Gene regulatory network evolution and the origin of biological novelties

描述（由申请人提供）：细胞在发育过程中通过组合基因活性的不同途径获得其独特的命运。基因调控网络（GRN）控制内胚层细胞命运的规范已经在少数模型系统中构建，包括海胆、脊椎动物和线虫。产生内胚层（肠道衍生物）和中胚层（肌肉、血液、体腔、肾脏和骨骼成分）细胞类型的内胚层前体通过不同的基因表达与外胚层前体（产生表皮和神经系统）不同。随后，从内胚层前体中分离出内胚层和中胚层。了解细胞内因子和细胞外信号之间的关系，重建不同动物物种之间的基因调控网络，可以为了解每种生物的分子和形态特征是如何以及何时建立提供关键的见解。一个典型的例子是动物进化中最初出现的中胚层。刺胞动物（海葵、珊瑚和“水母”）是一种动物群体，其成虫只具有两个胚层的衍生物，外胚层和双功能（具有吸收和收缩功能）的胃真皮（肠）层。刺胞动物是其他具有所有三胚层的双侧对称动物的近亲，令人信服的分子、基因组、发育和进化证据表明，刺胞动物的胃真皮是所有其他三胚层双侧动物的内胚层和中胚层的进化前体。因此，揭示这种刺胞动物的“内胚层”基因调控网络，将提供必要的见解，了解GRN亚回路如何在各种后生动物中被采用、重新连接或增选，以产生新的、修饰的或特化的内胚层特征。该基金将利用QPCR、全基因组微阵列、药物治疗等功能技术、合成mRNA错表达、翻译和剪接阻断morpholino方法和顺式调控分析，从功能上重建刺胞海葵（Nematostella vectensis）内胚层形成的基因调控网络（其基因组已由能源部测序）。此外，我们将把所有获得的数据纳入一个已经存在的基因表达数据库，以便与科学界分享我们的发现。首次从系统发育关键物种中产生的高质量分子数据将有助于解释以前在双边模型系统中发现的基因差异及其调节相互作用，通过极化进化变化的方向。

DESCRIPTION (provided by applicant): Cells acquire their unique fates by the differential pathways of combinatorial gene activity during the developmental period. Gene regulatory networks (GRN) controlling the specification of endomesodermal cell fates have been constructed in a handful of model systems, include sea urchins, vertebrates, and nematodes. Endomesodermal precursors that give rise to endodermal (gut derivatives) and mesodermal (muscle, blood, coelom, kidney and skeletal elements) cell types become distinct from ectodermal precursors (that give rise to epidermis and nervous system) by differential gene expression. Separate endodermal and mesodermal fates are then specified subsequently from endomesodermal precursors. Understanding the relationship between intracellular factors and extracellular signals, and reconstructing gene regulatory networks between different animal species can provide key insights in how and when the molecular and morphological characters of each organism are built. A prime example is the original evolutionary appearance of the mesodermal germ layer in animal evolution. Cnidarians (anemones, corals, and "jellyfish") are an animal group whose adults possess derivatives of only two germ layers, ectoderm and a bifunctional (having both absorptive and contractile functions) gastodermal (gut) layer. Cnidarians are the closest living relatives of other bilaterally symmetrical animals that possess all three germ layers, and compelling molecular, genomic, developmental, and evolutionary evidence exists to demonstrate that the cnidarian gastrodermis is the evolutionary precursor of both endodermal and mesodermal germ layers in all other triploblastic bilaterian animals. Thus, unraveling this cnidarian "endomesodermal" gene regulatory network, will provide necessary insight into how GRN sub circuits have been adopted, rewired or co-opted in various metazoan in order to give rise to novel, modified or specialized endomesodermal features. This grant will functionally reconstruct the gene regulatory network underlying endomesoderm formation in the cnidarian sea anemone Nematostella vectensis, (whose genome has been sequenced by the J.G.I (Dept. Energy), using, QPCR, whole genome microarrays, functional techniques such as pharmaceutical drug treatments, synthetic mRNA misexpression, translation and splice blocking morpholino approaches and cis-regulatory analysis. In addition, we will implement all the obtained data into an already existing gene expression database in order to share our findings with the scientific community. The generation of high quality molecular data from a phylogentically pivotal species for the first time will help explain the differences seen in genes and their regulatory interactions previously identified in bilaterian model systems by polarizing the direction of evolutionary change. PUBLIC HEALTH RELEVANCE: Project Narrative Individual cells in developing animal embryos learn their ultimate fate by the sequential differential activation of specific genes contained in each cell's genome. We have learned a great deal about how these genes functionally regulate each other in complex gene regulatory networks (GRN) in a handful of model species. This grant uses a powerful new model system to functionally understand how endodermal (gut) and mesodermal (e.g. muscle, blood, bone, kidney) arose from a common endomesodermal precursor. These novel data will provide insight into the significance of variations in the GRNs in different systems and suggest specific gene interactions involved in abnormalities in endomesodermal development.