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

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• 作者：Helle A. Hassing^a ; ^b ; Suzan Fares^a ; Olav Larsen^a ; Hamideh Pad^a ; ^b ; Maria Hauge^a ; ^c ; Robert M. Jones^d ; Thue W. Schwartz^a ; ^c ; Harald S. Hansen^b ; ^{hsh@sund.ku.dk" class="auth_mail" title="E-mail the corresponding author} ; Mette M. Rosenkilde^a ; ^{rosenkilde@sund.ku.dk" class="auth_mail" title="E-mail the corresponding author}
• 关键词：CREB ; cAMP response element-binding protein ; EEC ; enteroendocrine cell ; FAAH ; fatty acid amide hydrolase ; FBS ; Fetal Bovine Serum ; GIP ; glucose-dependent insulinotropic polypeptide ; GLP-1 ; glucagon-like-peptide 1 ; GPCR ; G protein-coupled receptor ; LPC ; lysophosphatidylcholine ; MAG ; monoacylglycerol ; MAGL ; monoacylglycerol lipase ; MEM ; minimal essential medium ; NAE ; N-acylethanolamine ; OEA ; oleoylethanolamide ; OLDA ; N-oleoyldopamine ; SRE ; serum response element ; 7TM ; seven transmembrane receptor
• 刊名：Biochemical Pharmacology
• 出版年：2016
• 出版时间：1 November 2016
• 年：2016
• 卷：119
• 期：Complete
• 页码：66-75
• 全文大小：1680 K

文摘

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 95 nM) across the different signaling pathways, whereas that of OEA varied >175-fold (from 85 nM to 15 μM) indicating a biased signaling for OEA. The degree of constitutive activity was 1–10%, 10–30% and 30–70% of OEA-induced E_max 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 2 h 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 100 nM 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.