title: Nucleolin is a nuclear target of heparan sulfate derived from glypican-1.
abstract: The recycling, S-nitrosylated heparan sulfate (HS) proteoglycan glypican-1 releases anhydromannose (anMan)-containing HS chains by a nitrosothiol-catalyzed cleavage in endosomes that can be constitutive or induced by ascorbate. The HS-anMan chains are then transported to the nucleus. A specific nuclear target for HS-anMan has not been identified. We have monitored endosome-to-nucleus trafficking of HS-anMan by deconvolution and confocal immunofluorescence microscopy using an anMan-specific monoclonal antibody in non-growing, ascorbate-treated, and growing, untreated, wild-type mouse embryonic fibroblasts and hypoxia-exposed Alzheimer mouse Tg2576 fibroblasts and human U87 glioblastoma cells. In all cells, nuclear HS-anMan targeted a limited number of sites of variable size where it colocalized with DNA and nucleolin, an established marker for nucleoli. HS-anMan also colocalized with ethynyl uridine-tagged nascent RNA and two acetylated forms of histone H3. Acute hypoxia increased the formation of HS-anMan in both Tg2576 and U87 cells. A portion of HS-anMan colocalized with nucleolin at small discrete sites, while most of the nucleolin and nascent RNA was dispersed. In U87 cells, HS-anMan, nucleolin and nascent RNA reassembled after prolonged hypoxia. Nucleolar HS may modulate synthesis and/or release of rRNA.
authors.affiliation: Department of Experimental Medical Science, Division of Neuroscience, Glycobiology Group, Lund University, Biomedical Center A13, SE-221 84 Lund, Sweden.
authors.forename: Fang
authors.initials: F
authors.lastname: Cheng
authors.affiliation: Department of Clinical Sciences, Section of Oncology and Pathology, Lund University, Lund, 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, SE-221 84 Lund, 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, SE-221 84 Lund, Sweden. Electronic address: katrin.mani@med.lu.se.
authors.forename: Katrin
authors.initials: K
authors.lastname: Mani
mesh_terms: D000544:Alzheimer Disease / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D016229:Amyloid beta-Peptides / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism* / Q000648:ultrastructure; D004195:Disease Models, Animal; D011992:Endosomes / Q000378:metabolism / Q000648:ultrastructure; D053673:Glypicans / Q000378:metabolism*; D006497:Heparan Sulfate / Q000378:metabolism; D006801:Humans; D008358:Mannose / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018613:Microscopy, Confocal; D009569:Nitric Oxide / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism* / Q000648:ultrastructure; D016601:RNA-Binding Proteins / Q000378:metabolism* / Q000648:ultrastructure; D000097796:Nucleolin
chemical_list: D016229:Amyloid beta-Peptides; D053673:Glypicans; D006497:Heparan Sulfate; D008358:Mannose; D009569:Nitric Oxide; D010750:Phosphoproteins; D016601:RNA-Binding Proteins; D000097796:Nucleolin
keywords: Anhydromannose; Glypican; Heparan sulfate; Histones; Nucleolin; RNA