Figure 4

ChIP analysis at endogenous centromeres. (a) Western blot analysis of histone H3 dimethylated at lysine 4 (H3K4me2) and histone H3 methylated at lysine 9 (H3K9me) chromatin immunoprecipitation (ChIP). Lanes-Input chromatin, ChIP with rabbit IgG, and ChIP with antibody to (left) H3K4me2 or (right) H3K9me3. (b, c, d) DNA from the each ChIP experiment from the indicated antibody was labeled and used as a probe on metaphase spreads. H3K9me3, HP1α and HP1γ ChIP DNA hybridized to centromeric/pericentromeric regions. (e) An area of ~6 Mbp around the centromere gap of chromosome 10. (f) An area of ~2 Mbp at the centromere of chromosome 13. ChIP on CHIP (array) results for indicated antibodies and cell lines. All antibodies shown are enriched at the pericentromeric region. In chromosome 10, the pericentric heterochromatin is present over ~1 Mb at each side of the centromere gap. In chromosome 13, heterochromatin extends approximately 0.5 Mbp on the q arm. Note that genomic satellite DNA is not included on the Affymetrix CHIP. H3K9me3 (BBB) MAT score P < 2.5 × 10-⁵, HP1α (BBB) P < 5.6 × 10-³ and HP1γ (BBB) P < 9.6 × 10-³, H3K9me3 (IMS13q) P < 1.6 × 10-⁵. Repeat Masker tracks are shown below the graphs.