Targeting BAX as a Therapeutic for Protection of Retinal Ganglion Cells

BAX是一种促凋亡蛋白，在视网膜神经节细胞内源性凋亡的执行中起关键作用 （RGCs）视神经损伤后，这表明靶向BAX可能是一种有效的治疗策略， 神经保护然而，据报道，降低BAX水平仅提供了短暂的保护， 青光眼小鼠模型中的轴突。这种短暂的保护是否足以让轴突 消除原有压力源后恢复，尚未得到验证。 目的1将测试BAX减少对轴突存活和/或恢复的能力的保护作用。 模拟高眼压（OHT）患者所经历的降眼压治疗的模型。两 小鼠中的诱导型OHT模型，微珠注射和类固醇诱导的OHT，将在两个野生型中使用。 型和Bax+/-小鼠（其中减少的BAX更可能模拟人类治疗）。在两种模型中，IOP水平 可以在期望的间隔之后恢复正常。我们将测试降低BAX蛋白水平是否既能减少索马， 和轴突病理，并且保护轴突功能或允许功能恢复。我们亦会研究 实验性眼压控制（CEI）。CEI的优点是它使IOP损伤正常化， 消除了与其他OHT模型相关的可变IOP的混杂因素。 背根神经节细胞含有BAX依赖的退行性通路，其在神经节形成的早期和之前被激活。 其他更好的特征分解代谢反应涉及钙流入。这条通路是由一种BH 3- 只有蛋白质在细胞索马中产生，然后运输到轴突。RGC轴突中的类似机制 这可能解释了BAX减少的部分保护作用。目标2将评估这一途径在 离体视神经中将诱导变性的RGC轴突。我们还将询问轴突， 激活BAX的关键分子和BAX下游作用分子的存在和定位 activation.初步研究表明，BH 3-only蛋白NOXA可能是BAX的重要调节因子 激活轴突。我们将详细探讨这一点，使用Noxa缺陷小鼠诱导OHT。 受保护的RGC沉默功能所需基因的转录。新的研究表明， 在缺乏细胞的死亡过程中，在8周后关闭。因此，细胞可以分为两种 类别，那些积极死亡（AD模式）和那些已经静止（Q模式）。Aim 3将进行调查 如果Q模式的细胞对3次重新激活它们的尝试有不同的反应，包括使用HDAC抑制剂， 减弱RGC特异性基因表达的转录沉默，添加酵母聚糖和CPT-cAMP 诱导再生，或上调转录因子，可以指定视网膜前体细胞， RGC。这些实验将在视神经急性损伤后的RGC上进行，视神经作为 一种模型，其中再生对于治疗结果具有高优先级。

BAX is a proapoptotic protein, which is critical for the execution of intrinsic apoptosis in retinal ganglion cells (RGCs) after optic nerve damage, suggesting that targeting BAX may be an effective therapeutic strategy for neuroprotection. It has been reported, however, that reducing BAX levels only provides a transient protection to axons in a mouse model of glaucoma. Whether or not this transient protection is sufficient to allow axons to recover after elimination of the original stressor, has not been tested. Aim 1 will test the protective effect of BAX reduction on the ability of axons to survive and/or recover in models that mimic the IOP-lowering therapy experienced by patients with ocular hypertension (OHT). Two models of inducible OHT in mice, microbead injection and steroid induced OHT, will be employed on both wild type and Bax+/- mice (where reduced BAX more likely mimics a human treatment). In both models IOP levels can be returned to normal after a desired interval. We will test if reducing BAX protein levels both reduces soma and axon pathology, and either protects axon function, or allows functional recovery. We will also examine the effects of controlled experimental IOP (CEI). The advantage of CEI is that it normalizes the IOP insult, which eliminates the confounding factors of variable IOP associated with other models of OHT. Dorsal Root Ganglion cells contain a BAX-dependent degenerative pathway that is activated early and before other more well-characterized catabolic reactions involving calcium influx. This pathway is activated by a BH3- only protein produced in the cell soma and then transported to the axon. A similar mechanism in RGC axons may explain the partial protective effect of BAX reduction. Aim 2 will evaluate the presence of this pathway in RGC axons where degeneration will be induced in optic nerves ex vivo. We will also interrogate axons for the presence and localization of key molecules that activate BAX, and molecules that act down-stream of BAX activation. Preliminary studies suggest that the BH3-only protein NOXA may be an important regulator of BAX activation in axons. We will explore this in detail using Noxa-deficient mice subjected to induced OHT. Protected RGCs silence transcription of genes required for function. New studies show that the committed process of dying in Bax-deficient cells, is shut down after 8 weeks. Thus cells can be classified into two categories, those actively dying (AD-mode) and those that have gone quiescent (Q-mode). Aim 3 will investigate if cells in Q-mode respond differently to 3 attempts to reactivate them, including using HDAC inhibitors to attenuate the transcriptional silencing of RGC-specific gene expression, the addition of Zymosan and CPT-cAMP to induce regeneration, or the up-regulation of transcription factors that can specify retinal precursor cells as RGCs. These experiments will be conducted on RGCs after acute damage to the optic nerve, which serves as a model where regeneration has a high priority for a therapeutic outcome.