A potential model representing the mechanisms underlying hypomethylation-dependent TLR2 promoter activation in human epithelial cells. Enhanced methylation of the CpG#18-20 site within TLR2 promoter observed in non-CF epithelial cells is followed by the enhanced recruitment of unknown factors "X" that could recognize methylated CpGs and could suppress SP1-dependent transcriptional activation without affecting the binding of SP1 to those CpGs (left panel). 5-azacytidine (5-AC) treatment of non-CF cells leads to the demethylation of CpG#18-20. On the other hand, CF epithelial cells express high level of TLR2 gene through decreased methylation of CpG#18-20, which might abolish the recruitment and activity of factors "X" in these cells (right panel).
Furuta et al. BMC Molecular Biology 2008 9:39 doi:10.1186/1471-2199-9-39