In vivo and in vitro phosphorylation of annexin II in T cells: potential regulation by annexin V.
In order to understand how signal transduction occurs during T cell activation, it is necessary to identify the key regulatory molecules whose function is influenced by phosphorylation. Annexins II (A-II) and V (A-V) belong to a large family of Ca(2+)-dependent phospholipid-binding proteins. Among many putative functions, annexins may be involved in signal transduction during cellular proliferation and differentiation. In the present study we show that A-II is phosphorylated in vivo in the Jurkat human T cell line. Indeed, A-II is phosphorylated after stimulation by phorbol myristate acetate and on serine residues after T cell antigen receptor (TcR) stimulation. In cytosol from Jurkat cells, A-II is phosphorylated only by Ca2+/phospholipid-stimulated kinases such as Ca(2+)-dependent protein kinases C (cPKCs). A-V inhibits the phosphorylation of A-II and other substrates of cPKCs and has no effect on kinases activated only by phospholipids. In conclusion, A-II is phosphorylated both in vitro and in vivo in Jurkat cells, and may play a role as a substrate during signal transduction in lymphocytes via the TcR through the PKC pathway. On the other hand, A-V could act as a potent modulator of cPKCs in Jurkat cells.
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Laboratoire de Signalisation, Inflammation et Transformation Cellulaire, INSERM U.332, Institut Cochin de Génétique Moléculaire (ICGM), Université René Descartes, Paris, France.
Oudinet
J P
JP
Russo-Marie
F
F
Rothhut
B
B
D017306:Annexin A2 / Q000378:metabolism*; D017304:Annexin A5 / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D006801:Humans; D010743:Phospholipids / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D015398:Signal Transduction; D013379:Substrate Specificity; D013601:T-Lymphocytes / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D017306:Annexin A2; D017304:Annexin A5; D010743:Phospholipids; D011948:Receptors, Antigen, T-Cell; D011493:Protein Kinase C; D002118:Calcium