Inhibition of DNA methylation in somatic cells.

DNA methylation plays a significant role in the expression of the genetic code and affects early growth and development through its influence on gene expression. DNA methyltransferase 1 (Dnmt1) is the enzyme responsible for maintaining the methylation marks through cell division. However, the de novo methyltransferases, Dnmt3a and Dnmt3b, can also contribute to the maintenance of the methylation pattern. Manipulation of these enzymes, especially Dnmt1, provides a means to alter DNA methylation levels. Manipulation of the DNA methylation pattern of somatic cells will allow a better understanding of the different molecular process associated with chromatin structure and gene expression. Different approaches to artificially manipulate the expression of Dnmt1 in somatic cells include the addition of 5-azacytidine, culture of cells for an extended period of time, and the use of small interfering RNA technologies.