Intercellular adhesion and morphogenesis: role of actin-regulatory proteins

描述（由申请方提供）：细胞形状变化和细胞间粘附的协调调节对于发育期间的形态发生、细胞迁移、存活和生长至关重要。这些过程的解偶联导致发育缺陷，导致毁灭性的病理条件，包括心血管异常。本研究的目的是确定机制所采用的Abi蛋白复合物和相关的Abl激酶调节肌动蛋白的动态下游的粘附和生长因子受体在发育形态发生。我们发现，Abl激酶在细胞表面受体下游肌动蛋白结构的形成和周转中发挥作用。这些过程是由局部肌动蛋白聚合驱动的，我们已经证明这涉及到阿比特龙蛋白的活性。我们已经证明，阿比特龙/Nap 1复合物是细胞间接触的形成和稳定所必需的，阿比特龙存在于不同的蛋白质复合物中：一种是由两种Abi结合蛋白，Abi和Wave，以及Nap 1，Sra 1和Arp 2/3组成的，第二种复合物由不同的新型Abi结合蛋白组成，这是细胞间粘附所必需的。值得注意的是，缺乏Abl家族激酶、Wave 2、Abi 1和Nap 1的小鼠表现出与改变的细胞骨架动力学和缺陷的细胞间粘附一致的显著发育缺陷，导致心血管异常。关于细胞间粘附与肌动蛋白聚合的信号通路存在根本性的知识空白。本研究的具体目的是：1）利用体外模型和基因敲除小鼠阐明Abi复合物调控粘附受体下游形态发生的机制，重点是我们最近发现的Abi/Nap 1依赖和Arp 2/3非依赖途径，这是细胞-细胞连接完整性的关键;和2）确定Abl激酶调节内皮细胞中的细胞增殖、存活和粘附的机制，重点是粘附受体的运输。重要性：从拟议的研究结果将提供新的见解的机制，从而组件的肌动蛋白聚合机制调节粘附过程的内皮细胞的生长和存活的关键。此外，我们的研究结果将提供急需的知识，阐明发育异常的分子基础，如先天性心血管疾病和其他病理引起的失调肌动蛋白动力学。

DESCRIPTION (provided by applicant): Coordinate regulation of cell shape changes and intercellular adhesion is critical for morphogenesis, cell migration, survival and growth during development. Uncoupling of these processes results in developmental defects that lead to devastating pathological conditions, including cardiovascular abnormalities. The goal of this research is to define the mechanisms employed by Abi protein complexes and associated Abl kinases to regulate actin dynamics downstream of adhesion and growth factor receptors during developmental morphogenesis. We showed that Abl kinases play a role in the formation and turnover of actin structures downstream of cell surface receptors. These processes are driven by localized actin polymerization, which we have demonstrated involves the activity of the Abi proteins. We have shown that the Abi/Nap1 complex is required for the formation and stability of cell-cell contacts, and that Abi exists in distinct protein complexes: one, which is comprised of two Abl-binding proteins, Abi and Wave, as well as Nap1, Sra1 and Arp2/3, and a second complex comprised of distinct novel Abi-binding proteins, which is required for cell-cell adhesion. Notably, mice deficient for Abl family kinases, Wave2, Abi1, and Nap1 exhibit striking developmental defects consistent with altered cytoskeletal dynamics and defective intercellular adhesion, leading to cardiovascular abnormalities. A fundamental gap in knowledge exists regarding the signaling pathways linking intercellular adhesion to actin polymerization. The specific aims of this proposal are: 1) to elucidate the mechanisms employed by Abi complexes to regulate morphogenesis downstream of adhesion receptors using in vitro models and knockout mice, with emphasis on our recently discovered Abi/Nap1-dependent and Arp2/3- independent pathway, which is critical for the integrity of cell-cell junctions; and 2) to define the mechanisms whereby the Abl kinases regulate cell proliferation, survival and adhesion in endothelial cells, with emphasis on trafficking of adhesion receptors. Significance: Results from the proposed studies will provide novel insights into the mechanisms whereby components of the actin polymerization machinery regulate adhesion processes critical for endothelial cell growth and survival. Moreover, our findings will provide much needed knowledge for elucidating the molecular basis of develomental abnormalities such as congenital cardiovascular disease and other pathologies induced by disregulated actin dynamics.