Vav1 transduces TCR signals required for LFA‐1 function and cell polarization at the immunological synapse

• Published in: European journal of immunology Vol. 33; no. 3; pp. 790 - 797
• Main Authors: Ardouin, Laurence, Bracke, Madelon, Mathiot, Anne, Pagakis, Stamatis N., Norton, Trisha, Hogg, Nancy, Tybulewicz, Victor L. J.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY‐VCH Verlag 01.03.2003
• Subjects: Adhesion molecule; Antigen-Presenting Cells - physiology; cdc42 GTP-Binding Protein - physiology; Cell Cycle Proteins; Cell Polarity; Humans; Immunological synapse; Lymphocyte Function-Associated Antigen-1 - physiology; Proto-Oncogene Proteins - physiology; Proto-Oncogene Proteins c-vav; Receptors, Antigen, T-Cell - physiology; Signal transduction; Signal Transduction - physiology; Synapses - immunology; T lymphocyte; Thymus
• ISSN: 0014-2980; 1521-4141
• DOI: 10.1002/eji.200323858

Activation of T lineage cells through the TCR by peptide–MHC complexes on APC is critically dependent on rearrangement of the actin cytoskeleton. Vav1 is a guanine nucleotide exchange factor for members of the Rho/Rac family of GTPases which is activated following TCR stimulation, suggesting that it may transduce TCR signals to the activation of some or all actin‐controlled processes. Weshow that Vav1‐deficient double‐positive thymocytes are less efficient at forming conjugates with APC presenting agonist peptide than wild‐type cells are. Furthermore we demonstrate that Vav1 is required for TCR‐induced activation of the integrin LFA‐1, which is likely to explain the defect in conjugate formation. However, once Vav1‐deficient cells form a conjugate, the assembly of proteins into an immunological synapse at the conjugate interface is normal. In contrast, thymocyte polarization is defective in the absence of Vav1, as judged by the relocalization of the microtubule‐organizing center. These data demonstrate that Vav1 transduces signals to only a subset of cytoskeleton‐dependent events at the immunological synapse.