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严格控制的细胞相互作用，这些相互作用最终导致传入的感觉传入对特定运动神经元树突的识别。新的证据表明，感觉和运动神经元的功能子集表达的转录因子指导选择性的发育 感觉-运动连接。一个重要的未解决问题是控制运动和感觉轴突生长和连接的转录因子的相关靶标的身份。该提案的主要目标是确定脊髓运动和感觉神经元身份的转录调节与控制该神经回路中轴突生长和目标特异性的关键细胞表面识别分子之间的联系。将讨论运动和感觉神经元发育的三个具体方面。 位于外侧运动柱内的运动神经元在 LIM 同源域转录因子的控制下，沿着肢体的背腹轴差异性地投射轴突。我们将利用小鼠遗传学方法探索LIM同源域蛋白通过调节运动轴突和肢体间充质细胞上Eph激酶和肝配蛋白的表达来指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，遗传学研究表明 ETS 基因调节运动神经元中的信号蛋白表达。我们将使用小鼠遗传学方法来绘制特定信号蛋白及其主要受体丛蛋白在运动和感觉神经元分化中的分布图并分析其功能，重点关注这些基因在感觉轴突生长和连接中的功能。 识别 LIM 同源域和 ETS 基因相关靶标的一个困难是从小鼠胚胎中获得的初级神经元数量有限。为了克服这个问题，我们将利用小鼠 ES 细胞产生基本上无限数量的运动神经元的能力，并且发现 ES 细胞衍生的运动神经元缺乏许多调节运动轴突生长和连接的 LIM 同源域和 ETS 蛋白的表达。 因此，ES细胞衍生的运动神经元将被用作基于DNA的微阵列筛选的细胞系统，以定义和研究由这些转录因子激活或抑制的其他靶基因的功能。