MECHANISMS FOR RENAL UPTAKE OF MERCURY

描述（由申请人提供）：汞在包括美国在内的许多国家都是一种重大的环境和职业健康危害。汞中毒的主要部位是肾脏，特别是近曲小管的直部。根据目前的数据，我们制定了以下假设：无机汞被采取了在管腔和基底侧质膜的近端肾小管上皮细胞作为共轭物的巯基生物分子，这种摄取发生通过已知的转运蛋白，如氨基酸和有机阴离子转运蛋白，通过涉及分子模拟的机制。汞离子的管腔摄取被认为涉及氨基酸转运蛋白，如系统b 0，+、B 0，+或系统ASC，而汞的基底外侧摄取被认为涉及有机阴离子转运蛋白1和3。为了研究各种转运蛋白在汞摄取中的作用，将使用离体灌注小管。为了研究单个转运蛋白的作用，将用单个转运蛋白RNA注射非洲爪蟾卵母细胞，并用单个氨基酸和有机阴离子转运蛋白稳定转染Madin-Darby犬肾和NRK-52 E细胞。每种载体在汞离子转运中的作用将使用功能性生物化学测定法进行测试。这些实验还将确定在质膜上吸收的汞的具体种类。这些研究很重要，因为它们将确定参与汞跨近端肾小管细胞质膜转运的确切机制。

DESCRIPTION (provided by applicant): Mercury is a significant environmental and occupational health hazard in many countries, including the United States. The primary site of mercury toxicity is the kidney, specifically the pars recta of the proximal tubule. Based on current data, we have formulated the following hypothesis: Inorganic mercury is taken up at the luminal and basolateral plasma membranes of the proximal tubular epithelium as a conjugate of thiol-containing biomolecules and this uptake occurs via known transporters, such as amino acid- and organic anion- transporters, through a mechanism involving molecular mimicry. The luminal uptake of mercuric ions is thought to involve amino acid transporters such as systems b0,+ , B0,+, or system ASC, while the basolateral uptake of mercury is thought to involve the organic anion transporters 1 and 3. To study the role of various transporters in the uptake of mercury, isolated perfused tubules will be used. In order to study the role of individual transporters, Xenopus oocytes will be injected with individual transporter RNA and Madin-Darby Canine Kidney and NRK- 52E cells will be stably transfected with individual amino acid- and organic anion- transport proteins. The role of each carrier in the transport of mercuric ions will be tested using functional biochemical assays. These experiments will also determine the specific species of mercury that is taken up at the plasma membrane. These studies are important in that they will determine the exact mechanisms that participate in the transport of mercury across the plasma membranes of the proximal tubular cells.