Cis-existence of H3K27me3 and H3K36me2 in mouse embryonic stem cells revealed by specific ions of isobaric modification chromatogram

摘要: Histone H3 lysine 27 trimethylation (H3K27me3) and 36 (H3K36me3) are important epigenetic modifications correlated with transcription repression activation, respectively. These two opposing rarely co-exist in the same polypeptide. However, a small but significant amount of tails modified 5 methyl groups on K27 K36 mouse embryonic stem cells (mESCs) it is unclear how distributed or K36. A label-free, bottom-up mass spectrum method, named specific ions isobaric modification chromatogram (SIMC), was established to quantify relative abundance K27me2-K36me3 K27me3-K36me2 histone tail. By using this we demonstrated that H3K27me3-K36me2 comprises about 85 % penta-methylated at mESCs. Upon mESC differentiation, significantly decreased, while level H3K27me2-K36me3 remains unchanged. Our study not only revealed cis-existence mESCs, also suggested combinatorial may assume regulatory function during differentiation.