RENAL TRANSPORT OF ORGANIC CHELATORS OF HEAVY METALS

重金属有机螯合剂的肾脏转运

• 批准号: 6500207
• 负责人: STEPHEN H WRIGHT
• 金额: $ 1.57万
• 依托单位: UNIVERSITY OF ARIZONA
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-02-01 至 2005-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6500207
• 关键词: Xenopus; Xenopus oocyte; anions; arsenic; chelating agents; chemical conjugate; complementary DNA; epithelium; human tissue; ion transport; laboratory rabbit; membrane transport proteins; mercury; metal metabolism; polymerase chain reaction; renal tubular transport

DESCRIPTION: (Adapted from the Applicant's Abstract): The long term goal of the proposed program of research is to understand the cellular mechanisms associated with the entrance and exit from renal cells of organic conjugates and chelates of heavy metals. Because these complexes carry a net negative charge, it has been assumed that the classical 'renal organic anion secretory pathway' plays a central role in the renal elimination of these compounds. While this may be true, there is no direct evidence that uptake or elimination of metal-containing complexes involves this process. Indeed, the cellular basis for clearance of anionic metal chelates from intoxicated cells is unknown. The mechanism by which the kidney secretes organic anions (OAs) has, in fact, received considerable attention, and a cellular model of OA secretion, for which p-aminohippurate (PAH) is considered the prototypic substrate, has been widely accepted. New evidence, however, suggests that renal OA secretion involves several distinct transporters with overlapping selectivity. Consequently, the overarching goal of the this study, i.e., establishing the mechanism of renal transport of anionic metal complexes, must be placed into the following context: the several, distinct mechanisms involved in renal transport of organic anions (OAs) have only recently begun to be identified, and the relative role played by each in renal secretion is largely unknown. We outline here, in two Specific Aims, experiments that examine characteristics of individual OA transporters, and their integrated behavior when working in concert with multiple processes in native renal tubules. We focus on several transporters: OAT1 (renal organic anion transporter); OAT-K2 (a renal homologue of the organic anion transporting polypeptide); and Mrp2 (the apical membrane homologue of the family of multidrug resistance-associated transport proteins). These transporters were selected because current evidence on their substrate specificity and their distribution within renal proximal tubules suggests that they can interact with anionic chelators and/or their heavy metal chelates. In Aim 1, we will determine, using heterologous expression systems, the extent to which these OA transporters interact with a common set of test substrates and inhibitors (including the anionic chelator 2,3-dimercapto-l-propanesulfonate [DMSP] and its mercury and arsenic-containing chelates). The information obtained in these experiments will be applied in Aim 2, which will examine the integrated behavior of these processes in (i) a model cell culture system containing selected combinations of these processes; and (ii) intact proximal tubules in which OA secretion is the product of a suite of transporters working in the physiological contex of the intact cell. The studies with intact tubules will include direct tests of the hypothesis that DMPS-metal chelates are exported from renal cells through interaction with Mrp2 and OAT-K2. The proposed studies will result in a new, general model of the cellular strategy for secretion of a diverse array of xenobiotic OAs, and a more specific understanding of the action of heavy metal chelators on renal cells.

描述：（改编自申请人的摘要）： 一项研究计划旨在了解细胞机制， 与有机结合物进入和离开肾细胞有关 和重金属的螯合物。因为这些络合物带有净负电荷 电荷，它已被假定为经典的“肾有机阴离子分泌 在这些化合物的肾消除中起着中心作用。 虽然这可能是真的，但没有直接证据表明， 含金属配合物的合成涉及这一过程。事实上，细胞基础 从中毒细胞中清除阴离子金属螯合物的能力是未知的。的 肾脏分泌有机阴离子（OAs）的机制，事实上， 受到了相当大的关注，OA分泌的细胞模型， 对氨基马尿酸（PAH）被认为是原型底物， 被广泛接受。然而，新的证据表明，肾脏OA分泌 涉及具有重叠选择性的几种不同的转运蛋白。 因此，本研究的总体目标，即，建立 阴离子金属络合物的肾转运机制，必须置于 以下内容：肾脏疾病涉及的几种不同机制 有机阴离子（OAs）的迁移最近才开始被识别， 并且它们各自在肾分泌中的相对作用在很大程度上是未知的。我们 在这里，在两个具体目标中，概述了检查 个体OA转运蛋白，以及它们在 与天然肾小管中的多个过程一致。我们专注于几个 转运蛋白：OAT 1（肾有机阴离子转运蛋白）; OAT-K2（肾同系物 有机阴离子转运多肽）;和Mrp 2（顶膜 多药耐药相关转运蛋白家族的同源物）。 选择这些转运蛋白是因为目前的证据表明， 特异性及其在肾近端小管内的分布表明， 它们可以与阴离子螯合剂和/或它们的重金属螯合物相互作用。在 目的1，我们将确定，使用异源表达系统， 这些OA转运蛋白与一组共同的测试底物相互作用， 抑制剂（包括阴离子螯合剂2，3-二巯基-1-丙磺酸盐[DMSP]） 及其含汞和砷的螯合物）。 在这些信息中获得的信息 实验将应用于目标2，这将检查这些的综合行为 在（i）含有这些的选择的组合的模型细胞培养系统中的方法， 过程;和（ii）完整的近端小管，其中OA分泌是一套 在完整细胞的生理环境中工作的转运蛋白。 研究与 完整的肾小管将包括DMPS-金属螯合物是 通过与Mrp 2和OAT-K2相互作用从肾细胞输出。 拟议 研究将导致一个新的，一般的细胞分泌策略模型， 多样的异生素OAs阵列，以及对该行动的更具体的理解， 重金属螯合剂对肾细胞的影响