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Signal transduction due to HIV-1 envelope interactions with chemokine receptors CXCR4 or CCR5.

Davis CB, Dikic I, Unutmaz D, Hill CM, Arthos J, Siani MA, Thompson DA, Schlessinger J, Littman DR - J. Exp. Med. (1997)

Bottom Line: In this study, we demonstrate that chemokines and HIV-1 envelope glycoproteins from both T-tropic and macrophage-tropic strains rapidly induce tyrosine phosphorylation of the protein tyrosine kinase Pyk2.The response requires CXCR4 and CCR5 to be accessible on the cell surface.The results presented here provide the first evidence for activation of an intracellular signaling event that can initiate multiple signaling pathways as a consequence of contact between HIV-1 and chemokine receptors.

View Article: PubMed Central - PubMed

Affiliation: Division of Molecular Pathogenesis, Skirball Institute for Biomolecular Medicine, NYU Medical Center 10016, USA. davis@saturn.med.nyu.edu

ABSTRACT
Infection with HIV-1 requires expression of CD4 and the chemokine receptors CXCR4 or CCR5 at the target cell surface. Engagement of these receptors by the HIV-1 envelope glycoprotein is essential for membrane fusion, but may additionally activate intracellular signaling pathways. In this study, we demonstrate that chemokines and HIV-1 envelope glycoproteins from both T-tropic and macrophage-tropic strains rapidly induce tyrosine phosphorylation of the protein tyrosine kinase Pyk2. The response requires CXCR4 and CCR5 to be accessible on the cell surface. The results presented here provide the first evidence for activation of an intracellular signaling event that can initiate multiple signaling pathways as a consequence of contact between HIV-1 and chemokine receptors.

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Tyrosine phosphorylation of Pyk2 after contact with HIV-1  envelope glycoprotein on the surface of transfected 293T cells and virions. (a) HL60 or DU6 cells were lysed 30 s after being mixed with 293T  cells expressing M-tropic (JRFL), T-tropic (HXB2), or no (−) envelope.  (b) DU6 cells were mixed with HIV–luc particles pseudotyped with either JRFL or VSV-G envelopes and lysed after 90 s. As a positive control,  MIP-1β was incubated with DU6 cells for 30 s before lysis.
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Figure 2: Tyrosine phosphorylation of Pyk2 after contact with HIV-1 envelope glycoprotein on the surface of transfected 293T cells and virions. (a) HL60 or DU6 cells were lysed 30 s after being mixed with 293T cells expressing M-tropic (JRFL), T-tropic (HXB2), or no (−) envelope. (b) DU6 cells were mixed with HIV–luc particles pseudotyped with either JRFL or VSV-G envelopes and lysed after 90 s. As a positive control, MIP-1β was incubated with DU6 cells for 30 s before lysis.

Mentions: We first determined whether HIV-1 envelope glycoprotein expressed on the surface of 293T cells could trigger Pyk2 phosphorylation in cells expressing the appropriate chemokine receptor. The 293T cells, which do not express Pyk2 (9, 15), were transfected with HIV-1 envelope expression constructs encoding the T-tropic HXB2 or the M-tropic JRFL envelope glycoproteins (22, 23). These cells were then mixed with HL60 cells, which can fuse with envelopes from T-tropic but not M-tropic HIV-1 strains (24), or DU6, which can be infected by both T-tropic and M-tropic HIV-1 strains (Davis, C.B., unpublished data). Tyrosine phosphorylation of Pyk2 was observed when HL60 cells were mixed with 293T transfectants expressing the HXB2, but not the JRFL, envelope glycoprotein (Fig. 2 a, left). In contrast, DU6 cells showed increased tyrosine phosphorylated Pyk2 when mixed with transfectants expressing either HXB2 or JRFL envelope glycoprotein (Fig. 2 a, right). To test whether cell contact with HIV-1 virions triggers phosphorylation of Pyk2, we made use of a system in which envelope-deficient HIV–luc reporter viruses can be coated with different viral envelopes (12). HIV–luc particles coated with JRFL envelope glycoprotein were mixed with DU6 T cells and analyzed for the status of Pyk2 phosphorylation (Fig. 2 b).As a control for nonspecific effects mediated by HIV–luc viral particles, DU6 cells were also mixed with HIV–luc coated with the VSV-G envelope, which mediates infection of cells via binding to sialic acid residues (25). HIV–luc coated with JRFL, but not with VSV-G, could induce tyrosine phosphorylation of Pyk2 (Fig. 2 b). Overall, these results indicate that Pyk2 is tyrosine phosphorylated when uninfected cells encounter envelope on the surface of virions or infected cells.


Signal transduction due to HIV-1 envelope interactions with chemokine receptors CXCR4 or CCR5.

Davis CB, Dikic I, Unutmaz D, Hill CM, Arthos J, Siani MA, Thompson DA, Schlessinger J, Littman DR - J. Exp. Med. (1997)

Tyrosine phosphorylation of Pyk2 after contact with HIV-1  envelope glycoprotein on the surface of transfected 293T cells and virions. (a) HL60 or DU6 cells were lysed 30 s after being mixed with 293T  cells expressing M-tropic (JRFL), T-tropic (HXB2), or no (−) envelope.  (b) DU6 cells were mixed with HIV–luc particles pseudotyped with either JRFL or VSV-G envelopes and lysed after 90 s. As a positive control,  MIP-1β was incubated with DU6 cells for 30 s before lysis.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2199136&req=5

Figure 2: Tyrosine phosphorylation of Pyk2 after contact with HIV-1 envelope glycoprotein on the surface of transfected 293T cells and virions. (a) HL60 or DU6 cells were lysed 30 s after being mixed with 293T cells expressing M-tropic (JRFL), T-tropic (HXB2), or no (−) envelope. (b) DU6 cells were mixed with HIV–luc particles pseudotyped with either JRFL or VSV-G envelopes and lysed after 90 s. As a positive control, MIP-1β was incubated with DU6 cells for 30 s before lysis.
Mentions: We first determined whether HIV-1 envelope glycoprotein expressed on the surface of 293T cells could trigger Pyk2 phosphorylation in cells expressing the appropriate chemokine receptor. The 293T cells, which do not express Pyk2 (9, 15), were transfected with HIV-1 envelope expression constructs encoding the T-tropic HXB2 or the M-tropic JRFL envelope glycoproteins (22, 23). These cells were then mixed with HL60 cells, which can fuse with envelopes from T-tropic but not M-tropic HIV-1 strains (24), or DU6, which can be infected by both T-tropic and M-tropic HIV-1 strains (Davis, C.B., unpublished data). Tyrosine phosphorylation of Pyk2 was observed when HL60 cells were mixed with 293T transfectants expressing the HXB2, but not the JRFL, envelope glycoprotein (Fig. 2 a, left). In contrast, DU6 cells showed increased tyrosine phosphorylated Pyk2 when mixed with transfectants expressing either HXB2 or JRFL envelope glycoprotein (Fig. 2 a, right). To test whether cell contact with HIV-1 virions triggers phosphorylation of Pyk2, we made use of a system in which envelope-deficient HIV–luc reporter viruses can be coated with different viral envelopes (12). HIV–luc particles coated with JRFL envelope glycoprotein were mixed with DU6 T cells and analyzed for the status of Pyk2 phosphorylation (Fig. 2 b).As a control for nonspecific effects mediated by HIV–luc viral particles, DU6 cells were also mixed with HIV–luc coated with the VSV-G envelope, which mediates infection of cells via binding to sialic acid residues (25). HIV–luc coated with JRFL, but not with VSV-G, could induce tyrosine phosphorylation of Pyk2 (Fig. 2 b). Overall, these results indicate that Pyk2 is tyrosine phosphorylated when uninfected cells encounter envelope on the surface of virions or infected cells.

Bottom Line: In this study, we demonstrate that chemokines and HIV-1 envelope glycoproteins from both T-tropic and macrophage-tropic strains rapidly induce tyrosine phosphorylation of the protein tyrosine kinase Pyk2.The response requires CXCR4 and CCR5 to be accessible on the cell surface.The results presented here provide the first evidence for activation of an intracellular signaling event that can initiate multiple signaling pathways as a consequence of contact between HIV-1 and chemokine receptors.

View Article: PubMed Central - PubMed

Affiliation: Division of Molecular Pathogenesis, Skirball Institute for Biomolecular Medicine, NYU Medical Center 10016, USA. davis@saturn.med.nyu.edu

ABSTRACT
Infection with HIV-1 requires expression of CD4 and the chemokine receptors CXCR4 or CCR5 at the target cell surface. Engagement of these receptors by the HIV-1 envelope glycoprotein is essential for membrane fusion, but may additionally activate intracellular signaling pathways. In this study, we demonstrate that chemokines and HIV-1 envelope glycoproteins from both T-tropic and macrophage-tropic strains rapidly induce tyrosine phosphorylation of the protein tyrosine kinase Pyk2. The response requires CXCR4 and CCR5 to be accessible on the cell surface. The results presented here provide the first evidence for activation of an intracellular signaling event that can initiate multiple signaling pathways as a consequence of contact between HIV-1 and chemokine receptors.

Show MeSH
Related in: MedlinePlus