Structural and Functional Studies of HER Receptor Tyrosine Kinases

描述（由申请人提供）：该项目的长期目标是对控制人类表皮生长因子受体（HERs）激活和信号传导的基本机制进行分子和结构上的理解。HER受体酪氨酸激酶、EGFR、HER2、HER3和HER4在控制细胞生长、存活和运动中起关键作用。这些受体的失调在不同类型的癌症、神经病理疾病和心血管疾病中很常见。虽然在过去十年中，在确定靶向EGFR和HER2的药物方面取得了重大进展，但由HER3受体介导的耐药性的发展是一个新出现的问题。HER3是HER家族中不寻常的成员，因为它没有催化活性。然而，它可以与EGFR和HER2二聚，导致其催化结构域的变构活化。HER3是药物发现的一个具有挑战性的靶点，因为它缺乏酶活性位点，我们不太了解HER3如何与EGFR和HER2相互作用。该应用程序将通过定义HER3与EGFR和HER2形成活性信号复合物的分子机制来解决这些问题，并探索开发HER3抑制剂的知识。主要假设是HER3的变构功能可以通过其核苷酸结合位点进行调节，这是基于我们的初步数据制定的假设，并且了解HER3与其他her的异源二聚化的分子基础将揭示HER3变构功能的基本原理。将调查以下具体目标：将研究核苷酸结合调节HER3变构功能的机制，从而为抑制HER3的小分子的产生提供信息；2. 将研究HER3与EGFR和HER2异源二聚化的结构基础，以确定生长因子结合与催化活化在结构上耦合的机制；3. HER3异源二聚化对细胞中EGFR和HER2信号传导的贡献将通过单分子成像进行研究。这种方法是创新的，因为它解决了HER3内的新功能，并将定义HER3对其他HER受体变构功能的未知方面。这项工作也将有助于开发新的实验策略，旨在克服与研究膜受体相关的挑战。这项研究的意义在于它为HER受体家族的激活机制增加了一个新的调控步骤。此外，该研究有望推进我们对HER受体如何整合外部激活信号以导致其胞内酶功能的严格控制激活的分子理解。最终，对HER3功能的详细了解将为下一代抑制剂的开发提供信息，这些抑制剂可以帮助缓解人类疾病中针对HER受体的药物日益严重的耐药性问题。

DESCRIPTION (provided by applicant): The long-term goals of this project are to develop a molecular and structural understanding of the fundamental mechanisms that control activation and signaling by human epidermal growth factor receptors (HERs). HER receptor tyrosine kinases, EGFR, HER2, HER3 and HER4 play pivotal roles in controlling cellular growth, survival and motility. Misregulation of these receptors is common in different types of cancer, neuropathological disorders and cardiovascular diseases. While significant progress has been made in identifying drugs that target EGFR and HER2 over the past decade, the development of resistance mediated by the HER3 receptor is an emerging problem. HER3 is an unusual member of the HER family, because it is catalytically inactive. It can, however, dimerize with EGFR and HER2 resulting in the allosteric activation of their catalytic domains. HER3 is a challenging target for drug discovery because it lacks an enzymatically active site and we do not understand very well how HER3 interacts with EGFR and HER2. This application will address these issues by defining the molecular mechanism by which HER3 forms active signaling complexes with EGFR and HER2, and exploring this knowledge to develop HER3 inhibitors. The central hypotheses are that allosteric function of HER3 can be modulated through its nucleotide-binding site, which is a hypothesis formulated based on our preliminary data, and that an understanding of the molecular underpinnings of HER3 heterodimerization with other HERs will reveal basic principles of HER3 allosteric function. The following specific aims will be investigated: 1. The mechanism by which nucleotide binding regulates allosteric function of HER3 will be studied to inform the generation of small molecules that inhibit HER3; 2. The structural basis for HER3 heterodimerization with EGFR and HER2 will be investigated to define the mechanism by which growth factor binding is structurally coupled to catalytic activation; 3. The contribution of HER3 heterodimerization to signaling by EGFR and HER2 in cells will be investigated using single molecule imaging. This approach is innovative because it addresses a novel functionality within HER3 and will define the unknown aspects of HER3 allosteric function towards other HER receptors. This work will also contribute to the development of novel experimental strategies designed to overcome the challenges associated with studying membrane receptors. The proposed research is significant because it adds a new regulatory step in the activation mechanism of the HER family of receptors. Moreover, the proposed research is expected to advance our molecular understanding of how HER receptors integrate external activating signals to result in tightly controlled activation of their intracellular enzymtic functions. Ultimately, this detailed understanding of HER3 functions will inform the development of next generation inhibitors that can help alleviate the increasing problem of resistance to agents that target HER receptors in human diseases.