title: Hypoxia induces NO-dependent release of heparan sulfate in fibroblasts from the Alzheimer mouse Tg2576 by activation of nitrite reduction.
abstract: There is a functional relationship between the heparan sulfate proteoglycan glypican-1 and the amyloid precursor protein (APP) of Alzheimer disease. In wild-type mouse embryonic fibroblasts, expression and processing of the APP is required for endosome-to-nucleus translocation of anhydromannose-containing heparan sulfate released from S-nitrosylated glypican-1 by ascorbate-induced, nitrosothiol-catalyzed deaminative cleavage. In fibroblasts from the transgenic Alzheimer mouse Tg2576, there is increased processing of the APP to amyloid-β peptides. Simultaneously, there is spontaneous formation of anhydromannose-containing heparan sulfate by an unknown mechanism. We have explored the effect of hypoxia on anhydromannose-containing heparan sulfate formation in wild-type and Tg2576 fibroblasts by deconvolution immunofluorescence microscopy and flow cytometry using an anhydromannose-specific monoclonal antibody and by (35)SO4-labeling experiments. Hypoxia prevented ascorbate-induced heparan sulfate release in wild-type fibroblasts, but induced an increased formation of anhydromannose-positive and (35)S-labeled heparan sulfate in Tg2576 fibroblasts. This appeared to be independent of glypican-1 S-nitrosylation as demonstrated by using a monoclonal antibody specific for S-nitrosylated glypican-1. In hypoxic wild-type fibroblasts, addition of nitrite to the medium restored anhydromannose-containing heparan sulfate formation. The increased release of anhydromannose-containing heparan sulfate in hypoxic Tg2576 fibroblasts did not require addition of nitrite. However, it was suppressed by inhibition of the nitrite reductase activity of xanthine oxidoreductase/aldehyde oxidase or by inhibition of p38 mitogen-activated protein kinase or by chelation of iron. We propose that normoxic Tg2576 fibroblasts maintain a high level of anhydromannose-containing heparan sulfate production by a stress-activated generation of nitric oxide from endogenous nitrite. This activation is enhanced by hypoxia.
authors.affiliation: Department of Experimental Medical Science, Division of Neuroscience, Glycobiology Group, Lund University, Biomedical Center A13, Lund SE-221 84, Sweden.
authors.forename: Fang
authors.initials: F
authors.lastname: Cheng
authors.affiliation: Department of Clinical Sciences, Section of Oncology and Pathology, Lund University, Lund SE-221 85, Sweden.
authors.forename: Erika
authors.initials: E
authors.lastname: Bourseau-Guilmain
authors.affiliation: Department of Clinical Sciences, Section of Oncology and Pathology, Lund University, Lund SE-221 85, Sweden Skåne Oncology Clinic, Lund SE-221 84, Sweden.
authors.forename: Mattias
authors.initials: M
authors.lastname: Belting
authors.affiliation: Department of Experimental Medical Science, Division of Neuroscience, Glycobiology Group, Lund University, Biomedical Center A13, Lund SE-221 84, Sweden.
authors.forename: Lars-Åke
authors.initials: LÅ
authors.lastname: Fransson
authors.affiliation: Department of Experimental Medical Science, Division of Neuroscience, Glycobiology Group, Lund University, Biomedical Center A13, Lund SE-221 84, Sweden katrin.mani@med.lu.se.
authors.forename: Katrin
authors.initials: K
authors.lastname: Mani
mesh_terms: D000544:Alzheimer Disease / Q000378:metabolism / Q000473:pathology; D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry; D001205:Ascorbic Acid / Q000494:pharmacology; D015687:Cell Hypoxia; D003676:Deferoxamine / Q000494:pharmacology; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D053673:Glypicans / Q000737:chemistry / Q000378:metabolism*; D006497:Heparan Sulfate / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007502:Iron Chelating Agents / Q000494:pharmacology; D008358:Mannose / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D008856:Microscopy, Fluorescence; D009569:Nitric Oxide / Q000378:metabolism / Q000494:pharmacology*; D009572:Nitrite Reductases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009573:Nitrites / Q000737:chemistry / Q000494:pharmacology; D010084:Oxidation-Reduction; D010100:Oxygen / Q000494:pharmacology*; D061251:Primary Cell Culture; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D001205:Ascorbic Acid; D003676:Deferoxamine; D004791:Enzyme Inhibitors; D053673:Glypicans; D006497:Heparan Sulfate; D007502:Iron Chelating Agents; D008358:Mannose; D009569:Nitric Oxide; D009572:Nitrite Reductases; D009573:Nitrites; D010100:Oxygen; D048051:p38 Mitogen-Activated Protein Kinases; C035767:2,5-anhydromannose
keywords: Alzheimer disease; anhydromannose; heparan sulfate; hypoxia; nitric oxide