title: Discrete generations of intracellular hydrogen peroxide and superoxide in antigen-stimulated mast cells: reciprocal regulation of store-operated Ca2+ channel activity.
abstract: Mast cells and T cells produce reactive oxygen species (ROS) after stimulation with the high-affinity IgE receptor (Fc epsilon RI) and T cell receptor. A growing body of evidence suggests the existence of ROS-regulated intracellular and/or plasma membrane Ca(2+) channels in these cells but their molecular entities remain to be identified. Here, we report that store-operated Ca(2+) channel (SOC) activity is regulated by superoxide (O(2)(*-)) and hydrogen peroxide (H(2)O(2)) in mast cells. MnTBaP (Mn(III)tetrakis(4-benzoic acid)porphyrin) and ebselen (2-phenyl-1,2-benziso-selenazol-3(2H)-one) selectively blocked the generation of O(2)(*-) and H(2)O(2), respectively, in antigen-stimulated cells. The H(2)O(2) generation was dependent on the Src family kinase (SFK) and phosphatidylinositol-3-kinase (PI3K) activities but independent of extracellular Ca(2+), and the Fc epsilon RI beta-chain immunoreceptor tyrosine-based activation motif played an essential role. On the other hand, O(2)(*-) generation was strictly dependent on extracellular Ca(2+), but negatively regulated by the SFK and PI3K activities. Inhibition of O(2)(*-) generation resulted in increased H(2)O(2) generation and reduced SOC activity, although it had a minimal effect on endoplasmic reticulum Ca(2+) store depletion. On the contrary, inhibition of H(2)O(2) generation resulted in increased intracellular O(2)(*-) generation and augmented SOC activity. The findings suggest that O(2)(*-) and H(2)O(2), which are generated by separate signaling pathways/sources, reciprocally regulate SOC activity in mast cells. Such generations of multiple oxidant species and their distinct roles in the regulation of SOC activity may facilitate the fine tuning of Ca(2+) signaling in mast cells.
authors.affiliation: Division of Molecular Cell Immunology and Allergology, Nihon University Graduate School of Medical Science, 30-1 Oyaguchikami-cho Itabashi-ku, Tokyo, Japan. ysuzuki@med.nihon-u.ac.jp
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Yoshimaru
authors.forename: Toshio
authors.initials: T
authors.lastname: Inoue
authors.forename: Chisei
authors.initials: C
authors.lastname: Ra
mesh_terms: D000818:Animals; D001393:Azoles / Q000494:pharmacology; D002118:Calcium / Q000502:physiology; D015220:Calcium Channels / Q000502:physiology*; D015550:Cell Degranulation / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism*; D054833:Isoindoles; D008407:Mast Cells / Q000187:drug effects / Q000276:immunology* / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D016566:Organoselenium Compounds / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D011166:Porphyrins / Q000494:pharmacology; D051381:Rats; D017455:Receptors, IgE / Q000235:genetics / Q000502:physiology; D013481:Superoxides / Q000378:metabolism*; D019061:src-Family Kinases / Q000502:physiology
chemical_list: D001393:Azoles; D002118:Calcium; D015220:Calcium Channels; D006861:Hydrogen Peroxide; D054833:Isoindoles; D016566:Organoselenium Compounds; D019869:Phosphatidylinositol 3-Kinases; D011166:Porphyrins; D017455:Receptors, IgE; D013481:Superoxides; D019061:src-Family Kinases; C521907:Fc-epsilon receptor I beta-chain, mouse; C480958:tetrakis(4-benzoic acid)porphyrin; C042986:ebselen