Understanding Signaling by Non-Canonical Receptor Tyrosine Kinases

项目摘要 这项MIRA申请中提出的研究旨在了解 跨受体酪氨酸激酶（RTK）超家族的跨膜信号传导，其成员发挥作用， 在人类疾病--从神经发育障碍到骨病、癌症、糖尿病 还有几处先天畸形在RTK信号传导的传统观点中，生长因子配体诱导 受体二聚体成为酪氨酸自磷酸化和招募下游信号分子。正如我们 了解更多关于20个不同的RTK系列（其中包括58个RTK），但是，它变得更加清晰 这种观点只适用于这些受体的一个子集。本文的研究重点是两个 需要非常不同的机制观点的特征-结合Wnt蛋白（并且不结合Wnt蛋白）的RTK 结果二聚化）和在其胞内区域具有“死”激酶或假激酶的RTK。新 为了理解这些重要的受体如何发出信号，必须理解范例。我们的目标结束了 未来5-10年是：1.为了对RTK在Wnt信号传导中所起的作用形成一个连贯的图景（这 涉及20个RTK系列中的4个），2.为了了解带有假激酶结构域的RTK如何， 结合ATP（在20个RTK家族中的5个中发现）可以信号传导，以及3.为了确定为什么假激酶- 在Wnt监管的RTK中代表。以受体/配体的细胞和体内研究为指导 关系，我们将研究配体诱导的复合物生化，并与高分辨率的结构 方法，以详细了解Wnt蛋白结合如何导致受体的激活， 信号复合物中的辅助受体。在进行这些研究时，我们将研究Wnt在其中所起的作用。 酰化-结合卷曲家族和RTK家族Wnt的要求似乎不同 受体。我们还希望在Wnt蛋白中确定不同信号传导模式的特异性决定簇。 在这些追求的同时，我们将使用结构指导的方法，结合化学生物学和 突变受体的功能分析，以探索RTK中假激酶的信号转导机制 超家族这些研究将对10%的人类激酶组产生重要影响， 假激酶，并将系统地测试假设，调节开关的假激酶 信号传导需要构象。我们的方法也将为治疗带来新的机会。 靶向假激酶，如PTK 7、Ror 2和Ror 1，它们与几种疾病有关。 总之，我们的研究将为一类受体的信号传导提供重要的基础新见解， 不符合RTK或Wnt受体的正常模式。理解它们对于解卷积至关重要 Wnt信号特异性的复杂性，并梳理出它的多重作用。此外，我们的研究结果应该 为潜在的治疗抑制开辟了新的途径-这些Wnt结合RTK在疾病中的作用 变得越来越清晰。

Project Summary The research proposed in this MIRA application seeks to understand unexplored mechanisms of transmembrane signaling across the receptor tyrosine kinase (RTK) superfamily, members of which play an important role in human disease – from neurodevelopmental disorders, to bone diseases, cancers, diabetes, and several congenital malformations. In the traditional view of RTK signaling, growth factor ligands induce receptor dimers that become tyrosine autophosphorylated and recruit downstream signaling molecules. As we understand more about the 20 different RTK families (which include 58 RTKs), however, it becomes clearer that this view only applies to a subset of these receptors. The research proposed here focuses on two characteristics that demand a very different mechanistic view – RTKs that bind Wnt proteins (and do not dimerize as a result) and RTKs that have `dead' kinase or pseudokinases in their intracellular regions. New paradigms must be understood in order to appreciate how these important receptors signal. Our goals over the next 5-10 years are: 1. To develop a coherent picture of the role played by RTKs in Wnt signaling (which involves 4 of the 20 RTK families), 2. To understand how RTKs with pseudokinase domains that do not even bind ATP (found in 5 of the 20 RTK families) can signal, and 3. To determine why pseudokinases are over- represented among the Wnt-regulated RTKs. Guided by cellular and in vivo studies of receptor/ligand relationships we will study ligand-induced complexes biochemically, and with high-resolution structural approaches, in order to understand in detail how Wnt protein binding leads to activation of the receptors and co-receptors in the signaling complex. In pursuing these studies, we will investigate the role played by Wnt acylation – requirements for which appear to be different for binding to Frizzled-family and RTK-family Wnt receptors. We also hope to define specificity determinants in the Wnt proteins for distinct modes of signaling. In parallel with these pursuits, we will use a structurally-guided approach, combined with chemical biology and functional analysis of mutated receptors, to explore the mechanism of signaling by pseudokinases in the RTK superfamily. These studies will have important implications for the 10% of the human kinome thought to be pseudokinases, and will systematically test the hypothesis that regulated switching of pseudokinase conformation is required for signaling. Our approaches will also bring new opportunities for therapeutic targeting of pseudokinases such as PTK7, Ror2, and Ror1, which have been implicated in several diseases. Together, our studies will provide important fundamental new insight into signaling by a class of receptors that do not fit into normal paradigms for RTKs or Wnt receptors. Understanding them is crucial for deconvoluting the complexity of Wnt signaling specificity and teasing out its multiple roles. In addition, our findings should open new avenues for potential therapeutic inhibition – as the roles of these Wnt-binding RTKs in disease become increasingly clear.