title: LFA-1 Engagement Triggers T Cell Polarization at the HIV-1 Virological Synapse.
abstract: HIV-1 efficiently disseminates by cell-cell spread at intercellular contacts called virological synapses (VS), where the virus preferentially assembles and buds. Cell-cell contact triggers active polarization of organelles and viral proteins within infected cells to the contact site to support efficient VS formation and HIV-1 spread; critically, however, which cell surface protein triggers contact-induced polarization at the VS remains unclear. Additionally, the mechanism by which the HIV-1 envelope glycoprotein (Env) is recruited to the VS remains ill defined. Here, we use a reductionist bead-coupled antibody assay as a model of the VS and show that cross-linking the integrin LFA-1 alone is sufficient to induce active T cell polarization and recruitment of the microtubule organizing center (MTOC) in HIV-1-infected cells. Mutant cell lines coupled with inhibitors demonstrated that LFA-1-induced polarization was dependent on the T cell kinase ZAP70. Notably, immunofluorescent staining of viral proteins revealed an accumulation of surface Env at sites of LFA-1 engagement, with intracellular Env localized to a Golgi compartment proximal to the polarized MTOC. Furthermore, blocking LFA-1-induced MTOC polarization through ZAP70 inhibition prevented intracellular Env polarization. Taken together, these data reveal that LFA-1 is a key determinant in inducing dynamic T cell remodeling to the VS and suggest a model in which LFA-1 engagement triggers active polarization of the MTOC and the associated Env-containing secretory apparatus to sites of cell-cell contact to support polarized viral assembly and egress for efficient cell-cell spread.
  
  
  OBJECTIVE
  HIV-1 causes AIDS by spreading within immune cells and depletion of CD4 T lymphocytes. Rapid spread between these cells occurs by highly efficient cell-cell transmission that takes place at virological synapses (VS). VS are characterized by striking T cell remodeling that is spatially associated with polarized virus assembly and budding at sites of cell contact. Here, we show that the integrin LFA-1 triggers organelle polarization and viral protein recruitment, facilitating formation of the VS, and that this requires the T cell kinase ZAP70. Taken together, these data suggest a mechanism by which HIV-1-infected T cells sense and respond to cell contact to polarize viral egress and promote cell-cell spread. Understanding how cell-cell spread is regulated may help reveal therapeutic targets to specifically block this mode of HIV-1 dissemination.
authors: Division of Infection and Immunity, University College London, London, United Kingdom.
authors: Shimona
authors: S
authors: Starling
authors: Division of Infection and Immunity, University College London, London, United Kingdom c.jolly@ucl.ac.uk.
authors: Clare
authors: http://orcid.org/0000-0002-4603-2281
authors: C
authors: Jolly
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism* / Q000821:virology*; D045744:Cell Line, Tumor; D015658:HIV Infections / Q000378:metabolism* / Q000821:virology; D015497:HIV-1 / Q000472:pathogenicity*; D006801:Humans; D019169:Jurkat Cells; D008213:Lymphocyte Activation / Q000502:physiology; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism*; D022101:Microtubule-Organizing Center / Q000378:metabolism; D019065:Virus Assembly / Q000502:physiology; D053586:Virus Internalization
chemical_list: D016169:Lymphocyte Function-Associated Antigen-1