N⁶-methyladenosine (m⁶A) is the most abundant RNA modification, but little is known about its role in mammalian hematopoietic development. Here, we show that conditional deletion of the m⁶A writer METTL3 in murine fetal liver resulted in hematopoietic failure and perinatal lethality. Loss of METTL3 and m⁶A activated an aberrant innate immune response, mediated by the formation of endogenous double-stranded RNAs (dsRNAs). The aberrantly formed dsRNAs were long, highly m⁶A modified in their native state, characterized by low folding energies, and predominantly protein coding. We identified coinciding activation of pattern recognition receptor pathways normally tasked with the detection of foreign dsRNAs. Disruption of the aberrant immune response via abrogation of downstream Mavs or Rnasel signaling partially rescued the observed hematopoietic defects in METTL3-deficient cells in vitro and in vivo. Our results suggest that m⁶A modification protects against endogenous dsRNA formation and a deleterious innate immune response during mammalian hematopoietic development.

N ⁶ -甲基腺苷 (m ⁶ A) 是最丰富的 RNA 修饰，但对其在哺乳动物造血发育中的作用知之甚少。在这里，我们展示了小鼠胎肝中m ⁶ A 作家 METTL3 的条件性缺失导致造血功能衰竭和围产期致死率。METTL3 和 m ⁶ A 的缺失激活了一种异常的先天免疫反应，由内源性双链 RNA (dsRNA) 的形成介导。异常形成的 dsRNA 很长，高度 m ⁶A 在其天然状态下经过修饰，以低折叠能为特征，主要编码蛋白质。我们确定了通常负责检测外来 dsRNA 的模式识别受体通路的同时激活。通过消除下游Mavs或Rnasel信号传导破坏异常免疫反应，在体外和体内部分挽救了 METTL3 缺陷细胞中观察到的造血缺陷。我们的结果表明，m ⁶ A 修饰可防止哺乳动物造血发育过程中的内源性 dsRNA 形成和有害的先天免疫反应。