Desmoplakin Assembly and Function in Epidermis

描述（由申请人提供）：通过将中间丝（IF）细胞骨架拴系到质膜上，桥粒斑块组分桥粒斑块蛋白（DP）增强了由跨膜桥粒钙粘蛋白介导的粘附。DP或其相关的犰狳蛋白的突变导致皮肤和心脏的潜在致命疾病。由桥粒功能障碍引起的机械组织完整性的丧失通常被认为是疾病发病机制的基础。然而，除了它们的机械功能，桥粒分子提供信号线索，以调节IF连接，驱动连接组装，并指导表皮形态发生。桥粒调控信号通路以控制组织稳态和疾病发病机制的机制知之甚少。我们建议，DP的N-末端和相关的犰狳蛋白的plakophilin（PKP）家族作为支架，利用信号介质的活动时，他们需要的连接组装和表皮分化。我们的目标是确定DP/PKP缺陷和影响DP-PKP相互作用的突变如何通过以下方式干扰结构和信号传导功能来促进疾病发病机制：1）确定DP和PKP在桥粒组装和细胞-细胞粘附中的独立和协同作用以及干扰DP-PKP相互作用的人类疾病突变对这些过程的影响，2）测试DP和PKPs是否形成PKC和小G蛋白（RhoA）信号传导介质的支架以整合控制桥粒功能和细胞骨架重塑的效应子途径，和3）阐明DP如何与PKPs结合工作以促进表皮形态发生和稳态。我们将使用shRNA依赖性敲除方法，结合对DP和PKP缺陷的小鼠模型和人类患者的组织和细胞的分析，使用2D浸没、3D体外和体内移植培养物来建立DP、PKPs和相关信号通路在分化中的各自作用。桥粒相关的信号传导介体有望作为小分子疗法的设计靶点，以改善由突变或自身免疫抗体引起的疾病，所述突变或自身免疫抗体与这些结构蛋白相关的下游途径协同作用。 公共卫生相关性：本项目旨在了解皮肤细胞表面的粘性结构如何促进细胞片的形成，以提供覆盖身体表面的基本皮肤屏障。这些研究有望揭示这些分子的新功能，超越它们在细胞凝聚中的作用，控制正常组织发育和疾病过程。预计这些新途径将为患有遗传性、自身免疫性和感染性皮肤病的人提供新的治疗靶点。

DESCRIPTION (provided by applicant): By tethering the intermediate filament (IF) cytoskeleton to the plasma membrane, the desmosome plaque component desmoplakin (DP) strengthens adhesion mediated by the transmembrane desmosomal cadherins. Mutations in DP or its associated armadillo proteins result in potentially lethal disorders of the skin and heart. The loss of mechanical tissue integrity caused by desmosome dysfunction is commonly thought to underlie disease pathogenesis. However, in addition to their mechanical functions, desmosomal molecules provide signaling cues to regulate IF attachment, drive junction assembly, and guide epidermal morphogenesis. The mechanisms by which desmosomes govern signaling pathways to control tissue homeostasis and disease pathogenesis are poorly understood. We propose that the DP N-terminus and associated armadillo proteins in the plakophilin (PKP) family act as scaffolds to harness the activities of signaling mediators when and where they are needed for junction assembly and epidermal differentiation. Our goal is to determine how DP/PKP deficiency and mutations affecting DP-PKP interactions contribute to disease pathogenesis by interfering with structural and signaling functions by: 1) Determining the independent and cooperative roles of DP and PKPs in desmosome assembly and cell- cell adhesion and the effect of human disease mutations that interfere with DP-PKP interactions on these processes, 2) Testing whether DP and PKPs form scaffolds for PKC and small GTPase (RhoA) signaling mediators to integrate effector pathways that control desmosome function and cytoskeletal remodeling, and 3) Elucidating how DP works in conjunction with PKPs to promote epidermal morphogenesis and homeostasis. We will use an shRNA-dependent knock down approach combined with analysis of tissues and cells from mouse models and human patients with DP and PKP deficiencies to establish the respective roles of DP, PKPs and related signaling pathways in differentiation using 2D submerged, 3D in vitro and in vivo transplanted cultures. Desmosome-associated signaling mediators hold promise as targets for the design of small molecule therapies to ameliorate diseases caused by mutations or autoimmune antibodies that co-opt downstream pathways associated with these structural proteins. PUBLIC HEALTH RELEVANCE: This project aims to understand how sticky structures on the surface of skin cells facilitate the formation of cell sheets to provide an essential skin barrier covering the surface of the body. The studies promise to reveal new functions for these molecules, beyond their role in cell coherence, that control normal tissue development and disease processes. These new pathways are predicted to provide novel therapeutic targets for people with inherited, autoimmune and infectious diseases of the skin.