Data_Sheet_3_Low Expression of YTH Domain-Containing 1 Promotes Microglial M1 Polarization by Reducing the Stability of Sirtuin 1 mRNA.docx

The N6-methyladenosine (m6A) modification is the most abundant posttranscriptional mRNA modification in mammalian cells and is dynamically modulated by a series of “writers,” “erasers,” and “readers.” Studies have shown that m6A affects RNA metabolism in terms of RNA processing, nuclear export, translation, and decay. However, the role of the m6A modification in retinal microglial activation remains unclear. Here, we analyzed the single-cell RNA sequencing data of retinal cells from mice with uveitis and found that the m6A-binding protein YTH domain-containing 1 (YTHDC1) was significantly downregulated in retinal microglia in the context of uveitis. Further studies showed that YTHDC1 deficiency resulted in M1 microglial polarization, an increased inflammatory response and the promotion of microglial migration. Mechanistically, YTHDC1 maintained sirtuin 1 (SIRT1) mRNA stability, which reduced signal transducer and activator of transcription 3 (STAT3) phosphorylation, thus inhibiting microglial M1 polarization. Collectively, our data show that YTHDC1 is critical for microglial inflammatory response regulation and can serve as a target for the development of therapeutics for autogenic immune diseases.

N6-甲基腺嘌呤（N6-methyladenosine，m6A）修饰是哺乳动物细胞中最为丰富的转录后mRNA修饰，由一系列“写入器”（writers）、“擦除器”（erasers）与“读取器”（readers）动态调控。现有研究表明，m6A可通过RNA加工、核输出、翻译及降解等过程影响RNA代谢。然而，m6A修饰在视网膜小胶质细胞活化中的作用仍未明确。本研究分析了葡萄膜炎小鼠视网膜细胞的单细胞RNA测序（single-cell RNA sequencing）数据，发现葡萄膜炎状态下视网膜小胶质细胞中的m6A结合蛋白YTH结构域包含蛋白1（YTH domain-containing 1，YTHDC1）显著下调。后续实验证实，YTHDC1缺失会诱导M1型小胶质细胞极化、增强炎症反应并促进小胶质细胞迁移。机制层面，YTHDC1可维持沉默信息调节因子1（sirtuin 1，SIRT1）的mRNA稳定性，进而降低信号转导与转录激活因子3（signal transducer and activator of transcription 3，STAT3）的磷酸化水平，最终抑制小胶质细胞M1极化。综上，本研究数据表明YTHDC1在调控小胶质细胞炎症反应中发挥关键作用，可作为自体免疫性疾病治疗药物的开发靶点。