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Cruciani-Guglielmacci C, Le Stunff H, Magnan C. Brain lipid sensing and the neural control of energy balance. Biochimie 2024; 223:159-165. [PMID: 38825062 DOI: 10.1016/j.biochi.2024.05.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 05/23/2024] [Accepted: 05/25/2024] [Indexed: 06/04/2024]
Abstract
The central nervous system continuously detects circulating concentrations of lipids such as fatty acids and troglycerides. Once information has been detected, the central nervous system can in turn participate in the control of energy balance and blood sugar levels and in particular regulate the secretion and action of insulin. Neurons capable of detecting circulating lipid variations are located in the hypothalamus and in other regions such as the nucleus accumbens, the striatum or the hippocampus. An excess of lipids will have deleterious effects and may induce central lipotoxicity, in particular following local production of ceramides and the appearance of neuroinflammation which may lead to metabolic diseases such as obesity and type 2 diabetes.
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Affiliation(s)
| | - Hervé Le Stunff
- Paris-Saclay Institute of Neuroscience, CNRS UMR 9197, Université Paris-Sud, University Paris Saclay, Orsay, France
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2
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López M, Diéguez C, Tena-Sempere M, González-García I. Ceramides in the central control of metabolism. Trends Endocrinol Metab 2024:S1043-2760(24)00167-X. [PMID: 38972782 DOI: 10.1016/j.tem.2024.06.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2024] [Revised: 06/11/2024] [Accepted: 06/12/2024] [Indexed: 07/09/2024]
Abstract
Central ceramides regulate energy metabolism by impacting hypothalamic neurons. This allows ceramides to integrate endocrine signals - such as leptin, ghrelin, thyroid hormones, or estradiol - and to modulate the central control of puberty. In this forum article we discuss recent evidence suggesting that specific ceramide species and neuronal populations are involved in these effects.
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Affiliation(s)
- Miguel López
- Department of Physiology, CiMUS, University of Santiago de Compostela, Santiago de Compostela, 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706, Spain.
| | - Carlos Diéguez
- Department of Physiology, CiMUS, University of Santiago de Compostela, Santiago de Compostela, 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706, Spain
| | - Manuel Tena-Sempere
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706, Spain; Instituto Maimonides de Investigación Biomédica de Córdoba, Córdoba, Spain; Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba 14004, Spain
| | - Ismael González-García
- Department of Physiology, CiMUS, University of Santiago de Compostela, Santiago de Compostela, 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706, Spain.
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3
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Spaggiari R, Angelini S, Di Vincenzo A, Scaglione G, Morrone S, Finello V, Fagioli S, Castaldo F, Sanz JM, Sergi D, Passaro A. Ceramides as Emerging Players in Cardiovascular Disease: Focus on Their Pathogenetic Effects and Regulation by Diet. Adv Nutr 2024; 15:100252. [PMID: 38876397 PMCID: PMC11263787 DOI: 10.1016/j.advnut.2024.100252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 05/16/2024] [Accepted: 06/10/2024] [Indexed: 06/16/2024] Open
Abstract
Impaired lipid metabolism is a pivotal driver of cardiovascular disease (CVD). In this regard, the accumulation of ceramides within the circulation as well as in metabolically active tissues and atherosclerotic plaques is a direct consequence of derailed lipid metabolism. Ceramides may be at the nexus between impaired lipid metabolism and CVD. Indeed, although on one hand ceramides have been implicated in the pathogenesis of CVD, on the other specific ceramide subspecies have also been proposed as predictors of major adverse cardiovascular events. This review will provide an updated overview of the role of ceramides in the pathogenesis of CVD, as well as their pathogenetic mechanisms of action. Furthermore, the manuscript will cover the importance of ceramides as biomarkers to predict cardiovascular events and the role of diet, both in terms of nutrients and dietary patterns, in modulating ceramide metabolism and homeostasis.
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Affiliation(s)
- Riccardo Spaggiari
- Department of Translational Medicine, University of Ferrara, Via Luigi Borsari, Ferrara, Italy
| | - Sharon Angelini
- Department of Translational Medicine, University of Ferrara, Via Luigi Borsari, Ferrara, Italy
| | - Alessandra Di Vincenzo
- Department of Translational Medicine, University of Ferrara, Via Luigi Borsari, Ferrara, Italy
| | - Gerarda Scaglione
- Department of Translational Medicine, University of Ferrara, Via Luigi Borsari, Ferrara, Italy
| | - Sara Morrone
- Department of Translational Medicine, University of Ferrara, Via Luigi Borsari, Ferrara, Italy
| | - Veronica Finello
- Department of Translational Medicine, University of Ferrara, Via Luigi Borsari, Ferrara, Italy
| | - Sofia Fagioli
- Department of Translational Medicine, University of Ferrara, Via Luigi Borsari, Ferrara, Italy
| | - Fabiola Castaldo
- Department of Translational Medicine, University of Ferrara, Via Luigi Borsari, Ferrara, Italy
| | - Juana M Sanz
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Via Luigi Borsari, Ferrara, Italy
| | - Domenico Sergi
- Department of Translational Medicine, University of Ferrara, Via Luigi Borsari, Ferrara, Italy.
| | - Angelina Passaro
- Department of Translational Medicine, University of Ferrara, Via Luigi Borsari, Ferrara, Italy
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4
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Wilkerson JL, Tatum SM, Holland WL, Summers SA. Ceramides are fuel gauges on the drive to cardiometabolic disease. Physiol Rev 2024; 104:1061-1119. [PMID: 38300524 DOI: 10.1152/physrev.00008.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 01/23/2024] [Accepted: 01/25/2024] [Indexed: 02/02/2024] Open
Abstract
Ceramides are signals of fatty acid excess that accumulate when a cell's energetic needs have been met and its nutrient storage has reached capacity. As these sphingolipids accrue, they alter the metabolism and survival of cells throughout the body including in the heart, liver, blood vessels, skeletal muscle, brain, and kidney. These ceramide actions elicit the tissue dysfunction that underlies cardiometabolic diseases such as diabetes, coronary artery disease, metabolic-associated steatohepatitis, and heart failure. Here, we review the biosynthesis and degradation pathways that maintain ceramide levels in normal physiology and discuss how the loss of ceramide homeostasis drives cardiometabolic pathologies. We highlight signaling nodes that sense small changes in ceramides and in turn reprogram cellular metabolism and stimulate apoptosis. Finally, we evaluate the emerging therapeutic utility of these unique lipids as biomarkers that forecast disease risk and as targets of ceramide-lowering interventions that ameliorate disease.
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Affiliation(s)
- Joseph L Wilkerson
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, United States
| | - Sean M Tatum
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, United States
| | - William L Holland
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, United States
| | - Scott A Summers
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, United States
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5
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Corporeau C, Le Foll C, Cruciani-Guglielmacci C, Le Stunff H, Mithieux G, Magnan C, Delarue J. Fish oil minimises feed intake and improves insulin sensitivity in Zucker fa/fa rats. Br J Nutr 2024; 131:749-761. [PMID: 37877265 DOI: 10.1017/s0007114523002404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2023]
Abstract
Long-chain n-3 PUFA (LC n-3 PUFA) prevent, in rodents, insulin resistance (IR) induced by a high-fat and/or fructose diet but not IR induced by glucocorticoids. In humans, contrasting effects have also been reported. We investigated their effects on insulin sensitivity, feed intake (FI) and body weight gain in genetically insulin resistant male obese (fa/fa) Zucker (ZO) rats during the development of obesity. ZO rats were fed a diet supplemented with 7 % fish oil (FO) + 1 % corn oil (CO) (wt/wt) (ZOFO), while the control group was fed a diet containing 8 % fat from CO (wt/wt) (ZOCO). Male lean Zucker (ZL) rats fed either FO (ZLFO) or CO (ZLCO) diet were used as controls. FO was a marine-derived TAG oil containing EPA 90 mg/g + DHA 430 mg/g. During an oral glucose tolerance test, glucose tolerance remained unaltered by FO while insulin response was reduced in ZOFO only. Liver insulin sensitivity (euglycaemic-hyperinsulinaemic clamp + 2 deoxyglucose) was improved in ZOFO rats, linked to changes in phosphoenolpyruvate carboxykinase expression, activity and glucose-6-phosphatase activity. FI in response to intra-carotid insulin/glucose infusion was decreased similarly in ZOFO and ZOCO. Hypothalamic ceramides levels were lower in ZOFO than in ZOCO. Our study demonstrates that LC n-3 PUFA can minimise weight gain, possibly by alleviating hypothalamic lipotoxicity, and liver IR in genetically obese Zucker rats.
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Affiliation(s)
- Charlotte Corporeau
- Department of Nutritional Sciences, Hospital University, Faculty of Medicine, University of Brest, Plouzané, France
- Present address: Ifremer, University of Brest, CNRS, IRD, LEMAR, F-29280 Plouzané, France
| | - Christelle Le Foll
- Department of Nutritional Sciences, Hospital University, Faculty of Medicine, University of Brest, Plouzané, France
- Present address: Institute of Veterinary Physiology, University of Zurich, CH-8057, Zurich, Switzerland
| | | | - Hervé Le Stunff
- Université Paris Cité, CNRS, Unité de Biologie Fonctionnelle et Adaptative, F-75013 Paris, France
- Present address: Institut des Neurosciences Paris-Saclay-Université Paris-Saclay-CNRS UMR 9197, Gif-sur-Yvette, France
| | - Gilles Mithieux
- Inserm, U855, Lyon, F-69008, France
- University Lyon 1, Villeurbanne, F-69622, France
- University of Lyon, Lyon, F-69008, France
| | - Christophe Magnan
- Université Paris Cité, CNRS, Unité de Biologie Fonctionnelle et Adaptative, F-75013 Paris, France
| | - Jacques Delarue
- Department of Nutritional Sciences, ER7479 SPURBO, Hospital University, Faculty of Medicine University of Brest, Plouzane, France
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6
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Hammerschmidt P, Steculorum SM, Bandet CL, Del Río-Martín A, Steuernagel L, Kohlhaas V, Feldmann M, Varela L, Majcher A, Quatorze Correia M, Klar RFU, Bauder CA, Kaya E, Porniece M, Biglari N, Sieben A, Horvath TL, Hornemann T, Brodesser S, Brüning JC. CerS6-dependent ceramide synthesis in hypothalamic neurons promotes ER/mitochondrial stress and impairs glucose homeostasis in obese mice. Nat Commun 2023; 14:7824. [PMID: 38016943 PMCID: PMC10684560 DOI: 10.1038/s41467-023-42595-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/17/2023] [Indexed: 11/30/2023] Open
Abstract
Dysregulation of hypothalamic ceramides has been associated with disrupted neuronal pathways in control of energy and glucose homeostasis. However, the specific ceramide species promoting neuronal lipotoxicity in obesity have remained obscure. Here, we find increased expression of the C16:0 ceramide-producing ceramide synthase (CerS)6 in cultured hypothalamic neurons exposed to palmitate in vitro and in the hypothalamus of obese mice. Conditional deletion of CerS6 in hypothalamic neurons attenuates high-fat diet (HFD)-dependent weight gain and improves glucose metabolism. Specifically, CerS6 deficiency in neurons expressing pro-opiomelanocortin (POMC) or steroidogenic factor 1 (SF-1) alters feeding behavior and alleviates the adverse metabolic effects of HFD feeding on insulin sensitivity and glucose tolerance. POMC-expressing cell-selective deletion of CerS6 prevents the diet-induced alterations of mitochondrial morphology and improves cellular leptin sensitivity. Our experiments reveal functions of CerS6-derived ceramides in hypothalamic lipotoxicity, altered mitochondrial dynamics, and ER/mitochondrial stress in the deregulation of food intake and glucose metabolism in obesity.
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Affiliation(s)
- Philipp Hammerschmidt
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany
- Policlinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Kerpener Strasse 26, 50924, Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Sophie M Steculorum
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
- Max Planck Institute for Metabolism Research, Research Group Neurocircuit Wiring and Function, Cologne, Germany
- National Center for Diabetes Research (DZD), Ingolstädter Landstrasse 1, 85764, Neuherberg, Germany
| | - Cécile L Bandet
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany
- Policlinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Kerpener Strasse 26, 50924, Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Almudena Del Río-Martín
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany
- Policlinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Kerpener Strasse 26, 50924, Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Lukas Steuernagel
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany
- Policlinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Kerpener Strasse 26, 50924, Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Vivien Kohlhaas
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany
- Policlinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Kerpener Strasse 26, 50924, Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Marvin Feldmann
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany
- Policlinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Kerpener Strasse 26, 50924, Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
- Faculty of Mathematics and Natural Sciences, University of Cologne, Cologne, Germany
| | - Luis Varela
- Yale Center for Molecular and Systems Metabolism, Department of Comparative Medicine, Yale University School of Medicine, 310 Cedar St., BML 330, New Haven, CT, 06520, USA
- Laboratory of Glia-Neuron Interactions in the Control of Hunger. Achucarro Basque Center for Neuroscience, Leioa, 48940, Spain
- Ikerbasque-Basque Foundation for Science, Bilbao, 48013, Spain
| | - Adam Majcher
- Center for Integrative Human Physiology, University of Zürich, Zürich, Switzerland
- Institute of Clinical Chemistry, University Hospital, Zürich, Switzerland
| | - Marta Quatorze Correia
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany
| | - Rhena F U Klar
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany
| | - Corinna A Bauder
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany
- Policlinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Kerpener Strasse 26, 50924, Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Ecem Kaya
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany
- Policlinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Kerpener Strasse 26, 50924, Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Marta Porniece
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany
- Policlinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Kerpener Strasse 26, 50924, Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Nasim Biglari
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany
- Policlinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Kerpener Strasse 26, 50924, Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Anna Sieben
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany
- Policlinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Kerpener Strasse 26, 50924, Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Tamas L Horvath
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
- Yale Center for Molecular and Systems Metabolism, Department of Comparative Medicine, Yale University School of Medicine, 310 Cedar St., BML 330, New Haven, CT, 06520, USA
- Laboratory of Glia-Neuron Interactions in the Control of Hunger. Achucarro Basque Center for Neuroscience, Leioa, 48940, Spain
- Ikerbasque-Basque Foundation for Science, Bilbao, 48013, Spain
| | - Thorsten Hornemann
- Center for Integrative Human Physiology, University of Zürich, Zürich, Switzerland
- Institute of Clinical Chemistry, University Hospital, Zürich, Switzerland
| | - Susanne Brodesser
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Jens C Brüning
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany.
- Policlinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Kerpener Strasse 26, 50924, Cologne, Germany.
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany.
- National Center for Diabetes Research (DZD), Ingolstädter Landstrasse 1, 85764, Neuherberg, Germany.
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7
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Lallement J, Raho I, Merlen G, Rainteau D, Croyal M, Schiffano M, Kassis N, Doignon I, Soty M, Lachkar F, Krempf M, Van Hul M, Cani PD, Foufelle F, Amouyal C, Le Stunff H, Magnan C, Tordjmann T, Cruciani-Guglielmacci C. Hepatic deletion of serine palmitoyl transferase 2 impairs ceramide/sphingomyelin balance, bile acids homeostasis and leads to liver damage in mice. Biochim Biophys Acta Mol Cell Biol Lipids 2023; 1868:159333. [PMID: 37224999 DOI: 10.1016/j.bbalip.2023.159333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 02/24/2023] [Accepted: 04/30/2023] [Indexed: 05/26/2023]
Abstract
Ceramides (Cer) have been shown as lipotoxic inducers, which disturb numerous cell-signaling pathways, leading to metabolic disorders such as type 2 diabetes. In this study, we aimed to determine the role of de novo hepatic ceramide synthesis in energy and liver homeostasis in mice. We generated mice lacking serine palmitoyltransferase 2 (Sptlc2), the rate limiting enzyme of ceramide de novo synthesis, in liver under albumin promoter. Liver function, glucose homeostasis, bile acid (BA) metabolism and hepatic sphingolipids content were assessed using metabolic tests and LC-MS. Despite lower expression of hepatic Sptlc2, we observed an increased concentration of hepatic Cer, associated with a 10-fold increase in neutral sphingomyelinase 2 (nSMase2) expression, and a decreased sphingomyelin content in the liver. Sptlc2ΔLiv mice were protected against obesity induced by high fat diet and displayed a defect in lipid absorption. In addition, an important increase in tauro-muricholic acid was associated with a downregulation of the nuclear BA receptor FXR target genes. Sptlc2 deficiency also enhanced glucose tolerance and attenuated hepatic glucose production, while the latter effect was dampened in presence of nSMase2 inhibitor. Finally, Sptlc2 disruption promoted apoptosis, inflammation and progressive development of hepatic fibrosis, worsening with age. Our data suggest a compensatory mechanism to regulate hepatic ceramides content from sphingomyelin hydrolysis, with deleterious impact on liver homeostasis. In addition, our results show the involvement of hepatic sphingolipid modulation in BA metabolism and hepatic glucose production in an insulin-independent manner, which highlight the still under-researched role of ceramides in many metabolic functions.
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Affiliation(s)
- Justine Lallement
- Université Paris Cité, CNRS, Unité de Biologie Fonctionnelle et Adaptative, F-75013 Paris, France
| | - Ilyès Raho
- Université Paris Cité, CNRS, Unité de Biologie Fonctionnelle et Adaptative, F-75013 Paris, France
| | | | - Dominique Rainteau
- Sorbonne Université, Inserm, Centre de Recherche Saint-Antoine, CRSA, AP-HP, Hôpital Saint Antoine, Biochemistry Department, Paris, France
| | - Mikael Croyal
- Université de Nantes, CHU Nantes, CNRS, INSERM, l'institut du thorax, F-44000 Nantes, France; Université de Nantes, CHU Nantes, Inserm, CNRS, SFR Santé, Inserm UMS 016, CNRS UMS 3556, F-44000 Nantes, France; Plateforme de Spectrométrie de Masse du CRNH-O, UMR1280, Nantes, France
| | - Melody Schiffano
- Plateforme de Spectrométrie de Masse du CRNH-O, UMR1280, Nantes, France
| | - Nadim Kassis
- Université Paris Cité, CNRS, Unité de Biologie Fonctionnelle et Adaptative, F-75013 Paris, France
| | | | - Maud Soty
- Université Claude Bernard Lyon 1, Université de Lyon, INSERM UMR-S1213, Lyon, France
| | - Floriane Lachkar
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, 75006 Paris, France
| | | | - Matthias Van Hul
- Metabolism and Nutrition Research Group, Louvain Drug Research Institute, UCLouvain (Université catholique de Louvain), 1200 Brussels, Belgium; Walloon Excellence in Life Sciences and BIOtechnology (WELBIO) department, WEL Research Institute (WELRI), avenue Pasteur, 6, 1300 Wavre, Belgium
| | - Patrice D Cani
- Metabolism and Nutrition Research Group, Louvain Drug Research Institute, UCLouvain (Université catholique de Louvain), 1200 Brussels, Belgium; Walloon Excellence in Life Sciences and BIOtechnology (WELBIO) department, WEL Research Institute (WELRI), avenue Pasteur, 6, 1300 Wavre, Belgium
| | - Fabienne Foufelle
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, 75006 Paris, France
| | - Chloé Amouyal
- Université Paris Cité, CNRS, Unité de Biologie Fonctionnelle et Adaptative, F-75013 Paris, France
| | - Hervé Le Stunff
- Institut des Neurosciences Paris-Saclay, CNRS UMR 9197, Université Paris Saclay, France
| | - Christophe Magnan
- Université Paris Cité, CNRS, Unité de Biologie Fonctionnelle et Adaptative, F-75013 Paris, France
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8
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Wang G, Hong X, Yu J, Zhang Y, Li Y, Li Z, Zhu Z, Yuan S, Zhang X, Wang S, Zhu F, Wang Y, Wu C, Su P, Shen T. Enhancing de novo ceramide synthesis induced by bisphenol A exposure aggravates metabolic derangement during obesity. Mol Metab 2023; 73:101741. [PMID: 37225016 PMCID: PMC10250932 DOI: 10.1016/j.molmet.2023.101741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 05/16/2023] [Indexed: 05/26/2023] Open
Abstract
OBJECTIVE Exposure to bisphenol A (BPA) has been shown to increase the prevalence of obesity and its related insulin resistance (IR). Ceramide is a sphingolipid known to facilitate the production of proinflammatory cytokines and subsequently exacerbate inflammation and IR during the progression of obesity. Here, we investigated the effects of BPA exposure on ceramide de novo synthesis and whether increased ceramides aggravate adipose tissue (AT) inflammation and obesity-related IR. METHODS A population-based case-control study was conducted to explore the relationship between BPA exposure and IR and the potential role of ceramide in AT in obesity. Next, we used mice reared on a normal chow diet (NCD) or a high-fat diet (HFD) to verify the results from the population study and then investigated the role of ceramides in low-level BPA exposure with HFD-induced IR and AT inflammation in mice treated with or without myriocin (an inhibitor of the rate-limiting enzyme in de novo ceramide synthesis). RESULTS BPA levels are higher in obese individuals and are significantly associated with AT inflammation and IR. Specific subtypes of ceramides mediated the associations between BPA and obesity, obesity-related IR and AT inflammation in the obesity group. In animal experiments, BPA exposure facilitated ceramide accumulation in AT, activated PKCζ, promoted AT inflammation, increased the expression and secretion of proinflammatory cytokines via the JNK/NF-κB pathway, and lowered insulin sensitivity by disrupting IRS1-PI3K-AKT signaling in mice fed a HFD. Myriocin suppressed BPA-induced AT inflammation and IR. CONCLUSION These findings indicate that BPA aggravates obesity-induced IR, which is partly via increased de novo synthesis of ceramides and subsequent promotion of AT inflammation. Ceramide synthesis could be a potential target for the prevention of environmental BPA exposure-related metabolic diseases.
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Affiliation(s)
- Gengfu Wang
- School of Public Health, Anhui Medical University, Hefei 230032, Anhui, PR China
| | - Xu Hong
- School of Public Health, Anhui Medical University, Hefei 230032, Anhui, PR China
| | - Jia Yu
- School of Public Health, Anhui Medical University, Hefei 230032, Anhui, PR China
| | - Yuheng Zhang
- School of Public Health, Anhui Medical University, Hefei 230032, Anhui, PR China
| | - Yuting Li
- School of Public Health, Anhui Medical University, Hefei 230032, Anhui, PR China
| | - Zuo Li
- School of Public Health, Anhui Medical University, Hefei 230032, Anhui, PR China
| | - Zhiyuan Zhu
- School of Public Health, Anhui Medical University, Hefei 230032, Anhui, PR China
| | - Shaoyun Yuan
- School of Public Health, Anhui Medical University, Hefei 230032, Anhui, PR China
| | - Xiaofei Zhang
- School of Public Health, Anhui Medical University, Hefei 230032, Anhui, PR China
| | - Sheng Wang
- Center for Scientific Research of Anhui Medical University, Hefei 230032, Anhui, PR China
| | - Fuhai Zhu
- Second Affiliated Hospital, Anhui Medical University, Hefei 230032, Anhui, PR China
| | - Yong Wang
- Second Affiliated Hospital, Anhui Medical University, Hefei 230032, Anhui, PR China
| | - Changhao Wu
- Department of Biochemistry and Physiology, Faculty of Heath & Medical Sciences, University of Surrey, Surrey, Guildford, UK.
| | - Puyu Su
- School of Public Health, Anhui Medical University, Hefei 230032, Anhui, PR China.
| | - Tong Shen
- School of Public Health, Anhui Medical University, Hefei 230032, Anhui, PR China.
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9
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Jiang H, Huang T, Yu Y, Zhou C, Qiu L, Mai HN, Gropler RJ, Klein RS, Tu Z. Characterization of a S1PR2 specific 11C-labeled radiotracer in streptozotocin-induced diabetic murine model. Nucl Med Biol 2023; 122-123:108370. [PMID: 37556928 PMCID: PMC10949307 DOI: 10.1016/j.nucmedbio.2023.108370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 07/21/2023] [Accepted: 07/24/2023] [Indexed: 08/11/2023]
Abstract
BACKGROUND Diabetes mellitus is a chronic progressive metabolic disorder that affects millions of people worldwide. Emerging evidence suggests the important roles of sphingolipid metabolism in diabetes. In particular, sphingosine-1-phosphate (S1P) and S1P receptor 2 (S1PR2) have important metabolic functions and are involved in several metabolic diseases. In diabetes, S1PR2 can effectively preserve β cells and improve glucose/insulin tolerance in high-fat diet induced and streptozotocin (STZ)-induced diabetic mouse models. We previously developed a group of potent and selective S1PR2 ligands and radioligands. METHODS In this study, we continued our efforts and characterized our leading S1PR2 radioligand, [11C]TZ34125, in a STZ-induced diabetic mouse model. [11C]TZ34125 was radiosynthesized in an automated synthesis module and in vitro saturation binding assay was performed using recombinant human S1PR2 membrane. In vitro saturation autoradiography analysis was also performed to determine the binding affinity of [11C]TZ34125 against mouse tissues. Type-1 diabetic mouse model was developed following a single high dose of STZ in C57BL/6 mice. Ex vivo biodistribution was performed to evaluate the distribution and amount of [11C]TZ34125 in tissues. In vitro autoradiography analysis was performed to compare the uptake of [11C]TZ34125 between diabetic and control animals in mouse spleen and pancreas. RESULTS Our in vitro saturation binding assay using [11C]TZ34125 confirmed [11C]TZ34125 is a potent radioligand to recombinant human S1PR2 membrane with a Kd value of 0.9 nM. Saturation autoradiographic analysis showed [11C]TZ34125 has a Kd of 67.5, 45.9, and 25.0 nM to mouse kidney, spleen, and liver tissues respectively. Biodistribution study in STZ-induced diabetic mice showed the uptake of [11C]TZ34125 was significantly elevated in the spleen (~2 fold higher) and pancreas (~1.4 fold higher) compared to normal controls. The increased uptake of [11C]TZ34125 was further confirmed using autoradiographic analysis in the spleen and pancreases of STZ-induced diabetic mice, indicating S1PR2 can potentially act as a biomarker of diabetes in pancreases and inflammation in spleen. Future mechanistic analysis and in vivo quantitative assessment using non-invasive PET imaging in large animal model of diabetes is worthwhile. CONCLUSIONS Overall, our data showed an increased uptake of our lead S1PR2-specific radioligand, [11C]TZ34125, in the spleen and pancreases of STZ-induced diabetic mice, and demonstrated [11C]TZ34125 has a great potential for preclinical and clinical usage for assessment of S1PR2 in diabetes and inflammation.
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Affiliation(s)
- Hao Jiang
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO, 63110, United States of America
| | - Tianyu Huang
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO, 63110, United States of America
| | - Yanbo Yu
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO, 63110, United States of America
| | - Charles Zhou
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO, 63110, United States of America
| | - Lin Qiu
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO, 63110, United States of America
| | - Hien Ngoc Mai
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO, 63110, United States of America
| | - Robert J Gropler
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO, 63110, United States of America
| | - Robyn S Klein
- Departments of Medicine and Pathology and Immunology, Washington University School of Medicine, Saint Louis, MO, 63110, United States of America
| | - Zhude Tu
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO, 63110, United States of America.
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10
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Ramanadham S, Turk J, Bhatnagar S. Noncanonical Regulation of cAMP-Dependent Insulin Secretion and Its Implications in Type 2 Diabetes. Compr Physiol 2023; 13:5023-5049. [PMID: 37358504 PMCID: PMC10809800 DOI: 10.1002/cphy.c220031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2023]
Abstract
Impaired glucose tolerance (IGT) and β-cell dysfunction in insulin resistance associated with obesity lead to type 2 diabetes (T2D). Glucose-stimulated insulin secretion (GSIS) from β-cells occurs via a canonical pathway that involves glucose metabolism, ATP generation, inactivation of K ATP channels, plasma membrane depolarization, and increases in cytosolic concentrations of [Ca 2+ ] c . However, optimal insulin secretion requires amplification of GSIS by increases in cyclic adenosine monophosphate (cAMP) signaling. The cAMP effectors protein kinase A (PKA) and exchange factor activated by cyclic-AMP (Epac) regulate membrane depolarization, gene expression, and trafficking and fusion of insulin granules to the plasma membrane for amplifying GSIS. The widely recognized lipid signaling generated within β-cells by the β-isoform of Ca 2+ -independent phospholipase A 2 enzyme (iPLA 2 β) participates in cAMP-stimulated insulin secretion (cSIS). Recent work has identified the role of a G-protein coupled receptor (GPCR) activated signaling by the complement 1q like-3 (C1ql3) secreted protein in inhibiting cSIS. In the IGT state, cSIS is attenuated, and the β-cell function is reduced. Interestingly, while β-cell-specific deletion of iPLA 2 β reduces cAMP-mediated amplification of GSIS, the loss of iPLA 2 β in macrophages (MØ) confers protection against the development of glucose intolerance associated with diet-induced obesity (DIO). In this article, we discuss canonical (glucose and cAMP) and novel noncanonical (iPLA 2 β and C1ql3) pathways and how they may affect β-cell (dys)function in the context of impaired glucose intolerance associated with obesity and T2D. In conclusion, we provide a perspective that in IGT states, targeting noncanonical pathways along with canonical pathways could be a more comprehensive approach for restoring β-cell function in T2D. © 2023 American Physiological Society. Compr Physiol 13:5023-5049, 2023.
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Affiliation(s)
- Sasanka Ramanadham
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Alabama, USA
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Alabama, USA
| | - John Turk
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Sushant Bhatnagar
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Alabama, USA
- Department of Medicine, University of Alabama at Birmingham, Alabama, USA
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11
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Bandet CL, Tan-Chen S, Ali-Berrada S, Campana M, Poirier M, Blachnio-Zabielska A, Pais-de-Barros JP, Rouch C, Ferré P, Foufelle F, Le Stunff H, Hajduch E. Ceramide analogue C2-cer induces a loss in insulin sensitivity in muscle cells through the salvage/recycling pathway. J Biol Chem 2023:104815. [PMID: 37178918 DOI: 10.1016/j.jbc.2023.104815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 05/01/2023] [Accepted: 05/02/2023] [Indexed: 05/15/2023] Open
Abstract
Ceramides have been shown to play a major role in the onset of skeletal muscle insulin resistance and therefore in the prevalence of type 2 diabetes (T2D). However, many of the studies involved in the discovery of deleterious ceramide actions used a non-physiological cell-permeable short-chain ceramide analogue, the C2-ceramide (C2-cer). In the present study, we determined how C2-cer promotes insulin resistance in muscle cells. We demonstrate that C2-cer enters the salvage/recycling pathway and becomes de-acylated, yielding sphingosine, re-acylation of which depends on the availability of long chain fatty acids provided by the lipogenesis pathway in muscle cells. Importantly, we show these salvaged ceramides are actually responsible for the inhibition of insulin signaling induced by C2-cer. Interestingly, we also show that the exogenous and endogenous mono-unsaturated fatty acid oleate prevents C2-cer to be recycled into endogenous ceramide species in a diacylglycerol O-acyltransferase 1 (DGAT1)-dependent mechanism, which forces free fatty acid metabolism towards triacylglyceride production. Altogether, the study highlights for the first time that C2-cer induces a loss in insulin sensitivity through the salvage/recycling pathway in muscle cells. This study also validates C2-cer as a convenient tool to decipher mechanisms by which long-chain ceramides mediate insulin resistance in muscle cells and suggests that in addition to the de novo ceramide synthesis, recycling of ceramide could contribute to muscle insulin resistance observed in obesity and T2D.
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Affiliation(s)
- Cécile L Bandet
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, F-75006 Paris, France; Institut Hospitalo-Universitaire ICAN, Paris, France
| | - Sophie Tan-Chen
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, F-75006 Paris, France; Institut Hospitalo-Universitaire ICAN, Paris, France
| | - Sarah Ali-Berrada
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, F-75006 Paris, France; Institut Hospitalo-Universitaire ICAN, Paris, France
| | - Mélanie Campana
- Université Paris-Saclay, CNRS UMR 9197, Institut des Neurosciences Paris-Saclay, CNRS UMR 9197, Saclay, France
| | - Maxime Poirier
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, F-75006 Paris, France; Institut Hospitalo-Universitaire ICAN, Paris, France
| | | | - Jean-Paul Pais-de-Barros
- Lipidomics Core Facility, INSERM UMR1231 - Université Bourgogne Franche Comté, 15 Boulevard Mal de Lattre de Tassigny, F-21000 Dijon, France
| | - Claude Rouch
- Université de Paris Cité, Functional and Adaptive Biology Unit, UMR 8251, CNRS, Paris, France
| | - Pascal Ferré
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, F-75006 Paris, France; Institut Hospitalo-Universitaire ICAN, Paris, France
| | - Fabienne Foufelle
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, F-75006 Paris, France; Institut Hospitalo-Universitaire ICAN, Paris, France
| | - Hervé Le Stunff
- Université Paris-Saclay, CNRS UMR 9197, Institut des Neurosciences Paris-Saclay, CNRS UMR 9197, Saclay, France
| | - Eric Hajduch
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, F-75006 Paris, France; Institut Hospitalo-Universitaire ICAN, Paris, France.
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12
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Wang Y, Sun Z, Zang G, Zhang L, Wang Z. Role of ceramides in diabetic foot ulcers (Review). Int J Mol Med 2023; 51:26. [PMID: 36799149 PMCID: PMC9943538 DOI: 10.3892/ijmm.2023.5229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 01/20/2023] [Indexed: 02/09/2023] Open
Abstract
Diabetes mellitus (DM) is a metabolic disorder, which if not managed properly, can lead to serious health problems over time and impose significant financial burden on the patient, their family and society as a whole. The study of this disease and the underlying biological mechanism is gaining momentum. Multiple pieces of conclusive evidence show that ceramides are involved in the occurrence and development of diabetes. The present review focuses on the function of ceramides, a type of sphingolipid signaling molecule, to provide a brief description of ceramides and their metabolism, discuss the significant roles of ceramides in the healthy skin barrier, and speculate on the potential involvement of ceramides in the pathogenesis and development of diabetic foot ulcers (DFUs). Understanding these aspects of this disease more thoroughly is crucial to establish how ceramides contribute to the etiology of diabetic foot infections and identify possible therapeutic targets for the treatment of DFUs.
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Affiliation(s)
| | | | | | | | - Zhongqun Wang
- Correspondence to: Dr Zhongqun Wang, Department of Cardiology, Affiliated Hospital of Jiangsu University, 438 Jiefang Road, Jingkou, Zhenjiang, Jiangsu 212001, P.R. China, E-mail:
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13
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Type 2 Diabetes and Alzheimer's Disease: The Emerging Role of Cellular Lipotoxicity. Biomolecules 2023; 13:biom13010183. [PMID: 36671568 PMCID: PMC9855893 DOI: 10.3390/biom13010183] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 01/06/2023] [Accepted: 01/13/2023] [Indexed: 01/18/2023] Open
Abstract
Type 2 diabetes (T2D) and Alzheimer's diseases (AD) represent major health issues that have reached alarming levels in the last decades. Although growing evidence demonstrates that AD is a significant comorbidity of T2D, and there is a ~1.4-2-fold increase in the risk of developing AD among T2D patients, the involvement of possible common triggers in the pathogenesis of these two diseases remains largely unknown. Of note, recent mechanistic insights suggest that lipotoxicity could represent the missing ring in the pathogenetic mechanisms linking T2D to AD. Indeed, obesity, which represents the main cause of lipotoxicity, has been recognized as a major risk factor for both pathological conditions. Lipotoxicity can lead to inflammation, insulin resistance, oxidative stress, ceramide and amyloid accumulation, endoplasmic reticulum stress, ferroptosis, and autophagy, which are shared biological events in the pathogenesis of T2D and AD. In the current review, we try to provide a critical and comprehensive view of the common molecular pathways activated by lipotoxicity in T2D and AD, attempting to summarize how these mechanisms can drive future research and open the way to new therapeutic perspectives.
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14
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Sánchez-Alegría K, Arias C. Functional consequences of brain exposure to saturated fatty acids: From energy metabolism and insulin resistance to neuronal damage. Endocrinol Diabetes Metab 2023; 6:e386. [PMID: 36321333 PMCID: PMC9836261 DOI: 10.1002/edm2.386] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 10/06/2022] [Accepted: 10/09/2022] [Indexed: 11/06/2022] Open
Abstract
INTRODUCTION Saturated fatty acids (FAs) are the main component of high-fat diets (HFDs), and high consumption has been associated with the development of insulin resistance, endoplasmic reticulum stress and mitochondrial dysfunction in neuronal cells. In particular, the reduction in neuronal insulin signaling seems to underlie the development of cognitive impairments and has been considered a risk factor for Alzheimer's disease (AD). METHODS This review summarized and critically analyzed the research that has impacted the field of saturated FA metabolism in neurons. RESULTS We reviewed the mechanisms for free FA transport from the systemic circulation to the brain and how they impact neuronal metabolism. Finally, we focused on the molecular and the physiopathological consequences of brain exposure to the most abundant FA in the HFD, palmitic acid (PA). CONCLUSION Understanding the mechanisms that lead to metabolic alterations in neurons induced by saturated FAs could help to develop several strategies for the prevention and treatment of cognitive impairment associated with insulin resistance, metabolic syndrome, or type II diabetes.
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Affiliation(s)
- Karina Sánchez-Alegría
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - Clorinda Arias
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
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15
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Targeting Ceramides and Adiponectin Receptors in the Islet of Langerhans for Treating Diabetes. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27186117. [PMID: 36144859 PMCID: PMC9502927 DOI: 10.3390/molecules27186117] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/14/2022] [Accepted: 09/15/2022] [Indexed: 11/17/2022]
Abstract
Ceramides belong to the sphingolipid family and represent the central hub of the sphingolipid network. In obesity, oversupply of saturated fatty acids including palmitate raises ceramide levels which can be detrimental to cells. Elevated ceramides can cause insulin resistance, endoplasmic reticulum stress, and mitochondrial dysfunction. Studies over the last few decades have highlighted the role played by ceramides in pancreatic islet β-cell apoptosis, especially under glucolipotoxic and inflammatory conditions. This review focuses on ceramides and adiponectin receptor signaling, summarizing recent advancements in our understanding of their roles in islet β-cells and the discovery of zinc-dependent lipid hydrolase (ceramidase) activity of adiponectin receptors. The therapeutic potential of targeting these events to prevent islet β-cell loss for treating diabetes is discussed.
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16
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Contribution of specific ceramides to obesity-associated metabolic diseases. Cell Mol Life Sci 2022; 79:395. [PMID: 35789435 PMCID: PMC9252958 DOI: 10.1007/s00018-022-04401-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 05/20/2022] [Accepted: 05/26/2022] [Indexed: 12/04/2022]
Abstract
Ceramides are a heterogeneous group of bioactive membrane sphingolipids that play specialized regulatory roles in cellular metabolism depending on their characteristic fatty acyl chain lengths and subcellular distribution. As obesity progresses, certain ceramide molecular species accumulate in metabolic tissues and cause cell-type-specific lipotoxic reactions that disrupt metabolic homeostasis and lead to the development of cardiometabolic diseases. Several mechanisms for ceramide action have been inferred from studies in vitro, but only recently have we begun to better understand the acyl chain length specificity of ceramide-mediated signaling in the context of physiology and disease in vivo. New discoveries show that specific ceramides affect various metabolic pathways and that global or tissue-specific reduction in selected ceramide pools in obese rodents is sufficient to improve metabolic health. Here, we review the tissue-specific regulation and functions of ceramides in obesity, thus highlighting the emerging concept of selectively inhibiting production or action of ceramides with specific acyl chain lengths as novel therapeutic strategies to ameliorate obesity-associated diseases.
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17
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The Role of Mitochondrial Quality Control in Cognitive Dysfunction in Diabetes. Neurochem Res 2022; 47:2158-2172. [PMID: 35661963 PMCID: PMC9352619 DOI: 10.1007/s11064-022-03631-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 05/05/2022] [Accepted: 05/07/2022] [Indexed: 12/26/2022]
Abstract
Type 2 diabetes (T2DM) is a well known risk factor for Alzheimer’s disease. Mitochondria are the center of intracellular energy metabolism and the main source of reactive oxygen species. Mitochondrial dysfunction has been identified as a key factor in diabetes-associated brain alterations contributing to neurodegenerative events. Defective insulin signaling may act in concert with neurodegenerative mechanisms leading to abnormalities in mitochondrial structure and function. Mitochondrial dysfunction triggers neuronal energy exhaustion and oxidative stress, leading to brain neuronal damage and cognitive impairment. The normality of mitochondrial function is basically maintained by mitochondrial quality control mechanisms. In T2DM, defects in the mitochondrial quality control pathway in the brain have been found to lead to mitochondrial dysfunction and cognitive impairment. Here, we discuss the association of mitochondrial dysfunction with T2DM and cognitive impairment. We also review the molecular mechanisms of mitochondrial quality control and impacts of mitochondrial quality control on the progression of cognitive impairment in T2DM.
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18
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Yang J, Wang M, Yang D, Yan H, Wang Z, Yan D, Guo N. Integrated lipids biomarker of the prediabetes and type 2 diabetes mellitus Chinese patients. Front Endocrinol (Lausanne) 2022; 13:1065665. [PMID: 36743922 PMCID: PMC9897314 DOI: 10.3389/fendo.2022.1065665] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 12/30/2022] [Indexed: 01/22/2023] Open
Abstract
INTRODUCTION Dyslipidemia is a hallmark of T2DM, and as such, analyses of lipid metabolic profiles in affected patients have the potential to permit the development of an integrated lipid metabolite-based biomarker model that can facilitate early patient diagnosis and treatment. METHODS Untargeted and targeted lipidomics approaches were used to analyze serum samples from newly diagnosed 93 Chinese participants in discovery cohort and 440 in validation cohort via UHPLC-MS and UHPLC-MS/MS first. The acid sphingomyelinase protein expression was analyzed by Western blot. RESULTS AND DISCUSSION Through these analyses, we developed a novel integrated biomarker signature composed of LPC 22:6, PC(16:0/20:4), PE(22:6/16:0), Cer(d18:1/24:0)/SM(d18:1/19:0), Cer(d18:1/24:0)/SM(d18:0/16:0), TG(18:1/18:2/18:2), TG(16:0/16:0/20:3), and TG(18:0/16:0/18:2). The area under the curve (AUC) values for this integrated biomarker signature for prediabetes and T2DM patients were 0.841 (cutoff: 0.565) and 0.894 (cutoff: 0.633), respectively. Furthermore, theresults of western blot analysis of frozen adipose tissue from 3 week (prediabetes) and 12 week (T2DM) Goto-Kakizaki (GK) rats also confirmed that acid sphingomyelinase is responsible for significant disruptions in ceramide and sphingomyelin homeostasis. Network analyses of the biomarkers associated with this biosignature suggested that the most profoundly affected lipid metabolism pathways in the context of diabetes include de novo ceramide synthesis, sphingomyelin metabolism, and additional pathways associated with phosphatidylcholine synthesis. Together, these results offer new biological insights regarding the role of serum lipids in the context of insidious T2DM development, and may offer new avenues for future diagnostic and/or therapeutic research.
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Affiliation(s)
- Jiaying Yang
- Experimental Research Center, China Academy of Chinese Medical Sciences, Beijing, China
- College of Pharmacy, Heilongjiang University of Traditional Chinese Medicine, Heilongjiang, China
| | - Mei Wang
- Experimental Research Center, China Academy of Chinese Medical Sciences, Beijing, China
| | - Dawei Yang
- Zhong Yuan Academy of Biological Medicine, Liaocheng People’s Hospital, Liaocheng, Shandong, China
| | - Han Yan
- Experimental Research Center, China Academy of Chinese Medical Sciences, Beijing, China
| | - Zhigang Wang
- College of Pharmacy, Heilongjiang University of Traditional Chinese Medicine, Heilongjiang, China
- *Correspondence: Zhigang Wang, ; Dan Yan, ; Na Guo,
| | - Dan Yan
- Beijing Institute of Clinical Pharmacy, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- *Correspondence: Zhigang Wang, ; Dan Yan, ; Na Guo,
| | - Na Guo
- Experimental Research Center, China Academy of Chinese Medical Sciences, Beijing, China
- *Correspondence: Zhigang Wang, ; Dan Yan, ; Na Guo,
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19
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Terzo S, Amato A, Mulè F. From obesity to Alzheimer's disease through insulin resistance. J Diabetes Complications 2021; 35:108026. [PMID: 34454830 DOI: 10.1016/j.jdiacomp.2021.108026] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 07/29/2021] [Accepted: 08/14/2021] [Indexed: 12/27/2022]
Abstract
Alzheimer's disease is one of the most frequent forms of dementia. It is a progressive neurodegenerative disease, characterized by presence of amyloid plaques and neurofibrillary tangles in the brain. Obesity is regarded as abnormal fat accumulation with deleterious impact on human health. There is full scientific evidence that obesity and the metabolic comorbidities (e.g., insulin resistance, hyperglycaemia, and type 2 diabetes) are related to Alzheimer's disease and likely in the causative pathway. Numerous studies have identified several overlapping neurodegenerative mechanisms, including oxidative stress, mitochondrial dysfunction, and inflammation. In this review, we present how obesity and the associated lipotoxicity as well as chronic inflammation initiate a state of insulin resistance that in turn, may have a role in causing the characteristic cerebral alterations of AD. In particular, we focus on the molecular mechanisms linking the obesity-induced impairment in insulin signalling to the upregulation of Aβ aggregation, tau hyper-phosphorylation, inflammation, oxidative stress and mitochondrial dysfunction.
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Affiliation(s)
- Simona Terzo
- Dipartimento di Scienze e Tecnologie Biologiche Chimiche e Farmaceutiche (STEBICEF), Università di Palermo, 90128, Italy.
| | - Antonella Amato
- Dipartimento di Scienze e Tecnologie Biologiche Chimiche e Farmaceutiche (STEBICEF), Università di Palermo, 90128, Italy.
| | - Flavia Mulè
- Dipartimento di Scienze e Tecnologie Biologiche Chimiche e Farmaceutiche (STEBICEF), Università di Palermo, 90128, Italy.
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Meneyrol K, Estévez-Salguero Á, González-García I, Guitton J, Taouis M, Benomar Y, Magnan C, López M, Le Stunff H. Ovarian insufficiency impairs glucose-stimulated insulin secretion through activation of hypothalamic de novo ceramide synthesis. Metabolism 2021; 123:154846. [PMID: 34371064 DOI: 10.1016/j.metabol.2021.154846] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 07/25/2021] [Accepted: 08/02/2021] [Indexed: 12/20/2022]
Abstract
Oestrogens regulate body weight through their action on hypothalamus to modulate food intake and energy expenditure. Hypothalamic de novo ceramide synthesis plays a central role on obesity induced by oestrogen deficiency. Depletion in oestrogens is also known to be associated with glucose intolerance, which favours type 2 diabetes (T2D). However, the implication of hypothalamic ceramide in the regulation of glucose homeostasis by oestrogen is unknown. Here, we studied glucose homeostasis and insulin secretion in ovariectomized (OVX) female rats. OVX induces body weight gain associated with a hypothalamic inflammation and impaired glucose homeostasis. Genetic blockade of ceramide synthesis in the ventromedial nucleus of the hypothalamus (VMH) reverses hypothalamic inflammation and partly restored glucose tolerance induced by OVX. Furthermore, glucose-stimulated insulin secretion (GSIS) is increased in OVX rats due to a raise of insulin secretion second phase, a characteristic of early stage of T2D. In contrast, GSIS from isolated islets of OVX rats is totally blunted. Inhibition of ceramide synthesis in the VMH restores GSIS from isolated OVX islets and represses the second phase of insulin secretion. Stimulation of oestrogen receptor α (ERα) by oestradiol (E2) down-regulates ceramide synthesis in hypothalamic neuronal GT1-7 cells but no in microglial SIM-A9 cells. In contrast, genetic inactivation of ERα in VMH upregulates ceramide synthesis. These results indicate that hypothalamic neuronal de novo ceramide synthesis triggers the OVX-dependent impairment of glucose homeostasis which is partly mediated by a dysregulation of GSIS.
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Affiliation(s)
- Kelly Meneyrol
- Unité de Biologie Fonctionnelle et Adaptative, CNRS UMR 8251, Université de Paris, Paris, France
| | - Ánxela Estévez-Salguero
- NeurObesity Group, Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706, Spain
| | - Ismael González-García
- NeurObesity Group, Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706, Spain
| | - Jeanne Guitton
- Institut des Neurosciences Paris-Saclay, CNRS UMR 9197, Université Paris Saclay, Orsay, France
| | - Mohammed Taouis
- Institut des Neurosciences Paris-Saclay, CNRS UMR 9197, Université Paris Saclay, Orsay, France
| | - Yacir Benomar
- Institut des Neurosciences Paris-Saclay, CNRS UMR 9197, Université Paris Saclay, Orsay, France
| | - Christophe Magnan
- Unité de Biologie Fonctionnelle et Adaptative, CNRS UMR 8251, Université de Paris, Paris, France
| | - Miguel López
- NeurObesity Group, Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706, Spain.
| | - Hervé Le Stunff
- Unité de Biologie Fonctionnelle et Adaptative, CNRS UMR 8251, Université de Paris, Paris, France; Institut des Neurosciences Paris-Saclay, CNRS UMR 9197, Université Paris Saclay, Orsay, France.
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21
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Magnan C, Le Stunff H. Role of hypothalamic de novo ceramides synthesis in obesity and associated metabolic disorders. Mol Metab 2021; 53:101298. [PMID: 34273578 PMCID: PMC8353504 DOI: 10.1016/j.molmet.2021.101298] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 06/28/2021] [Accepted: 07/09/2021] [Indexed: 12/31/2022] Open
Abstract
Background Sphingolipid-mediated signalling pathways are described as important players in the normal functioning of neurons and nonneuronal cells in the central nervous system (CNS). Scope of review This review aims to show role of de novo ceramide synthesis in the CNS in controling key physiological processes, including food intake, energy expenditure, and thermogenesis. The corollary is a condition that leads to a dysfunction in ceramide metabolism in these central regions that can have major consequences on the physiological regulation of energy balance. Major conclusions Excessive hypothalamic de novo ceramide synthesis has been shown to result in the establishment of central insulin resistance, endoplasmic reticulum stress, and inflammation. Additionally, excessive hypothalamic de novo ceramide synthesis has also been associated with changes in the activity of the autonomic nervous system. Such dysregulation of hypothalamic de novo ceramide synthesis forms the key starting point for the initiation of pathophysiological conditions such as obesity – which may or may not be associated with type 2 diabetes.
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Affiliation(s)
| | - Hervé Le Stunff
- CNRS UMR 9198 Institut des Neurosciences Paris Saclay (Neuro-PSI), Université Paris-Saclay, Saclay, France.
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22
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Reginato A, Veras ACC, Baqueiro MDN, Panzarin C, Siqueira BP, Milanski M, Lisboa PC, Torsoni AS. The Role of Fatty Acids in Ceramide Pathways and Their Influence on Hypothalamic Regulation of Energy Balance: A Systematic Review. Int J Mol Sci 2021; 22:5357. [PMID: 34069652 PMCID: PMC8160791 DOI: 10.3390/ijms22105357] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 04/30/2021] [Accepted: 05/06/2021] [Indexed: 12/09/2022] Open
Abstract
Obesity is a global health issue for which no major effective treatments have been well established. High-fat diet consumption is closely related to the development of obesity because it negatively modulates the hypothalamic control of food intake due to metaflammation and lipotoxicity. The use of animal models, such as rodents, in conjunction with in vitro models of hypothalamic cells, can enhance the understanding of hypothalamic functions related to the control of energy balance, thereby providing knowledge about the impact of diet on the hypothalamus, in addition to targets for the development of new drugs that can be used in humans to decrease body weight. Recently, sphingolipids were described as having a lipotoxic effect in peripheral tissues and the central nervous system. Specifically, lipid overload, mainly from long-chain saturated fatty acids, such as palmitate, leads to excessive ceramide levels that can be sensed by the hypothalamus, triggering the dysregulation of energy balance control. However, no systematic review has been undertaken regarding studies of sphingolipids, particularly ceramide and sphingosine-1-phosphate (S1P), the hypothalamus, and obesity. This review confirms that ceramides are associated with hypothalamic dysfunction in response to metaflammation, endoplasmic reticulum (ER) stress, and lipotoxicity, leading to insulin/leptin resistance. However, in contrast to ceramide, S1P appears to be a central satiety factor in the hypothalamus. Thus, our work describes current evidence related to sphingolipids and their role in hypothalamic energy balance control. Hypothetically, the manipulation of sphingolipid levels could be useful in enabling clinicians to treat obesity, particularly by decreasing ceramide levels and the inflammation/endoplasmic reticulum stress induced in response to overfeeding with saturated fatty acids.
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Affiliation(s)
- Andressa Reginato
- Biology Institute, State University of Rio de Janeiro, UERJ, Rio de Janeiro 20551-030, Brazil;
- Faculty of Applied Science, University of Campinas, UNICAMP, Campinas 13484-350, Brazil; (A.C.C.V.); (M.d.N.B.); (C.P.); (B.P.S.); (M.M.)
- Obesity and Comorbidities Research Center, University of Campinas, UNICAMP, Campinas 13083-864, Brazil
| | - Alana Carolina Costa Veras
- Faculty of Applied Science, University of Campinas, UNICAMP, Campinas 13484-350, Brazil; (A.C.C.V.); (M.d.N.B.); (C.P.); (B.P.S.); (M.M.)
- Obesity and Comorbidities Research Center, University of Campinas, UNICAMP, Campinas 13083-864, Brazil
| | - Mayara da Nóbrega Baqueiro
- Faculty of Applied Science, University of Campinas, UNICAMP, Campinas 13484-350, Brazil; (A.C.C.V.); (M.d.N.B.); (C.P.); (B.P.S.); (M.M.)
- Obesity and Comorbidities Research Center, University of Campinas, UNICAMP, Campinas 13083-864, Brazil
| | - Carolina Panzarin
- Faculty of Applied Science, University of Campinas, UNICAMP, Campinas 13484-350, Brazil; (A.C.C.V.); (M.d.N.B.); (C.P.); (B.P.S.); (M.M.)
- Obesity and Comorbidities Research Center, University of Campinas, UNICAMP, Campinas 13083-864, Brazil
| | - Beatriz Piatezzi Siqueira
- Faculty of Applied Science, University of Campinas, UNICAMP, Campinas 13484-350, Brazil; (A.C.C.V.); (M.d.N.B.); (C.P.); (B.P.S.); (M.M.)
- Obesity and Comorbidities Research Center, University of Campinas, UNICAMP, Campinas 13083-864, Brazil
| | - Marciane Milanski
- Faculty of Applied Science, University of Campinas, UNICAMP, Campinas 13484-350, Brazil; (A.C.C.V.); (M.d.N.B.); (C.P.); (B.P.S.); (M.M.)
- Obesity and Comorbidities Research Center, University of Campinas, UNICAMP, Campinas 13083-864, Brazil
| | | | - Adriana Souza Torsoni
- Faculty of Applied Science, University of Campinas, UNICAMP, Campinas 13484-350, Brazil; (A.C.C.V.); (M.d.N.B.); (C.P.); (B.P.S.); (M.M.)
- Obesity and Comorbidities Research Center, University of Campinas, UNICAMP, Campinas 13083-864, Brazil
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Song JH, Kim GT, Park KH, Park WJ, Park TS. Bioactive Sphingolipids as Major Regulators of Coronary Artery Disease. Biomol Ther (Seoul) 2021; 29:373-383. [PMID: 33903284 PMCID: PMC8255146 DOI: 10.4062/biomolther.2020.218] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/04/2021] [Accepted: 01/06/2021] [Indexed: 12/31/2022] Open
Abstract
Atherosclerosis is the deposition of plaque in the main arteries. It is an inflammatory condition involving the accumulation of macrophages and various lipids (low-density lipoprotein [LDL] cholesterol, ceramide, S1P). Moreover, endothelial cells, macrophages, leukocytes, and smooth muscle cells are the major players in the atherogenic process. Sphingolipids are now emerging as important regulators in various pathophysiological processes, including the atherogenic process. Various sphingolipids exist, such as the ceramides, ceramide-1-phosphate, sphingosine, sphinganine, sphingosine-1-phosphate (S1P), sphingomyelin, and hundreds of glycosphingolipids. Among these, ceramides, glycosphingolipids, and S1P play important roles in the atherogenic processes. The atherosclerotic plaque consists of higher amounts of ceramide, glycosphingolipids, and sphingomyelin. The inhibition of the de novo ceramide biosynthesis reduces the development of atherosclerosis. S1P regulates atherogenesis via binding to the S1P receptor (S1PR). Among the five S1PRs (S1PR1-5), S1PR1 and S1PR3 mainly exert anti-atherosclerotic properties. This review mainly focuses on the effects of ceramide and S1P via the S1PR in the development of atherosclerosis. Moreover, it discusses the recent findings and potential therapeutic implications in atherosclerosis.
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Affiliation(s)
- Jae-Hwi Song
- Department of Life Science, Gachon University, Sungnam 13120, Republic of Korea
| | - Goon-Tae Kim
- Department of Life Science, Gachon University, Sungnam 13120, Republic of Korea
| | - Kyung-Ho Park
- Department of Nutrition, Hallym University, Chuncheon 24252, Republic of Korea
| | - Woo-Jae Park
- Department of Biochemistry, College of Medicine, Gachon University, Incheon 21999, Republic of Korea
| | - Tae-Sik Park
- Department of Life Science, Gachon University, Sungnam 13120, Republic of Korea
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24
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Rodríguez M, Pintado C, Torrillas-de la Cal R, Moltó E, Gallardo N, Andrés A, Arribas C. Ageing alters the lipid sensing process in the hypothalamus of Wistar rats. Effect of food restriction. Nutr Neurosci 2021; 25:1509-1523. [PMID: 33544062 DOI: 10.1080/1028415x.2021.1872990] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
INTRODUCTION Lipids regulate a wide range of biological processes. The mechanisms by which fatty acids (FA) and its metabolites influence the hypothalamic regulation of energy homeostasis have been highly studied. However, the effect of ageing and food restriction (FR) on this process is unknown. METHODS Herein, we analyzed the gene expression, protein and phosphorylation levels of hypothalamic enzymes and transcription factors related to lipid metabolism. Experiments were performed in male Wistar rats of 3-, 8- and 24-month-old Wistar rats fed ad libitum (AL), as ageing model. Besides, 5- and 21-month-old rats were subjected to a moderate FR protocol (equivalent to ≈ 80% of normal food intake) for three months before the sacrifice. RESULTS Aged Wistar rats showed a situation of chronic lipid excess as a result of an increase in de novo FA synthesis and FA levels that reach the brain, contributing likely to the development of central leptin and insulin resistance. We observe a hypothalamic downregulation of AMP-activated protein kinase (AMPK) and stearoyl-CoA desaturase (SCD1) and an increase of carnitine palmitoyltransferase-1c (CPT1c) expression. DISCUSSION Our results suggest an impairment in the physiological lipid sensing system of aged Wistar rats, which would alter the balance of the intracellular mobilization and trafficking of lipids between the mitochondria and the Endoplasmic Reticulum (ER) in the hypothalamus, leading probably to the development of neurolipotoxicity in aged rats. Lastly, FR can only partially restore this imbalance.Schematic representation of the fate of LCFA-CoA in the hypothalamus of young and old rats. Blood circulating LCFAs in young Wistar rats reach the hypothalamus, where they are esterified to LCFA-CoA. Into glial cells or neurons, LCFA-CoA are driven to mitochondria (CPT1a) or ER (CPT1c) where could be desaturated by SDC1 and, thereby, converted into structural and signaling unsaturated lipids as oleic acid, related with neuronal myelinization and differentiation. However, the excess of LCFA that reach to the hypothalamus in old animals, could generate an increase in LCFA-CoA, which together with an increase in CPT1c levels, could favor the capture of LCFA-CoA to the ER. The decrease in the levels of SCD1 in old rats would decrease FA unsaturation degree that could trigger lipotoxicity process and neurodegeneration, both related to the development of neurodegenerative diseases linked to age.
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Affiliation(s)
- María Rodríguez
- Biochemistry Section, Faculty of Biochemistry and Environmental Sciences and Regional Centre for Biomedical Research, Universidad de Castilla-La Mancha, Toledo, Spain
| | - Cristina Pintado
- Biochemistry Section, Faculty of Biochemistry and Environmental Sciences and Regional Centre for Biomedical Research, Universidad de Castilla-La Mancha, Toledo, Spain
| | - Rodrigo Torrillas-de la Cal
- Biochemistry Section, Faculty of Biochemistry and Environmental Sciences and Regional Centre for Biomedical Research, Universidad de Castilla-La Mancha, Toledo, Spain
| | - Eduardo Moltó
- Biochemistry Section, Faculty of Biochemistry and Environmental Sciences and Regional Centre for Biomedical Research, Universidad de Castilla-La Mancha, Toledo, Spain
| | - Nilda Gallardo
- Biochemistry Section, Faculty of Science and Chemical Technologies and Regional Centre for Biomedical Research, Universidad de Castilla-La Mancha, Ciudad Real, Spain
| | - Antonio Andrés
- Biochemistry Section, Faculty of Science and Chemical Technologies and Regional Centre for Biomedical Research, Universidad de Castilla-La Mancha, Ciudad Real, Spain
| | - Carmen Arribas
- Biochemistry Section, Faculty of Biochemistry and Environmental Sciences and Regional Centre for Biomedical Research, Universidad de Castilla-La Mancha, Toledo, Spain
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25
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Abstract
Obesity, which has long since reached epidemic proportions worldwide, is associated with long-term stress to a variety of organs and results in diseases including type 2 diabetes. In the brain, overnutrition induces hypothalamic stress associated with the activation of several signalling pathways, together with central insulin and leptin resistance. This central action of nutrient overload appears very rapidly, suggesting that nutrition-induced hypothalamic stress is a major upstream initiator of obesity and associated diseases. The cellular response to nutrient overload includes the activation of the stress-activated c-Jun N-terminal kinases (JNKs) JNK1, JNK2 and JNK3, which are widely expressed in the brain. Here, we review recent findings on the regulation and effects of these kinases, with particular focus on the hypothalamus, a key brain region in the control of energy and glucose homeostasis. JNK1 blocks the hypothalamic-pituitary-thyroid axis, reducing energy expenditure and promoting obesity. Recently, opposing roles have been identified for JNK1 and JNK3 in hypothalamic agouti gene-related protein (AgRP) neurons: while JNK1 activation in AgRP neurons induces feeding and weight gain and impairs insulin and leptin signalling, JNK3 (also known as MAPK10) deletion in the same neuronal population produces very similar effects. The opposing roles of these kinases, and the unknown role of hypothalamic JNK2, reflect the complexity of JNK biology. Future studies should address the specific function of each kinase, not only in different neuronal subsets, but also in non-neuronal cells in the central nervous system. Decoding the puzzle of brain stress kinases will help to define the central stimuli and mechanisms implicated in the control of energy balance. Graphical abstract.
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Affiliation(s)
- Rubén Nogueiras
- Department of Physiology, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, Spain
- Galician Agency of Innovation (GAIN), Xunta de Galicia, Santiago de Compostela, Spain
| | - Guadalupe Sabio
- Department of Myocardial Pathophysiology, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain.
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Central Ceramide Signaling Mediates Obesity-Induced Precocious Puberty. Cell Metab 2020; 32:951-966.e8. [PMID: 33080217 DOI: 10.1016/j.cmet.2020.10.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 07/30/2020] [Accepted: 09/30/2020] [Indexed: 12/17/2022]
Abstract
Childhood obesity, especially in girls, is frequently bound to earlier puberty, which is linked to higher disease burden later in life. The mechanisms underlying this association remain elusive. Here we show that brain ceramides participate in the control of female puberty and contribute to its alteration in early-onset obesity in rats. Postnatal overweight caused earlier puberty and increased hypothalamic ceramide content, while pharmacological activation of ceramide synthesis mimicked the pubertal advancement caused by obesity, specifically in females. Conversely, central blockade of de novo ceramide synthesis delayed puberty and prevented the effects of the puberty-activating signal, kisspeptin. This phenomenon seemingly involves a circuit encompassing the paraventricular nucleus (PVN) and ovarian sympathetic innervation. Early-onset obesity enhanced PVN expression of SPTLC1, a key enzyme for ceramide synthesis, and advanced the maturation of the ovarian noradrenergic system. In turn, obesity-induced pubertal precocity was reversed by virogenetic suppression of SPTLC1 in the PVN. Our data unveil a pathway, linking kisspeptin, PVN ceramides, and sympathetic ovarian innervation, as key for obesity-induced pubertal precocity.
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Wang L, Tran A, Lee J, Belsham DD. Palmitate differentially regulates Spexin, and its receptors Galr2 and Galr3, in GnRH neurons through mechanisms involving PKC, MAPKs, and TLR4. Mol Cell Endocrinol 2020; 518:110991. [PMID: 32841709 DOI: 10.1016/j.mce.2020.110991] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 07/03/2020] [Accepted: 08/12/2020] [Indexed: 02/06/2023]
Abstract
The function of the gonadotropin-releasing hormone (GnRH) neuron is critical to maintain reproductive function and a significant decrease in GnRH can lead to disorders affecting fertility, including hypogonadotropic hypogonadism. Spexin (SPX) is a novel hypothalamic neuropeptide that exerts inhibitory effects on reproduction and feeding by acting through galanin receptor 2 (GALR2) and galanin receptor 3 (GALR3). Fatty acids can act as nutritional signals that regulate the hypothalamic-pituitary-gonadal (HPG) axis, and elevated levels of circulating saturated fatty acids associated with high fat diet (HFD)-feeding have been shown to induce neuroinflammation, endoplasmic reticulum stress and hormonal resistance in the hypothalamus, as well as alter neuropeptide expression. We previously demonstrated that palmitate, the most common saturated fatty acid in a HFD, elevates the expression of Spx, Galr2 and Galr3 mRNA in a model of appetite-regulating neuropeptide Y hypothalamic neurons. Here, we found that Spx, Galr2 and Galr3 mRNA were also significantly induced by palmitate in a model of reproductive GnRH neurons, mHypoA-GnRH/GFP. As a follow-up to our previous report, we examined the molecular pathways by which Spx and galanin receptor mRNA was regulated in this cell line. Furthermore, we performed inhibitor studies, which revealed that the effect of palmitate on Spx and Galr3 mRNA involved activation of the innate immune receptor TLR4, and we detected differential regulation of the three genes by the protein kinases PKC, JNK, ERK, and p38. However, the intracellular metabolism of palmitate to ceramide did not appear to be involved in the palmitate-mediated gene regulation. Overall, this suggests that SPX may play a role in reproduction at the level of the hypothalamus and the pathways by which Spx, Galr2 and Galr3 are altered by fatty acids could provide insight into the mechanisms underlying reproductive dysfunction in obesity.
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Affiliation(s)
- Lu Wang
- Departments of Physiology, Faculty of Medicine, University of Toronto, Ontario, Canada
| | - Andy Tran
- Departments of Physiology, Faculty of Medicine, University of Toronto, Ontario, Canada
| | - Juliette Lee
- Departments of Physiology, Faculty of Medicine, University of Toronto, Ontario, Canada
| | - Denise D Belsham
- Departments of Physiology, Faculty of Medicine, University of Toronto, Ontario, Canada; Medicine, Faculty of Medicine, University of Toronto, Ontario, Canada; Obstetrics and Gynecology, Faculty of Medicine, University of Toronto, Ontario, Canada.
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28
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Abstract
The global prevalence of metabolic diseases such as type 2 diabetes mellitus, steatohepatitis, myocardial infarction, and stroke has increased dramatically over the past two decades. These obesity-fueled disorders result, in part, from the aberrant accumulation of harmful lipid metabolites in tissues not suited for lipid storage (e.g., the liver, vasculature, heart, and pancreatic beta-cells). Among the numerous lipid subtypes that accumulate, sphingolipids such as ceramides are particularly impactful, as they elicit the selective insulin resistance, dyslipidemia, and ultimately cell death that underlie nearly all metabolic disorders. This review summarizes recent findings on the regulatory pathways controlling ceramide production, the molecular mechanisms linking the lipids to these discrete pathogenic events, and exciting attempts to develop therapeutics to reduce ceramide levels to combat metabolic disease.
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Affiliation(s)
- Bhagirath Chaurasia
- Department of Internal Medicine, Division of Endocrinology, Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA;
| | - Scott A Summers
- Department of Nutrition and Integrative Physiology and the Diabetes and Metabolism Research Center, University of Utah, Salt Lake City, Utah 84112, USA;
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29
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Reginato A, Siqueira BP, Miyamoto JÉ, Portovedo M, Costa SDO, de Fante T, Rodrigues HG, Ignácio-Souza LM, Torsoni MA, Torsoni AS, Le Stunff H, Belsham DD, Milanski M. Acute effects of fatty acids on autophagy in NPY neurones. J Neuroendocrinol 2020; 32:e12900. [PMID: 33040385 DOI: 10.1111/jne.12900] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 08/15/2020] [Accepted: 08/19/2020] [Indexed: 12/13/2022]
Abstract
High-fat diet (HFD) feeding is deleterious to hypothalamic tissue, leading to inflammation and lipotoxicity, as well as contributing to central insulin resistance. Autophagy is a process that restores cellular homeostasis by degrading malfunctioning organelles and proteins. Chronic HFD-feeding down-regulates hypothalamic autophagy. However, the effects of short-term HFD-feeding and the saturated fatty acid palmitate (PA) on hypothalamic autophagy and in neurones that express neuropeptide Y (NPY) and agouti-related peptide remains unknown. Therefore, we assessed hypothalamic autophagy after 1 and 3 days of HFD-feeding. We also injected PA i.c.v and analysed the modulation of autophagy in hypothalamic tissue. Both interventions resulted in changes in autophagy-related gene profiles without significant differences in protein content of p62 and LC3B-II, markers of the autophagy pathway. When we assessed native NPY neurones in brain slices from PA-treated animals, we observed increased levels of Atg7 and LC3B protein in response to PA treatment, indicating the induction of autophagy. We then tested the direct effects of fatty acids using the immortalised hypothalamic NPY-expressing neuronal cell model mHypoE-46. We found that PA, but not palmitoleate (PO) (a monounsaturated fatty acid), was able to induce autophagy. Co-treatment with PA and PO was able to block the PA-mediated induction of autophagy, as assessed by flow cytometry. When the de novo ceramide synthesis pathway was blocked with myriocin pre-treatment, we observed a decrease in PA-mediated induction of autophagy, although there was no change with the toll-like receptor 4 inhibitor, TAK-242. Taken together, these findings provide evidence that saturated and unsaturated fatty acids can differentially regulate hypothalamic autophagy and that ceramide synthesis may be an important mediator of those effects. Understanding the mechanisms by which dietary fats affect autophagy in neurones involved in the control of energy homeostasis will provide potential new pathways for targeting and containing the obesity epidemic.
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Affiliation(s)
- Andressa Reginato
- Faculty of Applied Science, University of Campinas, Campinas, Brazil
- Obesity and Comorbidities Research Center, University of Campinas, UNICAMP, Campinas, Brazil
| | - Beatriz Piatezzi Siqueira
- Faculty of Applied Science, University of Campinas, Campinas, Brazil
- Obesity and Comorbidities Research Center, University of Campinas, UNICAMP, Campinas, Brazil
| | - Josiane Érica Miyamoto
- Faculty of Applied Science, University of Campinas, Campinas, Brazil
- Obesity and Comorbidities Research Center, University of Campinas, UNICAMP, Campinas, Brazil
| | - Mariana Portovedo
- Faculty of Applied Science, University of Campinas, Campinas, Brazil
- Obesity and Comorbidities Research Center, University of Campinas, UNICAMP, Campinas, Brazil
| | - Suleyma de Oliveira Costa
- Faculty of Applied Science, University of Campinas, Campinas, Brazil
- Obesity and Comorbidities Research Center, University of Campinas, UNICAMP, Campinas, Brazil
| | - Thaís de Fante
- Faculty of Applied Science, University of Campinas, Campinas, Brazil
- Obesity and Comorbidities Research Center, University of Campinas, UNICAMP, Campinas, Brazil
| | | | - Letícia Martins Ignácio-Souza
- Faculty of Applied Science, University of Campinas, Campinas, Brazil
- Obesity and Comorbidities Research Center, University of Campinas, UNICAMP, Campinas, Brazil
| | - Márcio Alberto Torsoni
- Faculty of Applied Science, University of Campinas, Campinas, Brazil
- Obesity and Comorbidities Research Center, University of Campinas, UNICAMP, Campinas, Brazil
| | - Adriana Souza Torsoni
- Faculty of Applied Science, University of Campinas, Campinas, Brazil
- Obesity and Comorbidities Research Center, University of Campinas, UNICAMP, Campinas, Brazil
| | - Hervé Le Stunff
- Neuroscience Institute, Université Paris Saclay, Paris, France
| | - Denise D Belsham
- Departments of Physiology, Ob/Gyn, and Medicine, University of Toronto, Toronto, ON, Canada
| | - Marciane Milanski
- Faculty of Applied Science, University of Campinas, Campinas, Brazil
- Obesity and Comorbidities Research Center, University of Campinas, UNICAMP, Campinas, Brazil
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Sergi D, Williams LM. Potential relationship between dietary long-chain saturated fatty acids and hypothalamic dysfunction in obesity. Nutr Rev 2020; 78:261-277. [PMID: 31532491 DOI: 10.1093/nutrit/nuz056] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Diet-induced hypothalamic inflammation, which leads to hypothalamic dysfunction and a loss of regulation of energy balance, is emerging as a potential driver of obesity. Excessive intake of long-chain saturated fatty acids is held to be the causative dietary component in hypothalamic inflammation. This review summarizes current evidence on the role of long-chain saturated fatty acids in promoting hypothalamic inflammation and the related induction of central insulin and leptin insensitivity. Particularly, the present review focuses on the molecular mechanisms linking long-chain saturated fatty acids and hypothalamic inflammation, emphasizing the metabolic fate of fatty acids and the resulting lipotoxicity, which is a key driver of hypothalamic dysfunction. In conclusion, long-chain saturated fatty acids are key nutrients that promote hypothalamic inflammation and dysfunction by fostering the build-up of lipotoxic lipid species, such as ceramide. Furthermore, when long-chain saturated fatty acids are consumed in combination with high levels of refined carbohydrates, the proinflammatory effects are exacerbated via a mechanism that relies on the formation of advanced glycation end products.
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Affiliation(s)
- Domenico Sergi
- Nutrition and Health Substantiation Group, Nutrition and Health Program, Health and Biosecurity, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Adelaide, South Australia, Australia
| | - Lynda M Williams
- Rowett Institute, University of Aberdeen, Foresterhill, Aberdeen, United Kingdom
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Si X, Tian J, Shu C, Wang Y, Gong E, Zhang Y, Zhang W, Cui H, Li B. Serum Ceramide Reduction by Blueberry Anthocyanin-Rich Extract Alleviates Insulin Resistance in Hyperlipidemia Mice. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2020; 68:8185-8194. [PMID: 32692177 DOI: 10.1021/acs.jafc.0c01931] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Blueberry anthocyanin-rich extract (BAE) was supplemented to high-fat diet (HFD)-fed mice to investigate sphingolipid metabolism modulating factors involved in the attenuated hyperinsulinemia and hyperlipidemia. A BAE-containing diet effectively controlled food intake and liver weight and significantly attenuated insulin resistance triggered by a HFD. Higher BAE (200 mg/kg of body weight) administration performed more efficiently in the improvement of hepatic steatosis and adipocyte hypertrophy, together with distinct suppressions in serum triacylglycerol and cholesterol in total and species. Serum lipid compositions revealed 200 mg/kg of BAE supplementation remarkably suppressed ceramide accumulation. Consistently, genes encoding enzymes associated with sphingomyelin conversion and ceramide de novo synthesis were modulated toward a healthy direction for restrained sphingolipid accumulation. Further, the inhibited mRNA expressions of protein phosphatase 2A and protein kinase Cζ involved in blocking Akt phosphorylation connected the controlled ceramides with the restored insulin sensitivity.
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Affiliation(s)
- Xu Si
- College of Food Science, Shenyang Agricultural University, Shenyang, Liaoning 110866, People's Republic of China
| | - Jinlong Tian
- College of Food Science, Shenyang Agricultural University, Shenyang, Liaoning 110866, People's Republic of China
| | - Chi Shu
- College of Food Science, Shenyang Agricultural University, Shenyang, Liaoning 110866, People's Republic of China
| | - Yuehua Wang
- College of Food Science, Shenyang Agricultural University, Shenyang, Liaoning 110866, People's Republic of China
| | - Ersheng Gong
- College of Food Science, Shenyang Agricultural University, Shenyang, Liaoning 110866, People's Republic of China
| | - Ye Zhang
- College of Food Science, Shenyang Agricultural University, Shenyang, Liaoning 110866, People's Republic of China
| | - Weijia Zhang
- College of Food Science, Shenyang Agricultural University, Shenyang, Liaoning 110866, People's Republic of China
| | - Huijun Cui
- College of Food Science, Shenyang Agricultural University, Shenyang, Liaoning 110866, People's Republic of China
| | - Bin Li
- College of Food Science, Shenyang Agricultural University, Shenyang, Liaoning 110866, People's Republic of China
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Guitton J, Bandet CL, Mariko ML, Tan-Chen S, Bourron O, Benomar Y, Hajduch E, Le Stunff H. Sphingosine-1-Phosphate Metabolism in the Regulation of Obesity/Type 2 Diabetes. Cells 2020; 9:E1682. [PMID: 32668665 PMCID: PMC7407406 DOI: 10.3390/cells9071682] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 07/02/2020] [Accepted: 07/07/2020] [Indexed: 12/19/2022] Open
Abstract
Obesity is a pathophysiological condition where excess free fatty acids (FFA) target and promote the dysfunctioning of insulin sensitive tissues and of pancreatic β cells. This leads to the dysregulation of glucose homeostasis, which culminates in the onset of type 2 diabetes (T2D). FFA, which accumulate in these tissues, are metabolized as lipid derivatives such as ceramide, and the ectopic accumulation of the latter has been shown to lead to lipotoxicity. Ceramide is an active lipid that inhibits the insulin signaling pathway as well as inducing pancreatic β cell death. In mammals, ceramide is a key lipid intermediate for sphingolipid metabolism as is sphingosine-1-phosphate (S1P). S1P levels have also been associated with the development of obesity and T2D. In this review, the current knowledge on S1P metabolism in regulating insulin signaling in pancreatic β cell fate and in the regulation of feeding by the hypothalamus in the context of obesity and T2D is summarized. It demonstrates that S1P can display opposite effects on insulin sensitive tissues and pancreatic β cells, which depends on its origin or its degradation pathway.
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Affiliation(s)
- Jeanne Guitton
- Institut des Neurosciences Paris-Saclay, Université Paris Saclay, CNRS UMR 9197, F-91190 Orsay, France; (J.G.); (M.L.M.); (Y.B.)
| | - Cecile L. Bandet
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, F-75006 Paris, France; (C.L.B.); (S.T.-C.); (O.B.); (E.H.)
- Institut Hospitalo-Universitaire ICAN, F-75013 Paris, France
| | - Mohamed L. Mariko
- Institut des Neurosciences Paris-Saclay, Université Paris Saclay, CNRS UMR 9197, F-91190 Orsay, France; (J.G.); (M.L.M.); (Y.B.)
| | - Sophie Tan-Chen
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, F-75006 Paris, France; (C.L.B.); (S.T.-C.); (O.B.); (E.H.)
- Institut Hospitalo-Universitaire ICAN, F-75013 Paris, France
| | - Olivier Bourron
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, F-75006 Paris, France; (C.L.B.); (S.T.-C.); (O.B.); (E.H.)
- Institut Hospitalo-Universitaire ICAN, F-75013 Paris, France
- Assistance Publique-Hôpitaux de Paris, Département de Diabétologie et Maladies métaboliques, Hôpital Pitié-Salpêtrière, F-75013 Paris, France
| | - Yacir Benomar
- Institut des Neurosciences Paris-Saclay, Université Paris Saclay, CNRS UMR 9197, F-91190 Orsay, France; (J.G.); (M.L.M.); (Y.B.)
| | - Eric Hajduch
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, F-75006 Paris, France; (C.L.B.); (S.T.-C.); (O.B.); (E.H.)
- Institut Hospitalo-Universitaire ICAN, F-75013 Paris, France
| | - Hervé Le Stunff
- Institut des Neurosciences Paris-Saclay, Université Paris Saclay, CNRS UMR 9197, F-91190 Orsay, France; (J.G.); (M.L.M.); (Y.B.)
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Portovedo M, Reginato A, Miyamoto JÉ, Simino LA, Hakim MP, Campana M, Leal RF, Ignácio-Souza LM, Torsoni MA, Magnan C, Le Stunff H, Torsoni AS, Milanski M. Lipid excess affects chaperone-mediated autophagy in hypothalamus. Biochimie 2020; 176:110-116. [PMID: 32623049 DOI: 10.1016/j.biochi.2020.06.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 06/16/2020] [Accepted: 06/18/2020] [Indexed: 01/15/2023]
Abstract
Obesity is a major health problem worldwide. Overweight and obesity directly affect health-related quality of life and also have an important economic impact on healthcare systems. In experimental models, obesity leads to hypothalamic inflammation and loss of metabolic homeostasis. It is known that macroautophagy is decreased in the hypothalamus of obese mice but the role of chaperone-mediated autophagy is still unknown. In this study, we aimed to investigate the role of hypothalamic chaperone-mediated autophagy in response to high-fat diet and also the direct effect of palmitate on hypothalamic neurons. Mice received chow or high-fat diet for 3 days or 1 week. At the end of the experimental protocol, chaperone-mediated autophagy in hypothalamus was investigated, as well as cytokines expression. In other set of experiments, neuronal cell lines were treated with palmitic acid, a saturated fatty acid. We show that chaperone-mediated autophagy is differently regulated in response to high-fat diet intake for 3 days or 1 week. Also, when hypothalamic neurons are directly exposed to palmitate there is activation of chaperone-mediated autophagy. High-fat diet causes hypothalamic inflammation concomitantly to changes in the content of chaperone-mediated autophagy machinery. It remains to be studied the direct role of inflammation and lipids itself on the activation of chaperone-mediated autophagy in the hypothalamus in vivo and also the neuronal implications of chaperone-mediated autophagy inhibition in response to obesity.
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Affiliation(s)
- M Portovedo
- Laboratory of Metabolic Disorders, Faculty of Applied Sciences, UNICAMP, Limeira, 13484-350, Brazil
| | - A Reginato
- Laboratory of Metabolic Disorders, Faculty of Applied Sciences, UNICAMP, Limeira, 13484-350, Brazil
| | - J É Miyamoto
- Laboratory of Metabolic Disorders, Faculty of Applied Sciences, UNICAMP, Limeira, 13484-350, Brazil
| | - L A Simino
- Laboratory of Metabolic Disorders, Faculty of Applied Sciences, UNICAMP, Limeira, 13484-350, Brazil
| | - M P Hakim
- Laboratory of Metabolic Disorders, Faculty of Applied Sciences, UNICAMP, Limeira, 13484-350, Brazil
| | - M Campana
- Université de Paris, BFA, UMR 8251, CNRS, F-75013, Paris, France
| | - R F Leal
- IBD Research Laboratory, Colorectal Surgery Unit, Department of Surgery, School of Medical Sciences, UNICAMP, Campinas, 13083-878, Brazil
| | - L M Ignácio-Souza
- Laboratory of Metabolic Disorders, Faculty of Applied Sciences, UNICAMP, Limeira, 13484-350, Brazil
| | - M A Torsoni
- Laboratory of Metabolic Disorders, Faculty of Applied Sciences, UNICAMP, Limeira, 13484-350, Brazil
| | - C Magnan
- Université de Paris, BFA, UMR 8251, CNRS, F-75013, Paris, France
| | - H Le Stunff
- Université de Paris, BFA, UMR 8251, CNRS, F-75013, Paris, France
| | - A S Torsoni
- Laboratory of Metabolic Disorders, Faculty of Applied Sciences, UNICAMP, Limeira, 13484-350, Brazil
| | - M Milanski
- Laboratory of Metabolic Disorders, Faculty of Applied Sciences, UNICAMP, Limeira, 13484-350, Brazil.
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Oshima M, Pechberty S, Bellini L, Göpel SO, Campana M, Rouch C, Dairou J, Cosentino C, Fantuzzi F, Toivonen S, Marchetti P, Magnan C, Cnop M, Le Stunff H, Scharfmann R. Stearoyl CoA desaturase is a gatekeeper that protects human beta cells against lipotoxicity and maintains their identity. Diabetologia 2020; 63:395-409. [PMID: 31796987 PMCID: PMC6946759 DOI: 10.1007/s00125-019-05046-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 10/14/2019] [Indexed: 01/02/2023]
Abstract
AIMS/HYPOTHESIS During the onset of type 2 diabetes, excessive dietary intake of saturated NEFA and fructose lead to impaired insulin production and secretion by insulin-producing pancreatic beta cells. The majority of data on the deleterious effects of lipids on functional beta cell mass were obtained either in vivo in rodent models or in vitro using rodent islets and beta cell lines. Translating data from rodent to human beta cells remains challenging. Here, we used the human beta cell line EndoC-βH1 and analysed its sensitivity to a lipotoxic and glucolipotoxic (high palmitate with or without high glucose) insult, as a way to model human beta cells in a type 2 diabetes environment. METHODS EndoC-βH1 cells were exposed to palmitate after knockdown of genes related to saturated NEFA metabolism. We analysed whether and how palmitate induces apoptosis, stress and inflammation and modulates beta cell identity. RESULTS EndoC-βH1 cells were insensitive to the deleterious effects of saturated NEFA (palmitate and stearate) unless stearoyl CoA desaturase (SCD) was silenced. SCD was abundantly expressed in EndoC-βH1 cells, as well as in human islets and human induced pluripotent stem cell-derived beta cells. SCD silencing induced markers of inflammation and endoplasmic reticulum stress and also IAPP mRNA. Treatment with the SCD products oleate or palmitoleate reversed inflammation and endoplasmic reticulum stress. Upon SCD knockdown, palmitate induced expression of dedifferentiation markers such as SOX9, MYC and HES1. Interestingly, SCD knockdown by itself disrupted beta cell identity with a decrease in mature beta cell markers INS, MAFA and SLC30A8 and decreased insulin content and glucose-stimulated insulin secretion. CONCLUSIONS/INTERPRETATION The present study delineates an important role for SCD in the protection against lipotoxicity and in the maintenance of human beta cell identity. DATA AVAILABILITY Microarray data and all experimental details that support the findings of this study have been deposited in in the GEO database with the GSE130208 accession code.
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Affiliation(s)
- Masaya Oshima
- Université Paris Descartes, Institut Cochin, Inserm U1016, 123 bd du Port-Royal, 75014, Paris, France
| | - Séverine Pechberty
- Université Paris Descartes, Institut Cochin, Inserm U1016, 123 bd du Port-Royal, 75014, Paris, France
| | - Lara Bellini
- Unité Biologie Fonctionnelle et Adaptative, CNRS UMR 8251, Paris, France
| | - Sven O Göpel
- Bioscience Metabolism, Research and Early Development Cardiovascular Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Mélanie Campana
- Unité Biologie Fonctionnelle et Adaptative, CNRS UMR 8251, Paris, France
| | - Claude Rouch
- Unité Biologie Fonctionnelle et Adaptative, CNRS UMR 8251, Paris, France
| | - Julien Dairou
- Université Paris Descartes CNRS UMR 8601, Paris, France
| | - Cristina Cosentino
- ULB Center for Diabetes Research, Université Libre de Bruxelles, Brussels, Belgium
| | - Federica Fantuzzi
- ULB Center for Diabetes Research, Université Libre de Bruxelles, Brussels, Belgium
| | - Sanna Toivonen
- ULB Center for Diabetes Research, Université Libre de Bruxelles, Brussels, Belgium
| | - Piero Marchetti
- University of Pisa, Department of Clinical and Experimental Medicine, Pisa, Italy
| | - Christophe Magnan
- Unité Biologie Fonctionnelle et Adaptative, CNRS UMR 8251, Paris, France
| | - Miriam Cnop
- ULB Center for Diabetes Research, Université Libre de Bruxelles, Brussels, Belgium
- Division of Endocrinology, ULB Erasmus Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Hervé Le Stunff
- Unité Biologie Fonctionnelle et Adaptative, CNRS UMR 8251, Paris, France
- Université Paris-Sud, CNRS UMR 9197, Institut des Neurosciences Paris-Saclay (Neuro-PSI) - CNRS UMR 9197, Orsay, France
| | - Raphaël Scharfmann
- Université Paris Descartes, Institut Cochin, Inserm U1016, 123 bd du Port-Royal, 75014, Paris, France.
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Cheng H, Gang X, He G, Liu Y, Wang Y, Zhao X, Wang G. The Molecular Mechanisms Underlying Mitochondria-Associated Endoplasmic Reticulum Membrane-Induced Insulin Resistance. Front Endocrinol (Lausanne) 2020; 11:592129. [PMID: 33329397 PMCID: PMC7719781 DOI: 10.3389/fendo.2020.592129] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 10/26/2020] [Indexed: 12/13/2022] Open
Abstract
Mitochondria and the endoplasmic reticulum (ER) are connected at multiple sites via what are known as mitochondria-associated ER membranes (MAMs). These associations are known to play an important role in maintaining cellular homeostasis. Impaired MAM signaling has wide-ranging effects in many diseases, such as obesity, diabetes, and neurodegenerative disorders. Accumulating evidence has suggested that MAMs influence insulin signaling through different pathways, including those associated with Ca2+ signaling, lipid metabolism, mitochondrial function, ER stress responses, and inflammation. Altered MAM signaling is a common feature of insulin resistance in different tissues, including the liver, muscle, and even the brain. In the liver, MAMs are key glucose-sensing regulators and have been proposed to be a hub for insulin signaling. Impaired MAM integrity has been reported to disrupt hepatic responses to changes in glucose availability during nutritional transition and to induce hepatic insulin resistance. Meanwhile, these effects can be rescued by the reinforcement of MAM interactions. In contrast, several studies have proposed that enhanced ER-mitochondria connections are detrimental to hepatic insulin signaling and can lead to mitochondrial dysfunction. Thus, given these contradictory results, the role played by the MAM in the regulation of hepatic insulin signaling remains elusive. Similarly, in skeletal muscle, enhanced MAM formation may be beneficial in the early stage of diabetes, whereas continuous MAM enhancement aggravates insulin resistance. Furthermore, recent studies have suggested that ER stress may be the primary pathway through which MAMs induce brain insulin resistance, especially in the hypothalamus. This review will discuss the possible mechanisms underlying MAM-associated insulin resistance as well as the therapeutic potential of targeting the MAM in the treatment of type 2 diabetes.
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Affiliation(s)
| | | | | | | | | | - Xue Zhao
- *Correspondence: Guixia Wang, ; Xue Zhao,
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Gao J, Huang T, Li J, Guo X, Xiao H, Gu J, Tang J, Cai W, Li D. Beneficial Effects of n-3 Polyunsaturated Fatty Acids on Offspring's Pancreas of Gestational Diabetes Rats. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2019; 67:13269-13281. [PMID: 31725275 DOI: 10.1021/acs.jafc.9b05739] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We studied the long-term influence of gestational diabetes mellitus (GDM) on the pancreas of offspring and the effect of omega-3 polyunsaturated fatty acids (n-3 PUFAs) on offspring's pancreas. GDM offspring were divided into three groups: GDM offspring, n-3 PUFA-adequate-GDM offspring, and n-3 PUFA-deficient GDM offspring. All healthy and GDM offspring were fed up to 11 months old. The pancreas of GDM offspring exhibited fatty infiltration at 11 months old, whereas n-3 PUFA improved the pancreatic fatty infiltration. n-3 PUFA lowered the pancreatic oxidative stress and inflammation. Surprisingly, n-3 PUFA postponed pancreatic telomere shortening of GDM offspring at old age. Nontargeted metabolomics showed that many metabolites were altered in the pancreas of GDM offspring at old age, including l-valine, ceramide, acylcarnitines, tocotrienol, cholesteryl acetate, and biotin. n-3 PUFA modulated some altered metabolites and metabolic pathways. Therefore, GDM caused the long-term effects on offspring's pancreas, whereas n-3 PUFA played a beneficial role.
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Affiliation(s)
- Jinlong Gao
- Department of Food Science and Nutrition , Zhejiang University , 866 Yuhangtang Road , Hangzhou 310058 , China
| | - Tao Huang
- Department of Epidemiology and Biostatistics , Peking University , 5 Yiheyuan Road , Beijing 100871 , China
| | - Jiaomei Li
- Institute of Nutrition and Health , Qingdao University , 308 Ningxia Road , Qingdao 266071 , China
| | - Xiaofei Guo
- Institute of Nutrition and Health , Qingdao University , 308 Ningxia Road , Qingdao 266071 , China
| | - Hailong Xiao
- Department of Food Inspection , Hangzhou Institute for Food and Drug Control , 198 Yonghua Street , Hangzhou 310022 , China
| | - Jiaojiao Gu
- School of Nursing , Zhejiang Chinese Medical University , 548 Binwen Road , Hangzhou 310053 , China
| | - Jun Tang
- Department of Food Science and Nutrition , Zhejiang University , 866 Yuhangtang Road , Hangzhou 310058 , China
| | - Wenwen Cai
- Department of Food Science and Nutrition , Zhejiang University , 866 Yuhangtang Road , Hangzhou 310058 , China
| | - Duo Li
- Department of Food Science and Nutrition , Zhejiang University , 866 Yuhangtang Road , Hangzhou 310058 , China
- Institute of Nutrition and Health , Qingdao University , 308 Ningxia Road , Qingdao 266071 , China
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Abarkan M, Gaitan J, Lebreton F, Perrier R, Jaffredo M, Mulle C, Magnan C, Raoux M, Lang J. The glutamate receptor GluK2 contributes to the regulation of glucose homeostasis and its deterioration during aging. Mol Metab 2019; 30:152-160. [PMID: 31767166 PMCID: PMC6807305 DOI: 10.1016/j.molmet.2019.09.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 09/04/2019] [Accepted: 09/27/2019] [Indexed: 01/23/2023] Open
Abstract
OBJECTIVE Islets secrete neurotransmitters including glutamate which participate in fine regulation of islet function. The excitatory ionotropic glutamate receptor GluK2 of the kainate receptor family is widely expressed in brain and also found in islets, mainly in α and γ cells. α cells co-release glucagon and glutamate and the latter increases glucagon release via ionotropic glutamate receptors. However, neither the precise nature of the ionotropic glutamate receptor involved nor its role in glucose homeostasis is known. As isoform specific pharmacology is not available, we investigated this question in constitutive GluK2 knock-out mice (GluK2-/-) using adult and middle-aged animals to also gain insight in a potential role during aging. METHODS We compared wild-type GluK2+/+ and knock-out GluK2-/- mice using adult (14-20 weeks) and middle-aged animals (40-52 weeks). Glucose (oral OGTT and intraperitoneal IPGTT) and insulin tolerance as well as pyruvate challenge tests were performed according to standard procedures. Parasympathetic activity, which stimulates hormones secretion, was measured by electrophysiology in vivo. Isolated islets were used in vitro to determine islet β-cell electrical activity on multi-electrode arrays and dynamic secretion of insulin as well as glucagon was determined by ELISA. RESULTS Adult GluK2-/- mice exhibit an improved glucose tolerance (OGTT and IPGTT), and this was also apparent in middle-aged mice, whereas the outcome of pyruvate challenge was slightly improved only in middle-aged GluK2-/- mice. Similarly, insulin sensitivity was markedly enhanced in middle-aged GluK2-/- animals. Basal and glucose-induced insulin secretion in vivo was slightly lower in GluK2-/- mice, whereas fasting glucagonemia was strongly reduced. In vivo recordings of parasympathetic activity showed an increase in basal activity in GluK2-/- mice which represents most likely an adaptive mechanism to counteract hypoglucagonemia rather than altered neuronal mechanism. In vitro recording demonstrated an improvement of glucose-induced electrical activity of β-cells in islets obtained from GluK2-/- mice at both ages. Finally, glucose-induced insulin secretion in vitro was increased in GluK2-/- islets, whereas glucagon secretion at 2 mmol/l of glucose was considerably reduced. CONCLUSIONS These observations indicate a general role for kainate receptors in glucose homeostasis and specifically suggest a negative effect of GluK2 on glucose homeostasis and preservation of islet function during aging. Our observations raise the possibility that blockade of GluK2 may provide benefits in glucose homeostasis especially during aging.
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Affiliation(s)
- Myriam Abarkan
- Chimie et Biologie des Membranes et Nano-objets, UMR CNRS 5248, Université de Bordeaux, Pessac, France
| | - Julien Gaitan
- Chimie et Biologie des Membranes et Nano-objets, UMR CNRS 5248, Université de Bordeaux, Pessac, France
| | - Fanny Lebreton
- Chimie et Biologie des Membranes et Nano-objets, UMR CNRS 5248, Université de Bordeaux, Pessac, France
| | - Romain Perrier
- Chimie et Biologie des Membranes et Nano-objets, UMR CNRS 5248, Université de Bordeaux, Pessac, France
| | - Manon Jaffredo
- Chimie et Biologie des Membranes et Nano-objets, UMR CNRS 5248, Université de Bordeaux, Pessac, France
| | - Christophe Mulle
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Université de Bordeaux, Bordeaux, France
| | - Christophe Magnan
- Unité de Biologie Fonctionnelle et Adaptative, UMR 8251, CNRS, Université de Paris, Paris, France
| | - Matthieu Raoux
- Chimie et Biologie des Membranes et Nano-objets, UMR CNRS 5248, Université de Bordeaux, Pessac, France
| | - Jochen Lang
- Chimie et Biologie des Membranes et Nano-objets, UMR CNRS 5248, Université de Bordeaux, Pessac, France.
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Al-Daghri NM, Torretta E, Barbacini P, Asare H, Ricci C, Capitanio D, Guerini FR, Sabico SB, Alokail MS, Clerici M, Gelfi C. Sphingolipid serum profiling in vitamin D deficient and dyslipidemic obese dimorphic adults. Sci Rep 2019; 9:16664. [PMID: 31723209 PMCID: PMC6853956 DOI: 10.1038/s41598-019-53122-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 10/18/2019] [Indexed: 12/23/2022] Open
Abstract
Recent studies on Saudi Arabians indicate a prevalence of dyslipidemia and vitamin D deficiency (25(OH)D) in both normal weight and obese subjects. In the present study the sphingolipid pattern was investigated in 23 normolipidemic normal weight (NW), 46 vitamin D deficient dyslipidemic normal weight (-vitDNW) and 60 vitamin D deficient dyslipidemic obese (-vitDO) men and women by HPTLC-primuline profiling and LC-MS analyses. Results indicate higher levels of total ceramide (Cer) and dihydroceramide (dhCers C18–22) and lower levels of total sphingomyelins (SMs) and dihydrosphingomyelin (dhSM) not only in -vitDO subjects compared to NW, but also in –vitDNW individuals. A dependency on body mass index (BMI) was observed analyzing specific Cer acyl chains levels. Lower levels of C20 and 24 were observed in men and C24.2 in women, respectively. Furthermore, LC-MS analyses display dimorphic changes in NW, -vitDNW and –vitDO subjects. In conclusion, LC-MS data identify the independency of the axis high Cers, dhCers and SMs from obesity per se. Furthermore, it indicates that long chains Cers levels are specific target of weight gain and that circulating Cer and SM levels are linked to sexual dimorphism status and can contribute to predict obese related co-morbidities in men and women.
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Affiliation(s)
- Nasser M Al-Daghri
- Prince Mutaib Chair for Biomarkers of Osteoporosis, Biochemistry Department, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia
| | - Enrica Torretta
- Department of Biomedical Sciences for Health, University of Milan, Segrate-Milano, Italy
| | - Pietro Barbacini
- Department of Biomedical Sciences for Health, University of Milan, Segrate-Milano, Italy
| | - Hannah Asare
- Centre of Excellence for Nutrition (CEN), Potchefstroom, 2531, South Africa
| | - Cristian Ricci
- Centre of Excellence for Nutrition (CEN), Potchefstroom, 2531, South Africa
| | - Daniele Capitanio
- Department of Biomedical Sciences for Health, University of Milan, Segrate-Milano, Italy.,IRCCS Istituto Ortopedico Galeazzi, Milano, Italy
| | | | - Shaun B Sabico
- Prince Mutaib Chair for Biomarkers of Osteoporosis, Biochemistry Department, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia
| | - Majed S Alokail
- Prince Mutaib Chair for Biomarkers of Osteoporosis, Biochemistry Department, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia
| | - Mario Clerici
- IRCCS Fondazione Don Carlo Gnocchi, Milano, Italy.,Department of Physiopathology and Transplants, University of Milano, Milano, Italy
| | - Cecilia Gelfi
- Department of Biomedical Sciences for Health, University of Milan, Segrate-Milano, Italy. .,IRCCS Istituto Ortopedico Galeazzi, Milano, Italy.
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Feeding Stimulates Sphingosine-1-Phosphate Mobilization in Mouse Hypothalamus. Int J Mol Sci 2019; 20:ijms20164008. [PMID: 31426457 PMCID: PMC6720287 DOI: 10.3390/ijms20164008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2019] [Revised: 08/12/2019] [Accepted: 08/15/2019] [Indexed: 12/13/2022] Open
Abstract
Previous studies have shown that the sphingolipid-derived mediator sphingosine-1-phosphate (S1P) reduces food intake by activating G protein-coupled S1P receptor-1 (S1PR1) in the hypothalamus. Here, we examined whether feeding regulates hypothalamic mobilization of S1P and other sphingolipid-derived messengers. We prepared lipid extracts from the hypothalamus of C57Bl6/J male mice subjected to one of four conditions: free feeding, 12 h fasting, and 1 h or 6 h refeeding. Liquid chromatography/tandem mass spectrometry was used to quantify various sphingolipid species, including sphinganine (SA), sphingosine (SO), and their bioactive derivatives SA-1-phosphate (SA1P) and S1P. In parallel experiments, transcription of S1PR1 (encoded in mice by the S1pr1 gene) and of key genes of sphingolipid metabolism (Sptlc2, Lass1, Sphk1, Sphk2) was measured by RT-PCR. Feeding increased levels of S1P (in pmol-mg−1 of wet tissue) and SA1P. This response was accompanied by parallel changes in SA and dihydroceramide (d18:0/18:0), and was partially (SA1P) or completely (S1P) reversed by fasting. No such effects were observed with other sphingolipid species targeted by our analysis. Feeding also increased transcription of Sptlc2, Lass1, Sphk2, and S1pr1. Feeding stimulates mobilization of endogenous S1PR1 agonists S1P and SA1P in mouse hypothalamus, via a mechanism that involves transcriptional up-regulation of de novo sphingolipid biosynthesis. The results support a role for sphingolipid-mediated signaling in the central control of energy balance.
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Le Stunff H, Véret J, Kassis N, Denom J, Meneyrol K, Paul JL, Cruciani-Guglielmacci C, Magnan C, Janel N. Deciphering the Link Between Hyperhomocysteinemia and Ceramide Metabolism in Alzheimer-Type Neurodegeneration. Front Neurol 2019; 10:807. [PMID: 31417486 PMCID: PMC6684947 DOI: 10.3389/fneur.2019.00807] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 07/15/2019] [Indexed: 12/13/2022] Open
Abstract
Aging is one of the strongest risk factor for Alzheimer's disease (AD). However, several data suggest that dyslipidemia can either contribute or serve as co-factors in AD appearance. AD could be examined as a metabolic disorder mediated by peripheral insulin resistance. Insulin resistance is associated with dyslipidemia, which results in increased hepatic ceramide generation. Hepatic steatosis induces pro-inflammatory cytokine activation which is mediated by the increased ceramides production. Ceramides levels increased in cells due to perturbation in sphingolipid metabolism and upregulated expression of enzymes involved in ceramide synthesis. Cytotoxic ceramides and related molecules generated in liver promote insulin resistance, traffic through the circulation due to injury or cell death caused by local liver inflammation, and because of their hydrophobic nature, they can cross the blood-brain barrier and thereby exert neurotoxic responses as reducing insulin signaling and increasing pro-inflammatory cytokines. These abnormalities propagate a cascade of neurodegeneration associated with oxidative stress and ceramide generation, which potentiate brain insulin resistance, apoptosis, myelin degeneration, and neuro-inflammation. Therefore, excess of toxic lipids generated in liver can cause neurodegeneration. Elevated homocysteine level is also a risk factor for AD pathology and is narrowly associated with metabolic diseases and non-alcoholic fatty liver disease. The existence of a homocysteine/ceramides signaling pathway suggests that homocysteine toxicity could be partly mediated by intracellular ceramide accumulation due to stimulation of ceramide synthase. In this article, we briefly examined the role of homocysteine and ceramide metabolism linking metabolic diseases and non-alcoholic fatty liver disease to AD. We therefore analyzed the expression of mainly enzymes implicated in ceramide and sphingolipid metabolism and demonstrated deregulation of de novo ceramide biosynthesis and S1P metabolism in liver and brain of hyperhomocysteinemic mice.
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Affiliation(s)
- Hervé Le Stunff
- Université de Paris, BFA, UMR 8251, CNRS, Paris, France.,Institut des Neurosciences Paris-Saclay (Neuro-PSI), Université Paris-Sud, CNRS UMR 9197, Orsay, France
| | - Julien Véret
- Université de Paris, BFA, UMR 8251, CNRS, Paris, France
| | - Nadim Kassis
- Université de Paris, BFA, UMR 8251, CNRS, Paris, France
| | - Jessica Denom
- Université de Paris, BFA, UMR 8251, CNRS, Paris, France
| | | | - Jean-Louis Paul
- AP-HP, Hôpital Européen Georges Pompidou, Service de Biochimie, Paris, France
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41
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Potential therapeutic targets for atherosclerosis in sphingolipid metabolism. Clin Sci (Lond) 2019; 133:763-776. [PMID: 30890654 PMCID: PMC6422862 DOI: 10.1042/cs20180911] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 02/13/2019] [Accepted: 02/14/2019] [Indexed: 12/14/2022]
Abstract
Sphingolipids, such as sphingomyelins, ceramides, glycosphingolipids, and sphingosine-1-phosphates (S1P) are a large group of structurally and functionally diverse molecules. Some specific species are found associated with atherogenesis and provide novel therapeutic targets. Herein, we briefly review how sphingolipids are implicated in the progression of atherosclerosis and related diseases, and then we discuss the potential therapy options by targetting several key enzymes in sphingolipid metabolism.
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42
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Molecular Mechanisms of Hypothalamic Insulin Resistance. Int J Mol Sci 2019; 20:ijms20061317. [PMID: 30875909 PMCID: PMC6471380 DOI: 10.3390/ijms20061317] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 03/07/2019] [Accepted: 03/13/2019] [Indexed: 02/06/2023] Open
Abstract
Insulin exists in the central nervous system, where it executes two important functions in the hypothalamus: the suppression of food intake and the improvement of glucose metabolism. Recent studies have shown that both are exerted robustly in rodents and humans. If intact, these functions exert beneficial effects on obesity and diabetes, respectively. Disruption of both occurs due to a condition known as hypothalamic insulin resistance, which is caused by obesity and the overconsumption of saturated fat. An enormous volume of literature addresses the molecular mechanisms of hypothalamic insulin resistance. IKKβ and JNK are major players in the inflammation pathway, which is activated by saturated fatty acids that induce hypothalamic insulin resistance. Two major tyrosine phosphatases, PTP-1B and TCPTP, are upregulated in chronic overeating. They dephosphorylate the insulin receptor and insulin receptor substrate proteins, resulting in hypothalamic insulin resistance. Prolonged hyperinsulinemia with excessive nutrition activates the mTOR/S6 kinase pathway, thereby enhancing IRS-1 serine phosphorylation to induce hypothalamic insulin resistance. Other mechanisms associated with this condition include hypothalamic gliosis and disturbed insulin transport into the central nervous system. Unveiling the precise molecular mechanisms involved in hypothalamic insulin resistance is important for developing new ways of treating obesity and type 2 diabetes.
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43
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Nyamugenda E, Trentzsch M, Russell S, Miles T, Boysen G, Phelan KD, Baldini G. Injury to hypothalamic Sim1 neurons is a common feature of obesity by exposure to high-fat diet in male and female mice. J Neurochem 2019; 149:73-97. [PMID: 30615192 DOI: 10.1111/jnc.14662] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 10/16/2018] [Accepted: 01/04/2019] [Indexed: 12/13/2022]
Abstract
The hypothalamus is essential for regulation of energy homeostasis and metabolism. Feeding hypercaloric, high-fat (HF) diet induces hypothalamic arcuate nucleus injury and alters metabolism more severely in male than in female mice. The site(s) and extent of hypothalamic injury in male and female mice are not completely understood. In the paraventricular nucleus (PVN) of the hypothalamus, single-minded family basic helix-loop helix transcription factor 1 (Sim1) neurons are essential to control energy homeostasis. We tested the hypothesis that exposure to HF diet induces injury to Sim1 neurons in the PVN of male and female mice. Mice expressing membrane-bound enhanced green fluorescent protein (mEGFP) in Sim1 neurons (Sim1-Cre:Rosa-mEGFP mice) were generated to visualize the effects of exposure to HF diet on these neurons. Male and female Sim1-Cre:Rosa-mEGFP mice exposed to HF diet had increased weight, hyperleptinemia, and developed hepatosteatosis. In male and female mice exposed to HF diet, expression of mEGFP was reduced by > 40% in Sim1 neurons of the PVN, an effect paralleled by cell apoptosis and neuronal loss, but not by microgliosis. In the arcuate nucleus of the Sim1-Cre:Rosa-mEGFP male mice, there was decreased alpha-melanocyte-stimulating hormone in proopiomelanocortin neurons projecting to the PVN, with increased cell apoptosis, neuronal loss, and microgliosis. These defects were undetectable in the arcuate nucleus of female mice exposed to the HF diet. Thus, injury to Sim1 neurons of the PVN is a shared feature of exposure to HF diet in mice of both sexes, while injury to proopiomelanocortin neurons in arcuate nucleus is specific to male mice. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/.
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Affiliation(s)
- Eugene Nyamugenda
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Marcus Trentzsch
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Susan Russell
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Tiffany Miles
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Gunnar Boysen
- Department of Environmental and Occupational Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.,The Winthrop P Rockefeller Cancer Institute, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Kevin D Phelan
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Giulia Baldini
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
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44
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Levi NJ, Wilson CW, Redweik GAJ, Gray NW, Grzybowski CW, Lenkey JA, Moseman AW, Bertsch AD, Dao N, Walsh HE. Obesity-related cellular stressors regulate gonadotropin releasing hormone gene expression via c-Fos/AP-1. Mol Cell Endocrinol 2018; 478:97-105. [PMID: 30063946 DOI: 10.1016/j.mce.2018.07.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 07/14/2018] [Accepted: 07/25/2018] [Indexed: 12/15/2022]
Abstract
Obesity is a risk factor for infertility, but mechanisms underlying this risk are unclear. Fertility is regulated by hypothalamic gonadotropin-releasing hormone, encoded by the Gnrh1 gene. Because obesity promotes endoplasmic reticulum (ER) stress, we sought to determine how tunicamycin-induced ER stress affected Gnrh1 gene expression in the mouse hypothalamic cell line GT1-7. Tunicamycin repressed expression of Gnrh1 in a PKC- and JNK-dependent manner, while upregulating expression of a known Gnrh1 repressor, Fos. Obesity is associated with increased circulating free fatty acids, and exposure to palmitate promoted ER stress and inflammation. Fos expression increased with palmitate dose, but Gnrh1 expression was upregulated with low-dose palmitate and repressed with high-dose palmitate. Using a small molecule inhibitor, we determined that AP-1 was required for Gnrh1 repression by high-dose palmitate or tunicamycin-induced ER stress. These findings suggest that hypogonadism driven by decreased hypothalamic GnRH may be a component of obesity-related infertility.
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Affiliation(s)
- Noah J Levi
- Department of Biology, Wabash College, PO Box 352, Crawfordsville, IN, 47933, USA
| | - Christopher W Wilson
- Department of Biology, Wabash College, PO Box 352, Crawfordsville, IN, 47933, USA
| | - Graham A J Redweik
- Department of Biology, Wabash College, PO Box 352, Crawfordsville, IN, 47933, USA
| | - Nathan W Gray
- Department of Biology, Wabash College, PO Box 352, Crawfordsville, IN, 47933, USA
| | - Cody W Grzybowski
- Department of Biology, Wabash College, PO Box 352, Crawfordsville, IN, 47933, USA
| | - Joseph A Lenkey
- Department of Biology, Wabash College, PO Box 352, Crawfordsville, IN, 47933, USA
| | - Anthony W Moseman
- Department of Biology, Wabash College, PO Box 352, Crawfordsville, IN, 47933, USA
| | - Alec D Bertsch
- Department of Biology, Wabash College, PO Box 352, Crawfordsville, IN, 47933, USA
| | - Nhien Dao
- Department of Biology, Wabash College, PO Box 352, Crawfordsville, IN, 47933, USA
| | - Heidi E Walsh
- Department of Biology, Wabash College, PO Box 352, Crawfordsville, IN, 47933, USA.
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45
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Fan W, Hou J, Zhu W, Zhang S, Shao K, Quan F, Chen W. The mechanism of the preventive effect of Shen’an capsule on the calcium oxalate crystal-induced early renal injury based on metabolomics. Biomed Chromatogr 2018; 32:e4374. [PMID: 30141275 DOI: 10.1002/bmc.4374] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 08/09/2018] [Accepted: 08/17/2018] [Indexed: 12/25/2022]
Affiliation(s)
- Wei Fan
- No. 425 Hospital of PLA; Sanya China
| | - Jiebin Hou
- Changhai Hospital; Second Military Medical University; Shanghai China
| | - Weiye Zhu
- Changhai Hospital; Second Military Medical University; Shanghai China
| | - Shuyue Zhang
- Cadets Brigade; Second Military Medical University; Shanghai China
| | - Keda Shao
- Cadets Brigade; Second Military Medical University; Shanghai China
| | | | - Wei Chen
- Changhai Hospital; Second Military Medical University; Shanghai China
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46
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Metcalfe LK, Smith GC, Turner N. Defining lipid mediators of insulin resistance - controversies and challenges. J Mol Endocrinol 2018; 62:JME-18-0023. [PMID: 30068522 DOI: 10.1530/jme-18-0023] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 07/04/2018] [Accepted: 07/31/2018] [Indexed: 12/31/2022]
Abstract
Essential elements of all cells, lipids play important roles in energy production, signalling and as structural components. Despite these critical functions, excessive availability and intracellular accumulation of lipid is now recognised as a major factor contributing to many human diseases, including obesity and diabetes. In the context of these metabolic disorders, ectopic deposition of lipid has been proposed to have deleterious effects of insulin action. While this relationship has been recognised for some time now, there is currently no unifying mechanism to explain how lipids precipitate the development of insulin resistance. This review summarises the evidence linking specific lipid molecules to the induction of insulin resistance, describing some of the current controversies and challenges for future studies in this field.
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Affiliation(s)
- Louise K Metcalfe
- L Metcalfe, Department of Pharmacology, School of Medical Sciences, UNSW Australia, Kensington, Australia
| | - Greg C Smith
- G Smith, Department of Pharmacology, School of Medical Sciences, UNSW Australia, Kensington, Australia
| | - Nigel Turner
- N Turner, Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, Australia
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47
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Régnier M, Polizzi A, Guillou H, Loiseau N. Sphingolipid metabolism in non-alcoholic fatty liver diseases. Biochimie 2018; 159:9-22. [PMID: 30071259 DOI: 10.1016/j.biochi.2018.07.021] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 07/26/2018] [Indexed: 12/12/2022]
Abstract
Non-alcoholic fatty liver disease (NAFLD) involves a panel of pathologies starting with hepatic steatosis and continuing to irreversible and serious conditions like steatohepatitis (NASH) and hepatocarcinoma. NAFLD is multifactorial in origin and corresponds to abnormal fat deposition in liver. Even if triglycerides are mostly associated with these pathologies, other lipid moieties seem to be involved in the development and severity of NAFLD. That is the case with sphingolipids and more particularly ceramides. In this review, we explore the relationship between NAFLD and sphingolipid metabolism. After providing an analysis of complex sphingolipid metabolism, we focus on the potential involvement of sphingolipids in the different pathologies associated with NAFLD. An unbalanced ratio between ceramides and terminal metabolic products in the liver and plasma promotes weight gain, inflammation, and insulin resistance. In the etiology of NAFLD, some sphingolipid species such as ceramides may be potential biomarkers for NAFLD. We review the clinical relevance of sphingolipids in liver diseases.
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Affiliation(s)
- Marion Régnier
- INRA UMR1331, ToxAlim, Chemin de Tournefeuille, 31027 Toulouse, France
| | - Arnaud Polizzi
- INRA UMR1331, ToxAlim, Chemin de Tournefeuille, 31027 Toulouse, France
| | - Hervé Guillou
- INRA UMR1331, ToxAlim, Chemin de Tournefeuille, 31027 Toulouse, France
| | - Nicolas Loiseau
- INRA UMR1331, ToxAlim, Chemin de Tournefeuille, 31027 Toulouse, France.
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48
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Sergi D, Morris AC, Kahn DE, McLean FH, Hay EA, Kubitz P, MacKenzie A, Martinoli MG, Drew JE, Williams LM. Palmitic acid triggers inflammatory responses in N42 cultured hypothalamic cells partially via ceramide synthesis but not via TLR4. Nutr Neurosci 2018; 23:321-334. [PMID: 30032721 DOI: 10.1080/1028415x.2018.1501533] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
A high-fat diet induces hypothalamic inflammation in rodents which, in turn, contributes to the development of obesity by eliciting both insulin and leptin resistance. However, the mechanism by which long-chain saturated fatty acids trigger inflammation is still contentious. To elucidate this mechanism, the effect of fatty acids on the expression of the pro-inflammatory cytokines IL-6 and TNFα was investigated in the mHypoE-N42 hypothalamic cell line (N42). N42 cells were treated with lauric acid (LA) and palmitic acid (PA). PA challenge was carried out in the presence of either a TLR4 inhibitor, a ceramide synthesis inhibitor (L-cycloserine), oleic acid (OA) or eicosapentaenoic acid (EPA). Intracellular ceramide accumulation was quantified using LC-ESI-MS/MS. PA but not LA upregulated IL-6 and TNFα. L-cycloserine, OA and EPA all counteracted PA-induced intracellular ceramide accumulation leading to a downregulation of IL-6 and TNFα. However, a TLR4 inhibitor failed to inhibit PA-induced upregulation of pro-inflammatory cytokines.In conclusion, PA induced the expression of IL-6 and TNFα in N42 neuronal cells independently of TLR4 but, partially, via ceramide synthesis with OA and EPA being anti-inflammatory by decreasing PA-induced intracellular ceramide build-up. Thus, ceramide accumulation represents one on the mechanisms by which PA induces inflammation in neurons.
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Affiliation(s)
- Domenico Sergi
- Rowett Institute, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Amanda C Morris
- Rowett Institute, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Darcy E Kahn
- Rowett Institute, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Fiona H McLean
- Rowett Institute, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Elizabeth A Hay
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Phil Kubitz
- Rowett Institute, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Alasdair MacKenzie
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Maria G Martinoli
- Cellular Neurobiology Group, Université du Québec, Trois-Rivières, Québec, G9A 5H7 Canada
| | - Janice E Drew
- Rowett Institute, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Lynda M Williams
- Rowett Institute, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
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49
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Onyango AN. Cellular Stresses and Stress Responses in the Pathogenesis of Insulin Resistance. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2018; 2018:4321714. [PMID: 30116482 PMCID: PMC6079365 DOI: 10.1155/2018/4321714] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Accepted: 02/18/2018] [Indexed: 12/14/2022]
Abstract
Insulin resistance (IR), a key component of the metabolic syndrome, precedes the development of diabetes, cardiovascular disease, and Alzheimer's disease. Its etiological pathways are not well defined, although many contributory mechanisms have been established. This article summarizes such mechanisms into the hypothesis that factors like nutrient overload, physical inactivity, hypoxia, psychological stress, and environmental pollutants induce a network of cellular stresses, stress responses, and stress response dysregulations that jointly inhibit insulin signaling in insulin target cells including endothelial cells, hepatocytes, myocytes, hypothalamic neurons, and adipocytes. The insulin resistance-inducing cellular stresses include oxidative, nitrosative, carbonyl/electrophilic, genotoxic, and endoplasmic reticulum stresses; the stress responses include the ubiquitin-proteasome pathway, the DNA damage response, the unfolded protein response, apoptosis, inflammasome activation, and pyroptosis, while the dysregulated responses include the heat shock response, autophagy, and nuclear factor erythroid-2-related factor 2 signaling. Insulin target cells also produce metabolites that exacerbate cellular stress generation both locally and systemically, partly through recruitment and activation of myeloid cells which sustain a state of chronic inflammation. Thus, insulin resistance may be prevented or attenuated by multiple approaches targeting the different cellular stresses and stress responses.
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Affiliation(s)
- Arnold N. Onyango
- Department of Food Science and Technology, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000, Nairobi 00200, Kenya
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50
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Kowluru A, Kowluru RA. RACking up ceramide-induced islet β-cell dysfunction. Biochem Pharmacol 2018; 154:161-169. [PMID: 29715450 DOI: 10.1016/j.bcp.2018.04.026] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 04/27/2018] [Indexed: 12/20/2022]
Abstract
The International Diabetes Federation predicts that by 2045 the number of individuals afflicted with diabetes will increase to 629 million. Furthermore, ∼352 million individuals with impaired glucose tolerance are at increased risk for developing diabetes. Several mechanisms have been proposed for the onset of metabolic dysfunction and demise of the islet β-cell leading to the pathogenesis of diabetes. It is widely accepted that the onset of type 2 diabetes is due to an intricate interplay between genetic expression of the disease and a multitude of factors including increased oxidative and endoplasmic reticulum stress consequential to glucolipotoxicity and inflammation. Compelling experimental evidence from in vitro and in vivo studies implicates intracellular generation of ceramide (CER), a biologically-active sphingolipid, as a trigger in the onset of β-cell demise under above pathological conditions. Recent pharmacological and molecular biological evidence affirms regulatory roles for Ras-related C3 botulinum toxin substrate 1 (Rac1), a small G protein, in the islet β-cell function in health and diabetes. In this Commentary, we overviewed the emerging evidence implicating potential cross-talk between Rac1 and ceramide signaling pathways in the onset of metabolic dysregulation of the islet β-cell culminating in impaired physiological insulin secretion, loss of β-cell mass and the onset of diabetes. Further, we propose a model depicting contributory roles of defective protein lipidation (prenylation) pathway in the induction of metabolic defects in the β-cell under metabolic stress conditions. Potential avenues for the identification of novel therapeutic targets for the prevention/treatment of diabetes and its associated complications are highlighted.
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Affiliation(s)
- Anjaneyulu Kowluru
- Biomedical Research Service, John D. Dingell VA Medical Center, Wayne State University, Detroit, MI 48201, USA; Department of Pharmaceutical Sciences, Wayne State University, Detroit, MI 48201, USA.
| | - Renu A Kowluru
- Department of Ophthalmology and Anatomy and Cell Biology, Wayne State University, Detroit, MI 48201, USA
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