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Ye C, Jiang W, Hu T, Liang J, Chen Y. The Regulatory Impact of CFLAR Methylation Modification on Liver Lipid Metabolism. Int J Mol Sci 2024; 25:7897. [PMID: 39063139 PMCID: PMC11277202 DOI: 10.3390/ijms25147897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2024] [Revised: 07/11/2024] [Accepted: 07/17/2024] [Indexed: 07/28/2024] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) has emerged as the leading cause of chronic liver disease worldwide. Caspase 8 and FADD-like apoptosis regulator (CFLAR) has been identified as a potent factor in mitigating non-alcoholic steatohepatitis (NASH) by inhibiting the N-terminal dimerization of apoptosis signal-regulating kinase 1 (ASK1). While arginine methyltransferase 1 (PRMT1) was previously reported to be associated with increased hepatic glucose production, its involvement in hepatic lipid metabolism remains largely unexplored. The interaction between PRMT1 and CFLAR and the methylation of CFLAR were verified by Co-IP and immunoblotting assays. Recombinant adenoviruses were generated for overexpression or knockdown of PRMT1 in hepatocytes. The role of PRMT1 in NAFLD was investigated in normal and high-fat diet-induced obese mice. In this study, we found a significant upregulation of PRMT1 and downregulation of CFLAR after 48h of fasting, while the latter significantly rebounded after 12h of refeeding. The expression of PRMT1 increased in the livers of mice fed a methionine choline-deficient (MCD) diet and in hepatocytes challenged with oleic acid (OA)/palmitic acid (PA). Overexpression of PRMT1 not only inhibited the expression of genes involved in fatty acid oxidation (FAO) and promoted the expression of genes involved in fatty acid synthesis (FAS), resulting in increased triglyceride accumulation in primary hepatocytes, but also enhanced the gluconeogenesis of primary hepatocytes. Conversely, knockdown of hepatic PRMT1 significantly alleviated MCD diet-induced hepatic lipid metabolism abnormalities and liver injury in vivo, possibly through the upregulation of CFLAR protein levels. Knockdown of PRMT1 suppressed the expression of genes related to FAS and enhanced the expression of genes involved in FAO, causing decreased triglyceride accumulation in OA/PA-treated primary hepatocytes in vitro. Although short-term overexpression of PRMT1 had no significant effect on hepatic triglyceride levels under physiological conditions, it resulted in increased serum triglyceride and fasting blood glucose levels in normal C57BL/6J mice. More importantly, PRMT1 was observed to interact with and methylate CFLAR, ultimately leading to its ubiquitination-mediated protein degradation. This process subsequently triggered the activation of c-Jun N-terminal kinase 1 (JNK1) and lipid deposition in primary hepatocytes. Together, these results suggested that PRMT1-mediated methylation of CFLAR plays a critical role in hepatic lipid metabolism. Targeting PRMT1 for drug design may represent a promising strategy for the treatment of NAFLD.
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Affiliation(s)
| | | | | | - Jichao Liang
- National & Local Joint Engineering Research Center of High throughput Drug Screening Technology, Hubei Province Key Laboratory of Biotechnology of Chinese Traditional Medicine, College of Health Science and Engineering, Hubei University, Wuhan 430062, China; (C.Y.); (W.J.); (T.H.)
| | - Yong Chen
- National & Local Joint Engineering Research Center of High throughput Drug Screening Technology, Hubei Province Key Laboratory of Biotechnology of Chinese Traditional Medicine, College of Health Science and Engineering, Hubei University, Wuhan 430062, China; (C.Y.); (W.J.); (T.H.)
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2
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Johnson SM, Bao H, McMahon CE, Chen Y, Burr SD, Anderson AM, Madeyski-Bengtson K, Lindén D, Han X, Liu J. PNPLA3 is a triglyceride lipase that mobilizes polyunsaturated fatty acids to facilitate hepatic secretion of large-sized very low-density lipoprotein. Nat Commun 2024; 15:4847. [PMID: 38844467 PMCID: PMC11156938 DOI: 10.1038/s41467-024-49224-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 05/22/2024] [Indexed: 06/09/2024] Open
Abstract
The I148M variant of PNPLA3 is closely associated with hepatic steatosis. Recent evidence indicates that the I148M mutant functions as an inhibitor of PNPLA2/ATGL-mediated lipolysis, leaving the role of wild-type PNPLA3 undefined. Despite showing a triglyceride hydrolase activity in vitro, PNPLA3 has yet to be established as a lipase in vivo. Here, we show that PNPLA3 preferentially hydrolyzes polyunsaturated triglycerides, mobilizing polyunsaturated fatty acids for phospholipid desaturation and enhancing hepatic secretion of triglyceride-rich lipoproteins. Under lipogenic conditions, mice with liver-specific knockout or acute knockdown of PNPLA3 exhibit aggravated liver steatosis and reduced plasma VLDL-triglyceride levels. Similarly, I148M-knockin mice show decreased hepatic triglyceride secretion during lipogenic stimulation. Our results highlight a specific context whereby the wild-type PNPLA3 facilitates the balance between hepatic triglyceride storage and secretion, and suggest the potential contribution of a loss-of-function by the I148M variant to the development of fatty liver disease in humans.
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Affiliation(s)
- Scott M Johnson
- Department of Biochemistry and Molecular Biology; Mayo Clinic College of Medicine & Science, Rochester, MN, 55905, USA
- Mayo Clinic Graduate School of Biomedical Sciences; Mayo Clinic College of Medicine & Science, Rochester, MN, 55905, USA
- Department of Cell Biology; University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Hanmei Bao
- Barshop Institute for Longevity and Aging Studies and Department of Medicine, Division of Diabetes; University of Texas Health San Antonio, San Antonio, TX, 78229, USA
| | - Cailin E McMahon
- Molecular Biology and Genetics Department; Cornell College of Agriculture and Life Sciences, Ithaca, NY, 14853, USA
| | - Yongbin Chen
- Department of Biochemistry and Molecular Biology; Mayo Clinic College of Medicine & Science, Rochester, MN, 55905, USA
| | - Stephanie D Burr
- Department of Biochemistry and Molecular Biology; Mayo Clinic College of Medicine & Science, Rochester, MN, 55905, USA
| | - Aaron M Anderson
- Department of Developmental Biology; Washington University School of Medicine in St. Louis, St. Louis, MO, 63110, USA
| | - Katja Madeyski-Bengtson
- Translational Genomics, Discovery Sciences; BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Daniel Lindén
- Bioscience Metabolism, Research and Early Development Cardiovascular, Renal and Metabolism (CVRM); BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
- Division of Endocrinology, Department of Neuroscience and Physiology; Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Xianlin Han
- Barshop Institute for Longevity and Aging Studies and Department of Medicine, Division of Diabetes; University of Texas Health San Antonio, San Antonio, TX, 78229, USA
| | - Jun Liu
- Department of Biochemistry and Molecular Biology; Mayo Clinic College of Medicine & Science, Rochester, MN, 55905, USA.
- Division of Endocrinology, Diabetes, Metabolism and Nutrition; Mayo Clinic in Rochester, Rochester, MN, 55905, USA.
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3
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Liu M, Park S. The Role of PNPLA3_rs738409 Gene Variant, Lifestyle Factors, and Bioactive Compounds in Nonalcoholic Fatty Liver Disease: A Population-Based and Molecular Approach towards Healthy Nutrition. Nutrients 2024; 16:1239. [PMID: 38674929 PMCID: PMC11054963 DOI: 10.3390/nu16081239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Revised: 04/18/2024] [Accepted: 04/19/2024] [Indexed: 04/28/2024] Open
Abstract
This study aimed to investigate the impact of a common non-synonymous gene variant (C>G, rs738409) in patatin-like phospholipase domain-containing 3 (PNPLA3), leading to the substitution of isoleucine with methionine at position 148 (PNPLA3-I148M), on susceptibility to nonalcoholic fatty liver disease (NAFLD) and explore potential therapeutic nutritional strategies targeting PNPLA3. It contributed to understanding sustainable dietary practices for managing NAFLD, recently referred to as metabolic-dysfunction-associated fatty liver. NAFLD had been diagnosed by ultrasound in a metropolitan hospital-based cohort comprising 58,701 middle-aged and older Korean individuals, identifying 2089 NAFLD patients. The interaction between PNPLA3 and lifestyle factors was investigated. In silico analyses, including virtual screening, molecular docking, and molecular dynamics simulations, were conducted to identify bioactive compounds from foods targeting PNPLA3(I148M). Subsequent cellular experiments involved treating oleic acid (OA)-exposed HepG2 cells with selected bioactive compounds, both in the absence and presence of compound C (AMPK inhibitor), targeting PNPLA3 expression. Carriers of the risk allele PNPLA3_rs738409G showed an increased association with NAFLD risk, particularly with adherence to a plant-based diet, avoidance of a Western-style diet, and smoking. Delphinidin 3-caffeoyl-glucoside, pyranocyanin A, delta-viniferin, kaempferol-7-glucoside, and petunidin 3-rutinoside emerged as potential binders to the active site residues of PNPLA3, exhibiting a reduction in binding energy. These compounds demonstrated a dose-dependent reduction in intracellular triglyceride and lipid peroxide levels in HepG2 cells, while pretreatment with compound C showed the opposite trend. Kaempferol-7-glucoside and petunidin-3-rutinoside showed potential as inhibitors of PNPLA3 expression by enhancing AMPK activity, ultimately reducing intrahepatic lipogenesis. In conclusion, there is potential for plant-based diets and specific bioactive compounds to promote sustainable dietary practices to mitigate NAFLD risk, especially in individuals with genetic predispositions.
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Affiliation(s)
- Meiling Liu
- Department of Chemical Engineering, Shanxi Institute of Science and Technology, Jincheng 048000, China;
| | - Sunmin Park
- Department of Bioconvergence, Hoseo University, Asan 31499, Republic of Korea
- Department of Food and Nutrition, Institute of Basic Science, Obesity/Diabetes Research Center, Hoseo University, Asan 31499, Republic of Korea
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4
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Yazıcı D, Demir SÇ, Sezer H. Insulin Resistance, Obesity, and Lipotoxicity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1460:391-430. [PMID: 39287860 DOI: 10.1007/978-3-031-63657-8_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/19/2024]
Abstract
Lipotoxicity, originally used to describe the destructive effects of excess fat accumulation on glucose metabolism, causes functional impairments in several metabolic pathways, both in adipose tissue and peripheral organs, like liver, heart, pancreas, and muscle. Ectopic lipid accumulation in the kidneys, liver, and heart has important clinical counterparts like diabetic nephropathy in type 2 diabetes mellitus, obesity-related glomerulopathy, nonalcoholic fatty liver disease, and cardiomyopathy. Insulin resistance due to lipotoxicity indirectly lead to reproductive system disorders, like polycystic ovary syndrome. Lipotoxicity has roles in insulin resistance and pancreatic beta-cell dysfunction. Increased circulating levels of lipids and the metabolic alterations in fatty acid utilization and intracellular signaling have been related to insulin resistance in muscle and liver. Different pathways, like novel protein kinase c pathways and the JNK-1 pathway, are involved as the mechanisms of how lipotoxicity leads to insulin resistance in nonadipose tissue organs, such as liver and muscle. Mitochondrial dysfunction plays a role in the pathogenesis of insulin resistance. Endoplasmic reticulum stress, through mainly increased oxidative stress, also plays an important role in the etiology of insulin resistance, especially seen in non-alcoholic fatty liver disease. Visceral adiposity and insulin resistance both increase the cardiometabolic risk, and lipotoxicity seems to play a crucial role in the pathophysiology of these associations.
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Affiliation(s)
- Dilek Yazıcı
- Koç University Medical School, Section of Endocrinology and Metabolism, Koç University Hospital, Topkapi, Istanbul, Turkey.
| | - Selin Çakmak Demir
- Koç University Medical School, Section of Endocrinology and Metabolism, Koç University Hospital, Topkapi, Istanbul, Turkey
| | - Havva Sezer
- Koç University Medical School, Section of Endocrinology and Metabolism, Koç University Hospital, Topkapi, Istanbul, Turkey
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Li N, Li X, Ding Y, Liu X, Diggle K, Kisseleva T, Brenner DA. SREBP Regulation of Lipid Metabolism in Liver Disease, and Therapeutic Strategies. Biomedicines 2023; 11:3280. [PMID: 38137501 PMCID: PMC10740981 DOI: 10.3390/biomedicines11123280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 11/26/2023] [Accepted: 12/06/2023] [Indexed: 12/24/2023] Open
Abstract
Sterol regulatory element-binding proteins (SREBPs) are master transcription factors that play a crucial role in regulating genes involved in the biogenesis of cholesterol, fatty acids, and triglycerides. As such, they are implicated in several serious liver diseases, including non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), fibrosis, and hepatocellular carcinoma (HCC). SREBPs are subject to regulation by multiple cofactors and critical signaling pathways, making them an important target for therapeutic interventions. In this review, we first introduce the structure and activation of SREBPs, before focusing on their function in liver disease. We examine the mechanisms by which SREBPs regulate lipogenesis, explore how alterations in these processes are associated with liver disease, and evaluate potential therapeutic strategies using small molecules, natural products, or herb extracts that target these pathways. Through this analysis, we provide new insights into the versatility and multitargets of SREBPs as factors in the modulation of different physiological stages of liver disease, highlighting their potential targets for therapeutic treatment.
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Affiliation(s)
- Na Li
- College of Medical Technology, Shanghai University of Medicine & Health Sciences, Shanghai 201318, China
- Graduate School of Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Xiaodan Li
- College of Medical Technology, Shanghai University of Medicine & Health Sciences, Shanghai 201318, China
- Graduate School of Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Yifu Ding
- State Key Laboratory of Cell Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Shanghai 200031, China;
| | - Xiao Liu
- Department of Surgery, University of California San Diego, La Jolla, CA 92093, USA (T.K.)
| | - Karin Diggle
- Department of Surgery, University of California San Diego, La Jolla, CA 92093, USA (T.K.)
| | - Tatiana Kisseleva
- Department of Surgery, University of California San Diego, La Jolla, CA 92093, USA (T.K.)
| | - David A. Brenner
- Department of Surgery, University of California San Diego, La Jolla, CA 92093, USA (T.K.)
- Sanford Burnham Prebys, La Jolla, CA 92037, USA
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Watanabe N, Saito-Nakano Y, Kurisawa N, Otomo K, Suenaga K, Nakano K, Nozaki T. Fumagillin inhibits growth of the enteric protozoan parasite Entamoeba histolytica by covalently binding to and selectively inhibiting methionine aminopeptidase 2. Antimicrob Agents Chemother 2023; 67:e0056023. [PMID: 37874291 PMCID: PMC10648944 DOI: 10.1128/aac.00560-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 08/27/2023] [Indexed: 10/25/2023] Open
Abstract
Amebiasis is an important cause of morbidity and mortality worldwide, and caused by infection with the protozoan parasite Entamoeba histolytica. Metronidazole is currently the first-line drug despite adverse effects and concerns on the emergence of drug resistance. Fumagillin, a fungal metabolite from Aspergillus fumigatus, and its structurally related natural and synthetic compounds have been previously explored as potential anti-angiogenesis inhibitors for cancers, anti-microbial, and anti-obese compounds. Although fumagillin was used for human amebiasis in clinical trials in 1950s, the mode of action of fumagillin remains elusive until now. In this report, we showed that fumagillin covalently binds to methionine aminopeptidase 2 (MetAP2) and non-covalently but abundantly binds to patatin family phospholipase A (PLA). Susceptibility against fumagillin of the amebic strains in which expression of E. histolytica MetAP2 (EhMetAP2) gene was silenced increased compared to control strain. Conversely, overexpression of EhMetAP2 mutants that harbors amino acid substitutions responsible for resistance to ovalicin, a fumagillin analog, in human MetAP2, also resulted in decrease in fumagillin susceptibility. In contrast, neither gene silencing nor overexpression of E. histolytica PLA (EhPLA) affected fumagillin susceptibility. These data suggest that EhPLA is not essential and not the target of fumagillin for its amebicidal activity. Taken together, our data have demonstrated that EhMetAP2 is the primary target for amebicidal activity of fumagillin, and EhMetAP2 represents a rational explorable target for the development of alternative therapeutic agents against amebiasis.
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Affiliation(s)
- Natsuki Watanabe
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Yumiko Saito-Nakano
- Department of Parasitology and Antimicrobial Resistance Research Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Naoaki Kurisawa
- Department of Chemistry, Faculty of Science and Technology, Keio University, Kanagawa, Japan
| | - Keisuke Otomo
- Department of Chemistry, Faculty of Science and Technology, Keio University, Kanagawa, Japan
| | - Kiyotake Suenaga
- Department of Chemistry, Faculty of Science and Technology, Keio University, Kanagawa, Japan
| | - Kentaro Nakano
- Degree Programs in Biology, Graduate School of Science and Technology, University of Tsukuba, Ibaraki, Japan
| | - Tomoyoshi Nozaki
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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7
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Takashima M, Taniguchi K, Nagaya M, Yamamura S, Takamura Y, Inatani M, Oki M. Gene profiles and mutations in the development of cataracts in the ICR rat model of hereditary cataracts. Sci Rep 2023; 13:18161. [PMID: 37875594 PMCID: PMC10598066 DOI: 10.1038/s41598-023-45088-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 10/16/2023] [Indexed: 10/26/2023] Open
Abstract
Cataracts are opacifications of the lens that cause loss of visual acuity and ultimately of eyesight. Age-related cataract develops in most elderly people, but the mechanisms of cataract onset are incompletely understood. The Ihara Cataract Rat (ICR) is an animal model of hereditary cataracts showing cortical opacity that commonly develops prematurely. We identified putative mechanisms of cataract onset in the ICR rat model by measuring gene expression changes before and after cortical cataract development and conducting point mutation analysis. Genes differentially expressed between 4-week-old animals without cortical cataracts and 8-10-week-old animals with cortical cataracts were selected from microarray analysis. Three connections were identified by STRING analysis: (i) Epithelial-Mesenchymal Transition (EMT), including Col1a2, and Pik3r1. (ii) Lens homeostasis, including Aqp5, and Cpm. (iii) Lipid metabolism, including Scd1, Srebf1, and Pnpla3. Subsequently, mutation points were selected by comparing ICR rats with 12 different rats that do not develop cataracts. The apolipoprotein Apoc3 was mutated in ICR rats. Analyses of gene expression changes and point and mutations suggested that abnormalities in EMT or lipid metabolism could contribute to cataract development in ICR rats.
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Affiliation(s)
- Masaru Takashima
- Department of Industrial Creation Engineering, Graduate School of Engineering, University of Fukui, Fukui, Japan
| | - Kei Taniguchi
- Department of Industrial Creation Engineering, Graduate School of Engineering, University of Fukui, Fukui, Japan
| | - Masaya Nagaya
- Department of Industrial Creation Engineering, Graduate School of Engineering, University of Fukui, Fukui, Japan
| | - Shunki Yamamura
- Department of Industrial Creation Engineering, Graduate School of Engineering, University of Fukui, Fukui, Japan
| | - Yoshihiro Takamura
- Department of Ophthalmology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Masaru Inatani
- Department of Ophthalmology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Masaya Oki
- Department of Industrial Creation Engineering, Graduate School of Engineering, University of Fukui, Fukui, Japan.
- Life Science Innovation Center, University of Fukui, Fukui, Japan.
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Johnson S, Bao H, McMahon C, Chen Y, Burr S, Anderson A, Madeyski-Bengtson K, Lindén D, Han X, Liu J. Substrate-Specific Function of PNPLA3 Facilitates Hepatic VLDL-Triglyceride Secretion During Stimulated Lipogenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.30.553213. [PMID: 37693552 PMCID: PMC10491159 DOI: 10.1101/2023.08.30.553213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
The I148M variant of PNPLA3 is strongly linked to hepatic steatosis. Evidence suggests a gain-of-function role for the I148M mutant as an ATGL inhibitor, leaving the physiological relevance of wild-type PNPLA3 undefined. Here we show that PNPLA3 selectively degrades triglycerides (TGs) enriched in polyunsaturated fatty acids (PUFAs) independently of ATGL in cultured cells and mice. Lipidomics and metabolite tracing analyses demonstrated that PNPLA3 mobilizes PUFAs from intracellular TGs for phospholipid desaturation, supporting hepatic secretion of TG-rich lipoproteins. Consequently, mice with liver-specific knockout or acute knockdown of PNPLA3 both exhibited aggravated liver steatosis and concomitant decreases in plasma VLDL-TG, phenotypes that manifest only under lipogenic conditions. I148M-knockin mice similarly displayed impaired hepatic TG secretion during lipogenic stimulation. Our results highlight a specific context whereby PNPLA3 facilitates the balance between hepatic TG storage and secretion and suggest the potential contributions of I148M variant loss-of-function to the development of hepatic steatosis in humans. Summary Statement We define the physiological role of wild type PNPLA3 in maintaining hepatic VLDL-TG secretion.
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Shi H, Prough RA, McClain CJ, Song M. Different Types of Dietary Fat and Fructose Interactions Result in Distinct Metabolic Phenotypes in Male Mice. J Nutr Biochem 2023; 111:109189. [PMID: 36272691 DOI: 10.1016/j.jnutbio.2022.109189] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 07/19/2022] [Accepted: 09/20/2022] [Indexed: 11/06/2022]
Abstract
Fat and fructose are the two major components over-represented in the Western diet. The aim of this study was to determine the combined effects of different types of dietary fat and fructose on the development of nonalcoholic fatty liver disease (NAFLD) in a murine model. Eight-week-old male C57BL/6J mice were fed with high-fat diet enriched with saturated fat (HSF), or omega-6 polyunsaturated fat (n6HUSF), or omega-3 polyunsaturated fat (n3HUSF) with 42% of calories derived from the fat. Fructose supplementation was given via 10% fructose (w/v) in the drinking water ad libitum for 20 weeks. While both HSF and n6HUSF fed mice developed obesity, HSF fed mice exhibited severe hepatic steatosis associated with hepatomegaly and liver injury. Fructose feeding promotes the development of liver fibrosis in HSF fed mice. n6HUSF fed mice were characterized with moderate hepatic steatosis, accompanied with hypertriglyceridemia and hyperlipidemia. Notably, fructose supplementation led to remarkable glucose intolerance in n6HUSF fed mice compared to controls. Hepatic lipidomic analysis revealed that the total saturated fatty acids and total monounsaturated fatty acids were significantly increased by fructose in the free fatty acid pool in HSF fed mice. Moreover, fructose supplementation increased hepatic and plasma cholesterol levels in the HSF fed mice. Our data suggest that excess energy from HSF intake results in fat storage in the liver, likely due to impaired triglyceride secretion; whereas excess energy from n6HUSF diet is stored in the periphery. Both effects are exacerbated by fructose supplementation. n3HUSF is beneficial, even consumed with fructose.
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Affiliation(s)
- Hongxue Shi
- Department of Pharmacology and Toxicology; Department of Medicine, Columbia University Irving Medical Center, New York, New York, USA
| | - Russell A Prough
- Hepatobiology and Toxicology Center; Department of Biochemistry and Molecular Genetics
| | - Craig J McClain
- Department of Pharmacology and Toxicology; Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition; Hepatobiology and Toxicology Center; University of Louisville Alcohol Research Center, University of Louisville School of Medicine, Louisville, Kentucky, USA; Robley Rex Veterans Affairs Medical Center, Louisville, Kentucky, USA
| | - Ming Song
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition; Hepatobiology and Toxicology Center.
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Luo Z, Liu Y, Li H, Zhou Y, Peng Y, Lin X, Fang Y, Wan J, Wei B. Associations of PNPLA3 rs738409 Polymorphism with Plasma Lipid Levels: A Systematic Review and Meta-Analysis. Horm Metab Res 2022; 54:686-695. [PMID: 36206762 DOI: 10.1055/a-1929-1677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Accumulating evidence has shown that the rs738409 polymorphism of patatin-like phospholipase domain-containing 3 (PNPLA3) is associated with non-alcoholic fatty liver disease (NAFLD). Since NAFLD has been reported to be associated with lipid metabolism, this study is conducted to explore whether the rs738409 polymorphism of PNPLA3 was associated with lipid levels. By searching PubMed and the Cochrane database from May 31, 2020, to June 30, 2021. Sixty-three studies (81 003 subjects) were included for the analysis. The consistent findings for the associations of rs738409 polymorphism with lipid levels were the significantly decreased triglycerides (TG) (SMD=-0.04, 95% CI=-0.07 to -0.01, p=0.02) and total cholesterol (TC) (SMD=-0.03, 95% CI=-0.05 to -0.01, p<0.01) levels. Subgroup analysis indicated that the associations of rs738409 polymorphism with TG and TC levels were stronger in Caucasians, obesity patients, and adult subjects than in Asians, T2DM patients, and children subjects. The rs738409 polymorphism of PNPLA3 was associated with lower TG and TC levels in Caucasians, obese and adult subjects, which may contribute to the reduced coronary artery disease (CAD) risk between PNPLA3 rs738409 polymorphism and CAD.
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Affiliation(s)
- Zhi Luo
- Cardiology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Yang Liu
- Endocrinology, China Resources and WISCO General Hospital, Wuhan, China
| | - Hang Li
- Geratology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Yawen Zhou
- Cardiology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Yuanyuan Peng
- Cardiology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Xuan Lin
- Endocrinology, China Resources and WISCO General Hospital, Wuhan, China
| | - Ying Fang
- Endocrinology, China Resources and WISCO General Hospital, Wuhan, China
| | - Jing Wan
- Cardiology, Zhongnan Hospital of Wuhan University, Wuhan, China
- Institute of Myocardial Injury and Repair, Wuhan University, Wuhan, China
| | - Baozhu Wei
- Cardiology, Zhongnan Hospital of Wuhan University, Wuhan, China
- Institute of Myocardial Injury and Repair, Wuhan University, Wuhan, China
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11
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Qiao A, Ma W, Jiang Y, Han C, Yan B, Zhou J, Qin G. Hepatic Sam68 Regulates Systemic Glucose Homeostasis and Insulin Sensitivity. Int J Mol Sci 2022; 23:ijms231911469. [PMID: 36232770 PMCID: PMC9569775 DOI: 10.3390/ijms231911469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 09/19/2022] [Accepted: 09/21/2022] [Indexed: 11/21/2022] Open
Abstract
Hepatic glucose production (HGP) is an important component of glucose homeostasis, and deregulated HGP, particularly through gluconeogenesis, contributes to hyperglycemia and pathology of type-2 diabetes (T2D). It has been shown that the gluconeogenic gene expression is governed primarily by the transcription factor cAMP-response element (CRE)-binding protein (CREB) and its coactivator, CREB-regulated transcriptional coactivator 2 (CRTC2). Recently, we have discovered that Sam68, an adaptor protein and Src kinase substrate, potently promotes hepatic gluconeogenesis by promoting CRTC2 stability; however, the detailed mechanisms remain unclear. Here we show that in response to glucagon, Sam68 increases CREB/CRTC2 transactivity by interacting with CRTC2 in the CREB/CRTC2 complex and occupying the CRE motif of promoters, leading to gluconeogenic gene expression and glucose production. In hepatocytes, glucagon promotes Sam68 nuclear import, whereas insulin elicits its nuclear export. Furthermore, ablation of Sam68 in hepatocytes protects mice from high-fat diet (HFD)-induced hyperglycemia and significantly increased hepatic and peripheral insulin sensitivities. Thus, hepatic Sam68 potentiates CREB/CRTC2-mediated glucose production, contributes to the pathogenesis of insulin resistance, and may serve as a therapeutic target for T2D.
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Affiliation(s)
- Aijun Qiao
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Zhongshan Institute for Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Zhongshan 528400, China
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China
- Correspondence: (A.Q.); (G.Q.); Tel.: +205-934-6690 (G.Q.); Fax: +205-934-9101 (G.Q.)
| | - Wenxia Ma
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Ying Jiang
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Chaoshan Han
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Baolong Yan
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Junlan Zhou
- Feinberg Cardiovascular Research Institute, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Gangjian Qin
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Feinberg Cardiovascular Research Institute, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Correspondence: (A.Q.); (G.Q.); Tel.: +205-934-6690 (G.Q.); Fax: +205-934-9101 (G.Q.)
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Aljabban J, Rohr M, Syed S, Khorfan K, Borkowski V, Aljabban H, Segal M, Mukhtar M, Mohammed M, Panahiazar M, Hadley D, Spengler R, Spengler E. Transcriptome changes in stages of non-alcoholic fatty liver disease. World J Hepatol 2022; 14:1382-1397. [PMID: 36158924 PMCID: PMC9376779 DOI: 10.4254/wjh.v14.i7.1382] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 04/29/2022] [Accepted: 06/17/2022] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the United States and globally. The currently understood model of pathogenesis consists of a ‘multiple hit’ hypothesis in which environmental and genetic factors contribute to hepatic inflammation and injury.
AIM To examine the genetic expression of NAFLD and non-alcoholic steatohepatitis (NASH) tissue samples to identify common pathways that contribute to NAFLD and NASH pathogenesis.
METHODS We employed the Search Tag Analyze Resource for Gene Expression Omnibus platform to search the The National Center for Biotechnology Information Gene Expression Omnibus to elucidate NAFLD and NASH pathology. For NAFLD, we conducted meta-analysis of data from 58 NAFLD liver biopsies and 60 healthy liver biopsies; for NASH, we analyzed 187 NASH liver biopsies and 154 healthy liver biopsies.
RESULTS Our results from the NAFLD analysis reinforce the role of altered metabolism, inflammation, and cell survival in pathogenesis and support recently described contributors to disease activity, such as altered androgen and long non-coding RNA activity. The top upstream regulator was found to be sterol regulatory element binding transcription factor 1 (SREBF1), a transcription factor involved in lipid homeostasis. Downstream of SREBF1, we observed upregulation in CXCL10, HMGCR, HMGCS1, fatty acid binding protein 5, paternally expressed imprinted gene 10, and downregulation of sex hormone-binding globulin and insulin-like growth factor 1. These molecular changes reflect low-grade inflammation secondary to accumulation of fatty acids in the liver. Our results from the NASH analysis emphasized the role of cholesterol in pathogenesis. Top canonical pathways, disease networks, and disease functions were related to cholesterol synthesis, lipid metabolism, adipogenesis, and metabolic disease. Top upstream regulators included pro-inflammatory cytokines tumor necrosis factor and IL1B, PDGF BB, and beta-estradiol. Inhibition of beta-estradiol was shown to be related to derangement of several cellular downstream processes including metabolism, extracellular matrix deposition, and tumor suppression. Lastly, we found riciribine (an AKT inhibitor) and ZSTK-474 (a PI3K inhibitor) as potential drugs that targeted the differential gene expression in our dataset.
CONCLUSION In this study we describe several molecular processes that may correlate with NAFLD disease and progression. We also identified ricirbine and ZSTK-474 as potential therapy.
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Affiliation(s)
- Jihad Aljabban
- Department of Medicine, University of Wisconsin Hospital and Clinics, Madison, WI 53792, United States
| | - Michael Rohr
- Department of Medicine, University of Central Florida College of Medicine, Orlando, FL 32827, United States
| | - Saad Syed
- Department of Medicine, Northwestern Memorial Hospital, Chicago, IL 60611, United States
| | - Kamal Khorfan
- Department of Gastroenterology and Hepatology, University of California San Francisco-Fresno , Fresno, CA 93701, United States
| | - Vincent Borkowski
- Department of Medicine, University of Wisconsin Hospital and Clinics, Madison, WI 53792, United States
| | - Hisham Aljabban
- Department of Medicine, Barry University, Miami, FL 33161, United States
| | - Michael Segal
- Department of Medicine, University of Wisconsin Hospital and Clinics, Madison, WI 53792, United States
| | - Mohamed Mukhtar
- Department of Medicine, Michigan State University College of Human Medicine, East Lansing, MI 49503, United States
| | - Mohammed Mohammed
- Department of Medicine, Windsor University School of Medicine, Saint Kitts 1621, Cayon, Saint Kitts and Nevis
| | - Maryam Panahiazar
- Department of Surgery, University of California San Francisco, San Francisco, CA 94305, United States
| | - Dexter Hadley
- Department of Artificial Intelligence, Pathology, University of Central Florida College of Medicine , Orlando, FL 32827, United States
| | - Ryan Spengler
- Department of Medicine, University of Wisconsin Hospital and Clinics, Madison, WI 53792, United States
| | - Erin Spengler
- Department of Gastroenterology and Hepatology, University of Wisconsin Hospital and Clinics, Madison, WI 53792, United States
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Velázquez AM, Bentanachs R, Sala-Vila A, Lázaro I, Rodríguez-Morató J, Sánchez RM, Laguna JC, Roglans N, Alegret M. KHK, PNPLA3 and PPAR as Novel Targets for the Anti-Steatotic Action of Bempedoic Acid. Biomedicines 2022; 10:biomedicines10071517. [PMID: 35884822 PMCID: PMC9312949 DOI: 10.3390/biomedicines10071517] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 06/21/2022] [Accepted: 06/22/2022] [Indexed: 12/12/2022] Open
Abstract
Bempedoic acid (BemA) is an ATP-citrate lyase (ACLY) inhibitor used to treat hypercholesterolemia. We studied the anti-steatotic effect of BemA, and the mechanisms involved, in a model of fatty liver in female rats obtained through the administration of a high-fat diet supplemented with liquid fructose (HFHFr) for three months. In the third month, a group of rats was treated with BemA (30 mg/kg/day) by gavage. Plasma analytes, liver histology, adiposity, and the expression of key genes controlling fatty acid metabolism were determined, and PPAR agonism was explored by using luciferase reporter assays. Our results showed that, compared to HFHFr, BemA-treated rats exhibited lower body weight, higher liver/body weight, and reduced hepatic steatosis. In addition to ACLY inhibition, we found three novel mechanisms that could account for the anti-steatotic effect: (1) reduction of liver ketohexokinase, leading to lower fructose intake and reduced de novo lipogenesis; (2) increased expression of patatin-like phospholipase domain-containing protein 3, a protein related to the export of liver triglycerides to blood; and (3) PPARα agonist activity, leading to increased hepatic fatty acid β-oxidation. In conclusion, BemA may represent a novel approach to treat hepatic steatosis, and therefore to avoid progression to advanced stages of non-alcoholic fatty liver disease.
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Affiliation(s)
- Ana Magdalena Velázquez
- Department of Pharmacology, Toxicology and Therapeutic Chemistry, School of Pharmacy and Food Science, University of Barcelona, Av. Joan XXIII 27–31, 08028 Barcelona, Spain; (A.M.V.); (R.B.); (R.M.S.); (J.C.L.)
| | - Roger Bentanachs
- Department of Pharmacology, Toxicology and Therapeutic Chemistry, School of Pharmacy and Food Science, University of Barcelona, Av. Joan XXIII 27–31, 08028 Barcelona, Spain; (A.M.V.); (R.B.); (R.M.S.); (J.C.L.)
| | - Aleix Sala-Vila
- Cardiovascular Risk and Nutrition, Hospital del Mar Medical Research Institute (IMIM), 08003 Barcelona, Spain; (A.S.-V.); (I.L.)
| | - Iolanda Lázaro
- Cardiovascular Risk and Nutrition, Hospital del Mar Medical Research Institute (IMIM), 08003 Barcelona, Spain; (A.S.-V.); (I.L.)
| | - Jose Rodríguez-Morató
- Integrative Pharmacology and Systems Neuroscience Research Group, Hospital del Mar Medical Research Institute (IMIM), Dr. Aiguader 88, 08003 Barcelona, Spain;
- Department of Medicine and Life Sciences, Universitat Pompeu Fabra, Dr. Aiguader 88, 08003 Barcelona, Spain
- Spanish Biomedical Research Centre in Physiopathology of Obesity and Nutrition (CIBEROBN), Instituto de Salud Carlos III (ISCIII), 28029 Madrid, Spain
| | - Rosa María Sánchez
- Department of Pharmacology, Toxicology and Therapeutic Chemistry, School of Pharmacy and Food Science, University of Barcelona, Av. Joan XXIII 27–31, 08028 Barcelona, Spain; (A.M.V.); (R.B.); (R.M.S.); (J.C.L.)
- Spanish Biomedical Research Centre in Physiopathology of Obesity and Nutrition (CIBEROBN), Instituto de Salud Carlos III (ISCIII), 28029 Madrid, Spain
- Institute of Biomedicine, University of Barcelona, 08028 Barcelona, Spain
| | - Juan Carlos Laguna
- Department of Pharmacology, Toxicology and Therapeutic Chemistry, School of Pharmacy and Food Science, University of Barcelona, Av. Joan XXIII 27–31, 08028 Barcelona, Spain; (A.M.V.); (R.B.); (R.M.S.); (J.C.L.)
- Spanish Biomedical Research Centre in Physiopathology of Obesity and Nutrition (CIBEROBN), Instituto de Salud Carlos III (ISCIII), 28029 Madrid, Spain
- Institute of Biomedicine, University of Barcelona, 08028 Barcelona, Spain
| | - Núria Roglans
- Department of Pharmacology, Toxicology and Therapeutic Chemistry, School of Pharmacy and Food Science, University of Barcelona, Av. Joan XXIII 27–31, 08028 Barcelona, Spain; (A.M.V.); (R.B.); (R.M.S.); (J.C.L.)
- Spanish Biomedical Research Centre in Physiopathology of Obesity and Nutrition (CIBEROBN), Instituto de Salud Carlos III (ISCIII), 28029 Madrid, Spain
- Institute of Biomedicine, University of Barcelona, 08028 Barcelona, Spain
- Correspondence: (N.R.); (M.A.)
| | - Marta Alegret
- Department of Pharmacology, Toxicology and Therapeutic Chemistry, School of Pharmacy and Food Science, University of Barcelona, Av. Joan XXIII 27–31, 08028 Barcelona, Spain; (A.M.V.); (R.B.); (R.M.S.); (J.C.L.)
- Spanish Biomedical Research Centre in Physiopathology of Obesity and Nutrition (CIBEROBN), Instituto de Salud Carlos III (ISCIII), 28029 Madrid, Spain
- Institute of Biomedicine, University of Barcelona, 08028 Barcelona, Spain
- Correspondence: (N.R.); (M.A.)
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Xu X, Deng X, Chen Y, Xu W, Xu F, Liang H. SIRT1 mediates nutritional regulation of SREBP-1c-driven hepatic PNPLA3 transcription via modulation of H3k9 acetylation. Genes Environ 2022; 44:18. [PMID: 35624499 PMCID: PMC9137095 DOI: 10.1186/s41021-022-00246-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2021] [Accepted: 05/02/2022] [Indexed: 11/25/2022] Open
Abstract
Background Patatin-like phospholipase domain containing 3 (PNPLA3) is the main nonalcoholic fatty liver disease (NAFLD) susceptibility. Its expression is regulated tightly by nutritional and energy status, but the mechanism of epigenetic regulation of PNPLA3 gene by nutritional dietary factors has not been reported. Here, we investigated the effect and mechanism of Sirtuin 1 (SIRT1) regulated H3K9 deacetylation on PNPLA3 transcriptional expression in vivo and in vitro. Methods Mouse models of fasting/re-feeding transition and nonalcoholic fatty liver induced by high Sucrose diet were constructed; and HepG2 cells were treated with serum- and glucose-free medium or exposed to high glucose and high insulin, to generate fasting and high-glucose-induced lipid deposition cell states. Enrichment levels of histone H3K9 acetylation and sterol responsive element binding protein-1c (SREBP-1c) at the PNPLA3 promoter were observed by ChIP-qPCR. PNPLA3 gene expression was detected by real-time PCR; SIRT1 protein expression was detected by western blot. And lipid deposition was detected by Oil Red O. Results H3K9ac levels at SRE regions of PNPLA3 promoter were found to be decreased in mice during fasting and increase during refeeding, and increased in mice with NAFLD induced by high-sucrose diet. The change pattern of PNPLA3 promoter H3K9Ac physiologically (fasting/refeeding) and pathologically was consistent with that of PNPLA3 gene expression, but opposite to that of SIRT1 protein expression. In HepG2 cells, overexpression of SIRT1 inhibited high-glucose induced hyper-acetylation of H3K9 at PNPLA3 promoter, and silent expression of SIRT1 suppressed fasting-induced hypo-acetylation of H3K9. Overexpression of SIRT1 prevented basal and SREBP-1c-driven PNPLA3 gene expression and also prevented the endogenous binding of SREBP-1c to PNPLA3. Conclusions We first preliminarily revealed SIRT1 may regulate PNPLA3 gene expression by affecting SREBP-1-driven transcription via acetylation modification of H3K9. Supplementary Information The online version contains supplementary material available at 10.1186/s41021-022-00246-1.
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Affiliation(s)
- Xiao Xu
- Department of Endocrinology and Metabolism, Guangdong Provincial Key Laboratory of Diabetology, The Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510630, People's Republic of China.,Department of Emergency, Zhujiang Hospital, Southern Medical University, 510280, Guangzhou, People's Republic of China
| | - Xiaojie Deng
- Department of Endocrinology and Metabolism, Guangdong Provincial Key Laboratory of Diabetology, The Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510630, People's Republic of China
| | - Yunzhi Chen
- Department of Endocrinology and Metabolism, Guangdong Provincial Key Laboratory of Diabetology, The Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510630, People's Republic of China
| | - Wen Xu
- Department of Endocrinology and Metabolism, Guangdong Provincial Key Laboratory of Diabetology, The Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510630, People's Republic of China
| | - Fen Xu
- Department of Endocrinology and Metabolism, Guangdong Provincial Key Laboratory of Diabetology, The Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510630, People's Republic of China.
| | - Hua Liang
- Department of Endocrinology and Metabolism, Guangdong Provincial Key Laboratory of Diabetology, The Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510630, People's Republic of China.
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Sunami Y, Rebelo A, Kleeff J. Lipid Droplet-Associated Factors, PNPLA3, TM6SF2, and HSD17B Proteins in Hepatopancreatobiliary Cancer. Cancers (Basel) 2021; 13:cancers13174391. [PMID: 34503201 PMCID: PMC8431307 DOI: 10.3390/cancers13174391] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 08/17/2021] [Accepted: 08/25/2021] [Indexed: 12/16/2022] Open
Abstract
Simple Summary Aberrant lipid synthesis and reprogrammed lipid metabolism are both associated with the development and progression of pancreatic and liver cancer. Most cells store fatty acids in the form of triacylglycerols in lipid droplets. Lipid droplets are intracellular organelles that not only store neutral lipids, but also play roles as molecular messengers and signaling factors. Some cancer cells accumulate massive amount of lipid droplets. Lipid droplets and lipid droplet-associated factors are further implicated to mediate proliferation, invasion, metastasis, as well as chemotherapy resistance in several types of cancer. This review dissected recent findings on the role of several lipid droplet-associated factors, patatin-like phospholipase domain-containing 3 (PNPLA3), Transmembrane 6 superfamily member 2 (TM6SF2), and 17β-hydroxysteroid dehydrogenase (HSD17B) 11 and 13 as well as their genetic variations in hepatopancreatobiliary diseases, especially cancer. Abstract Pancreatic and liver cancer are leading causes of cancer deaths, and by 2030, they are projected to become the second and the third deadliest cancer respectively. Cancer metabolism, especially lipid metabolism, plays an important role in progression and metastasis of many types of cancer, including pancreatic and liver cancer. Lipid droplets are intracellular organelles that store neutral lipids, but also act as molecular messengers, and signaling factors. It is becoming increasingly evident that alterations in the regulation of lipid droplets and their associated factors influence the risk of developing not only metabolic disease but also fibrosis and cancer. In the current review article, we summarized recent findings concerning the roles of lipid droplet-associated factors, patatin-like phospholipase domain-containing 3, Transmembrane 6 superfamily member 2, and 17β-hydroxysteroid dehydrogenase 11 and 13 as well as genetic variants in pancreatic and hepatic diseases. A better understanding of cancer type- and cell type-specific roles of lipid droplet-associated factors is important for establishing new therapeutic options in the future.
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Qiao A, Zhou J, Xu S, Ma W, Boriboun C, Kim T, Yan B, Deng J, Yang L, Zhang E, Song Y, Ma YC, Richard S, Zhang C, Qiu H, Habegger KM, Zhang J, Qin G. Sam68 promotes hepatic gluconeogenesis via CRTC2. Nat Commun 2021; 12:3340. [PMID: 34099657 PMCID: PMC8185084 DOI: 10.1038/s41467-021-23624-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 05/05/2021] [Indexed: 02/07/2023] Open
Abstract
Hepatic gluconeogenesis is essential for glucose homeostasis and also a therapeutic target for type 2 diabetes, but its mechanism is incompletely understood. Here, we report that Sam68, an RNA-binding adaptor protein and Src kinase substrate, is a novel regulator of hepatic gluconeogenesis. Both global and hepatic deletions of Sam68 significantly reduce blood glucose levels and the glucagon-induced expression of gluconeogenic genes. Protein, but not mRNA, levels of CRTC2, a crucial transcriptional regulator of gluconeogenesis, are >50% lower in Sam68-deficient hepatocytes than in wild-type hepatocytes. Sam68 interacts with CRTC2 and reduces CRTC2 ubiquitination. However, truncated mutants of Sam68 that lack the C- (Sam68ΔC) or N-terminal (Sam68ΔN) domains fails to bind CRTC2 or to stabilize CRTC2 protein, respectively, and transgenic Sam68ΔN mice recapitulate the blood-glucose and gluconeogenesis profile of Sam68-deficient mice. Hepatic Sam68 expression is also upregulated in patients with diabetes and in two diabetic mouse models, while hepatocyte-specific Sam68 deficiencies alleviate diabetic hyperglycemia and improves insulin sensitivity in mice. Thus, our results identify a role for Sam68 in hepatic gluconeogenesis, and Sam68 may represent a therapeutic target for diabetes. Hepatic gluconeogenesis is important for glucose homeostasis and a therapeutic target for type 2 diabetes. Here, the authors show that the RNA-binding adaptor protein Sam68 promotes the expression level of gluconeogenic genes and increases blood glucose levels by stabilizing the transcriptional coactivator CRTC2, while hepatic Sam68 deletion alleviates hyperglycemia in mice.
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Affiliation(s)
- Aijun Qiao
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Junlan Zhou
- Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Shiyue Xu
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Wenxia Ma
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Chan Boriboun
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Teayoun Kim
- Department of Medicine - Endocrinology, Diabetes & Metabolism, University of Alabama at Birmingham, School of Medicine, Birmingham, AL, USA
| | - Baolong Yan
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Jianxin Deng
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Liu Yang
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Eric Zhang
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Yuhua Song
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Yongchao C Ma
- Departments of Pediatrics, Neurology and Physiology, Northwestern University Feinberg School of Medicine, Anne & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA
| | - Stephane Richard
- Lady Davis Institute for Medical Research, McGill University, Montreal, QC, Canada
| | - Chunxiang Zhang
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Hongyu Qiu
- Center for Molecular and Translational Medicine, Institute of Biomedical Science Georgia State University, Atlanta, GA, USA
| | - Kirk M Habegger
- Department of Medicine - Endocrinology, Diabetes & Metabolism, University of Alabama at Birmingham, School of Medicine, Birmingham, AL, USA
| | - Jianyi Zhang
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Gangjian Qin
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA. .,Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
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Mehmood A, Zhao L, Wang Y, Pan F, Hao S, Zhang H, Iftikhar A, Usman M. Dietary anthocyanins as potential natural modulators for the prevention and treatment of non-alcoholic fatty liver disease: A comprehensive review. Food Res Int 2021; 142:110180. [PMID: 33773656 DOI: 10.1016/j.foodres.2021.110180] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 01/18/2021] [Accepted: 01/24/2021] [Indexed: 02/07/2023]
Abstract
Nonalcoholic fatty liver disease (NAFLD) refers to a metabolic syndrome linked with type 2 diabetes mellitus, obesity, and cardiovascular diseases. It is characterized by the accumulation of triglycerides in the hepatocytes in the absence of alcohol consumption. The prevalence of NAFLD has abruptly increased worldwide, with no effective treatment yet available. Anthocyanins (ACNs) belong to the flavonoid subclass of polyphenols, are commonly present in various edible plants, and possess a broad array of health-promoting properties. ACNs have been shown to have strong potential to combat NAFLD. We critically assessed the literature regarding the pharmacological mechanisms and biopharmaceutical features of the action of ACNs on NAFLD in humans and animal models. We found that ACNs ameliorate NAFLD by improving lipid and glucose metabolism, increasing antioxidant and anti-inflammatory activities, and regulating gut microbiota dysbiosis. In conclusion, ACNs have potential to attenuate NAFLD. However, further mechanistic studies are required to confirm these beneficial impacts of ACNs on NAFLD.
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Affiliation(s)
- Arshad Mehmood
- Beijing Advance Innovation Center for Food Nutrition and Human Health, Beijing Engineering and Technology Research Center of Food Additives, School of Food and Health, Beijing Technology and Business University, Beijing 100048, China
| | - Lei Zhao
- Beijing Advance Innovation Center for Food Nutrition and Human Health, Beijing Engineering and Technology Research Center of Food Additives, School of Food and Health, Beijing Technology and Business University, Beijing 100048, China.
| | - Yong Wang
- Academy of National Food and Strategic Reserves Administration, Beijing 100037, China
| | - Fei Pan
- Beijing Advance Innovation Center for Food Nutrition and Human Health, Beijing Engineering and Technology Research Center of Food Additives, School of Food and Health, Beijing Technology and Business University, Beijing 100048, China
| | - Shuai Hao
- Beijing Advance Innovation Center for Food Nutrition and Human Health, Beijing Engineering and Technology Research Center of Food Additives, School of Food and Health, Beijing Technology and Business University, Beijing 100048, China
| | - Huimin Zhang
- Beijing Advance Innovation Center for Food Nutrition and Human Health, Beijing Engineering and Technology Research Center of Food Additives, School of Food and Health, Beijing Technology and Business University, Beijing 100048, China
| | - Asra Iftikhar
- Department of Pharmacy, Faculty of Pharmaceutical Sciences, The University of Faisalabad, Faisalabad 38000, Pakistan
| | - Muhammad Usman
- Beijing Advance Innovation Center for Food Nutrition and Human Health, Beijing Engineering and Technology Research Center of Food Additives, School of Food and Health, Beijing Technology and Business University, Beijing 100048, China
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18
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Adipocyte lipolysis: from molecular mechanisms of regulation to disease and therapeutics. Biochem J 2020; 477:985-1008. [PMID: 32168372 DOI: 10.1042/bcj20190468] [Citation(s) in RCA: 114] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 02/19/2020] [Accepted: 02/26/2020] [Indexed: 12/20/2022]
Abstract
Fatty acids (FAs) are stored safely in the form of triacylglycerol (TAG) in lipid droplet (LD) organelles by professional storage cells called adipocytes. These lipids are mobilized during adipocyte lipolysis, the fundamental process of hydrolyzing TAG to FAs for internal or systemic energy use. Our understanding of adipocyte lipolysis has greatly increased over the past 50 years from a basic enzymatic process to a dynamic regulatory one, involving the assembly and disassembly of protein complexes on the surface of LDs. These dynamic interactions are regulated by hormonal signals such as catecholamines and insulin which have opposing effects on lipolysis. Upon stimulation, patatin-like phospholipase domain containing 2 (PNPLA2)/adipocyte triglyceride lipase (ATGL), the rate limiting enzyme for TAG hydrolysis, is activated by the interaction with its co-activator, alpha/beta hydrolase domain-containing protein 5 (ABHD5), which is normally bound to perilipin 1 (PLIN1). Recently identified negative regulators of lipolysis include G0/G1 switch gene 2 (G0S2) and PNPLA3 which interact with PNPLA2 and ABHD5, respectively. This review focuses on the dynamic protein-protein interactions involved in lipolysis and discusses some of the emerging concepts in the control of lipolysis that include allosteric regulation and protein turnover. Furthermore, recent research demonstrates that many of the proteins involved in adipocyte lipolysis are multifunctional enzymes and that lipolysis can mediate homeostatic metabolic signals at both the cellular and whole-body level to promote inter-organ communication. Finally, adipocyte lipolysis is involved in various diseases such as cancer, type 2 diabetes and fatty liver disease, and targeting adipocyte lipolysis is of therapeutic interest.
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Zaharia OP, Strassburger K, Knebel B, Kupriyanova Y, Karusheva Y, Wolkersdorfer M, Bódis K, Markgraf DF, Burkart V, Hwang JH, Kotzka J, Al-Hasani H, Szendroedi J, Roden M. Role of Patatin-Like Phospholipase Domain-Containing 3 Gene for Hepatic Lipid Content and Insulin Resistance in Diabetes. Diabetes Care 2020; 43:2161-2168. [PMID: 32910776 DOI: 10.2337/dc20-0329] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 05/14/2020] [Indexed: 02/03/2023]
Abstract
OBJECTIVE The rs738409(G) single nucleotide polymorphism (SNP) in the patatin-like phospholipase domain-containing 3 (PNPLA3) gene associates with increased risk and progression of nonalcoholic fatty liver disease (NAFLD). As the recently described severe insulin-resistant diabetes (SIRD) cluster specifically relates to NAFLD, this study examined whether this SNP differently associates with hepatic lipid content (hepatocellular lipids [HCL]) and insulin sensitivity in recent-onset diabetes. RESEARCH DESIGN AND METHODS A total of 917 participants in the German Diabetes Study (GDS) underwent genotyping, hyperinsulinemic-euglycemic clamps with stable isotopic tracer dilution, and MRS. RESULTS The G allele associated positively with HCL (β = 0.36, P < 0.01), independent of age, sex, and BMI across the whole cohort, but not in the individual clusters. Those with SIRD exhibited lowest whole-body insulin sensitivity compared with those with severe insulin-deficient (SIDD), moderate obesity-related (MOD), moderate age-related (MARD), and severe autoimmune diabetes (SAID) clusters (all P < 0.001). Interestingly, the SIRD group presented with higher prevalence of the rs738409(G) SNP compared with other clusters and the glucose-tolerant control group (P < 0.05). HCL was higher in the SIRD group (median 13.6% [1st quartile 5.8; 3rd quartile 19.1] compared with the MOD (6.4 % [2.1; 12.4], P < 0.05), MARD (3.0% [1.0; 7.9], P < 0.001), SAID (0.4% [0.0; 1.5], P < 0.001), and glucose-tolerant (0.9% [0.4; 4.9), P < 0.001) group. Although the PNPLA3 polymorphism did not directly associate with whole-body insulin sensitivity in SIRD, the G-allele carriers had higher circulating free fatty acid concentrations and greater adipose tissue insulin resistance compared with noncarriers (both P < 0.001). CONCLUSIONS Members of the SIRD cluster are more frequently carriers of the rs738409(G) variant. The SNP-associated adipose tissue insulin resistance and excessive lipolysis may contribute to their NAFLD.
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Affiliation(s)
- Oana P Zaharia
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Institute for Diabetes Research at Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,German Center for Diabetes Research (DZD e.V.), München-Neuherberg, Germany
| | - Klaus Strassburger
- German Center for Diabetes Research (DZD e.V.), München-Neuherberg, Germany.,Institute for Biometrics and Epidemiology, German Diabetes Center, Leibniz Institute for Diabetes Research at Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Birgit Knebel
- German Center for Diabetes Research (DZD e.V.), München-Neuherberg, Germany.,Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center, Leibniz Institute for Diabetes Research at Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Yuliya Kupriyanova
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Institute for Diabetes Research at Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,German Center for Diabetes Research (DZD e.V.), München-Neuherberg, Germany
| | - Yanislava Karusheva
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Institute for Diabetes Research at Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,German Center for Diabetes Research (DZD e.V.), München-Neuherberg, Germany
| | | | - Kálmán Bódis
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Institute for Diabetes Research at Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,German Center for Diabetes Research (DZD e.V.), München-Neuherberg, Germany.,Division of Endocrinology and Diabetology, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Daniel F Markgraf
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Institute for Diabetes Research at Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,German Center for Diabetes Research (DZD e.V.), München-Neuherberg, Germany
| | - Volker Burkart
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Institute for Diabetes Research at Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,German Center for Diabetes Research (DZD e.V.), München-Neuherberg, Germany
| | - Jong-Hee Hwang
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Institute for Diabetes Research at Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,German Center for Diabetes Research (DZD e.V.), München-Neuherberg, Germany
| | - Jörg Kotzka
- German Center for Diabetes Research (DZD e.V.), München-Neuherberg, Germany.,Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center, Leibniz Institute for Diabetes Research at Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Hadi Al-Hasani
- German Center for Diabetes Research (DZD e.V.), München-Neuherberg, Germany.,Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center, Leibniz Institute for Diabetes Research at Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Julia Szendroedi
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Institute for Diabetes Research at Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,German Center for Diabetes Research (DZD e.V.), München-Neuherberg, Germany.,Division of Endocrinology and Diabetology, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
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20
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Bruschi FV, Tardelli M, Herac M, Claudel T, Trauner M. Metabolic regulation of hepatic PNPLA3 expression and severity of liver fibrosis in patients with NASH. Liver Int 2020; 40:1098-1110. [PMID: 32043752 PMCID: PMC7318357 DOI: 10.1111/liv.14402] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 01/31/2020] [Accepted: 02/03/2020] [Indexed: 02/06/2023]
Abstract
BACKGROUND AND AIMS The genetic PNPLA3 polymorphism I148M has been extensively associated with higher risk for development and progression of NAFLD towards NASH. METHODS PNPLA3 and α-SMA expression were quantified in liver biopsies collected from NASH patients (n = 26) with different fibrosis stages and PNPLA3 genotypes. To study the potential mechanisms driving PNPLA3 expression during NASH progression towards fibrosis, hepatocytes and hepatic stellate cells (HSCs) were cultivated in low and high glucose medium. Moreover, hepatocytes were treated with increasing concentrations of palmitic acid alone or in combination with glucose. Conditioned media were collected from challenged hepatocytes to stimulate HSCs. RESULTS Tissue expression of PNPLA3 was significantly enhanced in biopsies of patients carrying the I148M polymorphism compared to wild type (WT). In NASH biopsies, PNPLA3 significantly correlated with fibrosis stage and α-SMA levels independently of PNPLA3 genotype. In line, PNPLA3 expression was higher in α-SMA positive cells. Low glucose increased PNPLA3 in HSCs, whereas high glucose induced PNPLA3 and de-novo lipogenesis-related genes expression in hepatocytes. Palmitic acid induced fat accumulation and cell stress markers in hepatocytes, which could be counteracted by oleic acid. Conditioned media collected from lipotoxic challenged hepatocytes markedly induced PNPLA3 mRNA and protein levels, fibrogenic and autophagic markers and promoted migration in HSCs. Notably, conditioned media collected from hepatocytes cultivated with both glucose and palmitic acid exacerbated HSCs migration, PNPLA3 and fibrogenic gene expression, promoting release of cytokines from HSCs. CONCLUSIONS Collectively, our observations uncover the diverse metabolic regulation of PNPLA3 among different hepatic cell populations and support its relation to fibrosis progression.
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Affiliation(s)
- Francesca V. Bruschi
- Hans Popper Laboratory of Molecular HepatologyDivision of Gastroenterology and HepatologyInternal Medicine IIIMedical University of ViennaViennaAustria
| | - Matteo Tardelli
- Hans Popper Laboratory of Molecular HepatologyDivision of Gastroenterology and HepatologyInternal Medicine IIIMedical University of ViennaViennaAustria,Division of Gastroenterology and HepatologyJoan and Sanford I. Weill Cornell Department of MedicineWeill Cornell Medical CollegeNew YorkNYUSA
| | - Merima Herac
- Clinical Institute of PathologyMedical University of ViennaViennaAustria
| | - Thierry Claudel
- Hans Popper Laboratory of Molecular HepatologyDivision of Gastroenterology and HepatologyInternal Medicine IIIMedical University of ViennaViennaAustria
| | - Michael Trauner
- Hans Popper Laboratory of Molecular HepatologyDivision of Gastroenterology and HepatologyInternal Medicine IIIMedical University of ViennaViennaAustria
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21
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Yuan S, Liu H, Yuan D, Xu J, Chen Y, Xu X, Xu F, Liang H. PNPLA3 I148M mediates the regulatory effect of NF-kB on inflammation in PA-treated HepG2 cells. J Cell Mol Med 2019; 24:1541-1552. [PMID: 31793207 PMCID: PMC6991629 DOI: 10.1111/jcmm.14839] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 09/19/2019] [Accepted: 10/19/2019] [Indexed: 12/17/2022] Open
Abstract
Both PNPLA3 I148M and hepatic inflammation are associated with nonalcoholic fatty liver disease (NAFLD) progression. This study aimed to elucidate whether PNPLA3 I148M is involved in NF‐kB‐related inflammation regulation in NAFLD. HepG2 cells homozygous for the PNPLA3 I148M mutation were used. The human PNPLA3 promoter sequence was screened for NF‐kB binding sites using the MATCH and PATCH tools. NF‐kB‐mediated transcriptional regulation of the PNPLA3 gene was assessed by luciferase reporter assay, EMSA and ChIP‐qPCR. Wild‐type (I148I) and mutant (M148M) PNPLA3 were overexpressed using stable lentivirus‐mediated transfection. The pCMV vector and siRNA were transiently transfected into cells to direct NF‐kB overexpression and PNPLA3 silencing, respectively. A putative NF‐kB binding site in the human PNPLA3 promoter was shown to be necessary for basal and NF‐kB‐driven transcriptional activation of PNPLA3 and protein/DNA complex formation. Supershift analysis demonstrated a protein/DNA complex specifically containing the NF‐kB p65 and p50 subunits. ChIP‐qPCR confirmed the endogenous binding of NF‐kB to the human PNPLA3 promoter in response to NF‐kB overexpression and palmitic acid (PA) challenge. The silencing of PNPLA3 blocked the overexpression of NF‐kB or PA‐induced TNF‐α up‐regulation. Moreover, mutant PNPLA3 overexpression prevented NF‐kB inhibitor–induced down‐regulation of TNF‐α expression in PA‐treated HepG2 cells. Finally, the overexpression of mutant but not wild‐type PNPLA3 increased TNF‐α expression and activated the ER stress–mediated and NF‐kB‐independent inflammatory IRE‐1α/JNK/c‐Jun pathway. Human PNPLA3 was shown to be a target of NF‐kB, and PNPLA3 I148M mediated the regulatory effect of NF‐kB on inflammation in PA‐treated HepG2 cells, most likely via the IRE‐1α/JNK/c‐Jun ER stress pathway.
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Affiliation(s)
- Shuhua Yuan
- Department of Endocrinology and Metabolism, Guangdong Provincial Key Laboratory of Diabetology, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China.,Department of Endocrinology, Guangzhou Panyu Central Hospital, Guangzhou, China
| | - Hongxia Liu
- Department of Endocrinology and Metabolism, Guangdong Provincial Key Laboratory of Diabetology, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China
| | - Ding Yuan
- Department of Endocrinology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Jing Xu
- Department of Endocrinology and Metabolism, The Affiliated Hospital of Guizhou Medical University, Guiyang, China
| | - Yunzhi Chen
- Department of Endocrinology and Metabolism, Guangdong Provincial Key Laboratory of Diabetology, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China
| | - Xiao Xu
- Department of Endocrinology and Metabolism, Guangdong Provincial Key Laboratory of Diabetology, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China
| | - Fen Xu
- Department of Endocrinology and Metabolism, Guangdong Provincial Key Laboratory of Diabetology, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China
| | - Hua Liang
- Department of Endocrinology and Metabolism, Guangdong Provincial Key Laboratory of Diabetology, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China
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22
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Mendez-Garcia C, Trini A, Browne V, Kochansky CJ, Pontiggia L, D'mello AP. Decreased liver triglyceride content in adult rats exposed to protein restriction during gestation and lactation: roles of hepatic lipogenesis and lipid utilization in muscle and adipose tissue. Can J Physiol Pharmacol 2019; 97:952-962. [PMID: 31238009 DOI: 10.1139/cjpp-2018-0646] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Protein restriction throughout pregnancy and lactation reduces liver triglyceride (TG) content in adult male rat offspring. The study determined the contribution of hepatic lipogenesis to the reduction in liver TG content. Rats received either control or protein-restricted diets throughout pregnancy and lactation. Offspring were sacrificed on day 65. Hepatic fatty acid uptake and de novo fatty acid and TG biosynthesis were similar between control and low-protein (LP) offspring. These results indicate that hepatic lipogenesis cannot mediate the decrease in liver TG content in LP offspring. We then determined whether increased lipid utilization in adipose tissue and muscle was responsible for the decrease in liver TG content. There was suggestive evidence of increased sympathetic nervous system tone in epididymal adipose tissue of LP offspring that increased fatty acid uptake, TG lipolysis, and utilization of fatty acids in mitochondrial thermogenesis. Measurement of similar parameters demonstrated that such alterations do not occur in gastrocnemius muscle, another major lipid-utilizing tissue. Our results suggest that the decrease in liver TG content in LP offspring is likely due to increased diversion of fatty acids to white and brown adipose tissue depots and their enhanced utilization to fuel mitochondrial thermogenesis.
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Affiliation(s)
- Claudia Mendez-Garcia
- Department of Pharmaceutical Sciences, University of the Sciences in Philadelphia, 600 South 43rd Street, Philadelphia, PA 19104, USA
| | - Afsana Trini
- Department of Pharmaceutical Sciences, University of the Sciences in Philadelphia, 600 South 43rd Street, Philadelphia, PA 19104, USA
| | - Veron Browne
- Department of Pharmaceutical Sciences, University of the Sciences in Philadelphia, 600 South 43rd Street, Philadelphia, PA 19104, USA
| | - Christopher J Kochansky
- Pharmacokinetics, Pharmacodynamics, and Drug Metabolism (PPDM), Merck & Co., Inc. P.O. Box 4, 770 Sumneytown Pike, WP75A-203, West Point, PA 19486, USA
| | - Laura Pontiggia
- Department of Mathematics, Physics, and Statistics, University of the Sciences in Philadelphia, 600 South 43rd Street, Philadelphia, PA 19104, USA
| | - Anil P D'mello
- Department of Pharmaceutical Sciences, University of the Sciences in Philadelphia, 600 South 43rd Street, Philadelphia, PA 19104, USA
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23
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Yang A, Mottillo EP, Mladenovic-Lucas L, Zhou L, Granneman JG. Dynamic interactions of ABHD5 with PNPLA3 regulate triacylglycerol metabolism in brown adipocytes. Nat Metab 2019; 1:560-569. [PMID: 31497752 PMCID: PMC6730670 DOI: 10.1038/s42255-019-0066-3] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Patatin-Like Phospholipase Domain Containing 2 (PNPLA2)/Adipose Triglyceride Lipase (ATGL) and PNPLA3/Adiponutrin are close paralogs that appear to have opposite functions on triacylglycerol (TAG) mobilization and storage. PNPLA2/ATGL is a major triglyceride lipase in adipose tissue and liver, whereas a common human variant of PNPLA3, I148M, greatly increases risk of hepatosteatosis. Nonetheless, the function of PNPLA3 and the mechanism by which the I148M variant promotes TAG accumulation are poorly understood. Here we demonstrate that PNPLA3 strongly interacts with α/β hydrolase domain-containing 5 (ABHD5/CGI-58), an essential co-activator of PNPLA2/ATGL. Molecular imaging experiments demonstrate that PNPLA3 effectively competes with PNPLA2/ATGL for ABHD5, and that PNPLA3 I148M is more effective in this regard. Inducible overexpression of PNPLA3 I148M greatly suppressed PNPLA2/ATGL-dependent lipolysis and triggered massive TAG accumulation in brown adipocytes, and these effects were dependent on ABHD5. The interaction of PNPLA3 and ABHD5 can be regulated by fatty acid supplementation and synthetic ABHD5 ligands, raising the possibility that this interaction might be targeted for treatment of fatty liver disease.
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Affiliation(s)
- Alexander Yang
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, USA 48201
- Co-first authors
| | - Emilio P. Mottillo
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, USA 48201
- Co-first authors
- Correspondence and requests for materials should be addressed to E.P.M. or J.G.G. (J.G.G.), (E.P.M.)
| | - Ljiljana Mladenovic-Lucas
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, USA 48201
| | - Li Zhou
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, USA 48201
| | - James G. Granneman
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, USA 48201
- Correspondence and requests for materials should be addressed to E.P.M. or J.G.G. (J.G.G.), (E.P.M.)
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24
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Moslehi A, Hamidi-zad Z. Role of SREBPs in Liver Diseases: A Mini-review. J Clin Transl Hepatol 2018; 6:332-338. [PMID: 30271747 PMCID: PMC6160306 DOI: 10.14218/jcth.2017.00061] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 01/10/2018] [Accepted: 02/11/2018] [Indexed: 12/15/2022] Open
Abstract
Sterol regulator element binding proteins (SREBPs) are a family of transcription factors involved in the biogenesis of cholesterol, fatty acids and triglycerides. They also regulate physiological functions of many organs, such as thyroid, brain, heart, pancreas and hormone synthesis. Beside the physiological effects, SREBPs participate in some pathological processes, diabetes, endoplasmic reticulum stress, atherosclerosis and chronic kidney disease associated with SREBP expression changes. In the liver, SREBPs are involved in the pathogenesis of nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, hepatitis and hepatic cancer. There are several SREBP inhibitors that have potential for treating obesity, diabetes and cancer. This review assesses the recent findings about the roles of SREBPs in the physiology of organs' function and pathogenesis of liver diseases.
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Affiliation(s)
- Azam Moslehi
- Department of Physiology, Cellular & Molecular Research Center, Qom University of Medical Sciences, Qom, Iran
| | - Zeinab Hamidi-zad
- Department of Physiology, Cellular & Molecular Research Center, Qom University of Medical Sciences, Qom, Iran
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25
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Chen J, Montagner A, Tan NS, Wahli W. Insights into the Role of PPARβ/δ in NAFLD. Int J Mol Sci 2018; 19:ijms19071893. [PMID: 29954129 PMCID: PMC6073272 DOI: 10.3390/ijms19071893] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 06/13/2018] [Accepted: 06/23/2018] [Indexed: 12/14/2022] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is a major health issue in developed countries. Although usually associated with obesity, NAFLD is also diagnosed in individuals with low body mass index (BMI) values, especially in Asia. NAFLD can progress from steatosis to non-alcoholic steatohepatitis (NASH), which is characterized by liver damage and inflammation, leading to cirrhosis and hepatocellular carcinoma (HCC). NAFLD development can be induced by lipid metabolism alterations; imbalances of pro- and anti-inflammatory molecules; and changes in various other factors, such as gut nutrient-derived signals and adipokines. Obesity-related metabolic disorders may be improved by activation of the nuclear receptor peroxisome proliferator-activated receptor (PPAR)β/δ, which is involved in metabolic processes and other functions. This review is focused on research findings related to PPARβ/δ-mediated regulation of hepatic lipid and glucose metabolism and NAFLD development. It also discusses the potential use of pharmacological PPARβ/δ activation for NAFLD treatment.
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Affiliation(s)
- Jiapeng Chen
- Lee Kong Chian School of Medicine, Nanyang Technological University, 11 Mandalay Road, Singapore 308232, Singapore.
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.
| | - Alexandra Montagner
- ToxAlim, Research Center in Food Toxicology, National Institute for Agricultural Research (INRA), 180 Chemin de Tournefeuille, 31300 Toulouse, France.
- Institut National de La Santé et de La Recherche Médicale (INSERM), UMR1048, Institute of Metabolic and Cardiovascular Diseases, 31027 Toulouse, France.
| | - Nguan Soon Tan
- Lee Kong Chian School of Medicine, Nanyang Technological University, 11 Mandalay Road, Singapore 308232, Singapore.
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.
- KK Research Centre, KK Women's and Children Hospital, 100 Bukit Timah Road, Singapore 229899, Singapore.
- Institute of Molecular and Cell Biology, Agency for Science Technology & Research, 61 Biopolis Drive, Proteos, Singapore 138673, Singapore.
| | - Walter Wahli
- Lee Kong Chian School of Medicine, Nanyang Technological University, 11 Mandalay Road, Singapore 308232, Singapore.
- ToxAlim, Research Center in Food Toxicology, National Institute for Agricultural Research (INRA), 180 Chemin de Tournefeuille, 31300 Toulouse, France.
- Center for Integrative Genomics, University of Lausanne, Génopode, CH-1015 Lausanne, Switzerland.
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26
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Liu YY, Zhai T, Yu QQ, Zhu J, Chen Y. Effect of high exposure of chlorogenic acid on lipid accumulation and oxidative stress in oleic acid-treated HepG2 cells. CHINESE HERBAL MEDICINES 2018. [DOI: 10.1016/j.chmed.2018.03.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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27
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Multi-tissue transcriptomic study reveals the main role of liver in the chicken adaptive response to a switch in dietary energy source through the transcriptional regulation of lipogenesis. BMC Genomics 2018. [PMID: 29514634 PMCID: PMC5842524 DOI: 10.1186/s12864-018-4520-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Background Because the cost of cereals is unstable and represents a large part of production charges for meat-type chicken, there is an urge to formulate alternative diets from more cost-effective feedstuff. We have recently shown that meat-type chicken source is prone to adapt to dietary starch substitution with fat and fiber. The aim of this study was to better understand the molecular mechanisms of this adaptation to changes in dietary energy sources through the fine characterization of transcriptomic changes occurring in three major metabolic tissues – liver, adipose tissue and muscle – as well as in circulating blood cells. Results We revealed the fine-tuned regulation of many hepatic genes encoding key enzymes driving glycogenesis and de novo fatty acid synthesis pathways and of some genes participating in oxidation. Among the genes expressed upon consumption of a high-fat, high-fiber diet, we highlighted CPT1A, which encodes a key enzyme in the regulation of fatty acid oxidation. Conversely, the repression of lipogenic genes by the high-fat diet was clearly associated with the down-regulation of SREBF1 transcripts but was not associated with the transcript regulation of MLXIPL and NR1H3, which are both transcription factors. This result suggests a pivotal role for SREBF1 in lipogenesis regulation in response to a decrease in dietary starch and an increase in dietary PUFA. Other prospective regulators of de novo hepatic lipogenesis were suggested, such as PPARD, JUN, TADA2A and KAT2B, the last two genes belonging to the lysine acetyl transferase (KAT) complex family regulating histone and non-histone protein acetylation. Hepatic glycogenic genes were also down-regulated in chickens fed a high-fat, high-fiber diet compared to those in chickens fed a starch-based diet. No significant dietary-associated variations in gene expression profiles was observed in the other studied tissues, suggesting that the liver mainly contributed to the adaptation of birds to changes in energy source and nutrients in their diets, at least at the transcriptional level. Moreover, we showed that PUFA deposition observed in the different tissues may not rely on transcriptional changes. Conclusion We showed the major role of the liver, at the gene expression level, in the adaptive response of chicken to dietary starch substitution with fat and fiber. Electronic supplementary material The online version of this article (10.1186/s12864-018-4520-5) contains supplementary material, which is available to authorized users.
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28
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Wilson SK, Knoll LJ. Patatin-like phospholipases in microbial infections with emerging roles in fatty acid metabolism and immune regulation by Apicomplexa. Mol Microbiol 2017; 107:34-46. [PMID: 29090840 DOI: 10.1111/mmi.13871] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 10/23/2017] [Accepted: 10/26/2017] [Indexed: 12/22/2022]
Abstract
Emerging lipidomic technologies have enabled researchers to dissect the complex roles of phospholipases in lipid metabolism, cellular signaling and immune regulation. Host phospholipase products are involved in stimulating and resolving the inflammatory response to pathogens. While many pathogen-derived phospholipases also manipulate the immune response, they have recently been shown to be involved in lipid remodeling and scavenging during replication. Animal and plant hosts as well as many pathogens contain a family of patatin-like phospholipases, which have been shown to have phospholipase A2 activity. Proteins containing patatin-like phospholipase domains have been identified in protozoan parasites within the Apicomplexa phylum. These parasites are the causative agents of some of the most widespread human diseases. Malaria, caused by Plasmodium spp., kills nearly half a million people worldwide each year. Toxoplasma and Cryptosporidium infect millions of people each year with lethal consequences in immunocompromised populations. Parasite-derived patatin-like phospholipases are likely effective drug targets and progress in the tools available to the Apicomplexan field will allow for a closer look at the interplay of lipid metabolism and immune regulation during host infection.
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Affiliation(s)
- Sarah K Wilson
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Laura J Knoll
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, 53706, USA
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29
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Martínez LA, Larrieta E, Kershenobich D, Torre A. The Expression of PNPLA3 Polymorphism could be the Key for Severe Liver Disease in NAFLD in Hispanic Population. Ann Hepatol 2017; 16:909-915. [PMID: 29055919 DOI: 10.5604/01.3001.0010.5282] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Nonalcoholic fatty liver disease (NAFLD) encompasses: fatty liver (SS), steatohepatitis (NASH) with or without fibrosis and cirrhosis. Patatine-like phosphatas in domain 3 (PNPLA3; adiponutrin; SNP rs738409 C/G, M148I) shows anabolic and catabolic activities on lipid metabolism and significant association to fatty liver content; however, I148M demographics and ethnics, as its role with NAFLD have not been fully elucidated. MATERIAL AND METHODS PNPLA3 genotyping from peripheral blood DNA by polymerase chain reaction (PCR) and direct sequencing, 211 patients diagnosed with NAFLD including SS, NASH and fibrosis spectrum. RESULTS Eighty nine per cent showed the G risk allele [CC: 23 (10.5%), GC: 73 (34.7%), GG 115 (54.7%)], the allele frequency was 77%, NASH (71%), SS (80%) and fibrosis (73%). GG genotype carriers showed 3.8 times (CI 95%: 3.03 - 4.79) of increased risk of steatohepatitis and 2.3 times more (CI 95%: 1.77 ~ 3.23) risk of having liver fibrosis (CC). PNPLA3 (GC, GG) conditioned higher probability of low levels of HDL cholesterol (p < 0.010), SS even in normal weight (p < 0.007), insulin resistance by HOMA (p < 0.029), NAFLD fibrosis score showed > 0.675 (p < 0.001) and altered serum alanine aminotransferase (p < 0.05). CONCLUSION PNPLA3 expression in Hispanics could be decisive in NAFLD pathogenesis, it's highly prevalent and it's a key to condition and determine the spectrum associated, SS, NASH and fibrosis.
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Affiliation(s)
- Leonardo A Martínez
- Department of Gastroenterology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City
| | - Elena Larrieta
- Department of Gastroenterology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City
| | - David Kershenobich
- Institutional Director, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City
| | - Aldo Torre
- Department of Gastroenterology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City
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Insulin Resistance, Obesity and Lipotoxicity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 960:277-304. [PMID: 28585204 DOI: 10.1007/978-3-319-48382-5_12] [Citation(s) in RCA: 285] [Impact Index Per Article: 40.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Lipotoxicity , originally used to describe the destructive effects of excess fat accumulation on glucose metabolism, causes functional impairments in several metabolic pathways, both in adipose tissue and peripheral organs, like liver, heart, pancreas and muscle. Lipotoxicity has roles in insulin resistance and pancreatic beta cell dysfunction. Increased circulating levels of lipids and the metabolic alterations in fatty acid utilization and intracellular signaling, have been related to insulin resistance in muscle and liver. Different pathways, like novel protein kinase c pathways and the JNK-1 pathway are involved as the mechanisms of how lipotoxicity leads to insulin resistance in nonadipose tissue organs, such as liver and muscle. Mitochondrial dysfunction plays a role in the pathogenesis of insulin resistance. Endoplasmic reticulum stress, through mainly increased oxidative stress, also plays important role in the etiology of insulin resistance, especially seen in non-alcoholic fatty liver disease. Visceral adiposity and insulin resistance both increase the cardiometabolic risk and lipotoxicity seems to play a crucial role in the pathophysiology of these associations.
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Gluchowski NL, Becuwe M, Walther TC, Farese RV. Lipid droplets and liver disease: from basic biology to clinical implications. Nat Rev Gastroenterol Hepatol 2017; 14:343-355. [PMID: 28428634 PMCID: PMC6319657 DOI: 10.1038/nrgastro.2017.32] [Citation(s) in RCA: 404] [Impact Index Per Article: 57.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Lipid droplets are dynamic organelles that store neutral lipids during times of energy excess and serve as an energy reservoir during deprivation. Many prevalent metabolic diseases, such as the metabolic syndrome or obesity, often result in abnormal lipid accumulation in lipid droplets in the liver, also called hepatic steatosis. Obesity-related steatosis, or NAFLD in particular, is a major public health concern worldwide and is frequently associated with insulin resistance and type 2 diabetes mellitus. Here, we review the latest insights into the biology of lipid droplets and their role in maintaining lipid homeostasis in the liver. We also offer a perspective of liver diseases that feature lipid accumulation in these lipid storage organelles, which include NAFLD and viral hepatitis. Although clinical applications of this knowledge are just beginning, we highlight new opportunities for identifying molecular targets for treating hepatic steatosis and steatohepatitis.
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Affiliation(s)
- Nina L. Gluchowski
- Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, 655 Huntington Avenue, Boston, Massachusetts 02115, USA.,Boston Children’s Hospital Department of Gastroenterology, Hepatology and Nutrition, 300 Longwood Avenue Boston, Massachusetts 02115, USA
| | - Michel Becuwe
- Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, 655 Huntington Avenue, Boston, Massachusetts 02115, USA
| | - Tobias C. Walther
- Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, 655 Huntington Avenue, Boston, Massachusetts 02115, USA.,Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue Boston, Massachusetts 02115, USA.,Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur Boston, Massachusetts 02115, USA.,Howard Hughes Medical Institute, Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, 655 Huntington Avenue, Boston, Massachusetts 02115, USA
| | - Robert V. Farese
- Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, 655 Huntington Avenue, Boston, Massachusetts 02115, USA.,Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue Boston, Massachusetts 02115, USA.,Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur Boston, Massachusetts 02115, USA
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Asimakopoulou A, Fülöp A, Borkham-Kamphorst E, de Leur EV, Gassler N, Berger T, Beine B, Meyer HE, Mak TW, Hopf C, Henkel C, Weiskirchen R. Altered mitochondrial and peroxisomal integrity in lipocalin-2-deficient mice with hepatic steatosis. Biochim Biophys Acta Mol Basis Dis 2017; 1863:2093-2110. [PMID: 28396286 DOI: 10.1016/j.bbadis.2017.04.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 03/04/2017] [Accepted: 04/06/2017] [Indexed: 01/10/2023]
Abstract
Lipocalin-2 (LCN2) is a secreted adipokine that transports small hydrophobic molecules such as fatty acids and steroids. LCN2 limits bacterial growth by sequestering iron-containing siderophores and in mammalian liver protects against inflammation, infection, injury and other stressors. Because LCN2 modulates hepatic fat metabolism and homeostasis, we performed a comparative profiling of proteins and lipids of wild type (WT) and Lcn2-deficient mice fed either standard chow or a methionine- and choline-deficient (MCD) diet. Label-free proteomics and 2D-DIGE protein expression profiling revealed differential expression of BRIT1/MCPH1, FABP5, HMGB1, HBB2, and L-FABP, results confirmed by Western blotting. Gene ontology enrichment analysis identified enrichment for genes associated with mitochondrial membrane permeabilization and metabolic processes involving carboxylic acid. Measurements of mitochondrial membrane potential, mitochondrial chelatable iron pool, intracellular lipid peroxidation, and peroxisome numbers in primary hepatocytes confirmed that LCN2 regulates mitochondrial and peroxisomal integrity. Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight (MALDI-TOF) mass spectrometry imaging identified significant changes to sphingomyelins, triglycerides, and glycerophospholipids in livers of mice fed an MCD diet regardless of LCN2 status. However, two arachidonic acid-containing glycerophospholipids were increased in Lcn2-deficient livers. Thus, LCN2 influences peroxisomal and mitochondrial biology in the liver to maintain triglyceride balance, handle oxidative stress, and control apoptosis.
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Affiliation(s)
- Anastasia Asimakopoulou
- Institute of Molecular Pathobiochemistry, Experimental Gene Therapy and Clinical Chemistry, RWTH University Hospital Aachen, Aachen, Germany
| | - Annabelle Fülöp
- Applied Research Center in Biomedical Mass Spectrometry (ABIMAS), Instrumental Analysis and Bioanalysis, Mannheim University of Applied Sciences, Mannheim, Germany
| | - Erawan Borkham-Kamphorst
- Institute of Molecular Pathobiochemistry, Experimental Gene Therapy and Clinical Chemistry, RWTH University Hospital Aachen, Aachen, Germany
| | - Eddy Van de Leur
- Institute of Molecular Pathobiochemistry, Experimental Gene Therapy and Clinical Chemistry, RWTH University Hospital Aachen, Aachen, Germany
| | | | - Thorsten Berger
- The Campbell Family Institute for Breast Cancer Research, University Health Network, Toronto, ON, Canada
| | - Birte Beine
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., Dortmund, Germany; Medizinisches Proteom-Center, Ruhr-University, Bochum, Germany
| | - Helmut E Meyer
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., Dortmund, Germany
| | - Tak W Mak
- The Campbell Family Institute for Breast Cancer Research, University Health Network, Toronto, ON, Canada; Ontario Cancer Institute, University Health Network, Toronto, ON, Canada
| | - Carsten Hopf
- Applied Research Center in Biomedical Mass Spectrometry (ABIMAS), Instrumental Analysis and Bioanalysis, Mannheim University of Applied Sciences, Mannheim, Germany
| | - Corinna Henkel
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., Dortmund, Germany; Medizinisches Proteom-Center, Ruhr-University, Bochum, Germany; Bruker Daltonik GmbH, Bremen
| | - Ralf Weiskirchen
- Institute of Molecular Pathobiochemistry, Experimental Gene Therapy and Clinical Chemistry, RWTH University Hospital Aachen, Aachen, Germany.
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A Guide to Non-Alcoholic Fatty Liver Disease in Childhood and Adolescence. Int J Mol Sci 2016; 17:ijms17060947. [PMID: 27314342 PMCID: PMC4926480 DOI: 10.3390/ijms17060947] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 06/06/2016] [Accepted: 06/07/2016] [Indexed: 02/07/2023] Open
Abstract
Non-Alcoholic Fatty Liver Disease (NAFLD) is now the most prevalent form of chronic liver disease, affecting 10%–20% of the general paediatric population. Within the next 10 years it is expected to become the leading cause of liver pathology, liver failure and indication for liver transplantation in childhood and adolescence in the Western world. While our understanding of the pathophysiological mechanisms underlying this disease remains limited, it is thought to be the hepatic manifestation of more widespread metabolic dysfunction and is strongly associated with a number of metabolic risk factors, including insulin resistance, dyslipidaemia, cardiovascular disease and, most significantly, obesity. Despite this, ”paediatric” NAFLD remains under-studied, under-recognised and, potentially, undermanaged. This article will explore and evaluate our current understanding of NAFLD in childhood and adolescence and how it differs from adult NAFLD, in terms of its epidemiology, pathophysiology, natural history, diagnosis and clinical management. Given the current absence of definitive radiological and histopathological diagnostic tests, maintenance of a high clinical suspicion by all members of the multidisciplinary team in primary and specialist care settings remains the most potent of diagnostic tools, enabling early diagnosis and appropriate therapeutic intervention.
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Marmugi A, Lukowicz C, Lasserre F, Montagner A, Polizzi A, Ducheix S, Goron A, Gamet-Payrastre L, Gerbal-Chaloin S, Pascussi JM, Moldes M, Pineau T, Guillou H, Mselli-Lakhal L. Activation of the Constitutive Androstane Receptor induces hepatic lipogenesis and regulates Pnpla3 gene expression in a LXR-independent way. Toxicol Appl Pharmacol 2016; 303:90-100. [PMID: 27180240 DOI: 10.1016/j.taap.2016.05.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 05/02/2016] [Accepted: 05/09/2016] [Indexed: 12/20/2022]
Abstract
The Constitutive Androstane Receptor (CAR, NR1I3) has been newly described as a regulator of energy metabolism. A relevant number of studies using animal models of obesity suggest that CAR activation could be beneficial on the metabolic balance. However, this remains controversial and the underlying mechanisms are still unknown. This work aimed to investigate the effect of CAR activation on hepatic energy metabolism during physiological conditions, i.e. in mouse models not subjected to metabolic/nutritional stress. Gene expression profiling in the liver of CAR knockout and control mice on chow diet and treated with a CAR agonist highlighted CAR-mediated up-regulations of lipogenic genes, concomitant with neutral lipid accumulation. A strong CAR-mediated up-regulation of the patatin-like phospholipase domain-containing protein 3 (Pnpla3) was demonstrated. Pnpla3 is a gene whose polymorphism is associated with the pathogenesis of nonalcoholic fatty liver disease (NAFLD) development. This observation was confirmed in human hepatocytes treated with the antiepileptic drug and CAR activator, phenobarbital and in immortalized human hepatocytes treated with CITCO. Studying the molecular mechanisms controlling Pnpla3 gene expression, we demonstrated that CAR does not act by a direct regulation of Pnpla3 transcription or via the Liver X Receptor but may rather involve the transcription factor Carbohydrate Responsive Element-binding protein. These data provide new insights into the regulation by CAR of glycolytic and lipogenic genes and on pathogenesis of steatosis. This also raises the question concerning the impact of drugs and environmental contaminants in lipid-associated metabolic diseases.
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Affiliation(s)
- Alice Marmugi
- INRA, TOXALIM (Research Centre in Food Toxicology), Toulouse, France; Université de Toulouse, INP, UPS, TOXALIM, Toulouse, France
| | - Céline Lukowicz
- INRA, TOXALIM (Research Centre in Food Toxicology), Toulouse, France; Université de Toulouse, INP, UPS, TOXALIM, Toulouse, France
| | - Frederic Lasserre
- INRA, TOXALIM (Research Centre in Food Toxicology), Toulouse, France; Université de Toulouse, INP, UPS, TOXALIM, Toulouse, France
| | - Alexandra Montagner
- INRA, TOXALIM (Research Centre in Food Toxicology), Toulouse, France; Université de Toulouse, INP, UPS, TOXALIM, Toulouse, France
| | - Arnaud Polizzi
- INRA, TOXALIM (Research Centre in Food Toxicology), Toulouse, France; Université de Toulouse, INP, UPS, TOXALIM, Toulouse, France
| | - Simon Ducheix
- INRA, TOXALIM (Research Centre in Food Toxicology), Toulouse, France; Université de Toulouse, INP, UPS, TOXALIM, Toulouse, France
| | - Adeline Goron
- INRA, TOXALIM (Research Centre in Food Toxicology), Toulouse, France; Université de Toulouse, INP, UPS, TOXALIM, Toulouse, France
| | - Laurence Gamet-Payrastre
- INRA, TOXALIM (Research Centre in Food Toxicology), Toulouse, France; Université de Toulouse, INP, UPS, TOXALIM, Toulouse, France
| | - Sabine Gerbal-Chaloin
- Institute of Regenerative Medicine and Biotherapy, INSERM, U1183 Montpellier, France
| | - Jean Marc Pascussi
- Centre National de la Recherche Scientifique, UMR5203, Institut de Génomique Fonctionnelle, Montpellier, France
| | - Marthe Moldes
- Centre de Recherche Saint-Antoine, INSERM, UMR 938, Sorbonne Universités, Université Paris 6, Paris, France; Institut Hospitalo-Universitaire ICAN, Paris, France
| | - Thierry Pineau
- INRA, TOXALIM (Research Centre in Food Toxicology), Toulouse, France; Université de Toulouse, INP, UPS, TOXALIM, Toulouse, France
| | - Hervé Guillou
- INRA, TOXALIM (Research Centre in Food Toxicology), Toulouse, France; Université de Toulouse, INP, UPS, TOXALIM, Toulouse, France
| | - Laila Mselli-Lakhal
- INRA, TOXALIM (Research Centre in Food Toxicology), Toulouse, France; Université de Toulouse, INP, UPS, TOXALIM, Toulouse, France.
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Liu W, Baker RD, Bhatia T, Zhu L, Baker SS. Pathogenesis of nonalcoholic steatohepatitis. Cell Mol Life Sci 2016; 73:1969-87. [PMID: 26894897 PMCID: PMC11108381 DOI: 10.1007/s00018-016-2161-x] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 01/19/2016] [Accepted: 02/09/2016] [Indexed: 02/06/2023]
Abstract
Nonalcoholic steatohepatitis (NASH) is a severe form of nonalcoholic fatty liver disease and a risk factor for cirrhosis and hepatocellular carcinoma. The pathological features of NASH include steatosis, hepatocyte injury, inflammation, and various degrees of fibrosis. Steatosis reflects disordered lipid metabolism. Insulin resistance and excessive fatty acid influx to the liver are two important contributing factors. Steatosis is also likely associated with lipotoxicity and cellular stresses such as oxidative stress and endoplasmic reticulum stress, which result in hepatocyte injury. Inflammation and fibrosis are frequently triggered by various signals such as proinflammatory cytokines and chemokines, released by injuried hepatocytes and activated Kupffer cells. Although much progress has been made, the pathogenesis of NASH is not fully elucidated. The purpose of this review is to discuss the current understanding of NASH pathogenesis, mainly focusing on factors contributing to steatosis, hepatocyte injury, inflammation, and fibrosis.
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Affiliation(s)
- Wensheng Liu
- Department of Pediatrics, Digestive Diseases and Nutrition Center, Women and Children's Hospital of Buffalo, The State University of New York at Buffalo (SUNY Buffalo), 3435 Main Street, 422 BRB, Buffalo, NY, 14214, USA.
| | - Robert D Baker
- Department of Pediatrics, Digestive Diseases and Nutrition Center, Women and Children's Hospital of Buffalo, The State University of New York at Buffalo (SUNY Buffalo), 3435 Main Street, 422 BRB, Buffalo, NY, 14214, USA
| | - Tavleen Bhatia
- Department of Pediatrics, Digestive Diseases and Nutrition Center, Women and Children's Hospital of Buffalo, The State University of New York at Buffalo (SUNY Buffalo), 3435 Main Street, 422 BRB, Buffalo, NY, 14214, USA
| | - Lixin Zhu
- Department of Pediatrics, Digestive Diseases and Nutrition Center, Women and Children's Hospital of Buffalo, The State University of New York at Buffalo (SUNY Buffalo), 3435 Main Street, 422 BRB, Buffalo, NY, 14214, USA
| | - Susan S Baker
- Department of Pediatrics, Digestive Diseases and Nutrition Center, Women and Children's Hospital of Buffalo, The State University of New York at Buffalo (SUNY Buffalo), 3435 Main Street, 422 BRB, Buffalo, NY, 14214, USA.
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Mann JP, Semple RK, Armstrong MJ. How Useful Are Monogenic Rodent Models for the Study of Human Non-Alcoholic Fatty Liver Disease? Front Endocrinol (Lausanne) 2016; 7:145. [PMID: 27899914 PMCID: PMC5110950 DOI: 10.3389/fendo.2016.00145] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2016] [Accepted: 11/01/2016] [Indexed: 12/22/2022] Open
Abstract
Improving understanding of the genetic basis of human non-alcoholic fatty liver disease (NAFLD) has the potential to facilitate risk stratification of affected patients, permit personalized treatment, and inform development of new therapeutic strategies. Animal models have been widely used to interrogate the pathophysiology of, and genetic predisposition to, NAFLD. Nevertheless, considerable interspecies differences in intermediary metabolism potentially limit the extent to which results can be extrapolated to humans. For example, human genome-wide association studies have identified polymorphisms in PNPLA3 and TM6SF2 as the two most prevalent determinants of susceptibility to NAFLD and its inflammatory component (NASH), but animal models of these mutations have had only variable success in recapitulating this link. In this review, we critically appraise selected murine monogenic models of NAFLD, NASH, and hepatocellular carcinoma (HCC) with a focus on how closely they mirror human disease.
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Affiliation(s)
- Jake P. Mann
- Department of Paediatrics, University of Cambridge, Cambridge, UK
| | - Robert K. Semple
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
- The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, UK
- *Correspondence: Robert K. Semple,
| | - Matthew J. Armstrong
- Centre for Liver Research, National Institute for Health Research (NIHR) Birmingham Liver Biomedical Research Unit, University of Birmingham, Birmingham, UK
- Liver Unit, Queen Elizabeth University Hospital Birmingham, Birmingham, UK
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Tetra-primer ARMS-PCR identified four pivotal genetic variations in bovine PNPLA3 gene and its expression patterns. Gene 2015; 575:191-8. [PMID: 26318478 DOI: 10.1016/j.gene.2015.08.047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 08/20/2015] [Accepted: 08/22/2015] [Indexed: 11/22/2022]
Abstract
Patatin-like phospholipase domain-containing protein 3 (PNPLA3), a member of the patatin like phospholipase domain-containing (PNPLA) family, plays an important role in energy balance, fat metabolism regulation, glucose metabolism and fatty liver disease. Tetra-primer amplification refractory mutation system PCR (T-ARMS-PCR) is a new method offering fast detection and extreme simplicity at a negligible cost for SNP genotyping. In this paper, we investigated the genetic variations at different ages of 660 Chinese indigenous cattle belonging to three breeds (QC, NY, JX) and applied T-ARMS-PCR and PCR-RFLP methods to genotype four SNPs, SNP1: g.A2980G, SNP2: g.A2996T, SNP3: g.A36718G, SNP4: g.G36850A. The statistical analyses indicated that these 4 SNPs affected growth traits markedly (P<0.05) in QC population, whereas combined haplotypes were not (P>0.05). The qPCR (quantitative PCR) indicated that bovine PNPLA3 gene was exclusively expressed in fat tissues. Besides, the analysis between SNP and mRNA expression revealed that, in SNP1, the expression of AG was much higher than AA and GG (P<0.05), which was in accordance with the results of growth traits association analysis, while the results of SNP4 was not. These results supported high potential that SNPs of bovine PNPLA3 gene might be utilized as genetic markers in marker-assisted selection (MAS) for Chinese cattle breeding programs.
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Liang H, Xu J, Xu F, Liu H, Yuan D, Yuan S, Cai M, Yan J, Weng J. The SRE Motif in the Human PNPLA3 Promoter (-97 to -88 bp) Mediates Transactivational Effects of SREBP-1c. J Cell Physiol 2015; 230:2224-32. [PMID: 25655569 DOI: 10.1002/jcp.24951] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 01/23/2015] [Indexed: 12/24/2022]
Abstract
Patatin-like phospholipase domain containing 3 (PNPLA3) is a non-secreted protein primarily expressed in liver and adipose tissue. Recently, numerous genetic studies have shown that PNPLA3 is a major susceptibility gene for nonalcoholic fatty liver disease (NAFLD). However, the mechanism involved in transcriptional regulation of the PNPLA3 gene remains unknown. We performed a detailed analysis of the human PNPLA3 gene promoter and identified two novel cis-acting elements (SRE and NFY binding motifs) located at -97/-88 and -26/-22 bp, respectively. Overexpression of SREBP-1c in HepG2 cells significantly increased PNPLA3 promoter activity. Mutation of either of the putative SRE or NFY binding motifs blocked the transactivation effects of SREBP-1c on the promoter. Overexpression of SREBP-1c and NFY together increased PNPLA3 promoter activity twice as much as that of SREBP-1c or NFY expression alone. This result suggests that SREBP-1c and NFY synergistically transactivate the human PNPLA3 gene. The ability of SREBP-1c and NFY to bind these cis-elements was confirmed using gel shift analysis. Putative SRE and NFY motifs also mediated synergistic insulin-induced transactivation of the PNPLA3 promoter in HepG2 cells. Additionally, the ability of SREBP-1c to bind to the PNPLA3 promoter was increased by insulin in a dose-dependent manner. Moreover, the treatment of HepG2 cells with the PI3K inhibitor LY294002 led to reduced insulin promoter-activating ability accompanied by a decrease in PNPLA3 and SREBP-1c protein expression. These results demonstrate that SREBP-1c is a direct activator of the human PNPLA3 gene and insulin transactivates the PNPLA3 gene via the PI3K-SREBP-1c/NFY pathway in HepG2 cells.
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Affiliation(s)
- Hua Liang
- Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, P.R.China
| | - Jing Xu
- Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, P.R.China
| | - Fen Xu
- Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, P.R.China
| | - Hongxia Liu
- Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, P.R.China
| | - Ding Yuan
- Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, P.R.China
| | - Shuhua Yuan
- Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, P.R.China
| | - Mengyin Cai
- Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, P.R.China
| | - Jinhua Yan
- Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, P.R.China
| | - Jianping Weng
- Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, P.R.China
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Targher G, Byrne CD. A Perspective on Metabolic Syndrome and Nonalcoholic Fatty Liver Disease. Metab Syndr Relat Disord 2015; 13:235-8. [DOI: 10.1089/met.2015.1502] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Giovanni Targher
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University and Azienda Ospedaliera Universitaria Integrata of Verona, Verona, Italy
| | - Christopher D. Byrne
- Nutrition and Metabolism, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
- Southampton National Institute for Health Research Biomedical Research Centre, University Hospital Southampton, Southampton, United Kingdom
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Eichmann TO, Lass A. DAG tales: the multiple faces of diacylglycerol--stereochemistry, metabolism, and signaling. Cell Mol Life Sci 2015; 72:3931-52. [PMID: 26153463 PMCID: PMC4575688 DOI: 10.1007/s00018-015-1982-3] [Citation(s) in RCA: 175] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 06/17/2015] [Accepted: 06/29/2015] [Indexed: 12/31/2022]
Abstract
The neutral lipids diacylglycerols (DAGs) are involved in a plethora of metabolic pathways. They function as components of cellular membranes, as building blocks for glycero(phospho)lipids, and as lipid second messengers. Considering their central role in multiple metabolic processes and signaling pathways, cellular DAG levels require a tight regulation to ensure a constant and controlled availability. Interestingly, DAG species are versatile in their chemical structure. Besides the different fatty acid species esterified to the glycerol backbone, DAGs can occur in three different stereo/regioisoforms, each with unique biological properties. Recent scientific advances have revealed that DAG metabolizing enzymes generate and distinguish different DAG isoforms, and that only one DAG isoform holds signaling properties. Herein, we review the current knowledge of DAG stereochemistry and their impact on cellular metabolism and signaling. Further, we describe intracellular DAG turnover and its stereochemistry in a 3-pool model to illustrate the spatial and stereochemical separation and hereby the diversity of cellular DAG metabolism.
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Affiliation(s)
- Thomas Oliver Eichmann
- Institute of Molecular Biosciences, University of Graz, Heinrichstrasse 31/2, 8010, Graz, Austria.
| | - Achim Lass
- Institute of Molecular Biosciences, University of Graz, Heinrichstrasse 31/2, 8010, Graz, Austria.
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Stickel F, Hampe J, Trépo E, Datz C, Romeo S. PNPLA3 genetic variation in alcoholic steatosis and liver disease progression. Hepatobiliary Surg Nutr 2015; 4:152-60. [PMID: 26151055 DOI: 10.3978/j.issn.2304-3881.2014.11.04] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2014] [Accepted: 10/29/2014] [Indexed: 12/23/2022]
Abstract
Alcoholic liver disease (ALD) accounts for the majority of chronic liver diseases in Western countries, and alcoholic cirrhosis is among the premier causes of liver failure, hepatocellular carcinoma (HCC) and liver-related mortality causes. Studies in different genders and ethnic groups, as well as in twins provide strong evidence for a significant contribution of host genetic factors to liver disease development in drinkers. The intense quest for genetic modifiers of alcohol-induced fibrosis progression have identified and repeatedly confirmed a genetic polymorphism in the gene coding for patatin-like phospholipase domain-containing 3 (PNPLA3; adiponutrin; rs738409 C/G, M148I) as a risk factor for alcoholic cirrhosis and its related complication, HCC, in different populations. Although carriership of one or both mutated PNPLA3 alleles does not explain the entire liver phenotypic variability in drinkers, it clearly represents one of the strongest single genetic modulators in a complex trait such as ALD. As more genetic data supporting its important role aggregates, novel insight as to PNPLA3's function and that of its genetic variation in liver injury is unveiled pointing to an important novel pathway in alcohol-mediated hepatic lipid turnover with strong implications on inflammation, extra cellular matrix remodelling, and hepatocarcinogenesis. Future study shall decipher whether the gathered knowledge can be translated into therapeutic benefits of patients.
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Affiliation(s)
- Felix Stickel
- 1 Department of Gastroenterology and Hepatology, University Hospital of Zurich, Switzerland & Hepatology Unit, Clinic Beau-Site, Hirslanden Bern, Bern, Switzerland ; 2 Medical Department I, University Hospital Dresden, TU Dresden, Dresden, Germany ; 3 Department of Gastroenterology, Hepatopancreatology and Digestive Oncology, C.U.B. Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium ; 4 Laboratory of Experimental Gastroenterology, Université Libre de Bruxelles, Brussels, Belgium ; 5 Department of Gastroenterology, Paracelsus University of Salzburg, Hospital Oberndorf, Austria ; 6 Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, Wallenberg Laboratory, University of Gothenburg, Gothenburg, Sweden
| | - Jochen Hampe
- 1 Department of Gastroenterology and Hepatology, University Hospital of Zurich, Switzerland & Hepatology Unit, Clinic Beau-Site, Hirslanden Bern, Bern, Switzerland ; 2 Medical Department I, University Hospital Dresden, TU Dresden, Dresden, Germany ; 3 Department of Gastroenterology, Hepatopancreatology and Digestive Oncology, C.U.B. Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium ; 4 Laboratory of Experimental Gastroenterology, Université Libre de Bruxelles, Brussels, Belgium ; 5 Department of Gastroenterology, Paracelsus University of Salzburg, Hospital Oberndorf, Austria ; 6 Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, Wallenberg Laboratory, University of Gothenburg, Gothenburg, Sweden
| | - Eric Trépo
- 1 Department of Gastroenterology and Hepatology, University Hospital of Zurich, Switzerland & Hepatology Unit, Clinic Beau-Site, Hirslanden Bern, Bern, Switzerland ; 2 Medical Department I, University Hospital Dresden, TU Dresden, Dresden, Germany ; 3 Department of Gastroenterology, Hepatopancreatology and Digestive Oncology, C.U.B. Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium ; 4 Laboratory of Experimental Gastroenterology, Université Libre de Bruxelles, Brussels, Belgium ; 5 Department of Gastroenterology, Paracelsus University of Salzburg, Hospital Oberndorf, Austria ; 6 Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, Wallenberg Laboratory, University of Gothenburg, Gothenburg, Sweden
| | - Christian Datz
- 1 Department of Gastroenterology and Hepatology, University Hospital of Zurich, Switzerland & Hepatology Unit, Clinic Beau-Site, Hirslanden Bern, Bern, Switzerland ; 2 Medical Department I, University Hospital Dresden, TU Dresden, Dresden, Germany ; 3 Department of Gastroenterology, Hepatopancreatology and Digestive Oncology, C.U.B. Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium ; 4 Laboratory of Experimental Gastroenterology, Université Libre de Bruxelles, Brussels, Belgium ; 5 Department of Gastroenterology, Paracelsus University of Salzburg, Hospital Oberndorf, Austria ; 6 Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, Wallenberg Laboratory, University of Gothenburg, Gothenburg, Sweden
| | - Stefano Romeo
- 1 Department of Gastroenterology and Hepatology, University Hospital of Zurich, Switzerland & Hepatology Unit, Clinic Beau-Site, Hirslanden Bern, Bern, Switzerland ; 2 Medical Department I, University Hospital Dresden, TU Dresden, Dresden, Germany ; 3 Department of Gastroenterology, Hepatopancreatology and Digestive Oncology, C.U.B. Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium ; 4 Laboratory of Experimental Gastroenterology, Université Libre de Bruxelles, Brussels, Belgium ; 5 Department of Gastroenterology, Paracelsus University of Salzburg, Hospital Oberndorf, Austria ; 6 Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, Wallenberg Laboratory, University of Gothenburg, Gothenburg, Sweden
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Berlanga A, Guiu-Jurado E, Porras JA, Aragonès G, Auguet T. [Role of metabolic lipases and lipotoxicity in the development of non-alcoholic steatosis and non-alcoholic steatohepatitis]. CLINICA E INVESTIGACION EN ARTERIOSCLEROSIS 2015; 28:47-61. [PMID: 26049666 DOI: 10.1016/j.arteri.2015.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 03/03/2015] [Accepted: 03/04/2015] [Indexed: 10/23/2022]
Abstract
Non-alcoholic fatty liver disease (NAFLD) has become the most common liver disease in developed countries, covering a spectrum of pathological conditions ranging from single steatosis to non-alcoholic steatohepatitis, cirrhosis and hepatocellular carcinoma. Its pathogenesis has been often interpreted by the "double-hit" hypothesis, where the lipid accumulation in the liver is followed by proinflammatory mediators inducing inflammation, hepatocellular injury and fibrosis. Nowadays, a more complex model suggests that free fatty acids and their metabolites could be the true lipotoxic agents that contribute to the development of NAFLD and hepatic insulin resistance, suggesting a central role for metabolic lipases in that process.
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Affiliation(s)
- Alba Berlanga
- Grupo de recerca GEMMAIR (AGAUR)-Medicina Aplicada, Departamento de Medicina y Cirugía, Universidad Rovira i Virgili (URV), Institut d'Investigació Sanitària Pere Virgili (IISPV), Tarragona, España
| | - Esther Guiu-Jurado
- Grupo de recerca GEMMAIR (AGAUR)-Medicina Aplicada, Departamento de Medicina y Cirugía, Universidad Rovira i Virgili (URV), Institut d'Investigació Sanitària Pere Virgili (IISPV), Tarragona, España
| | - José Antonio Porras
- Grupo de recerca GEMMAIR (AGAUR)-Medicina Aplicada, Departamento de Medicina y Cirugía, Universidad Rovira i Virgili (URV), Institut d'Investigació Sanitària Pere Virgili (IISPV), Tarragona, España; Servicio de Medicina Interna, Hospital Universitario Joan XXIII, Tarragona, España
| | - Gemma Aragonès
- Grupo de recerca GEMMAIR (AGAUR)-Medicina Aplicada, Departamento de Medicina y Cirugía, Universidad Rovira i Virgili (URV), Institut d'Investigació Sanitària Pere Virgili (IISPV), Tarragona, España
| | - Teresa Auguet
- Grupo de recerca GEMMAIR (AGAUR)-Medicina Aplicada, Departamento de Medicina y Cirugía, Universidad Rovira i Virgili (URV), Institut d'Investigació Sanitària Pere Virgili (IISPV), Tarragona, España; Servicio de Medicina Interna, Hospital Universitario Joan XXIII, Tarragona, España.
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Carr RM, Correnti J. Insulin resistance in clinical and experimental alcoholic liver disease. Ann N Y Acad Sci 2015; 1353:1-20. [PMID: 25998863 DOI: 10.1111/nyas.12787] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Alcoholic liver disease (ALD) is the number one cause of liver failure worldwide; its management costs billions of healthcare dollars annually. Since the advent of the obesity epidemic, insulin resistance (IR) and diabetes have become common clinical findings in patients with ALD; and the development of IR predicts the progression from simple steatosis to cirrhosis in ALD patients. Both clinical and experimental data implicate the impairment of several mediators of insulin signaling in ALD, and experimental data suggest that insulin-sensitizing therapies improve liver histology. This review explores the contribution of impaired insulin signaling in ALD and summarizes the current understanding of the synergistic relationship between alcohol and nutrient excess in promoting hepatic inflammation and disease.
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Affiliation(s)
- Rotonya M Carr
- Division of Gastroenterology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jason Correnti
- Division of Gastroenterology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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44
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Fuchs CD, Claudel T, Trauner M. Role of metabolic lipases and lipolytic metabolites in the pathogenesis of NAFLD. Trends Endocrinol Metab 2014; 25:576-85. [PMID: 25183341 DOI: 10.1016/j.tem.2014.08.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 08/06/2014] [Accepted: 08/06/2014] [Indexed: 12/12/2022]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is the most frequent chronic liver disease in Western countries, ranging from simple steatosis to steatohepatitis, cirrhosis, and hepatocellular cancer. Although the mechanisms underlying disease progression are incompletely understood, lipotoxic events in the liver resulting in inflammation and fibrosis appear to be central. Free fatty acids and their metabolites are potentially lipotoxic mediators triggering liver injury, suggesting a central role for metabolic lipases. These enzymes are major players in lipid partitioning between tissues and within cells, and provide ligands for nuclear receptors (NRs). We discuss the potential role of intracellular lipases and their lipolytic products in NAFLD. Because tissue-specific modulation of lipases is currently impossible, targeting NRs with ligands may open novel therapeutic perspectives.
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Affiliation(s)
- Claudia D Fuchs
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Thierry Claudel
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Michael Trauner
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria.
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45
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Hao L, Ito K, Huang KH, Sae-tan S, Lambert JD, Ross AC. Shifts in dietary carbohydrate-lipid exposure regulate expression of the non-alcoholic fatty liver disease-associated gene PNPLA3/adiponutrin in mouse liver and HepG2 human liver cells. Metabolism 2014; 63:1352-62. [PMID: 25060692 PMCID: PMC4175036 DOI: 10.1016/j.metabol.2014.06.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 05/24/2014] [Accepted: 06/17/2014] [Indexed: 02/07/2023]
Abstract
OBJECTIVE Patatin-like phospholipase domain containing 3 (PNPLA3, adiponutrin) has been identified as a modifier of lipid metabolism. To better understand the physiological role of PNPLA3/adiponutrin, we have investigated its regulation in intact mice and human hepatocytes under various nutritional/metabolic conditions. MATERIAL/METHODS PNPLA3 gene expression was determined by real-time PCR in liver of C57BL/6 mice after dietary treatments and in HepG2 cells exposed to various nutritional/metabolic stimuli. Intracellular lipid content was determined in HepG2 cells after siRNA-mediated knockdown of PNPLA3. RESULTS In vivo, mice fed a high-carbohydrate (HC) liquid diet had elevated hepatic lipid content, and PNPLA3 mRNA and protein expression, compared to chow-fed mice. Elevated expression was completely abrogated by addition of unsaturated lipid emulsion to the HC diet. By contrast, in mice with high-fat diet-induced steatosis, Pnpla3 expression did not differ compared to low-fat fed mice. In HepG2 cells, Pnpla3 expression was reversibly suppressed by glucose depletion and increased by glucose refeeding, but unchanged by addition of insulin and glucagon. Several unsaturated fatty acids each significantly decreased Pnpla3 mRNA, similar to lipid emulsion in vivo. However, Pnpla3 knockdown in HepG2 cells did not alter total lipid content in high glucose- or oleic acid-treated cells. CONCLUSIONS Our results provide evidence that PNPLA3 expression is an early signal/signature of carbohydrate-induced lipogenesis, but its expression is not associated with steatosis per se. Under lipogenic conditions due to high-carbohydrate feeding, certain unsaturated fatty acids can effectively suppress both lipogenesis and PNPLA3 expression, both in vivo and in a hepatocyte cell line.
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Affiliation(s)
- Lei Hao
- Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA 16802 USA
| | - Kyoko Ito
- Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA 16802 USA
| | - Kuan-Hsun Huang
- Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA 16802 USA
| | - Sudathip Sae-tan
- Department of Food Science, The Pennsylvania State University, University Park, PA 16802 USA
| | - Joshua D Lambert
- Department of Food Science, The Pennsylvania State University, University Park, PA 16802 USA
| | - A Catharine Ross
- Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA 16802 USA; Center for Immunology and Infectious Disease, The Pennsylvania State University, University Park, PA 16802 USA.
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46
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La Merrill M, Karey E, Moshier E, Lindtner C, La Frano MR, Newman JW, Buettner C. Perinatal exposure of mice to the pesticide DDT impairs energy expenditure and metabolism in adult female offspring. PLoS One 2014; 9:e103337. [PMID: 25076055 PMCID: PMC4116186 DOI: 10.1371/journal.pone.0103337] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2014] [Accepted: 06/25/2014] [Indexed: 12/16/2022] Open
Abstract
Dichlorodiphenyltrichloroethane (DDT) has been used extensively to control malaria, typhus, body lice and bubonic plague worldwide, until countries began restricting its use in the 1970s. Its use in malaria control continues in some countries according to recommendation by the World Health Organization. Individuals exposed to elevated levels of DDT and its metabolite dichlorodiphenyldichloroethylene (DDE) have an increased prevalence of diabetes and insulin resistance. Here we hypothesize that perinatal exposure to DDT disrupts metabolic programming leading to impaired metabolism in adult offspring. To test this, we administered DDT to C57BL/6J mice from gestational day 11.5 to postnatal day 5 and studied their metabolic phenotype at several ages up to nine months. Perinatal DDT exposure reduced core body temperature, impaired cold tolerance, decreased energy expenditure, and produced a transient early-life increase in body fat in female offspring. When challenged with a high fat diet for 12 weeks in adulthood, female offspring perinatally exposed to DDT developed glucose intolerance, hyperinsulinemia, dyslipidemia, and altered bile acid metabolism. Perinatal DDT exposure combined with high fat feeding in adulthood further impaired thermogenesis as evidenced by reductions in core temperature and in the expression of numerous RNA that promote thermogenesis and substrate utilization in the brown adipose tissue of adult female mice. These observations suggest that perinatal DDT exposure impairs thermogenesis and the metabolism of carbohydrates and lipids which may increase susceptibility to the metabolic syndrome in adult female offspring.
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Affiliation(s)
- Michele La Merrill
- Department of Environmental Toxicology, University of California Davis, Davis, California, United States of America
- Department of Preventive Medicine, Mount Sinai School of Medicine, New York, New York, United States of America
- Metabolism Institute, Mount Sinai School of Medicine, New York, New York, United States of America
- * E-mail:
| | - Emma Karey
- Department of Environmental Toxicology, University of California Davis, Davis, California, United States of America
| | - Erin Moshier
- Department of Preventive Medicine, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Claudia Lindtner
- Metabolism Institute, Mount Sinai School of Medicine, New York, New York, United States of America
- Division of Endocrinology, Diabetes and Bone Disease, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Michael R. La Frano
- West Coast Metabolomic Center, University of California Davis, Davis, California, United States of America
- Department of Nutrition, University of California Davis, Davis, California, United States of America
| | - John W. Newman
- West Coast Metabolomic Center, University of California Davis, Davis, California, United States of America
- Department of Nutrition, University of California Davis, Davis, California, United States of America
- Obesity and Metabolism Research Unit, USDA-ARS-Western Human Nutrition Research Center, Davis, California, United States of America
| | - Christoph Buettner
- Metabolism Institute, Mount Sinai School of Medicine, New York, New York, United States of America
- Division of Endocrinology, Diabetes and Bone Disease, Mount Sinai School of Medicine, New York, New York, United States of America
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47
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Shen L, Cui A, Xue Y, Cui Y, Dong X, Gao Y, Yang H, Fang F, Chang Y. Hepatic differentiated embryo-chondrocyte-expressed gene 1 (Dec1) inhibits sterol regulatory element-binding protein-1c (Srebp-1c) expression and alleviates fatty liver phenotype. J Biol Chem 2014; 289:23332-42. [PMID: 24993831 DOI: 10.1074/jbc.m113.526343] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Hepatic steatosis, characterized by ectopic hepatic triglyceride accumulation, is considered as the early manifestation of non-alcoholic fatty liver diseases (NAFLD). Increased SREBP-1c level and activity contribute to excessive hepatic triglyceride accumulation in NAFLD patients; however, negative regulators of Srebp-1c are not well defined. In this study, we show that Dec1, a critical regulator of circadian rhythm, negatively regulates hepatic Srebp-1c expression. Hepatic Dec1 expression levels are markedly decreased in NAFLD mouse models. Restored Dec1 gene expression levels in NAFLD mouse livers decreased the expression of Srebp-1c and lipogenic genes, subsequently ameliorating the fatty liver phenotype. Conversely, knockdown of Dec1 expression by an adenovirus expressing Dec1-specific shRNA led to an increase in hepatic TG content in normal mouse livers. Correspondingly, expression levels of lipogenic genes, including Srebp-1c, Fas, and Acc, were increased in livers of mice with Dec1 knockdown. Moreover, a functional lipogenesis assay suggested that Dec1 overexpression repressed lipid synthesis in primary hepatocytes. Finally, a luciferase reporter gene assay indicates that DEC1 inhibits Srebp-1c gene transcription via the E-box mapped to the promoter region. Chromatin immunoprecipitation confirmed that DEC1 proteins bound to the identified E-box element. Our studies indicate that DEC1 is an important regulator of Srebp-1c expression and links circadian rhythm to hepatic lipogenesis. Activation of Dec1 can alleviate the nonalcoholic fatty liver phenotype.
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Affiliation(s)
- Lian Shen
- From the National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China and
| | - Anfang Cui
- the Biochemistry Department, Jining Medical University, Jining 272067, China
| | - Yuan Xue
- From the National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China and
| | - Ying Cui
- From the National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China and
| | - Xueyu Dong
- From the National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China and
| | - Yong Gao
- From the National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China and
| | - Hao Yang
- From the National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China and
| | - Fude Fang
- From the National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China and
| | - Yongsheng Chang
- From the National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China and
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Takaki A, Kawai D, Yamamoto K. Molecular mechanisms and new treatment strategies for non-alcoholic steatohepatitis (NASH). Int J Mol Sci 2014; 15:7352-79. [PMID: 24786095 PMCID: PMC4057677 DOI: 10.3390/ijms15057352] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Revised: 03/28/2014] [Accepted: 04/10/2014] [Indexed: 02/07/2023] Open
Abstract
Non-alcoholic steatohepatitis (NASH) is a severe form of non-alcoholic fatty liver disease (NAFLD), in which most patients exhibit non-progressive, non-alcoholic fatty liver (NAFL) attributable to simple steatosis. Multiple hits, including genetic differences, fat accumulation, insulin resistance and intestinal microbiota changes, account for the progression of NASH. NAFLD is strongly associated with obesity, which induces adipokine secretion, endoplasmic reticulum (ER) and oxidative stress at the cellular level, which in turn induces hepatic steatosis, inflammation and fibrosis. Among these factors, gut microbiota are acknowledged as having an important role in initiating this multifactorial disease. Oxidative stress is considered to be a key contributor in the progression from NAFL to NASH. Macrophage infiltration is apparent in NAFL and NASH, while T-cell infiltration is apparent in NASH. Although several clinical trials have shown that antioxidative therapy with vitamin E can effectively control hepatitis pathology in the short term, the long-term effects remain obscure and have often proved to be ineffective in many other diseases. Several long-term antioxidant protocols have failed to reduce mortality. New treatment modalities that incorporate current understanding of NAFLD molecular pathogenesis must be considered.
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Affiliation(s)
- Akinobu Takaki
- Department of Gastroenterology and Hepatology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan.
| | - Daisuke Kawai
- Department of Gastroenterology and Hepatology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan.
| | - Kazuhide Yamamoto
- Department of Gastroenterology and Hepatology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan.
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The PNPLA3 Ile148Met interacts with overweight and dietary intakes on fasting triglyceride levels. GENES AND NUTRITION 2014; 9:388. [PMID: 24563329 PMCID: PMC3968290 DOI: 10.1007/s12263-014-0388-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 02/12/2014] [Indexed: 12/31/2022]
Abstract
The Ile148Met (rs738409, G-allele) in the patatin-like phospholipase domain-containing protein 3 gene (PNPLA3) associates with liver fat content and may lead to loss-of-function (hydrolysis) or gain-of-function (CoA-dependent lysophosphatidic acid acyltransferase) defects. PNPLA3 is up-regulated by dietary carbohydrates, and interactions between rs738409 and carbohydrates, and sugar and ω6:ω3-polyunsaturated fatty acid (PUFA) ratio on hepatic fat accumulation have been reported. We examined interaction between rs738409 and overweight, and between rs738409 and dietary intakes (carbohydrates, sucrose and ω6:ω3-PUFA ratio), on fasting triglyceride levels. From the Malmo Diet and Cancer Study-Cardiovascular Cohort, 4,827 individuals without diabetes aged 58 ± 6 years, 2,346 with BMI ≤ 25 kg/m2 and 2,478 with BMI > 25 kg/m2, were included in cross-sectional analyses. Dietary data were collected by a modified diet history method. Overweight modified the association between rs738409 and fasting triglyceride levels (Pinteraction = 0.003). G-allele associated with lower triglycerides only among overweight individuals (P = 0.01). Nominally, significant interaction on triglyceride levels was observed between rs738409 and sucrose among normal-weight individuals (Pinteraction = 0.03). G-allele associated with lower triglycerides among overweight individuals in the lowest tertiles of carbohydrate and ω6:ω3-PUFA ratio (P = 0.04 and P = 0.001) and with higher triglycerides among normal-weight individuals in the highest tertile of sucrose (P = 0.001). We conclude that overweight and dietary sucrose may modify the association between rs738409 and fasting triglyceride levels.
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50
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Ruhanen H, Perttilä J, Hölttä-Vuori M, Zhou Y, Yki-Järvinen H, Ikonen E, Käkelä R, Olkkonen VM. PNPLA3 mediates hepatocyte triacylglycerol remodeling. J Lipid Res 2014; 55:739-46. [PMID: 24511104 DOI: 10.1194/jlr.m046607] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The I148M substitution in patatin-like phospholipase domain containing 3 (PNPLA3(I148M)) determines a genetic form of nonalcoholic fatty liver disease. To elucidate the mode of PNPLA3 action in human hepatocytes, we studied effects of WT PNPLA3 (PNPLA3(WT)) and PNPLA3(I148M) on HuH7 cell lipidome after [(13)C]glycerol labeling, cellular turnover of oleic acid labeled with 17 deuterium atoms ([D17]oleic acid) in triacylglycerols (TAGs), and subcellular distribution of the protein variants. PNPLA3(I148M) induced a net accumulation of unlabeled TAGs, but not newly synthesized total [(13)C]TAGs. Principal component analysis (PCA) revealed that both PNPLA3(WT) and PNPLA3(I148M) induced a relative enrichment of TAGs with saturated FAs or MUFAs, with concurrent enrichment of polyunsaturated phosphatidylcholines. PNPLA3(WT) associated in PCA with newly synthesized [(13)C]TAGs, particularly 52:1 and 50:1, while PNPLA3(I148M) associated with similar preexisting TAGs. PNPLA3(WT) overexpression resulted in increased [D17]oleic acid labeling of TAGs during 24 h, and after longer incubations their turnover was accelerated, effects not detected with PNPLA3(I148M). PNPLA3(I148M) localized more extensively to lipid droplets (LDs) than PNPLA3(WT), suggesting that the substitution alters distribution of PNPLA3 between LDs and endoplasmic reticulum/cytosol. This study reveals a function of PNPLA3 in FA-selective TAG remodeling, resulting in increased TAG saturation. A defect in TAG remodeling activity likely contributes to the TAG accumulation observed in cells expressing PNPLA3(I148M).
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Affiliation(s)
- Hanna Ruhanen
- Minerva Foundation Institute for Medical Research, Biomedicum 2U, FI-00290 Helsinki, Finland
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