A classic cAMP responsive element in the promoter region of the α₁- GABA(A) receptor subunit has non-classic properties

The cAMP responsive element binding protein (CREB) and the glucocorticoid receptor (GR) have been reported to bind to a 60 bp promoter fragment of the α₁-GABA(A) receptor gene containing a classic cAMP- responsive element (CRE). We inserted this fragment into a hormone responsive element-deleted mouse mammary tumor virus promoter controlling the expression of luciferase. Activation of GR showed no significant change in luciferase expression, but hormone induction by forskolin revealed a reduction in neuronal cell lines. Furthermore, we demonstrate that cellular factors from neuronal cells can bind to the CRE-containing promoter fragment, although competition by unlabeled CRE and GRE oligo-nucleotides is not present. Mutation of the CRE site and deletion of neighboring DNA sequences indicate that the promoter is probably associated with a complex of different regulatory factors.