The medium-chain free fatty acid receptor GPR84 is expressed in pro-inflammatory macrophages and mediates inflammatory sequelae in endometriosis
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE104176 | GEO | 2019/03/15
REPOSITORIES: GEO
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Project description:The medium-chain free fatty acid receptor GPR84 is expressed in pro-inflammatory macrophages and mediates inflammatory sequelae in endometriosis
| PRJNA411952 | ENA
Project description:Beta-catenin signaling is required for establishment of leukemic stem cells (LSCs) in acute myeloid leukemia (AML), yet the upstream regulators that can augment this pathway are unknown. Through genome-wide gene expression analysis and functional studies, we identified an important role for GPR84 in MLL AML. Suppression of GPR84 significantly inhibited cell growth in pre-LSCs, reduced LSC frequency and impaired reconstitution of MLL AML. Furthermore, GPR84 conferred a growth advantage to Hoxa9/Meis1a transduced hematopoietic stem cells (HSCs). Our microarray analysis demonstrated that GPR84 overexpression significantly up-regulated a small set of MLL-fusion targets and beta-catenin co-effectors, and down-regulated a hematopoietic cell cycle inhibitor. These data thus reveal a previously unrecognized role of GPR84 in the maintenance of fully developed AML by sustaining aberrant beta-catenin signaling in LSCs. HSC-derived Hoxa9/Meis1a pre-LSCs were transduced with GPR84 cDNA or empty vector, and replated in methylcellulose supplemented with cytokines. Each group contains triplicate samples.
2014-10-15 | E-MTAB-1932 | biostudies-arrayexpress
Project description:Medium-chain triglycerides (MCTs), which consist of medium-chain fatty acids (MCFAs), are unique forms of dietary fat with various health benefits. G protein-coupled 84 (GPR84) acts as a receptor for MCFAs (especially C10:0 and C12:0); however, GPR84 is still considered an orphan receptor, and the nutritional signaling of endogenous and dietary MCFAs via GPR84 remains unclear. Here, we showed that endogenous MCFA-mediated GPR84 signaling protected hepatic functions from diet-induced lipotoxicity. Under high-fat diet (HFD) conditions, GPR84-deficient mice exhibited nonalcoholic steatohepatitis (NASH) and the progression of hepatic fibrosis but not steatosis. With markedly increased hepatic MCFA levels under HFD, GPR84 suppressed lipotoxicity-induced macrophage overactivation. Thus, GPR84 is an immunomodulating receptor that suppresses excessive dietary fat intake-induced toxicity by sensing increases in MCFAs. Additionally, administering MCTs, MCFAs (C10:0 or C12:0, but not C8:0), or GPR84 agonists effectively improved NASH in mouse models. Therefore, exogenous GPR84 stimulation is a potential strategy for treating NASH.
| S-EPMC9977302 | biostudies-literature
Project description:Although the GPR84 activators 2-HTP and 6-OAU promoted phosphorylation of human GPR84 and its interactions with arrestin-3, PSB-16671 and DL-175 did not. Replacement of all 21 serine and threonine residues within the third intracellular loop, but not the 2 serines in the C-terminal tail, eliminated incorporation of [32P] promoted by 2-HTP and greatly reduced receptor-arrestin-3 interactions. Mass spectrometry indicated that GPR84 was phosphorylated constitutively on residues Ser221 and Ser224 whilst a range of sites became phosphorylated in response to 2-HTP. An antiserum able to identify pSer221/pSer224 recognised GPR84 from cells treated both with and without 2-THP, whilst an antiserum able to identify pThr263/pThr264 recognised GPR84 only after exposure to 2-HTP. Treatment with neither PSB-16671 nor DL-175 was able to promote receptor recognition by this antiserum. 2-HTP-mediated phosphorylation of Thr263/Thr264 was prevented by two chemically distinct GPR84 antagonists but neither affected constitutive phosphorylation of Ser221/Ser224. 2-HTP-mediated phosphorylation of Thr263/Thr264 but not constitutive phosphorylation of Ser221/Ser224 was prevented by GRK2/3 inhibition. Mutation of residues Thr263 and Thr264 to alanine generated a variant of GPR84 as limited in 2-HTP-induced interactions with arrestin-3 as when all 21 serine and threonine were eliminated from the third intracellular loop. By contrast this mutant was unaffected in capacity to reduce cAMP levels in response to 2-HTP. Homology modelling and mutagenesis provided molecular insight into differences in agonist function. These studies define key residues, regulated by GRK2/3, that define effective interactions with arrestins and provide novel tools to monitor the phosphorylation and functional status of GPR84.
2022-06-09 | PXD031252 | Pride
Project description:Medium-chain fatty acids (MCFAs) have been associated with anti-steatotic effects in hepatocytes. Expression of the MCFA receptor GPR84 (G protein-coupled receptor 84) is induced in immune cells under inflammatory conditions and can promote fibrogenesis. We aimed at deciphering the role of GPR84 in the pathogenesis of non-alcoholic steatohepatitis (NASH), exploring its potential as a therapeutic target. GPR84 expression is upregulated in liver from patients with non-alcoholic fatty liver disease (NAFLD), correlating with the histological degree of inflammation and fibrosis. In mouse and human, activated monocytes and neutrophils upregulate GPR84 expression. Chemotaxis of these myeloid cells by GPR84 stimulation is inhibited by two novel, small molecule GPR84 antagonists. Upon acute liver injury in mice, treatment with GPR84 antagonists significantly reduced the hepatic recruitment of neutrophils, monocytes, and monocyte-derived macrophages (MoMF). We, therefore, evaluated the therapeutic inhibition of GPR84 by these two novel antagonists in comparison to selonsertib, an apoptosis signal-regulating kinase 1 (ASK1) inhibitor, in three NASH mouse models. Pharmacological inhibition of GPR84 significantly reduced macrophage accumulation and ameliorated inflammation and fibrosis, to an extent similar to selonsertib. In conclusion, our findings support that GPR84 mediates myeloid cell infiltration in liver injury and is a promising therapeutic target in steatohepatitis and fibrosis.
| S-EPMC7231190 | biostudies-literature
Project description:Fatty acid receptors have been recognized as important players in glycaemic control. This study is the first to describe a role for the medium-chain fatty acid (MCFA) receptor G-protein-coupled receptor (Gpr) 84 in skeletal muscle mitochondrial function and insulin secretion. We are able to show that Gpr84 is highly expressed in skeletal muscle and adipose tissue. Mice with global deletion of Gpr84 [Gpr84 knockout (KO)] exhibit a mild impairment in glucose tolerance when fed a MCFA-enriched diet. Studies in mice and pancreatic islets suggest that glucose intolerance is accompanied by a defect in insulin secretion. MCFA-fed KO mice also exhibit a significant impairment in the intrinsic respiratory capacity of their skeletal muscle mitochondria, but at the same time also exhibit a substantial increase in mitochondrial content. Changes in canonical pathways of mitochondrial biogenesis and turnover are unable to explain these mitochondrial differences. Our results show that Gpr84 plays a crucial role in regulating mitochondrial function and quality control.-Montgomery, M. K., Osborne, B., Brandon, A. E., O'Reilly, L., Fiveash, C. E., Brown, S. H. J., Wilkins, B. P., Samsudeen, A., Yu, J., Devanapalli, B., Hertzog, A., Tolun, A. A., Kavanagh, T., Cooper, A. A., Mitchell, T. W., Biden, T. J., Smith, N. J., Cooney, G. J., Turner, N. Regulation of mitochondrial metabolism in murine skeletal muscle by the medium-chain fatty acid receptor Gpr84.
| S-EPMC9292139 | biostudies-literature
Project description:GPR84 is an orphan class A G protein-coupled receptor (GPCR) that is predominantly expressed in immune cells and plays important roles in inflammation, fibrosis, and metabolism. Here, we present cryo-electron microscopy (cryo-EM) structures of Gαi protein-coupled human GPR84 bound to a synthetic lipid-mimetic ligand, LY237, or a putative endogenous ligand, a medium-chain fatty acid (MCFA) 3-hydroxy lauric acid (3-OH-C12). Analysis of these two ligand-bound structures reveals a unique hydrophobic nonane tail -contacting patch, which forms a blocking wall to select MCFA-like agonists with the correct length. We also identify the structural features in GPR84 that coordinate the polar ends of LY237 and 3-OH-C12, including the interactions with the positively charged side chain of R172 and the downward movement of the extracellular loop 2 (ECL2). Together with molecular dynamics simulations and functional data, our structures reveal that ECL2 not only contributes to direct ligand binding, but also plays a pivotal role in ligand entry from the extracellular milieu. These insights into the structure and function of GPR84 could improve our understanding of ligand recognition, receptor activation, and Gαi-coupling of GPR84. Our structures could also facilitate rational drug discovery against inflammation and metabolic disorders targeting GPR84.
| S-EPMC10241960 | biostudies-literature
Project description:Fatty acids are derived from diet and fermentative processes by the intestinal flora. Two to five carbon chain fatty acids, termed short chain fatty acids (SCFA) are increasingly recognized to play a role in intestinal homeostasis. However, the characteristics of slightly longer 6 to 10 carbon, medium chain fatty acids (MCFA), derived primarily from diet, are less understood. Here, we demonstrated that SCFA and MCFA have divergent immunomodulatory propensities. SCFA down-attenuated host pro-inflammatory IL-1β, IL-6, and TNFα response predominantly through the TLR4 pathway, whereas MCFA augmented inflammation through TLR2. Butyric (C4) and decanoic (C10) acid displayed most potent modulatory effects within the SCFA and MCFA, respectively. Reduction in TRAF3, IRF3 and TRAF6 expression were observed with butyric acid. Decanoic acid induced up-regulation of GPR84 and PPARγ and altered HIF-1α/HIF-2α ratio. These variant immune characteristics of the fatty acids which differ by just several carbon atoms may be attributable to their origins, with SCFA being primarily endogenous and playing a physiological role, and MCFA exogenously from the diet.
| S-EPMC8234078 | biostudies-literature
Project description:Medium chain fatty acid (MCFAs) synthesis Metagenome
| PRJNA950190 | ENA
Project description:Concerns about global warming, fossil-fuel depletion, food security, and human health have promoted metabolic engineers to develop tools/strategies to overproduce microbial functional oils directly from renewable resources. Medium-chain fatty acids (MCFAs, C8-C12) have been shown to be important sources due to their diverse biotechnological importance, providing benefits ranging from functional lipids to uses in bio-fuel production. However, oleaginous microbes do not carry native pathways for the production of MCFAs, and therefore, diverse approaches have been adapted to compensate for the requirements of industrial demand. Mucor circinelloides is a promising organism for lipid production (15-36% cell dry weight; CDW) and the investigation of mechanisms of lipid accumulation; however, it mostly produces long-chain fatty acids (LCFAs). To address this challenge, we genetically modified strain M. circinelloides MU758, first by integrating heterologous acyl-ACP thioesterase (TE) into fatty acid synthase (FAS) complex and subsequently by modifying the ?-oxidation pathway by disrupting the acyl-CoA oxidase (ACOX) and/or acyl-CoA thioesterase (ACOT) genes with a preference for medium-chain acyl-CoAs, to elevate the yield of MCFAs. The resultant mutant strains (M-1, M-2, and M-3, respectively) showed a significant increase in lipid production in comparison to the wild-type strain (WT). MCFAs in M-1 (47.45%) was sharply increased compared to the wild type strain (2.25%), and it was further increased in M-2 (60.09%) suggesting a negative role of ACOX in MCFAs production. However, MCFAs in M-3 were much decreased compared to M-1,suggesting a positive role of ACOT in MCFAs production. The M-2 strain showed maximum lipid productivity (~1800 milligram per liter per day or mg/L.d) and MCFAs productivity (~1100 mg/L.d). Taken together, this study elaborates on how the combination of two multidimensional approaches, TE gene over-expression and modification of the ?-oxidation pathway via substantial knockout of specific ACOX gene, significantly increased the production of MCFAs. This synergistic approach ultimately offers a novel opportunity for synthetic/industrial biologists to increase the content of MCFAs.
| S-EPMC7464202 | biostudies-literature