Structures of full-length FGFR cancer fusions and disease mutants

当细胞需要分裂和复制时（例如，在胚胎发育、生长或伤口愈合期间），细胞接收来自生长因子的信号。这些信号由生长因子结合的细胞外部通过酪氨酸激酶受体（RTKs）传递到细胞内部，酪氨酸激酶受体是一种位于细胞膜内部并跨越细胞膜的蛋白质。虽然部分rtk的结构是已知的，但整个（全长）rtk的高分辨率结构尚未确定，因此我们对不同结构域如何相互作用以控制信号传导的理解是不完整的。在这个项目中，我们将使用尖端的原子分辨率方法，如冷冻电子显微镜和核磁共振波谱，确定全长成纤维细胞生长因子受体（FGFRs）的结构。fgfr和改变形式的FGRFs是几种人类癌症和一些发育障碍的原因，是控制胚胎发育、伤口愈合和新血管生长（血管生成）等过程的典型rtk。fgfr通常是通过成纤维细胞生长因子（FGFs）与细胞外（细胞外）区域结合而激活的，但在一些癌症和发育性疾病中，它们可以发生改变，因此即使没有FGF结合，它们也可以永久活跃。如果我们要了解fgfr和其他rtk如何正常发挥功能，例如，它们如何在静息状态下被自动抑制，但随后被激活，了解fgfr不同结构域（例如细胞外和细胞内部分）之间的结构连接是必不可少的。FGFRs的癌症相关变体尤其如此，其中FGFR3基因的一部分与另一种蛋白质TACC3的部分基因融合，产生一种高度激活的杂交蛋白，也定位于细胞的不同部分。这些所谓的FGFR3-TACC3融合是导致某些类型的胶质母细胞瘤（侵袭性脑肿瘤）和一些膀胱癌的原因。从结构层面理解过度激活是如何发生的，将提高我们选择性地靶向这些融合蛋白的能力，从而更好地治疗由它们引起的癌症。我们还预测，这些具有异常活性的fgfr的疾病相关变体可能与各种不同的蛋白质伴侣形成新的细胞内复合物。为了充分了解突变如何影响功能，我们还必须确定能够促进和调节信号转导的结合伙伴。为此，我们研究的另一个方面将是在实验室培养的癌细胞中使用交联质谱（XL-MS）来识别这些新的伙伴，并找出这些相互作用如何促进疾病进程。通过提高我们对（正常和疾病改变的）FGFR结构和细胞相互作用的认识，我们的目标是更好地理解为什么FGFR靶向药物分子在某些疾病中有效，而在其他疾病中则不那么有效，以及我们如何开发更有效的药物分子。总之，我们的项目旨在解决以下问题：-通过解决完整fgfr的结构及其与癌症相关的改变形式（例如FGFR-TACC融合），我们能否更好地理解细胞外信号（如生长因子结合）如何被翻译成活化fgfr产生的不同细胞内反应？FGFRs在正常细胞和癌细胞中形成什么功能复合物，它们对潜在的新治疗药物靶向策略有什么启示？

Cells receive signals from growth factors when they need to divide and replicate (e.g., during embryonic development, growth, or wound healing). These signals are transmitted from the outside of the cell, where the growth factor binds, to the inside, by receptor tyrosine kinases (RTKs) - proteins that sit within and span across the cell membrane. Although the structures for parts of RTKs are known, high resolution structures of whole (full-length) RTKs have yet to be determined, so our understanding of how the different domains interact to control signalling is incomplete.In this project, we will determine structures of full-length fibroblast growth factor receptors (FGFRs), using cutting-edge atomic-resolution methods such as cryo-electron microscopy and nuclear magnetic resonance spectroscopy. FGFRs, and altered forms of FGRFs that are responsible for several types of human cancers as well as for some developmental disorders, are archetypal RTKs that control processes such as embryonic development, wound healing, and growth of new blood vessels (angiogenesis). FGFRs are normally activated by binding of fibroblast growth factors (FGFs) to their extracellular (outside of the cell) regions, but in some cancers and developmental diseases they can become altered so that they are permanently active even without FGF binding.Understanding the structural connections between the different domains of FGFRs (e.g. extracellular and intracellular parts) is essential if we are to understand how FGFRs and other RTKs function normally - for example, how they are auto-inhibited in the resting state but then become activated. This is particularly the case for a cancer-associated variant of FGFRs whereby part of the FGFR3 gene becomes fused with part of the gene from another protein, TACC3, to generate a hybrid protein that is hyperactivated and also localises to different parts of the cell. These so-called FGFR3-TACC3 fusions are responsible for certain types of glioblastomas (aggressive brain tumours) and some bladder cancers. Understanding at a structural level how the hyperactivation occurs will improve our ability to selectively target these fusion proteins to better treat those cancers for which they are responsible.We also anticipate that these disease-associated variants of FGFRs with aberrant activity are likely to form novel intracellular complexes with a variety of different protein partners. To fully understand how mutations may affect function we must also identify binding partners that can facilitate and regulate signal transduction. To this end another aspect of our research will be to use cross-linking mass spectrometry (XL-MS) in lab-grown cancer cells to identify these new partners and find out how those interactions contribute to the disease process.By improving our knowledge of (normal and disease-altered) FGFR structures and cellular interactions, we aim to understand better why FGFR-targeted drug molecules are effective in some disease settings and less so in others, and how we can then develop more efficacious drug molecules. In summary, our project aims to address the following questions:- Through solving the structures of complete FGFRs and their cancer-associated altered forms (e.g. FGFR-TACC fusions), can we better understand how extracellular signals (such as growth factor binding) are translated into the different intracellular responses generated from activated FGFRs?- What functional complexes do FGFRs form in normal and cancer cells, and what do they tell us about potential new therapeutic drug targeting strategies?