Centre for Haemato-Oncology, Barts Cancer Institute, John Vane Science Centre, Charterhouse Square, Queen Mary University of London, London EC1M 6BQ, United Kingdom.
Haematopoietic Stem Cell Laboratory, Francis Crick Institute, London NW1 1AT, United Kingdom.
Proc Natl Acad Sci U S A. 2023 Aug 22;120(34):e2300224120. doi: 10.1073/pnas.2300224120. Epub 2023 Aug 14.
Aging is associated with an abnormal increase in DNA methylation (DNAm) in human gene promoters, including in bone marrow stem cells. DNAm patterns are further perturbed in hematological malignancies such as acute myeloid leukemia but the physiological significance of such epigenetic changes is unknown. Using epigenetic editing of human stem/progenitor cells (HSPCs), we show that p15 methylation affects hematopoiesis in vivo. We edited the (p15) promoter and (p14) using dCas9-3A3L and observed DNAm spreading beyond the gRNA location. We find that despite a transient delivery system, DNAm is maintained during myeloid differentiation in vitro, and hypermethylation of the p15 promoter reduces gene expression. In vivo, edited human HSPCs can engraft the bone marrow of mice and targeted DNAm is maintained in HSPCs long term. Moreover, epigenetic changes are conserved and inherited in both myeloid and lymphoid lineages. Although the proportion of myeloid (CD33) and lymphoid (CD19) cells is unaffected, monocyte (CD14) populations decreased and granulocytes (CD66b) increased in mice engrafted with p15 hypermethylated HSPCs. Monocytes derived from p15 hypermethylated HSPCs appear to be activated and show increased inflammatory transcriptional programs. We believe these findings have clinical relevance since we found p15 promoter methylation in the peripheral blood of patients with clonal hematopoiesis. Our study shows DNAm can be targeted and maintained in human HSPCs and demonstrated functional relevance of aberrant DNAm on the p15 locus. As such, other aging-associated aberrant DNAm may impact hematopoiesis in vivo.
衰老与人类基因启动子中 DNA 甲基化（DNAm）的异常增加有关，包括骨髓干细胞。在急性髓系白血病等血液系统恶性肿瘤中，DNAm 模式进一步受到干扰，但这种表观遗传变化的生理意义尚不清楚。通过对人类干细胞/祖细胞（HSPCs）进行表观遗传编辑，我们表明 p15 甲基化会影响体内造血。我们使用 dCas9-3A3L 编辑了 （p15）启动子和 （p14），并观察到 DNAm 在 gRNA 位置之外扩散。我们发现，尽管使用了瞬时传递系统，但在体外髓系分化过程中仍能维持 DNAm，并且 p15 启动子的过度甲基化会降低基因表达。在体内，编辑后的人类 HSPCs 可以植入小鼠的骨髓中，并且靶向 DNAm 在 HSPCs 中长期维持。此外，表观遗传变化在髓系和淋巴系中都得到了保守和遗传。尽管髓系（CD33）和淋巴系（CD19）细胞的比例没有受到影响，但植入 p15 高甲基化 HSPCs 的小鼠中单核细胞（CD14）群体减少，粒细胞（CD66b）增加。源自 p15 高甲基化 HSPCs 的单核细胞似乎被激活，并表现出增加的炎症转录程序。我们认为这些发现具有临床相关性，因为我们在克隆性造血患者的外周血中发现了 p15 启动子甲基化。我们的研究表明可以靶向和维持人类 HSPCs 中的 DNAm，并证明了 p15 基因座上异常 DNAm 的功能相关性。因此，其他与衰老相关的异常 DNAm 可能会影响体内造血。
