Inhibition of phosphatidylinositol 3-kinase blocks T cell antigen receptor/CD3-induced activation of the mitogen-activated kinase Erk2.
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.
Von Willebrand
M
M
Division of Cell Biology, La Jolla Institute for Allergy and Immunology, CA, USA.
Jascur
T
T
Bonnefoy-Bérard
N
N
Yano
H
H
Altman
A
A
Matsuda
Y
Y
Mustelin
T
T
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
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