title: Regulation of phosphoinositide 3-kinase signaling by oxidants: hydrogen peroxide selectively enhances immunoreceptor-induced recruitment of phosphatidylinositol (3,4) bisphosphate-binding PH domain proteins.
abstract: Phosphoinositide 3-kinases (PI3Ks) generate several distinct lipid second messengers including phosphatidylinositol (3,4,5) trisphosphate (PIP3) and phosphatidylinositol (3,4) bisphosphate PI(3,4)P2. PI(3,4)P2 is produced with distinct kinetics and binds to distinct PH domain effector proteins; however, the regulation of this signaling pathway is poorly understood. Superoxides such as hydrogen peroxide are transiently produced after activation through various cell surface receptors and play important roles in immune and inflammatory responses. Here we use quantitative microscopy to examine the effect of peroxide on PI(3,4)P2-mediated mobilization of signaling proteins in B lymphocytes. Peroxide was found to induce dose-dependant membrane recruitment of the PI(3,4)P2-binding PH domain proteins Bam32, TAPP2 and Akt/PKB but not the PIP3-binding PH domain of Btk. Peroxide-induced membrane recruitment was found to be dependant on PI3K activity, with the p110delta isoform contributing much of the activity in the BJAB human B lymphoma model. Strikingly, peroxide co-stimulation enhanced antigen receptor-induced membrane recruitment of Bam32 and TAPP2, with combined stimulation exceeding the maximum achievable with either stimulus alone. Expression of the lipid phosphatase PTEN led to reduction of antigen receptor-induced membrane recruitment of TAPP2; however, peroxide costimulation could overcome the inhibitory effect of PTEN. Inhibition of the NADPH oxidase led to reduction of antigen receptor-induced membrane recruitment of TAPP2. Our results indicate that exogenous and endogenous superoxides can modulate the quality of the PI3K signal in lymphocytes by selectively increasing PI(3,4)P2-dependant signaling.
authors.affiliation: Department of Immunology, University of Manitoba, 730 William Avenue, Winnipeg, MB Canada R3E 0W3.
authors.forename: Samuel M S
authors.initials: SM
authors.lastname: Cheung
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Kornelson
authors.forename: Monther
authors.initials: M
authors.lastname: Al-Alwan
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Marshall
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D001402:B-Lymphocytes / Q000201:enzymology / Q000378:metabolism*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D016877:Oxidants / Q000378:metabolism*; D051059:PTEN Phosphohydrolase / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism*; D015398:Signal Transduction; D013481:Superoxides / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C486555:DAPP1 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D016877:Oxidants; C461494:PLEKHA2 protein, human; D018129:Phosphatidylinositol Phosphates; D011947:Receptors, Antigen, B-Cell; C485184:enhanced green fluorescent protein; C060980:phosphatidylinositol 3,4-diphosphate; D013481:Superoxides; D049452:Green Fluorescent Proteins; D006861:Hydrogen Peroxide; D019869:Phosphatidylinositol 3-Kinases; D051059:PTEN Phosphohydrolase