Molecular Organization of Renal Organic Anion Transport

描述（由申请人提供）：肾脏是从体内排泄大量具有生理、药理学和毒理学意义的阴离子化合物（包括对内酰胺类抗生素、核苷衍生的抗病毒化合物、非甾体抗炎药（NSAIDs）和非甾体抗炎药（NSAIDs））的主要途径。阴离子螯合剂和重金属螯合剂)。此外，肾脏与肝脏在控制血浆II期代谢中许多其他阴离子代谢物的水平方面起着关键的辅助作用。这些有机阴离子（OAs）的肾脏排泄是由肾近端小管（RPT）细胞介导的经上皮分泌过程主导的。近年来，越来越多的证据支持这样一种观点，即OAs的肾脏分泌涉及许多单独的转运蛋白的协同活动，这些转运蛋白在RPTs的基底外侧（小管周围）和顶端（管腔）膜中表达。虽然现在对基底外侧的“进入步骤”已经有了相当好的了解，但对于我们对肾脏OA分泌的理解而言，RPT的管腔膜代表了“月球的阴暗面”。尽管至少有8种不同的转运蛋白已被证明在RPT的管腔膜中表达，但这些潜在的“候选”管腔转运蛋白对肾脏OA分泌的影响程度尚不清楚。这里提出的实验代表了一个综合的研究项目，旨在确定一组腔内转运蛋白，即多药耐药相关蛋白（MRPs）对肾脏OA分泌的贡献。我们将克隆转运蛋白和模型培养细胞系统的使用与使用完整肾小管和完整动物的研究相结合。我们将开发模型系统，培养表达克隆转运蛋白的细胞，以评估两种不同的基底外侧“有机阴离子转运蛋白”转运蛋白（燕麦，即OAT1和OAT3）和两种不同的腔内转运蛋白（即MRP2和MRP4）的分泌的相对贡献。这些模型细胞将提供设计和解释实验所需的数据，这些实验使用分离的单个肾近端小管和全肾清除率测量，采用野生型小鼠和缺乏选定OA转运蛋白的遗传模型。这项研究计划的创新设计允许在三个不同的生物组织水平上评估分泌的机制基础：分子和细胞；上皮细胞/组织;和整个器官/有机体，并将首次发展的观点，在药物-药物相互作用和肾毒性的发展管腔和基底侧事件的潜在作用。

DESCRIPTION (provided by applicant): The kidney is the principal means for excretion from the body of a vast array of anionic compounds of physiological, pharmacological and toxicological significance (including p-lactam antibiotics; nucleoside- derived antiviral compounds; non-steroidal anti-inflammatory drugs (NSAIDs); and anionic chelators and chelates of heavy metals). In addition, the kidney plays a critical auxiliary role with the liver in controlling plasma levels of many other anionic metabolites of Phase II metabolism. Renal excretion of these organic anions (OAs) is dominated by the processes of transepithelial secretion mediated by cells of the renal proximal tubule (RPT). In recent years, increasing evidence supports the contention that renal secretion of OAs involves the concerted activity of many separate transport proteins that are expressed in the basolateral (peritubular) and apical (luminal) membranes of RPTs. Although the basolateral 'entry step' is now reasonably well understood, the luminal membrane of the RPT represents 'the dark side of the moon' with respect to our understanding of renal OA secretion. Despite the fact that at least 8 distinct transporters have been shown to be expressed in the luminal membrane of RPT for none of these potential 'candidate' luminal transporters is the extent of their influence on renal OA secretion understood. The experiments proposed here represent an integrated program of study designed to establish the contribution to renal OA secretion of one group of luminal transporters, i.e., the multidrug resistance-associate proteins (the MRPs). We combine the use of cloned transport proteins and model cultured cell systems with studies that employ intact renal tubules and intact animals. We will develop model systems that cultured cells expressing cloned transport proteins to assess the relative contribution to secretion of two distinct basolateral 'organic anion transporters' transporters (OATs; i.e., OAT1 and OAT3) and two distinct luminal transporters (i.e., MRP2 and MRP4). These model cells will provide data required to design and interpret experiments using isolated single renal proximal tubules and whole renal clearance measurements that employ both wild type mice and genetic models that lack selected OA transporters. The innovative design of this research program permits assessment of the mechanistic basis of secretion at three distinct levels of biological organization: the molecular and cellular; the epithelial/tissue; and the whole organ/organismic, and will develop for the first time a view of the potential role of both luminal and basolateral events in drug-drug interactions and the development of nephrotoxicity.