Impact of Cadmium Exposure on Transporter Function and Drug Disposition in the Kidney

项目摘要/摘要 重金属镉(Cd)目前在2019年美国有毒物质和环境保护署中排名第7 疾病登记处(ATSDR)，并被美国环保局列为优先污染物之一 (美国环保署)。虽然高水平镉中毒现已罕见，但慢性低水平镉中毒 暴露仍然是一个主要的健康问题，因为镉是一种累积金属，具有极长的生物半衰期 在人体内存活10-30年。接触镉与多种疾病的发病率增加有关。 引人注目的是，人们几乎不知道长期接触镉是否会影响用于治疗的药物的处置。 疾病。肾转运蛋白通过介导药物跨肾小管细胞转运参与药物处置 尤其是近端小管。通过摄取转运体，如有机的，协调跨细胞转运 基底侧膜上的阳离子转运体(OCTs)和有机阴离子转运体(OATS)与 外排转运体，如多药和毒素排泄蛋白(MATE)和多药耐药相关 肾小管上皮细胞顶膜蛋白(Mrp)被认为是肾脏的重要系统。 分别处理阳离子和阴离子药物。我们最近的出版物和目前的初步结果 表明慢性镉暴露对肾脏转运蛋白包括OCTs、Mate、燕麦和MRP有广泛的影响。 然而，CD调节转运蛋白的详细机制及其对药物处置和 对此的回应还有待说明。我们假设慢性镉暴露可能改变肾脏转运蛋白 功能，导致药物处置的改变和肾脏的毒性。为了检验这一假设，我们建议 以三个具体目标进行研究。首先，通过使用各种细胞和分子分析， 用蛋白质组学的方法，我们将揭示一个分子机制，慢性镉暴露通过增强 OCT和燕麦摄取蛋白从细胞质池转移到细胞膜，从而 增加作为这些转运蛋白底物的小分子在细胞中的积累(目标1)。多数 临床使用的药物不是有机阳离子就是有机阴离子。然后，我们建议演示 Cd暴露对阳离子药物OCT和Mate的影响 在小鼠肾组织和人肾细胞中的表达，特别是对顺铂处置的影响 以及使用Oct1/2和Mate1缺陷小鼠的肾毒性(目标2)。最后，慢性镉暴露的影响 关于阴离子药物转运体燕麦和MRPs在小鼠肾脏组织中的表达 和人肾细胞，特别是镉对抗病毒药物替诺福韦的处置和肾毒性的影响 将在燕麦1/3-，mrp4缺陷小鼠和燕麦药物抑制(目标3)中进行研究。成功 该项目的完成将为发现以前未被承认的环境CD奠定基础 导致药物处置和反应的广泛差异的因素，有助于更好的药物治疗。

PROJECT SUMMARY/ABSTRACT The heavy metal cadmium (Cd) is currently ranked 7th on the 2019 US Agency for Toxic Substances and Disease Registry (ATSDR) and listed as one of Priority Pollutants by US Environmental Protection Agency (EPA). Although intoxication by high levels of Cd exposure is rarely seen nowadays, chronic low levels of Cd exposure is still a major health concern as Cd is a cumulative metal with an extremely long biological half-life of 10-30 years in human body. Cd exposure has been associated with increased incidence of multiple diseases. Strikingly, little is known whether chronic Cd exposure would affect the disposition of drugs that are used to treat diseases. Renal transporter proteins involve in drug disposition by mediating drug transport across tubular cells and particularly proximal tubules. Coordinated transcellular transport by uptake transporters, such as organic cation transporters (OCTs) and organic anion transporters (OATs) in the basolateral membrane in concert with efflux transporters, such as multidrug and toxin extrusion proteins (MATEs) and multidrug resistance-associated proteins (MRPs) in the apical membrane of tubular cells, is believed to be an essential system for renal disposition of cationic and anionic drugs, respectively. Our recent publications and current preliminary results indicate a broad effect by chronic Cd exposure on renal transporters including OCTs, MATEs, OATs and MRPs. However, the detail mechanism of transporter regulation by Cd and its broad impact on drug disposition and response remain to be illustrated. We hypothesize that chronic Cd exposure could alter renal transporter function, resulting in alteration in drug disposition and toxicity in the kidney. To test this hypothesis, we propose to conduct research with three specific Aims. Firstly, by using a variety of cellular and molecular assays, along with proteomic approach, we will uncover a molecular mechanism by which chronic Cd exposure enhances the translocation of OCT and OAT uptake proteins from the cytoplasmic pool to cell membrane and consequently increase the cellular accumulation of small molecules that are the substrates of these transporters (Aim 1). Most clinical used drugs are either organic cations or organic anions. We then propose to demonstrate the impact of Cd exposure on the disposition of cationic drugs by investigating the effects of Cd exposure on OCT and MATE expression in mouse kidney tissues and human renal cells, and particularly the impact on cisplatin disposition and nephrotoxicity using Oct1/2- and Mate1-deficinet mice (Aim 2). Lastly, the effects of chronic Cd exposure on expression of the anionic drug transporters OATs and MRPs will be characterized in mouse kidney tissues and human renal cells, and specifically Cd impact on the disposition and nephrotoxicity of the antiviral tenofovir will be studied with Oat1/3-, Mrp4-deficient mice and OAT pharmacological inhibition (Aim 3). Successful completion of this project will provide a foundation to uncover environmental Cd as a previously unrecognized factor for the broad variation in drug disposition and response, contributing to a better drug theray.