Analysis of Neural Precursor Cell cis-Regulatory Enhancers

神经前体细胞顺式调节增强剂的分析

• 批准号: 8557009
• 负责人: WARD F ODENWALD
• 金额: $ 76.24万
• 依托单位: NATIONAL INSTITUTE OF NEUROLOGICAL DISORDERS AND STROKE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8557009
• 关键词: Behavior; Binding Sites; Brain; Castor; Cell Lineage; Cell division; Cells; Conserved Sequence; Cues; DNA; DNA Binding; DNA Sequence; DNA Sequence Analysis; Development; Drosophila genus; Embryo; Enhancers; Event; Fingers; Gene Expression; Generations; Genes; Goals; Nervous System Physiology; Nervous system structure; Neuraxis; Neurobiology; Neuroglia; Neurons; Pathway interactions; Pattern; Publications; Regulator Genes; Research Personnel; Series; Signal Transduction; Stem cells; Tissues; Transcription factor genes; Work; base; cell type; comparative; comparative genomics; mutant; nerfin 1; nerve stem cell; nervous system development; neural precursor cell; programs; relating to nervous system; tool; transcription factor; web site

During metazoan central nervous system (CNS) development, neural precursor cells undergo multiple rounds of asymmetric cell divisions producing either neuronal or glial progenitor cells with each division. Underpinning the formation of these uniquely fated neural cells are integrated gene expression regulatory networks that establish distinct functional cellular identities. The objective of this project is to identify and characterize transcription factor cis-regulatory networks controlling cell-identity decisions in the developing CNS. Although much is known about early developmental decision leading to the formation of neural precursor cells, little is understood about subsequent cell fate decisions that generate the unique functional identities of neurons or glia. The identification and functional characterization of the molecules and pathways/circuits underlying these cell-fate decisions remain a central goal of neurobiology. We have discovered that in the developing Drosophila CNS most, if not all, neural precursor cells transition through a series of synchronized gene expression programs during their asymmetric divisions. These temporal windows of gene expression are marked by the sequential expression of different transcription factors that, in turn help establish unique neural cell types. Our studies have revealed that the temporal domains are part of a global CNS regulatory network that coordinates cell fate-determining events in both the developing embryonic brain and in the ventral cord. These studies have also demonstrated that when cultured in isolation, Drosophila neural precursor cells maintain the correct temporal shifts in transcription factor gene expression. This cellular independence provides evidence that once neural lineage development is initiated no additional signaling cues between stem cells or adjacent tissues are required to trigger this cascade of regulatory gene expression. More recent studies from our lab have identified the cis-regulatory enhancers that control the expression of specific transcription factor genes during different temporal windows of neural precursor cell lineage development. Our evolutionary comparative DNA sequence analysis of these enhancers have revealed that they contain clusters of conserved DNA sequence blocks and many of these genus invariant sequences contain DNA-binding sites for transcription factors. Functional analysis of the conserved cis-regulatory DNA that controls one of the earliest expressed cell-identity determinants, the Zn-finger Nerfin-1 transcription factor, and the enhancers that regulates a late expressing cell-determinant, the Zn-finger gene castor, reveals that their dynamic expression in the developing nervous system is controlled by multiple independent enhancers that regulate different aspects of their spatial and temporal expression patterns. Using a new set of comparative genomics tools that we have developed (described in our accompanying project Identification of Functionally Related Drosophila cis-Regulatory DNA NS009413-02) we have identified additional early neural precursor enhancers based on their shared conserved sequences with nerfin-1 enhancer. We have also used these comparative genomic tools to identify potential Castor regulated enhancers that contain highly conserved DNA-binding sites for the Castor transcription factor. We are currently pursuing the characterization of these enhancers to determine if their cis-regulatory behavior is altered in different mutant transcription factor backgrounds. Additional information and publications describing this work can be obtained at our web site (http://intra.ninds.nih.gov/investigators.asp).

在后生动物中枢神经系统（CNS）发育过程中，神经前体细胞经历多轮不对称细胞分裂，每次分裂产生神经元或神经胶质祖细胞。整合的基因表达调控网络支撑着这些独特命运的神经细胞的形成，这些网络建立了独特的功能细胞身份。该项目的目标是识别和表征控制发育中中枢神经系统细胞身份决策的转录因子顺式调控网络。尽管人们对导致神经前体细胞形成的早期发育决策了解甚多，但对产生神经元或神经胶质细胞独特功能特性的后续细胞命运决策却知之甚少。这些细胞命运决定背后的分子和通路/回路的识别和功能表征仍然是神经生物学的中心目标。我们发现，在发育中的果蝇中枢神经系统中，大多数（如果不是全部）神经前体细胞在其不对称分裂期间通过一系列同步基因表达程序进行转变。这些基因表达的时间窗口以不同转录因子的顺​​序表达为标志，这反过来又有助于建立独特的神经细胞类型。我们的研究表明，颞区是全球中枢神经系统调节网络的一部分，该网络协调发育中的胚胎大脑和腹索中的细胞命运决定事件。这些研究还表明，当单独培养时，果蝇神经前体细胞保持转录因子基因表达的正确时间变化。这种细胞独立性提供了证据，表明一旦神经谱系发育开始，干细胞或邻近组织之间不需要额外的信号线索来触发这种级联调节基因表达。 我们实验室最近的研究发现了顺式调节增强子，它们在神经前体细胞谱系发育的不同时间窗口期间控制特定转录因子基因的表达。 我们对这些增强子的进化比较 DNA 序列分析表明，它们含有保守 DNA 序列块簇，并且许多属不变序列含有转录因子的 DNA 结合位点。 对控制最早表达的细胞身份决定因素之一——锌指 Nerfin-1 转录因子的保守顺式调控 DNA 和调节晚期表达细胞决定因素——锌指基因蓖麻的增强子进行功能分析，揭示它们在发育中的神经系统中的动态表达是由多个独立的增强子控制的，这些增强子调节它们的空间和时间表达模式的不同方面。 使用我们开发的一套新的比较基因组学工具（在我们的附带项目功能相关果蝇顺式调节 DNA NS009413-02 的鉴定中进行了描述），我们根据与 nerfin-1 增强子共享的保守序列鉴定了其他早期神经前体增强子。我们还使用这些比较基因组工具来鉴定潜在的 Castor 调节增强子，这些增强子含有高度保守的 Castor 转录因子 DNA 结合位点。 我们目前正在研究这些增强子的表征，以确定它们的顺式调控行为是否在不同突变转录因子背景下发生改变。 描述这项工作的更多信息和出版物可以在我们的网站 (http://intra.ninds.nih.gov/investigators.asp) 上获得。