DISSECTING MOLECULAR AND GENETIC MECHANISMS THAT PROMOTE MYELINATION

剖析促进髓鞘形成的分子和遗传机制

• 批准号: 8814129
• 负责人: Sarah Petersen
• 金额: $ 5.6万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-03-01 至 2017-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8814129
• 关键词: Action Potentials; Adhesions; Alleles; Axon; Binding; Biological Models; C-terminal; Caliber; Cell Communication; Cell Differentiation process; Cell membrane; Cells; Cellular biology; Charcot-Marie-Tooth Disease; Cleaved cell; DNA Sequence Alteration; Data; Defect; Demyelinating Diseases; Demyelinations; Development; Disease; Enhancers; Extracellular Domain; Family; Foundations; G Protein-Coupled Receptor Genes; G-Protein-Coupled Receptors; Genes; Genetic; Genetic Screening; Genomics; Human; In Situ Hybridization; Inherited; Ligands; Membrane; Modeling; Molecular Genetics; Multiple Sclerosis; Mus; Mutant Strains Mice; Mutation; Myelin; Myelin Sheath; N-terminal; Nerve; Nervous system structure; Neuraxis; Neuroglia; Neurons; Neuropathy; Numbness; Orphan; Pain; Peripheral; Peripheral Nerves; Peripheral Nervous System; Pharmacologic Substance; Phenotype; Process; Radial; Reporter; Resources; Role; Schwann Cells; Signal Transduction; Sorting - Cell Movement; Staging; Structure; Syndrome; Technology; Testing; Transgenic Organisms; Transmission Electron Microscopy; Universities; Washington; Work; Zebrafish; base; design; in vivo; innovation; model building; molecular domain; mutant; myelination; myelinopathy; nervous system disorder; novel; prevent; programs; public health relevance; receptor; therapeutic target; therapy development

DESCRIPTION (provided by applicant): Myelin is a multilayered membrane that ensheathes axons in vertebrate nervous systems. In the peripheral nervous system, specialized glia called Schwann cells wrap themselves around axonal segments to form the myelin sheath. Myelin is essential for trophic support of neurons and provides insulation to efficiently conduct nerve impulses. Disruption of the peripheral myelin sheath can result in devastating neuropathies such as Charcot-Marie-Tooth (CMT) disease. There are currently no treatments to prevent de-myelination or stimulate re-myelination, and development of these therapies is hindered by an incomplete understanding of the genetic and molecular factors that drive Schwann cells to form the myelin sheath. Schwann cell myelination requires Gpr126, an orphaned adhesion family G protein-coupled receptor (aGPCR). Loss of Gpr126 function in vertebrate models results in arrested development of Schwann cells at the promyelinating state and reduced or absent peripheral myelin. Although Gpr126 is essential for peripheral myelination, very little is known about the mechanism by which it functions. This study will utilize the zebrafish model system to define the role of Gpr126 in myelination. In the first aim, I will use structure-function analysis o define the molecular domains of Gpr126 that regulate key steps in peripheral myelination. I predict that the large N-terminal domain of Gpr126 has a distinct function in sorting each Schwann cell around a single large-caliber axon. In contrast, I hypothesize the transmembrane C-terminus of Gpr126 is sufficient to direct the Schwann cell to wrap the axon following sorting. I will generate specific zebrafish mutants and perform in vivo analyses to test these hypotheses. In my second aim, I will perform an innovative forward genetic screen for mutations that enhance or suppress myelin defects in gpr126 hypomorphic mutants. This enhancer/suppressor screen will identify regulators of the Gpr126 myelination program as well as novel factors that function in parallel to Gpr126 for myelination. By defining the molecular and genetic factors that promote myelination, these studies will provide the basis for identifying causative mutations for genetic neuropathies like CMT. This work also will also deepen our understanding of Schwann cell biology and can lay the foundation for developing therapies to treat demyelination and promote re-myelination of peripheral nerves.

描述（由申请人提供）：髓磷脂是一种多层膜，包裹脊椎动物神经系统中的轴突。在周围神经系统中，称为雪旺细胞的特殊神经胶质细胞将自身包裹在轴突节段周围，形成髓鞘。髓磷脂对于神经元的营养支持至关重要，并提供绝缘以有效传导神经冲动。外周髓鞘的破坏可导致毁灭性的神经病，例如腓骨肌萎缩症 (CMT) 病。目前尚无预防脱髓鞘或刺激髓鞘再生的治疗方法，并且由于对驱动雪旺细胞形成髓鞘的遗传和分子因素的不完全了解，阻碍了这些疗法的发展。雪旺细胞髓鞘形成需要 Gpr126，一种孤儿粘附家族 G 蛋白偶联受体 (aGPCR)。脊椎动物模型中 Gpr126 功能的丧失会导致雪旺细胞在早髓鞘形成状态下发育停滞，并导致外周髓磷脂减少或缺失。尽管 Gpr126 对于外周髓鞘形成至关重要，但对其发挥作用的机制知之甚少。本研究将利用斑马鱼模型系统来定义 Gpr126 在髓鞘形成中的作用。第一个目标是，我将使用结构功能分析来定义调节外周髓鞘形成关键步骤的 Gpr126 分子结构域。我预测 Gpr126 的大 N 端结构域在对单个大口径轴突周围的每个施万细胞进行分类方面具有独特的功能。相反，我假设 Gpr126 的跨膜 C 末端足以引导雪旺细胞在分选后包裹轴突。我 将产生特定的斑马鱼突变体并进行体内分析来测试这些假设。在我的第二个目标中，我将对增强或抑制 gpr126 亚态突变体中髓磷脂缺陷的突变进行创新的正向遗传筛选。该增强子/抑制子筛选将识别 Gpr126 髓鞘形成程序的调节因子以及与 Gpr126 髓鞘形成并行作用的新因子。通过定义促进髓鞘形成的分子和遗传因素，这些研究将为识别 CMT 等遗传性神经病的致病突变提供基础。这项工作还将加深我们对雪旺细胞生物学的理解，并为开发治疗脱髓鞘和促进周围神经髓鞘再生的疗法奠定基础。