Molecular regulation of dendrite morphogenesis

树突形态发生的分子调控

• 批准号: 9068254
• 负责人: DAVID M MILLER
• 金额: $ 34.04万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-06-01 至 2018-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9068254
• 关键词: Actins; Address; Adherens Junction; Afferent Neurons; Animal Model; Animals; Architecture; Binding; Biological; Brain; C-terminal; Caenorhabditis elegans; Cell Adhesion Molecules; Cell membrane; Cell surface; Cells; Complex; Cues; Cysteine; Cytoplasmic Tail; Dendrites; Development; Disabled Persons; Disease; EGF gene; Epidermis; Event; F-Actin; Figs - dietary; Genes; Genetic; Goals; Growth; Health; Homeodomain Proteins; Homologous Gene; Human; Image; Individual; Insecta; Intercellular Junctions; Invertebrates; Lateral; Lead; Length; Life; Ligands; Location; Mammals; Mediating; Membrane Proteins; Methods; Microfilaments; Modeling; Molecular; Morphogenesis; Morphology; Motor; Mutate; Myosin ATPase; Nematoda; Nervous system structure; Neurons; Nociception; Organism; Pain; Pathway interactions; Pattern; Perception; Process; Proteins; Regulation; Resolution; Role; Sensory; Signal Pathway; Signal Transduction; Sister; Skin; Specific qualifier value; Stimulus; Structure; Subcutaneous Tissue; System; Techniques; Testing; Tissues; Total Internal Reflection Fluorescent; Transmembrane Domain; Withdrawal; Work; adapter protein; axon guidance; base; extracellular; genetic analysis; homeodomain; insight; interest; neuron development; non-muscle myosin; novel; polymerization; receptor; research study; response; time use; tool; trafficking; transcription factor

DESCRIPTION (provided by applicant): Sensory neurons utilize complex, topical networks of dendritic processes to detect external stimuli. Models that seek to explain the creation of these elaborate structures must include mechanisms that control the key events of branch initiation, elongation and termination. These features are universally observed in both vertebrate and invertebrate systems and are therefore likely governed by evolutionarily conserved components. The simple model organism, C. elegans, displays a single pair of PVD nociceptive neurons that envelop the animal with a net-like array of dendritic branches. We used time-lapse imaging to show that the discrete topical region occupied by each branch is defined by a contact-dependent mechanism in which sister dendrites (i.e., dendrites from the same neuron) repel each other to stop outgrowth. "Self-avoidance" is also observed in mammals and insects but the molecular underpinning of this fundamental patterning event is poorly understood. Our work has revealed a novel mechanism in which the diffusible cue UNC-6/Netrin is captured at the tips of PVD dendrites to mediate self-avoidance in a pathway involving the receptors UNC-40/DCC and UNC-5. This discovery is significant because it describes the first example of a role for these highly conserved proteins in dendrite self-avoidance. Now, we have extended these findings to identify multiple downstream components of the UNC-6/Netrin self-avoidance pathway. On the basis of these new results, we propose that UNC-6/Netrin triggers actin filament growth at the tips of contacting sister dendrites to engage a non-muscle myosin motor that drives retraction. Experiments described in Specific Aim 1 exploit the novel application of TIRF microscopy to a living organism to test this model. These studies are significant because little is known of how signals at the cell membrane trigger dendrite withdrawal during self-avoidance. Our work has uncovered a key role for a conserved membrane protein, tomoregulin, in self-avoidance. Specific Aim 2 will define the mechanism of this effect and determine if tomoregulin is necessary for other known short-range UNC- 6/Netrin signaling events. Aim 2 is significant because it addresses the fundamental question of how the UNC-6/Netrin pathway has been uniquely adapted for contact-dependent self-avoidance. To address the mechanism of dendritic outgrowth, we exploited powerful cell-specific profiling methods to identify targets of a conserved LIM-homeodomain transcription factor, MEC-3, that is required for PVD branching. Specific Aim 3 will test a model, based on these results, that dendritic branches are stabilized by interaction with claudin-like proteins and other specific cell-surface components in the adjacent epidermis. These experiments are important because sensory neuron outgrowth is typically executed in close contact with epidermal tissue but the intercellular mechanisms that pattern dendritic architecture in this location are poorly defined. This work in C. elegans is expected to identify key determinants that also specify dendritic architecture in the human nervous system.

描述（申请人提供）：感觉神经元利用复杂的树突过程局部网络来检测外部刺激。试图解释这些精致结构的创建的模型必须包括控制分支开始，伸长和终止的关键事件的机制。这些特征在脊椎动物和无脊椎动物系统中都普遍观察到，因此很可能受到进化保守的组件的控制。简单的模型有机体C.秀拉统显示了一对一对PVD伤害性神经元，该神经元与净状树突状分支包裹着动物。我们使用延时成像来表明每个分支占据的离散局部区域是由接触依赖的机制定义的，在该机制中，姐妹树突（即来自同一神经元的树突）互相排斥以停止生长。在哺乳动物和昆虫中也观察到了“自我避免”，但是对此基本图案事件的分子底座知之甚少。我们的工作揭示了一种新的机制，其中可扩散的提示UNC-6/Netrin在PVD树突的尖端被捕获，以介导涉及受体UNC-40/DCC和UNC-5的途径中的自我避免。这一发现很重要，因为它描述了这些高度保守的蛋白在树突自我避免的情况下的作用的第一个例子。现在，我们扩展了这些发现，以识别UNC-6/Netrin自避免途径的多个下游组件。在这些新结果的基础上，我们建议UNC-6/Netrin触发肌动蛋白丝的生长，以与姐妹树突接触以吸引可撤回的非肌肉肌球蛋白运动。特定目标1中描述的实验利用了TIRF显微镜在活生物体中测试该模型的新型应用。这些研究很重要，因为很少知道细胞膜的信号如何避免自我避免树突戒断。我们的工作发现了自避免的保守膜蛋白（pyore蛋白）的关键作用。特定的目标2将定义这种作用的机制，并确定在其他已知的短距离UNC-6/Netrin信号事件中是否需要多环蛋白。 AIM 2很重要，因为它解决了如何将UNC-6/Netrin途径如何独特地适应接触依赖性的自我避免的基本问题。为了解决树突状产生的机制，我们利用了强大的细胞特异性分析方法来识别 PVD分支所需的保守的Lim-Homeodomain转录因子MEC-3。特定目标3将根据这些结果测试模型，即树突分支被稳定 与Claudin样蛋白和相邻表皮中其他特定细胞表面成分的相互作用。这些实验很重要，因为感觉神经元出生通常与表皮组织密切接触，但是在该位置进行树突状结构的细胞间机制的定义很差。秀丽隐杆线虫中的这项工作有望确定关键决定因素，这些决定因素也指定了人类神经系统中的树突状结构。