With the help of epigenetic modifications of histones and DNA, cells establish its lineage specification. We focus only on the dynamic change of the methyl cytosine (5mC) in a long time. There are problems that treatment of DNA with bisulfite to evaluate the distribution of 5mC, cannot distinguish 5mC and 5-hmC. Here, with the new methods, we have mapped 5-hmC at different stages of T-cell development in the thymus and T-cell differentiation in the periphery.
In normal tissue, almost 90% of CpGs in the genome show high levels of cytosine methylation. As DNA methylation is associated with gene expression, we use bioinformatics to analysis the distribution of 5-hmC. We found that 5-hmC is enriched in the gene body of highly expressed genes at all developmental stages and that its occurrence correlates positively with gene expression.
As T-cell development is a good system to explore the relationship of epigenetics modification development regulation. We compare different stages of T-cells, and found that the 5-hmC levels change dynamically during the course of T-cell development and differentiation.
To summary, we have mapped the distribution of 5-hmC, a vital epigenetic modification, in developing and differentiating cells. 5-hmC is a marker for actively transcribed genes and for active enhancers.