It would be interesting to study the dynamics of these interactions during cell cycle. Moreover, expression is observed in a few embryos in the limb bud and in the brain, albeit less frequently. The expression of LacZ in the neural tube, as well as in parts of the brain, suggest that the target of CNC8 could be OLIG2 and/or OLIG1 whose murine patterns of expression are similar to the LacZ activity observed. Overall these results suggest that CNC8 is a potent enhancer of transcription although its specificity was different among embryos. The number of integrations as well as the genomic site of integration could explain the differences in the LacZ expression pattern among embryos. Alternatively, CNC8 could be a general regulator of gene activity, whose temporal and spatial specificity requires other DNA elements and a particular genomic context. If indeed CNC8 requires other DNA elements to function properly, other CNCs in the region might provide this additional layer of regulation. Moreover, as described above, CNCs in the region have the tendency to interact with each other. Thus, we tested whether other CNCs analyzed in this study showed interactions with or in the vicinity of OLIG2. Indeed, CNC6 and CNC7 display interactions within 5 kb of OLIG2. Two additional CNCs have CIRs within 10 kb of that gene despite of the fact that these are almost 0.2 Mb apart. CNC7, which is located about 16.5 kb upstream of OLIG2, show an interaction with a DpnII fragment 0.2 kb downstream of its transcription start site. Most interestingly, the mouse orthologue of CNC7 enables ALK5 Inhibitor II 446859-33-2 activation of a LacZ reporter in the neural tube as well as in the posterior diencephalon at E11.5. There are two lines of evidence suggesting that CNC7 and CNC8 are potential transcriptional regulators of OLIG2. First, we observe interaction between these CNCs and OLIG2. Second, these CNCs act as enhancers in regions of the mouse embryo that co-localize with the natural expression of OLIG2. Recent experiments combining enhancer identification by ChIP-seq against p300 and mouse transgenesis have shown that a region encompassing CNC8 drives the expression of a reporter gene in the mouse embryo forebrain at E11.5. However, we were surprised to observe these interactions in K562 cells where OLIG2 is silent or expressed at very low levels, indicating that these regions are not functional enhancers in this cellular context. Chromatin looping of these regions over the promoter of OLIG2 could either be repressive or non-productive, akin to a poised state of the enhancer-promoter configuration. Subsequent cell-specific recruitment of transcription factors or epigenetic modifiers would be permissive for gene expression. It is also possible that these interactions are residual or transient in non-expressing cells, therefore interfering with proper gene activation. Interestingly, we have identified at least 5 CNCs spanning a 200 kb genomic region that interact with loci within 10 kb of OLIG2.