Regulation of Zap-70 by Src family tyrosine protein kinases in an antigen-specific T-cell line.
To further understand the interactions between Zap-70, Src family kinases, and other T-cell proteins, we have examined the regulation of Zap-70 in the antigen-specific T-cell line BI-141. By analyzing derivatives containing an activated version of either p56lck or p59fynT, it was observed that the two Src-related enzymes augmented T-cell receptor (TCR)-mediated tyrosine phosphorylation of Zap-70, as well as its association with components of the antigen receptor complex. Importantly, the accumulation of TCR.Zap-70 complexes quantitatively and temporally correlated with the induction of tyrosine phosphorylation of the CD3 and zeta chains of TCR. Using a CD4-positive variant of BI-141, we also found that the ability of Zap-70 to undergo tyrosine phosphorylation and associate with TCR was enhanced by aggregation of TCR with the CD4 co-receptor. Further studies allowed the identification of two distinct pools of tyrosine-phosphorylated Zap-70 in activated T-cells. While one population was associated with TCR, the other was co-immunoprecipitated with a 120-kDa tyrosine-phosphorylated protein of unknown identity. In addition to supporting the notion that Src-related enzymes regulate the recruitment of Zap-70 in TCR signaling, these data added further complexity to previous models of regulation of Zap-70. Furthermore, they suggested that p120 may be an effector and/or a regulator of Zap-70 in activated T-lymphocytes.
McGill Cancer Centre, McGill University, Montréal, Canada.
R
R
Weil
J F
JF
Cloutier
M
M
Fournel
A
A
Veillette
D000818:Animals; D000941:Antigens / Q000276:immunology; D017252:CD3 Complex / Q000378:metabolism; D002460:Cell Line; D008213:Lymphocyte Activation; D051379:Mice; D010766:Phosphorylation; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism; D051746:ZAP-70 Protein-Tyrosine Kinase
D000941:Antigens; D017252:CD3 Complex; D011948:Receptors, Antigen, T-Cell; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D051746:ZAP-70 Protein-Tyrosine Kinase; C497262:Zap70 protein, mouse