Mechanisms directing adherens junctions and actin network interactions

计划摘要 细胞迁移和细胞间黏附之间的平衡在发育过程中是至关重要的， 在疾病状态下改变的，如转移性癌症。细胞在发育过程中迁移到特定的 当它们与其他细胞接触时，它们就会静止不动并分化成组织。因此， 强大的细胞间粘附力是维持组织完整性所必需的。细胞间黏附的变化 在细胞周转或伤口愈合期间重新启动细胞迁移，或允许转移细胞分散到 远处的器官。 细胞-细胞黏附复合体(黏附连接)的形成和稳定对 后生动物的发育、器官发生和组织动态平衡，对某些动物也是必要的 病理生理条件，如伤口愈合。相反，粘附性连接的丧失是一种 癌症的标志，导致不受限制的细胞增殖和转移。细胞-细胞黏附 连接需要在质细胞膜上适当地组装多蛋白复合体。这里, 单次跨膜通道钙结合胞外区的同型相互作用 钙粘附素受体允许相邻细胞相互结合。他们之间的相互作用 带有β-连环蛋白的细胞质尾部结构域，进而与α-连环蛋白结合，似乎指导了 通过抑制片基的产生而形成粘连连接。然而，如果没有 张力，这种三元钙粘蛋白/β-连环蛋白/α-连环蛋白复合体不直接与肌动蛋白网络结合， 这是稳定这些连接和组织动态平衡所必需的。 在GM094483资助的前三年中，我们测定了二聚体全长的晶体结构 人α-连环蛋白和纽蛋白结合的α-连环蛋白，以及这些结构和我们的生化和 生物学研究明确了纽蛋白-α-连环蛋白相互作用在形成和 粘结剂结点的稳定。通过从晶体结构和3D重建转移到 生物化学，然后到生物学，拟议的研究将定义粘连连接是如何 稳定和控制肌动蛋白细胞骨架的组织。总的来说，我们建议的研究将 显著增加我们对α-连环蛋白单体-二聚体转变及其对 膜动力学、迁移和细胞黏附。重要的是，我们的多学科研究也将 为了解这些控制如何在肿瘤进展过程中丢失奠定基础，并可能 为治疗干预提供新的途径。

Program summary The balance between cell migration and cell–cell adhesion is crucial during development and is altered in disease states such as metastatic cancers. Cells migrate during development to specific sites when upon contact with other cells; they become stationary and differentiate into tissues. Thus, strong cell–cell adhesion is necessary in maintaining tissue integrity. Changes in cell–cell adhesion reinitiate cell migration during cell turnover or wound healing or allow metastatic cells to scatter to distant organs. The formation and stabilization of cell-cell adhesion complexes (adherens junctions) is essential for metazoan development, organogenesis, and tissue homeostasis, and it also necessary for some pathophysiological conditions, such as wound healing. In contrast, loss of adherens junctions is a hallmark of cancer, leading to unrestricted cell proliferation and metastasis. Cell-cell adherens junctions require the proper assembly of multi-protein complexes at the plasma cell membrane. Here, homotypic interactions between the calcium-binding ectodomains of single transmembrane pass cadherin receptors allow neighboring cells to bind to one another. The interactions of their cytoplasmic tail domains with β-catenin, which in turn binds to α-catenin, appear to direct the formation of adherens junctions, by inhibiting the production of lamellopodia. However, without tension, this ternary cadherin/β-catenin/α-catenin complex does not bind directly to the actin network, which is necessary for stabilizing these junctions and for tissue homeostasis. In the first 3 years of funding by GM094483, we determined the crystal structure of dimeric full-length human α-catenin and of vinculin-bound α-catenin, and these structures and our biochemical and biological studies defined the roles of the vinculin-α-catenin interaction in the formation and stabilization of adherens junctions. By moving from crystal structures and 3D reconstructions to biochemistry and then to biology, the proposed studies will define how adherens junctions are stabilized and control the organization of the actin cytoskeleton. Collectively, our proposed studies will significantly increase our understanding of α-catenin monomer-dimer transitions and their effects on membrane dynamics, migration, and cell adhesion. Importantly, our multi-disciplinary studies will also lay the foundation for understanding how these controls are lost during tumor progression and may suggest new avenues for therapeutic intervention.