Mapping and Functional Characterisation of a CTCF-Dependent Insulator Element at the 3′ Border of the Murine Scl Transcriptional Domain
Figure 4
The +45 element function as an insulator and this activity is dependent on the 57FPR.
The left panel represents the different constructs diagrammatically. Data is presented as K562 colony numbers relative to the control pNI construct containing only the ß-globin HS2 enhancer and the neomycin resistance promoter. The positive control (1.2 kb fragment containing the chicken HSIV insulator) reduces the number of colonies by 50%, with similar insulation observed from the 1.76 kb +45 element containing the 350 bp core element and the 57FPR. Deletion of either the 350 bp core from the +45 or deletion of the 57FPR from the 350 bp core, both removed the insulator function of the elements. Furthermore, mutation of the CTCF-binding site in the 350 bp core element significantly reduced the insulator function of the 350 bp core element. The data represents the mean ±SD of relative colony numbers from 3 independent experiments each performed in triplicate. * p<0.05, ** p<0.01 when compared to pNI.