LIM-HD/bHLH Combinatorial Code in Motoneurons

项目总结 我们的长期目标是定义基因网络，使神经干细胞产生显著的分化 中枢神经系统发育中的细胞类型。转录因子的组合作用是一种流行的策略 在中枢神经系统中实现细胞复杂性。然而，转录的组合作用的机制 控制特定细胞特性的一组独特的末端分化基因表达的因素 在脊椎动物的中枢神经系统中仍不清楚。在这项建议中，我们希望通过关注 脊髓运动神经元规范的基因网络，其中发育的转录密码 是相对较好的理解。LIM同源结构域蛋白Lhx3和Isl1调节运动神经元的特性 通过形成一个六聚体复合体来结合，称为MN-六聚体。 这一提议的关键假设是MN-六角体直接控制一组控制 MN特性的广泛方面，包括胆碱能神经传递，通过协调 脊髓发育过程中的视黄醇信号和染色质修饰酶。我们将对此进行测试 利用分子和生化方法的集合假说，基因工程胚胎干细胞 细胞、鸡胚胎和突变小鼠。提出了三个具体的目标来剖析假设：1)定义 指定MN同一性的MN-六角体的靶基因。2)探讨胆碱能神经的调节作用 脊髓运动神经元和前脑胆碱能神经元中类似六聚体复合体的神经元识别。3) 明确RA在促进MN-六聚体MN规范中的作用。 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 为研究基因网络在中枢神经系统期间创造惊人的细胞多样性奠定基础框架 发展。这些研究还应该为开发脊柱的治疗策略提供新的工具。 脊髓损伤和与运动功能受损有关的疾病，如肌萎缩侧索硬化症(Lou Gehrig�S病)，以及 由前脑胆碱能神经元丧失引起的认知障碍，如阿尔茨海默病、�S病等。

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.