Understanding the Molecular Mechanisms of Gating in TREK K2P K+ Channels

我们感知压力和温度变化的能力，以及我们检测各种化学物质的能力，不仅对正常的身体功能至关重要，而且对疼痛的感知也是必不可少的。了解控制这些过程的分子机制是感觉生物学最重要的目标之一。当我们的身体接触到潜在的危险刺激时，一系列复杂的事件启动了旨在最大限度地减少或避免伤害的天然保护机制。例如，极端温度、机械压力和化学刺激物(如酸)由聚集在感觉神经纤维末端的特殊感受器检测到，感觉神经纤维将这些刺激转化为电信号。然后，这些信号被迅速从身体中遥远的部位传输到脊髓和大脑的高级处理中心，后者解释这些信号以启动适当的反应。这些电信号由不同的细胞膜蛋白质组协调，这些细胞膜蛋白质被称为“离子通道”，人体中有数百种不同的离子通道。然而，现在有重要的证据表明，一类特殊的钾选择性通道在这一途径的许多不同阶段发挥着重要作用，包括对正常刺激和疼痛刺激的特定检测。尽管痛感通常有利于避免更大的整体组织损伤，但不想要的疼痛给个人、雇主、医疗保健系统和社会带来了巨大的负担。事实上，慢性疼痛对个人和社会经济的影响与其他既定的医疗保健优先事项一样大，甚至更大。因此，迫切需要更好、更有效的药物来治疗疼痛，而K2P通道是此类药物有吸引力的治疗靶点。在最近的一项重大进展中，我们现在已经使用X射线结晶学确定了两个人类K2P通道(Trek-1和Trek-2)的三维结构。我们还能够确定它们在不同构象状态下的结构，这为这些通道如何打开和关闭‘开关’电信号提供了新的见解。更重要的是，我们还能够解决带有抑制剂氟西汀(Prozac)的复合体中Trek-2的结构。虽然不是这种药物的主要靶点，但结合位点的鉴定为了解Trek-2通道门控和小分子调节的生物物理机制以及这种常用药物的一些潜在的非靶点效应提供了重要的洞察。在这个研究项目中，我们的目标是利用这些令人兴奋的新发现来定义K2P通道如何开放和关闭以控制电信号的结构基础，并了解其他小分子和生理相关的调控途径如何控制这一过程。与辉瑞Neusentis拟议的工业合作伙伴关系还为我们提供了各种化学工具、专业知识和资源，这些工具、专业知识和资源在标准的学术环境中通常是无法获得的。因此，我们处于独特的地位，能够追求这些目标。

Our ability to sense changes in pressure and temperature, as well as our ability to detect a wide variety of chemical agents, is not only essential for normal bodily function, but also for the perception of pain. Understanding the molecular mechanisms which control these processes represents one of the most important goals in sensory biology.When our body comes into contact with potentially dangerous stimuli a complex series of events initiates innate protective mechanisms designed to minimize or avoid injury. For example, extreme temperatures, mechanical stress, and chemical irritants such as acid are detected by specialised receptors clustered at the ends of sensory nerve fibres which convert these stimuli into electrical signals. These signals are then rapidly transmitted from distant sites in the body to the spinal cord and to higher processing centres in the brain which interpret these signals to initiate an appropriate response.These electrical signals are orchestrated by distinct groups of cell membrane proteins known as 'ion channels' of which there are many hundreds of different kinds in the human body. However, there is now significant evidence that one particular group known as the 'two-pore' or 'K2P' family of potassium selective channels play an important role at many different stages of this pathway, including the specific detection of both normal and painful stimuli.Although the sensation of pain is generally beneficial for the avoidance of greater overall tissue damage, unwanted pain confers a substantial burden on individuals, employers, healthcare systems and society in general. Indeed, the personal and socioeconomic impact of chronic pain is as great as, or greater, than that of other established healthcare priorities. There is therefore a tremendous need for better and more effective drugs for the treatment of pain and K2P channels represent attractive therapeutic targets for such drugs.In a major recent advance, we have now determined the 3D structures of two human K2P channels (TREK-1 and TREK-2) using X-ray crystallography. We were also able to determine their structures in different conformational states which has provided new insights into how these channels open and close to 'switch' electrical signals on and off.More importantly, we were also able to solve the structure of TREK-2 in complex with an inhibitor, fluoxetine (Prozac). Although not the principal target of this drug, identification of the binding site has provided an important insight into the biophysical mechanisms of TREK-2 channel gating and regulation by small molecules, as well as some of the potential off-target effects of this commonly prescribed drug.In this research project we aim to exploit these exciting new findings to define a structural basis for how K2P channels open and close to control electrical signals, and also to understand how other small molecules and physiologically relevant regulatory pathways control this process.The proposed industrial partnership with Pfizer Neusentis also provides us with access to a variety of chemical tools, expertise and resources not normally available in a standard academic environment, and therefore places us in a unique position to be able to pursue these goals.