Induction of tyrosine phosphorylation and T-cell activation by vanadate peroxide, an inhibitor of protein tyrosine phosphatases.
Rapid tyrosine phosphorylation of key cellular proteins is a crucial event in the transduction of activation signals to T-lymphocytes. The regulatory role of protein tyrosine phosphatases (PTPases) in this process was explored by studying the effects of a powerful PTPase inhibitor, vanadate peroxide (pervanadate), on the activation cascade of Jurkat human leukaemic T-cells. Pervanadate induced activation of the tyrosine kinases lck and fyn (4- and 3-fold respectively) and a dramatic increase in tyrosine phosphorylation of cellular proteins, notably phospholipase C gamma 1. After this event, we observed a rise in intracellular Ca2+ concentration, corresponding to an influx. This effect required surface expression of the CD45 PTPase and was not observed in CD45-deficient variants of Jurkat cells. In the CD45-negative variant, the effect of pervanadate on tyrosine phosphorylation was globally decreased and some phosphorylated substrates were specifically missing. Pervanadate also stimulated transcription of the c-fos gene and accumulation of its mRNA as well as several other hallmarks of T-lymphocyte activation such as surface expression of the CD69 antigen and the interleukin 2 receptor alpha-chain (CD25). Pervanadate synergized with signals delivered by T-cell antigen receptor engagement or by a phorbol ester to induce interleukin 2 production. Pervanadate activated NF-kappa B, as shown by an increase in DNA-binding activity of this transcription factor. We thus conclude that PTPases play a crucial role in the negative regulation of signal transduction culminating in T-lymphocyte activation. Moreover, induction of tyrosine phosphorylation appears sufficient per se to initiate a complete activation programme.
Imbert
V
V
INSERM U364, Faculté de Médecine, Nice, France.
Peyron
J F
JF
Farahi Far
D
D
Mari
B
B
Auberger
P
P
Rossi
B
B
D001483:Base Sequence; D002118:Calcium / Q000378:metabolism; D016762:Genes, fos; D006801:Humans; D007376:Interleukin-2 / Q000096:biosynthesis; D007700:Kinetics; D007938:Leukemia; D017493:Leukocyte Common Antigens / Q000032:analysis; D008213:Lymphocyte Activation / Q000187:drug effects*; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation; D019000:Phosphotyrosine; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D015375:Receptors, Interleukin-2 / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology / Q000502:physiology*; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism; D014638:Vanadates / Q000494:pharmacology*
D007376:Interleukin-2; D016328:NF-kappa B; D012333:RNA, Messenger; D015375:Receptors, Interleukin-2; C069276:peroxovanadate; D019000:Phosphotyrosine; D014638:Vanadates; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D017493:Leukocyte Common Antigens; D017027:Protein Tyrosine Phosphatases; D010738:Type C Phospholipases; D002118:Calcium