Desmosomal Control of Cytoskeletal Organization

描述（由申请人提供）：桥粒是基本的细胞-细胞粘附结构，提供组织的机械完整性。桥粒的破坏导致人类一系列疾病，包括皮肤脆弱和起泡疾病以及心肌病。课本上对桥粒的看法是，它们是相当被动的结构，只是与中间丝细胞骨架结合。我们现在开始认识到桥粒比以前认为的更具活力和功能。例如，我们已经证明桥粒控制表皮和培养的角化细胞中的微管组织。在本应用中，我们关注桥粒如何控制细胞骨架网络的组织。我们的主要假设是，桥粒通过招募通常在中心体上发现的蛋白质复合物，积极地组织中间丝和微管。该复合体中的一些新型桥粒蛋白，包括Lis1和NDEL1，已知控制其他组织中的微管和中间丝组织。通过了解这些蛋白质如何被募集到桥粒及其在桥粒中的功能作用，我们将大大扩展我们对桥粒如何控制细胞骨架的认识。这将使我们能够特异性地破坏分化表皮中的微管组织，并确定这些细胞中皮质微管的生理功能。为了实现这一点，我们将生成并表征中心体蛋白不被募集到桥粒的小鼠模型。这将直接测试这种新型桥粒体功能的生理作用。其次，我们将确定表皮中Lis1的缺失如何导致表皮完整性、桥粒结构和微管组织的缺陷。第三，我们将确定新型角蛋白结合蛋白NDEL1在控制桥粒下游角蛋白丝组织中的作用。这项工作将导致对桥粒如何重组潜在细胞骨架的机制理解，并更好地理解为什么桥粒破坏会导致如此多样化的病理表型。

DESCRIPTION (provided by applicant): Desmosomes are essential cell-cell adhesion structures that provide mechanical integrity to tissues. Disruption of desmosomes leads to a range of diseases in man including skin fragility and blistering disorders as well as cardiomyopathies. The textbook view of desmosomes is that they are rather passive structures that simply bind to the intermediate filament cytoskeleton. We are now beginning to appreciate that desmosomes are both more dynamic and have more functions than previously thought. For example, we have shown that desmosomes control microtubule organization in the epidermis and cultured keratinocytes. In this application, we focus on how desmosomes control the organization of cytoskeletal networks. Our central hypothesis is that the desmosome actively organizes both intermediate filaments and microtubules through recruitment of a protein complex that is usually found at the centrosome. Some of the novel desmosomal proteins in this complex, including Lis1 and NDEL1, are known to control microtubule and intermediate filament organization in other tissues. By understanding both how these proteins are recruited to desmosomes and their functional role there, we will greatly expand our knowledge of how desmosomes control the cytoskeleton. This will allow us to specifically disrupt microtubule organization in differentiated epidermis, and to determine the physiological function of cortical microtubules in these cells. To accomplish this, we will generate and characterize mouse models in which centrosomal proteins are not recruited to desmosomes. This will directly test the physiological role of this novel desmosomal function. Second, we will determine how loss of Lis1 in the epidermis leads to defects in epidermal integrity, desmosome architecture, and microtubule organization. Third, we will determine the role of the novel keratin-binding protein, NDEL1, in controlling keratin filament organization downstream of the desmosome. This work will lead to a mechanistic understanding of how desmosomes reorganize the underlying cytoskeleton and to a greater understanding of why desmosome disruption results in such a diversity of pathological phenotypes. PUBLIC HEALTH RELEVANCE: Desmosomes are cell-cell adhesion structures that provide mechanical integrity to cells by linking to the underlying cytoskeleton network. Disruption of desmosomes causes epidermal fragility, skin blistering, and cardiomyopathies. We will characterize novel mechanisms that desmosomes use to reorganize the cytoskeleton. This will allow an understanding of how desmosome disruption results in such a diversity of pathological phenotypes.