CELL INTERACTIONS IN MOTOR NEURON DIFFERENTIATION

运动神经元分化中的细胞相互作用

• 批准号: 6989621
• 负责人: Thomas M. Jessell
• 金额: $ 12.97万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-04-12 至 2008-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6989621
• 关键词: biological signal transduction; cell cell interaction; cell differentiation; developmental genetics; efferent nerve; embryonic stem cell; gene expression; gene mutation; genetically modified animals; laboratory mouse; limbs; mammalian embryology; microarray technology; motor neurons; neurogenesis; neuronal guidance; neurons; protein signal sequence; protein tyrosine kinase; protooncogene; receptor expression; spinal cord; transcription factor

The specificity of connections formed between proprioceptive sensory neurons and motor neurons in the developing spinal cord is dependent on a series of tightly controlled cellular interactions that culminate in the recognition of specific motor neuron dendrites by incoming sensory afferents. Emerging evidence indicates that transcription factors expressed by functional subsets of sensory and motor neurons direct the development of selective sensory-motor connections. One important unresolved issue is the identity of the relevant targets of the transcription factors that control motor and sensory axon growth and connectivity. The main goal of this proposal is to define the link between the transcriptional regulation of spinal motor and sensory neuron identity and the key cell surface recognition molecules that control axonal growth and target specificity in this neural circuit. Three specific aspects of motor and sensory neuron development will be addressed. Motor neurons located within lateral motor column project their axons differentially along the dorsoventral axis of the limb, under the control of LIM homeodomain transcription factors. We will use mouse genetic methods to explore the possibility that LIM homeodomain proteins direct motor axon guidance by regulating the expression of Eph kinases and ephrins on motor axons and limb mesenchymal cells. ETS class transcription factors regulate the trajectory and terminal axonal branching of both motor and sensory neurons, and genetic studies have revealed that ETS genes regulate semaphorin expression in motor neurons. We will use mouse genetic approaches to map the distribution, and analyze the function, of specific semaphorins and their major receptors, the plexins, in the differentiation of motor and sensory neurons, focusing on the function of these genes in sensory axonal growth and connectivity. One difficulty in identifying relevant targets of LIM homeodomain and ETS genes has been the limitation in number of primary neurons that can be obtained from mouse embryos. To overcome this problem, we will take advantage of the ability to generate motor neurons in essentially unlimited numbers from mouse ES cells, and the finding that ES cell-derived motor neurons lack expression of many of the LIM homeodomain and ETS proteins that regulate motor axonal growth and connectivity. ES cell derived motor neurons will therefore be used as a cellular system for DNA-based microarray screens to define and study the function of additional target genes that are activated or repressed by these transcription factors.

发育中的脊髓中本体感受的感觉神经元和运动神经元之间形成的连接的特异性取决于一系列紧密控制的细胞相互作用，这些相互作用通过传入的感觉传递物来识别特定运动神经元树突。新兴的证据表明，感官和运动神经元功能子集表达的转录因子指导选择性的发展 感觉运动连接。一个重要的未解决的问题是控制电动机和感觉轴突生长和连通性的转录因子的相关目标的身份。该提案的主要目标是定义脊柱运动和感觉神经元同一性的转录调控与控制轴突生长和靶向特异性的关键细胞表面识别分子之间的联系。运动和感觉神经元发育的三个具体方面将得到解决。 位于侧电动柱内的运动神经元在LIM同源域转录因子的控制下，沿肢体的背轴沿肢体的背轴差异地伸出轴突。我们将使用小鼠遗传学方法来探索LIM同源蛋白蛋白通过调节运动轴突和肢体间充质细胞上EPH激酶和ephrins的表达来引导运动轴突引导的可能性。 ETS类转录因子调节运动神经元和感觉神经元的轨迹和末端轴突分支，遗传研究表明，ETS基因调节运动神经元中的Semaphorin表达。我们将使用小鼠遗传方法来绘制特定信号素及其主要受体的分布，并分析运动和感觉神经元的分化，重点是这些基因在感觉轴突生长和连接性中的功能。 识别LIM同源域和ETS基因的相关靶标的一个困难是可以从小鼠胚胎获得的主要神经元数量的限制。为了克服这个问题，我们将利用从基本无限的小鼠ES细胞中产生运动神经元的能力，并且发现ES细胞衍生的运动神经元缺乏调节运动轴突生长和连接性的许多LIM同源域和ETS蛋白的发现。 因此，ES细胞衍生的运动神经元将用作基于DNA的微阵列筛选的细胞系统，以定义和研究这些转录因子激活或抑制的其他靶基因的功能。