Role of Piezo1 in Mechanical Touch and Nociception

项目总结 机械刺激的检测对生物体的发育和生存至关重要。区分一个或多个 无害的机械刺激和有害的机械力对于避免组织损伤和由此产生的疼痛至关重要。 机械刺激检测的皮肤机制受到了相当大的关注，然而， 触觉和疼痛背后的感觉神经元特有的机械感受器还没有完全被理解。PIEZO1和 Piezo2离子通道是在不同水平和组织中表达的真正的机械转导通道 组成外周神经系统，包括角质形成细胞和感觉神经元。在感官上 Piezo2的神经元表达是触觉刺激的外周感觉所必需的，人们对此知之甚少 它的近亲Piezo1的作用。尽管早期的研究表明背根神经节(DRG)感觉神经元 显示相对较强的Piezo2表达和相对最小的Piezo1表达，更新的证据 提示Piezo1是由感觉神经元表达的，它可以是机械的和药理的 在这些神经元中被激活。这表明感觉神经元Piezo1可能在功能上对检测 身体感觉系统产生的触觉和机械性疼痛。此外，虽然感觉神经元Piezo2是 与机械性痛觉异常有关，目前尚不清楚感觉神经元Piezo1的作用 以神经性或炎症性疼痛为特征的机械性痛觉异常或痛觉过敏。在 在当前提案中概述的实验中，我将使用诱发行为分析、膜片钳电生理学、 和体外皮肤神经记录以确定Piezo1在感觉神经元介导中所起的作用 使用带有感觉神经元的转基因小鼠在幼稚(非损伤)和疼痛(损伤)环境中的机械感觉 Piezo1的特定缺失。在目标1中，我将研究感觉神经元特异性Piezo1对 机械感觉(目标1A)、机械诱发的外周纤维反应(目标1B)和背根神经节 对机械刺激的反应(目标1C)。类似的方法将在目标2中使用，以审问 PIEZO1治疗炎症诱导的机械过敏，使用完全弗氏佐剂，以及 备用胫神经损伤所致的周围神经病。我会确定Piezo1是否会导致受伤- 诱导的机械痛觉异常和痛觉过敏(Aim 2A)，以及机械刺激诱导的敏化 外周纤维(Aim 2B)和背根节感觉神经元(Aim 3C)。这些研究最终将揭示出 机械门控通道在触觉刺激传导中的作用。总体而言，拟议的目标将揭示 非损伤和损伤条件下感觉神经元Piezo1在机械刺激检测中的作用 潜在地揭示了治疗机械性疼痛的新途径。

PROJECT SUMMARY Detection of mechanical stimuli is crucial for organisms' development and survival. Discriminating between an innocuous mechanical stimulus and noxious mechanical force is vital to avoid tissue damage and resulting pain. Cutaneous mechanisms of mechanical stimulus detection have received considerable attention, however, the sensory neuron-specific mechanoreceptors underlying touch and pain are not fully understood. Piezo1 and Piezo2 ion channels are bona fide mechanotransduction cation channels expressed at various levels and tissues that comprise the peripheral nervous system, including keratinocytes and sensory neurons. While sensory neuron expression of Piezo2 is essential for peripheral sensation of tactile stimuli, relatively little is known about the role of its close relative, Piezo1. Despite early work suggesting dorsal root ganglia (DRG) sensory neurons display relatively robust Piezo2 expression and comparatively minimal Piezo1 expression, more recent evidence suggests that Piezo1 is expressed by sensory neurons and it can be mechanically and pharmacologically activated in these neurons. This suggests sensory neuron Piezo1 may be functionally important for detection of tactile and mechanical pain by the somatosensory system. Furthermore, while sensory neuron Piezo2 is implicated in mechanical allodynia, nothing is currently known about the contribution of sensory neuron Piezo1 to the mechanical allodynia or hyperalgesia characteristic of neuropathic or inflammatory pain conditions. In the experiments outlined in the current proposal, I will use evoked behavioral assays, patch clamp electrophysiology, and ex vivo skin-nerve recordings to determine the role Piezo1 plays in sensory neuron-mediated mechanosensation in naïve (non-injury) and pain (injury) contexts by using transgenic mice with sensory neuron specific deletion of Piezo1. In Aim 1, I will examine the contribution of sensory neuron-specific Piezo1 to mechanosensation (Aim 1A), to mechanically-evoked peripheral fiber responses (Aim 1B), and to DRG responses to mechanical stimuli (Aim 1C). Similar approaches will be used in Aim 2 to interrogate the role of Piezo1 in mechanical hypersensitivity induced by inflammation, using complete Freund's adjuvant, and peripheral neuropathy induced by spared tibial nerve injury. I will determine whether Piezo1 contributes to injury- induced mechanical allodynia and hyperalgesia (Aim 2A), and mechanical stimulus-induced sensitization of peripheral fibers (Aim 2B) and DRG sensory neurons (Aim 3C). These studies will ultimately reveal additional roles for mechanically-gated channels in tactile stimulus transduction. Overall, the proposed aims will reveal the contribution of sensory neuron Piezo1 to detection of mechanical stimuli in non-injury and injury conditions, potentially revealing new avenues for treatment of mechanical pain.