TcR and TcR-CD28 engagement of protein kinase B (PKB/AKT) and glycogen synthase kinase-3 (GSK-3) operates independently of guanine nucleotide exchange factor VAV-1.
TcRzeta/CD3 and TcRzeta/CD3-CD28 signaling requires the guanine nucleotide exchange factor (GEF) Vav-1 as well as the activation of phosphatidylinositol 3-kinase, protein kinase B (PKB/AKT), and its inactivation of glycogen synthase kinase-3 (GSK-3). Whether these two pathways are connected or operate independently of each other in T-cells has been unclear. Here, we report that anti-CD3 and anti-CD3/CD28 can induce PKB and GSK-3alpha phosphorylation in the Vav-1(-/-) Jurkat cell line J. Vav.1 and in primary CD4-positive Vav-1(-/-) T-cells. Reduced GSK-3alpha phosphorylation was observed in Vav-1,2,3(-/-) T-cells together with a complete loss of FOXO1 phosphorylation. Furthermore, PKB and GSK-3 phosphorylation was unperturbed in the presence of GEF-inactive Vav-1 that inhibited interleukin-2 gene activation and a form of Src homology 2 domain-containing lymphocytic protein of 76-kDa (SLP-76) that is defective in binding to Vav-1. The pathway also was intact under conditions of c-Jun N-terminal kinase (JNK) inhibition and disruption of the actin cytoskeleton by cytochalasin D. Both events are down-stream targets of Vav-1. Overall, our findings indicate that the TcR and TcR-CD28 driven PKB-GSK-3 pathway can operate independently of Vav-1 in T-cells.
Wood
Joanne E
JE
Molecular Immunology Section, Department of Immunology, Imperial College London, London W12 ONN, United Kingdom.
Schneider
Helga
H
Rudd
Christopher E
CE
D000818:Animals; D018106:CD28 Antigens / Q000276:immunology / Q000378:metabolism*; D016650:Fluorescein-5-isothiocyanate; D005456:Fluorescent Dyes; D017930:Genes, Reporter; D038362:Glycogen Synthase Kinase 3 / Q000235:genetics / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D006801:Humans; D019169:Jurkat Cells; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D010590:Phalloidine; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D051567:Proto-Oncogene Proteins c-vav / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D013601:T-Lymphocytes / Q000201:enzymology* / Q000276:immunology / Q000378:metabolism
D018106:CD28 Antigens; D005456:Fluorescent Dyes; D020662:Guanine Nucleotide Exchange Factors; D051567:Proto-Oncogene Proteins c-vav; D011948:Receptors, Antigen, T-Cell; C496618:VAV1 protein, human; D010590:Phalloidine; D008156:Luciferases; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3; C448021:glycogen synthase kinase 3 alpha; D016650:Fluorescein-5-isothiocyanate