DNA regulatory elements that control cholesterol 7 alpha -hydroxylase expression are disclosed, including bile acid responsive elements. A gene construct comprising at least one CYP7 regulatory element and a reporter gene is used to transfect HepG2 cells. Confluent transfected HepG2 cells are employed in an assay to detect a compound that modulates cholesterol 7 alpha -hydroxylase enzyme regulation. A method for screening compounds that inhibit or stimulate expression of the enzyme is provided, as well as a method for detecting and isolating transcription factors of the cholesterol 7 alpha -hydroxylase gene. A transcription factor of 57 KDa is identified which is useful in an assay for determining regulation of CYP7 expression. <IMAGE>
Cholesterol 7alpha-hydroxylase gene regulatory elements and transcription factors.