Characterization of the murine vasoactive intestinal peptide receptor VPAC2 promoter

Neuroimmune interactions are mediated primarily through a network of soluble molecules and specific receptors shared by neuronal/glial cells and immune cells. The neuropeptide vasoactive intestinal peptide (VIP) present in both primary and secondary immune organs affects a variety of immune functions, mostly mediated through the modulation of cytokines production. Previous reports from our laboratory indicated that VIP and the related neuropeptide, pituitary adenylate cyclase-activating polypeptide (PACAP), inhibit IL-2, IL-4 and IL-10 production by T cells receptor (TCR)-engaged CD4+ T cells and thymocytes. Three types of PACAP/VIP receptors (PVR) have been cloned recently. In the present study, we investigate the involvement of the three PVR in the inhibitory effect of VIP/PACAP on IL-2, IL-4 and IL-10 production, and the expression of these receptors at both mRNA and protein levels in purified CD4+ and CD8+ T lymphocytes. Our results show that the inhibitory effect of VIP/PACAP on IL-2, IL-4 and IL-10 production is mediated by both VPAC1 and VPAC2 but not by PAC1. Purified CD4+ and CD8+ splenic T cells express both VPAC1 and VPAC2 but no PAC1. The second part of the present study characterizes the promoter region of the murine VPAC2 gene. Our data show that the promoter region has a TATA box, two Oct1 binding sites, two CEBPB binding sites, two NFAT binding sites and one CREBP binding site. Results from the luciferase gene reporter system show that this region has functional promoter activity, and that the proximal Oct1 cis element is essential for transcription. Electromobility shift assay data further support this conclusion. The transcription start site was identified by primer extension experiments.