BME 130 – Genomes Lecture 19 The histone code
Figure 7.1 Genomes 3 (© Garland Science 2007)
Figure Genomes 3 (© Garland Science 2007) H3 H4 H2A H2B
CHiP-Seq DNA DNA-binding proteins (histones, e.g) crosslink Immuno-precipitate and fragment DNA Immuno-precipitate and fragment DNA Reverse cross-links and sequence
ChIP-Seq and ChIP-chip comparison of two histone marks Lower background & tighter peaks in ChIP-Seq (better contrast) trxG (activation) PcG (repression)
Promoter classes high CpG gene low CpG intermediate CpG CpG Highly expressed, housekeeping genes; other genes N=11,410 Genes with high tissue-specificity N=3,014 Mixture of genes N=3,338
NPC=neural progenitor cellsMEF=embryonic fibroblastsES = embryonic stem cells
Highly dynamic histone modification during differentiation
H3K36me3 marks gene bodies (may prevent aberrant transcriptional initiation)
Imprinting is reflected in H3K36me3 state
Nucleosome positioning and gene structure
Histone modification in cell division Haspin H3 P P Survivin Chromosomal passenger complex AuroraB (kinase)