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MOLECULAR PHARMACOLOGY 52:292-299 (1997).

Cholecystokinin_B Receptor from Human Jurkat Lymphoblastic T Cells Is Involved in Activator Protein-1-Responsive Gene Activation

Catherine Oiry, Didier Gagne, Éric Cottin, Nicole Bernad, Jean-Claude Galleyrand, Gilbert Bergé, Marie-Francoise Lignon, Patrick Eldin, Martine Le Cunff, Jean Léger, Pascal Clerc, Daniel Fourmy, and Jean Martinez

Laboratoire des Amino Acides, Peptides et Protéines (L.A.P.P.) ESA.CNRS 5075, Universités de Montpellier I et II Faculté de Pharmacie, 34060 Montpellier, France (C.O., D.G., E.C., N.B., J.-C.G., G.B., M.-F.L., J.M.), Institut National de la Santé et de la Recherche Médicale U300, Faculté de Pharmacie, 34060 Montpellier, France (P.E., M. le C., J.L.), and Institut National de la Santé et de la Recherche Médicale U151, Centre Hospitalier Universitaire Rangueil, 31054 Toulouse, France (P.C., D.F.)

The aim of this study was to analyze the role of cholecystokinin (CCK_B) receptor in human lymphoblastic Jurkat T cells. We investigated the trophic effect resulting from activation of such a receptor by using the reporter gene strategy. For this purpose, we transiently transfected Jurkat T cells with the reporter plasmid p[(TRE)3-tk-Luc] and found that CCK-8 was able to dose-dependently induce luciferase expression related to activator protein-1 (AP-1) activation with a maximal response identical to that obtained with compounds known to activate AP-1 complex (quantitatively, the same level of induction was obtained with 1 nM 12-O-tetradecanoylphorbol-13-acetate, 100 µM diacylglycerol, or 4 nM epidermal growth factor). The involvement of the CCK_B receptor in such a stimulation was demonstrated by the inhibiting effect of the selective CCK_B receptor antagonist PD-135,158. This effect was confirmed in COS-7 cells transfected with the cDNA of CCK_B receptor cloned from Jurkat T cells. To better understand the AP-1-dependent luciferase expression in Jurkat T cells, we tested two specific inhibitors of serine/threonine phosphatases-1 and -2A: okadaic acid and calyculin A. These compounds strongly increased the phorbol-12-myristate-13-acetate response, whereas we have not observed a contribution of phosphatase inhibitors on a CCK-8-induced luciferase activity. To confirm that CCK_B receptors are involved in AP-1 response, we investigated the CCK-8 effect on interleukin-2 expression, a natural endogenous gene regulated by several factors, including AP-1. In Jurkat T cells activated by phorbol-12-myristate-13-acetate and phytohemagglutinin, CCK-8 induced IL-2 expression. This induction was abolished by PD-135,158. Our results indicate that CCK-8 exerts a trophic effect in Jurkat T cells through stimulation of CCK_B receptors by modulation of expression of AP-1-regulated genes.