title: AQP8 transports NOX2-generated H2O2 across the plasma membrane to promote signaling in B cells.
abstract: H2O2acts as a second messenger in key signaling circuits, transiently modulating tyrosine phosphatases and kinases. We investigated its origin, membrane transport, and functional role during B cell activation and differentiation. Our data identified NADPH-oxidase 2 as the main source of H2O2and aquaporin 8 as a transport facilitator across the plasma membrane. On aquaporin 8 silencing, inducible B lymphoma cells responded poorly to TLR and BCR stimulation. Their differentiation was severely impaired, as demonstrated by retarded onset of IgM polymerization, low amounts of IgM secretion, and prolonged BCR expression on the cell surface. A silencing-resistant aquaporin 8 rescued responsiveness, confirming that the import of H2O2across the membrane is essential for B cell activation. The addition of exogenous catalase to primary B splenocytes severely impaired the tyrosine phosphorylation induced by BCR cross-linking, as did the absence of NOX2 in a murine model of chronic granulomatous disease. Importantly, re-expression of gp91phoxthrough gene therapy restored the specific B cell signaling deficiency in NOX2-/-cells. Thus, efficient induction of B cell activation and differentiation requires intact H2O2fluxes across the plasma membrane for signal amplification.
authors.affiliation: Division of Genetics and Cell Biology, IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Milena
authors.initials: M
authors.lastname: Bertolotti
authors.affiliation: San Raffaele Telethon Institute for Gene Therapy (TIGET), Milan, Italy.
authors.forename: Giada
authors.initials: G
authors.lastname: Farinelli
authors.affiliation: Division of Genetics and Cell Biology, IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Galli
authors.affiliation: San Raffaele Telethon Institute for Gene Therapy (TIGET), Milan, Italy.|Pediatric Immunohematology and Bone Marrow Transplantation Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy; and.|Vita-Salute San Raffaele University, Milan, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Aiuti
authors.affiliation: Division of Genetics and Cell Biology, IRCCS San Raffaele Scientific Institute, Milan, Italy; sitia.roberto@hsr.it.|Vita-Salute San Raffaele University, Milan, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Sitia
mesh_terms: D000818:Animals; D020346:Aquaporins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D001402:B-Lymphocytes / Q000378:metabolism*; D001692:Biological Transport; D016026:Bone Marrow Transplantation; D002374:Catalase / Q000494:pharmacology; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D004195:Disease Models, Animal; D006105:Granulomatous Disease, Chronic; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008213:Lymphocyte Activation; D016393:Lymphoma, B-Cell / Q000473:pathology; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D010950:Plasma Cells / Q000473:pathology; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D034622:RNA Interference; D011947:Receptors, Antigen, B-Cell / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D020346:Aquaporins; D008562:Membrane Glycoproteins; D011947:Receptors, Antigen, B-Cell; D011993:Recombinant Fusion Proteins; C108330:aquaporin 8; D006861:Hydrogen Peroxide; D002374:Catalase; C488842:Cybb protein, mouse; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases
keywords: aquaporins; differentiation; immunoglobulin; redox