Philp N J, Yoon M Y, Hock R S
Department of Anatomy, University of Pennsylvania School of Medicine, Philadelphia 19104.
Exp Eye Res. 1990 Aug;51(2):191-8. doi: 10.1016/0014-4835(90)90072-3.
Retinal pigmented epithelial cells are adherent at their basal surface to Bruch's membrane and at their apical surface to the neural retina. We examined the expression and distribution of two proteins that are found in regions of cell-matrix interaction, talin and integrin. Talin is a 235-kDa cytoplasmic protein that has been localized to regions of cell-substrate adhesion. It binds to both integrin, a transmembrane glycoprotein complex, and to vinculin, a cytoskeletal protein. In the present study, we produced a polyclonal antibody to chicken gizzard talin. Using this antibody we showed by western blot analysis that talin is expressed by RPE cells and is found in the triton-soluble fraction. Talin was shown to co-localize with integrin and vinculin in the basal region of chick RPE cells isolated from 18-day-old chick embryos. Neither talin nor integrin was found in the apical processes or in the zonula adherens. Antibodies to vinculin showed staining both in the apical and basal regions of the RPE cells. The localization of integrin, talin and vinculin along the basal membrane suggests that this complex is important in the attachment of the RPE cells to the basement membrane. The distribution of integrin and talin was examined in primary cultures of RPE cells grown on permeable filters. In these cells, a polarized distribution of integrin and talin was not observed. This may suggest that the neural retina may be important for maintaining the differentiated state of the RPE cells.
视网膜色素上皮细胞的基底表面附着于 Bruch 膜，顶端表面附着于神经视网膜。我们检测了在细胞与基质相互作用区域发现的两种蛋白质——踝蛋白（talin）和整合素（integrin）的表达与分布。踝蛋白是一种 235 kDa 的细胞质蛋白，定位于细胞与底物黏附区域。它既与跨膜糖蛋白复合物整合素结合，也与细胞骨架蛋白纽蛋白（vinculin）结合。在本研究中，我们制备了针对鸡肌胃踝蛋白的多克隆抗体。利用该抗体，我们通过蛋白质印迹分析表明，踝蛋白由视网膜色素上皮细胞表达，且存在于 Triton 可溶部分。结果显示，踝蛋白与整合素和纽蛋白在从 18 日龄鸡胚分离的鸡视网膜色素上皮细胞的基底区域共定位。在顶端突起或黏着小带中均未发现踝蛋白和整合素。针对纽蛋白的抗体在视网膜色素上皮细胞的顶端和基底区域均显示出染色。整合素、踝蛋白和纽蛋白沿基底膜的定位表明，该复合物在视网膜色素上皮细胞与基底膜的附着中起重要作用。在生长于可渗透滤膜上的视网膜色素上皮细胞原代培养物中检测了整合素和踝蛋白的分布。在这些细胞中，未观察到整合素和踝蛋白的极化分布。这可能表明神经视网膜对于维持视网膜色素上皮细胞的分化状态可能很重要。
