Elucidation of a Brachyury-independent branch of the notochord gene regulatory network

项目概要/摘要 在人类和其他脊椎动物胚胎的早期发育过程中，脊索支持和 通过中枢神经系统，轴旁中胚层， 内胚层和它们产生的众多器官。脊索形成障碍导致分娩 缺陷和先天性骨骼畸形，而出生后，改变脊索残余 是椎间盘病变的主要原因，并可引起罕见的肿瘤 叫做脊索瘤我们用简单的脊索动物玻璃海鞘来重建进化上 保守的脊索遗传工具包，最终目标是将我们的发现应用于脊椎动物 发育和人类胚胎发生。我们已经表明，大量的脊索表达， 脊椎动物基因在玻璃海鞘中是保守的，我们发现几个玻璃海鞘脊索增强子， 控制脊索基因表达的遗传开关，与脊索共享转录因子结合位点， 在脊椎动物中发现的调节区域。我们发表的结果提供了充分的证据， 简单的玻璃海鞘脊索表达的转录因子在进化上是保守的， 包括人类在内的脊椎动物，并且对于这种结构的发展是必要的。 本项目的目标是详细研究这些TF之一，玻璃海鞘Lmx样，并阐明其作用 在脊索发育中。这一目标将通过以下实验方法实现： 阐明Lmx样蛋白在脊索形态发生中的作用（目的1）; 由Lmx样控制的基因，以及它们中的一组选择的功能表征（目的2）。 这些研究的完成将揭示一个进化上保守的TF，Lmx样，似乎 与脊索形成的主要调节因子Brachyury平行作用，并将首次深入了解 它在脊索发育中的作用。预期的结果将揭示复杂的基因调控网络 它协调脊索动物之间的脊索形成，并将提供一个分子蓝图， 脊索源性出生缺陷的解释。

PROJECT SUMMARY/ABSTRACT During the early development of human and other vertebrate embryos, the notochord supports and instructs the formation of the body plan by patterning the central nervous system, paraxial mesoderm, endoderm and the numerous organs that they give rise to. Impairments in notochord formation cause birth defects and congenital skeletal malformations, while postnatally, alterations in the notochord remnants encased within the intervertebral discs are the main cause of discopathies and can give rise to rare tumors called chordomas. We are using the simple chordate Ciona to reconstruct the essential, evolutionarily conserved genetic toolkit of the notochord, with the ultimate goal of applying our findings to vertebrate development and human embryogenesis. We have shown that the notochord expression of a large number of vertebrate genes is conserved in Ciona and we have found that several Ciona notochord enhancers, the genetic switches that control notochord gene expression, share transcription factor binding sites with notochord regulatory regions that had been identified in vertebrates. Our published results provide ample evidence that the simple Ciona notochord expresses transcription factors (TFs) that are evolutionarily conserved in vertebrates, including humans, and are necessary for the development of this structure. The objective of this project is to study in detail one of these TFs, Ciona Lmx-like, and to clarify its role in notochord development. This objective will be achieved through the following experimental approaches: the elucidation of the role of Lmx-like in notochord morphogenesis (Aim 1); the identification of the notochord genes controlled by Lmx-like, and the functional characterization of a select group of them (Aim 2). Completion of these studies will shed light on an evolutionarily conserved TF, Lmx-like, which appears to act in parallel with Brachyury, the main regulator of notochord formation, and will provide a first insight into its role in notochord development. The expected results will shed light on the complex gene regulatory network that orchestrates notochord formation across chordates, and will provide a molecular blueprint for the interpretation of notochord-derived birth defects.