Rizzolo L J, Zhou S, Li Z Q
Department of Surgery, Yale University School of Medicine, New Haven, CT 06520-8062.
Invest Ophthalmol Vis Sci. 1994 Apr;35(5):2567-76.
The retinal pigment epithelium (RPE) lines the interface between the neural retina and the choroid. Early in chicken development, the beta 1 family of integrins resides in the apical (facing the neural retina) and basolateral (facing the choroid) membranes of RPE. Later in development, integrins reside only in the basolateral membranes, which is more typical of simple transporting epithelia. The authors examined whether the distribution of integrins is regulated by the neural retina.
Individual integrins were examined by studying the individual alpha-subunits that form heterodimers with the beta 1 subunit. The expression and distribution of these subunits were determined by immunoblotting and immunocytochemistry.
Subunits alpha 3 and alpha 6 exemplified contrasting behaviors. Early and late in development, alpha 3 was found only in the basal membranes. As was beta 1, the distribution of alpha 6 was nonpolarized early in development but was basal later in development. The effect of the immature neural retina was determined by reconstituting the RPE:neural retinal interface in explant culture. Absent the neural retina, alpha 6 and beta 1 were removed from the apical membrane. When present, the immature neural retina maintained both subunits in the apical membrane. The neural retina was effective only if the outer (primordial photoreceptor) surface of the retina apposed the RPE.
These data suggest that matrix or intercellular interactions determine the distribution of individual integrins. Further, the changes in integrin distribution during development reflect the maturation of the primordial interphotoreceptor matrix or photoreceptor cell layer.
视网膜色素上皮（RPE）衬于神经视网膜和脉络膜之间的界面。在鸡胚胎发育早期，整合素β1家族定位于RPE的顶端（面向神经视网膜）和基底外侧（面向脉络膜）膜。在发育后期，整合素仅存在于基底外侧膜，这是简单转运上皮细胞更典型的特征。作者研究了整合素的分布是否受神经视网膜调节。
通过研究与β1亚基形成异二聚体的单个α亚基来检测单个整合素。通过免疫印迹和免疫细胞化学确定这些亚基的表达和分布。
α3和α6亚基表现出相反的行为。在发育早期和晚期，α3仅存在于基底膜中。与β1一样，α6在发育早期的分布是非极化的，但在发育后期是基底侧分布。通过在器官培养中重建RPE：神经视网膜界面来确定未成熟神经视网膜的作用。没有神经视网膜时，α6和β1从顶端膜上去除。当存在时，未成熟的神经视网膜将两个亚基都维持在顶端膜上。只有当视网膜的外表面（原始光感受器）与RPE相邻时，神经视网膜才有效。
这些数据表明，基质或细胞间相互作用决定了单个整合素的分布。此外，发育过程中整合素分布的变化反映了原始光感受器间基质或光感受器细胞层的成熟。
