enhancer 和 promoter 组蛋白染色质修饰

• enhancer：H3K4me1、H3K27ac、H3K4me2
• promoter: H3K4me3、H3K9ac、H3K4me2

启动子上的染色质修饰通常无细胞特异性；而增强子的染色质修饰有细胞特异性

• a, We performed k-means clustering on the chromatin modifications found ±5 kb from 414 promoters, and observe them to be generally invariant across cell types. b, As in a, but clustering on 1,423 non-redundant enhancers predicted on the basis of chromatin signatures, revealing the cell-type-specificity of enhancers.

增强子的染色质修饰与细胞类型特异性基因表达全局相关

图片来源：Heintzman N D, Hon G C, Hawkins R D, et al. Histone modifications at human enhancers reflect global cell-type-specific gene expression[J]. Nature, 2009, 459(7243): 108-112.