TY - JOUR

T1 - Biased signaling of lipids and allosteric actions of synthetic molecules for GPR119

AU - Hassing, Helle A

AU - Fares, Suzan

AU - Larsen, Olav

AU - Pad, Hamideh

AU - Pedersen, Maria Hauge

AU - Jones, Robert M

AU - Schwartz, Thue W

AU - Hansen, Harald S

AU - Rosenkilde, Mette M

N1 - Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

PY - 2016/8/26

Y1 - 2016/8/26

N2 - GPR119 is a Gαs-coupled lipid-sensor in the gut, where it mediates release of incretin hormones from the enteroendocrine cells and in pancreatic α-cells, where it releases insulin. Naturally occurring lipids such as monoacylglycerols (MAGs) and N-acylethanolamines (NAEs), like oleoylethanolamide (OEA), activate GPR119, and multiple synthetic ligands have been described. Here, we extend the GPR119 signaling profile to Gαq and Gαi in addition to β-arrestin recruitment and the downstream transcription factors CRE (cAMP response element), SRE (serum response element) and NFAT (nuclear factor of activated T cells). The endogenous OEA and the synthetic AR231453 were full agonists in all pathways except for NFAT, where no ligand-modulation was observed. The potency of AR231453 varied <16-fold (EC50 from 6 to 95nM) across the different signaling pathways, whereas that of OEA varied >175-fold (from 85nM to 15μM) indicating a biased signaling for OEA. The degree of constitutive activity was 1-10%, 10-30% and 30-70% of OEA-induced Emax in Gαi, Gαq and Gαs-driven pathways, respectively. This coincided with the lowest and highest OEA potency observed in Gαi and Gαs-driven pathways, respectively. Incubation for 2h with the 2-MAG-lipase inhibitor JZL84 doubled the constitutive activity, indicating that endogenous lipids contribute to the apparent constitutive activity. Finally, besides being an agonist, AR231453 acted as a positive allosteric modulator of OEA and increased its potency by 54-fold at 100nM AR231453. Our studies uncovering broad and biased signaling, masked constitutive activity by endogenous MAGs, and ago-allosteric properties of synthetic ligands may explain why many GPR119 drug-discovery programs have failed so far.

AB - GPR119 is a Gαs-coupled lipid-sensor in the gut, where it mediates release of incretin hormones from the enteroendocrine cells and in pancreatic α-cells, where it releases insulin. Naturally occurring lipids such as monoacylglycerols (MAGs) and N-acylethanolamines (NAEs), like oleoylethanolamide (OEA), activate GPR119, and multiple synthetic ligands have been described. Here, we extend the GPR119 signaling profile to Gαq and Gαi in addition to β-arrestin recruitment and the downstream transcription factors CRE (cAMP response element), SRE (serum response element) and NFAT (nuclear factor of activated T cells). The endogenous OEA and the synthetic AR231453 were full agonists in all pathways except for NFAT, where no ligand-modulation was observed. The potency of AR231453 varied <16-fold (EC50 from 6 to 95nM) across the different signaling pathways, whereas that of OEA varied >175-fold (from 85nM to 15μM) indicating a biased signaling for OEA. The degree of constitutive activity was 1-10%, 10-30% and 30-70% of OEA-induced Emax in Gαi, Gαq and Gαs-driven pathways, respectively. This coincided with the lowest and highest OEA potency observed in Gαi and Gαs-driven pathways, respectively. Incubation for 2h with the 2-MAG-lipase inhibitor JZL84 doubled the constitutive activity, indicating that endogenous lipids contribute to the apparent constitutive activity. Finally, besides being an agonist, AR231453 acted as a positive allosteric modulator of OEA and increased its potency by 54-fold at 100nM AR231453. Our studies uncovering broad and biased signaling, masked constitutive activity by endogenous MAGs, and ago-allosteric properties of synthetic ligands may explain why many GPR119 drug-discovery programs have failed so far.

U2 - 10.1016/j.bcp.2016.08.018

DO - 10.1016/j.bcp.2016.08.018

M3 - Journal article

C2 - 27569424

VL - 119

SP - 66

EP - 75

JO - Biochemical Pharmacology

JF - Biochemical Pharmacology

SN - 0006-2952

IS - 1

ER -