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Application of an In Vivo Hepatic Triacylglycerol Production Method in the Setting of a High-Fat Diet in Mice. Nutrients 2016; 9:nu9010016. [PMID: 28036028 PMCID: PMC5295060 DOI: 10.3390/nu9010016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 12/02/2016] [Accepted: 12/21/2016] [Indexed: 12/21/2022] Open
Abstract
High-fat (HF) diets typically promote diet-induced obesity (DIO) and metabolic dysfunction (i.e., insulin resistance, hypertriglyceridemia, and hepatic steatosis). Dysfunction of triacylglycerol (TAG) metabolism may contribute to the development of hepatic steatosis, via increased de novo lipogenesis or repackaging of circulating nonesterified fatty acids (NEFAs). Hepatic TAG production (HTP) rate can be assessed through injecting mice with nonionic detergents that inhibit tissue lipoprotein lipase. Potential confounding effects of detergent-based HTP tests (HTPTs) used in longitudinal studies—including the impact on food intake, energy balance, and weight gain—have not been reported. To examine this, male C57BL/6J mice were fed a 10% or 60% kcal diet. After 4 weeks, the mice underwent an HTPT via poloxamer 407 intraperitoneal injections (1000 mg/kg). Weight gain, energy intake, and postabsorptive TAG levels normalized 7–10 days post-HTPT. The post-HTPT recovery of body weight and energy intake suggest that, in metabolic phenotyping studies, any additional sample collection should occur at least 7–10 days after the HTPT to reduce confounding effects. Diet-specific effects on HTP were also observed: HF-fed mice had reduced HTP, plasma TAG, and NEFA levels compared to controls. In conclusion, the current study highlights the procedural and physiological complexities associated with studying lipid metabolism using a HTPT in the DIO mouse model.
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202
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Marti AR, Meerlo P, Grønli J, van Hasselt SJ, Mrdalj J, Pallesen S, Pedersen TT, Henriksen TEG, Skrede S. Shift in Food Intake and Changes in Metabolic Regulation and Gene Expression during Simulated Night-Shift Work: A Rat Model. Nutrients 2016; 8:nu8110712. [PMID: 27834804 PMCID: PMC5133098 DOI: 10.3390/nu8110712] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 10/25/2016] [Accepted: 10/28/2016] [Indexed: 12/22/2022] Open
Abstract
Night-shift work is linked to a shift in food intake toward the normal sleeping period, and to metabolic disturbance. We applied a rat model of night-shift work to assess the immediate effects of such a shift in food intake on metabolism. Male Wistar rats were subjected to 8 h of forced activity during their rest (ZT2-10) or active (ZT14-22) phase. Food intake, body weight, and body temperature were monitored across four work days and eight recovery days. Food intake gradually shifted toward rest-work hours, stabilizing on work day three. A subgroup of animals was euthanized after the third work session for analysis of metabolic gene expression in the liver by real-time polymerase chain reaction (PCR). Results show that work in the rest phase shifted food intake to rest-work hours. Moreover, liver genes related to energy storage and insulin metabolism were upregulated, and genes related to energy breakdown were downregulated compared to non-working time-matched controls. Both working groups lost weight during the protocol and regained weight during recovery, but animals that worked in the rest phase did not fully recover, even after eight days of recovery. In conclusion, three to four days of work in the rest phase is sufficient to induce disruption of several metabolic parameters, which requires more than eight days for full recovery.
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Affiliation(s)
- Andrea Rørvik Marti
- Department of Biological and Medical Psychology, University of Bergen, Bergen 5009, Norway.
| | - Peter Meerlo
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, 9700 CC Groningen, The Netherlands.
| | - Janne Grønli
- Department of Biological and Medical Psychology, University of Bergen, Bergen 5009, Norway.
- College of Medical Sciences, Washington State University, Spokane, WA 99210, USA.
- Sleep and Performance Research Center, Washington State University, Spokane, WA 99210, USA.
| | - Sjoerd Johan van Hasselt
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, 9700 CC Groningen, The Netherlands.
| | - Jelena Mrdalj
- Department of Biological and Medical Psychology, University of Bergen, Bergen 5009, Norway.
- Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, Bergen 5021, Norway.
| | - Ståle Pallesen
- Department of Psychosocial Science, University of Bergen, Bergen 5015, Norway.
- Section of Psychiatry, Department of Clinical Medicine, Faculty of Medicine and Dentistry, University of Bergen, Bergen 5021, Norway.
| | - Torhild Thue Pedersen
- Department of Biological and Medical Psychology, University of Bergen, Bergen 5009, Norway.
| | - Tone Elise Gjøtterud Henriksen
- Section of Psychiatry, Department of Clinical Medicine, Faculty of Medicine and Dentistry, University of Bergen, Bergen 5021, Norway.
- Division of Mental Health Care, Valen Hospital, Fonna Local Health Authority, Valen 5451, Norway.
| | - Silje Skrede
- Dr. Einar Martens Research Group for Biological Psychiatry, Center for Medical Genetics and Molecular Medicine, Haukeland Univeristy Hospital, 5021 Bergen, Norway.
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203
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Angeles TS, Hudkins RL. Recent advances in targeting the fatty acid biosynthetic pathway using fatty acid synthase inhibitors. Expert Opin Drug Discov 2016; 11:1187-1199. [PMID: 27701891 DOI: 10.1080/17460441.2016.1245286] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
INTRODUCTION Elevated lipogenesis has been associated with a variety of diseases including obesity, cancer and nonalcoholic fatty liver disease (NAFLD). Fatty acid synthase (FASN) plays a pivotal role in de novo lipogenesis, making this multi-catalytic protein an attractive target for therapeutic intervention. Recently, the first FASN inhibitor successfully advanced through the drug development process and entered clinical evaluation in oncology. Areas covered: This review discusses the biological roles of FASN in three prominent disease areas: cancer, obesity-related disorders and NAFLD. Recent advances in drug discovery strategies and design of newer FASN inhibitors are also highlighted. Expert opinion: Despite the abundance of evidence linking the lipogenic pathway to cancer, progression of FASN-targeted molecules has been rather slow and challenging and no compounds have moved past the preclinical phase. The landscape has recently changed with the recent advancement of the first FASN inhibitor into clinical evaluation for solid tumors. Needless to say, the successful translation into the clinical setting will open opportunities for expanding the therapeutic utility of FASN inhibitors not just in oncology but in other diseases associated with elevated lipogenesis such as obesity, type 2 diabetes, and NAFLD.
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Affiliation(s)
- Thelma S Angeles
- a Discovery and Product Development , Teva Branded Pharmaceutical Products R&D, Inc ., West Chester , PA , USA
| | - Robert L Hudkins
- a Discovery and Product Development , Teva Branded Pharmaceutical Products R&D, Inc ., West Chester , PA , USA
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204
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Hepatic Deletion of Janus Kinase 2 Counteracts Oxidative Stress in Mice. Sci Rep 2016; 6:34719. [PMID: 27713471 PMCID: PMC5054456 DOI: 10.1038/srep34719] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 09/19/2016] [Indexed: 12/13/2022] Open
Abstract
Genetic deletion of the tyrosine kinase JAK2 or the downstream transcription factor STAT5 in liver impairs growth hormone (GH) signalling and thereby promotes fatty liver disease. Hepatic STAT5 deficiency accelerates liver tumourigenesis in presence of high GH levels. To determine whether the upstream kinase JAK2 exerts similar functions, we crossed mice harbouring a hepatocyte-specific deletion of JAK2 (JAK2Δhep) to GH transgenic mice (GHtg) and compared them to GHtgSTAT5Δhep mice. Similar to GHtgSTAT5Δhep mice, JAK2 deficiency resulted in severe steatosis in the GHtg background. However, in contrast to STAT5 deficiency, loss of JAK2 significantly delayed liver tumourigenesis. This was attributed to: (i) activation of STAT3 in STAT5-deficient mice, which was prevented by JAK2 deficiency and (ii) increased detoxification capacity of JAK2-deficient livers, which diminished oxidative damage as compared to GHtgSTAT5Δhep mice, despite equally severe steatosis and reactive oxygen species (ROS) production. The reduced oxidative damage in JAK2-deficient livers was linked to increased expression and activity of glutathione S-transferases (GSTs). Consistent with genetic deletion of Jak2, pharmacological inhibition and siRNA-mediated knockdown of Jak2 led to significant upregulation of Gst isoforms and to reduced hepatic oxidative DNA damage. Therefore, blocking JAK2 function increases detoxifying GSTs in hepatocytes and protects against oxidative liver damage.
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205
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Chikamoto K, Misu H, Takayama H, Kikuchi A, Ishii KA, Lan F, Takata N, Tajima-Shirasaki N, Takeshita Y, Tsugane H, Kaneko S, Matsugo S, Takamura T. Rapid response of the steatosis-sensing hepatokine LECT2 during diet-induced weight cycling in mice. Biochem Biophys Res Commun 2016; 478:1310-6. [DOI: 10.1016/j.bbrc.2016.08.117] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 08/20/2016] [Indexed: 10/21/2022]
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206
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C13orf31 (FAMIN) is a central regulator of immunometabolic function. Nat Immunol 2016; 17:1046-56. [PMID: 27478939 DOI: 10.1038/ni.3532] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 07/01/2016] [Indexed: 12/15/2022]
Abstract
Single-nucleotide variations in C13orf31 (LACC1) that encode p.C284R and p.I254V in a protein of unknown function (called 'FAMIN' here) are associated with increased risk for systemic juvenile idiopathic arthritis, leprosy and Crohn's disease. Here we set out to identify the biological mechanism affected by these coding variations. FAMIN formed a complex with fatty acid synthase (FASN) on peroxisomes and promoted flux through de novo lipogenesis to concomitantly drive high levels of fatty-acid oxidation (FAO) and glycolysis and, consequently, ATP regeneration. FAMIN-dependent FAO controlled inflammasome activation, mitochondrial and NADPH-oxidase-dependent production of reactive oxygen species (ROS), and the bactericidal activity of macrophages. As p.I254V and p.C284R resulted in diminished function and loss of function, respectively, FAMIN determined resilience to endotoxin shock. Thus, we have identified a central regulator of the metabolic function and bioenergetic state of macrophages that is under evolutionary selection and determines the risk of inflammatory and infectious disease.
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207
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Hu W, Mai KS, Luo Z, Zheng JL, Huang C, Pan YX. Effect of waterborne zinc exposure on lipid deposition and metabolism in hepatopancreas and muscle of grass carp Ctenopharyngodon idella. FISH PHYSIOLOGY AND BIOCHEMISTRY 2016; 42:1093-1105. [PMID: 26820140 DOI: 10.1007/s10695-016-0200-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 01/14/2016] [Indexed: 06/05/2023]
Abstract
The aim of the present study was to explore the effect of waterborne zinc (control, 0.85, 2.20, 3.10 mg/l, respectively) exposure on lipid deposition and metabolism in the hepatopancreas and muscle of grass carp Ctenopharyngodon idella. The lipid content, Zn accumulation, and the activities and expression levels of several enzymes involved in lipid metabolism were determined in hepatopancreas and muscle. Waterborne Zn exposure reduced growth performance and increased Zn accumulation in both tested tissues. In hepatopancreas, Zn exposure increased lipid content, the activities of lipogenic enzymes, such as 6PGD, G6PD, ME, ICDH and FAS, as well as the mRNA expression level of G6PD, 6PGD, ICDH, FAS and SREBP-1. But the activity of CPT I and the mRNA expression of HSL, CPT Iα1a, CPT Iα2a and PPARα were down-regulated by Zn exposure. In contrast, in muscle, waterborne Zn exposure decreased lipid deposition, activities of 6GPD, ICDH and ME, as well as the mRNA expression level of G6PD, ICDH, ME, FAS and SREBP-1. However, the activity of CPT I as well as the mRNA expression level of PPARα, HSL, CPT Iα2a, CPT Iα1b and CPT Iβ were up-regulated by Zn exposure. Our results indicate that waterborne Zn increases lipid content by up-regulating lipogenesis and down-regulating lipolysis in hepatopancreas. But, in muscle, waterborne Zn reduces lipid accumulation by up-regulating lipolysis and down-regulating lipogenesis. Differential patterns of lipid deposition, enzymatic activities and genes' expression indicate the tissue-specific regulatory mechanism in fish.
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Affiliation(s)
- Wei Hu
- Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture of P.R.C., Fishery College, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
- Freshwater Aquaculture Collaborative Innovative Centre of Hubei Province, Wuhan, 430070, People's Republic of China
| | - Kang-Sen Mai
- College of Fisheries, Ocean University of China, Qingdao, 266003, People's Republic of China
| | - Zhi Luo
- Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture of P.R.C., Fishery College, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China.
- Freshwater Aquaculture Collaborative Innovative Centre of Hubei Province, Wuhan, 430070, People's Republic of China.
| | - Jia-Lang Zheng
- Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture of P.R.C., Fishery College, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
- Freshwater Aquaculture Collaborative Innovative Centre of Hubei Province, Wuhan, 430070, People's Republic of China
| | - Chao Huang
- Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture of P.R.C., Fishery College, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
- Freshwater Aquaculture Collaborative Innovative Centre of Hubei Province, Wuhan, 430070, People's Republic of China
| | - Ya-Xiong Pan
- Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture of P.R.C., Fishery College, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
- Freshwater Aquaculture Collaborative Innovative Centre of Hubei Province, Wuhan, 430070, People's Republic of China
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208
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Karahashi M, Hirata-Hanta Y, Kawabata K, Tsutsumi D, Kametani M, Takamatsu N, Sakamoto T, Yamazaki T, Asano S, Mitsumoto A, Kawashima Y, Kudo N. Abnormalities in the Metabolism of Fatty Acids and Triacylglycerols in the Liver of the Goto-Kakizaki Rat: A Model for Non-Obese Type 2 Diabetes. Lipids 2016; 51:955-71. [PMID: 27372943 DOI: 10.1007/s11745-016-4171-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 06/20/2016] [Indexed: 02/08/2023]
Abstract
The Goto-Kakizaki (GK) rat is widely used as an animal model for spontaneous-onset type 2 diabetes without obesity; nevertheless, little information is available on the metabolism of fatty acids and triacylglycerols (TAG) in their livers. We investigated the mechanisms underlying the alterations in the metabolism of fatty acids and TAG in their livers, in comparison with Zucker (fa/fa) rats, which are obese and insulin resistant. Lipid profiles, the expression of genes for enzymes and proteins related to the metabolism of fatty acid and TAG, de novo synthesis of fatty acids and TAG in vivo, fatty acid synthase activity in vitro, fatty acid oxidation in liver slices, and very-low-density-lipoprotein (VLDL)-TAG secretion in vivo were estimated. Our results revealed that (1) the TAG accumulation was moderate, (2) the de novo fatty acid synthesis was increased by upregulation of fatty acid synthase in a post-transcriptional manner, (3) fatty acid oxidation was also augmented through the induction of carnitine palmitoyltransferase 1a, and (4) the secretion rate of VLDL-TAG remained unchanged in the livers of GK rats. These results suggest that, despite the fact that GK rats exhibit non-obese type 2 diabetes, the upregulation of de novo lipogenesis is largely compensated by the upregulation of fatty acid oxidation, resulting in only moderate increase in TAG accumulation in the liver.
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Affiliation(s)
- Minako Karahashi
- School of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama, 350-0295, Japan
| | - Yuko Hirata-Hanta
- School of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama, 350-0295, Japan
| | - Kohei Kawabata
- School of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama, 350-0295, Japan
| | - Daisuke Tsutsumi
- School of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama, 350-0295, Japan
| | - Misaki Kametani
- School of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama, 350-0295, Japan
| | - Nanako Takamatsu
- School of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama, 350-0295, Japan
| | - Takeshi Sakamoto
- School of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama, 350-0295, Japan
| | - Tohru Yamazaki
- School of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama, 350-0295, Japan
| | - Satoshi Asano
- Department of Pharmaceutical Sciences, International University of Health and Welfare, 2600-1 Kitakanemaru, Ohtawara, Tochigi, 324-8501, Japan
| | - Atsushi Mitsumoto
- Faculty of Pharmaceutical Sciences, Josai International University, 1 Gumyo, Togane, Chiba, 283-8555, Japan
| | - Yoichi Kawashima
- School of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama, 350-0295, Japan
| | - Naomi Kudo
- School of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama, 350-0295, Japan.
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209
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Eicosapentaenoic acid-containing phosphatidylcholine alleviated lipid accumulation in orotic acid-induced non-alcoholic fatty liver. J Funct Foods 2016. [DOI: 10.1016/j.jff.2016.02.041] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
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210
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Martin J, Balmer ML, Rajendran S, Maurhofer O, Dufour JF, St-Pierre MV. Nutritional stress exacerbates hepatic steatosis induced by deletion of the histidine nucleotide-binding (Hint2) mitochondrial protein. Am J Physiol Gastrointest Liver Physiol 2016; 310:G497-509. [PMID: 26767982 DOI: 10.1152/ajpgi.00178.2015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 01/07/2016] [Indexed: 01/31/2023]
Abstract
The histidine nucleotide-binding protein, Hint2, is a mitochondrial phosphoramidase expressed in liver, brown fat, pancreas, and muscle. The livers of Hint2 knockout (Hint2(-/-)) mice accumulate triglycerides and show a pattern of mitochondrial protein lysine hyperacetylation. The extent and nature of the lysine acetylation changes and the response of Hint2(-/-) mice to nutritional challenges that elicit a modification of protein acetylation have not been investigated. To compare the adaptation of Hint2(-/-) and control (Hint2(+/+)) mice with episodes of fasting and high-fat diet (HFD), we subjected animals to either feeding ad libitum or fasting for 24 h, and to either a HFD or control diet for 8 wk. Triglyceride content was higher in Hint2(-/-) than in Hint2(+/+) livers, whereas plasma triglycerides were fourfold lower. Malonyl-CoA levels were increased twofold in Hint2(-/-) livers. After 24 h fasting, Hint2(-/-) displayed a decrease in body temperature, commensurate with a decrease in mass of brown fat and downregulation of uncoupling protein 1. HFD-treated Hint2(-/-) livers showed more steatosis, and plasma insulin and cholesterol were higher than in Hint(+/+) mice. Several proteins identified as substrates of sirtuin 3 and 5 and active in intermediary and ketone metabolism were hyperacetylated in liver and brown fat mitochondria after both HFD and fasting regimens. Glutamate dehydrogenase activity was downregulated in fed and fasted livers, and this was attributed to an increase in acetylation and ADP-ribosylation. The absence of Hint2 deregulates the posttranslational modification of several mitochondrial proteins, which impedes the adaptation to episodes of nutritional stress.
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Affiliation(s)
- Juliette Martin
- Department of Clinical Research, University of Bern, Bern, Switzerland; and Department of Hepatology, Gastroenterology; and
| | - Maria L Balmer
- Department of Clinical Research, University of Bern, Bern, Switzerland; and Department of Hepatology, Gastroenterology; and
| | - Saranya Rajendran
- Department of Clinical Research, University of Bern, Bern, Switzerland; and Department of Hepatology, Gastroenterology; and
| | - Olivier Maurhofer
- Department of Clinical Research, University of Bern, Bern, Switzerland; and Department of Hepatology, Gastroenterology; and
| | - Jean-François Dufour
- Department of Clinical Research, University of Bern, Bern, Switzerland; and Department of Hepatology, Gastroenterology; and Visceral Surgery, University Hospital, Inselspital, Bern, Switzerland
| | - Marie V St-Pierre
- Department of Clinical Research, University of Bern, Bern, Switzerland; and Department of Hepatology, Gastroenterology; and
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211
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Bartoň L, Bureš D, Kott T, Řehák D. Associations of polymorphisms in bovine DGAT1, FABP4, FASN, and PPARGC1A genes with intramuscular fat content and the fatty acid composition of muscle and subcutaneous fat in Fleckvieh bulls. Meat Sci 2016; 114:18-23. [DOI: 10.1016/j.meatsci.2015.12.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 12/04/2015] [Accepted: 12/14/2015] [Indexed: 10/22/2022]
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212
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Zhu WF, Zhu JF, Liang L, Shen Z, Wang YM. Maternal undernutrition leads to elevated hepatic triglycerides in male rat offspring due to increased expression of lipoprotein lipase. Mol Med Rep 2016; 13:4487-93. [PMID: 27035287 DOI: 10.3892/mmr.2016.5040] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 12/08/2016] [Indexed: 11/06/2022] Open
Abstract
Small for gestational age (SGA) at birth increases the risk of developing metabolic syndrome, which encompasses various symptoms including hypertriglyceridemia. The aim of the present study was to determine whether maternal undernutrition during pregnancy may lead to alterations in hepatic triglyceride content and the gene expression levels of hepatic lipoprotein lipase (LPL) in SGA male offspring. The present study focused on the male offspring in order to prevent confounding factors, such as estrus cycle and hormone profile. Female Sprague Dawley rats were arbitrarily assigned to receive an ad libitum chow diet or 50% food restricted diet from pregnancy day 1 until parturition. Reverse transcription quantitative polymerase chain reaction and western blot analysis were used to measure the gene expression levels of hepatic LPL at day 1 and upon completion of the third week of age. Chromatin immunoprecipitation quantified the binding activity of liver X receptor‑α (LXR‑α) gene to the LXR response elements (LXRE) on LPL promoter and LPL epigenetic characteristics. At 3 weeks of age, SGA male offspring exhibited significantly elevated levels of hepatic triglycerides, which was concomitant with increased expression levels of LPL. Since LPL is regulated by LXR‑α, the expression levels of LXR‑α were detected in appropriate for gestational age and SGA male offspring. Maternal undernutrition during pregnancy led to an increase in the hepatic expression levels of LXR‑α, and enriched binding to the putative LXR response elements in the LPL promoter regions in 3‑week‑old male offspring. In addition, enhanced acetylation of histone H3 [H3 lysine (K)9 and H3K14] was detected surrounding the LPL promoter. The results of the present study indicated that maternal undernutrition during pregnancy may lead to an increase in hepatic triglycerides, via alterations in the transcriptional and epigenetic regulation of the LPL gene.
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Affiliation(s)
- Wei-Fen Zhu
- Department of Pediatrics, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, P.R. China
| | - Jian-Fang Zhu
- Department of Pediatrics, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, P.R. China
| | - Li Liang
- Department of Pediatrics, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, P.R. China
| | - Zheng Shen
- Department of Central Laboratory, Children's Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang 310003, P.R. China
| | - Ying-Min Wang
- Department of Pediatrics, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, P.R. China
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213
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Kieffer DA, Piccolo BD, Vaziri ND, Liu S, Lau WL, Khazaeli M, Nazertehrani S, Moore ME, Marco ML, Martin RJ, Adams SH. Resistant starch alters gut microbiome and metabolomic profiles concurrent with amelioration of chronic kidney disease in rats. Am J Physiol Renal Physiol 2016; 310:F857-71. [PMID: 26841824 DOI: 10.1152/ajprenal.00513.2015] [Citation(s) in RCA: 160] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 01/28/2016] [Indexed: 02/06/2023] Open
Abstract
Patients and animals with chronic kidney disease (CKD) exhibit profound alterations in the gut environment including shifts in microbial composition, increased fecal pH, and increased blood levels of gut microbe-derived metabolites (xenometabolites). The fermentable dietary fiber high amylose maize-resistant starch type 2 (HAMRS2) has been shown to alter the gut milieu and in CKD rat models leads to markedly improved kidney function. The aim of the present study was to identify specific cecal bacteria and cecal, blood, and urinary metabolites that associate with changes in kidney function to identify potential mechanisms involved with CKD amelioration in response to dietary resistant starch. Male Sprague-Dawley rats with adenine-induced CKD were fed a semipurified low-fiber diet or a high-fiber diet [59% (wt/wt) HAMRS2] for 3 wk (n = 9 rats/group). The cecal microbiome was characterized, and cecal contents, serum, and urine metabolites were analyzed. HAMRS2-fed rats displayed decreased cecal pH, decreased microbial diversity, and an increased Bacteroidetes-to-Firmicutes ratio. Several uremic retention solutes were altered in the cecal contents, serum, and urine, many of which had strong correlations with specific gut bacteria abundances, i.e., serum and urine indoxyl sulfate were reduced by 36% and 66%, respectively, in HAMRS2-fed rats and urine p-cresol was reduced by 47% in HAMRS2-fed rats. Outcomes from this study were coincident with improvements in kidney function indexes and amelioration of CKD outcomes previously reported for these rats, suggesting an important role for microbial-derived factors and gut microbe metabolism in regulating host kidney function.
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Affiliation(s)
- Dorothy A Kieffer
- Obesity and Metabolism Research Unit, United States Department of Agriculture-Agricultural Research Service Western Human Nutrition Research Center, Davis, California; Graduate Group in Nutritional Biology and Department of Nutrition, University of California, Davis, California
| | - Brian D Piccolo
- Arkansas Children's Nutrition Center and Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | | | - Shuman Liu
- Division of Nephrology, University of California, Irvine, California
| | - Wei L Lau
- Division of Nephrology, University of California, Irvine, California
| | - Mahyar Khazaeli
- Division of Nephrology, University of California, Irvine, California
| | | | - Mary E Moore
- Department of Food Science and Technology, University of California, Davis, California; and
| | - Maria L Marco
- Department of Food Science and Technology, University of California, Davis, California; and
| | - Roy J Martin
- Obesity and Metabolism Research Unit, United States Department of Agriculture-Agricultural Research Service Western Human Nutrition Research Center, Davis, California
| | - Sean H Adams
- Graduate Group in Nutritional Biology and Department of Nutrition, University of California, Davis, California; Arkansas Children's Nutrition Center and Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
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Jojima T, Tomotsune T, Iijima T, Akimoto K, Suzuki K, Aso Y. Empagliflozin (an SGLT2 inhibitor), alone or in combination with linagliptin (a DPP-4 inhibitor), prevents steatohepatitis in a novel mouse model of non-alcoholic steatohepatitis and diabetes. Diabetol Metab Syndr 2016; 8:45. [PMID: 27462372 PMCID: PMC4960737 DOI: 10.1186/s13098-016-0169-x] [Citation(s) in RCA: 145] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 07/12/2016] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Sodium-glucose co-transporter-2 (SGLT2) inhibitors are new oral antidiabetic drugs that reduce hyperglycemia by promoting urinary glucose excretion. Glycosuria produced by SGLT2 inhibitors is associated with weight loss, mainly due to reduced fat volume. We investigated the effects of empagliflozin (selective SGLT2 inhibitor) and linagliptin (DPP-4 inhibitor) on steatohepatitis and fibrosis in a mouse model of non-alcoholic steatohepatitis (NASH) with diabetes. METHODS A novel NASH model was generated by administration of streptozotocin to C57BL/6J mice at 2 days old, with a high-fat diet from 4 weeks. NASH mice aged 6 weeks were divided into four groups of 6 animals: vehicle, linagliptin (10 mg/kg), empagliflozin (10 mg/kg), and linagliptin + empagliflozin. The histological non-alcoholic fatty liver disease activity score was significantly lower in the empagliflozin and linagliptin + empagliflozin groups than in the vehicle or linagliptin groups. Hepatic expression of inflammatory genes (tumor necrosis factor-α, interleukin-6, and monocyte chemoattractant protein-1) was decreased in the empagliflozin and linagliptin + empagliflozin groups compared with the vehicle group. The collagen deposition with Sirius red staining was significantly reduced in the linagliptin + empagliflozin group compared with the linagliptin or the empagliflozin group. Immunohistochemistry showed that expression of α-smooth muscle actin, a marker of myofibroblasts (fibrosis), was reduced in the linagliptin + empagliflozin group compared with the vehicle group, as was expression of type 1 and 3 collagen mRNA. Linagliptin + empagliflozin decreased expression of mRNAs for genes related to fatty acid synthesis, but did not increase mRNAs for β-oxidation-related genes. CONCLUSIONS While empagliflozin alone attenuates development of NASH showing anti-steatotic and anti-inflammatory effects, combined administration of empagliflozin and linagliptin can synergistically ameliorates NASH with stronger anti-fibrotic effects.
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Affiliation(s)
- Teruo Jojima
- Department of Endocrinology and Metabolism, Dokkyo Medical University, Mibu, Tochigi Japan
| | - Takanori Tomotsune
- Department of Endocrinology and Metabolism, Dokkyo Medical University, Mibu, Tochigi Japan
| | - Toshie Iijima
- Department of Endocrinology and Metabolism, Dokkyo Medical University, Mibu, Tochigi Japan
| | - Kazumi Akimoto
- Division of Clinical Science, Research Support Center, Dokkyo Medical University, Mibu, Tochigi Japan
| | - Kunihiro Suzuki
- Department of Endocrinology and Metabolism, Dokkyo Medical University, Mibu, Tochigi Japan
| | - Yoshimasa Aso
- Department of Endocrinology and Metabolism, Dokkyo Medical University, Mibu, Tochigi Japan
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215
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Ritchie MK, Johnson LC, Clodfelter JE, Pemble CW, Fulp BE, Furdui CM, Kridel SJ, Lowther WT. Crystal Structure and Substrate Specificity of Human Thioesterase 2: INSIGHTS INTO THE MOLECULAR BASIS FOR THE MODULATION OF FATTY ACID SYNTHASE. J Biol Chem 2015; 291:3520-30. [PMID: 26663084 DOI: 10.1074/jbc.m115.702597] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Indexed: 01/12/2023] Open
Abstract
The type I fatty acid synthase (FASN) is responsible for the de novo synthesis of palmitate. Chain length selection and release is performed by the C-terminal thioesterase domain (TE1). FASN expression is up-regulated in cancer, and its activity levels are controlled by gene dosage and transcriptional and post-translational mechanisms. In addition, the chain length of fatty acids produced by FASN is controlled by a type II thioesterase called TE2 (E.C. 3.1.2.14). TE2 has been implicated in breast cancer and generates a broad lipid distribution within milk. The molecular basis for the ability of the TE2 to compete with TE1 for the acyl chain attached to the acyl carrier protein (ACP) domain of FASN is unknown. Herein, we show that human TE1 efficiently hydrolyzes acyl-CoA substrate mimetics. In contrast, TE2 prefers an engineered human acyl-ACP substrate and readily releases short chain fatty acids from full-length FASN during turnover. The 2.8 Å crystal structure of TE2 reveals a novel capping domain insert within the α/β hydrolase core. This domain is reminiscent of capping domains of type II thioesterases involved in polyketide synthesis. The structure also reveals that the capping domain had collapsed onto the active site containing the Ser-101-His-237-Asp-212 catalytic triad. This observation suggests that the capping domain opens to enable the ACP domain to dock and to place the acyl chain and 4'-phosphopantetheinyl-linker arm correctly for catalysis. Thus, the ability of TE2 to prematurely release fatty acids from FASN parallels the role of editing thioesterases involved in polyketide and non-ribosomal peptide synthase synthases.
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Affiliation(s)
- Melissa K Ritchie
- From the Center for Structural Biology and Department of Biochemistry
| | | | - Jill E Clodfelter
- From the Center for Structural Biology and Department of Biochemistry
| | - Charles W Pemble
- From the Center for Structural Biology and Department of Biochemistry
| | - Brian E Fulp
- Comprehensive Cancer Center of Wake Forest Baptist Medical Center, Winston-Salem, North Carolina 27157
| | - Cristina M Furdui
- Comprehensive Cancer Center of Wake Forest Baptist Medical Center, Winston-Salem, North Carolina 27157 Department of Internal Medicine, Section on Molecular Medicine, and
| | - Steven J Kridel
- Comprehensive Cancer Center of Wake Forest Baptist Medical Center, Winston-Salem, North Carolina 27157 Department of Cancer Biology, Wake Forest School of Medicine and
| | - W Todd Lowther
- From the Center for Structural Biology and Department of Biochemistry, Comprehensive Cancer Center of Wake Forest Baptist Medical Center, Winston-Salem, North Carolina 27157
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216
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Castro C, Freitag J, Berod L, Lochner M, Sparwasser T. Microbe-associated immunomodulatory metabolites: Influence on T cell fate and function. Mol Immunol 2015; 68:575-84. [DOI: 10.1016/j.molimm.2015.07.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 06/29/2015] [Accepted: 07/21/2015] [Indexed: 01/30/2023]
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217
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Paran CW, Zou K, Ferrara PJ, Song H, Turk J, Funai K. Lipogenesis mitigates dysregulated sarcoplasmic reticulum calcium uptake in muscular dystrophy. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:1530-8. [PMID: 26361872 DOI: 10.1016/j.bbalip.2015.09.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 08/27/2015] [Accepted: 09/06/2015] [Indexed: 01/07/2023]
Abstract
Muscular dystrophy is accompanied by a reduction in activity of sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA) that contributes to abnormal Ca(2+) homeostasis in sarco/endoplasmic reticulum (SR/ER). Recent findings suggest that skeletal muscle fatty acid synthase (FAS) modulates SERCA activity and muscle function via its effects on SR membrane phospholipids. In this study, we examined muscle's lipid metabolism in mdx mice, a mouse model for Duchenne muscular dystrophy (DMD). De novo lipogenesis was ~50% reduced in mdx muscles compared to wildtype (WT) muscles. Gene expressions of lipogenic and other ER lipid-modifying enzymes were found to be differentially expressed between wildtype (WT) and mdx muscles. A comprehensive examination of muscles' SR phospholipidome revealed elevated phosphatidylcholine (PC) and PC/phosphatidylethanolamine (PE) ratio in mdx compared to WT mice. Studies in primary myocytes suggested that defects in key lipogenic enzymes including FAS, stearoyl-CoA desaturase-1 (SCD1), and Lipin1 are likely contributing to reduced SERCA activity in mdx mice. Triple transgenic expression of FAS, SCD1, and Lipin1 (3TG) in mdx myocytes partly rescued SERCA activity, which coincided with an increase in SR PE that normalized PC/PE ratio. These findings implicate a defect in lipogenesis to be a contributing factor for SERCA dysfunction in muscular dystrophy. Restoration of muscle's lipogenic pathway appears to mitigate SERCA function through its effects on SR membrane composition.
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Affiliation(s)
- Christopher W Paran
- Department of Kinesiology, East Carolina University, 115 Heart Drive, Greenville, North Carolina 27834, USA; Department of Physiology, East Carolina University, 115 Heart Drive, Greenville, North Carolina 27834, USA; East Carolina Diabetes and Obesity Institute, East Carolina University, 115 Heart Drive, Greenville, North Carolina 27834, USA
| | - Kai Zou
- Department of Kinesiology, East Carolina University, 115 Heart Drive, Greenville, North Carolina 27834, USA; East Carolina Diabetes and Obesity Institute, East Carolina University, 115 Heart Drive, Greenville, North Carolina 27834, USA
| | - Patrick J Ferrara
- Department of Kinesiology, East Carolina University, 115 Heart Drive, Greenville, North Carolina 27834, USA; East Carolina Diabetes and Obesity Institute, East Carolina University, 115 Heart Drive, Greenville, North Carolina 27834, USA
| | - Haowei Song
- Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri 63110, USA
| | - John Turk
- Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri 63110, USA
| | - Katsuhiko Funai
- Department of Kinesiology, East Carolina University, 115 Heart Drive, Greenville, North Carolina 27834, USA; Department of Physiology, East Carolina University, 115 Heart Drive, Greenville, North Carolina 27834, USA; East Carolina Diabetes and Obesity Institute, East Carolina University, 115 Heart Drive, Greenville, North Carolina 27834, USA.
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218
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Stinkens R, Goossens GH, Jocken JWE, Blaak EE. Targeting fatty acid metabolism to improve glucose metabolism. Obes Rev 2015; 16:715-57. [PMID: 26179344 DOI: 10.1111/obr.12298] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 04/23/2015] [Accepted: 05/10/2015] [Indexed: 12/15/2022]
Abstract
Disturbances in fatty acid metabolism in adipose tissue, liver, skeletal muscle, gut and pancreas play an important role in the development of insulin resistance, impaired glucose metabolism and type 2 diabetes mellitus. Alterations in diet composition may contribute to prevent and/or reverse these disturbances through modulation of fatty acid metabolism. Besides an increased fat mass, adipose tissue dysfunction, characterized by an altered capacity to store lipids and an altered secretion of adipokines, may result in lipid overflow, systemic inflammation and excessive lipid accumulation in non-adipose tissues like liver, skeletal muscle and the pancreas. These impairments together promote the development of impaired glucose metabolism, insulin resistance and type 2 diabetes mellitus. Furthermore, intrinsic functional impairments in either of these organs may contribute to lipotoxicity and insulin resistance. The present review provides an overview of fatty acid metabolism-related pathways in adipose tissue, liver, skeletal muscle, pancreas and gut, which can be targeted by diet or food components, thereby improving glucose metabolism.
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Affiliation(s)
- R Stinkens
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - G H Goossens
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - J W E Jocken
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - E E Blaak
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands
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219
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PPARα/γ agonists and antagonists differently affect hepatic lipid metabolism, oxidative stress and inflammatory cytokine production in steatohepatitic rats. Cytokine 2015; 75:127-35. [DOI: 10.1016/j.cyto.2015.05.031] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 04/22/2015] [Accepted: 05/26/2015] [Indexed: 12/12/2022]
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220
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Renaville B, Bacciu N, Lanzoni M, Corazzin M, Piasentier E. Polymorphism of fat metabolism genes as candidate markers for meat quality and production traits in heavy pigs. Meat Sci 2015; 110:220-3. [PMID: 26255706 DOI: 10.1016/j.meatsci.2015.07.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 07/15/2015] [Accepted: 07/16/2015] [Indexed: 12/28/2022]
Abstract
High meat quality is required for dry-cured ham production, which quality depends on meat fat quantity and composition. The aim was to study the polymorphisms of six genes involved in fat metabolism, namely, Stearoyl-CoA desaturase (SCD), Diacylglycerol acyltransferase 1 and 2 (DGAT1 &DGAT2), Microsomal triglyceride transfer protein (MTTP), Fatty acid synthase (FASN) and Heart fatty acid binding protein (H-FABP) in two traditional (Large White or Duroc × (Landrace × Large White)) and two industrial hybrids (Goland and Danbred), which are used for dry-cured ham production. Significant associations of SCD and MTTP were found with carcass weight. DGAT2 was associated with back fat thickness and L* fat colour (objective white colour score). Several genes (DGAT2, MTTP &FASN) were associated with weight loss during salting, first step in dry-cured ham production, affecting final yield. Finally, MTTP was associated with shear force. Our findings suggest that the SCD, DGAT2, MTTP and FASN polymorphisms are associated with quality of heavy pig meat products.
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Affiliation(s)
- B Renaville
- Department of Food Science, University of Udine, Italy.
| | - N Bacciu
- Zoetis, VMRD Genetics, Kalamazoo, MI, USA
| | - M Lanzoni
- Department of Food Science, University of Udine, Italy
| | - M Corazzin
- Department of Agriculture and Environmental Science, University of Udine, Via Sondrio 2A, 33100 Udine, Italy
| | - E Piasentier
- Department of Agriculture and Environmental Science, University of Udine, Via Sondrio 2A, 33100 Udine, Italy
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221
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Martin GG, Atshaves BP, Landrock KK, Landrock D, Schroeder F, Kier AB. Loss of L-FABP, SCP-2/SCP-x, or both induces hepatic lipid accumulation in female mice. Arch Biochem Biophys 2015; 580:41-9. [PMID: 26116377 DOI: 10.1016/j.abb.2015.06.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2014] [Revised: 06/08/2015] [Accepted: 06/17/2015] [Indexed: 02/06/2023]
Abstract
Although roles for both sterol carrier protein-2/sterol carrier protein-x (SCP-2/SCP-x) and liver fatty acid binding protein (L-FABP) have been proposed in hepatic lipid accumulation, individually ablating these genes has been complicated by concomitant alterations in the other gene product(s). For example, ablating SCP2/SCP-x induces upregulation of L-FABP in female mice. Therefore, the impact of ablating SCP-2/SCP-x (DKO) or L-FABP (LKO) individually or both together (TKO) was examined in female mice. Loss of SCP-2/SCP-x (DKO, TKO) more so than loss of L-FABP alone (LKO) increased hepatic total lipid and total cholesterol content, especially cholesteryl ester. Hepatic accumulation of nonesterified long chain fatty acids (LCFA) and phospholipids occurred only in DKO and TKO mice. Loss of SCP-2/SCP-x (DKO, TKO) increased serum total lipid primarily by increasing triglycerides. Altered hepatic level of proteins involved in cholesterol uptake, efflux, and/or secretion was observed, but did not compensate for the loss of L-FABP, SCP-2/SCP-x or both. However, synergistic responses were not seen with the combinatorial knock out animals-suggesting that inhibiting SCP-2/SCP-x is more correlative with hepatic dysfunction than L-FABP. The DKO- and TKO-induced hepatic accumulation of cholesterol and long chain fatty acids shared significant phenotypic similarities with non-alcoholic fatty liver disease (NAFLD).
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Affiliation(s)
- Gregory G Martin
- Department of Physiology and Pharmacology, Texas A&M University, College Station, TX 77843-4466, United States
| | - Barbara P Atshaves
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, United States
| | - Kerstin K Landrock
- Department of Pathobiology, Texas A&M University, College Station, TX 77843-4467, United States
| | - Danilo Landrock
- Department of Pathobiology, Texas A&M University, College Station, TX 77843-4467, United States
| | - Friedhelm Schroeder
- Department of Physiology and Pharmacology, Texas A&M University, College Station, TX 77843-4466, United States
| | - Ann B Kier
- Department of Pathobiology, Texas A&M University, College Station, TX 77843-4467, United States.
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222
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Oligonol suppresses lipid accumulation and improves insulin resistance in a palmitate-induced in HepG2 hepatocytes as a cellular steatosis model. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2015; 15:185. [PMID: 26077338 PMCID: PMC4490649 DOI: 10.1186/s12906-015-0709-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 06/04/2015] [Indexed: 01/12/2023]
Abstract
Background Oligonol is a low molecular weight form of polyphenol polymers derived from lychee fruits. Several studies suggest that Oligonol has an anti-obesity effect. Since obesity is tightly associated with insulin resistance, we investigated a possible remission effect of Oligonol on lipid accumulation and insulin resistance in human hepatic HepG2 cells. Methods HepG2 cells were treated with palmitate for 24 h to induce cellular hepatic steatosis and insulin resistance. The cells were then treated with Oligonol at subtoxic concentrations and examined for lipid metabolism, cytokine production, and insulin signaling using quantitative RT-PCR and western blot analysis. Results Oligonol treatment reversed the palmitate-induced intracellular lipid accumulation, down regulated the expression of lipogenic genes, and up-regulated genes for fatty acid degradation. Oligonol restored insulin sensitivity, as was determined by the phosphorylation states of IRS-1. Oligonol also inhibited STAT3-SOCS3 signaling and increased AMPK phosphorylation in HepG2 cells. Conclusion Oligonol treatment improved palmitate-induced cellular steatosis and insulin resistance in HepG2 cells with concomitant reduction of inflammatory cytokines and decrease in STAT3-SOCS3 and AMPK-mTOR pathways. Oligonol may have beneficial effects in lipid metabolism and insulin resistance in the liver.
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223
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Characterization of novel mechanisms for steatosis from global protein hyperacetylation in ethanol-induced mouse hepatocytes. Biochem Biophys Res Commun 2015; 463:832-8. [PMID: 26056001 DOI: 10.1016/j.bbrc.2015.04.154] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 04/21/2015] [Indexed: 12/20/2022]
Abstract
Steatosis is the earliest and most common disease of the liver due to chronic ethanol consumption, and stems from alterations in the function of transcription factors related to lipid metabolism. Protein acetylation at the lysine residue (Kac) is known to have diverse functions in cell metabolism. Recent studies showed that ethanol exposure induces global protein hyperacetylation by reducing the deacetylase activities of SIRT1 and SIRT3. Although global acetylome analyses have revealed the involvement of a variety of lysine acetylation sites, the exact sites directly regulated by ethanol exposure are unknown. In this study, to elucidate the exact hyperacetylation sites that contribute to SIRT1 and SIRT3 downregulation, we identified and quantified a total of 1285 Kac sites and 686 Kac proteins in AML-12 cells after ethanol treatment (100 mM) for 3 days. All quantified Kac sites were divided into four quantiles: Q1 (0-15%), Q2 (15-50%), Q3 (50-85%), and Q4 (85-100%). Q4 had 192 Kac sites indicating ethanol-induced hyperacetylation. Using the Motif-x program, the [LXKL], [KH], and [KW] motifs were included in the Q4 category, where [KW] was a specific residue for SIRT3. We also performed gene ontology term and KEGG pathway enrichment analyses. Hyperacetylation sites were significantly enriched in biosynthetic processes and ATPase activities within the biological process and molecular function categories, respectively. In conclusion, ethanol regulates the acetylation of proteins in a variety of metabolic pathways mediated by SIRT1 and SIRT3. As a result, ethanol stimulates increased de novo fatty acid synthesis in hepatocytes.
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224
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Liu X, Chan HC, Ding G, Cai J, Song Y, Wang T, Zhang D, Chen H, Yu MK, Wu Y, Qu F, Liu Y, Lu Y, Adashi EY, Sheng J, Huang H. FSH regulates fat accumulation and redistribution in aging through the Gαi/Ca(2+)/CREB pathway. Aging Cell 2015; 14:409-20. [PMID: 25754247 PMCID: PMC4406670 DOI: 10.1111/acel.12331] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/17/2014] [Indexed: 12/25/2022] Open
Abstract
Increased fat mass and fat redistribution are commonly observed in aging populations worldwide. Although decreased circulating levels of sex hormones, androgens and oestrogens have been observed, the exact mechanism of fat accumulation and redistribution during aging remains obscure. In this study, the receptor of follicle-stimulating hormone (FSH), a gonadotropin that increases sharply and persistently with aging in both males and females, is functionally expressed in human and mouse fat tissues and adipocytes. Follicle-stimulating hormone was found to promote lipid biosynthesis and lipid droplet formation; FSH could also alter the secretion of leptin and adiponectin, but not hyperplasia, in vitro and in vivo. The effects of FSH are mediated by FSH receptors coupled to the Gαi protein; as a result, Ca2+ influx is stimulated, cAMP-response-element-binding protein is phosphorylated, and an array of genes involved in lipid biosynthesis is activated. The present findings depict the potential of FSH receptor-mediated lipodystrophy of adipose tissues in aging. Our results also reveal the mechanism of fat accumulation and redistribution during aging of males and females.
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Affiliation(s)
- Xin‐Mei Liu
- International Peace Maternity and Child Health Hospital School of Medicine Shanghai Jiao Tong University Shanghai China
- Department of Pathology & Pathophysiology School of Medicine Zhejiang University Zhejiang China
- Shanghai Jiao Tong University – The Chinese University of Hong Kong Joint Research Center for Human Reproduction and Related Diseases Shanghai China
| | - Hsiao Chang Chan
- Shanghai Jiao Tong University – The Chinese University of Hong Kong Joint Research Center for Human Reproduction and Related Diseases Shanghai China
- Epithelial Cell Biology Research Center School of Biomedical Sciences Faculty of Medicine The Chinese University of Hong Kong Hong Kong Hong Kong
- Key Laboratory for Regenerative Medicine (Jinan University – The Chinese University of Hong Kong) Ministry of Education Hangzhou China
| | - Guo‐Lian Ding
- International Peace Maternity and Child Health Hospital School of Medicine Shanghai Jiao Tong University Shanghai China
- Shanghai Jiao Tong University – The Chinese University of Hong Kong Joint Research Center for Human Reproduction and Related Diseases Shanghai China
- The Key Laboratory of Reproductive Genetics Ministry of Education Hangzhou China
| | - Jie Cai
- The Key Laboratory of Reproductive Genetics Ministry of Education Hangzhou China
- Ningbo Maternal and Child Health Hospital Zhejiang China
| | - Yang Song
- The Key Laboratory of Reproductive Genetics Ministry of Education Hangzhou China
| | - Ting‐Ting Wang
- The Key Laboratory of Reproductive Genetics Ministry of Education Hangzhou China
| | - Dan Zhang
- The Key Laboratory of Reproductive Genetics Ministry of Education Hangzhou China
| | - Hui Chen
- Shanghai Jiao Tong University – The Chinese University of Hong Kong Joint Research Center for Human Reproduction and Related Diseases Shanghai China
- Epithelial Cell Biology Research Center School of Biomedical Sciences Faculty of Medicine The Chinese University of Hong Kong Hong Kong Hong Kong
- Key Laboratory for Regenerative Medicine (Jinan University – The Chinese University of Hong Kong) Ministry of Education Hangzhou China
| | - Mei Kuen Yu
- Shanghai Jiao Tong University – The Chinese University of Hong Kong Joint Research Center for Human Reproduction and Related Diseases Shanghai China
- Epithelial Cell Biology Research Center School of Biomedical Sciences Faculty of Medicine The Chinese University of Hong Kong Hong Kong Hong Kong
- Key Laboratory for Regenerative Medicine (Jinan University – The Chinese University of Hong Kong) Ministry of Education Hangzhou China
| | - Yan‐Ting Wu
- International Peace Maternity and Child Health Hospital School of Medicine Shanghai Jiao Tong University Shanghai China
- Shanghai Jiao Tong University – The Chinese University of Hong Kong Joint Research Center for Human Reproduction and Related Diseases Shanghai China
- The Key Laboratory of Reproductive Genetics Ministry of Education Hangzhou China
| | - Fan Qu
- The Key Laboratory of Reproductive Genetics Ministry of Education Hangzhou China
| | - Ye Liu
- International Peace Maternity and Child Health Hospital School of Medicine Shanghai Jiao Tong University Shanghai China
- Department of Pathology & Pathophysiology School of Medicine Zhejiang University Zhejiang China
- The Key Laboratory of Reproductive Genetics Ministry of Education Hangzhou China
| | - Yong‐Chao Lu
- The Key Laboratory of Reproductive Genetics Ministry of Education Hangzhou China
| | - Eli Y. Adashi
- The Warren Alpert Medical School Brown University Providence RI USA
| | - Jian‐Zhong Sheng
- Department of Pathology & Pathophysiology School of Medicine Zhejiang University Zhejiang China
| | - He‐Feng Huang
- International Peace Maternity and Child Health Hospital School of Medicine Shanghai Jiao Tong University Shanghai China
- The Key Laboratory of Reproductive Genetics Ministry of Education Hangzhou China
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225
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Dietary docosahexaenoic acid and eicosapentaenoic acid influence liver triacylglycerol and insulin resistance in rats fed a high-fructose diet. Mar Drugs 2015; 13:1864-81. [PMID: 25837985 PMCID: PMC4413191 DOI: 10.3390/md13041864] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 03/10/2015] [Accepted: 03/23/2015] [Indexed: 12/31/2022] Open
Abstract
This study aimed to examine the benefits of different amounts of omega-3 (n-3) polyunsaturated fatty acids from fish oil (FO) on lipid metabolism, insulin resistance and gene expression in rats fed a high-fructose diet. Male Wistar rats were separated into two groups: Control (C, n = 6) and Fructose (Fr, n = 32), the latter receiving a diet containing 63% by weight fructose for 60 days. After this period, 24 animals from Fr group were allocated to three groups: FrFO2 (n = 8) receiving 63% fructose and 2% FO plus 5% soybean oil; FrFO5 (n = 8) receiving 63% fructose and 5% FO plus 2% soybean oil; and FrFO7 (n = 8) receiving 63% fructose and 7% FO. Animals were fed these diets for 30 days. Fructose led to an increase in liver weight, hepatic and serum triacylglycerol, serum alanine aminotransferase and HOMA1-IR index. These alterations were reversed by 5% and 7% FO. FO had a dose-dependent effect on expression of genes related to hepatic β-oxidation (increased) and hepatic lipogenesis (decreased). The group receiving the highest FO amount had increased markers of oxidative stress. It is concluded that n-3 fatty acids may be able to reverse the adverse metabolic effects induced by a high fructose diet.
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226
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C-C chemokine receptor 2 inhibitor ameliorates hepatic steatosis by improving ER stress and inflammation in a type 2 diabetic mouse model. PLoS One 2015; 10:e0120711. [PMID: 25816097 PMCID: PMC4376739 DOI: 10.1371/journal.pone.0120711] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Accepted: 01/26/2015] [Indexed: 12/11/2022] Open
Abstract
Hepatic steatosis is the accumulation of excess fat in the liver. Recently, hepatic steatosis has become more important because it occurs in the patients with obesity, type 2 diabetes, and hyperlipidemia and is associated with endoplasmic reticulum (ER) stress and insulin resistance. C-C chemokine receptor 2 (CCR2) inhibitor has been reported to improve inflammation and glucose intolerance in diabetes, but its mechanisms remained unknown in hepatic steatosis. We examined whether CCR2 inhibitor improves ER stress-induced hepatic steatosis in type 2 diabetic mice. In this study, db/db and db/m (n = 9) mice were fed CCR2 inhibitor (2 mg/kg/day) for 9 weeks. In diabetic mice, CCR2 inhibitor decreased plasma and hepatic triglycerides levels and improved insulin sensitivity. Moreover, CCR2 inhibitor treatment decreased ER stress markers (e.g., BiP, ATF4, CHOP, and XBP-1) and inflammatory cytokines (e.g., TNFα, IL-6, and MCP-1) while increasing markers of mitochondrial biogenesis (e.g., PGC-1α, Tfam, and COX1) in the liver. We suggest that CCR2 inhibitor may ameliorate hepatic steatosis by reducing ER stress and inflammation in type 2 diabetes mellitus.
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Lee SSY, Li J, Tai JN, Ratliff TL, Park K, Cheng JX. Avasimibe encapsulated in human serum albumin blocks cholesterol esterification for selective cancer treatment. ACS NANO 2015; 9:2420-32. [PMID: 25662106 PMCID: PMC5909415 DOI: 10.1021/nn504025a] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Undesirable side effects remain a significant challenge in cancer chemotherapy. Here we report a strategy for cancer-selective chemotherapy by blocking acyl-CoA cholesterol acyltransferase-1 (ACAT-1)-mediated cholesterol esterification. To efficiently block cholesterol esterification in cancer in vivo, we developed a systemically injectable nanoformulation of avasimibe (a potent ACAT-1 inhibitor), called avasimin. In cell lines of human prostate, pancreatic, lung, and colon cancer, avasimin significantly reduced cholesteryl ester storage in lipid droplets and elevated intracellular free cholesterol levels, which led to apoptosis and suppression of proliferation. In xenograft models of prostate cancer and colon cancer, intravenous administration of avasimin caused the concentration of avasimibe in tumors to be 4-fold higher than the IC50 value. Systemic treatment of avasimin notably suppressed tumor growth in mice and extended the length of survival time. No adverse effects of avasimin to normal cells and organs were observed. Together, this study provides an effective approach for selective cancer chemotherapy by targeting altered cholesterol metabolism of cancer cells.
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Affiliation(s)
- Steve Seung-Young Lee
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907
| | - Junjie Li
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907
| | - Jien Nee Tai
- Department of Chemistry, Purdue University, West Lafayette, IN 47907
| | - Timothy L. Ratliff
- Center for Cancer Research, Purdue University, West Lafayette, IN 47907
- Department of Comparative Pathobiology, Purdue University, West Lafayette, IN 47907
| | - Kinam Park
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907
- Center for Cancer Research, Purdue University, West Lafayette, IN 47907
- Department of Industrial and Physical Pharmacy, Purdue University, West Lafayette, IN 47907
| | - Ji-Xin Cheng
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907
- Department of Chemistry, Purdue University, West Lafayette, IN 47907
- Center for Cancer Research, Purdue University, West Lafayette, IN 47907
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Kwan HY, Niu X, Dai W, Tong T, Chao X, Su T, Chan CL, Lee KC, Fu X, Yi H, Yu H, Li T, Tse AKW, Fong WF, Pan SY, Lu A, Yu ZL. Lipidomic-based investigation into the regulatory effect of Schisandrin B on palmitic acid level in non-alcoholic steatotic livers. Sci Rep 2015; 5:9114. [PMID: 25766252 PMCID: PMC4358044 DOI: 10.1038/srep09114] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 02/17/2015] [Indexed: 02/08/2023] Open
Abstract
Schisandrin B (SchB) is one of the most abundant bioactive dibenzocyclooctadiene derivatives found in the fruit of Schisandra chinensis. Here, we investigated the potential therapeutic effects of SchB on non-alcoholic fatty-liver disease (NAFLD). In lipidomic study, ingenuity pathway analysis highlighted palmitate biosynthesis metabolic pathway in the liver samples of SchB-treated high-fat-diet-fed mice. Further experiments showed that the SchB treatment reduced expression and activity of fatty acid synthase, expressions of hepatic mature sterol regulatory element binding protein-1 and tumor necrosis factor-α, and hepatic level of palmitic acid which is known to promote progression of steatosis to steatohepatitis. Furthermore, the treatment also reduced hepatic fibrosis, activated nuclear factor-erythroid-2-related factor-2 which is known to attenuate the progression of NASH-related fibrosis. Interestingly, in fasting mice, a single high-dose SchB induced transient lipolysis and increased the expressions of adipose triglyceride lipase and phospho-hormone sensitive lipase. The treatment also increased plasma cholesterol levels and 3-hydroxy-3-methylglutaryl-CoA reductase activity, reduced the hepatic low-density-lipoprotein receptor expression in these mice. Our data not only suggest SchB is a potential therapeutic agent for NAFLD, but also provided important information for a safe consumption of SchB because SchB overdosed under fasting condition will have adverse effects on lipid metabolism.
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Affiliation(s)
- Hiu Yee Kwan
- Centre for Cancer and Inflammation Research, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China
- Institute of Integrated Bioinfomedicine & Translational Science, HKBU Shenzhen Research Institute and Continuing Education, Shenzhen, China
| | - Xuyan Niu
- Institute of Basic Research in Clinical Medicine, China Academy of Chinese Medical Sciences, China
| | - Wenlin Dai
- Department of Mathematics, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China
| | - Tiejun Tong
- Department of Mathematics, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China
| | - Xiaojuan Chao
- Centre for Cancer and Inflammation Research, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China
- Institute of Integrated Bioinfomedicine & Translational Science, HKBU Shenzhen Research Institute and Continuing Education, Shenzhen, China
| | - Tao Su
- Centre for Cancer and Inflammation Research, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China
- Institute of Integrated Bioinfomedicine & Translational Science, HKBU Shenzhen Research Institute and Continuing Education, Shenzhen, China
| | - Chi Leung Chan
- Centre for Cancer and Inflammation Research, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China
| | - Kim Chung Lee
- Agilent Technology, Hong Kong Limited, Hong Kong, China
| | - Xiuqiong Fu
- Centre for Cancer and Inflammation Research, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China
- Institute of Integrated Bioinfomedicine & Translational Science, HKBU Shenzhen Research Institute and Continuing Education, Shenzhen, China
| | - Hua Yi
- Department of Pathology, Guangzhou University of Chinese Medicine, China
| | - Hua Yu
- Centre for Cancer and Inflammation Research, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China
- Institute of Integrated Bioinfomedicine & Translational Science, HKBU Shenzhen Research Institute and Continuing Education, Shenzhen, China
| | - Ting Li
- Centre for Cancer and Inflammation Research, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China
- Institute of Integrated Bioinfomedicine & Translational Science, HKBU Shenzhen Research Institute and Continuing Education, Shenzhen, China
| | - Anfernee Kai Wing Tse
- Centre for Cancer and Inflammation Research, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China
- Institute of Integrated Bioinfomedicine & Translational Science, HKBU Shenzhen Research Institute and Continuing Education, Shenzhen, China
| | - Wang Fun Fong
- Centre for Cancer and Inflammation Research, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China
- Institute of Integrated Bioinfomedicine & Translational Science, HKBU Shenzhen Research Institute and Continuing Education, Shenzhen, China
| | - Si-Yuan Pan
- Department of Pharmacology, Beijing University of Chinese Medicine, Beijing, China
| | - Aiping Lu
- Centre for Cancer and Inflammation Research, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China
- Institute of Integrated Bioinfomedicine & Translational Science, HKBU Shenzhen Research Institute and Continuing Education, Shenzhen, China
| | - Zhi-Ling Yu
- Centre for Cancer and Inflammation Research, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China
- Institute of Integrated Bioinfomedicine & Translational Science, HKBU Shenzhen Research Institute and Continuing Education, Shenzhen, China
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Sanders FWB, Griffin JL. De novo lipogenesis in the liver in health and disease: more than just a shunting yard for glucose. Biol Rev Camb Philos Soc 2015; 91:452-68. [PMID: 25740151 PMCID: PMC4832395 DOI: 10.1111/brv.12178] [Citation(s) in RCA: 312] [Impact Index Per Article: 34.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 01/07/2015] [Accepted: 01/20/2015] [Indexed: 02/06/2023]
Abstract
Hepatic de novo lipogenesis (DNL) is the biochemical process of synthesising fatty acids from acetyl‐CoA subunits that are produced from a number of different pathways within the cell, most commonly carbohydrate catabolism. In addition to glucose which most commonly supplies carbon units for DNL, fructose is also a profoundly lipogenic substrate that can drive DNL, important when considering the increasing use of fructose in corn syrup as a sweetener. In the context of disease, DNL is thought to contribute to the pathogenesis of non‐alcoholic fatty liver disease, a common condition often associated with the metabolic syndrome and consequent insulin resistance. Whether DNL plays a significant role in the pathogenesis of insulin resistance is yet to be fully elucidated, but it may be that the prevalent products of this synthetic process induce some aspect of hepatic insulin resistance.
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Affiliation(s)
- Francis W B Sanders
- MRC Human Nutrition Research, Elsie Widdowson Laboratory, 120 Fulbourn Road, Cambridge CB1 9NL, U.K.,The Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, U.K
| | - Julian L Griffin
- MRC Human Nutrition Research, Elsie Widdowson Laboratory, 120 Fulbourn Road, Cambridge CB1 9NL, U.K.,The Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, U.K
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Fatty acid synthase cooperates with glyoxalase 1 to protect against sugar toxicity. PLoS Genet 2015; 11:e1004995. [PMID: 25692475 PMCID: PMC4334898 DOI: 10.1371/journal.pgen.1004995] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Accepted: 01/08/2015] [Indexed: 01/03/2023] Open
Abstract
Fatty acid (FA) metabolism is deregulated in several human diseases including metabolic syndrome, type 2 diabetes and cancers. Therefore, FA-metabolic enzymes are potential targets for drug therapy, although the consequence of these treatments must be precisely evaluated at the organismal and cellular levels. In healthy organism, synthesis of triacylglycerols (TAGs)—composed of three FA units esterified to a glycerol backbone—is increased in response to dietary sugar. Saturation in the storage and synthesis capacity of TAGs is associated with type 2 diabetes progression. Sugar toxicity likely depends on advanced-glycation-end-products (AGEs) that form through covalent bounding between amine groups and carbonyl groups of sugar or their derivatives α-oxoaldehydes. Methylglyoxal (MG) is a highly reactive α-oxoaldehyde that is derived from glycolysis through a non-enzymatic reaction. Glyoxalase 1 (Glo1) works to neutralize MG, reducing its deleterious effects. Here, we have used the power of Drosophila genetics to generate Fatty acid synthase (FASN) mutants, allowing us to investigate the consequence of this deficiency upon sugar-supplemented diets. We found that FASN mutants are lethal but can be rescued by an appropriate lipid diet. Rescued animals do not exhibit insulin resistance, are dramatically sensitive to dietary sugar and accumulate AGEs. We show that FASN and Glo1 cooperate at systemic and cell-autonomous levels to protect against sugar toxicity. We observed that the size of FASN mutant cells decreases as dietary sucrose increases. Genetic interactions at the cell-autonomous level, where glycolytic enzymes or Glo1 were manipulated in FASN mutant cells, revealed that this sugar-dependent size reduction is a direct consequence of MG-derived-AGE accumulation. In summary, our findings indicate that FASN is dispensable for cell growth if extracellular lipids are available. In contrast, FA-synthesis appears to be required to limit a cell-autonomous accumulation of MG-derived-AGEs, supporting the notion that MG is the most deleterious α-oxoaldehyde at the intracellular level. Consumption of sugar and lipid (fat) enriched food increases the risk of developing metabolic diseases and cancers. However, lipids are essential molecules for life, as they are the major components of cell membranes. Metabolism refers to biochemical reactions that transform nutrients into molecules required by an organism, although toxic by-products can also formed. Sugars or their derivatives are likely to induce toxic effects by forming stable conjugates with proteins. To neutralize their toxic potential, sugars are metabolized and stored as fat. Here, we have used the fruitfly model to investigate the consequences of lipogenesis deficiency upon ingestion of sugar-enriched diets. We show that lipogenesis deficient animals are dramatically sensitive to dietary sugar. Further, we have identified the sugar by-product responsible for intracellular toxicity, in the context of lipogenesis inhibition. Our study reveals that inhibiting lipogenesis does not disrupt cellular growth if extracellular lipids are available. In contrast lipogenesis inhibition may have deleterious consequences due to accumulation of toxic by-products. The efficacy of lipogenic inhibitors in fighting cancers and metabolic diseases is currently under investigation. Therefore, to evaluate the clinical benefit of these inhibitors, accumulation of the toxic molecules should be monitored in both sick and healthy cells.
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231
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Chen J, Li L, Li Y, Liang X, Sun Q, Yu H, Zhong J, Ni Y, Chen J, Zhao Z, Gao P, Wang B, Liu D, Zhu Z, Yan Z. Activation of TRPV1 channel by dietary capsaicin improves visceral fat remodeling through connexin43-mediated Ca2+ influx. Cardiovasc Diabetol 2015; 14:22. [PMID: 25849380 PMCID: PMC4340344 DOI: 10.1186/s12933-015-0183-6] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Accepted: 01/24/2015] [Indexed: 02/06/2023] Open
Abstract
Background The prevalence of obesity has dramatically increased worldwide and has attracted rising attention, but the mechanism is still unclear. Previous studies revealed that transient receptor potential vanilloid 1 (TRPV1) channels take part in weight loss by enhancing intracellular Ca2+ levels. However, the potential mechanism of the effect of dietary capsaicin on obesity is not completely understood. Ca2+ transfer induced by connexin43 (Cx43) molecules between coupled cells takes part in adipocyte differentiation. Whether TRPV1-evoked alterations in Cx43-mediated adipocyte-to-adipocyte communication play a role in obesity is unknown. Materials and methods We investigated whether Cx43 participated in TRPV1-mediated adipocyte lipolysis in cultured 3T3-L1 preadipocytes and visceral adipose tissues from humans and wild-type (WT) and TRPV1-deficient (TRPV1-/-) mice. Results TRPV1 and Cx43 co-expressed in mesenteric adipose tissue. TRPV1 activation by capsaicin increased the influx of Ca2+ in 3T3-L1 preadipocytes and promoted cell lipolysis, as shown by Oil-red O staining. These effects were deficient when capsazepine, a TRPV1 antagonist, and 18 alpha-glycyrrhetinic acid (18α-GA), a gap-junction inhibitor, were administered. Long-term chronic dietary capsaicin reduced the weights of perirenal, mesenteric and testicular adipose tissues in WT mice fed a high-fat diet. Capsaicin increased the expression levels of p-CaM, Cx43, CaMKII, PPARδ and HSL in mesenteric adipose tissues from WT mice fed a high-fat diet, db/db mice, as well as obese humans, but these effects of capsaicin were absent in TRPV1-/- mice. Long-term chronic dietary capsaicin decreased the body weights and serum lipids of WT mice, but not TRPV1-/- mice, fed a high-fat diet. Conclusion This study demonstrated that capsaicin activation of TRPV1-evoked increased Ca2+ influx in Cx43-mediated adipocyte-to-adipocyte communication promotes lipolysis in both vitro and vivo. TRPV1 activation by dietary capsaicin improves visceral fat remodeling through the up-regulation of Cx43.
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232
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New insights into the pathophysiology of dyslipidemia in type 2 diabetes. Atherosclerosis 2015; 239:483-95. [PMID: 25706066 DOI: 10.1016/j.atherosclerosis.2015.01.039] [Citation(s) in RCA: 266] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 01/28/2015] [Accepted: 01/30/2015] [Indexed: 02/06/2023]
Abstract
Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality for patients with type 2 diabetes, despite recent significant advances in management strategies to lessen CVD risk factors. A major cause is the atherogenic dyslipidemia, which consists of elevated plasma concentrations of both fasting and postprandial triglyceride-rich lipoproteins (TRLs), small dense low-density lipoprotein (LDL) and low high-density lipoprotein (HDL) cholesterol. The different components of diabetic dyslipidemia are not isolated abnormalities but closely linked to each other metabolically. The underlying disturbances are hepatic overproduction and delayed clearance of TRLs. Recent results have unequivocally shown that triglyceride-rich lipoproteins and their remnants are atherogenic. To develop novel strategies for the prevention and treatment of dyslipidaemia, it is essential to understand the pathophysiology of dyslipoproteinaemia in humans. Here, we review recent advances in our understanding of the pathophysiology of diabetic dyslipidemia.
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233
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O'Sullivan D, Pearce EL. Fatty acid synthesis tips the TH17-Treg cell balance. Nat Med 2015; 20:1235-6. [PMID: 25375921 DOI: 10.1038/nm.3744] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- David O'Sullivan
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Erika L Pearce
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
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Lodhi IJ, Wei X, Yin L, Feng C, Adak S, Abou-Ezzi G, Hsu FF, Link DC, Semenkovich CF. Peroxisomal lipid synthesis regulates inflammation by sustaining neutrophil membrane phospholipid composition and viability. Cell Metab 2015; 21:51-64. [PMID: 25565205 PMCID: PMC4287274 DOI: 10.1016/j.cmet.2014.12.002] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 09/26/2014] [Accepted: 12/09/2014] [Indexed: 12/31/2022]
Abstract
Fatty acid synthase (FAS) is altered in metabolic disorders and cancer. Conventional FAS null mice die in utero, so effects of whole-body inhibition of lipogenesis following development are unknown. Inducible global knockout of FAS (iFASKO) in mice was lethal due to a disrupted intestinal barrier and leukopenia. Conditional loss of FAS was associated with the selective suppression of granulopoiesis without disrupting granulocytic differentiation. Transplantation of iFASKO bone marrow into wild-type mice followed by Cre induction resulted in selective neutrophil depletion, but not death. Impaired lipogenesis increased ER stress and apoptosis in neutrophils by preferentially decreasing peroxisome-derived membrane phospholipids containing ether bonds. Inducible global knockout of PexRAP, a peroxisomal enzyme required for ether lipid synthesis, also produced neutropenia. FAS knockdown in neutrophil-like HL-60 cells caused cell loss that was partially rescued by ether lipids. Inhibiting ether lipid synthesis selectively constrains neutrophil development, revealing an unrecognized pathway in immunometabolism.
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Affiliation(s)
- Irfan J Lodhi
- Division of Endocrinology, Metabolism & Lipid Research, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Xiaochao Wei
- Division of Endocrinology, Metabolism & Lipid Research, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Li Yin
- Division of Endocrinology, Metabolism & Lipid Research, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Chu Feng
- Division of Endocrinology, Metabolism & Lipid Research, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Sangeeta Adak
- Division of Endocrinology, Metabolism & Lipid Research, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Grazia Abou-Ezzi
- Oncology Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Fong-Fu Hsu
- Division of Endocrinology, Metabolism & Lipid Research, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Daniel C Link
- Oncology Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Clay F Semenkovich
- Division of Endocrinology, Metabolism & Lipid Research, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Cell Biology & Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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235
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Brockman DA, Chen X, Gallaher DD. High-viscosity dietary fibers reduce adiposity and decrease hepatic steatosis in rats fed a high-fat diet. J Nutr 2014; 144:1415-22. [PMID: 24991042 DOI: 10.3945/jn.114.191577] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Viscous dietary fiber consumption lowers the postprandial glucose curve and may decrease obesity and associated comorbidities such as insulin resistance and fatty liver. We determined the effect of 2 viscous fibers, one fermentable and one not, on the development of adiposity, fatty liver, and metabolic flexibility in a model of diet-induced obesity. Rats were fed a normal-fat (NF) diet (26% energy from fat), a high-fat diet (60% energy from fat), each containing 5% fiber as cellulose (CL; nonviscous and nonfermentable), or 5% of 1 of 2 highly viscous fibers-hydroxypropyl methylcellulose (HPMC; nonfermentable) or guar gum (GG; fermentable). After 10 wk, fat mass percentage in the NF (18.0%; P = 0.03) and GG groups (17.0%; P < 0.01) was lower than the CL group (20.7%). The epididymal fat pad weight of the NF (3.9 g; P = 0.04), HPMC (3.9 g; P = 0.03), and GG groups (3.6 g; P < 0.01) was also lower than the CL group (5.0 g). The HPMC (0.11 g/g liver) and GG (0.092 g/g liver) groups had lower liver lipid concentrations compared with the CL group (0.14 g/g liver). Fat mass percentage, epididymal fat pad weight, and liver lipid concentration were not different among the NF, HPMC, and GG groups. The respiratory quotient was higher during the transition from the diet-deprived to fed state in the GG group (P = 0.002) and tended to be higher in the HPMC group (P = 0.06) compared with the CL group, suggesting a quicker shift from fatty acid (FA) to carbohydrate oxidation. The HPMC group [15.1 nmol/(mg ⋅ h)] had higher ex vivo palmitate oxidation in muscle compared with the GG [11.7 nmol/(mg ⋅ h); P = 0.04] and CL groups [10.8 nmol/(mg ⋅ h); P < 0.01], implying a higher capacity to oxidize FAs. Viscous fibers can reduce the adiposity and hepatic steatosis that accompany a high-fat diet, and increase metabolic flexibility, regardless of fermentability.
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Affiliation(s)
- David A Brockman
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN
| | - Xiaoli Chen
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN
| | - Daniel D Gallaher
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN
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Ruscogenin ameliorates experimental nonalcoholic steatohepatitis via suppressing lipogenesis and inflammatory pathway. BIOMED RESEARCH INTERNATIONAL 2014; 2014:652680. [PMID: 25136608 PMCID: PMC4127260 DOI: 10.1155/2014/652680] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2014] [Accepted: 06/11/2014] [Indexed: 11/18/2022]
Abstract
The aim of the study was to investigate the protective effects of ruscogenin, a major steroid sapogenin in Ophiopogon japonicus, on experimental models of nonalcoholic steatohepatitis. HepG2 cells were exposed to 300 μmol/l palmitic acid (PA) for 24 h with the preincubation of ruscogenin for another 24 h. Ruscogenin (10.0 μmol/l) had inhibitory effects on PA-induced triglyceride accumulation and inflammatory markers in HepG2 cells. Male golden hamsters were randomly divided into five groups fed a normal diet, a high-fat diet (HFD), or a HFD supplemented with ruscogenin (0.3, 1.0, or 3.0 mg/kg/day) by gavage once daily for 8 weeks. Ruscogenin alleviated dyslipidemia, liver steatosis, and necroinflammation and reversed plasma markers of metabolic syndrome in HFD-fed hamsters. Hepatic mRNA levels involved in fatty acid oxidation were increased in ruscogenin-treated HFD-fed hamsters. Conversely, ruscogenin decreased expression of genes involved in hepatic lipogenesis. Gene expression of inflammatory cytokines, chemoattractive mediator, nuclear transcription factor-(NF-) κB, and α-smooth muscle actin were increased in the HFD group, which were attenuated by ruscogenin. Ruscogenin may attenuate HFD-induced steatohepatitis through downregulation of NF-κB-mediated inflammatory responses, reducing hepatic lipogenic gene expression, and upregulating proteins in β-oxidation pathway.
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237
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Ameer F, Scandiuzzi L, Hasnain S, Kalbacher H, Zaidi N. De novo lipogenesis in health and disease. Metabolism 2014; 63:895-902. [PMID: 24814684 DOI: 10.1016/j.metabol.2014.04.003] [Citation(s) in RCA: 337] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Revised: 04/01/2014] [Accepted: 04/06/2014] [Indexed: 12/19/2022]
Abstract
BACKGROUND De novo lipogenesis (DNL) is a complex and highly regulated metabolic pathway. In normal conditions DNL converts excess carbohydrate into fatty acids that are then esterified to storage triacylglycerols (TGs). These TGs could later provide energy via β-oxidation. In human body this pathway is primarily active in liver and adipose tissue. However, it is considered to be a minor contributor to the serum lipid homeostasis. Deregulations in the lipogenic pathway are associated with diverse pathological conditions. SCOPE OF REVIEW The present review focuses on our current understanding of the lipogenic pathway with special reference to the causes and consequences of aberrant DNL. MAJOR CONCLUSIONS The deregulation of DNL in the major lipogenic tissues of the human body is often observed in various metabolic anomalies - including obesity, non-alcoholic fatty liver disease and metabolic syndrome. In addition to that de novo lipogenesis is reported to be exacerbated in cancer tissues, virus infected cells etc. These observations suggest that inhibitors of the DNL pathway might serve as therapeutically significant compounds. The effectiveness of these inhibitors in treatment of cancer and obesity has been suggested by previous works. GENERAL SIGNIFICANCE De novo lipogenesis - which is an intricate and highly regulated pathway - can lead to adverse metabolic consequences when deregulated. Therapeutic targeting of this pathway may open a new window of opportunity for combating various lipogenesis-driven pathological conditions - including obesity, cancer and certain viral infections.
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Affiliation(s)
- Fatima Ameer
- Microbiology and Molecular Genetics, University of the Punjab, Lahore-54590, Pakistan
| | - Lisa Scandiuzzi
- Department of Radiation Oncology, 1300 Morris Park Avenue, 10461, Bronx, NY, USA
| | - Shahida Hasnain
- Microbiology and Molecular Genetics, University of the Punjab, Lahore-54590, Pakistan
| | - Hubert Kalbacher
- Medical and Natural Sciences Research Centre, University of Tubingen, Germany
| | - Nousheen Zaidi
- Microbiology and Molecular Genetics, University of the Punjab, Lahore-54590, Pakistan.
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Rashid S, Tavori H, Brown PE, Linton MF, He J, Giunzioni I, Fazio S. Proprotein convertase subtilisin kexin type 9 promotes intestinal overproduction of triglyceride-rich apolipoprotein B lipoproteins through both low-density lipoprotein receptor-dependent and -independent mechanisms. Circulation 2014; 130:431-41. [PMID: 25070550 DOI: 10.1161/circulationaha.113.006720] [Citation(s) in RCA: 111] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Proprotein convertase subtilisin kexin type 9 (PCSK9) promotes the degradation of the low-density lipoprotein (LDL) receptor (LDLR), and its deficiency in humans results in low plasma LDL cholesterol and protection against coronary heart disease. Recent evidence indicates that PCSK9 also modulates the metabolism of triglyceride-rich apolipoprotein B (apoB) lipoproteins, another important coronary heart disease risk factor. Here, we studied the effects of physiological levels of PCSK9 on intestinal triglyceride-rich apoB lipoprotein production and elucidated for the first time the cellular and molecular mechanisms involved. METHODS AND RESULTS Treatment of human enterocytes (CaCo-2 cells) with recombinant human PCSK9 (10 μg/mL for 24 hours) increased cellular and secreted apoB48 and apoB100 by 40% to 55% each (P<0.01 versus untreated cells), whereas short-term deletion of PCSK9 expression reversed this effect. PCSK9 stimulation of apoB was due to a 1.5-fold increase in apoB mRNA (P<0.01) and to enhanced apoB protein stability through both LDLR-dependent and LDLR-independent mechanisms. PCSK9 decreased LDLR protein (P<0.01) and increased cellular apoB stability via activation of microsomal triglyceride transfer protein. PCSK9 also increased levels of the lipid-generating enzymes FAS, SCD, and DGAT2 (P<0.05). In mice, human PCSK9 at physiological levels increased intestinal microsomal triglyceride transfer protein levels and activity regardless of LDLR expression. CONCLUSIONS PCSK9 markedly increases intestinal triglyceride-rich apoB production through mechanisms mediated in part by transcriptional effects on apoB, microsomal triglyceride transfer protein, and lipogenic genes and in part by posttranscriptional effects on the LDLR and microsomal triglyceride transfer protein. These findings indicate that targeted PCSK9-based therapies may also be effective in the management of postprandial hypertriglyceridemia.
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Affiliation(s)
- Shirya Rashid
- From the Department of Pharmacology, Dalhousie University, Halifax, NS, and Saint John, NB, Canada (S.R.); Department of Medicine, Section of Cardiovascular Disease Prevention, Vanderbilt University, Nashville, TN (H.T., M.F.L., J.H., I.G., S.F.); Oregon Health and Science University, Portland (H.T., I.G.); and Department of Biostatistics, Faculty of Medicine, University of Toronto and Cancer Care Ontario, Toronto, ON, Canada (P.E.B.).
| | - Hagai Tavori
- From the Department of Pharmacology, Dalhousie University, Halifax, NS, and Saint John, NB, Canada (S.R.); Department of Medicine, Section of Cardiovascular Disease Prevention, Vanderbilt University, Nashville, TN (H.T., M.F.L., J.H., I.G., S.F.); Oregon Health and Science University, Portland (H.T., I.G.); and Department of Biostatistics, Faculty of Medicine, University of Toronto and Cancer Care Ontario, Toronto, ON, Canada (P.E.B.)
| | - Patrick E Brown
- From the Department of Pharmacology, Dalhousie University, Halifax, NS, and Saint John, NB, Canada (S.R.); Department of Medicine, Section of Cardiovascular Disease Prevention, Vanderbilt University, Nashville, TN (H.T., M.F.L., J.H., I.G., S.F.); Oregon Health and Science University, Portland (H.T., I.G.); and Department of Biostatistics, Faculty of Medicine, University of Toronto and Cancer Care Ontario, Toronto, ON, Canada (P.E.B.)
| | - MacRae F Linton
- From the Department of Pharmacology, Dalhousie University, Halifax, NS, and Saint John, NB, Canada (S.R.); Department of Medicine, Section of Cardiovascular Disease Prevention, Vanderbilt University, Nashville, TN (H.T., M.F.L., J.H., I.G., S.F.); Oregon Health and Science University, Portland (H.T., I.G.); and Department of Biostatistics, Faculty of Medicine, University of Toronto and Cancer Care Ontario, Toronto, ON, Canada (P.E.B.)
| | - Jane He
- From the Department of Pharmacology, Dalhousie University, Halifax, NS, and Saint John, NB, Canada (S.R.); Department of Medicine, Section of Cardiovascular Disease Prevention, Vanderbilt University, Nashville, TN (H.T., M.F.L., J.H., I.G., S.F.); Oregon Health and Science University, Portland (H.T., I.G.); and Department of Biostatistics, Faculty of Medicine, University of Toronto and Cancer Care Ontario, Toronto, ON, Canada (P.E.B.)
| | - Ilaria Giunzioni
- From the Department of Pharmacology, Dalhousie University, Halifax, NS, and Saint John, NB, Canada (S.R.); Department of Medicine, Section of Cardiovascular Disease Prevention, Vanderbilt University, Nashville, TN (H.T., M.F.L., J.H., I.G., S.F.); Oregon Health and Science University, Portland (H.T., I.G.); and Department of Biostatistics, Faculty of Medicine, University of Toronto and Cancer Care Ontario, Toronto, ON, Canada (P.E.B.)
| | - Sergio Fazio
- From the Department of Pharmacology, Dalhousie University, Halifax, NS, and Saint John, NB, Canada (S.R.); Department of Medicine, Section of Cardiovascular Disease Prevention, Vanderbilt University, Nashville, TN (H.T., M.F.L., J.H., I.G., S.F.); Oregon Health and Science University, Portland (H.T., I.G.); and Department of Biostatistics, Faculty of Medicine, University of Toronto and Cancer Care Ontario, Toronto, ON, Canada (P.E.B.)
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Yan SL, Yang HT, Lee YJ, Lin CC, Chang MH, Yin MC. Asiatic acid ameliorates hepatic lipid accumulation and insulin resistance in mice consuming a high-fat diet. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2014; 62:4625-4631. [PMID: 24779966 DOI: 10.1021/jf501165z] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Effects of asiatic acid (AA) at 10 or 20 mg/kg/day upon hepatic steatosis in mice consuming a high-fat diet (HFD) were examined. AA intake decreased body weight, water intake, feed intake, epididymal fat, and plasma and hepatic triglyceride levels in HFD-treated mice (P < 0.05). HFD enhanced 2.85-fold acetyl coenzyme A carboxylase (ACC1), 3.34-fold fatty acid synthase (FAS), 3.71-fold stearoyl CoA desaturase (SCD)-1, 3.62-fold 3-hydroxy-3-methylglutaryl coenzyme A reductase, 2.91-fold sterol regulatory element-binding protein (SREBP)-1c, and 2.75-fold SREBP-2 expression in liver (P < 0.05). Compared with HFD groups, AA intake at two doses reduced 18.9-45.7% ACC1, 25.1-49.8% FAS, 24.7-57.1% SCD-1, and 21.8-53.3% SREBP-1c protein expression (P < 0.05). Histological results indicated AA intake at two doses reduced hepatic lipid accumulation and inflammatory infiltrate. HFD increased hepatic production of reactive oxygen species, interleukin (IL)-1β, IL-6, and tumor necrosis factor-α, as well as decreased hepatic glutathione content and glutathione peroxidase and catalase activities (P < 0.05). AA intake at two doses reversed these alterations (P < 0.05). AA intake suppressed 32.4-58.8% nuclear factor kappa (NF-κ)B p65 and 24.2-56.7% p-p38 expression (P < 0.05) and at high dose down-regulated 29.1% NF-κB p50 and 40.7% p-JNK expression in livers from HFD-treated mice. AA intake at two doses lowered plasma insulin secretion and HOMR-IR (P < 0.05). These results suggest that AA is a potent hepatic protective agent against HFD-induced hepatic injury.
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Affiliation(s)
- Sheng-Lei Yan
- Division of Gastroenterology, Department of Internal Medicine, Chang Bing Show-Chwan Memorial Hospital , Changhua County, Taiwan
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240
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Joseph LB, Heck DE, Cervelli JA, Composto GM, Babin MC, Casillas RP, Sinko PJ, Gerecke DR, Laskin DL, Laskin JD. Structural changes in hair follicles and sebaceous glands of hairless mice following exposure to sulfur mustard. Exp Mol Pathol 2014; 96:316-27. [PMID: 24662110 DOI: 10.1016/j.yexmp.2014.03.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Accepted: 03/12/2014] [Indexed: 01/08/2023]
Abstract
Sulfur mustard (SM) is a bifunctional alkylating agent causing skin inflammation, edema and blistering. A hallmark of SM-induced toxicity is follicular and interfollicular epithelial damage. In the present studies we determined if SM-induced structural alterations in hair follicles and sebaceous glands were correlated with cell damage, inflammation and wound healing. The dorsal skin of hairless mice was treated with saturated SM vapor. One to seven days later, epithelial cell karyolysis within the hair root sheath, infundibulum and isthmus was apparent, along with reduced numbers of sebocytes. Increased numbers of utriculi, some with connections to the skin surface, and engorged dermal cysts were also evident. This was associated with marked changes in expression of markers of DNA damage (phospho-H2A.X), apoptosis (cleaved caspase-3), and wound healing (FGFR2 and galectin-3) throughout pilosebaceous units. Conversely, fatty acid synthase and galectin-3 were down-regulated in sebocytes after SM. Decreased numbers of hair follicles and increased numbers of inflammatory cells surrounding the utriculi and follicular cysts were noted within the wound 3-7 days post-SM exposure. Expression of phospho-H2A.X, cleaved caspase-3, FGFR2 and galectin-3 was decreased in dysplastic follicular epidermis. Fourteen days after SM, engorged follicular cysts which expressed galectin-3 were noted within hyperplastic epidermis. Galectin-3 was also expressed in basal keratinocytes and in the first few layers of suprabasal keratinocytes in neoepidermis formed during wound healing indicating that this lectin is important in the early stages of keratinocyte differentiation. These data indicate that hair follicles and sebaceous glands are targets for SM in the skin.
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Affiliation(s)
- Laurie B Joseph
- Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ, United States.
| | - Diane E Heck
- Environmental Health Science, New York Medical College, Valhalla, NY, United States
| | - Jessica A Cervelli
- Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ, United States
| | - Gabriella M Composto
- Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ, United States
| | | | | | - Patrick J Sinko
- Department of Pharmaceutics, Rutgers University, Piscataway, NJ, United States
| | - Donald R Gerecke
- Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ, United States
| | - Debra L Laskin
- Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ, United States
| | - Jeffrey D Laskin
- Environmental and Occupational Medicine, Rutgers University - Robert Wood Johnson Medical School, Piscataway, NJ, United States
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241
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Scheving LA, Zhang X, Garcia OA, Wang RF, Stevenson MC, Threadgill DW, Russell WE. Epidermal growth factor receptor plays a role in the regulation of liver and plasma lipid levels in adult male mice. Am J Physiol Gastrointest Liver Physiol 2014; 306:G370-81. [PMID: 24407590 PMCID: PMC3949019 DOI: 10.1152/ajpgi.00116.2013] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Dsk5 mice have a gain of function in the epidermal growth factor receptor (EGFR), caused by a point mutation in the kinase domain. We analyzed the effect of this mutation on liver size, histology, and composition. We found that the livers of 12-wk-old male Dsk5 heterozygotes (+/Dsk5) were 62% heavier compared with those of wild-type controls (+/+). The livers of the +/Dsk5 mice compared with +/+ mice had larger hepatocytes with prominent, polyploid nuclei and showed modestly increased cell proliferation indices in both hepatocytes and nonparenchymal cells. An analysis of total protein, DNA, and RNA (expressed relative to liver weight) revealed no differences between the mutant and wild-type mice. However, the livers of the +/Dsk5 mice had more cholesterol but less phospholipid and fatty acid. Circulating cholesterol levels were twice as high in adult male +/Dsk5 mice but not in postweaned young male or female mice. The elevated total plasma cholesterol resulted mainly from an increase in low-density lipoprotein (LDL). The +/Dsk5 adult mouse liver expressed markedly reduced protein levels of LDL receptor, no change in proprotein convertase subtilisin/kexin type 9, and a markedly increased fatty acid synthase and 3-hydroxy-3-methyl-glutaryl-CoA reductase. Increased expression of transcription factors associated with enhanced cholesterol synthesis was also observed. Together, these findings suggest that the EGFR may play a regulatory role in hepatocyte proliferation and lipid metabolism in adult male mice, explaining why elevated levels of EGF or EGF-like peptides have been positively correlated to increased cholesterol levels in human studies.
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Affiliation(s)
| | | | | | | | | | - David W. Threadgill
- 6Department of Genetics, North Carolina State University, Raleigh, North Carolina
| | - William E. Russell
- 1Departments of Pediatrics, ,2Cell and Developmental Biology, ,3Digestive Disease Research Center, ,4Vanderbilt Diabetes Center, ,5Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee;
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242
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Everts B, Amiel E, Huang SCC, Smith AM, Chang CH, Lam WY, Redmann V, Freitas TC, Blagih J, van der Windt GJW, Artyomov MN, Jones RG, Pearce EL, Pearce EJ. TLR-driven early glycolytic reprogramming via the kinases TBK1-IKKɛ supports the anabolic demands of dendritic cell activation. Nat Immunol 2014; 15:323-32. [PMID: 24562310 DOI: 10.1038/ni.2833] [Citation(s) in RCA: 794] [Impact Index Per Article: 79.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 01/24/2014] [Indexed: 12/14/2022]
Abstract
The ligation of Toll-like receptors (TLRs) leads to rapid activation of dendritic cells (DCs). However, the metabolic requirements that support this process remain poorly defined. We found that DC glycolytic flux increased within minutes of exposure to TLR agonists and that this served an essential role in supporting the de novo synthesis of fatty acids for the expansion of the endoplasmic reticulum and Golgi required for the production and secretion of proteins that are integral to DC activation. Signaling via the kinases TBK1, IKKɛ and Akt was essential for the TLR-induced increase in glycolysis by promoting the association of the glycolytic enzyme HK-II with mitochondria. In summary, we identified the rapid induction of glycolysis as an integral component of TLR signaling that is essential for the anabolic demands of the activation and function of DCs.
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Affiliation(s)
- Bart Everts
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Eyal Amiel
- Department of Medical Laboratory and Radiation Sciences, University of Vermont, Burlington, Vermont, USA
| | - Stanley Ching-Cheng Huang
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Amber M Smith
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Chih-Hao Chang
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Wing Y Lam
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Veronika Redmann
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
| | | | | | - Gerritje J W van der Windt
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Maxim N Artyomov
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Russell G Jones
- Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - Erika L Pearce
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Edward J Pearce
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
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243
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Fetal and neonatal exposure to nicotine leads to augmented hepatic and circulating triglycerides in adult male offspring due to increased expression of fatty acid synthase. Toxicol Appl Pharmacol 2013; 275:1-11. [PMID: 24368177 DOI: 10.1016/j.taap.2013.12.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 12/09/2013] [Accepted: 12/12/2013] [Indexed: 12/25/2022]
Abstract
While nicotine replacement therapy is assumed to be a safer alternative to smoking during pregnancy, the long-term consequences for the offspring remain elusive. Animal studies now suggest that maternal nicotine exposure during perinatal life leads to a wide range of adverse outcomes for the offspring including increased adiposity. The focus of this study was to investigate if nicotine exposure during pregnancy and lactation leads to alterations in hepatic triglyceride synthesis. Female Wistar rats were randomly assigned to receive daily subcutaneous injections of saline (vehicle) or nicotine bitartrate (1mg/kg/day) for two weeks prior to mating until weaning. At postnatal day 180 (PND 180), nicotine exposed offspring exhibited significantly elevated levels of circulating and hepatic triglycerides in the male offspring. This was concomitant with increased expression of fatty acid synthase (FAS), the critical hepatic enzyme in de novo triglyceride synthesis. Given that FAS is regulated by the nuclear receptor Liver X receptor (LXRα), we measured LXRα expression in both control and nicotine-exposed offspring. Nicotine exposure during pregnancy and lactation led to an increase in hepatic LXRα protein expression and enriched binding to the putative LXRE element on the FAS promoter in PND 180 male offspring. This was also associated with significantly enhanced acetylation of histone H3 [K9,14] surrounding the FAS promoter, a hallmark of chromatin activation. Collectively, these findings suggest that nicotine exposure during pregnancy and lactation leads to an increase in circulating and hepatic triglycerides long-term via changes in the transcriptional and epigenetic regulation of the hepatic lipogenic pathway.
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244
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Chang CJ, Liou SS, Tzeng TF, Liu IM. The ethanol extract of Zingiber zerumbet Smith attenuates non-alcoholic fatty liver disease in hamsters fed on high-fat diet. Food Chem Toxicol 2013; 65:33-42. [PMID: 24342243 DOI: 10.1016/j.fct.2013.11.048] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Revised: 10/25/2013] [Accepted: 11/29/2013] [Indexed: 12/30/2022]
Abstract
The beneficial effects of the ethanol extract of Zingiber zerumbet rhizome (EEZZR) for use in the treatment of non-alcoholic fatty liver disease (NAFLD) were investigated. Syrian golden hamsters were fed a high-fat diet to induce NAFLD. EEZZR (100, 200, or 300mg/kg) were orally administered by gavage once daily for 8weeks. The higher plasma levels of total cholesterol, triglycerides, free fatty acids, and hepatic lipids, as well as the degree of insulin resistance were lowered by EEZZR. Histological evaluation of liver specimens demonstrated that the hepatic steatosis of EEZZR-treated groups was improved. EEZZR decreased hepatic mRNA levels of sterol regulatory element-binding protein-1c and its lipogenic target genes. The hepatic mRNA expression of peroxisome proliferator-activated receptor α, together with its target genes responsible for β-oxidation of fatty acids were also upregulated by EEZZR. In conclusion, these findings suggest that EEZZR has the promising potential to ameliorate NAFLD.
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Affiliation(s)
- Chia Ju Chang
- Department of Pharmacy & Graduate Institute of Pharmaceutical Technology, Tajen University, Yanpu Shiang, Ping Tung Shien, Taiwan, ROC
| | - Shorong-Shii Liou
- Department of Pharmacy & Graduate Institute of Pharmaceutical Technology, Tajen University, Yanpu Shiang, Ping Tung Shien, Taiwan, ROC
| | - Thing-Fong Tzeng
- Department of Pharmacy & Graduate Institute of Pharmaceutical Technology, Tajen University, Yanpu Shiang, Ping Tung Shien, Taiwan, ROC
| | - I-Min Liu
- Department of Pharmacy & Graduate Institute of Pharmaceutical Technology, Tajen University, Yanpu Shiang, Ping Tung Shien, Taiwan, ROC.
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245
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Higley E, Tompsett AR, Giesy JP, Hecker M, Wiseman S. Effects of triphenyltin on growth and development of the wood frog (Lithobates sylvaticus). AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2013; 144-145:155-161. [PMID: 24177218 DOI: 10.1016/j.aquatox.2013.09.029] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 09/24/2013] [Accepted: 09/28/2013] [Indexed: 06/02/2023]
Abstract
Exposure to contaminants in the environment has been suggested as a contributing cause of ongoing declines in populations of amphibians reported in certain locations around the world. In the current study, responses of the wood frog (Lithobates sylvaticus) to exposure to triphenyltin (TPT), a commonly used fungicide, during the larval period were characterized. Exposure of L. sylvaticus to 0.1, 1.0, or 5.0 μg TPT/L significantly affected survival, growth, days to metamorphosis (DTM), and abundances of transcripts of genes of interest. After seven days of exposure there were no significant effects on survival, but masses and snout-ventral length (SVL) of larvae exposed to 5.0 μg TPT/L were significantly lesser than controls. Mortality of larvae after exposure to 5.0 μg TPT/L was 100% nine days after initiation of the experiment. Larvae exposed to 0.1 or 1.0 μg TPT/L were allowed to grow for 100 days or until they reached metamorphic climax, whichever occurred earlier. Mortality of wood frogs exposed to 1.0 μg TPT/L was 80%. The LC20 or LC50 after 100 days of exposure was 0.12 or 0.34 μg TPT/L, respectively. However, DTM of larvae that survived exposure to 1.0μgTPT/L was significantly less than that of controls. Abundances of transcripts of retinoid-X-receptor (rxr) and perixosomal proliferation receptor gamma (pparγ) were significantly lesser in larvae exposed to either concentration of TPT for seven days. Also, abundances of transcripts of stearoyl-CoA desaturase-1 (scd1), fatty acid synthase (fas), lipoprotein lipase (lpl), and β-hydroxybutyrate dehydrogenase (β-hb-m) were lesser in larvae exposed to 5.0 μg TPT/L, which suggested that disruption of lipid metabolism might have affected survival in this exposure group. However, in larvae that survived to metamorphic climax during exposure to TPT for as long as 100 days, abundances of transcripts of perixosomal proliferation receptor alpha (pparα), pparγ, cytochrome p4504B1 (cyp4b1), fas, and lpl were greater than in controls, suggesting that an up-regulation of processes related to metabolism of lipids might have been important for survival and development of these animals. Overall, concentrations of TPT that are found in the environment had a significant effect on the survival and development of L. sylvaticus, and this might have been due, in part, to effects on metabolism of lipids.
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Affiliation(s)
- Eric Higley
- Toxicology Centre, University of Saskatchewan, Saskatoon, SK, Canada S7N 5B3
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246
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The small molecule indirubin-3'-oxime activates Wnt/β-catenin signaling and inhibits adipocyte differentiation and obesity. Int J Obes (Lond) 2013; 38:1044-52. [PMID: 24232498 PMCID: PMC4125748 DOI: 10.1038/ijo.2013.209] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 10/10/2013] [Accepted: 11/04/2013] [Indexed: 01/21/2023]
Abstract
Objectives: Activation of the Wnt/β-catenin signaling pathway inhibits adipogenesis by maintaining preadipocytes in an undifferentiated state. We investigated the effect of indirubin-3′-oxime (I3O), which was screened as an activator of the Wnt/β-catenin signaling, on inhibiting the preadipocyte differentiation in vitro and in vivo. Methods: 3T3L1 preadipocytes were differentiated with 0, 4 or 20 μM of I3O. The I3O effect on adipocyte differentiation was observed by Oil-red-O staining. Activation of Wnt/β-catenin signaling in I3O-treated 3T3L1 cells was shown using immunocytochemical and immunoblotting analyses for β-catenin. The regulation of adipogenic markers was analyzed via real-time reverse transcription-PCR (RT-PCR) and immunoblotting analyses. For the in vivo study, mice were divided into five different dietary groups: chow diet, high-fat diet (HFD), HFD supplemented with I3O at 5, 25 and 100 mg kg−1. After 8 weeks, adipose and liver tissues were excised from the mice and subject to morphometry, real-time RT-PCR, immunoblotting and histological or immunohistochemical analyses. In addition, adipokine and insulin concentrations in serum of the mice were accessed by enzyme-linked immunosorbent assay. Results: Using a cell-based approach to screen a library of pharmacologically active small molecules, we identified I3O as a Wnt/β-catenin pathway activator. I3O inhibited the differentiation of 3T3-L1 cells into mature adipocytes and decreased the expression of adipocyte markers, CCAAT/enhancer-binding protein α and peroxisome proliferator-activated receptor γ, at both mRNA and protein levels. In vivo, I3O inhibited the development of obesity in HFD-fed mice by attenuating HFD-induced body weight gain and visceral fat accumulation without showing any significant toxicity. Factors associated with metabolic disorders such as hyperlipidemia and hyperglycemia were also improved by treatment of I3O. Conclusion: Activation of the Wnt/β-catenin signaling pathway can be used as a therapeutic strategy for the treatment of obesity and metabolic syndrome and implicates I3O as a candidate anti-obesity agent.
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247
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Zerumbone, a Natural Cyclic Sesquiterpene of Zingiber zerumbet Smith, Attenuates Nonalcoholic Fatty Liver Disease in Hamsters Fed on High-Fat Diet. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:303061. [PMID: 24223615 PMCID: PMC3810186 DOI: 10.1155/2013/303061] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Accepted: 08/08/2013] [Indexed: 12/18/2022]
Abstract
We investigated the effects of zerumbone, a natural cyclic sesquiterpene, on hepatic lipid metabolism in Syrian golden hamsters fed on high-fat diet (HFD). After being fed HFD for 2 weeks, hamsters were dosed orally with zerumbone (75, 150, and 300 mg kg(-1)) once daily for 8 weeks. After treatment with zerumbone, the plasma levels of total cholesterol (TC) and triglycerides (TGs) and the contents of TC and TG in hepatic tissue as well as homeostasis model assessment of insulin resistance were lowered, especially in the zerumbone-treated group (300 mg kg(-1)). Moreover, the histological evaluation of liver specimens demonstrated that the steatosis and inflammation in liver of zerumbone-treated groups were improved. Zerumbone exhibited the ability to decrease hepatic mRNA levels of sterol regulatory element-binding protein-1c and its lipogenic target genes, such as fatty acid synthase, acetyl-CoA carboxylase 1, and stearoyl-CoA desaturase 1. The hepatic mRNA expression of peroxisome proliferator-activated receptor α , together with its target genes including carnitine palmitoyl transferase-1, acyl-CoA oxidase, and acyl-CoA oxidase 1, was also upregulated by zerumbone. In conclusion, zerumbone improves insulin sensitivity, decreases lipogenesis, and increases lipid oxidation in the liver of HFD-fed hamsters, implying a potential application in the treatment of nonalcoholic fatty liver disease.
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248
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Li Q, Li L, Wang F, Chen J, Zhao Y, Wang P, Nilius B, Liu D, Zhu Z. Dietary capsaicin prevents nonalcoholic fatty liver disease through transient receptor potential vanilloid 1-mediated peroxisome proliferator-activated receptor δ activation. Pflugers Arch 2013; 465:1303-16. [PMID: 23605066 DOI: 10.1007/s00424-013-1274-4] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 03/19/2013] [Indexed: 02/06/2023]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is characterized by hepatic lipid deposition and coincides often with cardiometabolic diseases. Several dietary factors attenuate NAFLD. Here, we report beneficial effects of chronic dietary capsaicin intake on NAFLD which is mediated by the transient receptor potential vanilloid 1 (TRPV1) activation. The results showed that TRPV1 activation by capsaicin reduced free fatty acids (FFAs) induced the intracellular lipid droplets in HepG2 cells and prevented fatty liver in vivo. Chronic dietary capsaicin promoted lipolysis by increasing hepatic phosphorylated hormone-sensitive lipase (phospho-HSL), carnitine palmitoyltransferase 1 (CPT1), and peroxisome proliferator-activated receptor δ (PPARδ) in wild-type (WT) mice. This effect was absent in TRPV1(-/-) mice. Dietary capsaicin did not affect lipogenesis, as indicated by the detection of hepatic fatty acid synthase (FAS), sterol regulatory element-binding protein-1 (SREBP-1), PPARα, and liver X receptor (LXR) in mice. Importantly, TRPV1 causes PPARδ activation which significantly increased the expression of autophagy-related proteins, such as light chain 3 (LC3)II, Beclin1, Atg5, and Atg7 in HepG2 cells. In the in vivo study, TRPV1 activation by dietary capsaicin enhanced hepatic PPARδ and autophagy-related proteins and reduced hepatic enzymes and inflammatory factor in WT but not TRPV1(-/-) mice. TRPV1 activation by dietary capsaicin prevents NAFLD through PPARδ-dependent autophagy enhancement in mice. Dietary capsaicin may represent a beneficial intervention in populations at high risk for NAFLD.
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Affiliation(s)
- Qiang Li
- Center for Hypertension and Metabolic Diseases, Department of Hypertension and Endocrinology, Daping Hospital, Third Military Medical University, Chongqing Institute of Hypertension, Chongqing 400042, China
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249
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Jensen-Urstad APL, Song H, Lodhi IJ, Funai K, Yin L, Coleman T, Semenkovich CF. Nutrient-dependent phosphorylation channels lipid synthesis to regulate PPARα. J Lipid Res 2013; 54:1848-59. [PMID: 23585690 DOI: 10.1194/jlr.m036103] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Peroxisome proliferator-activated receptor (PPAR)α is a nuclear receptor that coordinates liver metabolism during fasting. Fatty acid synthase (FAS) is an enzyme that stores excess calories as fat during feeding, but it also activates hepatic PPARα by promoting synthesis of an endogenous ligand. Here we show that the mechanism underlying this paradoxical relationship involves the differential regulation of FAS in at least two distinct subcellular pools: cytoplasmic and membrane-associated. In mouse liver and cultured hepatoma cells, the ratio of cytoplasmic to membrane FAS-specific activity was increased with fasting, indicating higher cytoplasmic FAS activity under conditions associated with PPARα activation. This effect was due to a nutrient-dependent and compartment-selective covalent modification of FAS. Cytoplasmic FAS was preferentially phosphorylated during feeding or insulin treatment at Thr-1029 and Thr-1033, which flank a dehydratase domain catalytic residue. Mutating these sites to alanines promoted PPARα target gene expression. Rapamycin-induced inhibition of mammalian/mechanistic target of rapamycin complex 1 (mTORC1), a mediator of the feeding/insulin signal to induce lipogenesis, reduced FAS phosphorylation, increased cytoplasmic FAS enzyme activity, and increased PPARα target gene expression. Rapamycin-mediated induction of the same gene was abrogated with FAS knockdown. These findings suggest that hepatic FAS channels lipid synthesis through specific subcellular compartments that allow differential gene expression based on nutritional status.
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250
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Funai K, Song H, Yin L, Lodhi IJ, Wei X, Yoshino J, Coleman T, Semenkovich CF. Muscle lipogenesis balances insulin sensitivity and strength through calcium signaling. J Clin Invest 2013; 123:1229-40. [PMID: 23376793 DOI: 10.1172/jci65726] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Accepted: 12/14/2012] [Indexed: 12/24/2022] Open
Abstract
Exogenous dietary fat can induce obesity and promote diabetes, but endogenous fat production is not thought to affect skeletal muscle insulin resistance, an antecedent of metabolic disease. Unexpectedly, the lipogenic enzyme fatty acid synthase (FAS) was increased in the skeletal muscle of mice with diet-induced obesity and insulin resistance. Skeletal muscle-specific inactivation of FAS protected mice from insulin resistance without altering adiposity, specific inflammatory mediators of insulin signaling, or skeletal muscle levels of diacylglycerol or ceramide. Increased insulin sensitivity despite high-fat feeding was driven by activation of AMPK without affecting AMP content or the AMP/ATP ratio in resting skeletal muscle. AMPK was induced by elevated cytosolic calcium caused by impaired sarco/endoplasmic reticulum calcium ATPase (SERCA) activity due to altered phospholipid composition of the sarcoplasmic reticulum (SR), but came at the expense of decreased muscle strength. Thus, inhibition of skeletal muscle FAS prevents obesity-associated diabetes in mice, but also causes muscle weakness, which suggests that mammals have retained the capacity for lipogenesis in muscle to preserve physical performance in the setting of disrupted metabolic homeostasis.
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Affiliation(s)
- Katsuhiko Funai
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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