How Does Actin Disassembly Drive Myelin Wrapping?

肌动蛋白分解如何驱动髓磷脂包裹？

• 批准号: 10474732
• 负责人: John B Zuchero
• 金额: $ 5.36万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-30 至 2022-02-18
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10474732
• 关键词: Actins; Automobile Driving; Axon; Cells; Cellular biology; Chronic; Cytoskeleton; Data; Demyelinating Diseases; Development; Disease; Dissection; Dorsal; Electron Microscopy; Financial compensation; Foundations; Future; Genetic; Goals; Growth Cones; Image; Impairment; Injections; Injury; Knowledge; Light; Measures; Mediating; Membrane; Methods; Microfilaments; Microscopy; Modeling; Morphology; Multiple Sclerosis; Multiple Sclerosis Lesions; Mus; Myelin; Myelin Sheath; Neonatal; Neuraxis; Neurons; Oligodendroglia; PTEN gene; Pathway interactions; Patients; Permeability; Pharmaceutical Preparations; Phenotype; Positioning Attribute; Primary Cell Cultures; Process; Proteins; Reporter; Research; Resolution; Role; Specificity; Spinal Cord; Stains; Techniques; Testing; Time; Tissues; Vertebrates; Viral; base; cell motility; conditional knockout; disability; in vivo; innovation; jasplakinolide; light microscopy; live cell imaging; multidisciplinary; myelination; neonatal mice; nervous system development; nervous system disorder; neuronal growth; neurotransmission; novel; prevent; promoter; remyelination; tool; translational study

PROJECT SUMMARY/ABSTRACT Myelin—the electrical insulator around neuronal axons—is essential in vertebrates for rapid nerve signaling, and its loss in diseases like multiple sclerosis and following injury causes severe disability in patients. In the central nervous system, oligodendrocytes build myelin by first extending their membrane processes to ensheath axons, then wrapping spirally around the axon while compacting their membranes to become electrically insulating. In chronic multiple sclerosis lesions, oligodendrocytes ensheath axons but fail to wrap, suggesting that wrapping is a rate-limiting step for remyelination. To ultimately understand why remyelination fails in multiple sclerosis, we first aim to understand the mechanism by which myelin wraps normally. It was long hypothesized that the assembly of actin filaments provides the force required to drive wrapping, like the lamellipodium of a motile cell or a neuronal growth cone. However, we and others recently discovered that the dramatic disassembly of the oligodendrocyte actin cytoskeleton is required for wrapping. This finding was completely unexpected and suggests two models for wrapping. Cycles of actin disassembly and reassembly could be required to “ratchet” the oligodendrocyte membrane forward. In contrast, based on our preliminary data, we propose that actin disassembly acts as a “trigger” to initiate actin-independent wrapping and that the major role of actin disassembly is to allow myelin to compact. To test these models, we are using a suite of innovative approaches including first-in-class genetic tools we created to experimentally induce actin disassembly (DeActs) or block actin disassembly (StablActs) in oligodendrocytes during wrapping in vivo, advanced microscopy techniques to resolve myelin in vivo, and live cell imaging of oligodendrocytes in culture. Our preliminary data demonstrate: (1) actin filaments disassemble in oligodendrocytes prior to wrapping, (2) experimentally inducing actin disassembly specifically in oligodendrocytes in vivo increases myelin wrapping, and (3) experimentally blocking actin disassembly impairs myelin membrane compaction in a culture model of myelination. These data support the “trigger” model of myelin wrapping, laying the foundation for future translational studies to test whether this actin disassembly-based mechanism is recapitulated or perturbed during remyelination. By defining the role of actin disassembly in myelin wrapping and compaction, this project will open up new research directions towards understanding myelin formation, plasticity, and disease in the central nervous system.

项目摘要/摘要 髓磷脂--神经元轴突周围的电绝缘体--对于脊椎动物来说是快速神经信号传递所必需的， 在多发性硬化症和受伤后的疾病中，它的丢失会导致患者严重残疾。在 中枢神经系统，少突胶质细胞通过首先将其膜突起延伸到 包裹轴突，然后螺旋包裹在轴突周围，同时将它们的膜压缩成 电绝缘的。在慢性多发性硬化症病变中，少突胶质细胞包裹轴突，但不包裹， 这表明包裹是重新髓鞘形成的限速步骤。为了最终理解为什么重新髓鞘形成 在多发性硬化症中失败，我们首先旨在了解髓鞘正常包裹的机制。确实是 长期以来，人们假设肌动蛋白细丝的组装提供了驱动包裹所需的力，就像 运动细胞或神经元生长锥体的片层。然而，我们和其他人最近发现， 少突胶质细胞肌动蛋白细胞骨架的戏剧性分解是包裹所必需的。这一发现是 完全出乎意料，并建议了两种包装模式。肌动蛋白拆解和重组的循环 可能需要将少突胶质细胞膜向前“棘轮”。相比之下，根据我们的初步调查， 数据，我们认为肌动蛋白的分解起到了启动肌动蛋白非依赖性包装的“触发器”的作用，并且 肌动蛋白分解的主要作用是使髓鞘变得紧密。为了测试这些模型，我们使用了一套 创新的方法，包括我们创造的一流的基因工具，用于实验诱导肌动蛋白 在体内包裹过程中少突胶质细胞的拆解(DeActs)或阻断肌动蛋白拆解(SablActs)， 先进的显微技术在体内分解髓鞘，以及在培养中对少突胶质细胞进行活细胞成像。 我们的初步数据表明：(1)少突胶质细胞在包裹前肌动蛋白细丝解体，(2) 体内诱导少突胶质细胞特异性肌动蛋白分解的实验增加了髓鞘包裹， (3)实验上阻断肌动蛋白的分解损害了培养模型中髓鞘膜的致密化。 髓鞘形成。这些数据支持髓鞘包裹的“触发式”模型，为未来的研究奠定了基础 翻译研究，以测试这种基于肌动蛋白分解的机制是重述还是被干扰 在重新髓鞘形成过程中。通过定义肌动蛋白分解在髓鞘包裹和压缩中的作用，这个项目 将为理解髓鞘的形成、可塑性和疾病开辟新的研究方向。 中枢神经系统。