LIM-HD/bHLH Combinatorial Code in Motoneurons

项目摘要 我们的长期目标是定义基因网络，使神经干细胞能够产生显著不同的 CNS发育中的细胞类型。转录因子的组合作用是一种普遍的策略， 实现CNS中的细胞复杂性。然而，转录的组合作用的潜在机制 控制特定细胞特性的一组独特终末分化基因表达的因子 在脊椎动物中枢神经系统中仍不清楚。在本提案中，我们希望通过侧重于以下方面来解决这一重要问题： 脊髓运动神经元特异性的基因网络，其中发育转录编码 相对来说是很好理解的。LIM同源结构域蛋白Lhx 3和Isl 1调节运动神经元特化， 通过形成称为MN-六聚体的六聚体复合物进行组合。 这个提议的关键假设是MN-六聚体直接控制一组基因， MN身份的广泛方面，包括胆碱能神经传递，通过协调行动， 脊髓发育过程中类维生素A信号和染色质修饰酶。我们将测试这个 利用分子和生物化学方法，基因工程胚胎干细胞 细胞、鸡胚和突变小鼠。提出了三个具体目标来剖析该假设; 1）定义 MN-六聚体的指定MN身份的靶基因。2)探讨胆碱能神经的调节 在脊髓运动神经元和前脑胆碱能神经元中通过类似的六聚体复合物确定神经元身份。第三章 明确RA在MN六聚体介导MN特异化中的作用。 除了对运动神经元和运动回路的产生提供重要的见解外，我们的研究还将 奠定了研究基因网络的基本框架，在CNS过程中创造了惊人的细胞多样性 发展这些研究还应该为制定脊髓损伤的治疗策略提供新的工具。 脊髓损伤和与运动功能受损相关的疾病，如ALS（Lou Gehrig病）， 前脑胆碱能神经元缺失导致的认知障碍，如阿尔茨海默病。

PROJECT SUMMARY Our long-term goal is to define gene networks that enable neural stem cells to produce remarkably divergent cell types in CNS development. The combinatorial action of transcription factors is a prevalent strategy to achieve cellular complexity in CNS. However, the mechanisms underlying combinatorial action of transcription factors in controlling the expression of unique set of terminal differentiation genes for a specific cellular identity remain unclear in vertebrate CNS. In this proposal, we wish to tackle this important issue by focusing on the gene networks for the specification of spinal motor neurons, in which the developmental transcription codes are relatively well understood. LIM homeodomain proteins Lhx3 and Isl1 regulate motor neuron specification in combination by forming a hexameric complex, named MN-hexamer. The key hypothesis of this proposal is that MN-hexamer directly controls a battery of genes that control wide aspects of MN identity, including cholinergic neurotransmission, by coordinating the actions of retinoid signal and chromatin modifying enzymes during spinal cord development. We will test this hypothesis using an ensemble of molecular and biochemical methods, genetically engineered embryonic stem cells, chick embryos and mutant mice. Three specific aims are proposed to dissect the hypothesis; 1) To define the target genes of MN-hexamer that assign MN identity. 2) To investigate the regulation of cholinergic neuronal identity by similar hexameric complexes in spinal motor neurons and forebrain cholinergic neurons. 3) To define the role of RA in facilitating MN specification by MN-hexamer. Besides providing crucial insights into the generation of motor neurons and motor circuits, our studies will lay fundamental framework to study gene networks in creating the amazing cellular diversity during CNS development. These studies should also provide new tools for developing therapeutic strategies for the spinal cord injuries and diseases associated with impaired motor function, such as ALS (Lou Gehrig¿s disease), and the cognitive disorders resulting from the loss of forebrain cholinergic neurons, such as Alzheimer¿s diseases.