MOLECULAR MECHANISMS OF DRUG/XENOBIOTIC ELIMINATION

描述(申请人提供)：有机阴离子转运体(OAT)家族调节多种环境毒素和临床重要药物的吸收、分配和排泄，包括抗HIV治疗药物、抗肿瘤药物、抗生素、抗高血压药物和抗炎药物，因此对哺乳动物物种的生存至关重要。已鉴定出5种燕麦(OAT1、OAT2、OAT3、OAT4和OAT5)，并在肾脏、肝脏、脑和胎盘中检测到它们的表达。燕麦在这些器官中的功能障碍极大地导致了肾、肝、神经和胎儿的毒性和疾病。我们的长期目标是确定通过燕麦蛋白途径处理药物/毒素的分子机制。在上一批赠款期间，取得了重大进展，提高了生产率。我们绘制了燕麦1的膜拓扑图，并确定了燕麦功能的关键氨基酸残基。我们已经证明OAT1在肾脏LLC-PK1细胞中形成同源寡聚体。上一次赠款期间的新发现导致在这次竞争性更新中建立了一项微调的研究计划和战略。我们建议检验这一中心假设，即燕麦在体内不仅形成同源低聚复合体，而且还形成异源低聚复合体，并且燕麦的转运活性是由其寡聚状态决定的。概述了4个具体目标(SA)。在SA-1中，我们将确定燕麦寡聚的性质(同质与杂质齐聚物)。在SA-2中，我们将评估燕麦寡聚在维持其功能方面的重要性。在SA-3中，我们将剖析燕麦寡聚的分子决定因素。在SA-4中，我们将比较燕麦同源和杂合低聚物的药理和调节特性。生物化学、分子生物学和生物物理学的结合方法将被用于拟议的组织切片和培养细胞的研究。从这些研究中获得的知识对于合理设计新药和抑制剂以最大限度地提高治疗效果和最大限度地减少毒性将是非常宝贵的，并将使人们能够深入了解肾、肝、神经和胎儿毒性和疾病的分子、细胞和临床基础。

DESCRIPTION (provided by applicant): The organic anion transporter (OAT) family mediates the absorption, distribution, and excretion of a diverse array of environmental toxins, and clinically important drugs, including anti-HIV therapeutics, anti-tumor drugs, antibiotics, anti-hypertensives, and anti-inflammatories, and therefore is critical for the survival of mammalian species. 5 OATs have been identified (OAT1, OAT2, OAT3, OAT4, and OAT5) and their expression detected in kidney, liver, brain and placenta. OAT dysfunction in these organs significantly contributes to the renal, hepatic, neurological and fetal toxicity and disease. Our long-term goal is to define the molecular mechanisms underlying drug/toxin disposition through the OAT pathway. During the previous grant period, significant progress and productivity have been achieved. We have mapped the membrane topology of OAT 1. We have identified the amino acid residues critical for OAT function. We have showed that OAT1 form homo-oligomer in kidney LLC-PK1 cells. The new findings from the previous grant period led to the establishment of a fine-tuned research plan and strategy in this competing renewal. We propose to test the central hypothesis that OATs form not only homo- but also hetero-oligomeric complexes in vivo and that transport activities of OATs are conferred by their oligomerization states. 4 Specific Aims (SAs) are outlined. In SA-1, we will determine the nature of OAT oligomerization (homo-versus hetero-oligomers). In SA-2, we will assess the importance of OAT oligomerization in maintenance of its function. In SA-3, we will dissect the molecular determinants of OAT oligomerization. In SA-4, we will compare the pharmacological and regulatory properties of OAT homo-and hetero-oligomers. Combined approaches of biochemistry, molecular biology, and biophysics will be employed for the proposed studies in tissue slices, and cultured cells. The knowledge gained from these studies will be invaluable toward the rational design of novel drugs and inhibitors to maximize therapeutic efficacy and minimize toxicity, and will permit insight into the molecular, cellular, and clinical bases of renal, hepatic, neurological and fetal toxicity and disease.