The chaperone cycle of fibroblast growth factor receptor kinases in molecular detail

当我们体内的细胞老化或遇到外部压力时，例如来自饮食或环境的毒素，细胞内的蛋白质会累积损伤（例如突变）或表达水平的改变，从而导致它们形成损害细胞功能和生存的聚集体。诸如阿尔茨海默氏症和帕金森氏症等衰老疾病是与某些神经元细胞群内形成大而聚集的蛋白质结构相关的疾病，导致痴呆、震颤或失去运动控制等表现。在面对压力时，细胞会产生一组叫做伴侣蛋白的蛋白质，其功能是拯救这些异常折叠或聚集的蛋白质。然而，通常情况下，伴侣反应本身可以通过细胞损伤的积累而受到损害，这可以削弱生物体修复蛋白质聚集的能力，并导致疾病随着年龄的增长而恶化。伴侣反应的其中一个环节涉及到HSP90蛋白，它在包括Cdc37在内的各种共同伴侣蛋白的帮助下识别“客户”蛋白。Cdc37是参与细胞信号传导的重要蛋白家族（激酶）的特异性共伴侣。受体酪氨酸激酶（RTKs）是一种“信号传导”激酶，可将信号从细胞外部传递到细胞内部，包括成纤维细胞生长因子受体激酶（FGFRs），这是本研究的主题。fgfr在胚胎发育、伤口愈合、新血管的生成中起着重要作用，并且以改变的形式导致几种类型的癌症。我们感兴趣的是建立fgfr如何与Cdc37- hsp90伴侣系统相互作用的分子细节，特别是Cdc37如何能够区分需要伴侣干预的fgfr形式（例如，导致癌症等疾病的fgfr的改变形式）和那些不需要的fgfr形式（例如，大多数fgfr的野生型变体）。我们的项目旨在通过使用一系列尖端技术和方法来填补我们知识中的一些重要空白。特别是，冷冻电子显微镜（cryo-EM）最近经历了结构细节水平的显着提高，它可以提供，感谢新的技术和方法，在利兹和伦敦大学学院，我们有机会获得最新一代的冷冻电子显微镜设备和专业知识。其他结构技术，如核磁共振和质谱也有了显著的进步，同样，我们在利兹和伦敦大学学院拥有专业知识和最先进的设备来承担这项工作。此外，在过去的5年里，我们已经建立了一个强大的试点数据体系，产生了所需的成分，特别是蛋白质复合物，这通常是这些具有挑战性的项目的限制步骤。了解Cdc37的分子水平“参与规则”和FGFR激酶的伴侣系统及其改变的形式将有助于我们不仅了解伴侣系统在这类重要蛋白质客户（RTKs）方面的正常功能，而且了解它如何在急性或累积细胞应激中被淹没或破坏。这种理解也有助于有选择地靶向伴侣系统来治疗由致癌激酶驱动的癌症，这些致癌激酶对伴侣干预“上瘾”以维持其活性。

As cells in our body age or encounter external stresses, such as toxins derived from diet or the environment, proteins within the cell can accumulate damage (for example mutations) or alterations in expression levels that can cause them to form aggregates that are damaging to cell function and survival. Diseases of aging such as Alzheimer's and Parkinson's are examples of conditions associated with the formation of large, aggregated protein structures within certain groups of neuronal cells, leading to manifestations including dementia, tremor or loss of motor control. In response to stresses, cells marshal a set of proteins called chaperones whose function is to rescue such aberrantly folded or aggregated proteins. Often, however, the chaperone response itself can become compromised through accumulation of cellular damage, which can blunt the organism's ability to remediate protein aggregation and lead to disease progression with advancing age.One such arm of the chaperone response involves the protein HSP90, which is assisted in its recognition of 'client' proteins by various co-chaperones that include Cdc37. Cdc37 is the specific co-chaperone for an important family of proteins involved in cellular signalling known as kinases. Receptor tyrosine kinases (RTKs) are a type of 'signalling' kinase that transduce signals from outside to inside cells and include fibroblast growth factor receptor kinases (FGFRs), the subject of this study. FGFRs are important in embryonic development, wound-healing, generation of new blood vessels, and in altered forms are responsible for driving several types of cancer. We are interested in establishing the molecular details of how FGFRs interact with the Cdc37-HSP90 chaperone system, and in particular in how Cdc37 is able to distinguish between forms of FGFRs that require chaperone intervention (for example, altered forms of FGFRs responsible for diseases such as cancer) and those that do not (for example, wild-type variants of most FGFRs).Our project seeks to fill in some of the important gaps in our knowledge, by using a range of cutting-edge technologies and approaches. In particular, cryo-electron microscopy (cryo-EM) has recently undergone a dramatic improvement in the level of structural detail it can provide, thanks to new technologies and methods, and in Leeds and UCL we have access to the latest-generation cryo-EM equipment and expertise. Other structural techniques such as NMR and mass spectrometry have also seen significant advances in capability, and again, we have expertise and state-of-the-art equipment in Leeds and UCL to undertake this work. Moreover, over the last 5 years we have built up a strong body of pilot data, generating the components required, in-particular the protein complexes, which are often the limiting step in these challenging projects.Understanding the molecular-level 'rules of engagement' of Cdc37 and the chaperone system with FGFR kinases and their altered forms will help us to understand not only the normal functioning of the chaperone system in respect of this important class of protein clients (RTKs), but also how it might become overwhelmed or subverted in acute or cumulative cellular stress. Such understanding can also assist in efforts to target the chaperone system selectively to treat cancers driven by oncogenic kinases that are 'addicted' to chaperone intervention to maintain their activity.