Hu Yifan, Chen Jieqiong, Wang Yuwei, Sun Junran, Huang Peirong, Feng Jingyang, Liu Te, Sun Xiaodong
Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), National Clinical Research Center for Ophthalmic Diseases, Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai, China.
Department of Ophthalmology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Cell Biol Int. 2023 Mar;47(3):584-597. doi: 10.1002/cbin.11959. Epub 2022 Nov 15.
Amyloid-β (Aβ) is thought to be a critical pathologic factor of retinal pigment epithelium (RPE) degeneration in age-related macular degeneration (AMD). Aβ induces inflammatory responses in RPE cells and recent studies demonstrate the N6-methyladenosine (m6A) regulatory role in RPE cell inflammation. m6A is a reversible epigenetic posttranslational modification, but its relationship with Aβ-induced RPE degeneration is yet to be thoroughly investigated. The present study explored the role and mechanism of m6A in Aβ-induced RPE degeneration model. This model was induced via intravitreally injecting oligomeric Aβ and the morphology of its retina was analyzed. One of m6A demethylases, the fat mass and obesity-associated (FTO) gene expression, was assessed. An m6A-messenger RNA (mRNA) epitranscriptomic microarray was employed for further bioinformatic analyses. It was confirmed that Aβ induced FTO upregulation within the RPE. Hypopigmentation alterations and structural disorganization were observed in Aβ-treated eyes, and inhibition of FTO exacerbated retinal degeneration and RPE impairment. Moreover, the m6A-mRNA epitranscriptomic microarray suggested that protein kinase A (PKA) was a target of FTO, and the PKA/cyclic AMP-responsive element binding (CREB) signaling pathway was involved in Aβ-induced RPE degeneration. m6A-RNA binding protein immunoprecipitation confirmed that FTO demethylated PKA within the RPE cells of Aβ-treated eyes. Altered expression of PKA and its downstream targets (CREB and brain-derived neurotrophic factor) was confirmed by quantitative reverse-transcription polymerase chain reaction and Western blot analyses. Hence, this study's findings shed light on FTO-mediated m6A modification in Aβ-induced RPE degeneration and indicate potential therapeutic targets for AMD.
淀粉样蛋白-β（Aβ）被认为是年龄相关性黄斑变性（AMD）中视网膜色素上皮（RPE）变性的关键病理因素。Aβ可诱导RPE细胞发生炎症反应，近期研究表明N6-甲基腺苷（m6A）在RPE细胞炎症中具有调节作用。m6A是一种可逆的表观遗传翻译后修饰，但其与Aβ诱导的RPE变性之间的关系尚待深入研究。本研究探讨了m6A在Aβ诱导的RPE变性模型中的作用及机制。该模型通过玻璃体内注射寡聚Aβ诱导建立，并对其视网膜形态进行分析。评估了m6A去甲基化酶之一，即脂肪量和肥胖相关（FTO）基因的表达。采用m6A信使核糖核酸（mRNA）表观转录组微阵列进行进一步的生物信息学分析。证实Aβ可诱导RPE内FTO上调。在Aβ处理的眼中观察到色素脱失改变和结构紊乱，抑制FTO会加剧视网膜变性和RPE损伤。此外，m6A-mRNA表观转录组微阵列提示蛋白激酶A（PKA）是FTO的一个靶点，PKA/环磷酸腺苷反应元件结合蛋白（CREB）信号通路参与了Aβ诱导的RPE变性。m6A-RNA结合蛋白免疫沉淀证实FTO在Aβ处理眼的RPE细胞内使PKA去甲基化。通过定量逆转录聚合酶链反应和蛋白质免疫印迹分析证实了PKA及其下游靶点（CREB和脑源性神经营养因子）表达的改变。因此，本研究结果揭示了FTO介导的m6A修饰在Aβ诱导的RPE变性中的作用，并指出了AMD潜在的治疗靶点。
