MECHANISMS OF CADMIUM TOXICITY IN EPITHELIAL CELLS

镉(Cd_2)是一种重要的工业和环境污染物 已经被证明会对各种器官造成严重损害，而且 具有致突变、致畸和致癌活性。尽管它有 作为一个环境健康问题的重要性，人们相对知之甚少 关于CD2的特定细胞和分子机制 产生了它的许多效果。这个项目的长期目标是 找出其中一些机制。文献中的报告表明 CD2在体内的一些作用可能是由于干扰了 不同上皮或内皮细胞表面的细胞之间的连接。至 对这种可能性进行了更详细的研究，以 检测CD2在细胞-细胞连接中的作用 猪肾上皮细胞系LLC-PK1。这些研究的结果是 表明CD2对黏附和黏附有特定的破坏作用 阻断LLC-PK1细胞之间的连接，这些作用可能 涉及CD2与钙依赖的E-钙粘蛋白的相互作用 糖蛋白，在上皮细胞与细胞间的黏附中起关键作用。这个 本提案中描述的工作是对以前这些工作的直接扩展 研究并旨在解决三个重要问题。第一个目标 是确定CD2破坏E-钙粘素依赖的机制 LLC-PK1细胞系的细胞间连接。需要检验的假设 CD2可以竞争性地取代E-上结合位点上的钙 钙粘附素，从而改变分子的粘附性。这个 第二个目标是确定CD2是否可以选择性地干扰 血管内皮细胞中钙依赖的细胞-细胞连接。这 是一个重要的问题，因为血管内皮细胞是 体内CD2毒性的主要靶点。第三个主要目标是 确定CD2是否可以选择性地损伤钙粘附素依赖的细胞 体内的连接，以及这种机制是否可能有助于公开 CD2的毒性作用。这些问题将通过使用 多学科方法，包括形态、生物物理和 生化技术。这些研究的结果应该提供重要的 对CD2产生某些毒素的机制的新见解 这将会产生重大影响，并应为今后在这一领域的研究奠定基础。 此外，这些研究的结果可能会有更普遍的 关于有毒物质损害机制的影响 活细胞。

Cadmium (Cd2+) is an important industrial and environmental pollutant that has been shown to cause severe damage to a variety of organs, and to have mutagenic, teratogenic and carcinogenic activities. In spite of its importance as an environmental health problem, relatively little is known about the specific cellular and molecular mechanisms by which Cd2+ produces its many effects. The long-term objective of this project is to identify some of these mechanisms. Reports in the literature suggest that some of the effects of Cd2+ in vivo may result from the disruption of the junctions between cells in various epithelial or endothelial surfaces. To examine this possibility in more detail, studies were undertaken to examine the effects of Cd2+ on cell-cell junctions in the established porcine renal epithelial cell line, LLC-PK1. Results of these studies have shown that Cd2+ has specific damaging effects on the adhering and occluding junctions between LLC-PK1 cells and that these effects may involve the interaction of Cd2+ with E-cadherin, a Ca2+-dependent glycoprotein that plays a key role in epithelial cell-cell adhesion. The work described in this proposal is a direct extension of these previous studies and is aimed at resolving three important issues. The first goal is to identify the mechanisms by which Cd2+ disrupts E-cadherin dependent cell-cell junctions in the LLC-PK1 cell line. The hypothesis to be tested is that Cd2+ can competitively displace Ca2+ from binding sites on E- cadherin and thereby alter the adhesive properties of the molecule. The second goal is to determine whether or not Cd2+ can selectively disrupt calcium-dependent cell-cell junctions in vascular endothelial cells. This is an important issue because the vascular endothelium is one of the primary targets for Cd2+ toxicity in vivo. The third major goal is to determine whether Cd2+ can selectively damage cadherin-dependent cell-cell junctions in vivo, and whether such a mechanism may contribute to overt toxic effects of Cd2+. These issues will be addressed by using a multidisciplinary approach that includes morphologic, biophysical and biochemical techniques. Results of these studies should provide important new insights into the mechanisms by which Cd2+ produces some of its toxic effects and should lay the groundwork for future studies in this area. Furthermore, the results of these studies could have more general implications concerning the mechanisms by which toxic substances damage living cells.