Desmoglein 2 Function in Cell Adhesion and Pemphigus

描述（由申请人提供）：表皮角质形成细胞结合在一起 被称为桥粒的细胞间连接所控制， 维持细胞-细胞粘附、组织完整性和器官功能。 桥粒芯糖蛋白（Dsg）是桥粒的跨膜粘附组分。 在表皮中，Dsg 2和Dsg 3在增殖基底层中表达， Dsgl在高分化细胞中表达，而Dsgl在高分化细胞中表达。那里 是桥粒芯糖蛋白介导细胞-细胞粘附的有力证据。在 人自身免疫性起泡性疾病天疱疮，针对Dsg 1的抗体 和Dsg 3诱导表皮和口腔粘膜中的水疱形成。在小鼠中， Dsg 3基因的切除导致类似于观察到的水疱形成 寻常型天疱疮。然而，Dsg 3的强制表达在浅表层中， 表达Dsg 1的表皮防止天疱疮形成水疱 抗Dsg 1抗体。这些数据表明，Dsg 1和Dsg 3发挥作用， 在上皮细胞粘附中起关键作用， 补偿他人的损失。Dsg 2在表皮中的作用仍然存在， 部分原因在于其表达能力弱。该项目的总体目标是 阐明Dsg 2在皮肤细胞粘附中的功能。以下 提出了具体的目标：1）证明致病性天疱疮抗体 识别Dsg上的独特表位2）破坏正常表达 以及3）确定Dsg 2是否可以补偿表皮中的Dsg 2， Dsg 1和Dsg 3的缺失。为了实现这些特定的目标，GST融合蛋白 Dsg 2胞外结构域的A，将用于表征天疱疮 血清免疫印迹分析。此外，亲和纯化的Dsg 2特异性 天疱疮抗体将被测试，以确定特异性， Dsg 1和Dsg 3。Dsg 2吸附的天疱疮抗体将通过被动免疫法进行检测。 在新生小鼠中的致病性的转移测定。Dsg 2在肿瘤细胞中的作用 表皮将使用表达Dsg 2的转基因小鼠进行研究， 表皮在外皮蛋白启动子的控制下，其具有 在细胞分化过程中的活性。这样的老鼠将提供有价值的 深入了解Dsg 2在发展中的生物功能， 功能性表皮的细胞增殖，分化， 粘附和阻挡功能。最后，被动转移研究将 用天疱疮IgG进行，以确定Dsg 2是否可以保护免受抗Dsg 1 - 和/或抗-Dsg 3-诱导的细胞棘层松解。为此， 我们的目标是找到一种方法来上调表皮中的Dsg 2， 接近天疱疮。

DESCRIPTION (provided by applicant): Epidermal keratinocytes are held together by intercellular junctions called desmosomes, which are critical for the maintenance of cell-cell adhesion, tissue integrity, and organ function. Desmogleins (Dsg) are the transmembrane adhesive components of the desmosomes. In the epidermis, Dsg2 and Dsg3 are expressed in the proliferative basal keratinocytes while Dsgl is expressed in the upper differentiated cells. There is compelling evidence that desmogleins mediate cell-cell adhesion. In the human autoimmune blistering disease pemphigus, antibodies directed against Dsg1 and Dsg3 induce blister formation in the epidermis and oral mucosa. In mouse, ablation of the Dsg3 gene results in blister formation similar to that observed in pemphigus vulgaris. However, forced expression of Dsg3 in superficial epidermis where Dsg1 is expressed prevents blister formation by pemphigus foliaceus anti-Dsg1 antibodies. These data demonstrate that Dsg1 and Dsg3 play a pivotal role in epithelial cell adhesion and that one desmoglein can compensate the loss of another. The role of Dsg2 in the epidermis remains elusive in part due to its weak expression. The overall goal of this project is to elucidate the function of Dsg2 in cell adhesion in the skin. The following specific aims are proposed: 1) demonstration of pathogenic pemphigus antibodies that recognize unique epitopes on Dsg2, 2) disruption of the normal expression of Dsg2 in the epidermis, and 3) determining whether Dsg2 can compensate for the loss of Dsg1 and Dsg3. To achieve these specific aims, GST-fusion proteins of the extracellular domains of Dsg2,A,ill be used to characterize pemphigus sera by immunoblotting analysis. In addition, affinity purified Dsg2-specific pemphigus antibodies will be tested to determine specificity in relation to Dsg1 and Dsg3. Dsg2-adsorbed pemphigus antibodies will be tested by passive transfer assays for pathogenicity in neonatal mice. The function of Dsg2 in the epidermis will be studied using transgenic mice expressing Dsg2 in the superficial epidermis under control of the involucrin promoter, which has activity in cells undergoing differentiation. Such mice would provide valuable insights into the biological function of Dsg2 in the development of a functional epidermis with respect to cellular proliferation, differentiation, adhesion and bar-her functions. Finally passive transfer studies will be performed with pemphigus IgG to determine if Dsg2 can protect against anti-Dsg1 -and/or anti -Dsg3 -induced cellular acantholysis. To this end, the ultimate goal is to find a means to upregulate Dsg2 in the epidermis as a therapeutic approach to pemphigus.