CpG islands are distinguishable from the bulk of vertebrate DNA for being unmethylated and CpG-rich. Since CpG doublets are the specific target of eukaryotic DNA methyltransferases, CpG-rich sequences might be expected to be good methyl-accepting substrates in vitro, despite their unmethylated in vivo condition. This was tested using a partially purified DNA-methyltransferase from human placent...

Development of methods that will allow exogenous imposition of inheritable gene-specific methylation patterns has potential application in both therapeutics and in basic research. An ongoing approach is the use of targeted DNA methyltransferases, which consist of a fusion between gene-targeted zincfinger proteins and prokaryotic DNA cytosine methyltransferases. These enzymes however have so far...

The 5mC DNA methyltransferase M.HhaI can be split into two individually inactive N- and C-terminal fragments that together can form an active enzyme in vivo capable of efficiently methylating DNA. This active fragment pair was identified by creating libraries of M.HhaI gene fragment pairs and then selecting for the pairs that code for an active 5mC methyltransferase. The site of bisection for s...

DNA methylation is now seen as a primary signal in the cell for mediating transcriptional repression through chromatin formation. The construction and evaluation of enzymes capable of influencing this process in vivo is therefore of significant interest. We have fused the C5-cytosine DNA methyltransferases, M.HhaI and M.HpaII, which both methylate 4 bp sequences containing a CpG dinucleotide, t...

The 06-methylguanine-DNA-methyltransferase (methyltransferase) activity was determined in a rat hepatoma cell line after treatment with ultraviolet or 7-irradiation, heat treatment, or incubation with c/'.vdiamminedichloroplatinum(ll), 2-methyI-9-hydroxyeIIipticinium, or bleomycin. The assay measured the removal of 0*-methylguanine from 'IIalkylated DNA by cellular extracts. The results show th...

DNA methylation regulates gene expression in normal and malignant cells. The possibility to reactivate epigenetically silenced genes has generated considerable interest in the development of DNA methyltransferase inhibitors. Here, we provide a detailed characterization of RG108, a novel small molecule that effectively blocked DNA methyltransferases in vitro and did not cause covalent enzyme tra...

The de novo DNA methyltransferase 3-like (Dnmt3L) is a catalytically inactive DNA methyltransferase that cooperates with Dnmt3a and Dnmt3b to methylate DNA. Dnmt3L is highly expressed in mouse embryonic stem cells (ESCs), but its function in these cells is unknown. Through genome-wide analysis of Dnmt3L knockdown in ESCs, we found that Dnmt3L is a positive regulator of methylation at the gene b...

Asymmetry of cell fate is one fundamental property of stem cells, in which one daughter cell self-renews, whereas the other differentiates. Evidence of nonrandom template segregation (NRTS) of chromosomes during asymmetric cell divisions in phylogenetically divergent organisms, such as plants, fungi, and mammals, has already been shown. However, before this current work, asymmetric inheritance ...

DNA methylation regulates gene expression in normal and malignant cells. The possibility to reactivate epigenetically silenced genes has generated considerable interest in the development of DNA methyltransferase inhibitors. Here, we provide a detailed characterization of RG108, a novel small molecule that effectively blocked DNA methyltransferases in vitro and did not cause covalent enzyme tra...

An efficient adaptive response to alkylation damage was observed in several enterobacterial species, including Klebsiella aerogenes, Shigella sonnei, Shigella boydii, Escherichia alkalescens, Escherichia hermanii, and Escherichia fergusonii. Increased O6-methylguanine-DNA and methylphosphotriester-DNA methyltransferase activities correlated with the induction of a 39-kDa protein recognized by m...