The structural basis of biased signaling through HER4 receptor complexes

HER4 受体复合物偏向信号传导的结构基础

• 批准号: 437011922
• 负责人: Dr. Raphael Trenker, Ph.D.
• 金额: --
• 依托单位: Cardiovascular Research Institute
• 依托单位国家: 德国
• 项目类别: Research Fellowships
• 财政年份: 2020
• 资助国家: 德国
• 起止时间: 2019-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/437011922?language=en
• 关键词: structural; basis; biased; signaling; through

The Human Epidermal growth factor Receptor (HER) tyrosine kinases, represented by the structurally-related proteins EGFR, HER2, HER3 and HER4, are gatekeepers of cellular homeostasis. They control cell growth, survival, and motility by linking extracellular growth factor binding to intracellular chemical events. The least characterized family member is HER4, despite its crucial role in the development and function of heart and neuronal tissues. In the heart, HER4 forms complexes with HER2 to guide heart development in the embryo and function in the adult. Missregulation of HER4 and HER4/HER2 signaling are strongly correlated with heart disease and neurological disorders such as schizophrenia and Alzheimer’s Disease. While HER2 does not bind to ligands, HER4 can be activated by all four members of the Neuregulin family of growth factors (NRG1-4), and has a remarkable ability to distinguish them from one another to relay NRG type-distinct messages into the cell. This biased agonism leads to ligand-specific functional consequences for the cell and determines whether a cell proliferates, dies, or differentiates. However, we do not currently understand the mechanism by which binding of different ligands to the extracellular domains of HER4 influences its intracellular signaling domains - kinases. This is because there are no high-resolution structures in which both extracellular domains and kinase domains are present simultaneously. In this proposal, I aim to fill this gap by obtaining the first high-resolution structures of the near full-length HER4 receptor in complex with different Neuregulin growth factors, and with HER2. To this end, I will use cryo-EM and our recently gained ability to purify HER4 and HER2 in robust quantities permitting structural studies. In our preliminary work, we show that we are able to form NRG1-bound HER4 and HER2/HER4 heterocomplexes. Initial characterization of these receptors by negative-stain and cryo-EM already reveal receptor features that have not been observed in published crystal structures of isolated receptor domains. These results demonstrate feasibility of our approach and its application to understand receptor activation mechanism and its fine tuning by different ligands. We will validate our structure-function findings in cell-proliferation assays via mutagenesis. Our studies will be invaluable for uncovering fundamental principles of ligand-induced HER4 receptor signaling and the design of targeted therapies in cardiovascular and neuronal disorders.

以结构相关蛋白EGFR、HER 2、HER 3和HER 4为代表的人表皮生长因子受体（HER）酪氨酸激酶是细胞稳态的守门人。它们通过将细胞外生长因子结合到细胞内化学事件来控制细胞生长、存活和运动。最不具特征的家族成员是HER 4，尽管它在心脏和神经元组织的发育和功能中起着关键作用。在心脏中，HER 4与HER 2形成复合物，以指导胚胎中的心脏发育和成人中的功能。HER 4和HER 4/HER 2信号传导失调与心脏病和精神分裂症和阿尔茨海默病等神经系统疾病密切相关。虽然HER 2不与配体结合，但HER 4可以被生长因子的神经调节蛋白家族（NRG 1 -4）的所有四个成员激活，并且具有将它们彼此区分以将NRG类型不同的信息传递到细胞中的显著能力。这种偏向性激动作用导致细胞的配体特异性功能结果，并决定细胞是否增殖、死亡或分化。然而，我们目前还不了解不同配体与HER 4胞外结构域的结合影响其胞内信号传导结构域-激酶的机制。这是因为没有细胞外结构域和激酶结构域同时存在的高分辨率结构。在这项提案中，我的目标是通过获得与不同的Neuregulin生长因子和HER 2复合的近全长HER 4受体的第一个高分辨率结构来填补这一空白。为此，我将使用cryo-EM和我们最近获得的能力，以强大的数量纯化HER 4和HER 2，允许结构研究。在我们的初步工作中，我们表明，我们能够形成NRG 1结合的HER 4和HER 2/HER 4杂合物。这些受体的负染色和冷冻EM的初步表征已经揭示了尚未观察到的分离的受体域的晶体结构中发表的受体功能。这些结果证明了我们的方法的可行性，并将其应用于了解受体激活机制及其通过不同配体进行微调。我们将通过诱变在细胞增殖试验中验证我们的结构-功能发现。我们的研究对于揭示配体诱导的HER 4受体信号传导的基本原理以及心血管和神经元疾病靶向治疗的设计将是非常宝贵的。