Two separate cis-active elements of the vasoactive intestinal peptide gene mediate constitutive and inducible transcription by binding different sets of AP-1 proteins.

Vasoactive intestinal peptide (VIP) gene expression is highly restricted throughout the neuroaxis and regulated by extracellular factors that activate tyrosine- or serine/threonine-directed protein kinase pathways. Cytokine, cyclic AMP, and tissue-specific response elements on the VIP gene have been characterized. Those mediating responsiveness to protein kinase C have not. The endogenous VIP gene and a 5.2-kilobase pair (kb) VIP-luciferase reporter gene, are up-regulated by phorbol 12-myristate 13-acetate (PMA) in SK-N-SH neuroblastoma cells. PMA stimulation was abolished by deletion of sequences at -1.37 to -1.28 or -1.28 to -0.904 kb, but not by removal of the single phorbol ester response element (TRE; TGACTCA) located at -2.25 kb. Mutation of sites at -1.32 or -1.20 that mediate neurotrophin responsiveness of the VIP gene (Symes, A., Lewis, S., Corpus, L., Rajan, P., Hyman, S. E., and Fink, J. S. (1994) Mol. Endocrinol. 8, 1750-1763) each reduced PMA induction in SK-N-SH cells by >50%, and double mutation abolished it. The two mutations also reduced basal VIP reporter gene transcription in SH-EP neuroblastoma cells expressing VIP constitutively. Both cis-active elements bound pre-existing AP-1 proteins in SH-EP- or PMA-stimulated SK-N-SH cell nuclear extracts. The AP-1 complex at both sites contained a Fos-related protein with c-Jun in SH-EP cells and c-Fos with a Jun-related protein in SK-N-SH cells. Recruitment of combinatorially distinct AP-1 complexes to these elements may underlie cell type-specific regulation of the VIP gene.