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Teaney NA, Cyr NE. FoxO1 as a tissue-specific therapeutic target for type 2 diabetes. Front Endocrinol (Lausanne) 2023; 14:1286838. [PMID: 37941908 PMCID: PMC10629996 DOI: 10.3389/fendo.2023.1286838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 10/06/2023] [Indexed: 11/10/2023] Open
Abstract
Forkhead box O (FoxO) proteins are transcription factors that mediate many aspects of physiology and thus have been targeted as therapeutics for several diseases including metabolic disorders such as type 2 diabetes mellitus (T2D). The role of FoxO1 in metabolism has been well studied, but recently FoxO1's potential for diabetes prevention and therapy has been debated. For example, studies have shown that increased FoxO1 activity in certain tissue types contributes to T2D pathology, symptoms, and comorbidities, yet in other tissue types elevated FoxO1 has been reported to alleviate symptoms associated with diabetes. Furthermore, studies have reported opposite effects of active FoxO1 in the same tissue type. For example, in the liver, FoxO1 contributes to T2D by increasing hepatic glucose production. However, FoxO1 has been shown to either increase or decrease hepatic lipogenesis as well as adipogenesis in white adipose tissue. In skeletal muscle, FoxO1 reduces glucose uptake and oxidation, promotes lipid uptake and oxidation, and increases muscle atrophy. While many studies show that FoxO1 lowers pancreatic insulin production and secretion, others show the opposite, especially in response to oxidative stress and inflammation. Elevated FoxO1 in the hypothalamus increases the risk of developing T2D. However, increased FoxO1 may mitigate Alzheimer's disease, a neurodegenerative disease strongly associated with T2D. Conversely, accumulating evidence implicates increased FoxO1 with Parkinson's disease pathogenesis. Here we review FoxO1's actions in T2D conditions in metabolic tissues that abundantly express FoxO1 and highlight some of the current studies targeting FoxO1 for T2D treatment.
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Affiliation(s)
- Nicole A. Teaney
- Stonehill College, Neuroscience Program, Easton, MA, United States
| | - Nicole E. Cyr
- Stonehill College, Neuroscience Program, Easton, MA, United States
- Stonehill College, Department of Biology, Easton, MA, United States
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2
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Astaxanthin Exerts Anabolic Effects via Pleiotropic Modulation of the Excitable Tissue. Int J Mol Sci 2022; 23:ijms23020917. [PMID: 35055102 PMCID: PMC8778848 DOI: 10.3390/ijms23020917] [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: 11/17/2021] [Revised: 01/04/2022] [Accepted: 01/11/2022] [Indexed: 11/27/2022] Open
Abstract
Astaxanthin is a lipid-soluble carotenoid influencing lipid metabolism, body weight, and insulin sensitivity. We provide a systematic analysis of acute and chronic effects of astaxanthin on different organs. Changes by chronic astaxanthin feeding were analyzed on general metabolism, expression of regulatory proteins in the skeletal muscle, as well as changes of excitation and synaptic activity in the hypothalamic arcuate nucleus of mice. Acute responses were also tested on canine cardiac muscle and different neuronal populations of the hypothalamic arcuate nucleus in mice. Dietary astaxanthin significantly increased food intake. It also increased protein levels affecting glucose metabolism and fatty acid biosynthesis in skeletal muscle. Inhibitory inputs innervating neurons of the arcuate nucleus regulating metabolism and food intake were strengthened by both acute and chronic astaxanthin treatment. Astaxanthin moderately shortened cardiac action potentials, depressed their plateau potential, and reduced the maximal rate of depolarization. Based on its complex actions on metabolism and food intake, our data support the previous findings that astaxanthin is suitable for supplementing the diet of patients with disturbances in energy homeostasis.
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Besse A, Brezavar D, Hanson J, Larson A, Bonnen PE. LONP1 de novo dominant mutation causes mitochondrial encephalopathy with loss of LONP1 chaperone activity and excessive LONP1 proteolytic activity. Mitochondrion 2020; 51:68-78. [PMID: 31923470 DOI: 10.1016/j.mito.2020.01.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Revised: 11/16/2019] [Accepted: 01/03/2020] [Indexed: 02/04/2023]
Abstract
LONP1 is an ATP-dependent protease and chaperone that plays multiple vital roles in mitochondria. LONP1 is essential for mitochondrial homeostasis due to its role in maintenance of the mitochondrial genome and its central role in regulating mitochondrial processes such as oxidative phosphorylation, mitophagy, and heme biosynthesis. Bi-allelic LONP1 mutations have been reported to cause a constellation of clinical presentations. We report a patient heterozygous for a de novo mutation in LONP1: c.901C>T,p.R301W presenting as a neonate with seizures, encephalopathy, pachygyria and microcephaly. Assays of respiratory chain activity in muscle showed complex II-III function at 8% of control. Functional studies in patient fibroblasts showed a signature of dysfunction that included significant decreases in known proteolytic targets of LONP1 (TFAM, PINK1, phospho-PDH E1α) as well as loss of mitochondrial ribosome subunits MRPL44 and MRPL11 with concomitant decreased activity and level of protein subunits of oxidative phosphorylation complexes I and IV. These results indicate excessive LONP1 proteolytic activity and a loss of LONP1 chaperone activity. Further, we demonstrate that the LONP1 N-terminal domain is involved in hexamer stability of LONP1 and that the ability to make conformational changes is necessary for LONP1 to regulate proper functioning of both its proteolytic and chaperone activities.
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Affiliation(s)
- Arnaud Besse
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Daniel Brezavar
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Jennifer Hanson
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Austin Larson
- University of Colorado School of Medicine and Children's Hospital Colorado, Aurora, CO, United States
| | - Penelope E Bonnen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States.
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Kim JH, Park SJ, Chae U, Seong J, Lee HS, Lee SR, Lee S, Lee DS. Peroxiredoxin 2 mediates insulin sensitivity of skeletal muscles through regulation of protein tyrosine phosphatase oxidation. Int J Biochem Cell Biol 2018; 99:80-90. [PMID: 29605633 DOI: 10.1016/j.biocel.2018.03.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 03/07/2018] [Accepted: 03/27/2018] [Indexed: 01/14/2023]
Abstract
Insulin signaling is essential for regulating glucose homeostasis. Numerous studies have demonstrated that reactive oxygen species (ROS) affect insulin signaling, and low ROS levels can act as a signal to regulate cellular function. Peroxiredoxins (Prxs) are highly abundant and widely expressed antioxidant enzymes. However, it is unclear whether antioxidant enzymes, such as Prx2, mediate insulin signaling. The aim of our study was to investigate the influence of Prx2 deficiency on insulin signaling. Our western blot results showed that Prx2 deficiency enhanced insulin signaling and increased oxidation of protein tyrosine phosphatase 1B (PTP1B) and phosphatase and tensin homologue (PTEN) in mouse embryonic fibroblasts (MEFs) treated with insulin. In addition, we assessed ROS levels with a Cytosol-HyPer H2O2 sensor. As a result, increased ROS levels and Akt activation were decreased by N-acetyl-cysteine (Nac), which acted as an antioxidant in Prx2-deficient MEFs. Body weight measurements and glucose tolerance test (GTT) revealed significant body weight reduction and increase in glucose clearance in Prx2-/- mice fed a high-fat diet. Interestingly, glucose transporter type 4 (GLUT4) was significantly higher in Prx2-/- mice than in wild-type mice according to western blotting results. Western blotting also revealed that Akt phosphorylation was higher in Prx2-/- MEFs and muscle tissue than in wild-type. Together, our findings indicate that increased ROS due to Prx2 deficiency promotes insulin sensitivity and glucose clearance in skeletal muscles by increasing protein tyrosine phosphatase (PTPs) oxidation. These results provide novel insights into the fundamental mechanisms of insulin signaling induced by Prx2 deficiency and suggest that ROS-based therapeutic strategies can be used to suppress insulin resistance.
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Affiliation(s)
- Jung-Hak Kim
- School of Life Sciences and Biotechnology, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 41566, Republic of Korea; Division of Endocrinology, Internal Medicine, University of California, Davis, CA, 95616, USA
| | - Sun-Ji Park
- School of Life Sciences and Biotechnology, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 41566, Republic of Korea; Renal Division, School of Medicine, Washington University in St. Louis, MO, 63130, USA
| | - Unbin Chae
- School of Life Sciences and Biotechnology, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 41566, Republic of Korea
| | - Joongbae Seong
- School of Life Sciences and Biotechnology, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 41566, Republic of Korea
| | - Hyun-Shik Lee
- School of Life Sciences and Biotechnology, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 41566, Republic of Korea
| | - Sang-Rae Lee
- National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Chungcheongbuk-do, 34141, Republic of Korea
| | - Seunghoon Lee
- Animal Biotechnology Division, National Institute of Animal Science, Jeollabuk-do, 55365, Republic of Korea
| | - Dong-Seok Lee
- School of Life Sciences and Biotechnology, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 41566, Republic of Korea.
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Li T, Xu J, Qin X, Hou Z, Guo Y, Liu Z, Wu J, Zheng H, Zhang X, Gao F. Glucose oxidation positively regulates glucose uptake and improves cardiac function recovery after myocardial reperfusion. Am J Physiol Endocrinol Metab 2017; 313:E577-E585. [PMID: 28325730 DOI: 10.1152/ajpendo.00014.2017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 03/10/2017] [Accepted: 03/15/2017] [Indexed: 01/31/2023]
Abstract
Myocardial reperfusion decreases glucose oxidation and uncouples glucose oxidation from glycolysis. Therapies that increase glucose oxidation lessen myocardial ischemia-reperfusion (I/R) injury. However, the regulation of glucose uptake during reperfusion remains poorly understood. We found that glucose uptake was remarkably diminished in the myocardium following reperfusion in Sprague-Dawley rats as detected by 18F-labeled and fluorescent-labeled glucose analogs, even though GLUT1 was upregulated by threefold and GLUT4 translocation remained unchanged compared with those of sham-treated rats. The decreased glucose uptake was accompanied by suppressed glucose oxidation. Interestingly, stimulating glucose oxidation by inhibition of pyruvate dehydrogenase kinase 4 (PDK4), a rate-limiting enzyme for glucose oxidation, increased glucose uptake and alleviated I/R injury. In vitro data in neonatal myocytes showed that PDK4 overexpression decreased glucose uptake, whereas its knockdown increased glucose uptake, suggesting that PDK4 has a role in regulating glucose uptake. Moreover, inhibition of PDK4 increased myocardial glucose uptake with concomitant enhancement of cardiac insulin sensitivity following myocardial I/R. These results showed that the suppressed glucose oxidation mediated by PDK4 contributes to the reduced glucose uptake in the myocardium following reperfusion, and enhancement of glucose uptake exerts cardioprotection. The findings suggest that stimulating glucose oxidation via PDK4 could be an efficient approach to improve recovery from myocardial I/R injury.
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Affiliation(s)
- Tingting Li
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China; and
| | - Jie Xu
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China; and
| | - Xinghua Qin
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China; and
| | - Zuoxu Hou
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China; and
| | - Yongzheng Guo
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China; and
| | - Zhenhua Liu
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China; and
| | - Jianjiang Wu
- Department of Anesthesiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi, China
| | - Hong Zheng
- Department of Anesthesiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi, China
| | - Xing Zhang
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China; and
| | - Feng Gao
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China; and
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Chen YC, Travers RL, Walhin JP, Gonzalez JT, Koumanov F, Betts JA, Thompson D. Feeding influences adipose tissue responses to exercise in overweight men. Am J Physiol Endocrinol Metab 2017; 313:E84-E93. [PMID: 28292758 DOI: 10.1152/ajpendo.00006.2017] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 02/22/2017] [Accepted: 03/09/2017] [Indexed: 01/04/2023]
Abstract
Feeding profoundly affects metabolic responses to exercise in various tissues, but the effect of feeding status on human adipose tissue responses to exercise has never been studied. Ten healthy overweight men aged 26 ± 5 yr (mean ± SD) with a waist circumference of 105 ± 10 cm walked at 60% of maximum oxygen uptake under either fasted or fed conditions in a randomized, counterbalanced design. Feeding comprised 648 ± 115 kcal 2 h before exercise. Blood samples were collected at regular intervals to examine changes in metabolic parameters and adipokine concentrations. Adipose tissue samples were obtained at baseline and 1 h after exercise to examine changes in adipose tissue mRNA expression and secretion of selected adipokines ex vivo. Adipose tissue mRNA expression of pyruvate dehydrogenase kinase isozyme 4 (PDK4), adipose triglyceride lipase, hormone-sensitive lipase (HSL), fatty acid translocase/CD36, glucose transporter type 4 (GLUT4), and insulin receptor substrate 2 (IRS2) in response to exercise were lower in fed compared with fasted conditions (all P ≤ 0.05). Postexercise adipose IRS2 protein was affected by feeding (P ≤ 0.05), but Akt2, AMPK, IRS1, GLUT4, PDK4, and HSL protein levels were not different. Feeding status did not impact serum and ex vivo adipose secretion of IL-6, leptin, or adiponectin in response to exercise. This is the first study to show that feeding before acute exercise affects postexercise adipose tissue gene expression, and we propose that feeding is likely to blunt long-term adipose tissue adaptation to regular exercise.
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Affiliation(s)
- Yung-Chih Chen
- Department for Health, University of Bath, Bath, United Kingdom
| | | | | | | | | | - James A Betts
- Department for Health, University of Bath, Bath, United Kingdom
| | - Dylan Thompson
- Department for Health, University of Bath, Bath, United Kingdom
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Gjessing PF, Constantin-Teodosiu D, Hagve M, Lobo DN, Revhaug A, Irtun Ø. Preoperative carbohydrate supplementation attenuates post-surgery insulin resistance via reduced inflammatory inhibition of the insulin-mediated restraint on muscle pyruvate dehydrogenase kinase 4 expression. Clin Nutr 2015; 34:1177-83. [DOI: 10.1016/j.clnu.2014.12.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 11/25/2014] [Accepted: 12/04/2014] [Indexed: 01/04/2023]
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8
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Park S, Choi SG, Yoo SM, Nah J, Jeong E, Kim H, Jung YK. Pyruvate stimulates mitophagy via PINK1 stabilization. Cell Signal 2015; 27:1824-30. [DOI: 10.1016/j.cellsig.2015.05.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 05/13/2015] [Accepted: 05/20/2015] [Indexed: 11/30/2022]
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9
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Fang XL, Zhu XT, Chen SF, Zhang ZQ, Zeng QJ, Deng L, Peng JL, Yu JJ, Wang LN, Wang SB, Gao P, Jiang QY, Shu G. Differential gene expression pattern in hypothalamus of chickens during fasting-induced metabolic reprogramming: Functions of glucose and lipid metabolism in the feed intake of chickens. Poult Sci 2014; 93:2841-54. [DOI: 10.3382/ps.2014-04047] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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10
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Increased pyruvate dehydrogenase kinase expression in cultured myotubes from obese and diabetic individuals. Eur J Nutr 2014; 54:1033-43. [DOI: 10.1007/s00394-014-0780-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 10/06/2014] [Indexed: 12/11/2022]
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Guzmán S, Marin S, Miranda A, Selivanov VA, Centelles JJ, Harmancey R, Smih F, Turkieh A, Durocher Y, Zorzano A, Rouet P, Cascante M. (13)C metabolic flux analysis shows that resistin impairs the metabolic response to insulin in L6E9 myotubes. BMC SYSTEMS BIOLOGY 2014; 8:109. [PMID: 25217974 PMCID: PMC4363945 DOI: 10.1186/s12918-014-0109-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 08/29/2014] [Indexed: 12/11/2022]
Abstract
Background It has been suggested that the adipokine resistin links obesity and insulin resistance, although how resistin acts on muscle metabolism is controversial. We aimed to quantitatively analyse the effects of resistin on the glucose metabolic flux profile and on insulin response in L6E9 myotubes at the metabolic level using a tracer-based metabolomic approach and our in-house developed software, Isodyn. Results Resistin significantly increased glucose uptake and glycolysis, altering pyruvate utilisation by the cell. In the presence of resistin, insulin only slightly increased glucose uptake and glycolysis, and did not alter the flux profile around pyruvate induced by resistin. Resistin prevented the increase in gene expression in pyruvate dehydrogenase-E1 and the sharp decrease in gene expression in cytosolic phosphoenolpyruvate carboxykinase-1 induced by insulin. Conclusions These data suggest that resistin impairs the metabolic activation of insulin. This impairment cannot be explained by the activity of a single enzyme, but instead due to reorganisation of the whole metabolic flux distribution.
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Affiliation(s)
- Shirley Guzmán
- Department of Biochemistry and Molecular Biology, Faculty of Biology, Universitat de Barcelona, Av Diagonal 643, 08028, Barcelona, Spain. .,Institute of Biomedicine of Universitat de Barcelona (IBUB) and CSIC-Associated Unit, Barcelona, Spain.
| | - Silvia Marin
- Department of Biochemistry and Molecular Biology, Faculty of Biology, Universitat de Barcelona, Av Diagonal 643, 08028, Barcelona, Spain. .,Institute of Biomedicine of Universitat de Barcelona (IBUB) and CSIC-Associated Unit, Barcelona, Spain.
| | - Anibal Miranda
- Department of Biochemistry and Molecular Biology, Faculty of Biology, Universitat de Barcelona, Av Diagonal 643, 08028, Barcelona, Spain. .,Institute of Biomedicine of Universitat de Barcelona (IBUB) and CSIC-Associated Unit, Barcelona, Spain.
| | - Vitaly A Selivanov
- Department of Biochemistry and Molecular Biology, Faculty of Biology, Universitat de Barcelona, Av Diagonal 643, 08028, Barcelona, Spain. .,Institute of Biomedicine of Universitat de Barcelona (IBUB) and CSIC-Associated Unit, Barcelona, Spain.
| | - Josep J Centelles
- Department of Biochemistry and Molecular Biology, Faculty of Biology, Universitat de Barcelona, Av Diagonal 643, 08028, Barcelona, Spain. .,Institute of Biomedicine of Universitat de Barcelona (IBUB) and CSIC-Associated Unit, Barcelona, Spain.
| | - Romain Harmancey
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR 1048, Toulouse, France. .,Université Toulouse III Paul-Sabatier, Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), Equipe n°7, Toulouse, France.
| | - Fatima Smih
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR 1048, Toulouse, France. .,Université Toulouse III Paul-Sabatier, Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), Equipe n°7, Toulouse, France.
| | - Annie Turkieh
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR 1048, Toulouse, France. .,Université Toulouse III Paul-Sabatier, Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), Equipe n°7, Toulouse, France.
| | - Yves Durocher
- Animal Cell Technology Group, Biotechnology Research Institute, National Research Council Canada, Montreal, QC, Canada.
| | - Antonio Zorzano
- Department of Biochemistry and Molecular Biology, Faculty of Biology, Universitat de Barcelona, Av Diagonal 643, 08028, Barcelona, Spain. .,Institute for Research in Biomedicine (IRB Barcelona) and CIBER of Diabetes and Associated Metabolic Diseases (CIBERDEM), Barcelona, Spain.
| | - Philippe Rouet
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR 1048, Toulouse, France. .,Université Toulouse III Paul-Sabatier, Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), Equipe n°7, Toulouse, France.
| | - Marta Cascante
- Department of Biochemistry and Molecular Biology, Faculty of Biology, Universitat de Barcelona, Av Diagonal 643, 08028, Barcelona, Spain. .,Institute of Biomedicine of Universitat de Barcelona (IBUB) and CSIC-Associated Unit, Barcelona, Spain.
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12
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Kawakami Y, Yamanaka-Okumura H, Sakuma M, Mori Y, Adachi C, Matsumoto Y, Sato T, Yamamoto H, Taketani Y, Katayama T, Takeda E. Gene expression profiling in peripheral white blood cells in response to the intake of food with different glycemic index using a DNA microarray. JOURNAL OF NUTRIGENETICS AND NUTRIGENOMICS 2013; 6:154-68. [PMID: 24008923 DOI: 10.1159/000354247] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 07/07/2013] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIMS Transcriptomics technology in human nutrition intervention studies would allow for genome-wide screening of the effects of nutrients. We observed the time course of gene expression changes in peripheral white blood cells (WBC) to elucidate the metabolic changes in the postprandial state that are a reflection and a marker of whole body metabolic changes. METHODS In a randomized crossover study, 7 healthy subjects consumed test meals of glucose (GL), white rice (WR) and rolled barley (BAR), each containing 75 g of available carbohydrate, and water (WAT). Blood glucose, insulin and nonesterified fatty acid concentrations, as well as the subjective levels of fullness and hunger were measured. Microarray analysis of the WBC and the real-time PCR were examined during 360 min after the intake of the test meals. RESULTS The number of genes that changed more than 1.5-fold and the expression patterns in the time course were different between the GL, the WR and the BAR groups. Several genes involved in glycolysis and fatty acid β-oxidation were markedly changed after the intake of the GL, the WR and the BAR; however, these genes did not change at any time point in the WAT. CONCLUSIONS Gene expression profiling in the WBC can reflect food-related metabolic changes, even in the postprandial state.
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Affiliation(s)
- Yuka Kawakami
- Department of Clinical Nutrition, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima, Japan
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Abstract
The pyruvate dehydrogenase complex (PDC) activity is crucial to maintains blood glucose and ATP levels, which largely depends on the phosphorylation status by pyruvate dehydrogenase kinase (PDK) isoenzymes. Although it has been reported that PDC is phosphorylated and inactivated by PDK2 and PDK4 in metabolically active tissues including liver, skeletal muscle, heart, and kidney during starvation and diabetes, the precise mechanisms by which expression of PDK2 and PDK4 are transcriptionally regulated still remains unclear. Insulin represses the expression of PDK2 and PDK4 via phosphorylation of FOXO through PI3K/Akt signaling pathway. Several nuclear hormone receptors activated due to fasting or increased fat supply, including peroxisome proliferator-activated receptors, glucocorticoid receptors, estrogen-related receptors, and thyroid hormone receptors, also participate in the up-regulation of PDK2 and PDK4; however, the endogenous ligands that bind those nuclear receptors have not been identified. It has been recently suggested that growth hormone, adiponectin, epinephrine, and rosiglitazone also control the expression of PDK4 in tissue-specific manners. In this review, we discuss several factors involved in the expressional regulation of PDK2 and PDK4, and introduce current studies aimed at providing a better understanding of the molecular mechanisms that underlie the development of metabolic diseases such as diabetes.
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Affiliation(s)
- Ji Yun Jeong
- Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu, Korea
| | - Nam Ho Jeoung
- Department of Fundamental Medical & Pharmaceutical Sciences, Catholic University of Daegu, Daegu, Korea
| | - Keun-Gyu Park
- Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu, Korea
| | - In-Kyu Lee
- Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu, Korea
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Constantin-Teodosiu D, Constantin D, Stephens F, Laithwaite D, Greenhaff PL. The role of FOXO and PPAR transcription factors in diet-mediated inhibition of PDC activation and carbohydrate oxidation during exercise in humans and the role of pharmacological activation of PDC in overriding these changes. Diabetes 2012; 61:1017-24. [PMID: 22315317 PMCID: PMC3331777 DOI: 10.2337/db11-0799] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
High-fat feeding inhibits pyruvate dehydrogenase complex (PDC)-controlled carbohydrate (CHO) oxidation, which contributes to muscle insulin resistance. We aimed to reveal molecular changes underpinning this process in resting and exercising humans. We also tested whether pharmacological activation of PDC overrides these diet-induced changes. Healthy males consumed a control diet (CD) and on two further occasions an isocaloric high-fat diet (HFD). After each diet, subjects cycled for 60 min after intravenous infusion with saline (CD and HFD) or dichloroacetate (HFD+DCA). Quadriceps muscle biopsies obtained before and after 10 and 60 min of exercise were used to estimate CHO use, PDC activation, and mRNAs associated with insulin, fat, and CHO signaling. Compared with CD, HFD increased resting pyruvate dehydrogenase kinase 2 (PDK2), PDK4, forkhead box class O transcription factor 1 (FOXO1), and peroxisome proliferator-activated receptor transcription factor α (PPARα) mRNA and reduced PDC activation. Exercise increased PDC activation and whole-body CHO use in HFD, but to a lower extent than in CD. Meanwhile PDK4 and FOXO1, but not PPARα or PDK2, mRNA remained elevated. HFD+DCA activated PDC throughout and restored whole-body CHO use during exercise. FOXO1 appears to play a role in HFD-mediated muscle PDK4 upregulation and inhibition of PDC and CHO oxidation in humans. Also, pharmacological activation of PDC restores HFD-mediated inhibition of CHO oxidation during exercise.
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Kulkarni SS, Salehzadeh F, Fritz T, Zierath JR, Krook A, Osler ME. Mitochondrial regulators of fatty acid metabolism reflect metabolic dysfunction in type 2 diabetes mellitus. Metabolism 2012; 61:175-85. [PMID: 21816445 DOI: 10.1016/j.metabol.2011.06.014] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 06/17/2011] [Accepted: 06/20/2011] [Indexed: 10/25/2022]
Abstract
The delicate homeostatic balance between glucose and fatty acid metabolism in relation to whole-body energy regulation is influenced by mitochondrial function. We determined expression and regulation of mitochondrial enzymes including pyruvate dehydrogenase kinase (PDK) 4, PDK2, carnitine palmitoyltransferase 1b, and malonyl-coenzyme A decarboxylase in skeletal muscle from people with normal glucose tolerance (NGT) or type 2 diabetes mellitus (T2DM). Vastus lateralis biopsies were obtained from NGT (n = 79) or T2DM (n = 33) men and women matched for age and body mass index. A subset of participants participated in a 4-month lifestyle intervention program consisting of an unsupervised walking exercise. Muscle biopsies were analyzed for expression and DNA methylation status. Primary myotubes were derived from biopsies obtained from NGT individuals for metabolic studies. Cultured skeletal muscle was exposed to agents mimicking exercise activation for messenger RNA (mRNA) expression analysis. The mRNA expression of PDK4, PDK2, and malonyl-coenzyme A decarboxylase was increased in skeletal muscle from T2DM patients. Methylation of the PDK4 promoter was reduced in T2DM and inversely correlated with PDK4 expression. Moreover, PDK4 expression was positively correlated with body mass index, blood glucose, insulin, C peptide, and hemoglobin A(1c). A lifestyle intervention program resulted in increased PDK4 mRNA expression in NGT individuals, but not in those with T2DM. Exposure to caffeine or palmitate increased PDK4 mRNA in a cultured skeletal muscle system. Our findings reveal that skeletal muscle expression of PDK4 and related genes regulating mitochondrial function reflects alterations in substrate utilization and clinical features associated with T2DM. Furthermore, hypomethylation of the PDK4 promoter in T2DM coincided with an impaired response of PDK4 mRNA after exercise.
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MESH Headings
- Aged
- Biopsy
- Case-Control Studies
- Diabetes Mellitus, Type 2/complications
- Diabetes Mellitus, Type 2/genetics
- Diabetes Mellitus, Type 2/metabolism
- Diabetes Mellitus, Type 2/therapy
- Exercise Therapy
- Fatty Acids/metabolism
- Female
- Gene Expression Regulation, Enzymologic/physiology
- Humans
- Male
- Metabolic Diseases/etiology
- Metabolic Diseases/genetics
- Metabolic Diseases/metabolism
- Metabolic Diseases/therapy
- Middle Aged
- Mitochondria, Muscle/enzymology
- Mitochondria, Muscle/pathology
- Mitochondrial Proteins/genetics
- Mitochondrial Proteins/metabolism
- Mitochondrial Proteins/physiology
- Muscle, Skeletal/enzymology
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/pathology
- Risk Reduction Behavior
- Walking/physiology
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Affiliation(s)
- Sameer S Kulkarni
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
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16
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Oh YT, Oh KS, Choi YM, Jokiaho A, Donovan C, Choi S, Kang I, Youn JH. Continuous 24-h nicotinic acid infusion in rats causes FFA rebound and insulin resistance by altering gene expression and basal lipolysis in adipose tissue. Am J Physiol Endocrinol Metab 2011; 300:E1012-21. [PMID: 21386057 PMCID: PMC3118587 DOI: 10.1152/ajpendo.00650.2010] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Nicotinic acid (NA) has been used as a lipid drug for five decades. The lipid-lowering effects of NA are attributed to its ability to suppress lipolysis in adipocytes and lower plasma FFA levels. However, plasma FFA levels often rebound during NA treatment, offsetting some of the lipid-lowering effects of NA and/or causing insulin resistance, but the underlying mechanisms are unclear. The present study was designed to determine whether a prolonged, continuous NA infusion in rats produces a FFA rebound and/or insulin resistance. NA infusion rapidly lowered plasma FFA levels (>60%, P < 0.01), and this effect was maintained for ≥5 h. However, when this infusion was extended to 24 h, plasma FFA levels rebounded to the levels of saline-infused control rats. This was not due to a downregulation of NA action, because when the NA infusion was stopped, plasma FFA levels rapidly increased more than twofold (P < 0.01), indicating that basal lipolysis was increased. Microarray analysis revealed many changes in gene expression in adipose tissue, which would contribute to the increase in basal lipolysis. In particular, phosphodiesterase-3B gene expression decreased significantly, which would increase cAMP levels and thus lipolysis. Hyperinsulinemic glucose clamps showed that insulin's action on glucose metabolism was improved during 24-h NA infusion but became impaired with increased plasma FFA levels after cessation of NA infusion. In conclusion, a 24-h continuous NA infusion in rats resulted in an FFA rebound, which appeared to be due to altered gene expression and increased basal lipolysis in adipose tissue. In addition, our data support a previous suggestion that insulin resistance develops as a result of FFA rebound during NA treatment. Thus, the present study provides an animal model and potential molecular mechanisms of FFA rebound and insulin resistance, observed in clinical studies with chronic NA treatment.
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Affiliation(s)
- Young Taek Oh
- Department of Physiology and Biophysics, University of Southern California Keck School of Medicine, Los Angeles, CA 90089, USA
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17
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Tisdale PB, Seevaratnam N, Macdonald IA, Tsintzas K, Bennett AJ. Skeletal muscle metabolic gene expression is not affected by dichloroacetate-mediated modulation of substrate utilisation. ANNALS OF NUTRITION AND METABOLISM 2011; 58:19-24. [PMID: 21304220 DOI: 10.1159/000322971] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Accepted: 11/22/2010] [Indexed: 12/21/2022]
Abstract
AIM This study investigated whether changing fuel use, by increasing pyruvate dehydrogenase complex (PDC) flux, independently of plasma substrate availability and insulin signalling, would alter metabolic gene expression. METHODS The PDC activator, dichloroacetate (DCA), was administered as an intravenous infusion in healthy male subjects at a rate of 50 mg kg(-1) min(-1), for 90 min. Saline was infused as a control (CON) on a separate occasion in a randomised sequence. Muscle biopsies were taken from the vastus lateralis at 0 and 30 min into the infusion and 90 min after infusion. Gene expression was quantified using RT-qPCR, and immunoblotting was used to confirm that there were no changes in insulin signalling via the PI3K/Akt pathway. RESULTS Blood glucose concentrations fell during both trials but 3 h after the start of the infusion they were lower in DCA (p < 0.05) than CON. Blood lactate concentrations also declined in both trials (p < 0.01), however, this decrease was also more pronounced in DCA than CON (p < 0.001). Carbohydrate oxidation was increased by DCA, 0.037 ± 0.017 g min(-1) (p < 0.05) at 3 h with no change observed in CON. UCP3 and PGC1α mRNA expression were induced in CON (as a response to continued fasting) but this was attenuated by DCA. Akt phosphorylation and the expression of other metabolic genes and transcription factors were unchanged throughout the intervention. CONCLUSION It is concluded that PDC flux can be increased independently of plasma substrate availability, without causing downstream alterations to metabolic gene expression in the short term.
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Affiliation(s)
- Paul B Tisdale
- School of Biomedical Sciences, Queens Medical Centre, University of Nottingham, Nottingham, UK.
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18
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Choi S, Yoon H, Oh KS, Oh YT, Kim YI, Kang I, Youn JH. Widespread effects of nicotinic acid on gene expression in insulin-sensitive tissues: implications for unwanted effects of nicotinic acid treatment. Metabolism 2011; 60:134-44. [PMID: 20303128 PMCID: PMC2912158 DOI: 10.1016/j.metabol.2010.02.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2010] [Revised: 02/09/2010] [Accepted: 02/11/2010] [Indexed: 11/26/2022]
Abstract
Nicotinic acid (NA; or niacin) has been used as a hypolipidemic agent for more than 4 decades. However, the mechanisms underlying the effects of NA treatment (wanted and unwanted) are still poorly understood. In the present study, we discovered that NA infusion in rats resulted in dephosphorylation (ie, activation) of the forkhead transcription factor FOXO1 in insulin-sensitive tissues such as skeletal and cardiac muscles, liver, and adipose tissue. These NA effects were opposite to the effects of insulin to increase FOXO1 phosphorylation. To test whether NA alters gene expression in these tissues, rats were infused for 7 hours with NA (30 μmol/h) and/or insulin (5 mU/[kg min]); and gene expression was evaluated using a microarray analysis. Nicotinic acid had widespread effects on gene expression in all of the tissues studied, and the number of genes affected by NA greatly exceeded that of genes affected by insulin. A systematic (or strategic) analysis of the microarray data revealed that there were numerous genes whose expression was regulated inversely by insulin and NA in correlation with FOXO1 phosphorylation, representing potential FOXO1 target genes. We also identified a group of genes whose expression was altered by NA exclusively in adipose tissue, presumably because of stimulation of the NA receptor in this tissue. Finally, there were genes whose expression was altered by both NA and insulin, likely via lowering plasma free fatty acid levels, including lipoprotein lipase and adenosine triphosphate-binding cassette A1, which play a major role in the regulation of circulating lipids. Thus, our data suggest that NA alters gene expression in insulin-sensitive tissues by various mechanisms. Some of the NA-induced changes in gene expression are discussed as potential mechanisms underlying wanted and unwanted effects of NA treatment.
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Affiliation(s)
- Sangdun Choi
- Department of Molecular Science and Technology, Ajou University, Suwon, Korea
| | - Hana Yoon
- Department of Biochemistry and Molecular Biology, Kyung Hee University, School of Medicine, Seoul, Korea
- Department of Physiology and Biophysics, University of Southern California, Keck School of Medicine, Los Angeles, CA, USA
| | - Ki-Sook Oh
- Department of Physiology and Biophysics, University of Southern California, Keck School of Medicine, Los Angeles, CA, USA
| | - Young Taek Oh
- Department of Biochemistry and Molecular Biology, Kyung Hee University, School of Medicine, Seoul, Korea
- Department of Physiology and Biophysics, University of Southern California, Keck School of Medicine, Los Angeles, CA, USA
| | - Young I. Kim
- Department of Physiology and Biophysics, University of Southern California, Keck School of Medicine, Los Angeles, CA, USA
| | - Insug Kang
- Department of Biochemistry and Molecular Biology, Kyung Hee University, School of Medicine, Seoul, Korea
| | - Jang H. Youn
- Department of Physiology and Biophysics, University of Southern California, Keck School of Medicine, Los Angeles, CA, USA
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Nie J, DuBois DC, Jusko WJ, Almon RR. Mechanistic population modeling of diabetes disease progression in Goto-Kakizaki rat muscle. Biopharm Drug Dispos 2010; 32:50-63. [PMID: 21162119 DOI: 10.1002/bdd.738] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Revised: 11/04/2010] [Accepted: 11/05/2010] [Indexed: 12/31/2022]
Abstract
Pyruvate dehydrogenase kinase 4 (PDK4) is a lipid status responsive gene involved in muscle fuel selection. Evidence is mounting in support of the therapeutic potential of PDK4 inhibitors to treat diabetes. Factors that regulate PDK4 mRNA expression include plasma corticosterone, insulin and free fatty acids. The objective was to determine the impact of those plasma factors on PDK4 mRNA and to develop and validate a population mathematical model to differentiate aging, diet and disease effects on muscle PDK4 expression. The Goto-Kakizaki (GK) rat, a polygenic non-obese model of type 2 diabetes, was used as the diabetic animal model. Muscle PDK4 mRNA expression was examined by real-time QRTPCR. Groups of GK rats along with controls fed with either a normal or high fat diet were killed at 4, 8, 12, 16 and 20 weeks of age. Plasma corticosterone, insulin and free fatty acids were measured. The proposed mechanism-based model successfully described the age, disease and diet effects and the relative contribution of these plasma regulators on PDK4 mRNA expression. Muscle growth reduced the PDK4 mRNA production rate by 14% per gram increase. The high fat diet increased the initial production rate constant in GK rats by 2.19-fold. The model indicated that corticosterone had a moderate effect and PDK4 was more sensitive to free fatty acid than insulin fluxes, which was in good agreement with the literature data.
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Affiliation(s)
- Jing Nie
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, NY 14260, USA
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20
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Awad S, Constantin-Teodosiu D, Constantin D, Rowlands BJ, Fearon KCH, Macdonald IA, Lobo DN. Cellular Mechanisms Underlying the Protective Effects of Preoperative Feeding. Ann Surg 2010; 252:247-53. [DOI: 10.1097/sla.0b013e3181e8fbe6] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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21
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Folmes CD, Sawicki G, Cadete VJ, Masson G, Barr AJ, Lopaschuk GD. Novel O-palmitolylated beta-E1 subunit of pyruvate dehydrogenase is phosphorylated during ischemia/reperfusion injury. Proteome Sci 2010; 8:38. [PMID: 20618950 PMCID: PMC2909933 DOI: 10.1186/1477-5956-8-38] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Accepted: 07/09/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND During and following myocardial ischemia, glucose oxidation rates are low and fatty acids dominate as a source of oxidative metabolism. This metabolic phenotype is associated with contractile dysfunction during reperfusion. To determine the mechanism of this reliance on fatty acid oxidation as a source of ATP generation, a functional proteomics approach was utilized. RESULTS 2-D gel electrophoresis of mitochondria from working rat hearts subjected to 25 minutes of global no flow ischemia followed by 40 minutes of aerobic reperfusion identified 32 changes in protein abundance compared to aerobic controls. Of the five proteins with the greatest change in abundance, two were increased (long chain acyl-coenzyme A dehydrogenase (48 +/- 1 versus 39 +/- 3 arbitrary units, n = 3, P < 0.05) and alpha subunit of ATP synthase (189 +/- 15 versus 113 +/- 23 arbitrary units, n = 3, P < 0.05)), while two were decreased (24 kDa subunit of NADH-ubiquinone oxidoreductase (94 +/- 7 versus 127 +/- 9 arbitrary units, n = 3, P < 0.05) and D subunit of ATP synthase (230 +/- 11 versus 368 +/- 47 arbitrary units, n = 3, P < 05)). Two forms of pyruvate dehydrogenase betaE1 subunit, the rate-limiting enzyme for glucose oxidation, were also identified. The protein level of the more acidic form of pyruvate dehydrogenase was reduced during reperfusion (37 +/- 4 versus 56 +/- 7 arbitrary units, n = 3, P < 05), while the more basic form remained unchanged. The more acidic isoform was found to be O-palmitoylated, while both isoforms exhibited ischemia/reperfusion-induced phosphorylation. In silico analysis identified the putative kinases as the insulin receptor kinase for the more basic form and protein kinase Czeta or protein kinase A for the more acidic form. These modifications of pyruvate dehydrogenase are associated with a 35% decrease in glucose oxidation during reperfusion. CONCLUSIONS Cardiac ischemia/reperfusion induces significant changes to a number of metabolic proteins of the mitochondrial proteome. In particular, ischemia/reperfusion induced the post-translational modification of pyruvate dehydrogenase, the rate-limiting step of glucose oxidation, which is associated with a 35% decrease in glucose oxidation during reperfusion. Therefore these post-translational modifications may have important implications in the regulation of myocardial energy metabolism.
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Affiliation(s)
- Clifford Dl Folmes
- Cardiovascular Research Group and the Departments of Pharmacology and Pediatrics, The University of Alberta, Edmonton, Alberta, Canada
| | - Grzegorz Sawicki
- Department of Pharmacology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.,Department of Clinical Chemistry, Medical University of Wroclaw, Wroclaw, Poland
| | - Virgilio Jj Cadete
- Department of Pharmacology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Grant Masson
- Cardiovascular Research Group and the Departments of Pharmacology and Pediatrics, The University of Alberta, Edmonton, Alberta, Canada
| | - Amy J Barr
- Cardiovascular Research Group and the Departments of Pharmacology and Pediatrics, The University of Alberta, Edmonton, Alberta, Canada
| | - Gary D Lopaschuk
- Cardiovascular Research Group and the Departments of Pharmacology and Pediatrics, The University of Alberta, Edmonton, Alberta, Canada
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22
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Activation of PPARdelta up-regulates fatty acid oxidation and energy uncoupling genes of mitochondria and reduces palmitate-induced apoptosis in pancreatic beta-cells. Biochem Biophys Res Commun 2009; 391:1567-72. [PMID: 20040361 DOI: 10.1016/j.bbrc.2009.12.127] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Accepted: 12/22/2009] [Indexed: 02/05/2023]
Abstract
Recent evidence indicates that decreased oxidative capacity, lipotoxicity, and mitochondrial aberrations contribute to the development of insulin resistance and type 2 diabetes. The goal of this study was to investigate the effects of peroxisome proliferator-activated receptor delta (PPARdelta) activation on lipid oxidation, mitochondrial function, and insulin secretion in pancreatic beta-cells. After HIT-T15 cells (a beta-cell line) were exposed to high concentrations of palmitate and GW501516 (GW; a selective agonist of PPARdelta), we found that administration of GW increased the expression of PPARdelta mRNA. GW-induced activation of PPARdelta up-regulated carnitine palmitoyltransferase 1 (CPT1), long-chain acyl-CoA dehydrogenase (LCAD), pyruvate dehydrogenase kinase 4 (PDK4), and uncoupling protein 2 (UCP2); alleviated mitochondrial swelling; attenuated apoptosis; and reduced basal insulin secretion induced by increased palmitate in HIT cells. These results suggest that activation of PPARdelta plays an important role in protecting pancreatic beta-cells against aberrations caused by lipotoxicity in metabolic syndrome and diabetes.
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23
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Loh K, Deng H, Fukushima A, Cai X, Boivin B, Galic S, Bruce C, Shields BJ, Skiba B, Ooms LM, Stepto N, Wu B, Mitchell CA, Tonks NK, Watt MJ, Febbraio MA, Crack PJ, Andrikopoulos S, Tiganis T. Reactive oxygen species enhance insulin sensitivity. Cell Metab 2009; 10:260-72. [PMID: 19808019 PMCID: PMC2892288 DOI: 10.1016/j.cmet.2009.08.009] [Citation(s) in RCA: 460] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Revised: 06/23/2009] [Accepted: 08/19/2009] [Indexed: 12/15/2022]
Abstract
Chronic reactive oxygen species (ROS) production by mitochondria may contribute to the development of insulin resistance, a primary feature of type 2 diabetes. In recent years it has become apparent that ROS generation in response to physiological stimuli such as insulin may also facilitate signaling by reversibly oxidizing and inhibiting protein tyrosine phosphatases (PTPs). Here we report that mice lacking one of the key enzymes involved in the elimination of physiological ROS, glutathione peroxidase 1 (Gpx1), were protected from high-fat-diet-induced insulin resistance. The increased insulin sensitivity in Gpx1(-/-) mice was attributed to insulin-induced phosphatidylinositol-3-kinase/Akt signaling and glucose uptake in muscle and could be reversed by the antioxidant N-acetylcysteine. Increased insulin signaling correlated with enhanced oxidation of the PTP family member PTEN, which terminates signals generated by phosphatidylinositol-3-kinase. These studies provide causal evidence for the enhancement of insulin signaling by ROS in vivo.
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Affiliation(s)
- Kim Loh
- Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
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Potential dysregulation of the pyruvate dehydrogenase complex by bacterial toxins and insulin. ACTA ACUST UNITED AC 2009; 67:628-33. [PMID: 19741411 DOI: 10.1097/ta.0b013e3181a8b415] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The pyruvate dehydrogenase complex (PDC) catalyzes the conversion of pyruvate to acetyl CoA, effectively controlling the entrance of glycolysis products into aerobic metabolism. Because hyperlactatemia is one of the hallmarks of sepsis, we hyphothesized that gram-positive and negative bacterial toxin treatment will interfere with mRNA levels of regulatory enzymes of the PDC and overall enzyme activity in hepatocytes. METHODS HEP G2 hepatocarcinoma cells were incubated for 24 hours in the presence of lipopolysaccaride (LPS) or lipoteichoic acid. Total RNA was then isolated and message RNA levels for both pyruvate dehydrogense kinase 4 and phosphatase 2 were determined by RTPCR. Amplified DNA fragments were visualized by ethidium bromide in agarose gels and densitometry of the bands was performed. Data were then normalized to the housekeeping gene, GAPDH. Enzyme activity was then determined by capturing intact PDC on nitrocellulose membranes then determining PDC-dependent production of NADH. RESULTS LPS treatment led to a time dependent increase in PDK4 message while decreasing PDP2 levels. Enzyme activity, in these cells, also significantly decreased 24 hours after exposure to LPS. Cells cultured in the presence of lipoteichoic acid and insulin exhibited differing message ratios and activity levels when evaluated at 4 hours, but at 24 hours shifted to mimic those observed in LPS treated cells. CONCLUSION This data may indicate that exposure to bacterial cell wall components and insulin could create cellular environments that result in a build-up of lactate.
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25
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Hoy AJ, Brandon AE, Turner N, Watt MJ, Bruce CR, Cooney GJ, Kraegen EW. Lipid and insulin infusion-induced skeletal muscle insulin resistance is likely due to metabolic feedback and not changes in IRS-1, Akt, or AS160 phosphorylation. Am J Physiol Endocrinol Metab 2009; 297:E67-75. [PMID: 19366875 PMCID: PMC2711668 DOI: 10.1152/ajpendo.90945.2008] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Type 2 diabetes is characterized by hyperlipidemia, hyperinsulinemia, and insulin resistance. The aim of this study was to investigate whether acute hyperlipidemia-induced insulin resistance in the presence of hyperinsulinemia was due to defective insulin signaling. Hyperinsulinemia (approximately 300 mU/l) with hyperlipidemia or glycerol (control) was produced in cannulated male Wistar rats for 0.5, 1 h, 3 h, or 5 h. The glucose infusion rate required to maintain euglycemia was significantly reduced by 3 h with lipid infusion and was further reduced after 5 h of infusion, with no difference in plasma insulin levels, indicating development of insulin resistance. Consistent with this finding, in vivo skeletal muscle glucose uptake (31%, P < 0.05) and glycogen synthesis rate (38%, P < 0.02) were significantly reduced after 5 h compared with 3 h of lipid infusion. Despite the development of insulin resistance, there was no difference in the phosphorylation state of multiple insulin-signaling intermediates or muscle diacylglyceride and ceramide content over the same time course. However, there was an increase in cumulative exposure to long-chain acyl-CoA (70%) with lipid infusion. Interestingly, although muscle pyruvate dehydrogenase kinase 4 protein content was decreased in hyperinsulinemic glycerol-infused rats, this decrease was blunted in muscle from hyperinsulinemic lipid-infused rats. Decreased pyruvate dehydrogenase complex activity was also observed in lipid- and insulin-infused animals (43%). Overall, these results suggest that acute reductions in muscle glucose metabolism in rats with hyperlipidemia and hyperinsulinemia are more likely a result of substrate competition than a significant early defect in insulin action or signaling.
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Affiliation(s)
- Andrew J Hoy
- Diabetes and Obesity Research Program, Garvan Institute of Medical Research, Darlinghurst, University of New South Wales, Sydney, New South Wales, Australia.
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26
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McAinch AJ, Cameron-Smith D. Adiponectin decreases pyruvate dehydrogenase kinase 4 gene expression in obese- and diabetic-derived myotubes. Diabetes Obes Metab 2009; 11:721-8. [PMID: 19527483 DOI: 10.1111/j.1463-1326.2009.01042.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
AIM To investigate the effects of globular adiponectin (gAd) on gene expression and whether these effects are mediated through 3',5'-cyclic monophosphate-activated protein kinase in skeletal muscle myotubes obtained from lean, obese and obese diabetic individuals. METHODS Rectus abdominus muscle biopsies were obtained from surgical patients to establish primary skeletal muscle cell cultures. Three distinct primary cell culture groups were established (lean, obese and obese diabetic; n = 7 in each group). Once differentiated, these cultures were then exposed to gAd or 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR) for 6 h. RESULTS Stimulation with gAd decreased pyruvate dehydrogenase kinase 4 (PDK4) gene expression in the obese and diabetic samples (p < or = 0.05) and increased cytochrome c oxidase (COX) subunit 4 (COXIV) gene expression in the myotubes derived from lean individuals only (p < 0.05). AICAR treatment also decreased PDK4 gene expression in the obese- and diabetic-derived myotubes (p < or = 0.05) and increased the gene expression of the mitochondrial gene, COXIII, in the lean-derived samples only (p < 0.05). CONCLUSIONS This study demonstrated distinct disparity between myotubes derived from lean compared with obese and obese diabetic individuals following gAd and AICAR treatment. Further understanding of the regulation of PDK4 in obese and diabetic skeletal muscle and its interaction with adiponectin signalling is required as this appears to be an important early molecular event in these disease states that may improve blood glucose control and metabolic flux.
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Affiliation(s)
- A J McAinch
- School of Biomedical and Health Sciences, Victoria University, PO Box 14428, Melbourne, Victoria 8001, Australia.
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Constantin-Teodosiu D, Baker DJ, Constantin D, Greenhaff PL. PPARdelta agonism inhibits skeletal muscle PDC activity, mitochondrial ATP production and force generation during prolonged contraction. J Physiol 2008; 587:231-9. [PMID: 19001043 DOI: 10.1113/jphysiol.2008.164210] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
We have recently shown that PPARdelta agonism, used clinically to treat insulin resistance, increases fat oxidation and up-regulates mitochondrial PDK4 mRNA and protein expression in resting skeletal muscle. We hypothesized that PDK4 up-regulation, which inhibits pyruvate dehydrogenase complex (PDC)-dependent carbohydrate (CHO) oxidation, would negatively affect muscle function during sustained contraction where the demand on CHO is markedly increased. Three groups of eight male Wistar rats each received either vehicle or a PPARdelta agonist (GW610742X) at two doses (5 and 100 mg (kg body mass (bm))(-1) orally for 6 days. On the seventh day, the gastrocnemius-soleus-plantaris muscle group was isolated and snap frozen, or underwent 30 min of electrically evoked submaximal intensity isometric contraction using a perfused hindlimb model. During contraction, the rate of muscle PDC activation was significantly lower at 100 mg (kg bm)(-1) compared with control (P < 0.01). Furthermore, the rates of muscle PCr hydrolysis and lactate accumulation were significantly increased at 100 mg (kg bm)(-1) compared with control, reflecting lower mitochondrial ATP generation. Muscle tension development during contraction was significantly lower at 100 mg (kg bm)(-1) compared with control (25%; P < 0.05). The present data demonstrate that PPARdelta agonism inhibits muscle CHO oxidation at the level of PDC during prolonged contraction, and is paralleled by the activation of anaerobic metabolism, which collectively impair contractile function.
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Affiliation(s)
- Dumitru Constantin-Teodosiu
- Centre for Integrated Systems Biology and Medicine, Queens Medical Centre, University of Nottingham Medical School, Nottingham NG7 2UH, UK.
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28
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Schummer CM, Werner U, Tennagels N, Schmoll D, Haschke G, Juretschke HP, Patel MS, Gerl M, Kramer W, Herling AW. Dysregulated pyruvate dehydrogenase complex in Zucker diabetic fatty rats. Am J Physiol Endocrinol Metab 2008; 294:E88-96. [PMID: 17957038 DOI: 10.1152/ajpendo.00178.2007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The mitochondrial pyruvate dehydrogenase complex (PDC) is inactivated in many tissues during starvation and diabetes. We investigated carbohydrate oxidation (CHO) and the regulation of the PDC in lean and obese Zucker diabetic fatty (ZDF) rats during fed and starved conditions as well as during an oral glucose load without and with pharmacologically reduced levels of free fatty acids (FFA) to estimate the relative contribution of FFA on glucose tolerance, CHO, and PDC activity. The increase in total PDC activity (20-45%) was paralleled by increased protein levels ( approximately 2-fold) of PDC subunits in liver and muscle of obese ZDF rats. Pyruvate dehydrogenase kinase-4 (PDK4) protein levels were higher in obese rats, and consequently PDC activity was reduced. Although PDK4 protein levels were rapidly downregulated (57-62%) in both lean and obese animals within 2 h after glucose challenge, CHO over 3 h as well as the peak of PDC activity (1 h after glucose load) in liver and muscle were significantly lower in obese rats compared with lean rats. Similar differences were obtained with pharmacologically suppressed FFA by nicotinic acid, but with significantly improved glucose tolerance in obese rats, as well as increased CHO and delta increases in PDC activity (0-60 min) both in muscle and liver. These results demonstrated the suppressive role of FFA acids on the measured parameters. Furthermore, the results clearly demonstrate a rapid reactivation of PDC in liver and muscle of lean and obese rats after a glucose load and show that PDC activity is significantly lower in obese ZDF rats.
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Affiliation(s)
- Christoph M Schummer
- Sanofi-Aventis Deutschland GmbH, Industriepark Hoechst, 65926 Frankfurt am Main, Germany
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29
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Rodriguez A, Hilvo M, Kytömäki L, Fleming RE, Britton RS, Bacon BR, Parkkila S. Effects of iron loading on muscle: genome-wide mRNA expression profiling in the mouse. BMC Genomics 2007; 8:379. [PMID: 17949489 PMCID: PMC2151772 DOI: 10.1186/1471-2164-8-379] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2007] [Accepted: 10/19/2007] [Indexed: 01/03/2023] Open
Abstract
Background Hereditary hemochromatosis (HH) encompasses genetic disorders of iron overload characterized by deficient expression or function of the iron-regulatory hormone hepcidin. Mutations in 5 genes have been linked to this disease: HFE, TFR2 (encoding transferrin receptor 2), HAMP (encoding hepcidin), SLC40A1 (encoding ferroportin) and HJV (encoding hemojuvelin). Hepcidin inhibits iron export from cells into plasma. Hemojuvelin, an upstream regulator of hepcidin expression, is expressed in mice mainly in the heart and skeletal muscle. It has been suggested that soluble hemojuvelin shed by the muscle might reach the liver to influence hepcidin expression. Heart muscle is one of the target tissues affected by iron overload, with resultant cardiomyopathy in some HH patients. Therefore, we investigated the effect of iron overload on gene expression in skeletal muscle and heart using Illumina™ arrays containing over 47,000 probes. The most apparent changes in gene expression were confirmed using real-time RT-PCR. Results Genes with up-regulated expression after iron overload in both skeletal and heart muscle included angiopoietin-like 4, pyruvate dehydrogenase kinase 4 and calgranulin A and B. The expression of transferrin receptor, heat shock protein 1B and DnaJ homolog B1 were down-regulated by iron in both muscle types. Two potential hepcidin regulatory genes, hemojuvelin and neogenin, showed no clear change in expression after iron overload. Conclusion Microarray analysis revealed iron-induced changes in the expression of several genes involved in the regulation of glucose and lipid metabolism, transcription and cellular stress responses. These may represent novel connections between iron overload and pathological manifestations of HH such as cardiomyopathy and diabetes.
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Affiliation(s)
- Alejandra Rodriguez
- Institute of Medical Technology, University of Tampere and Tampere University Hospital, Tampere, Finland.
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30
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Tsintzas K, Chokkalingam K, Jewell K, Norton L, Macdonald IA, Constantin-Teodosiu D. Elevated free fatty acids attenuate the insulin-induced suppression of PDK4 gene expression in human skeletal muscle: potential role of intramuscular long-chain acyl-coenzyme A. J Clin Endocrinol Metab 2007; 92:3967-72. [PMID: 17652214 DOI: 10.1210/jc.2007-1104] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
AIM We investigated the effect of elevated plasma free fatty acid and insulin concentrations on PDK4 mRNA transcript and protein content and long-chain acyl-coenzyme A accumulation in human skeletal muscle. METHODS On two occasions, 10 healthy men underwent hyperinsulinemic-euglycemic clamps for 6 h with (LIPID) and without (CON) iv Intralipid (20% at 90 ml/h) plus heparin (200 U prime + 600 U/h) infusion. RESULTS Glucose disposal was approximately 50% lower at the end of the clamp in the LIPID compared with the CON trial (37.8 +/- 4.4 and 79.6 +/- 4.0 micromol/kg lean mass.min, respectively; P < 0.01). In the LIPID trial, muscle long-chain acyl-coenzyme A concentration increased after 6 h, but not 3 h of lipid infusion (P < 0.01). Muscle PDK4 mRNA, but not protein, was down-regulated by 2-fold within 3 h in both clamps and decreased further (6-fold; P < 0.01) at 6 h in the CON but not the LIPID clamp. The lipid-induced attenuation in the suppression of PDK4 gene expression was not dependent on the activation of the Akt/FOXO3 pathway. CONCLUSION Accumulation of im lipids plays a more important role than impaired activation of Akt-mediated pathways in the regulation of muscle PDK4 gene expression in lipid-induced acute insulin-resistant states.
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Affiliation(s)
- Kostas Tsintzas
- Centre for Integrated Systems Biology and Medicine, Institute of Clinical Research, School of Biomedical Sciences, University of Nottingham, Nottingham NG7 2UH, United Kingdom.
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31
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White UA, Coulter AA, Miles TK, Stephens JM. The STAT5A-mediated induction of pyruvate dehydrogenase kinase 4 expression by prolactin or growth hormone in adipocytes. Diabetes 2007; 56:1623-9. [PMID: 17360981 DOI: 10.2337/db06-1286] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The purpose of this study was to determine whether pyruvate dehydrogenase kinase (PDK)4 was expressed in adipocytes and whether PDK4 expression was hormonally regulated in fat cells. Both Northern blot and Western blot analyses were conducted on samples isolated from 3T3-L1 adipocytes after various treatments with prolactin (PRL), growth hormone (GH), and/or insulin. Transfection of PDK4 promoter reporter constructs was performed. In addition, glucose uptake measurements were conducted. Our studies demonstrate that PRL and porcine GH can induce the expression of PDK4 in 3T3-L1 adipocytes. Our studies also show that insulin pretreatment can attenuate the ability of these hormones to induce PDK4 mRNA expression. In addition, we identified a hormone-responsive region in the murine PDK4 promoter and characterized a STAT5 binding site in this region that mediates the PRL (sheep) and GH (porcine) induction in PDK4 expression in 3T3-L1 adipocytes. PDK4 is a STAT5A target gene. PRL is a potent inducer of PDK4 protein levels, results in an inhibition of insulin-stimulated glucose transport in fat cells, and likely contributes to PRL-induced insulin resistance.
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Affiliation(s)
- Ursula A White
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, USA
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32
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Pilegaard H, Birk JB, Sacchetti M, Mourtzakis M, Hardie DG, Stewart G, Neufer PD, Saltin B, van Hall G, Wojtaszewski JFP. PDH-E1alpha dephosphorylation and activation in human skeletal muscle during exercise: effect of intralipid infusion. Diabetes 2006; 55:3020-7. [PMID: 17065338 DOI: 10.2337/db06-0152] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
To investigate pyruvate dehydrogenase (PDH)-E1alpha subunit phosphorylation and whether free fatty acids (FFAs) regulate PDH activity, seven subjects completed two trials: saline (control) and intralipid/heparin (intralipid). Each infusion trial consisted of a 4-h rest followed by a 3-h two-legged knee extensor exercise at moderate intensity. During the 4-h resting period, activity of PDH in the active form (PDHa) did not change in either trial, yet phosphorylation of PDH-E1alpha site 1 (PDH-P1) and site 2 (PDH-P2) was elevated in the intralipid compared with the control trial. PDHa activity increased during exercise similarly in the two trials. After 3 h of exercise, PDHa activity remained elevated in the intralipid trial but returned to resting levels in the control trial. Accordingly, in both trials PDH-P1 and PDH-P2 decreased during exercise, and the decrease was more marked during intralipid infusion. Phosphorylation had returned to resting levels at 3 h of exercise only in the control trial. Thus, an inverse association between PDH-E1alpha phosphorylation and PDHa activity exists. Short-term elevation in plasma FFA at rest increases PDH-E1alpha phosphorylation, but exercise overrules this effect of FFA on PDH-E1alpha phosphorylation leading to even greater dephosphorylation during exercise with intralipid infusion than with saline.
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MESH Headings
- Adult
- DNA, Complementary/genetics
- Enzyme Activation
- Exercise/physiology
- Fat Emulsions, Intravenous/administration & dosage
- Fat Emulsions, Intravenous/pharmacology
- Fatty Acids, Nonesterified/blood
- Glycogen/metabolism
- Humans
- Infusions, Intravenous
- Knee Joint
- Mitochondria, Muscle/drug effects
- Mitochondria, Muscle/enzymology
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/enzymology
- Muscle, Skeletal/physiology
- Phosphorylation
- Pyruvate Dehydrogenase (Lipoamide)/genetics
- Pyruvate Dehydrogenase (Lipoamide)/metabolism
- RNA/genetics
- RNA/isolation & purification
- Rest
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33
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Kim YI, Lee FN, Choi WS, Lee S, Youn JH. Insulin regulation of skeletal muscle PDK4 mRNA expression is impaired in acute insulin-resistant states. Diabetes 2006; 55:2311-7. [PMID: 16873695 DOI: 10.2337/db05-1606] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We previously showed that insulin has a profound effect to suppress pyruvate dehydrogenase kinase (PDK) 4 expression in rat skeletal muscle. In the present study, we examined whether insulin's effect on PDK4 expression is impaired in acute insulin-resistant states and, if so, whether this change is accompanied by decreased insulin's effects to stimulate Akt and forkhead box class O (FOXO) 1 phosphorylation. To induce insulin resistance, conscious overnight-fasted rats received a constant infusion of Intralipid or lactate for 5 h, while a control group received saline infusion. Following the initial infusions, each group received saline or insulin infusion (n = 6 or 7 each) for an additional 5 h, while saline, Intralipid, or lactate infusion was continued. Plasma glucose was clamped at basal levels during the insulin infusion. Compared with the control group, Intralipid and lactate infusions decreased glucose infusion rates required to clamp plasma glucose by approximately 60% (P < 0.01), confirming the induction of insulin resistance. Insulin's ability to suppress PDK4 mRNA level was impaired in skeletal muscle with Intralipid and lactate infusions, resulting in two- to threefold higher PDK4 mRNA levels with insulin (P < 0.05). Insulin stimulation of Akt and FOXO1 phosphorylation was also significantly decreased with Intralipid and lactate infusions. These data suggest that insulin's effect to suppress PDK4 gene expression in skeletal muscle is impaired in insulin-resistant states, and this may be due to impaired insulin signaling for stimulation of Akt and FOXO1 phosphorylation. Impaired insulin's effect to suppress PDK4 expression may explain the association between PDK4 overexpression and insulin resistance in skeletal muscle.
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Affiliation(s)
- Young I Kim
- Department of Physiology and Biophysics, University of Southern California Keck School of Medicine, 1333 San Pablo St., MMR 626, Los Angeles, 90089-9142, USA
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34
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Sugden MC, Holness MJ. Mechanisms underlying regulation of the expression and activities of the mammalian pyruvate dehydrogenase kinases. Arch Physiol Biochem 2006; 112:139-49. [PMID: 17132539 DOI: 10.1080/13813450600935263] [Citation(s) in RCA: 191] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The mechanisms that control mammalian pyruvate dehydrogenase complex (PDC) activity include its phosphorylation (inactivation) by a family of pyruvate dehydrogenase kinases (PDKs 1 - 4). Here we review new developments in the regulation of the activities and expression of the PDKs, in particular PDK2 and PDK4, in relation to glucose and lipid homeostasis. This review describes recent advances relating to the acute and long-term modes of regulation of the PDKs, with particular emphasis on the regulatory roles of nuclear receptors including peroxisome proliferator-activated receptor (PPAR) alpha and Liver X receptor (LXR), PPAR gamma coactivator alpha (PGC-1alpha) and insulin, and the impact of changes in PDK activity and expression in glucose and lipid homeostasis. Since PDK4 may assist in lipid clearance when there is an imbalance between lipid delivery and oxidation, it may represent an attractive target for interventions aimed at rectifying abnormal lipid as well as glucose homeostasis in disease states.
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Affiliation(s)
- Mary C Sugden
- Centre for Diabetes and Metabolic Medicine, Institute of Cell and Molecular Science, Bart's and the London, Queen Mary's School of Medicine and Dentistry, London, UK.
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35
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Xu J, Han J, Epstein PN, Liu YQ. Regulation of PDK mRNA by high fatty acid and glucose in pancreatic islets. Biochem Biophys Res Commun 2006; 344:827-33. [PMID: 16631612 DOI: 10.1016/j.bbrc.2006.03.211] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2006] [Accepted: 03/31/2006] [Indexed: 11/30/2022]
Abstract
Pyruvate dehydrogenase (PDH) converts pyruvate to acetyl-CoA, links glycolysis to the Krebs cycle, and plays an important role in glucose metabolism and insulin secretion in pancreatic beta cells. In beta cells from obese and Type 2 diabetic animals, PDH activity is significantly reduced. PDH is negatively regulated by multiple pyruvate dehydrogenase kinase (PDK) isotypes (PDK subtypes 1-4). However, we do not know whether fatty acids or high glucose modulate PDKs in islets. To test this we determined PDH and PDK activities and PDK gene and protein expression in C57BL/6 mouse islets. Both high palmitate and high glucose reduced active PDH activity and increased PDK activity. The gene and protein for PDK3 were not expressed in islets. Palmitate up-regulated mRNA expression of PDK1 (2.9-fold), PDK2 (1.9-fold), and PDK4 (3.1-fold). High glucose increased PDK1 (1.8-fold) and PDK2 (2.7-fold) mRNA expression but reduced PDK4 mRNA expression by 40 percent in cultured islets. Changed PDK expression was confirmed by Western blotting. These results demonstrate that in islet cells both fat and glucose regulate PDK gene and protein expression and indicate that hyperglycemia and hyperlipidemia contribute to the decline in diabetic islet PDH activity by increasing mRNA and protein expression of PDK.
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Affiliation(s)
- Jianxiang Xu
- Kosair Children's Hospital Research Institute, Department of Pediatrics, University of Louisville School of Medicine, Louisville, KY 40292, USA
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36
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Civitarese AE, Hesselink MKC, Russell AP, Ravussin E, Schrauwen P. Glucose ingestion during exercise blunts exercise-induced gene expression of skeletal muscle fat oxidative genes. Am J Physiol Endocrinol Metab 2005; 289:E1023-9. [PMID: 16030063 DOI: 10.1152/ajpendo.00193.2005] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Ingestion of carbohydrate during exercise may blunt the stimulation of fat oxidative pathways by raising plasma insulin and glucose concentrations and lowering plasma free fatty acid (FFA) levels, thereby causing a marked shift in substrate oxidation. We investigated the effects of a single 2-h bout of moderate-intensity exercise on the expression of key genes involved in fat and carbohydrate metabolism with or without glucose ingestion in seven healthy untrained men (22.7 +/- 0.6 yr; body mass index: 23.8 +/- 1.0 kg/m(2); maximal O(2) consumption: 3.85 +/- 0.21 l/min). Plasma FFA concentration increased during exercise (P < 0.01) in the fasted state but remained unchanged after glucose ingestion, whereas fat oxidation (indirect calorimetry) was higher in the fasted state vs. glucose feeding (P < 0.05). Except for a significant decrease in the expression of pyruvate dehydrogenase kinase-4 (P < 0.05), glucose ingestion during exercise produced minimal effects on the expression of genes involved in carbohydrate utilization. However, glucose ingestion resulted in a decrease in the expression of genes involved in fatty acid transport and oxidation (CD36, carnitine palmitoyltransferase-1, uncoupling protein 3, and 5'-AMP-activated protein kinase-alpha(2); P < 0.05). In conclusion, glucose ingestion during exercise decreases the expression of genes involved in lipid metabolism rather than increasing genes involved in carbohydrate metabolism.
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Affiliation(s)
- Anthony E Civitarese
- Dept. of Human Physiology, Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, LA 70808, USA
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37
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Cluberton LJ, McGee SL, Murphy RM, Hargreaves M. Effect of carbohydrate ingestion on exercise-induced alterations in metabolic gene expression. J Appl Physiol (1985) 2005; 99:1359-63. [PMID: 15932964 DOI: 10.1152/japplphysiol.00197.2005] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Skeletal muscle possesses a high degree of plasticity and can adapt to both the physical and metabolic challenges that it faces. An acute bout of exercise is sufficient to induce the expression of a variety of metabolic genes, such as GLUT4, pyruvate dehydrogenase kinase 4 (PDK-4), uncoupling protein-3 (UCP3), and peroxisome proliferator-activated receptor-γ coactivator 1 (PGC-1). Reducing muscle glycogen levels before exercise potentiates the effect of exercise on many genes. Similarly, altered substrate availability induces transcription of many of these genes. The purpose of this study was to determine whether glucose ingestion attenuates the exercise-induced increase in a variety of exercise-responsive genes. Six male subjects (28 ± 7 yr; 83 ± 3 kg; peak pulmonary oxygen uptake = 46 ± 6 ml·kg−1·min−1) performed 60 min of cycling at 74 ± 2% of peak pulmonary oxygen uptake on two separate occasions. On one occasion, subjects ingested a 6% carbohydrate drink. On the other occasion, subjects ingested an equal volume of a sweet placebo. Muscle samples were obtained from vastus lateralis at rest, immediately after exercise, and 3 h after exercise. PDK-4, UCP3, PGC-1, and GLUT4 mRNA levels were measured on these samples using real-time RT-PCR. Glucose ingestion attenuated ( P < 0.05) the exercise-induced increase in PDK-4 and UCP3 mRNA. A similar trend ( P = 0.09) was observed for GLUT4 mRNA. In contrast, PGC-1 mRNA increased following exercise to the same extent in both conditions. These data suggest that glucose availability can modulate the effect of exercise on metabolic gene expression.
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Affiliation(s)
- Laura J Cluberton
- Centre for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria, Australia
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38
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Golfman LS, Wilson CR, Sharma S, Burgmaier M, Young ME, Guthrie PH, Van Arsdall M, Adrogue JV, Brown KK, Taegtmeyer H. Activation of PPARgamma enhances myocardial glucose oxidation and improves contractile function in isolated working hearts of ZDF rats. Am J Physiol Endocrinol Metab 2005; 289:E328-36. [PMID: 15797988 DOI: 10.1152/ajpendo.00055.2005] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
It is suggested that insulin resistance and metabolic maladaptation of the heart are causes of contractile dysfunction. We tested the hypothesis whether systemic PPARgamma activation, by changing the metabolic profile in a model of insulin resistance and type 2 diabetes (the ZDF rat) in vivo, improves contractile function of the heart in vitro. Male Zucker diabetic fatty (ZDF) and Zucker lean (ZL) rats, at 53-56 days of age, were treated with either GI-262570 (a nonthiazolidinedione PPARgamma agonist; A) or vehicle (V) for 1 wk. Agonist treatment resulted in correction of hyperglycemia and dyslipidemia, as well as in reduced hyperinsulinemia. The accumulation of triacylglycerols in the myocardium, characteristic of the ZDF rat, disappeared with treatment. Cardiac power and rates of glucose oxidation in the isolated working heart were significantly reduced in ZDF-V rats, but both parameters increased to nondiabetic levels with agonist treatment. In ZDF-V hearts, transcript levels of PPARalpha-regulated genes and of myosin heavy chain-beta were upregulated, whereas GLUT4 was downregulated compared with ZL. Agonist treatment of ZDF rats reduced PPARalpha-regulated genes and increased transcripts of GLUT4 and GLUT1. In conclusion, by changing the metabolic profile, reducing myocardial lipid accumulation, and promoting the downregulation of PPARalpha-regulated genes, PPARgamma activation leads to an increased capacity of the myocardium to oxidize glucose and to a tighter coupling of oxidative metabolism and contraction in the setting of insulin resistance and type 2 diabetes.
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Affiliation(s)
- Leonard S Golfman
- Dept. of Internal Medicine, Division of Cardiology, Univ. of Texas Medical School at Houston, 6431 Fannin, MSB 1.246, Houston, TX 77030, USA
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39
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Pilegaard H, Osada T, Andersen LT, Helge JW, Saltin B, Neufer PD. Substrate availability and transcriptional regulation of metabolic genes in human skeletal muscle during recovery from exercise. Metabolism 2005; 54:1048-55. [PMID: 16092055 DOI: 10.1016/j.metabol.2005.03.008] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In skeletal muscle of humans, transcription of several metabolic genes is transiently induced during recovery from exercise when no food is consumed. To determine the potential influence of substrate availability on the transcriptional regulation of metabolic genes during recovery from exercise, 9 male subjects (aged 22-27) completed 75 minutes of cycling exercise at 75% Vo2 max on 2 occasions, consuming either a high-carbohydrate (HC) or low-carbohydrate (LC) diet during the subsequent 24 hours of recovery. Nuclei were isolated and tissue frozen from vastus lateralis muscle biopsies obtained before exercise and 2, 5, 8, and 24 hours after exercise. Muscle glycogen was restored to near resting levels within 5 hours in the HC trial, but remained depressed through 24 hours in the LC trial. During the 2- to 8-hour recovery period, leg glucose uptake was 5- to 15-fold higher with HC ingestion, whereas arterial plasma free fatty acid levels were approximately 3- to 7-fold higher with LC ingestion. Exercise increased (P < .05) transcription and/or mRNA content of the pyruvate dehydrogenase kinase 4, uncoupling protein 3, lipoprotein lipase, carnitine palmitoyltransferase I, hexokinase II, peroxisome proliferator activated receptor gamma coactivator-1 alpha, and peroxisome proliferator activated receptor alpha. Providing HC during recovery reversed the activation of pyruvate dehydrogenase kinase 4, uncoupling protein 3, lipoprotein lipase, and carnitine palmitoyltransferase I within 5 to 8 hours after exercise, whereas providing LC during recovery elicited a sustained/enhanced increase in activation of these genes through 8 to 24 hours of recovery. These findings provide evidence that factors associated with substrate availability and/or cellular metabolic recovery (eg, muscle glycogen restoration) influence the transcriptional regulation of metabolic genes in skeletal muscle of humans during recovery from exercise.
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Affiliation(s)
- Henriette Pilegaard
- Copenhagen Muscle Research Centre, University of Copenhagen, Copenhagen, Denmark
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40
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Turvey EA, Heigenhauser GJF, Parolin M, Peters SJ. Elevated n-3 fatty acids in a high-fat diet attenuate the increase in PDH kinase activity but not PDH activity in human skeletal muscle. J Appl Physiol (1985) 2005; 98:350-5. [PMID: 15591305 DOI: 10.1152/japplphysiol.00604.2004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We tested the hypothesis that a high-fat diet (75% fat; 5% carbohydrates; 20% protein), for which 15% of the fat content was substituted with n-3 fatty acids, would not exhibit the diet-induced increase in pyruvate dehydrogenase kinase (PDK) activity, which is normally observed in human skeletal muscle. The fat content was the same in both the regular high-fat diet (HF) and in the n-3-substituted diet (N3). PDK activity increased after both high-fat diets, but the increase was attenuated after the N3 diet (0.051 +/- 0.007 and 0.218 +/- 0.047 min(-1) for pre- and post-HF, respectively; vs. 0.073 +/- 0.016 and 0.133 +/- 0.032 min(-1) for pre- and post-N3, respectively). However, the active form of pyruvate dehydrogenase (PDHa) activity decreased to a similar extent in both conditions (0.93 +/- 0.17 and 0.43 +/- 0.09 mmol/kg wet wt pre- and post-HF; vs. 0.87 +/- 0.19 and 0.39 +/- 0.05 mmol/kg wet wt pre- and post-N3, respectively). This suggested that the difference in PDK activity did not affect PDHa activation in the basal state, and it was regulated by intramitochondrial effectors, primarily muscle pyruvate concentration. Muscle glycogen content was consistent throughout the study, before and after both diet conditions, whereas muscle glucose-6-phosphate, glycerol-3-phosphate, lactate, and pyruvate were decreased after the high-fat diets. Plasma triglycerides decreased after both high-fat diets but decreased to a greater extent after the N3, whereas plasma free fatty acids increased after both diets, but to a lesser extent after the N3. In summary, PDK activity is decreased after a high-fat diet that is rich in n-3 fatty acids, although PDHa activity was unaltered. In addition, our data demonstrated that the hypolipidemic effect of n-3 fatty acids occurs earlier (3 days) than previously reported and is evident even when the diet has 75% of its total energy derived from fat.
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Affiliation(s)
- Erin A Turvey
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada N1G 2W1
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