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Phielix E, Szendroedi J, Roden M. Mitochondrial function and insulin resistance during aging: a mini-review. Gerontology 2010; 57:387-96. [PMID: 20798481 DOI: 10.1159/000317691] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Accepted: 06/22/2010] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Insulin resistance, i.e. impaired insulin sensitivity, and type 2 diabetes are more prevalent in elderly humans. Both conditions relate to lower aerobic performance and increased body fatness, which have been linked to reduced mitochondrial oxidative capacity. Thus, lower insulin sensitivity in the elderly could result from age-related diminished energy metabolism or from lifestyle-related abnormalities. OBJECTIVE This review addresses the question whether insulin sensitivity and mitochondrial oxidative capacity are independently affected during aging and type 2 diabetes. METHODS Only studies were analyzed which included elderly persons and employed state-of-the-art methodology to assess insulin sensitivity and oxidative capacity, e.g. electron microscopic imaging, in vivo magnetic resonance spectroscopy or ex vivo high-resolution respirometry. RESULTS Humans with or at risk of type 2 diabetes frequently exhibit insulin resistance along with structural and functional abnormalities of muscular mitochondria. Low mitochondrial oxidative capacity causes muscular fat accumulation, which impedes insulin signaling via lipid intermediates, in turn affecting oxidative capacity. However, insulin sensitivity is not generally reduced with age, when groups are carefully matched for physical activity and body fatness. Moreover, lifestyle intervention studies revealed discordant responses of mitochondrial oxidative capacity and insulin sensitivity. CONCLUSIONS In the elderly, low mitochondrial oxidative capacity likely results from age-related effects acquired during life span. Insulin resistance occurs independently of age mostly due to unhealthy lifestyle on top of genetic predisposition. Thus, insulin sensitivity and mitochondrial function may not be causally related, but mutually amplify each other during aging.
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Affiliation(s)
- Esther Phielix
- Institute for Clinical Diabetology, German Diabetes Center, Düsseldorf, Germany
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252
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Antoun E, Momken I, Bergouignan A, Villars C, Platat C, Schoeller DA, Blanc S, Simon C. The [1-13C]acetate recovery factor to correct tracer-derived dietary fat oxidation is lower in overweight insulin-resistant subjects. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/j.eclnm.2010.05.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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253
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Samocha-Bonet D, Campbell LV, Viardot A, Freund J, Tam CS, Greenfield JR, Heilbronn LK. A family history of type 2 diabetes increases risk factors associated with overfeeding. Diabetologia 2010; 53:1700-8. [PMID: 20461357 DOI: 10.1007/s00125-010-1768-y] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Accepted: 03/30/2010] [Indexed: 10/19/2022]
Abstract
AIMS/HYPOTHESIS The purpose of the study was to test prospectively whether healthy individuals with a family history of type 2 diabetes are more susceptible to adverse metabolic effects during experimental overfeeding. METHODS We studied the effects of 3 and 28 days of overfeeding by 5,200 kJ/day in 41 sedentary individuals with and without a family history of type 2 diabetes (FH+ and FH- respectively). Measures included body weight, fat distribution (computed tomography) and insulin sensitivity (hyperinsulinaemic-euglycaemic clamp). RESULTS Body weight was increased compared with baseline at 3 and 28 days in both groups (p < 0.001), FH+ individuals having gained significantly more weight than FH- individuals at 28 days (3.4 +/- 1.6 vs 2.2 +/- 1.4 kg, p < 0.05). Fasting serum insulin and C-peptide were increased at 3 and 28 days compared with baseline in both groups, with greater increases in FH+ than in FH- for insulin at +3 and +28 days (p < 0.01) and C-peptide at +28 days (p < 0.05). Fasting glucose also increased at both time points, but without a significant group effect (p = 0.1). Peripheral insulin sensitivity decreased in the whole cohort at +28 days (54.8 +/- 17.7 to 50.3 +/- 15.6 micromol min(-1) [kg fat-free mass](-1), p = 0.03), and insulin sensitivity by HOMA-IR decreased at both time points (p < 0.001) and to a greater extent in FH+ than in FH- (p = 0.008). Liver fat, subcutaneous and visceral fat increased similarly in the two groups (p < 0.001). CONCLUSIONS Overfeeding induced weight and fat gain, insulin resistance and hepatic fat deposition in healthy individuals. However, individuals with a family history of type 2 diabetes gained more weight and greater insulin resistance by HOMA-IR. The results of this study suggest that healthy individuals with a family history of type 2 diabetes are predisposed to adverse effects of overfeeding. TRIAL REGISTRATION ClinicalTrials.gov NCT00562393 FUNDING The study was funded by the National Health and Medical Research Council (NHMRC), Australia (no. #427639).
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Affiliation(s)
- D Samocha-Bonet
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia
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254
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Isomaa B, Forsén B, Lahti K, Holmström N, Wadén J, Matintupa O, Almgren P, Eriksson JG, Lyssenko V, Taskinen MR, Tuomi T, Groop LC. A family history of diabetes is associated with reduced physical fitness in the Prevalence, Prediction and Prevention of Diabetes (PPP)-Botnia study. Diabetologia 2010; 53:1709-13. [PMID: 20454776 DOI: 10.1007/s00125-010-1776-y] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Accepted: 03/09/2010] [Indexed: 10/19/2022]
Abstract
AIMS/HYPOTHESIS We studied the impact of a family history of type 2 diabetes on physical fitness, lifestyle factors and diabetes-related metabolic factors. METHODS The Prevalence, Prediction and Prevention of Diabetes (PPP)-Botnia study is a population-based study in Western Finland, which includes a random sample of 5,208 individuals aged 18 to 75 years identified through the national Finnish Population Registry. Physical activity, dietary habits and family history of type 2 diabetes were assessed by questionnaires and physical fitness by a validated 2 km walking test. Insulin secretion and action were assessed based upon OGTT measurements of insulin and glucose. RESULTS A family history of type 2 diabetes was associated with a 2.4-fold risk of diabetes and lower physical fitness (maximal aerobic capacity 29.2 +/- 7.2 vs 32.1 +/- 7.0, p = 0.01) despite having similar reported physical activity to that of individuals with no family history. The same individuals also had reduced insulin secretion adjusted for insulin resistance, i.e. disposition index (p < 0.001) despite having higher BMI (27.4 +/- 4.6 vs 26.0 +/- 4.3 kg/m(2), p < 0.001). CONCLUSIONS/INTERPRETATION Individuals with a family history of type 2 diabetes are characterised by lower physical fitness, which cannot solely be explained by lower physical activity. They also have an impaired capacity of beta cells to compensate for an increase in insulin resistance imposed by an increase in BMI. These defects should be important targets for interventions aiming at preventing type 2 diabetes in individuals with inherited susceptibility to the disease.
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Affiliation(s)
- B Isomaa
- Folkhälsan Genetic Institute, Helsinki, Finland.
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255
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Hyperglycemia-induced mitochondrial alterations in liver. Life Sci 2010; 87:197-214. [DOI: 10.1016/j.lfs.2010.06.007] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 05/21/2010] [Accepted: 06/05/2010] [Indexed: 01/07/2023]
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256
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Navarro JA, Ohmann E, Sanchez D, Botella JA, Liebisch G, Moltó MD, Ganfornina MD, Schmitz G, Schneuwly S. Altered lipid metabolism in a Drosophila model of Friedreich's ataxia. Hum Mol Genet 2010; 19:2828-40. [PMID: 20460268 PMCID: PMC7108586 DOI: 10.1093/hmg/ddq183] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Revised: 04/08/2010] [Accepted: 05/01/2010] [Indexed: 12/21/2022] Open
Abstract
Friedreich's ataxia (FRDA) is the most common form of autosomal recessive ataxia caused by a deficit in the mitochondrial protein frataxin. Although demyelination is a common symptom in FRDA patients, no multicellular model has yet been developed to study the involvement of glial cells in FRDA. Using the recently established RNAi lines for targeted suppression of frataxin in Drosophila, we were able to study the effects of general versus glial-specific frataxin downregulation. In particular, we wanted to study the interplay between lowered frataxin content, lipid accumulation and peroxidation and the consequences of these effects on the sensitivity to oxidative stress and fly fitness. Interestingly, ubiquitous frataxin reduction leads to an increase in fatty acids catalyzing an enhancement of lipid peroxidation levels, elevating the intracellular toxic potential. Specific loss of frataxin in glial cells triggers a similar phenotype which can be visualized by accumulating lipid droplets in glial cells. This phenotype is associated with a reduced lifespan, an increased sensitivity to oxidative insult, neurodegenerative effects and a serious impairment of locomotor activity. These symptoms fit very well with our observation of an increase in intracellular toxicity by lipid peroxides. Interestingly, co-expression of a Drosophila apolipoprotein D ortholog (glial lazarillo) has a strong protective effect in our frataxin models, mainly by controlling the level of lipid peroxidation. Our results clearly support a strong involvement of glial cells and lipid peroxidation in the generation of FRDA-like symptoms.
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Affiliation(s)
- Juan A. Navarro
- Institute of Zoology, Universitaetsstrasse 31, University of Regensburg, 93040 Regensburg, Germany
| | - Elisabeth Ohmann
- Institute of Zoology, Universitaetsstrasse 31, University of Regensburg, 93040 Regensburg, Germany
| | - Diego Sanchez
- Departamento de Bioquímica y Biología Molecular y Fisiología, Instituto de Biología y Genética Molecular, C/Sanz y Forés s/n, Universidad de Valladolid-CSIC, 47003 Valladolid, Spain
| | - José A. Botella
- Institute of Zoology, Universitaetsstrasse 31, University of Regensburg, 93040 Regensburg, Germany
| | - Gerhard Liebisch
- Institute for Clinical Chemistry and Laboratory Medicine, University of Regensburg, Franz-Josef-Strauß-Allee 11, 93053 Regensburg, Germany and
| | - María D. Moltó
- Department of Genetics, Universidad de Valencia, CIBERSAM, 46100 Burjassot, Valencia, Spain
| | - María D. Ganfornina
- Departamento de Bioquímica y Biología Molecular y Fisiología, Instituto de Biología y Genética Molecular, C/Sanz y Forés s/n, Universidad de Valladolid-CSIC, 47003 Valladolid, Spain
| | - Gerd Schmitz
- Institute for Clinical Chemistry and Laboratory Medicine, University of Regensburg, Franz-Josef-Strauß-Allee 11, 93053 Regensburg, Germany and
| | - Stephan Schneuwly
- Institute of Zoology, Universitaetsstrasse 31, University of Regensburg, 93040 Regensburg, Germany
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257
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Pazderska A, Wanic K, Nolan JJ. Skeletal muscle mitochondrial dysfunction in Type 2 diabetes. Expert Rev Endocrinol Metab 2010; 5:475-477. [PMID: 30780805 DOI: 10.1586/eem.10.21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Agnieszka Pazderska
- a Metabolic Research Unit, Department of Endocrinology, St James Hospital, Trinity College, Dublin 8, Ireland
| | - Krzysztof Wanic
- a Metabolic Research Unit, Department of Endocrinology, St James Hospital, Trinity College, Dublin 8, Ireland
| | - John J Nolan
- b Metabolic Research Unit, Department of Endocrinology, St James Hospital, Trinity College, Dublin 8, Ireland.
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258
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Adam T, Opie LH, Essop MF. AMPK activation represses the human gene promoter of the cardiac isoform of acetyl-CoA carboxylase: Role of nuclear respiratory factor-1. Biochem Biophys Res Commun 2010; 398:495-9. [PMID: 20599696 DOI: 10.1016/j.bbrc.2010.06.106] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Accepted: 06/28/2010] [Indexed: 01/10/2023]
Abstract
The cardiac-enriched isoform of acetyl-CoA carboxylase (ACCbeta) produces malonyl-CoA, a potent inhibitor of carnitine palmitoyltransferase-1. AMPK inhibits ACCbeta activity, lowering malonyl-CoA levels and promoting mitochondrial fatty acid beta-oxidation. Previously, AMPK increased promoter binding of nuclear respiratory factor-1 (NRF-1), a pivotal transcriptional modulator controlling gene expression of mitochondrial proteins. We therefore hypothesized that NRF-1 inhibits myocardial ACCbeta promoter activity via AMPK activation. A human ACCbeta promoter-luciferase construct was transiently transfected into neonatal cardiomyocytes+/-a NRF-1 expression construct. NRF-1 overexpression decreased ACCbeta gene promoter activity by 71+/-4.6% (p<0.001 vs. control). Transfections with 5'-end serial promoter deletions revealed that NRF-1-mediated repression of ACCbeta was abolished with a pPIIbeta-18/+65-Luc deletion construct. AMPK activation dose-dependently reduced ACCbeta promoter activity, while NRF-1 addition did not further decrease it. We also investigated NRF-1 inhibition in the presence of upstream stimulatory factor 1 (USF1), a known transactivator of the human ACCbeta gene promoter. Here NRF-1 blunted USF1-dependent induction of ACCbeta promoter activity by 58+/-7.5% (p<0.001 vs. control), reversed with a dominant negative NRF-1 construct. NRF-1 also suppressed endogenous USF1 transcriptional activity by 55+/-6.2% (p<0.001 vs. control). This study demonstrates that NRF-1 is a novel transcriptional inhibitor of the human ACCbeta gene promoter in the mammalian heart. Our data extends AMPK regulation of ACCbeta to the transcriptional level.
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Affiliation(s)
- Tasneem Adam
- Hatter Cardiovascular Research Institute, Faculty of Health Sciences, University of Cape Town, Observatory 7925, South Africa
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259
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Abstract
Insulin resistance has long been associated with obesity. More than 40 years ago, Randle and colleagues postulated that lipids impaired insulin-stimulated glucose use by muscles through inhibition of glycolysis at key points. However, work over the past two decades has shown that lipid-induced insulin resistance in skeletal muscle stems from defects in insulin-stimulated glucose transport activity. The steatotic liver is also resistant to insulin in terms of inhibition of hepatic glucose production and stimulation of glycogen synthesis. In muscle and liver, the intracellular accumulation of lipids-namely, diacylglycerol-triggers activation of novel protein kinases C with subsequent impairments in insulin signalling. This unifying hypothesis accounts for the mechanism of insulin resistance in obesity, type 2 diabetes, lipodystrophy, and ageing; and the insulin-sensitising effects of thiazolidinediones.
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Affiliation(s)
- Varman T Samuel
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06536-8012, USA
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260
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Normand-Lauzière F, Frisch F, Labbé SM, Bherer P, Gagnon R, Cunnane SC, Carpentier AC. Increased postprandial nonesterified fatty acid appearance and oxidation in type 2 diabetes is not fully established in offspring of diabetic subjects. PLoS One 2010; 5:e10956. [PMID: 20532041 PMCID: PMC2881041 DOI: 10.1371/journal.pone.0010956] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Accepted: 05/07/2010] [Indexed: 12/15/2022] Open
Abstract
Background It has been proposed that abnormal postprandial plasma nonesterified fatty acid (NEFA) metabolism may participate in the development of tissue lipotoxicity and type 2 diabetes (T2D). We previously found that non-diabetic offspring of two parents with T2D display increased plasma NEFA appearance and oxidation rates during intravenous administration of a fat emulsion. However, it is currently unknown whether plasma NEFA appearance and oxidation are abnormal during the postprandial state in these subjects at high-risk of developing T2D. Methodology Palmitate appearance and oxidation rates and glycerol appearance rate were determined in eleven healthy offspring of two parents with T2D (positive family history, FH+), 13 healthy subjects without first-degree relatives with T2D (FH-) and 12 subjects with T2D at fasting, during normoglycemic hyperinsulinemic clamp and during continuous oral intake of a standard liquid meal to achieve steady postprandial NEFA and triacylglycerols (TG) without and with insulin infusion to maintain similar glycemia in all three groups. Principal Findings Plasma palmitate appearance and oxidation were higher at fasting and during the clamp conditions in the T2D group (all P<0.05). In the postprandial state, palmitate appearance, oxidative and non oxidative rates were all elevated in T2D (all P<0.05) but not in FH+. Both T2D and FH+ displayed elevated postprandial TG vs. FH- (P<0.001). Acute correction of hyperglycemia during the postprandial state did not affect these group differences. Increased waist circumference and BMI were positively associated with elevated postprandial plasma palmitate appearance and oxidation. Conclusions/Significance Postprandial plasma NEFA intolerance observed in subjects with T2D is not fully established in non-diabetic offspring of both parents with T2D, despite the presence of increased postprandial plasma TG in the later. Elevated postprandial plasma NEFA appearance and oxidation in T2D is observed despite acute correction of the exaggerated glycemic excursion in this group.
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Affiliation(s)
- François Normand-Lauzière
- Division of Endocrinology, Department of Medicine, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Frédérique Frisch
- Division of Endocrinology, Department of Medicine, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Sébastien M. Labbé
- Division of Endocrinology, Department of Medicine, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Patrick Bherer
- Division of Endocrinology, Department of Medicine, Université de Sherbrooke, Sherbrooke, Québec, Canada
- Division of Genetics, Department of Pediatrics, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - René Gagnon
- Division of Genetics, Department of Pediatrics, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | | | - André C. Carpentier
- Division of Endocrinology, Department of Medicine, Université de Sherbrooke, Sherbrooke, Québec, Canada
- * E-mail:
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261
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Lenaers E, De Feyter HM, Hoeks J, Schrauwen P, Schaart G, Nabben M, Nicolay K, Prompers JJ, Hesselink MKC. Adaptations in mitochondrial function parallel, but fail to rescue, the transition to severe hyperglycemia and hyperinsulinemia: a study in Zucker diabetic fatty rats. Obesity (Silver Spring) 2010; 18:1100-7. [PMID: 19875988 DOI: 10.1038/oby.2009.372] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Cross-sectional human studies have associated mitochondrial dysfunction to type 2 diabetes. We chose Zucker diabetic fatty (ZDF) rats as a model of progressive insulin resistance to examine whether intrinsic mitochondrial defects are required for development of type 2 diabetes. Muscle mitochondrial function was examined in 6-, 12-, and 19-week-old ZDF (fa/fa) and fa/+ control rats (n = 8-10 per group) using respirometry with pyruvate, glutamate, and palmitoyl-CoA as substrates. Six-week-old normoglycemic-hyperinsulinemic fa/fa rats had reduced mitochondrial fat oxidative capacity. Adenosine diphosphate (ADP)-driven state 3 and carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP)-stimulated state uncoupled (state u) respiration on palmitoyl-CoA were lower compared to controls (62.3 +/- 9.5 vs. 119.1 +/- 13.8 and 87.8 +/- 13.3 vs. 141.9 +/- 14.3 nmol O(2)/mg/min.). Pyruvate oxidation in 6-week-old fa/fa rats was similar to controls. Remarkably, reduced fat oxidative capacity in 6-week-old fa/fa rats was compensated for by an adaptive increase in intrinsic mitochondrial function at week 12, which could not be maintained toward week 19 (140.9 +/- 11.2 and 57.7 +/- 9.8 nmol O(2)/mg/min, weeks 12 and 19, respectively), whereas hyperglycemia had developed (13.5 +/- 0.6 and 16.1 +/- 0.3 mmol/l, weeks 12 and 19, respectively). This mitochondrial adaptation failed to rescue the progressive development of insulin resistance in fa/fa rats. The transition of prediabetes state toward advanced hyperglycemia and hyperinsulinemia was accompanied by a blunted increase in uncoupling protein-3 (UCP3). Thus, in ZDF rats insulin resistance develops progressively in the absence of mitochondrial dysfunction. In fact, improved mitochondrial capacity in hyperinsulinemic hyperglycemic rats does not rescue the progression toward advanced stages of insulin resistance.
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MESH Headings
- Adaptation, Physiological/physiology
- Adenine Nucleotide Translocator 1/metabolism
- Animals
- Diabetes Mellitus, Experimental/complications
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Experimental/pathology
- Diabetes Mellitus, Experimental/physiopathology
- Hyperglycemia/complications
- Hyperglycemia/metabolism
- Hyperglycemia/physiopathology
- Hyperinsulinism/complications
- Hyperinsulinism/metabolism
- Hyperinsulinism/physiopathology
- Ion Channels/metabolism
- Male
- Mitochondria, Muscle/metabolism
- Mitochondria, Muscle/pathology
- Mitochondria, Muscle/physiology
- Mitochondrial Proteins/metabolism
- Muscle Fibers, Skeletal/metabolism
- Muscle Fibers, Skeletal/pathology
- Obesity/complications
- Obesity/metabolism
- Obesity/pathology
- Obesity/physiopathology
- Oxidation-Reduction
- Oxygen Consumption/physiology
- Protein Carbonylation/physiology
- Rats
- Rats, Zucker
- Severity of Illness Index
- Uncoupling Protein 3
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Affiliation(s)
- Ellen Lenaers
- NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, The Netherlands
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262
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Wei JN, Li HY, Wang YC, Chuang LM, Lin MS, Lin CH, Sung FC. Detailed family history of diabetes identified children at risk of type 2 diabetes: a population-based case-control study. Pediatr Diabetes 2010; 11:258-64. [PMID: 19708906 DOI: 10.1111/j.1399-5448.2009.00564.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
OBJECTIVES Recently, the incidence of type 2 diabetes (T2D) in children has increased dramatically. Mass screening is suffering and costly. It remains unknown if a detailed family diabetes mellitus history (FDMH) can identify children with different risks of T2D. This study investigated how FDMH was associated with childhood T2D. METHODS From 1992 to 1997, a nationwide survey conducted in Taiwan for all 3 000 000 school children aged between 6 and 18 yr identified 1966 children with diabetes. For comparison, 1780 children were randomly selected as the control group from all students with normal fasting glycemia (NFG). Telephonic Interviews were conducted using questionnaire for detailed FDMH. In the present analysis, 505 children with T2D and 619 children with NFG were enrolled. RESULTS Children with more family members having diabetes were more likely to have T2D. Children with the parental FDMH had a higher risk for T2D than children with the grandparental FDMH; the odds ratios (ORs) were 2.61 (95% confidence interval (CI) 1.25-5.48, p < 0.05) for boys and 6.47 (95% CI 2.69-15.6, p < 0.05) for girls, adjusting for age, birth weight, gestational age and body mass index (BMI) z-score. Children with maternal FDMH had a higher risk for T2D than children with paternal FDMH, and much greater in boys (OR = 29.5, 95% CI 3.67-237, p < 0.05) than in girls (OR = 7.63, 95% CI 2.05-28.4, p < 0.05), adjusted for age, birth weight, gestational age, BMI z-score, and FDMH in grandparents. CONCLUSIONS Children with parental FDMH, especially the maternal FDMH, have an elevated risk for T2D. Detailed FDMH is a convenient alternative to identify children with different risks of T2D.
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Affiliation(s)
- Jung-Nan Wei
- Chia Nan University of Pharmacy and Science, Tainan 717, Taiwan
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263
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Aguer C, Mercier J, Man CYW, Metz L, Bordenave S, Lambert K, Jean E, Lantier L, Bounoua L, Brun JF, Raynaud de Mauverger E, Andreelli F, Foretz M, Kitzmann M. Intramyocellular lipid accumulation is associated with permanent relocation ex vivo and in vitro of fatty acid translocase (FAT)/CD36 in obese patients. Diabetologia 2010; 53:1151-63. [PMID: 20333349 DOI: 10.1007/s00125-010-1708-x] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2009] [Accepted: 01/27/2010] [Indexed: 02/06/2023]
Abstract
AIMS/HYPOTHESIS Intramyocellular lipids (IMCL) accumulation is a classical feature of metabolic diseases. We hypothesised that IMCL accumulate mainly as a consequence of increased adiposity and independently of type 2 diabetes. To test this, we examined IMCL accumulation in two different models and four different populations of participants: muscle biopsies and primary human muscle cells derived from non-obese and obese participants with or without type 2 diabetes. The mechanism regulating IMCL accumulation was also studied. METHODS Muscle biopsies were obtained from ten non-obese and seven obese participants without type 2 diabetes, and from eight non-obese and eight obese type 2 diabetic patients. Mitochondrial respiration, citrate synthase activity and both AMP-activated protein kinase and acetyl-CoA carboxylase phosphorylation were measured in muscle tissue. Lipid accumulation in muscle and primary myotubes was estimated by Oil Red O staining and fatty acid translocase (FAT)/CD36 localisation by immunofluorescence. RESULTS Obesity and type 2 diabetes are independently characterised by skeletal muscle IMCL accumulation and permanent FAT/CD36 relocation. Mitochondrial function is not reduced in type 2 diabetes. IMCL accumulation was independent of type 2 diabetes in cultured myotubes and was correlated with obesity markers of the donor. In obese participants, membrane relocation of FAT/CD36 is a determinant of IMCL accumulation. CONCLUSIONS/INTERPRETATION In skeletal muscle, mitochondrial function is normal in type 2 diabetes, while IMCL accumulation is dependent upon obesity or type 2 diabetes and is related to sarcolemmal FAT/CD36 relocation. In cultured myotubes, IMCL content and FAT/CD36 relocation are independent of type 2 diabetes, suggesting that distinct factors in obesity and type 2 diabetes contribute to permanent FAT/CD36 relocation ex vivo.
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Affiliation(s)
- C Aguer
- INSERM, ERI25 Muscle et pathologies, Hôpital A. de Villeneuve, Bâtiment Crastes de Paulet, Avenue du Doyen G. Giraud, Montpellier F-34295, France
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264
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Abstract
The pathophysiology of type 2 diabetes mellitus (DM) is varied and complex. However, the association of DM with obesity and inactivity indicates an important, and potentially pathogenic, link between fuel and energy homeostasis and the emergence of metabolic disease. Given the central role for mitochondria in fuel utilization and energy production, disordered mitochondrial function at the cellular level can impact whole-body metabolic homeostasis. Thus, the hypothesis that defective or insufficient mitochondrial function might play a potentially pathogenic role in mediating risk of type 2 DM has emerged in recent years. Here, we summarize current literature on risk factors for diabetes pathogenesis, on the specific role(s) of mitochondria in tissues involved in its pathophysiology, and on evidence pointing to alterations in mitochondrial function in these tissues that could contribute to the development of DM. We also review literature on metabolic phenotypes of existing animal models of impaired mitochondrial function. We conclude that, whereas the association between impaired mitochondrial function and DM is strong, a causal pathogenic relationship remains uncertain. However, we hypothesize that genetically determined and/or inactivity-mediated alterations in mitochondrial oxidative activity may directly impact adaptive responses to overnutrition, causing an imbalance between oxidative activity and nutrient load. This imbalance may lead in turn to chronic accumulation of lipid oxidative metabolites that can mediate insulin resistance and secretory dysfunction. More refined experimental strategies that accurately mimic potential reductions in mitochondrial functional capacity in humans at risk for diabetes will be required to determine the potential pathogenic role in human insulin resistance and type 2 DM.
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265
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Regulation of skeletal muscle oxidative capacity and insulin signaling by the mitochondrial rhomboid protease PARL. Cell Metab 2010; 11:412-26. [PMID: 20444421 PMCID: PMC3835349 DOI: 10.1016/j.cmet.2010.04.004] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Revised: 06/15/2009] [Accepted: 04/07/2010] [Indexed: 12/25/2022]
Abstract
Type 2 diabetes mellitus (T2DM) and aging are characterized by insulin resistance and impaired mitochondrial energetics. In lower organisms, remodeling by the protease pcp1 (PARL ortholog) maintains the function and lifecycle of mitochondria. We examined whether variation in PARL protein content is associated with mitochondrial abnormalities and insulin resistance. PARL mRNA and mitochondrial mass were both reduced in elderly subjects and in subjects with T2DM. Muscle knockdown of PARL in mice resulted in malformed mitochondrial cristae, lower mitochondrial content, decreased PGC1alpha protein levels, and impaired insulin signaling. Suppression of PARL protein in healthy myotubes lowered mitochondrial mass and insulin-stimulated glycogen synthesis and increased reactive oxygen species production. We propose that lower PARL expression may contribute to the mitochondrial abnormalities seen in aging and T2DM.
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266
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Pathogenesis of insulin resistance in skeletal muscle. J Biomed Biotechnol 2010; 2010:476279. [PMID: 20445742 PMCID: PMC2860140 DOI: 10.1155/2010/476279] [Citation(s) in RCA: 378] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 01/20/2010] [Indexed: 12/16/2022] Open
Abstract
Insulin resistance in skeletal muscle is manifested by decreased insulin-stimulated glucose uptake and results from impaired insulin signaling and multiple post-receptor intracellular defects including impaired glucose transport, glucose phosphorylation, and reduced glucose oxidation and glycogen synthesis. Insulin resistance is a core defect in type 2 diabetes, it is also associated with obesity and the metabolic syndrome. Dysregulation of fatty acid metabolism plays a pivotal role in the pathogenesis of insulin resistance in skeletal muscle. Recent studies have reported a mitochondrial defect in oxidative phosphorylation in skeletal muscle in variety of insulin resistant states. In this review, we summarize the cellular and molecular defects that contribute to the development of insulin resistance in skeletal muscle.
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267
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Abstract
Understanding the molecular mechanisms of insulin resistance remains a major medical challenge of the twenty-first century. Over the last half-century, many hypotheses have been proposed to explain insulin resistance, and, most recently, inflammation associated with alterations in adipocytokines has become the prevailing hypothesis. Here we discuss diacylglycerol-mediated insulin resistance as an alternative and unifying hypothesis to explain the most common forms of insulin resistance associated with obesity and type 2 diabetes mellitus, as well as lipodystrophy and aging.
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268
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Sivitz WI, Yorek MA. Mitochondrial dysfunction in diabetes: from molecular mechanisms to functional significance and therapeutic opportunities. Antioxid Redox Signal 2010; 12:537-77. [PMID: 19650713 PMCID: PMC2824521 DOI: 10.1089/ars.2009.2531] [Citation(s) in RCA: 507] [Impact Index Per Article: 36.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Given their essential function in aerobic metabolism, mitochondria are intuitively of interest in regard to the pathophysiology of diabetes. Qualitative, quantitative, and functional perturbations in mitochondria have been identified and affect the cause and complications of diabetes. Moreover, as a consequence of fuel oxidation, mitochondria generate considerable reactive oxygen species (ROS). Evidence is accumulating that these radicals per se are important in the pathophysiology of diabetes and its complications. In this review, we first present basic concepts underlying mitochondrial physiology. We then address mitochondrial function and ROS as related to diabetes. We consider different forms of diabetes and address both insulin secretion and insulin sensitivity. We also address the role of mitochondrial uncoupling and coenzyme Q. Finally, we address the potential for targeting mitochondria in the therapy of diabetes.
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Affiliation(s)
- William I Sivitz
- Department of Internal Medicine, Division of Endocrinology and Metabolism, Iowa City Veterans Affairs Medical Center and University of Iowa, Iowa City, Iowa, USA.
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269
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Mitchell CS, Savage DB, Dufour S, Schoenmakers N, Murgatroyd P, Befroy D, Halsall D, Northcott S, Raymond-Barker P, Curran S, Henning E, Keogh J, Owen P, Lazarus J, Rothman DL, Farooqi IS, Shulman GI, Chatterjee K, Petersen KF. Resistance to thyroid hormone is associated with raised energy expenditure, muscle mitochondrial uncoupling, and hyperphagia. J Clin Invest 2010; 120:1345-54. [PMID: 20237409 PMCID: PMC2846038 DOI: 10.1172/jci38793] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Accepted: 01/13/2010] [Indexed: 01/07/2023] Open
Abstract
Resistance to thyroid hormone (RTH), a dominantly inherited disorder usually associated with mutations in thyroid hormone receptor beta (THRB), is characterized by elevated levels of circulating thyroid hormones (including thyroxine), failure of feedback suppression of thyrotropin, and variable tissue refractoriness to thyroid hormone action. Raised energy expenditure and hyperphagia are recognized features of hyperthyroidism, but the effects of comparable hyperthyroxinemia in RTH patients are unknown. Here, we show that resting energy expenditure (REE) was substantially increased in adults and children with THRB mutations. Energy intake in RTH subjects was increased by 40%, with marked hyperphagia particularly evident in children. Rates of muscle TCA cycle flux were increased by 75% in adults with RTH, whereas rates of ATP synthesis were unchanged, as determined by 13C/31P magnetic resonance spectroscopy. Mitochondrial coupling index between ATP synthesis and mitochondrial rates of oxidation (as estimated by the ratio of ATP synthesis to TCA cycle flux) was significantly decreased in RTH patients. These data demonstrate that basal mitochondrial substrate oxidation is increased and energy production in the form of ATP synthesis is decreased in the muscle of RTH patients and that resting oxidative phosphorylation is uncoupled in this disorder. Furthermore, these observations suggest that mitochondrial uncoupling in skeletal muscle is a major contributor to increased REE in patients with RTH, due to tissue selective retention of thyroid hormone receptor alpha sensitivity to elevated thyroid hormone levels.
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Affiliation(s)
- Catherine S. Mitchell
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, United Kingdom.
Howard Hughes Medical Institute and
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
Department of Clinical Biochemistry, Addenbrooke’s Hospital.
Department of Medicine, University of Cardiff, United Kingdom.
Department of Diagnostic Radiology and
Department of Cellular and Molecular Physiology, Yale University School of Medicine
| | - David B. Savage
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, United Kingdom.
Howard Hughes Medical Institute and
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
Department of Clinical Biochemistry, Addenbrooke’s Hospital.
Department of Medicine, University of Cardiff, United Kingdom.
Department of Diagnostic Radiology and
Department of Cellular and Molecular Physiology, Yale University School of Medicine
| | - Sylvie Dufour
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, United Kingdom.
Howard Hughes Medical Institute and
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
Department of Clinical Biochemistry, Addenbrooke’s Hospital.
Department of Medicine, University of Cardiff, United Kingdom.
Department of Diagnostic Radiology and
Department of Cellular and Molecular Physiology, Yale University School of Medicine
| | - Nadia Schoenmakers
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, United Kingdom.
Howard Hughes Medical Institute and
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
Department of Clinical Biochemistry, Addenbrooke’s Hospital.
Department of Medicine, University of Cardiff, United Kingdom.
Department of Diagnostic Radiology and
Department of Cellular and Molecular Physiology, Yale University School of Medicine
| | - Peter Murgatroyd
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, United Kingdom.
Howard Hughes Medical Institute and
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
Department of Clinical Biochemistry, Addenbrooke’s Hospital.
Department of Medicine, University of Cardiff, United Kingdom.
Department of Diagnostic Radiology and
Department of Cellular and Molecular Physiology, Yale University School of Medicine
| | - Douglas Befroy
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, United Kingdom.
Howard Hughes Medical Institute and
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
Department of Clinical Biochemistry, Addenbrooke’s Hospital.
Department of Medicine, University of Cardiff, United Kingdom.
Department of Diagnostic Radiology and
Department of Cellular and Molecular Physiology, Yale University School of Medicine
| | - David Halsall
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, United Kingdom.
Howard Hughes Medical Institute and
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
Department of Clinical Biochemistry, Addenbrooke’s Hospital.
Department of Medicine, University of Cardiff, United Kingdom.
Department of Diagnostic Radiology and
Department of Cellular and Molecular Physiology, Yale University School of Medicine
| | - Samantha Northcott
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, United Kingdom.
Howard Hughes Medical Institute and
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
Department of Clinical Biochemistry, Addenbrooke’s Hospital.
Department of Medicine, University of Cardiff, United Kingdom.
Department of Diagnostic Radiology and
Department of Cellular and Molecular Physiology, Yale University School of Medicine
| | - Philippa Raymond-Barker
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, United Kingdom.
Howard Hughes Medical Institute and
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
Department of Clinical Biochemistry, Addenbrooke’s Hospital.
Department of Medicine, University of Cardiff, United Kingdom.
Department of Diagnostic Radiology and
Department of Cellular and Molecular Physiology, Yale University School of Medicine
| | - Suzanne Curran
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, United Kingdom.
Howard Hughes Medical Institute and
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
Department of Clinical Biochemistry, Addenbrooke’s Hospital.
Department of Medicine, University of Cardiff, United Kingdom.
Department of Diagnostic Radiology and
Department of Cellular and Molecular Physiology, Yale University School of Medicine
| | - Elana Henning
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, United Kingdom.
Howard Hughes Medical Institute and
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
Department of Clinical Biochemistry, Addenbrooke’s Hospital.
Department of Medicine, University of Cardiff, United Kingdom.
Department of Diagnostic Radiology and
Department of Cellular and Molecular Physiology, Yale University School of Medicine
| | - Julia Keogh
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, United Kingdom.
Howard Hughes Medical Institute and
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
Department of Clinical Biochemistry, Addenbrooke’s Hospital.
Department of Medicine, University of Cardiff, United Kingdom.
Department of Diagnostic Radiology and
Department of Cellular and Molecular Physiology, Yale University School of Medicine
| | - Penny Owen
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, United Kingdom.
Howard Hughes Medical Institute and
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
Department of Clinical Biochemistry, Addenbrooke’s Hospital.
Department of Medicine, University of Cardiff, United Kingdom.
Department of Diagnostic Radiology and
Department of Cellular and Molecular Physiology, Yale University School of Medicine
| | - John Lazarus
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, United Kingdom.
Howard Hughes Medical Institute and
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
Department of Clinical Biochemistry, Addenbrooke’s Hospital.
Department of Medicine, University of Cardiff, United Kingdom.
Department of Diagnostic Radiology and
Department of Cellular and Molecular Physiology, Yale University School of Medicine
| | - Douglas L. Rothman
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, United Kingdom.
Howard Hughes Medical Institute and
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
Department of Clinical Biochemistry, Addenbrooke’s Hospital.
Department of Medicine, University of Cardiff, United Kingdom.
Department of Diagnostic Radiology and
Department of Cellular and Molecular Physiology, Yale University School of Medicine
| | - I. Sadaf Farooqi
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, United Kingdom.
Howard Hughes Medical Institute and
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
Department of Clinical Biochemistry, Addenbrooke’s Hospital.
Department of Medicine, University of Cardiff, United Kingdom.
Department of Diagnostic Radiology and
Department of Cellular and Molecular Physiology, Yale University School of Medicine
| | - Gerald I. Shulman
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, United Kingdom.
Howard Hughes Medical Institute and
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
Department of Clinical Biochemistry, Addenbrooke’s Hospital.
Department of Medicine, University of Cardiff, United Kingdom.
Department of Diagnostic Radiology and
Department of Cellular and Molecular Physiology, Yale University School of Medicine
| | - Krishna Chatterjee
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, United Kingdom.
Howard Hughes Medical Institute and
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
Department of Clinical Biochemistry, Addenbrooke’s Hospital.
Department of Medicine, University of Cardiff, United Kingdom.
Department of Diagnostic Radiology and
Department of Cellular and Molecular Physiology, Yale University School of Medicine
| | - Kitt Falk Petersen
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, United Kingdom.
Howard Hughes Medical Institute and
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
Department of Clinical Biochemistry, Addenbrooke’s Hospital.
Department of Medicine, University of Cardiff, United Kingdom.
Department of Diagnostic Radiology and
Department of Cellular and Molecular Physiology, Yale University School of Medicine
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270
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Bruce KD, Hanson MA. The developmental origins, mechanisms, and implications of metabolic syndrome. J Nutr 2010; 140:648-52. [PMID: 20107145 DOI: 10.3945/jn.109.111179] [Citation(s) in RCA: 181] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Metabolic syndrome (MetS) represents a combination of cardio-metabolic risk determinants, including central obesity, insulin resistance, glucose intolerance, dyslipidemia, hypertension, hyperinsulinemia, and microalbuminuria. The prevalence of MetS is rapidly increasing worldwide, largely as a consequence of the ongoing obesity epidemic. Environmental factors during periods early in development have been shown to influence the susceptibility to develop disease in later life. In particular, there is a wealth of evidence from both epidemiological and animal studies for greater incidence of features of MetS as a result of unbalanced maternal nutrition. The mechanisms by which nutritional insults during a period of developmental plasticity result in a MetS phenotype are now beginning to receive considerable scientific interest. This review focuses on recent data regarding these mechanisms, in particular the epigenetic and transcriptional regulation of key metabolic genes in response to nutritional stimuli that mediate persistent changes and an adult MetS phenotype. A continued and greater understanding of these mechanisms will eventually allow specific interventions, with a favorable impact on the global incidence of cardiovascular disease and type 2 diabetes in the future.
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Affiliation(s)
- Kimberley D Bruce
- Developmental Origins of Health and Disease Division, Institute of Developmental Sciences, University of Southampton School of Medicine, Southampton General Hospital, Southampton, UK.
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271
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Meex RC, Schrauwen-Hinderling VB, Moonen-Kornips E, Schaart G, Mensink M, Phielix E, van de Weijer T, Sels JP, Schrauwen P, Hesselink MK. Restoration of muscle mitochondrial function and metabolic flexibility in type 2 diabetes by exercise training is paralleled by increased myocellular fat storage and improved insulin sensitivity. Diabetes 2010; 59:572-9. [PMID: 20028948 PMCID: PMC2828651 DOI: 10.2337/db09-1322] [Citation(s) in RCA: 235] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE Mitochondrial dysfunction and fat accumulation in skeletal muscle (increased intramyocellular lipid [IMCL]) have been linked to development of type 2 diabetes. We examined whether exercise training could restore mitochondrial function and insulin sensitivity in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS Eighteen male type 2 diabetic and 20 healthy male control subjects of comparable body weight, BMI, age, and VO2max participated in a 12-week combined progressive training program (three times per week and 45 min per session). In vivo mitochondrial function (assessed via magnetic resonance spectroscopy), insulin sensitivity (clamp), metabolic flexibility (indirect calorimetry), and IMCL content (histochemically) were measured before and after training. RESULTS Mitochondrial function was lower in type 2 diabetic compared with control subjects (P = 0.03), improved by training in control subjects (28% increase; P = 0.02), and restored to control values in type 2 diabetic subjects (48% increase; P < 0.01). Insulin sensitivity tended to improve in control subjects (delta Rd 8% increase; P = 0.08) and improved significantly in type 2 diabetic subjects (delta Rd 63% increase; P < 0.01). Suppression of insulin-stimulated endogenous glucose production improved in both groups (-64%; P < 0.01 in control subjects and -52% in diabetic subjects; P < 0.01). After training, metabolic flexibility in type 2 diabetic subjects was restored (delta respiratory exchange ratio 63% increase; P = 0.01) but was unchanged in control subjects (delta respiratory exchange ratio 7% increase; P = 0.22). Starting with comparable pretraining IMCL levels, training tended to increase IMCL content in type 2 diabetic subjects (27% increase; P = 0.10), especially in type 2 muscle fibers. CONCLUSIONS Exercise training restored in vivo mitochondrial function in type 2 diabetic subjects. Insulin-mediated glucose disposal and metabolic flexibility improved in type 2 diabetic subjects in the face of near-significantly increased IMCL content. This indicates that increased capacity to store IMCL and restoration of improved mitochondrial function contribute to improved muscle insulin sensitivity.
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Affiliation(s)
- Ruth C.R. Meex
- Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Vera B. Schrauwen-Hinderling
- Department of Human Biology, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, the Netherlands
- Department of Radiology, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Esther Moonen-Kornips
- Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, the Netherlands
- Department of Human Biology, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Gert Schaart
- Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Marco Mensink
- Human Nutrition, Wageningen University, the Netherlands
| | - Esther Phielix
- Department of Human Biology, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Tineke van de Weijer
- Department of Human Biology, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Jean-Pierre Sels
- Department of Internal Medicine, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Patrick Schrauwen
- Department of Human Biology, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Matthijs K.C. Hesselink
- Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, the Netherlands
- Corresponding author: Matthijs K.C. Hesselink,
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272
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Pagel-Langenickel I, Bao J, Pang L, Sack MN. The role of mitochondria in the pathophysiology of skeletal muscle insulin resistance. Endocr Rev 2010; 31:25-51. [PMID: 19861693 PMCID: PMC2852205 DOI: 10.1210/er.2009-0003] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Accepted: 08/27/2009] [Indexed: 12/18/2022]
Abstract
Multiple organs contribute to the development of peripheral insulin resistance, with the major contributors being skeletal muscle, liver, and adipose tissue. Because insulin resistance usually precedes the development of type 2 diabetes mellitus (T2DM) by many years, understanding the pathophysiology of insulin resistance should enable development of therapeutic strategies to prevent disease progression. Some subjects with mitochondrial genomic variants/defects and a subset of lean individuals with hereditary predisposition to T2DM exhibit skeletal muscle mitochondrial dysfunction early in the course of insulin resistance. In contrast, in the majority of subjects with T2DM the plurality of evidence implicates skeletal muscle mitochondrial dysfunction as a consequence of perturbations associated with T2DM, and these mitochondrial deficits then contribute to subsequent disease progression. We review the affirmative and contrarian data regarding skeletal muscle mitochondrial biology in the pathogenesis of insulin resistance and explore potential therapeutic options to intrinsically modulate mitochondria as a strategy to combat insulin resistance. Furthermore, an overview of restricted molecular manipulations of skeletal muscle metabolic and mitochondrial biology offers insight into the mitochondrial role in metabolic substrate partitioning and in promoting innate adaptive and maladaptive responses that collectively regulate peripheral insulin sensitivity. We conclude that skeletal muscle mitochondrial dysfunction is not generally a major initiator of the pathophysiology of insulin resistance, although its dysfunction is integral to this pathophysiology and it remains an intriguing target to reverse/delay the progressive perturbations synonymous with T2DM.
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Affiliation(s)
- Ines Pagel-Langenickel
- Translational Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, 10 Center Drive, Bethesda, Maryland 20892-1454, USA
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273
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Samocha-Bonet D, Heilbronn LK, Lichtenberg D, Campbell LV. Does skeletal muscle oxidative stress initiate insulin resistance in genetically predisposed individuals? Trends Endocrinol Metab 2010; 21:83-8. [PMID: 19854062 DOI: 10.1016/j.tem.2009.09.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Revised: 09/26/2009] [Accepted: 09/29/2009] [Indexed: 01/06/2023]
Abstract
Reactive oxygen species (ROS) are postulated to be a common trigger of insulin resistance. For example, treatment of adipocytes with either tumor-necrosis factor-alpha or dexamethasone increases ROS before impairing glucose uptake. Similarly, treatment with mitochondria-specific antioxidants preserves insulin sensitivity in animal models of insulin resistance. However, it remains unclear whether ROS contribute to insulin resistance in humans. First-degree relatives (FDRs) of type 2 diabetes subjects are at increased risk of developing insulin resistance and type 2 diabetes. Here we review the documented metabolic impairments in FDRs that could contribute to insulin resistance via increased oxidative stress. We propose that lipotoxic intermediates and lipid peroxides in skeletal muscle interfere with insulin signaling and might cause insulin resistance in these 'at risk' individuals.
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Affiliation(s)
- Dorit Samocha-Bonet
- Diabetes and Obesity Research Program, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, NSW 2010, Australia.
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274
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Chow L, From A, Seaquist E. Skeletal muscle insulin resistance: the interplay of local lipid excess and mitochondrial dysfunction. Metabolism 2010; 59:70-85. [PMID: 19766267 PMCID: PMC2789850 DOI: 10.1016/j.metabol.2009.07.009] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Revised: 06/02/2009] [Accepted: 07/09/2009] [Indexed: 01/07/2023]
Affiliation(s)
- Lisa Chow
- University of Minnesota Medical School, Minneapolis, MN 55455, United States.
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275
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Hwang H, Bowen BP, Lefort N, Flynn CR, De Filippis EA, Roberts C, Smoke CC, Meyer C, Højlund K, Yi Z, Mandarino LJ. Proteomics analysis of human skeletal muscle reveals novel abnormalities in obesity and type 2 diabetes. Diabetes 2010; 59:33-42. [PMID: 19833877 PMCID: PMC2797941 DOI: 10.2337/db09-0214] [Citation(s) in RCA: 186] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE Insulin resistance in skeletal muscle is an early phenomenon in the pathogenesis of type 2 diabetes. Studies of insulin resistance usually are highly focused. However, approaches that give a more global picture of abnormalities in insulin resistance are useful in pointing out new directions for research. In previous studies, gene expression analyses show a coordinated pattern of reduction in nuclear-encoded mitochondrial gene expression in insulin resistance. However, changes in mRNA levels may not predict changes in protein abundance. An approach to identify global protein abundance changes involving the use of proteomics was used here. RESEARCH DESIGN AND METHODS Muscle biopsies were obtained basally from lean, obese, and type 2 diabetic volunteers (n = 8 each); glucose clamps were used to assess insulin sensitivity. Muscle protein was subjected to mass spectrometry-based quantification using normalized spectral abundance factors. RESULTS Of 1,218 proteins assigned, 400 were present in at least half of all subjects. Of these, 92 were altered by a factor of 2 in insulin resistance, and of those, 15 were significantly increased or decreased by ANOVA (P < 0.05). Analysis of protein sets revealed patterns of decreased abundance in mitochondrial proteins and altered abundance of proteins involved with cytoskeletal structure (desmin and alpha actinin-2 both decreased), chaperone function (TCP-1 subunits increased), and proteasome subunits (increased). CONCLUSIONS The results confirm the reduction in mitochondrial proteins in insulin-resistant muscle and suggest that changes in muscle structure, protein degradation, and folding also characterize insulin resistance.
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Affiliation(s)
- Hyonson Hwang
- Center for Metabolic Biology, Arizona State University, Tempe, Arizona
- Department of Kinesiology, Arizona State University, Tempe, Arizona
| | - Benjamin P. Bowen
- Center for Metabolic Biology, Arizona State University, Tempe, Arizona
- Harrington Department of Bioengineering, Arizona State University, Tempe, Arizona
| | - Natalie Lefort
- Center for Metabolic Biology, Arizona State University, Tempe, Arizona
- Department of Kinesiology, Arizona State University, Tempe, Arizona
| | - Charles R. Flynn
- Center for Metabolic Biology, Arizona State University, Tempe, Arizona
| | | | - Christine Roberts
- Center for Metabolic Biology, Arizona State University, Tempe, Arizona
| | | | - Christian Meyer
- Center for Metabolic Biology, Arizona State University, Tempe, Arizona
| | - Kurt Højlund
- Center for Metabolic Biology, Arizona State University, Tempe, Arizona
- Diabetes Research Centre, Department of Endocrinology, Odense University Hospital, Odense, Denmark
| | - Zhengping Yi
- Center for Metabolic Biology, Arizona State University, Tempe, Arizona
- School of Life Sciences, Arizona State University, Tempe, Arizona
| | - Lawrence J. Mandarino
- Center for Metabolic Biology, Arizona State University, Tempe, Arizona
- Department of Kinesiology, Arizona State University, Tempe, Arizona
- School of Life Sciences, Arizona State University, Tempe, Arizona
- Corresponding author: Lawrence J. Mandarino,
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276
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Puddu P, Puddu GM, Cravero E, De Pascalis S, Muscari A. The emerging role of cardiovascular risk factor-induced mitochondrial dysfunction in atherogenesis. J Biomed Sci 2009; 16:112. [PMID: 20003216 PMCID: PMC2800844 DOI: 10.1186/1423-0127-16-112] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Accepted: 12/09/2009] [Indexed: 12/23/2022] Open
Abstract
An important role in atherogenesis is played by oxidative stress, which may be induced by common risk factors. Mitochondria are both sources and targets of reactive oxygen species, and there is growing evidence that mitochondrial dysfunction may be a relevant intermediate mechanism by which cardiovascular risk factors lead to the formation of vascular lesions. Mitochondrial DNA is probably the most sensitive cellular target of reactive oxygen species. Damage to mitochondrial DNA correlates with the extent of atherosclerosis. Several cardiovascular risk factors are demonstrated causes of mitochondrial damage. Oxidized low density lipoprotein and hyperglycemia may induce the production of reactive oxygen species in mitochondria of macrophages and endothelial cells. Conversely, reactive oxygen species may favor the development of type 2 diabetes mellitus, mainly through the induction of insulin resistance. Similarly - in addition to being a cause of endothelial dysfunction, reactive oxygen species and subsequent mitochondrial dysfunction - hypertension may develop in the presence of mitochondrial DNA mutations. Finally, other risk factors, such as aging, hyperhomocysteinemia and cigarette smoking, are also associated with mitochondrial damage and an increased production of free radicals. So far clinical studies have been unable to demonstrate that antioxidants have any effect on human atherogenesis. Mitochondrial targeted antioxidants might provide more significant results.
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Affiliation(s)
- Paolo Puddu
- Department of Internal Medicine, Aging and Nephrological Diseases, University of Bologna and S, Orsola-Malpighi Hospital, Bologna, Italy.
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277
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Jørgensen W, Gam C, Andersen JL, Schjerling P, Scheibye-Knudsen M, Mortensen OH, Grunnet N, Nielsen MO, Quistorff B. Changed mitochondrial function by pre- and/or postpartum diet alterations in sheep. Am J Physiol Endocrinol Metab 2009; 297:E1349-57. [PMID: 19826104 DOI: 10.1152/ajpendo.00505.2009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In a sheep model, we investigated diet effects on skeletal muscle mitochondria to look for fetal programming. During pregnancy, ewes were fed normally (N) or were 50% food restricted (L) during the last trimester, and lambs born to these ewes received a normal (N) or a high-fat diet (H) for the first 6 mo of life. We examined mitochondrial function in permeabilized muscle fibers from the lambs at 6 mo of age (adolescence) and after 24 mo of age (adulthood). The postpartum H diet for the lambs induced an approximately 30% increase (P < 0.05) of mitochondrial VO(2max) and an approximately 50% increase (P < 0.05) of the respiratory coupling ratio (RCR) combined with lower levels of UCP3 and PGC-1alpha mRNA levels (P < 0.05). These effects proved to be reversible by a normal diet from 6 to 24 mo of age. However, at 24 mo, a long-term effect of the maternal gestational diet restriction (fetal programming) became evident as a lower VO(2max) (approximately 40%, P < 0.05), a lower state 4 respiration (approximately 40%, P < 0.05), and lower RCR ( approximately 15%, P < 0.05). Both PGC-1alpha and UCP3 mRNA levels were increased (P < 0.05). Two analyzed muscles were affected differently, and muscle rich in type I fibers was more susceptible to fetal programming. We conclude that fetal programming, seen as a reduced VO(2max) in adulthood, results from gestational undernutrition. Postnatal high-fat diet results in a pronounced RCR and VO(2max) increase in adolescence. However, these effects are reversible by diet correction and are not maintained in adulthood.
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MESH Headings
- Animals
- Animals, Newborn
- Biopsy
- DNA, Mitochondrial/chemistry
- DNA, Mitochondrial/genetics
- Female
- Fetal Development/physiology
- Malnutrition/metabolism
- Maternal Nutritional Physiological Phenomena/physiology
- Mitochondria, Muscle/metabolism
- Mitochondria, Muscle/physiology
- Muscle Fibers, Skeletal/metabolism
- Muscle Fibers, Skeletal/physiology
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/physiology
- Oxygen Consumption/physiology
- PPAR delta/genetics
- PPAR delta/metabolism
- Pregnancy
- RNA, Messenger/chemistry
- RNA, Messenger/genetics
- Reverse Transcriptase Polymerase Chain Reaction
- Sheep/physiology
- Transcription Factors/genetics
- Transcription Factors/physiology
- Uncoupling Agents/metabolism
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Affiliation(s)
- Wenche Jørgensen
- Department of Biomedical Sciences, Nuclear Magnetic Resonance Center, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
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278
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Fleischman A, Kron M, Systrom DM, Hrovat M, Grinspoon SK. Mitochondrial function and insulin resistance in overweight and normal-weight children. J Clin Endocrinol Metab 2009; 94:4923-30. [PMID: 19846731 PMCID: PMC2795647 DOI: 10.1210/jc.2009-1590] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
BACKGROUND Obesity has become an epidemic in children, associated with an increase in insulin resistance and metabolic dysfunction. Mitochondrial function is known to be an important determinant of glucose metabolism in adults. However, little is known about the relationship between mitochondrial function and obesity, insulin resistance, energy expenditure, and pubertal development in children. METHODS Seventy-four participants, 37 overweight (> or = 85th percentile body mass index for age and sex) and 37 normal-weight (< 85th percentile) without personal or family history of diabetes mellitus were enrolled. Subjects were evaluated with an oral glucose tolerance test, metabolic markers, resting energy expenditure, Tanner staging, and (31)P magnetic resonance spectroscopy of skeletal muscle for mitochondrial function. RESULTS Overweight and normal-weight children showed no difference in muscle ATP synthesis [phosphocreatine (PCr) recovery after exercise] (32.4 +/- 2.3 vs. 34.1 +/- 2.1, P = 0.58). However, insulin-resistant children had significantly prolonged PCr recovery when compared with insulin-sensitive children, by homeostasis model assessment for insulin resistance quartile (ANOVA, P = 0.04). Similarly, insulin-resistant overweight children had PCr recovery that was prolonged compared with insulin-sensitive overweight children (P = 0.01). PCr recovery was negatively correlated with resting energy expenditure in multivariate modeling (P = 0.03). Mitochondrial function worsened during mid-puberty in association with insulin resistance. CONCLUSION Reduced skeletal muscle mitochondrial oxidative phosphorylation, assessed by PCr recovery, is associated with insulin resistance and an altered metabolic phenotype in children. Normal mitochondrial function may be associated with a healthier metabolic phenotype in overweight children. Further studies are needed to investigate the long-term physiological consequences and potential treatment strategies targeting children with reduced mitochondrial function.
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Affiliation(s)
- Amy Fleischman
- Program in Nutritional Metabolism, Massachusetts General Hospital, 55 Fruit Street, LON 207, Boston, Massachusetts 02114, USA.
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279
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Beck Jørgensen S, O'Neill HM, Hewitt K, Kemp BE, Steinberg GR. Reduced AMP-activated protein kinase activity in mouse skeletal muscle does not exacerbate the development of insulin resistance with obesity. Diabetologia 2009; 52:2395-404. [PMID: 19688337 DOI: 10.1007/s00125-009-1483-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Accepted: 07/02/2009] [Indexed: 10/20/2022]
Abstract
AIMS/HYPOTHESIS Obesity-related insulin resistance is associated with accumulation of bioactive lipids in skeletal muscle. The AMP-activated protein kinase (AMPK) regulates lipid oxidation in muscle by inhibiting acetyl-CoA carboxylase-2 (ACC2) and increasing mitochondrial biogenesis. We investigated whether reduced levels of muscle AMPK promote lipid accumulation and insulin resistance during high-fat feeding. METHODS Male C57/BL6 wild-type mice and transgenic littermates overexpressing an alpha2AMPK kinase-dead (KD) in muscle were fed control or high-fat diet. Whole-body glucose homeostasis was assessed by glucose and insulin tolerance tests, and by measuring fasting and fed serum insulin and glucose. Insulin action in muscle was determined by measuring 2-deoxy-[(3)H]glucose uptake and Akt phosphorylation in incubated soleus and extensor digitorum longus muscles. Muscle triacylglycerol, diacylglycerol and ceramide content was measured by thin-layer chromatography. Mitochondrial proteins were measured by immunoblotting. RESULTS KD mice had reduced skeletal muscle alpha2AMPK activity (50% in gastrocnemius and >80% in soleus and extensor digitorum longus) and ACC2 Ser228 phosphorylation (90% in gastrocnemius). High-fat feeding increased body mass and adiposity, and impaired insulin and glucose tolerance; however, there were no differences between wild-type and KD littermates. High-fat feeding impaired insulin-stimulated muscle glucose uptake and Akt-phosphorylation, while increasing muscle triacylglycerol, diacylglycerol (p = 0.07) and ceramide, but these effects were not exacerbated in KD mice. In response to high-fat feeding, mitochondrial proteins were increased to similar levels in wild-type and KD muscles. CONCLUSIONS/INTERPRETATION Obesity-induced lipid accumulation and insulin resistance were not exacerbated in AMPK KD mice, suggesting that reduced levels of muscle alpha2AMPK do not promote insulin resistance in the early phase of obesity-related diabetes.
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Affiliation(s)
- S Beck Jørgensen
- St Vincent's Institute of Medical Research and Department of Medicine, University of Melbourne, Fitzroy, VIC, Australia.
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280
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Lindinger A, Peterli R, Peters T, Kern B, von Flüe M, Calame M, Hoch M, Eberle AN, Lindinger PW. Mitochondrial DNA content in human omental adipose tissue. Obes Surg 2009; 20:84-92. [PMID: 19826890 DOI: 10.1007/s11695-009-9987-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2008] [Accepted: 09/22/2009] [Indexed: 12/18/2022]
Abstract
BACKGROUND Impairment of mitochondrial function plays an important role in obesity and the development of insulin resistance. The aim of this project was to investigate the mitochondrial DNA copy number in human omental adipose tissue with respect to obesity. METHODS The mitochondrial DNA (mtDNA) content per single adipocyte derived from abdominal omental adipose tissue was determined by quantitative RT-PCR in a group of 75 patients, consisting of obese and morbidly obese subjects, as well as non-obese controls. Additionally, basal metabolic rate and fat oxidation rate were recorded and expressed as total values or per kilogram fat mass. RESULTS MtDNA content is associated with obesity. Higher body mass index (BMI) resulted in a significantly elevated mtDNA count (ratio = 1.56; p = 0.0331) comparing non-obese (BMI < 30) to obese volunteers (BMI >or= 30). The mtDNA count per cell was not correlated with age or gender. Diabetic patients showed a trend toward reduced mtDNA content. A seasonal change in mtDNA copy number could not be identified. In addition, a substudy investigating the basal metabolic rate and the fasting fat oxidation did not reveal any associations to the mtDNA count. CONCLUSIONS The mtDNA content per cell of omental adipose tissue did not correlate with various clinical parameters but tended to be reduced in patients with diabetes, which may partly explain the impairment of mitochondrial function observed in insulin resistance. Furthermore, the mtDNA content was significantly increased in patients suffering from obesity (BMI above 30). This might reflect a compensatory response to the development of obesity, which is associated with impairment of mitochondrial function.
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281
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Johannsen DL, Ravussin E. The role of mitochondria in health and disease. Curr Opin Pharmacol 2009; 9:780-6. [PMID: 19796990 DOI: 10.1016/j.coph.2009.09.002] [Citation(s) in RCA: 167] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Revised: 08/31/2009] [Accepted: 09/02/2009] [Indexed: 01/07/2023]
Abstract
Mitochondria play a key role in energy metabolism in many tissues, including skeletal muscle and liver. Inherent disorders of mitochondria such as DNA deletions cause major disruption of metabolism and can result in severe impairment or death. However, the occurrence of such disorders is extremely rare and cannot account for the majority of metabolic disease. Recently, mitochondrial dysfunction of a more subtle nature in skeletal muscle has been implicated in the pathology of chronic metabolic disease characterized by insulin resistance such as obesity, type 2 diabetes mellitus, and aging. This hypothesis has been substantiated by work from Shulman and colleagues, showing that reduced mitochondrial oxidative capacity underlies the accumulation of intramuscular fat causing insulin resistance with aging. However, recent work by Nair and coworkers has demonstrated that mitochondrial activity may actually be higher in persons exposed to high-calorie diet leading to obesity, suggesting that the accumulation of intramuscular fat and associated fatty acid metabolites may be directly responsible for the development of insulin resistance, independent of mitochondrial function. These inconsistent findings have promoted ongoing investigation into mitochondrial function to determine whether impaired function is a cause or consequence of metabolic disorders.
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282
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Gaster M. Reduced TCA flux in diabetic myotubes: A governing influence on the diabetic phenotype? Biochem Biophys Res Commun 2009; 387:651-5. [PMID: 19615969 DOI: 10.1016/j.bbrc.2009.07.064] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Accepted: 07/13/2009] [Indexed: 02/03/2023]
Abstract
The diabetic phenotype is complex, requiring elucidation of key initiating defects. It is unknown whether the reduced tricarboxylic acid cycle (TCA) flux in skeletal muscle of obese and obese type 2 diabetic (T2D) subjects is of primary origin. Acetate oxidation (measurement of TCA-flux) was significantly reduced in primary myotube cultures established from T2D versus lean subjects. Acetate oxidation was acutely stimulated by insulin and respiratory uncoupling. Inhibition of TCA flux in lean myotubes by malonate was followed by a measured decline in; acetate oxidation, complete palmitate oxidation, lipid uptake, glycogen synthesis, ATP content and increased glucose uptake, while glucose oxidation was unaffected. Acute TCA inhibition did not induce insulin resistance. Thus the reduced TCA cycle flux in T2D skeletal muscle may be of primary origin. The diabetic phenotype of increased basal glucose uptake and glucose oxidation, the reduced complete lipid oxidation and increased respiratory quotient, are likely to be adaptive responses to the reduced TCA cycle flux.
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Affiliation(s)
- Michael Gaster
- KMEB, Dept. of Endocrinology, Odense University Hospital, Denmark.
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283
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Miljkovic I, Yerges LM, Li H, Gordon CL, Goodpaster BH, Kuller LH, Nestlerode CS, Bunker CH, Patrick AL, Wheeler VW, Zmuda JM. Association of the CPT1B gene with skeletal muscle fat infiltration in Afro-Caribbean men. Obesity (Silver Spring) 2009; 17:1396-401. [PMID: 19553926 PMCID: PMC2895554 DOI: 10.1038/oby.2008.677] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Skeletal muscle fat is greater in African ancestry individuals compared with whites, is associated with diabetes, and is a heritable polygenic trait. However, specific genetic factors contributing to skeletal muscle fat in humans remain to be defined. Muscle carnitine palmitoyltransferase-1B (CPT1B) is a key enzyme in the regulation of skeletal muscle mitochondrial beta-oxidation of long-chain fatty acids, and as such is a reasonable biological candidate gene for skeletal muscle fat accumulation. Therefore, we examined the association of three nonsynonymous coding variants in CPT1B (G531L, I66V, and S427C; a fourth, A320G, could not be genotyped) and quantitative computed tomography measured tibia skeletal muscle composition and BMI among 1,774 Afro-Caribbean men aged > or =40, participants of the population-based Tobago Health Study. For all variants, no significant differences were observed for BMI or total adipose tissue. Among individuals who were homozygous for the minor allele at G531L or I66V, intermuscular adipose tissue (IMAT) was 87% (P = 0.03) and 54% lower (P = 0.03), respectively. In contrast, subcutaneous adipose tissue (SAT) was 11% (P = 0.017) and 7% (P = 0.049) higher, respectively, than among individuals without these genotypes. These associations were independent of age, body size, and muscle area. Finally, no individuals with type 2 diabetes were found among those who were homozygous for the minor allele of either at G531L and I66V whereas 14-18% of men with the major alleles had type 2 diabetes (P = 0.03 and 0.007, respectively). Our results suggest a novel association between common nonsynonymous coding variants in CPT1B and ectopic skeletal muscle fat among middle-aged and older African ancestry men.
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Affiliation(s)
- Iva Miljkovic
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
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284
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Linoleic acid-induced mitochondrial Ca(2+) efflux causes peroxynitrite generation and protein nitrotyrosylation. PLoS One 2009; 4:e6048. [PMID: 19557129 PMCID: PMC2699034 DOI: 10.1371/journal.pone.0006048] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Accepted: 05/27/2009] [Indexed: 12/22/2022] Open
Abstract
It is well known that excessive non-esterified fatty acids in diabetes contribute to the pathogenesis of renal complications although the mechanism remains elusive. Enhanced oxidative stress has been hypothesized as a unified factor contributing to diabetic complications and increased protein nitrotyrosylation has been reported in the kidneys of diabetic patients. In the current manuscript we described that linoleic acid (LA) caused mitochondrial Ca2+ efflux and peroxynitrite production, along with increased nitrotyrosine levels of cellular proteins in primary human mesangial cells. The peroxynitrite production by LA was found to depend on mitochondrial Ca2+ efflux. Downregulation of hsp90β1, which has been previously shown to be essential for polyunsaturated fatty acid-induced mitochondrial Ca2+ efflux, significantly diminished LA-responsive mitochondrial Ca2+ efflux and the coupled peroxynitrite generation, implicating a critical role of hsp90β1 in the LA responses. Our results further demonstrated that mitochondrial complexes I and III were directly involved in the LA-induced peroxynitrite generation. Using the well established type 2 diabetic animal model db/db mice, we observed a dramatically enhanced LA responsive mitochondrial Ca2+ efflux and protein nitrotyrosylation in the kidney. Our study thus demonstrates a cause-effect relationship between LA and peroxynitrite or protein nitrotyrosylation and provides a novel mechanism for lipid-induced nephropathy in diabetes.
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285
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Adams SH, Hoppel CL, Lok KH, Zhao L, Wong SW, Minkler PE, Hwang DH, Newman JW, Garvey WT. Plasma acylcarnitine profiles suggest incomplete long-chain fatty acid beta-oxidation and altered tricarboxylic acid cycle activity in type 2 diabetic African-American women. J Nutr 2009; 139:1073-81. [PMID: 19369366 PMCID: PMC2714383 DOI: 10.3945/jn.108.103754] [Citation(s) in RCA: 461] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Inefficient muscle long-chain fatty acid (LCFA) combustion is associated with insulin resistance, but molecular links between mitochondrial fat catabolism and insulin action remain controversial. We hypothesized that plasma acylcarnitine profiling would identify distinct metabolite patterns reflective of muscle fat catabolism when comparing individuals bearing a missense G304A uncoupling protein 3 (UCP3 g/a) polymorphism to controls, because UCP3 is predominantly expressed in skeletal muscle and g/a individuals have reduced whole-body fat oxidation. MS analyses of 42 carnitine moieties in plasma samples from fasting type 2 diabetics (n = 44) and nondiabetics (n = 12) with or without the UCP3 g/a polymorphism (n = 28/genotype: 22 diabetic, 6 nondiabetic/genotype) were conducted. Contrary to our hypothesis, genotype had a negligible impact on plasma metabolite patterns. However, a comparison of nondiabetics vs. type 2 diabetics revealed a striking increase in the concentrations of fatty acylcarnitines reflective of incomplete LCFA beta-oxidation in the latter (i.e. summed C10- to C14-carnitine concentrations were approximately 300% of controls; P = 0.004). Across all volunteers (n = 56), acetylcarnitine rose and propionylcarnitine decreased with increasing hemoglobin A1c (r = 0.544, P < 0.0001; and r = -0.308, P < 0.05, respectively) and with increasing total plasma acylcarnitine concentration. In proof-of-concept studies, we made the novel observation that C12-C14 acylcarnitines significantly stimulated nuclear factor kappa-B activity (up to 200% of controls) in RAW264.7 cells. These results are consistent with the working hypothesis that inefficient tissue LCFA beta-oxidation, due in part to a relatively low tricarboxylic acid cycle capacity, increases tissue accumulation of acetyl-CoA and generates chain-shortened acylcarnitine molecules that activate proinflammatory pathways implicated in insulin resistance.
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Affiliation(s)
- Sean H. Adams
- USDA/Agricultural Research Service Western Human Nutrition Research Center and Department of Nutrition, University of California, Davis, CA 95616; Department of Pharmacology, Case Western Reserve University, Cleveland, OH, 44106; and Department of Nutrition Sciences, University of Alabama, Birmingham, AL 35294
| | - Charles L. Hoppel
- USDA/Agricultural Research Service Western Human Nutrition Research Center and Department of Nutrition, University of California, Davis, CA 95616; Department of Pharmacology, Case Western Reserve University, Cleveland, OH, 44106; and Department of Nutrition Sciences, University of Alabama, Birmingham, AL 35294
| | - Kerry H. Lok
- USDA/Agricultural Research Service Western Human Nutrition Research Center and Department of Nutrition, University of California, Davis, CA 95616; Department of Pharmacology, Case Western Reserve University, Cleveland, OH, 44106; and Department of Nutrition Sciences, University of Alabama, Birmingham, AL 35294
| | - Ling Zhao
- USDA/Agricultural Research Service Western Human Nutrition Research Center and Department of Nutrition, University of California, Davis, CA 95616; Department of Pharmacology, Case Western Reserve University, Cleveland, OH, 44106; and Department of Nutrition Sciences, University of Alabama, Birmingham, AL 35294
| | - Scott W. Wong
- USDA/Agricultural Research Service Western Human Nutrition Research Center and Department of Nutrition, University of California, Davis, CA 95616; Department of Pharmacology, Case Western Reserve University, Cleveland, OH, 44106; and Department of Nutrition Sciences, University of Alabama, Birmingham, AL 35294
| | - Paul E. Minkler
- USDA/Agricultural Research Service Western Human Nutrition Research Center and Department of Nutrition, University of California, Davis, CA 95616; Department of Pharmacology, Case Western Reserve University, Cleveland, OH, 44106; and Department of Nutrition Sciences, University of Alabama, Birmingham, AL 35294
| | - Daniel H. Hwang
- USDA/Agricultural Research Service Western Human Nutrition Research Center and Department of Nutrition, University of California, Davis, CA 95616; Department of Pharmacology, Case Western Reserve University, Cleveland, OH, 44106; and Department of Nutrition Sciences, University of Alabama, Birmingham, AL 35294
| | - John W. Newman
- USDA/Agricultural Research Service Western Human Nutrition Research Center and Department of Nutrition, University of California, Davis, CA 95616; Department of Pharmacology, Case Western Reserve University, Cleveland, OH, 44106; and Department of Nutrition Sciences, University of Alabama, Birmingham, AL 35294
| | - W. Timothy Garvey
- USDA/Agricultural Research Service Western Human Nutrition Research Center and Department of Nutrition, University of California, Davis, CA 95616; Department of Pharmacology, Case Western Reserve University, Cleveland, OH, 44106; and Department of Nutrition Sciences, University of Alabama, Birmingham, AL 35294
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286
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Buscemi S, Verga S, Donatelli M, D'Orio L, Mattina A, Tranchina MR, Pizzo G, Mulè G, Cerasola G. A low reported energy intake is associated with metabolic syndrome. J Endocrinol Invest 2009; 32:538-41. [PMID: 19474528 DOI: 10.1007/bf03346503] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND AND AIMS Metabolic syndrome (MS) may be associated with the presence of an energy-sparing metabolism that predisposes to the excess accumulation of body fat. This study examined the relationship between reported energy intake and obesity in individuals with and without MS. METHODS AND RESULTS Ninety consecutive non-diabetic obese subjects were divided into 2 groups based on the presence (MS+: no.=50) or absence (MS-: no.=40) of MS. The study design was cross-sectional. The 3-day food record method was used to assess the subjects' usual energy intake and the Diet Readiness Test (DRT) was also administered. Compared to the MS- group, the MS+ group had a significantly higher body weight, body mass index (mean+/-SEM: 39.1+/-1.3 vs 31.5+/-0.9, p<0.001) and fat mass. The absolute energy intake of the MS+ group (8629+/-331 kJ/24h) did not differ from that of the MS- group (8571+/-515 kJ/24h; p=ns). The daily energy intake normalized for the fat-free mass (FFM) size was higher in the MS- group (163+/-8 kJ/kg-FFM x 24h) than in the MS+ group (138+/-4 kJ/kg-FFM x 24h; p<0.03). The DRT test results were similar in both groups except that section 6 (exercise patterns and attitudes) score was lower in the MS+ group (10.0+/-0.5) than in the MS- group (11.9+/-0.5; p<0.01). CONCLUSION The results of this study support the hypothesis that subjects with MS have an energy-sparing metabolism.
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Affiliation(s)
- S Buscemi
- Department of Internal Medicine, Cardiovascular and Nephrourological Diseases, Faculty of Medicine, University of Palermo, Palermo, Italy.
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287
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Abstract
Early interventions to prevent type 2 diabetes mellitus (T2DM) demand a better understanding of its underlying mechanisms. Nonobese healthy subjects with a strong family history of T2DM (FH(+) subjects) hold a key to this end by allowing the study of the disease before the development of confounding factors, such as obesity or hyperglycemia. In this article, we share our experience over the past decade in studying FH(+) subjects and how lipotoxicity alters glucose metabolism in such individuals, in particular pancreatic beta-cell function. FH(+) subjects have no obvious clinical abnormalities, but when carefully studied, reveal severe hepatic/muscle/adipose tissue insulin resistance and subtle defects in beta-cell function. In most subjects, metabolic adaption allows freedom from diabetes for decades. However, the obesity epidemic is drastically changing this. Given the unique susceptibility of pancreatic beta cells to free fatty acids in FH(+) subjects, interventions that protect against obesity-induced lipotoxicity may hold the greatest promise for preventing T2DM in genetically predisposed individuals.
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Affiliation(s)
- Kenneth Cusi
- Diabetes Division, Department of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
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288
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Gaster M. Reduced lipid oxidation in myotubes established from obese and type 2 diabetic subjects. Biochem Biophys Res Commun 2009; 382:766-70. [DOI: 10.1016/j.bbrc.2009.03.102] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Accepted: 03/19/2009] [Indexed: 11/28/2022]
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289
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Brøns C, Jensen CB, Storgaard H, Hiscock NJ, White A, Appel JS, Jacobsen S, Nilsson E, Larsen CM, Astrup A, Quistorff B, Vaag A. Impact of short-term high-fat feeding on glucose and insulin metabolism in young healthy men. J Physiol 2009; 587:2387-97. [PMID: 19332493 DOI: 10.1113/jphysiol.2009.169078] [Citation(s) in RCA: 191] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
A high-fat, high-calorie diet is associated with obesity and type 2 diabetes. However, the relative contribution of metabolic defects to the development of hyperglycaemia and type 2 diabetes is controversial. Accumulation of excess fat in muscle and adipose tissue in insulin resistance and type 2 diabetes may be linked with defective mitochondrial oxidative phosphorylation. The aim of the current study was to investigate acute effects of short-term fat overfeeding on glucose and insulin metabolism in young men. We studied the effects of 5 days' high-fat (60% energy) overfeeding (+50%) versus a control diet on hepatic and peripheral insulin action by a hyperinsulinaemic euglycaemic clamp, muscle mitochondrial function by (31)P magnetic resonance spectroscopy, and gene expression by qrt-PCR and microarray in 26 young men. Hepatic glucose production and fasting glucose levels increased significantly in response to overfeeding. However, peripheral insulin action, muscle mitochondrial function, and general and specific oxidative phosphorylation gene expression were unaffected by high-fat feeding. Insulin secretion increased appropriately to compensate for hepatic, and not for peripheral, insulin resistance. High-fat feeding increased fasting levels of plasma adiponectin, leptin and gastric inhibitory peptide (GIP). High-fat overfeeding increases fasting glucose levels due to increased hepatic glucose production. The increased insulin secretion may compensate for hepatic insulin resistance possibly mediated by elevated GIP secretion. Increased insulin secretion precedes the development of peripheral insulin resistance, mitochondrial dysfunction and obesity in response to overfeeding, suggesting a role for insulin per se as well GIP, in the development of peripheral insulin resistance and obesity.
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Affiliation(s)
- Charlotte Brøns
- Steno Diabetes Center, Niels Steensens Vej 1, 2820 Gentofte, Denmark.
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290
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Lindroos MM, Majamaa K, Tura A, Mari A, Kalliokoski KK, Taittonen MT, Iozzo P, Nuutila P. m.3243A>G mutation in mitochondrial DNA leads to decreased insulin sensitivity in skeletal muscle and to progressive beta-cell dysfunction. Diabetes 2009; 58:543-9. [PMID: 19073775 PMCID: PMC2646052 DOI: 10.2337/db08-0981] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE To study insulin sensitivity and perfusion in skeletal muscle together with the beta-cell function in subjects with the m.3243A>G mutation in mitochondrial DNA, the most common cause of mitochondrial diabetes. RESEARCH DESIGN AND METHODS We measured skeletal muscle glucose uptake and perfusion using positron emission tomography and 2-[18F]fluoro-2-deoxyglucose and [15O]H2O during euglycemic hyperinsulinemia in 15 patients with m.3243A>G. These patients included five subjects with no diabetes as defined by the oral glucose tolerance test (OGTT) (group 1), three with GHb <6.1% and newly found diabetes by OGTT (group 2), and seven with a previously diagnosed diabetes (group 3). Control subjects consisted of 13 healthy individuals who were similar to the carriers of m.3243A>G with respect to age and physical activity. Beta-cell function was assessed using the OGTT and subsequent mathematical modeling. RESULTS Skeletal muscle glucose uptake was significantly lower in groups 1, 2, and 3 than in the control subjects. The glucose sensitivity of beta-cells in group 1 patients was similar to that of the control subjects, whereas in group 2 and 3 patients, the glucose sensitivity was significantly lower. The insulin secretion parameters correlated strongly with the proportion of m.3243A>G mutation in muscle. CONCLUSIONS Our findings show that subjects with m.3243A>G are insulin resistant in skeletal muscle even when beta-cell function is not markedly impaired or glucose control compromised. We suggest that both the skeletal muscle insulin sensitivity and the beta-cell function are affected before the onset of the mitochondrial diabetes caused by the m.3243A>G mutation.
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Affiliation(s)
- Markus M Lindroos
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.
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291
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Mitsuishi M, Miyashita K, Muraki A, Itoh H. Angiotensin II reduces mitochondrial content in skeletal muscle and affects glycemic control. Diabetes 2009; 58:710-7. [PMID: 19074984 PMCID: PMC2646070 DOI: 10.2337/db08-0949] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE Blockade of angiotensin (Ang) II has been shown to prevent new-onset type 2 diabetes. We focused on the effects of AngII on muscle mitochondria, especially on their biogenesis, as an underlining mechanism of type 2 diabetes. RESEARCH DESIGN AND METHODS C2C12 cells and C57bl/6 mice were used to examine roles for AngII in the regulation of muscle mitochondria and to explore whether the effect was mediated by type 1 AngII receptor (AT1R) or type 2 receptor (AT2R). RESULTS C2C12 cells treated with 10(-8)-10(-6) mol/l AngII reduced the mitochondrial content associated with downregulation of the genes involved in mitochondrial biogenesis. The action of AngII was diminished by blockade of AT2R but not AT1R, whereas overexpression of AT2R augmented the effect. AngII increased mitochondrial ROS and decreased mitochondrial membrane potential, and these effects of AngII were significantly suppressed by blockade of either AT1R or AT2R. Chronic AngII infusion in mice also reduced muscle mitochondrial content in association with increased intramuscular triglyceride and deteriorated glycemic control. The AngII-induced reduction in muscle mitochondria in mice was partially, but significantly, reversed by blockade of either AT1R or AT2R, associated with increased fat oxidation, decreased muscle triglyceride, and improved glucose tolerance. Genes involved in mitochondrial biogenesis were decreased via AT2R but not AT1R under these in vivo conditions. CONCLUSIONS Taken together, these findings imply the novel roles for AngII in the regulation of muscle mitochondria and lipid metabolism. AngII reduces mitochondrial content possibly through AT1R-dependent augmentation of their degradation and AT2R-dependent direct suppression of their biogenesis.
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MESH Headings
- Angiotensin II/pharmacology
- Animals
- Calorimetry, Indirect
- Cell Line
- DNA, Mitochondrial/genetics
- Gene Expression/drug effects
- Glucose Tolerance Test
- Membrane Potentials
- Mice
- Mice, Inbred C57BL
- Mitochondria, Muscle/drug effects
- Mitochondria, Muscle/metabolism
- Oligonucleotide Array Sequence Analysis
- Polymerase Chain Reaction
- RNA Interference
- Receptor, Angiotensin, Type 1/drug effects
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/physiology
- Receptor, Angiotensin, Type 2/drug effects
- Receptor, Angiotensin, Type 2/genetics
- Receptor, Angiotensin, Type 2/physiology
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Affiliation(s)
- Masanori Mitsuishi
- Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan
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292
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Khuu A, Ren J, Dimitrov I, Woessner D, Murdoch J, Sherry AD, Malloy CR. Orientation of lipid strands in the extracellular compartment of muscle: effect on quantitation of intramyocellular lipids. Magn Reson Med 2009; 61:16-21. [PMID: 19097207 DOI: 10.1002/mrm.21831] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Single-voxel (1)H NMR spectra from gastrocnemius and soleus muscle were acquired in healthy volunteers at 7T with the objective of measuring the concentration of intramyocellular lipid [IMCL] (note: throughout this article, square brackets indicate concentration). However, significant asymmetry in the resonance assigned to the methylene protons (-CH(2)-)(n) in extramyocellular lipids (EMCL) interfered with fitting the spectra. Since muscle fibers in these tissues are generally not parallel to B(0), the influence of variable orientation in strands of extracellular fat was examined using a mathematical model. Modest variation in orientation produced asymmetric lineshapes that were qualitatively similar to typical observations at 7T. Analysis of simulated spectra by fitting with a Voigt function overestimated [IMCL]/[EMCL] except when EMCL fibers were nearly parallel to B(0). Estimates of [IMCL]/[EMCL] were improved by including variations in fiber orientation in the lineshape analysis (fiber orientation modeling, or FOM). Calculated [IMCL] using FOM, 4.8 +/- 2.2 mmol/kg wet weight, was lower compared to most previous reports in soleus.
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Affiliation(s)
- Anthony Khuu
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390-8568, USA
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293
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Schulthess FT, Katz S, Ardestani A, Kawahira H, Georgia S, Bosco D, Bhushan A, Maedler K. Deletion of the mitochondrial flavoprotein apoptosis inducing factor (AIF) induces beta-cell apoptosis and impairs beta-cell mass. PLoS One 2009; 4:e4394. [PMID: 19197367 PMCID: PMC2632884 DOI: 10.1371/journal.pone.0004394] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2008] [Accepted: 12/15/2008] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Apoptosis is a hallmark of beta-cell death in both type 1 and type 2 diabetes mellitus. Understanding how apoptosis contributes to beta-cell turnover may lead to strategies to prevent progression of diabetes. A key mediator of apoptosis, mitochondrial function, and cell survival is apoptosis inducing factor (AIF). In the present study, we investigated the role of AIF on beta-cell mass and survival using the Harlequin (Hq) mutant mice, which are hypomorphic for AIF. METHODOLOGY/PRINCIPAL FINDINGS Immunohistochemical evaluation of pancreata from Hq mutant mice displayed much smaller islets compared to wild-type mice (WT). Analysis of beta-cell mass in these mice revealed a greater than 4-fold reduction in beta-cell mass together with an 8-fold increase in beta-cell apoptosis. Analysis of cell cycle dynamics, using BrdU pulse as a marker for cells in S-phase, did not detect significant differences in the frequency of beta-cells in S-phase. In contrast, double staining for phosphorylated Histone H3 and insulin showed a 3-fold increase in beta-cells in the G2 phase in Hq mutant mice, but no differences in M-phase compared to WT mice. This suggests that the beta-cells from Hq mutant mice are arrested in the G2 phase and are unlikely to complete the cell cycle. beta-cells from Hq mutant mice display increased sensitivity to hydrogen peroxide-induced apoptosis, which was confirmed in human islets in which AIF was depleted by siRNA. AIF deficiency had no effect on glucose stimulated insulin secretion, but the impaired effect of hydrogen peroxide on beta-cell function was potentiated. CONCLUSIONS/SIGNIFICANCE Our results indicate that AIF is essential for maintaining beta-cell mass and for oxidative stress response. A decrease in the oxidative phosphorylation capacity may counteract the development of diabetes, despite its deleterious effects on beta-cell survival.
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Affiliation(s)
- Fabienne T. Schulthess
- Centre for Biomolecular Interactions, University of Bremen, Bremen, Germany
- Larry L. Hillblom Islet Research Center, Department of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Sophie Katz
- Larry L. Hillblom Islet Research Center, Department of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Amin Ardestani
- Centre for Biomolecular Interactions, University of Bremen, Bremen, Germany
| | - Hiroshi Kawahira
- Larry L. Hillblom Islet Research Center, Department of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Senta Georgia
- Larry L. Hillblom Islet Research Center, Department of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Domenico Bosco
- Cell Isolation and Transplantation Center, Department of Surgery, University of Geneva School of Medicine, Genèva, Switzerland
| | - Anil Bhushan
- Larry L. Hillblom Islet Research Center, Department of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Kathrin Maedler
- Centre for Biomolecular Interactions, University of Bremen, Bremen, Germany
- Larry L. Hillblom Islet Research Center, Department of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail:
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294
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Chanséaume E, Morio B. Potential mechanisms of muscle mitochondrial dysfunction in aging and obesity and cellular consequences. Int J Mol Sci 2009; 10:306-324. [PMID: 19333447 PMCID: PMC2662471 DOI: 10.3390/ijms10010306] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Revised: 01/07/2009] [Accepted: 01/09/2009] [Indexed: 12/15/2022] Open
Abstract
Mitochondria play a key role in the energy metabolism in skeletal muscle. A new concept has emerged suggesting that impaired mitochondrial oxidative capacity in skeletal muscle may be the underlying defect that causes insulin resistance. According to current knowledge, the causes and the underlying molecular mechanisms at the origin of decreased mitochondrial oxidative capacity in skeletal muscle still remain to be elucidated. The present review focuses on recent data investigating these issues in the area of metabolic disorders and describes the potential causes, mechanisms and consequences of mitochondrial dysfunction in the skeletal muscle.
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Affiliation(s)
- Emilie Chanséaume
- INRA, UMR1019 Nutrition Humaine, F-63120 Saint Genès Champanelle, France. E-Mail:
- Université Clermont 1, UFR Médecine, UMR1019 Nutrition Humaine, F-63000 Clermont-Ferrand, France
| | - Béatrice Morio
- INRA, UMR1019 Nutrition Humaine, F-63120 Saint Genès Champanelle, France. E-Mail:
- Université Clermont 1, UFR Médecine, UMR1019 Nutrition Humaine, F-63000 Clermont-Ferrand, France
- * Author to whom correspondence should be addressed; E-Mail:
; Tel. +33-473 608 272; Fax: +33-473 608 255
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295
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Lumini JA, Magalhães J, Oliveira PJ, Ascensão A. Beneficial effects of exercise on muscle mitochondrial function in diabetes mellitus. Sports Med 2009; 38:735-50. [PMID: 18712941 DOI: 10.2165/00007256-200838090-00003] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The physiopathology of diabetes mellitus has been closely associated with a variety of alterations in mitochondrial histology, biochemistry and function. Generally, the alterations comprise increased mitochondrial reactive oxygen and nitrogen species (RONS) generation, resulting in oxidative stress and damage; decreased capacity to metabolize lipids, leading to intramyocyte lipid accumulation; and diminished mitochondrial density and reduced levels of uncoupling proteins (UCPs), with consequent impairment in mitochondrial function. Chronic physical exercise is a physiological stimulus able to induce mitochondrial adaptations that can counteract the adverse effects of diabetes on muscle mitochondria. However, the mechanisms responsible for mitochondrial adaptations in the muscles of diabetic patients are still unclear. The main mechanisms by which exercise may be considered an important non-pharmacological strategy for preventing and/or attenuating diabetes-induced mitochondrial impairments may involve (i) increased mitochondrial biogenesis, which is dependent on the increased expression of some important proteins, such as the 'master switch' peroxisome proliferator-activated receptor (PPAR)-gamma-coactivator-1alpha (PGC-1alpha) and heat shock proteins (HSPs), both of which are severely downregulated in the muscles of diabetic patients; and (ii) the restoration or attenuation of the low UCP3 expression in skeletal muscle mitochondria of diabetic patients, which is suggested to play a pivotal role in mitochondrial dysfunction.There is evidence that chronic exercise and lifestyle interventions reverse impairments in mitochondrial density and size, in the activity of respiratory chain complexes and in cardiolipin content; however, the mechanisms by which chronic exercise alters mitochondrial respiratory parameters, mitochondrial antioxidant systems and other specific proteins involved in mitochondrial metabolism in the muscles of diabetic patients remain to be elucidated.
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Affiliation(s)
- José A Lumini
- Research Centre in Physical Activity, Health and Leisure, University of Porto, Porto, Portugal
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296
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Short KR. Introduction to symposium proceedings: the emerging interplay among muscle mitochondrial function, nutrition, and disease. Am J Clin Nutr 2009; 89:453S-4S. [PMID: 19056554 DOI: 10.3945/ajcn.2008.26717a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Affiliation(s)
- Kevin R Short
- Department of Pediatrics, Section of Diabetes & Endocrinology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73117, USA.
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297
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Scheele C, Larsson O, Timmons JA. Using functional genomics to study PINK1 and metabolic physiology. Methods Enzymol 2009; 457:211-29. [PMID: 19426870 DOI: 10.1016/s0076-6879(09)05012-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Genome sequencing projects have provided the substrate for an unimaginable number of biological experiments. Further, genomic technologies such as microarrays and quantitative and exquisitely sensitive techniques such as real-time quantitative polymerase chain reaction have made it possible to reliably generate millions of data points per experiment. The data can be high quality and yield entirely new insights into how gene expression is coordinated under complex physiological situations. It can also be that the data and interpretation are meaningless because of a lack of physiological context or experimental control. Thus, functional genomics is now being applied to study metabolic physiology with varying degrees of success. From the genome sequencing projects we also have the information needed to design chemical tools that can knock down a gene transcript, even distinguishing between splice variants in mammalian cells. Use of such technologies, inspired by nature's endogenous RNAi mechanism-microRNA targeting, comes with significant caveats. While the discipline of Pharmacology taught us last century that inhibitor action specificity is dependent on the concentration used, these experiences have been ignored by users of siRNA technologies. What we provide in this chapter is some considerations and observations from functional genomic studies. We are largely concerned with the phase that follows a microarray study, where a candidate gene is selected for manipulation in a system that is considered to be simpler than the in vivo mammalian tissue and thus the methods discussed largely apply to this cell biology phase. We apologize for not referring to all relevant publications and for any technical considerations we have also failed to factor into our discussion.
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Affiliation(s)
- Camilla Scheele
- The Centre of Inflammation and Metabolism, Department of Infectious Diseases and CMRC, Rigshospitalet, The Faculty of Health Sciences, University of Copenhagen, Denmark
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298
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Holloszy JO. Skeletal muscle "mitochondrial deficiency" does not mediate insulin resistance. Am J Clin Nutr 2009; 89:463S-6S. [PMID: 19056574 DOI: 10.3945/ajcn.2008.26717c] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Patients with type 2 diabetes, insulin-resistant obese individuals, and insulin-resistant offspring of patients with diabetes have approximately 30% less mitochondria in their skeletal muscles than age-matched healthy controls. It has been hypothesized that this "deficiency" of mitochondria mediates insulin resistance by impairing the ability of muscle to oxidize fatty acids (FAs). However, a 30% decrease in mitochondria should not impair the ability of muscle to oxidize FAs because the capacity of muscle to oxidize substrate is far in excess of what is needed to supply energy in the basal state, ie, in resting muscle. In pathologic states in which mitochondrial content/function is so severely impaired as to limit substrate oxidation in resting muscle, glucose uptake and insulin action are actually enhanced. Recent studies have shown that feeding rodents high-fat diets and raising FA concentrations results in muscle insulin resistance despite an increase muscle mitochondria that enhances the capacity for fat oxidation. Furthermore, it was recently shown that skeletal muscle mitochondrial capacity for oxidative phosphorylation in Asian Indians with type 2 diabetes is the same as in nondiabetic Indians and higher than in healthy European Americans. In light of this evidence, it seems highly unlikely that "mitochondrial deficiency" causes muscle insulin resistance.
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Affiliation(s)
- John O Holloszy
- Division of Geriatrics and Nutritional Sciences, Washington University School of Medicine, St Louis, MO 63110, USA.
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299
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Befroy DE, Falk Petersen K, Rothman DL, Shulman GI. Assessment of in vivo mitochondrial metabolism by magnetic resonance spectroscopy. Methods Enzymol 2009; 457:373-93. [PMID: 19426879 DOI: 10.1016/s0076-6879(09)05021-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Magnetic resonance spectroscopy (MRS), a companion technique to the more familiar MRI scan, has emerged as a powerful technique for studying metabolism noninvasively in a variety of tissues. In this article, we review two techniques that we have developed which take advantage of the unique characteristics of (31)P and (13)C MRS to investigate two distinct parameters of muscle mitochondrial metabolism; ATP production can be estimated by using the (31)P saturation-transfer technique, and oxidation via the TCA cycle can be modeled from (13)C MRS data obtained during the metabolism of a (13)C-labeled substrate. We will also examine applications of the techniques to investigate how these parameters of muscle mitochondrial metabolism are modulated in insulin resistant and endurance trained individuals.
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Affiliation(s)
- Douglas E Befroy
- Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut, USA
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300
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Paradoxical effects of increased expression of PGC-1alpha on muscle mitochondrial function and insulin-stimulated muscle glucose metabolism. Proc Natl Acad Sci U S A 2008; 105:19926-31. [PMID: 19066218 DOI: 10.1073/pnas.0810339105] [Citation(s) in RCA: 229] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Peroxisome proliferator-activated receptor-gamma coactivator (PGC)-1alpha has been shown to play critical roles in regulating mitochondria biogenesis, respiration, and muscle oxidative phenotype. Furthermore, reductions in the expression of PGC-1alpha in muscle have been implicated in the pathogenesis of type 2 diabetes. To determine the effect of increased muscle-specific PGC-1alpha expression on muscle mitochondrial function and glucose and lipid metabolism in vivo, we examined body composition, energy balance, and liver and muscle insulin sensitivity by hyperinsulinemic-euglycemic clamp studies and muscle energetics by using (31)P magnetic resonance spectroscopy in transgenic mice. Increased expression of PGC-1alpha in muscle resulted in a 2.4-fold increase in mitochondrial density, which was associated with an approximately 60% increase in the unidirectional rate of ATP synthesis. Surprisingly, there was no effect of increased muscle PGC-1alpha expression on whole-body energy expenditure, and PGC-1alpha transgenic mice were more prone to fat-induced insulin resistance because of decreased insulin-stimulated muscle glucose uptake. The reduced insulin-stimulated muscle glucose uptake could most likely be attributed to a relative increase in fatty acid delivery/triglyceride reesterfication, as reflected by increased expression of CD36, acyl-CoA:diacylglycerol acyltransferase1, and mitochondrial acyl-CoA:glycerol-sn-3-phosphate acyltransferase, that may have exceeded mitochondrial fatty acid oxidation, resulting in increased intracellular lipid accumulation and an increase in the membrane to cytosol diacylglycerol content. This, in turn, caused activation of PKC, decreased insulin signaling at the level of insulin receptor substrate-1 (IRS-1) tyrosine phosphorylation, and skeletal muscle insulin resistance.
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