Hox genes in the development of respiratory circuits

描述（由候选人提供）：哺乳动物呼吸是依赖膈肌收缩的重要运动行为。呼吸运动的频率和幅度是由脑干和脊髓中的神经网络控制的。这些网络的退化导致呼吸系统疾病，如中枢性睡眠呼吸暂停，并最终导致呼吸衰竭。我的长期目标是揭示呼吸回路组装的基本原理，这样我们就可以开始考虑呼吸功能障碍的替代治疗方法。呼吸神经网络研究中的一个难题是，尽管在脑干节律性回路的定义方面取得了重大进展，但脊髓呼吸神经元的发育起源、分子身份和连通性仍然未知。总的来说，提出的研究旨在确定脊柱呼吸网络组装背后的遗传和分子途径。我们最近证明，支配膈肌的颈脊髓膈运动柱（PMC）神经元的发育需要Hox5基因的持续活动。运动神经元（MNs）缺乏Hox5基因的小鼠在出生时死于呼吸衰竭，并在PMC身份的多个方面表现出缺陷，包括聚类、轴突引导和膈神经支配。在本奖项的指导部分，将进一步探讨Hox5基因在PMC MNs中的作用。将进行差异基因表达分析，以鉴定Hox5蛋白下游的基因，以调节PMC发育的不同方面（目的1）。此外，将采用基于跨突触病毒的追踪方法来研究从MNs中去除Hox5如何影响PMC的运动前输入的建立（Aim 2）。在独立阶段，将研究Hox基因及其下游靶标在脊髓呼吸中间神经元发育和连接中的作用（Aim 3）。解决这个问题将严重依赖于遗传方法，跨突触回路标记技术和生理呼吸测定，其中的专业知识将在K99阶段获得。该研究的指导部分将在纽约大学医学中心的Dasen和Fishell实验室进行，这是一个出色的研究环境，将提供拟议实验所需的所有设备和设施。此外，拉瓦尔大学的Kinkead博士将担任顾问，并提供容积脉搏描记技术方面的培训。我已经成立了一个委员会，他们将监督我的进展，并在奖项的指导部分提供技术和智力上的投入。我之前在分子神经科学方面的经验，加上严格的培训计划，将确保我成功完成所提出的研究目标，而K99阶段的职业发展活动将有助于我顺利过渡到一个独立的职位。

DESCRIPTION (provided by candidate): Breathing is a vital motor behavior that relies on diaphragm muscle contractions in mammals. The frequency and amplitude of breathing movements is controlled by neural networks residing in the brainstem and spinal cord. Degeneration of these networks leads to respiratory disorders, such as central sleep apneas, and, eventually, respiratory failure. My long term goal is to uncover the basic principles underlying respiratory circuit assembly so that we can begin to consider alternative treatment methods for respiratory dysfunction. A conundrum in the study of respiratory neural networks is that while significant progress has been made in defining the rhythmogenic circuits in the brain stem, the developmental origins, molecular identity and connectivity of spinal cord respiratory neurons remain unknown. Overall, the proposed research aims to define the genetic and molecular pathways that underlie spinal respiratory network assembly. We have recently demonstrated that the development of phrenic motor column (PMC) neurons in the cervical spinal cord, which innervate the diaphragm, requires the sustained activity of Hox5 genes. Mice lacking Hox5 genes in motor neurons (MNs) die of respiratory failure at birth and exhibit defects in multiple aspects of PMC identity, including clustering, axon guidance and diaphragm innervation. During the mentored part of this award, the role of Hox5 genes in PMC MNs will be further explored. Differential gene expression analysis will be carried out in order to identify genes acting downstream of Hox5 proteins to regulate distinct aspects of PMC development (Aim 1). Additionally, transsynaptic virus-based tracing approaches will be implored to examine how Hox5 removal from MNs affects the establishment of premotor inputs to the PMC (Aim 2). During the independent phase of the award, the role of Hox genes and their downstream targets in spinal cord respiratory interneuron development and connectivity will be examined (Aim 3). Addressing this question will rely heavily on genetic approaches, transsynaptic circuit labeling techniques and physiological respiratory assays, in which expertise will be acquired during the K99 phase. The mentored part of the research will be performed at the Dasen and Fishell labs at NYU Medical Center, an outstanding research environment that will provide all the equipment and facilities required for the proposed experiments. In addition, Dr. Kinkead at Laval University will act as a consultant and will provide training in the technique of plethysmography. I have assembled a committee who will oversee my progress and provide technical and intellectual input during the mentored part of the award. My previous experience in molecular neuroscience, in combination with a rigorous training plan, will ensure the successful completion of the proposed research aims, while the career development activities during the K99 phase of the award will facilitate a smooth transition to an independent position.