While CpG Islands and CpG Shores have always been hot destinations on the CpG landmark tour, a new feature has emerged that may just give them a run for their money. Using genome-wide mapping of 5mC and 5hmC in mouse stem cells to explore the luxurious shores and islands of the CpGenome, an adventurous team from the Baylor College of Medicine came across an exciting new landmark. Here’s what they discovered:

Mystical regions of low methylation, that they dubbed CpG Canyons, which span conserved domains frequented by touring transcription factors.

There’s no confusing a canyon for a island or shore – each have very distinct features.

Interestingly, there appears to be two unique classes of CpG Canyons. About half of the genes in canyons are “coated with repressive histone marks, whereas the remainder are covered by activating histone marks and are highly expressed.”

Finally, they observed that canyon borders are landmarked by 5hmC and with the removal of DNA methyltransferase 3a (Dnmt3a) they go onto become eroded by the sands of the time.

After getting off their luxury liner tour, the team also went on to characterize associations and found that genes dysregulated in leukemia tend to reside in CpG Canyons. Ultimately, this report serves as a great travel diary documenting the exploration of a new feature in the epigenetic landscape, while also leaving us with a mechanism for the regulation of stem cell differentiation that appears to contribute to the etiology of complex disease.

Take the full tour of the CpGenome in Nature Genetics, March 2014