Mechanisms of Different Wnt Signals

描述（由申请人提供）：拟议研究的目的是通过结构和生物物理方法研究Wnt信号通路特定调控和靶向相互作用的分子机制。Wnt信号在胚胎发育和细胞生长调控中起重要作用。Wnt信号的不适当激活与癌症和其他人类疾病有关。disheveled （Dvl）是Wnt信号通路的重要组成部分，它将信号从膜结合的Wnt受体frzzled （Fz）传递到下游伙伴。不同的Wnt信号通路在Dvl水平上存在分化。然而，Dvl转导Wnt信号的机制尚不清楚，在Dvl水平上调节通路规范的分子事件也不清楚。提出的结构和生物物理分析将通过阐明Dvl及其结合伙伴之间相互作用的基本化学性质来解决这些问题。假设Dvl在接收到Wnt信号后发生构象变化。蛋白质核磁共振波谱将用于研究这些构象变化及其通过Dvl及其结合分子的分子相互作用调控的机制。具体目的：1)通过蛋白质核磁共振波谱等物理生化方法确定Dvl蛋白PDZ结构域与Fz受体c端结合的特异性；2)鉴定介导Dvl蛋白功能的调控网络的组成部分；3)确定Dvl在Wnt信号转导过程中是否发生构象变化。从这些研究中获得的知识不仅有助于解释Wnt信号中Dvl水平上复杂分子相互作用的基本化学性质，而且还将阐明细胞内信号特异性的维持和全局信号控制的性质。这些发现也可能有助于制定合理的方法来开发能够干扰导致人类疾病的特定Wnt信号事件的新型药物。

DESCRIPTION (provided by applicant): The objective of the proposed studies is to investigate the molecular mechanisms underlying the specific regulatory and targeting interactions of the Wnt signaling pathways by using structural and biophysical methods. Wnt signaling plays an important role in embryonic development and in the regulation of cell growth. Inappropriate activation of Wnt signaling has been implicated in cancers and other human diseases. Dishevelled (Dvl), an important component of the Wnt signaling pathways, relays signals from the membrane-bound Wnt receptor Frizzled (Fz) to downstream partners. Different Wnt signaling pathways diverge at the level of Dvl. However, the mechanism by which Dvl transduces the Wnt signals is unclear, as are the molecular events that regulate pathway specification at the level of Dvl. The proposed structural and biophysical analyses will address these questions by elucidating the fundamental chemical nature of the interactions between Dvl and its binding partners. Dvl is hypothesized to undergo conformational changes upon receiving Wnt signals. Protein NMR spectroscopy will be used to investigate these conformational changes and the mechanism of their regulation by molecular interactions of Dvl and its binding molecules. The Specific Aims are to 1) Determine the binding specificities between the PDZ domains of Dvl proteins and the C-termini of Fz receptors by protein NMR spectroscopy and other physical biochemistry methods; 2) Identify components of the regulatory network that mediates the function of the Dvl proteins; and 3) Ascertain whether Dvl undergoes a conformational change in the transduction of Wnt signaling. The knowledge gained from these investigations will not only help to explain the fundamental chemical nature of the complex molecular interplay at the level of Dvl in Wnt signaling but will also shed light on the maintenance of intracellular signal specificity and the nature of global signaling control. These findings may also be useful in formulating rational approaches to the development of novel pharmaceutical agents that can interfere with specific Wnt signaling events that contribute to human diseases.