Excessive cytokine activity underlies many autoimmune conditions, particularly through the interleukin-17 (IL-17) and tumor necrosis factor–α (TNFα) signaling axis. Both cytokines activate nuclear factor κB, but appropriate induction of downstream effector genes requires coordinated activation of other transcription factors, notably, CCAAT/enhancer binding proteins (C/EBPs). Here, we demonstrate the unexpected involvement of a posttranscriptional “epitranscriptomic” mRNA modification [N6-methyladenosine (m⁶A)] in regulating C/EBPβ and C/EBPδ in response to IL-17A, as well as IL-17F and TNFα. Prompted by the observation that C/EBPβ/δ-encoding transcripts contain m⁶A consensus sites, we show that Cebpd and Cebpb mRNAs are subject to m⁶A modification. Induction of C/EBPs is enhanced by an m⁶A methylase “writer” and suppressed by a demethylase “eraser.” The only m⁶A “reader” found to be involved in this pathway was IGF2BP2 (IMP2), and IMP2 occupancy of Cebpd and Cebpb mRNA was enhanced by m⁶A modification. IMP2 facilitated IL-17–mediated Cebpd mRNA stabilization and promoted translation of C/EBPβ/δ in response to IL-17A, IL-17F, and TNFα. RNA sequencing revealed transcriptome-wide IL-17–induced transcripts that are IMP2 influenced, and RNA immunoprecipitation sequencing identified the subset of mRNAs that are directly occupied by IMP2, which included Cebpb and Cebpd. Lipocalin-2 (Lcn2), a hallmark of autoimmune kidney injury, was strongly dependent on IL-17, IMP2, and C/EBPβ/δ. Imp2^−/− mice were resistant to autoantibody-induced glomerulonephritis (AGN), showing impaired renal expression of C/EBPs and Lcn2. Moreover, IMP2 deletion initiated only after AGN onset ameliorated disease. Thus, posttranscriptional regulation of C/EBPs through m⁶A/IMP2 represents a previously unidentified paradigm of cytokine-driven autoimmune inflammation.

过多的细胞因子活性是许多自身免疫性疾病的基础，特别是通过白细胞介素 17 (IL-17) 和肿瘤坏死因子 -α (TNFα) 信号轴。两种细胞因子都会激活核因子 κB，但下游效应基因的适当诱导需要其他转录因子的协调激活，特别是 CCAAT/增强子结合蛋白 (C/EBP)。在这里，我们证明了转录后“表转录组”mRNA 修饰 [N6-甲基腺苷 (m ⁶ A)] 意想不到地参与调节 C/EBPβ 和 C/EBPδ 以响应 IL-17A、IL-17F 和 TNFα。观察到 C/EBPβ/δ 编码转录本包含 m ⁶ A 共有位点，我们发现Cebpd和Cebpb mRNA 受到 m ⁶ A 修饰。 C/EBP 的诱导通过 m ⁶ A 甲基化酶“写入器”增强，并通过去甲基化酶“擦除器”抑制。发现参与该途径的唯一 m ⁶ A“阅读器”是 IGF2BP2 (IMP2)，并且 m ⁶ A 修饰增强了 IMP2 对Cebpd和Cebpb mRNA 的占据。 IMP2 促进 IL-17 介导的Cebpd mRNA 稳定，并促进 C/EBPβ/δ 翻译以响应 IL-17A、IL-17F 和 TNFα。 RNA测序揭示了受IMP2影响的全转录组IL-17诱导的转录物，RNA免疫沉淀测序鉴定了IMP2直接占据的mRNA子集，其中包括Cebpb和Cebpd 。 Lipocalin-2 ( Lcn2 ) 是自身免疫性肾损伤的标志，强烈依赖于 IL-17、IMP2 和 C/EBPβ/δ。 Imp2 ^-/−小鼠对自身抗体诱导的肾小球肾炎 (AGN) 具有抵抗力，显示 C/EBP 和Lcn2的肾脏表达受损。此外，IMP2 删除仅在 AGN 发作后才开始改善疾病。因此，通过 m ⁶ A/IMP2 对 C/EBP 的转录后调节代表了细胞因子驱动的自身免疫炎症的先前未识别的范例。