PATTERN FORMATION IN CHICK MIDBRAIN DEVELOPMENT

雏鸡中脑发育中的模式形成

• 批准号: 6825699
• 负责人: Clifton W. Ragsdale
• 金额: $ 24.2万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-08-01 至 2006-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6825699
• 关键词: bone morphogenetic proteins; brain mapping; cell differentiation; cell growth regulation; cell migration; cell population study; cell proliferation; chick embryo; developmental genetics; developmental neurobiology; electroporation; embryo /fetus protein; fluorescent dye /probe; gene expression; histochemistry /cytochemistry; in situ hybridization; intermolecular interaction; mesencephalon; nerve /myelin protein; neurogenesis; neurogenetics; neurons; neuroregulation; nonmammalian vertebrate embryology; protein structure function; transcription factor

DESCRIPTION (provided by applicant): The broad goal of this research is to understand the cellular and molecular mechanisms by which brain nuclei of the appropriate size, shape and neuronal cell-type constituency are generated during development. We study this problem in the midbrain, a principal division of the vertebrate brain. During the period of neurogenesis, the chick ventral midbrain is transiently organized into regularly spaced, longitudinal zones distinguished by morphology and histochemistry. Our hypothesis is that these zones, called midbrain arcs, are a patterning mechanism by which neurons are allocated to different nuclear fates. The aims of our research are (1) to test a prediction of this hypothesis, that the midbrain arcs differ in their fiber-connections, and (2) to discover the molecular mechanisms by which arcs are generated during midbrain development. In the initial funding period, we established that the most medial arc gives rise to two nuclear structures, the oculomotor complex and the red nucleus. We also demonstrated that a complete set of midbrain arcs could be elicited by an ectopic source of the morphogen Sonic Hedgehog (SHH). In the proposed experiments we will extend our test of the arcs-as-pronuclei hypothesis to lateral midbrain, and we will address whether a SHH source patterns the arcs directly, as a long-range morphogen, or acts in part through bone morphogenetic protein (BMP) intermediaries. The first set of experiments studies the anatomy of the lateral midbrain arcs with anterograde and retrograde tract-tracing methods. A finding of that the lateral arcs have characteristic neuronal connections would not only support the pronuclear hypothesis, but could serve to identify particular arcs as specific pronuclei. The second set of experiments tests the competency of SHH to specify midbrain arc cell-types directly, as a long-range morphogen. These experiments will be carried out in wild-type and talpid(2) mutant chick embryos using in ovo electroporation and explant tissue culture methods. Our finding that ectopic SHH induces BMP gene expression raises, however, the possibility that BMP2 and BMP7 may participate in long-range signaling by a SHH source. The third set of experiments tests the contributions of BMP signaling to midbrain arc patterning. The ventral midbrain is a frequent site of pathology in stroke and other neurological disorders. Understanding its developmental biology should facilitate research into therapeutics, including those based on tissue transplants. More generally, ventral midbrain development provides a model for understanding how brain nuclei form. Insight into these mechanisms may suggest novel approaches to neurological disorders due to nuclear ablations or disconnections.

描述（由申请人提供）：这项研究的总体目标是 了解大脑细胞核的细胞和分子机制 生成适当大小、形状和神经元细胞类型的选区 在开发过程中。我们在中脑（一个主要部门）中研究这个问题 脊椎动物的大脑。在神经发生期间，雏鸡腹侧 中脑短暂地组织成规则间隔的纵向区域 通过形态学和组织化学来区分。我们的假设是这些 称为中脑弧的区域是一种模式机制，神经元通过该机制 分配给不同的核命运。我们研究的目的是（1）测试 这一假设的预测，即中脑弧的不同之处在于 纤维连接，以及（2）发现电弧的分子机制 是在中脑发育过程中产生的。在初始融资期间，我们 确定最内侧的弧产生两个核结构， 动眼神经复合体和红核。我们还证明了一个完整的 一组中脑弧可能是由形态发生素的异位源引发的 音速刺猬（SHH）。在提议的实验中，我们将扩展我们的测试 外侧中脑的弧作为原核假说，我们将解决 SHH 源是否直接对弧进行图案化（作为远程形态发生素），或者 部分通过骨形态发生蛋白（BMP）中介发挥作用。第一个 一组实验研究了中脑外侧弧的解剖结构 顺行和逆行束追踪方法。一个发现是横向 弧具有特征性的神经元连接，不仅支持 原核假说，但可以用于将特定的弧识别为特定的 原核。第二组实验测试SHH指定的能力 中脑弧细胞类型直接作为远程形态发生素。这些实验 将在野生型和 talpid(2) 突变鸡胚胎中进行 卵电穿孔和外植体组织培养方法。我们的发现 然而，异位 SHH 诱导 BMP 基因表达提出了以下可能性： BMP2和BMP7可以参与SHH源的远程信令。这 第三组实验测试BMP信号对中脑的贡献 弧形图案。 腹侧中脑是中风和其他疾病的常见病理部位 神经系统疾病。了解其发育生物学应该 促进治疗学研究，包括基于组织的治疗学研究 移植。更一般地说，腹侧中脑发育提供了一个模型 了解脑核是如何形成的。对这些机制的深入了解可能会表明 治疗由核消融引起的神经系统疾病的新方法或 断线。