Epigenetics in embryonic stem cells: regulation of pluripotency and differentiation.

Embryonic stem cells (ESC) are pluripotent cells capable of multilineage differentiation into every somatic cell type and therefore must be able to initiate transcription profiles for each of these different cells while maintaining their pluripotent state. Numerous studies have attempted to uncover the basic biology of the ESC and delineate mechanisms of pluripotency, but with limited success. However, recent studies attempting to understand the mechanisms by which gene expression is regulated in ESC have uncovered potential mechanisms that may be vitally important to their pluripotent nature. Epigenetic regulatory mechanisms include covalent modification of histone modification and DNA methylation. Studies have now shown that epigenetic mechanisms are vitally important to the pluripotent nature of ESC and that these mechanisms regulate differentiation. The epigenetic nature of the ESC has been demonstrated to be unique and its characteristics have been strongly linked to the global permissivity of gene expression and pluripotency. Unique mechanisms have also been suggested for the dynamic regulation of differentiation-associated gene expression. Additionally, epigenetic mechanisms have been indicated to play a role in the formation of the pluripotent cells of the inner cell mass in the developing blastocyst.