The role of Nrg1 signaling in Schwann cell development and myelination

Nrg1 信号在雪旺细胞发育和髓鞘形成中的作用

• 批准号: 9049928
• 负责人: Daniel Lysko
• 金额: $ 5.42万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-12-01 至 2018-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9049928
• 关键词: Alleles; Animal Model; Antibodies; Autoimmunity; Axon; Biological Models; Charcot-Marie-Tooth Disease; Cues; Defect; Development; Disease; Environmental Risk Factor; Functional disorder; Genes; Human; Inherited; Knock-in Mouse; Ligands; Location; Mammals; Measures; Mitogens; Monitor; Morbidity - disease rate; Motor; Mutation; Myelin; Myelin Sheath; Nerve; Neural Crest; Neuregulin 1; Neuregulins; Neurologic; Neuropathy; Pain; Paralysed; Patients; Peripheral Nervous System; Peripheral Nervous System Diseases; Phenotype; Play; Population; Prevalence; Prevention; Proliferating; Protein Isoforms; Publishing; Regulation; Rodent; Role; Schwann Cells; Sensory; Severities; Signal Transduction; Signaling Molecule; Speed; Staging; Symptoms; Testing; Therapeutic; Thick; Transgenic Organisms; Work; Zebrafish; axon injury; cell motility; diabetic; genome editing; in vivo; migration; mutant; myelination; novel; painful neuropathy; public health relevance; receptor; remyelination; research study

 DESCRIPTION (provided by applicant): Patients with peripheral neuropathy suffer from debilitating sensory and motor symptoms. Developmental defects or damage to Schwann cells or axons can cause neuropathy. In the peripheral nervous system, Schwann cells wrap the axons in nerves and form the myelin sheath. Understanding the mechanisms that regulate Schwann cells is crucial to approaching therapies for remyelination and prevention of axonal damage in neuropathy patients. Studies in zebrafish, a powerful vertebrate model system with myelinated nerves, have led to key discoveries in nerve development, including the role of one Neuregulin isoform (type III) as a guidance cue for Schwann cells migrating in growing nerves. I hypothesize that changes in the localization or levels of Nrg1 type III on axons and ErbB receptors on Schwann cells drive different developmental decisions of Schwann cells, and that Nrg1 type I and type II signals cooperate with type III to control different steps of Schwann cell development. This project will discover the roles of the remaining vertebrate Nrg1 isoforms (type I and II) by using genome editing to generate isoform-specific Nrg1 mutants. Analyses of the phenotypes of these novel mutants will define the functions of type I and type II Nrg1 isoforms in vivo. The ability of Nrg1 type I and II to guide Schwann cells to ectopic locations will be tested n transgenic zebrafish. Nrg1 signaling functions throughout Schwann cell development to control specification, migration, proliferation and myelination, but it remains a major challenge to understand how Nrg1 controls so many different steps of Schwann cell development. One possibility is that Nrg1 level or distribution changes dynamically to define each stage of Schwann cell development. Creation of a tagged Nrg1 knock-in allele will allow changes in the localization and levels of endogenous Nrg1 to be monitored in vivo. Nrg1 signals though heterodimeric ErbB2/3 receptors on Schwann cells as they migrate towards the axon terminus, but it is not known whether ErbB receptors or downstream signaling molecules are polarized within migrating Schwann cells. Using antibodies and tagged receptors, the distribution and activity of ErbB receptors will be tested in migrating Schwann cells. To increase the levels of ErbB receptor activity, we will express constitutively active ErbB receptors and measure impact on migration, proliferation and myelination in vivo. These experiments will examine the mechanisms underlying regulation of Schwann cell development, myelination, and ultimately peripheral neuropathy. Despite the prevalence and severity of peripheral neuropathies, there is no cure for these diseases. This emphasizes the need to understand the mechanisms that control Schwann cell development and myelination, which may provide approaches toward therapeutic remyelination and prevention of axonal damage. This proposal will provide new animal models of neuropathy, elucidate the pathophysiology of neuropathy, and suggest roads toward new therapies.

 描述(申请人提供)：周围神经病患者出现感觉和运动衰弱症状。发育缺陷或雪旺细胞或轴突受损可导致神经病变。在周围神经系统中，雪旺细胞包裹神经中的轴突，形成髓鞘。了解调节雪旺细胞的机制对于探讨神经病患者重新髓鞘形成和预防轴突损伤的治疗方法至关重要。斑马鱼是一种具有有髓神经的强大脊椎动物模型系统，对斑马鱼的研究导致了神经发育方面的关键发现，包括一种神经调节蛋白亚型(类型III)作为雪旺细胞在生长神经中迁移的指导信号的作用。我推测，Nrg1III型在轴突上的定位或水平的变化以及雪旺细胞上ErbB受体的变化驱动了雪旺细胞不同的发育决定，并且Nrg1I型和II型信号与III型信号协同控制雪旺细胞发育的不同步骤。该项目将通过使用基因组编辑来产生特定于Nrg1的突变体，从而发现剩下的脊椎动物Nrg1亚型(类型I和II型)的作用。对这些新突变体的表型分析将确定I型和II型Nrg1亚型在体内的功能。Nrg1I型和II型引导雪旺细胞到异位位置的能力将在转基因斑马鱼上进行测试。NRG1信号在雪旺细胞发育的整个过程中起着控制规格、迁移、增殖和髓鞘形成的作用，但要了解Nrg1是如何控制雪旺细胞发育的这么多不同步骤仍然是一个重大挑战。一种可能性是Nrg1水平或分布动态变化，以定义雪旺细胞发育的每个阶段。标记的Nrg1敲入等位基因的创建将允许在体内监测内源性Nrg1的定位和水平的变化。当NRG1向轴突末端迁移时，NRG1通过雪旺细胞上的异二聚体ErbB2/3受体传递信号，但尚不清楚迁移中的雪旺细胞中是否存在ErbB受体或下游信号分子极化。使用抗体和标记的受体，将测试ErbB受体在迁移的雪旺细胞中的分布和活性。为了提高ErbB受体的活性水平，我们将表达具有结构性活性的ErbB受体，并在体内检测对迁移、增殖和髓鞘形成的影响。这些实验将研究雪旺细胞发育、髓鞘形成以及最终的周围神经病变的潜在调控机制。尽管周围神经病的发病率和严重性很高，但这些疾病是无法治愈的。这强调了有必要了解控制雪旺细胞发育和髓鞘形成的机制，这可能为治疗再髓鞘形成和预防轴突损伤提供方法。这项建议将提供新的神经病动物模型，阐明神经病的病理生理学，并为新的治疗方法提供方向。