Morphogenesis and function of somatosensory axon ensheathment by epidermal cells

表皮细胞体感轴突鞘的形态发生和功能

• 批准号: 10220849
• 负责人: Alvaro Sagasti
• 金额: $ 35.61万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-05-15 至 2025-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10220849
• 关键词: Adherens Junction; Adult; Affect; Afferent Neurons; Animals; Axon; Basal Cell; Behavioral Assay; CRISPR screen; CRISPR/Cas technology; Caenorhabditis elegans; Cell membrane; Cell physiology; Cells; Chemicals; Cholesterol; Complement; Dendrites; Desmosomes; Development; Disease; Drosophila genus; Epidermis; Epithelial; Epithelial Cells; Event; F-Actin; Fishes; Functional disorder; Grant; Human; Image; Individual; Integral Membrane Protein; Larva; Lipids; Mammals; Mechanics; Mediating; Membrane; Methods; Microscopy; Modeling; Molecular; Morphogenesis; Mutagenesis; Neck; Nervous System Physiology; Neurites; Neuroglia; Neurons; Neurophysiology - biologic function; Nociception; Pain; Periderm; Peripheral; Play; Process; Property; Proteins; Reporter; Resolution; Role; Schwann Cells; Sensory; Signal Transduction; Site; Skin; Stimulus; Structure; Study models; Subcellular structure; Supporting Cell; System; Testing; Touch sensation; Transgenic Organisms; Vertebrates; Work; Zebrafish; cell type; epidermis cell; experimental study; fly; innovation; keratinocyte; knock-down; neural circuit; neuron development; optogenetics; pain sensation; plakoglobin; protein distribution; receptor; recruit; repaired; response; seal; sensor; somatosensory; temporal measurement; tool; transcriptome; virtual

PROJECT SUMMARY Selective interactions between neurons and non-neuronal cells are crucial for the development and function of neural circuits. Pain-sensing somatosensory neurons project peripheral axons to the skin, where they branch extensively amongst epithelial epidermal cells. Although these sensory terminals are called “free endings”, recent studies have revealed that they are often wrapped by epidermal cells, which enclose them into ensheathment channels reminiscent of those formed by non-myelinating Remak Schwann cells. Although underappreciated, epidermal ensheathment channels have been observed in worms, flies, fish, and mammals, indicating that ensheathment is a conserved feature of epidermal sensory endings, and thus likely plays critical roles in the development and function of nociceptive axons. Little is known about the morphogenetic process of axon ensheathment by epidermal cells, and nothing is known about how these structures contribute to sensory function or disease in vertebrate animals. This proposal investigates the morphogenetic mechanisms that create epidermal ensheathment channels and how they contribute to sensory function in zebrafish larvae. Their external development and the availability of unique transgenic tools make zebrafish an ideal model for studying this dynamic morphogenetic process. Preliminary work using live fluorescent reporters for subcellular structures in zebrafish skin cells identified a sequence of events leading up to ensheathment and suggested a step-wise morphogenetic process. First, axons growing into this epidermis induce the formation of specialized lipid microdomains at skin cell-axon contact sites. Second, F-actin is recruited to these microdomains, likely promoting membrane invagination to initiate the ensheathment process. Finally, adherens junctions and desmosomes form at “necks” of ensheathment channels to tightly seal the channels. The first two aims of this proposal use innovative microscopy approaches for high spatial and temporal resolution live imaging, cell-specific molecular manipulations, and CRISPR/Cas9-mediated mutagenesis to determine how axons and skin cells establish selective interactions and execute the ensheathment process. These studies will illuminate morphogenetic mechanisms relevant not just to axon ensheathment by epidermal and glial cells, but also to basic cellular processes, like the formation of membrane signaling domains and junction assembly. The third aim combines imaging and behavioral assays to reveal how axon ensheathment impacts neuronal structure and function. These studies have the potential to uncover a critical feature of the touch-sensing apparatus and suggest how ensheathment contributes to disease conditions affecting pain and touch sensation.

项目摘要 神经元和非神经元细胞之间的选择性相互作用对于神经元的发育和功能至关重要。 神经回路感受疼痛的躯体感觉神经元将外周轴突投射到皮肤，并在那里形成分支 广泛存在于上皮细胞中。虽然这些感觉末梢被称为“游离末梢”， 最近的研究表明，它们通常被表皮细胞包裹，表皮细胞将它们包围在 鞘化通道使人联想到由非髓鞘化Remak Schwann细胞形成的那些。虽然 在蠕虫、蝇、鱼和哺乳动物中观察到了未被充分认识的表皮鞘通道， 这表明鞘化是表皮感觉末梢的保守特征，因此可能起着关键作用。 在伤害性轴突的发育和功能中的作用。关于其形态发生过程知之甚少， 轴突鞘由表皮细胞，并没有什么是知道这些结构如何有助于感觉 脊椎动物的功能或疾病。 该建议调查了产生表皮鞘管通道的形态发生机制， 它们如何影响斑马鱼幼鱼的感觉功能。他们的外部发展和可用性 独特的转基因工具使斑马鱼成为研究这种动态形态发生过程的理想模型。 使用活荧光报告子对斑马鱼皮肤细胞亚细胞结构进行初步研究， 一系列的事件导致ensheathment，并提出了一个逐步的形态发生过程。第一、 轴突生长到这个表皮诱导形成专门的脂质微域在皮肤细胞轴突 接触部位。其次，F-肌动蛋白被募集到这些微区，可能促进膜内陷， 启动入鞘过程最后，粘附连接和桥粒形成在细胞的“颈部”， 套入通道以紧密密封通道。该提案的前两个目标是使用创新的 用于高空间和时间分辨率实时成像的显微镜方法，细胞特异性分子 操作和CRISPR/Cas9介导的诱变，以确定轴突和皮肤细胞如何建立 选择性相互作用并执行包封过程。这些研究将阐明形态发生学 不仅与表皮细胞和神经胶质细胞对轴突的鞘化有关， 过程，如膜信号结构域和连接组装的形成。第三个目标结合了 成像和行为测定，以揭示轴突鞘化如何影响神经元结构和功能。 这些研究有可能揭示触摸感应装置的一个关键特征，并提出如何 鞘入有助于影响疼痛和触觉的疾病状况。