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

β-3肾上腺素受体（β-3 adrenoceptor，B3 AR）是治疗肥胖、膀胱过度活动症（overactive bladder，OAB）和2型糖尿病的重要靶点，属于G蛋白偶联受体（GPCR）超家族。GPCR是复杂且柔性的膜结合蛋白，包含约800个家族成员。B3 AR由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解和产热。虽然B3 AR是在40多年前发现的，但关于它的药理学还有很多东西要学，迄今为止，只有少数OAB的治疗方法获得了临床批准。特别地，最期望的B3 AR药物是激动剂（激活受体），并且这些配体的真实的时间结合行为是它们如何很好地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作用的关键组成部分。（Nagiri等人，2021，PDB：7 DH 5）。虽然人和犬的蛋白质序列具有约83%的总体相似性，但它们的差异可能导致其三维形状和配体相互作用的显著变化。因此，有必要开发一个可靠的人B3 AR模型，告知新的B3 AR选择性ligands.The建模工作将允许设计和合成的荧光配体库，将进行药理学表征的设计和合成。此外，有效的荧光配体将允许建立强大的基于荧光的B3 AR检测，映射更详细的配体结合动力学分析所需的功能响应。生成优化的人类B3 AR计算模型，并使用这些模型设计、合成和构建新型荧光配体库。在所有的β-肾上腺素受体亚型中发现新的荧光配体3。使用人类受体的计算模型进行虚拟筛选，以开发B3 AR的新型选择性配体支架。将新的多学科知识（结构，化学，药理学）应用于B3 AR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，建模和药理学的学科，以增加我们对B3 AR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.