MEMBRANE DYNAMICS IN POLARIZED EPITHELIAL CELLS

我们建议研究顶膜分选的分子基础 极化上皮细胞中的蛋白质。 我们将通过比较 对比两种不同的上皮细胞--MDCK （肾脏）和WIF-B（肝细胞）细胞-隔离和包装2 顶端胞外酶 第一种是二肽基肽酶IV（DPPIV）， 属于单跨膜（II型）蛋白类; 第二个是5'核苷酸酶（5' NT），一种糖脂锚定的 蛋白 肝细胞使用间接的，基底外侧到顶端的 这些蛋白质通过胞吞转运途径递送，而MDCK细胞 直接从trans-Golgi网络（TGN）传递它们。 但是，在这方面， 当MDCK细胞从药物的长期治疗中恢复时， Brefeldin A，从该表中检索错分选的DPPIV和5 'NT， 基底外侧表面，随后将其递送至顶端 表面（即使用间接路线）。 多聚IgA受体 （pIgA-R）通常在两种细胞类型中使用转胞吞途径。 做 这些蛋白质和细胞类型共享一个共同的（间接）途径？ 如何 相似或不同的是间接与直接的机制， 顶膜靶向？

We propose to study the molecular basis of sorting of apical membrane proteins in polarized epithelial cells. We will do this by comparing and contrasting how two different epithelial cells types--the MDCK (kidney) and the WIF-B (hepatocyte) cells-- sequester and package two apical ectoenzymes. The first is dipeptidyl peptidase IV (DPPIV), belonging to the class of single transmembrane (Type II) proteins; and the second is 5' nucleotidase (5'NT), a glycolipid-anchored protein. Hepatocytes use an indirect, basolateral-to-apical transcytotic pathway(s) to deliver these proteins, while MDCK cells deliver them directly from the trans-Golgi network (TGN). However, when MDCK cells recover from prolonged treatment with the drug Brefeldin A, the retrieve missorted DPPIV and 5'NT from the basolateral surface and subsequently deliver them to the apical surface (ie, use the indirect route). The polymeric IgA-receptor (pIgA-R) normally uses a transcytotic pathway in both cell types. Do these proteins and cell types share a common (indirect) pathway? How similar or different are the indirect versus direct mechanisms for apical membrane targeting?