FIGURE 9.

Formation of a CTCF-dependent intragenic chromatin loop. A, schematic view of a chromatin loop between the two introns flanking ANG coding exon. The arrows indicate the primers used in 3C experiment. B, chromatin loop formation shown by 3C assay. Transient chromatin interactions are stabilized by formaldehyde cross-linking followed by extraction and digestion with restriction enzyme StuI. DNA fragments were then ligated and amplified by PCR with the primer sets indicated in A. The loading control was derived from DNA sample before 3C with the primers amplifying the ANG coding region. C, ChIP-3C experiments. 3C and PCR amplifications were performed using control IgG and CTCF-specific IgG immunoprecipitated (IP) chromatin in both control and CTCF knockdown cells.