Epigenetic regulation of human embryonic stem cells

Recently, there has been tremendous progress in characterizing the transcriptional network regulating human embryonic stem cells (hESCs; MacArthur etal., 2009; Loh etal., 2011), including those signaling events mediated by Oct4, Nanog, and Sox2. There is growing interest in the epigenetic machinery involved in hESC self-renewal and differentiation. In general, epigenetic regulation includes chromatin reorganization, DNA modification, and histone modification, which are not directly related to alterations in DNA sequences. Various protein complexes, including Polycomb, trithorax, nucleosome remodeling deacetylase, SWI/SNF, and Oct4, have been shown to play critical roles in epigenetic control of hESC physiology. Hence, we will formally review recent advances in unraveling the multifaceted role of epigenetic regulation in hESC self-renewal and induced differentiation, particularly with respect to chromatin remodeling and DNA methylation events. Elucidating the molecular mechanisms underlying the maintenance/differentiation of hESCs and reprogramming of somatic cells will greatly strengthen our capacity to generate various types of cells to treat human diseases.