CryoEM structure of cannabinoid receptor CB2 with a biased ligands

G蛋白偶联受体（GPCRs）是细胞内外信号的传递者。由于它们在细胞信号传导中的关键作用，它们是三分之一上市药物的目标。具有激动剂活性的配体的结合稳定GPCR的特定构象，这导致G蛋白和抑制蛋白介导的信号传导途径的活化。现在人们普遍认识到，“偏向”疗法，它只激活一个子集的特定信号传导途径，提供了显着的进步，现有的药物与完全激动剂或拮抗剂活性，由于更高的特异性的行动和更低的副作用。目前正在大力开发这类药物。然而，由于GPCR的混杂性和信号传导途径的复杂性，通常难以将观察到的候选偏向配体的作用归因于一种特定的信号传导模式。大麻素受体CB 2是治疗炎症性疾病、疼痛、骨质疏松症、动脉粥样硬化和脑肿瘤的有价值的药物靶标。我们最近确定了几个CB2配体，显示出强烈的偏见信号传导。互补诱变的结果表明，配体结合位点含有“热点”，介导的配体结合诱导的信号，并可能影响偏置信号。我们的主要假设是CB2配体通过配体结合口袋中的特异性相互作用发挥其作用和信号传导偏好。为了验证这一假设，我们需要有偏见的配体如何结合受体的结构信息。该项目将专注于使用CryoEM获得CB2受体与几种偏向配体复合的CryoEM结构。学生将学习哺乳动物细胞培养，膜蛋白生物化学和单粒子CryoEM技术。这些技能将与培训药理学试验补充，以验证受结构数据启发的新型配体的药理学。该项目的结果将建立受体诱导的结构变化与其信号传导特性之间的联系，并将促进下一代“偏向”疗法的发展。该学生将被嵌入膜蛋白和受体中心（COMPARE），这是伯明翰大学和诺丁汉大学之间的独特合作，是欧洲和全球GPCR卓越中心。它提供了一个由40多名博士生和博士后组成的充满活力的社区，以发展研究和演讲技能以及学术网络。此外，他们将在RCH从事CryoEM结构测定工作，并进一步扩大他们的学术网络。

G protein-coupled receptors (GPCRs) are transmit signals between the cellular environment and its interior. Due to their key role in cellular signalling, they are the target of a third of marketed drugs. Binding of ligands with agonist activity stabilises particular conformations of a GPCR, which result in the activation of G proteins and arrestin-mediated signalling pathways. It is now widely recognized that "biased" therapeutics, which activate only a subset of specific signalling pathways, offer significant advancement over existing drugs with full agonist or antagonist activity due to higher specificity of action and lower side effects. Significant efforts are now being directed to develop such drugs. However, due to the promiscuity of the GPCRs and complexity of the signalling pathways, it is often difficult to attribute the observed effects of candidate biased ligands to one particular mode of signalling. Cannabinoid receptor CB2 is a valuable drug target for treating inflammatory diseases, pain, osteoporosis, atherosclerosis and brain tumours. We recently identified several CB2 ligands that show strong biased signalling profile. Complementary mutagenesis results suggested that the ligand binding site contains "hot-spots" that mediate signalling induced by the ligand binding, and are likely to affect biased signalling. Our main hypothesise is that CB2 ligands exert their action and signalling bias via specific interactions in the ligand binding pocket. To test this hypothesis, we need structural information of how biased ligands bind the receptor. The project will focus on obtaining a CryoEM structure of CB2 receptor in complex with several biased ligands using CryoEM. The student will learn mammalian cell culture, membrane protein biochemistry and single-particle CryoEM techniques. These skills will be complemented with training pharmacological assays to characterise pharmacology of novel ligands inspired by the structural data. The results of the project will establish a link between the structural changes induced in receptors to their signalling properties and would promote the development of the next generation of "biased" therapeutics.The student will be embedded in the Centre of Membrane Proteins and Receptors (COMPARE), a unique collaboration between the Universities of Birmingham and Nottingham, a centre of GPCR excellence in Europe and worldwide. It offers a vibrant community of over 40 PhD students and post-docs to develop research and presentation skills and an academic network. Additionally, they will work at RCH on CryoEM structure determination and further expanding their academic network.