Neuroprotection and Retinal Ganglion Cell Death

神经保护与视网膜神经节细胞死亡 在本申请中提出的研究的首要目标是了解特定的细胞凋亡 青光眼患者RGC中触发的通路，以确定神经保护的靶点。在这 应用，我们将建立在一系列令人兴奋的新观察结果的基础上来验证我们的假设，即钙调神经磷酸酶起作用 作为青光眼患者RGC死亡的中心控制点。在房水流出障碍(Morison)大鼠中 在实验性青光眼模型中，我们观察到LOP相关的凋亡级联增加，涉及 促凋亡Bad去磷酸化，线粒体细胞色素c(Cytc)释放，caspase 视网膜神经节RGC的活化和凋亡丢失。我们假设这些事件是一个后果 钙调神经磷酸酶的异常激活。钙调神经磷酸酶治疗大鼠青光眼的实验研究 抑制剂FK506(FDA批准的免疫抑制剂他克莫司)可产生显著的神经保护作用 反应表现为pBad去磷酸化钝化、细胞色素c释放、RGC丢失和轴突破坏。 此外，在高眼压大鼠和DBA/2J小鼠青光眼模型中，我们只观察到 眼压升高的眼睛出现一种截断形式的钙调神经磷酸酶，缺乏关键的抑制作用 结构域，因此具有结构性活性和促凋亡性。新的初步数据与 引起这一不正常卵裂事件的钙蛋白酶。这些结果表明，钙蛋白和钙调神经磷酸酶激活 是压力诱导的RGC死亡的关键早期介质，钙调神经磷酸酶激活是一种潜在的 控制青光眼视网膜色素上皮细胞死亡的结点。这一假设在三个目标上得到了检验：我们建议 进一步探讨眼压和钙蛋白与视网膜神经节细胞钙调神经磷酸酶激活和细胞凋亡的关系 了解眼压致RGC死亡的早期事件(目标1)。我们将正式检验这一假设 FK506的作用机制是局部抑制钙调神经磷酸酶(AIM2)。我们将评估钙调蛋白的作用 钙调神经磷酸酶和半胱氨酸天冬氨酸酶的激活，并确定抑制钙调蛋白是否具有神经保护作用 实验性青光眼(目标3)。如果进一步证实，这些发现指向一种新的神经保护 具有临床适用性的策略。

Neuroprotection and Retinal Ganglion Cell Death The overarching goal of the studies proposed in this application is to understand the specific apoptosis pathways that are triggered in RGC in glaucoma in order to identify targets for neuroprotection. In this application, we will build on a series of exciting new observations to test our hypothesis that calcineurin acts as a central control point in RGC death in glaucoma. In the aqueous outflow obstruction (Morrison) rat model of experimental glaucoma, we observe an increased lOP-related apoptotic cascade that involves dephosphorylation of proapoptotic Bad,release of cytochrome c (cytc) from the mitochondria, caspase activation and apoptotic retinal ganglion RGC loss. We hypothesize that these events are a consequence of aberrant calcineurin activation. Treatment of rats with surgically induced glaucoma with the calcineurin inhibitor, FK506 (tacrolimus, an FDA-approved immunosuppressant), leads to a dramatic neuroprotective response with blunting of the pBad dephosphorylation, cyt c release, RGC loss and axonal destruction. Moreover, in both rats with elevated IOP and the DBA/2J mouse model of glaucoma, we observe only in eyes with elevated IOP the appearance of a truncated form of calcineurin that lacks a key inhibitory domain, and is therefore constitutively active and proapoptotic. New preliminary data are consistent with calpain causing this abnormal cleavage event. These results suggest that calpain and calcineurin activation are critical early mediators of pressure-induced RGC death and that calcineurin activation is a potential nodal point in the control of RGC death in glaucoma. This hypothesis is tested in 3 aims: We propose to further evaluate the relationship between IOP and calpain and calcineurin activation and apoptosis of RGC to understand early events in IOP induced RGC death (aim 1). We will formally test the hypothesis thta the mechanism of action of FK506 is local inhibition of calcineurin (aim2). We will assess the role of calpain activation of calcineurin and of caspases, and determine whether calpain inhibition is neuroprotective in experimental glaucoma (aim 3). If further confirmed, these findings point towards a novel neuroprotective strategy with clinical applicability.