Bowman KG, Hemmerich S, Bhakta S, Singer MS, Bistrup A, Rosen SD, Bertozzi CR. Identification of an N-acetylglucosamine-6-0-sulfotransferase activity specific to lymphoid tissue: an enzyme with a possible role in lymphocyte homing.
CHEMISTRY & BIOLOGY 1998;
5:447-60. [PMID:
9710564 DOI:
10.1016/s1074-5521(98)90161-2]
[Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND
The leukocyte adhesion molecule L-selection participates in the initial attachment of blood-borne lymphocytes to high endothelial venules (HEVs) during lymphocyte homing to secondary lymphoid organs, and contributes to leukocyte adhesion and extravasation in HEV-like vessels at sites of chronic inflammation. The L-selection ligands on lymph mode HEVs are mucin-like glycoproteins adorned with the unusual sulfated carbohydrate epitope, 6-sulfo sialyl Lewis x. Sulfation of this epitope on the N-acetylglucosamine (GlcNAc) residue confers high-avidity L-selection binding, and is thought to be restricted in the vasculature to sites of sustained lymphocyte recruitment. The GlcNAc-6-0 sulfotransferase that installs the sulfate ester may be a key modulator of lymphocyte recruitment to secondary lymphoid organs and sites of chronic inflammation and is therefore a potential target for anti-inflammatory therapy.
RESULTS
A GlcNAc-6-0-sulfotransferase activity was identified within porcine lymph nodes and characterized using a rapid, sensitive, and quantitative assay. We synthesized two unnatural oligosaccharide substrates, GlcNAc beta 1-->6Gal alpha-R and Gal beta 1-->4GlcNAc beta 1-->6Gal alpha-R, that incorporate structural motifs from the native L-selection ligands into an unnatural C-glycosyl hydrocarbon scaffold. The sulfotransferase incorporated greater than tenfold more sulfate into the disaccharide than the trisaccharide, indicating a requirement for a terminal GlcNAc. Activity across tissues was highly restricted to the HEVs within peripheral lymph node.
CONCLUSIONS
The restricted expression of the GlcNAc-6-0-sulfotransferase activity to lymph node HEVs strongly suggestions a role in the biosynthesis of L-selection ligands. In addition, similar sulfated epitopes are known to be expressed on HEV-like vessels of chronically inflamed tissues; indicating that this sulfotransferase may also contribute to inflammatory lymphocyte recruitment. We identified a concise disaccharide motif, GlcNAc beta 1-->6Gal alpha-R, that preserved both recognition and specificity determinants for the GlcNAc-6-0-sulfotransferase. The absence of activity on the trisaccharide Gal beta 1-->6Gal alpha-R indicates a requirement for a substrate with a terminal GlcNAc residue, suggesting that sulfation precedes further biosynthetic assembly of L-selection ligands.
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