title: Tyrosine phosphatase CD45 regulates hydrogen peroxide-induced calcium mobilization in B cells.
abstract: By taking advantage of established CD45-deficient DT40 cells, the roles of CD45 in oxidative stress signaling were investigated. Using p-nitrophenyl phosphate as substrate, it was found that CD45 constituted nearly 40% of the total protein-tyrosine phosphatase activity. Almost 90% of the phosphatase activity was rapidly inactivated upon hydrogen peroxide treatment. Hydrogen peroxide-induced tyrosine phosphorylation of cellular proteins and c-Jun N-terminal kinase activation were markedly enhanced in CD45-deficient cells relative to that in its parental cells. In comparison, hydrogen peroxide-induced inositol 1,4,5-trisphosphate production and Ca(2+) mobilization were impaired in CD45-deficient DT40 cells. However, hydrogen peroxide-induced tyrosine phosphorylation of phospholipase Cgamma2 (PLCgamma2), phosphatidylinositol 3-kinase activity precipitated by anti-phosphotyrosine antibody, and activation of Bruton's tyrosine kinase appeared intact in CD45-deficient DT40 cells. This suggests that CD45 mediates the ability of hydrogen peroxide-activated PLCgamma2 to hydrolyze its substrate via a mechanism independent of both tyrosine phosphorylation of PLCgamma2 and phosphatidylinositol 3-kinase, as well as activation of Bruton's tyrosine kinase. Taken together, our observations demonstrated that, in addition to its negative regulatory or phosphatase activity, CD45 has a positive role in oxidative stress signaling.
authors.affiliation: Laboratory of Biochemistry, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892-8012, USA.
authors.forename: Suofu
authors.initials: S
authors.lastname: Qin
authors.forename: P Boon
authors.initials: PB
authors.lastname: Chock
mesh_terms: D000077329:Agammaglobulinaemia Tyrosine Kinase; D000730:Androstadienes / Q000378:metabolism; D000818:Animals; D001402:B-Lymphocytes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D002460:Cell Line; D002645:Chickens; D004789:Enzyme Activation; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases; D017493:Leukocyte Common Antigens / Q000235:genetics / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology*; D018384:Oxidative Stress; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051966:Phospholipase C gamma; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism; D000077191:Wortmannin
chemical_list: D000077329:Agammaglobulinaemia Tyrosine Kinase; D000730:Androstadienes; D002118:Calcium; D006861:Hydrogen Peroxide; D015544:Inositol 1,4,5-Trisphosphate; D007527:Isoenzymes; D048031:JNK Mitogen-Activated Protein Kinases; D017493:Leukocyte Common Antigens; D020928:Mitogen-Activated Protein Kinases; D016877:Oxidants; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051966:Phospholipase C gamma; D011505:Protein-Tyrosine Kinases; D010738:Type C Phospholipases; D014443:Tyrosine; D000077191:Wortmannin