Figure 1B ChIP assays were performed using human K562 cells, the Diagenode antibody against H3K27ac (Cat. No. C15410196)and optimized PCR primer pairs for qPCR. ChIP was performed with the “iDeal ChIP-seq” kit (cat. No. AB- 001-0024), using sheared chromatin from 100,000 cells. A titration consisting of 0.2, 0.5, 1 and 2 μg of antibody per ChIP experiment was analyzed. IgG (1 μg/IP) was used as a negative IP control. Quantitative PCR was performed with primers for the promoters of the active GAPDH and EIF4A2 genes, used as positive controls, and for the coding regions of the inactive MB and MYT1 genes, used as negative controls. Figure 1 shows the recovery, expressed as a % of input (the relative amount of immunoprecipitated DNA compared to input DNA after qPCR analysis)

Figure 2. ChIP-seq results obtained with the Diagenode antibody directed against H3K27ac
ChIP was performed on sheared chromatin from 100,000 K562 cells using 1 μg of the Diagenode antibody against H3K27ac (Cat. No. C15410196) as described above. The IP’d DNA was subsequently analysed on an Illumina Genome Analyzer. Library preparation, cluster generation and sequencing were performed according to the manufacturer’s instructions. The 36 bp tags were aligned to the human genome using the ELAND algorithm. Figure 2A shows the peak distribution along the complete human X-chromosome. Figure 2 B and C show the peak distribution in two regions surrounding the EIF4A2 and GAPDH positive control genes, respectively. The position of the PCR amplicon, used for validating the ChIP assay is indicated with an arrow.

Figure 3. Determination of the antibody titer
To determine the titer of the antibody, an ELISA was performed using a serial dilution of the Diagenode antibody against H3K27ac (Cat. No. C15410196). The antigen used was a peptide containing the histone modification of interest. By plotting the absorbance against the antibody dilution (Figure 3), the titer of the antibody was estimated to be 1:8,300.

Figure 4. Cross reactivity tests using the Diagenode antibody directed against H3K27ac
To test the cross reactivity of the Diagenode antibody against H3K27ac (Cat. No. C15410196), a Dot Blot analysis was performed with peptides containing other histone modifications and the unmodified H3K27. One hundred to 0.2 pmol of the respective peptides were spotted on a membrane. The antibody was used at a dilution of 1:20,000. Figure 4 shows a high specificity of the antibody for the modification of interest.

Figure 5. Western blot analysis using the Diagenode antibody directed against H3K27ac
Western blot was performed on whole cell (25 μg, lane 1) and histone extracts (15 μg, lane 2) from HeLa cells, and on 1 μg of recombinant histone H2A, H2B, H3 and H4 (lane 3, 4, 5 and 6, respectively) using the Diagenode antibody against H3K27ac (Cat. No. C1541196). The antibody was diluted 1:1,000 in TBS-Tween containing 5% skimmed milk. The marker (in kDa) is shown on the left.

Figure 6. Immunofluorescence using the Diagenode antibody directed against H3K27ac
HeLa cells were stained with the Diagenode antibody against H3K27ac (Cat. No. C15410196) and with DAPI. Cells were fixed with 4% formaldehyde for 10’ and blocked with PBS/ TX-100 containing 5% normal goat serum and 1% BSA. The cells were immunofluorescently labeled with the H3K27ac antibody (top) diluted 1:500 in blocking solution followed by an anti-rabbit antibody conjugated to Alexa488. The middle panel shows staining of the nuclei with DAPI. A merge of the two stainings is shown at the bottom.