MECHANISMS FOR RENAL UPTAKE OF MERCURY

描述（由申请人提供）：在包括美国在内的许多国家，汞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，特别是近端肾小管的直肠部。基于目前的数据，我们提出了以下假设：无机汞作为含硫醇生物分子的缀合物在近端小管上皮的管腔和基侧质膜上被吸收，这种吸收通过已知的转运体，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。汞离子的腔内摄取被认为涉及氨基酸转运体，如系统b0、+、b0、+或系统ASC，而汞的基底侧摄取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摄取中的作用，将使用分离的灌注小管。为了研究单个转运蛋白的作用，将向爪蟾卵母细胞注射单个转运蛋白RNA，并稳定地向Madin-Darby犬肾和NRK- 52E细胞转染单个氨基酸和有机阴离子转运蛋白。每种载体在汞离子运输中的作用将使用功能性生化分析进行测试。这些实验还将确定被质膜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.