Analysis of upstream regulatory regions required for the activities of two promoters of the rat aldolase A gene

Abstract

Rat aldolase A gene has 2 promoters with different tissue specificities (M- and AH promoters). The M promoter is active only in adult skeletal muscle and induced during myogenesis, whereas the AH promoter is active ubiquitously in many tissues, including various cancer cells. Regulatory sequences for these promoters were investigated through assays for transient expression after introduction into myogenic and nonmyogenic cells. When M promoter—CAT fusion genes were transfected into primary cultures of chicken myoblasts, expression of CAT activity was drastically induced during myotube formation. The region comprising 202 to 85 base pairs (bp) upstream from the transcription initiation site was round to be necessary for the induction and an enhancer activity whose region includes the AT-rich recognition sequence MEF-2 binding site. On the other hand, 2 upstream regions were found to be responsible for AH promoter activity expressed in HepG2 cells. The distal region (−280 to –260) of the promoter includes the AP1 binding sequence, whereas the proximal region (−207 to −180) contains a novel inverted repeat consisting of 22 bp but does not contain known promoter and enhancer sequences