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).

在后生中枢神经系统（CNS）发育期间，神经前体细胞经历了多发的不对称细胞分裂，产生每种分裂的神经元或神经胶质祖细胞。这些独特命名的神经细胞的形成是基础的基因表达调节网络，这些网络建立了不同的功能性细胞同一性。该项目的目的是识别和表征转录因子顺式调节网络，以控制开发中枢神经系统中的细胞身份决策。尽管对导致神经前体细胞形成的早期发育决策知之甚少，但几乎没有什么理解的关于产生神经元或神经胶质的独特功能身份的细胞命运决策。这些细胞命运决定的分子和途径/电路的鉴定和功能表征仍然是神经生物学的核心目标。我们已经发现，在发展中的果蝇中枢神经系统中，神经前体细胞最多，在其不对称分裂过程中通过一系列同步基因表达程序过渡。这些基因表达的时间窗口以不同的转录因子的顺​​序表达为标志，这些表达又有助于建立独特的神经细胞类型。我们的研究表明，时间域是全球中枢神经系统调节网络的一部分，该网络可以协调发育中的胚胎大脑和腹部绳索中细胞命运确定的事件。这些研究还表明，当分离培养时，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，一旦开始神经谱系的发展，干细胞或相邻组织之间就无需其他信号线索来触发这种调节基因表达的级联。 我们实验室的最新研究确定了在神经前体细胞谱系发育的不同时间窗口中控制特定转录因子基因表达的顺式调节增强剂。 我们对这些增强子的进化比较DNA序列分析表明，它们包含保守的DNA序列块簇，其中许多不变序列包含用于转录因子的DNA结合位点。 控制最早表达的细胞认同决定因素之一，Zn手指nerfin-1转录因子以及调节后期表达细胞测定剂，Zn手指基因astor的功能分析，以及调节Zn手指的晚期表达的增强剂，表明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剂控制的，并且是多个独立增强剂的控制性的，并且它们在多个独立的表达中受到了控制。 使用我们开发的一套新的比较基因组学工具（在随附的项目识别中描述了与功能相关的果蝇调节DNA NS009413-02），我们根据具有Nerfin-1增强剂的共享保守序列确定了其他早期神经前体增强剂。我们还使用了这些比较基因组工具来识别蓖麻转录因子中包含高度保守的DNA结合位点的潜在蓖麻调节增强子。 我们目前正在追求这些增强剂的表征，以确定在不同的突变转录因子背景中其顺式调节行为是否改变。 可以在我们的网站（http://intra.ninds.nih.gov/investigators.asp）上获得描述这项工作的其他信息和出版物。