Regulation of myelination by myosin II-mediated mechanotransduction

描述（由申请人提供）：在中枢（CNS）多发性硬化症和外周（PNS）神经系统格林-巴利综合征等疾病中，髓鞘缺失导致沿着受影响轴突的传导阻滞，并成为临床缺陷特征的基础。 这些疾病。神经功能的恢复与髓鞘再生有关，髓鞘再生不仅恢复神经传导，而且重建有髓鞘轴突的正常分子组织。虽然有治疗CNS和PNS髓磷脂的炎症攻击的方法，但目前还没有设计直接靶向髓磷脂修复效率和神经功能恢复的治疗方法。我们确定了非肌肉肌球蛋白II（NMII）作为一种新的神经胶质细胞分化和髓鞘形成在PNS和CNS的关键调节剂。NMII对于雪旺细胞的轴突鞘化是必需的，并且其抑制损害它们的形态分化和形成髓鞘的能力。相反，在少突胶质细胞中抑制匪II促进细胞分支并增强髓鞘形成。这些明显相反的作用背后的分子机制目前尚不清楚，但如果理解可能提供新的治疗靶点，以促进脱髓鞘神经的修复和恢复神经功能。在本申请中，我们建议测试这样的假设：许旺细胞和少突胶质细胞感知和响应其环境独特机械特性的能力在这些细胞对NMII抑制的差异反应中发挥着重要作用。与本申请特别相关的是观察到细胞分支的程度和未分化细胞的谱系定型可以通过细胞外基质（ECM）弹性的变化以匪II依赖性方式调节。在目标#1中，我们将使用允许控制基质弹性的培养系统来表征ECM弹性的差异如何影响神经胶质细胞形态和分化，并通过进行功能丧失和获得实验来确定匪II在介导这些效应中的直接作用。在目标#2中，我们将使用活细胞成像和功能实验的丧失和获得的组合，建立过程延伸和Rho/ROCK下游的匪II活性下调之间的直接机制联系。最后，在目标#3中，我们将使用小鼠直接检查匪II与体内髓鞘发育和髓鞘再生的相关性，在所述小鼠中匪IIB在髓鞘生成CNS和PNS神经胶质中被条件性消融。我们研究的长期目标是了解调节雪旺细胞和少突胶质细胞分化的细胞骨架机制，以确定新的治疗靶点，促进髓鞘修复和神经功能恢复。

DESCRIPTION (provided by applicant): In diseases such as Multiple Sclerosis in the central (CNS) and Guilain-Barre Syndrome in the peripheral (PNS) nervous system, loss of myelin results in conduction block along affected axons and underlies the clinical deficits characteristic of these disorders. Recovery of neural function is associated with remyelination, which not only restores nerve conduction, but also re-establish the normal molecular organization of the myelinated axon. Although therapies are available that address the inflammatory attack on CNS and PNS myelin, there are currently no treatments designed to directly target the efficiency of myelin repair and the return of nerve function. We identified non-muscle myosin II (NMII) as a novel key regulator of glial cell differentiation and myelin formation in both the PNS and the CNS. NMII is necessary for the ensheathment of axons by Schwann cells, and its inhibition impairs their morphological differentiation and ability to form myelin. By contrast, inhibition of NMII in oligodendrocytes promotes cell branching and enhances myelin formation. The molecular mechanisms behind these remarkably opposite effects are currently unknown, but if understood might provide novel therapeutic targets to promote repair of demyelinated nerves and restore nerve function. In this application we propose to test the hypothesis that the ability of Schwann cells and oligodendrocytes to sense and respond to the unique mechanical properties of their environment plays a major role in the differential response of these cells to NMII inhibition. Of particular relevance for this application are the observations that the extent f cell branching and the lineage commitment of undifferentiated cells can be regulated by changes in the extracellular matrix (ECM) elasticity in a NMII-dependant manner. In Aim#1 we will characterize how differences in ECM elasticity affect glial cell morphology and differentiatio using a culture system that allows the control of substrate elasticity and determine the direct rol of NMII in mediating these effects by performing loss and gain of function experiments. In Aim#2 we will establish the direct mechanistic link between process extension and downregulation of NMII activity downstream of Rho/ROCK, using a combination of live-cell imaging and loss and gain of function experiment. Finally in Aim#3 we will directly examine the relevance of NMII for myelin development and remyelination in vivo using mice in which NMIIB has been conditionally ablated in myelinating CNS and PNS glia. The long-term goal of our research is to understand the cytoskeletal mechanisms regulating Schwann cell and oligodendrocyte differentiation as a way to identify novel therapeutic targets to promote myelin repair and recovery of nerve function.