Actomyosin motors and Mechanism of Myelin Formation

描述（由申请人提供）：髓鞘由轴突周围的胶质膜螺旋包裹形成。的;这一过程的机制尚不清楚，但可能涉及神经胶质细胞骨架的变化。我们实验室最近的数据强烈表明，肌凝蛋白轻链（MLC）磷酸化对肌动球蛋白组装的调节是这一过程的一个重要方面。我们发现rho相关激酶（ROCK）和肌球蛋白轻链激酶（MLCK）是参与MLC磷酸化的两种主要激酶，它们在髓鞘形成中具有非常不同的作用。在雪旺细胞-神经元共培养中，抑制ROCK导致非典型雪旺细胞形态，细胞分支异常，沿轴突长度形成多个独立的小髓鞘节段，每个节段都有相关的淋巴结和偏旁。这种组织部分类似于由少突胶质细胞形成的髓磷脂。相比之下，抑制MLCK似乎通过干扰轴突周围髓鞘的螺旋包裹来阻止髓鞘形成。我们还发现，在发育过程中髓鞘形成时，MLC磷酸化是稳定但短暂的激活。在本研究中，我们将验证ROCK和MLCK这两个调节MLC磷酸化和肌动球蛋白活性的主要途径直接参与髓磷脂形态及其包裹轴突的控制的假设。该项目的总体目标是为PNS和CNS中髓磷脂形态和形成的调节机制提供新的见解。对髓鞘形成的分子机制的基本了解将有助于开发新的治疗策略来促进疾病的髓鞘再生；如多发性硬化症和周围脱髓鞘神经病。

DESCRIPTION (provided by applicant): The myelin sheath forms by the spiral wrapping of a glial membrane around an axon. The; mechanisms responsible for this process are unknown but are likely to involve changes in the glial cell cytoskeleton. Recent data from our laboratory strongly suggest that regulation of actomyosin assembly via phosphorylation of myosin light chain (MLC) is an important aspect of this process. We have found that Rho-associated kinase (ROCK) and myosin light chain kinase (MLCK), two of the major kinases involved in MLC phosphorylation, have very distinct roles on myelination. In Schwann cell-neuron cocultures, inhibition of ROCK results in atypical Schwann cell morphology, with cells that branch aberrantly and form multiple, small independent myelin segments along the length of axons, each with associated nodes and paranodes. This organization partially resembles myelin formed by oligodendrocytes. By contrast, inhibition of MLCK appears to prevent myelination by interfering with the spiral wrapping of the myelin sheath around the axon. We have also found that MLC phosphorylation is robustly, but transiently, activated at the onset of myelination during development. In this study we will test the hypothesis that ROCK and MLCK, two of the major pathways regulating MLC phosphorylation and hence actomyosin activity, are directly involved in the control of myelin morphology and its wrapping around the axon. The overall goal of this project is to provide novel insights into the mechanisms that regulate myelin morphology and formation in the PNS and CNS. A basic understanding of the molecular machinery of myelination should aid in the development of new therapeutic strategies to promote remyelination in diseases; such as multiple sclerosis and peripheral demyelinating neuropathies.