ChIP-seq for histone modifications and chromatin factors in H3.3 mutant (K9A; K27A; K79A) and control mESCs

Mouse embryonic stem cells (i.e., mESCs; line ESC 129-B13) were genetically modified using CRISPR-Cas9 to mutate the H3f3b locus, in order to carry homozygous lysine-to-alanine substitution of residues K9, K27 or K79. Two control mESC lines carrying knock-out of the H3f3a gene were used as background for the editing. Chromatin immunoprecipitation followed by sequencing (ChIP-seq) was performed to profile the changes in histone modifications, in the different H3.3 mutant mESC lines. The following histone modifications were profiled: H3K27ac (39685, Active Motif), H3K9ac (C5B11-9649, Cell Signalling Technology), H3K27me3 (C36B11, Cell Signalling Technology), H3K9me2 (D85B4, Cell Signalling Technology), H3K9me3 (D4W1U, Cell Signalling Technology). H3.3 (09-838, Merck-Millipore, purified polyclonal) ChIP-seq was performed in order to profile the deposition of this histone variant in the H3.3 K9A and K27A mESC mutant lines. SUZ12 (D39F6-3737, Cell Signalling Technology) ChIP-seq was performed to profile the genomic distribution of the Polycomb repressive complex 2 (i.e., PRC2). Two to three independent replicates per condition were grown and harvested for each ChIP experiment. Matched input controls were also generated in every experiment. Sequencing libraries were prepared using the NEBNext Ultra II library preparation kit (New England Biolabs) and sequenced on NextSeq500 or NextSeq2000 platforms in single-end mode.