Figure 4

Association between HP1α and CTCF binding sites. (A) Graph of significant genome-wide associations between AGO1, CTCF, HP1α, RNAPII and 5metC binding sites. The black double arrows indicate the significant associations between HP1α and CTCF, HP1α and 5metC and CTCF and RNAPII, whereas the directional gray arrows indicate the significant one-sided associations (Additional file 1: Table S8). The number beside each arrow indicates the proportion of clusters (rounded to the closest integer) that overlap with the sites of the factors connected by the arrow. (B) Mean densities of HP1α clusters centered at CTCF clusters (blue line), compared with randomized HP1α clusters (dashed blue line); and mean densities of CTCF clusters (green line) centered at the HP1α clusters, compared with randomized CTCF clusters (dashed green line). Randomized clusters were calculated by relocating each cluster in an arbitrary new position in the same chromosome, avoiding satellites, gaps, pericentromeric regions and the overlap with any other random cluster. AGO1, argonaute 1 protein; CTCF, CCCTC-binding factor; HP1, heterochromatin protein 1; RNAPII, RNA polymerase II; 5metC, 5-methycytosine.