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异性细胞凋亡， 在青光眼的RGC中触发的通路，以确定神经保护的靶点。在这 应用程序，我们将建立一系列令人兴奋的新观察，以检验我们的假设，钙调神经磷酸酶的行为 作为青光眼中RGC死亡的中心控制点。在房水流出道阻塞（莫里森）大鼠中 在实验性青光眼模型中，我们观察到增加的IOP相关凋亡级联， 促凋亡Bad的去磷酸化，线粒体释放细胞色素c（cytc），半胱天冬酶 活化和凋亡性视网膜神经节RGC丢失。我们假设这些事件是 钙调神经磷酸酶异常激活钙调神经磷酸酶治疗大鼠青光眼的实验研究 抑制剂FK 506（他克莫司，FDA批准的免疫抑制剂）导致显著的神经保护作用， pBad去磷酸化、cyt c释放、RGC丢失和轴突破坏的钝化反应。 此外，在眼压升高的大鼠和DBA/2 J小鼠青光眼模型中，我们仅观察到， 眼压升高的眼睛出现截断形式的钙调神经磷酸酶，缺乏关键的抑制因子， 结构域，因此是组成性活性和促凋亡的。新的初步数据与 钙蛋白酶导致这种异常的卵裂事件。这些结果表明钙蛋白酶和钙调神经磷酸酶的激活 是压力诱导RGC死亡的关键早期介质，钙调磷酸酶激活是压力诱导RGC死亡的潜在机制。 控制青光眼中RGC死亡的节点。这一假设是在3个目标测试：我们建议， 进一步探讨眼压与视网膜神经节细胞钙蛋白酶、钙调神经磷酸酶激活及凋亡的关系 了解IOP诱导RGC死亡的早期事件（目的1）。我们将正式测试这个假设， FK 506的作用机制是局部抑制钙调神经磷酸酶（aim 2）。我们将评估钙蛋白酶的作用 激活钙调神经磷酸酶和半胱天冬酶，并确定钙蛋白酶抑制是否是神经保护性的， 实验性青光眼（aim 3）。如果得到进一步证实，这些发现指向一种新的神经保护剂， 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.