Identification of a suppressor element in the amelogenin promoter

Amelogenin expression is regulated in a cell-type-specific manner. investigators have previously identified an enhancer element by using the 5ĝ2 flanking sequence of the amelogenin promoter. however,the cell-type-specific regulation of the amelogenin gene remains poorly understood. in some genes,the first intron regulates tissue-specific expression. we hypothesized that intron 1 is important for the cell-type-specific regulation of amelogenin expression. we identified a suppressor element between -74 and -464. we also found enhancer activity in intron 1. additionally,we found that the suppressor element in the promoter region suppressed intron 1 enhancer activity. the suppressor and the enhancers acted in an ameloblast-like cell line,but not in hela cells. mutation of the oct-1 binding sites reversed the suppressor activity,suggesting that oct-1 sites are essential for suppression. these results suggest that oct-1 and intron 1 may contribute to cell-type-specific amelogenin expression.