Gordon S R, Czerwinski-Mowers D, Marchand J, Shuffett R
Department of Biological Sciences, Oakland University, Rochester, MI 48309-4476, USA.
Histochem Cell Biol. 1998 Sep;110(3):251-62. doi: 10.1007/s004180050287.
Binding, internalization, and movement of hemeproteins and peroxidase-conjugated lectins across organ cultured rat corneal endothelia has been investigated. Horseradish peroxidase (HRP) type II, bound to the surface, was minimally internalized and was easily washed off. In contrast, HRP-VI bound and was rapidly internalized. Reaction product was observed in vesicles, endosomes, multivesicular bodies, and extended along the length of the intercellular space (ICS) to Descemet's membrane. Studies at 4 degrees C indicated HRP-VI bound uniformly along the surface in a punctate fashion. Exposure to polylysine or mannose significantly decreased uptake. Other tracers such as HRP-VIII, -IX, catalase, and microperoxidase exhibited limited uptake by the tissue. However, endothelia vigorously internalized soybean agglutinin (SBA)-HRP, and reaction product was found intracellularly and within the ICS at the cell/Descemet's membrane interface. Internalization and the appearance of SBA-HRP within the ICS was diminished following polylysine or mannose treatment. Experiments at 4 degrees C indicated that SBA-HRP binding and uptake were temperature sensitive. Wheat germ agglutinin (WGA)-HRP was also strongly endocytosed and reaction product was visualized within vesicles, endosomes, and multivesicular bodies. Although WGA-HRP reaction product was observed within the ICS, none was detected at the level of Descemet's membrane. The WGA competitive sugar N-acetyl-D-glucosamine, reduced endocytosis, whereas exposure to unlabeled WGA and mannose together reduced uptake. These results indicate endothelia exhibit differential uptake of various hemeproteins and lectins which is dependent on charge, mannose receptors, and appropriate surface sugars.
已经研究了血红素蛋白和过氧化物酶结合的凝集素在器官培养的大鼠角膜内皮细胞中的结合、内化及转运情况。结合在表面的II型辣根过氧化物酶（HRP）极少被内化，且很容易被冲洗掉。相比之下，HRP-VI能结合并迅速被内化。在小泡、内体、多囊泡体中观察到反应产物，并沿着细胞间间隙（ICS）延伸至Descemet膜。4℃下的研究表明，HRP-VI以点状方式均匀地结合在表面。暴露于多聚赖氨酸或甘露糖会显著降低摄取量。其他示踪剂如HRP-VIII、-IX、过氧化氢酶和微过氧化物酶在组织中的摄取有限。然而，内皮细胞能强烈内化大豆凝集素（SBA）-HRP，并且在细胞内以及细胞/Descemet膜界面的ICS内发现了反应产物。用多聚赖氨酸或甘露糖处理后，SBA-HRP在ICS内的内化及出现情况减少。4℃下的实验表明，SBA-HRP的结合和摄取对温度敏感。小麦胚凝集素（WGA）-HRP也被强烈内吞，并且在小泡、内体和多囊泡体内观察到反应产物。尽管在ICS内观察到了WGA-HRP反应产物，但在Descemet膜水平未检测到。WGA的竞争性糖N-乙酰-D-葡萄糖胺减少了内吞作用，而同时暴露于未标记的WGA和甘露糖会减少摄取。这些结果表明，内皮细胞对各种血红素蛋白和凝集素的摄取存在差异，这取决于电荷、甘露糖受体和合适的表面糖。
