Targeted DNA Demethylation to Identify Regulatory CpG Methlation Marks
Genome-wide studies have defined cell type–specific patterns of DNA methylation that are associated with differential gene expression profiles, but the ability to determine the regulatory role of any given methylation mark has been elusive. Recently, we described a strategy for efficient targeted demethylation of specific cytosine-guanine diresidues (CpGs) in human cells using fusions of programmable transcription activator–like effector (TALE) arrays and the catalytic domain of the dioxygenase TET1.
Using these TALE-TET1 fusions, we demonstrated that removal of critical methylation marks in promoters can lead to substantial increases in the expression of endogenous human genes. Notably, we found that demethylation of one particular promoter CpG – but not others nearby – was sufficient to activate transcription of the HBB gene, lending support to the idea that only a small number of promoter CpGs are bona fide regulatory marks.
I will discuss these initial experiments, as well as a number of potential improvements to our published approach that we are currently pursuing.
If you would like to meet with Dr James Angstman, please contact the host Dr Peter Rugg-Gunn directly.