Histone lysine methylation functions at the interface of the extracellular environment and intracellular gene expression. DOT1L is a versatile histone H3K79 methyltransferase with a prominent role in MLL-fusion leukemia, yet little is known about how DOT1L responds to extracellular stimuli. Here, we report that DOT1L protein stability is regulated by the extracellular glucose level through the hexosamine biosynthetic pathway (HBP). Mechanistically, DOT1L is O-GlcNAcylated at evolutionarily conserved S1511 in its C terminus. We identify UBE3C as a DOT1L E3 ubiquitin ligase promoting DOT1L degradation whose interaction with DOT1L is susceptible to O-GlcNAcylation. Consequently, HBP enhances H3K79 methylation and expression of critical DOT1L target genes such as HOXA9/MEIS1, promoting cell proliferation in MLL-fusion leukemia. Inhibiting HBP or O-GlcNAc transferase (OGT) increases cellular sensitivity to DOT1L inhibitor. Overall, our work uncovers O-GlcNAcylation and UBE3C as critical determinants of DOT1L protein abundance, revealing a mechanism by which glucose metabolism affects malignancy progression through histone methylation.

组蛋白赖氨酸甲基化作用于细胞外环境和细胞内基因表达的界面。DOT1L 是一种多功能组蛋白 H3K79 甲基转移酶，在 MLL 融合白血病中具有重要作用，但对 DOT1L 如何响应细胞外刺激知之甚少。在这里，我们报告 DOT1L 蛋白稳定性受细胞外葡萄糖水平通过己糖胺生物合成途径 (HBP) 调节。从机制上讲，DOT1L 在其 C 末端的进化保守 S1511 处被 O-GlcNAcylated。我们将 UBE3C 鉴定为促进 DOT1L 降解的 DOT1L E3 泛素连接酶，其与 DOT1L 的相互作用易受 O-GlcNAcylation 的影响。因此，HBP 增强 H3K79 甲基化和关键 DOT1L 靶基因（如 HOXA9/MEIS1）的表达，促进 MLL 融合白血病中的细胞增殖。抑制 HBP 或 O-GlcNAc 转移酶 (OGT) 会增加细胞对 DOT1L 抑制剂的敏感性。总体而言，我们的工作揭示了 O-GlcNAcylation 和 UBE3C 作为 DOT1L 蛋白丰度的关键决定因素，揭示了葡萄糖代谢通过组蛋白甲基化影响恶性肿瘤进展的机制。