Motor neuron diversity: markers, regulatory mechanisms, and functional relevance.

毁灭性的运动神经元疾病肌萎缩侧索硬化症和脊髓性肌萎缩症引起运动神经元亚群的差异变性。人类拥有数百种运动神经元亚型，它们在形态、功能特性、基因表达模式、分子特征和连通性方面各不相同。关于如何识别/定义终末运动神经元亚型，以及为什么有些人比其他人更容易受到疾病过程的影响，人们知之甚少。本研究计划的目标是在秀丽隐杆线虫中使用一种独特的“自下而上”方法来确定产生运动神经元亚型的定义因素和调节机制，并了解运动神经元亚型多样性的功能重要性。这将通过研究秀丽隐杆线虫腹侧神经索中的一种胆碱能运动神经元亚型，即AS运动神经元，以及unc-55在指定AS亚型命运中的潜在作用来实现。利用秀丽隐杆线虫和基因调控分析，将鉴定出分子上相互区分亚型的新因子，并确定unc-55在调节这些因子中的作用。接下来，一种候选方法和无偏正向遗传筛选将利用人工和自动遗传筛选技术在秀丽隐杆线虫中定义unc-55在AS运动神经元中的调控。最后，AS运动神经元的功能重要性将通过结合光消融、光神经元活动监测、AS运动神经元的光遗传操作和光自由行为蠕虫的先进跟踪和成像来定义。该建议将定义AS运动神经元的规格和功能，但也广泛地解决产生运动神经元亚型的机制。揭示识别、调节和维持运动神经元亚型的分子机制与运动神经元变性特别相关，并可能为运动神经元相关疾病的发病机制、疾病诊断和治疗提供新的靶点。

DESCRIPTION (provided by applicant): Summary The devastating motor neuron diseases Amyotrophic Lateral Sclerosis and Spinal Muscular Atrophy cause differential degeneration of subsets of motor neurons. Humans possess hundreds of subtypes of motor neurons that differ in morphology, functional properties, gene expression patterns, molecular signatures, and connectivity. Little is known about how to identify/define terminal motor neuron subtypes or why some are more susceptible to disease processes than others. The goal of this research proposal is use a unique 'bottom-up' approach in C. elegans to identify defining factors and regulatory mechanisms for generating motor neuron subtypes and to understand the functional importance of motor neuron subtype diversity. This will be achieved by studying one cholinergic motor neuron subtype in the C. elegans ventral nerve cord, the AS motor neurons, and the potential role for unc-55 in specifying AS subtype fate. Using C. elegans and analysis of gene regulation, novel factors that molecularly define subtypes from one another will be identified, and the role for unc-55 in regulating these factors will be determined. Next, a candidate approach and an unbiased forward genetic screen will define the regulation of unc-55 in AS motor neurons, utilizing both manual and automated genetic screening techniques in C. elegans. Lastly, the functional importance of the AS motor neurons will be defined by combining optical ablation, optical neuronal activity monitoring, and optogenetic manipulation of AS motor neurons with advanced worm tracking and imaging in freely behaving worms. This proposal will define the specification and function of AS motor neurons, but also broadly address the mechanisms for generating motor neuron subtypes. Unraveling the molecular mechanisms that identify, regulate, and maintain motor neuron subtypes are particularly relevant to motor neuron degeneration, and may provide novel targets for pathogenesis, disease diagnosis, and therapeutics for motor neuron related diseases.