What's the role of DNA methylation in regulating gene expression, why DNA methylation is important?

It alters the expression of genes in cells as cells divide and differentiate from embryonic stem cells into specific tissues. changes are usually permanent and unidirectional, preventing differentiated cell from reverting to a stem cell or converting into another type of tissue. DNA methylation suppresses the expression of endogenous retroviral genes and other harmful stretches of DNA that have been incorporated into the genome of the host over time.