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Vincent B, Windelinckx A, Van Proeyen K, Masschelein E, Nielens H, Ramaekers M, Van Leemputte M, Hespel P, Thomis M. Alpha-actinin-3 deficiency does not significantly alter oxidative enzyme activity in fast human muscle fibres. Acta Physiol (Oxf) 2012; 204:555-61. [PMID: 21933355 DOI: 10.1111/j.1748-1716.2011.02366.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
AIM In Western European populations, about 18% of all individuals have a complete deficiency of the alpha-actinin-3 protein owing to homozygosity for a stop codon mutation (R577X) in the ACTN3 gene. Actn3(-/-) knock-out mice show increased activity of multiple enzymes in the aerobic metabolic pathway in fast muscle fibres. Whether this observation is also present in human XX genotype carriers compared to RR carriers has not been studied in a fibre-type-specific approach in humans. The purpose of this study was therefore to compare fibre-type-specific oxidative enzyme activity in humans with a different ACTN3 R577X genotype. METHODS Vastus lateralis muscle biopsy samples of 17 XX and 16 RR subjects were used to measure markers of oxidative capacity [cytochrome c oxidase (CYTOX) and succinate dehydrogenase (SDH)] in a fibre-type-specific assay using enzyme histochemistry. RESULTS Cytochrome c oxidase staining showed no significant genotype group differences in type I or type II muscle fibres. Also, we found no significant differences in SDH staining of fast fibres comparing XX and RR carriers. CONCLUSION In conclusion, the increase in oxidative enzyme activity of fast muscle fibres, as reported in an Actn3(-/-) knock-out mouse, was not observed in our human samples. Known differences in metabolic characteristics of muscle fibres in rodents compared to humans may in part explain this discrepancy in findings.
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Affiliation(s)
- B Vincent
- Research Centre for Exercise and Health, Department of Biomedical Kinesiology, Faculty of Kinesiology and Rehabilitation Sciences, K. U. Leuven, Belgium
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2
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Martins AR, Nachbar RT, Gorjao R, Vinolo MA, Festuccia WT, Lambertucci RH, Cury-Boaventura MF, Silveira LR, Curi R, Hirabara SM. Mechanisms underlying skeletal muscle insulin resistance induced by fatty acids: importance of the mitochondrial function. Lipids Health Dis 2012; 11:30. [PMID: 22360800 PMCID: PMC3312873 DOI: 10.1186/1476-511x-11-30] [Citation(s) in RCA: 190] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Accepted: 02/23/2012] [Indexed: 01/06/2023] Open
Abstract
Insulin resistance condition is associated to the development of several syndromes, such as obesity, type 2 diabetes mellitus and metabolic syndrome. Although the factors linking insulin resistance to these syndromes are not precisely defined yet, evidence suggests that the elevated plasma free fatty acid (FFA) level plays an important role in the development of skeletal muscle insulin resistance. Accordantly, in vivo and in vitro exposure of skeletal muscle and myocytes to physiological concentrations of saturated fatty acids is associated with insulin resistance condition. Several mechanisms have been postulated to account for fatty acids-induced muscle insulin resistance, including Randle cycle, oxidative stress, inflammation and mitochondrial dysfunction. Here we reviewed experimental evidence supporting the involvement of each of these propositions in the development of skeletal muscle insulin resistance induced by saturated fatty acids and propose an integrative model placing mitochondrial dysfunction as an important and common factor to the other mechanisms.
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Affiliation(s)
- Amanda R Martins
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, Avenida Professor Lineu Prestes 1524, Butantã, São Paulo, SP, Brazil
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3
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Negre-Salvayre A, Auge N, Ayala V, Basaga H, Boada J, Brenke R, Chapple S, Cohen G, Feher J, Grune T, Lengyel G, Mann GE, Pamplona R, Poli G, Portero-Otin M, Riahi Y, Salvayre R, Sasson S, Serrano J, Shamni O, Siems W, Siow RCM, Wiswedel I, Zarkovic K, Zarkovic N. Pathological aspects of lipid peroxidation. Free Radic Res 2010; 44:1125-71. [PMID: 20836660 DOI: 10.3109/10715762.2010.498478] [Citation(s) in RCA: 474] [Impact Index Per Article: 33.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Lipid peroxidation (LPO) product accumulation in human tissues is a major cause of tissular and cellular dysfunction that plays a major role in ageing and most age-related and oxidative stress-related diseases. The current evidence for the implication of LPO in pathological processes is discussed in this review. New data and literature review are provided evaluating the role of LPO in the pathophysiology of ageing and classically oxidative stress-linked diseases, such as neurodegenerative diseases, diabetes and atherosclerosis (the main cause of cardiovascular complications). Striking evidences implicating LPO in foetal vascular dysfunction occurring in pre-eclampsia, in renal and liver diseases, as well as their role as cause and consequence to cancer development are addressed.
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Toime LJ, Brand MD. Uncoupling protein-3 lowers reactive oxygen species production in isolated mitochondria. Free Radic Biol Med 2010; 49:606-11. [PMID: 20493945 PMCID: PMC2903626 DOI: 10.1016/j.freeradbiomed.2010.05.010] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2010] [Revised: 04/20/2010] [Accepted: 05/12/2010] [Indexed: 12/23/2022]
Abstract
Mitochondria are the major cellular producers of reactive oxygen species (ROS), and mitochondrial ROS production increases steeply with increased proton-motive force. The uncoupling proteins (UCP1, UCP2, and UCP3) and adenine nucleotide translocase induce proton leak in response to exogenously added fatty acids, superoxide, or lipid peroxidation products. "Mild uncoupling" by these proteins may provide a negative feedback loop to decrease proton-motive force and attenuate ROS production. Using wild-type and Ucp3(-/-) mice, we found that native UCP3 actively lowers the rate of ROS production in isolated energized skeletal muscle mitochondria, in the absence of exogenous activators. The estimated specific activity of UCP3 in lowering ROS production was 90 to 500 times higher than that of the adenine nucleotide translocase. The mild uncoupling hypothesis was tested by measuring whether the effect of UCP3 on ROS production could be mimicked by chemical uncoupling. A chemical uncoupler mimicked the effect of UCP3 at early time points after mitochondrial energization, in support of the mild uncoupling hypothesis. However, at later time points the uncoupler did not mimic UCP3, suggesting that UCP3 can also affect ROS production through a membrane potential-independent mechanism.
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Affiliation(s)
- Laurence J. Toime
- Medical Research Council Mitochondrial Biology Unit, Hills Road, Cambridge CB2 0XY, UK
| | - Martin D. Brand
- Medical Research Council Mitochondrial Biology Unit, Hills Road, Cambridge CB2 0XY, UK
- Buck Institute for Age Research, 8001 Redwood Blvd, Novato, CA 94945, USA
- Corresponding author. M.D. Brand, Buck Institute for Age Research, 8001 Redwood Blvd, Novato, CA 94945, USA. Tel +1 415-493-3676. Fax +1-415-209-2232. (M.D. Brand)
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5
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Trumble SJ, Noren SR, Cornick LA, Hawke TJ, Kanatous SB. Age-related differences in skeletal muscle lipid profiles of Weddell seals: clues to developmental changes. J Exp Biol 2010; 213:1676-84. [DOI: 10.1242/jeb.040923] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
SUMMARY
Our objective was to elucidate age-related changes in lipids associated with skeletal muscle of Weddell seals and to suggest possible physiological implications. Muscle biopsies were collected from pups, juveniles and adults in McMurdo Sound, Antarctica and analyzed for intramuscular lipid (IML) and triacylglyceride (IMTG) amounts, fatty acid groups, as well as individual fatty acid profiles. The results from this study suggest a switch from primarily saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) in the skeletal muscle of young pups to increases in polyunsaturated fatty acids (PUFAs) as the percentage of blubber increases, resulting in possible thermoregulatory benefits. As Weddell pups continue to develop into juveniles, fatty acids associated with the skeletal muscle changes such that MUFA levels are relatively higher, which may be in response to energy depletion associated with their restricted diving ability and rapid growth. As juveniles transform into adults, a reduction in n-3 PUFA levels in the muscle as the percentage of blubber increases may be indicative of a trigger to prepare for deep diving or could be a mechanism for oxygen conservation during long-duration dives. We speculate that the observed change in lipids associated with the skeletal muscle of Weddell seals is related to ontogenetic differences in thermoregulation and locomotion.
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Affiliation(s)
- Stephen J. Trumble
- Department of Biology, Baylor University, One Bear Place No. 97388, Waco, TX 76798, USA
| | - Shawn R. Noren
- Institute of Marine Science, University of California, 100 Shaffer Road, Santa Cruz, CA 95118
| | - Leslie A. Cornick
- Department of Environmental Science, Alaska Pacific University, 4101 University Drive, Anchorage, AK 99508, USA
| | - Thomas J. Hawke
- School of Kinesiology and Health Science, York University, Toronto, ON, Canada M3J 1P3
| | - Shane B. Kanatous
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
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6
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Meex RC, Schrauwen-Hinderling VB, Moonen-Kornips E, Schaart G, Mensink M, Phielix E, van de Weijer T, Sels JP, Schrauwen P, Hesselink MK. Restoration of muscle mitochondrial function and metabolic flexibility in type 2 diabetes by exercise training is paralleled by increased myocellular fat storage and improved insulin sensitivity. Diabetes 2010; 59:572-9. [PMID: 20028948 PMCID: PMC2828651 DOI: 10.2337/db09-1322] [Citation(s) in RCA: 235] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE Mitochondrial dysfunction and fat accumulation in skeletal muscle (increased intramyocellular lipid [IMCL]) have been linked to development of type 2 diabetes. We examined whether exercise training could restore mitochondrial function and insulin sensitivity in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS Eighteen male type 2 diabetic and 20 healthy male control subjects of comparable body weight, BMI, age, and VO2max participated in a 12-week combined progressive training program (three times per week and 45 min per session). In vivo mitochondrial function (assessed via magnetic resonance spectroscopy), insulin sensitivity (clamp), metabolic flexibility (indirect calorimetry), and IMCL content (histochemically) were measured before and after training. RESULTS Mitochondrial function was lower in type 2 diabetic compared with control subjects (P = 0.03), improved by training in control subjects (28% increase; P = 0.02), and restored to control values in type 2 diabetic subjects (48% increase; P < 0.01). Insulin sensitivity tended to improve in control subjects (delta Rd 8% increase; P = 0.08) and improved significantly in type 2 diabetic subjects (delta Rd 63% increase; P < 0.01). Suppression of insulin-stimulated endogenous glucose production improved in both groups (-64%; P < 0.01 in control subjects and -52% in diabetic subjects; P < 0.01). After training, metabolic flexibility in type 2 diabetic subjects was restored (delta respiratory exchange ratio 63% increase; P = 0.01) but was unchanged in control subjects (delta respiratory exchange ratio 7% increase; P = 0.22). Starting with comparable pretraining IMCL levels, training tended to increase IMCL content in type 2 diabetic subjects (27% increase; P = 0.10), especially in type 2 muscle fibers. CONCLUSIONS Exercise training restored in vivo mitochondrial function in type 2 diabetic subjects. Insulin-mediated glucose disposal and metabolic flexibility improved in type 2 diabetic subjects in the face of near-significantly increased IMCL content. This indicates that increased capacity to store IMCL and restoration of improved mitochondrial function contribute to improved muscle insulin sensitivity.
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Affiliation(s)
- Ruth C.R. Meex
- Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Vera B. Schrauwen-Hinderling
- Department of Human Biology, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, the Netherlands
- Department of Radiology, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Esther Moonen-Kornips
- Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, the Netherlands
- Department of Human Biology, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Gert Schaart
- Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Marco Mensink
- Human Nutrition, Wageningen University, the Netherlands
| | - Esther Phielix
- Department of Human Biology, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Tineke van de Weijer
- Department of Human Biology, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Jean-Pierre Sels
- Department of Internal Medicine, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Patrick Schrauwen
- Department of Human Biology, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Matthijs K.C. Hesselink
- Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, the Netherlands
- Corresponding author: Matthijs K.C. Hesselink,
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7
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Mitochondrial dysfunction and lipotoxicity. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1801:266-71. [PMID: 19782153 DOI: 10.1016/j.bbalip.2009.09.011] [Citation(s) in RCA: 181] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Revised: 08/28/2009] [Accepted: 09/13/2009] [Indexed: 12/25/2022]
Abstract
Mitochondrial dysfunction in skeletal muscle has been suggested to underlie the development of insulin resistance and type 2 diabetes mellitus. Reduced mitochondrial capacity will contribute to the accumulation of lipid intermediates, desensitizing insulin signaling and leading to insulin resistance. Why mitochondrial function is reduced in the (pre-)diabetic state is, however, so far unknown. Although it is tempting to suggest that skeletal muscle insulin resistance may result from an inherited or acquired reduction in mitochondrial function in the pre-diabetic state, it cannot be excluded that mitochondrial dysfunction may in fact be the consequence of the insulin-resistant/diabetic state. Lipotoxicity, the deleterious effects of accumulating fatty acids in skeletal muscle cells, may lie at the basis of mitochondrial dysfunction: next to producing energy, mitochondria are also the major source of reactive oxygen species (ROS). Fatty acids accumulating in the vicinity of mitochondria are vulnerable to ROS-induced lipid peroxidation. Subsequently, these lipid peroxides could have lipotoxic effects on mtDNA, RNA and proteins of the mitochondrial machinery, leading to mitochondrial dysfunction. Indeed, increased lipid peroxidation has been reported in insulin resistant skeletal muscle and the mitochondrial uncoupling protein-3, which has been suggested to prevent lipid-induced mitochondrial damage, is reduced in subjects with an impaired glucose tolerance and in type 2 diabetic patients. These findings support the hypothesis that fat accumulation in skeletal muscle may precede the reduction in mitochondrial function that is observed in type 2 diabetes mellitus.
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8
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Mayrhofer C, Krieger S, Huttary N, Chang MWF, Grillari J, Allmaier G, Kerjaschki D. Alterations in fatty acid utilization and an impaired antioxidant defense mechanism are early events in podocyte injury: a proteomic analysis. THE AMERICAN JOURNAL OF PATHOLOGY 2009; 174:1191-202. [PMID: 19264907 DOI: 10.2353/ajpath.2009.080654] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Ultrastructural alterations of podocytes are closely associated with loss of glomerular filtration function. In the present study, we explored changes at the proteome level that paralleled the disturbances of podocyte architecture in the early stages of puromycin aminonucleoside (PA) nephrosis in vivo. Using two-dimensional fluorescence difference gel electrophoresis and vacuum matrix-assisted laser desorption/ionization mass spectrometry combined with postsource decay fragment ion analysis and high-energy collision-induced dissociation tandem mass spectrometry, 23 differentially expressed protein spots, corresponding to 16 glomerular proteins that are involved in various cellular functions, were unambiguously identified, and a subset was corroborated by Western blot analysis. The majority of these proteins were primarily related to fatty acid metabolism and redox regulation. Key enzymes of the mitochondrial beta-oxidation pathway and antioxidant enzymes were consistently down-regulated in PA nephrosis. These changes were paralleled by increased expression levels of CD36. PA treatment of murine podocytes in culture resembled these specific protein changes in vitro. In this cell system, the modulatory effects of albumin-bound fatty acids on the expression levels of Mn-superoxide dismutase in response to PA were demonstrated as well. Taken together, these results indicate that a disrupted fatty acid metabolism in concert with an impaired antioxidant defense mechanism in podocytes may play a role in the early stages of PA-induced lesions in podocytes.
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Affiliation(s)
- Corina Mayrhofer
- Clinical Institute of Pathology, Medical University of Vienna, Waehringer Gürtel 18-20, A-1090 Vienna, Austria.
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9
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Characterization of survival and phenotype throughout the life span in UCP2/UCP3 genetically altered mice. Exp Gerontol 2008; 43:1061-8. [DOI: 10.1016/j.exger.2008.09.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2008] [Revised: 08/21/2008] [Accepted: 09/19/2008] [Indexed: 11/20/2022]
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10
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Nabben M, Hoeks J, Briedé JJ, Glatz JFC, Moonen-Kornips E, Hesselink MKC, Schrauwen P. The effect of UCP3 overexpression on mitochondrial ROS production in skeletal muscle of young versus aged mice. FEBS Lett 2008; 582:4147-52. [PMID: 19041310 DOI: 10.1016/j.febslet.2008.11.016] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Revised: 11/04/2008] [Accepted: 11/12/2008] [Indexed: 01/04/2023]
Abstract
Uncoupling protein 3 (UCP3) is suggested to protect mitochondria against aging and lipid-induced damage, possibly via modulation of reactive oxygen species (ROS) production. Here we show that mice overexpressing UCP3 (UCP3Tg) have a blunted age-induced increase in ROS production, assessed by electron spin resonance spectroscopy, but only after addition of 4-hydroxynonenal (4-HNE). Mitochondrial function, assessed by respirometry, on glycolytic substrate was lower in UCP3Tg mice compared to wild types, whereas this tended to be higher on fatty acids. State 4o respiration was higher in UCP3Tg animals. To conclude, UCP3 overexpression leads to increased state 4o respiration and, in presence of 4-HNE, blunts the age-induced increase in ROS production.
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Affiliation(s)
- Miranda Nabben
- Department of Human Biology, Nutrition and Toxicology Research Institute Maastricht, Maastricht University, PO Box 616, 6200 MD, Maastricht, The Netherlands
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11
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Lombardi A, Grasso P, Moreno M, de Lange P, Silvestri E, Lanni A, Goglia F. Interrelated influence of superoxides and free fatty acids over mitochondrial uncoupling in skeletal muscle. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:826-33. [PMID: 18471434 DOI: 10.1016/j.bbabio.2008.04.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2007] [Revised: 03/21/2008] [Accepted: 04/14/2008] [Indexed: 10/22/2022]
Abstract
Mitochondrial uncoupling protein 3 (UCP(3))-mediated uncoupling has been postulated to depend on several factors, including superoxides, free fatty acids (FFAs), and fatty acid hydroperoxides and/or their derivatives. We investigated whether there is an interrelation between endogenous mitochondrial superoxides and fatty acids in inducing skeletal muscle mitochondrial uncoupling, and we speculated on the possible involvement of UCP(3) in this process. In the absence of FFAs, no differences in proton-leak kinetic were detected between succinate-energized mitochondria respiring in the absence or presence of rotenone, despite a large difference in complex I superoxide production. The addition of either arachidic acid or arachidonic acid induced an increase in proton-leak kinetic, with arachidonic acid having the more marked effect. The uncoupling effect of arachidic acid was independent of the presence of GDP, rotenone and vitamin E, while that of arachidonic acid was dependent on these factors. These data demonstrate that FFA and O(2-) play interrelated roles in inducing mitochondrial uncoupling, and we hypothesize that a likely formation of mitochondrial fatty acid hydroperoxides is a key event in the arachidonic acid-induced GDP-dependent inhibition of mitochondrial uncoupling.
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Affiliation(s)
- Assunta Lombardi
- Dipartimento delle Scienze Biologiche, Sezione Fisiologia, Università degli Studi di Napoli Federico II, Via Mezzocannone 8, 80134 Napoli, Italy
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12
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Fernandez-Solà J, Preedy VR, Lang CH, Gonzalez-Reimers E, Arno M, Lin JCI, Wiseman H, Zhou S, Emery PW, Nakahara T, Hashimoto K, Hirano M, Santolaria-Fernández F, González-Hernández T, Fatjó F, Sacanella E, Estruch R, Nicolás JM, Urbano-Márquez A. Molecular and cellular events in alcohol-induced muscle disease. Alcohol Clin Exp Res 2008; 31:1953-62. [PMID: 18034690 DOI: 10.1111/j.1530-0277.2007.00530.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Alcohol consumption induces a dose-dependent noxious effect on skeletal muscle, leading to progressive functional and structural damage of myocytes, with concomitant reductions in lean body mass. Nearly half of high-dose chronic alcohol consumers develop alcoholic skeletal myopathy. The pathogenic mechanisms that lie between alcohol intake and loss of muscle tissue involve multiple pathways, making the elucidation of the disease somewhat difficult. This review discusses the recent advances in basic and clinical research on the molecular and cellular events involved in the development of alcohol-induced muscle disease. The main areas of recent research interest on this field are as follows: (i) molecular mechanisms in alcohol exposed muscle in the rat model; (ii) gene expression changes in alcohol exposed muscle; (iii) the role of trace elements and oxidative stress in alcoholic myopathy; and (iv) the role of apoptosis and preapoptotic pathways in alcoholic myopathy. These aforementioned areas are crucial in understanding the pathogenesis of this disease. For example, there is overwhelming evidence that both chronic alcohol ingestion and acute alcohol intoxication impair the rate of protein synthesis of myofibrillar proteins, in particular, under both postabsorptive and postprandial conditions. Perturbations in gene expression are contributory factors to the development of alcoholic myopathy, as ethanol-induced alterations are detected in over 400 genes and the protein profile (i.e., the proteome) of muscle is also affected. There is supportive evidence that oxidative damage is involved in the pathogenesis of alcoholic myopathy. Increased lipid peroxidation is related to muscle fibre atrophy, and reduced serum levels of some antioxidants may be related to loss of muscle mass and muscle strength. Finally, ethanol induces skeletal muscle apoptosis and increases both pro- and antiapoptotic regulatory mechanisms.
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13
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Graier WF, Trenker M, Malli R. Mitochondrial Ca2+, the secret behind the function of uncoupling proteins 2 and 3? Cell Calcium 2008; 44:36-50. [PMID: 18282596 DOI: 10.1016/j.ceca.2008.01.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2007] [Revised: 01/07/2008] [Accepted: 01/07/2008] [Indexed: 12/20/2022]
Abstract
The underlying molecular action of the novel uncoupling proteins 2 and 3 (UCP2 and UCP3) is still under debate. The proteins have been implicated in many cell functions, including the regulation of insulin secretion and regulation of reactive oxygen species (ROS) generation. These effects have mainly been explained by suggesting that the proteins establish a proton leak through the inner mitochondrial membrane (IMM). However, accumulating data question this mechanism and suggest that UCP2 and UCP3 may play other roles, including carrying free fatty acids from the matrix towards the intermembrane space, or contributing to the mitochondrial Ca(2+) uniport. Accordingly, in this review we reflect on these actions of UCP2/UCP3 and discuss alternative explanations for the molecular mechanisms by which UCP2/UCP3 might contribute to aspects of cell function. Based on the potential role of UCP2/UCP3 in regulating mitochondrial Ca(2+) uptake, we propose a scheme whereby these proteins integrate Ca(2+)-dependent signal transduction and energy metabolism in order to meet the energy demand of the cell for its continuous response, adaptation, and stimulation to environmental input.
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Affiliation(s)
- Wolfgang F Graier
- Institute of Molecular Biology and Biochemistry, Molecular and Cellular Physiology Research Unit, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21/III, Graz, Austria.
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14
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De Bock K, Derave W, Eijnde BO, Hesselink MK, Koninckx E, Rose AJ, Schrauwen P, Bonen A, Richter EA, Hespel P. Effect of training in the fasted state on metabolic responses during exercise with carbohydrate intake. J Appl Physiol (1985) 2008; 104:1045-55. [PMID: 18276898 DOI: 10.1152/japplphysiol.01195.2007] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Skeletal muscle gene response to exercise depends on nutritional status during and after exercise, but it is unknown whether muscle adaptations to endurance training are affected by nutritional status during training sessions. Therefore, this study investigated the effect of an endurance training program (6 wk, 3 day/wk, 1-2 h, 75% of peak Vo(2)) in moderately active males. They trained in the fasted (F; n = 10) or carbohydrate-fed state (CHO; n = 10) while receiving a standardized diet [65 percent of total energy intake (En) from carbohydrates, 20%En fat, 15%En protein]. Before and after the training period, substrate use during a 2-h exercise bout was determined. During these experimental sessions, all subjects were in a fed condition and received extra carbohydrates (1 g.kg body wt(-1) .h(-1)). Peak Vo(2) (+7%), succinate dehydrogenase activity, GLUT4, and hexokinase II content were similarly increased between F and CHO. Fatty acid binding protein (FABPm) content increased significantly in F (P = 0.007). Intramyocellular triglyceride content (IMCL) remained unchanged in both groups. After training, pre-exercise glycogen content was higher in CHO (545 +/- 19 mmol/kg dry wt; P = 0.02), but not in F (434 +/- 32 mmol/kg dry wt; P = 0.23). For a given initial glycogen content, F blunted exercise-induced glycogen breakdown when compared with CHO (P = 0.04). Neither IMCL breakdown (P = 0.23) nor fat oxidation rates during exercise were altered by training. Thus short-term training elicits similar adaptations in peak Vo(2) whether carried out in the fasted or carbohydrate-fed state. Although there was a decrease in exercise-induced glycogen breakdown and an increase in proteins involved in fat handling after fasting training, fat oxidation during exercise with carbohydrate intake was not changed.
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Affiliation(s)
- K De Bock
- Research Center for Exercise and Health, F.A.B.E.R. - K.U.Leuven, Tervuursevest 101, B-3001 Leuven Heverlee, Belgium
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15
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Hoeks J, Briedé JJ, de Vogel J, Schaart G, Nabben M, Moonen-Kornips E, Hesselink MKC, Schrauwen P. Mitochondrial function, content and ROS production in rat skeletal muscle: effect of high-fat feeding. FEBS Lett 2008; 582:510-6. [PMID: 18230360 DOI: 10.1016/j.febslet.2008.01.013] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Revised: 01/03/2008] [Accepted: 01/15/2008] [Indexed: 12/25/2022]
Abstract
A high intake of dietary fat has been suggested to diminish mitochondrial functioning in skeletal muscle, possibly attributing to muscular fat accumulation. Here we show however, that an 8-week high-fat dietary intervention did not affect intrinsic functioning of rat skeletal muscle mitochondria assessed by respirometry, neither on a carbohydrate- nor on a lipid-substrate. Interestingly, PPARGC1A protein increased by approximately 2-fold upon high-fat feeding and we observed inconsistent results on different markers of mitochondrial density. Mitochondrial ROS production, assessed by electron spin resonance spectroscopy remained unaffected. Intramyocellular lipid levels increased significantly illustrating that a reduced innate mitochondrial function is not a prerequisite for intra-muscular fat accumulation.
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Affiliation(s)
- Joris Hoeks
- Department of Human Biology, Nutrition and Toxicology Research Institute Maastricht, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands.
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Mills EM, Weaver KL, Abramson E, Pfeiffer M, Sprague JE. Influence of dietary fats on Ecstasy-induced hyperthermia. Br J Pharmacol 2007; 151:1103-8. [PMID: 17533413 PMCID: PMC2042934 DOI: 10.1038/sj.bjp.0707312] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE Studies were designed to examine the effects of dietary fats on metabolic effects of 3,4-methylenedioxymethamphetamine (MDMA, Ecstasy). These effects included hyperthermia, expression of uncoupling protein (UCP1 and 3) in brown adipose tissue or skeletal muscle and plasma free fatty acid (FFA) levels. EXPERIMENTAL APPROACH Male Sprague-Dawley rats were fed either a high-fat diet (HFD, 60% kcal) or a lower fat isocaloric controlled diet (LFD, 10% kcal) for 28 days before MDMA challenge. KEY RESULTS No significant differences were observed between LFD and HFD groups in terms of body weight, plasma thyroxine (T4) levels and expression of brown fat UCP1 or skeletal muscle UCP3 protein. HFD significantly raised levels of circulating FFA and potentiated the thermogenesis induced by MDMA (10 mg kg(-1), s.c.), compared to the effects of the LFD. Moreover, 30 and 60 min after MDMA administration, plasma FFA levels decreased in HFD animals, but were markedly elevated in the LFD group. CONCLUSIONS AND IMPLICATIONS These results indicate that high-fat feeding regulates MDMA-induced thermogenesis by augmenting the activation of UCP rather than its expression.
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MESH Headings
- Adipose Tissue, Brown/drug effects
- Adipose Tissue, Brown/metabolism
- Analysis of Variance
- Animals
- Blotting, Western
- Body Temperature/drug effects
- Diet, Fat-Restricted
- Dietary Fats/administration & dosage
- Fatty Acids, Nonesterified/blood
- Fever/blood
- Fever/chemically induced
- Fever/physiopathology
- Injections, Subcutaneous
- Ion Channels/metabolism
- Male
- Mitochondria, Muscle/drug effects
- Mitochondria, Muscle/metabolism
- Mitochondrial Proteins/metabolism
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/metabolism
- N-Methyl-3,4-methylenedioxyamphetamine/administration & dosage
- N-Methyl-3,4-methylenedioxyamphetamine/toxicity
- Rats
- Rats, Sprague-Dawley
- Thermogenesis/drug effects
- Thyroxine/blood
- Time Factors
- Uncoupling Agents/metabolism
- Uncoupling Protein 1
- Uncoupling Protein 3
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Affiliation(s)
- E M Mills
- Division of Pharmacology and Toxicology, College of Pharmacy, University of Texas at Austin Austin, TX, USA
| | - K L Weaver
- Department of Pharmacology, Virginia College of Osteopathic Medicine Blacksburg, VA, USA
| | - E Abramson
- Division of Pharmacology and Toxicology, College of Pharmacy, University of Texas at Austin Austin, TX, USA
| | - M Pfeiffer
- Division of Pharmacology and Toxicology, College of Pharmacy, University of Texas at Austin Austin, TX, USA
| | - J E Sprague
- Department of Pharmacology, Virginia College of Osteopathic Medicine Blacksburg, VA, USA
- The Raabe College of Pharmacy, Ohio Northern University Ada, OH, USA
- Author for correspondence:
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Abstract
A high dietary fat intake and low physical activity characterize the current Western lifestyle. Dietary fatty acids do not stimulate their own oxidation and a surplus of fat is stored in white adipose tissue, liver, heart and muscle. In these organs intracellular lipids serve as a rapidly-available energy source during, for example, physical activity. However, under conditions of elevated plasma fatty acid levels and high dietary fat intake, conditions implicated in the development of modern diseases such as obesity and type 2 diabetes mellitus, fat accumulation in liver and muscle (intramyocellular lipids; IMCL) is associated with the development of insulin resistance. Recent data suggest that IMCL are specifically harmful when combined with reduced mitochondrial function, both conditions that characterize type 2 diabetes. In the (pre)diabetic state reduced expression of the transcription factor PPARgamma co-activator-1alpha (PGC-1alpha), which is involved in mitochondrial biogenesis, has been suggested to underlie the reduced mitochondrial function. Importantly, the reduction in PGC-1alpha may be a result of low physical activity, consumption of high-fat diets and high plasma fatty acid levels. Mitochondrial function can also be impaired as a result of enhanced mitochondrial damage by reactive oxygen species. Fatty acids in the vicinity of mitochondria are particularly prone to lipid peroxidation. In turn, lipid peroxides can induce oxidative damage to mitochondrial RNA, DNA and proteins. The mitochondrial protein uncoupling protein 3, which is induced under high-fat conditions, may serve to protect mitochondria against lipid-induced oxidative damage, but is reduced in the prediabetic state. Thus, muscular lipotoxicity may impair mitochondrial function and may be central to insulin resistance and type 2 diabetes mellitus.
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Affiliation(s)
- Patrick Schrauwen
- Department of Human Biology, Maastricht University, Wageningen Center for Food Sciences & Nutrition and Toxicology Research Institute Maastricht, PO Box 616, NL-6200 MD, Maastricht, The Netherlands.
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Bézaire V, Seifert EL, Harper ME. Uncoupling protein-3: clues in an ongoing mitochondrial mystery. FASEB J 2007; 21:312-24. [PMID: 17202247 DOI: 10.1096/fj.06-6966rev] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Uncoupling protein (UCP) 3 (UCP3) is a mitochondrial anion carrier protein with highly selective expression in skeletal muscle. Despite a great deal of interest, to date neither its molecular mechanism nor its biochemical and physiological functions are well understood. Based on its high degree of homology to the original UCP (UCP1), early studies examined a role for UCP3 in thermogenesis. However, evidence for such a function is lacking. Recent studies have focused on two distinct, but not mutually exclusive, hypotheses: 1) UCP3 mitigates reactive oxygen species (ROS) production, and 2) UCP3 is somehow involved in fatty acid (FA) translocation. While supportive evidence exists for both hypotheses, the interpretation of the corresponding evidence has created some controversy. Mechanistic studies examining mitigated ROS production have been largely conducted in vitro, and the physiological significance of the findings is questioned. Conversely, while physiological evidence exists for FA translocation hypotheses, the evidence is largely correlative, leaving causal relationships unexplored. This review critically assesses evidence for the hypotheses and attempts to link the outcomes from mechanistic studies to physiological implications. Important directions for future studies, using current and novel approaches, are discussed.
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Affiliation(s)
- Véronic Bézaire
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Rd., Ottawa, ON, Canada K1H 8M5
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Hoeks J, Hesselink MKC, Schrauwen P. Involvement of UCP3 in mild uncoupling and lipotoxicity. Exp Gerontol 2006; 41:658-62. [PMID: 16564663 DOI: 10.1016/j.exger.2006.02.005] [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] [Received: 11/10/2005] [Accepted: 02/14/2006] [Indexed: 01/06/2023]
Abstract
Although vital to life, mitochondria are also the major source of ROS production, which may have unwanted detrimental effects on DNA, RNA and protein structures Therefore, mitochondria must exhibit well-developed mechanisms to regulate its ROS production. One such mechanism might be mild uncoupling of the mitochondrial respiratory chain, thereby lowering the proton gradient across the inner mitochondrial membrane and directly lowering ROS production. Mitochondrial uncoupling proteins have been shown to possess mild uncoupling activity and may therefore be important regulator of mitochondrial ROS production. The skeletal muscle isoform of the uncoupling protein family, UCP3, seems to be specifically active under conditions of high fatty acid availability. Although the exact function of UCP3 is not yet unravelled, UCP3 is activated by lipid peroxides and suggested to export fatty acid anions and/or peroxides from the mitochondrial matrix, thereby specifically protecting fatty acids from ROS-induced oxidative damage. Protein levels of UCP3 are reduced with aging and in the (pre)-diabetic state, both conditions characterized by increased levels of oxidative damage to lipids and proteins and reduced mitochondrial function. Whether UCP3 is causally related to mitochondrial dysfunction and is essential in the prevention and treatment of lipid-induced mitochondrial dysfunction requires further study.
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Affiliation(s)
- Joris Hoeks
- Department of Human Biology, Nutrition and Toxicology Research Institute Maastricht (NUTRIM), Maastricht University, P.O. Box 616, NL-6200 MD, Maastricht, The Netherlands
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