DNA methylation can be reversed either passively, as when maintenance DNA methyltransferase activity is inhibited in proliferating cells, or by an active, replication-independent process in which DNA methylation is enzymatically removed.
Can we control DNA methylation?
Transcription factors can regulate DNA methylation by binding to specific DNA sequence to either recruit Dnmts for methylation or protect from DNA methylation. In some cases, Dnmts bind to transcription factors or components of repressor complexes to target methylation to DNA
Is DNA methylation a good thing?
In mammals, DNA methylation is essential for normal development and is associated with a number of key processes including genomic imprinting, X-chromosome inactivation, repression of transposable elements, aging, and carcinogenesis.