Determining the role of the mechano-activated potassium channel TRAAK at nodes of Ranvier

摘要 通过郎维叶结的动作电位传播是神经系统功能的中枢。理解这一 该过程对于开发电信号的节点病理学的改进治疗是必不可少的，包括 多发性硬化、格林-巴利综合征、中风、脊髓损伤和青光眼。跳跃传导 从一个节点到下一个节点的动作电位跳跃-自从它被发现以来就被描述为纯粹的 电现象。这项建议旨在调查它是否也基本上是机械性质的。 机械激活的双孔结构域钾通道TRAAK仅在淋巴结表达。 兰维尔TRAAK对电压不敏感，但对膜张力敏感，细胞肿胀增加 TRAAK介导的钾电流高达一百倍。尽管如此，TRAAK的机械激活是否 与尖峰传播相关的信息是未知的。利用有机化学、分子生物物理学和 神经生理学，这项建议将研究如何机械激活TRAAK电流有助于行动 潜在的传播、速度和可靠性。为了选择性地控制TRAAK通道， 配体（PTL）将被设计，合成和优化，以最大限度地时空精确阻断 TRAAK电流。在泄漏和机械激活的开放TRAAK通道中筛选PTL拴系位点将 能够识别状态特异性PTL·Cys-TRAAK对，并精确调节基础和/或 机械激活的TRAAK电流。使用这些工具，TRAAK对动作电位传播的贡献 将在典型条件下的有髓鞘视神经中表征，并响应于机械 扰动这些实验将阐明TRAAK在棘波传播中的作用， 表明机械力是节点复极的核心，对治疗具有广泛的意义。 神经节病理学和神经元通讯领域的研究。

Abstract Action potential propagation through nodes of Ranvier is central to nervous system function. Understanding this process is essential for developing improved treatments for nodal pathologies of electrical signaling including multiple sclerosis, Guillain-Barré syndrome, stroke, spinal injury, and glaucoma. Saltatory conduction—the jumping of the action potential from one node to the next—has been described since its discovery as a purely electrical phenomenon. This proposal aims to investigate whether it is also fundamentally mechanical in nature. The mechano-activated two-pore domain potassium channel TRAAK is exclusively expressed at nodes of Ranvier. TRAAK is insensitive to voltage, but acutely tuned to membrane tension, with cell swelling increasing TRAAK-mediated potassium currents up to one hundred-fold. Still, whether mechanical activation of TRAAK is relevant to spike propagation is unknown. Using a combination of organic chemistry, molecular biophysics, and neurophysiology, this proposal will examine how mechanically activated TRAAK currents contribute to action potential propagation, speed, and reliability. To selectively control TRAAK channels, photoswitchable tethered ligands (PTLs) will be designed, synthesized, and optimized for maximal spatiotemporally precise block of TRAAK current. Screening of PTL tethering sites in leak and mechano-activated open TRAAK channels will enable the identification of state-specific PTL·Cys-TRAAK pairs and the precise modulation of basal and/or mechano-activated TRAAK currents. Using these tools, TRAAK's contributions to action potential propagation will be characterized in myelinated optic nerve under typical conditions and in response to mechanical perturbation. These experiments will both elucidate the role of TRAAK in spike propagation and, potentially, demonstrate that mechanical force is central to node repolarization, with broad implications for the treatment of nodal pathologies and the field of neuronal communication as a whole.