Molecular and structural analyses of hemidesmosomes

半粒酶（HD）是一种细胞与底物的粘附装置，存在于分层上皮和复杂上皮中。在本项目中，我们从生物化学和结构上研究了半粒酶体主要成分的分子性质，以表征半粒酶体粘附复合物。纯化的BP180的旋转阴影图像显示了一个典型的分子形状，包括三个结构域，一个球形头部，一个中心杆和一个灵活的尾巴。此外，我们证明了BP180分子的细胞外区域在细胞膜上被切割并从细胞表面释放出来。我们认为这种分裂具有生物学和临床意义。我们还证明，当BP自身抗体与BP180结合时，细胞结合免疫复合物，并提示BP180的结合导致BP180缺陷并引起水泡。在联合研究项目中，我们报道了bp180缺失患者由有丝分裂基因转换引起的反向嵌合现象，并通过胎儿皮肤活检和单克隆抗体进行了可靠的产前诊断。HD1是存在于HD斑块大部分细胞质侧的主要HD成分，似乎在连接粘附分子与角蛋白中间丝方面起重要作用。利用单克隆抗体、部分氨基酸测序、部分cDNA测序和表位定位，结合EBS-MD患者的结果，我们确定HD1为plectin，一种多功能交联蛋白。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.