401
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Cullberg KB, Larsen JØ, Pedersen SB, Richelsen B. Effects of LPS and dietary free fatty acids on MCP-1 in 3T3-L1 adipocytes and macrophages in vitro. Nutr Diabetes 2014; 4:e113. [PMID: 24662749 PMCID: PMC3974034 DOI: 10.1038/nutd.2014.10] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 01/23/2014] [Accepted: 02/07/2014] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND High levels of free fatty acids (FFA) have been suggested to be one of the underlying mechanisms for adipose tissue (AT) inflammation and dysfunction in obesity. Human AT produces several adipokines including monocyte chemoattractant protein-1 (MCP-1), which are involved in the pathogenesis of obesity-mediated inflammation. OBJECTIVE In this study, we investigated the effects of lipopolysaccharide (LPS) and a panel of dietary FFA on MCP-1 gene and protein expression in adipocytes and macrophages. Furthermore, we investigated whether the effect of LPS and FFA were mediated through the toll-like receptor 4 (TLR4). METHODS 3T3-L1 adipocytes and THP-1 macrophages were incubated for 24 h with the following FFA: monounsaturated fatty acid (oleic acid), saturated fatty acid (palmitic acid) and trans fatty acid (elaidic acid; 500 μM) with and without LPS (2 ng ml(-1)), and MCP-1 and TLR4 mRNA expression and MCP-1 protein secretion was determined. RESULTS The results showed that LPS significantly increased MCP-1 and TLR4 expression and MCP-1 secretion in 3T3-L1 adipocytes, and that the MCP-1 expression was blocked by a TLR4 inhibitor (CLI095). The effects of the various FFA on MCP-1 mRNA expression and protein secretion in the adipocytes showed no significant changes either alone or in combination with LPS. In macrophages, palmitic acid increased MCP-1 mRNA expression by 1.8-fold (P<0.05), but oleic acid and elaidic acid had no effects. CONCLUSIONS In conclusion, in 3T3-L1 adipocyte, the TLR4-agonist, LPS, stimulates the proinflammatory chemokine MCP-1. The different classes of FFA did not induce MCP-1 mRNA expression or protein secretion in the adipocytes, but the saturated FFA, palmitic acid, induced MCP-1 mRNA expression in macrophages, possibly because of the higher expression level of TLR4 in the macrophages than the adipocytes. Our results indicate that FFA may induce AT inflammation through proinflammatory stimulation of macrophages.
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Affiliation(s)
- K B Cullberg
- Department of Endocrinology and Internal Medicine, MEA, THG, Aarhus University Hospital, Aarhus C, Denmark
| | - J Ø Larsen
- Department of Endocrinology and Internal Medicine, MEA, THG, Aarhus University Hospital, Aarhus C, Denmark
| | - S B Pedersen
- Department of Endocrinology and Internal Medicine, MEA, THG, Aarhus University Hospital, Aarhus C, Denmark
| | - B Richelsen
- Department of Endocrinology and Internal Medicine, MEA, THG, Aarhus University Hospital, Aarhus C, Denmark
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402
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Bosma M. Lipid homeostasis in exercise. Drug Discov Today 2014; 19:1019-23. [PMID: 24632001 DOI: 10.1016/j.drudis.2014.03.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 03/06/2014] [Indexed: 01/08/2023]
Abstract
Fatty acids (FA) are essential energy substrates during endurance exercise. In addition to systemic supply, intramyocellular neutral lipids form an important source of FA for the working muscle. Endurance exercise training is associated with an increased reliance on lipids as a fuel source, has systemic lipid-lowering effects and results in a remodeling of skeletal muscle lipid metabolism toward increased oxidation, neutral lipid storage and turnover. Interestingly, recent studies have indicated common exercise-induced regulatory pathways for genes involved in skeletal muscle mitochondrial oxidative metabolism and lipid droplet (LD) dynamics. In this review, I discuss lipid homeostasis during acute exercise and adaptations in lipid metabolism upon exercise training in the light of recent advances in the field.
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Affiliation(s)
- Madeleen Bosma
- Department of Cell and Molecular Biology, Karolinska Institutet, PO Box 285, SE-171 77 Stockholm, Sweden.
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403
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Sahoo S, Aurich MK, Jonsson JJ, Thiele I. Membrane transporters in a human genome-scale metabolic knowledgebase and their implications for disease. Front Physiol 2014; 5:91. [PMID: 24653705 PMCID: PMC3949408 DOI: 10.3389/fphys.2014.00091] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Accepted: 02/17/2014] [Indexed: 01/18/2023] Open
Abstract
Membrane transporters enable efficient cellular metabolism, aid in nutrient sensing, and have been associated with various diseases, such as obesity and cancer. Genome-scale metabolic network reconstructions capture genomic, physiological, and biochemical knowledge of a target organism, along with a detailed representation of the cellular metabolite transport mechanisms. Since the first reconstruction of human metabolism, Recon 1, published in 2007, progress has been made in the field of metabolite transport. Recently, we published an updated reconstruction, Recon 2, which significantly improved the metabolic coverage and functionality. Human metabolic reconstructions have been used to investigate the role of metabolism in disease and to predict biomarkers and drug targets. Given the importance of cellular transport systems in understanding human metabolism in health and disease, we analyzed the coverage of transport systems for various metabolite classes in Recon 2. We will review the current knowledge on transporters (i.e., their preferred substrates, transport mechanisms, metabolic relevance, and disease association for each metabolite class). We will assess missing coverage and propose modifications and additions through a transport module that is functional when combined with Recon 2. This information will be valuable for further refinements. These data will also provide starting points for further experiments by highlighting areas of incomplete knowledge. This review represents the first comprehensive overview of the transporters involved in central metabolism and their transport mechanisms, thus serving as a compendium of metabolite transporters specific for human metabolic reconstructions.
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Affiliation(s)
- Swagatika Sahoo
- Center for Systems Biology, University of Iceland Reykjavik, Iceland ; Molecular Systems Physiology Group, Luxembourg Centre for Systems Biomedicine, University of Luxembourg Belval, Luxembourg
| | - Maike K Aurich
- Center for Systems Biology, University of Iceland Reykjavik, Iceland ; Molecular Systems Physiology Group, Luxembourg Centre for Systems Biomedicine, University of Luxembourg Belval, Luxembourg
| | - Jon J Jonsson
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Iceland Reykjavik, Iceland ; Department of Genetics and Molecular Medicine, Landspitali, National University Hospital of Iceland Reykjavik, Iceland
| | - Ines Thiele
- Center for Systems Biology, University of Iceland Reykjavik, Iceland ; Molecular Systems Physiology Group, Luxembourg Centre for Systems Biomedicine, University of Luxembourg Belval, Luxembourg
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404
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Sahini N, Borlak J. Recent insights into the molecular pathophysiology of lipid droplet formation in hepatocytes. Prog Lipid Res 2014; 54:86-112. [PMID: 24607340 DOI: 10.1016/j.plipres.2014.02.002] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 02/17/2014] [Accepted: 02/21/2014] [Indexed: 12/11/2022]
Abstract
Triacyglycerols are a major energy reserve of the body and are normally stored in adipose tissue as lipid droplets (LDs). The liver, however, stores energy as glycogen and digested triglycerides in the form of fatty acids. In stressed condition such as obesity, imbalanced nutrition and drug induced liver injury hepatocytes accumulate excess lipids in the form of LDs whose prolonged storage leads to disease conditions most notably non-alcoholic fatty liver disease (NAFLD). Fatty liver disease has become a major health burden with more than 90% of obese, nearly 70% of overweight and about 25% of normal weight patients being affected. Notably, research in recent years has shown LD as highly dynamic organelles for maintaining lipid homeostasis through fat storage, protein sorting and other molecular events studied in adipocytes and other cells of living organisms. This review focuses on the molecular events of LD formation in hepatocytes and the importance of cross talk between different cell types and their signalling in NAFLD as to provide a perspective on molecular mechanisms as well as possibilities for different therapeutic intervention strategies.
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Affiliation(s)
- Nishika Sahini
- Centre for Pharmacology and Toxicology, Hannover Medical School, 30625 Hannover, Germany
| | - Jürgen Borlak
- Centre for Pharmacology and Toxicology, Hannover Medical School, 30625 Hannover, Germany.
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405
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Protein mediated fatty acid uptake: Synergy between CD36/FAT-facilitated transport and acyl-CoA synthetase-driven metabolism. Arch Biochem Biophys 2014; 546:8-18. [DOI: 10.1016/j.abb.2014.01.025] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 01/17/2014] [Accepted: 01/23/2014] [Indexed: 11/21/2022]
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406
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McArdle Disease and Exercise Physiology. BIOLOGY 2014; 3:157-66. [PMID: 24833339 PMCID: PMC4009758 DOI: 10.3390/biology3010157] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 02/19/2014] [Accepted: 02/20/2014] [Indexed: 11/17/2022]
Abstract
McArdle disease (glycogen storage disease Type V; MD) is a metabolic myopathy caused by a deficiency in muscle glycogen phosphorylase. Since muscle glycogen is an important fuel for muscle during exercise, this inborn error of metabolism provides a model for understanding the role of glycogen in muscle function and the compensatory adaptations that occur in response to impaired glycogenolysis. Patients with MD have exercise intolerance with symptoms including premature fatigue, myalgia, and/or muscle cramps. Despite this, MD patients are able to perform prolonged exercise as a result of the “second wind” phenomenon, owing to the improved delivery of extra-muscular fuels during exercise. The present review will cover what this disease can teach us about exercise physiology, and particularly focuses on the compensatory pathways for energy delivery to muscle in the absence of glycogenolysis.
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407
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Trent CM, Yu S, Hu Y, Skoller N, Huggins LA, Homma S, Goldberg IJ. Lipoprotein lipase activity is required for cardiac lipid droplet production. J Lipid Res 2014; 55:645-58. [PMID: 24493834 PMCID: PMC3966699 DOI: 10.1194/jlr.m043471] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The rodent heart accumulates TGs and lipid droplets during fasting. The sources of heart lipids could be either FFAs liberated from adipose tissue or FAs from lipoprotein-associated TGs via the action of lipoprotein lipase (LpL). Because circulating levels of FFAs increase during fasting, it has been assumed that albumin transported FFAs are the source of lipids within heart lipid droplets. We studied mice with three genetic mutations: peroxisomal proliferator-activated receptor α deficiency, cluster of differentiation 36 (CD36) deficiency, and heart-specific LpL deletion. All three genetically altered groups of mice had defective accumulation of lipid droplet TGs. Moreover, hearts from mice treated with poloxamer 407, an inhibitor of lipoprotein TG lipolysis, also failed to accumulate TGs, despite increased uptake of FFAs. TG storage did not impair maximal cardiac function as measured by stress echocardiography. Thus, LpL hydrolysis of circulating lipoproteins is required for the accumulation of lipids in the heart of fasting mice.
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Affiliation(s)
- Chad M Trent
- Division of Preventive Medicine and Nutrition, Columbia University College of Physicians and Surgeons, New York, NY 10032
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408
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Geerling JJ, Boon MR, Kooijman S, Parlevliet ET, Havekes LM, Romijn JA, Meurs IM, Rensen PCN. Sympathetic nervous system control of triglyceride metabolism: novel concepts derived from recent studies. J Lipid Res 2014; 55:180-9. [PMID: 24285857 PMCID: PMC3886657 DOI: 10.1194/jlr.r045013] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 11/27/2013] [Indexed: 12/16/2022] Open
Abstract
Important players in triglyceride (TG) metabolism include the liver (production), white adipose tissue (WAT) (storage), heart and skeletal muscle (combustion to generate ATP), and brown adipose tissue (BAT) (combustion toward heat), the collective action of which determine plasma TG levels. Interestingly, recent evidence points to a prominent role of the hypothalamus in TG metabolism through innervating the liver, WAT, and BAT mainly via sympathetic branches of the autonomic nervous system. Here, we review the recent findings in the area of sympathetic control of TG metabolism. Various neuronal populations, such as neuropeptide Y (NPY)-expressing neurons and melanocortin-expressing neurons, as well as peripherally produced hormones (i.e., GLP-1, leptin, and insulin), modulate sympathetic outflow from the hypothalamus toward target organs and thereby influence peripheral TG metabolism. We conclude that sympathetic stimulation in general increases lipolysis in WAT, enhances VLDL-TG production by the liver, and increases the activity of BAT with respect to lipolysis of TG, followed by combustion of fatty acids toward heat. Moreover, the increased knowledge about the involvement of the neuroendocrine system in TG metabolism presented in this review offers new therapeutic options to fight hypertriglyceridemia by specifically modulating sympathetic nervous system outflow toward liver, BAT, or WAT.
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Affiliation(s)
- Janine J. Geerling
- Departments of Endocrinology and Metabolic Diseases, Leiden University Medical Center, Leiden, The Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Mariëtte R. Boon
- Departments of Endocrinology and Metabolic Diseases, Leiden University Medical Center, Leiden, The Netherlands
| | - Sander Kooijman
- Departments of Endocrinology and Metabolic Diseases, Leiden University Medical Center, Leiden, The Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Edwin T. Parlevliet
- Departments of Endocrinology and Metabolic Diseases, Leiden University Medical Center, Leiden, The Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
- Department of Medicine, Academic Medical Center, University of Amsterdam, The Netherlands
| | - Louis M. Havekes
- Departments of Endocrinology and Metabolic Diseases, Leiden University Medical Center, Leiden, The Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
- Gaubius Laboratory, Netherlands Organization for Applied Scientific Research - Metabolic Health Research, Leiden, The Netherlands
| | - Johannes A. Romijn
- Department of Medicine, Academic Medical Center, University of Amsterdam, The Netherlands
| | - Illiana M. Meurs
- Departments of Endocrinology and Metabolic Diseases, Leiden University Medical Center, Leiden, The Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Patrick C. N. Rensen
- Departments of Endocrinology and Metabolic Diseases, Leiden University Medical Center, Leiden, The Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
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409
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Turner N, Cooney GJ, Kraegen EW, Bruce CR. Fatty acid metabolism, energy expenditure and insulin resistance in muscle. J Endocrinol 2014; 220:T61-79. [PMID: 24323910 DOI: 10.1530/joe-13-0397] [Citation(s) in RCA: 133] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Fatty acids (FAs) are essential elements of all cells and have significant roles as energy substrates, components of cellular structure and signalling molecules. The storage of excess energy intake as fat in adipose tissue is an evolutionary advantage aimed at protecting against starvation, but in much of today's world, humans are faced with an unlimited availability of food, and the excessive accumulation of fat is now a major risk for human health, especially the development of type 2 diabetes (T2D). Since the first recognition of the association between fat accumulation, reduced insulin action and increased risk of T2D, several mechanisms have been proposed to link excess FA availability to reduced insulin action, with some of them being competing or contradictory. This review summarises the evidence for these mechanisms in the context of excess dietary FAs generating insulin resistance in muscle, the major tissue involved in insulin-stimulated disposal of blood glucose. It also outlines potential problems with models and measurements that may hinder as well as help improve our understanding of the links between FAs and insulin action.
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Affiliation(s)
- Nigel Turner
- Department of Pharmacology School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia Diabetes and Obesity Division, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, New South Wales 2010, Australia St Vincent's Clinical School, University of New South Wales, Sydney, New South Wales, Australia Department of Physiology, Monash University, Clayton, Victoria 3800, Australia
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410
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van Oort MM, Drost R, Janβen L, Van Doorn JM, Kerver J, Van der Horst DJ, Luiken JJFP, Rodenburg KCW. Each of the four intracellular cysteines of CD36 is essential for insulin- or AMP-activated protein kinase-induced CD36 translocation. Arch Physiol Biochem 2014; 120:40-9. [PMID: 24377880 DOI: 10.3109/13813455.2013.876049] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Stimulation of cellular fatty acid uptake by induction of insulin signalling or AMP-kinase (AMPK) activation is due to translocation of the fatty acid-transporter CD36 from intracellular stores to the plasma membrane (PM). For investigating the role of the four Cys-residues within CD36's cytoplasmic tails in CD36 translocation, we constructed CHO-cells expressing CD36 mutants in which all four, two, or one of the intracellular Cys were replaced by Ser. Intracellular and PM localization of all mutants was similar to wild-type CD36 (CD36wt). Hence, the four Cys do not regulate sub-cellular CD36 localization. However, in contrast to CD36wt, insulin or AMPK activation failed to induce translocation of any of the mutants, indicating that all four intracellular Cys residues are essential for CD36 translocation. The mechanism of defective translocation of mutant CD36 is unknown, but appears not due to loss of S-palmitoylation of the cytoplasmic tails or to aberrant oligomerization of the mutants.
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Affiliation(s)
- Masja M van Oort
- Division of Endocrinology and Metabolism, Department of Biology and Institute of Biomembranes, Utrecht University , NL-3584 CH Utrecht , The Netherlands and
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411
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Carr SK, Chen JH, Cooper WN, Constância M, Yeo GSH, Ozanne SE. Maternal diet amplifies the hepatic aging trajectory of Cidea in male mice and leads to the development of fatty liver. FASEB J 2014; 28:2191-201. [PMID: 24481968 DOI: 10.1096/fj.13-242727] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The importance of the early environment on long-term heath and life span is well documented. However, the molecular mechanisms mediating these effects remain poorly understood. Male offspring from a maternal protein restriction model, in which animals are exposed to a low-protein diet while in utero and then are cross-fostered to normally fed dams, demonstrate low birth weight, catch-up growth, and reduced life span (recuperated offspring). In the current study, we used microarray analysis to identify hepatic genes that changed with age. Cell death-inducing DNA fragmentation factor, α subunit-like effector A (Cidea), a transcriptional coactivator that has been implicated in lipid accumulation demonstrated one of the largest age-associated increases in expression (200-fold, P<0.001). This increase was exaggerated ∼3-fold in recuperated offspring. These demonstrated increased hepatic lipid accumulation, higher levels of transcription factors important in lipid regulation, and greater oxidative stress. In vitro analysis revealed that Cidea expression was regulated by oxidative stress and DNA methylation. These findings suggest that maternal diet modulates the age-associated changes in Cidea expression through several mechanisms. This expression affects hepatic lipid metabolism in these animals and thus provides a mechanism by which maternal diet can contribute to the metabolic health and ultimately the life span of the offspring.
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Affiliation(s)
- Sarah K Carr
- 1University of Cambridge Metabolic Research Laboratories, MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Level 4, Box 289, Addenbrooke's Hospital, Cambridge CB2 OQQ, UK.
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412
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Khalifeh-Soltani A, McKleroy W, Sakuma S, Cheung YY, Tharp K, Qiu Y, Turner SM, Chawla A, Stahl A, Atabai K. Mfge8 promotes obesity by mediating the uptake of dietary fats and serum fatty acids. Nat Med 2014; 20:175-83. [PMID: 24441829 DOI: 10.1038/nm.3450] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 12/11/2013] [Indexed: 12/14/2022]
Abstract
Fatty acids are integral mediators of energy storage, membrane formation and cell signaling. The pathways that orchestrate uptake of fatty acids remain incompletely understood. Expression of the integrin ligand Mfge8 is increased in human obesity and in mice on a high-fat diet, but its role in obesity is unknown. We show here that Mfge8 promotes the absorption of dietary triglycerides and the cellular uptake of fatty acid and that Mfge8-deficient (Mfge8(-/-)) mice are protected from diet-induced obesity, steatohepatitis and insulin resistance. Mechanistically, we found that Mfge8 coordinates fatty acid uptake through αvβ3 integrin- and αvβ5 integrin-dependent phosphorylation of Akt by phosphatidylinositide-3 kinase and mTOR complex 2, leading to translocation of Cd36 and Fatp1 from cytoplasmic vesicles to the cell surface. Collectively, our results imply a role for Mfge8 in regulating the absorption and storage of dietary fats, as well as in the development of obesity and its complications.
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Affiliation(s)
- Amin Khalifeh-Soltani
- 1] Cardiovascular Research Institute, University of California, San Francisco, San Francisco, California, USA. [2] Lung Biology Center, University of California, San Francisco, San Francisco, California, USA. [3] Department of Medicine, University of California, San Francisco, San Francisco, California, USA
| | - William McKleroy
- 1] Cardiovascular Research Institute, University of California, San Francisco, San Francisco, California, USA. [2] Lung Biology Center, University of California, San Francisco, San Francisco, California, USA. [3] Department of Medicine, University of California, San Francisco, San Francisco, California, USA
| | - Stephen Sakuma
- 1] Cardiovascular Research Institute, University of California, San Francisco, San Francisco, California, USA. [2] Lung Biology Center, University of California, San Francisco, San Francisco, California, USA. [3] Department of Medicine, University of California, San Francisco, San Francisco, California, USA
| | - Yuk Yin Cheung
- 1] Cardiovascular Research Institute, University of California, San Francisco, San Francisco, California, USA. [2] Department of Medicine, University of California, San Francisco, San Francisco, California, USA
| | - Kevin Tharp
- 1] Metabolic Biology, University of California, Berkeley, Berkeley, California, USA. [2] Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, California, USA
| | - Yifu Qiu
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, California, USA
| | | | - Ajay Chawla
- 1] Cardiovascular Research Institute, University of California, San Francisco, San Francisco, California, USA. [2] Department of Medicine, University of California, San Francisco, San Francisco, California, USA. [3] Department of Physiology, University of California, San Francisco, San Francisco, California, USA
| | - Andreas Stahl
- 1] Metabolic Biology, University of California, Berkeley, Berkeley, California, USA. [2] Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, California, USA
| | - Kamran Atabai
- 1] Cardiovascular Research Institute, University of California, San Francisco, San Francisco, California, USA. [2] Lung Biology Center, University of California, San Francisco, San Francisco, California, USA. [3] Department of Medicine, University of California, San Francisco, San Francisco, California, USA
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413
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Abstract
Lactation physiology is a process that is only partly understood. Proteomics techniques have shown to be useful to help advance the knowledge on lactation physiology in human and rodent species but have not been used as major tools for dairy cows, except for mastitis. In this paper, advanced non-targeted proteomics techniques (Filter aided sample preparation and NanoLC-Orbitrap-MS/MS) were applied to study the milk fat globule membrane and milk serum fraction, resulting in the identification of 246 proteins. Of these, 23 transporters and enzymes were related to lipid synthesis and secretion in mammary gland and their functions are discussed in detail. The identification of these intracellular transporters and enzymes in milk provides a possibility of using milk itself to study lipid synthesis and secretion pathways. This full-scale scan of milk proteins by using non-targeted proteomic analysis helps to reveal the important proteins involved in lipid synthesis and secretion for further examination in targeted studies.
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414
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Hagberg C, Mehlem A, Falkevall A, Muhl L, Eriksson U. Endothelial fatty acid transport: role of vascular endothelial growth factor B. Physiology (Bethesda) 2014; 28:125-34. [PMID: 23455771 DOI: 10.1152/physiol.00042.2012] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Dietary lipids present in the circulation have to be transported through the vascular endothelium to be utilized by tissue cells, a vital mechanism that is still poorly understood. Vascular endothelial growth factor B (VEGF-B) regulates this process by controlling the expression of endothelial fatty acid transporter proteins (FATPs). Here, we summarize research on the role of the vascular endothelium in nutrient transport, with emphasis on VEGF-B signaling.
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415
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Draczkowski P, Matosiuk D, Jozwiak K. Isothermal titration calorimetry in membrane protein research. J Pharm Biomed Anal 2014; 87:313-25. [DOI: 10.1016/j.jpba.2013.09.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2013] [Revised: 08/28/2013] [Accepted: 09/03/2013] [Indexed: 01/18/2023]
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416
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Lundsgaard AM, Kiens B. Gender differences in skeletal muscle substrate metabolism - molecular mechanisms and insulin sensitivity. Front Endocrinol (Lausanne) 2014; 5:195. [PMID: 25431568 PMCID: PMC4230199 DOI: 10.3389/fendo.2014.00195] [Citation(s) in RCA: 169] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 10/30/2014] [Indexed: 12/23/2022] Open
Abstract
It has become increasingly apparent that substrate metabolism is subject to gender-specific regulation, and the aim of this review is to outline the available evidence of molecular gender differences in glucose and lipid metabolism of skeletal muscle. Female sex has been suggested to have a favorable effect on glucose homeostasis, and the available evidence from hyperinsulinemic-euglycemic clamp studies is summarized to delineate whether there is a gender difference in whole-body insulin sensitivity and in particular insulin-stimulated glucose uptake of skeletal muscle. Whether an eventual higher insulin sensitivity of female skeletal muscle can be related to gender-specific regulation of molecular metabolism will be topic for discussion. Gender differences in muscle fiber type distribution and substrate availability to and in skeletal muscle are highly relevant for substrate metabolism in men and women. In particular, the molecular machinery for glucose and fatty acid oxidative and storage capacities in skeletal muscle and its implications for substrate utilization during metabolic situations of daily living are discussed, emphasizing their relevance for substrate choice in the fed and fasted state, and during periods of physical activity and recovery. Together, handling of carbohydrate and lipids and regulation of their utilization in skeletal muscle have implications for whole-body glucose homeostasis in men and women. 17-β estradiol is the most important female sex hormone, and the identification of estradiol receptors in skeletal muscle has opened for a role in regulation of substrate metabolism. Also, higher levels of circulating adipokines as adiponectin and leptin in women and their implications for muscle metabolism will be considered.
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Affiliation(s)
- Anne-Marie Lundsgaard
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, August Krogh Centre, University of Copenhagen, Copenhagen, Denmark
| | - Bente Kiens
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, August Krogh Centre, University of Copenhagen, Copenhagen, Denmark
- *Correspondence: Bente Kiens, Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, August Krogh Centre, University of Copenhagen, Universitetsparken 13, Copenhagen 2100, Denmark e-mail:
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417
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Liu S, Brown JD, Stanya KJ, Homan E, Leidl M, Inouye K, Bhargava P, Gangl MR, Dai L, Hatano B, Hotamisligil GS, Saghatelian A, Plutzky J, Lee CH. A diurnal serum lipid integrates hepatic lipogenesis and peripheral fatty acid use. Nature 2013; 502:550-4. [PMID: 24153306 PMCID: PMC4141623 DOI: 10.1038/nature12710] [Citation(s) in RCA: 165] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 09/19/2013] [Indexed: 12/17/2022]
Abstract
Food intake increases the activity of hepatic de novo lipogenesis, which mediates the conversion of glucose to fats for storage or utilization. In mice, this program follows a circadian rhythm that peaks with nocturnal feeding1,2 and is repressed by Rev-erbα/β and an HDAC3-containing complex3–5 during the day. The transcriptional activators controlling rhythmic lipid synthesis in the dark cycle remain poorly defined. Disturbances in hepatic lipogenesis are also associated with systemic metabolic phenotypes6–8, suggesting that lipogenesis in the liver communicates with peripheral tissues to control energy substrate homeostasis. Here we identify a PPARδ-dependent de novo lipogenic pathway in the liver that modulates fat utilization by muscle via a circulating lipid. The nuclear receptor PPARδ controls diurnal expression of lipogenic genes in the dark/feeding cycle. Liver-specific PPARδ activation increases, while hepatocyte-Ppard deletion reduces, muscle fatty acid (FA) uptake. Unbiased metabolite profiling identifies PC(18:0/18:1), or 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC), as a serum lipid regulated by diurnal hepatic PPARδ activity. PC(18:0/18:1) reduces postprandial lipid levels and increases FA utilization through muscle PPARα. High fat feeding diminishes rhythmic production of PC(18:0/18:1), whereas PC(18:0/18:1) administration in db/db mice improves metabolic homeostasis. These findings reveal an integrated regulatory circuit coupling lipid synthesis in the liver to energy utilization in muscle by coordinating the activity of two closely related nuclear receptors. These data implicate alterations in diurnal hepatic PPARδ-PC(18:0/18:1) signaling in metabolic disorders including obesity.
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Affiliation(s)
- Sihao Liu
- 1] Department of Genetics and Complex Diseases, Division of Biological Sciences, Harvard School of Public Health, 665 Huntington Avenue, Boston, Massachusetts 02115, USA [2]
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418
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Sisignano M, Bennett DLH, Geisslinger G, Scholich K. TRP-channels as key integrators of lipid pathways in nociceptive neurons. Prog Lipid Res 2013; 53:93-107. [PMID: 24287369 DOI: 10.1016/j.plipres.2013.11.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 11/12/2013] [Accepted: 11/14/2013] [Indexed: 12/22/2022]
Abstract
TRP-channels are the most prominent family of ligand-gated ion channels for pain perception. In sensory neurons, TRPV1-V4, TRPA1 and TRPM8 are expressed and are responsible for the conversion of external stimuli to painful sensations. Under pathophysiological conditions, excessive activity of TRP-channels leads to mechanical allodynia and thermal hyperalgesia. Among the endogenous TRP-channel sensitizers, activators and inhibitors, more than 50 arachidonic acid- and linoleic acid-metabolites from the COX-, LOX- and CYP-pathways, as well as lysophospholipids and isoprenoids can be found. As a consequence, these lipids represent the vast majority of endogenous TRP-channel modulators in sensory neurons. Although the precise mechanisms of TRP-channel modulation by most lipids are still unknown, it became clear that lipids can either bind directly to the target TRP-channel or modulate TRP-channels indirectly by activating G-protein coupled receptors. Thus, TRP-channels seem to be key sensors for lipids, integrating and interpreting incoming signals from the different metabolic lipid pathways. Here, we discuss the specific properties of the currently known endogenous lipid-derived TRP-channel modulators concerning their ability to activate or inhibit TRP-channels, the molecular mechanisms of lipid/TRP-channel interactions and specific TRP-regulatory characteristics of the individual lipid families.
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Affiliation(s)
- Marco Sisignano
- Institute of Clinical Pharmacology, Pharmazentrum Frankfurt/ZAFES, University Hospital of the Goethe-University, D-60590 Frankfurt am Main, Germany
| | - David L H Bennett
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
| | - Gerd Geisslinger
- Institute of Clinical Pharmacology, Pharmazentrum Frankfurt/ZAFES, University Hospital of the Goethe-University, D-60590 Frankfurt am Main, Germany
| | - Klaus Scholich
- Institute of Clinical Pharmacology, Pharmazentrum Frankfurt/ZAFES, University Hospital of the Goethe-University, D-60590 Frankfurt am Main, Germany.
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Lee EJ, Kamli MR, Pokharel S, Malik A, Tareq KMA, Roouf Bhat A, Park HB, Lee YS, Kim S, Yang B, Young Chung K, Choi I. Expressed sequence tags for bovine muscle satellite cells, myotube formed-cells and adipocyte-like cells. PLoS One 2013; 8:e79780. [PMID: 24224006 PMCID: PMC3818215 DOI: 10.1371/journal.pone.0079780] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2013] [Accepted: 09/25/2013] [Indexed: 12/25/2022] Open
Abstract
Background Muscle satellite cells (MSCs) represent a devoted stem cell population that is responsible for postnatal muscle growth and skeletal muscle regeneration. An important characteristic of MSCs is that they encompass multi potential mesenchymal stem cell activity and are able to differentiate into myocytes and adipocytes. To achieve a global view of the genes differentially expressed in MSCs, myotube formed-cells (MFCs) and adipocyte-like cells (ALCs), we performed large-scale EST sequencing of normalized cDNA libraries developed from bovine MSCs. Results A total of 24,192 clones were assembled into 3,333 clusters, 5,517 singletons and 3,842contigs. Functional annotation of these unigenes revealed that a large portion of the differentially expressed genes are involved in cellular and signaling processes. Database for Annotation, Visualization and Integrated Discovery (DAVID) functional analysis of three subsets of highly expressed gene lists (MSC233, MFC258, and ALC248) highlighted some common and unique biological processes among MSC, MFC and ALC. Additionally, genes that may be specific to MSC, MFC and ALC are reported here, and the role of dimethylargininedimethylaminohydrolase2 (DDAH2) during myogenesis and hemoglobinsubunitalpha2 (HBA2) during transdifferentiation in C2C12 were assayed as a case study. DDAH2 was up-regulated during myognesis and knockdown of DDAH2 by siRNA significantly decreased myogenin (MYOG) expression corresponding with the slight change in cell morphology. In contrast, HBA2 was up-regulated during ALC formation and resulted in decreased intracellular lipid accumulation and CD36 mRNA expression upon knockdown assay. Conclusion In this study, a large number of EST sequences were generated from the MSC, MFC and ALC. Overall, the collection of ESTs generated in this study provides a starting point for the identification of novel genes involved in MFC and ALC formation, which in turn offers a fundamental resource to enable better understanding of the mechanism of muscle differentiation and transdifferentiation.
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Affiliation(s)
- Eun Ju Lee
- School of Biotechnology, Yeungnam University, Gyeongsan, Republic of Korea
- Bovine Genome Resources Bank, Yeungnam University, Gyeongsan, Republic of Korea
| | - Majid Rasool Kamli
- School of Biotechnology, Yeungnam University, Gyeongsan, Republic of Korea
| | - Smritee Pokharel
- School of Biotechnology, Yeungnam University, Gyeongsan, Republic of Korea
| | - Adeel Malik
- School of Biotechnology, Yeungnam University, Gyeongsan, Republic of Korea
| | - K. M. A. Tareq
- School of Biotechnology, Yeungnam University, Gyeongsan, Republic of Korea
| | - Abdul Roouf Bhat
- School of Biotechnology, Yeungnam University, Gyeongsan, Republic of Korea
| | - Hee-Bok Park
- Institute of Agriculture and Life Sciences, Gyeongsang National University, Jinju, Republic of Korea
| | - Yong Seok Lee
- Bovine Genome Resources Bank, Yeungnam University, Gyeongsan, Republic of Korea
- Department of Life Science and Biotechnology, College of Natural Sciences, Soonchunhyang University, Asan, Korea
| | - SangHoon Kim
- Department of Biology, Kyung Hee University, Seoul, Republic of Korea
| | - Bohsuk Yang
- Hanwoo Experiment Station, National Institute of Animal Science, RDA, Pyeongchang, Seoul, Republic of Korea
| | - Ki Young Chung
- Hanwoo Experiment Station, National Institute of Animal Science, RDA, Pyeongchang, Seoul, Republic of Korea
- * E-mail: (IC); (KYC)
| | - Inho Choi
- School of Biotechnology, Yeungnam University, Gyeongsan, Republic of Korea
- Bovine Genome Resources Bank, Yeungnam University, Gyeongsan, Republic of Korea
- * E-mail: (IC); (KYC)
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Xu J, Donepudi AC, Moscovitz JE, Slitt AL. Keap1-knockdown decreases fasting-induced fatty liver via altered lipid metabolism and decreased fatty acid mobilization from adipose tissue. PLoS One 2013; 8:e79841. [PMID: 24224011 PMCID: PMC3817107 DOI: 10.1371/journal.pone.0079841] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 09/25/2013] [Indexed: 01/10/2023] Open
Abstract
AIMS The purpose of this study was to determine whether Nrf2 activation, via Keap1-knockdown (Keap1-KD), regulates lipid metabolism and mobilization induced by food deprivation (e.g. fasting). METHODS AND RESULTS Male C57BL/6 (WT) and Keap1-KD mice were either fed ad libitum or food deprived for 24 hours. After fasting, WT mice exhibited a marked increase in hepatic lipid accumulation, but Keap1-KD mice had an attenuated increase of lipid accumulation, along with reduced expression of lipogenic genes (acetyl-coA carboxylase, stearoyl-CoA desaturase-1, and fatty acid synthase) and reduced expression of genes related to fatty acid transport, such as fatty acid translocase/CD36 (CD36) and Fatty acid transport protein (FATP) 2, which may attribute to the reduced induction of Peroxisome proliferator-activated receptor (Ppar) α signaling in the liver. Additionally, enhanced Nrf2 activity by Keap1-KD increased AMP-activated protein kinase (AMPK) phosphorylation in liver. In white adipose tissue, enhanced Nrf2 activity did not change the lipolysis rate by fasting, but reduced expression of fatty acid transporters--CD36 and FATP1, via a PPARα-dependent mechanism, which impaired fatty acid transport from white adipose tissue to periphery circulation system, and resulted in increased white adipose tissue fatty acid content. Moreover, enhanced Nrf2 activity increased glucose tolerance and Akt phosphorylation levels upon insulin administration, suggesting Nrf2 signaling pathway plays a key role in regulating insulin signaling and enhanced insulin sensitivity in skeletal muscle. CONCLUSION Enhanced Nrf2 activity via Keap1-KD decreased fasting-induced steatosis, pointing to an important function of Nrf2 on lipid metabolism under the condition of nutrient deprivation.
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Affiliation(s)
- Jialin Xu
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island, United States of America
- Institute of Biochemistry and Molecular Biology, College of Life and Health Sciences, Northeastern University, Shenyang, P. R. China
| | - Ajay C. Donepudi
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island, United States of America
| | - Jamie E. Moscovitz
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island, United States of America
| | - Angela L. Slitt
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island, United States of America
- * E-mail:
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421
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Wang TY, Liu M, Portincasa P, Wang DQH. New insights into the molecular mechanism of intestinal fatty acid absorption. Eur J Clin Invest 2013; 43:1203-23. [PMID: 24102389 PMCID: PMC3996833 DOI: 10.1111/eci.12161] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2013] [Accepted: 08/20/2013] [Indexed: 01/05/2023]
Abstract
BACKGROUND Dietary fat is one of the most important energy sources of all the nutrients. Fatty acids, stored as triacylglycerols (also called triglycerides) in the body, are an important reservoir of stored energy and derived primarily from animal fats and vegetable oils. DESIGN Although the molecular mechanisms for the transport of water-insoluble amphipathic fatty acids across cell membranes have been debated for many years, it is now believed that the dominant means for intestinal fatty acid uptake is via membrane-associated fatty acid-binding proteins, that is, fatty acid transporters on the apical membrane of enterocytes. RESULTS These findings indicate that intestinal fatty acid absorption is a multistep process that is regulated by multiple genes at the enterocyte level, and intestinal fatty acid absorption efficiency could be determined by factors influencing intraluminal fatty acid molecules across the brush border membrane of enterocytes. To facilitate research on intestinal, hepatic and plasma triacylglycerol metabolism, it is imperative to establish standard protocols for precisely and accurately measuring the efficiency of intestinal fatty acid absorption in humans and animal models. In this review, we will discuss the chemical structure and nomenclature of fatty acids and summarize recent progress in investigating the molecular mechanisms underlying the intestinal absorption of fatty acids, with a particular emphasis on the physical chemistry of intestinal lipids and the molecular physiology of intestinal fatty acid transporters. CONCLUSIONS A better understanding of the molecular mechanism of intestinal fatty acid absorption should lead to novel approaches to the treatment and the prevention of fatty acid-related metabolic diseases that are prevalent worldwide.
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Affiliation(s)
- Tony Y Wang
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Saint Louis University School of Medicine, St. Louis, MO, USA; Department of Biomedical Engineering, Washington University, St. Louis, MO, USA
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Vaillant F, Lauzier B, Poirier I, Gélinas R, Rivard ME, Robillard Frayne I, Thorin E, Des Rosiers C. Mouse strain differences in metabolic fluxes and function of ex vivo working hearts. Am J Physiol Heart Circ Physiol 2013; 306:H78-87. [PMID: 24186097 DOI: 10.1152/ajpheart.00465.2013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In mice, genetic background is known to influence various parameters, including cardiac function. Its impact on cardiac energy substrate metabolism-a factor known to be closely related to function and contributes to disease development-is, however, unclear. This was examined in this study. In commonly used control mouse substrains SJL/JCrNTac, 129S6/SvEvTac, C57Bl/6J, and C57Bl/6NCrl, we assessed the functional and metabolic phenotypes of 3-mo-old working mouse hearts perfused ex vivo with physiological concentrations of (13)C-labeled carbohydrates (CHO) and a fatty acid (FA). Marked variations in various functional and metabolic flux parameters were observed among all mouse substrains, although the pattern observed differed for these parameters. For example, among all strains, C57Bl/6NCrl hearts had a greater cardiac output (+1.7-fold vs. SJL/JCrNTac and C57Bl/6J; P < 0.05), whereas at the metabolic level, 129S6/SvEvTac hearts stood out by displaying (vs. all 3 strains) a striking shift from exogenous FA (~-3.5-fold) to CHO oxidation as well as increased glycolysis (+1.7-fold) and FA incorporation into triglycerides (+2-fold). Correlation analyses revealed, however, specific linkages between 1) glycolysis, FA oxidation, and pyruvate metabolism and 2) cardiac work, oxygen consumption with heart rate, respectively. This implies that any genetically determined factors affecting a given metabolic flux parameter may impact on the associated functional parameters. Our results emphasize the importance of selecting the appropriate control strain for cardiac metabolic studies using transgenic mice, a factor that has often been neglected. Understanding the molecular mechanisms underlying the diversity of strain-specific cardiac metabolic and functional profiles, particularly the 129S6/SvEvTac, may ultimately disclose new specific metabolic targets for interventions in heart disease.
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Affiliation(s)
- Fanny Vaillant
- Departments of Nutrition, Montreal Heart Institute and Université de Montréal, Montreal, Quebec, Canada; and
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423
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Igarashi M, Chang L, Ma K, Rapoport SI. Kinetics of eicosapentaenoic acid in brain, heart and liver of conscious rats fed a high n-3 PUFA containing diet. Prostaglandins Leukot Essent Fatty Acids 2013; 89:403-12. [PMID: 24209500 PMCID: PMC5861380 DOI: 10.1016/j.plefa.2013.09.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 09/07/2013] [Accepted: 09/07/2013] [Indexed: 01/06/2023]
Abstract
Eicosapentaenoic acid (EPA, 20:5n-3), a precursor of docosahexaenoic acid (DHA), may benefit cardiovascular and brain health. Quantifying EPA's in vivo kinetics might elucidate these effects. [1-(14)C]EPA was infused i.v. for 5min in unanesthetized male rats fed a standard EPA-DHA diet. Plasma and microwaved tissue were analyzed. Kinetic parameters were calculated using our compartmental model. At 5min, 31-48% of labeled EPA in brain and heart was oxidized, 7% in liver. EPA incorporation rates from brain and liver precursor EPA-CoA pools into lipids, mainly phospholipids, were 36 and 2529nmol/s/g×10(-4), insignificant for heart. Deacylation-reacylation half-lives were 22h and 38-128min. Conversion rates to DHA equaled 0.65 and 25.1nmol/s/g×10(-4), respectively. The low brain concentration and incorporation rate and high oxidation of EPA suggest that, if EPA has a beneficial effect in brain, it might result from its suppression of peripheral inflammation and hepatic conversion to bioactive DHA.
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Affiliation(s)
- Miki Igarashi
- Brain Physiology and Metabolism Section, National Institute on Aging, National Institutes of Health, Building 9, Room 1S126, Bethesda, MD 20892, USA.
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424
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Geetha R, Yogalakshmi B, Sreeja S, Bhavani K, Anuradha CV. Troxerutin suppresses lipid abnormalities in the heart of high-fat–high-fructose diet-fed mice. Mol Cell Biochem 2013; 387:123-34. [DOI: 10.1007/s11010-013-1877-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 10/18/2013] [Indexed: 12/28/2022]
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425
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Gaccioli F, White V, Capobianco E, Powell TL, Jawerbaum A, Jansson T. Maternal overweight induced by a diet with high content of saturated fat activates placental mTOR and eIF2alpha signaling and increases fetal growth in rats. Biol Reprod 2013; 89:96. [PMID: 24006279 DOI: 10.1095/biolreprod.113.109702] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The mammalian target of rapamycin (mTOR) and the eukaryotic initiation factor 2 (eIF2) signaling pathways control protein synthesis in response to nutrient availability. Moreover, mTOR is a positive regulator of placental nutrient transport and is involved in the regulation of fetal growth. We hypothesized that maternal overweight, induced by a diet with high saturated fat content, i) up-regulates placental mTOR activity and nutrient transport, resulting in fetal overgrowth; ii) inhibits phosphorylation of eIF2 at its alpha subunit (eIF2alpha); and iii) leads to placental inflammation. Albino Wistar female rats were fed a control or high-saturated-fat (HF) diet for 7 wk before mating and during pregnancy. At gestational day 21, the HF diet significantly increased maternal and fetal triglyceride, leptin, and insulin (but not glucose) levels and maternal and fetal weights, and placental weights trended to increase. Phosphorylated 4EBP1 (T37/46 and S65) was significantly higher, and phosphorylated rpS6 (S235/236) tended to increase, in the placentas of dams fed an HF diet, indicating an activation of mTOR complex 1 (mTORC1). Phosphorylation of AMPK and eIF2alpha was reduced in the HF diet group compared to the control. The expression and activity of placental nutrient transporters and lipoprotein lipase (LPL), as well as the activation of inflammatory pathways, were not altered by the maternal diet. We conclude that maternal overweight induced by an HF diet stimulates mTORC1 activity and decreases eIF2alpha phosphorylation in rat placentas. We speculate that these changes may up-regulate protein synthesis and contribute to placental and fetal overgrowth.
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Affiliation(s)
- Francesca Gaccioli
- Center for Pregnancy and Newborn Research, University of Texas Health Science Center, San Antonio, Texas
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426
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Araújo JR, Correia-Branco A, Ramalho C, Keating E, Martel F. Gestational diabetes mellitus decreases placental uptake of long-chain polyunsaturated fatty acids: involvement of long-chain acyl-CoA synthetase. J Nutr Biochem 2013; 24:1741-50. [DOI: 10.1016/j.jnutbio.2013.03.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 01/31/2013] [Accepted: 03/07/2013] [Indexed: 12/11/2022]
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427
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Tanaka S, Yamazaki T, Asano S, Mitsumoto A, Kobayashi D, Kudo N, Kawashima Y. Increased lipid synthesis and decreased β-oxidation in the liver of SHR/NDmcr-cp (cp/cp) rats, an animal model of metabolic syndrome. Lipids 2013; 48:1115-34. [PMID: 24045975 DOI: 10.1007/s11745-013-3839-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 08/24/2013] [Indexed: 12/19/2022]
Abstract
SHR/NDmcr-cp (cp/cp) rats (SHR/NDcp) are an animal model of metabolic syndrome. A previous study of ours revealed drastic increases in the mass of palmitic (16:0), oleic (18:1n-9), palmitoleic (16:1n-7), cis-vaccenic (18:1n-7) and 5,8,11-eicosatrienoic acids in the liver of SHR/NDcp. However, detailed information on the class of lipid accumulated and the mechanism responsible for the overproduction of the accumulated lipid in the liver was not obtained. This study aimed to characterize the class of lipid accumulated and to explore the mechanism underlying the lipid accumulation in the liver of SHR/NDcp, in comparison with SHR/NDmcr-cp (+/+) (lean hypertensive littermates of SHR/NDcp) and Wistar Kyoto rats. In the liver of SHR/NDcp, de novo synthesis of fatty acids (16:0, 18:1n-9 and 16:1n-7) and triacylglycerol (TAG) synthesis were up-regulated and fatty acid β-oxidation was down-regulated. These perturbations of lipid metabolism caused fat accumulation in hepatocytes and accumulation of TAG, which were enriched with 16:0, 18:1n-9 and 16:1n-7, in the liver of SHR/NDcp. On the other hand, no changes were found in hepatic contents of diacylglycerol and unesterified fatty acid (FFA); among FFA, there were no differences in the hepatic concentrations of unesterified 16:0 and stearic acid between SHR/NDcp and two other groups of rats. Moreover, little change was brought about in the expression of genes responsive to endoplasmic reticulum stress in the liver of SHR/NDcp. These results may reinforce the pathophysiological role of stearoyl-CoA desaturase 1 and fatty acid elongase 6 in the liver of SHR/NDcp.
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Affiliation(s)
- Shizuyo Tanaka
- Faculty of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama, 350-0295, Japan
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Stefanyk LE, Bonen A, Dyck DJ. Fatty acid transport proteins chronically relocate to the transverse-tubules in muscle from obese Zucker rats but are resistant to further insulin-induced translocation. Metabolism 2013; 62:1296-304. [PMID: 23743348 DOI: 10.1016/j.metabol.2013.04.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2013] [Revised: 04/12/2013] [Accepted: 04/29/2013] [Indexed: 12/27/2022]
Abstract
OBJECTIVES Recently, we have demonstrated that FA transport proteins are located within the t-tubule fraction of rodent muscle, and that insulin stimulation causes their translocation to this membrane fraction. Chronic relocation of the FA transport protein FAT/CD36 to the sarcolemma is observed in obese rodents and humans, and correlates with intramuscular lipid accumulation and insulin resistance. It is not known whether in an obese, insulin resistant state FA transporters also chronically relocate to the t-tubules. Furthermore, it is not known whether the insulin-stimulated translocation of the various FA transport proteins to the t-tubules is impaired in insulin resistance. METHODS Sarcolemmal and t-tubule membrane fractions were isolated via differential centrifugation from muscles of lean and obese female Zucker rats during basal or insulin stimulated conditions. FA transport proteins were measured via western blot on both membrane fractions. RESULTS Our results demonstrate that in muscle from insulin resistant Zucker rats, FAT/CD36, FABPpm and FATP1 are all increased on the t-tubules in the basal state (+72%, +120%, and +69%, respectively), potentially contributing to the accumulation of intramuscular lipids. Insulin failed to increase the content of the FA transport proteins on either the t-tubule or sarcolemma above the elevated basal levels, analogous to the well characterized impairment of insulin-stimulated GLUT4 translocation to both membrane domains in obesity. CONCLUSION FA transport proteins chronically relocate to the t-tubule domain in insulin resistant muscle, potentially contributing to lipid accumulation. Further translocation of the FA transport proteins to this domain during insulin stimulation, however, is impaired.
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Affiliation(s)
- Leslie E Stefanyk
- Department of Human Health and Nutritional Science, University of Guelph, Guelph, ON, Canada, N1G 2W1
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Nassir F, Adewole OL, Brunt EM, Abumrad NA. CD36 deletion reduces VLDL secretion, modulates liver prostaglandins, and exacerbates hepatic steatosis in ob/ob mice. J Lipid Res 2013; 54:2988-97. [PMID: 23964120 DOI: 10.1194/jlr.m037812] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Recent findings described the role of CD36-mediated signaling in regulating cellular calcium and the release of various bioactive molecules, including the prostaglandins, neurotransmitters, cholecystokinin, and secretin. Here we document the role of CD36 in the secretion of hepatic VLDL. CD36 deletion resulted in 60% suppression of VLDL output in vivo, and VLDL secretion was reduced in vitro using incubated liver slices. The effect of CD36 deletion was mediated by enhancing formation of hepatic prostaglandins D2, F2, and E2. Treatment of CD36-deficient slices with inhibitors of cyclooxygenases reversed the reduction in triglyceride secretion. We also examined the effect of CD36 deletion on the obesity-associated spontaneous steatosis of the ob/ob mouse that is driven by enhanced de novo lipogenesis. Homozygous ob/ob mice lacking CD36 (ob-CD36⁻/⁻) were generated and studied for hepatic triglyceride accumulation and VLDL secretion. Livers of ob/ob mice were steatotic as expected and had 5-fold more CD36 on Kupffer cells and hepatocytes. CD36 deletion exacerbated the steatosis by impairing hepatic triglyceride and apoB secretion through increasing prostaglandin levels. These findings suggest an unappreciated role of CD36 in regulating VLDL secretion, which might have relevance to some forms of fatty liver. They provide insight into the association reported in humans between CD36 protein expression and serum levels of apoB and VLDL particle number.
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Affiliation(s)
- Fatiha Nassir
- Department of Medicine Washington University School of Medicine, St. Louis, MO 63110
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Ceccon A, D'Onofrio M, Zanzoni S, Longo DL, Aime S, Molinari H, Assfalg M. NMR investigation of the equilibrium partitioning of a water-soluble bile salt protein carrier to phospholipid vesicles. Proteins 2013; 81:1776-91. [DOI: 10.1002/prot.24329] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2013] [Revised: 04/29/2013] [Accepted: 05/09/2013] [Indexed: 11/07/2022]
Affiliation(s)
- Alberto Ceccon
- Department of Biotechnology; University of Verona; 37134 Verona Italy
| | | | - Serena Zanzoni
- Department of Biotechnology; University of Verona; 37134 Verona Italy
| | - Dario Livio Longo
- Department of Molecular Biotechnologies and Health Sciences; Molecular Imaging Center, University of Torino; 10126 Torino Italy
| | - Silvio Aime
- Department of Molecular Biotechnologies and Health Sciences; Molecular Imaging Center, University of Torino; 10126 Torino Italy
| | | | - Michael Assfalg
- Department of Biotechnology; University of Verona; 37134 Verona Italy
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431
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Nagendran J, Pulinilkunnil T, Kienesberger PC, Sung MM, Fung D, Febbraio M, Dyck JRB. Cardiomyocyte-specific ablation of CD36 improves post-ischemic functional recovery. J Mol Cell Cardiol 2013; 63:180-8. [PMID: 23948483 DOI: 10.1016/j.yjmcc.2013.07.020] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 07/29/2013] [Accepted: 07/31/2013] [Indexed: 12/19/2022]
Abstract
Although pre-clinical evidence has suggested that partial inhibition of myocardial fatty acid oxidation (FAO) and subsequent switch to greater glucose oxidation for ATP production can prevent ischemia/reperfusion injury, controversy about this approach persists. For example, mice with germline deletion of the FA transporter CD36, exhibited either impaired or unchanged post-ischemic functional recovery despite a 40-60% reduction in FAO rates. Because there are limitations to cardiac studies utilizing whole body CD36 knockout (totalCD36KO) mice, we have now generated an inducible and cardiomyocyte-specific CD36 KO (icCD36KO) mouse to better address the role of cardiomyocyte CD36 and its regulation of FAO and post-ischemic functional recovery. Four to six weeks following CD36 ablation, hearts from icCD36KO mice had significantly decreased FA uptake compared to controls, which was paralleled by significant reductions in intramyocardial triacylglycerol content. Analysis of cardiac energy metabolism using ex vivo working heart perfusions showed that reduced FAO rates were compensated by enhanced glucose oxidation in the hearts from icCD36KO mice. In contrast to the totalCD36KO mice, hearts from icCD36KO mice exhibited significantly improved functional recovery following ischemia/reperfusion (18min of global no-flow ischemia followed by 40min of aerobic reperfusion). This improved recovery was associated with lower calculated proton production prior to and following ischemia compared to controls. Moreover, the amount of ATP generated relative to cardiac work was significantly lower in the hearts from icCD36KO mice compared to controls, indicating significantly increased cardiac efficiency in the hearts from icCD36KO mice. These data provide genetic evidence that reduced FAO as a result of diminished CD36-mediated FA uptake improves post-ischemic cardiac efficiency and functional recovery. As such, targeting cardiomyocyte FA uptake and FAO via inhibition of CD36 in the adult myocardium may provide therapeutic benefit during ischemia-reperfusion.
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Affiliation(s)
- Jeevan Nagendran
- Cardiovascular Research Centre, Department of Pediatrics, Mazankowski Alberta Heart Institute, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; Division of Cardiac Surgery, Department of Surgery, Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada
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432
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Canton J, Neculai D, Grinstein S. Scavenger receptors in homeostasis and immunity. Nat Rev Immunol 2013; 13:621-34. [PMID: 23928573 DOI: 10.1038/nri3515] [Citation(s) in RCA: 563] [Impact Index Per Article: 51.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Scavenger receptors were originally identified by their ability to recognize and to remove modified lipoproteins; however, it is now appreciated that they carry out a striking range of functions, including pathogen clearance, lipid transport, the transport of cargo within the cell and even functioning as taste receptors. The large repertoire of ligands recognized by scavenger receptors and their broad range of functions are not only due to the wide range of receptors that constitute this family but also to their ability to partner with various co-receptors. The ability of individual scavenger receptors to associate with different co-receptors makes their responsiveness extremely versatile. This Review highlights recent insights into the structural features that determine the function of scavenger receptors and the emerging role that these receptors have in immune responses, notably in macrophage polarization and in the pathogenesis of diseases such as atherosclerosis and Alzheimer's disease.
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Affiliation(s)
- Johnathan Canton
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
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433
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Tung S, Shi Y, Wong K, Zhu F, Gorczynski R, Laister RC, Minden M, Blechert AK, Genzel Y, Reichl U, Spaner DE. PPARα and fatty acid oxidation mediate glucocorticoid resistance in chronic lymphocytic leukemia. Blood 2013; 122:969-80. [PMID: 23814018 DOI: 10.1182/blood-2013-03-489468] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
High-dose glucocorticoids (GCs) can be a useful treatment for aggressive forms of chronic lymphocytic leukemia (CLL). However, their mechanism of action is not well understood, and resistance to GCs is inevitable. In a minimal, serum-free culture system, the synthetic GC dexamethasone (DEX) was found to decrease the metabolic activity of CLL cells, indicated by down-regulation of pyruvate kinase M2 (PKM2) expression and activity, decreased levels of pyruvate and its metabolites, and loss of mitochondrial membrane potential. This metabolic restriction was associated with decreased size and death of some of the tumor cells in the population. Concomitant plasma membrane damage increased killing of CLL cells by DEX. However, the nuclear receptor peroxisome proliferator activated receptor α (PPARα), which regulates fatty acid oxidation, was also increased by DEX, and adipocyte-derived lipids, lipoproteins, and propionic acid protected CLL cells from DEX. PPARα and fatty acid oxidation enzyme inhibitors increased DEX-mediated killing of CLL cells in vitro and clearance of CLL xenografts in vivo. These findings suggest that GCs prevent tumor cells from generating the energy needed to repair membrane damage, fatty acid oxidation is a mechanism of resistance to GC-mediated cytotoxicity, and PPARα inhibition is a strategy to improve the therapeutic efficacy of GCs.
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MESH Headings
- Adipocytes/cytology
- Animals
- Carrier Proteins/metabolism
- Cell Line, Tumor
- Cell Membrane/metabolism
- Culture Media, Conditioned
- Dexamethasone/pharmacology
- Drug Resistance, Neoplasm
- Fatty Acids/metabolism
- Gene Expression Regulation, Leukemic
- Glucocorticoids/pharmacology
- Humans
- Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy
- Leukemia, Lymphocytic, Chronic, B-Cell/metabolism
- Lipid Metabolism
- Membrane Potential, Mitochondrial
- Membrane Proteins/metabolism
- Mice
- Mice, Inbred NOD
- Mice, SCID
- Oxygen/metabolism
- PPAR alpha/metabolism
- Phosphorylation
- Propionates/chemistry
- Thyroid Hormones/metabolism
- Thyroid Hormone-Binding Proteins
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Affiliation(s)
- Stephanie Tung
- Division of Molecular and Cellular Biology, Sunnybrook Research Institute, 2075 Bayview Ave., Toronto, ON, Canada
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434
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Mazibuko SE, Muller CJF, Joubert E, de Beer D, Johnson R, Opoku AR, Louw J. Amelioration of palmitate-induced insulin resistance in C₂C₁₂ muscle cells by rooibos (Aspalathus linearis). PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2013; 20:813-819. [PMID: 23639187 DOI: 10.1016/j.phymed.2013.03.018] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Accepted: 03/27/2013] [Indexed: 06/02/2023]
Abstract
Increased levels of free fatty acids (FFAs), specifically saturated free fatty acids such as palmitate are associated with insulin resistance of muscle, fat and liver. Skeletal muscle, responsible for up to 80% of the glucose disposal from the peripheral circulation, is particularly vulnerable to increased levels of saturated FFAs. Rooibos (Aspalathus linearis) and its unique dihydrochalcone C-glucoside, aspalathin, shown to reduce hyperglycemia in diabetic rats, could play a role in preventing or ameliorating the development of insulin resistance. This study aims to establish whether rooibos can ameliorate experimentally-induced insulin-resistance in C₂C₁₂ skeletal muscle cells. Palmitate-induced insulin resistant C₂C₁₂ cells were treated with an aspalathin-enriched green (unfermented) rooibos extract (GRE), previously shown for its blood glucose lowering effect in vitro and in vivo or an aqueous extract of fermented rooibos (FRE). Glucose uptake and mitochondrial activity were measured using 2-deoxy-[³H]-D-glucose, MTT and ATP assays, respectively. Expression of proteins relevant to glucose metabolism was analysed by Western blot. GRE contained higher levels of all compounds, except the enolic phenylpyruvic acid-2-O-glucoside and luteolin-7-O-glucoside. Both rooibos extracts increased glucose uptake, mitochondrial activity and ATP production. Compared to FRE, GRE was more effective at increasing glucose uptake and ATP production. At a mechanistic level both extracts down-regulated PKC θ activation, which is associated with palmitate-induced insulin resistance. Furthermore, the extracts increased activation of key regulatory proteins (AKT and AMPK) involved in insulin-dependent and non-insulin regulated signalling pathways. Protein levels of the glucose transporter (GLUT4) involved in glucose transport via these two pathways were also increased. This in vitro study therefore confirms that rooibos can ameliorate palmitate-induced insulin resistance in C₂C₁₂ skeletal muscle cells. Inhibition of PKC θ activation and increased activation of AMPK and AKT offer a plausible mechanistic explanation for this ameliorative effect.
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Affiliation(s)
- S E Mazibuko
- Diabetes Discovery Platform, South African Medical Research Council, P.O. Box 19070, Tygerberg 7505, South Africa.
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435
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Eisenreich W, Heesemann J, Rudel T, Goebel W. Metabolic host responses to infection by intracellular bacterial pathogens. Front Cell Infect Microbiol 2013; 3:24. [PMID: 23847769 PMCID: PMC3705551 DOI: 10.3389/fcimb.2013.00024] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 06/11/2013] [Indexed: 12/12/2022] Open
Abstract
The interaction of bacterial pathogens with mammalian hosts leads to a variety of physiological responses of the interacting partners aimed at an adaptation to the new situation. These responses include multiple metabolic changes in the affected host cells which are most obvious when the pathogen replicates within host cells as in case of intracellular bacterial pathogens. While the pathogen tries to deprive nutrients from the host cell, the host cell in return takes various metabolic countermeasures against the nutrient theft. During this conflicting interaction, the pathogen triggers metabolic host cell responses by means of common cell envelope components and specific virulence-associated factors. These host reactions generally promote replication of the pathogen. There is growing evidence that pathogen-specific factors may interfere in different ways with the complex regulatory network that controls the carbon and nitrogen metabolism of mammalian cells. The host cell defense answers include general metabolic reactions, like the generation of oxygen- and/or nitrogen-reactive species, and more specific measures aimed to prevent access to essential nutrients for the respective pathogen. Accurate results on metabolic host cell responses are often hampered by the use of cancer cell lines that already exhibit various de-regulated reactions in the primary carbon metabolism. Hence, there is an urgent need for cellular models that more closely reflect the in vivo infection conditions. The exact knowledge of the metabolic host cell responses may provide new interesting concepts for antibacterial therapies.
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Affiliation(s)
- Wolfgang Eisenreich
- Lehrstuhl für Biochemie, Center of Isotopologue Profiling, Technische Universität München Garching, Germany
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436
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Roche JR, Kay JK, Friggens NC, Loor JJ, Berry DP. Assessing and Managing Body Condition Score for the Prevention of Metabolic Disease in Dairy Cows. Vet Clin North Am Food Anim Pract 2013; 29:323-36. [DOI: 10.1016/j.cvfa.2013.03.003] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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437
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Casuso RA, Martínez-Amat A, Martínez-Romero R, Camiletti-Moiron D, Hita-Contreras F, Martínez-López E. Plasmatic nitric oxide correlates with weight and red cell distribution width in exercised rats supplemented with quercetin. Int J Food Sci Nutr 2013; 64:830-5. [PMID: 23763647 DOI: 10.3109/09637486.2013.803521] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Quercetin is suggested as a nitric oxide regulator which may in turn influence blood parameters and weight gain. Wistar rats were classified as: quercetin-exercise training, QT; placebo-exercise training, PT; quercetin-sedentary, QS; and placebo sedentary, PS. After 6 weeks of treatment with quercetin and/or exercise, an incremental test was run to measure oxygen consumption. QT had lower levels of NO compared with PS (p = 0.029) and QS (p = 0.002). Red cell distribution width increased in both exercised groups, especially in the QT group (p < 0.001). Pearson correlation analysis showed that nitric oxide levels were associated with weight (r = 0.675) and red distribution width (r = -0814) in the QT group. Quercetin effect on NO production seems to be more powerful when it is supplemented during exercise training. Moreover, RDW relationship with NO production need to be further investigated in regards to health.
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438
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Dobrzyn P, Pyrkowska A, Duda MK, Bednarski T, Maczewski M, Langfort J, Dobrzyn A. Expression of lipogenic genes is upregulated in the heart with exercise training-induced but not pressure overload-induced left ventricular hypertrophy. Am J Physiol Endocrinol Metab 2013; 304:E1348-58. [PMID: 23632628 DOI: 10.1152/ajpendo.00603.2012] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cardiac hypertrophy is accompanied by molecular remodeling that affects different cellular pathways, including fatty acid (FA) utilization. In the present study, we show that cardiac lipid metabolism is differentially regulated in response to physiological (endurance training) and pathological [abdominal aortic banding (AAB)] hypertrophic stimuli. Physiological hypertrophy was accompanied by an increased expression of lipogenic genes and the activation of sterol regulatory element-binding protein-1c and Akt signaling. Additionally, FA oxidation pathways regulated by AMP-activated protein kinase (AMPK) and peroxisome proliferator activated receptor-α (PPARα) were induced in trained hearts. Cardiac lipid content was not changed by physiological stimulation, underlining balanced lipid utilization in the trained heart. Moreover, pathological hypertrophy induced the AMPK-regulated oxidative pathway, whereas PPARα and expression of its downstream targets, i.e., acyl-CoA oxidase and carnitine palmitoyltransferase I, were not affected by AAB. In contrast, pathological hypertrophy leads to cardiac triglyceride (TG) and diacylglycerol (DAG) accumulation, although the expression of lipogenic genes and the levels of FA transport proteins (CD36 and FATP) were not changed or reduced compared with the sham group. A possible explanation for this phenomenon is a decrease in lipolysis, as evidenced by the increased content of adipose triglyceride lipase inhibitor G0S2, the increased phosphorylation of hormone-sensitive lipase at Ser(565), and the decreased protein levels of DAG lipase that attenuate TG and DAG contents. The increased TG and DAG accumulation observed in AAB-induced hypertrophy might have lipotoxic effects, thereby predisposing to cardiomyopathy and heart failure in the future.
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Affiliation(s)
- Pawel Dobrzyn
- Laboratory of Molecular and Medical Biochemistry, Nencki Institute of Experimental Biology, Warsaw, Poland
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439
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Hu C, Ge F, Hyodo E, Arai K, Iwata S, Lobdell H, Walewski JL, Zhou S, Clugston RD, Jiang H, Zizola CP, Bharadwaj KG, Blaner WS, Homma S, Schulze PC, Goldberg IJ, Berk PD. Chronic ethanol consumption increases cardiomyocyte fatty acid uptake and decreases ventricular contractile function in C57BL/6J mice. J Mol Cell Cardiol 2013; 59:30-40. [PMID: 23422163 PMCID: PMC3647020 DOI: 10.1016/j.yjmcc.2013.02.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 02/01/2013] [Accepted: 02/02/2013] [Indexed: 02/07/2023]
Abstract
Alcohol, a major cause of human cardiomyopathy, decreases cardiac contractility in both animals and man. However, key features of alcohol-related human heart disease are not consistently reproduced in animal models. Accordingly, we studied cardiac histology, contractile function, cardiomyocyte long chain fatty acid (LCFA) uptake, and gene expression in male C57BL/6J mice consuming 0, 10, 14, or 18% ethanol in drinking water for 3months. At sacrifice, all EtOH groups had mildly decreased body and increased heart weights, dose-dependent increases in cardiac triglycerides and a marked increase in cardiac fatty acid ethyl esters. [(3)H]-oleic acid uptake kinetics demonstrated increased facilitated cardiomyocyte LCFA uptake, associated with increased expression of genes encoding the LCFA transporters CD36 and Slc27a1 (FATP1) in EtOH-fed animals. Although SCD-1 expression was increased, lipidomic analysis did not indicate significantly increased de novo LCFA synthesis. By echocardiography, ejection fraction (EF) and the related fractional shortening (FS) of left ventricular diameter during systole were reduced and negatively correlated with cardiac triglycerides. Expression of myocardial PGC-1α and multiple downstream target genes in the oxidative phosphorylation pathway, including several in the electron transport and ATP synthase complexes of the inner mitochondrial membrane, were down-regulated. Cardiac ATP was correspondingly reduced. The data suggest that decreased expression of PGC-1α and its target genes result in decreased cardiac ATP levels, which may explain the decrease in myocardial contractile function caused by chronic EtOH intake. This model recapitulates important features of human alcoholic cardiomyopathy and illustrates a potentially important pathophysiologic link between cardiac lipid metabolism and function.
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Affiliation(s)
- Chunguang Hu
- The Department of Medicine, Division of Digestive & Liver Disease, Columbia University College of Physicians & Surgeons, New York, NY 10032, USA
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440
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Montgomery MK, Hallahan NL, Brown SH, Liu M, Mitchell TW, Cooney GJ, Turner N. Mouse strain-dependent variation in obesity and glucose homeostasis in response to high-fat feeding. Diabetologia 2013; 56:1129-39. [PMID: 23423668 DOI: 10.1007/s00125-013-2846-8] [Citation(s) in RCA: 287] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 01/15/2013] [Indexed: 12/12/2022]
Abstract
AIMS/HYPOTHESIS Metabolic disorders are commonly investigated using knockout and transgenic mouse models. A variety of mouse strains have been used for this purpose. However, mouse strains can differ in their inherent propensities to develop metabolic disease, which may affect the experimental outcomes of metabolic studies. We have investigated strain-dependent differences in the susceptibility to diet-induced obesity and insulin resistance in five commonly used inbred mouse strains (C57BL/6J, 129X1/SvJ, BALB/c, DBA/2 and FVB/N). METHODS Mice were fed either a low-fat or a high-fat diet (HFD) for 8 weeks. Whole-body energy expenditure and body composition were then determined. Tissues were used to measure markers of mitochondrial metabolism, inflammation, oxidative stress and lipid accumulation. RESULTS BL6, 129X1, DBA/2 and FVB/N mice were all susceptible to varying degrees to HFD-induced obesity, glucose intolerance and insulin resistance, but BALB/c mice exhibited some protection from these detrimental effects. This protection could not be explained by differences in mitochondrial metabolism or oxidative stress in liver or muscle, or inflammation in adipose tissue. Interestingly, in contrast with the other strains, BALB/c mice did not accumulate excess lipid (triacylglycerols and diacylglycerols) in the liver; this is potentially related to lower fatty acid uptake rather than differences in lipogenesis or lipid oxidation. CONCLUSIONS/INTERPRETATION Collectively, our findings indicate that most mouse strains develop metabolic defects on an HFD. However, there are inherent differences between strains, and thus the genetic background needs to be considered carefully in metabolic studies.
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MESH Headings
- Adipose Tissue, Brown/immunology
- Adipose Tissue, Brown/metabolism
- Adipose Tissue, Brown/pathology
- Adipose Tissue, White/immunology
- Adipose Tissue, White/metabolism
- Adipose Tissue, White/pathology
- Adiposity
- Animals
- Biomarkers/metabolism
- Diet, High-Fat/adverse effects
- Disease Susceptibility
- Glucose Intolerance/etiology
- Glucose Intolerance/immunology
- Glucose Intolerance/metabolism
- Glucose Intolerance/pathology
- Insulin Resistance
- Lipid Metabolism
- Liver/enzymology
- Liver/metabolism
- Male
- Mice
- Mice, Inbred Strains
- Mitochondria/enzymology
- Mitochondria/metabolism
- Muscle, Skeletal/enzymology
- Muscle, Skeletal/metabolism
- Obesity/etiology
- Obesity/immunology
- Obesity/metabolism
- Obesity/pathology
- Oxidative Stress
- Random Allocation
- Species Specificity
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Affiliation(s)
- M K Montgomery
- Diabetes and Obesity Research Program, Garvan Institute of Medical Research, 384 Victoria St., Darlinghurst, Sydney, NSW 2010, Australia
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441
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Kuda O, Pietka TA, Demianova Z, Kudova E, Cvacka J, Kopecky J, Abumrad NA. Sulfo-N-succinimidyl oleate (SSO) inhibits fatty acid uptake and signaling for intracellular calcium via binding CD36 lysine 164: SSO also inhibits oxidized low density lipoprotein uptake by macrophages. J Biol Chem 2013; 288:15547-55. [PMID: 23603908 DOI: 10.1074/jbc.m113.473298] [Citation(s) in RCA: 127] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
FAT/CD36 is a multifunctional glycoprotein that facilitates long-chain fatty acid (FA) uptake by cardiomyocytes and adipocytes and uptake of oxidized low density lipoproteins (oxLDL) by macrophages. CD36 also mediates FA-induced signaling to increase intracellular calcium in various cell types. The membrane-impermeable sulfo-N-hydroxysuccinimidyl (NHS) ester of oleate (SSO) irreversibly binds CD36 and has been widely used to inhibit CD36-dependent FA uptake and signaling to calcium. The inhibition mechanism and whether SSO modification of CD36 involves the FA-binding site remain unexplored. CHO cells expressing human CD36 were SSO-treated, and the protein was pulled down, deglycosylated, and resolved by electrophoresis. The CD36 band was extracted from the gel and digested for analysis by mass spectrometry. NHS derivatives react with primary or secondary amines on proteins to yield stable amide or imide bonds. Two oleoylated peptides, found only in SSO-treated samples, were identified with high contribution and confidence scores as carrying oleate modification of Lys-164. Lysine 164 lies within a predicted CD36 binding domain for FA and oxLDL. CHO cells expressing CD36 with mutated Lys-164 had impaired CD36 function in FA uptake and FA-induced calcium release from the endoplasmic reticulum, supporting the importance of Lys-164 for both FA effects. Furthermore, consistent with the importance of Lys-164 for oxLDL binding, SSO inhibited oxLDL uptake by macrophages. In conclusion, SSO accesses Lys-164 in the FA-binding site on CD36, and initial modeling of this site is presented. The data suggest competition between FA and oxLDL for access to the CD36 binding pocket.
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Affiliation(s)
- Ondrej Kuda
- Institute of Physiology, Academy of Sciences of the Czech Republic, v.v.i., Videnska 1083, 14220 Praha 4, Czech Republic.
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442
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Nagendran J, Waller TJ, Dyck JRB. AMPK signalling and the control of substrate use in the heart. Mol Cell Endocrinol 2013; 366:180-93. [PMID: 22750050 DOI: 10.1016/j.mce.2012.06.015] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 03/29/2012] [Accepted: 06/21/2012] [Indexed: 12/21/2022]
Abstract
All mammalian cells rely on adenosine triphosphate (ATP) to maintain function and for survival. The heart has the highest basal ATP demand of any organ due to the necessity for continuous contraction. As such, the ability of the cardiomyocyte to monitor cellular energy status and adapt the supply of substrates to match the energy demand is crucial. One important serine/threonine protein kinase that monitors cellular energy status in the heart is adenosine monophosphate activated protein kinase (AMPK). AMPK is also a key enzyme that controls multiple catabolic and anabolic biochemical pathways in the heart and indirectly plays a crucial role in regulating cardiac function in both physiological and pathophysiological conditions. Herein, we review the involvement of AMPK in myocardial fatty acid and glucose transport and utilization, as it relates to basal cardiac function. We also assess the literature amassed on cardiac AMPK and discuss the controversies surrounding the role of AMPK in physiological and pathophysiological processes in the heart. The work reviewed herein also emphasizes areas that require further investigation for the purpose of eventually translating this information into improved patient care.
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Affiliation(s)
- Jeevan Nagendran
- Cardiovascular Research Centre, Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
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443
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Abstract
Carnitine palmitoyltransferase I has been viewed historically as the sole regulator of fatty acid oxidation. However, we have identified fatty acid translocase/CD36 as an additional control point. Specifically, fatty acid translocase/CD36 seems to have a novel dual mechanism of action with regard to fatty acid oxidation during exercise, influencing transport of lipids across the sarcolemmal membrane and into the mitochondria.
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444
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Chabowski A, Żendzian-Piotrowska M, Konstantynowicz K, Pankiewicz W, Mikłosz A, Łukaszuk B, Górski J. Fatty acid transporters involved in the palmitate and oleate induced insulin resistance in primary rat hepatocytes. Acta Physiol (Oxf) 2013; 207:346-57. [PMID: 23140342 DOI: 10.1111/apha.12022] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 06/25/2012] [Accepted: 09/18/2012] [Indexed: 12/12/2022]
Abstract
AIMS To determine the presence and possible involvement of FAT/CD36, FABPpm and FATP-2, transporters in (i) fatty acids movement across plasma membrane and (ii) an induction of insulin resistance by palmitic (PA) and oleic (OA) fatty acids in primary hepatocytes. METHODS Primary hepatocytes were treated with either PA and OA or combination of activators (AICAR, Insulin) or inhibitors (SSO, phloretin) of FA transport. Expression of FA and glucose transporters as well as insulin signalling proteins was determined using Western blot analyses. Palmitate and glucose transport was measured using radioactive isotopes. Intracellular lipid content [ceramide, diacylglycerols (DG) and triacylglycerols] and FA composition were estimated by GLC. RESULTS In primary hepatocytes, adding phloretin diminished insulin, and AICAR stimulated palmitate transport. Both PA and OA fatty acids induced the protein expression of FAT/CD36 and FATP-2 with concomitant: (i) reduction in GLUT-2 protein content, (ii) inhibition of insulin-stimulated glucose uptake, (iii) reduction in insulin-stimulated activation of AKT and GSK, (iv) accumulation of either DG (PA and OA) or ceramide (only PA). CONCLUSIONS FA transport into hepatocytes is, at least in part, protein-mediated process, and both PA and OA induce the protein expression of FAT/CD36 and FATP-2. Both saturated (PA) and unsaturated (OA) fatty acids induce insulin resistance in primary hepatocytes, associated with the accumulation of DG and/or ceramide.
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Affiliation(s)
- A. Chabowski
- Department of Physiology; Medical University of Bialystok; Bialystok; Poland
| | | | - K. Konstantynowicz
- Department of Physiology; Medical University of Bialystok; Bialystok; Poland
| | - W. Pankiewicz
- Department of Physiology; Medical University of Bialystok; Bialystok; Poland
| | - A. Mikłosz
- Department of Physiology; Medical University of Bialystok; Bialystok; Poland
| | - B. Łukaszuk
- Department of Physiology; Medical University of Bialystok; Bialystok; Poland
| | - J. Górski
- Department of Physiology; Medical University of Bialystok; Bialystok; Poland
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445
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Chowdhury KK, Legare DJ, Lautt WW. Lifestyle impact on meal-induced insulin sensitization in health and prediabetes: A focus on diet, antioxidants, and exercise interventions. Can J Physiol Pharmacol 2013; 91:91-100. [DOI: 10.1139/cjpp-2012-0228] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The augmented whole-body glucose uptake response to insulin during the postprandial state is described as meal-induced insulin sensitization (MIS). MIS occurs when the presence of food in the upper gastrointestinal tract activates 2 feeding signals (activation of hepatic parasympathetic nerves and elevation of hepatic glutathione level), and causes insulin to release hepatic insulin sensitizing substance (HISS), which stimulates glucose uptake in skeletal muscle, heart, and kidneys. HISS action results in nutrient storage, primarily as glycogen. Impairment of HISS release results in the absence of meal-induced insulin sensitization (AMIS), which causes postprandial hyperglycemia and hyperinsulinemia, and chronically leads to the progression to a cluster of metabolic, vascular, and cardiac dysfunctions, which we refer to as components of the AMIS syndrome. Manipulation of the MIS process in health and in disease, by pharmacological and nonpharmacological interventions, is outlined in this review. High fat or sugar supplemented diet reduces MIS; exercise elevates MIS; and antioxidants protect MIS against reductions associated with diet and age.
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Affiliation(s)
- Kawshik K. Chowdhury
- Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Manitoba, A210 – 753 McDermot Avenue, Winnipeg, MB R3E 0T6, Canada
| | - Dallas J. Legare
- Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Manitoba, A210 – 753 McDermot Avenue, Winnipeg, MB R3E 0T6, Canada
| | - W. Wayne Lautt
- Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Manitoba, A210 – 753 McDermot Avenue, Winnipeg, MB R3E 0T6, Canada
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446
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Semova I, Carten JD, Stombaugh J, Mackey LC, Knight R, Farber SA, Rawls JF. Microbiota regulate intestinal absorption and metabolism of fatty acids in the zebrafish. Cell Host Microbe 2013; 12:277-88. [PMID: 22980325 DOI: 10.1016/j.chom.2012.08.003] [Citation(s) in RCA: 569] [Impact Index Per Article: 51.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Revised: 05/01/2012] [Accepted: 08/02/2012] [Indexed: 12/16/2022]
Abstract
Regulation of intestinal dietary fat absorption is critical to maintaining energy balance. While intestinal microbiota clearly impact the host's energy balance, their role in intestinal absorption and extraintestinal metabolism of dietary fat is less clear. Using in vivo imaging of fluorescent fatty acid (FA) analogs delivered to gnotobiotic zebrafish hosts, we reveal that microbiota stimulate FA uptake and lipid droplet (LD) formation in the intestinal epithelium and liver. Microbiota increase epithelial LD number in a diet-dependent manner. The presence of food led to the intestinal enrichment of bacteria from the phylum Firmicutes. Diet-enriched Firmicutes and their products were sufficient to increase epithelial LD number, whereas LD size was increased by other bacterial types. Thus, different members of the intestinal microbiota promote FA absorption via distinct mechanisms. Diet-induced alterations in microbiota composition might influence fat absorption, providing mechanistic insight into how microbiota-diet interactions regulate host energy balance.
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Affiliation(s)
- Ivana Semova
- Department of Cell and Molecular Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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447
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Goto K, Iso T, Hanaoka H, Yamaguchi A, Suga T, Hattori A, Irie Y, Shinagawa Y, Matsui H, Syamsunarno MRAA, Matsui M, Haque A, Arai M, Kunimoto F, Yokoyama T, Endo K, Gonzalez FJ, Kurabayashi M. Peroxisome proliferator-activated receptor-γ in capillary endothelia promotes fatty acid uptake by heart during long-term fasting. J Am Heart Assoc 2013; 2:e004861. [PMID: 23525438 PMCID: PMC3603264 DOI: 10.1161/jaha.112.004861] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Background Endothelium is a crucial blood–tissue interface controlling energy supply according to organ needs. We investigated whether peroxisome proliferator‐activated receptor‐γ (PPARγ) induces expression of fatty acid–binding protein 4 (FABP4) and fatty acid translocase (FAT)/CD36 in capillary endothelial cells (ECs) to promote FA transport into the heart. Methods and Results Expression of FABP4 and CD36 was induced by the PPARγ agonist pioglitazone in human cardiac microvessel ECs (HCMECs), but not in human umbilical vein ECs. Real‐time PCR and immunohistochemistry of the heart tissue of control (Ppargfl/null) mice showed an increase in expression of FABP4 and CD36 in capillary ECs by either pioglitazone treatment or 48 hours of fasting, and these effects were not found in mice deficient in endothelial PPARγ (Pparg∆EC/null). Luciferase reporter constructs of the Fabp4 and CD36 promoters were markedly activated by pioglitazone in HCMECs through canonical PPAR‐responsive elements. Activation of PPARγ facilitated FA uptake by HCMECs, which was partially inhibited by knockdown of either FABP4 or CD36. Uptake of an FA analogue, 125I‐BMIPP, was significantly reduced in heart, red skeletal muscle, and adipose tissue in Pparg∆EC/null mice as compared with Ppargfl/null mice after olive oil loading, whereas those values were comparable between Ppargfl/null and Pparg∆EC/null null mice on standard chow and a high‐fat diet. Furthermore, Pparg∆EC/null mice displayed slower triglyceride clearance after olive oil loading. Conclusions These findings identified a novel role for capillary endothelial PPARγ as a regulator of FA handing in FA‐metabolizing organs including the heart in the postprandial state after long‐term fasting.
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Affiliation(s)
- Kosaku Goto
- Department of Medicine and Biological Science, Gunma University Graduate School of Health Sciences, Maebashi, Gunma, Japan
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448
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CD36 inhibition prevents lipid accumulation and contractile dysfunction in rat cardiomyocytes. Biochem J 2013; 448:43-53. [PMID: 22780108 DOI: 10.1042/bj20120060] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
An increased cardiac fatty acid supply and increased sarcolemmal presence of the long-chain fatty acid transporter CD36 are associated with and contribute to impaired cardiac insulin sensitivity and function. In the present study we aimed at preventing the development of insulin resistance and contractile dysfunction in cardiomyocytes by blocking CD36-mediated palmitate uptake. Insulin resistance and contractile dysfunction were induced in primary cardiomyocytes by 48 h incubation in media containing either 100 nM insulin (high insulin; HI) or 200 μM palmitate (high palmitate; HP). Under both culture conditions, insulin-stimulated glucose uptake and Akt phosphorylation were abrogated or markedly reduced. Furthermore, cardiomyocytes cultured in each medium displayed elevated sarcolemmal CD36 content, increased basal palmitate uptake, lipid accumulation and decreased sarcomere shortening. Immunochemical CD36 inhibition enhanced basal glucose uptake and prevented elevated basal palmitate uptake, triacylglycerol accumulation and contractile dysfunction in cardiomyocytes cultured in either medium. Additionally, CD36 inhibition prevented loss of insulin signalling in cells cultured in HP, but not in HI medium. In conclusion, CD36 inhibition prevents lipid accumulation and lipid-induced contractile dysfunction in cardiomyocytes, but probably independently of effects on insulin signalling. Nonetheless, pharmacological CD36 inhibition may be considered as a treatment strategy to counteract impaired functioning of the lipid-loaded heart.
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449
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Glatz JFC, Angin Y, Steinbusch LKM, Schwenk RW, Luiken JJFP. CD36 as a target to prevent cardiac lipotoxicity and insulin resistance. Prostaglandins Leukot Essent Fatty Acids 2013; 88:71-7. [PMID: 22580174 DOI: 10.1016/j.plefa.2012.04.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Revised: 04/19/2012] [Accepted: 04/20/2012] [Indexed: 11/17/2022]
Abstract
The fatty acid transporter and scavenger receptor CD36 is increasingly being implicated in the pathogenesis of insulin resistance and its progression towards type 2 diabetes and associated cardiovascular complications. The redistribution of CD36 from intracellular stores to the plasma membrane is one of the earliest changes occurring in the heart during diet induced obesity and insulin resistance. This elicits an increased rate of fatty acid uptake and enhanced incorporation into triacylglycerol stores and lipid intermediates to subsequently interfere with insulin-induced GLUT4 recruitment (i.e., insulin resistance). In the present paper we discuss the potential of CD36 to serve as a target to rectify abnormal myocardial fatty acid uptake rates in cardiac lipotoxic diseases. Two approaches are described: (i) immunochemical inhibition of CD36 present at the sarcolemma and (ii) interference with the subcellular recycling of CD36. Using in vitro model systems of high-fat diet induced insulin resistance, the results indicate the feasibility of using CD36 as a target for adaptation of cardiac metabolic substrate utilization. In conclusion, CD36 deserves further attention as a promising therapeutic target to redirect fatty acid fluxes in the body.
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Affiliation(s)
- Jan F C Glatz
- Department of Molecular Genetics, Cardiovascular Research Institute Maastricht CARIM, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands.
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450
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Karahashi M, Hoshina M, Yamazaki T, Sakamoto T, Mitsumoto A, Kawashima Y, Kudo N. Fibrates Reduce Triacylglycerol Content by Upregulating Adipose Triglyceride Lipase in the Liver of Rats. J Pharmacol Sci 2013; 123:356-70. [DOI: 10.1254/jphs.13149fp] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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