CELL SECRETION AND MEMBRANE FORMATION IN THE PANCREAS

极化的分泌上皮细胞具有几种分选装置 影响分泌和膜蛋白的载体流动 它们的顶极和基底外侧极。我们之前的研究 胰腺腺泡细胞已经描绘了 分泌蛋白进入细胞内的转座 促分泌剂激活(调节)途径通向心尖 胞吐作用，而另一个单独的分泌途径导致 基底侧无刺激(本构)放电 膜蛋白。同样，膜的载体递送 分泌细胞顶端和基底外侧极的蛋白质 需要建立和维护结构和功能 池塘。该项目的目标是定义路线和 结构性分泌和调节性分泌的调控机制 胰腺腺泡细胞和其他上皮细胞中的通路 描述与生物发生有关的途径 等电极性。为此，我们将使用胰腺腺泡 和其他在小室中培养的细胞株，允许探测 顶端和基底外侧分泌室。符合条件的代理 扰动分泌蛋白分类将测试它们的能力 不同程度地影响顶端(如淀粉酶)或基侧(如 基膜)分泌途径。这些措施包括 促分泌剂、抗酸药物、糖基化抑制剂 蛋白质合成和药物生产细胞骨架 拆卸。温度降低和三磷酸腺苷的影响 等级也将被检查。可比较的实验条件 将与免疫测定一起使用，以测定其极性 心尖部(谷氨酰转移酶)和基底侧部(胰岛素和 层粘连蛋白受体)膜蛋白递送，以定义因子 调控质膜极性的生物发生及澄清 分泌蛋白与膜蛋白的关系 传递途径。我们还将研究膜靶向在 转导γ-谷氨酰化基因的MDCX细胞 转移酶，一种根尖和基底侧膜蛋白 胰腺腺泡细胞。最后，我们计划研究细菌的生物发生 胰腺发育过程中的调节分泌途径 获得促分泌性反应性。

Polarized secretory epithelial cells possess several sorting devices to effect vectorial flow of secretory and membrane proteins to their apical and basolateral poles. Our previous studies on pancreatic acinar cells have delineated the kinetics and routes of intracellular transpost of secretory proteins that enter a secretagogue activated (regulated) pathway leading to apical exocytosis while a separate secretory pathway results in basolateral, nonstimulated (constitutive) discharge of basement membrane proteins. Similarly, vectorial delivery of membrane proteins to the apical and basolateral poles of secretory cells is required to establish and maintain structural and functional poolarity. The goal of this project is to define the routes and control mechanisms for constitutive and regulated secretory pathways in pancreatic acinar and other epithelial cells and to characterize the pathways responsible for biogenesis of plasmalemmal polarity. To this end, we will use pancreatic acinar and other cell lines cultured in chambers that allow probing of apical and basolateral secretory compartments. Agents that perturb secretory protein sorting will be tested for their ability to affect differentially apical (e.g. amylase) or basolateral (e.g. basal lamina) secretory pathways. These will include secretagogues, acidothrophic agents, inhibitors of glycosylation and protein synthesis and drugs producing cytoskeletal disassembly. The effects of reduction in temperature and ATP levels will also be examined. Comparable experimental conditions will be used, in conjunction with immnoassays for polarity of apical (gamma-glutamyl transferase) and basolateral (insulin and laminin receptors) membrane protein delivery, to define factors regulating biogenesis of plasmalemmal polarity and to clarify relationships between secretory protein and membrane protein delivery pathways. We will also examine membrane targeting in MDCX cells transfected with cDNAs for gamma-glutamyl transferase, an apical and basolateral membrane protein in pancreatic acinar cells. Finally, we plan to study biogenesis of the regulated secretory pathway in developing pancreas as it acquires secretagogue responsiveness.