Arg coordinates contractile forces with adhesion dynamics in migrating neurons

描述(由申请人提供)：通过粘连线索精确控制神经元迁移对大脑的正常发育至关重要。神经元迁移是通过富含F-肌动蛋白的膜突起的主导过程来启动的。粘连将突起固定，并将细胞F-肌动蛋白细胞骨架连接到细胞外基质。肌动球蛋白的收缩然后产生牵引力，将领先的过程向前拉。这种迁移装置由细胞表面受体控制，细胞表面受体将迁移信号传递给细胞骨架机械。这些迁移信号通路的缺陷已知会导致神经元迁移障碍(NMD)，包括头部障碍、失眠、异位和癫痫。ABL家族的非受体酪氨酸激酶，包括Abl和Abl相关基因(Arg)，是发育过程中神经元迁移的重要调节因子。ABL-/-Arg-/-双基因敲除小鼠表现出明显的小脑畸形，这是由异常的小脑颗粒神经元迁移引起的。Rho抑制剂p190RhoGAP-A是发育中大脑中的主要Arg底物。我已经证明，整合素的结合将Arg定位于细胞外围的特定区域，在那里Arg激活p190A以抑制Rho诱导的细胞-基质粘连(灶性粘连)以及肌动蛋白和肌球蛋白收缩束(应力纤维)。Arg抑制应激纤维导致细胞收缩能力下降。精氨酸对细胞收缩和局部黏附动力学的影响减弱了细胞在黏附底物上的迁移。我发现在这些细胞迁移表型中起主要作用的是Arg，而不是Abl。我假设Arg协调迁移神经元的收缩和粘连过程，以确保神经元的准确定位。我的建议的目标是确定Arg如何协调迁移的小脑颗粒神经元的收缩和黏附动力学。在目标1中，我将确定Arg如何局部调节迁移的成纤维细胞的收缩性能，作为神经元迁移的模型系统。在目标2中，我将确定Arg如何调节迁移中的成纤维细胞的局部黏附动力学。在目标3中，我将确定Arg如何协调迁移的小脑颗粒神经元的收缩和粘连。总体而言，这些实验应该为了解NMD的原因以及潜在地发现缓解NMD患者症状的新疗法或药物治疗提供详细的分子框架。神经元迁移障碍会导致严重的发育和认知障碍，但协调正常迁移神经元中迁移机制的信号机制尚不清楚。我提出了一种新的信号通路来协调迁移神经元的收缩和黏附。

DESCRIPTION (provided by applicant): The precise control of neuronal migration by adhesive cues is essential for proper brain development. Neuron migration initiates via F-actin-rich membrane protrusion of a leading process. Adhesions anchor the protrusion and link the cellular F-actin cytoskeleton to the extracellular matrix. Actomyosin contraction then generates traction force to pull the leading process forward. This migratory apparatus is controlled by cell surface receptors that relay migratory signals to the cytoskeleton machinery. Defects in these migratory signaling pathways are known to cause neuronal migration disorders (NMDs), including cephalic disorders, agyrias, heterotopias, and epilepsy. Abl family non-receptor tyrosine kinases, including Abl and Abl-related gene (Arg), are important regulators of neuron migration in developing animals. abl-/-arg-/- double knockout mice exhibit significant cerebellar deformities caused by aberrant cerebellar granular neuron migration. The Rho inhibitor p190RhoGAP-A is a major Arg substrate in the developing brain. I have shown that integrin engagement localizes Arg to specific regions at the cell periphery, where Arg activates p190A to inhibit Rho-induced cell-matrix adhesions (focal adhesions) and contractile bundles of actin and myosin (stress fibers). Arg inhibition of stress fibers leads to a decrease in cell contractility. The effects of Arg on cell contractility and focal adhesion dynamics attenuate cell migration on adhesive substrates. I found that Arg, not Abl, played the major role in these cell migration phenotypes. I hypothesize that Arg coordinates contractile and adhesive processes in migrating neurons to ensure accurate neuronal positioning. The goal of my proposal is to determine how Arg coordinates contractility and adhesion dynamics in migrating cerebellar granular neurons. In aim 1, I will determine how Arg locally regulates contractility in migrating fibroblasts, as a model system for neuronal migration. In aim 2, I will determine how Arg regulates focal adhesion dynamics in migrating fibroblasts. In aim 3, I will determine how Arg coordinates contractility and adhesion in migrating cerebellar granular neurons. Overall, these experiments should provide a detailed molecular framework for understanding the causes of NMDs and potentially discovering novel therapies or drug treatments that alleviate the symptoms of those suffering from NMDs. Neuronal migration disorders lead to severe developmental and cognitive disorders, but the signaling mechanisms that coordinate migratory machinery in properly-migrating neurons are unknown. I propose a novel signaling pathway that coordinates contractility and adhesion in migrating neurons.