Needham L K, Schnaar R L
Department of Pharmacology, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
Proc Natl Acad Sci U S A. 1993 Feb 15;90(4):1359-63. doi: 10.1073/pnas.90.4.1359.
E-selectin, L-selectin, and P-selectin are related cell adhesion molecules that bind via their lectin domains to sialyl Lewis x and related carbohydrate determinants. Reports have indicated that sulfated glycolipids and polysaccharides also bind selectins. To extend these findings, we compared binding of selectin-IgG chimeras to immobilized sulfated and sialylated glycosphingolipids. E-, L-, and P-selectin chimeras all bound to surfaces absorbed with 2,3-sialyl Lewis x glycolipid or sulfatide (galactosylceramide I3-sulfate) but not to surfaces adsorbed with control sulfated lipids (octadecyl sulfate, sphingosine sulfate). Notably, the L- and P-selectin chimeras but not E-selectin chimera bound to surfaces adsorbed with sulfoglucuronyl glycosphingolipids (SGNL lipids; e.g., IV3 glucuronylneolactotetraosylceramide V3-sulfate). These unusual lipids have been reported as antigenic determinants for monoclonal IgM antibodies produced in patients with neuropathy associated with paraproteinemia and react with the mouse monoclonal antibody HNK-1. Binding of L- and P-selectin chimeras to SGNL lipids was specifically inhibited by appropriate anti-selectin antibodies. While binding of all three selectin chimeras to sialyl Lewis x was blocked by removal of calcium, binding to SGNL lipid was only modestly reduced by EDTA. Chemically desulfated SGNL lipid retained binding activity for L- and P-selectin chimeras, while methyl esterification of the glucuronic acid eliminated binding. We conclude that SGNL lipids, unlike sialyl Lewis x and sulfatides, selectively support L- and P-selectin but not E-selectin chimera binding. The presence of SGNL lipids on brain microvascular endothelium (and other endothelia) may implicate these molecules in leukocyte trafficking to the nervous system and elsewhere.
E-选择素、L-选择素和P-选择素是相关的细胞黏附分子,它们通过其凝集素结构域与唾液酸化路易斯x及相关碳水化合物决定簇结合。报告表明,硫酸化糖脂和多糖也能结合选择素。为扩展这些发现,我们比较了选择素-IgG嵌合体与固定化硫酸化和唾液酸化糖鞘脂的结合情况。E-、L-和P-选择素嵌合体均能与吸附有2,3-唾液酸化路易斯x糖脂或硫苷脂(半乳糖神经酰胺I3-硫酸盐)的表面结合,但不能与吸附有对照硫酸化脂质(十八烷基硫酸盐、鞘氨醇硫酸盐)的表面结合。值得注意的是,L-和P-选择素嵌合体而非E-选择素嵌合体能与吸附有硫酸葡萄糖醛酸糖鞘脂(SGNL脂质;例如,IV3葡萄糖醛酸新乳糖四糖神经酰胺V3-硫酸盐)的表面结合。这些特殊脂质已被报道为与副蛋白血症相关的神经病患者产生的单克隆IgM抗体的抗原决定簇,并能与小鼠单克隆抗体HNK-1发生反应。L-和P-选择素嵌合体与SGNL脂质的结合被相应的抗选择素抗体特异性抑制。虽然去除钙会阻断所有三种选择素嵌合体与唾液酸化路易斯x的结合,但EDTA仅适度降低其与SGNL脂质的结合。化学去硫酸化的SGNL脂质保留了与L-和P-选择素嵌合体的结合活性,而葡萄糖醛酸的甲酯化则消除了结合。我们得出结论,与唾液酸化路易斯x和硫苷脂不同,SGNL脂质选择性地支持L-和P-选择素嵌合体的结合,而不支持E-选择素嵌合体的结合。脑微血管内皮(及其他内皮)上存在SGNL脂质可能表明这些分子在白细胞向神经系统及其他部位的转运中起作用。