Defining interactions and distributions of cadherin and catenin complexes in polarized epithelial cells.
Defining interactions and distributions of cadherin and catenin complexes in polarized epithelial cells.
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DOI：
10.1083/jcb.125.6.1341
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发表时间：
1994-06
期刊：
影响因子：
--
通讯作者：
Nelson WJ
中科院分区：
文献类型：
--
作者：
Näthke IS;Hinck L;Swedlow JR;Papkoff J;Nelson WJ
cadherin/catenin复合物在细胞粘附、信号转导以及细胞和组织的结构和功能组织的启动和维持中起着重要作用。在之前的研究中，我们发现cadherin/catenin复合物的组装受到暂时调节，并且在Triton x -100可溶和不可溶组分中形成了catenin和cadherin复合物的新组合；我们提出了一个模型，其中连环蛋白在调节e -钙粘蛋白/连环蛋白和连环蛋白复合物的组装中很重要。在这里，我们试图确定E- cadherin、α -连环蛋白、β -连环蛋白和血小板红蛋白的空间分布，以及这些蛋白的不同复合物是否在极化的Madin-Darby犬肾细胞中以稳定的状态积累。通过宽视场、光学切片和双免疫荧光显微镜观察蛋白质分布，然后重建三维图像。在用Triton X-100提取并固定的细胞中（Triton X-100不溶性部分），相对于外侧膜的其他区域，e -钙粘蛋白在顶端连接处的浓度更高。-连环蛋白和-连环蛋白与E-钙粘蛋白在顶端连接复合体上共定位。这些蛋白质在侧膜上的分布有一些重叠，但也有分布不同的区域。血小板红蛋白被排除在顶结复合体之外，其在外侧膜上的分布与e -钙粘蛋白不同。细胞也被固定，然后渗透，以显示每个蛋白质的总细胞池（Triton x -100可溶和不溶部分）。该分析显示α -连环蛋白、β -连环蛋白和血小板红蛋白的侧膜定位，并显示它们分布在整个细胞中。蛋白质的化学交联和特异性抗体的分析证实，在稳定状态下存在含有-连环蛋白或血小板蛋白的E-cadherin/连环蛋白复合物，以及不含E-cadherin的连环蛋白复合物。含有e -钙粘蛋白/ β -连环蛋白和e -钙粘蛋白/ α -连环蛋白的复合物存在于Triton X-100可溶部分和-不溶部分，但在Triton X-100不溶部分未检测到e -钙粘蛋白/血小板红蛋白复合物。综上所述，这些结果表明，钙粘蛋白和连环蛋白的不同复合物在完全极化的上皮细胞中积累，并分布到不同的部位。我们认为cadherin/catenin和不同位点的catenin复合物在极化上皮细胞的结构和功能组织的建立和维持中具有特殊的作用。
The cadherin/catenin complex plays important roles in cell adhesion, signal transduction, as well as the initiation and maintenance of structural and functional organization of cells and tissues. In the preceding study, we showed that the assembly of the cadherin/catenin complex is temporally regulated, and that novel combinations of catenin and cadherin complexes are formed in both Triton X-100-soluble and - insoluble fractions; we proposed a model in which pools of catenins are important in regulating assembly of E-cadherin/catenin and catenin complexes. Here, we sought to determine the spatial distributions of E- cadherin, alpha-catenin, beta-catenin, and plakoglobin, and whether different complexes of these proteins accumulate at steady state in polarized Madin-Darby canine kidney cells. Protein distributions were visualized by wide field, optical sectioning, and double immunofluorescence microscopy, followed by reconstruction of three- dimensional images. In cells that were extracted with Triton X-100 and then fixed (Triton X-100-insoluble fraction), more E-cadherin was concentrated at the apical junction relative to other areas of the lateral membrane. alpha-Catenin and beta-catenin colocalize with E- cadherin at the apical junctional complex. There is some overlap in the distribution of these proteins in the lateral membrane, but there are also areas where the distributions are distinct. Plakoglobin is excluded from the apical junctional complex, and its distribution in the lateral membrane is different from that of E-cadherin. Cells were also fixed and then permeabilized to reveal the total cellular pool of each protein (Triton X-100-soluble and -insoluble fractions). This analysis showed lateral membrane localization of alpha-catenin, beta- catenin, and plakoglobin, and it also revealed that they are distributed throughout the cell. Chemical cross-linking of proteins and analysis with specific antibodies confirmed the presence at steady state of E-cadherin/catenin complexes containing either beta-catenin or plakoglobin, and catenin complexes devoid of E-cadherin. Complexes containing E-cadherin/beta-catenin and E-cadherin/alpha-catenin are present in both the Triton X-100-soluble and -insoluble fractions, but E-cadherin/plakoglobin complexes are not detected in the Triton X-100- insoluble fraction. Taken together, these results show that different complexes of cadherin and catenins accumulate in fully polarized epithelial cells, and that they distribute to different sites. We suggest that cadherin/catenin and catenin complexes at different sites have specialized roles in establishing and maintaining the structural and functional organization of polarized epithelial cells.