101
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Zhang YY, Li C, Yao GF, Du LJ, Liu Y, Zheng XJ, Yan S, Sun JY, Liu Y, Liu MZ, Zhang X, Wei G, Tong W, Chen X, Wu Y, Sun S, Liu S, Ding Q, Yu Y, Yin H, Duan SZ. Deletion of Macrophage Mineralocorticoid Receptor Protects Hepatic Steatosis and Insulin Resistance Through ERα/HGF/Met Pathway. Diabetes 2017; 66:1535-1547. [PMID: 28325853 PMCID: PMC5860190 DOI: 10.2337/db16-1354] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 03/13/2017] [Indexed: 12/20/2022]
Abstract
Although the importance of macrophages in nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes mellitus (T2DM) has been recognized, how macrophages affect hepatocytes remains elusive. Mineralocorticoid receptor (MR) has been implicated to play important roles in NAFLD and T2DM. However, cellular and molecular mechanisms are largely unknown. We report that myeloid MR knockout (MRKO) improves glucose intolerance, insulin resistance, and hepatic steatosis in obese mice. Estrogen signaling is sufficient and necessary for such improvements. Hepatic gene and protein expression suggests that MRKO reduces hepatic lipogenesis and lipid storage. In the presence of estrogen, MRKO in macrophages decreases lipid accumulation and increases insulin sensitivity of hepatocytes through hepatocyte growth factor (HGF)/Met signaling. MR directly regulates estrogen receptor 1 (Esr1 [encoding ERα]) in macrophages. Knockdown of hepatic Met eliminates the beneficial effects of MRKO in female obese mice. These findings identify a novel MR/ERα/HGF/Met pathway that conveys metabolic signaling from macrophages to hepatocytes in hepatic steatosis and insulin resistance and provide potential new therapeutic strategies for NAFLD and T2DM.
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Affiliation(s)
- Yu-Yao Zhang
- Laboratory of Oral Microbiology, Shanghai Research Institute of Stomatology, Ninth People's Hospital, School of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai, China
| | - Chao Li
- Laboratory of Oral Microbiology, Shanghai Research Institute of Stomatology, Ninth People's Hospital, School of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai, China
| | - Gao-Feng Yao
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai, China
| | - Lin-Juan Du
- Laboratory of Oral Microbiology, Shanghai Research Institute of Stomatology, Ninth People's Hospital, School of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai, China
| | - Yuan Liu
- Laboratory of Oral Microbiology, Shanghai Research Institute of Stomatology, Ninth People's Hospital, School of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai, China
| | - Xiao-Jun Zheng
- Laboratory of Oral Microbiology, Shanghai Research Institute of Stomatology, Ninth People's Hospital, School of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai, China
| | - Shuai Yan
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai, China
| | - Jian-Yong Sun
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai, China
| | - Yan Liu
- Laboratory of Oral Microbiology, Shanghai Research Institute of Stomatology, Ninth People's Hospital, School of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ming-Zhu Liu
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai, China
| | - Xiaoran Zhang
- Key Laboratory of Computational Biology, CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Gang Wei
- Key Laboratory of Computational Biology, CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Wenxin Tong
- Department of Infectious Diseases, Ren-Min Hospital of Wuhan University, Wuhan, China
| | - Xiaobei Chen
- Department of Infectious Diseases, Ren-Min Hospital of Wuhan University, Wuhan, China
| | - Yong Wu
- Division of Cancer Research and Training, Department of Internal Medicine, Charles R. Drew University of Medicine and Science, Los Angeles, CA
- David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA
| | - Shuyang Sun
- Shanghai Key Laboratory of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Department of Oral and Maxillofacial-Head Neck Oncology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Suling Liu
- Shanghai Cancer Center and Institutes of Biomedical Sciences, Key Laboratory of Breast Cancer in Shanghai, Cancer Institute, Fudan University, Shanghai, China
| | - Qiurong Ding
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai, China
| | - Ying Yu
- Department of Pharmacology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin, China
| | - Huiyong Yin
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai, China
| | - Sheng-Zhong Duan
- Laboratory of Oral Microbiology, Shanghai Research Institute of Stomatology, Ninth People's Hospital, School of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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102
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Leoni V, Nury T, Vejux A, Zarrouk A, Caccia C, Debbabi M, Fromont A, Sghaier R, Moreau T, Lizard G. Mitochondrial dysfunctions in 7-ketocholesterol-treated 158N oligodendrocytes without or with α-tocopherol: Impacts on the cellular profil of tricarboxylic cycle-associated organic acids, long chain saturated and unsaturated fatty acids, oxysterols, cholesterol and cholesterol precursors. J Steroid Biochem Mol Biol 2017; 169:96-110. [PMID: 27020660 DOI: 10.1016/j.jsbmb.2016.03.029] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2015] [Revised: 03/21/2016] [Accepted: 03/22/2016] [Indexed: 11/28/2022]
Abstract
In multiple sclerosis (MS) a process of white matter degradation leading to demyelination is observed. Oxidative stress, inflammation, apoptosis, necrosis and/or autophagy result together into a progressive loss of oligodendrocytes. 7-ketocholesterol (7KC), found increased in the cerebrospinal fluid of MS patients, triggers a rupture of RedOx homeostasis associated with mitochondrial dysfunctions, aptoptosis and autophagy (oxiapoptophagy) in cultured murine oligodendrocytes (158N). α-tocopherol is able to mild the alterations induced by 7KC partially restoring the cellular homeostasis. In presence of 7KC, the amount of adherent 158N cells was decreased and oxidative stress was enhanced. An increase of caspase-3 and PARP degradation (evidences of apoptosis), and an increased LC3-II/LC3-I ratio (criterion of autophagy), were detected. These events were associated with a decrease of the mitochondrial membrane potential (ΔΨm) and by a decrease of oxidative phosphorylation revealed by reduced NAD+ and ATP. The cellular lactate was higher while pyruvate, citrate, fumarate, succinate (tricarboxylic acid (TCA) cycle intermediates) were significantly reduced in exposed cells, suggesting that an impairment of mitochondrial respiratory functions could lead to an increase of lactate production and to a reduced amount of ATP and acetyl-CoA available for the anabolic pathways. The concentration of sterol precursors lathosterol, lanosterol and desmosterol were significantly reduced together with satured and unsatured long chain fatty acids (C16:0 - C18:0, structural elements of membrane phospholipids). Such reductions were milder with α-tocopherol. It is likely that the cell death induced by 7KC is associated with mitochondrial dysfunctions, including alterations of oxidative phosphorylation, which could result from lipid anabolism dysfunctions, especially on TCA cycle intermediates. A better knowledge of mitochondrial associated dysfunctions triggered by 7KC will contribute to bring new information on the demyelination processes which are linked with oxidative stress and lipid peroxidation, especially in MS.
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Affiliation(s)
- Valerio Leoni
- Laboratory of Clinical Chemistry, Hospital of Varese, ASST-Settelaghi, Varese, Italy; Laboratory of Clinical Pathology, Foundation IRCCS Istituto Neurologico Carlo Besta, Milan, Italy.
| | - Thomas Nury
- Biochemistry of the Peroxisome, Inflammation and Lipid Metabolism' EA 7270/Univ. Bourgogne Franche Comté/INSERM, Dijon, France
| | - Anne Vejux
- Biochemistry of the Peroxisome, Inflammation and Lipid Metabolism' EA 7270/Univ. Bourgogne Franche Comté/INSERM, Dijon, France
| | - Amira Zarrouk
- Biochemistry of the Peroxisome, Inflammation and Lipid Metabolism' EA 7270/Univ. Bourgogne Franche Comté/INSERM, Dijon, France; Univ. Monastir, Faculty of Medicine, LR12ES05, Lab-NAFS 'Nutrition - Functional Food & Vascular Health', Monastir, & Univ. Sousse, Faculty of Medicine, Sousse, Tunisia
| | - Claudio Caccia
- Laboratory of Clinical Pathology, Foundation IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Meryam Debbabi
- Biochemistry of the Peroxisome, Inflammation and Lipid Metabolism' EA 7270/Univ. Bourgogne Franche Comté/INSERM, Dijon, France; Univ. Monastir, Faculty of Medicine, LR12ES05, Lab-NAFS 'Nutrition - Functional Food & Vascular Health', Monastir, & Univ. Sousse, Faculty of Medicine, Sousse, Tunisia
| | - Agnès Fromont
- Department of Neurology, Univ. Hospital/Univ. Bourgogne Franche Comté, Dijon, France
| | - Randa Sghaier
- Biochemistry of the Peroxisome, Inflammation and Lipid Metabolism' EA 7270/Univ. Bourgogne Franche Comté/INSERM, Dijon, France; Univ. Monastir, Faculty of Medicine, LR12ES05, Lab-NAFS 'Nutrition - Functional Food & Vascular Health', Monastir, & Univ. Sousse, Faculty of Medicine, Sousse, Tunisia
| | - Thibault Moreau
- Department of Neurology, Univ. Hospital/Univ. Bourgogne Franche Comté, Dijon, France
| | - Gérard Lizard
- Biochemistry of the Peroxisome, Inflammation and Lipid Metabolism' EA 7270/Univ. Bourgogne Franche Comté/INSERM, Dijon, France.
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103
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Nie L, Shuai L, Zhu M, Liu P, Xie ZF, Jiang S, Jiang HW, Li J, Zhao Y, Li JY, Tan M. The Landscape of Histone Modifications in a High-Fat Diet-Induced Obese (DIO) Mouse Model. Mol Cell Proteomics 2017; 16:1324-1334. [PMID: 28450421 DOI: 10.1074/mcp.m117.067553] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Revised: 04/20/2017] [Indexed: 12/24/2022] Open
Abstract
Type 2 diabetes (T2D) is a major chronic healthcare concern worldwide. Emerging evidence suggests that a histone-modification-mediated epigenetic mechanism underlies T2D. Nevertheless, the dynamics of histone marks in T2D have not yet been carefully analyzed. Using a mass spectrometry-based label-free and chemical stable isotope labeling quantitative proteomic approach, we systematically profiled liver histone post-translational modifications (PTMs) in a prediabetic high-fat diet-induced obese (DIO) mouse model. We identified 170 histone marks, 30 of which were previously unknown. Interestingly, about 30% of the histone marks identified in DIO mouse liver belonged to a set of recently reported lysine acylation modifications, including propionylation, butyrylation, malonylation, and succinylation, suggesting possible roles of these newly identified histone acylations in diabetes and obesity. These histone marks were detected without prior affinity enrichment with an antibody, demonstrating that the histone acylation marks are present at reasonably high stoichiometry. Fifteen histone marks differed in abundance in DIO mouse liver compared with liver from chow-fed mice in label-free quantification, and six histone marks in stable isotope labeling quantification. Analysis of hepatic histone modifications from metformin-treated DIO mice revealed that metformin, a drug widely used for T2D, could reverse DIO-stimulated histone H3K36me2 in prediabetes, suggesting that this mark is likely associated with T2D development. Our study thus offers a comprehensive landscape of histone marks in a prediabetic mouse model, provides a resource for studying epigenetic functions of histone modifications in obesity and T2D, and suggest a new epigenetic mechanism for the physiological function of metformin.
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Affiliation(s)
- Litong Nie
- From the ‡The Chemical Proteomics Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China, 201203.,§State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China, 201203.,¶University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Lin Shuai
- §State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China, 201203.,¶University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Mingrui Zhu
- From the ‡The Chemical Proteomics Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China, 201203.,§State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China, 201203.,¶University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Ping Liu
- From the ‡The Chemical Proteomics Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China, 201203.,§State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China, 201203
| | - Zhi-Fu Xie
- §State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China, 201203.,¶University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Shangwen Jiang
- From the ‡The Chemical Proteomics Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China, 201203.,§State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China, 201203
| | - Hao-Wen Jiang
- ‖College of Chemistry and Molecular Engineering, East China Normal University, China, 200062
| | - Jia Li
- §State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China, 201203
| | - Yingming Zhao
- From the ‡The Chemical Proteomics Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China, 201203.,§State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China, 201203.,**Ben May Department for Cancer Research, University of Chicago, Chicago, IL
| | - Jing-Ya Li
- §State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China, 201203;
| | - Minjia Tan
- From the ‡The Chemical Proteomics Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China, 201203; .,§State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China, 201203
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104
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Abstract
PURPOSE OF REVIEW ATP-citrate lyase (ACLY) has re-emerged as a drug target for LDL cholesterol (LDL-C) lowering. We review ACLY as a therapeutic strategy, its genetics, its molecular and cellular biology, and also its inhibition. RECENT FINDINGS ACLY is a critical enzyme linking glucose catabolism to lipogenesis by providing acetyl-CoA from mitochondrial citrate for fatty acid and cholesterol biosynthesis. Human genetic variants have been associated with enhanced growth and survival of several cancers, and with attenuated plasma triglyceride responses to dietary fish oil. In mice, liver-specific Acly deficiency protects from hepatic steatosis and dyslipidemia, whereas adipose tissue-specific Acly deletion has no phenotype, supporting therapeutic inhibition of ACLY. A lipid-regulating compound, bempedoic acid, was discovered to potently inhibit ACLY, and in animal models, it prevents dyslipidemia and attenuates atherosclerosis. Phase 2 clinical trials revealed that bempedoic acid effectively lowers LDL-C as monotherapy, combined with ezetimibe, added to statin therapy and in statin-intolerant hypercholesterolemic patients. SUMMARY The efficacy of bempedoic acid as an LDL-C-lowering agent has validated ACLY inhibition as a therapeutic strategy. Positive results of phase 3 patient studies, together with long-term cardiovascular disease outcome trials, are required to establish ACLY as a major new target in cardiovascular medicine.
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Affiliation(s)
- Amy C Burke
- aDepartment of Biochemistry bDepartment of Medicine cRobarts Research Institute, The University of Western Ontario, London, Ontario, Canada
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105
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Cinnamon Polyphenol Extract Inhibits Hyperlipidemia and Inflammation by Modulation of Transcription Factors in High-Fat Diet-Fed Rats. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:1583098. [PMID: 28396714 PMCID: PMC5370473 DOI: 10.1155/2017/1583098] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 02/26/2017] [Indexed: 12/11/2022]
Abstract
We evaluated the effects of cinnamon polyphenol extract on hepatic transcription factors expressions including SREBP-1c and LXR-α in rats fed high fat diet (HFD). Twenty-eight Wistar rats were allocated into four groups: (i) normal control: animals fed with normal chow; (ii) cinnamon: animals supplemented with cinnamon polyphenol; (iii) HFD: animals fed a high-fat diet; and (iv) HFD + cinnamon: animals fed a high-fat diet and treated with cinnamon polyphenol. Obesity was linked to hyperglycemia, hyperlipidemia, and oxidative stress as imitated by elevated serum glucose, lipid profile, and serum and liver malondialdehyde (MDA) concentrations. Cinnamon polyphenol decreased body weight, visceral fat, liver weight and serum glucose and insulin concentrations, liver antioxidant enzymes, and lipid profile (P < 0.05) and reduced serum and liver MDA concentration compared to HFD rats (P < 0.05). Cinnamon polyphenol also suppressed the hepatic SREBP-1c, LXR-α, ACLY, FAS, and NF-κB p65 expressions and enhanced the PPAR-α, IRS-1, Nrf2, and HO-1 expressions in the HFD rat livers (P < 0.05). In conclusion, cinnamon polyphenol reduces the hyperlipidemia, inflammation, and oxidative stress through activating transcription factors and antioxidative defense signaling pathway in HFD rat liver.
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106
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Liver-specific ATP-citrate lyase inhibition by bempedoic acid decreases LDL-C and attenuates atherosclerosis. Nat Commun 2016; 7:13457. [PMID: 27892461 PMCID: PMC5133702 DOI: 10.1038/ncomms13457] [Citation(s) in RCA: 287] [Impact Index Per Article: 35.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 10/06/2016] [Indexed: 12/25/2022] Open
Abstract
Despite widespread use of statins to reduce low-density lipoprotein cholesterol (LDL-C) and associated atherosclerotic cardiovascular risk, many patients do not achieve sufficient LDL-C lowering due to muscle-related side effects, indicating novel treatment strategies are required. Bempedoic acid (ETC-1002) is a small molecule intended to lower LDL-C in hypercholesterolemic patients, and has been previously shown to modulate both ATP-citrate lyase (ACL) and AMP-activated protein kinase (AMPK) activity in rodents. However, its mechanism for LDL-C lowering, efficacy in models of atherosclerosis and relevance in humans are unknown. Here we show that ETC-1002 is a prodrug that requires activation by very long-chain acyl-CoA synthetase-1 (ACSVL1) to modulate both targets, and that inhibition of ACL leads to LDL receptor upregulation, decreased LDL-C and attenuation of atherosclerosis, independently of AMPK. Furthermore, we demonstrate that the absence of ACSVL1 in skeletal muscle provides a mechanistic basis for ETC-1002 to potentially avoid the myotoxicity associated with statin therapy.
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107
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Genomics of human fatty liver disease reveal mechanistically linked lipid droplet-associated gene regulations in bland steatosis and nonalcoholic steatohepatitis. Transl Res 2016; 177:41-69. [PMID: 27376874 DOI: 10.1016/j.trsl.2016.06.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2016] [Revised: 05/13/2016] [Accepted: 06/08/2016] [Indexed: 12/11/2022]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is a common disorder hallmarked by excessive lipid deposits. Based on our recent research on lipid droplet (LD) formation in hepatocytes, we investigated LD-associated gene regulations in NAFLD of different grades, that is, steatosis vs steatohepatitis by comparing liver biopsies from healthy controls (N = 13) and NAFLD patients (N = 102). On average, more than 700 differentially expressed genes (DEGs) were identified of which 146 are mechanistically linked to LD formation. We identified 51 LD-associated DEGs frequently regulated in patient samples (range ≥5 to ≤102) with the liver-receptor homolog-1(NR5A2), that is, a key regulator of cholesterol metabolism being commonly repressed among 100 patients examined. With bland steatosis, notable regulations involved hypoxia-inducible lipid droplet-associated-protein and diacylglycerol-O-acyltransferase-2 renowned for their role in LD-growth. Conversely, nonalcoholic steatohepatitis-associated DEGs coded for epidermal growth factor receptor and TLR4 signaling with decreased expression of the GTPase Rab5 and the lipid phosphohydrolase PPAP2B thus highlighting adaptive responses to inflammation, LDL-mediated endocytosis and lipogenesis, respectively. Studies with steatotic primary human hepatocyte cultures demonstrated induction of LD-associated PLIN2, CIDEC, DNAAF1, whereas repressed expression of CPT1A, ANGPTL4, and PKLR informed on burdened mitochondrial metabolism. Equally, repressed expression of the B-lymphocyte chemoattractant CXCL13 and STAT4 as well as induced FGF21 evidenced amelioration of steatosis-related inflammation. In-vitro/in-vivo patient sample comparisons confirmed C-reactive protein, SOCS3, NR5A2, and SOD2 as commonly regulated. Lastly, STRING network analysis highlighted potential "druggable" targets with PLIN2, CIDEC, and hypoxia-inducible lipid droplet-associated-protein being confirmed by immunofluorescence microscopy. In conclusion, steatosis and steatohepatitis specific gene regulations informed on the pathogenesis of NAFLD to broaden the perspective of targeted therapies.
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108
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Pesta DH, Perry RJ, Guebre-Egziabher F, Zhang D, Jurczak M, Fischer-Rosinsky A, Daniels MA, Willmes DM, Bhanot S, Bornstein SR, Knauf F, Samuel VT, Shulman GI, Birkenfeld AL. Prevention of diet-induced hepatic steatosis and hepatic insulin resistance by second generation antisense oligonucleotides targeted to the longevity gene mIndy (Slc13a5). Aging (Albany NY) 2016; 7:1086-93. [PMID: 26647160 PMCID: PMC4712334 DOI: 10.18632/aging.100854] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Reducing the expression of the Indy (I'm Not Dead Yet) gene in lower organisms extends life span by mechanisms resembling caloric restriction. Similarly, deletion of the mammalian homolog, mIndy (Slc13a5), encoding for a plasma membrane tricarboxylate transporter, protects from aging- and diet-induced adiposity and insulin resistance in mice. The organ specific contribution to this phenotype is unknown. We examined the impact of selective inducible hepatic knockdown of mIndy on whole body lipid and glucose metabolism using 2′-O-methoxyethyl chimeric anti-sense oligonucleotides (ASOs) in high-fat fed rats. 4-week treatment with 2′-O-methoxyethyl chimeric ASO reduced mIndy mRNA expression by 91% (P<0.001) compared to control ASO. Besides similar body weights between both groups, mIndy-ASO treatment lead to a 74% reduction in fasting plasma insulin concentrations as well as a 35% reduction in plasma triglycerides. Moreover, hepatic triglyceride content was significantly reduced by the knockdown of mIndy, likely mediating a trend to decreased basal rates of endogenous glucose production as well as an increased suppression of hepatic glucose production by 25% during a hyperinsulinemic-euglycemic clamp. Together, these data suggest that inducible liver-selective reduction of mIndy in rats is able to ameliorate hepatic steatosis and insulin resistance, conditions occurring with high calorie diets and during aging.
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Affiliation(s)
- Dominik H Pesta
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA.,Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, USA.,Department of Sport Science, Medical Section, University of Innsbruck, Innsbruck, Austria.,Department of Visceral, Transplant, and Thoracic Surgery, D. Swarovski Research Laboratory, Medical University of Innsbruck, Innsbruck, Austria.,Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich-Heine University Düsseldorf, German Center for Diabetes Research, Partner Düsseldorf, Düsseldorf, Germany
| | - Rachel J Perry
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA.,Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, USA.,Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT, USA
| | | | - Dongyan Zhang
- Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, USA
| | - Michael Jurczak
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - Antje Fischer-Rosinsky
- Charité - University School of Medicine, Department of Endocrinology, Diabetes and Nutrition, Berlin, Germany
| | - Martin A Daniels
- Charité - University School of Medicine, Department of Endocrinology, Diabetes and Nutrition, Berlin, Germany.,Section of Metabolic Vascular Medicine, Medical Clinic III and Paul Langerhans Institute Dresden (PLID), TU Dresden, Germany
| | - Diana M Willmes
- Section of Metabolic Vascular Medicine, Medical Clinic III and Paul Langerhans Institute Dresden (PLID), TU Dresden, Germany.,German Center for Diabetes Research (DZD), Dresden, Germany
| | | | - Stefan R Bornstein
- Section of Metabolic Vascular Medicine, Medical Clinic III and Paul Langerhans Institute Dresden (PLID), TU Dresden, Germany.,German Center for Diabetes Research (DZD), Dresden, Germany.,Section of Diabetes and Nutritional Sciences, Rayne Institute, King's College London, London, UK
| | - Felix Knauf
- University Clinic Erlangen, Erlangen, Germany
| | - Varman T Samuel
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA.,Veterans Affairs Medical Center, West Haven, CT, USA
| | - Gerald I Shulman
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA.,Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, USA.,Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT, USA
| | - Andreas L Birkenfeld
- Section of Metabolic Vascular Medicine, Medical Clinic III and Paul Langerhans Institute Dresden (PLID), TU Dresden, Germany.,German Center for Diabetes Research (DZD), Dresden, Germany.,Section of Diabetes and Nutritional Sciences, Rayne Institute, King's College London, London, UK
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109
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Koronowicz AA, Banks P, Szymczyk B, Leszczyńska T, Master A, Piasna E, Szczepański W, Domagała D, Kopeć A, Piątkowska E, Laidler P. Dietary conjugated linoleic acid affects blood parameters, liver morphology and expression of selected hepatic genes in laying hens. Br Poult Sci 2016; 57:663-673. [PMID: 27267260 DOI: 10.1080/00071668.2016.1192280] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The objective of this research were to investigate the effect of a conjugated linoleic acid (CLA)-enriched diet on Isa Brown laying hen health status and to provide a comprehensive analysis of changes in blood parameters, liver morphology and selected hepatic gene expression. Hens were allocated to the control and experimental group (diet enriched with 0.75% CLA) for a total period of 4 m. At the end of the experiment half of the hens from each group were slaughtered for analyses. The remaining hens were transferred to an organic farm for the next 5 m and fed on the diet without CLA supplementation. The CLA-enriched diet resulted in significant changes in blood and serum parameters; specifically, haematocrit (HCT), mean corpuscular volume (MCV) and white blood cells (WBC) count were decreased compared to the control. The total cholesterol (TC) was not significantly affected while the triacylglycerol's (TG) concentration was elevated. The activity of alanine aminotransferase (ALT) was significantly increased in the CLA-supplemented group, while aspartate aminotransferase (AST) showed an increasing tendency. Liver biopsies showed pathological changes classified as non-alcoholic fatty liver disease (NAFLD). Additionally, the expression of hepatic genes involved in fatty acids synthesis (ME1, ACLY, ACC, FASN, SCD1), oxidation (CPT1α, PPARA), detoxification processes (Cytochrome P450, CYP, Flavin-containing monooxygenase, FMO3), oxidative stress (NOX4, XbP1) and inflammation (IL6, TNFα) were elevated. Cessation of CLA supplementation for 5 m of organic farming resulted in normalisation of blood and hepatic parameters to the levels observed in control hens. The results of this study indicate that dietary CLA triggers an integrated stress response in laying hens and activates mechanisms involved in liver detoxification.
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Affiliation(s)
- A A Koronowicz
- a Department of Human Nutrition, Faculty of Food Technology , University of Agriculture , Krakow , Poland
| | - P Banks
- a Department of Human Nutrition, Faculty of Food Technology , University of Agriculture , Krakow , Poland
| | - B Szymczyk
- b Department of Animal Nutrition and Feed Science , National Research Institute of Animal Production , Krakow , Poland
| | - T Leszczyńska
- a Department of Human Nutrition, Faculty of Food Technology , University of Agriculture , Krakow , Poland
| | - A Master
- c Department of Biochemistry and Molecular Biology , Medical Centre for Postgraduate Education , Warszawa , Poland
| | - E Piasna
- a Department of Human Nutrition, Faculty of Food Technology , University of Agriculture , Krakow , Poland
| | - W Szczepański
- d Department of Pathomorphology , Jagiellonian University Medical College , Krakow , Poland
| | - D Domagała
- a Department of Human Nutrition, Faculty of Food Technology , University of Agriculture , Krakow , Poland
| | - A Kopeć
- a Department of Human Nutrition, Faculty of Food Technology , University of Agriculture , Krakow , Poland
| | - E Piątkowska
- a Department of Human Nutrition, Faculty of Food Technology , University of Agriculture , Krakow , Poland
| | - P Laidler
- e Department of Medical Biochemistry , Jagiellonian University Medical College , Krakow , Poland
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Li K, Xiao Y, Yu J, Xia T, Liu B, Guo Y, Deng J, Chen S, Wang C, Guo F. Liver-specific Gene Inactivation of the Transcription Factor ATF4 Alleviates Alcoholic Liver Steatosis in Mice. J Biol Chem 2016; 291:18536-46. [PMID: 27405764 DOI: 10.1074/jbc.m116.726836] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Indexed: 12/17/2022] Open
Abstract
Although numerous biological functions of the activating transcription factor 4 (ATF4) have been identified, a direct effect of ATF4 on alcoholic liver steatosis has not been described previously. The aim of our current study is to investigate the role of ATF4 in alcoholic liver steatosis and elucidate the underlying mechanisms. Here, we showed that the expression of ATF4 is induced by ethanol in hepatocytes in vitro and in vivo, and liver-specific ATF4 knock-out mice are resistant to ethanol-induced liver steatosis, associated with stimulated hepatic AMP-activated protein kinase (AMPK) activity. Furthermore, adenovirus-mediated AMPK knockdown significantly reversed the suppressive effects of ATF4 deficiency on ethanol-induced liver steatosis in mice. In addition, ethanol-fed ATF4 knock-out mice exhibit AMPK-dependent inhibition of fatty acid synthase and stimulation of carnitine palmitoyltransferase 1 (CPT1) in the liver. Moreover, hepatic Tribbles homolog 3 (TRB3) expression was stimulated by ethanol in an ATF4-dependent manner, and adenovirus-mediated TRB3 knockdown blocked ATF4-dependent ethanol-induced AMPK inhibition and triglyceride accumulation in AML-12 cells. Finally, TRB3 directly interacted with AMPK to suppress its phosphorylation. Taken together, these results identify the ATF4-TRB3-AMPK axis as a novel pathway responsible for ethanol-induced liver steatosis.
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Affiliation(s)
- Kai Li
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, the Graduate School of the Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Yuzhong Xiao
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, the Graduate School of the Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Junjie Yu
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, the Graduate School of the Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Tingting Xia
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, the Graduate School of the Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Bin Liu
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, the Graduate School of the Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Yajie Guo
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, the Graduate School of the Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Jiali Deng
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, the Graduate School of the Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Shanghai Chen
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, the Graduate School of the Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Chunxia Wang
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, the Graduate School of the Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Feifan Guo
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, the Graduate School of the Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
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Zagayko AL, Shkapo AI, Fylymonenko VP, Briukhanova TO. The impact of hydroxycitric acid on the lipid metabolism profile under experimental insulin resistance syndrome of syrian hamsters. UKRAINIAN BIOCHEMICAL JOURNAL 2016; 88:78-82. [DOI: 10.15407/ubj88.03.078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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112
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Softic S, Cohen DE, Kahn CR. Role of Dietary Fructose and Hepatic De Novo Lipogenesis in Fatty Liver Disease. Dig Dis Sci 2016; 61:1282-93. [PMID: 26856717 PMCID: PMC4838515 DOI: 10.1007/s10620-016-4054-0] [Citation(s) in RCA: 414] [Impact Index Per Article: 51.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 01/21/2016] [Indexed: 12/11/2022]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is a liver manifestation of metabolic syndrome. Overconsumption of high-fat diet (HFD) and increased intake of sugar-sweetened beverages are major risk factors for development of NAFLD. Today the most commonly consumed sugar is high fructose corn syrup. Hepatic lipids may be derived from dietary intake, esterification of plasma free fatty acids (FFA) or hepatic de novo lipogenesis (DNL). A central abnormality in NAFLD is enhanced DNL. Hepatic DNL is increased in individuals with NAFLD, while the contribution of dietary fat and plasma FFA to hepatic lipids is not significantly altered. The importance of DNL in NAFLD is further established in mouse studies with knockout of genes involved in this process. Dietary fructose increases levels of enzymes involved in DNL even more strongly than HFD. Several properties of fructose metabolism make it particularly lipogenic. Fructose is absorbed via portal vein and delivered to the liver in much higher concentrations as compared to other tissues. Fructose increases protein levels of all DNL enzymes during its conversion into triglycerides. Additionally, fructose supports lipogenesis in the setting of insulin resistance as fructose does not require insulin for its metabolism, and it directly stimulates SREBP1c, a major transcriptional regulator of DNL. Fructose also leads to ATP depletion and suppression of mitochondrial fatty acid oxidation, resulting in increased production of reactive oxygen species. Furthermore, fructose promotes ER stress and uric acid formation, additional insulin independent pathways leading to DNL. In summary, fructose metabolism supports DNL more strongly than HFD and hepatic DNL is a central abnormality in NAFLD. Disrupting fructose metabolism in the liver may provide a new therapeutic option for the treatment of NAFLD.
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Affiliation(s)
- Samir Softic
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, One Joslin Place, Boston, MA, 02215, USA
- Department of Gastroenterology, Hepatology and Nutrition, Boston Children's Hospital, Boston, MA, USA
| | - David E Cohen
- Division of Gastroenterology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - C Ronald Kahn
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, One Joslin Place, Boston, MA, 02215, USA.
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113
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Shankar K, Singh SK, Kumar D, Varshney S, Gupta A, Rajan S, Srivastava A, Beg M, Srivastava AK, Kanojiya S, Mishra DK, Gaikwad AN. Cucumis melo ssp. Agrestis var. Agrestis Ameliorates High Fat Diet Induced Dyslipidemia in Syrian Golden Hamsters and Inhibits Adipogenesis in 3T3-L1 Adipocytes. Pharmacogn Mag 2016; 11:S501-10. [PMID: 27013786 PMCID: PMC4787080 DOI: 10.4103/0973-1296.172945] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Background: Cucumis melo ssp. agrestis var. agrestis (CMA) is a wild variety of C. melo. This study aimed to explore anti-dyslipidemic and anti-adipogenic potential of CMA. Materials and Methods: For initial anti-dyslipidemic and antihyperglycemic potential of CMA fruit extract (CMFE), male Syrian golden hamsters were fed a chow or high-fat diet with or without CMFE (100 mg/kg). Further, we did fractionation of this CMFE into two fractions namely; CMA water fraction (CMWF) and CMA hexane fraction (CMHF). Phytochemical screening was done with liquid chromatography-mass spectrometry LC- (MS)/MS and direct analysis in real time-MS to detect active compounds in the fractions. Further, high-fat diet fed dyslipidemic hamsters were treated with CMWF and CMHF at 50 mg/kg for 7 days. Results: Oral administration of CMFE and both fractions (CMWF and CMHF) reduced the total cholesterol, triglycerides, low‐density lipoprotein cholesterol, and very low‐density lipoprotein-cholesterol levels in high fat diet-fed dyslipidemic hamsters. CMHF also modulated expression of genes involved in lipogenesis, lipid metabolism, and reverse cholesterol transport. Standard biochemical diagnostic tests suggested that neither of fractions causes any toxicity to hamster liver or kidneys. CMFE and CMHF also decreased oil-red-O accumulation in 3T3-L1 adipocytes. Conclusion: Based on these results, it is concluded that CMA possesses anti-dyslipidemic and anti-hyperglycemic activity along with the anti-adipogenic activity. SUMMARY The oral administration of Cucumis melo agrestis fruit extract (CMFE) and its fractions (CMWF and CMHF) improved serum lipid profile in HFD fed dyslipidemic hamsters. CMFE, CMWF and CMHF significantly attenuated body weight gain and eWAT hypertrophy. The CMHF decreased lipogenesis in both liver and adipose tissue. CMFE and CMHF also inhibited adipogenesis in 3T3-L1 adipocytes.
Abbreviation used: CMA: Cucumis melo ssp. agrestis var. agrestis, CMFE: CMA fruit extract, CMWF: CMA water fraction, CMHF: CMA hexane fraction, FAS: Fatty acid synthase, SREBP1c: Sterol regulatory element binding protein 1c, ACC: Acetyl CoA carboxylase, LXR α: Liver X receptor α.
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Affiliation(s)
- Kripa Shankar
- Division of Pharmacology, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India
| | - Sumit K Singh
- Division of Botany, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India
| | - Durgesh Kumar
- Division of Pharmacology, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India; Academy of Scientific and Innovative Research, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India
| | - Salil Varshney
- Division of Pharmacology, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India
| | - Abhishek Gupta
- Division of Pharmacology, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India
| | - Sujith Rajan
- Division of Pharmacology, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India; Academy of Scientific and Innovative Research, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India
| | - Ankita Srivastava
- Division of Pharmacology, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India; Academy of Scientific and Innovative Research, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India
| | - Muheeb Beg
- Division of Pharmacology, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India
| | | | - Sanjeev Kanojiya
- Sophisticated Analytical Instrument Facility, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India
| | - Dipak K Mishra
- Division of Botany, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India; Division of Pharmacology, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India
| | - Anil N Gaikwad
- Division of Pharmacology, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India
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114
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Angiotensin-converting enzyme 2/angiotensin-(1-7)/Mas axis activates Akt signaling to ameliorate hepatic steatosis. Sci Rep 2016; 6:21592. [PMID: 26883384 PMCID: PMC4756304 DOI: 10.1038/srep21592] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 01/27/2016] [Indexed: 02/08/2023] Open
Abstract
The classical axis of renin-angiotensin system (RAS), angiotensin (Ang)-converting enzyme (ACE)/Ang II/AT1, contributes to the development of non-alcoholic fatty liver disease (NAFLD). However, the role of bypass axis of RAS (Angiotensin-converting enzyme 2 (ACE2)/Ang-(1–7)/Mas) in hepatic steatosis is still unclear. Here we showed that deletion of ACE2 aggravates liver steatosis, which is correlated with the increased expression of hepatic lipogenic genes and the decreased expression of fatty acid oxidation-related genes in the liver of ACE2 knockout (ACE2−/y) mice. Meanwhile, oxidative stress and inflammation were also aggravated in ACE2−/y mice. On the contrary, overexpression of ACE2 improved fatty liver in db/db mice, and the mRNA levels of fatty acid oxidation-related genes were up-regulated. In vitro, Ang-(1–7)/ACE2 ameliorated hepatic steatosis, oxidative stress and inflammation in free fatty acid (FFA)-induced HepG2 cells, and what’s more, Akt inhibitors reduced ACE2-mediated lipid metabolism. Furthermore, ACE2-mediated Akt activation could be attenuated by blockade of ATP/P2 receptor/Calmodulin (CaM) pathway. These results indicated that Ang-(1–7)/ACE2/Mas axis may reduce liver lipid accumulation partly by regulating lipid-metabolizing genes through ATP/P2 receptor/CaM signaling pathway. Our findings support the potential role of ACE2/Ang-(1–7)/Mas axis in prevention and treatment of hepatic lipid metabolism.
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115
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Kinlaw WB, Baures PW, Lupien LE, Davis WL, Kuemmerle NB. Fatty Acids and Breast Cancer: Make Them on Site or Have Them Delivered. J Cell Physiol 2016; 231:2128-41. [PMID: 26844415 DOI: 10.1002/jcp.25332] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 02/02/2016] [Indexed: 12/11/2022]
Abstract
Brisk fatty acid (FA) production by cancer cells is accommodated by the Warburg effect. Most breast and other cancer cell types are addicted to fatty acids (FA), which they require for membrane phospholipid synthesis, signaling purposes, and energy production. Expression of the enzymes required for FA synthesis is closely linked to each of the major classes of signaling molecules that stimulate BC cell proliferation. This review focuses on the regulation of FA synthesis in BC cells, and the impact of FA, or the lack thereof, on the tumor cell phenotype. Given growing awareness of the impact of dietary fat and obesity on BC biology, we will also examine the less-frequently considered notion that, in addition to de novo FA synthesis, the lipolytic uptake of preformed FA may also be an important mechanism of lipid acquisition. Indeed, it appears that cancer cells may exist at different points along a "lipogenic-lipolytic axis," and FA uptake could thwart attempts to exploit the strict requirement for FA focused solely on inhibition of de novo FA synthesis. Strategies for clinically targeting FA metabolism will be discussed, and the current status of the medicinal chemistry in this area will be assessed. J. Cell. Physiol. 231: 2128-2141, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- William B Kinlaw
- Division of Endocrinology and Metabolism, Department of Medicine, The Geisel School of Medicine at Dartmouth, Norris Cotton Cancer Center, Lebanon, New Hampshire
| | - Paul W Baures
- Department of Chemistry, Keene State University, Keene, New Hampshire
| | - Leslie E Lupien
- The Geisel School of Medicine at Dartmouth, Program in Experimental and Molecular Medicine, Lebanon, New Hampshire.,Division of Oncology, Department of Medicine, The Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire
| | - Wilson L Davis
- Division of Endocrinology and Metabolism, Department of Medicine, The Geisel School of Medicine at Dartmouth, Norris Cotton Cancer Center, Lebanon, New Hampshire
| | - Nancy B Kuemmerle
- The Geisel School of Medicine at Dartmouth, Norris Cotton Cancer Center, Lebanon, New Hampshire.,Division of Hematology/Oncology, Department of Medicine, White River Junction VAMC, White River Junction, Vermont
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116
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Xiao Y, Liu H, Yu J, Zhao Z, Xiao F, Xia T, Wang C, Li K, Deng J, Guo Y, Chen S, Chen Y, Guo F. Activation of ERK1/2 Ameliorates Liver Steatosis in Leptin Receptor-Deficient (db/db) Mice via Stimulating ATG7-Dependent Autophagy. Diabetes 2016; 65:393-405. [PMID: 26581593 DOI: 10.2337/db15-1024] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 11/11/2015] [Indexed: 11/13/2022]
Abstract
Although numerous functions of extracellular signal-regulated kinase 1/2 (ERK1/2) are identified, a direct effect of ERK1/2 on liver steatosis has not been reported. Here, we show that ERK1/2 activity is compromised in livers of leptin receptor-deficient (db/db) mice. Adenovirus-mediated activation of mitogen-activated protein kinase kinase 1 (MEK1), the upstream regulator of ERK1/2, significantly ameliorated liver steatosis in db/db mice, increased expression of genes related to fatty acid β-oxidation and triglyceride (TG) export and increased serum β-hydroxybutyrate (3-HB) levels. Opposite effects were observed in adenovirus-mediated ERK1/2 knockdown C57/B6J wild-type mice. Furthermore, autophagy and autophagy-related protein 7 (ATG7) expression were decreased or increased by ERK1/2 knockdown or activation, respectively, in primary hepatocytes and liver. Blockade of autophagy by the autophagy inhibitor chloroquine or adenovirus-mediated ATG7 knockdown reversed the ameliorated liver steatosis in recombinant adenoviruses construct expressing rat constitutively active MEK1 Ad-CA MEK1 db/db mice, decreased expression of genes related to fatty acid β-oxidation and TG export, and decreased serum 3-HB levels. Finally, ERK1/2 regulated ATG7 expression in a p38-dependent pathway. Taken together, these results identify a novel beneficial role for ERK1/2 in liver steatosis via promoting ATG7-dependent autophagy, which provides new insights into the mechanisms underlying liver steatosis and important hints for targeting ERK1/2 in treating liver steatosis.
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Affiliation(s)
- Yuzhong Xiao
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Graduate School of the Chinese Academy of Sciences, The Chinese Academy of Sciences, Shanghai, China
| | - Hao Liu
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Graduate School of the Chinese Academy of Sciences, The Chinese Academy of Sciences, Shanghai, China
| | - Junjie Yu
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Graduate School of the Chinese Academy of Sciences, The Chinese Academy of Sciences, Shanghai, China
| | - Zilong Zhao
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Graduate School of the Chinese Academy of Sciences, The Chinese Academy of Sciences, Shanghai, China
| | - Fei Xiao
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Graduate School of the Chinese Academy of Sciences, The Chinese Academy of Sciences, Shanghai, China
| | - Tingting Xia
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Graduate School of the Chinese Academy of Sciences, The Chinese Academy of Sciences, Shanghai, China
| | - Chunxia Wang
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Graduate School of the Chinese Academy of Sciences, The Chinese Academy of Sciences, Shanghai, China
| | - Kai Li
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Graduate School of the Chinese Academy of Sciences, The Chinese Academy of Sciences, Shanghai, China
| | - Jiali Deng
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Graduate School of the Chinese Academy of Sciences, The Chinese Academy of Sciences, Shanghai, China
| | - Yajie Guo
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Graduate School of the Chinese Academy of Sciences, The Chinese Academy of Sciences, Shanghai, China
| | - Shanghai Chen
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Graduate School of the Chinese Academy of Sciences, The Chinese Academy of Sciences, Shanghai, China
| | - Yan Chen
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Graduate School of the Chinese Academy of Sciences, The Chinese Academy of Sciences, Shanghai, China
| | - Feifan Guo
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Graduate School of the Chinese Academy of Sciences, The Chinese Academy of Sciences, Shanghai, China
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117
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Gomes P, Fleming Outeiro T, Cavadas C. Emerging Role of Sirtuin 2 in the Regulation of Mammalian Metabolism. Trends Pharmacol Sci 2015; 36:756-768. [DOI: 10.1016/j.tips.2015.08.001] [Citation(s) in RCA: 156] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 07/30/2015] [Accepted: 08/03/2015] [Indexed: 12/23/2022]
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118
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Roberts MD, Mobley CB, Toedebush RG, Heese AJ, Zhu C, Krieger AE, Cruthirds CL, Lockwood CM, Hofheins JC, Wiedmeyer CE, Leidy HJ, Booth FW, Rector RS. Western diet-induced hepatic steatosis and alterations in the liver transcriptome in adult Brown-Norway rats. BMC Gastroenterol 2015; 15:151. [PMID: 26519296 PMCID: PMC4628330 DOI: 10.1186/s12876-015-0382-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 10/21/2015] [Indexed: 01/15/2023] Open
Abstract
Background The purpose of this study was to investigate the effects of sub-chronic high fat, high sucrose diet (also termed ‘Westernized diet’ or WD) feeding on the liver transcriptome during early nonalcoholic fatty liver disease (NAFLD) development. Methods Brown Norway male rats (9 months of age) were randomly assigned to receive ad libitum access to a control (CTL; 14 % kcal fat, 1.2 % sucrose by weight) diet or WD (42 % kcal from fat, 34 % sucrose by weight) for 6 weeks. Results Six weeks of WD feeding caused hepatic steatosis development as evidenced by the 2.25-fold increase in liver triacylglycerol content, but did not induce advanced liver disease (i.e., no overt inflammation or fibrosis) in adult Brown Norway rats. RNA deep sequencing (RNA-seq) revealed that 94 transcripts were altered in liver by WD feeding (46 up-, 48 down-regulated, FDR < 0.05). Specifically, the top differentially regulated gene network by WD feeding was ‘Lipid metabolism, small molecular biochemistry, vitamin and mineral metabolism’ (Ingenuity Pathway Analysis (IPA) score 61). The top-regulated canonical signaling pathway in WD-fed rats was the ‘Superpathway of cholesterol biosynthesis’ (10/29 genes regulated, p = 1.68E-17), which coincides with a tendency for serum cholesterol levels to increase in WD-fed rats (p = 0.09). Remarkably, liver stearoyl-CoA desaturase (Scd) mRNA expression was by far the most highly-induced transcript in WD-fed rats (approximately 30-fold, FDR = 0.01) which supports previous literature underscoring this gene as a crucial target during NAFLD development. Conclusions In summary, sub-chronic WD feeding appears to increase hepatic steatosis development over a 6-week period but only induces select inflammation-related liver transcripts, mostly acute phase response genes. These findings continue to outline the early stages of NAFLD development prior to overt liver inflammation and advanced liver disease.
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Affiliation(s)
- Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, AL, USA.,Edward Via College of Osteopathic Medicine-Auburn Campus, Auburn, AL, USA
| | | | - Ryan G Toedebush
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, USA
| | - Alexander J Heese
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, USA
| | - Conan Zhu
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, USA
| | - Anna E Krieger
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, USA
| | - Clayton L Cruthirds
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, USA
| | | | - John C Hofheins
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, USA
| | - Charles E Wiedmeyer
- Department of Veterinary Pathobiology, University of Missouri, Columbia, MO, USA
| | - Heather J Leidy
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, MO, 65212, USA
| | - Frank W Booth
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, USA.,Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, USA.,Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, USA
| | - R Scott Rector
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, MO, 65212, USA. .,Department of Medicine-Gastroenterology and Hepatology, University of Missouri, Columbia, MO, USA. .,Research Service-Harry S Truman Memorial VA Hospital, Columbia, MO, USA.
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119
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Xiao F, Deng J, Yu J, Guo Y, Chen S, Guo F. A novel function of B‐cell translocation gene 1 (
BTG1
) in the regulation of hepatic insulin sensitivity in mice
via
c‐Jun. FASEB J 2015; 30:348-59. [DOI: 10.1096/fj.15-278689] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 09/08/2015] [Indexed: 12/17/2022]
Affiliation(s)
- Fei Xiao
- Key Laboratory of Nutrition and MetabolismInstitute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, the Graduate School of the Chinese Academy of SciencesChinese Academy of SciencesShanghaiChina
| | - Jiali Deng
- Key Laboratory of Nutrition and MetabolismInstitute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, the Graduate School of the Chinese Academy of SciencesChinese Academy of SciencesShanghaiChina
| | - Junjie Yu
- Key Laboratory of Nutrition and MetabolismInstitute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, the Graduate School of the Chinese Academy of SciencesChinese Academy of SciencesShanghaiChina
| | - Yajie Guo
- Key Laboratory of Nutrition and MetabolismInstitute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, the Graduate School of the Chinese Academy of SciencesChinese Academy of SciencesShanghaiChina
| | - Shanghai Chen
- Key Laboratory of Nutrition and MetabolismInstitute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, the Graduate School of the Chinese Academy of SciencesChinese Academy of SciencesShanghaiChina
| | - Feifan Guo
- Key Laboratory of Nutrition and MetabolismInstitute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, the Graduate School of the Chinese Academy of SciencesChinese Academy of SciencesShanghaiChina
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Distinct regulatory mechanisms governing embryonic versus adult adipocyte maturation. Nat Cell Biol 2015; 17:1099-111. [PMID: 26280538 PMCID: PMC4553131 DOI: 10.1038/ncb3217] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 07/02/2015] [Indexed: 12/15/2022]
Abstract
Pathological expansion of adipose tissue contributes to the metabolic syndrome. Distinct depots develop at various times under different physiological conditions. The transcriptional cascade mediating adipogenesis is established in vitro, and centers around a core program involving PPARγ and C/EBPα. We developed an inducible, adipocyte-specific knockout system to probe the requirement of key adipogenic transcription factors at various stages of adipogenesis in vivo. C/EBPα is essential for all white adipogenic conditions in the adult stage, such as adipose tissue regeneration, adipogenesis in muscle and unhealthy expansion of white adipose tissue during high fat feeding or due to leptin deficiency. Surprisingly, terminal embryonic adipogenesis is fully C/EBPα independent, does depend however on PPARγ; cold-induced beige adipogenesis is also C/EBPα independent. Moreover, C/EBPα is not vital for adipocyte survival in the adult stage. We reveal a surprising diversity of transcriptional signals required at different stages of adipogenesis in vivo.
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121
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Pan QR, Ren YL, Liu WX, Hu YJ, Zheng JS, Xu Y, Wang G. Resveratrol prevents hepatic steatosis and endoplasmic reticulum stress and regulates the expression of genes involved in lipid metabolism, insulin resistance, and inflammation in rats. Nutr Res 2015; 35:576-84. [PMID: 26055348 DOI: 10.1016/j.nutres.2015.05.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 05/04/2015] [Accepted: 05/14/2015] [Indexed: 02/08/2023]
Abstract
Previous research demonstrated that resveratrol possesses promising properties for preventing obesity. Endoplasmic reticulum (ER) stress was proposed to be involved in the pathophysiology of both obesity and hepatic steatosis. In the current study, we hypothesized that resveratrol could protect against high-fat diet (HFD)-induced hepatic steatosis and ER stress and regulate the expression of genes related to hepatic steatosis. Rats were fed either a control diet or a HFD for 12 weeks. After 4 weeks, HFD-fed rats were treated with either resveratrol or vehicle for 8 weeks. Body weight, serum metabolic parameters, hepatic histopathology, and hepatic ER stress markers were evaluated. Moreover, an RT2 Profiler Fatty Liver PCR Array was performed to investigate the mRNA expressions of 84 genes related to hepatic steatosis. Our work showed that resveratrol prevented dyslipidemia and hepatic steatosis induced by HFD. Resveratrol significantly decreased activating transcription factor 4, C/EBP-homologous protein and immunoglobulin binding protein levels, which were elevated by the HFD. Resveratrol also decreased PKR-like ER kinase phosphorylation, although it was not affected by the HFD. Furthermore, resveratrol increased the expression of peroxisome proliferator-activated receptor δ, while decreasing the expression of ATP citrate lyase, suppressor of cytokine signaling-3, and interleukin-1β. Our data suggest that resveratrol can prevent hepatic ER stress and regulate the expression of peroxisome proliferator-activated receptor δ, ATP citrate lyase, suppressor of cytokine signaling-3, tumor necrosis factor α, and interleukin-1β in diet-induced obese rats, and these effects likely contribute to resveratrol's protective function against excessive accumulation of fat in the liver.
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Affiliation(s)
- Qing-Rong Pan
- Department of Endocrinology, Beijing Chaoyang Hospital, Capital Medical University, Beijing, 100020, China
| | - Yan-Long Ren
- Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing, 100029, China
| | - Wen-Xian Liu
- Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing, 100029, China
| | - Yan-Jin Hu
- Department of Endocrinology, Beijing Chaoyang Hospital, Capital Medical University, Beijing, 100020, China
| | - Jin-Su Zheng
- Department of Traditional Chinese medicine, Beijing Chaoyang Hospital, Capital Medical University, Beijing, 100020, China
| | - Yuan Xu
- Department of Endocrinology, Beijing Chaoyang Hospital, Capital Medical University, Beijing, 100020, China.
| | - Guang Wang
- Department of Endocrinology, Beijing Chaoyang Hospital, Capital Medical University, Beijing, 100020, China.
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122
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Wu Q, Wang H, An P, Tao Y, Deng J, Zhang Z, Shen Y, Chen C, Min J, Wang F. HJV and HFE Play Distinct Roles in Regulating Hepcidin. Antioxid Redox Signal 2015; 22:1325-36. [PMID: 25608116 PMCID: PMC4410569 DOI: 10.1089/ars.2013.5819] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
AIMS Hereditary hemochromatosis (HH) is an iron overload disease that is caused by mutations in HFE, HJV, and several other genes. However, whether HFE-HH and HJV-HH share a common pathway via hepcidin regulation is currently unclear. Recently, some HH patients have been reported to carry concurrent mutations in both the HFE and HJV genes. To dissect the roles and molecular mechanisms of HFE and/or HJV in the pathogenesis of HH, we studied Hfe(-/-), Hjv(-/-), and Hfe(-/-)Hjv(-/-) double-knockout mouse models. RESULTS Hfe(-/-)Hjv(-/-) mice developed iron overload in multiple organs at levels comparable to Hjv(-/-) mice. After an acute delivery of iron, the expression of hepcidin (i.e., Hamp1 mRNA) was increased in the livers of wild-type and Hfe(-/-) mice, but not in either Hjv(-/-) or Hfe(-/-)Hjv(-/-) mice. Furthermore, iron-induced phosphorylation of Smad1/5/8 was not detected in the livers of Hjv(-/-) or Hfe(-/-)Hjv(-/-) mice. INNOVATION We generated and phenotypically characterized Hfe(-/-)Hjv(-/-) double-knockout mice. In addition, because they faithfully phenocopy clinical HH patients, these mouse models are an invaluable tool for mechanistically dissecting how HFE and HJV regulate hepcidin expression. CONCLUSIONS Based on our results, we conclude that HFE may depend on HJV for transferrin-dependent hepcidin regulation. The presence of residual hepcidin in the absence of HFE suggests either the presence of an unknown regulator (e.g., TFR2) that is synergistic with HJV or that HJV is sufficient to maintain basal levels of hepcidin.
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Affiliation(s)
- Qian Wu
- 1 Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences , Shanghai, China
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Yu J, Xiao F, Guo Y, Deng J, Liu B, Zhang Q, Li K, Wang C, Chen S, Guo F. Hepatic Phosphoserine Aminotransferase 1 Regulates Insulin Sensitivity in Mice via Tribbles Homolog 3. Diabetes 2015; 64:1591-602. [PMID: 25503742 DOI: 10.2337/db14-1368] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 12/09/2014] [Indexed: 11/13/2022]
Abstract
Phosphoserine aminotransferase 1 (PSAT1) is an enzyme participating in serine synthesis. A role of PSAT1 in the regulation of insulin sensitivity, however, is unknown. In this study, we showed that hepatic PSAT1 expression and liver serine levels are reduced in genetically engineered leptin receptor-deficient (db/db) mice and high-fat diet (HFD)-induced diabetic mice. Additionally, overexpression of PSAT1 by adenovirus expressing PSAT1 improved insulin signaling and insulin sensitivity in vitro and in vivo under normal conditions. Opposite effects were observed when PSAT1 was knocked down by adenovirus expressing small hairpin RNA specific for PSAT1 (Ad-shPSAT1). Importantly, overexpression of PSAT1 also significantly ameliorated insulin resistance in diabetic mice. In addition, PSAT1 inhibited the expression of hepatic tribbles homolog 3 (TRB3) in vitro and in vivo, and adenoviruses expressing small hairpin RNA against TRB3-mediated inhibition of TRB3 reversed the attenuated insulin sensitivity in Ad-shPSAT1 mice. Interestingly, we found that serine mediates PSAT1 regulation of TRB3 expression and insulin signaling in vitro. These results identify a novel function for hepatic PSAT1 in regulating insulin sensitivity and provide important insights in targeting PSAT1 for treating insulin resistance and type 2 diabetes. Our results also suggest that nonessential amino acid serine may play an important role in regulating insulin sensitivity.
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Affiliation(s)
- Junjie Yu
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Shanghai, China
| | - Fei Xiao
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Shanghai, China
| | - Yajie Guo
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Shanghai, China
| | - Jiali Deng
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Shanghai, China
| | - Bin Liu
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Shanghai, China
| | - Qian Zhang
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Shanghai, China
| | - Kai Li
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Shanghai, China
| | - Chunxia Wang
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Shanghai, China
| | - Shanghai Chen
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Shanghai, China
| | - Feifan Guo
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Shanghai, China
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Solinas G, Borén J, Dulloo AG. De novo lipogenesis in metabolic homeostasis: More friend than foe? Mol Metab 2015; 4:367-77. [PMID: 25973385 PMCID: PMC4421107 DOI: 10.1016/j.molmet.2015.03.004] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 03/06/2015] [Accepted: 03/12/2015] [Indexed: 02/09/2023] Open
Abstract
Background An acute surplus of carbohydrates, and other substrates, can be converted and safely stored as lipids in adipocytes via de novo lipogenesis (DNL). However, in obesity, a condition characterized by chronic positive energy balance, DNL in non-adipose tissues may lead to ectopic lipid accumulation leading to lipotoxicity and metabolic stress. Indeed, DNL is dynamically recruited in liver during the development of fatty liver disease, where DNL is an important source of lipids. Nonetheless, a number of evidences indicates that DNL is an inefficient road for calorie to lipid conversion and that DNL may play an important role in sustaining metabolic homeostasis. Scope of review In this manuscript, we discuss the role of DNL as source of lipids during obesity, the energetic efficiency of this pathway in converting extra calories to lipids, and the function of DNL as a pathway supporting metabolic homeostasis. Major conclusion We conclude that inhibition of DNL in obese subjects, unless coupled with a correction of the chronic positive energy balance, may further promote lipotoxicity and metabolic stress. On the contrary, strategies aimed at specifically activating DNL in adipose tissue could support metabolic homeostasis in obese subjects by a number of mechanisms, which are discussed in this manuscript.
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Affiliation(s)
- Giovanni Solinas
- Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, Wallenberg Laboratory, University of Gothenburg, Gothenburg, Sweden
| | - Jan Borén
- Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, Wallenberg Laboratory, University of Gothenburg, Gothenburg, Sweden
| | - Abdul G Dulloo
- Division of Physiology, Department of Medicine, University of Fribourg, Fribourg, Switzerland
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Li K, Zhang J, Yu J, Liu B, Guo Y, Deng J, Chen S, Wang C, Guo F. MicroRNA-214 suppresses gluconeogenesis by targeting activating transcriptional factor 4. J Biol Chem 2015; 290:8185-95. [PMID: 25657009 DOI: 10.1074/jbc.m114.633990] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Although the gluconeogenesis pathway is already a target for the treatment of type 2 diabetes, the potential role of microRNAs (miRNAs) in gluconeogenesis remains unclear. Here, we investigated the physiological functions of miR-214 in gluconeogenesis. The expression of miR-214 was suppressed by glucagon via protein kinase A signaling in primary hepatocytes, and miR-214 was down-regulated in the livers of fasted, high fat diet-induced diabetic and leptin receptor-mutated (db/db) mice. The overexpression of miR-214 in primary hepatocytes suppressed glucose production, and silencing miR-214 reversed this effect. Gluconeogenesis was suppressed in the livers of mice injected with an adenovirus expressing miR-214 (Ad-miR-214). Additionally, Ad-miR-214 alleviated high fat diet-induced elevation of gluconeogenesis and hyperglycemia. Furthermore, we found that activating transcription factor 4 (ATF4), a reported target of miR-214, can reverse the suppressive effect of miR-214 on gluconeogenesis in primary hepatocytes, and this suppressive effect was blocked in liver-specific ATF4 knock-out mice. ATF4 regulated gluconeogenesis via affecting forkhead box protein O1 (FOXO1) transcriptional activity. Finally, liver-specific miR-214 transgenic mice exhibited suppressed gluconeogenesis and reduced expression of ATF4, phosphoenolpyruvate carboxykinase, and glucose-6-phosphatase in liver. Taken together, our results suggest that the miR-214-ATF4 axis is a novel pathway for the regulation of hepatic gluconeogenesis.
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Affiliation(s)
- Kai Li
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031 and
| | - Jin Zhang
- the Key Laboratory of Molecular Medicine, Ministry of Education, Institute of Medical Sciences, Department of Biochemistry and Molecular Biology, Shanghai Medical College, Fudan University, 130 Dongan Road, Shanghai 200032, China
| | - Junjie Yu
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031 and
| | - Bin Liu
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031 and
| | - Yajie Guo
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031 and
| | - Jiali Deng
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031 and
| | - Shanghai Chen
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031 and
| | - Chunxia Wang
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031 and
| | - Feifan Guo
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031 and
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Sahini N, Selvaraj S, Borlak J. Whole genome transcript profiling of drug induced steatosis in rats reveals a gene signature predictive of outcome. PLoS One 2014; 9:e114085. [PMID: 25470483 PMCID: PMC4254931 DOI: 10.1371/journal.pone.0114085] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 11/04/2014] [Indexed: 12/20/2022] Open
Abstract
Drug induced steatosis (DIS) is characterised by excess triglyceride accumulation in the form of lipid droplets (LD) in liver cells. To explore mechanisms underlying DIS we interrogated the publically available microarray data from the Japanese Toxicogenomics Project (TGP) to study comprehensively whole genome gene expression changes in the liver of treated rats. For this purpose a total of 17 and 12 drugs which are diverse in molecular structure and mode of action were considered based on their ability to cause either steatosis or phospholipidosis, respectively, while 7 drugs served as negative controls. In our efforts we focused on 200 genes which are considered to be mechanistically relevant in the process of lipid droplet biogenesis in hepatocytes as recently published (Sahini and Borlak, 2014). Based on mechanistic considerations we identified 19 genes which displayed dose dependent responses while 10 genes showed time dependency. Importantly, the present study defined 9 genes (ANGPTL4, FABP7, FADS1, FGF21, GOT1, LDLR, GK, STAT3, and PKLR) as signature genes to predict DIS. Moreover, cross tabulation revealed 9 genes to be regulated ≥10 times amongst the various conditions and included genes linked to glucose metabolism, lipid transport and lipogenesis as well as signalling events. Additionally, a comparison between drugs causing phospholipidosis and/or steatosis revealed 26 genes to be regulated in common including 4 signature genes to predict DIS (PKLR, GK, FABP7 and FADS1). Furthermore, a comparison between in vivo single dose (3, 6, 9 and 24 h) and findings from rat hepatocyte studies (2 h, 8 h, 24 h) identified 10 genes which are regulated in common and contained 2 DIS signature genes (FABP7, FGF21). Altogether, our studies provide comprehensive information on mechanistically linked gene expression changes of a range of drugs causing steatosis and phospholipidosis and encourage the screening of DIS signature genes at the preclinical stage.
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Affiliation(s)
- Nishika Sahini
- Centre for Pharmacology and Toxicology, Hannover Medical School, Hannover, Germany
| | | | - Jürgen Borlak
- Centre for Pharmacology and Toxicology, Hannover Medical School, Hannover, Germany
- * E-mail:
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127
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Zou X, Yan C, Shi Y, Cao K, Xu J, Wang X, Chen C, Luo C, Li Y, Gao J, Pang W, Zhao J, Zhao F, Li H, Zheng A, Sun W, Long J, Szeto IMY, Zhao Y, Dong Z, Zhang P, Wang J, Lu W, Zhang Y, Liu J, Feng Z. Mitochondrial dysfunction in obesity-associated nonalcoholic fatty liver disease: the protective effects of pomegranate with its active component punicalagin. Antioxid Redox Signal 2014; 21:1557-70. [PMID: 24393106 PMCID: PMC4175030 DOI: 10.1089/ars.2013.5538] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
AIMS Punicalagin (PU) is one of the major ellagitannins found in the pomegranate (Punica granatum), which is a popular fruit with several health benefits. So far, no studies have evaluated the effects of PU on nonalcoholic fatty liver disease (NAFLD). Our work aims at studying the effect of PU-enriched pomegranate extract (PE) on high fat diet (HFD)-induced NAFLD. RESULTS PE administration at a dosage of 150 mg/kg/day significantly inhibited HFD-induced hyperlipidemia and hepatic lipid deposition. As major contributors to NAFLD, increased expression of pro-inflammatory cytokines such as tumor necrosis factor-alpha, interleukins 1, 4, and 6 as well as augmented oxidative stress in hepatocytes followed by nuclear factor (erythroid-derived-2)-like 2 (Nrf2) activation were normalized through PE supplementation. In addition, PE treatment reduced uncoupling protein 2 (UCP2) expression, restored ATP content, suppressed mitochondrial protein oxidation, and improved mitochondrial complex activity in the liver. In contrast, mitochondrial content was not affected despite increased peroxisomal proliferator-activated receptor-gamma coactivator-1α (PGC-1α) and elevated expression of genes related to mitochondrial beta-oxidation after PE treatment. Finally, PU was identified as the predominant active component of PE with regard to the lowering of triglyceride and cholesterol content in HepG2 cells, and both PU- and PE-protected cells from palmitate induced mitochondrial dysfunction and insulin resistance. INNOVATION Our work presents the beneficial effects of PE on obesity-associated NAFLD and multiple risk factors. PU was proposed to be the major active component. CONCLUSIONS By promoting mitochondrial function, eliminating oxidative stress and inflammation, PU may be a useful nutrient for the treatment of NAFLD.
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Affiliation(s)
- Xuan Zou
- 1 The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Frontier Institute of Science and Technology, Xi'an Jiaotong University , Xi'an, China
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Xiao F, Xia T, Lv Z, Zhang Q, Xiao Y, Yu J, Liu H, Deng J, Guo Y, Wang C, Li K, Liu B, Chen S, Guo F. Central prolactin receptors (PRLRs) regulate hepatic insulin sensitivity in mice via signal transducer and activator of transcription 5 (STAT5) and the vagus nerve. Diabetologia 2014; 57:2136-44. [PMID: 25064125 DOI: 10.1007/s00125-014-3336-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 06/24/2014] [Indexed: 10/25/2022]
Abstract
AIMS/HYPOTHESIS Recent studies have revealed the crucial role of the central nervous system (CNS), especially the hypothalamus, in the regulation of insulin sensitivity in peripheral tissues. The aim of our current study was to investigate the possible involvement of hypothalamic prolactin receptors (PRLRs) in the regulation of hepatic insulin sensitivity. METHODS We employed overexpression of PRLRs in mouse hypothalamus via intracerebroventricular injection of adenovirus expressing PRLR and inhibition of PRLRs via adenovirus expressing short-hairpin RNA (shRNA) specific for PRLRs in vivo. Selective hepatic vagotomy was employed to verify the important role of the vagus nerve in mediating signals from the brain to peripheral organs. In addition, a genetic insulin-resistant animal model, the db/db mouse, was used in our study to investigate the role of hypothalamic PRLRs in regulating whole-body insulin sensitivity. RESULTS Overexpression of PRLRs in the hypothalamus improved hepatic insulin sensitivity in mice and inhibition of hypothalamic PRLRs had the opposite effect. In addition, we demonstrated that hypothalamic PRLR-improved insulin sensitivity was significantly attenuated by inhibiting the activity of signal transducer and activator of transcription 5 (STAT5) in the CNS and by selective hepatic vagotomy. Finally, overexpression of PRLRs significantly ameliorated insulin resistance in db/db mice. CONCLUSIONS/INTERPRETATION Our study identifies a novel central pathway involved in the regulation of hepatic insulin sensitivity, mediated by hypothalamic PRLR/STAT5 signalling and the vagus nerve, thus demonstrating an important role for hypothalamic PRLRs under conditions of insulin resistance.
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Affiliation(s)
- Fei Xiao
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai, 200031, People's Republic of China
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Comparison between transient elastography (Fibroscan) and liver biopsy for the diagnosis of hepatic fibrosis in chronic hepatitis C genotype 4. EGYPTIAN LIVER JOURNAL 2014. [DOI: 10.1097/01.elx.0000454686.81811.1a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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130
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Liver Med23 ablation improves glucose and lipid metabolism through modulating FOXO1 activity. Cell Res 2014; 24:1250-65. [PMID: 25223702 PMCID: PMC4185346 DOI: 10.1038/cr.2014.120] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 07/03/2014] [Accepted: 07/27/2014] [Indexed: 12/23/2022] Open
Abstract
Mediator complex is a molecular hub integrating signaling, transcription factors, and RNA polymerase II (RNAPII) machinery. Mediator MED23 is involved in adipogenesis and smooth muscle cell differentiation, suggesting its role in energy homeostasis. Here, through the generation and analysis of a liver-specific Med23-knockout mouse, we found that liver Med23 deletion improved glucose and lipid metabolism, as well as insulin responsiveness, and prevented diet-induced obesity. Remarkably, acute hepatic Med23 knockdown in db/db mice significantly improved the lipid profile and glucose tolerance. Mechanistically, MED23 participates in gluconeogenesis and cholesterol synthesis through modulating the transcriptional activity of FOXO1, a key metabolic transcription factor. Indeed, hepatic Med23 deletion impaired the Mediator and RNAPII recruitment and attenuated the expression of FOXO1 target genes. Moreover, this functional interaction between FOXO1 and MED23 is evolutionarily conserved, as the in vivo activities of dFOXO in larval fat body and in adult wing can be partially blocked by Med23 knockdown in Drosophila. Collectively, our data revealed Mediator MED23 as a novel regulator for energy homeostasis, suggesting potential therapeutic strategies against metabolic diseases.
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131
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Jiang S, Yan C, Fang QC, Shao ML, Zhang YL, Liu Y, Deng YP, Shan B, Liu JQ, Li HT, Yang L, Zhou J, Dai Z, Liu Y, Jia WP. Fibroblast growth factor 21 is regulated by the IRE1α-XBP1 branch of the unfolded protein response and counteracts endoplasmic reticulum stress-induced hepatic steatosis. J Biol Chem 2014; 289:29751-65. [PMID: 25170079 DOI: 10.1074/jbc.m114.565960] [Citation(s) in RCA: 149] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Endoplasmic reticulum (ER) stress activates the adaptive unfolded protein response (UPR) and represents a critical mechanism that underlies metabolic dysfunctions. Fibroblast growth factor 21 (FGF21), a hormone that is predominantly secreted by the liver, exerts a broad range of effects upon the metabolism of carbohydrates and lipids. Although increased circulating levels of FGF21 have been documented in animal models and human subjects with obesity and nonalcoholic fatty liver disease, the functional interconnections between metabolic ER stress and FGF21 are incompletely understood. Here, we report that increased ER stress along with the simultaneous elevation of FGF21 expression were associated with the occurrence of nonalcoholic fatty liver disease both in diet-induced obese mice and human patients. Intraperitoneal administration of the ER stressor tunicamycin in mice resulted in hepatic steatosis, accompanied by activation of the three canonical UPR branches and increased the expression of FGF21. Furthermore, the IRE1α-XBP1 pathway of the UPR could directly activate the transcriptional expression of Fgf21. Administration of recombinant FGF21 in mice alleviated tunicamycin-induced liver steatosis, in parallel with reduced eIF2α-ATF4-CHOP signaling. Taken together, these results suggest that FGF21 is an integral physiological component of the cellular UPR program, which exerts beneficial feedback effects upon lipid metabolism through counteracting ER stress.
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Affiliation(s)
- Shan Jiang
- From the Shanghai Key Laboratory of Diabetes Mellitus, Department of Endocrinology and Metabolism, Shanghai Diabetes Institute, Shanghai Clinical Center for Diabetes, and Shanghai Key Clinical Center for Metabolic Disease, Shanghai JiaoTong University Affiliated Sixth People's Hospital, Shanghai 200233
| | - Cheng Yan
- the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai 200031, and
| | - Qi-chen Fang
- From the Shanghai Key Laboratory of Diabetes Mellitus, Department of Endocrinology and Metabolism, Shanghai Diabetes Institute, Shanghai Clinical Center for Diabetes, and Shanghai Key Clinical Center for Metabolic Disease, Shanghai JiaoTong University Affiliated Sixth People's Hospital, Shanghai 200233
| | - Meng-le Shao
- the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai 200031, and
| | - Yong-liang Zhang
- the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai 200031, and
| | - Yang Liu
- the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai 200031, and
| | - Yi-ping Deng
- the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai 200031, and
| | - Bo Shan
- the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai 200031, and
| | - Jing-qi Liu
- the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai 200031, and
| | - Hua-ting Li
- From the Shanghai Key Laboratory of Diabetes Mellitus, Department of Endocrinology and Metabolism, Shanghai Diabetes Institute, Shanghai Clinical Center for Diabetes, and Shanghai Key Clinical Center for Metabolic Disease, Shanghai JiaoTong University Affiliated Sixth People's Hospital, Shanghai 200233
| | - Liu Yang
- the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai 200031, and
| | - Jian Zhou
- the Department of Liver Surgery, Liver Cancer Institute, Zhongshan Hospital, Fudan University, Shanghai 200032, China
| | - Zhi Dai
- the Department of Liver Surgery, Liver Cancer Institute, Zhongshan Hospital, Fudan University, Shanghai 200032, China
| | - Yong Liu
- the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai 200031, and
| | - Wei-ping Jia
- From the Shanghai Key Laboratory of Diabetes Mellitus, Department of Endocrinology and Metabolism, Shanghai Diabetes Institute, Shanghai Clinical Center for Diabetes, and Shanghai Key Clinical Center for Metabolic Disease, Shanghai JiaoTong University Affiliated Sixth People's Hospital, Shanghai 200233,
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Comparative proteomic study reveals 17β-HSD13 as a pathogenic protein in nonalcoholic fatty liver disease. Proc Natl Acad Sci U S A 2014; 111:11437-42. [PMID: 25028495 DOI: 10.1073/pnas.1410741111] [Citation(s) in RCA: 152] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is characterized by a massive accumulation of lipid droplets (LDs). The aim of this study was to determine the function of 17β-hydroxysteroid dehydrogenase-13 (17β-HSD13), one of our newly identified LD-associated proteins in human subjects with normal liver histology and simple steatosis, in NAFLD development. LDs were isolated from 21 human liver biopsies, including 9 cases with normal liver histology (group 1) and 12 cases with simple steatosis (group 2). A complete set of LD-associated proteins from three liver samples of group 1 or group 2 were determined by 2D LC-MS/MS. By comparing the LD-associated protein profiles between subjects with or without NAFLD, 54 up-regulated and 35 down-regulated LD-associated proteins were found in NAFLD patients. Among them, 17β-HSD13 represents a previously unidentified LD-associated protein with a significant up-regulation in NAFLD. Because the 17β-HSD family plays an important role in lipid metabolism, 17β-HSD13 was selected for validating the proteomic findings and exploring its role in the pathogenesis of NAFLD. Increased hepatic 17β-HSD13 and its LD surface location were confirmed in db/db (diabetic) and high-fat diet-fed mice. Adenovirus-mediated hepatic overexpression of human 17β-HSD13 induced a fatty liver phenotype in C57BL/6 mice, with a significant increase in mature sterol regulatory element-binding protein 1 and fatty acid synthase levels. The present study reports an extensive set of human liver LD proteins and an array of proteins differentially expressed in human NAFLD. We also identified 17β-HSD13 as a pathogenic protein in the development of NAFLD.
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133
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Xiao F, Yu J, Guo Y, Deng J, Li K, Du Y, Chen S, Zhu J, Sheng H, Guo F. Effects of individual branched-chain amino acids deprivation on insulin sensitivity and glucose metabolism in mice. Metabolism 2014; 63:841-50. [PMID: 24684822 DOI: 10.1016/j.metabol.2014.03.006] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 02/21/2014] [Accepted: 03/12/2014] [Indexed: 12/12/2022]
Abstract
OBJECTIVE We recently discovered that leucine deprivation increases hepatic insulin sensitivity via general control nondepressible (GCN) 2/mammalian target of rapamycin (mTOR) and AMP-activated protein kinase (AMPK) pathways. The goal of the present study was to investigate whether the above effects were leucine specific or were also induced by deficiency of other branched chain amino acids including valine and isoleucine. METHODS Following depletion of BCAAs, changes in metabolic parameters and the expression of genes and proteins involved in regulation of insulin sensitivity and glucose metabolism were analyzed in mice and cell lines including human HepG2 cells, primary mouse hepatocytes and a mouse myoblast cell line C2C12. RESULTS Valine or isoleucine deprivation for 7 days has similar effect on improving insulin sensitivity as leucine, in wild type and insulin-resistant mice models. These effects are possibly mediated by decreased mTOR/S6K1 and increased AMPK signaling pathways, in a GCN2-dependent manner. Similar observations were obtained in in vitro studies. In contrast to leucine withdrawal, valine or isoleucine deprivation for 7 days significantly decreased fed blood glucose levels, possibly due to reduced expression of a key gluconeogenesis gene, glucose-6-phosphatase. Finally, insulin sensitivity was rapidly improved in mice 1 day following maintenance on a diet deficient for any individual BCAAs. CONCLUSIONS Our results show that while improvement on insulin sensitivity is a general feature of BCAAs depletion, individual BCAAs have specific effects on metabolic pathways, including those that regulate glucose level. These observations provide a conceptual framework for delineating the molecular mechanisms that underlie amino acid regulation of insulin sensitivity.
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Affiliation(s)
- Fei Xiao
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, the Graduate School of the Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, China 200031.
| | - Junjie Yu
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, the Graduate School of the Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, China 200031.
| | - Yajie Guo
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, the Graduate School of the Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, China 200031.
| | - Jiali Deng
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, the Graduate School of the Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, China 200031.
| | - Kai Li
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, the Graduate School of the Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, China 200031.
| | - Ying Du
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, the Graduate School of the Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, China 200031.
| | - Shanghai Chen
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, the Graduate School of the Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, China 200031.
| | - Jianmin Zhu
- Shanghai Xuhui Central Hospital, 966 Huaihai Middle Road, Shanghai, China 200030.
| | - Hongguang Sheng
- Shanghai Xuhui Central Hospital, 966 Huaihai Middle Road, Shanghai, China 200030.
| | - Feifan Guo
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, the Graduate School of the Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, China 200031.
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Wang QA, Scherer PE, Gupta RK. Improved methodologies for the study of adipose biology: insights gained and opportunities ahead. J Lipid Res 2014; 55:605-24. [PMID: 24532650 PMCID: PMC3966696 DOI: 10.1194/jlr.r046441] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Revised: 02/10/2014] [Indexed: 12/14/2022] Open
Abstract
Adipocyte differentiation and function have become areas of intense focus in the field of energy metabolism; however, understanding the role of specific genes in the establishment and maintenance of fat cell function can be challenging and complex. In this review, we offer practical guidelines for the study of adipocyte development and function. We discuss improved cellular and genetic systems for the study of adipose biology and highlight recent insights gained from these new approaches.
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Affiliation(s)
- Qiong A. Wang
- Department of Internal Medicine, Touchstone Diabetes Center, and University of Texas Southwestern Medical Center, Dallas, TX 75287
| | - Philipp E. Scherer
- Department of Internal Medicine, Touchstone Diabetes Center, and University of Texas Southwestern Medical Center, Dallas, TX 75287
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75287
| | - Rana K. Gupta
- Department of Internal Medicine, Touchstone Diabetes Center, and University of Texas Southwestern Medical Center, Dallas, TX 75287
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135
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Iron metabolism regulates p53 signaling through direct heme-p53 interaction and modulation of p53 localization, stability, and function. Cell Rep 2014; 7:180-93. [PMID: 24685134 PMCID: PMC4219651 DOI: 10.1016/j.celrep.2014.02.042] [Citation(s) in RCA: 161] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 12/02/2013] [Accepted: 02/27/2014] [Indexed: 02/06/2023] Open
Abstract
Iron excess is closely associated with tumorigenesis in multiple types of human cancers, with underlying mechanisms yet unclear. Recently, iron deprivation has emerged as a major strategy for chemotherapy, but it exerts tumor suppression only on select human malignancies. Here, we report that the tumor suppressor protein p53 is downregulated during iron excess. Strikingly, the iron polyporphyrin heme binds to p53 protein, interferes with p53-DNA interactions, and triggers both nuclear export and cytosolic degradation of p53. Moreover, in a tumorigenicity assay, iron deprivation suppressed wild-type p53-dependent tumor growth, suggesting that upregulation of wild-type p53 signaling underlies the selective efficacy of iron deprivation. Our findings thus identify a direct link between iron/heme homeostasis and the regulation of p53 signaling, which not only provides mechanistic insights into iron-excess-associated tumorigenesis but may also help predict and improve outcomes in iron-deprivation-based chemotherapy.
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136
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Sahini N, Borlak J. Recent insights into the molecular pathophysiology of lipid droplet formation in hepatocytes. Prog Lipid Res 2014; 54:86-112. [PMID: 24607340 DOI: 10.1016/j.plipres.2014.02.002] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 02/17/2014] [Accepted: 02/21/2014] [Indexed: 12/11/2022]
Abstract
Triacyglycerols are a major energy reserve of the body and are normally stored in adipose tissue as lipid droplets (LDs). The liver, however, stores energy as glycogen and digested triglycerides in the form of fatty acids. In stressed condition such as obesity, imbalanced nutrition and drug induced liver injury hepatocytes accumulate excess lipids in the form of LDs whose prolonged storage leads to disease conditions most notably non-alcoholic fatty liver disease (NAFLD). Fatty liver disease has become a major health burden with more than 90% of obese, nearly 70% of overweight and about 25% of normal weight patients being affected. Notably, research in recent years has shown LD as highly dynamic organelles for maintaining lipid homeostasis through fat storage, protein sorting and other molecular events studied in adipocytes and other cells of living organisms. This review focuses on the molecular events of LD formation in hepatocytes and the importance of cross talk between different cell types and their signalling in NAFLD as to provide a perspective on molecular mechanisms as well as possibilities for different therapeutic intervention strategies.
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Affiliation(s)
- Nishika Sahini
- Centre for Pharmacology and Toxicology, Hannover Medical School, 30625 Hannover, Germany
| | - Jürgen Borlak
- Centre for Pharmacology and Toxicology, Hannover Medical School, 30625 Hannover, Germany.
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137
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Kim S, Choi Y, Choi S, Choi Y, Park T. Dietary camphene attenuates hepatic steatosis and insulin resistance in mice. Obesity (Silver Spring) 2014; 22:408-17. [PMID: 23818423 DOI: 10.1002/oby.20554] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 05/18/2013] [Accepted: 05/27/2013] [Indexed: 11/11/2022]
Abstract
OBJECTIVE The aim of this study was to investigate the protective effects of camphene on high-fat diet (HFD)-induced hepatic steatosis and insulin resistance in mice and to elucidate its mechanism of action. DESIGN AND METHODS Male C57BL/6N mice were fed with a normal diet, HFD (20% fat and 1% cholesterol of total diet), or HFD supplemented with 0.2% camphene (CPND) for 10 weeks. RESULTS Camphene alleviated the HFD-induced increases in liver weight and hepatic lipid levels in mice. Camphene also increased circulating adiponectin levels. To examine the direct effects of camphene on adiponectin secretion, 3T3-L1 adipocytes were incubated with camphene. Consistent with in vivo result, camphene increased adiponectin expression and secretion in 3T3-L1 adipocytes. In HFD-fed mice, camphene increased hepatic adiponectin receptor expression and AMP-activated protein kinase (AMPK) activation. Concordant with the activation of adiponectin-AMPK signaling, camphene increased hepatic expression of fatty acid oxidation-related genes and decreased those of lipogenesis-related genes in HFD-fed mice. Moreover, camphene increased insulin-signaling molecules activation and stimulated glucose transporter-2translocation to the plasma membrane in the liver. CONCLUSIONS These results suggest camphene prevents HFD-induced hepatic steatosis and insulin resistance in mice; furthermore, these protective effects are mediated via the activation of adiponectin-AMPK signaling.
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Affiliation(s)
- Sohee Kim
- Department of Food and Nutrition, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 120-749, South Korea
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Migita T, Okabe S, Ikeda K, Igarashi S, Sugawara S, Tomida A, Soga T, Taguchi R, Seimiya H. Inhibition of ATP citrate lyase induces triglyceride accumulation with altered fatty acid composition in cancer cells. Int J Cancer 2013; 135:37-47. [PMID: 24310723 DOI: 10.1002/ijc.28652] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 11/16/2013] [Accepted: 11/19/2013] [Indexed: 01/17/2023]
Abstract
De novo lipogenesis is activated in most cancers and several lipogenic enzymes have been implicated as therapeutic targets. Here, we demonstrate a novel function of the lipogenic enzyme, ATP citrate lyase (ACLY), in lipid metabolism in cancer cells. ACLY depletion by small interfering RNAs caused growth suppression and/or apoptosis in a subset of cancer cell lines. To investigate the effect of ACLY inhibition on lipid metabolism, metabolome and transcriptome analysis was performed. ACLY depletion blocks the fatty acid chain elongation from C16 to C18 in triglyceride (TG), but not in other lipid classes. Meanwhile, wild-type ACLY overexpression enhanced fatty acid elongation of TG, whereas an inactive mutant ACLY did not change it. ACLY depletion-mediated blockade of fatty acid elongation was coincident with downregulation of long-chain fatty acid elongase ELOVL6, which resides in endoplasmic reticulum (ER). Paradoxically, ACLY depletion-mediated growth suppression was associated with TG accumulation. ACLY depletion downregulated the expression of carnitine palmitoyltransferase 1A, which is a mitochondrial fatty acid transporter. Consistent with this finding, metabolome analysis revealed that ACLY positively regulates the carnitine system, which plays as an essential cofactor for fatty acid transport across mitochondrial membrane. AICAR, an activator of mitochondrial fatty acid oxidation (FAO), significantly reduced ACLY depletion-mediated TG accumulation. These data indicate that inhibition of ACLY might affect both fatty acid elongation in ER and FAO in mitochondria, thereby explaining the TG accumulation with altered fatty acid composition. This phenotype may be a hallmark of growth suppression mediated by ACLY inhibition.
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Affiliation(s)
- Toshiro Migita
- Division of Molecular Biotherapy Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, Tokyo, Japan; Department of Molecular Medical Research, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
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139
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Cytosolic functions of MORC2 in lipogenesis and adipogenesis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1843:316-26. [PMID: 24286864 DOI: 10.1016/j.bbamcr.2013.11.012] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 11/15/2013] [Accepted: 11/18/2013] [Indexed: 11/24/2022]
Abstract
Microrchidia (MORC) family CW-type zinc finger 2 (MORC2) has been shown to be involved in several nuclear processes, including transcription modulation and DNA damage repair. However, its cytosolic function remains largely unknown. Here, we report an interaction between MORC2 and adenosine triphosphate (ATP)-citrate lyase (ACLY), an enzyme that catalyzes the formation of acetyl-coA and plays a central role in lipogenesis, cholesterogenesis, and histone acetylation. Furthermore, we demonstrate that MORC2 promotes ACLY activation in the cytosol of lipogenic breast cancer cells and plays an essential role in lipogenesis, adipogenesis and differentiation of 3T3-L1 preadipocytic cells. Consistently, the expression of MORC2 is induced during the process of 3T3-L1 adipogenic differentiation and mouse mammary gland development at a stage of increased lipogenesis. This observation was accompanied by a high ACLY activity. Together, these results demonstrate a cytosolic function of MORC2 in lipogenesis, adipogenic differentiation, and lipid homeostasis by regulating the activity of ACLY.
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140
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Wang C, Li H, Meng Q, Du Y, Xiao F, Zhang Q, Yu J, Li K, Chen S, Huang Z, Liu B, Guo F. ATF4 deficiency protects hepatocytes from oxidative stress via inhibiting CYP2E1 expression. J Cell Mol Med 2013; 18:80-90. [PMID: 24373582 PMCID: PMC3916120 DOI: 10.1111/jcmm.12166] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Accepted: 09/16/2013] [Indexed: 01/08/2023] Open
Abstract
Activating transcription factor (ATF) 4 is involved in the regulation of oxidative stress in fibroblasts and neurons. The role of ATF4 in hepatocytes, however, is unknown. The aim of this study was to investigate the role of ATF4 in hepatocytes in oxidative stress under a high-fat diet (HFD). Here, we showed that palmitate-stimulated reactive oxygen species (ROS) production and triglyceride (TG) accumulation is blocked by ATF4 deficiency in primary hepatocytes. Consistently, HFD-induced oxidative stress, TG accumulation and expression of cytochrome P450, family 2, subfamily, polypeptide 1 (CYP2E1) are also blocked by knocking down ATF4 expression in the mouse liver. This suggests that ATF4 might regulate oxidative stress viaCYP2E1 under an HFD. In addition, we observed that expression of CYP2E1 is indirectly regulated by ATF4 in a cAMP-responsive element binding protein (CREB)-dependent manner, which can directly activate the CYP2E1 promoter activity. Notably, ATF4-stimulated ROS production is inhibited in vivo by treatment with diallyl sulphide, a selective CYP2E1 inhibitor. Finally, we showed that ATF4 expression in the liver is responsible for the protective effects against HFD-induced CYP2E1 expression, oxidative stress, and TG accumulation. Taken together, these observations suggest that ATF4 is a novel regulator of oxidative stress as well as accumulation of TG in response to HFD.
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Affiliation(s)
- Chunxia Wang
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, The Graduate School of the Chinese Academy of Sciences, Shanghai, China
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141
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Yu J, Xiao F, Zhang Q, Liu B, Guo Y, Lv Z, Xia T, Chen S, Li K, Du Y, Guo F. PRLR regulates hepatic insulin sensitivity in mice via STAT5. Diabetes 2013; 62:3103-13. [PMID: 23775766 PMCID: PMC3749345 DOI: 10.2337/db13-0182] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Insulin resistance is one of the major contributing factors in the development of metabolic diseases. The mechanisms responsible for insulin resistance, however, remain poorly understood. Although numerous functions of the prolactin receptor (PRLR) have been identified, a direct effect on insulin sensitivity has not been previously described. The aim of our current study is to investigate this possibility and elucidate underlying mechanisms. Here we show that insulin sensitivity is improved or impaired in mice injected with adenovirus that overexpress or knock down PRLR expression, respectively. Similar observations were obtained in in vitro studies. In addition, we discovered that the signal transducer and activator of transcription-5 pathway are required for regulating insulin sensitivity by PRLR. Moreover, we observed that PRLR expression is decreased or increased under insulin-resistant (db/db mice) or insulin-sensitive (leucine deprivation) conditions, respectively, and found that altering PRLR expression significantly reverses insulin sensitivity under both conditions. Finally, we found that PRLR expression levels are increased under leucine deprivation via a general control nonderepressible 2/mammalian target of rapamycin/ribosomal protein S6 kinase-1-dependent pathway. These results demonstrate a novel function for hepatic PRLR in the regulation of insulin sensitivity and provide important insights concerning the nutritional regulation of PRLR expression.
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142
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DNA methylation analysis in nonalcoholic fatty liver disease suggests distinct disease-specific and remodeling signatures after bariatric surgery. Cell Metab 2013; 18:296-302. [PMID: 23931760 DOI: 10.1016/j.cmet.2013.07.004] [Citation(s) in RCA: 377] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 05/12/2013] [Accepted: 07/12/2013] [Indexed: 12/11/2022]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disorder in industrialized countries. Liver samples from morbidly obese patients (n = 45) with all stages of NAFLD and controls (n = 18) were analyzed by array-based DNA methylation and mRNA expression profiling. NAFLD-specific expression and methylation differences were seen for nine genes coding for key enzymes in intermediate metabolism (including PC, ACLY, and PLCG1) and insulin/insulin-like signaling (including IGF1, IGFBP2, and PRKCE) and replicated by bisulfite pyrosequening (independent n = 39). Transcription factor binding sites at NAFLD-specific CpG sites were >1,000-fold enriched for ZNF274, PGC1A, and SREBP2. Intraindividual comparison of liver biopsies before and after bariatric surgery showed NAFLD-associated methylation changes to be partially reversible. Postbariatric and NAFLD-specific methylation signatures were clearly distinct both in gene ontology and transcription factor binding site analyses, with >400-fold enrichment of NRF1, HSF1, and ESRRA sites. Our findings provide an example of treatment-induced epigenetic organ remodeling in humans.
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143
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Wu J, Wang C, Li S, Li S, Wang W, Li J, Chi Y, Yang H, Kong X, Zhou Y, Dong C, Wang F, Xu G, Yang J, Gustafsson JÅ, Guan Y. Thyroid hormone-responsive SPOT 14 homolog promotes hepatic lipogenesis, and its expression is regulated by liver X receptor α through a sterol regulatory element-binding protein 1c-dependent mechanism in mice. Hepatology 2013; 58:617-28. [PMID: 23348573 DOI: 10.1002/hep.26272] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Accepted: 12/20/2012] [Indexed: 01/02/2023]
Abstract
UNLABELLED The protein, thyroid hormone-responsive SPOT 14 homolog (Thrsp), has been reported to be a lipogenic gene in cultured hepatocytes, implicating an important role of Thrsp in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Thrsp expression is known to be regulated by a variety of transcription factors, including thyroid hormone receptor, pregnane X receptor, and constitutive androstane receptor. Emerging in vitro evidence also points to a critical role of liver X receptor (LXR) in regulating Thrsp transcription in hepatocytes. In the present study, we showed that Thrsp was up-regulated in livers of db/db mice and high-fat-diet-fed mice, two models of murine NAFLD. Hepatic overexpression of Thrsp increased triglyceride accumulation with enhanced lipogenesis in livers of C57Bl/6 mice, whereas hepatic Thrsp gene silencing attenuated the fatty liver phenotype in db/db mice. LXR activator TO901317 induced Thrsp expression in livers of wild-type (WT) and LXR-β gene-deficient mice, but not in LXR-α or LXR-α/β double-knockout mice. TO901317 treatment significantly enhanced hepatic sterol regulatory element-binding protein 1c (SREBP-1c) expression and activity in WT mice, but failed to induce Thrsp expression in SREBP-1c gene-deficient mice. Sequence analysis revealed four LXR response-element-like elements and one sterol regulatory element (SRE)-binding site within a -2,468 ∼+1-base-pair region of the Thrsp promoter. TO901317 treatment and LXR-α overexpression failed to induce, whereas overexpression of SREBP-1c significantly increased Thrsp promoter activity. Moreover, deletion of the SRE site completely abolished SREBP-1c-induced Thrsp transcription. CONCLUSION Thrsp is a lipogenic gene in the liver that is induced by the LXR agonist through an LXR-α-mediated, SREBP-1c-dependent mechanism. Therefore, Thrsp may represent a potential therapeutic target for the treatment of NAFLD.
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Affiliation(s)
- Jing Wu
- Department of Physiology and Pathophysiology, Peking University Health Science Center, Key Laboratory of Cardiovascular Science of the Ministry of Education, Beijing, China
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144
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Cho Y, Chung JH, Do HJ, Jeon HJ, Jin T, Shin MJ. Effects of fisetin supplementation on hepatic lipogenesis and glucose metabolism in Sprague–Dawley rats fed on a high fat diet. Food Chem 2013; 139:720-7. [DOI: 10.1016/j.foodchem.2013.01.060] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2012] [Revised: 01/16/2013] [Accepted: 01/19/2013] [Indexed: 02/06/2023]
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145
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Abstract
As rates of obesity soar in the Unites States and around the world, cancer attributed to obesity has emerged as major threat to public health. The link between obesity and cancer can be attributed in part to the state of chronic inflammation that develops in obesity. Acetyl-CoA production and protein acetylation patterns are highly sensitive to metabolic state and are significantly altered in obesity. In this article, we explore the potential role of nutrient-sensitive lysine acetylation in regulating inflammatory processes in obesity-linked cancer.
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Affiliation(s)
- Joyce V Lee
- Department of Cancer Biology, Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
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146
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Miraldi ER, Sharfi H, Friedline RH, Johnson H, Zhang T, Lau KS, Ko HJ, Curran TG, Haigis KM, Yaffe MB, Bonneau R, Lauffenburger DA, Kahn BB, Kim JK, Neel BG, Saghatelian A, White FM. Molecular network analysis of phosphotyrosine and lipid metabolism in hepatic PTP1b deletion mice. Integr Biol (Camb) 2013; 5:940-63. [PMID: 23685806 DOI: 10.1039/c3ib40013a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Metabolic syndrome describes a set of obesity-related disorders that increase diabetes, cardiovascular, and mortality risk. Studies of liver-specific protein-tyrosine phosphatase 1b (PTP1b) deletion mice (L-PTP1b(-/-)) suggest that hepatic PTP1b inhibition would mitigate metabolic-syndrome through amelioration of hepatic insulin resistance, endoplasmic-reticulum stress, and whole-body lipid metabolism. However, the altered molecular-network states underlying these phenotypes are poorly understood. We used mass spectrometry to quantify protein-phosphotyrosine network changes in L-PTP1b(-/-) mouse livers relative to control mice on normal and high-fat diets. We applied a phosphosite-set-enrichment analysis to identify known and novel pathways exhibiting PTP1b- and diet-dependent phosphotyrosine regulation. Detection of a PTP1b-dependent, but functionally uncharacterized, set of phosphosites on lipid-metabolic proteins motivated global lipidomic analyses that revealed altered polyunsaturated-fatty-acid (PUFA) and triglyceride metabolism in L-PTP1b(-/-) mice. To connect phosphosites and lipid measurements in a unified model, we developed a multivariate-regression framework, which accounts for measurement noise and systematically missing proteomics data. This analysis resulted in quantitative models that predict roles for phosphoproteins involved in oxidation-reduction in altered PUFA and triglyceride metabolism.
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Affiliation(s)
- Emily R Miraldi
- Computational and Systems Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Pinkosky SL, Filippov S, Srivastava RAK, Hanselman JC, Bradshaw CD, Hurley TR, Cramer CT, Spahr MA, Brant AF, Houghton JL, Baker C, Naples M, Adeli K, Newton RS. AMP-activated protein kinase and ATP-citrate lyase are two distinct molecular targets for ETC-1002, a novel small molecule regulator of lipid and carbohydrate metabolism. J Lipid Res 2012; 54:134-51. [PMID: 23118444 DOI: 10.1194/jlr.m030528] [Citation(s) in RCA: 168] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
ETC-1002 (8-hydroxy-2,2,14,14-tetramethylpentadecanedioic acid) is a novel investigational drug being developed for the treatment of dyslipidemia and other cardio-metabolic risk factors. The hypolipidemic, anti-atherosclerotic, anti-obesity, and glucose-lowering properties of ETC-1002, characterized in preclinical disease models, are believed to be due to dual inhibition of sterol and fatty acid synthesis and enhanced mitochondrial long-chain fatty acid β-oxidation. However, the molecular mechanism(s) mediating these activities remained undefined. Studies described here show that ETC-1002 free acid activates AMP-activated protein kinase in a Ca(2+)/calmodulin-dependent kinase β-independent and liver kinase β 1-dependent manner, without detectable changes in adenylate energy charge. Furthermore, ETC-1002 is shown to rapidly form a CoA thioester in liver, which directly inhibits ATP-citrate lyase. These distinct molecular mechanisms are complementary in their beneficial effects on lipid and carbohydrate metabolism in vitro and in vivo. Consistent with these mechanisms, ETC-1002 treatment reduced circulating proatherogenic lipoproteins, hepatic lipids, and body weight in a hamster model of hyperlipidemia, and it reduced body weight and improved glycemic control in a mouse model of diet-induced obesity. ETC-1002 offers promise as a novel therapeutic approach to improve multiple risk factors associated with metabolic syndrome and benefit patients with cardiovascular disease.
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148
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Hasegawa S, Noda K, Maeda A, Matsuoka M, Yamasaki M, Fukui T. Acetoacetyl-CoA synthetase, a ketone body-utilizing enzyme, is controlled by SREBP-2 and affects serum cholesterol levels. Mol Genet Metab 2012; 107:553-60. [PMID: 22985732 DOI: 10.1016/j.ymgme.2012.08.017] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Accepted: 08/21/2012] [Indexed: 01/20/2023]
Abstract
Ketone bodies have been regarded as an energy source that is mainly produced in the liver, and exported to extrahepatic tissues. However, ketone bodies have also been suggested to be used during the lipogenesis by the ketone body-utilizing enzyme, acetoacetyl-CoA synthetase (AACS). To elucidate the physiological role of AACS in the liver, we investigated the mechanism of transcription of the AACS gene and performed knockdown experiments. We showed that SREBP-2 regulates the expression of AACS and that knockdown of AACS in vivo, by the hydrodynamics method, resulted in the reduction of total blood cholesterol. These results suggest that ketone body metabolism via AACS activity plays an important role in cholesterol homeostasis.
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Affiliation(s)
- Shinya Hasegawa
- Department of Health Chemistry, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan.
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149
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Zhang Y, Zhou B, Zhang F, Wu J, Hu Y, Liu Y, Zhai Q. Amyloid-β induces hepatic insulin resistance by activating JAK2/STAT3/SOCS-1 signaling pathway. Diabetes 2012; 61:1434-43. [PMID: 22522613 PMCID: PMC3357286 DOI: 10.2337/db11-0499] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Epidemiological studies indicate that patients with Alzheimer's disease (AD) have an increased risk of developing type 2 diabetes mellitus (T2DM), and experimental studies suggest that AD exacerbates T2DM, but the underlying mechanism is still largely unknown. This study aims to investigate whether amyloid-β (Aβ), a key player in AD pathogenesis, contributes to the development of insulin resistance, as well as the underlying mechanism. We find that plasma Aβ40/42 levels are increased in patients with hyperglycemia. APPswe/PSEN1dE9 transgenic AD model mice with increased plasma Aβ40/42 levels show impaired glucose and insulin tolerance and hyperinsulinemia. Furthermore, Aβ impairs insulin signaling in mouse liver and cultured hepatocytes. Aβ can upregulate suppressors of cytokine signaling (SOCS)-1, a well-known insulin signaling inhibitor. Knockdown of SOCS-1 alleviates Aβ-induced impairment of insulin signaling. Moreover, JAK2/STAT3 is activated by Aβ, and inhibition of JAK2/STAT3 signaling attenuates Aβ-induced upregulation of SOCS-1 and insulin resistance in hepatocytes. Our results demonstrate that Aβ induces hepatic insulin resistance by activating JAK2/STAT3/SOCS-1 signaling pathway and have implications toward resolving insulin resistance and T2DM.
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150
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ATP-citrate lyase: a mini-review. Biochem Biophys Res Commun 2012; 422:1-4. [PMID: 22575446 DOI: 10.1016/j.bbrc.2012.04.144] [Citation(s) in RCA: 153] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Accepted: 04/26/2012] [Indexed: 02/07/2023]
Abstract
ATP-citrate lyase (ACLY) is a cytosolic enzyme that catalyzes generation of acetyl-CoA from citrate. Acetyl-CoA is a vital building block for the endogenous biosynthesis of fatty acids and cholesterol and is involved in isoprenoid-based protein modifications. Acetyl-CoA is also required for acetylation reactions that modify proteins such as histone acetylation. In the present review some of the known features of ACLY such as tissue distribution, subcellular localization, enzymatic properties, gene regulation and associated physiological conditions are highlighted.
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