Evidence for Cell-Surface Association Between Fusin and the CD4-gp120 Complex in Human Cell Lines

Lapham, Cheryl; Ouyang, Jun; Chandrasekhar, Bhaskar; Nguyen, Nga Y.; Dimitrov, Dimiter S.; Golding, Hana

doi:10.1126/science.274.5287.602

Cited by 352 publications

(259 citation statements)

References 12 publications

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“…Phosphorylation of the cytoplasmic tail of CXCR4 is likely responsible for the down-regulation of CXCR4, but this contention will have to be confirmed by substitution mutations of the PKC sites on the receptor. PMA-induced down-regulation of CD4 in the presence of GP120 required an accessory protein and it was recently shown that this accessory protein is likely CXCR4 (44,45). The results presented here suggest that this down-regulation may involve phosphorylation on the cytoplasmic tail of CXCR4.…”

Section: Fig 4 Desensitization Of Cxcr4supporting

confidence: 45%

Regulation of Human Chemokine Receptors CXCR4

Haribabu

Richardson

Fisher

et al. 1997

Journal of Biological Chemistry

261

100

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Members of the chemokine receptor family CCR5 and CXCR4 have recently been shown to be involved in the entry of human immunodeficiency virus (HIV) into target cells. Here, we investigated the regulation of CXCR4 in rat basophilic leukemia cells (RBL-2H3) stably transfected with wild type (Wt CXCR4) or a cytoplasmic tail deletion mutant (⌬Cyto CXCR4) of CXCR4. The ligand, stromal cell derived factor-1 (SDF-1) stimulated higher G-protein activation, inositol phosphate generation, and a more sustained calcium elevation in cells expressing ⌬Cyto CXCR4 relative to Wt CXCR4. SDF-1 and phorbol 12-myristate 13-acetate (PMA), but not a membrane permeable cAMP analog induced rapid phosphorylation as well as desensitization of Wt CXCR4. Phosphorylation of ⌬Cyto CXCR4 was not detected under any of these conditions. Despite lack of receptor phosphorylation, calcium mobilization by SDF-1 in ⌬Cyto CXCR4 cells was partially desensitized by prior treatment with SDF-1. Of interest, the rapid release of calcium was inhibited without affecting the sustained calcium elevation, indicating independent regulatory pathways for these processes. PMA completely inhibited phosphoinositide hydrolysis and calcium mobilization in Wt CXCR4 but only partially inhibited these responses in ⌬Cyto CXCR4. cAMP also partially inhibited these responses in both Wt CXCR4 and ⌬Cyto CXCR4. SDF-1, PMA, and cAMP caused phosphorylation of phospholipase C␤3 in Wt and ⌬Cyto CXCR4 cells. Both SDF-1 as well as PMA induced rapid internalization of Wt CXCR4. SDF-1 but not PMA induced internalization of ⌬Cyto CXCR4 albeit at reduced levels relative to Wt CXCR4. These results indicate that signaling and internalization of CXCR4 are regulated by receptor phosphorylation dependent and independent mechanisms. Desensitization of CXCR4 signaling, independent of receptor phosphorylation, appears to be a consequence of the phosphorylation of phospholipase C␤3.Chemokines are a group of proteins that mediate directed migration and activation of leukocytes (1). These have been classified into two main families, CXC or CC-chemokines. Two newly identified proteins define additional groups of C and CX3C chemokines based on the position of conserved cysteines (2, 3). Both CC and CXC chemokines bind to seven transmembrane G-protein-coupled receptors which transduce signals through heterotrimeric G-proteins (4). Several recent studies showed that chemokines play a significant role in human immunodeficiency virus (HIV-1) 1 infection and that the chemokine receptors CCR5 and CXCR4 along with CD4 act as major co-receptors for the macrophage tropic and T-cell tropic HIV-1 strains entry, respectively, into target cells (5-10). While the C-C chemokines such as MIP1␣, MIP1␤, and regulated upon activation, normal T expressed and secreted can activate CCR5 the CXC chemokine SDF-1 is the ligand for CXCR4 (11-13). Recently, CD4 independent infection by HIV-2 was shown to be mediated by CXCR4 (14). HIV-1 envelope glycoproteins interact with chemokine receptors in a CD4-dependent and in one case...

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Section: Fig 4 Desensitization Of Cxcr4supporting

confidence: 45%

Regulation of Human Chemokine Receptors CXCR4

Haribabu

Richardson

Fisher

et al. 1997

Journal of Biological Chemistry

261

100

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“…CXCR4 and CCR5 are present as homodimers and heterodimers at the plasma membrane (18)(19)(20). In addition, gp120-mediated CD4/CXCR4 and CD4/CCR5 association and clustering is reported (21)(22)(23). Nonetheless, little is known of how CCR5 expression influences the CD4/CXCR4 interaction, or of the molecular basis that underlies the differences in X4 strains infection relative to CCR5 levels at the cell surface.…”

mentioning

confidence: 99%

CCR5/CD4/CXCR4 oligomerization prevents HIV-1 gp120_IIIBbinding to the cell surface

Martínez-Muñoz

Barroso

Dyrhaug

et al. 2014

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

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CCR5 and CXCR4, the respective cell surface coreceptors of R5 and X4 HIV-1 strains, both form heterodimers with CD4, the principal HIV-1 receptor. Using several resonance energy transfer techniques, we determined that CD4, CXCR4, and CCR5 formed heterotrimers, and that CCR5 coexpression altered the conformation of both CXCR4/CXCR4 homodimers and CD4/CXCR4 heterodimers. As a result, binding of the HIV-1 envelope protein gp120 IIIB to the CD4/CXCR4/CCR5 heterooligomer was negligible, and the gp120-induced cytoskeletal rearrangements necessary for HIV-1 entry were prevented. CCR5 reduced HIV-1 envelope-induced CD4/ CXCR4-mediated cell-cell fusion. In nucleofected Jurkat CD4 cells and primary human CD4 + T cells, CCR5 expression led to a reduction in X4 HIV-1 infectivity. These findings can help to understand why X4 HIV-1 strains infection affect T-cell types differently during AIDS development and indicate that receptor oligomerization might be a target for previously unidentified therapeutic approaches for AIDS intervention.chemokine receptors | oligomer formation | FRET/BRET F or HIV-1 to enter a target cell, the viral envelope glycoprotein gp120 must interact with a set of cell surface molecules that include the primary receptor, CD4 (1), and a chemokine receptor (CCR5 or CXCR4) that acts as a coreceptor (2, 3). These molecules form CD4/chemokine receptor complexes, as deduced from coprecipitation data for CXCR4 or CCR5 with CD4 (4-8).Most HIV-1 variants isolated from newly infected individuals use CCR5 and CD4 to enter host cells; these M-tropic R5 strains are predominant in acute and asymptomatic phases of HIV infection. CD4 + T helper type 1 (Th1) cells, which express high CCR5 levels (9, 10), are implicated in maintaining asymptomatic status (11, 12). The "viral shift" from R5 to T-tropic X4 HIV-1 strains correlates with AIDS progression (13,14). X4 strains infect mainly CD4 + Th2 cells, which express little CCR5 and whose CXCR4 levels resemble those of Th1 cells (15,16), which suggests that cell susceptibility to HIV-1 infection depends on the CD4/coreceptor ratio and on receptor levels during cell activation and/or differentiation (17). CXCR4 and CCR5 are present as homodimers and heterodimers at the plasma membrane (18)(19)(20). In addition, gp120-mediated CD4/CXCR4 and CD4/CCR5 association and clustering is reported (21-23). Nonetheless, little is known of how CCR5 expression influences the CD4/CXCR4 interaction, or of the molecular basis that underlies the differences in X4 strains infection relative to CCR5 levels at the cell surface.Here, we identify CD4/CXCR4/CCR5 oligomers at the cell membrane, even in the absence of ligands. CCR5 expression in these complexes modifies the heterodimeric CD4/CXCR4 conformation and blocks gp120 IIIB binding, without altering binding of the CXCR4 ligand CXCL12 and its subsequent signaling. gp120 IIIB -triggered LIMK1 activation, cofilin dephosphorylation, and the actin cytoskeleton rearrangement necessary for cell-cell fusion were impeded in CD4/CXCR4/CCR5-expressing c...

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“…The receptor for stromal derived factor-␣ (SDF-1␣), CXCR4, appears to act as the primary coreceptor for entry of T-cell tropic strains of HIV (5), whereas CCR5, which functions as the receptor for the chemokines RANTES, MIP-1␣ and MIP-1␤, mediates entry of macrophage or M-tropic viruses (6). The simultaneous interaction of HIV envelope protein (gp120) with both the CD4 receptor and a chemokine receptor is required for viral entry, after exposure of a chemokine receptor-binding determinant mediated by the initial interaction of gp120 with CD4 (7)(8)(9)(10). However, there are examples of chemokine receptordependent but CD4-independent entry of virus (11)(12)(13)(14).…”

mentioning

confidence: 99%

Trafficking of the HIV Coreceptor CXCR4

Orsini¹,

Parent²,

Mundell

et al. 1999

Journal of Biological Chemistry

221

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The G protein-coupled chemokine receptor CXCR4 serves as the primary coreceptor for entry of T-cell tropic human immunodeficiency virus. CXCR4 undergoes tonic internalization as well as internalization in response to stimulation with phorbol esters and ligand (SDF-1␣). We investigated the trafficking of this receptor, and we attempted to define the residues of CXCR4 that were critical for receptor internalization. In both COS-1 and HEK-293 cells transiently overexpressing CXCR4, SDF-1␣ and phorbol esters (PMA) promoted rapid internalization of cell surface receptors as assessed by both enzyme-linked immunosorbent assay and immunofluorescence analysis. Expression of GRK2 and/or arrestins promoted modest additional CXCR4 internalization in response to both PMA and SDF. Both PMA-and SDF-mediated CXCR4 internalization was inhibited by coexpression of dominant negative mutants of dynamin-1 and arrestin-3. Arrestin was also recruited to the plasma membrane and appeared to colocalize with internalized receptors in response to SDF but not PMA. We then evaluated the ability of CXCR4 receptors containing mutations of serines and threonines, as well as a dileucine motif, within the C-terminal tail to be internalized and phosphorylated in response to either PMA or SDF-1␣. This analysis showed that multiple residues within the CXCR4 C-terminal tail appear to mediate both PMA-and SDF-1␣-mediated receptor internalization. The ability of coexpressed GRK2 and arrestins to promote internalization of the CXCR4 mutants revealed distinct differences between respective mutants and suggested that the integrity of the dileucine motif (Ile-328 and Leu-329) and serines 324, 325, 338, and 339 are critical for receptor internalization.

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Evidence for Cell-Surface Association Between Fusin and the CD4-gp120 Complex in Human Cell Lines

Cited by 352 publications

References 12 publications

Regulation of Human Chemokine Receptors CXCR4

Regulation of Human Chemokine Receptors CXCR4

CCR5/CD4/CXCR4 oligomerization prevents HIV-1 gp120_IIIBbinding to the cell surface

Trafficking of the HIV Coreceptor CXCR4

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Evidence for Cell-Surface Association Between Fusin and the CD4-gp120 Complex in Human Cell Lines

Cited by 352 publications

References 12 publications

Regulation of Human Chemokine Receptors CXCR4

Regulation of Human Chemokine Receptors CXCR4

CCR5/CD4/CXCR4 oligomerization prevents HIV-1 gp120IIIBbinding to the cell surface

Trafficking of the HIV Coreceptor CXCR4

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CCR5/CD4/CXCR4 oligomerization prevents HIV-1 gp120_IIIBbinding to the cell surface