tropic (T-tropic) HIV strains. Physiological activation of CD8-α/β+ CD4− T cell receptor–α/β+ neonatal T cells, including activation by allogeneic dendritic cells, induces the accumulation of CD4 messenger RNA and the expression of CD4 Ag on the cell surface. The large majority of anti-CD3/B7.1–activated cord blood CD8+ T cells coexpress CD4, the primary HIV receptor, as well as CCR5 and CXCR4, the coreceptors used by M- and T-tropic HIV-1 strains, respectively, to enter target cells. These findings are relevant to the rapid progression of neonatal HIV infection. Infection of primary HIV-specific CD8+ T cells may compromise their survival and thus significantly contribute to the failure of the immune system to control the infection. Furthermore, these results indicate a previously unsuspected level of plasticity in the neonatal immune system in the regulation of CD4 expression by costimulation.

scholarly journals Shaping of T Cell Functions by Trogocytosis

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1155
Author(s):  
Masafumi Nakayama ◽  
Arisa Hori ◽  
Saori Toyoura ◽  
Shin-Ichiro Yamaguchi
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Antigen Processing ◽  
Cell Contact ◽  
Target Cells ◽  
Dependent Manner ◽  
Mhc Molecules ◽  
Cell Functions ◽  
Cell Cell

Trogocytosis is an active process whereby plasma membrane proteins are transferred from one cell to the other cell in a cell-cell contact-dependent manner. Since the discovery of the intercellular transfer of major histocompatibility complex (MHC) molecules in the 1970s, trogocytosis of MHC molecules between various immune cells has been frequently observed. For instance, antigen-presenting cells (APCs) acquire MHC class I (MHCI) from allografts, tumors, and virally infected cells, and these APCs are subsequently able to prime CD8+ T cells without antigen processing via the preformed antigen-MHCI complexes, in a process called cross-dressing. T cells also acquire MHC molecules from APCs or other target cells via the immunological synapse formed at the cell-cell contact area, and this phenomenon impacts T cell activation. Compared with naïve and effector T cells, T regulatory cells have increased trogocytosis activity in order to remove MHC class II and costimulatory molecules from APCs, resulting in the induction of tolerance. Accumulating evidence suggests that trogocytosis shapes T cell functions in cancer, transplantation, and during microbial infections. In this review, we focus on T cell trogocytosis and the related inflammatory diseases.

scholarly journals Modulation of the CCR5 Receptor/Ligand Axis by Seminal Plasma and the Utility of In Vitro versus In Vivo Models

2019 ◽  
Vol 93 (11) ◽  
Author(s):  
Jennifer A. Juno ◽  
Kathleen M. Wragg ◽  
Anne B. Kristensen ◽  
Wen Shi Lee ◽  
Kevin J. Selva ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Seminal Plasma ◽  
Target Cells ◽  
Ccr5 Expression ◽  
Ccr5 Receptor ◽  
The Impact ◽  
Hiv 1

ABSTRACT Sexual HIV-1 transmission occurs primarily in the presence of semen. Although data from macaque studies suggest that CCR5+ CD4+ T cells are initial targets for HIV-1 infection, the impact of semen on T cell CCR5 expression and ligand production remains inconclusive. To determine if semen modulates the lymphocyte CCR5 receptor/ligand axis, primary human T cell CCR5 expression and natural killer (NK) cell anti-HIV-1 antibody-dependent beta chemokine production was assessed following seminal plasma (SP) exposure. Purified T cells produce sufficient quantities of RANTES to result in a significant decline in CCR5bright T cell frequency following 16 h of SP exposure (P = 0.03). Meanwhile, NK cells retain the capacity to produce limited amounts of MIP-1α/MIP-1β in response to anti-HIV-1 antibody-dependent stimulation (median, 9.5% MIP-1α+ and/or MIP-1β+), despite the immunosuppressive nature of SP. Although these in vitro experiments suggest that SP-induced CCR5 ligand production results in the loss of surface CCR5 expression on CD4+ T cells, the in vivo implications are unclear. We therefore vaginally exposed five pigtail macaques to SP and found that such exposure resulted in an increase in CCR5+ HIV-1 target cells in three of the animals. The in vivo data support a growing body of evidence suggesting that semen exposure recruits target cells to the vagina that are highly susceptible to HIV-1 infection, which has important implications for HIV-1 transmission and vaccine design. IMPORTANCE The majority of HIV-1 vaccine studies do not take into consideration the impact that semen exposure might have on the mucosal immune system. In this study, we demonstrate that seminal plasma (SP) exposure can alter CCR5 expression on T cells. Importantly, in vitro studies of T cells in culture cannot replicate the conditions under which immune cells might be recruited to the genital mucosa in vivo, leading to potentially erroneous conclusions about the impact of semen on mucosal HIV-1 susceptibility.

Insights into the ontogeny and activation of T cells

1994 ◽  
Vol 40 (11) ◽  
pp. 2128-2131 ◽  
Author(s):  
T W Mak
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
Cell Surface ◽  
Immune Responses ◽  
Tyrosine Phosphatase ◽  
T Cell Development ◽  
Cell Development ◽  
Mutant Mice ◽  
Target Cells

Abstract T lymphocytes recognize antigen peptides and major histocompatibility complex products through their T-cell antigen receptors (TcR), consisting of alpha and beta chains. The interaction between T cells and their target cells or antigen-presenting cells is also assisted by a series of other cell-surface polypeptides, most notably CD4 and CD8, which are selectively expressed on mature helper/inducer and killer/suppressor T cells, respectively. Upon engagement of their ligands, a series of signals is transduced intracytoplasmically via some of these molecules and their associated proteins. Perhaps the most important enzyme in this signal transduction process is the lymphocyte-specific tyrosine kinase lck. Another important component is the cell-surface tyrosine phosphatase CD45. This molecule is alternatively spliced and the different isoforms are expressed on the various hematopoietic and lymphopoietic cells. Signaling through the TcR-CD4 D8-lck-CD45 complex is thought to be insufficient to activate T lymphocytes. A costimulatory signal is believed to be essential, and many investigators have suggested that CD28, a ligand for B7/BB1, is such a signal. Immune responses are also controlled by a number of cytokines and soluble factors. Signaling through the tumor necrosis factor receptor p55 is required for clearance of intracellular pathogens. Transcriptional factors involved in controlling interferon production are also important in T-cell development and immune responses. In an attempt to gain a better understanding of the roles of these molecules in T-lymphocyte functions and ontogeny, we generated a series of mutant mice with disruptions in the genes coding for these molecules. We are analyzing the mutant mice to evaluate the importance of these genes in T-cell development.

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