Transient Receptor Potential Channels and Neurodegeneration in Glaucoma

描述（由申请人提供）：我们的长期目标是了解青光眼神经变性的机制，并找到新的方法来减轻它。青光眼的视力丧失涉及视网膜神经节细胞（RGC）神经元通过两种广泛的退行性程序的选择性丧失：在视神经投射中，影响RGC轴突，在视网膜中，影响RGC树突、突触和细胞体。变性源于对眼压（IOP）的敏感，但降低眼压的治疗方案并不总是减缓进展。因此，要在神经元水平上进行干预，需要更好地了解RGC通路如何响应与io相关的应激源，以及这种反应是否包括对抗功能丧失的机制。在这个项目中，我们的目标集中在表征一种涉及TRPV1（瞬时受体电位香草素-1）受体的机制。我们的中心假设是TRPV1通过增强IOP相关应激反应的兴奋性活动来对抗RGC变性。在其他系统中，神经元膜上TRPV1的增加维持了细胞骨架的完整性，并通过增强Ca2+活性来增强突触兴奋。我们提出TRPV1在RGCs中也有类似的作用，已经确定TRPV1在RGCs中是一个强大的Ca2+通道，当激活时，会增加兴奋并影响它们的存活。我们将使用急性（微珠闭塞）和慢性（DBA2J）小鼠模型来验证我们的假设，我们已经绘制了关键的RGC退行性结局指标。在Aim 1中，我们将把急性模型应用于TRPV1敲除小鼠，以确定TRPV1依赖的轴突和视网膜结果及其在RGC变性中的进展。在Aim 2中，我们将比较急性和慢性模型中TRPV1表达和定位的io依赖性变化，并将这些变化与RGC亚细胞区室联系起来，以确定TRPV1作用的结构相关性。对于Aim 3，我们将在两个模型中测量IOP的变化如何影响TRPV1对RGC兴奋的贡献，并确定调节TRPV1的敏感性是否能促进生存。这些新的研究将利用我们已经完成的TRPV1研究和一个独特的工具箱来阐明一个新的级联，可以对抗和减缓与青光眼相关的应力引起的功能丧失。

DESCRIPTION (provided by applicant): Our long-term goal is to understand the mechanisms of neurodegeneration in glaucoma and find new ways to abate it. Vision loss in glaucoma involves selective loss of retinal ganglion cell (RGC) neurons through two broad degenerative programs: in the optic projection, affecting RGC axons, and in the retina, affecting RGC dendrites, synapses and cell bodies. Degeneration arises from sensitivity to intraocular pressure (IOP), but IOP-lowering regimens do not always slow progression. Thus, to intervene at the neuronal level requires a better understanding of how the RGC pathway responds to IOP-related stressors and whether this response includes mechanisms to counter loss of function. Our objective in this project is focused on characterizing one such mechanism involving the TRPV1 (transient receptor potential vanilloid-1) receptor. Our central hypothesis is that TRPV1 counters RGC degeneration by enhancing excitatory activity in response to IOP- related stress. In other systems, increased TRPV1 at the neuronal membrane maintains cytoskeletal integrity and augments synaptic excitation by enhancing Ca2+ activity in response to stress. We propose a similar role for TRPV1 in RGCs, having established TRPV1 as a robust Ca2+ channel in RGCs that, when activated, increases excitation and influences their survival. We will test our hypothesis using both acute (microbead occlusion) and chronic (DBA2J) mouse models for which we have mapped key RGC degenerative outcome measures. For Aim 1, we will apply the acute model to a TRPV1 knock-out mouse to identify TRPV1- dependent axonal and retinal outcomes and their progression in RGC degeneration. For Aim 2, we will compare in the acute and chronic models IOP-dependent changes in TRPV1 expression and localization and link these changes to RGC subcellular compartments to identify structural correlates of TRPV1's action. For Aim 3 we will measure in both models how changes in IOP influence TRPV1's contribution to RGC excitation and determine if modulating TRPV1 sensitivity promotes survival. These new studies will capitalize on our completed studies of TRPV1 and a unique toolbox already in place to illuminate a novel cascade that could counter and slow stress-induced loss of function associated with glaucoma.