AN AP-2 BINDING SEQUENCE WITHIN EXON-1 OF HUMAN AND PORCINE CHOLINE-ACETYLTRANSFERASE GENES ENHANCES TRANSCRIPTION IN NEURAL CELLS

The gene for choline acetyltransferase, synthesizing acetylcholine, is induced by several neurotrophic factors. A role for AP-2 in enhancing this transcription and limiting it to neural cells is strongly sugges ted. Previous studies demonstrated that base pairs +465-727 within the untranslated exon 1 of the porcine gene enhanced the expression of a reporter gene transfected into PC-12 cells. Deletion and mutation expe riments indicate that base pairs +465-472 (CCGCGGGG) in the porcine ge ne, or +307-314 (CCTCGGGG) in the human sequence, were necessary and s ufficient for increased gene expression in cholinergic or adrenergic b ut not liver cells. Constructs containing active sequences, but not in active mutated sequences, specifically bind nuclear proteins from neur oblastoma cells, but not liver cells, in gel shift experiments. The hu man and porcine sequences are in agreement with an AP-2 consensus bind ing sequence, a nuclear transcription factor expressed only in cells d erived from the neural crest. Gel shift experiments using recombinant AP-2 confirm this identification. AP-2 antibody Further retarded the m obility of these DNA-nuclear extract or DNA-AP-2 complexes. These resu lts support the importance of this AP-2 binding sequence in enhancing and limiting choline acetyltransferase expression in neural cells. Cop yright (C) 1996 IBRO.