51
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A grape polyphenol extract modulates muscle membrane fatty acid composition and lipid metabolism in high-fat--high-sucrose diet-fed rats. Br J Nutr 2011; 106:491-501. [PMID: 21554810 DOI: 10.1017/s0007114511000602] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Accumulation of muscle TAG content and modification of muscle phospholipid fatty acid pattern may have an impact on lipid metabolism, increasing the risk of developing diabetes. Some polyphenols have been reported to modulate lipid metabolism, in particular those issued from red grapes. The present study was designed to determine whether a grape polyphenol extract (PPE) modulates skeletal muscle TAG content and phospholipid fatty acid composition in high-fat-high-sucrose (HFHS) diet-fed rats. Muscle plasmalemmal and mitochondrial fatty acid transporters, GLUT4 and lipid metabolism pathways were also explored. The PPE decreased muscle TAG content in HFHS/PPE diet-fed rats compared with HFHS diet-fed rats and induced higher proportions of n-3 PUFA in phospholipids. The PPE significantly up-regulated GLUT4 mRNA expression. Gene and protein expression of muscle fatty acid transporter cluster of differentiation 36 (CD36) was increased in HFHS diet-fed rats but returned to control values in HFHS/PPE diet-fed rats. Carnitine palmitoyltransferase 1 protein expression was decreased with the PPE. Mitochondrial β-hydroxyacyl CoA dehydrogenase was increased in HFHS diet-fed rats and returned to control values with PPE supplementation. Lipogenesis, mitochondrial biogenesis and mitochondrial activity were not affected by the PPE. In conclusion, the PPE modulated membrane phospholipid fatty acid composition and decreased muscle TAG content in HFHS diet-fed rats. The PPE lowered CD36 gene and protein expression, probably decreasing fatty acid transport and lipid accumulation within skeletal muscle, and increased muscle GLUT4 expression. These effects of the PPE are in favour of a better insulin sensibility.
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García-Serrano S, Moreno-Santos I, Garrido-Sánchez L, Gutierrez-Repiso C, García-Almeida JM, García-Arnés J, Rivas-Marín J, Gallego-Perales JL, García-Escobar E, Rojo-Martinez G, Tinahones F, Soriguer F, Macias-Gonzalez M, García-Fuentes E. Stearoyl-CoA desaturase-1 is associated with insulin resistance in morbidly obese subjects. Mol Med 2011; 17:273-80. [PMID: 21060977 PMCID: PMC3060976 DOI: 10.2119/molmed.2010.00078] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Accepted: 11/04/2010] [Indexed: 11/06/2022] Open
Abstract
Animal studies have revealed the association between stearoyl-CoA desaturase 1 (SCD1) and obesity and insulin resistance. However, only a few studies have been undertaken in humans. We studied SCD1 in visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) from morbidly obese patients and their association with insulin resistance, sterol regulatory element binding protein-1 (SREBP-1) and ATPase p97, proteins involved in SCD1 synthesis and degradation. The insulin resistance was calculated in 40 morbidly obese patients and 11 overweight controls. Measurements were made of VAT and SAT SCD1, SREBP-1 and ATPase p97 mRNA expression and protein levels. VAT and SAT SCD1 mRNA expression levels in the morbidly obese patients were significantly lower than in the controls (P = 0.006), whereas SCD1 protein levels were significantly higher (P < 0.001). In the morbidly obese patients, the VAT SCD1 protein levels were decreased in patients with higher insulin resistance (P = 0.007). However, SAT SCD1 protein levels were increased in morbidly obese patients with higher insulin resistance (P < 0.05). Multiple linear regressions in the morbidly obese patients showed that the variable associated with the SCD1 protein levels in VAT was insulin resistance, and the variables associated with SCD1 protein levels in SAT were body mass index (BMI) and ATPase p97. In conclusion, these data suggest that the regulation of SCD1 is altered in individuals with morbid obesity and that the SCD1 protein has a different regulation in the two adipose tissues, as well as being closely linked to the degree of insulin resistance.
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Affiliation(s)
| | | | | | | | - Jose M García-Almeida
- Endocrinology and Nutrition Service, Virgen de la Victoria Clinical Hospital, Málaga, Spain
| | - Juan García-Arnés
- Endocrinology and Nutrition Service, Carlos Haya University Hospital, Málaga, Spain
| | - Jose Rivas-Marín
- Surgery Service, Virgen de la Victoria Clinical Hospital, Málaga, Spain
| | | | - Eva García-Escobar
- CIBER Diabetes and Associated Metabolic Disorders (CIBERDEM), ISCIII, Spain
| | - Gemma Rojo-Martinez
- CIBER Diabetes and Associated Metabolic Disorders (CIBERDEM), ISCIII, Spain
- IMABIS Foundation, Málaga, Spain
| | - Francisco Tinahones
- CIBER Physiopathology Obesity and Nutrition (CIBEROBN), ISCIII, Spain
- Endocrinology and Nutrition Service, Virgen de la Victoria Clinical Hospital, Málaga, Spain
| | - Federico Soriguer
- CIBER Diabetes and Associated Metabolic Disorders (CIBERDEM), ISCIII, Spain
- Endocrinology and Nutrition Service, Carlos Haya University Hospital, Málaga, Spain
| | - Manuel Macias-Gonzalez
- IMABIS Foundation, Málaga, Spain
- CIBER Physiopathology Obesity and Nutrition (CIBEROBN), ISCIII, Spain
| | - Eduardo García-Fuentes
- IMABIS Foundation, Málaga, Spain
- CIBER Physiopathology Obesity and Nutrition (CIBEROBN), ISCIII, Spain
- Endocrinology and Nutrition Service, Carlos Haya University Hospital, Málaga, Spain
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53
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Fatty acid bile acid conjugate inhibits hepatic stearoyl coenzyme A desaturase and is non-atherogenic. Arch Med Res 2011; 41:397-404. [PMID: 21044742 DOI: 10.1016/j.arcmed.2010.09.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Accepted: 09/01/2010] [Indexed: 02/08/2023]
Abstract
BACKGROUND AND AIMS Suppression of stearoyl-coenzyme A desaturase (SCD) activity leads to reduction of obesity, fatty liver as well as of insulin resistance. It was, however, recently reported to enhance atherogenesis. The aim of the present study was to investigate whether inhibition of SCD by Aramchol, a fatty acid bile conjugate with known hypocholesterolemic effects, will affect atherogenesis and how. METHODS Aramchol was tested in vitro in cultured cells and in vivo in rodents. RESULTS Aramchol, at very low concentrations, reduced SCD activity in liver microsomes of mice. Aramchol enhanced cholesterol efflux from macrophages more than twofold. In vivo it increased fecal sterol output and decreased markedly plasma cholesterol levels in mice. In ApoE(-/-), LDRL(-/-) and C57Bl6 mice, the effects of Aramchol on atherogenesis were non-atherogenic. CONCLUSIONS Aramchol reduces SCD activity and is non-atherogenic. It may offer a means to obtain the desirable hepatic metabolic effects of SCD inhibition without the deleterious atherogenic effect.
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54
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Peter A, Cegan A, Wagner S, Elcnerova M, Königsrainer A, Königsrainer I, Häring HU, Schleicher ED, Stefan N. Relationships between hepatic stearoyl-CoA desaturase-1 activity and mRNA expression with liver fat content in humans. Am J Physiol Endocrinol Metab 2011; 300:E321-6. [PMID: 21045174 DOI: 10.1152/ajpendo.00306.2010] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Stearoyl-CoA desaturase-1 (SCD1) has gained much interest as a future drug target to treat fatty liver and its consequences. However, there are few and inconsistent human data about expression and activity of this important enzyme. We investigated activity and expression of SCD1 and their relationships with liver fat (LF) content in human liver samples. Fifty subjects undergoing liver surgery were studied. SCD1 activity was estimated from the ratio of oleate (C18:1) to stearate (C18:0) within lipid subfractions. Furthermore, SCD1 mRNA expression and LF content were measured. Similarly to previous studies, we observed a strong positive correlation between LF content and the C18:1/C18:0 ratio in the combined fatty acid (FA) fractions (r = 0.96, P < 0.0001), which could be interpreted as higher SCD1 activity with increasing LF. However, hepatic SCD1 mRNA expression did not correlate with LF (r = 0.16, P = 0.13). To solve these conflicting data, we analyzed the FA composition of hepatic lipid subfractions. With increasing LF content the amount of FAs from the triglyceride (TG) fraction increased (r = 0.96, P < 0.0001), whereas the FAs from the phospholipid (PL) fraction remained unchanged (r = -0.17, P = 0.19). Of these two major lipid fractions, the C18:1/C18:0 ratio in TG was 16-fold higher than in PL. Supporting the SCD1 mRNA expression data, the C18:1/C18:0 ratio of the TG or PL fraction did not correlate with LF (r = 0.26, P = 0.12 and r = 0.08, P = 0.29). We provide novel information that SCD1 activity and mRNA expression appear not to be elevated in subjects with high LF content. We suggest that the FA composition of lipid subclasses, rather than of mixed lipids, should be analyzed to estimate SCD1 activity.
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Affiliation(s)
- Andreas Peter
- Dept. of Internal Medicine, University of Tübingen, German Center for Diabetes Research, Germany.
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55
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A large waist circumference is associated with higher liver fat in healthy pre-menopausal women in the absence of classical biochemical risk factors for CVD. Proc Nutr Soc 2011. [DOI: 10.1017/s0029665111002801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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56
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Mauvoisin D, Mounier C. Hormonal and nutritional regulation of SCD1 gene expression. Biochimie 2011; 93:78-86. [DOI: 10.1016/j.biochi.2010.08.001] [Citation(s) in RCA: 138] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Revised: 07/16/2010] [Accepted: 08/03/2010] [Indexed: 01/08/2023]
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57
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Carpino PA, Goodwin B. Diabetes area participation analysis: a review of companies and targets described in the 2008 – 2010 patent literature. Expert Opin Ther Pat 2010; 20:1627-51. [DOI: 10.1517/13543776.2010.533171] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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58
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2-Aryl benzimidazoles: Human SCD1-specific stearoyl coenzyme-A desaturase inhibitors. Bioorg Med Chem Lett 2010; 20:6366-9. [DOI: 10.1016/j.bmcl.2010.09.094] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 09/14/2010] [Accepted: 09/16/2010] [Indexed: 11/18/2022]
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59
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Pynn CJ, Picardi MV, Nicholson T, Wistuba D, Poets CF, Schleicher E, Perez-Gil J, Bernhard W. Myristate is selectively incorporated into surfactant and decreases dipalmitoylphosphatidylcholine without functional impairment. Am J Physiol Regul Integr Comp Physiol 2010; 299:R1306-16. [DOI: 10.1152/ajpregu.00380.2010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Lung surfactant mainly comprises phosphatidylcholines (PC), together with phosphatidylglycerols and surfactant proteins SP-A to SP-D. Dipalmitoyl-PC (PC16:0/16:0), palmitoylmyristoyl-PC (PC16:0/14:0), and palmitoylpalmitoleoyl-PC (PC16:0/16:1) together comprise 75–80% of surfactant PC. During alveolarization, which occurs postnatally in the rat, PC16:0/14:0 reversibly increases at the expense of PC16:0/16:0. As lipoproteins modify surfactant metabolism, we postulated an extrapulmonary origin of PC16:0/14:0 enrichment in surfactant. We, therefore, fed rats (d19–26) with trilaurin (C12:03), trimyristin (C14:03), tripalmitin (C16:03), triolein (C18:13) or trilinolein (C18:23) vs. carbohydrate diet to assess their effects on surfactant PC composition and surface tension function using a captive bubble surfactometer. Metabolism was assessed with deuterated C12:0 (ω-d3-C12:0) and ω-d3-C14:0. C14:03 increased PC16:0/14:0 in surfactant from 12 ± 1 to 45 ± 3% and decreased PC16:0/16:0 from 47 ± 1 to 29 ± 2%, with no impairment of surface tension function. Combined phospholipase A2 assay and mass spectrometry revealed that 50% of the PC16:0/14:0 peak comprised its isomer 1-myristoyl-2-palmitoyl-PC (PC14:0/16:0). While C12:03 was excluded from incorporation into PC, it increased PC16:0/14:0 as well. C16:03, C18:13, and C18:23 had no significant effect on PC16:0/16:0 or PC16:0/14:0. d3-C14:0 was enriched in lung PC, either via direct supply or via d3-C12:0 elongation. Enrichment of d3-C14:0 in surfactant PC contrasted its rapid turnover in plasma and liver PC, where its elongation product d3-C16:0 surmounted d3-C14:0. In summary, high surfactant PC16:0/14:0 during lung development correlates with C14:0 and C12:0 supply via specific C14:0 enrichment into lung PC. Surfactant that is high in PC16:0/14:0 but low in PC16:0/16:0 is compatible with normal respiration and surfactant function in vitro.
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Affiliation(s)
- Christopher J. Pynn
- Departments of 1Neonatology and
- Internal Medicine IV, Faculty of Medicine, and
| | - M. Victoria Picardi
- Department of Bioquimica y Biologia Molecular, Universidad Complutense, Madrid, Spain
| | - Tim Nicholson
- Department of Chemistry, Eberhard-Karls-University, Tübingen, Germany; and
| | - Dorothee Wistuba
- Department of Chemistry, Eberhard-Karls-University, Tübingen, Germany; and
| | | | | | - Jesus Perez-Gil
- Department of Bioquimica y Biologia Molecular, Universidad Complutense, Madrid, Spain
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Abstract
PURPOSE OF REVIEW This review aims to address the latest research on hepatic desaturases and metabolic disorders, with focus on stearoyl-CoA desaturase-1 (SCD-1) indices in observational studies. RECENT FINDINGS In animal studies, SCD-1 inhibition protects against features of the metabolic syndrome and is associated with improved hepatic insulin resistance and decreased steatosis. In human observational studies, higher estimated hepatic SCD-1 and Δ6-desaturase activities predict the metabolic syndrome, insulin resistance and mortality whereas Δ5-desaturase index is often inversely related. However, because the desaturase activities in the liver and adipose tissue may not be regulated in parallel, it is important to define used lipid fractions when comparing studies. It is also important to take the background diets of the populations into account when comparing studies. Moreover, there may be a divergence in desaturase regulation depending on glycaemic control among individuals. SUMMARY Increased SCD-1 indices reflecting liver desaturase activity have been associated with insulin resistance, fatty liver, the metabolic syndrome and mortality. However, it remains to be determined if high hepatic SCD-1 activity plays a direct role in the development of metabolic disorders or rather is a marker for an unfavourable diet or hepatic insulin resistance.
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Affiliation(s)
- Helena Bjermo
- Department of Public Health and Caring Sciences, Clinical Nutrition and Metabolism, Uppsala University, Uppsala, Sweden
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Zhao X, Fritsche J, Wang J, Chen J, Rittig K, Schmitt-Kopplin P, Fritsche A, Häring HU, Schleicher ED, Xu G, Lehmann R. Metabonomic fingerprints of fasting plasma and spot urine reveal human pre-diabetic metabolic traits. Metabolomics 2010; 6:362-374. [PMID: 20676218 PMCID: PMC2899018 DOI: 10.1007/s11306-010-0203-1] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Accepted: 02/17/2010] [Indexed: 12/17/2022]
Abstract
Impaired glucose tolerance (IGT) which precedes overt type 2 diabetes (T2DM) for decades is associated with multiple metabolic alterations in insulin sensitive tissues. In an UPLC-qTOF-mass spectrometry-driven non-targeted metabonomics approach we investigated plasma as well as spot urine of 51 non-diabetic, overnight fasted individuals aiming to separate subjects with IGT from controls thereby identify pathways affected by the pre-diabetic metabolic state. We could clearly demonstrate that normal glucose tolerant (NGT) and IGT subjects clustered in two distinct groups independent of the investigated metabonome. These findings reflect considerable differences in individual metabolite fingerprints, both in plasma and urine. Pre-diabetes associated alterations in fatty acid-, tryptophan-, uric acid-, bile acid-, and lysophosphatidylcholine-metabolism, as well as the TCA cycle were identified. Of note, individuals with IGT also showed decreased levels of gut flora-associated metabolites namely hippuric acid, methylxanthine, methyluric acid, and 3-hydroxyhippuric acid. The findings of our non-targeted UPLC-qTOF-MS metabonomics analysis in plasma and spot urine of individuals with IGT vs NGT offers novel insights into the metabolic alterations occurring in the long, asymptomatic period preceding the manifestation of T2DM thereby giving prospects for new intervention targets. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11306-010-0203-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Xinjie Zhao
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, The Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, 116023 China
| | - Jens Fritsche
- Immatics Biotechnologies GmbH, 72076 Tuebingen, Germany
| | - Jiangshan Wang
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, The Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, 116023 China
| | - Jing Chen
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, The Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, 116023 China
| | - Kilian Rittig
- Department of Internal Medicine 4, University Hospital Tuebingen, 72076 Tuebingen, Germany
| | - Philippe Schmitt-Kopplin
- Institute for Ecological Chemistry, Helmholtz-Zentrum Muenchen—German Research Center for Environmental Health, Ingoldstaedter Landstraße 1, 85764 Neuherberg, Germany
| | - Andreas Fritsche
- Department of Internal Medicine 4, University Hospital Tuebingen, 72076 Tuebingen, Germany
| | - Hans-Ulrich Häring
- Department of Internal Medicine 4, University Hospital Tuebingen, 72076 Tuebingen, Germany
| | - Erwin D. Schleicher
- Division of Clinical Chemistry and Pathobiochemistry, Central Laboratory, University Hospital Tuebingen, Otfried-Mueller-Str. 10, 72076 Tuebingen, Germany
| | - Guowang Xu
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, The Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, 116023 China
| | - Rainer Lehmann
- Division of Clinical Chemistry and Pathobiochemistry, Central Laboratory, University Hospital Tuebingen, Otfried-Mueller-Str. 10, 72076 Tuebingen, Germany
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A polyphenol extract modifies quantity but not quality of liver fatty acid content in high-fat-high-sucrose diet-fed rats: possible implication of the sirtuin pathway. Br J Nutr 2010; 104:1760-70. [PMID: 20673376 DOI: 10.1017/s0007114510002850] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
High-fat or high-fat-high-sucrose diets are known to induce non-alcoholic fatty liver disease and this is emerging as one of the most common liver diseases worldwide. Some polyphenols have been reported to decrease rat hepatic lipid accumulation, in particular those extracted from red grapes such as resveratrol. The present study was designed to determine whether a polyphenol extract (PPE), from red grapes, modulates liver fatty acid composition and desaturase activity indexes in rats fed a high-fat-high-sucrose (HFHS) diet, and to explore whether sirtuin-1 deacetylase activation was implicated in the effect of the PPE against liver steatosis. The effect of this PPE on mitochondriogenesis and mitochondrial activity was also explored. The PPE decreased liver TAG content in HFHS+PPE diet-fed rats in comparison with HFHS diet-fed rats. The PPE had no effect on liver fatty acid composition, desaturase activity indexes and stearoyl-CoA desaturase 1 (SCD1) gene expression. Sirtuin-1 deacetylase protein expression was significantly increased with the PPE; AMP kinase protein expression was higher with the PPE in comparison with the HFHS rats, but no modification of phosphorylated AMP kinase was observed. Protein expression of phospho-acetyl-CoA carboxylase was decreased in HFHS rats and returned to basal values with the PPE. Finally, the PPE modulated PPARγ coactivator-1α (PGC-1α) but did not modify mitochondriogenesis and mitochondrial activity. In conclusion, the PPE partially prevented the accumulation of TAG in the liver by regulating acetyl-CoA carboxylase phosphorylation, a key enzyme in lipid metabolism, probably via sirtuin-1 deacetylase activation. However, the PPE had no effect on the qualitative composition of liver fatty acids.
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63
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Candidate gene markers involved in San Daniele ham quality. Meat Sci 2010; 85:441-5. [DOI: 10.1016/j.meatsci.2010.02.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Revised: 02/08/2010] [Accepted: 02/10/2010] [Indexed: 11/19/2022]
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Springer F, Machann J, Claussen CD, Schick F, Schwenzer NF. Liver fat content determined by magnetic resonance imaging and spectroscopy. World J Gastroenterol 2010; 16:1560-6. [PMID: 20355234 PMCID: PMC2848364 DOI: 10.3748/wjg.v16.i13.1560] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Hepatic steatosis as the most prevalent liver disorder can either be related to alcoholic liver disease (ALD) or non-alcoholic fatty liver disease (NAFLD). In both conditions, hepatocytes excessively accumulate fat-containing vacuoles within their cytoplasm, which is the key histological feature. In contrast to ALD, NAFLD is commonly associated with metabolic syndrome, obesity and insulin resistance. To determine increased liver fat content, liver biopsy is currently considered the gold standard. Besides the invasive technique, various other non-invasive techniques have been developed, such as ultrasound, computed tomography (CT), magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI) based methods. Among these techniques, ultrasound and CT provide only qualitative information about hepatic steatosis, whereas MRS- or MRI-based methods are able to determine even small amounts of fat accurately. These non-invasive magnetic resonance techniques have already proven their great potential, especially in longitudinal and cross-sectional studies regarding various metabolic conditions and medical treatment regimens. In this review, the most common, non-invasive MRS/MRI techniques for assessment of intrahepatic lipid content are described with their inherent advantages and limitations.
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65
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Abstract
It is well established that the development of NAFLD and NASH are closely linked to an excess flow of free fatty acids (FFA) arising from dysfunctional/insulin resistant adipose tissue causing ectopic fat deposition in many organs. In the liver, when chronic lipid supply surpasses the metabolic ability to adapt it will induce hepatocellular damage as FFA are redirected into harmful pathways of non-oxidative metabolism with intracellular accumulation of toxic lipid-derived metabolites. Multiple mechanisms have been implicated including mitochondrial dysfunction, endoplasmic reticulum stress, and activation of multiple inflammatory pathways. Understanding the role of insulin resistance and lipotoxicity in NASH as part of a broader metabolic disorder is likely to assist practitioners in the successful management of these challenging patients.
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Affiliation(s)
- Kenneth Cusi
- Diabetes Division, The University of Texas Health Science Center at San Antonio, Room 3.380S, 7703 Floyd Curl Drive, San Antonio, TX 78284-3900, USA.
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66
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Abstract
BACKGROUND Stearoyl-CoA desaturase 1 (SCD1) has been implicated as a novel therapeutic target for the treatment of a variety of disease states, including hepatic steatosis, metabolic diseases, skin and eye disorders, and certain cancers. OBJECTIVE/METHOD This review focuses on the novel composition of matter patents in the area of small molecule SCD1 inhibitors, along with their pharmacological effects in relevant disease models. The prospect of targeting SCD1 inhibition as a novel therapeutic approach is discussed. CONCLUSION The rapid development of SCD1 inhibitors is evidenced by the increasing number of patent applications published and the number of promising preclinical compounds that have emerged in the past 5 years. Between January 2005 and February 2009, there were approximately 70 SCD1 inhibitor patent applications published.
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Affiliation(s)
- Gang Liu
- Ambit Biosciences, 4215 Sorrento Valley Blvd, San Diego, CA 92121, USA.
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67
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Flowers MT. The delta9 fatty acid desaturation index as a predictor of metabolic disease. Clin Chem 2009; 55:2071-3. [PMID: 19850628 DOI: 10.1373/clinchem.2009.135152] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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68
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Peter A, Cegan A, Wagner S, Lehmann R, Stefan N, Königsrainer A, Königsrainer I, Häring HU, Schleicher E. Hepatic lipid composition and stearoyl-coenzyme A desaturase 1 mRNA expression can be estimated from plasma VLDL fatty acid ratios. Clin Chem 2009; 55:2113-20. [PMID: 19850634 DOI: 10.1373/clinchem.2009.127274] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Stearoyl-coenzyme A desaturase 1 (SCD1) catalyzes the limiting step of monounsaturated fatty acid synthesis in humans and is an important player in triglyceride generation. SCD1 has been repeatedly implicated in the pathogenesis of metabolic and inflammatory diseases. Therefore it is of great importance to determine SCD1 activity in human samples. In this study we aimed to evaluate a hepatic SCD1 activity index derived from plasma VLDL triglyceride composition as a tool to estimate hepatic SCD1 expression in humans. Additionally, we further evaluated commonly used fatty acid ratios [elongase, de novo lipogenesis, and Delta5 and Delta6 desaturase] in plasma VLDL and hepatic lipid fractions. DESIGN AND METHODS Liver biopsies and plasma samples were simultaneously collected from 15 individuals. Plasma VLDL was obtained by ultracentrifugation. Hepatic and plasma VLDL lipids were fractionated by thin-layer chromatography, and the fatty acid composition of each fraction was analyzed by gas chromatography. Hepatic SCD1 expression was determined by real-time PCR. RESULTS Hepatic SCD1 mRNA expression was associated with the product/precursor ratios (16:1/16:0 and 18:1/18:0) of hepatic lipid fractions. The 16:1/16:0 ratio in hepatic and VLDL triglycerides as well as the 18:1/18:0 ratio in plasma VLDL were closely associated with hepatic SCD1 expression. The hepatic de novo lipogenesis index from triglycerides was associated with expression of lipogenic genes [fatty acid synthase (FASN), acetyl-Coenzyme A carboxylase alpha (ACACA), and sterol regulatory element binding transcription factor 1 (SREBP-1)] and is closely reflected by the de novo lipogenesis index in VLDL triglycerides. CONCLUSION We demonstrated for the first time that hepatic SCD1 expression can be estimated noninvasively from routine blood samples by measuring the SCD1 activity index in fasting plasma VLDL.
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Affiliation(s)
- Andreas Peter
- Department of Internal Medicine, Division of Endocrinology, Diabetology, Vascular Medicine, Nephrology and Clinical Chemistry, University of Tübingen, Tübingen Germany.
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Schwenzer NF, Springer F, Schraml C, Stefan N, Machann J, Schick F. Non-invasive assessment and quantification of liver steatosis by ultrasound, computed tomography and magnetic resonance. J Hepatol 2009; 51:433-45. [PMID: 19604596 DOI: 10.1016/j.jhep.2009.05.023] [Citation(s) in RCA: 528] [Impact Index Per Article: 35.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Hepatic steatosis is the most prevalent liver disorder in the developed world. It is closely associated with features of metabolic syndrome, especially insulin resistance and obesity. The two most common conditions associated with fatty liver are alcoholic liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD). Liver biopsy is considered the gold standard for the assessment of liver fat, but there is a need for less invasive diagnostic techniques. New imaging modalities are emerging, which could provide more detailed information about hepatic tissue or even replace biopsy. In the present review, available imaging modalities (ultrasound, computed tomography, magnetic resonance imaging and proton magnetic resonance spectroscopy) are presented which are employed to detect or even quantify the fat content of the liver. The advantages and disadvantages of the above-mentioned imaging modalities are discussed. Although none of these techniques is able to differentiate between microvesicular and macrovesicular steatosis and to reveal all features visible using histology, the proposed diagnostic modalities offer a wide range of additional information such as anatomical and morphological information non-invasively. In particular, magnetic resonance imaging and proton magnetic resonance spectroscopy are able to quantify the hepatic fat content hence avoiding exposure to radiation. Except for proton magnetic resonance spectroscopy, all modalities offer additional information about regional fat distribution within the liver. MR elastography, which can estimate the amount of fibrosis, also appears promising in the differentiation between simple steatosis and steatohepatitis.
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Affiliation(s)
- Nina F Schwenzer
- Section on Experimental Radiology, Department of Diagnostic and Interventional Radiology, Eberhard-Karls University, 72076 Tübingen, Germany
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Peter A, Weigert C, Staiger H, Machicao F, Schick F, Machann J, Stefan N, Thamer C, Häring HU, Schleicher E. Individual stearoyl-coa desaturase 1 expression modulates endoplasmic reticulum stress and inflammation in human myotubes and is associated with skeletal muscle lipid storage and insulin sensitivity in vivo. Diabetes 2009; 58:1757-65. [PMID: 19478146 PMCID: PMC2712792 DOI: 10.2337/db09-0188] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVE Increased plasma levels of free fatty acids occur in obesity and type 2 diabetes and contribute to the development of insulin resistance. Saturated fatty acids (SFAs) such as palmitate especially have lipotoxic effects leading to endoplasmatic reticulum (ER) stress, inflammation, and insulin resistance. Stearoyl-CoA desaturase 1 (SCD1) plays a key role in preventing lipotoxic effects, as it converts SFAs to less harmful monounsaturated fatty acids. Here, we tested the hypothesis that individual differences in the regulation of SCD1 expression by palmitate exist and influence insulin sensitivity and the cellular response to palmitate. RESEARCH DESIGN AND METHODS Palmitate-induced gene expression was studied in primary human myotubes of 39 metabolically characterized individuals, as well as in an SCD1-overexpressing cell culture model. RESULTS SCD1 mRNA expression and inducibility by palmitate in cultured myotubes showed a broad interindividual variation, presumably due to inheritable characteristics of the donors. Overexpression of SCD1 prevented the inflammatory and ER stress response to palmitate exposure. In primary human myotubes, high SCD1 inducibility was associated with a low inflammatory (interleukin [IL]-6, IL-8, and chemokine [CXC motif] ligand 3 [CXCL3]) and ER stress (CCAAT/enhancer binding protein [C/EBP] homologous protein, activating transcription factor 3 [ATF3], and X-box binding protein 1 [XBP1]) response to palmitate exposure. Finally, palmitate-stimulated SCD1 mRNA expression, positively correlated with intramyocellular lipid (IMCL) content of the donors, was measured by (1)H-magnetic resonance spectroscopy. After adjustment for IMCL, SCD1 expression and inducibility were positively correlated with insulin sensitivity. CONCLUSIONS We hypothesize that myocellular SCD1 inducibility by palmitate is an individual characteristic that modulates lipid storage, palmitate-induced inflammation, ER stress, and insulin resistance. This may describe individuals with increased capability of innoxious free fatty acid handling and benign triglyceride storage.
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Affiliation(s)
- Andreas Peter
- Department of Internal Medicine, Division of Endocrinology, Diabetology, Vascular Medicine, Nephrology, and Clinical Chemistry, University of Tübingen, Tübingen, Germany.
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Pineau L, Colas J, Dupont S, Beney L, Fleurat-Lessard P, Berjeaud JM, Bergès T, Ferreira T. Lipid-Induced ER Stress: Synergistic Effects of Sterols and Saturated Fatty Acids. Traffic 2009; 10:673-90. [DOI: 10.1111/j.1600-0854.2009.00903.x] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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72
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Liu G. Azacycloalkane derivatives as inhibitors of delta-9 stearoyl-coenzyme A desaturase. Expert Opin Ther Pat 2009; 19:885-91. [DOI: 10.1517/13543770902755145] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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73
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Abstract
PURPOSE OF REVIEW To increase awareness about the close interrelationship between nonalcoholic fatty liver disease and type 2 diabetes mellitus, and of recent diagnostic and treatment advances in the field. RECENT FINDINGS The perception of nonalcoholic fatty liver disease as an uncommon and benign condition is rapidly changing. Approximately 70% of persons with type 2 diabetes mellitus have a fatty liver and the disease follows a more aggressive course with necroinflammation and fibrosis (i.e. nonalcoholic steatohepatitis) in diabetes. New evidence suggests that it is not steatosis per se but the development of lipotoxicity-induced mitochondrial dysfunction and activation of inflammatory pathways that leads to progressive liver damage. Nonalcoholic steatohepatitis is a leading cause of end-stage liver disease and contributes to cardiovascular disease in patients with type 2 diabetes mellitus. Because nonalcoholic steatohepatitis may develop even in the presence of normal liver transaminases, a liver biopsy is still necessary for a definitive diagnosis. However, new imaging methods and plasma biomarkers are emerging as alternative diagnostic tools. Lifestyle intervention is the gold standard for the management of nonalcoholic steatohepatitis. Recent randomized controlled trials suggest thiazolidiendiones are promising therapeutic agents. SUMMARY Nonalcoholic steatohepatitis is a frequently overlooked and potentially severe complication of type 2 diabetes mellitus. Patients may benefit from its early diagnosis and treatment.
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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 78284-3900, USA.
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Zhao X, Peter A, Fritsche J, Elcnerova M, Fritsche A, Häring HU, Schleicher ED, Xu G, Lehmann R. Changes of the plasma metabolome during an oral glucose tolerance test: is there more than glucose to look at? Am J Physiol Endocrinol Metab 2009; 296:E384-93. [PMID: 19066319 DOI: 10.1152/ajpendo.90748.2008] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The oral glucose tolerance test (oGTT) is a common tool to provoke a metabolic challenge for scientific purposes, as well as for diagnostic reasons, to monitor the kinetics of glucose and insulin. Here, we aimed to follow the variety of physiological changes of the whole metabolic pattern in plasma during an oGTT in healthy subjects in a nontargeted reversed-phase ultra performance liquid chromatography coupled to electrospray ionization quadrupole time of flight mass spectrometric metabolomics approach. We detected 11,500 metabolite ion masses/individual. Applying multivariate data analysis, four major groups of metabolites have been detected as the most discriminating oGTT biomarkers: free fatty acids (FFA), acylcarnitines, bile acids, and lysophosphatidylcholines. We found in detail 1) a strong decrease of all saturated and monounsaturated FFA studied during the oGTT; 2) a significant faster decline of palmitoleate (C16:1) and oleate (C18:1) FFA levels than their saturated counterparts; 3) a strong relative increase of polyunsaturated fatty acids in the fatty acid pattern at 120 min; and 4) a clear decrease in plasma C10:0, C12:0, and C14:1 acylcarnitine levels. These data reflect the switch from beta-oxidation to glycolysis and fat storage during the oGTT. Moreover, the bile acids glycocholic acid, glycochenodeoxycholic acid, and glycodeoxycholic acid were highly discriminative, showing a biphasic kinetic with a maximum of a 4.5- to 6-fold increase at 30 min after glucose ingestion, a significant decrease over the next 60 min followed by an increase until the end of the oGTT. Lysophosphatidylcholines were also increased significantly. The findings of our metabolomics study reveal detailed insights in the complex physiological regulation of the metabolism during an oGTT offering novel perspectives of this widely used procedure.
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Affiliation(s)
- Xinjie Zhao
- Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
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