title: Glutathione peroxidase-1 but not -4 is involved in the regulation of cellular 5-lipoxygenase activity in monocytic cells.
abstract: In contrast to neutrophils or B-lymphocytes, cells of the monocytic lineage like rat macrophages, human peripheral blood monocytes and Mono Mac 6 cells contain a strong inhibitor of 5-lipoxygenase (5-LO) activity, which scavenges hydroperoxides and inhibits 5-LO activity in broken-cell preparations in the absence of exogenously added thiols. Chromatographic purification of the inhibitor from the human monocytic cell line Mono Mac 6 and amino acid sequence analysis revealed that the inhibitory factor is glutathione peroxidase-1 (GPx-1). In contrast to the peroxidase activity of GPx-1, 5-LO inhibition by GPx-1 was supported by beta-mercaptoethanol and there was no absolute requirement for millimolar concentrations of glutathione or dithiothreitol. These cofactor characteristics suggest that both activities address distinct catalytic properties of GPx-1. 5-LO inhibition by GPx-1 was not due to direct GPx-5-LO protein-protein interactions, since GPx-1 did not bind to immobilized 5-LO. Interestingly, 5-LO derived from granulocytes was significantly more resistant against GPx-1 inhibition than B-lymphocytic 5-LO, which correlates with the respective cellular 5-LO activities. In summary, the data suggest that, in addition to previously reported phospholipid hydroperoxide glutathione peroxidase (GPx-4), GPx-1 is an efficient inhibitor of 5-LO even at low thiol concentrations, and is involved in the regulation of cellular 5-LO activity in various cell types.
authors.affiliation: Institute of Pharmaceutical Chemistry, University of Frankfurt, Marie-Curie-Str. 9, D-60439 Frankfurt, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Straif
authors.forename: O
authors.initials: O
authors.lastname: Werz
authors.forename: R
authors.initials: R
authors.lastname: Kellner
authors.forename: U
authors.initials: U
authors.lastname: Bahr
authors.forename: D
authors.initials: D
authors.lastname: Steinhilber
mesh_terms: D000818:Animals; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism*; D002384:Catalysis; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000378:metabolism; D004795:Enzyme Stability; D005979:Glutathione Peroxidase / Q000378:metabolism*; D006801:Humans; D016859:Lipoxygenase Inhibitors; D009000:Monocytes / Q000201:enzymology*; D000080662:Phospholipid Hydroperoxide Glutathione Peroxidase; D011485:Protein Binding; D051381:Rats; D012643:Selenium / Q000494:pharmacology; D013438:Sulfhydryl Compounds / Q000378:metabolism; D000094765:Glutathione Peroxidase GPX1
chemical_list: D004791:Enzyme Inhibitors; D016859:Lipoxygenase Inhibitors; D013438:Sulfhydryl Compounds; D000080662:Phospholipid Hydroperoxide Glutathione Peroxidase; D005979:Glutathione Peroxidase; D001094:Arachidonate 5-Lipoxygenase; D012643:Selenium; D000094765:Glutathione Peroxidase GPX1