MECHANISMS FOR RENAL UPTAKE OF MERCURY

描述(申请人提供)：在许多国家，包括美国，汞是一种严重的环境和职业健康危害。汞中毒的主要部位是肾脏，特别是近端小管的直肠部。根据现有的数据，我们提出了以下假设：无机汞作为含有硫醇的生物分子的结合物，被近端肾小管上皮细胞的管腔和基侧质膜摄取，这种摄取通过已知的转运体，如氨基酸和有机阴离子转运体，通过涉及分子模拟的机制发生。汞离子的腔吸收被认为涉及氨基酸转运体，如B0，+，B0，+，或ASC系统，而汞的基侧吸收被认为涉及有机阴离子转运体1和3。为了研究各种转运体在汞吸收中的作用，将使用分离的灌流小管。为了研究单个转运蛋白的作用，将单个转运蛋白RNA注射到非洲爪哇卵母细胞和Madin-Darby犬肾脏和NRK-52E细胞中，稳定地转染单个氨基酸和有机阴离子转运蛋白。将使用功能生化分析来测试每个载体在汞离子传输中的作用。这些实验还将确定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运输的确切机制。

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.