Department of Chemical and Biological Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
Biochimie. 2013 Dec;95(12):2345-53. doi: 10.1016/j.biochi.2013.08.018. Epub 2013 Aug 28.
Roundabout 1 (Robo1) is the cognate receptor for secreted axon guidance molecule, Slits, which function to direct cellular migration during neuronal development and angiogenesis. The Slit2-Robo1 signaling is modulated by heparan sulfate, a sulfated linear polysaccharide that is abundantly expressed on the cell surface and in the extracellular matrix. Biochemical studies have further shown that heparan sulfate binds to both Slit2 and Robo1 facilitating the ligand-receptor interaction. The structural requirements for heparan sulfate interaction with Robo1 remain unknown. In this report, surface plasmon resonance (SPR) spectroscopy was used to examine the interaction between Robo1 and heparin and other GAGs and determined that heparin binds to Robo1 with an affinity of ~650 nM. SPR solution competition studies with chemically modified heparins further determined that although all sulfo groups on heparin are important for the Robo1-heparin interaction, the N-sulfo and 6-O-sulfo groups are essential for the Robo1-heparin binding. Examination of differently sized heparin oligosaccharides and different GAGs also demonstrated that Robo1 prefers to bind full-length heparin chains and that GAGs with higher sulfation levels show increased Robo1 binding affinities.
盘旋 1 号（Robo1）是分泌性轴突导向分子 Slit 的同源受体，其功能是在神经元发育和血管生成过程中指导细胞迁移。Slit2-Robo1 信号受肝素硫酸酯调节，肝素硫酸酯是一种富含细胞表面和细胞外基质的硫酸线性多糖。生化研究进一步表明，肝素硫酸酯结合 Slit2 和 Robo1，促进配体-受体相互作用。肝素硫酸酯与 Robo1 相互作用的结构要求尚不清楚。在本报告中，表面等离子体共振（SPR）光谱用于研究 Robo1 与肝素和其他 GAGs 之间的相互作用，并确定肝素与 Robo1 的亲和力约为 650 nM。用化学修饰的肝素进行 SPR 溶液竞争研究进一步表明，尽管肝素上的所有硫酸基团对 Robo1-肝素相互作用很重要，但 N-硫酸酯和 6-O-硫酸酯基团对 Robo1-肝素结合至关重要。对不同大小的肝素寡糖和不同 GAGs 的检查还表明，Robo1 更喜欢结合全长肝素链，并且硫酸化水平较高的 GAGs 显示出增加的 Robo1 结合亲和力。
