期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2020
卷号：117
期号：14
页码：7755-7763
DOI：10.1073/pnas.1915582117
出版社：The National Academy of Sciences of the United States of America
摘要：Methionine metabolism is critical for the maintenance of embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) pluripotency. However, little is known about the regulation of the methionine cycle to sustain ESC pluripotency. Here, we show that adenosylhomocysteinase (AHCY), an important enzyme in the methionine cycle, is critical for the maintenance and differentiation of mouse embryonic stem cells (mESCs). We show that mESCs exhibit high levels of methionine metabolism, whereas decreasing methionine metabolism via depletion of AHCY promotes mESCs to differentiate into the three germ layers. AHCY is posttranslationally modified with an O-linked β- N -acetylglucosamine sugar (O-GlcNAcylation), which is rapidly removed upon differentiation. O-GlcNAcylation of threonine 136 on AHCY increases its activity and is important for the maintenance of trimethylation of histone H3 lysine 4 (H3K4me3) to sustain mESC pluripotency. Blocking glycosylation of AHCY decreases the ratio of S-adenosylmethionine versus S-adenosylhomocysteine (SAM/SAH), reduces the level of H3K4me3, and poises mESC for differentiation. In addition, blocking glycosylation of AHCY reduces somatic cell reprogramming. Thus, our findings reveal a critical role of AHCY and a mechanistic understanding of O-glycosylation in regulating ESC pluripotency and differentiation.
