Ex vivo evidence for asymmetric tyrosine phosphorylation of ZAP-70 on double-positive thymocytes in the positive selection process.
Antigen stimulation via TCR in mature T cells provides rapid induction of tyrosine phosphorylation of intracellular substrates including ZAP-70. To study the potential involvement of tyrosine phosphorylation in CD4+CD8+ [double-positive (DP)] thymocytes in the positive selection process in vivo, we isolated and analyzed them in the presence of phosphatase inhibitor. DP thymocytes were obtained from TCR transgenic mice (TCR-Tg) expressing MHC class I- or class II-restricted TCR in selecting and non-selecting MHC backgrounds respectively. The phosphorylation of ZAP-70 in DP thymocytes of class I-restricted TCR-Tg was significantly higher in the positively selecting background than in the non-selecting one. However, such a phosphorylation difference between selecting and non-selecting TCR-Tg was found to be considerably less in class II-restricted TCR-Tg. A similar bias for ZAP-70 phosphorylation was also observed on selecting DP thymocytes when I-A(beta) deficient- and beta2-microglobulin-deficient mice were compared. These ex vivo studies suggest that TCR-mediated signaling on DP thymocytes induces ZAP-70 phosphorylation under a different manner of engagement of TCR to class I and class II molecules in the positive selection process.
Department of Immunology, Tokai University School of Medicine, Kanagawa, Japan.
Y
Y
Kametani
H
H
Goto
A
A
Kobori
T
T
Sato
K
K
Ando
K
K
Hozumi
T
T
Nishimura
T
T
Saito
T
T
Yamamoto
S
S
Habu
D000818:Animals; D000911:Antibodies, Monoclonal; D017252:CD3 Complex / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D002478:Cells, Cultured; D006649:Histocompatibility Antigens / Q000276:immunology; D007527:Isoenzymes / Q000378:metabolism; D008285:Major Histocompatibility Complex / Q000276:immunology; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D051966:Phospholipase C gamma; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism / Q000502:physiology; D015398:Signal Transduction; D016176:T-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism*; D013950:Thymus Gland / Q000276:immunology / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism; D014638:Vanadates / Q000494:pharmacology; D051746:ZAP-70 Protein-Tyrosine Kinase; D001613:beta 2-Microglobulin / Q000276:immunology
D000911:Antibodies, Monoclonal; D017252:CD3 Complex; D006649:Histocompatibility Antigens; D007527:Isoenzymes; D008565:Membrane Proteins; D011948:Receptors, Antigen, T-Cell; C054979:antigen T cell receptor, zeta chain; D001613:beta 2-Microglobulin; D019000:Phosphotyrosine; D014638:Vanadates; D011505:Protein-Tyrosine Kinases; D051746:ZAP-70 Protein-Tyrosine Kinase; C497262:Zap70 protein, mouse; D010738:Type C Phospholipases; D051966:Phospholipase C gamma