A cell type-dependent enhancer core element is located in exon 5 of the human angiotensinogen gene

We have recently characterized a cell type-dependent downstream enhancer that is contained within an 832-bp B2 sequences spanning the exon 5 and 3'-flanking region of the human angiotensinogen gene and have localized one of core elements to a 24-bp region in the 3'-flanking region. In the present study, we functionally dissected the 5'-half of B2 region and identified an additional cell type-dependent enhancer core element composed of the 80-bp sequences (+1399 to +1478) in the exon 5. Electrophoretic mobility shift assays demonstrated that the element interacts with two HepG2 cell-specific and several ubiquitous nuclear factors. These results, together with our previous results, suggest that the 80-bp exon 5 enhancer core element as well as 24-bp region plays an important role in the downstream enhancer effect.