Molecular Regulation of Corticospinal Motor Neuron Development

描述(申请人提供)：脊椎动物中枢神经系统(CNS)的发育是由复杂的遗传程序和细胞外部信号调控的，这些信号控制着神经前体细胞向成体中看到的各种神经元亚型的分化。虽然调控早期神经发生的一般方面的分子机制已经开始被阐明，但控制谱系特定的神经元命运决定和分化的机制在很大程度上仍然难以捉摸。特别是，调控哺乳动物新皮质复杂神经元异质性的分子遗传学程序才刚刚开始被发现。皮质脊髓运动神经元(CSMN)位于大脑皮层V层的众多神经元中，是阐明皮质神经元亚型发育的分子调控的典型和重要的临床谱系。最近，我们实验室的成员开发了从其他神经元和神经胶质亚型中纯化CSMN(和其他投射神经元谱系)的方法，用于微阵列分析，揭示了CSMN特化和分化过程中谱系特异性分子遗传控制的组合程序。这些研究确定了一些似乎是关键调控因素的候选基因(前四项研究中的每一项都是新发现的对CSMN发育的中央控制)。为了确定发育功能并更完整地了解这种典型的皮质神经元亚型是如何发展的，我提议研究选定的候选基因：1.CS3和CS4，这两个以前在前脑中未表现出特征的转录因子，将通过分析这两个蛋白质的功能缺失和功能获得表型以及功能相互作用来检测；2.将使用体内电穿孔和逆转录病毒转导介导的过表达和RNA干扰(RNAi)方法，通过系统的功能获得和丢失分析来检测一组非常有针对性的相关候选基因。总之，这些研究旨在描述CSMN发育的关键分子调控的功能、时间进程和组合作用，阐明中枢神经系统的谱系特征。这项工作也有重要的临床意义。投射神经元对疾病和损伤具有选择性易感性；CSMN易损性在与肌萎缩侧索硬化症(ALS)相关的运动神经元变性和脊髓损伤后运动功能丧失时尤为明显。了解形成CSMN的发育机制将是在中枢神经系统潜在地开发有效和持久的CSMN保护和修复的关键的第一步。这些进展也可能导致对其他易受疾病和损伤的神经元亚型的普遍研究和治疗方法。

DESCRIPTION (provided by applicant): The development of the vertebrate central nervous system (CNS) is orchestrated by complex genetic programs and cell extrinsic signals that govern the differentiation of neural progenitors into the rich variety of neuronal subtypes seen in the adult. While the molecular mechanisms that regulate general aspects of early neurogenesis have begun to be elucidated, the mechanisms controlling lineage-specific neuronal fate determination and differentiation remain largely elusive. In particular, the molecular-genetic programs that regulate the complex neuronal heterogeneity of the mammalian neocortex are only beginning to be discerned. Corticospinal motor neurons (CSMN), located among many other neuron types in layer V of the neocortex, are a prototypical and clinically important lineage for elucidating molecular regulation of cortical neuron subtype development. Recently, members of our laboratory developed approaches to purify CSMN (and other projection neuron lineages) from other neuronal and glial subtypes for microarray analysis, revealing a combinatorial program of lineage-specific molecular-genetic controls during CSMN specification and differentiation. These studies identified a number of candidate genes that appear to be critical regulators (each of the first four studied are newly identified central controls over CSMN development). In order to determine developmental functions and create a more complete picture of how this prototypical cortical neuronal subtype develops, I propose to investigate selected candidate genes: 1. cs3 and cs4, two transcription factors previously uncharacterized in the forebrain, will be examined via analysis of loss- and gain-of-function phenotypes as well as functional interactions of the two proteins; 2. A very focused set of related candidates will be examined via a systematic gain- and Ioss-of-function analysis using in vivo electroporation and retroviral transduction-mediated overexpression and RNA interference (RNAi) approaches. Together, these studies aim to characterize the functions, temporal courses, and combinatorial roles of key molecular controls over CSMN development, elucidating lineage specification in the CNS. Significant clinical implications to this work also exist. Projection neurons are selectively vulnerable to disease and injury; CSMN vulnerability is especially apparent in motor neuron degeneration associated with amyotrophic lateral sclerosis (ALS) and loss of motor function after spinal cord injury. Understanding the developmental mechanisms that build CSMN will be a key first step in potentially developing effective and long-lasting CSMN protection and repair in the CNS. These advancements might also lead to generalizable investigative and therapeutic approaches for other neuron subtypes vulnerable to disease and injury.