Methylation Mesa define functional regulatory elements for targeted gene activation

DNA methylation regulates transcription, yet the demethylation of canonical elements like promoter CpG islands exhibits inconsistent correlations with gene activation. We hypothesize that causal regulatory elements are defined by biophysical hypersensitivity. Profiling 24 whole-genome bisulfite sequencing samples across diverse human and murine models, we identify Methylation Mesa, narrow (~45-300 bp), structurally conserved epigenetic regulatory elements. Mesa show enrichment in 5’ untranslated regions and associate with transcriptional activation significantly better than canonical promoters. To investigate causal regulatory dynamics, we develop CRISPR-DiR, an RNA-based targeted demethylation technology offering greater spatial precision, higher potency, and reduced toxicity compared to CRISPR-TET1. While proximal promoter demethylation initiated limited early transcription, focal demethylation of the Mesa seed acts as the primary driver of exponential CDKN2A (p16) reactivation and robust in vivo tumor suppression. We demonstrate that precise demethylation of a Mesa locus triggers localized demethylation, subsequent activation histone mark deposition, and long-range three-dimensional chromatin rewiring. Thus, Methylation Mesa act as precise, dominant epigenetic regulatory hubs, and CRISPR-DiR as a potent high-resolution tool, establishing a structural framework for biomarker discovery and targeted therapies. DNA methylation influences gene expression, but the regulatory importance of specific methylated regions is unclear. Here, the authors identify “Methylation Mesa” as focal epigenetic regulatory elements and show that precise Mesa demethylation drives gene activation, chromatin remodeling and tumor suppression.