Matsumoto Masanori, Atarashi Kazuyuki, Umemoto Eiji, Furukawa Yuko, Shigeta Akiko, Miyasaka Masayuki, Hirata Takako
Laboratory of Immunodynamics, Department of Microbiology and Immunology, Osaka University Graduate School of Medicine, Japan.
J Immunol. 2005 Dec 15;175(12):8042-50. doi: 10.4049/jimmunol.175.12.8042.
E-selectin, an inducible cell adhesion molecule expressed on endothelial cells, mediates the rolling on endothelium of leukocytes expressing E-selectin ligands, such as neutrophils and activated T cells. Although previous studies using mice lacking P-selectin glycoprotein ligand-1 (PSGL-1) have indicated that PSGL-1 on Th1 cells functions as an E-selectin ligand, the molecular nature of E-selectin ligands other than PSGL-1 remains unknown. In this study, we show that a 130-kDa glycoprotein was precipitated by an E-selectin-IgG chimera from mouse Th1 cells. This protein was cleaved by O-sialoglycoprotein endopeptidase and required sialic acid for E-selectin binding. The mAb 1B11, which recognizes the 130-kDa glycoform of CD43, recognized the 130-kDa band in the E-selectin-IgG precipitate. In addition, immunoprecipitation of the E-selectin-IgG precipitate with 1B11 depleted the 130-kDa protein, further confirming its identity as CD43. CD43 was also precipitated with E-selectin-IgG from cultured human T cells. E-selectin-dependent cell rolling on CD43 was observed under flow conditions using a CD43-IgG chimera generated in Chinese hamster ovary cells expressing alpha-1,3-fucosyltransferase VII and a core 2 beta-1,6-N-acetylglucosaminyltransferase. These results suggest that CD43, when modified by a specific set of glycosyltranferases, can function as an E-selectin ligand and therefore potentially mediate activated T cell migration into inflamed sites.
E选择素是一种在内皮细胞上表达的可诱导细胞黏附分子，介导表达E选择素配体的白细胞（如中性粒细胞和活化T细胞）在内皮上的滚动。尽管先前使用缺乏P选择素糖蛋白配体-1（PSGL-1）的小鼠进行的研究表明，Th1细胞上的PSGL-1作为E选择素配体发挥作用，但除PSGL-1之外的E选择素配体的分子性质仍然未知。在本研究中，我们发现一种130 kDa的糖蛋白可被E选择素-IgG嵌合体从小鼠Th1细胞中沉淀出来。该蛋白可被O-唾液酸糖蛋白内肽酶切割，且E选择素结合需要唾液酸。识别CD43的130 kDa糖型的单克隆抗体1B11识别E选择素-IgG沉淀中的130 kDa条带。此外，用1B11对E选择素-IgG沉淀进行免疫沉淀可使130 kDa蛋白减少，进一步证实其为CD43。CD43也可被E选择素-IgG从培养的人T细胞中沉淀出来。在流动条件下，使用在中国仓鼠卵巢细胞中表达α-1,3-岩藻糖基转移酶VII和核心2 β-1,6-N-乙酰葡糖胺基转移酶产生的CD43-IgG嵌合体观察到E选择素依赖的细胞在CD43上的滚动。这些结果表明，当被一组特定的糖基转移酶修饰时，CD43可作为E选择素配体发挥作用，因此可能介导活化T细胞迁移到炎症部位。
