Dishevelled-Mediated Control of Wnt/PCP Pathways

描述(申请人提供)：保存完好的规范和非规范的Wnt通路对哺乳动物发育的各个方面都很重要，包括中枢神经系统的发育。一个悬而未决的问题是：在体内，调节发育的各种Wnt途径是如何整合的？DVL是解决这一问题的优秀候选者，因为这些保守的蛋白质在所有真核生物中都是规范和非规范Wnt途径所必需的。我们已经发现了三个DVL基因中部分独特但主要是冗余的功能。单个突变体在社会行为和心脏圆锥干发育方面表现出一些独特的缺陷，而双DVL突变体则表现出严重的神经管缺陷(颅口裂)和严重的耳蜗缺陷。为了进一步支持冗余性，Dvl1/2/3三重突变体不能进行原肠胚形成，也不形成中胚层。我们计划剖析DVL调节正常发育和DVL突变体中被干扰以产生这些表型的体内途径。我们在小鼠体内为每个DVL基因产生了条件等位基因，以及可以区分非典型Wnt/PCP途径功能的典型Wnt的体内等位基因。我们使用这些等位基因来提供确凿的证据，证明Dvl1和Dvl2双突变所表现的颅口裂表型是通过Wnt/PCP途径的会聚伸展运动中断所致。我们将使用这些工具来全面分析规范的Wnt和非规范的Wnt/PCP通路在神经元发育过程中的作用，从原肠形成和神经形成期间的第一次神经折叠发育到神经发生和神经元迁移。根据我们公布的初步数据，我们预测DVL及其调控的通路在大脑发育的所有阶段都是至关重要的。我们将使用以下特定目标：1)确定在活体原肠形成过程中规范的Wnt和非规范的Wnt/PCP通路的作用；2)表征DVL依赖的通路在神经形成过程中负责神经管关闭的作用；3)使用双Dvl突变体确定Dvls和规范的Wnt和非典型的Wnt/PCP通路在前脑/中脑-后脑发育中的作用；以及4)使用三重Dvl突变体确定Dvls和典型的Wnt和非典型的Wnt/PCP通路在前脑/中脑-后脑发育过程中的作用。

DESCRIPTION (provided by applicant): The well-conserved canonical and non-canonical Wnt pathways are important for all aspects of mammalian development, including the development of the central nervous system. An outstanding question remains: how are the various Wnt pathways that regulate development integrated in vivo? Dvls are outstanding candidates to address this question, since these conserved proteins are required in all eukaryotes for both canonical and non-canonical Wnt pathways. We have uncovered partially unique but predominantly redundant functions among the three Dvl genes. Single mutants display some unique defects in social behavior and conotruncal heart development, while double Dvl mutants display severe neural tube defects (craniorachischisis) and severe cochlear defects. In further support of redundancy, Dvl1/2/3 triple mutants are unable to undergo gastrulation and do not form mesoderm. We plan to dissect the in vivo pathways that Dvls regulate normal development and are disrupted in the Dvl mutants to produce these phenotypes. We produced in vivo conditional alleles in mice for each of the Dvl genes as well as in vivo alleles that can distinguish either canonical Wnt of non-canonical Wnt/PCP pathway function. We used these alleles to provide definitive evidence that the craniorachischisis phenotype displayed by Dvl1;Dvl2 double mutants resulted from disruption of convergent extension movements via the Wnt/PCP pathway. We will use these tools to provide a comprehensive analysis of the role of the canonical Wnt and non-canonical Wnt/PCP pathways during neuronal development from the first development of neural folds during gastrulation and neurulation throughout neurogenesis and neuronal migration. Based on our published and preliminary data, we predict that Dvls and the pathways they regulate are critical at all stages of brain development. We will use the following specific aims: 1) Determine the role of canonical Wnt and non-canonical Wnt/PCP pathways during gastrulation in vivo; 2) Characterize the Dvl dependent pathways responsible for neural tube closure during neurulation; 3) Determine the role of Dvls and the canonical Wnt and non-canonical Wnt/PCP pathways during forebrain/midbrain-hindbrain development using double Dvl mutants; and 4) Determine the role of Dvls and the canonical Wnt and non-canonical Wnt/PCP pathways during forebrain/midbrain-hindbrain development using triple Dvl mutants.