Wollner D A, Krzeminski K A, Nelson W J
Department of Molecular and Cellular Physiology, Stanford University School of Medicine, California 94305-5426.
J Cell Biol. 1992 Feb;116(4):889-99. doi: 10.1083/jcb.116.4.889.
The development of polarized epithelial cells from unpolarized precursor cells follows induction of cell-cell contacts and requires resorting of proteins into different membrane domains. We show that in MDCK cells the distributions of two membrane proteins, Dg-1 and E-cadherin, become restricted to the basal-lateral membrane domain within 8 h of cell-cell contact. During this time, however, 60-80% of newly synthesized Dg-1 and E-cadherin is delivered directly to the forming apical membrane and then rapidly removed, while the remainder is delivered to the basal-lateral membrane and has a longer residence time. Direct delivery of greater than 95% of these proteins from the Golgi complex to the basal-lateral membrane occurs greater than 48 h later. In contrast, we show that two apical proteins are efficiently delivered and restricted to the apical cell surface within 2 h after cell-cell contact. These results provide insight into mechanisms involved in the development of epithelial cell surface polarity, and the establishment of protein sorting pathways in polarized cells.
从非极化前体细胞发育出极化上皮细胞是在细胞间接触诱导之后发生的，并且需要将蛋白质重新分配到不同的膜结构域。我们发现，在MDCK细胞中，两种膜蛋白Dg-1和E-钙黏蛋白的分布在细胞间接触后的8小时内会局限于基底外侧膜结构域。然而，在此期间，新合成的Dg-1和E-钙黏蛋白中有60%-80%会直接被转运至正在形成的顶端膜，然后迅速被移除，而其余部分则被转运至基底外侧膜，并且停留时间更长。这些蛋白质超过95%从高尔基体复合体直接转运至基底外侧膜的情况会在48小时之后才出现。相比之下，我们发现两种顶端蛋白在细胞间接触后2小时内就能有效地被转运并局限于顶端细胞表面。这些结果为上皮细胞表面极性发育所涉及的机制以及极化细胞中蛋白质分选途径的建立提供了深入了解。
