Abstract
The G protein–coupled receptor 55 (GPR55) is a lysophosphatidylinositol (LPI) receptor that is also responsive to certain cannabinoids. Although GPR55 has been implicated in several (patho)physiologic functions, its role remains enigmatic owing mainly to the lack of selective GPR55 antagonists. Here we show that the compound CID16020046 ((4-[4-(3-hydroxyphenyl)-3-(4-methylphenyl)-6-oxo-1H,4H,5H,6H-pyrrolo[3,4-c]pyrazol-5-yl] benzoic acid) is a selective GPR55 antagonist. In yeast cells expressing human GPR55, CID16020046 antagonized agonist-induced receptor activation. In human embryonic kidney (HEK293) cells stably expressing human GPR55, the compound behaved as an antagonist on LPI-mediated Ca2+ release and extracellular signal-regulated kinases activation, but not in HEK293 cells expressing cannabinoid receptor 1 or 2 (CB1 or CB2). CID16020046 concentration dependently inhibited LPI-induced activation of nuclear factor of activated T-cells (NFAT), nuclear factor κ of activated B cells (NF-κB) and serum response element, translocation of NFAT and NF-κB, and GPR55 internalization. It reduced LPI-induced wound healing in primary human lung microvascular endothelial cells and reversed LPI-inhibited platelet aggregation, suggesting a novel role for GPR55 in platelet and endothelial cell function. CID16020046 is therefore a valuable tool to study GPR55-mediated mechanisms in primary cells and tissues.
Footnotes
- Received February 9, 2013.
- Accepted May 1, 2013.
↵1 Current affiliation: Hagedorn Research Institute, Novo Nordisk A/S, Gentofte, Denmark.
This work was supported by funds from the Austrian Science Fund [Grants P18723 (to M.W.), P22521 (to A.H.), P22771, and P25633 (to R.S.)]; the Jubilaeumsfonds of the Austrian National Bank [Grants 12552 (to M.W.), 13487, 14263 (to A.H.), and 14429 (to R.S.)]; the Lanyar Stiftung (to M.W.); the START-Funding Program of the Medical University of Graz, Ph.D. program Molecular Medicine of the Medical University of Graz, and an EMBO short-term fellowship (all to J.K.).
In-text citations for Bowes et al., 2012; Coma et al., 2009; and Zhang et al., 1999 can be found in Supplemental Methods.
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This article has supplemental material available at jpet.aspetjournals.org.
- Copyright © 2013 by The American Society for Pharmacology and Experimental Therapeutics
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