Neuroprotection and Retinal Ganglion Cell Death

描述（由申请人提供）：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总体目标是了解青光眼中RGC中触发的特定细胞凋亡途径，以鉴定神经保护的靶点。在这个应用程序中，我们将建立一系列令人兴奋的新的观察，以测试我们的假设，钙调神经磷酸酶作为一个中央控制点在青光眼RGC死亡。在实验性青光眼的房水流出道阻塞（莫里森）大鼠模型中，我们观察到增加的IOP相关的凋亡级联，其涉及促凋亡Bad的去磷酸化、细胞色素c（cyt c）从线粒体的释放、半胱天冬酶激活和凋亡性视网膜神经节RGC损失。我们假设这些事件是钙调磷酸酶异常激活的结果。用钙调磷酸酶抑制剂FK 506（他克莫司，FDA批准的免疫抑制剂）治疗患有手术诱导的青光眼的大鼠，导致显著的神经保护性反应，使pBad去磷酸化、cyt c释放、RGC损失和轴突破坏钝化。此外，在眼压升高的大鼠和DBA/2 J小鼠青光眼模型中，我们仅在眼压升高的眼睛中观察到缺乏关键抑制结构域的截短形式的钙调神经磷酸酶的出现，因此具有组成性活性和促凋亡作用。新的初步数据与钙蛋白酶导致这种异常卵裂事件一致。这些结果表明，钙蛋白酶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控制青光眼RGC死亡的潜在节点。该假设在3个目的中进行测试：我们建议进一步评估IOP与RGC的钙蛋白酶和钙调神经磷酸酶激活和凋亡之间的关系，以了解IOP诱导的RGC死亡的早期事件（目的1）。我们将正式检验FK 506的作用机制是局部抑制钙调磷酸酶（目的2）的假设。我们将评估钙蛋白酶激活钙神经磷酸酶和半胱天冬酶的作用，并确定钙蛋白酶抑制是否在实验性青光眼中具有神经保护作用（目的3）。如果进一步证实，这些发现指向一种具有临床适用性的新型神经保护策略。

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.