CELL SECRETION & MEMBRANE FORMATION IN THE PANCREAS

极化分泌上皮细胞具有几种分选装置 以影响分泌和膜蛋白的矢量流， 它们的顶极和基底极。 我们以前的研究 胰腺腺泡细胞已经描绘了 分泌性蛋白质的细胞内转运， 促分泌素激活（调节）途径导致顶端 胞吐作用，而单独的分泌途径导致 基底外侧非刺激性（组成性）基底放电 膜蛋白 类似地，膜的载体递送 蛋白质的顶端和基底外侧极的分泌细胞是 需要建立和维护结构和功能 池性 该项目的目标是确定路线， 组成性和调节性分泌的控制机制 胰腺腺泡和其他上皮细胞中的信号通路， 表征负责生物起源的途径 质膜极性 为此，我们将使用胰腺腺泡 和其他细胞系培养在小室中， 顶端和基底外侧分泌室。 的试剂 干扰分泌蛋白分选将测试它们的能力， 影响差异顶端（如淀粉酶）或基底侧（如 基底层）分泌途径。 这些将包括 促分泌剂、促酸剂、糖基化抑制剂 蛋白质合成和药物生产细胞骨架 拆卸 温度和ATP降低的影响 还将检查水平。 可比实验条件 将与免疫测定结合使用，以确定 顶侧（γ-谷氨酰转移酶）和底侧（胰岛素和 层粘连蛋白受体）膜蛋白递送，以确定因子 调节质膜极性的生物发生， 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 用γ-谷氨酰cDNA转染的MDCX细胞 转移酶，一种顶侧和基底侧膜蛋白， 胰腺腺泡细胞。 最后，我们计划研究 在发育中的胰腺中调节分泌途径， 获得促分泌素反应性。

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.