CELLULAR MECHANISMS OF XENOBIOTIC TRANSPORT

异生物运输的细胞机制

• 批准号: 5202273
• 负责人: D S MILLER
• 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/5202273
• 关键词: active transport; alternatives to animals in research; animal tissue; bioenergetics; choroid plexus; confocal scanning microscopy; cytoskeleton; excretion; fluorescence microscopy; intracellular transport; ion transport; kidney cell; membrane transport proteins; microinjections; microtubules; multidrug resistance; renal tubular transport; renal tubule; secretion; tissue /cell culture; toxin metabolism; vesicle /vacuole; video recording system

An important function of the vertebrate kidney is the excretion of potentially toxic chemicals such as waste products of cellular metabolism, xenobiotics and xenobiotic metabolites. This occurs primarily in the proximal tubule where specific renal transport systems remove organic anions and organic cations from peritubular capillaries and move them across the tubular epithelium into the lumen. We are using comparative renal models (proximal tubules from lower vertebrates and invertebrates and mammalian renal cells in culture) in combination with fluorescence microscopy (conventional and confocal), video imaging, intracellular microinjection and isolated membrane vesicle techniques to define the cellular mechanisms that underlie xenobiotic excretion. We have found that organic anions and cations are distributed over two compartments within kidney, liver and choroid plexus cells: one diffuse and cytoplasmic, and the second punctuate and vesicular. Sequestration in intracellular vesicles is not a result of endocytosis, but rather of active uptake from the cytoplasm. Moreover, in proximal tubule, organic anion-containing vesicles appear to move through the cytoplasm in the secretory direction on micro-tubules; this movement contributes substantially to the rate of net secretion. In addition, imaging studies have provided the first demonstration in intact renal tubules of xenobiotic (cyclosporin and daunomycin) secretion mediated by the multidrug resistance (MDR) transporter. This ATP-driven pump is the third major excretory transport system with broad specificity limits present in the renal proximal tubule. Future studies will focus on: 1) characterizing vesicular transport mechanisms driving xenobiotic secretion in proximal tubule, especially interactions with the cytoskeleton, 2) defining the role of the MDR transporter in xenobiotic secretion, 3) identifying the mechanisms that regulate xenobiotic secretion, and 4) characterizing analogous systems in other specialized epithelia that accumulate and transport organic anions and cations, e.g., liver and choroid plexus.

脊椎动物肾脏的一个重要功能是排泄 潜在有毒化学物质，例如细胞废物 代谢、异生物质和异生代谢物。 出现这种情况 主要在近曲小管中，其中有特定的肾转运系统 去除管周毛细血管中的有机阴离子和有机阳离子 并将它们穿过管状上皮进入管腔。 我们正在使用 比较肾脏模型（来自低等脊椎动物和 无脊椎动物和培养的哺乳动物肾细胞）与 荧光显微镜（传统和共焦）、视频成像、 细胞内显微注射和分离膜囊泡技术 定义外源物质排泄的细胞机制。我们 发现有机阴离子和阳离子分布在两个 肾、肝和脉络丛细胞内的隔室：一个弥漫性 和细胞质，第二个是点状和泡状的。封存 细胞内囊泡的作用不是内吞作用的结果，而是 从细胞质中主动摄取。此外，在近曲小管中，有机质 含阴离子的囊泡似乎在细胞质中移动 微管的分泌方向；这项运动有助于 与净分泌率基本一致。 此外，影像学研究 首次在完整的肾小管中进行了演示 异生素（环孢菌素和道诺霉素）的分泌由 多药耐药性（MDR）转运蛋白。这个 ATP 驱动泵是第三个 存在广泛特异性限制的主要排泄运输系统 在肾近曲小管中。 未来的研究将集中在：1） 表征驱动异生物质的囊泡运输机制 近曲小管的分泌，特别是与 细胞骨架，2) 定义 MDR 转运蛋白在异生素中的作用 分泌，3）确定调节外源性物质的机制 分泌，以及 4) 表征其他专业中的类似系统 积累和运输有机阴离子和阳离子的上皮细胞，例如， 肝脏和脉络丛。