Evidence for inducible recruitment of Wiskott-Aldrich syndrome protein to T cell receptor-CD3 complex in Jurkat T cells.

Background: The engagement of the T cell receptor (TCR)-CD3 complex induces the formation of multiple signalling complexes, which are required for actin cytoskeletal rearrangement. The Wiskott-Aldrich syndrome protein (WASp) is a key regulator of actin polymerization that is recruited to the TCR activation site. Since WASp is a binding partner of adaptor protein Nck, which is recruited directly to the TCR CD3e subunit upon TCR ligation, therefore we proposed that the direct recruitment of Nck to TCR-CD3 may also bring WASp directly to TCR-CD3. Objective: The aim of this present study was to assess the distribution of WASp, in relation to Nck, to the TCR-CD3e complex. Methods: Jurkat T cells were stimulated with anti-TCR antibody and then the cell lysates were immunoprecipitated with anti-CD3 antibody before immunoblotting with antibodies specific to WASp, Nck1, Nck2, SLP-76 and CD3e molecules. Results: WASp was recruited to SLP-76 and also directly to the TCR-CD3 complex upon TCR triggering. The inducible recruitment of WASp to the TCR-CD3 complex is partially dependent of tyrosine phosphorylation.  Conclusions: The present findings provide an alternative mechanism of WASp recruitment to the site of TCR activation that may be involved in recruitment of Nck.