Lipid Modulation of Potassium Channels

描述（由申请人提供）：我们的项目侧重于膜衍生的多不饱和脂肪酸（PUFA）如花生四烯酸对钾离子通道的调节。PUFA是重要的膳食脂质，并且在某些形式的细胞通讯之后作为脂质信号从膜释放。电压门控Kv 4通道在心脏的节律性放电、学习和兴奋性中是重要的。它们与癫痫、疼痛、记忆障碍和心律失常等疾病状态有关。TREK和TRAAK通道是钾通道K2 P家族的PUFA和机械敏感性成员。K2 P通道在维持细胞的静息兴奋性和对抗兴奋性的增加中是重要的。它们参与感受膜拉伸和渗透变化，并可提供抗缺血性损伤的保护。PUFA改变了这两种类型钾通道的活性，我们的研究目标是确定这在分子水平上是如何发生的，以便我们能够了解脂质信号如何影响神经活动。我们将以电生理学的方法来研究离子通道，并将使用通道的结构模型、计算工作和分子修饰来达到我们的研究目标。我们将确定PUFAs如何与Kv 4通道的不同门控状态或形状变化相互作用。为了在分子水平上测试这一点，我们将进行结构改变，改变通道的功能，并测量PUFA对通道的影响。我们将研究膜拉伸的变化和PUFA的影响之间的关系。最后，我们将使用我们建立的通道的结构模型来识别通道上可能的脂质结合口袋。对于K2 P通道，PUFA如何打开通道将通过从与哺乳动物通道远亲的海绵克隆的新型K2 P通道的策略性使用来测试。我们的初步数据表明，海绵通道是敏感的PUFAs，但不对膜中的机械力，这是相反的TREK和TRAAK哺乳动物K2 P通道，同时具有敏感性PUFAs和膜拉伸。海绵和哺乳动物通道的分子和生理学比较将用于确定PUFA敏感性所需的结构区域。由于K2 P通道受另一种脂质信号PIP 2调节，因此我们将评估两种脂质对K2 P通道可能的生理相互作用。主要研究者是一位经验丰富的离子通道生物学家，他在里士满大学6年内成功指导了24名本科研究生。她的实验室为本科生追求生物医学研究兴趣提供了良好的环境。除了研究目标之外，本项目的第二个目标是通过参与本研究计划，为本科生提供积极参与科学过程的宝贵机会。 公共卫生相关性：我们的项目致力于通过PUFA、omega-3脂肪酸（细胞膜的重要结构成分）和重要的膳食脂质调节某些钾离子通道的分子基础。这项研究对于脂质信号如何影响心脏肌肉和大脑某些区域的适当节律性放电，记忆障碍，疼痛，中风和心脏病发作期间的缺血性损伤，以及膜拉伸和组织盐浓度变化的生理和病理后果具有重要的健康意义。更好地了解某些脂质信号分子如何改变细胞的兴奋性是生物医学研究的一个重要目标。

DESCRIPTION (provided by applicant): Our project focuses on modulation of potassium ion channels by membrane-derived polyunsaturated fatty acids (PUFAs) such as arachidonic acid. PUFAs are important dietary lipids and are released from the membrane as lipid signals following certain forms of cellular communication. Voltage-gated Kv4 channels are important in rhythmic firing, learning, and excitability of the heart. They are implicated in disease states such as epilepsy, pain, memory disorders, and cardiac arrhythmia. TREK and TRAAK channels are PUFA- and mechanosensitive members of the K2P family of potassium channels. K2P channels are important in maintaining the resting excitability of cells and opposing increases in excitability. They are implicated in sensing membrane stretch and osmotic changes and may provide protection against ischemic damage. PUFAs modify the activity of both of these types of potassium channels and our research goal is to determine how this occurs at the molecular level so that we can understand how lipid signals impact neural activity. We will study the ion channels by electrophysiology and will use structural models, computational work, and molecular modifications of the channels to reach our research goal. We will determine how PUFAs interact with different gating states or shape changes of the Kv4 channel. To test this at the molecular level, we will make structural changes that alter how the channels function and will measure the impact on PUFA effects on the channel. We will examine the relationship between changes in membrane stretch and the effects of PUFAs. Finally, we will use a structural model of the channel which we built to identify possible lipid binding pockets on the channel. For K2P channels, how PUFAs open the channels will be tested by strategic use of a novel K2P channel cloned from a marine sponge which is distantly related to the mammalian channels. Our preliminary data suggest that the sponge channel is sensitive to PUFAs but not to mechanical forces in the membrane; this is in contrast to the TREK and TRAAK mammalian K2P channels which simultaneously possess sensitivity to PUFAs and membrane stretch. Molecular and physiological comparisons of the sponge and mammalian channels will be used to identify the structural regions that are required and sufficient for PUFA sensitivity. Because K2P channels are regulated by another lipid signal, PIP2, we will assess possible physiological interactions of the two lipids on the K2P channels. The principal investigator is an experienced ion channel biologist who has successfully mentored 24 undergraduate research students in 6 years at the University of Richmond. Her lab provides an excellent environment for undergraduates to pursue their interests in biomedical research. In addition to the research goal, a second goal of this project is to provide undergraduate students with valuable opportunities to participate actively in the scientific process by engagement in this research program. PUBLIC HEALTH RELEVANCE: Our project addresses the molecular basis for the regulation of certain potassium ion channels by PUFAs, omega-3 fatty acids which are important structural components of cell membranes and important dietary lipids. This research has important health implications for how lipid signals impact the proper rhythmic firing of heart muscle and some regions of the brain, memory disorders, pain, ischemic damage during stroke and heart attack, and the physiological and pathological consequences of membrane stretch and changes in tissue salt concentration. A better understanding of how certain lipid signaling molecules alter cellular excitability is an important goal in biomedical research.