Clark V M
Jules Stein Eye Institute, UCLA Center for Health Sciences 90024-7008.
Invest Ophthalmol Vis Sci. 1991 Feb;32(2):327-35.
Previous studies showed that cultured retinal pigment epithelial (RPE) cells from the Royal College of Surgeons (RCS) rat incorporate 50% less fucose into a number of cell-surface glycoproteins compared with controls. The cause of reduced fucose incorporation may be a generalized defect in glycoprotein processing in the RCS rat RPE. This hypothesis has been further explored by comparing the relative sensitivities of normal and dystrophic rat RPE to the toxicity of plant lectins of various specificities. Freshly isolated RPE cells from normal and dystrophic rats were cultured in the presence of increasing concentrations of lectin. For each lectin, the concentration at which less than 10% of the cells survived was determined. These tests showed that the dystrophic RPE cells were more sensitive to lectins that bound to core sugar moieties such as mannose and N-acetylglucosamine; normal RPE cells were more sensitive to lectins which bound to the more terminally located sugars, galactose and N-acetylgalactosamine. Overall, the results suggest that decreased incorporation of fucose into the RCS RPE may be due to failure of the dystrophic RPE to add either N-acetylgalactosamine or galactose (to which fucose is subsequently added) to oligosaccharide structures.
先前的研究表明，与对照组相比，来自皇家外科学院（RCS）大鼠的培养视网膜色素上皮（RPE）细胞将岩藻糖掺入多种细胞表面糖蛋白的量减少了50%。岩藻糖掺入减少的原因可能是RCS大鼠RPE中糖蛋白加工存在普遍缺陷。通过比较正常和营养不良大鼠RPE对各种特异性植物凝集素毒性的相对敏感性，进一步探讨了这一假说。将来自正常和营养不良大鼠的新鲜分离的RPE细胞在浓度不断增加的凝集素存在下进行培养。对于每种凝集素，确定细胞存活率低于10%时的浓度。这些测试表明，营养不良的RPE细胞对与核心糖部分（如甘露糖和N-乙酰葡糖胺）结合的凝集素更敏感；正常RPE细胞对与更末端位置的糖（半乳糖和N-乙酰半乳糖胺）结合的凝集素更敏感。总体而言，结果表明，RCS RPE中岩藻糖掺入减少可能是由于营养不良的RPE无法将N-乙酰半乳糖胺或半乳糖（随后添加岩藻糖）添加到寡糖结构中。
