Identification of an N-acetylglucosamine-6-0-sulfotransferase activity specific to lymphoid tissue: an enzyme with a possible role in lymphocyte homing.
Identification of an N-acetylglucosamine-6-0-sulfotransferase activity specific to lymphoid tissue: an enzyme with a possible role in lymphocyte homing.
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淋巴组织特异性 N-乙酰氨基葡萄糖-6-0-磺基转移酶活性的鉴定：一种可能在淋巴细胞归巢中发挥作用的酶。
DOI：
10.1016/s1074-5521(98)90161-2
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发表时间：
1998
影响因子：
--
通讯作者：
Bertozzi,CR
中科院分区：
文献类型：
--
作者：
Bowman,KG;Hemmerich,S;Bhakta,S;Singer,MS;Bistrup,A;Rosen,SD;Bertozzi,CR
背景：白细胞粘附分子L-选择素参与淋巴细胞归巢至次级淋巴器官期间血源性淋巴细胞与高内皮微静脉（HEV）的初始附着，并有助于慢性炎症部位的HEV样血管中的白细胞粘附和外渗。淋巴结 HEV 上的 L-选择素配体是粘蛋白样糖蛋白，装饰有不寻常的硫酸化碳水化合物表位 6-磺基唾液酸 Lewis x。 N-乙酰氨基葡萄糖 (GICNAc) 残基上的该表位的硫酸化赋予了高亲和力的 L-选择素结合，并且被认为在脉管系统中被限制在持续淋巴细胞募集的位点。安装硫酸酯的 GlcNAc-6-O-磺基转移酶可能是淋巴细胞募集至次级淋巴器官和慢性炎症部位的关键调节剂，因此是抗炎治疗的潜在靶标。结果：在猪淋巴结内鉴定出 GlcNAc-6-O-磺基转移酶活性，并使用快速、灵敏和定量测定进行表征。我们合成了两种非天然寡糖底物 GlcNAcβ1 →6Galα-R 和 Galβ1→4GlcNAcβ1 →6Galα-R，它们将天然 L-选择素配体的结构基序合并到非天然 C-糖基烃支架中。磺基转移酶将比三糖多十倍多的硫酸盐掺入二糖中，表明需要末端 GlcNAc。跨组织的活性高度限制于外周淋巴结内的 HEV。结论：GlcNAc-6-O-磺基转移酶活性在淋巴结 HEV 中的限制性表达强烈表明其在 L-选择素配体的生物合成中的作用。此外，已知类似的硫酸化表位在慢性炎症组织的 HEV 样血管上表达，表明这种磺基转移酶也可能有助于炎症淋巴细胞的募集。我们鉴定了一个简洁的二糖基序 GlcNAcβ1 →6-Galα-R，它保留了 GlcNAc-6-O-磺基转移酶的识别和特异性决定因素。三糖 Galβ1 → 4-GlcNAcβ1 → 6-Galα-R 缺乏活性表明需要具有末端 GlcNAc 残基的底物，这表明硫酸化先于 L-选择素配体的进一步生物合成组装。
Background: The leukocyte adhesion molecule L-selectin 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-selectin ligands on lymph node 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 (GICNAc) residue confers high-avidity L-selectin binding, and is thought to be restricted in the vasculature to sites of sustained lymphocyte recruitment. The GIcNAc-6-Osulfotransferase that installs the sulfate ester may be a key modulator of lymphocyte recruitement to secondary lymphoid organs and sites of chronic inflammation and is therefore a potential target for anti-inflammatory therapy.Results: A GIcNAc-6-O-sulfotransferase activity was identified within porcine lymph nodes and characterized using a rapid, sensitive, and quantitative assay. We synthesized two unnatural oligosaccharide substrates, GIcNAcβ1 →6Galα-R and Galβ1→4GIcNAcβ1 →6Galα-R, that incorporate structural motifs from the native L-selectin 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 GIcNAc-6-O-sulfotransferase activity to lymph node HEVs strongly suggests a role in the biosynthesis of L-selectin 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, GIcNAcβ1 →6-Galα-R, that preserved both recognition and specificity determinants for the GIcNAc-6-O-sulfotransferase. The absence of activity on the trisaccharide Galβ1→4-GIcNAcβ1 →6-Galα-R indicates a requirement for a substrate with a terminal GIcNAc residue, suggesting that sulfation precedes further biosynthetic assembly of L-selectin ligands.