HUMAN VASOACTIVE INTESTINAL PEPTIDE(1) RECEPTORS EXPRESSED BY STABLE TRANSFECTANTS COUPLE TO 2 DISTINCT SIGNALING PATHWAYS

Vasoactive intestinal peptide (VIP) is a potent neuropeptide mediator of central and peripheral nervous system function. A human VIP1 receptor (HVR) cDNA clone was previously obtained from HT29 intestinal epithelial cells and lung tissue. Stably-transfected human embryonic kidney 293 cells and chinese hamster ovary (CHO) cells expressing about 10(6) HVRs per cell that bind [I-125]VIP with a Kd of 0.2 - 0.8 nM, and specifically recognized by anti-HVR antibodies, were established and characterized. VIP induced increases in intracellular cAMP levels ([cAMP]i) dose-dependently with EC50 of 0.2 nM in 293 anxc CHO stable transfectants and concurrently evoked dose-dependent increases in intracellular calcium concentrations ([Ca2+]i) as determined by fluorescence-dye spectroscopy. Untransfected 293 anc CHO cells showed minimal binding of intracellular effects of VIP; however, native VIP1 receptors of HT29 cells also increased [cAMP]i and [Ca2+]i-dependent responses to VIP. Thus recombinant and native human VIP1 receptors both couple to two distinct signal transduction pathways within a single cell type. (C) 1991 Academic Press, Inc.