Vogel J, Bendas G, Bakowsky U, Hummel G, Schmidt R R, Kettmann U, Rothe U
Department of Pharmacy, Martin Luther University Halle, Wolfgang-Langenbeck-Str. 4, 06120 Halle, Germany.
Biochim Biophys Acta. 1998 Jul 17;1372(2):205-15. doi: 10.1016/s0005-2736(98)00058-3.
Selectins constitute a family of proteins that mediate leukocyte tethering and rolling along the vascular endothelium by recognizing various carbohydrate ligands in response to inflammation. To test the hypothesis that multivalent binding of selectins to their ligands is the molecular basis for achieving sufficient binding forces, we have performed this flow chamber study. Selectin-containing Chinese hamster ovarial cells (CHO-E) bind and roll along a support-fixed phospholipid membrane containing a defined concentration of a synthetic Sialyl Lewisx (sLex) glycolipid ligand. Ligands are either homogeneously distributed, or arranged in defined lateral clusters, as illustrated here for the first time. The lateral glycolipid clusters which appear as recognition motifs are essential for mediating cell rolling. Furthermore, the transition from firm cell adhesion to cell rolling depends on the site density of ligands. Rolling velocity shows little dependence on shear forces within a broad range. As we found out that cells do not roll along the model membranes with homogeneous ligand distribution, our results therefore support the hypothesis of multivalent binding events. Since these investigations suggest that lipid-anchored sLex, functionally embedded in a lipid matrix, can mediate cell rolling, this study demonstrates the relationship between dynamic glycolipid binding to selectins with the hypothesis of multivalency of binding for the first time.
选择素是一类蛋白质家族，可通过识别炎症反应中的各种碳水化合物配体，介导白细胞与血管内皮细胞的拴系和滚动。为了验证选择素与其配体的多价结合是实现足够结合力的分子基础这一假说，我们进行了这项流动腔室研究。含选择素的中国仓鼠卵巢细胞（CHO-E）沿着含有一定浓度合成唾液酸化路易斯x（sLex）糖脂配体的支持固定磷脂膜结合并滚动。配体要么均匀分布，要么排列成特定的侧向簇，本文首次对此进行了说明。作为识别基序出现的侧向糖脂簇对于介导细胞滚动至关重要。此外，从牢固的细胞黏附到细胞滚动的转变取决于配体的位点密度。在很宽的范围内，滚动速度对剪切力的依赖性很小。由于我们发现细胞不会沿着配体均匀分布的模型膜滚动，因此我们的结果支持多价结合事件的假说。由于这些研究表明，功能上嵌入脂质基质中的脂质锚定sLex可以介导细胞滚动，因此本研究首次证明了动态糖脂与选择素结合与结合多价性假说之间的关系。
