Direct Ca2+-dependent heterophilic interaction between desmosomal cadherins, desmoglein and desmocollin, contributes to cell-cell adhesion.
Direct Ca2+-dependent heterophilic interaction between desmosomal cadherins, desmoglein and desmocollin, contributes to cell-cell adhesion.
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DOI：
10.1083/jcb.138.1.193
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发表时间：
1997-07-14
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影响因子：
--
通讯作者：
Troyanovsky SM
中科院分区：
文献类型：
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作者：
Chitaev NA;Troyanovsky SM
人纤维肉瘤细胞HT-1080以广泛的粘附连接为特征，缺乏成熟的桥粒，并表达单一的已知桥粒蛋白桥粒芯糖蛋白2（Dsg 2）。用牛桥粒胶原1a（Dsc 1a）转染这些细胞引起内源性Dsg 2的亚细胞分布的显著变化。这两种钙粘蛋白聚集在粘附连接的区域，而只有一小部分的Dsg 2被认为是在这些地区的亲本细胞。缺失图谱显示Dsc 1a（Arg 1-Thr 170）的完整细胞外钙粘蛋白样重复序列是Dsg 2易位所必需的。删除介导Dsc 1a与斑珠蛋白相互作用的细胞内C结构域，或参与与桥粒斑蛋白结合的CSI区域，没有影响。免疫共沉淀实验的细胞裂解物稳定表达Dsc 1a与抗Dsc或Dsg抗体表明，桥粒钙粘蛋白，Dsg 2和Dsc 1a，参与了直接的钙依赖性相互作用。固相结合实验的结果进一步支持了这一结论。这些表明，含有钙粘蛋白样重复1和2的Dsc 1a片段直接结合到Dsg的细胞外部分的钙离子依赖性的方式。通过将表达Dsc 1a的HT-1080细胞与缺乏Dsc但表达myc标记的斑珠蛋白（MPg）的HT-1080细胞共培养来测试Dsg/ Dsc相互作用对细胞-细胞粘附的贡献。在后者的细胞中，MPg和内源性Dsg形成稳定的复合物。所观察到的特异性免疫共沉淀MPG抗DSC抗体在共培养表明，DSC 1和DSG之间的细胞间相互作用参与细胞-细胞粘附。
Human fibrosarcoma cells, HT-1080, feature extensive adherens junctions, lack mature desmosomes, and express a single known desmosomal protein, Desmoglein 2 (Dsg2). Transfection of these cells with bovine Desmocollin 1a (Dsc1a) caused dramatic changes in the subcellular distribution of endogenous Dsg2. Both cadherins clustered in the areas of the adherens junctions, whereas only a minor portion of Dsg2 was seen in these areas in the parental cells. Deletion mapping showed that intact extracellular cadherin-like repeats of Dsc1a (Arg1-Thr170) are required for the translocation of Dsg2. Deletion of the intracellular C-domain that mediates the interaction of Dsc1a with plakoglobin, or the CSI region that is involved in the binding to desmoplakin, had no effect. Coimmunoprecipitation experiments of cell lysates stably expressing Dsc1a with anti-Dsc or -Dsg antibodies demonstrate that the desmosomal cadherins, Dsg2 and Dsc1a, are involved in a direct Ca2+-dependent interaction. This conclusion was further supported by the results of solid phase binding experiments. These showed that the Dsc1a fragment containing cadherin-like repeats 1 and 2 binds directly to the extracellular portion of Dsg in a Ca2+-dependent manner. The contribution of the Dsg/ Dsc interaction to cell–cell adhesion was tested by coculturing HT-1080 cells expressing Dsc1a with HT-1080 cells lacking Dsc but expressing myc-tagged plakoglobin (MPg). In the latter cells, MPg and the endogenous Dsg form stable complexes. The observed specific coimmunoprecipitation of MPg by anti-Dsc antibodies in coculture indicates that an intercellular interaction between Dsc1 and Dsg is involved in cell–cell adhesion.