Research Laboratory of Ophthalmology, West China Hospital, Sichuan University, Chengdu, 610041, China; College of Life Sciences, Sichuan Normal University, Chengdu, 610041, China.
Research Laboratory of Ophthalmology, West China Hospital, Sichuan University, Chengdu, 610041, China; Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, 610041, China.
Exp Eye Res. 2021 Nov;212:108785. doi: 10.1016/j.exer.2021.108785. Epub 2021 Sep 30.
Epigenetic gene enhancer of zeste homolog-2 (Ezh2) is reported to be associated with ocular neurodegenerative diseases; however, its underlying mechanism is poorly understood. The present study aimed to determine the role of 3-deazaneplanocin A (DZNep), which inhibits the transcription of Ezh2 by reducing the trimethylation of histone 3 lysine 27 (H3K27me3), in a retinal ganglion cell (RGC) degeneration model. Retinal damage was caused by intravitreal injection of N-methyl-D-aspartate (NMDA). DZNep and the vehicle control were intravitreally applied immediately post-NMDA injection. The severity of retinal damage was evaluated by immunofluorescence and terminal deoxyribonucleotide transferase (TdT)-mediated dUTP nick end labeling (TUNEL) staining, and retinal function was determined by electroretinogram (ERG). The transcriptome was examined by RNA sequencing and quantitative PCR (qPCR). Microglial cells were detected by immunohistochemistry. DZNep significantly prevented the cell death in the ganglion cell layer (GCL) and inner nuclear layer (INL) induced by NMDA. DZNep preserved the ERG b- and a-wave amplitudes and the b/a ratio in NMDA-treated mice. Moreover, RNA sequencing and qPCR revealed that neuroprotective genes were upregulated and played an important role in preserving retinal cells. In addition, DZNep inhibited the NMDA-induced activation of microglial cells. Our results suggest that H3K27me3 controls RGC survival at the transcriptional and epigenetic levels. The absence of H3K27me3 deposition upregulates neuroprotective genes to protect RGCs. Therefore, DZNep, which inhibits Ezh2 activity, could be a novel therapeutic treatment for ocular neurodegenerative diseases.
表观基因增强子的 zeste 同源物-2（Ezh2）被报道与眼部神经退行性疾病有关；然而，其潜在机制尚不清楚。本研究旨在确定 3-去氮杂胞苷（DZNep）的作用，DZNep 通过减少组蛋白 3 赖氨酸 27（H3K27me3）的三甲基化来抑制 Ezh2 的转录，在视网膜神经节细胞（RGC）变性模型中。通过玻璃体内注射 N-甲基-D-天冬氨酸（NMDA）引起视网膜损伤。DZNep 和载体对照在 NMDA 注射后立即玻璃体内给药。通过免疫荧光和末端脱氧核苷酸转移酶（TdT）介导的 dUTP 缺口末端标记（TUNEL）染色评估视网膜损伤的严重程度，并通过视网膜电图（ERG）测定视网膜功能。通过 RNA 测序和定量 PCR（qPCR）检查转录组。通过免疫组织化学检测小胶质细胞。DZNep 显著防止了 NMDA 诱导的神经节细胞层（GCL）和内核层（INL）细胞死亡。DZNep 保存了 NMDA 处理小鼠的 ERG b-和 a-波幅度和 b/a 比值。此外，RNA 测序和 qPCR 显示，神经保护基因上调并在保护视网膜细胞方面发挥重要作用。此外，DZNep 抑制了 NMDA 诱导的小胶质细胞激活。我们的结果表明，H3K27me3 在转录和表观遗传水平上控制 RGC 的存活。H3K27me3 缺失导致神经保护基因上调，从而保护 RGC。因此，抑制 Ezh2 活性的 DZNep 可能是眼部神经退行性疾病的一种新的治疗方法。
