GSE27322
de novo DNA Methylation Balances Hematopoietic Stem Cell Self-Renewal and Differentiation
Cytosine methylation is an epigenetic mark usually associated with gene repression. Despite a requirement for de novo DNA methylation for differentiation of embryonic stem cells, its role in somatic stem cells is unknown. Using conditional ablation, we show that loss of either, or both, Dnmt3a or Dnmt3b, progressively impedes hematopoietic stem cell (HSC) differentiation during serial in vivo passage. Concomitantly, HSC self-renewal is immensely augmented in absence of either Dnmt3, particularly Dnmt3a. Dnmt3-KO HSCs show upregulation of HSC multipotency genes and downregulation of early differentiation factors, and the differentiated progeny of Dnmt3-KO HSCs exhibit hypomethylation and incomplete repression of HSC-specific genes. HSCs lacking Dnmt3a manifest hyper-methylation of CpG islands and hypo-methylation of genes which are highly correlated with human hematologic malignancies. These data establish that aberrant DNA methylation has direct pathologic consequences for somatic stem cell development, leading to inefficient differentiation and maintenance of a self-renewal program. Overall design: Reduced representation bisulfite sequencing (MspI,~40-220bp size fraction) of secondarily-transplanted wild-type and Dnmt3a conditional knockout hematopoietic stem cells. We used microarrays to detail the global expression of genes in secondarily-transplanted control-HSCs and Dnmt3a-KO-HSCs.