Molecular Mechanisms of Motor Neuron Development

这项建议的主要目的是了解运动神经元的分子机制。 区分和规范。维甲酸(RA)信号是神经源性和运动性同步所必需的 脊髓运动神经元分化过程中的神经元指定通路，这些事件是由 RA反应基因GDE2。GDE2编码一个六跨膜蛋白和一个胞外蛋白 甘油磷酸二酯磷酸二酯酶(GDPD)结构域。GDPD活性是GDE2的S能力所必需的 协调细胞周期退出和运动神经元规范，揭示GDPD代谢之间的新联系 运动神经元分化。GDE2的独特拓扑结构，其中GDPD结构域是细胞外的 而功能先例的缺乏有力地预测了新的分子网络的发现 运动神经元分化。为了识别这样的网络，使用无偏筛来分离 与GDE2互动。鉴定了两条不同信号通路的组成。在这项建议中，在体外 结构-功能分析将与体内功能丧失和获得研究相结合，以研究 这些信号通路如何与GDE2结合促进运动神经元分化。当开始的时候 GDE2在分化中的细胞中表达，在终末分化的细胞中保持表达 运动神经元；提示GDE2可能对后来的运动神经元功能或 生死存亡。为了确定GDE2在运动神经元发育的不同阶段的功能，小鼠遗传学 将用于在分化和有丝分裂后运动神经元中消融GDE2。由此产生的胚胎将是 运动神经元分化、运动神经元规格、运动轴突靶向缺陷分析 识别和运动神经元存活。 这些实验将发现与GDE2依赖的机制协同的新途径 运动神经元分化及GDE2在运动神经元不同发育阶段的功能定位 发展。因此，它们将提供对基本运动神经元生物学的更好理解，并将 拓展运动神经元病的潜在治疗靶点。鉴于这些研究也提供了洞察力 研究细胞分化机制，它们将进一步有益于相关领域的研究，如癌症和 干细胞生物学。

The major goals of this proposal are to understand the molecular mechanisms of motor neuron differentiation and specification. Retinoid (RA) signals are necessary for synchronizing neurogenic and motor neuron specification pathways during spinal motor neuron differentiation, and these events are mediated by the RA-responsive gene, GDE2. GDE2 encodes a six transmembrane protein with an extracellular glycerophosphodiester phosphodiesterase (GDPD) domain. GDPD activity is required for GDE2's ability to coordinate cell-cycle exit and motor neuron specification, revealing a novel link between GDPD metabolism and motor neuron differentiation. The distinctive topology of GDE2 where the GDPD domain is extracellular and the lack of functional precedent strongly predicts the discovery of new molecular networks involved in motor neuron differentiation. To identify such networks, unbiased screens were used to isolate proteins that interact with GDE2. Components of two different signaling pathways were identified. In this proposal, in vitro structure-function analyses will be combined with in vivo loss- and gain- of function studies to investigate how these signaling pathways integrate with GDE2 to promote motor neuron differentiation. While onset of GDE2 expression occurs in differentiating cells, GDE2 expression is maintained in terminally differentiated motor neurons; suggesting that GDE2 may have additional roles critical for later motor neuron function or survival. To define the function of GDE2 at different stages of motor neuron development, mouse genetics will be used to ablate GDE2 in differentiating and postmitotic motor neurons. Resultant embryos will be analyzed for defects in motor neuron differentiation, motor neuron specification, motor axon target recognition and motor neuron survival. These experiments will discover new pathways that synergize with GDE2-dependent mechanisms of motor neuron differentiation and define the function of GDE2 at different stages of motor neuron development. Consequently, they will provide a better understanding of basic motor neuron biology, and will expand potential therapeutic targets for motor neuron diseases. Given that these studies also provide insight into cellular differentiation mechanisms, they will further benefit related areas of study such as cancer and stem cell biology.