The dynamic balance of DNA methylation and demethylation is required for erythropoiesis. Our previous transcriptomic analyses revealed that DNA methyltransferase 1 (DNMT1) is abundantly expressed in erythroid cells at all developmental stages. However, the role and molecular mechanisms of DNMT1 in human erythropoiesis remain unknown. Here we found that DNMT1 deficiency led to cell cycle arrest of erythroid progenitors which was partially rescued by treatment with a p21 inhibitor UC2288. Mechanically, this is due to decreased DNA methylation of p21 promoter, leading to upregulation of p21 expression. In contrast, DNMT1 deficiency led to increased apoptosis during terminal stage by inducing endoplasmic reticulum (ER) stress in a p21 independent manner. ER stress was attributed to the upregulation of RPL15 expression due to the decreased DNA methylation at RPL15 promoter. The upregulated RPL15 expression subsequently caused a significant upregulation of core ribosomal proteins (RPs) and thus ultimately activated all branches of unfolded protein response (UPR) leading to the excessive ER stress, suggesting a role of DNMT1 in maintaining protein homeostasis during terminal erythroid differentiation. Furthermore, the increased apoptosis was significantly rescued by the treatment of ER stress inhibitor TUDCA. Our findings demonstrate the stage-specific role of DNMT1 in regulating human erythropoiesis and provide new insights into regulation of human erythropoiesis.

DNA甲基化和去甲基化的动态平衡是红细胞生成所必需的。我们之前的转录组分析表明，DNA 甲基转移酶 1 (DNMT1) 在所有发育阶段的红细胞中大量表达。然而，DNMT1在人类红细胞生成中的作用和分子机制仍不清楚。在这里，我们发现 DNMT1 缺陷导致红系祖细胞的细胞周期停滞，但通过 p21 抑制剂 UC2288 治疗可以部分挽救这一现象。从机制上讲，这是由于p21启动子的 DNA 甲基化减少，导致 p21 表达上调。相比之下，DNMT1 缺陷通过以独立于 p21 的方式诱导内质网 (ER) 应激，导致末期细胞凋亡增加。 ER 应激归因于RPL15启动子 DNA 甲基化减少导致 RPL15 表达上调。 RPL15表达上调随后导致核心核糖体蛋白（RP）显着上调，从而最终激活未折叠蛋白反应（UPR）的所有分支，导致过度的内质网应激，这表明DNMT1在红系终末分化过程中维持蛋白质稳态中的作用。此外，ER应激抑制剂TUDCA的治疗显着挽救了增加的细胞凋亡。我们的研究结果证明了 DNMT1 在调节人类红细胞生成中的阶段特异性作用，并为人类红细胞生成的调节提供了新的见解。