title: T cell receptor (TCR) engagement in apoptosis-defective, but interleukin 2 (IL-2)-producing, T cells results in impaired ZAP70/CD3-zeta association.
abstract: We have previously shown that a tyrosine to leucine replacement in the transmembrane region of T cell receptor (TCR)-beta results in a deficient induction of CD95-L and apoptosis upon TCR triggering in a transfected T cell line. By contrast, interleukin (IL)-2 production and the expression of CD25 and CD69 were normally induced. Since the mutation in TCR-beta also resulted in impaired association of CD3-zeta, it was proposed that this chain is specifically required for the induction of apoptosis. We now show that the deficient induction of CD95-L and apoptosis does not derive from a general lower production of second messengers, since intracellular Ca2+ fluxes and tyrosine phosphorylation of total proteins were elicited at wild-type levels. Unlike in T cell clones stimulated with partial agonists, both p21 and p18 forms of tyrosine-phosphorylated CD3-zeta were detected, although the overall level of tyrosine-phosphorylated CD3-zeta was low. More strikingly, inducible association of ZAP70 to CD3-zeta was strongly inhibited, despite a normal induction of ZAP70 tyrosine phosphorylation. Finally, ZAP70 was not concentrated near the plasma membrane in the apoptosis-deficient cells. These results suggest that CD3-zeta is necessary for engagement of a specific signaling pathway leading to CD95-L expression that also needs the recruitment of ZAP70.
authors.affiliation: Department of Immunology, Fundación Jiménez-Díaz, Avenida Reyes Católicos 2, 28040 Madrid, Spain.
authors.forename: A G
authors.initials: AG
authors.lastname: Sahuquillo
authors.forename: A
authors.initials: A
authors.lastname: Roumier
authors.forename: E
authors.initials: E
authors.lastname: Teixeiro
authors.forename: R
authors.initials: R
authors.lastname: Bragado
authors.forename: B
authors.initials: B
authors.lastname: Alarcón
mesh_terms: D017209:Apoptosis; D017252:CD3 Complex / Q000378:metabolism*; D002451:Cell Compartmentation; D002462:Cell Membrane / Q000378:metabolism; D002999:Clone Cells; D053222:Fas Ligand Protein; D006801:Humans; D007376:Interleukin-2 / Q000096:biosynthesis; D019169:Jurkat Cells; D008562:Membrane Glycoproteins / Q000378:metabolism; D009154:Mutation; D010750:Phosphoproteins / Q000378:metabolism; D019000:Phosphotyrosine / Q000378:metabolism; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics / Q000378:metabolism*; D015290:Second Messenger Systems; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology*; D051746:ZAP-70 Protein-Tyrosine Kinase
chemical_list: D017252:CD3 Complex; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D007376:Interleukin-2; D008562:Membrane Glycoproteins; D010750:Phosphoproteins; D016693:Receptors, Antigen, T-Cell, alpha-beta; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases; D051746:ZAP-70 Protein-Tyrosine Kinase; C497261:ZAP70 protein, human