TY - JOUR

T1 - MHC class I ligation of human T cells activates the ZAP70 and p56lck tyrosine kinases, leads to an alternative phenotype of the TCR/CD3 zeta-chain, and induces apoptosis

AU - Skov, S

AU - Bregenholt, S

AU - Claesson, Mogens Helweg

PY - 1997/4/1

Y1 - 1997/4/1

N2 - Cross-linking of MHC class I (MHC-I) molecules on human T cells induces signal-transduction events, including activation of tyrosine kinases, tyrosine phosphorylation of phospholipase C-gamma 1, and elevation of the intracellular free calcium concentration. In this study, we demonstrate that the ZAP70 tyrosine kinase is tyrosine phosphorylated in Jurkat T cells and in purified peripheral T cells after MHC-I ligation. The tyrosine-phosphorylated ZAP70 kinase exhibits a particular phenotype with low affinities for proteins at 21, 40, 60, and 120 kDa, proteins normally co-precipitated with ZAP70 after TCR/CD3 stimulation. The phosphorylation of ZAP70 after MHC-I ligation was dependent on TCR/CD3 surface expression. One of the natural substrates for ZAP70 is the zeta-chain dimer of the TCR/CD3 complex. MHC-I cross-linking induces a phosphorylated zeta-protein that migrates as a dimer at 42 kDa in SDS-PAGE and differs from the 38-kDa phosphorylated zeta-protein dimer induced by TCR/CD3 cross-linking. Furthermore, we demonstrate that the p56lck tyrosine kinase is tyrosine phosphorylated following MHC-I ligation, and that a p56lck-negative Jurkat T cell mutant does not induce phosphorylation of the zeta-chain and the ZAP70 kinase following MHC-I ligation. Previous studies have demonstrated that lack or diminished activation of ZAP70 is involved in the induction of anergy or apoptosis in T cells. Likewise, MHC-I cross-linking of Jurkat T cells results in growth arrest and induction of apoptosis that is strongly inhibited by herbimycin A, suggesting an essential role of tyrosine kinase activity in the process leading to apoptosis.

AB - Cross-linking of MHC class I (MHC-I) molecules on human T cells induces signal-transduction events, including activation of tyrosine kinases, tyrosine phosphorylation of phospholipase C-gamma 1, and elevation of the intracellular free calcium concentration. In this study, we demonstrate that the ZAP70 tyrosine kinase is tyrosine phosphorylated in Jurkat T cells and in purified peripheral T cells after MHC-I ligation. The tyrosine-phosphorylated ZAP70 kinase exhibits a particular phenotype with low affinities for proteins at 21, 40, 60, and 120 kDa, proteins normally co-precipitated with ZAP70 after TCR/CD3 stimulation. The phosphorylation of ZAP70 after MHC-I ligation was dependent on TCR/CD3 surface expression. One of the natural substrates for ZAP70 is the zeta-chain dimer of the TCR/CD3 complex. MHC-I cross-linking induces a phosphorylated zeta-protein that migrates as a dimer at 42 kDa in SDS-PAGE and differs from the 38-kDa phosphorylated zeta-protein dimer induced by TCR/CD3 cross-linking. Furthermore, we demonstrate that the p56lck tyrosine kinase is tyrosine phosphorylated following MHC-I ligation, and that a p56lck-negative Jurkat T cell mutant does not induce phosphorylation of the zeta-chain and the ZAP70 kinase following MHC-I ligation. Previous studies have demonstrated that lack or diminished activation of ZAP70 is involved in the induction of anergy or apoptosis in T cells. Likewise, MHC-I cross-linking of Jurkat T cells results in growth arrest and induction of apoptosis that is strongly inhibited by herbimycin A, suggesting an essential role of tyrosine kinase activity in the process leading to apoptosis.

KW - Antibodies, Monoclonal

KW - Apoptosis

KW - Benzoquinones

KW - Cell Division

KW - Enzyme Activation

KW - HLA Antigens

KW - Histocompatibility Antigens Class I

KW - Humans

KW - Immunophenotyping

KW - Jurkat Cells

KW - Lactams, Macrocyclic

KW - Lymphocyte Specific Protein Tyrosine Kinase p56(lck)

KW - Membrane Proteins

KW - Molecular Weight

KW - Phosphorylation

KW - Protein-Tyrosine Kinases

KW - Quinones

KW - Receptor-CD3 Complex, Antigen, T-Cell

KW - Receptors, Antigen, T-Cell

KW - T-Lymphocytes

KW - ZAP-70 Protein-Tyrosine Kinase

KW - src-Family Kinases

M3 - Journal article

C2 - 9120273

VL - 158

SP - 3189

EP - 3196

JO - Journal of Immunology

JF - Journal of Immunology

SN - 0022-1767

IS - 7

ER -