Development of a novel method to analyze 5-hydroxymethylcytosine in the CpG sequence of the genome using maintenance DNA methyltransferase, DNMT1.

In mammals, cytosine in the CpG sequence is often methylated by DNA methyltransferase (Dnmt). Methylated cytosine (5mC) plays crucial roles in gene silencing, genomic imprinting, X-chromosome inactivation and the stability of genomic DNA. Aberrant DNA methylation causes embryonic lethality and cancer. Recently, 5-hydoxymethylcytosine (5hmC) was discovered to be a new modification of cytosine, being an intermediate of the demethylation process, and thus is implicated in the pluripotency of stem cells, development, and disease. Therefore, it is quite important to develop the technique to analyze the position of 5hmC in genome. To determine 5hmC at single-base resolution, several techniques have been reported. However, each method has advantages and disadvantages.

In the present study, we have developed a novel and simple method to determine 5hmC in the CpG sequence utilizing DNA methyltransferase 1 (DNMT1), which scarcely methylates hemi-hydroxymethylated DNA. We named this method DNMT1 methylation activity-assisted BS sequencing (DMAB-seq), which involves a different tool from those previously reported.

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Contact: Shoji Tajima