North Texas Eye Research Institute, Ft, Worth, TX USA.
Mol Neurodegener. 2014 Apr 27;9:14. doi: 10.1186/1750-1326-9-14.
Central nervous system (CNS) trauma and neurodegenerative disorders trigger a cascade of cellular and molecular events resulting in neuronal apoptosis and regenerative failure. The pathogenic mechanisms and gene expression changes associated with these detrimental events can be effectively studied using a rodent optic nerve crush (ONC) model. The purpose of this study was to use a mouse ONC model to: (a) evaluate changes in retina and optic nerve (ON) gene expression, (b) identify neurodegenerative pathogenic pathways and (c) discover potential new therapeutic targets.
Only 54% of total neurons survived in the ganglion cell layer (GCL) 28 days post crush. Using Bayesian Estimation of Temporal Regulation (BETR) gene expression analysis, we identified significantly altered expression of 1,723 and 2,110 genes in the retina and ON, respectively. Meta-analysis of altered gene expression (≥1.5, ≤-1.5, p < 0.05) using Partek and DAVID demonstrated 28 up and 20 down-regulated retinal gene clusters and 57 up and 41 down-regulated optic nerve clusters. Regulated gene clusters included regenerative change, synaptic plasticity, axonogenesis, neuron projection, and neuron differentiation. Expression of selected genes (Vsnl1, Syt1, Synpr and Nrn1) from retinal and ON neuronal clusters were quantitatively and qualitatively examined for their relation to axonal neurodegeneration by immunohistochemistry and qRT-PCR.
A number of detrimental gene expression changes occur that contribute to trauma-induced neurodegeneration after injury to ON axons. Nrn1 (synaptic plasticity gene), Synpr and Syt1 (synaptic vesicle fusion genes), and Vsnl1 (neuron differentiation associated gene) were a few of the potentially unique genes identified that were down-regulated spatially and temporally in our rodent ONC model. Bioinformatic meta-analysis identified significant tissue-specific and time-dependent gene clusters associated with regenerative changes, synaptic plasticity, axonogenesis, neuron projection, and neuron differentiation. These ONC induced neuronal loss and regenerative failure associated clusters can be extrapolated to changes occurring in other forms of CNS trauma or in clinical neurodegenerative pathological settings. In conclusion, this study identified potential therapeutic targets to address two key mechanisms of CNS trauma and neurodegeneration: neuronal loss and regenerative failure.
中枢神经系统（CNS）创伤和神经退行性疾病会引发一系列细胞和分子事件，导致神经元凋亡和再生失败。使用啮齿动物视神经挤压（ONC）模型可以有效地研究与这些有害事件相关的致病机制和基因表达变化。本研究的目的是使用小鼠 ONC 模型：（a）评估视网膜和视神经（ON）基因表达的变化，（b）确定神经退行性发病途径，（c）发现潜在的新治疗靶点。
视神经挤压后 28 天，节细胞层（GCL）中仅有 54%的神经元存活。使用贝叶斯时间调节估计（BETR）基因表达分析，我们分别在视网膜和 ON 中鉴定出 1723 个和 2110 个基因的表达发生显著改变。使用 Partek 和 DAVID 对改变的基因表达（≥1.5，≤-1.5，p<0.05）进行荟萃分析，显示 28 个上调和 20 个下调的视网膜基因簇和 57 个上调和 41 个下调的视神经簇。调节后的基因簇包括再生变化、突触可塑性、轴突发生、神经元投射和神经元分化。从视网膜和 ON 神经元簇中选择基因（Vsnl1、Syt1、Synpr 和 Nrn1）的表达通过免疫组织化学和 qRT-PCR 定量和定性地检查它们与轴突神经退行性变的关系。
在 ON 轴突损伤后，许多有害的基因表达变化导致创伤诱导的神经退行性变。Nrn1（突触可塑性基因）、Synpr 和 Syt1（突触小泡融合基因）和 Vsnl1（与神经元分化相关的基因）是我们啮齿动物 ONC 模型中空间和时间下调的几个潜在独特基因。生物信息学荟萃分析确定了与再生变化、突触可塑性、轴突发生、神经元投射和神经元分化相关的显著组织特异性和时间依赖性基因簇。这些 ONC 诱导的神经元丢失和再生失败相关簇可以推断为发生在其他形式的中枢神经系统创伤或临床神经退行性病理状态中的变化。总之，本研究确定了潜在的治疗靶点，以解决中枢神经系统创伤和神经退行性变的两个关键机制：神经元丢失和再生失败。
