Figure 3.

In vivo binding of CTCF at the +6.8 kb DHS region. Immunoprecipitations were performed with a CTCF-specific antibody and chromatin from (A) Caco2 cells and (B) Primary epididymis cells. No antibody control samples were also prepared, in which chromatin was incubated with Protein A agarose beads alone (data not shown). Samples were subjected to Taqman quantitative PCR analysis using probes specific for intron 17a and regions of interest 3′ to CFTR. CTCF-specific enrichment of each of these regions is shown relative to levels at intron 17a (which contains no predicted CTCF-binding sites). Vertical dashed line represents location of CFTR translation end-point, and x-axis on the right of this is drawn to scale (i.e. each data point accurately reflects the relative positions of Taqman amplicons). Immunoprecipitations were repeated at least twice. PCRs were performed in triplicate and Ct values averaged. Error bars denote S.E.M.