title: Fyn and PTP-PEST-mediated regulation of Wiskott-Aldrich syndrome protein (WASp) tyrosine phosphorylation is required for coupling T cell antigen receptor engagement to WASp effector function and T cell activation.
abstract: Involvement of the Wiskott-Aldrich syndrome protein (WASp) in promoting cell activation requires its release from autoinhibitory structural constraints and has been attributed to WASp association with activated cdc42. Here, however, we show that T cell development and T cell receptor (TCR)-induced proliferation and actin polymerization proceed normally in WASp-/- mice expressing a WASp transgene lacking the cdc42 binding domain. By contrast, mutation of tyrosine residue Y291, identified here as the major site of TCR-induced WASp tyrosine phosphorylation, abrogated induction of WASp tyrosine phosphorylation and its effector activities, including nuclear factor of activated T cell transcriptional activity, actin polymerization, and immunological synapse formation. TCR-induced WASp tyrosine phosphorylation was also disrupted in T cells lacking Fyn, a kinase shown here to bind, colocalize with, and phosphorylate WASp. By contrast, WASp was tyrosine dephosphorylated by protein tyrosine phosphatase (PTP)-PEST, a tyrosine phosphatase shown here to interact with WASp via proline, serine, threonine phosphatase interacting protein (PSTPIP)1 binding. Although Fyn enhanced WASp-mediated Arp2/3 activation and was required for synapse formation, PTP-PEST combined with PSTPIP1 inhibited WASp-driven actin polymerization and synapse formation. These observations identify key roles for Fyn and PTP-PEST in regulating WASp and imply that inducible WASp tyrosine phosphorylation can occur independently of cdc42 binding, but unlike the cdc42 interaction, is absolutely required for WASp contributions to T cell activation.
authors.affiliation: Mount Sinai Hospital, 600 University Avenue, Room 656A, Toronto, Ontario M5G 1X5, Canada.
authors.forename: Karen
authors.initials: K
authors.lastname: Badour
authors.forename: Jinyi
authors.initials: J
authors.lastname: Zhang
authors.forename: Fabio
authors.initials: F
authors.lastname: Shi
authors.forename: Yan
authors.initials: Y
authors.lastname: Leng
authors.forename: Michael
authors.initials: M
authors.lastname: Collins
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Siminovitch
mesh_terms: D000818:Animals; D003433:Crosses, Genetic; D017353:Gene Deletion; D006801:Humans; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D019000:Phosphotyrosine / Q000378:metabolism; D054594:Protein Tyrosine Phosphatase, Non-Receptor Type 12; D017027:Protein Tyrosine Phosphatases / Q000502:physiology*; D011505:Protein-Tyrosine Kinases / Q000502:physiology; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D051076:Proto-Oncogene Proteins c-fyn; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D013601:T-Lymphocytes / Q000276:immunology*; D014923:Wiskott-Aldrich Syndrome / Q000276:immunology*; D051316:Wiskott-Aldrich Syndrome Protein
chemical_list: D011506:Proteins; D011518:Proto-Oncogene Proteins; D011948:Receptors, Antigen, T-Cell; C495767:WAS protein, human; C495768:Was protein, mouse; D051316:Wiskott-Aldrich Syndrome Protein; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases; C494957:FYN protein, human; C494960:Fyn protein, mouse; D051076:Proto-Oncogene Proteins c-fyn; C516738:PTPN12 protein, human; D054594:Protein Tyrosine Phosphatase, Non-Receptor Type 12; D017027:Protein Tyrosine Phosphatases; C516739:Ptpn12 protein, mouse