title: Key role of the p110delta isoform of PI3K in B-cell antigen and IL-4 receptor signaling: comparative analysis of genetic and pharmacologic interference with p110delta function in B cells.
abstract: Mouse gene-targeting studies have documented a central role of the p110delta isoform of phosphoinositide 3-kinase (PI3K) in B-cell development and function. A defect in B-cell antigen receptor (BCR) signaling is key to this B-cell phenotype. Here we further characterize this signaling defect and report that a p110delta-selective small molecule inhibitor mirrors the effect of genetic inactivation of p110delta in BCR signaling. p110delta activity is indispensable for BCR-induced DNA synthesis and phosphorylation of Akt/protein kinase B (PKB), forkhead transcription factor/forkhead box O3a (FOXO3a), and p70 S6 kinase (p70 S6K), with modest effects on the phosphorylation of glycogen synthase kinase 3 alpha/beta (GSK3alpha/beta) and extracellular signal-regulated kinase (Erk). The PI3K-dependent component of intracellular calcium mobilization also completely relies on p110delta catalytic activity. Resting B cells with inactive p110delta fail to enter the cell cycle, correlating with an incapacity to up-regulate the expression of cyclins D2, A, and E, and to phosphorylate the retinoblastoma protein (Rb). p110delta is also critical for interleukin 4 (IL-4)-induced phosphorylation of Akt/PKB and FOXO3a, and protection from apoptosis. Taken together, these data show that defects observed in p110delta mutant mice are not merely a consequence of altered B-cell differentiation, and emphasize the potential utility of p110delta as a drug target in autoimmune diseases in which B cells play a crucial role.
authors.affiliation: Ludwig Institute for Cancer Research, 91 Riding House Street, London, W1W 7BS, United Kingdom.
authors.forename: Antonio
authors.initials: A
authors.lastname: Bilancio
authors.forename: Klaus
authors.initials: K
authors.lastname: Okkenhaug
authors.forename: Montserrat
authors.initials: M
authors.lastname: Camps
authors.forename: Juliet L
authors.initials: JL
authors.lastname: Emery
authors.forename: Thomas
authors.initials: T
authors.lastname: Ruckle
authors.forename: Christian
authors.initials: C
authors.lastname: Rommel
authors.forename: Bart
authors.initials: B
authors.lastname: Vanhaesebroeck
mesh_terms: D000818:Animals; D017209:Apoptosis; D001402:B-Lymphocytes / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002453:Cell Cycle; D002454:Cell Differentiation; D049109:Cell Proliferation / Q000187:drug effects*; D058534:Class I Phosphatidylinositol 3-Kinases; D019925:Cyclin A / Q000378:metabolism; D056742:Cyclin D2; D019927:Cyclin E / Q000378:metabolism; D016213:Cyclins / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000378:metabolism; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D015847:Interleukin-4 / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000502:physiology*; D010766:Phosphorylation; D020033:Protein Isoforms; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism*; D019948:Receptors, Interleukin-4 / Q000378:metabolism*; D016160:Retinoblastoma Protein / Q000378:metabolism; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D002118:Calcium; D058534:Class I Phosphatidylinositol 3-Kinases; D019925:Cyclin A; D056742:Cyclin D2; D019927:Cyclin E; D016213:Cyclins; D004791:Enzyme Inhibitors; D048049:Extracellular Signal-Regulated MAP Kinases; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; D038362:Glycogen Synthase Kinase 3; D000071679:Glycogen Synthase Kinase 3 beta; D015847:Interleukin-4; D019869:Phosphatidylinositol 3-Kinases; D020033:Protein Isoforms; D051057:Proto-Oncogene Proteins c-akt; D011947:Receptors, Antigen, B-Cell; D019948:Receptors, Interleukin-4; D016160:Retinoblastoma Protein; D038762:Ribosomal Protein S6 Kinases, 70-kDa; C080336:CCND2 protein, human; C499517:FOXO3 protein, human; C421683:Pik3cd protein, mouse; C448021:glycogen synthase kinase 3 alpha