Regulation of desmosome assembly in MDCK epithelial cells: coordination of membrane core and cytoplasmic plaque domain assembly at the plasma membrane.
Regulation of desmosome assembly in MDCK epithelial cells: coordination of membrane core and cytoplasmic plaque domain assembly at the plasma membrane.
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MDCK上皮细胞中脱骨组装的调节：质膜上膜核和细胞质斑块结构域的配位。
DOI：
10.1083/jcb.113.3.645
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发表时间：
1991-05
影响因子：
7.8
通讯作者：
Nelson, W J
中科院分区：
文献类型：
--
作者：
Pasdar, M;Krzeminski, K A;Nelson, W J
桥粒是上皮细胞间连接复合体的主要成分。它们由至少八种不同的细胞质和膜蛋白组成，这些蛋白被组织成两个生物化学和结构不同的结构域：细胞质斑块和膜核心。我们先前表明，在MDCK上皮细胞中，细胞质斑块的主要组分（桥粒斑蛋白I和II; DPI/II）和膜核心结构域（桥粒芯蛋白I; DGI）最初进入可溶于含有Triton X-100的缓冲液的蛋白质池，然后在它们到达质膜之前滴定到不溶性池中（Pasdar，M.，和W.纳尔逊。1988. 106：677- 685; Pasdar. M.，和W.纳尔逊。1989. 109：163-177）。我们现在已经研究了这些蛋白质的可溶性或不溶性池是否代表在质膜组装成桥粒之前组装和结构域之间相互作用的细胞内位点。Triton X-100可溶性池DPI/II和DGI之间的相互作用进行了分析，通过在蔗糖梯度中沉淀提取的蛋白质。结果表明，这些蛋白质的沉降曲线有明显的差异，这表明它们不相关的Triton X-100可溶性蛋白质池，这也支持DGI和DPI/II不能从蔗糖梯度组分中相互共免疫沉淀在复合物中的观察。DPI/II和DGI，在细胞中，桥粒组装已同步的不溶性池的免疫荧光分析显示，这些蛋白质的空间分布的明显差异。此外，DPI/II和DGI被发现与细胞骨架的不同元素相关; DPI/II位于沿着细胞角蛋白中间丝，而DGI似乎与微管相关。在细胞内的组织和装配的细胞质斑块和膜的核心结构域，并将其整合到细胞质膜上的桥粒的细胞骨架元素的调节作用进行了讨论。
Desmosomes are major components of the intercellular junctional complex in epithelia. They consist of at least eight different cytoplasmic and integral membrane proteins that are organized into two biochemically and structurally distinct domains: the cytoplasmic plaque and membrane core. We showed previously that in MDCK epithelial cells major components of the cytoplasmic plaque (desmoplakin I and II; DPI/II) and membrane core domains (desmoglein I; DGI) initially enter a pool of proteins that is soluble in buffers containing Triton X-100, and then titrate into an insoluble pool before their arrival at the plasma membrane (Pasdar, M., and W. J. Nelson. 1988. J. Cell Biol. 106:677- 685; Pasdar. M., and W. J. Nelson. 1989. J. Cell Biol. 109:163-177). We have now examined whether either the soluble or insoluble pool of these proteins represents an intracellular site for assembly and interactions between the domains before their assembly into desmosomes at the plasma membrane. Interactions between the Triton X-100-soluble pools of DPI/II and DGI were analyzed by sedimentation of extracted proteins in sucrose gradients. Results show distinct differences in the sedimentation profiles of these proteins, suggesting that they are not associated in the Triton X-100-soluble pool of proteins; this was also supported by the observation that DGI and DPI/II could not be coimmunoprecipitated in a complex with each other from sucrose gradient fractions. Immunofluorescence analysis of the insoluble pools of DPI/II and DGI, in cells in which desmosome assembly had been synchronized, showed distinct differences in the spatial distributions of these proteins. Furthermore, DPI/II and DGI were found to be associated with different elements of cytoskeleton; DPI/II were located along cytokeratin intermediate filaments, whereas DGI appeared to be associated with microtubules. The regulatory role of cytoskeletal elements in the intracellular organization and assembly of the cytoplasmic plaque and membrane core domains, and their integration into desmosomes on the plasma membrane is discussed.