SALT TRANSPORT IN SURGICAL DIARRHEAL DISEASE

上皮氯化物(C1-)分泌调节缺陷是其基础 几种重要疾病的临床表现 从囊性纤维化到分泌性腹泻 肠道中毒性感染或肠道炎症。虽然相当可观 已经花费了大量的努力来确定顶膜c1的作用。 在这一过程中，人们对渠道的了解相对较少 基底膜事件。这背后的中心假设是 研究表明，基底侧膜Na~+-K~+-2Cl~-共转运体 (NKCC1)是一个关键的独立监管网站，它控制着Net C1- 分泌能力。越来越多的证据表明，NKCC1是 在三个水平上调节：1)受磷酸化依赖和- 协同转运蛋白功能的独立变化，2)由改变的细胞 表面表达，以及3)基因表达的长期变化。 该项目解决了每个监管级别的基本问题。 并以培养的人肠上皮细胞系为模型 系统。胞内Cl-对NKCC1的抑制作用 活动将被定义，并F-潜在的监管作用- NKCC1上的肌动蛋白细胞骨架和酪氨酸激酶信号将被 评估过了。蛋白激酶C对F-肌动蛋白和基底外侧的影响 膜回收将作为改变的一种可能机制进行探索 佛波酯对NKCC1表面表达的影响最后，Long- NKCC1基因表达和C_1分泌的时程变化 将定义炎症性、渗透性和代谢性应激。这个 拟议中的研究应提高对C1C-分泌的理解。 胃肠道、呼吸道和外分泌器官的基础阐明 NKCC1的调控机制。NKCC1在大多数细胞中都有表达， 被认为在控制细胞方面起着普遍的管家作用 体积及其在支持离子矢量传输方面的作用 穿过极化的上皮细胞。我们的长期目标是建立一个 设计新的治疗方法的合理依据 电解液的运输。此外，这些研究可能具有重要的 对这种无处不在的膜运输调控的启示 健康和疾病期间哺乳动物细胞中的蛋白质。

Defective regulation of epithelial chloride (C1-) secretion underlies the clinical manifestations of a number of important diseases ranging from cystic fibrosis to the secretory diarrhea associated with enterotoxic infection or intestinal inflammation. While considerable effort has been expended to define the role of apical membrane C1- channels in this process, comparatively little is known about basolateral membrane events. The central hypothesis underlying this research is that the basolateral membrane Na+-K+-2C1-cotransporter (NKCC1) is a critical independent regulatory site that controls net C1- secretory capacity. Accumulating evidence suggests that NKCC1 is regulated at three levels: 1) by phosphorylation-dependent and - independent changes in cotransporter function, 2) by altered cell surface expression, and 3) by long-term changes in gene expression. This project addresses fundamental questions at each level of regulation and utilizes cultured human intestinal epithelial cell lines as model systems. The inhibitory influence of intracellular C1- on NKCC1 activity will be defined, and the potential regulatory roles of the F- actin cytoskeleton and tyrosine kinase signaling on NKCC1 will be assessed. Effects of protein kinase C on F-actin and basolateral membrane recycling will be explored as a possible mechanism for altered NKCC1 surface expression in response to phorbol ester. Finally, long- term changes in NKCC1 gene expression and C1- secretion in response to inflammatory, osmotic, and metabolic stress will be defined. The proposed studies should improve understanding of C1- secretion in the gastrointestinal tract, airway, and exocrine organs by elucidating basic mechanisms of regulation of NKCC1. NKCC1 is expressed in most cells and is thought to play a generalized housekeeping role in controlling cell volume in addition to its role in supporting vectorial transport of ions across polarized epithelia. The long-term objective is to establish a rational basis for designing new therapeutic approaches to disorders of electrolyte transport. Moreover, these studies may have important implications for the regulation of this ubiquitous membrane transport protein in mammalian cells during health and disease.