SR 144528, an Antagonist for the Peripheral Cannabinoid Receptor that Behaves as an Inverse Agonist
- Marielle Portier1,
- Murielle Rinaldi-Carmona1,
- Florence Pecceu2,
- Thérèse Combes1,
- Caroline Poinot-Chazel1,
- Bernard Calandra2,
- Francis Barth1,
- Gérard Le Fur3 and
- Pierre Casellas1
- 1Sanofi Recherche, Montpellier Cedex, France (M.P., M.R.-C., T.C., C.P.-C., F.B., P.C.); 2Sanofi Recherche, Labège Cedex, France (F.P., B.C.); and 3Sanofi Recherche, Paris, France (G. Le F.)
Abstract
In the present report, we investigated in detail the effects of SR 144528, a selective antagonist of the peripheral cannabinoid receptor (CB2), on two well-characterized functions mediated by CB2: the induction of the early response gene krox24 and the inhibition of adenylyl cyclase. We generated Chinese hamster ovary cells doubly transfected with human CB2 and a luciferase reporter gene linked to either the murine krox24 regulatory sequence or multiple cAMP responsive elements. Our results show that (1) SR 144528 antagonizes the effect of receptor agonists—it inhibits the krox24 reporter activity and prevents the inhibition of forskolin-induced cAMP reporter activity mediated by CP 55,940; (2) CB2 is autoactivated—CB2 mediates signaling in the absence of ligand, and this basal activity is reduced by pretreating the cells with pertussis toxin; (3) SR 144528 is an inverse agonist—it reproduces the effects of pertussis toxin; and (4) inhibition of precoupled CB2 by a long-term pretreatment of cells with SR 144528 potentiates krox24 response to cannabinoid receptor agonists and restores activation of adenylyl cyclase. Taken together, these data provide evidences for the inverse agonist property of SR 144528 and the constitutive activation of CB2 in Chinese hamster ovary-expressing cells.
Footnotes
-
Send reprint requests to: Marielle Portier, Immunopharmacology Department of Sanofi Recherche, 371 rue du Pr. J. Blayac, 34184 Montpellier cedex 04, France. E-mail:marielle.portier{at}tls1.elfsanofi.fr.
- Abbreviations:
- GPCR
- G protein-coupled receptor
- CB1
- central cannabinoid receptor
- CB2
- peripheral cannabinoid receptor
- CHO
- Chinese hamster ovary
- CKL
- CHO cells expressing krox24-luciferase
- CKL-CB2
- CKL cells expressing CB2, CRE, cAMP responsive element
- CCL
- CHO cells expressing CRE-luciferase, CCL-CB2, CCL cells expressing CB2
- RLU
- relative light unit
- RLU
- relative light unit
- PMA
- phorbol-12-myristate-13-acetate
- AC
- adenylyl cyclase
- MAPK
- mitogen-activated protein kinase
- PTX
- pertussis toxin
- Δ9-THC
- Δ9-tetrahydrocannabinol
- FSK
- forskolin
-
- Received March 18, 1998.
- Accepted August 10, 1998.
- The American Society for Pharmacology and Experimental Therapeutics
