Gp120 V3-dependent Impairment of R5 HIV-1 Infectivity Due to Virion-incorporated CCR5

HIV-1 incorporates various host membrane proteins during particle assembly at the plasma membrane; however, the mechanisms mediating this incorporation process remain poorly understood. We previously showed that the HIV-1 structural protein Gag localizes to the uropod, a rear-end structure of polarized T cells, and that assembling Gag copatches with a subset, but not all, of the uropod-directed proteins, i.e., PSGL-1, CD43, and CD44, in nonpolarized T cells. The latter observation suggests the presence of a mechanism promoting virion incorporation of these cellular proteins. To address this possibility and identify molecular determinants, in the present study we examined coclustering between Gag and the transmembrane proteins in T and HeLa cells using quantitative two-color superresolution localization microscopy. Consistent with the findings of the T-cell copatching study, we found that basic residues within the matrix domain of Gag are required for Gag-PSGL-1 coclustering. Notably, the presence of a polybasic sequence in the PSGL-1 cytoplasmic domain significantly enhanced this coclustering. We also found that polybasic motifs present in the cytoplasmic tails of CD43 and CD44 also promote their coclustering with Gag. ICAM-1 and ICAM-3, uropod-directed proteins that do not copatch with Gag in T cells, and CD46, a non-uropod-directed protein, showed no or little coclustering with Gag. However, replacing their cytoplasmic tails with the cytoplasmic tail of PSGL-1 significantly enhanced their coclustering with Gag. Altogether, these results identify a novel mechanism for host membrane protein association with assembling HIV-1 Gag in which polybasic sequences present in the cytoplasmic tails of the membrane proteins and in Gag are the major determinants. IMPORTANCENascent HIV-1 particles incorporate many host plasma membrane proteins during assembly. However, it is largely unknown what mechanisms promote the association of these proteins with virus assembly sites within the plasma membrane. Notably, our previous study showed that HIV-1 structural protein Gag colocalizes with a group of uropod-directed transmembrane proteins, PSGL-1, CD43, and CD44, at the plasma membrane of T cells. The results obtained in the current study using superresolution localization microscopy suggest the presence of a novel molecular mechanism promoting the association of PSGL-1, CD43, and CD44 with assembling HIV-1 which relies on polybasic sequences in HIV-1 Gag and in cytoplasmic domains of the transmembrane proteins. This information advances our understanding of virion incorporation of host plasma membrane proteins, some of which modulate virus spread positively or negatively, and suggests a possible new strategy to enrich HIV-1-based lentiviral vectors with a desired transmembrane protein. HIV-1 assembles at the plasma membrane in most cell types. The viral structural protein Gag, synthesized as a precursor polyprotein (Pr55), initiates and coordinates viral assembly at the plasma membrane. Membrane binding and targeting of ...

mentioning

confidence: 60%

Basic Motifs Target PSGL-1, CD43, and CD44 to Plasma Membrane Sites Where HIV-1 Assembles

Grover

Veatch

Ono

2015

“…In total, we cloned 31 different V3 sequences from 30 individuals, of which 14 (45.2%) were below the 5% FPR cutoff, suggesting a high frequency of CXCR4 usage in this area (Table 1). To confirm coreceptor usage using phenotypic assays, we produced luciferase reporter HIV-1 pseudotyped with Env that carried each V3 region in its strain JR-FL background (38,39). We used these viruses to infect NP-2/CD4 cells that expressed either CCR5 or CXCR4 (Table 1).…”

Section: Resultsmentioning

confidence: 99%

“…The amplified fragment carrying the AflII and NheI sites was cloned into a pCR-TOPO vector (Invitrogen) and sequenced. The AflII-NheI-carrying fragment of the V3 region was then introduced into the AflII-NheI cloning site of the pCXN-FLan vector as previously described (39,75). A luciferase reporter HIV-1 pseudotyped with Env carrying the V3 region or full-length Env was prepared by transfecting 293T cells with pNL-LucΔBglII and each Env expression vector (25,38,(75)(76)(77).…”

Section: Methodsmentioning

confidence: 99%

Existence of Replication-Competent Minor Variants with Different Coreceptor Usage in Plasma from HIV-1-Infected Individuals

Maeda

Takemura

Chikata

et al. 2020

Self Cite

Cell entry by HIV-1 is mediated by its principal receptor, CD4, and a coreceptor, either CCR5 or CXCR4, with viral envelope glycoprotein gp120. Generally, CCR5-using HIV-1 variants, called R5, predominate over most of the course of infection, while CXCR4-using HIV-1 variants (variants that utilize both CCR5 and CXCR4 [R5X4, or dual] or CXCR4 alone [X4]) emerge at late-stage infection in half of HIV-1-infected individuals and are associated with disease progression. Although X4 variants also appear during acute-phase infection in some cases, these variants apparently fall to undetectable levels thereafter. In this study, replication-competent X4 variants were isolated from plasma of drug treatment-naive individuals infected with HIV-1 strain CRF01_AE, which dominantly carries viral RNA (vRNA) of R5 variants. Next-generation sequencing (NGS) confirmed that sequences of X4 variants were indeed present in plasma vRNA from these individuals as a minor population. On the other hand, in one individual with a mixed infection in which X4 variants were dominant, only R5 replication-competent variants were isolated from plasma. These results indicate the existence of replication-competent variants with different coreceptor usage as minor populations. IMPORTANCE The coreceptor switch of HIV-1 from R5 to CXCR4-using variants (R5X4 or X4) has been observed in about half of HIV-1-infected individuals at late-stage infection with loss of CD4 cell count and disease progression. However, the mechanisms that underlie the emergence of CXCR4-using variants at this stage are unclear. In the present study, CXCR4-using X4 variants were isolated from plasma samples of HIV-1-infected individuals that dominantly carried vRNA of R5 variants. The sequences of the X4 variants were detected as a minor population using next-generation sequencing. Taken together, CXCR4-using variants at late-stage infection are likely to emerge when replication-competent CXCR4-using variants are maintained as a minor population during the course of infection. The present study may support the hypothesis that R5-to-X4 switching is mediated by the expansion of preexisting X4 variants in some cases.

“…We previously showed that the incorporation of larger amounts of HIV-1 coreceptor CCR5 into virions impaired the infectivity of HIV-1 when a CCR5-high CD4 ϩ T-cell line was infected with a distinct HIV-1 molecular clone, while a CCR5-low CD4 ϩ T-cell line was able to support virus infectivity (42). Because primary CD4…”

Section: Discussionmentioning

confidence: 99%

Separate Cellular Localizations of Human T-Lymphotropic Virus 1 (HTLV-1) Env and Glucose Transporter Type 1 (GLUT1) Are Required for HTLV-1 Env-Mediated Fusion and Infection

Maeda

Terasawa

Tanaka

et al. 2015

Self Cite

Interaction of the envelope glycoprotein (Env) of human T-lymphotropic virus 1 (HTLV-1) with the glucose transporter type 1 (GLUT1) expressed in target cells is essential for viral entry. This study found that the expression level of GLUT1 in virus-producing 293T cells was inversely correlated with HTLV-1 Env-mediated fusion activity and infectivity. Chimeric studies between GLUT1 and GLUT3 indicated that the extracellular loop 6 (ECL6) of GLUT1 is important for the inhibition of cell-cell fusion mediated by Env. When GLUT1 was translocated into the plasma membrane from intracellular storage sites by bafilomycin A1 (BFLA1) treatment in 293T cells, HTLV-1 Env-mediated cell fusion and infection also were inhibited without the overexpression of GLUT1, indicating that the localization of GLUT1 in intracellular compartments rather than in the plasma membrane is crucial for the fusion activity of HTLV-1 Env. Immunoprecipitation and laser scanning confocal microscopic analyses indicated that under normal conditions, HTLV-1 Env and GLUT1 do not colocalize or interact. BFLA1 treatment induced this colocalization and interaction, indicating that GLUT1 normally accumulates in intracellular compartments separate from that of Env. Western blot analyses of FLAGtagged HTLV-1 Env in virus-producing cells and the incorporation of HTLV-1 Env in virus-like particles (VLPs) indicate that the processing of Env is inhibited by either overexpression of GLUT1 or BFLA1 treatment in virus-producing 293T cells. This inhibition probably is due to the interaction of the Env with GLUT1 in intracellular compartments. Taken together, separate intracellular localizations of GLUT1 and HTLV-1 Env are required for the fusion activity and infectivity of HTLV-1 Env. IMPORTANCEThe deltaretrovirus HTLV-1 is a causative agent of adult T-cell leukemia (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Although HTLV-1 is a complex retrovirus that has accessory genes, no HTLV-1 gene product has yet been shown to regulate its receptor GLUT1 in virus-producing cells. In this study, we found that a large amount of GLUT1 or translocation of GLUT1 to the plasma membrane from intracellular compartments in virus-producing cells enhances the colocalization and interaction of GLUT1 with HTLV-1 Env, leading to the inhibition of cell fusion activity and infectivity. The results of our study suggest that GLUT1 normally accumulates in separate intracellular compartments from Env, which is indeed required for the proper processing of Env. Human T-lymphotropic virus 1 (HTLV-1) is a complex deltaretrovirus and a causative agent of adult T-cell leukemia (ATL) (62-64) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) (1, 2). The envelope glycoprotein (Env) of HTLV-1 is synthesized in virus-infected cells as a polyprotein precursor (gp62), which subsequently is cleaved by cellular proteinase(s) localized in the Golgi apparatus into two proteins, surface glycoprotein (gp46; SU) and transmembrane glycoprotein (gp21; TM...