TRP and AQP Channels: Modulation of Function, Raft Location by Membrane Lipids

瞬时受体电位香草酸1通道（TRPV 1）是伤害感受器的关键组分， 也是膀胱中的机械传感器和神经元中的机械传感器。水通道 水通道蛋白-4（AQP-4）存在于CNS中的神经胶质细胞中，并且对于CNS中的水稳态是关键的。 个脑袋尽管TRPV 1和AQP-4在正常的身体功能和一些疾病中都很重要， 在病理条件下，目前对这些通道的功能知之甚少 通过双层组成或它们的膜微区位置进行修饰。这些都是基本 因为许多离子通道的功能已被证明是由特定的修饰， 膜脂质如磷脂酰肌醇-4，5二磷酸（PIP 2），以及通过膜 由胆固醇的存在控制的材料性质。此外，一些渠道 被隔离在富含胆固醇的质膜微区中，称为筏。此应用程序使用 膜片钳电生理学和微管抽吸测量双层胆固醇的作用 浓度分别对TRPV 1和AQP-4的通道特性的影响。此外，各种 技术，包括共聚焦显微镜和冷冻断裂电子显微镜，将采用 确定TRPV 1和AQP-4的微区位置，并测试TRPV 1和AQP-4的可能机制。 将水道隔离成筏。我们的假设是：（1）特定的蛋白质-脂质和蛋白质- 蛋白质相互作用，包括通道的同源寡聚化，是分选的关键因素 微区之间的通道，（2）双层材料性质（由磷脂控制 烃链组成和胆固醇含量）调节TRPV 1和 AQP-4，和（3）酰化的多元胞质蛋白可以螯合关键的调节脂质， PIP 2进入膜双层的细胞质小叶中的筏结构域。

The Transient Receptor Potential Vanilloid 1 channel (TRPV1) is a key component of nociceptors and is also a mechanosensor in the urinary bladder and osmosensor in neurons. The water channel Aquaporin-4 (AQP-4) is found in glial cells in the CNS and is critical for water homeostasis in the brain. Although both TRPV1 and AQP-4 are important in normal body function and several pathological conditions, little is currently known about how the functions of these channels are modified by bilayer composition or their membrane microdomain locations. These are fundamental issues because the functions of many ion channels have been shown to be modified by specific membrane lipids such as phosphatidylinositol-4,5 bisphosphate (PIP2), as well as by membrane material properties controlled by the presence of cholesterol. Moreover, some channels are sequestered into cholesterol-rich plasma membrane microdomains called rafts. This application uses patch clamp electrophysiology and micropipette aspiration to measure the role of bilayer cholesterol concentration on the channel properties of TRPV1 and AQP-4, respectively. In addition, a variety of techniques, including confocal microscopy and freeze-fracture electron microscopy, will be employed to determine the microdomain locations of TRPV1 and AQP-4 and test possible mechanisms for the sequestering of channels into rafts. Our hypotheses are that: (1) specific protein-lipid and protein- protein interactions, including homo-oligomerization of the channels, are key factors in sorting channels between microdomains, (2) bilayer material properties (as controlled by phospholipid hydrocarbon chain composition and cholesterol content) modulate the function of both TRPV1 and AQP-4, and (3) acylated polybasic cytoplasmic proteins can sequester key regulatory lipids such as PIP2 into raft domains in the cytoplasmic leaflet of membrane bilayers.