CADMIUM, COBALT, NICKEL EFFECT ON SIGNAL TRANSDUCTION IN SHARK RECTAL GLAND

该应用程序通过膜毒理学中心寻求支持 荒漠山岛生物实验室的研究(CMTS) 三种重金属(镉、钴、镍)的效应研究 激素调节氯离子分泌的信号转导途径 在鲨鱼的直肠腺里。鲨鱼直肠腺是一种同质的、单一的 细胞类型，高度特化的上皮细胞，是一个模型系统 激素调节氯化物的分泌。我们的假设是有毒的 重金属在不同土壤中的交互作用效应 刺激的部位，而不是抑制的激素信号 转导通路。我们已经确定镉可以可逆地阻止 受体介导的氯离子分泌抑制，以及主要的 这种效应的组成部分通过一种新的和意想不到的机制发生--以及 增强对刺激性激素的反应。我们将决定 通过区分这种金属-蛋白质相互作用的特定部位(S) 镉对(A)细胞外镉受体的影响 介导三磷酸肌醇的活化和释放 细胞内钙离子；(B)对环状病毒特异性同工酶的直接影响 核苷酸磷酸二酯酶；和(C)受体/激酶后机制- DFTR-氯通道从胞内位置到胞内位置的移位 顶端质膜。与镉相反，钴和镍抑制VIP Forsklin刺激灌流直肠腺的氯化物分泌。 与中心的其他人合作，我们将确定蛋白质 互动网站(S)对这些金属和有毒物质的区别 钙信使系统及其在心尖DFTR中的直接作用 频道。研究将在体外灌流的直肠中进行。 在原代培养的直肠腺细胞单层中，以及在 表达DFTR氯通道的非洲爪哇卵母细胞。

This application seeks support through the Center for Membrane Toxicology Studies (CMTS) at the Mount Desert Island Biological Laboratory for studies on the effects of three heavy metals (cadmium, cobalt and nickel) on signal transduction pathways of hormones regulating chloride secretion in the shark rectal gland. The shark rectal gland is a homogenous, single cell type, highly specialized epithelium that is a model system for hormone regulated chloride secretion. Our hypothesis is that the toxic effects of heavy metals results from interactions at different specific sites of stimulatory as opposed to inhibitory hormonal signal transduction pathways. We have determined that cadmium reversibly blocks receptor-mediated inhibition of chloride secretion and that a major component of this effect occurs by a novel and unexpected mechanism- and augmentation of the response to stimulatory hormones. We will determine the specific site(s) of this metal-protein interaction by distinguishing between effects of cadmium on (a) an extracellular receptor for Cd mediating activation of inositol triphosphates and release of intracellular calcium; (b) direct effects on specific isozyme of cyclic nucleotide phosphodiesterases; and (c) a post-receptor/kinase mechanism- translocation of DFTR-chloride channels from an intracellular site to the apical plasma membrane. In contrast to Cd, cobalt and nickel inhibit VIP and forskolin stimulated chloride secretion in the perfused rectal gland. In collaboration with others in the center we will determine the protein interactive site(s) of these metals and distinguish between toxic effects on the calcium messenger system and direct actions on apical DFTR channels. Studies will be carried out in the in vitro perfused rectal gland, in primary culture monolayers of rectal gland cells, and in Xenopus oocytes expressing the DFTR chloride channel.