Article

Dnmt3a is essential for hematopoietic stem cell differentiation. Nat Genet

Stem Cells and Regenerative Medicine Center, Baylor College of Medicine, Houston, Texas, USA.
Nature Genetics (Impact Factor: 29.35). 12/2011; 44(1):23-31. DOI: 10.1038/ng.1009
Source: PubMed

ABSTRACT

Loss of the de novo DNA methyltransferases Dnmt3a and Dnmt3b in embryonic stem cells obstructs differentiation; however, the role of these enzymes in somatic stem cells is largely unknown. Using conditional ablation, we show that Dnmt3a loss progressively impairs hematopoietic stem cell (HSC) differentiation over serial transplantation, while simultaneously expanding HSC numbers in the bone marrow. Dnmt3a-null HSCs show both increased and decreased methylation at distinct loci, including substantial CpG island hypermethylation. Dnmt3a-null HSCs upregulate HSC multipotency genes and downregulate differentiation factors, and their progeny exhibit global hypomethylation and incomplete repression of HSC-specific genes. These data establish Dnmt3a as a critical participant in the epigenetic silencing of HSC regulatory genes, thereby enabling efficient differentiation.

Download full-text

Full-text

Available from: Mira Jeong, Dec 20, 2013
  • Source
    • "Consequently, it was postulated that methylation serves as a lock that reinforces a previously silenced state of X-linked genes (Lock et al. 1987). However, results from a study that investigated the role of DNMT3A in haematopoietic stem cell differentiation have raised questions about the universality of the long-term locking model (Challen et al. 2012). The aforementioned study indicated that methylase was vital for differentiation of a short-lived cell type. "

    Full-text · Dataset · Jan 2016
  • Source
    • "We hypothesized that the observed differences in chromatin condensation among ESCs, HSPCs, and mature cells could be due to global differences in either DNA methylation or histone modifications. However, despite recent demonstrations of the importance of DNA methylation for HSC function (Bröske et al., 2009; Challen et al., 2011; Trowbridge et al., 2009), we did not detect significant differences in DNA digestion between HSPCs and mature cells using the restriction enzymes MspI and HpaII (Figure S1B) (Bernardino et al., 1997). Using immunoblotting, we also found no significant differences in the overall levels of any of the histone marks investigated (H3K4me3, H3Ac, H4K16Ac, H4K20me1, and H3K36me3 that are usually associated with active transcription, or H3K27me3, H3K9me2, and H3K9me3 that usually act as repressive marks) among ESCs, HSPCs, and fully mature cells (Figure 1C). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Epigenetic regulation serves as the basis for stem cell differentiation into distinct cell types, but it is unclear how global epigenetic changes are regulated during this process. Here, we tested the hypothesis that global chromatin organization affects the lineage potential of stem cells and that manipulation of chromatin dynamics influences stem cell function. Using nuclease sensitivity assays, we found a progressive decrease in chromatin digestion among pluripotent embryonic stem cells (ESCs), multipotent hematopoietic stem cells (HSCs), and mature hematopoietic cells. Quantitative high-resolution microscopy revealed that ESCs contain significantly more euchromatin than HSCs, with a further reduction in mature cells. Increased cellular maturation also led to heterochromatin localization to the nuclear periphery. Functionally, prevention of heterochromatin formation by inhibition of the histone methyltransferase G9A resulted in delayed HSC differentiation. Our results demonstrate global chromatin rearrangements during stem cell differentiation and that heterochromatin formation by H3K9 methylation regulates HSC differentiation.
    Full-text · Article · Oct 2015 · Stem Cell Reports
  • Source
    • "DNA methylation of CpG dinucleotides is catalyzed by at least three different DNA methyltransferases (DNMTs), including Dnmt1 for methylation maintenance and Dnmt3a and Dnmt3b for de novo methylation (Denis et al., 2011). The DNMTs are essential for maintaining the methylation pattern in stem cells and for regulating their self-renewal and differentiation (Challen et al., 2012; Tsai et al., 2012a). We observed downregulation of Dnmt1, Dnmt3a, and Dnmt3b in MRL/lpr BMMSCs when compared to control BMMSCs, as indicated by western blot (Figure 3A). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Mesenchymal stem cell transplantation (MSCT) has been used to treat human diseases, but the detailed mechanisms underlying its success are not fully un- derstood. Here we show that MSCT rescues bone marrow MSC (BMMSC) function and ameliorates osteopenia in Fas-deficient-MRL/lpr mice. Mecha- nistically, we show that Fas deficiency causes failure of miR-29b release, thereby elevating intracel- lular miR-29b levels, and downregulates DNA meth- yltransferase 1 (Dnmt1) expression in MRL/lpr BMMSCs. This results in hypomethylation of the Notch1 promoter and activation of Notch signaling, in turn leading to impaired osteogenic differentiation. Furthermore, we show that exosomes, secreted due to MSCT, transfer Fas to recipient MRL/lpr BMMSCs to reduce intracellular levels of miR-29b, which re- sults in recovery of Dnmt1-mediated Notch1 pro- moter hypomethylation and thereby improves MRL/ lpr BMMSC function. Collectively our findings un- ravel the means by which MSCT rescues MRL/lpr BMMSC function through reuse of donor exosome- provided Fas to regulate the miR-29b/Dnmt1/Notch epigenetic cascade.
    Full-text · Article · Aug 2015 · Cell Metabolism
Show more