title: CXCR4-tropic HIV-1 envelope glycoprotein functions as a viral chemokine in unstimulated primary CD4+ T lymphocytes.
abstract: Interaction of HIV-1 envelope glycoprotein gp120 with the chemokine receptor CXCR4 triggers not only viral entry but also an array of signal transduction cascades. Whether gp120 induces an incomplete or aberrant set of signals, or whether it can function as a full CXCR4 agonist, remains unclear. We report that, in unstimulated human primary CD4(+) T cells, the spectrum of signaling responses induced by gp120 through CXCR4 paralleled that induced by the natural ligand stromal cell-derived factor 1/CXCL12. gp120 activated heterotrimeric G proteins and the major G protein-dependent pathways, including calcium mobilization, phosphoinositide-3 kinase, and Erk-1/2 MAPK activation. Interestingly, gp120 caused rapid actin cytoskeleton rearrangements and profuse membrane ruffling, as evidenced by dynamic confocal imaging. This coordinated set of events resulted in a bona fide chemotactic response. Inactivated HIV-1 virions that harbored conformationally intact envelope glycoproteins also caused actin polymerization and chemotaxis, while similar virions devoid of envelope glycoproteins did not. Thus gp120, in monomeric as well as oligomeric, virion-associated form, elicited a complex cellular response that mimicked the effects of a chemokine. HIV-1 has therefore the capacity to dysregulate the vast CD4(+) T cell population that expresses CXCR4. In addition, HIV-1 may exploit its chemotactic properties to retain potential target cells and locally perturb their cytoskeleton, thereby facilitating viral transmission.
authors.affiliation: Viral Immunology Unit, Pasteur Institute, Paris, France.
authors.forename: Karl
authors.initials: K
authors.lastname: Balabanian
authors.forename: Julie
authors.initials: J
authors.lastname: Harriague
authors.forename: Christine
authors.initials: C
authors.lastname: Décrion
authors.forename: Bernard
authors.initials: B
authors.lastname: Lagane
authors.forename: Spencer
authors.initials: S
authors.lastname: Shorte
authors.forename: Françoise
authors.initials: F
authors.lastname: Baleux
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Virelizier
authors.forename: Fernando
authors.initials: F
authors.lastname: Arenzana-Seisdedos
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Chakrabarti
mesh_terms: D000199:Actins / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000276:immunology; D002634:Chemotaxis, Leukocyte / Q000276:immunology*; D003599:Cytoskeleton / Q000378:metabolism; D015699:HIV Envelope Protein gp120 / Q000502:physiology*; D015497:HIV-1 / Q000276:immunology*; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology; D020935:MAP Kinase Signaling System / Q000276:immunology; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000096:biosynthesis / Q000502:physiology; D019718:Receptors, CXCR4 / Q000819:agonists / Q000502:physiology*; D014771:Virion / Q000502:physiology
chemical_list: D000199:Actins; D015699:HIV Envelope Protein gp120; D019718:Receptors, CXCR4; D019869:Phosphatidylinositol 3-Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020962:Heterotrimeric GTP-Binding Proteins; D002118:Calcium