Mechanisms of Desmosome Regulation and Disassembly in the Skin Disease Pemphigus

描述（由申请人提供）：天疱疮是一类破坏性表皮起泡疾病，其中产生针对皮肤和粘膜中存在的细胞-细胞粘附分子的自身抗体。天疱疮IgG靶向桥粒，一种将角蛋白中间丝网络与强细胞-细胞粘附区域偶联的结构。在寻常型天疱疮（PV）中，自身抗体的主要靶点是桥粒芯糖蛋白-3（Dsg 3），它是粘附分子桥粒钙粘蛋白亚家族的成员。本申请中概述的工作研究了寻常型天疱疮患者IgG破坏细胞-细胞粘附的机制。假设PV IgG通过引起Dsg 3从细胞表面内化来破坏桥粒，导致桥粒不稳定和角质形成细胞粘附的丧失。将使用一系列体外细胞培养模型来检验这一假设，这些模型采用细胞和分子方法来确定PV IgG引起Dsg 3内化和桥粒解体的机制。这些研究将揭示介导Dsg 3内吞作用的细胞机制和途径，以及桥粒的细胞质组分如何调节Dsg 3内化。此外，将采用一组抗体试剂，包括PV患者IgG、从患者克隆的人单克隆抗体和具有不同程度致病活性的小鼠单克隆Dsg 3抗体。这些试剂将用于揭示桥粒分解途径和抗体致病性谱之间的关系，以确定天疱疮IgG如何在细胞水平上引起疾病。相关性：这些研究旨在对调节细胞-细胞粘附的基本细胞机制产生新的见解，并揭示治疗天疱疮和其他以表皮脆性为特征的皮肤病的新治疗靶点。

DESCRIPTION (provided by applicant): Pemphigus is a class of devastating epidermal blistering diseases in which autoantibodies are generated against cell-cell adhesion molecules present in the skin and mucous membranes. Pemphigus IgG target desmosomes, a structure that couples the keratin intermediate filament network to regions of strong cell-cell adhesion. In pemphigus vulgaris (PV), the primary target of the autoantibodies is desmoglein-3 (Dsg3), a member of the desmosomal cadherin subfamily of adhesion molecules. The work outlined in this application investigates the mechanisms by which IgG from pemphigus vulgaris patients disrupts cell-cell adhesion. It is hypothesized that PV IgG disrupt desmosomes by causing Dsg3 internalization from the cell surface, leading to desmosome destabilization and loss of keratinocyte adhesion. This hypothesis will be tested using a series of in vitro cell culture models that employ cellular and molecular approaches to define the mechanisms by which PV IgG cause Dsg3 internalization and desmosome disassembly. These studies will reveal the cellular machinery and pathways that mediate Dsg3 endocytosis, and how cytoplasmic components of the desmosome regulate Dsg3 internalization. Furthermore, a panel of antibody reagents will be employed, including PV patient IgG, human monoclonal antibodies cloned from patients, and mouse monoclonal Dsg3 antibodies with varying degrees of pathogenic activity. These reagents will be used to reveal relationships between desmosome disassembly pathways and antibody pathogenicity profiles to determine how pemphigus IgG causes disease at the cellular level. RELEVANCE: These studies are designed to generate new insights into the basic cellular mechanisms that regulate cell-cell adhesion, and to expose new therapeutic targets for the treatment of pemphigus and other skin diseases characterized by epidermal fragility.