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Hypoxia Reduces Arylsulfatase B Activity and Silencing Arylsulfatase B Replicates and Mediates the Effects of Hypoxia

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posted on 18.09.2012 by Joanne K. Tobacman, Sumit Bhattacharyya
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)x1 h, ARSB activity declined by approximately 41% and approximately 30% from baseline, as nuclear hypoxia inducible factor (HIF)-1alpha increased by approximately 53% and approximately 37%. When ARSB was silenced, nuclear HIF-1alpha increased by approximately 81% and approximately 61% from baseline, and mRNA expression increased to 3.73 (+/-0.34) times baseline. Inversely, ARSB overexpression reduced nuclear HIF-1alpha by approximately 37% and approximately 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.

Funding

The sources of funding were VA Merit Review and Clinical and Translational Science Award (CTSA) UL1 RR029879. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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Publisher Statement

This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.

Publisher

PLoS One

Language

en_US

issn

1932-6203

Issue date

13/03/2012

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