Regulation of mouse neuropeptide Y Y1 receptor gene transcription: a potential role for nuclear factor-kappa B/Rel proteins.

We previously isolated a 1.3-kb genomic fragment in the 5'-flanking region of the murine neuropeptide Y (NPY) Y1 receptor gene, which is able to drive the expression of LacZ reporter gene in neuronal cells. We determined the ability of deletion mutants of this region to modulate transcription of the heterologous luciferase gene in the Y1 receptor-expressing neuroblastoma/ glioma NG108-15 cells and the Y1 receptor-deficient 293 cells. Results suggest the presence of a cell type-specific core promoter (-399 to -218 from the initiator ATG) and, upstream, of two positive and two negative regulatory elements. Sequence analysis of the Y1 receptor promoter identified two decameric sequences corresponding to consensus binding sites for nuclear factor-kappa B/Rel proteins. Gel shift analysis indicated that a 29-bp oligonucleotide comprising the two putative kappa B sites, which we refer to as Y1-kappa B sequence, specifically binds kappa B-related complexes in nuclear extracts from rat brain areas, NG108-15 cells, and the murine T cell clone A.E7. In nuclear extracts from A.E7 and NG108-15 cells, the Y1-kappa B sequence specifically binds an additional complex whose molecular nature remains to be elucidated. Through transient transfection studies, we also demonstrated that the Y1-kappa B sequence acts as an enhancer element, inferring its potential role in regulation of the Y1 receptor gene expression.