Ena/VASP Protein-Mediated Actin Polymerization Contributes to Naïve CD8+ T Cell Activation and Expansion by Promoting T Cell-APC Interactions In Vivo

Front Immunol. 2022 Jun 9;13:856977. doi: 10.3389/fimmu.2022.856977. eCollection 2022.


Naïve T cell activation in secondary lymphoid organs such as lymph nodes (LNs) occurs upon recognition of cognate antigen presented by antigen presenting cells (APCs). T cell activation requires cytoskeleton rearrangement and sustained interactions with APCs. Enabled/vasodilator-stimulated phosphoprotein (Ena/VASP) proteins are a family of cytoskeletal effector proteins responsible for actin polymerization and are frequently found at the leading edge of motile cells. Ena/VASP proteins have been implicated in motility and adhesion in various cell types, but their role in primary T cell interstitial motility and activation has not been explored. Our goal was to determine the contribution of Ena/VASP proteins to T cell-APC interactions, T cell activation, and T cell expansion in vivo. Our results showed that naïve T cells from Ena/VASP-deficient mice have a significant reduction in antigen-specific T cell accumulation following Listeria monocytogenes infection. The kinetics of T cell expansion impairment were further confirmed in Ena/VASP-deficient T cells stimulated via dendritic cell immunization. To investigate the cause of this T cell expansion defect, we analyzed T cell-APC interactions in vivo by two-photon microscopy and observed fewer Ena/VASP-deficient naïve T cells interacting with APCs in LNs during priming. We also determined that Ena/VASP-deficient T cells formed conjugates with significantly less actin polymerization at the T cell-APC synapse, and that these conjugates were less stable than their WT counterparts. Finally, we found that Ena/VASP-deficient T cells have less LFA-1 polarized to the T cell-APC synapse. Thus, we conclude that Ena/VASP proteins contribute to T cell actin remodeling during T cell-APC interactions, which promotes the initiation of stable T cell conjugates during APC scanning. Therefore, Ena/VASP proteins are required for efficient activation and expansion of T cells in vivo.

Keywords: EVL; T cell; T cell activation; T cell motility; VASP; cytoskeleton; immunological synapse; two-photon microscopy.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins* / immunology
  • Actins* / metabolism
  • Animals
  • CD8-Positive T-Lymphocytes* / immunology
  • CD8-Positive T-Lymphocytes* / metabolism
  • Cell Adhesion Molecules* / immunology
  • Cell Adhesion Molecules* / metabolism
  • Cytoskeletal Proteins
  • Lymphocyte Activation
  • Mice
  • Microfilament Proteins* / immunology
  • Microfilament Proteins* / metabolism
  • Phosphoproteins* / immunology
  • Phosphoproteins* / metabolism
  • Polymerization
  • T-Lymphocytes* / immunology
  • T-Lymphocytes* / metabolism


  • Actins
  • Cell Adhesion Molecules
  • Cytoskeletal Proteins
  • Microfilament Proteins
  • Phosphoproteins
  • vasodilator-stimulated phosphoprotein