The ligand-binding profile of HARE: hyaluronan and chondroitin sulfates A, C, and D bind to overlapping sites distinct from the sites for heparin, acetylated low-density lipoprotein, dermatan sulfate, and CS-E
The ligand-binding profile of HARE: hyaluronan and chondroitin sulfates A, C, and D bind to overlapping sites distinct from the sites for heparin, acetylated low-density lipoprotein, dermatan sulfate, and CS-E
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DOI：
10.1093/glycob/cwn045
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发表时间：
2008-08-01
期刊：
影响因子：
4.3
通讯作者：
Weigel, Paul H.
中科院分区：
文献类型：
--
作者：
Harris, Edward N.;Weigel, Paul H.
内吞作用的透明质酸受体（HARE）/稳定蛋白-2是透明质酸（HA）、硫酸软骨素（CS）、硫酸皮肤素（DS）和非糖胺聚糖（GAG）配体如乙酰化低密度脂蛋白（AcLDL）、前胶原蛋白前肽和晚期糖基化终产物的主要全身性清道夫受体。我们最近发现HARE也是肝素（Hep）的全身性清道夫受体（Harris EN，Weigel JA，Weigel PH. 2008.内吞作用的人透明质酸受体[HARE/Stabilin-2]是肝素的全身清除受体。J Biol Chem.283：17341-17350）。我们的目标是绘制HARE内八种不同配体的结合位点。我们使用生物素化的GAG和放射性碘化的链霉亲和素或AcLDL，在使用表达用于内吞作用的315或190 kDa HA受体（315-或190-HARE）同种型的稳定细胞系的内吞作用测定中直接或间接（通过与未标记的配体竞争）评估配体的结合活性，并使用纯化的重组可溶性190-HARE胞外域进行ELISA样测定。例如，Hep与HARE的结合被DS、CS-E、AcLDL和硫酸葡聚糖竞争，但不被其他CS类型、HA、葡聚糖或肝素原竞争。Hep和硫酸葡聚糖可部分竞争I-125-AcLDL与HARE的结合，但不被HA竞争。两种配体DS和CS-E在一定程度上与Hep和HA竞争。Hep和HA结合或内吞作用是相互包容的;这两种GAG的结合发生在功能上分离的、非竞争性的和明显非相互作用的结构域。因此，HARE同时结合HA和Hep。尽管负责Hep结合的结构域仍然未知，但HARE与HA、CS-A、CS-C和CS-D结合需要连接结构域。这些结果使我们能够概述，第一次，HARE的多个配体的结合活性图。
The hyaluronic acid receptor for endocytosis (HARE)/ Stabilin-2 is the primary systemic scavenger receptor for hyaluronan (HA), the chondroitin sulfates (CS), dermatan sulfate (DS), and nonglycosaminoglycan (GAG) ligands such as acetylated low-density lipoprotein (AcLDL), pro-collagen propeptides, and advanced glycation end products. We recently discovered that HARE is also a systemic scavenger receptor for heparin (Hep) (Harris EN, Weigel JA, Weigel PH. 2008. The human hyaluronan receptor for endocytosis [HARE/Stabilin-2] is a systemic clearance receptor for heparin. J Biol Chem. 283: 17341-17350). Our goal was to map the binding sites of eight different ligands within HARE. We used biotinylated GAGs and radio-iodinated streptavidin or AcLDL to assess the binding activities of ligands directly or indirectly (by competition with unlabeled ligands) in endocytosis assays using stable cell lines expressing the 315 or 190 kDa HA receptor for endocytosis (315- or 190-HARE) isoforms, and ELISA-like assays, with purified recombinant soluble 190-HARE ecto-domain. For example, Hep binding to HARE was competed by DS, CS-E, AcLDL, and dextran sulfate, but not by other CS types, HA, dextran, or heparosan. I-125-AcLDL binding to HARE was partially competed by Hep and dextran sulfate, but not competed by HA. Two ligands, DS and CS-E, competed with both Hep and HA to some degree. Hep and HA binding or endocytosis is mutually inclusive; binding of these two GAGs occurs with functionally separate, noncompetitive, and apparently noninteracting domains. Thus, HARE binds to HA and Hep simultaneously. Although the domain(s) responsible for Hep binding remains unknown, the Link domain was required for HARE binding to HA, CS-A, CS-C, and CS-D. These results enable us to outline, for the first time, a binding activity map for multiple ligands of HARE.