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Husted AS, Ekberg JH, Tripp E, Nissen TAD, Meijnikman S, O'Brien SL, Ulven T, Acherman Y, Bruin SC, Nieuwdorp M, Gerhart-Hines Z, Calebiro D, Dragsted LO, Schwartz TW. Autocrine negative feedback regulation of lipolysis through sensing of NEFAs by FFAR4/GPR120 in WAT. Mol Metab 2020; 42:101103. [PMID: 33091626 PMCID: PMC7683346 DOI: 10.1016/j.molmet.2020.101103] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/11/2020] [Accepted: 10/13/2020] [Indexed: 12/11/2022] Open
Abstract
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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Affiliation(s)
- Anna Sofie Husted
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, Denmark.
| | - Jeppe H Ekberg
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, Denmark.
| | - Emma Tripp
- Institute of Metabolism and Systems Research and Center of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham B15 2TT, United Kingdom.
| | - Tinne A D Nissen
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, Denmark.
| | - Stijn Meijnikman
- Departments of Internal and Experimental Vascular Medicine, Amsterdam University Medical Centers, Location AMC, Amsterdam, the Netherlands.
| | - Shannon L O'Brien
- Institute of Metabolism and Systems Research and Center of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham B15 2TT, United Kingdom.
| | - Trond Ulven
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark; Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
| | - Yair Acherman
- Department of Surgery, Spaarne Hospital, Hoofddorp, the Netherlands.
| | - Sjoerd C Bruin
- Department of Surgery, Spaarne Hospital, Hoofddorp, the Netherlands.
| | - Max Nieuwdorp
- Departments of Internal and Experimental Vascular Medicine, Amsterdam University Medical Centers, Location AMC, Amsterdam, the Netherlands.
| | - Zach Gerhart-Hines
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, Denmark.
| | - Davide Calebiro
- Institute of Metabolism and Systems Research and Center of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham B15 2TT, United Kingdom.
| | - Lars O Dragsted
- Department of Nutrition, Exercise, and Sports, Section of Preventive and Clinical Nutrition, University of Copenhagen, Rolighedsvej 30, Frederiksberg C, 1958, Denmark.
| | - Thue W Schwartz
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, Denmark.
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Arriola A, Biuw M, Walton M, Moss S, Pomeroy P. Selective blubber fatty acid mobilization in lactating gray seals (Halichoerus grypus). Physiol Biochem Zool 2013; 86:441-50. [PMID: 23799838 DOI: 10.1086/671446] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
During negative energy balance periods, fatty acids (FAs) are mobilized to cover the metabolic demands of the body. FAs from adipose tissue are selectively mobilized according to their carbon length (CL) and number of double bonds (DBs); however, studies in vivo have focused only on fasting and nonlactating animals. During lactation, UK gray seals fast for 18 d, mobilizing a large amount of lipid from blubber to sustain their own metabolic demands and the nutritional requirements of pups. We investigated FA mobilization in individual gray seal mothers from two UK colonies sampled in 2005 and 2006. Linear mixed-effects models were used to examine to what extent the mobilization observed from FAs in blubber can be explained as a function of FAs' CL and number of DBs. FAs were mobilized according to their structure, such that for a given CL, mobilization increased with the number of DBs, and for a given number of DBs, mobilization decreased as CL increased. This pattern of selective mobilization was very similar between colonies, although the relative amounts of component FAs in blubber at early lactation were different between them. FAs, which are considered crucial to pup development, were mobilized more than predicted by the model. This suggests that selective mobilization of FAs is not related solely to the physicochemical characteristics of the FAs but also to the needs of a growing pup.
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Affiliation(s)
- Aline Arriola
- Scottish Oceans Institute, University of St. Andrews, St. Andrews KY16 8LB, Scotland, United Kingdom.
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Mittendorfer B, Liem O, Patterson BW, Miles JM, Klein S. What does the measurement of whole-body fatty acid rate of appearance in plasma by using a fatty acid tracer really mean? Diabetes 2003; 52:1641-8. [PMID: 12829627 DOI: 10.2337/diabetes.52.7.1641] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We evaluated the validity of using a single fatty acid tracer to assess total plasma long-chain free fatty acid (FFA) kinetics and the relationship between the rate of appearance (R(a)) of fatty acids in plasma and the fatty acid composition of adipose tissue triglyceride (TG). A mixture of [(13)C]-labeled myristate, palmitate, stearate, oleate, and linoleate was infused in healthy men during basal conditions and during conditions that stimulate (epinephrine infusion) and inhibit (insulin infusion) lipolysis of adipose tissue TGs. Calculated total FFA, R(a) based on palmitate, oleate, or linoleate tracers, was within 15% of the measured sum of the individual fatty acid R(a) under all conditions, whereas stearate and myristate tracers consistently underestimated and overestimated total FFA R(a), respectively. The fatty acid R(a) profile closely matched the fatty acid profile of subcutaneous adipose tissue TGs during epinephrine infusion, but not during basal conditions and insulin infusion. Our data support the common practice of using labeled palmitate or oleate as fatty acid tracers for assessing total plasma FFA kinetics and suggest that a source of lipids other than adipose tissue TG release fatty acids into the systemic circulation.
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Affiliation(s)
- Bettina Mittendorfer
- Department of Internal Medicine and Center for Human Nutrition, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Abstract
Adipose tissue triacylglycerols represent the main storage of a wide spectrum of fatty acids differing by molecular structure. The release of individual fatty acids from adipose tissue is selective according to carbon chain length and unsaturation degree in vitro and in vivo in animal studies and also in humans. The mechanism of selective fatty acid mobilization from white fat cells is not known. Lipolysis is widely reported to work at a lipid-water interface where only small amounts of substrate are available. A preferential hydrolysis of a small triacylglycerol fraction enriched in certain triacylglycerol molecular species at the lipid-water interface and enzymological properties of hormone-sensitive lipase could explain the selective mobilization of fatty acids from fat cells. This selectivity could affect the individual fatty acid supply to tissues.
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Affiliation(s)
- Thierry Raclot
- Centre d'Ecologie et de Physiologie Energétiques, CNRS UPR 9010, associé à l'Université Louis Pasteur, 23 rue Becquerel, 67087 Strasbourg Cedex 2, France.
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Abstract
Triacylglycerols represent the main form of storage for a wide spectrum of fatty acids. Their utilization first involves mobilization from adipose tissue through lipolysis. The release of individual fatty acids from adipose tissue is selective in vitro and in vivo in animal studies and also in human subjects. Generally, fatty acids are more readily mobilized from fat cells when they are short-chain and unsaturated. This selectivity could affect the storage of individual fatty acids in adipose tissue, and their subsequent supply to tissues. The nature of the dietary fats could affect lipid homeostasis and body fat deposition. Dietary fish oil influences adipose tissue development in a site-specific manner as a function of diet and feeding period. A diet high in n-3 polyunsaturated fatty acids (PUFA) results in a preferential partitioning of ingested energy towards oxidation at the expense of storage. Fatty acids are important mediators of gene expression in the liver. Indeed, genes encoding both glycolytic and lipogenic enzymes and key metabolic enzymes involved in fatty acid oxidation are regulated by dietary PUFA. White adipose tissue could also be a target for PUFA control of gene expression. The treatment of pre-adipose cells by fatty acids induces the expression of numerous genes that encode proteins involved in fatty acid metabolism. The mechanisms of PUFA-mediated repression of gene expression in adipocytes seem to be different, at least partly, from those described in liver. Tissue-specific and site-specific factors are possibly involved in the specific effect of PUFA on gene expression, although other mechanisms cannot be excluded.
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Affiliation(s)
- T Raclot
- Centre d'Ecologie et Physiologie Energétiques, UPR 9010 CNRS, l'Université Louis Pasteur, Strasbourg, France.
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Abstract
An in vivo approach was taken to examine fatty acid esterification in adipose tissue using a coconut oil-enriched diet. Rats were fed a diet containing coconut oil (50% lauric acid) for six weeks. Triacylglycerols from perirenal adipose tissue were fractionated by silver nitrate-thin layer chromatography and, then, preparative gas chromatography. The distribution of 169 triacylglycerol types accounting for 97% of total triacylglycerols was determined. There was evidence for a very high content of mixed triacylglycerols composed of intermediate (12:0 and 14:0) and long acyl moieties. No significant differences were observed between the experimental distribution of triacylglycerol types and the random distribution, calculated from the total fatty acid composition. This indicated that most long chain triacylglycerols stored before coconut oil feeding would have been rearranged after the six weeks of coconut oil feeding. The experimental proportion of trilauroylglycerol reached 2%, as expected from its random proportion, and the proportions of dilauroylacylglycerols were slightly higher than the random values. Present results were compared with those previously obtained from triacylglycerols of adipose tissue of rats fed a low-fat standard diet. From our results and those of other authors, it is suggested that lauric acid is a good substrate for sn-glycero-3-phosphate acyltransferase and diacylglycerol acyltransferase in rat adipose tissue.
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Affiliation(s)
- M Bugaut
- Laboratoire de Physiologie Animale et de la Nutrition, Faculté des Sciences Mirande, Dijon, France
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Metz SA, Rice MG, Robertson RP. Applications and limitations of measurement of 15-keto,13,14-dihydro prostaglandin E2 in human blood by radioimmunoassay. PROSTAGLANDINS 1979; 17:839-61. [PMID: 504691 DOI: 10.1016/0090-6980(79)90057-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
It has been anticipated that the inherent limitations of radioimmunoassays for prostaglandin E (PGE) would be obviated by assays for its major circulating metabolite, 15-keto, 13,14-dihydro PGE2) which has a longer half-life in blood. We examined the effects of PGE2 infusion and alterations in lipolysis in vivo, and of clotting, prolonged storage and hemolysis in vitro, on KH2-PGE2 immunoreactivity in unextracted human plasma and serum samples. Indeed KH2-PGE2 levels rose several hundred fold during infusions of PGE2 at doses which cause little or no increment in peripheral PGE levels. During stimulation of lipolysis by infusions of epinephrine, apparent KH2-PGE2 levels rose five-fold. However, the dilution curve of plasma obtained during stimulation of lipolysis was not parallel to the standard curve; furthermore, apparent KH2-PGE2 levels were correlated strongly with free fatty acid (FFA) levels, suggesting that FFA's cross-reacted in the RIA weakly but significantly due to their very high molar concentration in blood. Clotting and prolonged storage of samples, but not hemolysis, also caused marked apparent increments in KH2-PGE2 levels. Competition curves using dilutions of such samples were again not parallel to the standard curves in plasma or buffer, but resembled dilution curves of samples containing high levels of FFA. These results suggest that handling of human blood samples for KH2-PGE2 measurement must be carefully standardized to avoid significant artifacts which presumably are due in part to fatty acids released from triglyceride stores in vivo or from disrupted membrane phospholipids in vitro. Unextracted plasma appears to be unsatisfactory for use in this RIA.
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