N‐Palmitoylglycine and other N‐acylamides activate the lipid receptor G2A/GPR132

Abstract

The G‐protein‐coupled receptor GPR132, also known as G2A, is activated by 9‐hydroxyoctadecadienoic acid (9‐HODE) and other oxidized fatty acids. Other suggested GPR132 agonists including lysophosphatidylcholine (LPC) have not been readily reproduced. Here, we identify N‐acylamides in particular N‐acylglycines, as lipid activators of GPR132 with comparable activity to 9‐HODE. The order‐of‐potency is N‐palmitoylglycine > 9‐HODE ≈ N‐linoleoylglycine > linoleamide > N‐oleoylglycine ≈ N‐stereoylglycine > N‐arachidonoylglycine > N‐docosehexanoylglycine. Physiological concentrations of N‐acylglycines in tissue are sufficient to activate GPR132. N‐linoleoylglycine and 9‐HODE also activate rat and mouse GPR132, despite limited sequence conservation to human. We describe pharmacological tools for GPR132, identified through drug screening. SKF‐95667 is a novel GPR132 agonist. SB‐583831 and SB‐583355 are peptidomimetic molecules containing core amino acids (glycine and phenylalanine, respectively), and structurally related to previously described ligands. A telmisartan analog, GSK1820795A, antagonizes the actions of N‐acylamides at GPR132. The synthetic cannabinoid CP‐55 940 also activates GPR132. Molecular docking to a homology model suggested a site for lipid binding, predicting the acyl side‐chain to extend into the membrane bilayer between TM4 and TM5 of GPR132. Small‐molecule ligands are envisaged to occupy a “classical” site encapsulated in the 7TM bundle. Structure‐directed mutagenesis indicates a critical role for arginine at position 203 in transmembrane domain 5 to mediate GPR132 activation by N‐acylamides. Our data suggest distinct modes of binding for small‐molecule and lipid agonists to the GPR132 receptor. Antagonists, such as those described here, will be vital to understand the physiological role of this long‐studied target.

The Lipid Receptor G2A (GPR132) Mediates Macrophage Migration in Nerve Injury-Induced Neuropathic Pain

“…The BMDMs were stimulated with the G2A agonist 9-HODE (1 µM) for 24 h prior to the proteomic analysis. This concentration is in range of the EC50 of 9-HODE for both the human and the murine G2A, as previously shown [16,21]. The stimulation of BMDMs with 9-HODE induced a minor, but significant increase of G2A mRNA expression (Figure 4A).…”

“…G2A belongs to the group of proton-sensing GPCRs and is expressed in TRPV1-positive primary sensory neurons, but mainly in immune cells [ 18 , 19 ]. In the group of proton-sensing GPCRs, G2A shows the weakest response to acidic pH and seems to be a receptor for signaling lipids rather than for acidic conditions [ 20 , 21 ]. It has also been suggested before that G2A is responsible for the migration of leukocytes, but the underlying signaling pathways are still unclear [ 22 , 23 , 24 ].…”

Proton-Sensing GPCRs in Health and Disease

“…A recent study also identified N-palmitoylglycine and N-linoleoylglycine as G2A-activators with similar potency to 9-HODE, which strengthens the concept of G2A being a receptor for signaling lipids rather than protons and acidification. In the same study, the angiotensin-II type I receptor antagonist telmisartan as well as a telmisartan analogue, GSK1820795A, were identified as potent G2A inhibitors [113].…”

The Intestinal Fatty Acid-Enteroendocrine Interplay, Emerging Roles for Olfactory Signaling and Serotonin Conjugates

“…In addition to FFAR2, and to GPR35, which senses kynurenic acid [ 107 ], Hcar2; (hydroxycarboxylic acid receptor 2; Niacr1; GPR109A), detecting butyrate and nicotinic acid [ 104 ], GPBAR1 (TGR5) the sensor for secondary bile acids and GPR132, which detects N -acylglycines and oxidized fatty acids [ 114 ] showed high expression levels in ECs from colon [ 95 ]. Additionally, Martin et al found that in colonic ECs, FFAR4 showed similar high expression as FFAR2 and a moderate expression of GPR119 and GPR92 (LPA5), while FFAR3 was low expressed [ 103 ].…”