title: Hypoxia reduces arylsulfatase B activity and silencing arylsulfatase B replicates and mediates the effects of hypoxia.
abstract: This report presents evidence of 1) a role for arylsulfatase B (ARSB; N-acetylgalactosamine-4-sulfatase) in mediating intracellular oxygen signaling; 2) replication between the effects of ARSB silencing and hypoxia on sulfated glycosaminoglycan content, cellular redox status, and expression of hypoxia-associated genes; and 3) a mechanism whereby changes in chondroitin-4-sulfation that follow either hypoxia or ARSB silencing can induce transcriptional changes through galectin-3. ARSB removes 4-sulfate groups from the non-reducing end of chondroitin-4-sulfate and dermatan sulfate and is required for their degradation. For activity, ARSB requires modification of a critical cysteine residue by the formylglycine generating enzyme and by molecular oxygen. When primary human bronchial and human colonic epithelial cells were exposed to 10% O(2) × 1 h, ARSB activity declined by ~41% and ~30% from baseline, as nuclear hypoxia inducible factor (HIF)-1α increased by ~53% and ~37%. When ARSB was silenced, nuclear HIF-1α increased by ~81% and ~61% from baseline, and mRNA expression increased to 3.73 (± 0.34) times baseline. Inversely, ARSB overexpression reduced nuclear HIF-1α by ~37% and ~54% from baseline in the epithelial cells. Hypoxia, like ARSB silencing, significantly increased the total cellular sulfated glycosaminoglycans and chondroitin-4-sulfate (C4S) content. Both hypoxia and ARSB silencing had similar effects on the cellular redox status and on mRNA expression of hypoxia-associated genes. Transcriptional effects of both ARSB silencing and hypoxia may be mediated by reduction in galectin-3 binding to more highly sulfated C4S, since the galectin-3 that co-immunoprecipitated with C4S declined and the nuclear galectin-3 increased following ARSB knockdown and hypoxia.
authors.affiliation: Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America.
authors.forename: Sumit
authors.initials: S
authors.lastname: Bhattacharyya
authors.forename: Joanne K
authors.initials: JK
authors.lastname: Tobacman
mesh_terms: D000704:Analysis of Variance; D017931:DNA Primers / Q000235:genetics; D004797:Enzyme-Linked Immunosorbent Assay; D004847:Epithelial Cells; D005470:Fluorometry; D037502:Galectin 3 / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D055785:Gene Knockdown Techniques; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D000860:Hypoxia / Q000201:enzymology / Q000378:metabolism*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D007413:Intestinal Mucosa / Q000166:cytology; D020051:N-Acetylgalactosamine-4-Sulfatase / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D050862:Oxidoreductases Acting on Sulfur Group Donors; D010100:Oxygen / Q000378:metabolism* / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D034741:RNA, Small Interfering / Q000235:genetics; D020545:Respiratory Mucosa / Q000166:cytology; D015398:Signal Transduction / Q000502:physiology*; D013429:Sulfatases / Q000235:genetics / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D037502:Galectin 3; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D034741:RNA, Small Interfering; D050862:Oxidoreductases Acting on Sulfur Group Donors; C480483:SUMF1 protein, human; D013429:Sulfatases; D020051:N-Acetylgalactosamine-4-Sulfatase; D005978:Glutathione; D010100:Oxygen