Disruption of spinal circuit early development after silencing En1/Foxp2 interneurons

沉默 En1/Foxp2 中间神经元后脊髓回路早期发育中断

• 批准号: 10752857
• 负责人: FRANCISCO J ALVAREZ
• 金额: $ 43.04万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10752857
• 关键词: Acute; Adult; Affect; Anatomy; Ataxia; Automobile Driving; Birth; Brain Stem; Cell physiology; Central Nervous System; Cerebellum; Chemical Synapse; Chlorides; Chronic; Cochlea; Coupling; Development; Electrical Synapse; Electrophysiology (science); Elements; Embryo; Embryonic Development; Environmental Risk Factor; Etiology; Extensor; FOXP2 gene; Fetal Alcohol Spectrum Disorder; Fetal Alcohol Syndrome; Flexor; Functional disorder; Future; Generations; Genetic; Genetic Models; Glycine; Hippocampus; Interneurons; Intervention; Joints; Knowledge; Left; Limb structure; Literature; Maps; Modeling; Motor; Motor Activity; Motor Neurons; Motor output; Mus; Neurodevelopmental Disorder; Neurons; Newborn Infant; Participant; Pathologic; Pattern; Periodicity; Play; Preparation; Regulation; Renshaw Cell; Resources; Retina; Role; Sensory; Shapes; Spinal; Spinal Cord; Study models; Synapses; Syndrome; Testing; Tetanus Toxin; Time; Ventral Roots; Vertebral column; Viral; Visual Pathways; Work; autism spectrum disorder; axon guidance; connectome; experimental study; extracellular; forkhead protein; gamma-Aminobutyric Acid; imprint; limb movement; malformation; motor deficit; neural circuit; neural network; neurodevelopment; neuroinflammation; nicotine exposure; patch clamp; pharmacologic; pup; retinotopic; stem; synaptic inhibition; transcription factor; voltage

ABSTRACT Rhythmic spontaneous activity episodes, known as spontaneous network activity (SNA), occur throughout the central nervous system (CNS) at the time in which the first synaptic connections are established. During this time an early connectome is form and it is through later maturation and refinement of these early connections that adult synaptic circuitries with mature functionalities emerge. Therefore, the early development of this first connectivity is critical for later adult functional networks and when genetic or environmental factors disrupt SNA the resulting adult circuits are malformed and dysfunctional. For example, SNA mechanisms are disturbed in fetal alcohol spectrum disorders resulting in anomalous circuit development in the hippocampus. Similarly, many neurodevelopmental disorders like those in the autism spectrum display associated motor deficits in the newborn. SNA has been intensely studied in some CNS regions (retina, visual pathways, hippocampus) and the exact cellular interactions involved, the assembly and disassembly of the SNA network and its significance for maturation of correctly connected adult circuits are well known. Surprisingly, less is known about SNA in spinal cord motor circuits, despite this being an early model for the study of SNA mechanisms. Currently, the literature offers contradictory conclusions on the exact types of neurons involved in the SNA spinal network and the significance of SNA for spinal circuit development remains unexplored. These are critical gaps in our knowledge given the large number of motor syndromes in newborns with unknown etiology. This exploratory proposal stems from the serendipitous finding of profound ataxia and limb discoordination in mouse pups in which spinal inhibitory interneurons expressing the transcription factors engrailed 1 (En1) and forkhead box P2 (Foxp2) were chronically silenced throughout embryonic development. This suggests major dysfunction in adult spinal motor circuits controlling limbs and preliminary results suggest disruption of early SNA in the embryo. This genetic model could therefore offer a new entry point to interrogate cellular mechanisms in the network driving SNA in the spinal cord (Aim 1) and the consequences of SNA dysfunction for the later organization of key spinal motor circuits (Aim 2). For the second aim we will use as model the most basic of motor circuits composed by extensor and flexor motoneurons, Ia reciprocal inhibitory interneurons (many of which are En1-Foxp2) and Renshaw cells. This circuit displays a well-defined organization of specific connections that has been extensively studied for many years and therefore offers an unambiguous model to test the role of SNA in establishing specific connectivity. We hypothesize that its basic organization will be disrupted by anomalous early SNA given that the principal interneurons involved in the SNA network (Renshaw cells and Ia inhibitory interneurons) are also participants in this adult circuit. We hope to generate first evidence for the usefulness of this model, and this could lead to future proposals focusing on more thorough analyses of cellular mechanisms to better understand possible origins of some newborn motor syndromes.

抽象的 有节律的自发活动发作，称为自发网络活动（SNA），发生在整个 中枢神经系统（CNS）在建立第一个突触连接时。在此期间 早期连接体形成的时间是通过这些早期连接的后期成熟和完善而形成的 具有成熟功能的成人突触回路出现。因此，这第一个早期开发 连接对于成年后的功能网络以及遗传或环境因素破坏 SNA 时至关重要 由此产生的成人回路畸形且功能失调。例如，SNA 机制在以下方面受到干扰： 胎儿酒精谱系障碍导致海马体回路发育异常。相似地， 许多神经发育障碍，如自闭症谱系障碍，都表现出相关的运动缺陷 新生。 SNA 已在一些中枢神经系统区域（视网膜、视觉通路、海马体）进行了深入研究， 所涉及的确切细胞相互作用、SNA 网络的组装和分解及其意义 正确连接的成人电路的成熟是众所周知的。令人惊讶的是，人们对 SNA 知之甚少。 脊髓运动回路，尽管这是研究​​ SNA 机制的早期模型。目前， 文献对 SNA 脊髓网络中神经元的确切类型提供了相互矛盾的结论 SNA 对于脊髓回路发育的重要性仍有待探索。这些是我们的关键差距 鉴于新生儿中存在大量病因不明的运动综合征。这种探索性的 该提议源于在小鼠幼崽中偶然发现的严重共济失调和肢体不协调 哪些脊髓抑制性中间神经元表达转录因子 engrailed 1 (En1) 和叉头盒 P2 (Foxp2) 在整个胚胎发育过程中长期沉默。这表明主要功能障碍 成人脊髓运动回路控制四肢，初步结果表明早期 SNA 受到破坏 胚胎。因此，这种遗传模型可以为研究细胞机制提供一个新的切入点。 网络驱动脊髓中的 SNA（目标 1）以及 SNA 功能障碍对后来的后果 关键脊髓运动回路的组织（目标 2）。对于第二个目标，我们将使用最基本的模型作为模型 运动回路由伸肌和屈肌运动神经元组成，Ia 相互抑制性中间神经元（许多 它们是 En1-Foxp2) 和 Renshaw 细胞。该电路显示了特定的明确定义的组织 多年来已被广泛研究的连接，因此提供了一个明确的模型 测试 SNA 在建立特定连接方面的作用。我们假设它的基本组织是 鉴于 SNA 网络中涉及的主要中间神经元（Renshaw 细胞和 Ia 抑制性中间神经元）也是这个成人回路的参与者。我们希望产生第一个证据 对于这个模型的实用性，这可能会导致未来的提案侧重于更彻底的分析 细胞机制，以更好地了解某些新生儿运动综合症的可能起源。