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Sharma AK, Khandelwal R, Wolfrum C. Futile cycles: Emerging utility from apparent futility. Cell Metab 2024; 36:1184-1203. [PMID: 38565147 DOI: 10.1016/j.cmet.2024.03.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 02/15/2024] [Accepted: 03/11/2024] [Indexed: 04/04/2024]
Abstract
Futile cycles are biological phenomena where two opposing biochemical reactions run simultaneously, resulting in a net energy loss without appreciable productivity. Such a state was presumed to be a biological aberration and thus deemed an energy-wasting "futile" cycle. However, multiple pieces of evidence suggest that biological utilities emerge from futile cycles. A few established functions of futile cycles are to control metabolic sensitivity, modulate energy homeostasis, and drive adaptive thermogenesis. Yet, the physiological regulation, implication, and pathological relevance of most futile cycles remain poorly studied. In this review, we highlight the abundance and versatility of futile cycles and propose a classification scheme. We further discuss the energetic implications of various futile cycles and their impact on basal metabolic rate, their bona fide and tentative pathophysiological implications, and putative drug interactions.
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Affiliation(s)
- Anand Kumar Sharma
- Laboratory of Translational Nutrition Biology, Institute of Food, Nutrition and Health, ETH Zurich, Schwerzenbach, Switzerland.
| | - Radhika Khandelwal
- Laboratory of Translational Nutrition Biology, Institute of Food, Nutrition and Health, ETH Zurich, Schwerzenbach, Switzerland
| | - Christian Wolfrum
- Laboratory of Translational Nutrition Biology, Institute of Food, Nutrition and Health, ETH Zurich, Schwerzenbach, Switzerland.
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2
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Abstract
Rather than serving as a mere onlooker, adipose tissue is a complex endocrine organ and active participant in disease initiation and progression. Disruptions of biological processes operating within adipose can disturb healthy systemic physiology, the sequelae of which include metabolic disorders such as obesity and type 2 diabetes. A burgeoning interest in the field of adipose research has allowed for the elucidation of regulatory networks underlying both adipose tissue function and dysfunction. Despite this progress, few diseases are treated by targeting maladaptation in the adipose, an oft-overlooked organ. In this review, we elaborate on the distinct subtypes of adipocytes, their developmental origins and secretory roles, and the dynamic interplay at work within the tissue itself. Central to this discussion is the relationship between adipose and disease states, including obesity, cachexia, and infectious diseases, as we aim to leverage our wealth of knowledge for the development of novel and targeted therapeutics.
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Affiliation(s)
- Christopher Auger
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA;
| | - Shingo Kajimura
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA; .,Howard Hughes Medical Institute, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA;
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3
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Oeckl J, Janovska P, Adamcova K, Bardova K, Brunner S, Dieckmann S, Ecker J, Fromme T, Funda J, Gantert T, Giansanti P, Hidrobo MS, Kuda O, Kuster B, Li Y, Pohl R, Schmitt S, Schweizer S, Zischka H, Zouhar P, Kopecky J, Klingenspor M. Loss of UCP1 function augments recruitment of futile lipid cycling for thermogenesis in murine brown fat. Mol Metab 2022; 61:101499. [PMID: 35470094 PMCID: PMC9097615 DOI: 10.1016/j.molmet.2022.101499] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 04/12/2022] [Accepted: 04/12/2022] [Indexed: 11/30/2022] Open
Affiliation(s)
- Josef Oeckl
- Chair for Molecular Nutritional Medicine, TUM School of Life Sciences, Technical University of Munich, Freising, Germany; EKFZ - Else Kröner Fresenius Center for Nutritional Medicine, Technical University of Munich, Freising, Germany; ZIEL Institute for Food & Health, Technical University of Munich, Freising, Germany
| | - Petra Janovska
- Laboratory of Adipose Tissue Biology, Institute of Physiology of the Czech Academy of Sciences, Czech Republic
| | - Katerina Adamcova
- Laboratory of Adipose Tissue Biology, Institute of Physiology of the Czech Academy of Sciences, Czech Republic
| | - Kristina Bardova
- Laboratory of Adipose Tissue Biology, Institute of Physiology of the Czech Academy of Sciences, Czech Republic
| | - Sarah Brunner
- Chair for Molecular Nutritional Medicine, TUM School of Life Sciences, Technical University of Munich, Freising, Germany; EKFZ - Else Kröner Fresenius Center for Nutritional Medicine, Technical University of Munich, Freising, Germany; ZIEL Institute for Food & Health, Technical University of Munich, Freising, Germany
| | - Sebastian Dieckmann
- Chair for Molecular Nutritional Medicine, TUM School of Life Sciences, Technical University of Munich, Freising, Germany; EKFZ - Else Kröner Fresenius Center for Nutritional Medicine, Technical University of Munich, Freising, Germany; ZIEL Institute for Food & Health, Technical University of Munich, Freising, Germany
| | - Josef Ecker
- ZIEL Institute for Food & Health, Technical University of Munich, Freising, Germany
| | - Tobias Fromme
- Chair for Molecular Nutritional Medicine, TUM School of Life Sciences, Technical University of Munich, Freising, Germany; EKFZ - Else Kröner Fresenius Center for Nutritional Medicine, Technical University of Munich, Freising, Germany; ZIEL Institute for Food & Health, Technical University of Munich, Freising, Germany
| | - Jiri Funda
- Laboratory of Adipose Tissue Biology, Institute of Physiology of the Czech Academy of Sciences, Czech Republic
| | - Thomas Gantert
- Chair for Molecular Nutritional Medicine, TUM School of Life Sciences, Technical University of Munich, Freising, Germany; EKFZ - Else Kröner Fresenius Center for Nutritional Medicine, Technical University of Munich, Freising, Germany; ZIEL Institute for Food & Health, Technical University of Munich, Freising, Germany
| | - Piero Giansanti
- Chair of Proteomics and Bioanalytics, TUM School of Life Sciences, Technical University of Munich, Freising, Germany; Bavarian Center for Biomolecular Mass Spectrometry, Technical University of Munich, Freising, Germany
| | - Maria Soledad Hidrobo
- Chair for Molecular Nutritional Medicine, TUM School of Life Sciences, Technical University of Munich, Freising, Germany; EKFZ - Else Kröner Fresenius Center for Nutritional Medicine, Technical University of Munich, Freising, Germany; ZIEL Institute for Food & Health, Technical University of Munich, Freising, Germany
| | - Ondrej Kuda
- Laboratory of Metabolism of Bioactive Lipids, Institute of Physiology of the Czech Academy of Sciences, Czech Republic
| | - Bernhard Kuster
- Chair of Proteomics and Bioanalytics, TUM School of Life Sciences, Technical University of Munich, Freising, Germany; Bavarian Center for Biomolecular Mass Spectrometry, Technical University of Munich, Freising, Germany
| | - Yongguo Li
- Chair for Molecular Nutritional Medicine, TUM School of Life Sciences, Technical University of Munich, Freising, Germany; EKFZ - Else Kröner Fresenius Center for Nutritional Medicine, Technical University of Munich, Freising, Germany; ZIEL Institute for Food & Health, Technical University of Munich, Freising, Germany
| | - Radek Pohl
- NMR spectroscopy, Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Czech Republic
| | - Sabine Schmitt
- Institute of Toxicology and Environmental Hygiene, School of Medicine, Technical University of Munich, Munich, Germany
| | - Sabine Schweizer
- Chair for Molecular Nutritional Medicine, TUM School of Life Sciences, Technical University of Munich, Freising, Germany; EKFZ - Else Kröner Fresenius Center for Nutritional Medicine, Technical University of Munich, Freising, Germany; ZIEL Institute for Food & Health, Technical University of Munich, Freising, Germany
| | - Hans Zischka
- Institute of Toxicology and Environmental Hygiene, School of Medicine, Technical University of Munich, Munich, Germany; Institute of Molecular Toxicology and Pharmacology, Helmholtz Center Munich, Munich, Germany
| | - Petr Zouhar
- Laboratory of Adipose Tissue Biology, Institute of Physiology of the Czech Academy of Sciences, Czech Republic
| | - Jan Kopecky
- Laboratory of Adipose Tissue Biology, Institute of Physiology of the Czech Academy of Sciences, Czech Republic.
| | - Martin Klingenspor
- Chair for Molecular Nutritional Medicine, TUM School of Life Sciences, Technical University of Munich, Freising, Germany; EKFZ - Else Kröner Fresenius Center for Nutritional Medicine, Technical University of Munich, Freising, Germany; ZIEL Institute for Food & Health, Technical University of Munich, Freising, Germany.
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4
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Arfuso F, Giannetto C, Panzera MF, Fazio F, Piccione G. Uncoupling Protein-1 (UCP1) in the Adult Horse: Correlations with Body Weight, Rectal Temperature and Lipid Profile. Animals (Basel) 2021; 11:ani11061836. [PMID: 34202932 PMCID: PMC8235278 DOI: 10.3390/ani11061836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/15/2021] [Accepted: 06/18/2021] [Indexed: 11/23/2022] Open
Abstract
Simple Summary Uncoupling protein-1 (UCP1) plays important roles in the energy balance and regulation of metabolism and in the body temperature regulation. In this survey the correlation among UCP1, body weight, rectal temperature and lipid profile was assessed in the adult horse. The findings gathered from the current survey showed that UCP1 values are not related with body weight and temperature in studied animals, but they seem to be linked to pathways involved in lipid and lipoprotein metabolism. Abstract This study aimed to evaluate the possible relationship among UCP1, body weight, rectal temperature and lipid profile in the horse. Thirty clinically healthy Italian Saddle geldings (6–10 years old) were enrolled after the informed owners’ consent. All horses were blood sampled and their body weight and rectal temperatures were recorded. On the sera obtained after blood centrifugation the concentration of UCP1, total lipids, phospholipids, non-esterified fatty acids (NEFAs), triglycerides, total cholesterol, high density lipoproteins (HDLs), low density lipoproteins (LDLs) and very low density lipoprotein fraction (VLDLs) was evaluated. Pearson’s correlation analysis was applied to assess the possible relationship between serum UCP1 concentration and the values of body weight, rectal temperature and lipid parameters. Serum UCP1 concentration showed no correlation with body weight, rectal temperature, HDLs and LDLs values, whereas it correlated negatively with serum total lipids, phospholipids, NEFAs, total cholesterol, triglycerides and VLDLs values (p < 0.0001). The findings suggest that in the adult horse the role of UCP1 is linked to the lipid metabolism rather than to thermoregulation.
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Affiliation(s)
- Francesca Arfuso
- Department of Veterinary Sciences, University of Messina, Polo Universitario dell’Annunziata, 98168 Messina, Italy; (C.G.); (F.F.); (G.P.)
- Correspondence: ; Tel.: +39-(090)-6766726
| | - Claudia Giannetto
- Department of Veterinary Sciences, University of Messina, Polo Universitario dell’Annunziata, 98168 Messina, Italy; (C.G.); (F.F.); (G.P.)
| | - Maria Francesca Panzera
- Department of Biomedical, Dental, Morphological and Functional Images, University of Messina, Via Consolare Valeria, 98125 Messina, Italy;
| | - Francesco Fazio
- Department of Veterinary Sciences, University of Messina, Polo Universitario dell’Annunziata, 98168 Messina, Italy; (C.G.); (F.F.); (G.P.)
| | - Giuseppe Piccione
- Department of Veterinary Sciences, University of Messina, Polo Universitario dell’Annunziata, 98168 Messina, Italy; (C.G.); (F.F.); (G.P.)
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Cohen P, Kajimura S. The cellular and functional complexity of thermogenic fat. Nat Rev Mol Cell Biol 2021; 22:393-409. [PMID: 33758402 PMCID: PMC8159882 DOI: 10.1038/s41580-021-00350-0] [Citation(s) in RCA: 208] [Impact Index Per Article: 69.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/08/2021] [Indexed: 02/01/2023]
Abstract
Brown and beige adipocytes are mitochondria-enriched cells capable of dissipating energy in the form of heat. These thermogenic fat cells were originally considered to function solely in heat generation through the action of the mitochondrial protein uncoupling protein 1 (UCP1). In recent years, significant advances have been made in our understanding of the ontogeny, bioenergetics and physiological functions of thermogenic fat. Distinct subtypes of thermogenic adipocytes have been identified with unique developmental origins, which have been increasingly dissected in cellular and molecular detail. Moreover, several UCP1-independent thermogenic mechanisms have been described, expanding the role of these cells in energy homeostasis. Recent studies have also delineated roles for these cells beyond the regulation of thermogenesis, including as dynamic secretory cells and as a metabolic sink. This Review presents our current understanding of thermogenic adipocytes with an emphasis on their development, biological functions and roles in systemic physiology.
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Affiliation(s)
- Paul Cohen
- Laboratory of Molecular Metabolism, The Rockefeller University, New York, NY, USA.
| | - Shingo Kajimura
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
- Department of Cell and Tissue Biology, UCSF Diabetes Center, University of California, San Francisco, San Francisco, CA, USA.
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6
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Cruz MM, Lopes AB, Crisma AR, de Sá RCC, Kuwabara WMT, Curi R, de Andrade PBM, Alonso-Vale MIC. Palmitoleic acid (16:1n7) increases oxygen consumption, fatty acid oxidation and ATP content in white adipocytes. Lipids Health Dis 2018; 17:55. [PMID: 29554895 PMCID: PMC5859716 DOI: 10.1186/s12944-018-0710-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 03/13/2018] [Indexed: 12/27/2022] Open
Abstract
Background We have recently demonstrated that palmitoleic acid (16:1n7) increases lipolysis, glucose uptake and glucose utilization for energy production in white adipose cells. In the present study, we tested the hypothesis that palmitoleic acid modulates bioenergetic activity in white adipocytes. Methods For this, 3 T3-L1 pre-adipocytes were differentiated into mature adipocytes in the presence (or absence) of palmitic (16:0) or palmitoleic (16:1n7) acid at 100 or 200 μM. The following parameters were evaluated: lipolysis, lipogenesis, fatty acid (FA) oxidation, ATP content, oxygen consumption, mitochondrial mass, citrate synthase activity and protein content of mitochondrial oxidative phosphorylation (OXPHOS) complexes. Results Treatment with 16:1n7 during 9 days raised basal and isoproterenol-stimulated lipolysis, FA incorporation into triacylglycerol (TAG), FA oxidation, oxygen consumption, protein expression of subunits representing OXPHOS complex II, III, and V and intracellular ATP content. These effects were not observed in adipocytes treated with 16:0. Conclusions Palmitoleic acid, by concerted action on lipolysis, FA esterification, mitochondrial FA oxidation, oxygen consumption and ATP content, does enhance white adipocyte energy expenditure and may act as local hormone.
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Affiliation(s)
- Maysa M Cruz
- Department of Biological Sciences, Institute of Environmental Sciences, Chemical and Pharmaceutical, Federal University of São Paulo, 210, Sao Nicolau St, Diadema, 09913-030, Brazil
| | - Andressa B Lopes
- Department of Nursing , Health Sciences Center, Federal University of Espírito Santo, Vitória, Brazil
| | - Amanda R Crisma
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Roberta C C de Sá
- Department of Biological Sciences, Institute of Environmental Sciences, Chemical and Pharmaceutical, Federal University of São Paulo, 210, Sao Nicolau St, Diadema, 09913-030, Brazil
| | - Wilson M T Kuwabara
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Rui Curi
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.,Interdisciplinary Postgraduate Program in Health Sciences, Institute of Physical Activity Sciences and Sports, Cruzeiro do Sul University, São Paulo, Brazil
| | - Paula B M de Andrade
- Interdisciplinary Postgraduate Program in Health Sciences, Institute of Physical Activity Sciences and Sports, Cruzeiro do Sul University, São Paulo, Brazil
| | - Maria I C Alonso-Vale
- Department of Biological Sciences, Institute of Environmental Sciences, Chemical and Pharmaceutical, Federal University of São Paulo, 210, Sao Nicolau St, Diadema, 09913-030, Brazil.
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7
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Turenne ED, Weber JM. Lean, mean, lipolytic machines: lipid mobilization in rainbow trout during graded swimming. ACTA ACUST UNITED AC 2018; 221:jeb.171553. [PMID: 29212842 DOI: 10.1242/jeb.171553] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 11/28/2017] [Indexed: 11/20/2022]
Abstract
The mobilization of mammalian lipid reserves is strongly stimulated during exercise to reach a maximum at moderate intensities, but the effects of swimming speed on fish lipolysis have never been quantified. Continuous infusion of 2-[3H]glycerol was used to measure the rate of appearance of glycerol or lipolytic rate (Ra glycerol) in rainbow trout kept at rest, or during graded exercise in a swim tunnel up to critical swimming speed (Ucrit). Results show that Ra glycerol is 1.67±0.18 µmol kg-1 min-1 in control animals, and remains at a steady level of 1.24±0.10 µmol kg-1 min-1 in exercising fish at all swimming intensities. Baseline lipolytic rate provides more than enough fatty acids from lipid reserves to accommodate all the oxidative fuel requirements for swimming at up to 2 body lengths per second (BL s-1), and more than 50% of the energy needed at Ucrit (3.4±0.1 BL s-1). Such 'excess lipolysis' also means that trout sustain high rates of fatty acid reesterification. Maintaining steady lipolysis at rest and throughout graded swimming is strikingly different from mammals that stimulate Ra glycerol by twofold to fivefold to support exercise. Instead, trout act like 'lipolytic machines' that do not modulate Ra glycerol even when their metabolic rate triples - a strategy that eliminates the need to increase lipolytic rate during exercise. This study also supports the notion that maintaining a high rate of reesterification (or triacylglycerol/fatty acid cycling) may be a mechanism widely used by ectotherms to achieve rapid membrane remodelling in variable environments.
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Affiliation(s)
- Eric D Turenne
- Biology Department, University of Ottawa, Ottawa, Ontario, Canada, K1N 6N5
| | - Jean-Michel Weber
- Biology Department, University of Ottawa, Ottawa, Ontario, Canada, K1N 6N5
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8
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Fritzemeier CJ, Hartleb D, Szappanos B, Papp B, Lercher MJ. Erroneous energy-generating cycles in published genome scale metabolic networks: Identification and removal. PLoS Comput Biol 2017; 13:e1005494. [PMID: 28419089 PMCID: PMC5413070 DOI: 10.1371/journal.pcbi.1005494] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 05/02/2017] [Accepted: 04/01/2017] [Indexed: 01/11/2023] Open
Abstract
Energy metabolism is central to cellular biology. Thus, genome-scale models of heterotrophic unicellular species must account appropriately for the utilization of external nutrients to synthesize energy metabolites such as ATP. However, metabolic models designed for flux-balance analysis (FBA) may contain thermodynamically impossible energy-generating cycles: without nutrient consumption, these models are still capable of charging energy metabolites (such as ADP→ATP or NADP+→NADPH). Here, we show that energy-generating cycles occur in over 85% of metabolic models without extensive manual curation, such as those contained in the ModelSEED and MetaNetX databases; in contrast, such cycles are rare in the manually curated models of the BiGG database. Energy generating cycles may represent model errors, e.g., erroneous assumptions on reaction reversibilities. Alternatively, part of the cycle may be thermodynamically feasible in one environment, while the remainder is thermodynamically feasible in another environment; as standard FBA does not account for thermodynamics, combining these into an FBA model allows erroneous energy generation. The presence of energy-generating cycles typically inflates maximal biomass production rates by 25%, and may lead to biases in evolutionary simulations. We present efficient computational methods (i) to identify energy generating cycles, using FBA, and (ii) to identify minimal sets of model changes that eliminate them, using a variant of the GlobalFit algorithm. Genome-scale metabolic models are routinely used to simulate the growth of unicellular organisms, and are likely to become an important tool in the medical sciences. The most popular method employed for this task is flux balance analysis (FBA), a simplified mathematical description able to describe the simultaneous activity of hundreds of biochemical reactions. Cellular functions are often dependent on the availability of sufficient energy, and thus a correct representation of energy metabolism appears crucial to metabolic modeling. However, we found that the majority of FBA models generated directly from genome sequences, as well as a minority of carefully curated models, are capable of generating energy out of thin air. These models charge energy metabolites such as ATP without any nutrient uptake. We named the corresponding sets of reactions “erroneous energy generating cycles” (EGCs) and developed a high-throughput algorithm for their identification. We found EGCs in 238 (68%) of 350 metabolic models from three different databases. We developed a second, fully automated method for EGC removal. Simulations on the corrected models typically showed growth rates that were 25% slower than in the original models, demonstrating the importance of checking metabolic model reconstructions for EGCs.
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Affiliation(s)
- Claus Jonathan Fritzemeier
- Institute for Computer Science and Cluster of Excellence on Plant Sciences, Heinrich Heine University, Düsseldorf, Germany
| | - Daniel Hartleb
- Institute for Computer Science and Cluster of Excellence on Plant Sciences, Heinrich Heine University, Düsseldorf, Germany
| | - Balázs Szappanos
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Balázs Papp
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Martin J. Lercher
- Institute for Computer Science and Cluster of Excellence on Plant Sciences, Heinrich Heine University, Düsseldorf, Germany
- * E-mail:
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9
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Nijemeisland M, Abdelmohsen LKEA, Huck WTS, Wilson DA, van Hest JCM. A Compartmentalized Out-of-Equilibrium Enzymatic Reaction Network for Sustained Autonomous Movement. ACS CENTRAL SCIENCE 2016; 2:843-849. [PMID: 27924313 PMCID: PMC5126709 DOI: 10.1021/acscentsci.6b00254] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Indexed: 05/04/2023]
Abstract
Every living cell is a compartmentalized out-of-equilibrium system exquisitely able to convert chemical energy into function. In order to maintain homeostasis, the flux of metabolites is tightly controlled by regulatory enzymatic networks. A crucial prerequisite for the development of lifelike materials is the construction of synthetic systems with compartmentalized reaction networks that maintain out-of-equilibrium function. Here, we aim for autonomous movement as an example of the conversion of feedstock molecules into function. The flux of the conversion is regulated by a rationally designed enzymatic reaction network with multiple feedforward loops. By compartmentalizing the network into bowl-shaped nanocapsules the output of the network is harvested as kinetic energy. The entire system shows sustained and tunable microscopic motion resulting from the conversion of multiple external substrates. The successful compartmentalization of an out-of-equilibrium reaction network is a major first step in harnessing the design principles of life for construction of adaptive and internally regulated lifelike systems.
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Affiliation(s)
- Marlies Nijemeisland
- Institute
for Molecules and Materials, Radboud University
Nijmegen, Heyendaalseweg
135, 6525 AJ Nijmegen, The Netherlands
| | - Loai K. E. A. Abdelmohsen
- Institute
for Molecules and Materials, Radboud University
Nijmegen, Heyendaalseweg
135, 6525 AJ Nijmegen, The Netherlands
| | - Wilhelm T. S. Huck
- Institute
for Molecules and Materials, Radboud University
Nijmegen, Heyendaalseweg
135, 6525 AJ Nijmegen, The Netherlands
- E-mail:
| | - Daniela A. Wilson
- Institute
for Molecules and Materials, Radboud University
Nijmegen, Heyendaalseweg
135, 6525 AJ Nijmegen, The Netherlands
- E-mail:
| | - Jan C. M. van Hest
- Institute
for Molecules and Materials, Radboud University
Nijmegen, Heyendaalseweg
135, 6525 AJ Nijmegen, The Netherlands
- Department
of Biomedical Engineering and Chemical Engineering & Chemistry, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands
- E-mail: ,
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10
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Arfuso F, Giannetto C, Rizzo M, Fazio F, Giudice E, Piccione G. Serum levels of mitochondrial uncoupling protein 1, leptin, and lipids during late pregnancy and the early postpartum period in mares. Theriogenology 2016; 86:1156-64. [DOI: 10.1016/j.theriogenology.2016.04.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 04/04/2016] [Accepted: 04/05/2016] [Indexed: 12/17/2022]
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11
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Ivanov VV, Shakhristova EV, Stepovaya EA, Nosareva OL, Fedorova TS, Ryazantseva NV, Novitsky VV. Effect of insulin, the glutathione system, and superoxide anion radical in modulation of lipolysis in adipocytes of rats with experimental diabetes. BIOCHEMISTRY (MOSCOW) 2015; 80:87-96. [PMID: 25754043 DOI: 10.1134/s0006297915010101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Spontaneous lipolysis was found to be increased in adipocytes of rats with alloxan-induced diabetes. In addition, isoproterenol-stimulated hydrolysis of triacylglycerols was inhibited against the background of oxidative stress and decreased redox-status of cells. A decrease in the ability of insulin to inhibit isoproterenol-stimulated lipolysis in adipocytes that were isolated from adipose tissue of rats with experimental diabetes was found, which shows a disorder in regulation of lipolysis in adipocytes by the hormone in alloxan-induced diabetes. Based on these findings, we concluded that there is an influence of reactive oxygen species, superoxide anion radical in particular, and redox potential of the glutathione system on molecular mechanisms of change in lipolysis intensity in rat adipocytes in alloxan-induced oxidative stress. Activation of spontaneous lipolysis under conditions of oxidative stress might be a reason for the high concentration of free fatty acids in blood plasma in experimental diabetes, and this may play a significant role in development of insulin resistance and appearance of complications of diabetes.
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Affiliation(s)
- V V Ivanov
- Siberian State Medical University, Tomsk, 634050, Russia.
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12
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Sridharan GV, Ullah E, Hassoun S, Lee K. Discovery of substrate cycles in large scale metabolic networks using hierarchical modularity. BMC SYSTEMS BIOLOGY 2015; 9:5. [PMID: 25884368 PMCID: PMC4349670 DOI: 10.1186/s12918-015-0146-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 01/26/2015] [Indexed: 11/10/2022]
Abstract
BACKGROUND A substrate cycle is a set of metabolic reactions, arranged in a loop, which does not result in net consumption or production of the metabolites. The cycle operates by transforming a cofactor, e.g. oxidizing a reducing equivalent. Substrate cycles have been found experimentally in many parts of metabolism; however, their physiological roles remain unclear. As genome-scale metabolic models become increasingly available, there is now the opportunity to comprehensively catalogue substrate cycles, and gain additional insight into this potentially important motif of metabolic networks. RESULTS We present a method to identify substrate cycles in the context of metabolic modules, which facilitates functional analysis. This method utilizes elementary flux mode (EFM) analysis to find potential substrate cycles in the form of cyclical EFMs, and combines this analysis with network partition based on retroactive (cyclical) interactions between reactions. In addition to providing functional context, partitioning the network into modules allowed exhaustive EFM calculations on smaller, tractable subnetworks that are enriched in metabolic cycles. Applied to a large-scale model of human liver metabolism (HepatoNet1), our method found not only well-known substrate cycles involving ATP hydrolysis, but also potentially novel substrate cycles involving the transformation of other cofactors. A key characteristic of the substrate cycles identified in this study is that the lengths are relatively short (2-13 reactions), comparable to many experimentally observed substrate cycles. CONCLUSIONS EFM computation for large scale networks remains computationally intractable for exhaustive substrate cycle enumeration. Our algorithm utilizes a 'divide and conquer' strategy where EFM analysis is performed on systematically identified network modules that are designed to be enriched in cyclical interactions. We find that several substrate cycles uncovered using our approach are not identified when the network is partitioned in a more generic manner based solely on connectivity rather than cycles, demonstrating the value of targeting motif searches to sub-networks replete with a topological feature that resembles the desired motif itself.
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Affiliation(s)
- Gautham Vivek Sridharan
- Department of Chemical and Biological Engineering, Tufts University, 4 Colby Street, Medford, MA, 02155, USA.
| | - Ehsan Ullah
- Department of Computer Science, Tufts University, 161 College Avenue, Medford, MA, 02155, USA.
| | - Soha Hassoun
- Department of Computer Science, Tufts University, 161 College Avenue, Medford, MA, 02155, USA.
| | - Kyongbum Lee
- Department of Chemical and Biological Engineering, Tufts University, 4 Colby Street, Medford, MA, 02155, USA.
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13
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Effectual comparison of quinoa and amaranth supplemented diets in controlling appetite; a biochemical study in rats. Journal of Food Science and Technology 2015; 52:6735-41. [PMID: 26396423 DOI: 10.1007/s13197-014-1691-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Revised: 12/02/2014] [Accepted: 12/16/2014] [Indexed: 10/24/2022]
Abstract
The objective of this study was to assess the efficacy of two current cynosure protein substitutes; quinoa and amaranth in controlling short term food intake and satiety in rats. Experimental rats were allotted to three groups (n = 8 per group) and fed with diets containing casein, quinoa and amaranth as major protein sources, with casein diet kept as control. At the end of the experiment it was observed that the rats ingesting quinoa and amaranth supplemented diets exhibited lesser food intake (p < 0.01) and lesser body weight gain significantly in amaranth (p < 0.05) as compared to control. They seemed to bring down plasma ghrelin levels while meliorating plasma leptin and cholecystokinin (CCK) levels postprandially (p < 0.01). Although both quinoa diet and amaranth diet were effective in improving blood glucose response and maintaining plasma free fatty acids (FFA) and general lipid profiles subsequently after the meal, amaranth diet showed significant effects when compared to control and amaranth diets. There was 15 % improvement in blood glucose profile in the amaranth group with respect to the control at 90 min, where as there was only 3.4 % improvement in the quinoa group. These findings provide a scientific rationale to consider incorporation of these modest cereals in a diet meant to fight against growing obesity and poverty.
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14
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Miller BF, Drake JC, Peelor FF, Biela LM, Geor R, Hinchcliff K, Davis M, Hamilton KL. Participation in a 1,000-mile race increases the oxidation of carbohydrate in Alaskan sled dogs. J Appl Physiol (1985) 2014; 118:1502-9. [PMID: 25150223 DOI: 10.1152/japplphysiol.00588.2014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 08/19/2014] [Indexed: 11/22/2022] Open
Abstract
The Alaskan Husky has been specifically bred for endurance performance and is capable of extreme endurance performance. We examined sled dogs in the trained state at the beginning of the race season and after a 1,600-km race (Iditarod). Our hypothesis was that lipids would be the predominant substrate during submaximal exercise in long-distance racing sled dogs, and a 1,600-km race would increase the reliance on lipids during an exercise bout at the same absolute exercise intensity. The experiments were completed over three testing periods, which were completed in January of two different years before participation in a 1,600-km race, or in March shortly after completion of a 1,600-km race. After determination of H(13)CO3 (-) recovery, the dogs were tested with primed continuous infusions of [1,1,2,3,3-(2)H]glycerol, [3-(13)C]lactate, or [6,6-(2)H2]glucose. During exercise, respiratory exchange ratio was significantly higher in raced (0.92 ± 0.01) compared with nonraced (0.87 ± 0.01) dogs. During exercise, glucose rate of appearance was potentially sustained by a large glycerol rate of disappearance with an increase in lactate rates of oxidation after a 1,600-km race. Therefore, contrary to our hypothesis, the sled dogs were dependent on carbohydrate energy sources, a reliance that increased further after participation in a 1,600-km race.
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Affiliation(s)
- Benjamin F Miller
- Department of Health and Exercise Science, Colorado State University, Fort Collins, Colorado;
| | - Joshua C Drake
- Department of Health and Exercise Science, Colorado State University, Fort Collins, Colorado
| | - Frederick F Peelor
- Department of Health and Exercise Science, Colorado State University, Fort Collins, Colorado
| | - Laurie M Biela
- Department of Health and Exercise Science, Colorado State University, Fort Collins, Colorado
| | - Raymond Geor
- Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan
| | - Kenneth Hinchcliff
- Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria, Australia; and
| | - Michael Davis
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, Oklahoma
| | - Karyn L Hamilton
- Department of Health and Exercise Science, Colorado State University, Fort Collins, Colorado
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15
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Perello M, Raingo J. Leptin activates oxytocin neurons of the hypothalamic paraventricular nucleus in both control and diet-induced obese rodents. PLoS One 2013; 8:e59625. [PMID: 23527232 PMCID: PMC3601091 DOI: 10.1371/journal.pone.0059625] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Accepted: 02/15/2013] [Indexed: 12/25/2022] Open
Abstract
The adipocyte-derived hormone leptin acts in the brain to reduce body weight and fat mass. Recent studies suggest that parvocellular oxytocin (OXT) neurons of the hypothalamic paraventricular nucleus (PVN) can mediate body weight reduction through inhibition of food intake and increased energy expenditure. However, the role of OXT neurons of the PVN as a primary target of leptin has not been investigated. Here, we studied the potential role of OXT neurons of the PVN in leptin-mediated effects on body weight regulation in fasted rats. We demonstrated that intracerebroventricular (ICV) leptin activates STAT3 phosphorylation in OXT neurons of the PVN, showed that this occurs in a subpopulation of OXT neurons that innervate the nucleus of the solitary tract (NTS), and provided further evidence suggesting a role of OXT to mediate leptin's actions on body weight. In addition, our results indicated that OXT neurons are responsive to ICV leptin and mediate leptin effects on body weight in diet induced obese (DIO) rats, which are resistant to the anorectic effects of the hormone. Thus, we conclude that leptin targets a specific subpopulation of parvocellular OXT neurons of the PVN, and that this action may be important for leptin's ability to reduce body weight in both control and obese rats.
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Affiliation(s)
- Mario Perello
- Laboratory of Neurophysiology, Argentine Research Council and Scientific Research Commission of the Province of Buenos Aires, La Plata, Buenos Aires, Argentina.
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16
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Weber JM, Reidy SP. Extending food deprivation reverses the short-term lipolytic response to fasting: role of the triacylglycerol/fatty acid cycle. ACTA ACUST UNITED AC 2012; 215:1484-90. [PMID: 22496284 DOI: 10.1242/jeb.062992] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The effects of short-term food deprivation on lipid metabolism are well documented, but little is known about prolonged fasting. This study monitored the kinetics of glycerol (rate of appearance, R(a) glycerol) and non-esterified fatty acids (R(a) NEFA) in fasting rabbits. Our goals were to determine whether lipolysis is stimulated beyond values seen for short-term fasting, and to characterize the roles of primary (intracellular) and secondary (with transit through the circulation) triacylglycerol/fatty acid cycling (TAG/FA cycling) in regulating fatty acid allocation to oxidation or re-esterification. R(a) glycerol (9.62±0.72 to 15.29±0.96 μmol kg(-1) min(-1)) and R(a) NEFA (18.05±2.55 to 31.25±1.93 μmol kg(-1) min(-1)) were stimulated during the first 2 days of fasting, but returned to baseline after 4 days. An initial increase in TAG/FA cycling was followed by a reduction below baseline after 6 days without food, with primary and secondary cycling contributing to these responses. We conclude that the classic activation of lipolysis caused by short-term fasting is abolished when food deprivation is prolonged. High rates of re-esterification may become impossible to sustain, and TAG/FA cycling could decrease to reduce its cost to 3% of total energy expenditure. Throughout prolonged fasting, fatty acid metabolism gradually shifts towards increased oxidation and reduced re-esterification. Survival is achieved by pressing fuel selection towards the fatty acid dominance of energy metabolism and by slowing substrate cycles to assist metabolic suppression. However, TAG/FA cycling remains active even after prolonged fasting, suggesting that re-esterification is a crucial mechanism that cannot be stopped without harmful consequences.
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Affiliation(s)
- Jean-Michel Weber
- Biology Department, University of Ottawa, 30 Marie Curie, Ottawa, Ontario, Canada K1N 6N5.
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17
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Abstract
OBJECTIVE Several gastrointestinal peptides are now recognized to have target functions beyond the intestinal wall, including effects on adipocytes. Secretin (SEC), one of the first identified, has not been evaluated in this context. METHODS Using cultured 3T3-L1 preadipocytes, adipocytes and primary rat adipocytes we evaluated the effect of SEC on cell proliferation, mitochondrial activity, differentiation, triglyceride (TG) synthesis, lipolysis as well expression of the SEC receptor (SCTR) in rodent and human adipose tissues. RESULTS In preadipocytes, SEC significantly increased mitochondrial activity (115%; P<0.01), thymidine incorporation (149.7%; P<0.05) and C/EBPβ expression (123.4%; P<0.05). During standard differentiation, SCTR mRNA increased up to a maximum of ninefold (P<0.001). In human adipose tissue, SCTR correlated with body mass index and plasma insulin, and SCTR mRNA expression was also detected in rat adipose tissues. SEC supplementation during differentiation enhanced TG accumulation (+138%; P<0.01). In mature adipocytes, SEC increased fatty acid (FA) uptake (186%; P<0.01), adiponectin and monocyte chemotactic protein-1 secretion (+142% and +149%, respectively; P<0.05) and mRNA expression of PPARγ (+206%; P<0.01), FABP4 (+164%; P<0.001), DGAT-1 (+144%; P<0.01), adiponectin (+138%; P<0.001) and CD36 (+149%; P<0.05). In primary rat adipocytes, SEC also increased FA uptake (137%; P<0.05). Pretreatment with a SEC antagonist impaired SEC-induced FA uptake and cAMP accumulation. SEC treatment simultaneously stimulated lipolysis measured as glycerol release in 3T3-L1 adipocytes and rat adipose tissue. CONCLUSION The present results suggest that SEC is a potent modulator of adipocyte functions, demonstrating overall a role in enhanced substrate cycling.
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18
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Modulator recognition factor-2 regulates triglyceride metabolism in adipocytes. Biochem Biophys Res Commun 2009; 391:277-81. [PMID: 19913508 DOI: 10.1016/j.bbrc.2009.11.049] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Accepted: 11/07/2009] [Indexed: 11/20/2022]
Abstract
Mice lacking modulator recognition factor-2 (Mrf-2; ARID5B) have less fat in brown and white adipose tissues, partly because of a defect in adipocyte differentiation. We have also shown that knockdown of Mrf-2 decreases the expression of the adipogenic transcription factors C/EBPalpha and PPARgamma, and inhibits adipogenesis in 3T3-L1 preadipocytes. Since these transcription factors may also contribute to the maintenance of adipocyte function, we examined the effects of siRNA targeted to Mrf-2 on triglyceride metabolism in mature 3T3-L1-derived adipocytes. As it did in differentiating adipocytes, knockdown of Mrf-2 decreased the expression of both C/EBPalpha and PPARgamma. Knockdown of Mrf-2 also activated both lipolysis and triglyceride synthesis, and caused a significant increase in the ratio of glycerol release to free fatty acid release. This suggests that knockdown of Mrf-2 increases the rate of fatty acid recycling in 3T3-L1-derived adipocytes. Continual cycling of fatty acids through lipolysis and triglyceride synthesis could lead to dissipation of energy. Therefore, the activation of such a futile cycle via the suppression of Mrf-2 could be an effective treatment for obesity and diabetes.
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19
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Vaillancourt E, Haman F, Weber JM. Fuel selection in Wistar rats exposed to cold: shivering thermogenesis diverts fatty acids from re-esterification to oxidation. J Physiol 2009; 587:4349-59. [PMID: 19622609 DOI: 10.1113/jphysiol.2009.175331] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
This study characterizes the effects of shivering thermogenesis on metabolic fuel selection in Wistar rats. Because lipids account for most of the heat produced, we have investigated: (1) whether the rate of appearance of non-esterified fatty acids (R(a) NEFAs) is stimulated by shivering, (2) whether mono-unsaturated (oleate) and saturated fatty acids (palmitate) are affected similarly, and (3) whether the partitioning between fatty acid oxidation and re-esterification is altered by cold exposure. Fuel oxidation was measured by indirect calorimetry and fatty acid mobilization by continuous infusion of 9,10-[(3)H]oleate and 1-[(14)C]palmitate. During steady-state cold exposure, results show that total heat production is unequally shared by the oxidation of lipids (52% of metabolic rate), carbohydrates (35%) and proteins (13%), and that the same fuel selection pattern is observed at all shivering intensities. All previous research shows that mammals stimulate R(a) NEFA to support exercise or shivering. In contrast, results reveal that the R(a) NEFA of the rat remains constant during cold exposure (55 micromol kg(1) min(1)). No preferential use of mono-unsaturated over saturated fatty acids could be demonstrated. The rat decreases its rate of fatty acid re-esterification from 48.4 +/- 6.4 to 19.6 +/- 6.3 micromol kg(1) min(1) to provide energy to shivering muscles. This study is the first to show that mammals do not only increase fatty acid availability for oxidation by stimulating R(a) NEFA. Reallocation of fatty acids from re-esterification to oxidation is a novel, alternative strategy used by the rat to support shivering.
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Affiliation(s)
- Eric Vaillancourt
- University of Ottawa, Department of Biology, 30 Marie-Curie, PO Box 450, Station A, Ottawa, Ontario, Canada K1N 6N5.
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20
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Wijers SLJ, Saris WHM, van Marken Lichtenbelt WD. Recent advances in adaptive thermogenesis: potential implications for the treatment of obesity. Obes Rev 2009; 10:218-26. [PMID: 19021870 DOI: 10.1111/j.1467-789x.2008.00538.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Large inter-individual differences in cold-induced (non-shivering) and diet-induced adaptive thermogenesis exist in animals and humans. These differences in energy expenditure can have a large impact on long-term energy balance and thus body weight (when other factors remain stable). Therefore, the level of adaptive thermogenesis might relate to the susceptibility to obesity; efforts to increase adaptive thermogenesis might be used to treat obesity. In small mammals, the main process involved is mitochondrial uncoupling in brown adipose tissue (BAT), which is regulated by the sympathetic nervous system. For a long time, it was assumed that mitochondrial uncoupling is not a major physiological contributor to adaptive thermogenesis in adult humans. However, several studies conducted in recent years suggest that mitochondrial uncoupling in BAT and skeletal muscle tissue in adult humans can be physiologically significant. Other mechanisms besides mitochondrial uncoupling that might be involved are futile calcium cycling, protein turnover and substrate cycling. In conjunction with recent advances on signal transduction studies, this knowledge makes manipulation of adaptive thermogenesis a more realistic option and thus a pharmacologically interesting target to treat obesity.
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Affiliation(s)
- S L J Wijers
- Department of Human Biology, Nutrition and Toxicology Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands.
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21
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Magnoni L, Vaillancourt E, Weber JM. In vivoregulation of rainbow trout lipolysis by catecholamines. J Exp Biol 2008; 211:2460-6. [DOI: 10.1242/jeb.018143] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
SUMMARYLipolysis provides fatty acids that support key life processes by functioning as membrane components, oxidative fuels and metabolic signals. It is commonly measured as the rate of appearance of glycerol(Ra glycerol). Its in vivo regulation by catecholamines has been thoroughly investigated in mammals, but little information is available for ectotherms. Therefore, the goals of this study were, first, to characterize the effects of the catecholamines norepinephrine(NE) and epinephrine (Epi) on the lipolytic rate of intact rainbow trout(Oncorhynchus mykiss) and, second, to determine whether the plasma glycerol concentration is a reliable index of Ra glycerol. Our results show that baseline Ra glycerol (4.6±0.4μmol kg–1 min–1) is inhibited by NE(–56%), instead of being stimulated, as in mammals, whereas Epi has the same activating effect in both groups of vertebrates (+167%). NE-induced inhibition of fish lipolysis might play a particularly important role during aquatic hypoxia, when survival often depends on regulated metabolic depression. The plasma glycerol concentration is a poor predictor of Ra glycerol, and it should not be used as an index of lipolysis. Trout maintain a particularly high baseline lipolytic rate because only 13% of the fatty acids provided are sufficient to support total energy expenditure, whereas the remaining fatty acids must undergo reesterification(87%).
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Affiliation(s)
- Leonardo Magnoni
- Biology Department, University of Ottawa, 30 Marie Curie, Ottawa,Ontario, Canada, K1N 6N5
| | - Eric Vaillancourt
- Biology Department, University of Ottawa, 30 Marie Curie, Ottawa,Ontario, Canada, K1N 6N5
| | - Jean-Michel Weber
- Biology Department, University of Ottawa, 30 Marie Curie, Ottawa,Ontario, Canada, K1N 6N5
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22
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Vaillancourt E, Weber JM. Lipid mobilization of long-distance migrant birds in vivo: the high lipolytic rate of ruff sandpipers is not stimulated during shivering. J Exp Biol 2007; 210:1161-9. [PMID: 17371915 DOI: 10.1242/jeb.003012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
For long migrations, birds must rely on high flux capacities at all steps of lipid metabolism, from the mobilization of adipose reserves to fatty acid oxidation in flight muscle mitochondria. Substrate kinetics and indirect calorimetry were used to investigate key parameters of lipid metabolism in a highly aerobic shorebird: the ruff sandpiper Philomachus pugnax. In this study, we have quantified the effects of cold exposure because such measurements are presently impossible during flight. Lipolytic rate was monitored by continuous infusion of 2-[3H]-glycerol and lipid oxidation by respirometry. Plasma lipid concentrations (non-esterified fatty acids, neutral lipids and phospholipids) and their fatty acid composition were also measured to assess whether cold exposure causes selective metabolism of specific lipids. Results show that shivering leads to a 47% increase in metabolic rate (44.4±3.8 ml O2kg–1min–1 to 65.2±8.1 ml O2kg–1 min–1), almost solely by stimulating lipid oxidation (33.3± 3.3 ml O2 kg–1min–1 to 48.2±6.8 ml O2kg–1 min–1) because carbohydrate oxidation remains close to 11.5± 0.5 ml O2 kg–1min–1. Sandpipers support an unusually high lipolytic rate of 55–60 μmol glycerol kg–1 min–1. Its stimulation above thermoneutral rates is unnecessary during shivering when the birds are still able to re-esterify 50% of released fatty acids. No changes in plasma lipid composition were observed, suggesting that cold exposure does not lead to selective metabolism of particular fatty acids. This study provides the first measurements of lipolytic rate in migrant birds and shows that their capacity for lipid mobilization reaches the highest values measured to date in vertebrates. Extending the limits of conventional lipid metabolism has clearly been necessary to achieve long-distance migrations.
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Affiliation(s)
- Eric Vaillancourt
- Biology Department, University of Ottawa, 30 Marie Curie, Ottawa, Ontario, K1N 6N5, Canada
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23
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Schaeffer PJ, Villarin JJ, Pierotti DJ, Kelly DP, Lindstedt SL. Cost of transport is increased after cold exposure in Monodelphis domestica: training for inefficiency. ACTA ACUST UNITED AC 2006; 208:3159-67. [PMID: 16081613 DOI: 10.1242/jeb.01703] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Monodelphis domestica (Didelphidae: Marsupialia) lacks brown adipose tissue and thus relies on skeletal muscle as its primary thermogenic organ. Following cold exposure, the aerobic capacity of skeletal muscle in these animals is greatly increased. We investigated the effects of this plastic response to thermogenesis on locomotion and muscle mechanics. In cold-exposed animals, cost of transport was 15% higher than in controls but was unaffected by exercise training. Twitch kinetics in isolated semitendinosus muscles of cold-exposed animals were characteristic of slow-oxidative fiber types. Both time-to-peak tension and half-relaxation time were longer and maximal shortening velocity was slower following cold exposure compared to either thermoneutral controls or exercise-trained animals. Further, muscles from the cold-exposed animals had greater fatigue resistance than either control or exercise-trained animals, indicating greater oxidative capacity. Finally, we identified an uncoupling protein 3 homologue, whose gene expression was upregulated in skeletal muscle of cold-exposed Monodelphis domestica. Cold exposure provided a potent stimulus for muscle plasticity, driving a fast-to-slow transition more effectively than exercise training. However, linked to the dramatic shift in muscle properties is an equally dramatic increase in whole animal muscle energetics during locomotion, suggesting an uncoupled state, or 'training for inefficiency'.
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Affiliation(s)
- Paul J Schaeffer
- Department of Biological Sciences, Physiology and Functional Morphology Group, Northern Arizona University, Flagstaff, AZ 86011, USA.
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24
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Dulloo AG. A role for suppressed skeletal muscle thermogenesis in pathways from weight fluctuations to the insulin resistance syndrome. ACTA ACUST UNITED AC 2006; 184:295-307. [PMID: 16026421 DOI: 10.1111/j.1365-201x.2005.01466.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
An impressive body of epidemiological evidence suggests that a history of large perturbations in body weight earlier in life, independently of excess weight, is a risk factor for later development of insulin-related complications, namely central obesity, type 2 diabetes and cardiovascular disease. Such an increased risk has been reported in men and women who in young adulthood experienced weight fluctuations that involved weight recovery after weight loss caused by disease, famine or voluntary 'yoyo' dieting, and is particularly strong when the weight fluctuations occurred much earlier in life and are characterized by catch-up growth after foetal and/or neonatal growth retardation. As the phase of weight recovery/catch-up growth is associated with both hyperinsulinaemia and an accelerated rate for recovering fat mass (i.e. catch-up fat), the questions arise as to whether, why and how processes that regulate catch-up fat might predispose to hyperinsulinaemia and to insulin-related diseases. In addressing these issues, this paper first reviews evidence for the existence of an adipose-specific control of thermogenesis, whose suppression contributes to the phenomenon of catch-up fat during weight recovery/catch-up growth. It subsequently concentrates upon recent findings suggesting that: (i) such suppression of thermogenesis directed at catch-up fat is accompanied by a redistribution of glucose from skeletal muscle to white adipose tissue, and (ii) substrate cycling between de novo lipogenesis and lipid oxidation can operate as a thermogenic effector in skeletal muscle in response to signalling interactions between leptin and insulin - two key 'adiposity' hormones implicated in the peripheral control of substrate metabolism. These new findings are integrated into the proposal that, in its 'evolutionary adaptive' role to spare glucose for rapid rebuilding of the fat stores, suppressed thermogenesis in skeletal muscle - via inhibition of substrate cycling between de novo lipogenesis and lipid oxidation - confers to the phase of weight recovery/catch-up growth its high sensitivity towards the development of insulin resistance and hyperinsulinaemia, and hence towards diseases that are clustered around the insulin resistance syndrome.
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Affiliation(s)
- A G Dulloo
- Division of Physiology, Department of Medicine, University of Fribourg, Fribourg, Switzerland.
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25
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Solinas G, Summermatter S, Mainieri D, Gubler M, Montani JP, Seydoux J, Smith SR, Dulloo AG. Corticotropin-releasing hormone directly stimulates thermogenesis in skeletal muscle possibly through substrate cycling between de novo lipogenesis and lipid oxidation. Endocrinology 2006; 147:31-8. [PMID: 16210362 DOI: 10.1210/en.2005-1033] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The mechanisms by which CRH and related peptides (i.e. the CRH/urocortin system) exert their control over thermogenesis and weight regulation have until now focused only upon their effects on brain centers controlling sympathetic outflow. Using a method that involves repeated oxygen uptake determinations in intact mouse skeletal muscle, we report here that CRH can act directly on skeletal muscle to stimulate thermogenesis, an effect that is more pronounced in oxidative than in glycolytic muscles and that can be inhibited by a selective CRH-R2 antagonist or blunted by a nonselective CRH receptor antagonist. This thermogenic effect of CRH can also be blocked by interference along pathways of de novo lipogenesis and lipid oxidation, as well as by inhibitors of phosphatidylinositol 3-kinase or AMP-activated protein kinase. Taken together, these studies demonstrate that CRH can directly stimulate thermogenesis in skeletal muscle, and in addition raise the possibility that this thermogenic effect, which requires both phosphatidylinositol 3-kinase and AMP-activated protein kinase signaling, might occur via substrate cycling between de novo lipogenesis and lipid oxidation. The effect of CRH in directly stimulating thermogenesis in skeletal muscle underscores a potentially important peripheral role for the CRH/urocortin system in the control of thermogenesis in this tissue, in its protection against excessive intramyocellular lipid storage, and hence against skeletal muscle lipotoxicity and insulin resistance.
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Affiliation(s)
- G Solinas
- Division of Physiology, Department of Medicine, University of Fribourg, Fribourg, Switzerland
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26
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Rossi AS, Lombardo YB, Lacorte JM, Chicco AG, Rouault C, Slama G, Rizkalla SW. Dietary fish oil positively regulates plasma leptin and adiponectin levels in sucrose-fed, insulin-resistant rats. Am J Physiol Regul Integr Comp Physiol 2005; 289:R486-R494. [PMID: 16014450 DOI: 10.1152/ajpregu.00846.2004] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Insulin resistance and adiposity induced by a long-term sucrose-rich diet (SRD) in rats could be reversed by fish oil (FO). Regulation of plasma leptin and adiponectin levels, as well as their gene expression, by FO might be implicated in these findings. This study was designed to evaluate the long-term regulation of leptin and adiponectin by dietary FO in a dietary model of insulin resistance induced by long-term SRD in rats and to determine their impact on adiposity and insulin sensitivity. Rats were randomized to consume a control diet (CD; n = 25) or an SRD (n = 50) for 7 mo. Subsequently, the SRD-fed rats were randomized to consume SRD+FO or to continue on SRD for an additional 2 mo. Long-term SRD induced overweight and decreased both plasma leptin and adiponectin levels without change in gene expression. Dyslipidemia, adiposity, and insulin resistance accompanied these modifications. Shifting the source of fat to FO for 2 mo increased plasma levels of both adipokines, reversed insulin resistance and dyslipidemia, and improved adiposity. These results were not associated with modifications in gene expression. These results suggest that increasing both adipokines by dietary FO might play an essential role in the normalization of insulin resistance and adiposity in dietary-induced, insulin-resistant models.
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Affiliation(s)
- Andrea S Rossi
- Dept. of Biochemistry, School of Biochemistry, University of Litoral, Ciudad Universitaria, Paraje El Pozo C.C 242, 3000 Santa Fe, Argentina
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27
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Sanchez VC, Goldstein J, Stuart RC, Hovanesian V, Huo L, Munzberg H, Friedman TC, Bjorbaek C, Nillni EA. Regulation of hypothalamic prohormone convertases 1 and 2 and effects on processing of prothyrotropin-releasing hormone. J Clin Invest 2004; 114:357-69. [PMID: 15286802 PMCID: PMC484982 DOI: 10.1172/jci21620] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2004] [Accepted: 06/15/2004] [Indexed: 01/19/2023] Open
Abstract
Regulation of energy balance by leptin involves regulation of several neuropeptides, including thyrotropin-releasing hormone (TRH). Synthesized from a larger inactive precursor, its maturation requires proteolytic cleavage by prohormone convertases 1 and 2 (PC1 and PC2). Since this maturation in response to leptin requires prohormone processing, we hypothesized that leptin might regulate hypothalamic PC1 and PC2 expression, ultimately leading to coordinated processing of prohormones into mature peptides. Using hypothalamic neurons, we found that leptin stimulated PC1 and PC2 mRNA and protein expression and also increased PC1 and PC2 promoter activities in transfected 293T cells. Starvation of rats, leading to low serum leptin levels, decreased PC1 and PC2 gene and protein expression in the paraventricular nucleus (PVN) of the hypothalamus. Exogenous administration of leptin to fasted animals restored PC1 levels in the median eminence (ME) and the PVN to approximately the level found in fed control animals. Consistent with this regulation of PCs in the PVN, concentrations of TRH in the PVN and ME were substantially reduced in the fasted animals relative to the fed animals, and leptin reversed this decrease. Further analysis showed that proteolytic cleavage of pro-thyrotropin-releasing hormone (proTRH) at known PC cleavage sites was reduced by fasting and increased in animals given leptin. Combined, these findings suggest that leptin-dependent stimulation of hypothalamic TRH expression involves both activation of trh transcription and stimulation of PC1 and PC2 expression, which lead to enhanced processing of proTRH into mature TRH.
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Affiliation(s)
- Vanesa C Sanchez
- Division of Endocrinology, Department of Medicine, Brown Medical School, Rhode Island Hospital, Providence, Rhode Island 02903, USA
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Evans SA, Overton JM, Alshingiti A, Levenson CW. Regulation of metabolic rate and substrate utilization by zinc deficiency. Metabolism 2004; 53:727-32. [PMID: 15164319 DOI: 10.1016/j.metabol.2004.01.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The trace metal zinc (Zn) is essential for the catalytic activity of many enzymes involved in energy nutrient metabolism and appears to regulate hormones, such as insulin, leptin, and thyroid hormone that play key roles in metabolism. Thus, this study used the continuous monitoring of oxygen consumption, carbon dioxide production, locomotion, and food intake to determine the effect of dietary Zn restriction on metabolic rate (MR), basal metabolic rate (BMR), and respiratory quotient (RQ). Rats were fed a Zn-adequate (ZA, 28 ppm) or Zn-deficient (ZD, <1 ppm) diet for 8 days, followed by a 4-day refeeding period. To control for reductions in food intake that characteristically occur in ZD rats, an additional group was pair-fed (PF) the same amount ZA food eaten by ZD rats. The mean caloric intake of ZD rats was significantly lower than ZA rats by day 3. By day 8, ZD and PF rats weighed 64% and 67% of ZA rats, respectively, (P <.01). Pair feeding resulted in increased locomotor activity, such that the distance traveled for PF rats (316 +/- 43 m) was 6 times that of ZA (53 +/- 6 m). Despite the fact that PF and ZD rats had the same food intake, there was no increase in locomotor activity in ZD rats suggesting that the mechanisms responsible for increased physical activity in food restricted animals may be Zn dependent. Furthermore, differences in activity between PF and ZD animals were not reflected in differences in MR. Both ZD and PF significantly reduced MR compared with ZA rats beginning on day 4. There was a significant relationship between RQ and caloric intake (r = 0.708, P <.01), but no specific effect of Zn status. Thus, while there may be an effect of Zn on locomotion and the energetic cost of activity, it appears that the most profound effect of Zn status on MR and substrate utilization is the result of Zn deficiency-induced anorexia.
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Affiliation(s)
- Stephanie A Evans
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, USA
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Banks WA, Coon AB, Robinson SM, Moinuddin A, Shultz JM, Nakaoke R, Morley JE. Triglycerides induce leptin resistance at the blood-brain barrier. Diabetes 2004; 53:1253-60. [PMID: 15111494 DOI: 10.2337/diabetes.53.5.1253] [Citation(s) in RCA: 366] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Obesity is associated with leptin resistance as evidenced by hyperleptinemia. Resistance arises from impaired leptin transport across the blood-brain barrier (BBB), defects in leptin receptor signaling, and blockades in downstream neuronal circuitries. The mediator of this resistance is unknown. Here, we show that milk, for which fats are 98% triglycerides, immediately inhibited leptin transport as assessed with in vivo, in vitro, and in situ models of the BBB. Fat-free milk and intralipid, a source of vegetable triglycerides, were without effect. Both starvation and diet-induced obesity elevated triglycerides and decreased the transport of leptin across the BBB, whereas short-term fasting decreased triglycerides and increased transport. Three of four triglycerides tested intravenously inhibited transport of leptin across the BBB, but their free fatty acid constituents were without effect. Treatment with gemfibrozil, a drug that specifically reduces triglyceride levels, reversed both hypertriglyceridemia and impaired leptin transport. We conclude that triglycerides are an important cause of leptin resistance as mediated by impaired transport across the BBB and suggest that triglyceride-mediated leptin resistance may have evolved as an anti-anorectic mechanism during starvation. Decreasing triglycerides may potentiate the anorectic effect of leptin by enhancing leptin transport across the BBB.
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Affiliation(s)
- William A Banks
- Department of Internal Medicine, Division of Geriatrics, Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, St. Louis University School of Medicine, 915 N. Grand Boulevard, St. Louis, MO 631056, USA.
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30
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Commerford SR, Peng L, Dubé JJ, O'Doherty RM. In vivo regulation of SREBP-1c in skeletal muscle: effects of nutritional status, glucose, insulin, and leptin. Am J Physiol Regul Integr Comp Physiol 2004; 287:R218-27. [PMID: 15001432 DOI: 10.1152/ajpregu.00377.2003] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Sterol regulatory element binding protein-1c (SREBP-1c), a transcription factor that is important for mediating insulin effects on metabolic gene expression in liver during the fasted-to-fed transition, is also expressed in skeletal muscle. However, the regulation and role of SREBP-1c in skeletal muscle are poorly understood. The present study compared the effects of nutritional status, physiological hyperinsulinemic clamps, and adenovirus-mediated hyperleptinemia (HLEP) in rats on expression of SREBP-1c and other metabolic genes in skeletal muscle. Three- and 6-h refeeding of 18-h-fasted animals increased levels of SREBP-1c mRNA and the SREBP-1 protein (full length and mature) in gastrocnemius muscle (P < 0.05). Fatty acid synthase (FAS) and hexokinase II (HKII) mRNA levels were also increased by refeeding, and uncoupling protein 3 (UCP3) mRNA level was decreased (all P < 0.05). Surprisingly, 3-h hyperinsulinemic clamps did not increase gastrocnemius muscle SREBP-1c and FAS mRNA levels or SREBP-1 protein levels but did increase HKII mRNA levels and decrease UCP3 mRNA levels (P < 0.05). HLEP reduced refeeding-induced increases of SREBP-1c and FAS mRNA levels but did not reduce the level of SREBP-1 protein. We conclude that 1) skeletal muscle SREBP-1c gene expression is regulated by nutritional status in a fashion similar to that observed in liver and adipose tissue, 2) physiological hyperinsulinemia is not sufficient to imitate the effects of refeeding on SREBP-1c gene expression, and 3) leptin suppresses refeeding effects on SREBP-1c mRNA levels.
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Affiliation(s)
- S Renee Commerford
- Department of Medicine, Division of Endocrinology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania 15261, USA
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Ajuwon KM, Kuske JL, Anderson DB, Hancock DL, Houseknecht KL, Adeola O, Spurlock ME. Chronic leptin administration increases serum NEFA in the pig and differentially regulates PPAR expression in adipose tissue11Purdue University Agriculture Research Program #16748. J Nutr Biochem 2003; 14:576-83. [PMID: 14559108 DOI: 10.1016/s0955-2863(03)00104-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Two in vivo studies were conducted with pigs to determine the effects of exogenous leptin on the expression of peroxisome proliferator activated receptors (PPAR), and on serum concentrations of selected metabolites and hormones. Initially, leptin was administered i.m. to young pigs for 15 days at 0 (control), 0.003 (low), 0.01 (medium) and 0.03 (high) mg. kg(-1). day(-1). There was no leptin effect on serum glucose (P > 0.84), triglycerides (P > 0.69), non-esterified fatty acids (NEFA, P > 0.53), or glycerol (P > 0.33). Leptin at the intermediate and high doses depressed adipose expression of both PPARgamma1 (P < 0.06) and PPARgamma2 (P < 0.01). In a second study, we used a paired-feeding experimental design to determine the effects of a higher dose of leptin (0.05 mg. kg(-1). day(-1)) on serum metabolites and PPAR expression in selected tissues. At this dose, leptin increased (P < 0.0001) serum NEFA concentrations relative to both the ad libitum and pair-fed control groups. However, in this study, there was no difference in the expression of PPARgamma1 in adipose tissue, but PPARgamma2 mRNA was upregulated by leptin (P < 0.08). In contrast, leptin had no impact on the expression of PPARalpha in liver, skeletal muscle or adipose tissue. Adipose tissue explants were also incubated with leptin to assess the effect on PPARgamma expression, in vitro. The abundance of PPARgamma1 mRNA (P < 0.05) was increased after 24 hr of exposure, but the effect of leptin on gamma2 was not significant (P > 0.24). The lipolytic effect of leptin was also evaluated in vitro using isolated adipocytes. In keeping with the increase in serum NEFA concentrations in vivo, leptin stimulated lipolysis in vitro, increasing glycerol concentrations in the medium to about 219% of that in basal (non-treated) culture medium after 8 hr of incubation. Collectively, the data presented herein indicate that leptin modulates lipid metabolism in the pig, but that PPARalpha expression is not a parallel target of leptin as it is in rodent models. The regulation of PPARgamma by leptin seems complex in that it varied in relation to dose in vivo, and may be impacted by in vitro vs. in vivo circumstances.
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Affiliation(s)
- Kolapo M Ajuwon
- Department of Animal Sciences, Purdue University, West Lafayette, IN, USA
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Abstract
Intensive selection by poultry breeders over many generations for economically important production traits such as growth rate and meat production has been accompanied by significant changes in feed intake and energy balance. For example, the modern commercial broiler, selected for rapid growth and enhanced muscle mass, does not adequately regulate voluntary feed intake to achieve energy balance. When given unrestricted access to feed, broilers exhibit hyperphagia leading to an excessive accumulation of energy (fat) stores, making these birds prone to obesity and other health-related problems. Humoral and neural pathways have been identified and studied in mammals that link appetite and energy balance. A series of highly integrated regulatory mechanisms exists for both of these processes involving complex interactions between peripheral tissues and the central nervous system. Within the central nervous system, the brainstem and the hypothalamus play critical roles in the regulation of feed intake and energy balance. Genes encoding key regulatory factors such as hormones, neuropeptides, receptors, enzymes, transcription factors, and binding/transport proteins constitute the molecular basis for regulatory systems that derive from integrated sensing, signaling, and metabolic pathways. However, we do not yet have a complete understanding of the genetic basis for this regulation in poultry. This review examines what is currently known about the regulation of feed intake and energy balance in poultry. A better understanding of the genes associated with controlling feed intake and energy balance and how their expression is regulated by nutritional and hormonal stimuli will offer new insights into current poultry breeding and management practices.
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Affiliation(s)
- M P Richards
- USDA, ARS, Growth Biology Laboratory, 10300 Baltimore Avenue, Building 200, Room 206, BARC-East, Beltsville, MD 20705-2350, USA.
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Holtenius K, Agenäs S, Delavaud C, Chilliard Y. Effects of feeding intensity during the dry period. 2. Metabolic and hormonal responses. J Dairy Sci 2003; 86:883-91. [PMID: 12703625 DOI: 10.3168/jds.s0022-0302(03)73671-6] [Citation(s) in RCA: 185] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The metabolic response to different feeding levels during the dry period was studied in 24 multiparous dairy cows of the Swedish Red and White breed. The cows represented two lines, selected for high or low milk fat percentage, at the same amount of energy produced in milk. The cows were fed one of three different amounts of the same total mixed diet during the dry period, starting 8 wk prior to the expected parturition. The rations provided 71, 106, or 177 MJ metabolizable energy per day. After parturition the cows were offered another total mixed diet ad libitum for the first 12 wk of lactation. Glucose challenges were performed 3 wk prior to and 3 wk after parturition. Prepartum the glucose clearance rate was related to feeding level. Insulin response to the glucose challenge was reduced during the postpartum period, compared to the prepartum period. During about 6 wk prepartum, the insulin level in plasma was related to feeding level. At the sampling 3 wk prior to parturition the plasma level of leptin also was related to the feeding level. After parturition both leptin and insulin were reduced. In early lactation plasma leptin concentration was not related to adiposity as reflected by body condition scoring. It was suggested that lactation as such affected the leptin concentration in plasma.
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Affiliation(s)
- K Holtenius
- Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden.
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Xia Z, Sniderman AD, Cianflone K. Acylation-stimulating protein (ASP) deficiency induces obesity resistance and increased energy expenditure in ob/ob mice. J Biol Chem 2002; 277:45874-9. [PMID: 12244109 DOI: 10.1074/jbc.m207281200] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Acylation-stimulating protein (ASP) acts as a paracrine signal to increase triglyceride synthesis in adipocytes. ASP administration results in more rapid postprandial lipid clearance. In mice, C3 (the precursor to ASP) knockout results in ASP deficiency and leads to reduced body fat and leptin levels. The protective potential of ASP deficiency against obesity and involvement of the leptin pathway were examined in ob/ob C3(-/-) double knockout mice (2KO). Compared with age-matched ob/ob mice, 2KO mice had delayed postprandial triglyceride and fatty acid clearance; associated with decreased body weight (4-17 weeks age: male: -13.7%, female: -20.6%, p < 0.0001) and HOMA (homeostasis model assessment) index (-37.7%), suggesting increased insulin sensitivity. By contrast, food intake in 2KO mice was +9.1% higher over ob/ob mice (p < 0.001, 2KO 5.1 +/- 0.2 g/day, ob/ob 4.5 +/- 0.2 g/day, wild type 2.6 +/- 0.1 g/day). The hyperphagia/leanness was balanced by a 28.5% increase in energy expenditure (oxygen consumption: 2KO, 131 +/- 8.9 ml/h; ob/ob, 102 +/- 4.5 ml/h; p < 0.01; wild type, 144 +/- 8.9 ml/h). These results suggest that the ASP regulation of energy storage may influence energy expenditure and dynamic metabolic balance.
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Affiliation(s)
- Zhunan Xia
- Mike Rosenbloom Laboratory for Cardiovascular Research, McGill University Health Center, Montreal, Quebec H3A 1A1, Canada
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Abstract
The development of cachexia is commonly seen in many pathological states and is associated with a markedly impaired prognosis. Loss of fat tissue appears to be of particular pathophysiological importance in this setting. Lipolysis is closely regulated in health; the major established pathways involving catecholamines (stimulation of lipolysis) and insulin (inhibition of lipolysis). The wasting process in cachexia is associated with marked metabolic dysfunction, and loss of this tight regulatory control. Natriuretic peptides are a family of related peptides with important vasodilatory, natriuretic and diuretic properties. It has recently been shown that natriuretic peptides are also potent stimuli for lipolysis in humans. In this respect, atrial and brain natriuretic peptide appear to have the greatest lipolytic effect, and are similar in potency to catecholamines. Elevated levels of circulating natriuretic peptides are found in several pathological states, and generally reflect disease severity. This article will provide a concise review of the regulation of lipolysis in humans, concentrating on the role of the natriuretic peptides. The relevance of natriuretic peptides to the development of cachexia will be discussed.
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Affiliation(s)
- Paul R Kalra
- Clinical Cardiology, National Heart and Lung Institute, London, UK.
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