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 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 HIV envelope tail truncation confers resistance to SERINC5 restriction

2021 ◽  
Vol 118 (21) ◽  
pp. e2101450118
Author(s):  
Tafhima Haider ◽  
Xenia Snetkov ◽  
Clare Jolly
Keyword(s):  
T Cells ◽  
Envelope Glycoprotein ◽  
Cytoplasmic Tail ◽  
Restriction Factor ◽  
Viral Fusion ◽  
Restriction Factors ◽  
Complete Resistance ◽  
Hiv Envelope ◽  
Hiv 1

SERINC5 is a potent lentiviral restriction factor that gets incorporated into nascent virions and inhibits viral fusion and infectivity. The envelope glycoprotein (Env) is a key determinant for SERINC restriction, but many aspects of this relationship remain incompletely understood, and the mechanism of SERINC5 restriction remains unresolved. Here, we have used mutants of HIV-1 and HIV-2 to show that truncation of the Env cytoplasmic tail (ΔCT) confers complete resistance of both viruses to SERINC5 and SERINC3 restriction. Critically, fusion of HIV-1 ΔCT virus was not inhibited by SERINC5 incorporation into virions, providing a mechanism to explain how EnvCT truncation allows escape from restriction. Neutralization and inhibitor assays showed ΔCT viruses have an altered Env conformation and fusion kinetics, suggesting that EnvCT truncation dysregulates the processivity of entry, in turn allowing Env to escape targeting by SERINC5. Furthermore, HIV-1 and HIV-2 ΔCT viruses were also resistant to IFITMs, another entry-targeting family of restriction factors. Notably, while the EnvCT is essential for Env incorporation into HIV-1 virions and spreading infection in T cells, HIV-2 does not require the EnvCT. Here, we reveal a mechanism by which human lentiviruses can evade two potent Env-targeting restriction factors but show key differences in the capacity of HIV-1 and HIV-2 to exploit this. Taken together, this study provides insights into the interplay between HIV and entry-targeting restriction factors, revealing viral plasticity toward mechanisms of escape and a key role for the long lentiviral EnvCT in regulating these processes.

scholarly journals Virological Synapse-Mediated Spread of Human Immunodeficiency Virus Type 1 between T Cells Is Sensitive to Entry Inhibition

2010 ◽  
Vol 84 (7) ◽  
pp. 3516-3527 ◽  
Author(s):  
Nicola Martin ◽  
Sonja Welsch ◽  
Clare Jolly ◽  
John A. G. Briggs ◽  
David Vaux ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cells ◽  
Virological Synapse ◽  
Viral Spread ◽  
Immunodeficiency Virus ◽  
Virological Synapses ◽  
Hiv 1 ◽  
Entry Inhibition ◽  
Cell Cell

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) can disseminate between CD4+ T cells via diffusion-limited cell-free viral spread or by directed cell-cell transfer using virally induced structures termed virological synapses. Although T-cell virological synapses have been well characterized, it is unclear whether this mode of viral spread is susceptible to inhibition by neutralizing antibodies and entry inhibitors. We show here that both cell-cell and cell-free viral spread are equivalently sensitive to entry inhibition. Fluorescence imaging analysis measuring virological synapse lifetimes and inhibitor time-of-addition studies implied that inhibitors can access preformed virological synapses and interfere with HIV-1 cell-cell infection. This concept was supported by electron tomography that revealed the T-cell virological synapse to be a relatively permeable structure. Virological synapse-mediated HIV-1 spread is thus efficient but is not an immune or entry inhibitor evasion mechanism, a result that is encouraging for vaccine and drug design.

scholarly journals HIV-1-Infected CD4+ T Cells Facilitate Latent Infection of Resting CD4+ T Cells through Cell-Cell Contact

Cell Reports ◽  
2018 ◽  
Vol 24 (8) ◽  
pp. 2088-2100 ◽  
Author(s):  
Luis M. Agosto ◽  
Melissa B. Herring ◽  
Walther Mothes ◽  
Andrew J. Henderson
Keyword(s):  
T Cells ◽  
Cd4 T Cells ◽  
Latent Infection ◽  
Cell Contact ◽  
Hiv 1 ◽  
Cell Cell

scholarly journals αII-spectrin in T cells is involved in the regulation of cell-cell contact leading to immunological synapse formation?

PLoS ONE ◽  
2017 ◽  
Vol 12 (12) ◽  
pp. e0189545 ◽  
Author(s):  
Justyna M. Meissner ◽  
Aleksander F. Sikorski ◽  
Tomasz Nawara ◽  
Jakub Grzesiak ◽  
Krzysztof Marycz ◽  
...  
Keyword(s):  
T Cells ◽  
Synapse Formation ◽  
Immunological Synapse ◽  
Cell Contact ◽  
Cell Cell

Proliferation of highly purified T cells in response to signaling via surface receptors requires cell-cell contact

1989 ◽  
Vol 9 (2) ◽  
pp. 151-158 ◽  
Author(s):  
David Schwartz ◽  
Richard C. K. Wong ◽  
Talal Chatila ◽  
Amin Arnaout ◽  
Richard Miller ◽  
...  
Keyword(s):  
T Cells ◽  
Cell Contact ◽  
Surface Receptors ◽  
Cell Cell

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 Control of exocytotic processes: cytological and physiological studies of trichocyst mutants in Paramecium tetraurelia.

1981 ◽  
Vol 88 (2) ◽  
pp. 301-311 ◽  
Author(s):  
M Lefort-Tran ◽  
K Aufderheide ◽  
M Pouphile ◽  
M Rossignol ◽  
J Beisson
Keyword(s):  
Plasma Membrane ◽  
Freeze Fracture ◽  
Cell Interaction ◽  
Secretory Vesicle ◽  
Secretory Process ◽  
Cell Contact ◽  
Paramecium Tetraurelia ◽  
Cytoplasmic Factor ◽  
And Function ◽  
Cell Cell

The trichocysts of Paramecium tetraurelia constitute a favorable system for studying secretory process because of the numerous available mutations that block, at various stages, the development of these secretory vesicles, their migration towards and interaction with the cell surface, and their exocytosis. Previous studies of several mutants provided information (a) on the assembly and function of the intramembranous particles arrays in the plasma membrane at trichocyst attachment sites, (b) on the autonomous motility of trichocysts, required for attachment to the cortex, and (c) on a diffusible cytoplasmic factor whose interaction with both trichocyst and plasma membrane is required for exocytosis to take place. We describe here the properties of four more mutants deficient in exocytosis ability, nd6, nd7, tam38, and tam6, which were analyzed by freeze-fracture, microinjection of trichocysts, and assay for repair of the mutational defect through cell-cell interaction during conjugation with wild-type cells. As well as providing confirmation of previous conclusions, our observations show that the mutations nd6 and tam6 (which display striking abnormalities in their plasma membrane particle arrays and are reparable through cell-cell contact but not by microinjection of cytoplasm) affect two distinct properties of the plasma membrane, whereas the other two mutations affect different properties of the trichocysts. Altogether, the mutants so far analyzed now provide a rather comprehensive view of the steps and functions involved in secretory processes in Paramecium and demonstrate that two steps of these processes, trichocyst attachment to the plasma membrane and exocytosis, depend upon specific properties of both the secretory vesicle and the plasma membrane.

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