ROLE OF ALTERED MEMBRANE FUNCTION IN XENOBIOTIC TOXICITY

膜功能改变在异生物毒性中的作用

• 批准号: 3755499
• 负责人: J B PRITCHARD
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3755499
• 关键词: Xenopus oocyte; acidity /alkalinity; alpha ketoglutarate; bioenergetics; dichloroacetate; epithelium; intracellular transport; ion transport; kidney function; membrane transport proteins; molecular cloning; protein kinase C; renal tubular transport; secretion; tissue /cell culture; toxin metabolism; vesicle /vacuole

In recent years, we have examined the mechanism and energetics of renal organic anion (OA) and cation (OC) transport. These are the primary systems which govern the elimination of foreign chemicals. OA transport was shown to be indirectly coupled to metabolic energy through Na/alpha- ketoglutarate (alphaKG) co-transport and OA/alphaKG exhange. We are currently examinng both plasma membrane and intracellular events associated with secretory transport and initiating studies of the molecular biology of these systems. This work indicates that the rate of OA transport may be modulated by manipulations which alter either the internal alphaKG concentration or its in-to-out gradient. In addition, imaging studies indicate that sequestration within intracellular vesicles reduces the cytoplasmic OA concentrations, apparently protecting intracellular sites during secretion. Sequestration of OA is both carrier mediated and energy dependent. OC are also sequestered, suggesting that vesicular packaging may be a general means of protecting transporting epithelial cells during secretion. The mechanism of OC sequestration was a secondary active proton/OC exchange, driven by a proton-ATPase present in these endosomal vesicles. Initial evidence indicates that these vesicles move in a basolateral to apical direction, raising the possibility that they may also play a direct role in transcellular movement of secreted xenobiotics. Expression cloning techniques are currently in use to identify and clone specific membrane proteins responsible for individual transport steps in secretion of foreign anions and cations. Finally, cell culture techniques have been applied to develop intact epithelial sheet preparations for analysis of these transport systems, their control mechanisms, and their sensitivity to xenobiotic toxicity. These studies have shown for the first time that a renal line (the OK cell) demonstrates OA secretion and in comparison with primary cultures of rat proximal tubule, they provide a means to analyze control of transepithelial OA and OC transport in intact epithelial.

近年来，我们检查了肾脏的机制和能量学 有机阴离子（OA）和阳离子（OC）运输。 这些是主要的 控制消除外国化学物质的系统。 OA运输 被证明通过Na/alpha-间接耦合到代谢能 Ketoglutarate（Alphakg）共同传输和OA/Alphakg Enkange。 我们是 目前检查质膜和细胞内事件 与分泌运输和启动研究有关 这些系统的分子生物学。 这项工作表明费率 OA运输的运输可能会通过改变的操作来调节 内部alphakg浓度或其内向梯度。 此外， 成像研究表明细胞内隔离 囊泡降低了细胞质OA浓度，显然 在分泌过程中保护细胞内部位。 OA的隔离为 载体介导和依赖能量。 OC也被隔离， 暗示囊泡包装可能是保护的一般手段 分泌过程中运输上皮细胞。 OC的机制 隔离是由A驱动的次级活动质子/OC交换 这些内体囊泡中存在质子ATPase。 最初的证据 表明这些囊泡在基底外侧移动到顶方向， 提高他们也可能在 分泌异生元的跨细胞运动。 表达克隆 目前正在使用技术来识别和克隆特定的膜 蛋白质负责分泌的个人运输步骤 外国阴离子和阳离子。 最后，细胞培养技术已经 应用于开发完整的上皮床单准备，以分析 这些运输系统，其控制机制及其敏感性 Xenobiotic毒性。 这些研究首次表明 肾线（OK单元）展示了OA的分泌和 与大鼠近端小管的一级培养物进行比较，它们提供了 分析对跨跨型OA和OC转运的控制的手段 完整的上皮。