Epigenomics of human embryonic stem cells and induced pluripotent stem cells: insights into pluripotency and implications for disease

Table 2 Chromatin signatures defining different classes of regulatory elements

Regulatory element	Chromatin signature	Cell type	References
Active promoters	Main: H3K4me3/2. Additional: H3ac, H4ac	General	[42, 56, 63, 64, 79]
Poised promoters (bivalent)	Main: H3K4me3/2, H3K27me3. Additional: H2AZ, MacroH2A	More prevalent in ESCs/iPSCs	[42, 56, 59]
Inactive promoters (CpG island-poor)	meC	General	[41, 68, 70]
Active enhancers	Presence: p300, H3K4me1/2, H3K27ac. Absence: H3K4me3, H3K27me3	General	[63, 64, 79]
Poised enhancers	Presence: p300, H3K4me1/2, H3K27me3. Absence: H3K4me3, H3K27ac	Prevalent in hESCs	[66, 67]
Insulators	CTCF	General	[105]
Long non-coding RNAs	promoter: H3K4me3. Gene body: H3K36me3	General	[104]

ESC, embryonic stem cell; CTCF, CCCTC-binding factor, insulator associated protein; hESC, human embryonic stem cell; iPSC, induced pluripotent stem cell; H2AZ, histone variant H2AZ; H3ac, acetylation of histone H3; H4ac, acetylation of histone H4; H3K4me1/2/3, (mono-, di- and tri) methylation of lysine 4 of histone H3; H3K27ac, acetylation of lysine 27 of histone H3; H3K27me3, trimethylation of lysine 27 of histone H3; H3K36me3, trimethylation of lysine 36 of histone H3; MacroH2A, histone variant MacroH2A; meC, methylcytosine.

ISSN: 1756-994X