Arg coordinates contractile forces with adhesion dynamics in migrating neurons

描述（由申请人提供）：通过粘附线索精确控制神经元迁移对于适当的大脑发育至关重要。神经元迁移起始于富含F-肌动蛋白的膜突起的一个前导过程。粘附锚突起和连接细胞的F-肌动蛋白细胞骨架的细胞外基质。肌动球蛋白收缩产生牵引力，将前导突起向前拉。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构。已知这些迁移信号通路的缺陷会引起神经元迁移障碍（NMD），包括头部障碍、无脑回、异位和癫痫。Abl家族的非受体酪氨酸激酶（包括Abl和Arg）是发育中动物神经元迁移的重要调节因子。ABL-/-Arg-/-双敲除小鼠表现出由异常小脑颗粒神经元迁移引起的显著小脑畸形。Rho抑制剂p190 RhoGAP-A是发育中大脑的主要Arg底物。我已经证明，整合素接合将Arg定位于细胞外周的特定区域，其中Arg激活p190 A以抑制Rho诱导的细胞基质粘附（局灶性粘附）以及肌动蛋白和肌球蛋白的收缩束（应力纤维）。精氨酸抑制应力纤维导致细胞收缩性降低。精氨酸对细胞收缩性和粘着斑动力学的影响减弱了粘附基质上的细胞迁移。我发现Arg，而不是Abl，在这些细胞迁移表型中起主要作用。我推测，精氨酸协调迁移神经元的收缩和粘附过程，以确保准确的神经元定位。我的建议的目标是确定精氨酸如何协调迁移小脑颗粒神经元的收缩和粘附动力学。在目标1中，我将确定精氨酸如何局部调节迁移成纤维细胞的收缩性，作为神经元迁移的模型系统。在目标2中，我将确定精氨酸如何调节迁移成纤维细胞中的粘着斑动力学。在目标3中，我将确定精氨酸如何协调迁移小脑颗粒神经元的收缩和粘附。总的来说，这些实验应该提供一个详细的分子框架，以了解NMD的原因，并可能发现新的疗法或药物治疗，以减轻NMD患者的症状。神经元迁移障碍导致严重的发育和认知障碍，但在适当迁移的神经元中协调迁移机制的信号传导机制尚不清楚。我提出了一种新的信号通路，协调迁移神经元的收缩和粘附。

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.