About this Research Topic
DNA methylation (5-methylcytosine, 5mC) of CpG dinucleotides has been known for a long time as the major epigenetic modification contributing to the regulation of gene expression in eukaryotic genomes. Several years ago, a number of ground-breaking studies have demonstrated that 5mC can be enzymatically oxidised by TET proteins producing 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC). Growing body of experimental evidence suggests that these oxidised forms of 5mC may not only serve as intermediates in the process of DNA demethylation but also play specific roles in transcriptional regulation in different biological systems. Moreover, recent exciting reports demonstrating that adenine can be methylated and exist as N6-methadenine (6mA) in animal DNA, provided additional level of complexity to the DNA methylation field. This Research Topic is intended to offer an opportunity to discuss the current state and identify the challenges and future directions related to studying the biological importance of these novel enigmatic DNA modifications by research articles, mini-reviews and reviews.
Potential subtopics include, but are not limited to (a) the methylation of non-CpG cytosines in animal DNA, (b) the roles of three oxidative derivitatives of 5mC (5hmC, 5fC and 5caC) in various biological contexts and (c) potential functional significance and distribution of 6mA in eukaryotic genomes.
Keywords: modified bases in eukaryotic DNA, DNA demethylation, 5-hydroxymethylcytosine, 5-formylcytosine, 5-carboxylcytosine, N6-methadenine
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