Inductive and morphogenetic processes shaping the zebrafish embryonic axes

 描述(申请人提供)：脊椎动物的身体是如何从单个细胞发育而来的是我研究的首要问题。尽管取得了很大进展，但胚胎发生的许多基本机制仍然知之甚少。我特别感兴趣的是，如何在空间和时间上协调建立胚胎身体计划的诱导和形态发生过程，以确保正常发育。斑马鱼受精卵的前后和背腹胚轴的指定涉及促进背部Wnt/β-catenin活性的微管依赖的运输，这些因子形成胚层并协调原肠形成运动。我们发现，Ccl19.1趋化因子信号通过CCR7G蛋白偶联受体(GPCRi)通过下调β-连环蛋白来限制轴的形成。利用ccl19.1和CCR7斑马鱼基因的突变，我们将描述它们调节钙信号和限制轴形成的途径。我们最近发现，Dachsous(DCHS)钙粘附素调节受精卵和轴形成过程中的细胞骨架。虽然DCHS通常与Fat钙粘蛋白和Fjx1激酶相互作用，但我们将描述DCHs的Fat/Fjx1依赖和独立的作用。我们将确定与DCHS相互作用的蛋白质，以确定其与细胞骨架和其他效应器的功能联系。在原肠形成过程中，会聚和伸展(C&E)运动使胚层向前拉长，背面变窄。WNT/平面细胞极性(WNT/PCP)信号是驱动脊椎动物C&E的极化细胞行为的保守调节因子。我们的研究认为，Wnt/PCP信号在原肠发育过程中作为一个细胞指南针，协调具有前后胚胎极性的单个细胞的极性和行为，部分原因是PCP组分在前后细胞膜上的不对称分布。为了了解动态间充质细胞中PCP组分的平面不对称性是如何产生的，我们将检验一种新的PCP组分GPCRGpr125促进后富集膜PCP复合体的形成的假设。我们将确定DCHS是否在原肠形成过程中与Fat和Fjx1一起作用于微管极化，并调节依赖于Wnt/PCP信号的细胞极性。最后，我们将测试DCHS/Fat/Fjx1系统是否提供了一种将Wnt/PCP信号与全球胚胎模式联系起来的机制。为了揭示更多参与轴系形成和原肠形成的趋化因子GPCRs，我们将通过表征功能丧失的单一和复合突变表型来询问21个趋化因子GPCRs亚集在胚胎发育过程中表达的功能。由于Wnt、DCHS/Fat和GPCR通路的突变会导致流产、出生缺陷和疾病，我们的研究可以促进对它们的理解、诊断和促进治疗的发展。

 DESCRIPTION (provided by applicant): How does a vertebrate animal body develop from a single cell is an overarching question of my research. Despite much progress, many basic mechanisms underlying embryogenesis remain poorly understood. I am particularly interested how the inductive and morphogenetic processes that establish the embryonic body plan are coordinated in space and time to ensure normal development. Specification of anteroposterior and dorsoventral embryonic axis in the zebrafish zygote involves microtubule dependent transport of factors promoting dorsal Wnt/β-catenin activity, which patterns germ layers and coordinates gastrulation movements. We showed that Ccl19.1 chemokine signaling through Ccr7 G protein-coupled receptor (GPCR) limits axis formation by downregulating β-catenin. Using mutations in ccl19.1 and ccr7 zebrafish genes we will delineate the pathways through which they regulate calcium signaling and limit axis formation. We recently discovered that Dachsous (Dchs) cadherins regulate cytoskeleton in the zygote and during axis formation. Whereas Dchs is commonly known to interact with Fat cadherin and Fjx1 kinase, we will characterize Fat/Fjx1-dependent and independent roles of Dchs. We will identify proteins interacting with Dchs to define its functional links to cytoskeleton and other effectors. During gastrulation, convergence and extension (C&E) movements elongate the germ layers anteroposteriorly and narrow them dorsoventrally. Wnt/Planar Cell Polarity (Wnt/PCP) signaling is a conserved regulator of polarized cell behaviors driving C&E in vertebrates. Our studies posit that Wnt/PCP signaling works during gastrulation as a cellular compass coordinating polarity and behaviors of individual cells with anteroposterior embryonic polarity, in part by asymmetric distribution of PCP components at anterior and posterior cell membranes. To understand how the planar asymmetries of PCP components arise in dynamic mesenchymal cells, we will test the hypothesis that adhesion GPCR, Gpr125, a new PCP component, promotes formation of the posteriorly enriched membrane PCP complexes. We will determine whether Dchs works with Fat and Fjx1 during gastrulation to polarize microtubules and regulate Wnt/PCP signaling-dependent cell polarity. Finally, we will test whether the Dchs/Fat/Fjx1 system provides a mechanism to link Wnt/PCP signaling to global embryo patterning. To uncover additional chemokine GPCRs involved in axis formation and gastrulation, we will interrogate functions of the subset of 21 chemokine GPCRs expressed during embryogenesis by characterizing loss-of-function single and compound mutant phenotypes. As mutations in the components of the Wnt, Dchs/Fat and GPCR pathways cause miscarriages, birth defects and diseases; our studies can advance their understanding, diagnosis and facilitate development of therapies.