Molecular and structural analyses of hemidesmosomes

半桥粒(HD)是一种细胞与基质的黏附装置，存在于复层和复杂的上皮细胞中。在这个项目中，我们从生化和结构上研究了半桥粒主要成分的分子性质，以表征半桥粒黏附复合体。纯化的BP180的旋转阴影图像显示出由三个结构域组成的特征分子形状，即球形头部、中心杆状和柔性尾部。进一步，我们证明了BP180分子的胞外区在细胞膜上被切割，并在组织和培养中从细胞表面释放出来。我们还证明了当BP自身抗体与BP180结合时，细胞结合了免疫复合体，并提示BP180的这种结合导致了BP180的缺陷并导致水泡。在联合研究项目中，我们报道了由有丝分裂基因转换引起的BP180缺失患者的突变嵌合体，并利用胎儿皮肤活检和单抗进行了可靠的产前诊断。HD1是HD斑块最胞质一侧的主要HD组分，在连接黏附分子和角蛋白中间丝方面起着重要作用。结合EBS-MD患者的研究结果，结合单抗、部分氨基酸序列测定、部分基因序列测定和表位定位，我们将HD1鉴定为plectin，一种多功能的交联蛋白。在联合研究项目中，我们报道了hd1的极化表达以及hd1/plectin与整合素β4的相互作用。

The hemidesmosome (HD) is a cell-to-substrate adhesion apparatus found in stratified and complex epithelia. In this project, we have investigated molecular nature of major constituents of hemidesmosomes biochemically and structurally to characterize hemidesmosomal adhesion complex.1. The rotary-shadowed images of purified BP180 showed a characteristic molecular shape consisting of three domains, a globular head, a central rod, and a flexible tail. Further, we demonstrated that the extracellular region of BP180 molecule was cleaved on the cell membrane and released from cell surface both in tissue and in culture. We suggested biological and clinical significance of this splitting.We also demonstrated that when BP autoantibodies bound to BP180, the cells incorporated the immune complex, and suggested that this incorporation of BP180 results in defect of BP180 and causes blistering. In joint research projects, we reported revertant mosaicism in BP180-null patient caused by mitotic gene conversion and reliable prenatal diagnosis using fetal skin biopsy and monoclonal antibodies.2. HD1 is a major HD constituent present in the most cytoplasmic side of HD plaques, and seems to play an important role in connecting adhesion molecules with keratin intermediate filaments. Using monoclonal antibodies, partial amino acid sequencing, partial cDNA sequencing and epitope mapping, together with the results from patients with EBS-MD, we identified HD1 as plectin, a versatile cross-linking protein. In joint research projects, we reported polarized expression of HD1 and interaction of HD1/plectin with integrin β4.