LIM-HD/bHLH Combinatorial Code in Motoneurons

运动神经元中的 LIM-HD/bHLH 组合代码

• 批准号: 7576920
• 负责人: Soo-Kyung Lee
• 金额: $ 41.17万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-04-01 至 2011-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7576920
• 关键词: BHLH Protein; Binding; Binding Sites; Biochemical; Boxing; Cells; Code; DNA; Disease; Embryo; Gene Expression; Gene Targeting; Genes; Genomics; Goals; Heart; Helix-Turn-Helix Motifs; Interneurons; Knowledge; LIM Domain; Link; Mediating; Methods; Molecular; Molecular Genetics; Motor Neurons; Mus; Nervous system structure; Neuraxis; Neuroglia; Neuronal Injury; Neurons; Nodal; Nuclear; Organ; Pancreas; Pituitary Gland; Play; Property; Prosencephalon; Retina; Role; Screening procedure; Specific qualifier value; Spinal; Spinal Cord; System; Testing; To specify; base; cell type; cofactor; combinatorial; homeodomain; insight; novel; response; transcription factor; yeast genetics

Our long-term goal is to understand the combinatorial transcriptional regulatory networks in the developing central nervous system (CMS), which play essential roles to specify a large number of distinct neuronal and glial cell types. LIM homeodomain (LIM-HD) and basic helix-loop-helix (bHLH) proteins are relatively well characterized transcription factors regulating cell type specification in the embryonic CMS. However, both the molecular mechanism by which these factors regulate gene expression and the identity of their target genes remain poorly understood. We wish to explore these important issues by specifically focusing on their role in generating spinal motoneurons (MNs). Our results demonstrate that LIM-HD factors Lhx3 and Isl1specify two distinct neurons of the embryonic spinal cord in a combinatorial manner. Lhx3 and the LIM cofactor NLI(for nuclear LIM-interactor) form a V2-interneuron (IN)-specifying tetramer. In contrast, Lhx3 and NLI form a MN-specifying hexamerwhen coexpressed with Isl1. During MN specification, bHLH proteins Ngn2/NeuroM are functionally synchronized with the hexamer, although the molecular mechanism underlying this novel crosstalk is not fully understood. Our recent screening effort led to the finding of genomic fragments with the NLI:lsl1 :Lhx3 hexamer binding sites, many of which are linked to candidate MN genes. These results led to our central hypothesis of this proposal: the hexamer directly regulates multiple MNgenes in conjunction with bHLH factors to effect MN specification. We will dissect this hypothesis to uncover the molecular basis that directs MN specification in response to a combinatorial expression of transcription factors. Specifically, studies are proposed to explore the diverse functional aspects of the hexamer/bHLHs with their candidate target genes. Overall, the proposed studies should provide critical insights into the basic principles for the proper formation of the nervous system and practical information to treat a variety of neuronal injuries and diseases. Of note, LIM-HD/bHLH factors are also involved with specifying cell fates in other regions of the developing CNS (e.g., retina and forebrain) as well as non-CNS organs such as heart, pancreas and pituitary, which highlights the general importance of the proposed studies.

我们的长期目标是了解开发中的组合转录调节网络 中枢神经系统（CMS），它们在指定大量不同的神经元和 神经胶质细胞类型。 Lim同源域（LIM-HD）和基本螺旋环螺旋（BHLH）蛋白相对较好 调节胚胎CMS中细胞类型规范的转录因子的表征。但是，两个 这些因素调节基因表达及其靶基因的身份的分子机制 保持不当理解。我们希望通过专门关注它们在 产生脊柱运动神经元（MNS）。我们的结果表明，LIM-HD因子LHX3和ISL1Spectify 胚胎脊髓的两个不同的神经元以组合方式。 LHX3和Lim cofactor nli（用于 核liminteractor）形成v2-Interneuron（in）指定四聚体。相反，LHX3和NLI形成A 与ISL1共表达的Mn指定六聚体。在MN规范期间，BHLH蛋白NGN2/NEUROM 在功能上与六聚体同步，尽管该小说的分子机制 串扰尚未完全理解。我们最近的筛选工作导致发现了基因组碎片 NLI：LSL1：LHX3六聚体结合位点，其中许多与候选MN基因有关。这些结果导致了我们 该提议的中心假设：六聚体直接调节多个MNGENES与BHLH 影响MN规范的因素。我们将剖析这一假设，以发现指导的分子基础 MN规范响应转录因子的组合表达。具体而言，研究是 提议探索六聚体/BHLHS及其候选靶基因的各种功能方面。 总体而言，拟议的研究应提供对正确形成的基本原理的重要见解 神经系统和实际信息，以治疗各种神经元损伤和疾病。值得注意的是， LIM-HD/BHLH因子还与开发中枢神经系统的其他区域指定细胞命运有关（例如， 视网膜和前脑）以及心脏，胰腺和垂体等非CNS器官，突出显示 拟议研究的一般重要性。