Genetic Control of Schwann Cell Differentiation

项目概述：髓鞘是脊椎动物神经系统的重要组成部分。都是再生的 脱髓鞘疾病的疗法和治疗将通过了解 控制其合成。这些疾病是常见的，并占相当大的发病率和死亡率。 然而，髓鞘形成和髓鞘再生的调节知之甚少。在PNS中，雪旺细胞 需要轴突接触来增殖、存活和表达转录因子Oct-6， 这是及时形成髓鞘所必需的。在爪爪突变小鼠中， 雪旺细胞及其Oct-6下游效应基因的表达被延迟，即使Oct-6是 正常激活。最近，我们已经确定了遗传缺陷的潜在爪爪突变作为一个 Lgi 4（Leucine-rich glioma inactivated-4）基因。该基因由许旺细胞表达， 编码一种功能未知的分泌蛋白因此，许旺细胞分泌一种蛋白质， 轴突分离、Oct-6靶基因的激活和髓鞘形成。我们假设Lgi 4触发或 改变轴突或细胞外基质信号，从而调节许旺细胞对这些信号的反应。 我们提出了以下目的来确定Lgi 4在许旺细胞发育中如何起作用：1）测试Lgi 4在许旺细胞发育中的作用。 许旺细胞分化受Lgi 4表达水平调节的假设。2)测试 Lgi 4控制必需的雪旺细胞基因的表达的假说。3)测试的假设 Lgi 4通过Akt/PKB信号通路起作用。上面总结的实验集中在识别 雪旺细胞信号传导途径，响应于Lgi 4介导的细胞外信号传导;在这样做时，我们将 阐明导致外周髓鞘形成的遗传调控途径，从而提供 治疗髓鞘形成障碍的新疗法的基础。 相关性：影响髓鞘的疾病，如中枢神经系统多发性硬化症， 周围神经系统中的遗传性脱髓鞘性神经病是使人衰弱的和常见的。通过 了解Lgi 4蛋白如何控制许旺细胞发育，我们将建立新的途径， 髓鞘疾病和神经损伤的治疗。

Project Summary: Myelin is a crucial component of vertebrate nervous systems. Both regenerative therapies and treatment of demyelinating diseases will be facilitated by knowledge of the mechanisms that control its synthesis. These diseases are frequent, and account for considerable morbidity and mortality. However, the regulation of myelination and remyelination is poorly understood. In the PNS, Schwann cells require axonal contact for proliferation, survival, and for the expression of the transcription factor Oct-6, which is required for timely myelination. In claw paw mutant mice, both the segregation of axon fascicles by Schwann cells and their expression of Oct-6 downstream effector genes is delayed, even though Oct-6 is activated normally. Recently, we have identified the genetic defect underlying the claw paw mutation as an insertion in the Lgi4 (Leucine-rich glioma inactivated-4) gene. This gene is expressed by Schwann cells, and encodes a secreted protein of unknown function. Thus Schwann cells secrete a protein that they require for axon segregation, activation of Oct-6 target genes, and myelination. We hypothesize that Lgi4 triggers or modifies axonal or extracellular matrix signal(s), thereby regulating Schwann cell responses to these cues. We propose the following aims to determine how Lgi4 functions in Schwann cell development: 1) Test the hypothesis that Schwann cell differentiation is modulated by the level of Lgi4 expression. 2) Test the hypothesis that Lgi4 controls the expression of essential Schwann cell genes. 3) Test the hypothesis that Lgi4 acts through the Akt/PKB signaling pathway. The experiments summarized above focus on identifying Schwann cell signaling pathways that respond to Lgi4-mediated extracellular signaling; in doing so, we will elucidate the genetic regulatory pathways that result in the formation of peripheral myelin, thereby providing the foundation for new therapies to treat myelination disorders. Relevance: Diseases that affect myelin, such as multiple sclerosis in the central nervous system, and inherited demyelinating neuropathies in the peripheral nervous system, are both debilitating and frequent. By understanding how the Lgi4 protein controls Schwann cell development, we will establish new avenues for the treatment of myelin disorders and nerve injury.