Disease relevance of Dnmt3a

• We also show that hypermethylation of genomic DNA by Dnmt3a and Dnmt3b is necessary for ES cells to form teratomas in nude mice [1].
• De novo DNA methyltransferases, Dnmt3a and 3b, were purified by fractionation of S-100 extract from mouse lymphosarcoma cells through several chromatographic matrices followed by glycerol density gradient centrifugation [2].
• To study this mechanism we have cloned and expressed Dnmt3a using a baculovirus expression system [3].
• Dnmt3a from mouse was cloned and expressed in Escherichia coli [4].
• In this study, we have analyzed the sequence specificity of Dnmt3a and Dnmt3b during de novo methylation of murine Moloney leukemia virus provirus DNA in virus-infected ES cells [5].

High impact information on Dnmt3a

• In this system, Dnmt3a functioned as a de novo methyltransferase, whereas Dnmt1 had no detectable de novo methylation activity [6].
• When co-expressed, Dnmt1 and Dnmt3a cooperated to establish and maintain methylation patterns [6].
• Inactivation of both Dnmt3a and Dnmt3b, DNA methyltransferases essential for the initiation of de novo DNA methylation, abolished the establishment of DNA methylation and the silencing of Rhox cluster genes in the embryo proper [7].
• These findings suggest that rapid methylation of the evolutionarily conserved -53 CpG by Dnmt3a may suppress IFN-gamma transcription in developing TH2 cells by directly inhibiting transcription factor binding [8].
• The PWWP domain is a weakly conserved sequence motif found in > 60 eukaryotic proteins, including the mammalian DNA methyltransferases Dnmt3a and Dnmt3b [9].

Biological context of Dnmt3a

• DNA methylation density influences the stability of an epigenetic imprint and Dnmt3a/b-independent de novo methylation [10].
• In the present study, we demonstrate that Dnmt3a and Dnmt3b are also essential for the stable inheritance, or "maintenance," of DNA methylation patterns [1].
• The DNA methyltransferases (MTases) Dnmt3a and Dnmt3b are thought to be the sole de novo MTases in the mammalian genome [10].
• Therefore, Dnmt1 and Dnmt3a/3b share targets in CpG islands [11].
• Molecular enzymology of the catalytic domains of the Dnmt3a and Dnmt3b DNA methyltransferases [12].

Anatomical context of Dnmt3a

• Establishment and maintenance of genomic methylation patterns in mouse embryonic stem cells by Dnmt3a and Dnmt3b [1].
• We have previously shown that the DNA methyltransferases Dnmt3a and Dnmt3b carry out de novo methylation of the mouse genome during early postimplantation development and of maternally imprinted genes in the oocyte [1].
• Use of an alternative promoter at the Dnmt3a locus produces the shorter Dnmt3a2 transcript in the germ line and postimplantation embryo only, whereas alternative splicing of the Dnmt3b transcript ensures that Dnmt3b1 is absent in the male prospermatogonia [13].
• In this study, we have investigated how targeted disruption of the DNA methyltransferases Dnmt3a and Dnmt3b affects the growth of mouse embryonic fibroblasts (MEFs) [14].
• Dnmt3a2 and Dnmt3b transcripts were at their highest levels in type A spermatogonia, decreased dramatically in type B spermatogonia and preleptotene spermatocytes and rose again in leptotene/zygotene spermatocytes, while Dnmt3a expression was mostly constant, except in type B spermatogonia where it increased [15].

Associations of Dnmt3a with chemical compounds

• These results suggest that the cytotoxic effect of 5-aza-dC may be mediated primarily through Dnmt3a and Dnmt3b de novo DNA methyltransferases [16].
• DNA methyltransferases Dnmt1, Dnmt3a and Dnmt3b cooperatively regulate cytosine methylation in CpG dinucleotides in mammalian genomes, providing an epigenetic basis for gene silencing and maintenance of genome integrity [17].
• Kinetic analysis supports an Ordered Bi Bi mechanism for Dnmt3a, where DNA binds first, followed by S-adenosyl-l-methionine [3].
• Catalytic mechanism of DNA-(cytosine-C5)-methyltransferases revisited: covalent intermediate formation is not essential for methyl group transfer by the murine Dnmt3a enzyme [18].
• Whereas wild-type Dnmt3a and the ENV variants form covalent complexes with 5-fluorocytidine modified DNA, the PCN variant does not [18].

Co-localisations of Dnmt3a

• Unlike DNMT1, which localizes to replication foci during S-phase in murine embryonic fibroblasts, Dnmt3a co-localizes with heterochromatin protein 1 alpha (HP1 alpha) and methyl-CpG binding proteins throughout the cell cycle to late-replicating pericentromeric heterochromatin [19].

Regulatory relationships of Dnmt3a

• Dnmt3b is specifically expressed in the totipotent cells of mouse early embryos and Dnmt3a, a longer form of the two isoforms, is ubiquitously expressed in mesenchyme cells after the 10 day embryo stage [Mech. Dev. 118 (2002) 187] [20].

Other interactions of Dnmt3a

• These studies revealed the presence of a Dnmt3a/Dnmt3b-independent de novo methyltransferase activity that is stimulated by the presence of preexisting methylation [10].
• We have analyzed the expression of Dnmtl, Dnmt3a, and Dnmt3b methyltransferases in wild type and drug resistant murine neuroblastoma cells by using Western blot, immunofluorescence microscopy, semiquantitative and quantitative real time RT-PCR analyses [21].
• The expression of Dnmt3a was also increased in the liver but not in the thymus of p53-deficient mice [22].
• In contrast, glial fibrillary acidic protein-positive astrocytes exhibit relatively weak or no Dnmt3a immunoreactivity in vitro and in vivo [23].
• 5. However, from the newborn stage to adulthood, Dnmt3a X-gal signal was detected predominantly in postmitotic CNS neurons across all the regions examined, including olfactory bulb, cortex, hippocampus, striatum, and cerebellum [23].

Analytical, diagnostic and therapeutic context of Dnmt3a

• Increased expression of Dnmt3b was observed at days 5 and 14, followed by increased expression of Dnmt1 and Dnmt3a at day 30, as evaluated by real-time RT-PCR [24].
• Immunocytochemistry experiments confirmed that Dnmt3a protein is strongly expressed in neural precursor cells, postmitotic CNS neurons, and oligodendrocytes [23].
• Assignment of cytosine-5 DNA methyltransferases Dnmt3a and Dnmt3b to mouse chromosome bands 12A2-A3 and 2H1 by in situ hybridization [25].

References