Identification of neutrophil granule glycoproteins as Lewis(x)-containing ligands cleared by the scavenger receptor C-type lectin.
Identification of neutrophil granule glycoproteins as Lewis(x)-containing ligands cleared by the scavenger receptor C-type lectin.
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DOI：
10.1074/jbc.m111.244772
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发表时间：
2011-07-08
期刊：
影响因子：
--
通讯作者：
Taylor ME
中科院分区：
文献类型：
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作者：
Graham SA;Antonopoulos A;Hitchen PG;Haslam SM;Dell A;Drickamer K;Taylor ME
清道夫受体C型凝集素（SRCL）是一种聚糖结合受体，能够介导携带末端Lewisx基团（Galβ1-4（Fucα1-3）GlcNAc）的糖蛋白的内吞作用。筛选糖蛋白配体SRCL使用亲和层析固定化SRCL，然后通过质谱为基础的蛋白质组学分析显示，可溶性糖蛋白从次级颗粒的中性粒细胞，包括乳铁蛋白和基质金属蛋白酶8和9，是主要的配体。结合竞争和表面等离子体共振分析表明，在低微摩尔范围内的亲和力。SRCL与嗜中性粒细胞和牛乳铁蛋白结合的比较表明，结合依赖于嗜中性粒细胞中的细胞特异性糖基化，因为乳形式的糖蛋白是更差的配体。与中性粒细胞糖蛋白的结合是岩藻糖依赖性的，并且使用中性粒细胞和牛乳铁蛋白的基于质谱的糖组学分析来建立与SRCL的高亲和力结合与在分支聚糖的异质混合物上存在多个成簇的末端Lewisx基团之间的相关性，其中一些具有聚N-乙酰乳糖胺延伸。使用SRCL转染的成纤维细胞证实了SRCL介导嗜中性粒细胞乳铁蛋白摄取的能力。因此，颗粒蛋白聚糖中常见的Lewisx基团可以靶向颗粒蛋白，以通过SRCL清除。PCR和免疫组织化学分析证实，SRCL广泛表达于内皮细胞上，因此代表了一个分布式系统，可以在炎症部位局部或在循环中释放时全身性地抑制释放的中性粒细胞糖蛋白。
The scavenger receptor C-type lectin (SRCL) is a glycan-binding receptor that has the capacity to mediate endocytosis of glycoproteins carrying terminal Lewisx groups (Galβ1–4(Fucα1–3)GlcNAc). A screen for glycoprotein ligands for SRCL using affinity chromatography on immobilized SRCL followed by mass spectrometry-based proteomic analysis revealed that soluble glycoproteins from secondary granules of neutrophils, including lactoferrin and matrix metalloproteinases 8 and 9, are major ligands. Binding competition and surface plasmon resonance analysis showed affinities in the low micromolar range. Comparison of SRCL binding to neutrophil and milk lactoferrin indicates that the binding is dependent on cell-specific glycosylation in the neutrophils, as the milk form of the glycoprotein is a much poorer ligand. Binding to neutrophil glycoproteins is fucose-dependent, and mass spectrometry-based glycomic analysis of neutrophil and milk lactoferrin was used to establish a correlation between high affinity binding to SRCL and the presence of multiple clustered terminal Lewisx groups on a heterogeneous mixture of branched glycans, some with poly N-acetyllactosamine extensions. The ability of SRCL to mediate uptake of neutrophil lactoferrin was confirmed using fibroblasts transfected with SRCL. The common presence of Lewisx groups in granule protein glycans can thus target granule proteins for clearance by SRCL. PCR and immunohistochemical analysis confirm that SRCL is widely expressed on endothelial cells and thus represents a distributed system that could scavenge released neutrophil glycoproteins both locally at sites of inflammation or systemically when they are released in the circulation.