Genetics and epigenetics of the multifunctional protein CTCF.

Recent advances in studying long-range chromatin interactions have shifted focus from the transcriptional regulation by nearby regulatory elements to recognition of the role of higher-order chromatin organization within the nucleus. These advances have also suggested that CCCTC-binding factor (CTCF), a known chromatin insulator protein, may play a central role in mediating long-range chromatin interactions, directing DNA segments into transcription factories and/or facilitating interactions with other DNA regions. Several models that describe possible mechanisms for multiple functions of CTCF in establishment and maintenance of epigenetic programs are now emerging. Epigenetics plays an important role in normal development and disease including cancer. CTCF involvement in multiple aspects of epigenetic regulation, including regulation of genomic imprinting and X-chromosome inactivation, has been well established. More recently, CTCF was found to play a role in regulation of noncoding transcription and establishing local chromatin structure at the repetitive elements in mammalian genomes, suggesting a new epigenetic basis for several repeat-associated genetic disorders. Emerging evidence also points to the role of CTCF deregulation in the epigenetic imbalance in cancer. These studies provide some of the important missing links in our understanding of epigenetic control of both development and cancer.