背景:慢性炎症在致盲性视网膜疾病如年龄相关性黄斑变性(AMD)和色素性视网膜炎(RP)中显著导致光感受器死亡。溴结构域和外结构域(BET)蛋白是表观遗传学的读者,作为关键的促炎因子。我们最近发现第一代BET抑制剂JQ1通过抑制cGAS-STING先天免疫减轻碘酸钠诱导的视网膜变性。这里,我们研究了dBET6的作用和机制,dBET6是一种蛋白水解靶向嵌合体(PROTAC)小分子,通过泛素-蛋白酶体系统选择性降解BET,在光诱导的视网膜变性中。
方法:将小鼠暴露于强光下诱导视网膜变性,并通过RNA测序和分子生物学确定cGAS-STING的激活。视网膜功能,形态学,在存在和不存在dBET6治疗的情况下检查光感受器活力和视网膜炎症。
结果:腹膜内注射dBET6导致视网膜中BET蛋白的快速降解,而没有可检测到的毒性。dBET6改善了光损伤(LD)后的视网膜反应性和视力。dBET6还抑制了LD诱导的视网膜巨噬细胞/小胶质细胞激活,穆勒细胞胶质增生,光感受器死亡和视网膜变性。单细胞RNA测序结果的分析显示cGAS-STING组分在视网膜小胶质细胞中表达。LD导致cGAS-STING途径的戏剧性激活,而dBET6抑制LD诱导的STING在反应性巨噬细胞/小胶质细胞中的表达和相关的炎症反应。
结论:这项研究表明,dBET6靶向降解BET通过抑制反应性视网膜巨噬细胞/小胶质细胞中的cGAS-STING发挥神经保护作用,有望成为治疗视网膜变性的新策略。
BACKGROUND: Chronic inflammation significantly contributes to photoreceptor death in blinding retinal diseases such as age-related macular degeneration (AMD) and retinitis pigmentosa (RP). Bromodomain and extraterminal domain (
BET) proteins are epigenetic readers that act as key proinflammatory factors. We recently found the first-generation
BET inhibitor JQ1 alleviated sodium iodate-induced retinal degeneration by suppressing cGAS-STING innate immunity. Here, we investigated the effects and mechanism of dBET6, a proteolysis‑targeting chimera (PROTAC) small molecule that selectively degrades
BET by the ubiquitin‒proteasome system, in light-induced retinal degeneration.
METHODS: Mice were exposed to bright light to induce retinal degeneration, and the activation of cGAS-STING was determined by RNA-sequencing and molecular biology. Retinal function, morphology, photoreceptor viability and retinal inflammation were examined in the presence and absence of dBET6 treatment.
RESULTS: Intraperitoneal injection of dBET6 led to the rapid degradation of
BET protein in the retina without detectable toxicity. dBET6 improved retinal responsiveness and visual acuity after light damage (LD). dBET6 also repressed LD-induced retinal macrophages/microglia activation, Müller cell gliosis, photoreceptor death and retinal degeneration. Analysis of single-cell RNA-sequencing results revealed cGAS-STING components were expressed in retinal microglia. LD led to dramatic activation of the cGAS-STING pathway, whereas dBET6 suppressed LD-induced STING expression in reactive macrophages/microglia and the related inflammatory response.
CONCLUSIONS: This study indicates targeted degradation of
BET by dBET6 exerts neuroprotective effects by inhibiting cGAS-STING in reactive retinal macrophages/microglia, and is expected to become a new strategy for treatment of retinal degeneration.