5/ We found that this competition is partly encoded in the Sox2 coding sequence (CDS) – a 1kb exon. Addition of the CDS to the reporter increases reporter expression and competition with the Sox2 gene. This effect seems to be mediated by the CDS-DNA sequence rather than the produced RNA or protein.

4/ Strikingly, deleting the endogenous Sox2 gene expands this landscape—yet the original Sox2 site remains a “sweet spot” for activation. Genes can thus act as gatekeepers, restricting their enhancer’s influence.

3/ These maps depict a sharply confined activation landscape. Interestingly, reporter expression is highest at the enhancer and around the endogenous gene whereas it turns silent upstream of the gene and downstream of the enhancer.

2/ By “loading” our transposon with a fluorescent Sox2 reporter, relocating it, and sorting cells by reporter expression, we generated high-resolution activity maps.

1/ Using a transposon-based approach, we systematically studied the positional relationship between the mouse Sox2 gene and its enhancer (SCR). In a single experiment, we can map >2000 unique genomic positions.