Design and synthesis of novel fluorescent ligands for the Beta-3 adrenoceptor

β -3肾上腺素能受体（B3AR）是肥胖、膀胱过动症（OAB）和2型糖尿病的治疗靶点，属于G蛋白偶联受体（GPCR）超家族。gpcr是一种复杂而灵活的膜结合蛋白，由约800个家族成员组成。B3AR被内源性儿茶酚胺（如肾上腺素/去甲肾上腺素）激活，并介导关键的稳态过程，如脂肪分解和产热。尽管早在40年前就发现了B3AR，但关于其药理学还有很多需要了解的地方，迄今为止，只有少数治疗OAB的药物获得了临床批准。特别是，大多数期望的B3AR药物是激动剂（激活受体），这些配体的实时结合行为是它们如何刺激靶细胞类型（如脂肪细胞和平滑肌）以提供抗肥胖或膀胱松弛效果的关键组成部分。最近，犬B3AR结合OAB药物mirabegron的结构已被发表（Nagiri et al, 2021, PDB: 7DH5）。虽然人类和犬的蛋白质序列有83%的相似性，但它们的差异可能导致它们的三维形状和配体相互作用的显著差异。因此，有必要建立一个可靠的人体B3AR模型，为新的B3AR选择性配体的设计提供信息。建模工作将允许设计和合成一个将进行药理学表征的荧光配体库。此外，有效的荧光配体将允许建立强大的基于荧光的B3AR分析，将更详细的配体结合动力学分析映射到所需的功能响应。该项目的具体目标将是：1。生成人类B3AR的优化计算模型，并使用这些模型来设计、合成和表征一个新型荧光配体库。对所有β -肾上腺素能受体亚型的新荧光配体进行药理学表征。利用人类受体的计算模型进行虚拟筛选，以开发新的、选择性的b3ar配体支架。将新的多学科知识（结构、化学、药理学）应用于B3AR的有效和亚型选择性配体的开发。这个以化学生物学为重点的项目将跨越合成化学、建模和药理学等学科，以增加我们对B3AR生物学的理解。肾上腺素受体家族作为原型gpcr和关键治疗靶点的重要性意味着该项目将与未来的药物发现工作直接相关。

The Beta-3 adrenoceptor (B3AR) is an attractive therapeutic target for obesity, overactive bladder (OAB) and type-2 diabetes and belongs to the G protein-coupled receptor (GPCR) superfamily. GPCRs are complex and flexible membrane-bound proteins comprising ~800 family members. The B3AR is activated by endogenous catecholamines, such as epinephrine/norephinephrine and mediates critical homeostatic processes such as lipolysis and thermogenesis. Though the B3AR was identified >40 years ago, there is much to be learnt about its pharmacology and to-date only a handful of therapeutics for OAB have been clinically approved. In particular, most desired B3AR drugs are agonists (activating the receptors), and the real time binding behaviour of these ligands is a key component of how well they stimulate target cell types such as adipocytes and smooth muscle to provide an anti-obesity or bladder relaxation effect.Recently, the structure of the canine B3AR bound to the OAB drug mirabegron has been published (Nagiri et al, 2021, PDB: 7DH5). Whilst the human and canine protein sequences share ~83% overall similarity, their differences may confer significant variation in their three-dimensional shape and ligand interaction. Therefore, there is a need to develop a reliable human B3AR model to inform the design of new B3AR-selective ligands.The modelling work will allow the design and synthesis of a library of fluorescent ligands which will undergo pharmacological characterisation. Furthermore, effective fluorescent ligands will allow powerful fluorescence-based B3AR assays to be established, mapping more detailed analysis of ligand-binding kinetics to the desired functional responses.Specific aims of the project will be:1. To generate optimised computational models of the human B3AR and use these to design, synthesise and characterise a library of novel fluorescent ligands.2. To pharmacologically characterise the new fluorescent ligands at all beta-adrenoceptor subtypes3. To use the computational model of the human receptor to conduct a virtual screen for leads to develop novel, selective ligand scaffolds for the B3AR.4. To apply the new multidisciplinary knowledge (structures, chemistry, pharmacology) to the development of selected leads into potent and subtype-selective ligands for the B3AR.This chemical biology-focused project will span the disciplines of synthetic chemistry, modelling and pharmacology to increase our understanding of B3AR biology. The importance of the adrenoceptor family as prototypical GPCRs and key therapeutic targets means this project will be of direct relevance to future drug discovery efforts.