Publications by authors named "Thue W Schwartz"

139 Publications

Adhesion receptor ADGRG2/GPR64 is in the GI-tract selectively expressed in mature intestinal tuft cells.

Mol Metab 2021 Apr 5;51:101231. Epub 2021 Apr 5.

NNF Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, Denmark. Electronic address:

Objective: GPR64/ADGRG2 is an orphan Adhesion G protein-coupled receptor (ADGR) known to be mainly expressed in the parathyroid gland and epididymis. This investigation aimed to delineate the cellular expression of GPR64 throughout the body with focus on the gastrointestinal (GI) tract.

Methods: Transgenic Gpr64 reporter mice were histologically examined throughout the body and reporter protein expression in intestinal tuft cells was confirmed by specific cell ablation. The GPCR repertoire of intestinal Gpr64-positive tuft cells was analyzed by quantitative RT-PCR analysis and in situ hybridization. The Gpr64 was crossed into the general tuft cell reporter Trpm5 to generate small intestinal organoids for time-lapse imaging. Intestinal tuft cells were isolated from small intestine, FACS-purified and transcriptionally compared using RNA-seq analysis.

Results: Expression of the Gpr64 reporter was identified in multiple organs and specifically in olfactory microvillous cells, enteric nerves, and importantly in respiratory and GI tuft cells. In the small intestine, cell ablation targeting Gpr64-expressing epithelial cells eliminated tuft cells. Transcriptional analysis of small intestinal Gpr64 -positive tuft cells confirmed expression of Gpr64 and the chemo-sensors Sucnr1, Gprc5c, Drd3, and Gpr41/Ffar3. Time-lapse studies of organoids from Trpm5:Gpr64 mice revealed sequential expression of initially Trpm5 and subsequently also Gpr64 in maturing intestinal tuft cells. RNA-seq analysis of small intestinal tuft cells based on these two markers demonstrated a dynamic change in expression of transcription factors and GPCRs from young to mature tuft cells.

Conclusions: GPR64 is expressed in chemosensory epithelial cells across a broad range of tissues; however, in the GI tract, GPR64 is remarkably selectively expressed in mature versus young immunoregulatory tuft cells.
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http://dx.doi.org/10.1016/j.molmet.2021.101231DOI Listing
April 2021

Post-oral fat-induced satiation is mediated by endogenous CCK and GLP-1 in a fat self-administration mouse model.

Physiol Behav 2021 May 15;234:113315. Epub 2021 Jan 15.

Department of Drug Design and Pharmacology, University of Copenhagen, Jagtvej 160, DK-2100 Copenhagen, Denmark. Electronic address:

Triacylglycerol is the most abundant dietary lipid, and a strong stimulator of satiation. Absorption of triacylglycerol in the small intestine occurs in the form of free fatty acids and 2-monoacylglycerol, a process known to trigger not only the release of cholecystokinin (CCK) but also glucagon-like peptide 1 (GLP-1) and peptide YY (PYY). It remains controversial, however, whether endogenously released GLP-1 and PYY are required for fat-induced satiation. Using a self-administration model where mice are trained to self-administer Intralipid 30% intragastrically, we show that blocking the CCK receptors with intraperitoneal devazepide diminishes the post-oral satiation effect of ingested fat. Similarly, s.c. administration of a GLP-1 receptor antagonist with a prolonged half-life (Jant4-C16) also reduced the post-oral satiation effect of ingested fat. Importantly, coadministration of the GLP-1 antagonist together with devazepide increased fat self-infusions to a level equal to the combined blockade of each individual peptide action alone, indicating an additive effect of endogenous CCK and GLP-1 in fat satiation signaling. Blocking the PYY Y receptor did not further enhance the fat intake in devazepide-treated mice. Consistent with the above, we show that voluntary post-oral ingestion of fat increases CCK and GLP-1 plasma levels and is correlated positively with CCK and GLP-1 plasma concentrations. Taken together, our results support the role of endogenous GLP-1 in the regulation of fat intake and suggest that both CCK and GLP-1 are required for the fat satiation signaling.
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http://dx.doi.org/10.1016/j.physbeh.2021.113315DOI Listing
May 2021

snRNA-seq reveals a subpopulation of adipocytes that regulates thermogenesis.

Nature 2020 11 28;587(7832):98-102. Epub 2020 Oct 28.

Institute of Food, Nutrition and Health, ETH Zurich, Schwerzenbach, Switzerland.

Adipose tissue is usually classified on the basis of its function as white, brown or beige (brite). It is an important regulator of systemic metabolism, as shown by the fact that dysfunctional adipose tissue in obesity leads to a variety of secondary metabolic complications. In addition, adipose tissue functions as a signalling hub that regulates systemic metabolism through paracrine and endocrine signals. Here we use single-nucleus RNA-sequencing (snRNA-seq) analysis in mice and humans to characterize adipocyte heterogeneity. We identify a rare subpopulation of adipocytes in mice that increases in abundance at higher temperatures, and we show that this subpopulation regulates the activity of neighbouring adipocytes through acetate-mediated modulation of their thermogenic capacity. Human adipose tissue contains higher numbers of cells of this subpopulation, which could explain the lower thermogenic activity of human compared to mouse adipose tissue and suggests that targeting this pathway could be used to restore thermogenic activity.
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http://dx.doi.org/10.1038/s41586-020-2856-xDOI Listing
November 2020

Autocrine negative feedback regulation of lipolysis through sensing of NEFAs by FFAR4/GPR120 in WAT.

Mol Metab 2020 12 19;42:101103. Epub 2020 Oct 19.

Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, Denmark. Electronic address:

Objectives: Long-chain fatty acids (LCFAs) released from adipocytes inhibit lipolysis through an unclear mechanism. We hypothesized that the LCFA receptor, FFAR4 (GPR120), which is highly expressed in adipocytes, may be involved in this feedback regulation.

Methods And Results: Liquid chromatography mass spectrometry (LC-MS) analysis of conditioned media from isoproterenol-stimulated primary cultures of murine and human adipocytes demonstrated that most of the released non-esterified free fatty acids (NEFAs) are known agonists for FFAR4. In agreement with this, conditioned medium from isoproterenol-treated adipocytes stimulated signaling strongly in FFAR4 transfected COS-7 cells as opposed to non-transfected control cells. In transfected 3T3-L1 cells, FFAR4 agonism stimulated Gi- and Go-mini G protein binding more strongly than Gq, effects which were blocked by the selective FFAR4 antagonist AH7614. In primary cultures of murine white adipocytes, the synthetic, selective FFAR4 agonist CpdA inhibited isoproterenol-induced intracellular cAMP accumulation in a manner similar to the antilipolytic control agent nicotinic acid acting through another receptor, HCAR2. In vivo, oral gavage with the synthetic, specific FFAR4 agonist CpdB decreased the level of circulating NEFAs in fasting lean mice to a similar degree as nicotinic acid. In agreement with the identified anti-lipolytic effect of FFAR4, plasma NEFAs and glycerol were increased in FFAR4-deficient mice as compared to littermate controls despite having elevated insulin levels, and cAMP accumulation in primary adipocyte cultures was augmented by treatment with the FFAR4 antagonist conceivably by blocking the stimulatory tone of endogenous NEFAs on FFAR4.

Conclusions: In white adipocytes, FFAR4 functions as an NEFA-activated, autocrine, negative feedback regulator of lipolysis by decreasing cAMP though Gi-mediated signaling.
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http://dx.doi.org/10.1016/j.molmet.2020.101103DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7683346PMC
December 2020

Synthetic G protein-coupled bile acid receptor agonists and bile acids act via basolateral receptors in ileal and colonic mucosa.

Neurogastroenterol Motil 2020 12 12;32(12):e13943. Epub 2020 Jul 12.

King's College London, Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, London, UK.

Background: The G protein-coupled bile acid (BA) receptor, GPBA (previously named TGR5), mediates BA gastrointestinal (GI) activities. Our aim was to elucidate the mucosal and motility responses to selective GPBA agonists compared with conjugated BA (eg, taurodeoxycholate, TDCA) in mouse and human colon.

Methods: Ion transport responses to GPBA agonists or BAs were measured in mucosal preparations with intact submucous innervation, from C57Bl/6, PYY-/-, or GPBA-/- mice and compared with GPBA signaling in human colon. We also investigated the mechanisms underlying GPBA agonism in mucosae and on natural fecal pellet propulsion.

Key Results: GPBA agonist Merck V stimulated basolateral responses involving peptide YY (PYY), cholinergic, and 5-HT mechanisms in colonic mucosa. The PYY-mediated GPBA signal was glucose-sensitive. Luminal TDCA crossed the epithelial lining via the apical sodium-dependent BA transporter (ASBT) and its inhibitor, GSK2330672 significantly reduced luminal, but not basolateral TDCA activity. Merck V also slowed natural fecal pellet progression in wild-type and PYY-/- colons but not in GPBA-/- colon, while TDCA increased motility in wild-type colon. The antimotile GPBA effect was reversed by blockade of glucagon-like peptide 1 (GLP-1) receptors or nitric oxide synthase, indicating involvement of GLP-1 and nitric oxide.

Conclusions & Inferences: We conclude that several different targets within the lamina propria express GPBA, including L cells (that release PYY and GLP-1), enterochromaffin cells and neurons (that release 5-HT), and other enteric neurons. Furthermore, luminal-conjugated BAs require transport across the epithelium via ASBT in order to activate basolateral GPBA.
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http://dx.doi.org/10.1111/nmo.13943DOI Listing
December 2020

Why Warburg Works: Lactate Controls Immune Evasion through GPR81.

Cell Metab 2020 04;31(4):666-668

Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, The Mærsk Tower, The Panum Institute, 2200 Copenhagen, Denmark. Electronic address:

Lactate accumulation in tumors-a hallmark of the Warburg effect-has recently been shown to regulate cancer cell metabolism and survival through autocrine activation of GPR81. Now, Brown et al. (2020) demonstrate that lactate surprisingly also controls immune evasion through paracrine activation of GPR81 on stromal dendritic cells.
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http://dx.doi.org/10.1016/j.cmet.2020.03.001DOI Listing
April 2020

L-Cell Differentiation Is Induced by Bile Acids Through GPBAR1 and Paracrine GLP-1 and Serotonin Signaling.

Diabetes 2020 04 10;69(4):614-623. Epub 2020 Feb 10.

Novo Nordisk Foundation Center for Basic Metabolic Research Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark

Glucagon-like peptide 1 (GLP-1) mimetics are effective drugs for treatment of type 2 diabetes, and there is consequently extensive interest in increasing endogenous GLP-1 secretion and L-cell abundance. Here we identify G-protein-coupled bile acid receptor 1 (GPBAR1) as a selective regulator of intestinal L-cell differentiation. Lithocholic acid and the synthetic GPBAR1 agonist, L3740, selectively increased L-cell density in mouse and human intestinal organoids and elevated GLP-1 secretory capacity. L3740 induced expression of and transcription factors and L3740 also increased the L-cell number and GLP-1 levels and improved glucose tolerance in vivo. Further mechanistic examination revealed that the effect of L3740 on L cells required intact GLP-1 receptor and serotonin 5-hydroxytryptamine receptor 4 (5-HT4) signaling. Importantly, serotonin signaling through 5-HT4 mimicked the effects of L3740, acting downstream of GLP-1. Thus, GPBAR1 agonists and other powerful GLP-1 secretagogues facilitate L-cell differentiation through a paracrine GLP-1-dependent and serotonin-mediated mechanism.
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http://dx.doi.org/10.2337/db19-0764DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7224989PMC
April 2020

Structural basis for GPCR signaling by small polar versus large lipid metabolites-discovery of non-metabolite ligands.

Curr Opin Cell Biol 2020 04 14;63:38-48. Epub 2020 Jan 14.

Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Maersk Tower, Blegdamsvej 3B, DK-2200, Copenhagen, Denmark. Electronic address:

Key metabolites act through specific G protein-coupled receptors (GPCRs) as extracellular signals of fuel availability and metabolic stress. Here, we focus on the succinate receptor SUCNR1/GPR91 and the long chain fatty acid receptor FFAR1/GPR40, for which 3D structural information is available. Like other small polar acidic metabolites, succinate is excreted from the cell by transporter proteins to bind to an extracellular, solvent-exposed pocket in SUCNR1. Non-metabolite pharmacological tool compounds are currently being designed based on the structure of the SUCNR1 binding pocket. In FFAR1, differently signaling lipid mimetics bind in two distinct membrane-exposed sites corresponding to each of the lipid bilayer leaflets. Conceivably endogenous lipid ligands gain access to these sites by way of the membrane and probably occupy both sites under physiological circumstances. Design of polar agonists for a dynamic, solvent-exposed pocket in FFAR1 underlines the possibility of structure-based approaches for development of novel tool compounds even in lipid sensing metabolite GPCRs.
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http://dx.doi.org/10.1016/j.ceb.2019.12.005DOI Listing
April 2020

Activation of metabolite receptor GPR91 promotes platelet aggregation and transcellular biosynthesis of leukotriene C.

J Thromb Haemost 2020 04 17;18(4):976-984. Epub 2020 Feb 17.

Division of Physiological Chemistry II, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.

Background: Succinate is a Krebs cycle intermediate whose formation is enhanced under metabolic stress, and for which a selective sensor GPR91 has been identified on various cell types including platelets. Platelet-derived eicosanoids play pivotal roles in platelet activation/aggregation, which is key to thrombus formation and progression of atherothrombosis.

Objectives: This study aims to decipher the molecular mechanism(s) and potential involvement of eicosanoids in succinate enhanced platelet activation/aggregation.

Methods: We used liquid chromatography-mass spectrometry (LC-MS)/MS-based lipid mediator profiling to identify eicosanoids regulated by succinate. We ran light transmittance aggregometry and flow cytometry to assess platelet aggregation, P-selectin expression, and platelet-polymorphonuclear leukocyte (PMN) adherence. Various pharmacological tools were used to assess the contributions of GPR91 signalling and eicosanoids in platelet aggregation.

Results: Succinate and two types of synthetic non-metabolite GPR91 agonists-cis-epoxysuccinate (cES) and Cmpd131-potentiated platelet aggregation, which was partially blocked by a selective GPR91 antagonist XT1. GPR91 activation increased production of 12-hydroxy-eicosatetraenoic acid (12-HETE), thromboxane (TX) A , and 12-hydroxy-heptadecatrienoic acid (12-HHT) in human platelets, associated with phosphorylation of cytosolic phospholipase A (cPLA ), suggesting increased availability of free arachidonic acid. Blocking 12-HETE and TXA synthesis, or antagonism of the TXA receptor, significantly reduced platelet aggregation enhanced by GPR91 signalling. Moreover, platelet-PMN suspensions challenged with succinate exhibited enhanced transcellular biosynthesis of leukotriene C (LTC ), a powerful proinflammatory vascular spasmogen.

Conclusion: Succinate signals through GPR91 to promote biosynthesis of eicosanoids, which contribute to platelet aggregation/activation and potentially vascular inflammation. Hence, GPR91 may be a suitable target for pharmacological intervention in atherothrombotic conditions.
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http://dx.doi.org/10.1111/jth.14734DOI Listing
April 2020

-acyl taurines are endogenous lipid messengers that improve glucose homeostasis.

Proc Natl Acad Sci U S A 2019 12 18;116(49):24770-24778. Epub 2019 Nov 18.

Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark;

Fatty acid amide hydrolase (FAAH) degrades 2 major classes of bioactive fatty acid amides, the -acylethanolamines (NAEs) and -acyl taurines (NATs), in central and peripheral tissues. A functional polymorphism in the human gene is linked to obesity and mice lacking FAAH show altered metabolic states, but whether these phenotypes are caused by elevations in NAEs or NATs is unknown. To overcome the problem of concurrent elevation of NAEs and NATs caused by genetic or pharmacological disruption of FAAH in vivo, we developed an engineered mouse model harboring a single-amino acid substitution in FAAH (S268D) that selectively disrupts NAT, but not NAE, hydrolytic activity. The FAAH-S268D mice accordingly show substantial elevations in NATs without alterations in NAE content, a unique metabolic profile that correlates with heightened insulin sensitivity and GLP-1 secretion. We also show that -oleoyl taurine (C18:1 NAT), the most abundant NAT in human plasma, decreases food intake, improves glucose tolerance, and stimulates GPR119-dependent GLP-1 and glucagon secretion in mice. Together, these data suggest that NATs act as a class of lipid messengers that improve postprandial glucose regulation and may have potential as investigational metabolites to modify metabolic disease.
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http://dx.doi.org/10.1073/pnas.1916288116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6900532PMC
December 2019

Rfx6 promotes the differentiation of peptide-secreting enteroendocrine cells while repressing genetic programs controlling serotonin production.

Mol Metab 2019 11 13;29:24-39. Epub 2019 Aug 13.

Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France; Institut National de la Santé et de la Recherche Médicale (INSERM) U1258, Illkirch, France; Centre National de la Recherche Scientifique (CNRS) UMR7104, Illkirch, France; Université de Strasbourg, Illkirch, France. Electronic address:

Objective: Enteroendocrine cells (EECs) of the gastro-intestinal tract sense gut luminal factors and release peptide hormones or serotonin (5-HT) to coordinate energy uptake and storage. Our goal is to decipher the gene regulatory networks controlling EECs specification from enteroendocrine progenitors. In this context, we studied the role of the transcription factor Rfx6 which had been identified as the cause of Mitchell-Riley syndrome, characterized by neonatal diabetes and congenital malabsorptive diarrhea. We previously reported that Rfx6 was essential for pancreatic beta cell development and function; however, the role of Rfx6 in EECs differentiation remained to be elucidated.

Methods: We examined the molecular, cellular, and metabolic consequences of constitutive and conditional deletion of Rfx6 in the embryonic and adult mouse intestine. We performed single cell and bulk RNA-Seq to characterize EECs diversity and identify Rfx6-regulated genes.

Results: Rfx6 is expressed in the gut endoderm; later, it is turned on in, and restricted to, enteroendocrine progenitors and persists in hormone-positive EECs. In the embryonic intestine, the constitutive lack of Rfx6 leads to gastric heterotopia, suggesting a role in the maintenance of intestinal identity. In the absence of intestinal Rfx6, EECs differentiation is severely impaired both in the embryo and adult. However, the number of serotonin-producing enterochromaffin cells and mucosal 5-HT content are increased. Concomitantly, Neurog3-positive enteroendocrine progenitors accumulate. Combined analysis of single-cell and bulk RNA-Seq data revealed that enteroendocrine progenitors differentiate in two main cell trajectories, the enterochromaffin (EC) cells and the Peptidergic Enteroendocrine (PE) cells, the differentiation programs of which are differentially regulated by Rfx6. Rfx6 operates upstream of Arx, Pax6 and Isl1 to trigger the differentiation of peptidergic EECs such as GIP-, GLP-1-, or CCK-secreting cells. On the contrary, Rfx6 represses Lmx1a and Tph1, two genes essential for serotonin biosynthesis. Finally, we identified transcriptional changes uncovering adaptive responses to the prolonged lack of enteroendocrine hormones and leading to malabsorption and lower food efficiency ratio in Rfx6-deficient mouse intestine.

Conclusion: These studies identify Rfx6 as an essential transcriptional regulator of EECs specification and shed light on the molecular mechanisms of intestinal failures in human RFX6-deficiencies such as Mitchell-Riley syndrome.
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http://dx.doi.org/10.1016/j.molmet.2019.08.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6728766PMC
November 2019

Paracrine crosstalk between intestinal L- and D-cells controls secretion of glucagon-like peptide-1 in mice.

Am J Physiol Endocrinol Metab 2019 12 10;317(6):E1081-E1093. Epub 2019 Sep 10.

Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.

DPP-4 inhibitors, used for treatment of type 2 diabetes, act by increasing the concentrations of intact glucagon-like peptide-1 (GLP-1), but at the same time, they inhibit secretion of GLP-1, perhaps by a negative feedback mechanism. We hypothesized that GLP-1 secretion is feedback regulated by somatostatin (SS) from neighboring D-cells, and blocking this feedback circuit results in increased GLP-1 secretion. We used a wide range of experimental techniques, including gene expression analysis, immunohistochemical approaches, and the perfused mouse intestine to characterize the paracrine circuit controlling GLP-1 and SS. We show that ) antagonizing the SS receptor (SSTr) 2 and SSTr5 led to increased GLP-1 and SS secretion in the mouse, ) SS exhibits strong tonic inhibition of GLP-1 secretion preferentially through SSTr5, and ) the secretion of S was GLP-1 receptor dependent. We conclude that SS is a tonic inhibitor of GLP-1 secretion, and interventions in the somatostain-GLP-1 paracrine loop lead to increased GLP-1 secretion.
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http://dx.doi.org/10.1152/ajpendo.00239.2019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6962500PMC
December 2019

The Molecular Diversity of Vagal Afferents Revealed.

Trends Neurosci 2019 10 14;42(10):663-666. Epub 2019 Aug 14.

Division of Hypothalamic Research and Department of Internal Medicine, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390, USA. Electronic address:

Using single-cell RNA sequencing (RNA-seq), Kupari and coworkers (Cell Rep., 2019) have generated a long sought-after molecular atlas of vagal afferents in the mouse. Vagal afferents were found to be organized into 24 subtypes, revealing a level of diversity that was not previously recognized.
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http://dx.doi.org/10.1016/j.tins.2019.08.002DOI Listing
October 2019

Molecular dynamics-guided discovery of an ago-allosteric modulator for GPR40/FFAR1.

Proc Natl Acad Sci U S A 2019 04 14;116(14):7123-7128. Epub 2019 Mar 14.

Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, DL-2200 Copenhagen, Denmark;

The long-chain fatty acid receptor FFAR1/GPR40 binds agonists in both an interhelical site between the extracellular segments of transmembrane helix (TM)-III and TM-IV and a lipid-exposed groove between the intracellular segments of these helices. Molecular dynamics simulations of FFAR1 with agonist removed demonstrated a major rearrangement of the polar and charged anchor point residues for the carboxylic acid moiety of the agonist in the interhelical site, which was associated with closure of a neighboring, solvent-exposed pocket between the extracellular poles of TM-I, TM-II, and TM-VII. A synthetic compound designed to bind in this pocket, and thereby prevent its closure, was identified through structure-based virtual screening and shown to function both as an agonist and as an allosteric modulator of receptor activation. This discovery of an allosteric agonist for a previously unexploited, dynamic pocket in FFAR1 demonstrates both the power of including molecular dynamics in the drug discovery process and that this specific, clinically proven, but difficult, antidiabetes target can be addressed by chemotypes different from existing ligands.
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http://dx.doi.org/10.1073/pnas.1811066116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6452680PMC
April 2019

Human substance P receptor binding mode of the antagonist drug aprepitant by NMR and crystallography.

Nat Commun 2019 02 7;10(1):638. Epub 2019 Feb 7.

State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Pudong, Shanghai, 201203, China.

Neurokinin 1 receptor (NK1R) has key regulating functions in the central and peripheral nervous systems, and NK1R antagonists such as aprepitant have been approved for treating chemotherapy-induced nausea and vomiting. However, the lack of data on NK1R structure and biochemistry has limited further drug development targeting this receptor. Here, we combine NMR spectroscopy and X-ray crystallography to provide dynamic and static characterisation of the binding mode of aprepitant in complexes with human NK1R variants. F-NMR showed a slow off-rate in the binding site, where aprepitant occupies multiple substates that exchange with frequencies in the millisecond range. The environment of the bound ligand is affected by the amino acid in position 2.50, which plays a key role in ligand binding and receptor signaling in class A GPCRs. Crystal structures now reveal how receptor signaling relates to the conformation of the conserved NPxxY motif in transmembrane helix VII.
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http://dx.doi.org/10.1038/s41467-019-08568-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6367319PMC
February 2019

Molecular adaptations in human subcutaneous adipose tissue after ten weeks of endurance exercise training in healthy males.

J Appl Physiol (1985) 2019 03 20;126(3):569-577. Epub 2018 Dec 20.

Research Laboratory for Biochemical Pathology, Department of Clinical Medicine, Aarhus University , Aarhus , Denmark.

Endurance exercise training induces adaptations in metabolically active organs, but adaptations in human subcutaneous adipose tissue (scAT) remains incompletely understood. On the basis of animal studies, we hypothesized that endurance exercise training would increase the expression of proteins involved in lipolysis and glucose uptake in scAT. To test these hypotheses, 19 young and healthy males were randomized to either endurance exercise training (TR; age 18-24 yr; BMI 19.0-25.4 kg/m) or a nonexercising control group (CON; age 21-35 yr; BMI 20.5-28.8 kg/m). Abdominal subcutaneous fat biopsies and blood were obtained at rest before and after intervention. By using Western blotting and PCR, we determined expression of lipid droplet-associated proteins, various proteins involved in substrate metabolism, and mRNA abundance of cell surface G protein-coupled receptors (GPCRs). Adipose tissue insulin sensitivity was determined from fasting plasma insulin and nonesterified fatty acids (adipose tissue insulin resistance index; Adipo-IR). Adipo-IR improved in TR compared with CON ( P = 0.03). This was accompanied by increased insulin receptor (IR) protein expression in scAT with a 1.54-fold (SD 0.79) change from baseline in TR vs. 0.85 (SD 0.30) in CON ( P = 0.007). Additionally, hexokinase II (HKII) and succinate dehydrogenase complex subunit A (SDHA) protein increased in TR compared with CON ( P = 0.006 and P = 0.04, respectively). We did not observe changes in lipid droplet-associated proteins or mRNA abundance of GPCRs. Collectively, 10 weeks of endurance exercise training improved adipose tissue insulin sensitivity, which was accompanied by increased IR, HKII, and SDHA protein expression in scAT. We suggest that these adaptations contribute to an improved metabolic flexibility. NEW & NOTEWORTHY This study is the first to investigate the molecular adaptations in human subcutaneous adipose tissue (scAT) after endurance exercise training compared with a nonexercising control group. We show that endurance exercise training improves insulin sensitivity in human scAT, and this is accompanied by increased expression of insulin receptor, hexokinase II, and succinate dehydrogenase complex subunit A. Collectively, our data suggest that endurance exercise training induces molecular adaptations in human scAT, which may contribute to an improved metabolic flexibility.
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http://dx.doi.org/10.1152/japplphysiol.00989.2018DOI Listing
March 2019

Microbial fermentation of flaxseed fibers modulates the transcriptome of GPR41-expressing enteroendocrine cells and protects mice against diet-induced obesity.

Am J Physiol Endocrinol Metab 2019 03 18;316(3):E453-E463. Epub 2018 Dec 18.

Wallenberg Laboratory, Department of Molecular and Clinical Medicine, Institute of Medicine, University of Gothenburg , Gothenburg , Sweden.

Dietary fibers, an integral part of the human diet, require the enzymatic activity of the gut microbiota for complete metabolism into short-chain fatty acids (SCFAs). SCFAs are important modulators of host metabolism and physiology and act in part as signaling molecules by activating G protein-coupled receptors (GPCRs), such as GPR41. Flaxseed fibers improve metabolism in rodents and mice, but their fermentation profiles, effects on enteroendocrine cells, and associated metabolic benefits are unknown. We fed GPR41-red fluorescent protein mice, an enteroendocrine reporter mouse strain, chow, high-fat diet (HFD), or HFD supplemented either with 10% nonfermentable fiber cellulose or fermentable flaxseed fibers for 12 wk to assess changes in cecal gut microbiota, enteroendocrine cell transcriptome in the ileum and colon, and physiological parameters. We observed that flaxseed fibers restructured the gut microbiota and promoted proliferation of the genera Bifidobacterium and Akkermansia compared with HFD. The shifts in cecal bacterial composition restored levels of the SCFAs butyrate similar to the chow diet, resulting in colonic but not ileal enteroendocrine cell transcriptional changes in genes related to cell cycle, mRNA, and protein transport compared with HFD. Consistent with the effects on enteroendocrine functions, flaxseed fibers also protected mice from diet-induced obesity, potentially by preventing a reduction in energy expenditure induced by an HFD. Our study shows that flaxseed fibers alter cecal microbial ecology, are fermented to SCFAs in the cecum, and modulate enteroendocrine cell transcriptome in the colon, which may contribute to their metabolically favorable phenotype.
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http://dx.doi.org/10.1152/ajpendo.00391.2018DOI Listing
March 2019

Preassociation between the 5-HT serotonin receptor and G protein G: molecular determinants and association with low potency activation of adenylyl cyclase.

FASEB J 2019 03 3;33(3):3870-3886. Epub 2018 Dec 3.

Department of Pharmacology, Institute of Clinical Medicine, University of Oslo and Oslo University Hospital, Oslo, Norway.

According to early models of GPCR signaling, G proteins only interact with activated receptors. However, some GPCRs were shown to assemble with G proteins before receptor activation, in accordance with more recent models. Previously, we found that the 5-HT receptor, as opposed to the 5-HT receptor, was preassociated with G, but the molecular determinants for this interaction are still elusive. In a series of chimeric 5-HT receptors with intracellular segments from 5-HT, we determined the receptor-G protein interaction by performing antibody-immobilized fluorescence recovery after photobleaching and fluorescence resonance energy transfer. We identified the intracellular loop 3 and C-tail of the 5-HT receptor to be responsible for the preassociation with G, and we further delineated the TM5 extension in the intracellular loop 3 and helix 8 in the C-tail as the molecular determinants. These chimeric exchanges converted the 5-HT receptor into a collision-coupled receptor that recruited G proteins only upon agonist activation, whereas reciprocal exchanges converted 5-HT to a preassociated receptor. The 5-HT receptor displayed 2-component agonist-induced G signaling with high and low potency. In addition, the same segments were involved in low-potency signaling and preassociation. The correspondence between G preassociation and low-potency G signaling is a novel aspect of GPCR pharmacology.-Ulsund, A. H., Dahl, M., Frimurer, T. M., Manfra, O., Schwartz, T. W., Levy, F. O., Andressen, K. W. Preassociation between the 5-HT serotonin receptor and G protein G: molecular determinants and association with low potency activation of adenylyl cyclase.
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http://dx.doi.org/10.1096/fj.201800805RRDOI Listing
March 2019

The aromatic amino acid sensor GPR142 controls metabolism through balanced regulation of pancreatic and gut hormones.

Mol Metab 2019 01 5;19:49-64. Epub 2018 Nov 5.

Section for Metabolic Receptology, Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark; Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark. Electronic address:

Objectives: GPR142, which is highly expressed in pancreatic islets, has recently been deorphanized as a receptor for aromatic amino acids; however, its physiological role and pharmacological potential is unclear.

Methods And Results: We find that GPR142 is expressed not only in β- but also in α-cells of the islets as well as in enteroendocrine cells, and we confirm that GPR142 is a highly selective sensor of essential aromatic amino acids, in particular Trp and oligopeptides with N-terminal Trp. GPR142 knock-out mice displayed a very limited metabolic phenotype but demonstrated that L-Trp induced secretion of pancreatic and gut hormones is mediated through GPR142 but that the receptor is not required for protein-induced hormone secretion. A synthetic GPR142 agonist stimulated insulin and glucagon as well as GIP, CCK, and GLP-1 secretion. In particular, GIP secretion was sensitive to oral administration of the GPR142 agonist an effect which in contrast to the other hormones was blocked by protein load. Oral administration of the GPR142 agonist increased [H]-2-deoxyglucose uptake in muscle and fat depots mediated through insulin action while it lowered liver glycogen conceivably mediated through glucagon, and, consequently, it did not lower total blood glucose. Nevertheless, acute administration of the GPR142 agonist strongly improved oral glucose tolerance in both lean and obese mice as well as Zucker fatty rat. Six weeks in-feed chronic treatment with the GPR142 agonist did not affect body weight in DIO mice, but increased energy expenditure and carbohydrate utilization, lowered basal glucose, and improved insulin sensitivity.

Conclusions: GPR142 functions as a sensor of aromatic amino acids, controlling GIP but also CCK and GLP-1 as well as insulin and glucagon in the pancreas. GPR142 agonists could have novel interesting potential in modifying metabolism through a balanced action of gut hormones as well as both insulin and glucagon.
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http://dx.doi.org/10.1016/j.molmet.2018.10.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6323244PMC
January 2019

Structure-Activity Investigations and Optimisations of Non-metabolite Agonists for the Succinate Receptor 1.

Sci Rep 2018 07 3;8(1):10010. Epub 2018 Jul 3.

NNF Center for Basic Metabolic Research, Section for Metabolic Receptology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark.

The succinate receptor 1 (SUCNR1) is a receptor for the metabolite succinate, which functions as a metabolic stress signal in the liver, kidney, adipose tissue and the retina. However, potent non-metabolite tool compounds are needed to reveal the physiological role and pharmacological potential of SUCNR1. Recently, we published the discovery of a computationally receptor-structure derived non-metabolite SUCNR1 agonist series with high target selectivity. We here report our structure-activity exploration and optimisation that has resulted in the development of agonists with nanomolar potency and excellent solubility and stability properties in a number of in vitro assays. Ligand-guided receptor models with high discriminative power between binding of active and inactive compounds were developed for design of novel chemotypes.
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http://dx.doi.org/10.1038/s41598-018-28263-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6030209PMC
July 2018

Inhibiting RHOA Signaling in Mice Increases Glucose Tolerance and Numbers of Enteroendocrine and Other Secretory Cells in the Intestine.

Gastroenterology 2018 10 20;155(4):1164-1176.e2. Epub 2018 Jun 20.

Section of Metabolic Receptology, Novo Nordisk Foundation Center for Basic Metabolic Research Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.

Background & Aims: Glucagon-like peptide 1 (GLP1) is produced by L cells in the intestine, and agonists of the GLP1 receptor are effective in the treatment of diabetes. Levels of GLP1 increase with numbers of L cells. Therefore, agents that increase numbers of L cell might be developed for treatment of diabetes. Ras homologue family member A (RhoA) signaling through Rho-associated coiled-coil-containing protein kinases 1 and 2 (ROCK1 and ROCK2) controls cell differentiation, but it is not clear whether this pathway regulates enteroendocrine differentiation in the intestinal epithelium. We investigated the effects of Y-27632, an inhibitor of ROCK1 and ROCK2, on L-cell differentiation.

Methods: We collected intestinal tissues from GLU-Venus, GPR41-RFP, and Neurog3-RFP mice, in which the endocrine lineage is fluorescently labeled, for in vitro culture and histologic analysis. Small intestine organoids derived from these mice were cultured with Y-27632 and we measured percentages of L cells, expression of intestinal cell-specific markers, and secretion of GLP1 in medium. Mice were fed a normal chow or a high-fat diet and given Y-27632 or saline (control) and blood samples were collected for measurement of GLP1, insulin, and glucose.

Results: Incubation of intestinal organoids with Y-27632 increased numbers of L cells and secretion of GLP1. These increases were associated with upregulated expression of genes encoding intestinal hormones, neurogenin 3, neurogenic differentiation factor 1, forkhead box A1 and A2, and additional markers of secretory cells. Mice fed the normal chow diet and given Y-27632 had increased numbers of L cells in intestinal tissues, increased plasma levels of GLP1 and insulin, and lower blood levels of glucose compared with mice fed the normal chow diet and given saline. In mice with insulin resistance induced by the high-fat diet, administration of Y-27632 increased secretion of GLP1 and glucose tolerance compared with administration of saline.

Conclusions: In mouse intestinal organoids, an inhibitor of RhoA signaling increased the differentiation of the secretory lineage and the development of enteroendocrine cells. Inhibitors of RhoA signaling or other strategies to increase numbers of L cells might be developed for treatment of patients with type 2 diabetes or for increasing glucose tolerance.
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http://dx.doi.org/10.1053/j.gastro.2018.06.039DOI Listing
October 2018

Profiling of G protein-coupled receptors in vagal afferents reveals novel gut-to-brain sensing mechanisms.

Mol Metab 2018 06 3;12:62-75. Epub 2018 Apr 3.

Division of Hypothalamic Research and Department of Internal Medicine, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390, USA. Electronic address:

Objectives: G protein-coupled receptors (GPCRs) act as transmembrane molecular sensors of neurotransmitters, hormones, nutrients, and metabolites. Because unmyelinated vagal afferents richly innervate the gastrointestinal mucosa, gut-derived molecules may directly modulate the activity of vagal afferents through GPCRs. However, the types of GPCRs expressed in vagal afferents are largely unknown. Here, we determined the expression profile of all GPCRs expressed in vagal afferents of the mouse, with a special emphasis on those innervating the gastrointestinal tract.

Methods: Using a combination of high-throughput quantitative PCR, RNA sequencing, and in situ hybridization, we systematically quantified GPCRs expressed in vagal unmyelinated Na1.8-expressing afferents.

Results: GPCRs for gut hormones that were the most enriched in Na1.8-expressing vagal unmyelinated afferents included NTSR1, NPY2R, CCK1R, and to a lesser extent, GLP1R, but not GHSR and GIPR. Interestingly, both GLP1R and NPY2R were coexpressed with CCK1R. In contrast, NTSR1 was coexpressed with GPR65, a marker preferentially enriched in intestinal mucosal afferents. Only few microbiome-derived metabolite sensors such as GPR35 and, to a lesser extent, GPR119 and CaSR were identified in the Na1.8-expressing vagal afferents. GPCRs involved in lipid sensing and inflammation (e.g. CB1R, CYSLTR2, PTGER4), and neurotransmitters signaling (CHRM4, DRD2, CRHR2) were also highly enriched in Na1.8-expressing neurons. Finally, we identified 21 orphan GPCRs with unknown functions in vagal afferents.

Conclusion: Overall, this study provides a comprehensive description of GPCR-dependent sensing mechanisms in vagal afferents, including novel coexpression patterns, and conceivably coaction of key receptors for gut-derived molecules involved in gut-brain communication.
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http://dx.doi.org/10.1016/j.molmet.2018.03.016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6001940PMC
June 2018

Enterochromaffin 5-HT cells - A major target for GLP-1 and gut microbial metabolites.

Mol Metab 2018 05 10;11:70-83. Epub 2018 Mar 10.

Section for Metabolic Receptology, Novo Nordisk Foundation Center for Basic Metabolite Research, Faculty of Health Sciences, University of Copenhagen, Denmark; Laboratory for Molecular Pharmacology, Department for Biomedical Research, Faculty of Health Sciences, University of Copenhagen, Denmark. Electronic address:

Objectives: 5-HT storing enterochromaffin (EC) cells are believed to respond to nutrient and gut microbial components, and 5-HT receptor-expressing afferent vagal neurons have been described to be the major sensors of nutrients in the GI-tract. However, the molecular mechanism through which EC cells sense nutrients and gut microbiota is still unclear.

Methods And Results: TPH1, the 5-HT generating enzyme, and chromogranin A, an acidic protein responsible for secretory granule storage of 5-HT, were highly enriched in FACS-purified EC cells from both small intestine and colon using a 5-HT antibody-based method. Surprisingly, EC cells from the small intestine did not express GPCR sensors for lipid and protein metabolites, such as FFAR1, GPR119, GPBAR1 (TGR5), CaSR, and GPR142, in contrast to the neighboring GLP-1 storing enteroendocrine cell. However, the GLP-1 receptor was particularly highly expressed and enriched in EC cells as judged both by qPCR and by immunohistochemistry using a receptor antibody. GLP-1 receptor agonists robustly stimulated 5-HT secretion from intestinal preparations using both HPLC and a specific amperometric method. Colonic EC cells expressed many different types of known and potential GPCR sensors of microbial metabolites including three receptors for SCFAs, i.e. FFAR2, OLF78, and OLF558 and receptors for aromatic acids, GPR35; secondary bile acids GPBAR1; and acyl-amides and lactate, GPR132.

Conclusion: Nutrient metabolites apparently do not stimulate EC cells of the small intestine directly but through a paracrine mechanism involving GLP-1 secreted from neighboring enteroendocrine cells. In contrast, colonic EC cells are able to sense a multitude of different metabolites generated by the gut microbiota as well as gut hormones, including GLP-1.
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http://dx.doi.org/10.1016/j.molmet.2018.03.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6001397PMC
May 2018

Bidirectional GPR119 Agonism Requires Peptide YY and Glucose for Activity in Mouse and Human Colon Mucosa.

Endocrinology 2018 04;159(4):1704-1717

King's College London, Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology & Neuroscience, London, United Kingdom.

The lipid sensor G protein-coupled receptor 119 (GPR119) is highly expressed by enteroendocrine L-cells and pancreatic β-cells that release the hormones, peptide YY (PYY) and glucagonlike peptide 1, and insulin, respectively. Endogenous oleoylethanolamide (OEA) and the dietary metabolite, 2-monoacylglycerol (2-OG), can each activate GPR119. Here, we compared mucosal responses with selective, synthetic GPR119 agonists (AR440006 and AR231453) and the lipids, OEA, 2-OG, and N-oleoyldopamine (OLDA), monitoring epithelial ion transport as a readout for L-cell activity in native mouse and human gastrointestinal (GI) mucosae. We also assessed GPR119 modulation of colonic motility in wild-type (WT), GPR119-deficient (GPR119-/-), and PYY-deficient (PYY-/-) mice. The water-soluble GPR119 agonist, AR440006 (that cannot traverse epithelial tight junctions), elicited responses, when added apically or basolaterally in mouse and human colonic mucosae. In both species, GPR119 responses were PYY, Y1 receptor mediated, and glucose dependent. AR440006 efficacy matched the GI distribution of L-cells in WT tissues but was absent from GPR119-/- tissue. OEA and 2-OG responses were significantly reduced in the GPR119-/- colon, but OLDA responses were unchanged. Alternative L-cell activation via free fatty acid receptors 1, 3, and 4 and the G protein-coupled bile acid receptor TGR5 or by the melanocortin 4 receptor, was unchanged in GPR119-/- tissues. The GPR119 agonist slowed transit in WT but not the PYY-/- colon in vitro. AR440006 (intraperitoneally) slowed WT colonic and upper-GI transit significantly in vivo. These data indicate that luminal or blood-borne GPR119 agonism can stimulate L-cell PYY release with paracrine consequences and slower motility. We suggest that this glucose-dependent L-cell response to a gut-restricted GPR119 stimulus has potential therapeutic advantage in modulating insulinotropic signaling with reduced risk of hypoglycemia.
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http://dx.doi.org/10.1210/en.2017-03172DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5972582PMC
April 2018

The HETE Is on FFAR1 and Pancreatic Islet Cells.

Cell Metab 2018 02;27(2):273-275

Center for Basic Metabolic Research, University of Copenhagen, Denmark; Laboratory for Molecular Pharmacology, Department for Biomedical Research, Faculty of Health Sciences, University of Copenhagen, Denmark. Electronic address:

It is known but generally unappreciated that the fatty acid receptor FFAR1 (GPR40) is responsible for a major part of glucose-induced insulin secretion. This puzzling fact is now explained by Tunaru et al. (2018), who demonstrate that glucose-induced 20-hydroxyeicosatetraenoic acid (20-HETE) amplifies insulin secretion through autocrine activation of FFAR1.
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http://dx.doi.org/10.1016/j.cmet.2018.01.006DOI Listing
February 2018

Microbial regulation of the L cell transcriptome.

Sci Rep 2018 01 19;8(1):1207. Epub 2018 Jan 19.

Wallenberg Laboratory and Sahlgrenska Center for Cardiovascular and Metabolic Research, Department of Molecular and Clinical Medicine, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden.

L cells are an important class of enteroendocrine cells secreting hormones such as glucagon like peptide-1 and peptide YY that have several metabolic and physiological effects. The gut is home to trillions of bacteria affecting host physiology, but there has been limited understanding about how the microbiota affects gene expression in L cells. Thus, we rederived the reporter mouse strain, GLU-Venus expressing yellow fluorescent protein under the control of the proglucagon gene, as germ-free (GF). L cells from ileum and colon of GF and conventionally raised (CONV-R) GLU-Venus mice were isolated and subjected to transcriptomic profiling. We observed that the microbiota exerted major effects on ileal L cells. Gene Ontology enrichment analysis revealed that microbiota suppressed biological processes related to vesicle localization and synaptic vesicle cycling in L cells from ileum. This finding was corroborated by electron microscopy of L cells showing reduced numbers of vesicles as well as by demonstrating decreased intracellular GLP-1 content in primary cultures from ileum of CONV-R compared with GF GLU-Venus mice. By analysing L cells following colonization of GF mice we observed that the greatest transcriptional regulation was evident within 1 day of colonization. Thus, the microbiota has a rapid and pronounced effect on the L cell transcriptome, predominantly in the ileum.
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http://dx.doi.org/10.1038/s41598-017-18079-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5775357PMC
January 2018

Receptor structure-based discovery of non-metabolite agonists for the succinate receptor GPR91.

Mol Metab 2017 12 30;6(12):1585-1596. Epub 2017 Sep 30.

NNF Center for Basic Metabolic Research, Section for Metabolic Receptology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, Denmark; Laboratory for Molecular Pharmacology, Department of Biomedical Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, Denmark. Electronic address:

Objective: Besides functioning as an intracellular metabolite, succinate acts as a stress-induced extracellular signal through activation of GPR91 (SUCNR1) for which we lack suitable pharmacological tools.

Methods And Results: Here we first determined that the cis conformation of the succinate backbone is preferred and that certain backbone modifications are allowed for GPR91 activation. Through receptor modeling over the X-ray structure of the closely related P2Y1 receptor, we discovered that the binding pocket is partly occupied by a segment of an extracellular loop and that succinate therefore binds in a very different mode than generally believed. Importantly, an empty side-pocket is identified next to the succinate binding site. All this information formed the basis for a substructure-based search query, which, combined with molecular docking, was used in virtual screening of the ZINC database to pick two serial mini-libraries of a total of only 245 compounds from which sub-micromolar, selective GPR91 agonists of unique structures were identified. The best compounds were backbone-modified succinate analogs in which an amide-linked hydrophobic moiety docked into the side-pocket next to succinate as shown by both loss- and gain-of-function mutagenesis. These compounds displayed GPR91-dependent activity in altering cytokine expression in human M2 macrophages similar to succinate, and importantly were devoid of any effect on the major intracellular target, succinate dehydrogenase.

Conclusions: These novel, synthetic non-metabolite GPR91 agonists will be valuable both as pharmacological tools to delineate the GPR91-mediated functions of succinate and as leads for the development of GPR91-targeted drugs to potentially treat low grade metabolic inflammation and diabetic complications such as retinopathy and nephropathy.
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http://dx.doi.org/10.1016/j.molmet.2017.09.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5699910PMC
December 2017

Structural biology: Full monty of family B GPCRs.

Nat Chem Biol 2017 07;13(8):819-821

Section for Metabolic Receptology at the Center for Basic Metabolic Research at University of Copenhagen.

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http://dx.doi.org/10.1038/nchembio.2438DOI Listing
July 2017

GPCR-Mediated Signaling of Metabolites.

Cell Metab 2017 Apr;25(4):777-796

Section for Metabolic Receptology, Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, 2200 Copenhagen, Denmark; Laboratory for Molecular Pharmacology, Department for Biomedical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark. Electronic address:

In addition to their bioenergetic intracellular function, several classical metabolites act as extracellular signaling molecules activating cell-surface G-protein-coupled receptors (GPCRs), similar to hormones and neurotransmitters. "Signaling metabolites" generated from nutrients or by gut microbiota target primarily enteroendocrine, neuronal, and immune cells in the lamina propria of the gut mucosa and the liver and, through these tissues, the rest of the body. In contrast, metabolites from the intermediary metabolism act mainly as metabolic stress-induced autocrine and paracrine signals in adipose tissue, the liver, and the endocrine pancreas. Importantly, distinct metabolite GPCRs act as efficient pro- and anti-inflammatory regulators of key immune cells, and signaling metabolites may thus function as important drivers of the low-grade inflammation associated with insulin resistance and obesity. The concept of key metabolites as ligands for specific GPCRs has broadened our understanding of metabolic signaling significantly and provides a number of novel potential drug targets.
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http://dx.doi.org/10.1016/j.cmet.2017.03.008DOI Listing
April 2017

Model-Based Discovery of Synthetic Agonists for the Zn-Sensing G-Protein-Coupled Receptor 39 (GPR39) Reveals Novel Biological Functions.

J Med Chem 2017 02 23;60(3):886-898. Epub 2017 Jan 23.

Novo Nordisk Foundation Center for Protein Research, University of Copenhagen , Blegdamsvej 3, DK-2200, Copenhagen, Denmark.

The G-protein-coupled receptor 39 (GPR39) is a G-protein-coupled receptor activated by Zn. We used a homology model-based approach to identify small-molecule pharmacological tool compounds for the receptor. The method focused on a putative binding site in GPR39 for synthetic ligands and knowledge of ligand binding to other receptors with similar binding pockets to select iterative series of minilibraries. These libraries were cherry-picked from all commercially available synthetic compounds. A total of only 520 compounds were tested in vitro, making this method broadly applicable for tool compound development. The compounds of the initial library were inactive when tested alone, but lead compounds were identified using Zn as an allosteric enhancer. Highly selective, highly potent Zn-independent GPR39 agonists were found in subsequent minilibraries. These agonists identified GPR39 as a novel regulator of gastric somatostatin secretion.
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http://dx.doi.org/10.1021/acs.jmedchem.6b00648DOI Listing
February 2017