The field of epigenetics now occupy a leading position in the studies relating to diverse processes such as transcriptional regulation, chromatin structure, genome integrity, and tumorigenesis. Recent works have demonstrated how DNA methylation and chromatin structure are linked at the molecular level and how alterations in methylation play a role in tumorigenesis and genetic diseases. The cellular methylation machinery, known as the DNA methyltransferases, plays a major role in mammalian development in terms of the types of proteins they are known to interact with. Recent informations explain how cellular DNA methylation patterns may be established during development and maintained in somatic cells. Emerging evidence indicates that various chromatin states such as histone modifications (acetylation and methylation) and nucleosome positioning (modulated by ATP-dependent chromatin remodeling machines) determine DNA methylation patterning. Additionally, various regulatory factors interacting with the DNA methyltransferases and direct them to specific DNA sequences, regulate their enzymatic activity, and allow their use as transcriptional repressors. Connections between DNA methylation and chromatin structure and the DNA methyltransferase associated proteins, reveal that many, if not all, epigenetic modifications of the genome are directly connected. Such studies should also yield new insights into treating diseases involving aberrant DNA methylation like cancer
