DESMOSOMAL PROTEINS AND THE CELL

桥粒芯糖蛋白和桥粒芯淋蛋白是本发明的主要粘合剂组分。 桥粒和形式的钙粘蛋白超家族的两个不同的亚型， 细胞-细胞粘附和形态调节蛋白。粘接性能 这些和其他钙粘蛋白型蛋白的细胞骨架连接， 通过与几种细胞质蛋白的结合来调节。 斑珠蛋白与桥粒芯糖蛋白和桥粒芯淋蛋白物理结合 在桥粒以及经典的钙粘蛋白集中在 粘附连接。作为唯一与所有三个组件交互的组件， 斑珠蛋白是上皮细胞的主要细胞-细胞粘附蛋白， 独特的定位，在协调粘合剂中发挥关键作用， 细胞的属性。斑珠蛋白也是结构和功能性的 果蝇中一种参与细胞命运决定蛋白质同源物 并且已经显示参与PC 12细胞的Wnt-1转化。 此外，斑珠蛋白最近已被证明形成胞质 与另一种结构上相关的蛋白质APC形成复合物，APC是 一种与遗传性结肠癌有关的基因该系列 因此，蛋白质可以被认为是细胞-细胞粘附中的中心角色 和肿瘤抑制。鉴于斑珠蛋白参与了 以上概述的重要细胞过程，我建议进一步 研究这种蛋白质及其受体的作用。我的具体目标 为： 1.为了检测细胞粘附和增殖的影响， 过表达天然和突变形式的斑珠蛋白。这些突变体 设计为使钙粘蛋白或APC上的特异性结合位点饱和， 以有效或否定这些蛋白质与 细胞骨架 2.确定桥粒芯糖蛋白/斑珠蛋白的其他相互作用 复合物：a）纯化并克隆斑珠蛋白的70 kDa胞质配偶体 B）鉴定结合至细胞质结构域的新配偶体， 桥粒芯糖蛋白表达为融合蛋白，通过用 相同的融合蛋白，并采用酵母双杂交系统。 3)研究桥粒钙粘蛋白受体及其功能 通过使用碱性磷酸酶干扰桥粒形成 桥粒芯糖蛋白的标记的可溶性胞外域。

Desmogleins and desmocollins are the major adhesive components of desmosomes and form two distinct subtypes of the cadherin superfamily of cell-cell adhesion and morphoregulatory proteins. The adhesive properties and cytoskeletal connections of these and other cadherin-type proteins are modulated by their association with several cytoplasmic proteins. Plakoglobin physically associates with both desmogleins and desmocollins at the desmosome as well as with classical cadherins which concentrate in the adherens junction. As the only component to interact with all three of the major cell-cell adhesive proteins of epithelia, plakoglobin is uniquely positioned to play a key role in co-ordinating the adhesive properties of the cell. Plakoglobin is also the structural and functional homologue of a protein involved in cell fate determination in Drosophila and has been shown to participate in Wnt-l transformation of PC12 cells. Furthermore plakoglobin has recently been shown to form cytosolic complexes with another structurally related protein, APC, the product of a gene linked to an inherited form of colon cancer. This family of proteins may therefore be considered central players in cell-cell adhesion and tumor suppression. Given the involvement of plakoglobin in the important cellular processes outlined above I propose to further investigate the role of this protein and its receptors. My specific aims are: 1. To examine the effect on cell adhesion and proliferation of overexpressing native and mutant forms of plakoglobin. These mutants are designed to saturate specifically binding sites on cadherins , or, APC and to potentate or negate the interactions of these proteins with the cytoskeleton. 2. To identify the additional interactions of desmoglein/plakoglobin complexes: a) purify and clone a 70 kDa cytoplasmic partner of plakoglobin b) identify the novel partners binding to the cytoplasmic domain of desmoglein expressed as a fusion protein by screening libraries with the same fusion protein and employing the yeast two-hybrid system. 3) To characterize desmosomal cadherin receptors and functionally interfere with desmosome formation by use of an alkaline phosphatase tagged soluble ectodomain of desmoglein.