Neuroprotection and Retinal Ganglion Cell Death

描述(申请人提供)：神经保护和视网膜神经节细胞死亡本申请中提出的研究的主要目标是了解青光眼患者RGC中触发的特定细胞凋亡途径，以确定神经保护的靶点。在这项应用中，我们将建立在一系列令人兴奋的新观察结果的基础上，以验证我们的假设，即钙调神经磷酸酶在青光眼患者RGC死亡中起着中心控制点的作用。在实验性青光眼的房水流出阻塞型(Morison)大鼠模型中，我们观察到LOP相关的凋亡级联增加，包括促凋亡的Bad的去磷酸化，细胞色素c(Cytc)从线粒体释放，caspase激活和凋亡的视网膜神经节RGC丢失。我们假设这些事件是钙调神经磷酸酶异常激活的结果。用钙调神经磷酸酶抑制剂FK506(FDA批准的免疫抑制剂他克莫司)治疗手术诱导的青光眼大鼠，可以产生戏剧性的神经保护反应，抑制pBad去磷酸化，细胞色素c释放，RGC丢失和轴突破坏。此外，在眼压升高的大鼠和DBA/2J小鼠青光眼模型中，我们只在眼压升高的眼睛中观察到钙调神经磷酸酶的截断形式的出现，它缺乏关键的抑制结构域，因此具有结构性的活性和促凋亡作用。新的初步数据与Calain导致这一异常卵裂事件相一致。这些结果提示钙调神经磷酸酶和钙调神经磷酸酶的激活是压力诱导的RGC死亡的关键早期介质，而钙调神经磷酸酶的激活是控制青光眼RGC死亡的一个潜在的结点。这一假说的验证有三个目的：我们建议进一步评估眼压和钙蛋白与RGC钙调神经磷酸酶激活和凋亡的关系，以了解IOP诱导RGC死亡的早期事件(目标1)。我们将正式检验FK506的作用机制是局部抑制钙调神经磷酸酶的假设(目标2)。我们将评估钙调神经磷酸酶和半胱氨酸氨基转移酶激活钙蛋白酶的作用，并确定在实验性青光眼中抑制钙蛋白酶是否具有神经保护作用(目标3)。如果进一步证实，这些发现指向了一种具有临床适用性的新的神经保护策略。

DESCRIPTION (provided by applicant): 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 (cyt c) 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 that the mechanism of action of FK506 is local inhibition of calcineurin (aim 2). 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.