Jiang Jing, Dean Dana, Burghardt Robert C, Parrish Alan R
Department of Medical Pharmacology and Toxicology, College of Medicine, Texas A&M University System Health Science Center, College Station 77843-1114, USA.
Toxicol Sci. 2004 Jul;80(1):170-82. doi: 10.1093/toxsci/kfh143. Epub 2004 Apr 14.
The cadherin/catenin complex is an essential regulator of intercellular adhesion and is critical for the establishment of epithelial cell polarity. The purpose of this study was to (1) determine the spatial pattern of cadherin and catenin expression, colocalization, and interaction along the mouse nephron, and (2) investigate the expression, localization, and interaction of proximal tubular cadherins and catenins during mercuric chloride-induced nephrotoxicity. Using a combination of Western blot analysis, colocalization studies, and coimmunoprecipitation, we conclude that two distinct cadherin/catenin complexes exist in adult mouse kidney proximal tubules: N-cadherin/beta-catenin/alpha-catenin and E-cadherin/beta-catenin/alpha-catenin/p120-catenin. In the distal tubule, E-cadherin/beta-catenin/alpha-catenin and E-cadherin/gamma-catenin/alpha-catenin complexes are present. Male C3H mice were challenged with 0-25 micromol/kg mercuric chloride i.p. (6-48 h) to assess the impact of nephrotoxicity on cadherin/catenin complexes. Plasma creatinine and blood urea nitrogen were increased between 6 and 48 h, indicating the onset of renal failure. In addition, histological evaluation demonstrated alterations in the proximal tubules. At 24 h, we observed decreases in Ksp- and N-cadherin, but not in E-cadherin. Additionally, alpha-catenin expression was decreased, in the absence of changes in beta-, gamma-, and p120-catenin. The early stages (6 h) of mercuric chloride-induced nephrotoxicity were associated with disruption of complex integrity. N-cadherin and alpha-catenin localizations were disrupted at 6 h. These changes in cadherin and catenin localization corresponded with a decrease in the coimmunoprecipitation of alpha-catenin with both beta-catenin and N-cadherin. Interestingly, these changes occurred at the same time that aberrant staining of Na+/K(+)-ATPase staining was seen. Taken together, these data suggest that alterations in cadherin and catenin expression, localization, and interaction are associated with nephrotoxicity.
钙黏蛋白/连环蛋白复合体是细胞间黏附的重要调节因子，对上皮细胞极性的建立至关重要。本研究的目的是：（1）确定钙黏蛋白和连环蛋白在小鼠肾单位中的表达空间模式、共定位及相互作用；（2）研究氯化汞诱导的肾毒性过程中近端肾小管钙黏蛋白和连环蛋白的表达、定位及相互作用。通过蛋白质免疫印迹分析、共定位研究和免疫共沉淀相结合的方法，我们得出结论：成年小鼠肾近端小管中存在两种不同的钙黏蛋白/连环蛋白复合体：N-钙黏蛋白/β-连环蛋白/α-连环蛋白和E-钙黏蛋白/β-连环蛋白/α-连环蛋白/p120-连环蛋白。在远端小管中，存在E-钙黏蛋白/β-连环蛋白/α-连环蛋白和E-钙黏蛋白/γ-连环蛋白/α-连环蛋白复合体。雄性C3H小鼠腹腔注射0 - 25 μmol/kg氯化汞（6 - 48小时），以评估肾毒性对钙黏蛋白/连环蛋白复合体产生的影响。血浆肌酐和血尿素氮在6至48小时之间升高，表明肾衰竭开始。此外，组织学评估显示近端小管发生改变。在24小时时，我们观察到Ksp-钙黏蛋白和N-钙黏蛋白减少，但E-钙黏蛋白未减少。此外，α-连环蛋白表达减少，而β-、γ-和p120-连环蛋白无变化。氯化汞诱导的肾毒性早期（6小时）与复合体完整性破坏有关。6小时时，N-钙黏蛋白和α-连环蛋白的定位被破坏。钙黏蛋白和连环蛋白定位的这些变化与α-连环蛋白与β-连环蛋白和N-钙黏蛋白免疫共沉淀的减少相对应。有趣的是，这些变化与Na+/K(+)-ATP酶染色异常同时出现。综上所述，这些数据表明钙黏蛋白和连环蛋白的表达、定位及相互作用的改变与肾毒性有关。
