Role of Piezo1 in Mechanical Touch and Nociception

项目摘要 机械刺激的检测对于生物体的发育和生存至关重要。区分一个 无害的机械刺激和有害的机械力对于避免组织损伤和导致的疼痛是至关重要的。 机械刺激检测的皮肤机制已经受到相当大的关注，然而， 感觉神经元特异性的机械感受器是触觉和疼痛的基础，但还没有完全了解。压电1和 Piezo 2离子通道是真正的机械传导阳离子通道，在不同水平和组织中表达 包括角质形成细胞和感觉神经元。虽然感官 Piezo 2的神经元表达对于触觉刺激的外周感觉是必不可少的，相对而言， 它的近亲Piezo 1的作用。尽管早期的研究表明背根神经节（DRG）感觉神经元 显示相对稳健的Piezo 2表达和相对最小的Piezo 1表达，最近的证据表明， 提示Piezo 1由感觉神经元表达，并且它可以被机械地和非机械地调节。 在这些神经元中激活。这表明感觉神经元Piezo 1可能在功能上对检测 触觉和机械疼痛的躯体感觉系统。此外，虽然感觉神经元Piezo 2是 与机械性异常性疼痛有关，目前对感觉神经元Piezo 1的作用一无所知 涉及神经性或炎性疼痛病症的机械性异常性疼痛或痛觉过敏特征。在 在目前的建议中概述的实验，我将使用诱发行为分析，膜片钳电生理学， 和离体皮肤神经记录，以确定Piezo 1在感觉神经元介导的 通过使用具有感觉神经元的转基因小鼠在幼稚（非损伤）和疼痛（损伤）情况下的机械感觉 Piezo 1的特异性缺失。在目标1中，我将研究感觉神经元特异性Piezo 1对 机械感觉（Aim 1A）、机械诱发的外周纤维反应（Aim 1B）和DRG 对机械刺激的反应（目标1C）。在目标2中将采用类似的方法， Piezo 1在使用完全弗氏佐剂的炎症诱导的机械超敏反应中的作用，以及 保留胫神经损伤引起的周围神经病变。我来决定压电1是否会造成伤害- 诱导的机械异常性疼痛和痛觉过敏（目的2A），以及机械刺激诱导的 外周纤维（Aim 2B）和DRG感觉神经元（Aim 3C）。这些研究最终将揭示更多的 机械门控通道在触觉刺激转导中的作用。总体而言，拟议目标将揭示 感觉神经元Piezo 1在非损伤和损伤条件下对机械刺激检测的贡献， 可能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.