Futei Y, Amagai M, Sekiguchi M, Nishifuji K, Fujii Y, Nishikawa T
Department of Dermatology, Keio University School of Medicine, Shinjuku-ku, Tokyo, Japan.
J Invest Dermatol. 2000 Nov;115(5):829-34. doi: 10.1046/j.1523-1747.2000.00137.x.
Pemphigus vulgaris is an autoimmune blistering disease caused by autoantibodies against desmoglein 3, a member of the desmosomal cadherin family. These autoantibodies recognize conformation-dependent epitopes on desmoglein 3. In this study we attempted to map the conformational epitopes of desmoglein 3 in pemphigus vulgaris using recombinant desmoglein 3 produced by the baculovirus expression system. We developed a series of domain-swapped molecules between desmoglein 3 and desmoglein 1, which have similar structures but distinct epitopes. These were developed by substituting deleted segmental regions of desmoglein 3 by the corresponding desmoglein 1. Thus domain-swapped molecules containing desmoglein 3 residues 1-403, 1-161, 163-566, and 405-566 were constructed and used as competitors for competition enzyme-linked immunosorbent assay against the entire extracellular domain of desmoglein 3 with 25 pemphigus vulgaris sera. Considering more than 50% absorption as significant, residues 1-403 and 1-161 showed significant absorption in 24 out of 25 (96%) and 18 out of 25 (72%) pemphigus vulgaris sera, respectively, whereas only one serum and no sera showed significant absorption by residues 163-566 and 405-566, respectively. Furthermore, no apparent change in their major epitopes was seen during the time course in four pemphigus vulgaris cases tested. These findings indicate that the domain-swapping approach is useful for conformational epitope mapping in pemphigus and that amino-terminal residues 1-161, which are considered to include a region essential for cell-cell adhesion in cadherins, contain the critical residues of the conformational epitope of desmoglein 3 recognized by the autoantibodies in pemphigus vulgaris sera.
寻常型天疱疮是一种自身免疫性水疱病，由针对桥粒芯糖蛋白3（一种桥粒钙黏蛋白家族成员）的自身抗体引起。这些自身抗体识别桥粒芯糖蛋白3上依赖构象的表位。在本研究中，我们试图利用杆状病毒表达系统产生的重组桥粒芯糖蛋白3来绘制寻常型天疱疮中桥粒芯糖蛋白3的构象表位图谱。我们构建了一系列桥粒芯糖蛋白3和桥粒芯糖蛋白1之间的结构域交换分子，它们具有相似的结构但表位不同。这些分子是通过用相应的桥粒芯糖蛋白1替换桥粒芯糖蛋白3缺失的片段区域而构建的。因此，构建了包含桥粒芯糖蛋白3第1 - 403、1 - 161、163 - 566和405 - 566位残基的结构域交换分子，并将其用作竞争酶联免疫吸附测定的竞争者，以检测25份寻常型天疱疮血清与桥粒芯糖蛋白3的整个细胞外结构域的反应。若吸收超过50%被视为显著吸收，则第1 - 403位和第1 - 161位残基分别在25份寻常型天疱疮血清中的24份（96%）和18份（72%）中显示出显著吸收，而第163 - 566位和第405 - 566位残基分别仅在1份血清和无血清中显示出显著吸收。此外，在检测的4例寻常型天疱疮病例的病程中，其主要表位未见明显变化。这些发现表明，结构域交换方法对于寻常型天疱疮中构象表位的绘制是有用的，并且被认为包含钙黏蛋白中细胞间黏附所必需区域的氨基末端残基1 - 161，包含了寻常型天疱疮血清中自身抗体识别的桥粒芯糖蛋白3构象表位的关键残基。
