The role of mechanosensation in the vertebrate retina

视网膜神经节细胞和Müler胶质细胞特别容易受到机械力的影响，这种机械力会导致炎症 在青光眼等疾病中激活和RGC变性，但压力传导机制是 不是很清楚。早期的研究仅限于遗传、分子、细胞和 压力升高引起的RGC损伤和神经胶质细胞激活的行为后果。虽然很多人 研究表明，高血压眼的生化通路发生了改变，这种分子感受器可以传递 机械力仍然模糊不清，混淆了对压力诱导的时间依赖关系的解释 视网膜内的重塑会发生变化。关于青光眼压力损伤的主要假说集中在 力对筛板拉伸的作用小鼠发病但没有胶原蛋白 椎板。轴心假说也不能解释温和的压力升高如何导致早期的变化。 树突状结构和突触功能，或激活胶质细胞，而轴突运输没有明显变化。它也是 不知道生理水平的眼压如何影响RGC生理学，以及它们是否 足以与突触(光)反应结合。最后，尽管神经胶质细胞通常是最早的反应者 对于机械应力，促使这些细胞的机械敏感性的机制以及它们如何影响RGC 生理学在很大程度上仍然是未知的。 拟议的工作通过识别机械换能器并阐明它们的作用来解决这些混淆 在RGC和Müller中，神经胶质细胞钙稳态和多峰压力整合进入(病理性)生理 视网膜反应。该项目测试了树突、胞体和轴突的压力敏感性这一中心假设 视网膜节细胞和胶质细胞是由机械敏感离子通道控制的，它维持张力性动态平衡和 调节眼压变化时钙稳态、兴奋性和神经胶质递质的释放 也不会紧张。利用最近获得的数据并使用新的机械生物学工具，目标1将识别和 表征RGC质膜中的机械传感离子通道，并通过压力量化其激活 和基质拉伸，并检验机械应变从质膜传递的假设 通过细胞骨架进入细胞内部。在目标2中，我们建议刻画多通道机制 通过它，机械刺激与温度和突触(光)反应的影响相结合， 并检验有关RGC张力稳态调节的新假说。目标3将描述 机械诱导的胶质细胞激活影响RGC生理的分子机制，从而提供 深入了解青光眼等疾病的早期炎症机制。总而言之，拟议的 研究可能会通过揭示对急性视网膜反应的新机制来加深我们对视网膜功能的理解 和慢性机械力，并通过调和目前关于视网膜压力的不同假说 转导。 此外，这些研究将有助于理解神经退行性变，这是早期优化所必需的。 目前青光眼缺乏诊断和神经保护治疗。在过去几年里， 推测的机械感应离子通道的突变已被证明会导致许多人类疾病和 疾病，包括严重的发育不良、神经胶质血管异常和轴索神经病变，但它们对 由于缺乏基础研究，视觉信号尚不清楚。这些研究提供的信息可 从而有助于洞察视网膜疾病和转导的机械敏感机制 中枢神经系统内的机械应力。

Retinal ganglion cells and Müller glia are particularly susceptible to mechanical forces which drive inflammatory activation and RGC degeneration in diseases such as glaucoma, but the pressure transduction mechanisms are not well understood. Earlier studies have been limited to phenotyping the genetic, molecular, cellular and behavioral consequences of RGC injury and glial activation induced by elevated pressure. While many biochemical pathways were shown to be altered in hypertensive eyes, the molecular sensors that transduce mechanical forces remain obscure, confounding interpretations of time-dependence of pressure-induced remodeling changes within the retina. The dominant hypotheses about pressure injury in glaucoma focus on the role of forces on the stretch of the lamina cribrosa yet mice develop the disease but do not have the collagenous lamina. The axocentric hypotheses also cannot explain how mild pressure elevations induce early changes in dendritic architecture and synaptic function, or activate glia without visible changes in axonal transport. It is also not known how physiological levels of intraocular pressure might inform RGC physiology and whether they are sufficient to integrate with the synaptic (light) responses. Finally, although glia are often the earliest responder to mechanical stress, the mechanisms that impel mechanosensitivity to these cells and how they impact RGC physiology remain largely unknown. The proposed work addresses these confounds by identifying the mechanotransducers and elucidating their role in RGC and Müller glial calcium homeostasis and polymodal integration of pressure into the (patho)physiological retinal response. The project tests the central hypothesis that pressure sensitivity of dendrites, somata and axons of RGCs and glia is governed by mechanosensitive ion channels, which maintain tensile homeostasis and modulate calcium homeostasis, excitability and gliotransmitter release in response to changes in ocular pressure or strain. Leveraging the recently derived data and using novel mechanobiological tools, Aim 1 will identify and characterize mechanosensing ion channels in the RGC plasma membrane, quantify their activation by pressure and matrix stretch, and test the hypothesis that mechanical strains are transmitted from the plasma membrane into the cell interior through the cytoskeleton. In Aim 2 we propose to characterize the polymodal mechanism through which mechanical stimuli are integrated with the effects of temperature and synaptic (light) responses, and to test a novel hypothesis regarding the regulation of RGC tensile homeostasis. Aim 3 will characterize the molecular mechanisms whereby mechanically induced glial activation influences RGC physiology, thus providing insight into the early inflammatory mechanisms in diseases such as glaucoma. Taken together, the proposed studies may deepen our understanding of retinal function by uncovering new mechanisms that respond to acute and chronic mechanical forces and by reconciling currently disparate hypotheses about retinal pressure transduction. In addition, these studies will aid in the understanding of neurodegeneration that is required to optimize early diagnosis and neuroprotective treatment, which are currently lacking in glaucoma. During the last few years, mutations in putative mechanosensing ion channels have been shown to cause many human diseases and disorders, including severe dysplasias, gliovascular abnormalities and axonal neuropathies but their impact on visual signaling is unknown due to the absence of basic studies. The information provided by these studies may thus contribute insights into mechanosensitive mechanisms that underlie retinal disease as well as transduction of mechanical stress within the CNS.