Spiro R C, Casteel H E, Laufer D M, Reisfeld R A, Harper J R
Department of Immunology, Research Institute of Scripps Clinic, La Jolla, California 92037.
J Biol Chem. 1989 Jan 25;264(3):1779-86.
A melanoma proteoglycan model system has been used to examine the role of core protein asparagine-linked (N-linked) oligosaccharides in the transport and assembly of proteoglycan molecules. The use of agents which block discrete steps in the trimming and processing of core oligosaccharides (castanospermine, 1-deoxynojirimycin, N-methyldeoxynojirimycin, 1-deoxymannojirimycin, and swainsonine) demonstrates that removal of glucose residues from the N-linked oligosaccharides is required for the cell surface expression of a melanoma proteoglycan core protein and for the conversion of the core protein to a chondroitin sulfate proteoglycan. However, complete maturation of the oligosaccharides to a "complex" form is not required for these events. Treatment of M21 human melanoma cells with the glucosidase inhibitors castanospermine, 1-deoxynojirimycin, or N-methyldeoxynojirimycin results in a dose-dependent inhibition of glycosaminoglycan (GAG) addition to the melanoma antigen recognized by monoclonal antibody 9.2.27. In contrast, treatment with the mannosidase inhibitors 1-deoxymannojirimycin and swainsonine does not effect GAG addition. Identical results are obtained when the major histocompatibility complex class II antigen gamma chain proteoglycan is examined in inhibitor-treated melanoma and B-lymphoblastoid cells. These data, in conjunction with the known effects of the glucosidase and mannosidase inhibitors on the transport and secretion of other glycoproteins support the hypothesis that the addition, trimming, and processing of N-linked oligosaccharides is involved in the transport of certain proteoglycan core proteins to the site of GAG addition and to the cell surface.
一种黑色素瘤蛋白聚糖模型系统已被用于研究核心蛋白天冬酰胺连接的（N-连接的）寡糖在蛋白聚糖分子的转运和组装中的作用。使用能阻断核心寡糖修剪和加工过程中离散步骤的试剂（栗精胺、1-脱氧野尻霉素、N-甲基脱氧野尻霉素、1-脱氧甘露野尻霉素和苦马豆素）表明，从N-连接的寡糖中去除葡萄糖残基是黑色素瘤蛋白聚糖核心蛋白在细胞表面表达以及核心蛋白转化为硫酸软骨素蛋白聚糖所必需的。然而，这些事件并不需要寡糖完全成熟为“复杂”形式。用葡糖苷酶抑制剂栗精胺、1-脱氧野尻霉素或N-甲基脱氧野尻霉素处理M21人黑色素瘤细胞，会导致对单克隆抗体9.2.27识别的黑色素瘤抗原的糖胺聚糖（GAG）添加的剂量依赖性抑制。相比之下，用甘露糖苷酶抑制剂1-脱氧甘露野尻霉素和苦马豆素处理不会影响GAG的添加。当在抑制剂处理的黑色素瘤细胞和B淋巴细胞样细胞中检测主要组织相容性复合体II类抗原γ链蛋白聚糖时，得到了相同的结果。这些数据，结合葡糖苷酶和甘露糖苷酶抑制剂对其他糖蛋白的转运和分泌的已知影响，支持了以下假设：N-连接寡糖的添加、修剪和加工参与了某些蛋白聚糖核心蛋白向GAG添加位点和细胞表面的转运。
