title: Inhibition of phosphatidylinositol 3-kinase blocks T cell antigen receptor/CD3-induced activation of the mitogen-activated kinase Erk2.
abstract: The production of 3-phosphorylated inositol phospholipids is implicated in regulation of cell growth and transformation. To explore the role of these lipids in T cell antigen receptor (TCR)/CD3-induced signaling, we have examined the effects of a specific phosphatidylinositol 3-kinase (PtdIns3K) inhibitor, wortmannin, and overexpression of two PtdIns3K constructs on the activation of down-stream effectors in anti-CD3 treated T cells. We report that treatment of cells with wortmannin blocked anti-CD3-induced activation of the mitogen-activation kinase Erk2 while not affecting phorbol-ester-induced Erk2 activation. An inactive analog of wortmannin, WM12, did not affect TCR/CD3-induced Erk2 activation, and wortmannin had no effect on the activity of Erk2 when added directly to the in vitro assays. Expression of a disruptive PtdIns3K construct also reduced Erk2 activation, while a construct that stimulates PtdIns3K enhanced the activation of Erk2. Receptor-induced activation of other Ser/Thr kinases, such as c-Raf, B-Raf, Mek1, Mek2, Mekk, was not affected by wortmannin. Our results suggest that the production of 3-phosphorylated inositol phospholipids is involved in the activation of Erk2, but does not regulate the enzymes that are thought to be upstream of Erk2.
authors.affiliation: Division of Cell Biology, La Jolla Institute for Allergy and Immunology, CA, USA.
authors.forename: M
authors.initials: M
authors.lastname: Von Willebrand
authors.forename: T
authors.initials: T
authors.lastname: Jascur
authors.forename: N
authors.initials: N
authors.lastname: Bonnefoy-Bérard
authors.forename: H
authors.initials: H
authors.lastname: Yano
authors.forename: A
authors.initials: A
authors.lastname: Altman
authors.forename: Y
authors.initials: Y
authors.lastname: Matsuda
authors.forename: T
authors.initials: T
authors.lastname: Mustelin
mesh_terms: D000595:Amino Acid Sequence; D000730:Androstadienes / Q000494:pharmacology; D017252:CD3 Complex / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D004261:DNA Replication / Q000187:drug effects; D004789:Enzyme Activation; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1; D008969:Molecular Sequence Data; D019869:Phosphatidylinositol 3-Kinases; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011494:Protein Kinases / Q000187:drug effects / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000037:antagonists & inhibitors*; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D017252:CD3 Complex; D011948:Receptors, Antigen, T-Cell; D014443:Tyrosine; D011494:Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D000077191:Wortmannin