The interaction of Uncoupling Protein 1 with regulatory ligands - new metabolite players in controlling brown fat thermogenic energy expenditure

哺乳动物通过分解食物中的营养物质来获得生存所需的能量。利用的大部分能量是通过线粒体中发生的生化过程产生的，线粒体是身体几乎所有细胞中的“能量工厂”。这些能量中心分解食物分子以产生ATP，ATP是一种通用的“燃料”分子，为细胞中的许多过程提供动力。虽然传统的“白色”脂肪被用来储存多余的食物营养素，但哺乳动物也可以产生专门的棕色脂肪，或“好脂肪”，其中含有解偶联蛋白1（UCP 1）的线粒体，这是一种独特的蛋白质，可以让营养卡路里作为热量“燃烧"，而不是制造ATP。该蛋白质的活性用于保护动物，包括牲畜（例如绵羊），特别是新生儿，免受寒冷温度的影响，但也发生在人类成年人中，它赋予健康益处。棕色脂肪与UCP1被发现在更瘦的人，当刺激消耗卡路里，从血液中去除葡萄糖和脂肪，对抗糖尿病和肥胖。这些疾病是一个重大的国家和国际问题，迫切需要改进的治疗方法。据估计，仅英国一国每年就因肥胖和相关疾病而花费约270亿英镑。全世界的研究人员都在寻找鼓励棕色脂肪发育的方法，将其作为改善健康的一种有前途的策略。然而，一个关键问题是，即使存在，UCP1在棕色脂肪细胞中也是无活性的，除非在响应特定的生理刺激（如低温）时特别“打开”，这是通过与控制活性的关键激活剂和抑制剂分子相互作用而发生的。人工激活蛋白质的方法有可能大大增加组织的卡路里周转能力及其相关的健康益处。UCP1不存在于其他主要组织中，是一个有吸引力的治疗靶点。这种蛋白质已经被研究了40多年，但直到最近，人们对它的工作原理知之甚少。UCP1是一种膜蛋白，在分离时不溶且通常不稳定，使其特别难以研究。然而，我们已经能够开发专门的方法来生产，分离和研究完整的UCP1。我们的工作已经阐明了蛋白质的组成，核心机制以及关键激活分子如何相互作用以诱导活性，使我们能够识别也可以激活蛋白质的新分子，例如特定药物。我们现在已经确定了UCP1的新功能，为抑制剂分子如何相互作用以控制蛋白质提供了可靠的模型。此外，我们还发现了一种全新的调节分子，在棕色脂肪代谢中很重要，它与UCP1相互作用，并可能表明一种重要的新功能。该项目旨在确定这些分子如何相互作用以影响UCP1活性和功能的分子细节。将使用生物物理和生物化学方法研究分离的UCP1，包括通过蛋白质稳定性的特定变化监测膜蛋白相互作用和蛋白质状态变化的专门测定。该蛋白质将在人工膜中进行研究，使用放射性标记方法追踪分子，并确定它们如何影响蛋白质。改变UCP1特定特征的分子生物学方法将用于确定分子在何处以及如何相互作用。还将进行先进的低温电子显微镜方法，以获得蛋白质3D分子结构的详细“快照”，为合理化UCP1调控的分子过程提供框架。这项工作将提供有关UCP1如何在脂肪组织中调节的分子细节，推进我们对膜蛋白功能，能量代谢和脂肪生物学的基本理解。这项工作也有可能定义新的生化途径，这有助于下游途径治疗目标的能量消耗，以对抗肥胖和代谢疾病。

Mammals gain energy to live through the breakdown of nutrients in food. The bulk of the energy harnessed occurs though biochemical processes that occur in mitochondria, the 'energy factories' present in just about all cells of the body. These energy hubs work to breakdown food molecules to generate ATP, a universal 'fuel' molecule that powers the many processes in cells. While conventional 'white' fat is used to store excess food nutrients, mammals can also produce specialised brown fat, or "good fat", which is packed with mitochondria containing Uncoupling protein 1 (UCP1), a unique protein that allows nutrient calories to be 'burned' off as heat instead of making ATP. Activity of the protein is used to protect animals including livestock (e.g. sheep), especially new-borns, from cold temperatures, but also occurs in human adults where it confers health benefits. Brown fat with UCP1 is found more in leaner people, and when stimulated expends calories, removing glucose and fat from the blood, combating diabetes and obesity. These conditions are a major national and international issue, urgently requiring improved therapies. Obesity and related conditions are estimated to cost the UK alone ~£27 billion per year.Researchers worldwide are looking into ways to encourage brown fat development as a promising strategy for improved health. However, a key issue is that, even when present, UCP1 is inactive in brown fat cells unless specifically 'switched on' in response to particular physiological stimulation such as cold temperatures, which occurs through interactions with key activator and inhibitor molecules that control activity. Methods to artificially activate the protein have potential to greatly increase the calorie turnover capacity of the tissue and its associated health benefits. UCP1 is not present in other major tissues and is an attractive therapeutic target. The protein has been studied for over 40 years, though, until recently, little was understood on how it works. UCP1 is a membrane protein, which are insoluble and often unstable when isolated, making them particularly difficult to study. However, we have been able to develop specialised methods to produce, isolate and study intact UCP1. Our work has clarified the protein's composition, core mechanism and how key activator molecules interact to induce activity, allowing us to identify new molecules that can also activate the protein, e.g. particular drugs.We have now identified novel features in UCP1 that provide a credible model of how inhibitor molecules interact to control the protein. Additionally, we have discovered a completely new class of regulator molecule, important in brown fat metabolism, that interacts with UCP1, and may indicate a major new function. This project aims to determine the molecular details of how these molecules interact to influence UCP1 activity and function. Isolated UCP1 will be investigated using biophysical and biochemical methods, including specialised assays to monitor membrane protein interactions and protein state changes through specific changes in the protein's stability. The protein will be studied in artificial membranes, using radiolabelling methods to tract molecules, and determine how they influence the protein. Molecular biology methods to change specific features of UCP1 will be used to identify where and how molecules interact. Advanced cryogenic electron microscopy methods will also be carried out to gain a detailed 'snap shot' of the protein's 3D molecular structure, to provide a framework for rationalising the molecular processes of UCP1 regulation. The work will provide molecular details on how UCP1 is regulated in fat tissue, advancing our fundamental understanding on membrane protein function, energy metabolism and fat biology. The work also has potential to define new biochemical pathways, which help downstream avenues to therapeutically target energy expenditure to combat obesity and metabolic disease.