Ich, the Baugarten Foundation, the Sobek Foundation, Fondation Acteria, the Wellcome Trust, the Leukaemia and Lymphoma Research, the Medical Analysis Council and the Swiss National Science Foundation (310030_143979 and CRSII3_136241).
DNA methylation of CpG dinucleotides can be a important mode of epigenetic regulation within the vertebrate genome, with functions like silencing of repetitive elements, X chromosome inactivation, genomic imprinting and regulation of gene expression (Jaenisch and Jahner, 1984; Ng and Bird, 1999; Surani, 1998). From the three catalytic DNA methyltransferase enzymes, Dnmt1 has a greater affinity for hemimethylated DNA than unmethylated DNA (Bestor, 1992) and ablation of Dnmt1 in embryonic stem (ES) cells results in comprehensive but non-specific loss of DNA methylation, top for the view that Dnmt1 is often a “maintenance” methyltransferase (Lei et al., 1996; Li et al., 1992). Conversely, Dnmt3a and Dnmt3b act as de novo DNA methyltransferases accountable for establishment of DNA methylation patterns, predominantly through early improvement (Hata et al., 2002; Okano et al., 1999). On the other hand, Dnmt3a and Dnmt3b also seem critical for the stable inheritance of some DNA methylation, as loss of each enzymes in ES cells results in progressive loss of DNA methylation in repetitive and some single-copy components (Chen et al., 2003). Whilst Dnmt3a and Dnmt3b are very homologous, their biological functions stay unclear. Dnmt3b-null mice die at mid-gestation with a number of developmental defects, and Dnmt3a-null mice die shortly just after birth (Okano et al., 1999), but their cell type-specific roles have not been completely elucidated. Compound Dnmt3a/Dnmt3b double knockout (DKO) embryos arrest shortly after gastrulation (Okano et al., 1999), and DKO ES cells display inefficient differentiation which can be increasingly pronounced with extended passage (Chen et al., 2003). In neural stem cells, Dnmt3a is required for neurogenesis as Dnmt3a-dependent nonproximal promoter methylation regulates expression of neurogenic genes (Wu et al., 2010). Our group has lately reported that Dnmt3a is essential for hematopoietic stem cell (HSC) differentiation as Dnmt3a-null HSCs show a marked decline in differentiation capacity on a per-HSC basis over serial transplantation, resulting in accumulation of undifferentiated HSCs within the bone marrow (Challen et al., 2012). Furthermore, mutations in DNMT3A are prevalent in myeloid malignancies (Ley et al., 2010; Walter et al., 2011; Yan et al., 2011) and lymphoid leukemias (Grossmann et al., 2013), constant with an important function in hematopoiesis. On the other hand, no distinct role for Dnmt3b has been identified in HSCs or any other adult stem cell. Right here, we conditionally ablate Dnmt3b alone, or in combination with Dnmt3a, and investigate the functional consequences for HSCs.tert-Butyl azetidin-3-ylcarbamate web Cell Stem Cell.Buy3-Oxo-3-(thiophen-3-yl)propanenitrile Author manuscript; obtainable in PMC 2015 September 04.PMID:24576999 Challen et al.PageRESULTSDnmt3s co-operatively enable long-term HSC differentiation in vivo Equivalent to Dnmt3a, Dnmt3b is most highly expressed in long-term HSCs relative to differentiated cells (Figure S1A). To investigate the functional role of Dnmt3b, we generated conditional KO mice by crossing Dnmt3bfl/fl and Dnmt3afl/fl mice (Dodge et al., 2005) with Mx1-cre mice to generate inducible Dnmt3b-KO mice (3bKO) and Dnmt3a/Dnmt3b double KO (DKO) mice; we also compare data from these mice in some cases with that from Dnmt3a-KO mice (3aKO; information generated right here or from (Challen et al., 2012)).
