Brachyury-downstream gene networks in the notochord

描述（由申请人提供）：转录因子Brachyury（Bra）在脊索形成中的作用有充分的文献记载，并且在整个脊索动物门中进化保守。然而，目前对Bra直接或间接调控的转录因子以及与Bra协同作用的转录因子在脊索发育和进化中的作用还知之甚少。特别是，在脊索中指导表达的顺式调节模块（增强子）的结构、共同特征和调节方式的知识是零碎和贫乏的。我们已经利用了海鞘玻璃海鞘作为模型系统提供的实验优势，分离和表征的集合脊索增强子的基因，已经被描述为Bra的目标和基因的关系与Bra是未知的。我们的初步数据，收集的脊索增强子的比较分析，使我们假设，脊索的形成在玻璃海鞘依赖于额外的，主要是uncharacterized脊索转录因子，分为两类：布拉下游因子，直接或间接控制的布拉和作为其转录中介体和因素与布拉协同作用。我们将通过以下具体目标来检验这些假设：（1）分离脊索表达所需的最小调节序列;（2）鉴定控制最小增强子序列的激活子，并研究它们在脊索发育中的作用;（3）鉴定控制所选脊索激活子的增强子。 拟议的研究的广泛范围是迅速解开脊索发育和分化的不同步骤的基因网络，并获得有价值的见解脊索形成和进化过程中的基因表达控制的分子机制。

DESCRIPTION (provided by applicant): The role of the transcription factor Brachyury (Bra) in notochord formation is well documented and evolutionarily conserved throughout the chordate phylum. However, still little is known about the transcription factors controlled directly or indirectly by Bra and about the function of factors acting in concert with Bra in notochord development and evolution. In particular, the knowledge of structure, common features and modalities of regulation of cis-regulatory modules (enhancers) directing expression in the notochord is fragmentary and poor. We have exploited the experimental advantages offered by the ascidian Ciona intestinalis as a model system to isolate and characterize a collection of notochord enhancers from genes that have already been described as Bra targets and from genes whose relationship with Bra is unknown. Our preliminary data, gathered from the comparative analysis of the notochord enhancers, lead us to hypothesize that notochord formation in Ciona relies upon additional, mostly uncharacterized notochord transcription factors that fall into two categories: Bra-downstream factors, controlled directly or indirectly by Bra and acting as its transcriptional intermediaries and factors acting in concert with Bra. We will test these hypotheses through the following specific aims: (1) Isolate minimal regulatory sequences necessary for notochord expression; (2) Identify the activators controlling the minimal enhancer sequences and study their role in notochord development; (3) Identify the enhancers controlling, in turn, selected notochord activators. The broad scope of the proposed research is to rapidly untangle the gene networks underlying the different steps of notochord development and differentiation and to gain valuable insights into the molecular mechanisms controlling gene expression in the notochord during its formation and evolution.