Role of DNA methylation in the regulation of cell function.

The methylation of DNA helps stabilize chromatin in an inactive configuration and inhibits gene transcription. This mechanism of gene regulation is involved in essential genetic events including differentiation, genomic imprinting, and X chromosome inactivation. The alteration of methylation patterns can result in abnormal gene expression, with significant pathologic effects including carcinogenesis, autoimmunity, and some of the changes in gene expression associated with aging. The mechanisms establishing, maintaining, and modifying methylation patterns in normal and pathologic states are only now becoming understood, as are the mechanisms relating DNA methylation to gene expression and chromosome inactivation. Further characterization of these mechanisms holds promise for delaying or preventing the changes in methylation patterns that contribute to cancer, autoimmunity, and aging. (J Lab Clin Med 1999;134:333-40)