Dual enhancer activities of the cyclic-AMP responsive element with cell type and promoter specificity.

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RESUMO

The role of the cyclic-AMP (cAMP) responsive element (CRE) in eukaryotic gene transcription was investigated in several cell lines transfected by constructs containing the chloramphenicol acetyltransferase (CAT) gene linked to the three different promoters, simian virus (SV) 40, human c-Ha-ras-1, or chicken beta-actin promoter, with or without CRE. CRE had inducible enhancer activity only when it was linked to the SV40 promoter and in a few cell lines such as PC12. CRE functioned as a constitutive enhancer with the human c-Ha-ras-1 promoter in all cell lines examined. CRE also had constitutive enhancer activity when it was linked to the chicken beta-actin promoter, but this activity was observed only in KB, HeLa, and A431 cells. The different types of enhancer activities of CRE depending on the cell and promoter may be caused by interaction with different trans-acting factors that were demonstrated by gel retardation analyses.

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