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Sahin C, Melanson JR, Le Billan F, Magomedova L, Ferreira TAM, Oliveira AS, Pollock-Tahari E, Saikali MF, Cash SB, Woo M, Romeiro LAS, Cummins CL. A novel fatty acid mimetic with pan-PPAR partial agonist activity inhibits diet-induced obesity and metabolic dysfunction-associated steatotic liver disease. Mol Metab 2024; 85:101958. [PMID: 38763495 PMCID: PMC11170206 DOI: 10.1016/j.molmet.2024.101958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Revised: 05/09/2024] [Accepted: 05/13/2024] [Indexed: 05/21/2024] Open
Abstract
OBJECTIVE The prevalence of metabolic diseases is increasing globally at an alarming rate; thus, it is essential that effective, accessible, low-cost therapeutics are developed. Peroxisome proliferator-activated receptors (PPARs) are transcription factors that tightly regulate glucose homeostasis and lipid metabolism and are important drug targets for the treatment of type 2 diabetes and dyslipidemia. We previously identified LDT409, a fatty acid-like compound derived from cashew nut shell liquid, as a novel pan-active PPARα/γ/δ compound. Herein, we aimed to assess the efficacy of LDT409 in vivo and investigate the molecular mechanisms governing the actions of the fatty acid mimetic LDT409 in diet-induced obese mice. METHODS C57Bl/6 mice (6-11-month-old) were fed a chow or high fat diet (HFD) for 4 weeks; mice thereafter received once daily intraperitoneal injections of vehicle, 10 mg/kg Rosiglitazone, 40 mg/kg WY14643, or 40 mg/kg LDT409 for 18 days while continuing the HFD. During treatments, body weight, food intake, glucose and insulin tolerance, energy expenditure, and intestinal lipid absorption were measured. On day 18 of treatment, tissues and plasma were collected for histological, molecular, and biochemical analysis. RESULTS We found that treatment with LDT409 was effective at reversing HFD-induced obesity and associated metabolic abnormalities in mice. LDT409 lowered food intake and hyperlipidemia, while improving insulin tolerance. Despite being a substrate of both PPARα and PPARγ, LDT409 was crucial for promoting hepatic fatty acid oxidation and reducing hepatic steatosis in HFD-fed mice. We also highlighted a role for LDT409 in white and brown adipocytes in vitro and in vivo where it decreased fat accumulation, increased lipolysis, induced browning of WAT, and upregulated thermogenic gene Ucp1. Remarkably, LDT409 reversed HFD-induced weight gain back to chow-fed control levels. We determined that the LDT409-induced weight-loss was associated with a combination of increased energy expenditure (detectable before weight loss was apparent), decreased food intake, increased systemic fat utilization, and increased fecal lipid excretion in HFD-fed mice. CONCLUSIONS Collectively, LDT409 represents a fatty acid mimetic that generates a uniquely favorable metabolic response for the treatment of multiple abnormalities including obesity, dyslipidemia, metabolic dysfunction-associated steatotic liver disease, and diabetes. LDT409 is derived from a highly abundant natural product-based starting material and its development could be pursued as a therapeutic solution to the global metabolic health crisis.
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Affiliation(s)
- Cigdem Sahin
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON M5S 3M2, Canada
| | - Jenna-Rose Melanson
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON M5S 3M2, Canada
| | - Florian Le Billan
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON M5S 3M2, Canada
| | - Lilia Magomedova
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON M5S 3M2, Canada
| | - Thais A M Ferreira
- Department of Pharmacy, Faculty of Health Sciences, University of Brasilia, Brasilia, DF 71910-900, Brazil
| | - Andressa S Oliveira
- Department of Pharmacy, Faculty of Health Sciences, University of Brasilia, Brasilia, DF 71910-900, Brazil
| | - Evan Pollock-Tahari
- Toronto General Hospital Research Institute, University Health Network, Toronto, ON, M5G 2C4, Canada
| | - Michael F Saikali
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON M5S 3M2, Canada
| | - Sarah B Cash
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON M5S 3M2, Canada
| | - Minna Woo
- Toronto General Hospital Research Institute, University Health Network, Toronto, ON, M5G 2C4, Canada; Banting and Best Diabetes Centre, Toronto, ON, M5G 2C4, Canada
| | - Luiz A S Romeiro
- Department of Pharmacy, Faculty of Health Sciences, University of Brasilia, Brasilia, DF 71910-900, Brazil
| | - Carolyn L Cummins
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON M5S 3M2, Canada; Banting and Best Diabetes Centre, Toronto, ON, M5G 2C4, Canada.
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Liu H, Yokoyama F, Ishizuka S. Metabolic alterations of the gut-liver axis induced by cholic acid contribute to hepatic steatosis in rats. Biochim Biophys Acta Mol Cell Biol Lipids 2023; 1868:159319. [PMID: 37075973 DOI: 10.1016/j.bbalip.2023.159319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 03/24/2023] [Accepted: 04/07/2023] [Indexed: 04/21/2023]
Abstract
12α-Hydroxylated (12αOH) bile acids (BAs) selectively increase with high-fat diet intake. Dietary supplementation with cholic acid (CA) in rats is a possible strategy to reveal the causal link between 12αOH BAs and hepatic steatosis. The present study aimed to investigate the metabolic mechanism underlying the effect of 12αOH BAs on hepatic steatosis. Male WKAH rats were fed either a control (Ct) or CA-supplemented diet (0.5 g/kg). After the 12-week intervention, the CA diet elevated the 12αOH BA levels in the gut-liver axis. CA-fed rats showed greater hepatic lipid accumulation than in the Ct group, regardless of the dietary energy balance. Untargeted metabolomics suggested marked differences in the fecal metabolome of rats subjected to the CA diet compared with that of Ct, characterized by the depletion of fatty acids and enrichment of amino acids and amines. Moreover, the liver metabolome differed in the CA diet group, characterized by an alteration in redox-related pathways. The CA diet elevated nicotinamide adenine dinucleotide consumption owing to the activation of poly(ADP-ribose) polymerase 1, resulting in impaired peroxisome proliferator-activated receptor α signaling in the liver. The CA diet increased sedoheptulose 7-phosphate, and enhanced glucose-6-phosphate dehydrogenase activity, suggesting promotion of the pentose phosphate pathway that generates reducing equivalents. Integrated analysis of the gut-liver metabolomic data revealed the role of deoxycholic acid and its liver counterpart in mediating these metabolic alterations. These observations suggest that alterations in metabolites induced by 12αOH BAs in the gut-liver axis contribute to the enhancement of liver lipid accumulation.
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Affiliation(s)
- Hongxia Liu
- Division of Fundamental Agriscience Research, Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan
| | - Fumika Yokoyama
- Division of Fundamental Agriscience Research, Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan
| | - Satoshi Ishizuka
- Division of Fundamental Agriscience Research, Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan.
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Chandramohan K, Balan DJ, Devi KP, Nabavi SF, Reshadat S, Khayatkashani M, Mahmoodifar S, Filosa R, Amirkhalili N, Pishvaei S, Aval OS, Nabavi SM. Short interfering RNA in colorectal cancer: is it wise to shoot the messenger? Eur J Pharmacol 2023; 949:175699. [PMID: 37011722 DOI: 10.1016/j.ejphar.2023.175699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 03/23/2023] [Accepted: 03/28/2023] [Indexed: 04/03/2023]
Abstract
Colorectal cancer (CRC) is the third most common cancer and the leading cause of gastrointestinal cancer death. 90% of people diagnosed with colorectal cancer are over the age of 50; nevertheless, the illness is more aggressive among those detected at a younger age. Chemotherapy-based treatment has several adverse effects on both normal and malignant cells. The primary signaling pathways implicated in the advancement of CRC include hedgehog (Hh), janus kinase and signal transducer and activator of transcription (JAK/STAT), Wingless-related integration site (Wnt)/β-catenin, transforming growth factor-β (TNF-β), epidermal growth factor receptor (EGFR)/Mitogen-activated protein kinases (MAPK), phosphoinositide 3-kinase (PI3K), nuclear factor kappa B (NF-κB), and Notch. Loss of heterozygosity in tumor suppressor genes like adenomatous polyposis coli, as well as mutation or deletion of genes like p53 and Kirsten rat sarcoma viral oncogene (KRAS), are all responsible for the occurrence of CRC. Novel therapeutic targets linked to these signal-transduction cascades have been identified as a consequence of advances in small interfering RNA (siRNA) treatments. This study focuses on many innovative siRNA therapies and methodologies for delivering siRNA therapeutics to the malignant site safely and effectively for the treatment of CRC. Treatment of CRC using siRNA-associated nanoparticles (NPs) may inhibit the activity of oncogenes and MDR-related genes by targeting a range of signaling mechanisms. This study summarizes several siRNAs targeting signaling molecules, as well as the therapeutic approaches that might be employed to treat CRC in the future.
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Mandal A. The Focus on Core Genetic Factors That Regulate Hepatic Injury in Cattle Seems to be Important for the Dairy Sector’s Long-Term Development. Vet Med Sci 2022. [DOI: 10.5772/intechopen.108151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The cattle during the perinatal period, as well as malnutrition, generate oxidative stress which leads to high culling rates of calves after calving across the world. Although metabolic diseases have such a negative impact on the welfare and economic value of dairy cattle, that becomes a serious industrial concern across the world. According to research, genetic factors have a role or controlling fat deposition in the liver by influencing the biological processes of hepatic lipid metabolism, insulin resistance, gluconeogenesis, oxidative stress, endoplasmic reticulum stress, and inflammation, all of which contribute to hepatic damage. This review focuses on the critical regulatory mechanisms of VEGF, mTOR/AKT/p53, TNF-alpha, Nf-kb, interleukin, and antioxidants that regulate lipid peroxidation in the liver via direct or indirect pathways, suggesting that they could be a potential critical therapeutic target for hepatic disease.
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Zhao F, Chen J, Guo R, Zhu J, Gu W, Li S, Li J. Absolute quantitative lipidomics reveals lipids profiling in liver of mice with early-stage alcoholic liver disease. Nutr Metab (Lond) 2022; 19:42. [PMID: 35790996 PMCID: PMC9254412 DOI: 10.1186/s12986-022-00679-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 06/28/2022] [Indexed: 11/10/2022] Open
Abstract
Background Alcoholic liver disease (ALD) is one of the most prevalent chronic liver disease worldwide. Alcohol-induced alterations in hepatic lipids play an important role in ALD develpoment and progression. The present study aimed to thoroughly describe the changes of lipid profiling in liver of mice with early-stage alcoholic liver disease. Methods C57BL/6J male mice aged 7-week were randomized into alcohol-fed (AF) group and pair-fed control group (PF) (n = 10 per group). The early stage of ALD was induced with Lieber-DeCarli liquid diet. The lipids profiling was analyzed by absolute quantitative lipidomics with UHPLC-QTRAP-MS/MS. Results Alcohol intake significantly increased the levels of alanine aminotransferase (ALT) in plasma, and tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and triacylglycerols (TAG) levels in liver. Lipidomis analyses showed that 41 TAGs were up-regulated and 8 TAGs were down-regulated in response to alcohol intake. The 8 decreased TAGs were with more double bond, longer carbon chain length and mostly contained docosahexaenoic acid (C22:6n-3) and eicosapentaenoic acid (C20:5n-3), compared with the up-regulated TAGs. Furthermore, the down-regulated TAG(56:9)_FA20:5 was inversely associated with ALT and IL-6 levels. In addition, several altered lysophosphatidylcholines (LPC), lysophosphatidylethanolamines (LPE) and hexosylceramides (HCER) were all significantly decreased in response to alcohol consumption, especially HCer(18:1/22:0), with the top reduction among all the down-regulated lipids. Conclusions These findings suggest that not only the up-regulated lipids, alcohol-induced reduction in some specific lipids might also contribute to the ALD development, especially TAG(56:9)_FA20:5 and HCer(18:1/22:0). Their physiological functions and effects on ALD development warrants further investigation. Supplementary Information The online version contains supplementary material available at 10.1186/s12986-022-00679-z.
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Buerger AN, Parente CE, Harris JP, Watts EG, Wormington AM, Bisesi JH. Impacts of diethylhexyl phthalate and overfeeding on physical fitness and lipid mobilization in Danio rerio (zebrafish). CHEMOSPHERE 2022; 295:133703. [PMID: 35066078 DOI: 10.1016/j.chemosphere.2022.133703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 01/04/2022] [Accepted: 01/18/2022] [Indexed: 06/14/2023]
Abstract
As the prevalence of obesity has steadily increased on a global scale, research has shifted to explore potential contributors to this pandemic beyond overeating and lack of exercise. Environmental chemical contaminants, known as obesogens, alter metabolic processes and exacerbate the obese phenotype. Diethylhexyl phthalate (DEHP) is a common chemical plasticizer found in medical supplies, food packaging, and polyvinyl materials, and has been identified as a probable obesogen. This study investigated the hypothesis that co-exposure to DEHP and overfeeding would result in decreased lipid mobilization and physical fitness in Danio rerio (zebrafish). Four treatment groups were randomly assigned: Regular Fed (control, 10 mg/fish/day with 0 mg/kg DEHP), Overfed (20 mg/fish/day with 0 mg/kg DEHP), Regular Fed + DEHP (10 mg/fish/day with 3 mg/kg DEHP), Overfed + DEHP (20 mg/fish/day with 3 mg/kg DEHP). After 24 weeks, swim tunnel assays were conducted on half of the zebrafish from each treatment to measure critical swimming speeds (Ucrit); the other fish were euthanized without swimming. Body mass index (BMI) was measured, and tissues were collected for blood lipid characterization and gene expression analyses. Co-exposure to DEHP and overfeeding decreased swim performance as measured by Ucrit. While no differences in blood lipids were observed with DEHP exposure, differential expression of genes related to lipid metabolism and utilization in the gastrointestinal and liver tissue suggests alterations in metabolism and lipid packaging, which may impact utilization and ability to mobilize lipid reserves during physical activity following chronic exposures.
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Affiliation(s)
- Amanda N Buerger
- Department of Environmental and Global Health, University of Florida, Gainesville, FL, USA; Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL, USA
| | - Caitlyn E Parente
- Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL, USA; Department of Chemistry, University of Florida, Gainesville, FL, USA
| | - Jason P Harris
- Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL, USA; Department of Biology, University of Florida, Gainesville, FL, USA
| | - Emily G Watts
- Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL, USA; Department of Chemistry, University of Florida, Gainesville, FL, USA
| | - Alexis M Wormington
- Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL, USA
| | - Joseph H Bisesi
- Department of Environmental and Global Health, University of Florida, Gainesville, FL, USA; Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL, USA.
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Rehman A, Mehta KJ. Betaine in ameliorating alcohol-induced hepatic steatosis. Eur J Nutr 2021; 61:1167-1176. [PMID: 34817678 PMCID: PMC8921017 DOI: 10.1007/s00394-021-02738-2] [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: 09/07/2021] [Accepted: 11/03/2021] [Indexed: 01/15/2023]
Abstract
Alcohol-associated liver disease (AALD) is one of most common chronic liver diseases. Hepatic steatosis is the earliest stage in AALD pathological spectrum, reversible by alcohol abstinence. Untreated steatosis can progress to steatohepatitis, fibrosis and/or cirrhosis. Considering the difficulties in achieving complete abstinence, challenges in disease reversal at advanced stages, high costs of AALD management and lack of standardised prescribed medications for treatment, it is essential to explore low-cost natural compounds that can target AALD at an early stage and halt or decelerate disease progression. Betaine is a non-hazardous naturally occurring nutrient. Here, we address the mechanisms of alcohol-induced hepatic steatosis, the role of betaine in reversing the effects i.e., its action against hepatic steatosis in animal models and humans, and the associated cellular and molecular processes. Accordingly, the review discusses how betaine restores the alcohol-induced reduction in methylation potential by elevating the levels of S-adenosylmethionine and methionine. It details how betaine reinstates alcohol-induced alterations in the expressions and/or activities of protein phosphtase-2A, FOXO1, PPAR-α, AMPK, SREBP-1c, fatty acid synthase, diacylglycerol transferase-2, adiponectin and nitric oxide. Interrelationships between these factors in preventing de novo lipogenesis, reducing hepatic uptake of adipose-tissue-derived free fatty acids, promoting VLDL synthesis and secretion, and restoring β-oxidation of fatty acids to attenuate hepatic triglyceride accumulation are elaborated. Despite its therapeutic potential, very few clinical trials have examined betaine’s effect on alcohol-induced hepatic lipid accumulation. This review will provide further confidence to conduct randomised control trials to enable maximum utilisation of betaine’s remedial properties to treat alcohol-induced hepatic steatosis.
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Affiliation(s)
- Aisha Rehman
- Faculty of Life Sciences and Medicine, King's College London, London, UK
| | - Kosha J Mehta
- Centre for Education, Faculty of Life Sciences and Medicine, King's College London, London, UK.
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Matsumoto Y, Fujita S, Yamagishi A, Shirai T, Maeda Y, Suzuki T, Kobayashi KI, Inoue J, Yamamoto Y. Brown Rice Inhibits Development of Nonalcoholic Fatty Liver Disease in Obese Zucker (fa/fa) Rats by Increasing Lipid Oxidation Via Activation of Retinoic Acid Synthesis. J Nutr 2021; 151:2705-2713. [PMID: 34224565 DOI: 10.1093/jn/nxab188] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 02/24/2021] [Accepted: 05/17/2021] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND White rice and its unrefined form, brown rice, contain numerous compounds that are beneficial to human health. However, the starch content of rice can contribute to obesity, a main risk factor for nonalcoholic fatty liver disease (NAFLD). OBJECTIVES We investigated the effect of rice consumption on NAFLD and its underlying molecular mechanism. METHODS We randomly divided 7-week-old male obese Zucker (fa/fa) rats, an animal model of NAFLD, into 3 groups (n = 10 each) fed 1 of 3 diets for 10 weeks: a control diet (Cont; AIN-93G diet; 53% cornstarch), a white rice diet (WR; AIN-93G diet with cornstarch replaced with white rice powder), or a brown rice diet (BR; AIN-93G diet with cornstarch replaced with brown rice powder). Liver fat accumulation and gene expression related to lipid and vitamin A metabolisms, including retinoic acid (RA) signaling, were analyzed. RESULTS Hepatic lipid values were significantly decreased in the BR group compared with the Cont group, by 0.4-fold (P < 0.05). The expression of genes related to hepatic fatty acid oxidation, such as carnitine palmitoyltransferase 2, was approximately 2.1-fold higher in the BR group than the Cont group (P < 0.05). The expression of peroxisomal acyl-coenzyme A oxidase 1 and acyl-CoA dehydrogenase medium chain was also significantly increased, by 1.6-fold, in the BR group compared with the Cont group (P < 0.05). The expression of VLDL-secretion-related genes, such as microsomal triglyceride transfer protein, was also significantly higher in the BR group (2.4-fold; P < 0.05). Furthermore, aldehyde dehydrogenase 1 family member A1, an RA synthase gene, was 2-fold higher in the BR group than the Cont group (P < 0.05). CONCLUSIONS Brown rice prevented development of NAFLD in obese Zucker (fa/fa) rats. The beneficial effects of pregelatinized rice on NAFLD could be manifested as increased fatty acid oxidation and VLDL secretion, which are regulated by RA signaling.
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Affiliation(s)
- Yu Matsumoto
- Department of Agricultural Chemistry, Faculty of Applied Bioscience, Tokyo University of Agriculture, Tokyo, Japan
| | - Saya Fujita
- Department of Agricultural Chemistry, Faculty of Applied Bioscience, Tokyo University of Agriculture, Tokyo, Japan
| | - Ayano Yamagishi
- Department of Agricultural Chemistry, Faculty of Applied Bioscience, Tokyo University of Agriculture, Tokyo, Japan
| | - Tomomi Shirai
- Department of Agricultural Chemistry, Faculty of Applied Bioscience, Tokyo University of Agriculture, Tokyo, Japan
| | | | - Tsukasa Suzuki
- Department of Agricultural Chemistry, Faculty of Applied Bioscience, Tokyo University of Agriculture, Tokyo, Japan
| | - Ken-Ichi Kobayashi
- Department of Agricultural Chemistry, Faculty of Applied Bioscience, Tokyo University of Agriculture, Tokyo, Japan.,Department of Foods and Human Nutrition, Faculty of Human Living Sciences Notre Dame Seishin University, Okayama, Japan
| | - Jun Inoue
- Department of Agricultural Chemistry, Faculty of Applied Bioscience, Tokyo University of Agriculture, Tokyo, Japan
| | - Yuji Yamamoto
- Department of Agricultural Chemistry, Faculty of Applied Bioscience, Tokyo University of Agriculture, Tokyo, Japan
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Li P, Chen X, Dong M, Luo J, Lu S, Chen M, Zhang Y, Zhou H, Jiang H. Gut inflammation exacerbates high-fat diet induced steatosis by suppressing VLDL-TG secretion through HNF4α pathway. Free Radic Biol Med 2021; 172:459-469. [PMID: 34186207 DOI: 10.1016/j.freeradbiomed.2021.06.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 06/20/2021] [Accepted: 06/23/2021] [Indexed: 12/11/2022]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is increasingly identified in inflammatory bowel disease (IBD) patients with unclear etiology. In the current study we assessed the contribution of colonic inflammation to NAFLD development and the underlying mechanism in a mouse model for IBD. Our results showed that dextran sulfate sodium (DSS)-induced gut colitis directly led to hepatic inflammation, injury and further exacerbated hepatic steatosis caused by high fat diet (HF) feeding. The essential genes assessment, hepatic metabolic analysis and triglyceride-rich very low-density lipoprotein (VLDL-TG) secretion assays revealed a higher β-oxidation of fatty acids (FAs) but impaired VLDL-TG secretion in liver of DSS-treated mice. Disruption of the intestinal barrier by DSS promoted liver inflammation, which strongly suppressed hepatic VLDL-TG secretion and further aggravated HF-induced VLDL-TG secretion impairment through down-regulation of apolipoprotein B (APOB), hence promoting the storage of triglycerides (TG) in the liver. Inflammation induced by mixed proinflammatory cytokines or LPS obviously inhibited the expression of microsomal triglyceride transfer protein (MTP) and APOB expression and subsequently increased TG content via the suppression of HNF4α in mouse primary hepatocytes. In addition, the downregulation of MTP and APOB by proinflammatory cytokines was also rescued through activating Hnf4α by cortisol. Altogether, our results demonstrated that chronic inflammation exacerbated hepatic steatosis by inhibiting the secreting of hepatic VLDL-TG through HNF4α pathway, suggesting that restoring hepatic VLDL-TG secretion may be a novel strategy for treatment of NAFLD in IBD.
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Affiliation(s)
- Ping Li
- Laboratory of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Xiu Chen
- Laboratory of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Minlei Dong
- Laboratory of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Jun Luo
- Laboratory of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Shuanghui Lu
- Laboratory of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Mingyang Chen
- Laboratory of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Yingqiong Zhang
- Laboratory of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Hui Zhou
- Laboratory of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Huidi Jiang
- Laboratory of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China.
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Fang W, Chen Q, Cui K, Chen Q, Li X, Xu N, Mai K, Ai Q. Lipid overload impairs hepatic VLDL secretion via oxidative stress-mediated PKCδ-HNF4α-MTP pathway in large yellow croaker (Larimichthys crocea). Free Radic Biol Med 2021; 172:213-225. [PMID: 34116177 DOI: 10.1016/j.freeradbiomed.2021.06.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 05/30/2021] [Accepted: 06/02/2021] [Indexed: 02/08/2023]
Abstract
Lipid overload-induced hepatic steatosis is a major public health problem worldwide. However, the potential molecular mechanism is not completely understood. Herein, we found that high-fat diet (HFD) or oleic acid (OA) treatment induced oxidative stress which prevented the entry of hepatocyte nuclear factor 4 alpha (HNF4α) into the nucleus by activating protein kinase C delta (PKCδ) in vivo and in vitro in large yellow croaker (Larimichthys crocea). This reduced the level of microsomal triglyceride transfer protein (MTP) transcription, resulting in the impaired secretion of very-low-density lipoprotein (VLDL) and the abnormal accumulation of triglyceride (TG) in hepatocytes. Meanwhile, the detrimental effects induced by lipid overload could be partly alleviated by pretreating hepatocytes with Go6983 (PKCδ inhibitor) or N-acetylcysteine (NAC, reactive oxygen species (ROS) scavenger). In conclusion, for the first time, we revealed that lipid overload impaired hepatic VLDL secretion via oxidative stress-mediated PKCδ-HNF4α-MTP pathway in fish. This study may provide critical insights into potential intervention strategies against lipid overload-induced hepatic steatosis of fish and human beings.
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Affiliation(s)
- Wei Fang
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, People's Republic of China
| | - Qiuchi Chen
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, People's Republic of China
| | - Kun Cui
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, People's Republic of China
| | - Qiang Chen
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, People's Republic of China
| | - Xueshan Li
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, People's Republic of China
| | - Ning Xu
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, People's Republic of China
| | - Kangsen Mai
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, People's Republic of China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, 1 Wenhai Road, 266237, Qingdao, Shandong, People's Republic of China
| | - Qinghui Ai
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, People's Republic of China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, 1 Wenhai Road, 266237, Qingdao, Shandong, People's Republic of China.
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Zhu W, Chang L, Shu G, Wang B, Jiang JP. Fatter or stronger: Resource allocation strategy and the underlying metabolic mechanisms in amphibian tadpoles. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS 2021; 38:100825. [PMID: 33770735 DOI: 10.1016/j.cbd.2021.100825] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 03/11/2021] [Accepted: 03/14/2021] [Indexed: 12/24/2022]
Abstract
The allocation of resources between storage and somatic growth is an essential physiological phenomenon in animals. Allocation mechanisms have broad theoretical and applied implications. The real-time resource allocation patterns in animals remain to be elucidated, and there is limited understanding of the metabolic mechanisms. We investigated the resource allocation strategy of Rana omeimontis tadpoles. Their ontogenetic fat accumulation began when body weight increased to 30-50 mg, at which time storage had a high priority in resource allocation. Beyond this weight range, somatic growth accelerated but storage investment was maintained, resulting in a positive correlation between body fat index and body weight at the population level. This pattern could be explained by assuming a positive relationship between storage abundance and growth investment, and this was supported by the prioritized increment of body fat to body weight when tadpoles were provided with increased food. At the metabolic level, hepatic fat accumulation was accompanied by upregulated utilization of fat storage, and the tadpoles presented lipid-based energy metabolism. Activating the mobilization of hepatic fat storage promoted somatic growth. In short, the liver is like a reservoir with valves that regulate energy flow for downstream developmental processes. These results provide novel mechanistic insights into resource allocation.
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Affiliation(s)
- Wei Zhu
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization, Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chengdu 610041, China
| | - Liming Chang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization, Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chengdu 610041, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Guocheng Shu
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization, Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chengdu 610041, China; Yibin University, Yibin, Sichuan 644000, China
| | - Bin Wang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization, Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chengdu 610041, China.
| | - Jian-Ping Jiang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization, Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chengdu 610041, China.
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12
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Dungubat E, Watabe S, Togashi-Kumagai A, Watanabe M, Kobayashi Y, Harada N, Yamaji R, Fukusato T, Lodon G, Sevjid B, Takahashi Y. Effects of Caffeine and Chlorogenic Acid on Nonalcoholic Steatohepatitis in Mice Induced by Choline-Deficient, L-Amino Acid-Defined, High-Fat Diet. Nutrients 2020; 12:nu12123886. [PMID: 33353230 PMCID: PMC7767129 DOI: 10.3390/nu12123886] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 12/14/2020] [Accepted: 12/15/2020] [Indexed: 12/14/2022] Open
Abstract
Several recent experimental studies have investigated the effects of caffeine and chlorogenic acid (CGA), representative ingredients of coffee, on nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH). However, the results are conflicting, and their effects are yet to be clarified. In the present study, we examined the effects of caffeine and CGA on choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD)-fed mice, relatively new model mice of NASH. Seven-week-old male C57BL/6J mice were divided into the following groups: Control diet (control), CDAHFD (CDAHFD), CDAHFD supplemented with 0.05% (w/w) caffeine (caffeine), and CDAHFD supplemented with 0.1% (w/w) CGA (CGA). After seven weeks, the mice were killed and serum biochemical, histopathological, and molecular analyses were performed. Serum alanine aminotransferase (ALT) levels were significantly higher in the caffeine and CGA groups than in the CDAHFD group. On image analysis, the prevalence of Oil red O-positive areas (reflecting steatosis) was significantly higher in the caffeine group than in the CDAHFD group, and that of CD45R-positive areas (reflecting lymphocytic infiltration) in the hepatic lobule was significantly higher in the caffeine and CGA groups than in the CDAHFD group. Hepatic expression of interleukin (IL)-6 mRNA was higher in the caffeine and CGA groups than in the CDAHFD group, and the difference was statistically significant for the caffeine group. In conclusion, in the present study, caffeine and CGA significantly worsened the markers of liver cell injury, inflammation, and/or steatosis in NASH lesions in mice.
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Affiliation(s)
- Erdenetsogt Dungubat
- Department of Pathology, School of Medicine, International University of Health and Welfare, Narita, Chiba 286-8686, Japan;
- Department of Pathology, School of Biomedicine, Mongolian National University of Medical Sciences, Ulaanbaatar 14210, Mongolia
| | - Shiori Watabe
- Department of Pathology, Teikyo University School of Medicine, Tokyo 173-8605, Japan; (S.W.); (A.T.-K.); (M.W.)
| | - Arisa Togashi-Kumagai
- Department of Pathology, Teikyo University School of Medicine, Tokyo 173-8605, Japan; (S.W.); (A.T.-K.); (M.W.)
| | - Masato Watanabe
- Department of Pathology, Teikyo University School of Medicine, Tokyo 173-8605, Japan; (S.W.); (A.T.-K.); (M.W.)
| | - Yasuyuki Kobayashi
- Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan; (Y.K.); (N.H.); (R.Y.)
| | - Naoki Harada
- Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan; (Y.K.); (N.H.); (R.Y.)
| | - Ryoichi Yamaji
- Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan; (Y.K.); (N.H.); (R.Y.)
| | - Toshio Fukusato
- General Medical Education and Research Center, Teikyo University, Tokyo 173-8605, Japan;
| | - Galtsog Lodon
- Department of Pathology, School of Medicine, Ach Medical University, Ulaanbaatar 18080, Mongolia;
| | - Badamjav Sevjid
- Department of Gastroenterology, School of Medicine, Mongolian National University of Medical Sciences, Ulaanbaatar 14210, Mongolia;
| | - Yoshihisa Takahashi
- Department of Pathology, School of Medicine, International University of Health and Welfare, Narita, Chiba 286-8686, Japan;
- Correspondence: ; Tel.: +81-(476)-20-7701
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13
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Zhu W, Chang L, Zhao T, Wang B, Jiang J. Remarkable metabolic reorganization and altered metabolic requirements in frog metamorphic climax. Front Zool 2020; 17:30. [PMID: 33062031 PMCID: PMC7542913 DOI: 10.1186/s12983-020-00378-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 09/18/2020] [Indexed: 02/07/2023] Open
Abstract
Background Metamorphic climax is the crucial stage of amphibian metamorphosis responsible for the morphological and functional changes necessary for transition to a terrestrial habitat. This developmental period is sensitive to environmental changes and pollution. Understanding its metabolic basis and requirements is significant for ecological and toxicological research. Rana omeimontis tadpoles are a useful model for investigating this stage as their liver is involved in both metabolic regulation and fat storage. Results We used a combined approach of transcriptomics and metabolomics to study the metabolic reorganization during natural and T3-driven metamorphic climax in the liver and tail of Rana omeimontis tadpoles. The metabolic flux from the apoptotic tail replaced hepatic fat storage as metabolic fuel, resulting in increased hepatic amino acid and fat levels. In the liver, amino acid catabolism (transamination and urea cycle) was upregulated along with energy metabolism (TCA cycle and oxidative phosphorylation), while the carbohydrate and lipid catabolism (glycolysis, pentose phosphate pathway (PPP), and β-oxidation) decreased. The hepatic glycogen phosphorylation and gluconeogenesis were upregulated, and the carbohydrate flux was used for synthesis of glycan units (e.g., UDP-glucuronate). In the tail, glycolysis, β-oxidation, and transamination were all downregulated, accompanied by synchronous downregulation of energy production and consumption. Glycogenolysis was maintained in the tail, and the carbohydrate flux likely flowed into both PPP and the synthesis of glycan units (e.g., UDP-glucuronate and UDP-glucosamine). Fatty acid elongation and desaturation, as well as the synthesis of bioactive lipid (e.g., prostaglandins) were encouraged in the tail during metamorphic climax. Protein synthesis was downregulated in both the liver and tail. The significance of these metabolic adjustments and their potential regulation mechanism are discussed. Conclusion The energic strategy and anabolic requirements during metamorphic climax were revealed at the molecular level. Amino acid made an increased contribution to energy metabolism during metamorphic climax. Carbohydrate anabolism was essential for the body construction of the froglets. The tail was critical in anabolism including synthesizing bioactive metabolites. These findings increase our understanding of amphibian metamorphosis and provide background information for ecological, evolutionary, conservation, and developmental studies of amphibians.
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Affiliation(s)
- Wei Zhu
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, No.9, Section4, South Renmin Road, Chengdu, 610041 Sichuan China
| | - Liming Chang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, No.9, Section4, South Renmin Road, Chengdu, 610041 Sichuan China.,University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Tian Zhao
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, No.9, Section4, South Renmin Road, Chengdu, 610041 Sichuan China
| | - Bin Wang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, No.9, Section4, South Renmin Road, Chengdu, 610041 Sichuan China
| | - Jianping Jiang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, No.9, Section4, South Renmin Road, Chengdu, 610041 Sichuan China
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14
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Gao Y, Zhang S, Li J, Zhao J, Xiao Q, Zhu Y, Zhang J, Huang W. Effect and mechanism of ginsenoside Rg1-regulating hepatic steatosis in HepG2 cells induced by free fatty acid. Biosci Biotechnol Biochem 2020; 84:2228-2240. [PMID: 32654591 DOI: 10.1080/09168451.2020.1793293] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Ginsenoside Rg1 (G-Rg1) is a bioactive phytochemical that has been found to be beneficial for the treatment of several diseases including nonalcoholic fatty liver disease (NAFLD). But there is a lack of literature reporting the effect of G-Rg1 on lipid metabolism balance in NAFLD. We investigated the effect and mechanism of G-Rg1 on lipid metabolism in vitro. We found that G-Rg1 decreased the levels of TG, TC, and MDA, and increased activity of SOD. Results of RT-PCR and western blotting showed that supplementation with G-Rg1 downregulated the expression of PPAR γ, FABP1, FATP2/5, CD36, SREBP1 c, and FASN, while the expression of PPAR ɑ, CPT1, ACOX1, MTTP, and ApoB100 was upregulated, after induction by a free fatty acid. Taken together, we conclude that G-Rg1 inhibits lipid synthesis and lipid uptake, and enhances lipid oxidation and lipid export to reduce hepatic steatosis of HepG2 cells by regulating PPAR ɑ and PPAR γ expression.
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Affiliation(s)
- Yue Gao
- Chongqing Key Laboratory of Infectious Diseases and Parasitic Diseases, Department of Infectious Diseases, The First Affiliated Hospital of Chongqing Medical University , Chongqing, China
| | - Shujun Zhang
- Chongqing Key Laboratory of Infectious Diseases and Parasitic Diseases, Department of Infectious Diseases, The First Affiliated Hospital of Chongqing Medical University , Chongqing, China
| | - Jiajun Li
- Chongqing Key Laboratory of Infectious Diseases and Parasitic Diseases, Department of Infectious Diseases, The First Affiliated Hospital of Chongqing Medical University , Chongqing, China
| | - Jinqiu Zhao
- Chongqing Key Laboratory of Infectious Diseases and Parasitic Diseases, Department of Infectious Diseases, The First Affiliated Hospital of Chongqing Medical University , Chongqing, China
| | - Qing Xiao
- Chongqing Key Laboratory of Infectious Diseases and Parasitic Diseases, Department of Infectious Diseases, The First Affiliated Hospital of Chongqing Medical University , Chongqing, China
| | - Yali Zhu
- Chongqing Key Laboratory of Infectious Diseases and Parasitic Diseases, Department of Infectious Diseases, The First Affiliated Hospital of Chongqing Medical University , Chongqing, China
| | - Jia Zhang
- Chongqing Key Laboratory of Infectious Diseases and Parasitic Diseases, Department of Infectious Diseases, The First Affiliated Hospital of Chongqing Medical University , Chongqing, China
| | - Wenxiang Huang
- Chongqing Key Laboratory of Infectious Diseases and Parasitic Diseases, Department of Infectious Diseases, The First Affiliated Hospital of Chongqing Medical University , Chongqing, China
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15
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Iqbal J, Mascareno E, Chua S, Hussain MM. Leptin-mediated differential regulation of microsomal triglyceride transfer protein in the intestine and liver affects plasma lipids. J Biol Chem 2020; 295:4101-4113. [PMID: 32047110 PMCID: PMC7105304 DOI: 10.1074/jbc.ra119.011881] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 02/06/2020] [Indexed: 11/06/2022] Open
Abstract
The hormone leptin regulates fat storage and metabolism by signaling through the brain and peripheral tissues. Lipids delivered to peripheral tissues originate mostly from the intestine and liver via synthesis and secretion of apolipoprotein B (apoB)-containing lipoproteins. An intracellular chaperone, microsomal triglyceride transfer protein (MTP), is required for the biosynthesis of these lipoproteins, and its regulation determines fat mobilization to different tissues. Using cell culture and animal models, here we sought to identify the effects of leptin on MTP expression in the intestine and liver. Leptin decreased MTP expression in differentiated intestinal Caco-2 cells, but increased expression in hepatic Huh7 cells. Similarly, acute and chronic leptin treatment of chow diet-fed WT mice decreased MTP expression in the intestine, increased it in the liver, and lowered plasma triglyceride levels. These leptin effects required the presence of leptin receptors (LEPRs). Further experiments also suggested that leptin interacted with long-form LEPR (ObRb), highly expressed in the intestine, to down-regulate MTP. In contrast, in the liver, leptin interacted with short-form LEPR (ObRa) to increase MTP expression. Mechanistic experiments disclosed that leptin activates signal transducer and activator of transcription 3 (STAT3) and mitogen-activated protein kinase (MAPK) signaling pathways in intestinal and hepatic cells, respectively, and thereby regulates divergent MTP expression. Our results also indicated that leptin-mediated MTP regulation in the intestine affects plasma lipid levels. In summary, our findings suggest that leptin regulates MTP expression differentially by engaging with different LEPR types and activating distinct signaling pathways in intestinal and hepatic cells.
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Affiliation(s)
- Jahangir Iqbal
- Department of Cell Biology, SUNY Downstate Medical Center, Brooklyn, New York 11203; King Abdullah International Medical Research Center, King Saud Bin Abdulaziz University for Health Sciences, Eastern Region, Ministry of National Guard Health Affairs, Al Ahsa 31982, Saudi Arabia.
| | - Eduardo Mascareno
- Department of Cell Biology, SUNY Downstate Medical Center, Brooklyn, New York 11203
| | - Streamson Chua
- Department of Medicine and Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461
| | - M Mahmood Hussain
- Department of Cell Biology, SUNY Downstate Medical Center, Brooklyn, New York 11203; Department of Foundations of Medicine, NYU Long Island School of Medicine and Diabetes and Obesity Research Center, NYU Winthrop Research Institute, Mineola, New York 11501; Veterans Affairs New York Harbor Healthcare System, Brooklyn, New York 11209.
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16
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Jeon S, Carr R. Alcohol effects on hepatic lipid metabolism. J Lipid Res 2020; 61:470-479. [PMID: 32029510 DOI: 10.1194/jlr.r119000547] [Citation(s) in RCA: 115] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 01/28/2020] [Indexed: 12/16/2022] Open
Abstract
Alcoholic liver disease (ALD) is the most prevalent type of chronic liver disease with significant morbidity and mortality worldwide. ALD begins with simple hepatic steatosis and progresses to alcoholic steatohepatitis, fibrosis, and cirrhosis. The severity of hepatic steatosis is highly associated with the development of later stages of ALD. This review explores the disturbances of alcohol-induced hepatic lipid metabolism through altered hepatic lipid uptake, de novo lipid synthesis, fatty acid oxidation, hepatic lipid export, and lipid droplet formation and catabolism. In addition, we review emerging data on the contributions of genetics and bioactive lipid metabolism in alcohol-induced hepatic lipid accumulation.
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Affiliation(s)
- Sookyoung Jeon
- Division of Gastroenterology, University of Pennsylvania, Philadelphia, PA
| | - Rotonya Carr
- Division of Gastroenterology, University of Pennsylvania, Philadelphia, PA
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17
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Pan X, Schwartz GJ, Hussain MM. Oleoylethanolamide differentially regulates glycerolipid synthesis and lipoprotein secretion in intestine and liver. J Lipid Res 2018; 59:2349-2359. [PMID: 30369486 DOI: 10.1194/jlr.m089250] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 10/26/2018] [Indexed: 01/13/2023] Open
Abstract
Dietary fat absorption takes place in the intestine, and the liver mobilizes endogenous fat to other tissues by synthesizing lipoproteins that require apoB and microsomal triglyceride transfer protein (MTP). Dietary fat triggers the synthesis of oleoylethanolamide (OEA), a regulatory fatty acid that signals satiety to reduce food intake mainly by enhancing neural PPARα activity, in enterocytes. We explored OEA's roles in the assembly of lipoproteins in WT and Ppara -/- mouse enterocytes and hepatocytes, Caco-2 cells, and human liver-derived cells. In differentiated Caco-2 cells, OEA increased synthesis and secretion of triacylglycerols, apoB secretion in chylomicrons, and MTP expression in a dose-dependent manner. OEA also increased MTP activity and triacylglycerol secretion in WT and knockout primary enterocytes. In contrast to its intestinal cell effects, OEA reduced synthesis and secretion of triacylglycerols, apoB secretion, and MTP expression and activity in human hepatoma Huh-7 and HepG2 cells. Also, OEA reduced MTP expression and triacylglycerol secretion in WT, but not knockout, primary hepatocytes. These studies indicate differential effects of OEA on lipid synthesis and lipoprotein assembly: in enterocytes, OEA augments glycerolipid synthesis and lipoprotein assembly independent of PPARα. Conversely, in hepatocytes, OEA reduces MTP expression, glycerolipid synthesis, and lipoprotein secretion through PPARα-dependent mechanisms.
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Affiliation(s)
- Xiaoyue Pan
- Department of Cell Biology, State University of New York Downstate Medical Center, Brooklyn, NY .,Diabetes and Obesity Research Center, New York University Winthrop Hospital, Mineola, NY
| | - Gary J Schwartz
- Departments of Medicine and Neuroscience, Albert Einstein College of Medicine, Bronx, NY
| | - M Mahmood Hussain
- Department of Cell Biology, State University of New York Downstate Medical Center, Brooklyn, NY .,Diabetes and Obesity Research Center, New York University Winthrop Hospital, Mineola, NY.,Veterans Affairs New York Harbor Healthcare System, Brooklyn, NY
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18
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Ipsen DH, Lykkesfeldt J, Tveden-Nyborg P. Molecular mechanisms of hepatic lipid accumulation in non-alcoholic fatty liver disease. Cell Mol Life Sci 2018; 75:3313-3327. [PMID: 29936596 PMCID: PMC6105174 DOI: 10.1007/s00018-018-2860-6] [Citation(s) in RCA: 740] [Impact Index Per Article: 123.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 06/18/2018] [Accepted: 06/20/2018] [Indexed: 12/17/2022]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is currently the world's most common liver disease, estimated to affect up to one-fourth of the population. Hallmarked by hepatic steatosis, NAFLD is associated with a multitude of detrimental effects and increased mortality. This narrative review investigates the molecular mechanisms of hepatic steatosis in NAFLD, focusing on the four major pathways contributing to lipid homeostasis in the liver. Hepatic steatosis is a consequence of lipid acquisition exceeding lipid disposal, i.e., the uptake of fatty acids and de novo lipogenesis surpassing fatty acid oxidation and export. In NAFLD, hepatic uptake and de novo lipogenesis are increased, while a compensatory enhancement of fatty acid oxidation is insufficient in normalizing lipid levels and may even promote cellular damage and disease progression by inducing oxidative stress, especially with compromised mitochondrial function and increased oxidation in peroxisomes and cytochromes. While lipid export initially increases, it plateaus and may even decrease with disease progression, sustaining the accumulation of lipids. Fueled by lipo-apoptosis, hepatic steatosis leads to systemic metabolic disarray that adversely affects multiple organs, placing abnormal lipid metabolism associated with NAFLD in close relation to many of the current life-style-related diseases.
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Affiliation(s)
- David Højland Ipsen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Ridebanevej 9, 1870, Frederiksberg C, Denmark
| | - Jens Lykkesfeldt
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Ridebanevej 9, 1870, Frederiksberg C, Denmark
| | - Pernille Tveden-Nyborg
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Ridebanevej 9, 1870, Frederiksberg C, Denmark.
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19
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Lee J, Hong SW, Kwon H, Park SE, Rhee EJ, Park CY, Oh KW, Park SW, Lee WY. Exendin-4 improves ER stress-induced lipid accumulation and regulates lipin-1 signaling in HepG2 cells. Cell Stress Chaperones 2018; 23:629-638. [PMID: 29934713 PMCID: PMC6045528 DOI: 10.1007/s12192-017-0872-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Revised: 12/20/2017] [Accepted: 12/25/2017] [Indexed: 12/12/2022] Open
Abstract
Lipin-1 performs dual function during lipid metabolism, i.e., it functions as a transcriptional coactivator and as a phosphatidate phosphatase during triglyceride biosynthesis. We investigated whether exendin-4 prevented endoplasmic reticulum (ER) stress-induced hepatic steatosis and whether the protective effects of exendin-4 were associated with lipin-1 signaling. Tunicamycin and thapsigargin, ER stress inducers, increased triglycerides (TG) content and expression of genes encoding lipid droplet surface proteins. Exendin-4 decreased the expression of ER stress markers phosphorylated PKR like ER kinase (PERK), phosphorylated inositol-requiring enzyme 1 alpha (IRE1α), and glucose-regulated protein 78 kDa (GRP78) proteins and spliced X-box binding protein 1 (XBP-1s) mRNA and increased the expression of genes encoding lipolytic enzymes hormone-sensitive lipase (HSL) and monoacylglycerol lipase (MGL) and VLDL assembly-associated proteins microsomal triglyceride transfer protein (MTP) and apolipoprotein B (APOB) in tunicamycin-pretreated cells. Moreover, exendin-4 significantly decreased lipin-1β/α ratio by increasing SFRP10 and increased lipin-1 nuclear localization. The decrease in lipin-1β/α ratio was also observed in SIRT1 and AMPK agonist-treated cells. These data suggest that exendin-4 improves ER stress-induced hepatic lipid accumulation by increasing lipolysis and VLDL assembly, which is partially mediated by the regulation of lipin-1 signaling.
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Affiliation(s)
- Jinmi Lee
- Institute of Medical Research, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, 03181, Republic of Korea
| | - Seok-Woo Hong
- Institute of Medical Research, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, 03181, Republic of Korea
| | - Hyemi Kwon
- Department of Endocrinology and Metabolism, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, 03181, Republic of Korea
| | - Se Eun Park
- Department of Endocrinology and Metabolism, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, 03181, Republic of Korea
| | - Eun-Jung Rhee
- Department of Endocrinology and Metabolism, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, 03181, Republic of Korea
| | - Cheol-Young Park
- Department of Endocrinology and Metabolism, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, 03181, Republic of Korea
| | - Ki-Won Oh
- Department of Endocrinology and Metabolism, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, 03181, Republic of Korea
| | - Sung-Woo Park
- Department of Endocrinology and Metabolism, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, 03181, Republic of Korea
| | - Won-Young Lee
- Department of Endocrinology and Metabolism, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, 03181, Republic of Korea.
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, #29 Seamunan-ro, Jongro-Ku, Seoul, 03181, Republic of Korea.
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20
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Yu D, Chen G, Pan M, Zhang J, He W, Liu Y, Nian X, Sheng L, Xu B. High fat diet-induced oxidative stress blocks hepatocyte nuclear factor 4α and leads to hepatic steatosis in mice. J Cell Physiol 2018; 233:4770-4782. [PMID: 29150932 DOI: 10.1002/jcp.26270] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 11/14/2017] [Indexed: 12/15/2022]
Affiliation(s)
- Dongsheng Yu
- Department of Pharmacology; School of Basic Medical Science; Nanjing Medical University; Nanjing Jiangsu China
| | - Gang Chen
- Department of Hepatobiliary Surgery; The First Affiliated Hospital of Wenzhou Medical University; Wenzhou Zhejiang China
| | - Minglin Pan
- Department of Endocrinology; The Second Affiliated Hospital of Nanjing Medical University; Nanjing Jiangsu China
| | - Jia Zhang
- Department of Pharmacology; School of Basic Medical Science; Nanjing Medical University; Nanjing Jiangsu China
| | - Wenping He
- Department of Pharmacology; School of Basic Medical Science; Nanjing Medical University; Nanjing Jiangsu China
| | - Yang Liu
- Department of Gastroenterology and Hepatology; Zhongda Hospital; Nanjing Jiangsu China
- Institute of Gastroenterology and Hepatology; School of Medicine; Southeast University; Nanjing Jiangsu China
| | - Xue Nian
- Department of Pharmacology; School of Basic Medical Science; Nanjing Medical University; Nanjing Jiangsu China
| | - Liang Sheng
- Department of Pharmacology; School of Basic Medical Science; Nanjing Medical University; Nanjing Jiangsu China
| | - Bin Xu
- Department of Internal Medicine; Division of Metabolism, Endocrinology and Diabetes; University of Michigan Medical Center; Ann Arbor Michigan
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21
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HIV-1 viral protein R (Vpr) induces fatty liver in mice via LXRα and PPARα dysregulation: implications for HIV-specific pathogenesis of NAFLD. Sci Rep 2017; 7:13362. [PMID: 29042644 PMCID: PMC5645472 DOI: 10.1038/s41598-017-13835-w] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 10/02/2017] [Indexed: 12/18/2022] Open
Abstract
HIV patients develop hepatic steatosis. We investigated hepatic steatosis in transgenic mice expressing the HIV-1 accessory protein Vpr (Vpr-Tg) in liver and adipose tissues, and WT mice infused with synthetic Vpr. Vpr-Tg mice developed increased liver triglyceride content and elevated ALT, bilirubin and alkaline phosphatase due to three hepatic defects: 1.6-fold accelerated de novo lipogenesis (DNL), 45% slower fatty acid ß-oxidation, and 40% decreased VLDL-triglyceride export. Accelerated hepatic DNL was due to coactivation by Vpr of liver X receptor-α (LXRα) with increased expression of its lipogenic targets Srebp1c, Chrebp, Lpk, Dgat, Fasn and Scd1, and intranuclear SREBP1c and ChREBP. Vpr enhanced association of LXRα with Lxrα and Srebp1c promoters, increased LXRE-LXRα binding, and broadly altered hepatic expression of LXRα-regulated lipid metabolic genes. Diminished hepatic fatty acid ß-oxidation was associated with decreased mRNA expression of Pparα and its targets Cpt1, Aox, Lcad, Ehhadh, Hsd10 and Acaa2, and blunted VLDL export with decreased expression of Mttp and its product microsomal triglyceride transfer protein. With our previous findings that Vpr circulates in HIV patients (including those with undetectable plasma HIV-1 RNA), co-regulates the glucocorticoid receptor and PPARγ and transduces hepatocytes, these data indicate a potential role for Vpr in HIV-associated fatty liver disease.
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Massafra V, van Mil SWC. Farnesoid X receptor: A "homeostat" for hepatic nutrient metabolism. Biochim Biophys Acta Mol Basis Dis 2017; 1864:45-59. [PMID: 28986309 DOI: 10.1016/j.bbadis.2017.10.003] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 09/27/2017] [Accepted: 10/02/2017] [Indexed: 02/06/2023]
Abstract
The Farnesoid X receptor (FXR) is a nuclear receptor activated by bile acids (BAs). BAs are amphipathic molecules that serve as fat solubilizers in the intestine under postprandial conditions. In the post-absorptive state, BAs bind FXR in the hepatocytes, which in turn provides feedback signals on BA synthesis and transport and regulates lipid, glucose and amino acid metabolism. Therefore, FXR acts as a homeostat of all three classes of nutrients, fats, sugars and proteins. Here we re-analyze the function of FXR in the perspective of nutritional metabolism, and discuss the role of FXR in liver energy homeostasis in postprandial, post-absorptive and fasting/starvation states. FXR, by regulating nutritional metabolism, represses autophagy in conditions of nutrient abundance, and controls the metabolic needs of proliferative cells. In addition, FXR regulates inflammation via direct effects and via its impact on nutrient metabolism. These functions indicate that FXR is an attractive therapeutic target for liver diseases.
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Affiliation(s)
- Vittoria Massafra
- Center for Molecular Medicine, UMC Utrecht, Utrecht, The Netherlands
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Kamada Y, Ebisutani Y, Kida S, Mizutani K, Akita M, Yamamoto A, Fujii H, Sobajima T, Terao N, Takamatsu S, Yoshida Y, Takehara T, Miyoshi E. Ectopic expression of N-acetylglucosaminyltransferase V accelerates hepatic triglyceride synthesis. Hepatol Res 2016; 46:E118-29. [PMID: 26041473 DOI: 10.1111/hepr.12541] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 05/24/2015] [Accepted: 06/02/2015] [Indexed: 01/28/2023]
Abstract
AIM Glycosylation changes induce various types of biological phenomena in human diseases. N-Acetylglucosaminyltransferase V (GnT-V) is one of the most important glycosyltransferases involved in cancer biology. Recently, many researchers have challenged studies of lipid metabolism in cancer. To elucidate the relationships between cancer and lipid metabolism more precisely, we investigated the effects of GnT-V on lipid metabolism. In this study, we investigated the effects of aberrant glycosylation by GnT-V on hepatic triglyceride production. METHODS We compared lipid metabolism in GnT-V transgenic (Tg) mice with that of wild-type (WT) mice fed with normal chow or a choline-deficient amino acid-defined (CDAA) diet in vivo. HepG2 cells and GnT-V transfectants of Hep3B cells were used in an in vitro study. RESULTS Serum triglyceride levels and hepatic very low-density lipoprotein (VLDL) secretion in Tg mice were significantly elevated compared with that of WT mice. Hepatic lipogenic genes (Lxrα, Srebp1, Fas and Acc) and VLDL secretion-related gene (Mttp1) were significantly higher in Tg mice. Expression of these genes was also significantly higher in GnT-V transfectants than in mock cells. Knockdown of GnT-V decreased, while both epidermal growth factor and transforming growth factor-β1 stimulation increased LXRα gene expression in HepG2 cells. Finally, we found that the blockade of VLDL secretion by CDAA diet induced massive hepatic steatosis in Tg mice. CONCLUSION Our study demonstrates that enhancement of hepatic GnT-V activity accelerates triglyceride synthesis and VLDL secretion. Glycosylation modification by GnT-V regulation could be a novel target for a therapeutic approach to lipid metabolism.
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Affiliation(s)
- Yoshihiro Kamada
- Departments of Molecular Biochemistry and Clinical Investigation, Suita, Japan.,Gastroenterology and Hepatology, Osaka University, Graduate School of Medicine, Suita, Japan
| | - Yusuke Ebisutani
- Departments of Molecular Biochemistry and Clinical Investigation, Suita, Japan
| | - Sachiho Kida
- Departments of Molecular Biochemistry and Clinical Investigation, Suita, Japan
| | - Kayo Mizutani
- Departments of Molecular Biochemistry and Clinical Investigation, Suita, Japan
| | - Maaya Akita
- Departments of Molecular Biochemistry and Clinical Investigation, Suita, Japan
| | - Akiko Yamamoto
- Departments of Molecular Biochemistry and Clinical Investigation, Suita, Japan
| | - Hironobu Fujii
- Departments of Molecular Biochemistry and Clinical Investigation, Suita, Japan
| | - Tomoaki Sobajima
- Departments of Molecular Biochemistry and Clinical Investigation, Suita, Japan
| | - Naoko Terao
- Departments of Molecular Biochemistry and Clinical Investigation, Suita, Japan
| | - Shinji Takamatsu
- Departments of Molecular Biochemistry and Clinical Investigation, Suita, Japan
| | - Yuichi Yoshida
- Gastroenterology and Hepatology, Osaka University, Graduate School of Medicine, Suita, Japan
| | - Tetsuo Takehara
- Gastroenterology and Hepatology, Osaka University, Graduate School of Medicine, Suita, Japan
| | - Eiji Miyoshi
- Departments of Molecular Biochemistry and Clinical Investigation, Suita, Japan
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Li JY, Zhang DD, Jiang GZ, Li XF, Zhang CN, Zhou M, Liu WB, Xu WN. Cloning and characterization of microsomal triglyceride transfer protein gene and its potential connection with peroxisome proliferator-activated receptor (PPAR) in blunt snout bream (Megalobrama amblycephala). Comp Biochem Physiol B Biochem Mol Biol 2015. [PMID: 26210738 DOI: 10.1016/j.cbpb.2015.07.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Microsomal triglyceride transfer protein (MTTP), a major intracellular protein capable of transferring neutral lipids, plays a pivotal role in the assembly and secretion of apolipoprotein B-containing lipoproteins. In this study, MTTP cDNA was firstly cloned from the liver of blunt snout bream (Megalobrama amblycephala), the full-length cDNA covered 3457-bp with an open reading frame of 2661-bp, which encodes 886 amino acids, including a putative signal peptide of 24 amino acids long. After the feeding trial, a graded tissue-specific expression pattern of MTTP was observed and high expression abundance in the liver and intestine indicated its major function in lipid transport in this fish species. In addition, expression of genes encoding MTTP as well as peroxisome proliferator-activated receptor (PPAR), which are transcription factors and serve as key regulators in lipid homoeostasis, was all affected by dietary lipid and choline supplementations. Elevated dietary lipid levels significantly increased the liver, intestinal and muscle MTTP mRNA abundance. Additionally, the down-regulation of MTTP expression in the liver and muscle was observed when fish were fed with inadequate choline supplementation in high-fat diet, yet up-regulated as supplementing extra choline in diet. Expressions of PPARα and PPARβ in the liver and muscle showed similar trend of MTTP expression. The results suggested the potential connection of MTTP and PPAR in response to different dietary nutritional factors. Furthermore, extra choline supplementations could promote lipid transfer and enhance fatty acid oxidation, which indicated a molecular mechanism of choline on diminishing fat accumulation in blunt snout bream.
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Affiliation(s)
- Jun-Yi Li
- Laboratory of Aquatic Nutrition and Ecology, College of Animal Science and Technology, Nanjing Agricultural University, No. 1 Weigang Road, Nanjing 210095, China
| | - Ding-Dong Zhang
- Laboratory of Aquatic Nutrition and Ecology, College of Animal Science and Technology, Nanjing Agricultural University, No. 1 Weigang Road, Nanjing 210095, China
| | - Guang-Zhen Jiang
- Laboratory of Aquatic Nutrition and Ecology, College of Animal Science and Technology, Nanjing Agricultural University, No. 1 Weigang Road, Nanjing 210095, China
| | - Xiang-Fei Li
- Laboratory of Aquatic Nutrition and Ecology, College of Animal Science and Technology, Nanjing Agricultural University, No. 1 Weigang Road, Nanjing 210095, China
| | - Chun-Nuan Zhang
- Laboratory of Aquatic Nutrition and Ecology, College of Animal Science and Technology, Nanjing Agricultural University, No. 1 Weigang Road, Nanjing 210095, China
| | - Man Zhou
- Laboratory of Aquatic Nutrition and Ecology, College of Animal Science and Technology, Nanjing Agricultural University, No. 1 Weigang Road, Nanjing 210095, China
| | - Wen-Bin Liu
- Laboratory of Aquatic Nutrition and Ecology, College of Animal Science and Technology, Nanjing Agricultural University, No. 1 Weigang Road, Nanjing 210095, China.
| | - Wei-Na Xu
- Laboratory of Aquatic Nutrition and Ecology, College of Animal Science and Technology, Nanjing Agricultural University, No. 1 Weigang Road, Nanjing 210095, China.
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Abstract
Atherosclerosis is a chronic inflammatory disease with deposition of excessive cholesterol in the arterial intima. Peroxisome proliferator-activated receptor α (PPARα) is a nuclear receptor that can activate or inhibit the expression of many target genes by forming a heterodimer complex with the retinoid X receptor. Activation of PPARα plays an important role in the metabolism of multiple lipids, including high-density lipoprotein, cholesterol, low-density lipoprotein, triglyceride, phospholipid, bile acids, and fatty acids. Increased PPARα activity also mitigates atherosclerosis by blocking macrophage foam cell formation, vascular inflammation, vascular smooth muscle cell proliferation and migration, plaque instability, and thrombogenicity. Clinical use of synthetic PPARα agonist fibrate improved dyslipidemia and attenuated atherosclerosis-related disease risk. This review summarizes PPARα in lipid and lipoprotein metabolism and atherosclerosis, and also highlights its potential therapeutic benefits.
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Urbatzka R, Galante-Oliveira S, Rocha E, Lobo-da-Cunha A, Castro LFC, Cunha I. Effects of the PPARα agonist WY-14,643 on plasma lipids, enzymatic activities and mRNA expression of lipid metabolism genes in a marine flatfish, Scophthalmus maximus. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2015; 164:155-162. [PMID: 25974001 DOI: 10.1016/j.aquatox.2015.05.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 05/02/2015] [Accepted: 05/04/2015] [Indexed: 06/04/2023]
Abstract
Fibrates and other lipid regulator drugs are widespread in the aquatic environment including estuaries and coastal zones, but little is known on their chronic effects on non-target organisms as marine fish. In the present study, turbot juveniles were exposed to the PPARα model agonist WY-14,643 for 21 days by repeated injections at the concentrations of 5mg/kg (lo-WY) and 50mg/kg (hi-WY), and samples taken after 7 and 21 days. Enzyme activity and mRNA expression of palmitoyl-CoA oxidase and catalase in the liver were analyzed as first response, which validated the experiment by demonstrating interactions with the peroxisomal fatty acid oxidation and oxidative stress pathways in the hi-WY treatment. In order to get mechanistic insights, alterations of plasma lipids (free cholesterol, FC; HDL associated cholesterol, C-HDL; triglycerides, TG; non-esterified fatty acids, NEFA) and hepatic mRNA expression of 17 genes involved in fatty acid and lipid metabolism were studied. The exposure to hi-WY reduced the quantity of plasma FC, C-HDL, and NEFA. Microsomal triglyceride transfer protein and apolipoprotein E mRNA expression were higher in hi-WY, and indicated an increased formation of VLDL particles and energy mobilization from liver. It is speculated that energy depletion by PPARα agonists may contribute to a higher susceptibility to environmental stressors.
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Affiliation(s)
- R Urbatzka
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), CIMAR Associated Laboratory (CIMAR LA), University of Porto (U.Porto), Portugal.
| | - S Galante-Oliveira
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), CIMAR Associated Laboratory (CIMAR LA), University of Porto (U.Porto), Portugal; Department of Biology & CESAM, University of Aveiro, Portugal
| | - E Rocha
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), CIMAR Associated Laboratory (CIMAR LA), University of Porto (U.Porto), Portugal; Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto (U.Porto), Portugal
| | - A Lobo-da-Cunha
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), CIMAR Associated Laboratory (CIMAR LA), University of Porto (U.Porto), Portugal; Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto (U.Porto), Portugal
| | - L F C Castro
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), CIMAR Associated Laboratory (CIMAR LA), University of Porto (U.Porto), Portugal
| | - I Cunha
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), CIMAR Associated Laboratory (CIMAR LA), University of Porto (U.Porto), Portugal
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Hooper AJ, Burnett JR, Watts GF. Contemporary Aspects of the Biology and Therapeutic Regulation of the Microsomal Triglyceride Transfer Protein. Circ Res 2015; 116:193-205. [DOI: 10.1161/circresaha.116.304637] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Amanda J. Hooper
- Department of Clinical Biochemistry, PathWest Laboratory Medicine WA (A.J.H., J.R.B.), School of Medicine and Pharmacology (A.J.H., J.R.B., G.F.W.), School of Pathology and Laboratory Medicine (A.J.H), and Lipid Disorders Clinic, Cardiovascular Medicine (J.R.B., G.F.W), Royal Perth Hospital, University of Western Australia, Perth, Western Australia, Australia
| | - John R. Burnett
- Department of Clinical Biochemistry, PathWest Laboratory Medicine WA (A.J.H., J.R.B.), School of Medicine and Pharmacology (A.J.H., J.R.B., G.F.W.), School of Pathology and Laboratory Medicine (A.J.H), and Lipid Disorders Clinic, Cardiovascular Medicine (J.R.B., G.F.W), Royal Perth Hospital, University of Western Australia, Perth, Western Australia, Australia
| | - Gerald F. Watts
- Department of Clinical Biochemistry, PathWest Laboratory Medicine WA (A.J.H., J.R.B.), School of Medicine and Pharmacology (A.J.H., J.R.B., G.F.W.), School of Pathology and Laboratory Medicine (A.J.H), and Lipid Disorders Clinic, Cardiovascular Medicine (J.R.B., G.F.W), Royal Perth Hospital, University of Western Australia, Perth, Western Australia, Australia
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Szalowska E, Tesfay HA, van Hijum SAFT, Kersten S. Transcriptomic signatures of peroxisome proliferator-activated receptor α (PPARα) in different mouse liver models identify novel aspects of its biology. BMC Genomics 2014; 15:1106. [PMID: 25511156 PMCID: PMC4378209 DOI: 10.1186/1471-2164-15-1106] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 12/01/2014] [Indexed: 12/15/2022] Open
Abstract
Background The peroxisome proliferator-activated receptor alpha (PPARα) is a ligand-activated transcription factor that regulates lipid catabolism and inflammation and is hepatocarcinogenic in rodents. It is presumed that the functions of PPARα in liver depend on cross-talk between parenchymal (hepatocytes) and non-parenchymal (Kupffer and endothelial cells) fractions as well as inter-organ interactions. In order to determine how cellular composition and inter-organ interactions influence gene expression upon pharmacological activation of PPARα, we performed a meta-analysis of transcriptomics data obtained from mouse hepatocytes (containing only the parenchymal fraction), mouse liver slices (containing both fractions), and mouse livers exposed to a PPARα agonist. The aim was to obtain a comprehensive view of common and model-specific PPARα-dependent genes and biological processes to understand the impact of cross-talk between parenchymal and non-parenchymal fractions as well as the effect of inter-organ interactions on the hepatic PPARα transcriptome. To this end we analyzed microarray data of experiments performed in mouse primary hepatocytes treated with the PPARα agonist Wy14643 for 6 or 24 h (in vitro), mouse precision cut liver slices treated with Wy14643 for 24 h (ex vivo), and livers of wild type and Ppara knockout mice treated with Wy14643 for 6 h or 5 days (in vivo). Results In all models, activation of PPARα significantly altered processes related to various aspects of lipid metabolism. In ex vivo and in vivo models, PPARα activation significantly regulated processes involved in inflammation; these processes were unaffected in hepatocytes. Only in vivo models showed significant regulation of genes involved in coagulation, carcinogenesis, as well as vesicular trafficking and extracellular matrix. Conclusions PPARα-dependent regulation of genes/processes involved in lipid metabolism is mostly independent of the presence of non-parenchymal cells or systemic factors, as it was observed in all liver models. PPARα-dependent regulation of inflammatory genes requires the presence of non-parenchymal cells, as it was observed only ex vivo and in vivo. However, the full spectrum of PPARα biology at the level of lipid metabolism, immunity, carcinogenesis, as well as novel aspects of PPARα signaling such as coagulation, vesicular trafficking and the extracellular matrix, seems to require systemic factors, as it was observed exclusively in vivo. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-1106) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ewa Szalowska
- RIKILT - Institute of Food Safety, Wageningen UR, P,O, Box 230, 6700 AE Wageningen, The Netherlands.
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Agarwal N, Iyer D, Patel SG, Sekhar RV, Phillips TM, Schubert U, Oplt T, Buras ED, Samson SL, Couturier J, Lewis DE, Rodriguez-Barradas MC, Jahoor F, Kino T, Kopp JB, Balasubramanyam A. HIV-1 Vpr induces adipose dysfunction in vivo through reciprocal effects on PPAR/GR co-regulation. Sci Transl Med 2014; 5:213ra164. [PMID: 24285483 DOI: 10.1126/scitranslmed.3007148] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Viral infections, such as HIV, have been linked to obesity, but mechanistic evidence that they cause adipose dysfunction in vivo is lacking. We investigated a pathogenic role for the HIV-1 accessory protein viral protein R (Vpr), which can coactivate the glucocorticoid receptor (GR) and co-repress peroxisome proliferator-activated receptor γ (PPARγ) in vitro, in HIV-associated adipose dysfunction. Vpr circulated in the blood of most HIV-infected patients tested, including those on antiretroviral therapy (ART) with undetectable viral load. Vpr-mediated mechanisms were dissected in vivo using mouse models expressing the Vpr transgene in adipose tissues and liver (Vpr-Tg) or infused with synthetic Vpr. Both models demonstrated accelerated whole-body lipolysis, hyperglycemia and hypertriglyceridemia, and tissue-specific findings. Fat depots in these mice had diminished mass, macrophage infiltration, and blunted PPARγ target gene expression but increased GR target gene expression. In liver, we observed blunted PPARα target gene expression, steatosis with decreased adenosine monophosphate-activated protein kinase activity, and insulin resistance. Similar to human HIV-infected patients, Vpr circulated in the serum of Vpr-Tg mice. Vpr blocked differentiation in preadipocytes through cell cycle arrest, whereas in mature adipocytes, it increased lipolysis with reciprocally altered association of PPARγ and GR with their target promoters. These results delineate a distinct pathogenic sequence: Vpr, released from HIV-1 in tissue reservoirs after ART, can disrupt PPAR/GR co-regulation and cell cycle control to produce adipose dysfunction and hepatosteatosis. Confirmation of these mechanisms in HIV patients could lead to targeted treatment of the metabolic complications with Vpr inhibitors, GR antagonists, or PPARγ/PPARα agonists.
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Affiliation(s)
- Neeti Agarwal
- Translational Metabolism Unit, Diabetes Research Center, Division of Diabetes, Endocrinology and Metabolism, Baylor College of Medicine, Houston, TX 77030, USA
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Gao Y, Shen W, Lu B, Zhang Q, Hu Y, Chen Y. Upregulation of hepatic VLDLR via PPARα is required for the triglyceride-lowering effect of fenofibrate. J Lipid Res 2014; 55:1622-33. [PMID: 24899625 DOI: 10.1194/jlr.m041988] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Indexed: 01/17/2023] Open
Abstract
The liver and the VLDL receptor (VLDLR) play major roles in TG and VLDL metabolism. However, the exact role of liver VLDLR is not well known because of the absence of or difficulty in detecting VLDLR in the liver. In this study, we demonstrate that fenofibrate, a PPARα agonist and widely used TG-lowering drug, markedly upregulated hepatic VLDLR, which is essential for lowering TG. This study also shows that the distinct regulatory roles of PPARα agonists on VLDLR in the liver and peripheral tissues including adipose tissues, heart, and skeletal muscles are due to the pattern of expression of PPARα. The in vivo portion of our study demonstrated that oral fenofibrate robustly increased liver VLDLR expression levels in hyperlipidemic and diabetic mice and significantly reduced the increase in serum TG observed in wt mice after feeding with high-fat diet (HFD) but not in Vldlr(-/-) mice or Pparα(-/-) mice. However, overexpression of mouse VLDLR in livers of Vldlr(-/-) mice significantly prevented the increase in serum TG induced by HFD. The in vitro portion of our study showed that fenofibrate upregulated VLDLR transcriptional activity through PPAR response element binding to the VLDLR promoter. The conclusions of our study provide a novel mechanism for the TG-lowering effects of fenofibrate in the treatment of dyslipidemia.
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Affiliation(s)
- Yang Gao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK
| | - Wei Shen
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK
| | - Boyu Lu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Qingjiong Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Yang Hu
- Oklahoma Medical Research Foundation, Oklahoma City, OK
| | - Ying Chen
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK
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Lushnikova EL, Nepomnyashchikh LM, Pichigin VI, Klinnikova MG, Nepomnyashchikh RD, Sergeevichev DS. Expression of mRNA of Apolipoprotein E, Apolipoprotein A-IV, and Matricellular Proteins in the Myocardium and Intensity of Fibroplastic Processes during Experimental Hypercholesterolemia. Bull Exp Biol Med 2013; 156:271-5. [DOI: 10.1007/s10517-013-2328-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Buttet M, Traynard V, Tran TTT, Besnard P, Poirier H, Niot I. From fatty-acid sensing to chylomicron synthesis: role of intestinal lipid-binding proteins. Biochimie 2013; 96:37-47. [PMID: 23958439 DOI: 10.1016/j.biochi.2013.08.011] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Accepted: 08/05/2013] [Indexed: 12/31/2022]
Abstract
Today, it is well established that the development of obesity and associated diseases results, in part, from excessive lipid intake associated with a qualitative imbalance. Among the organs involved in lipid homeostasis, the small intestine is the least studied even though it determines lipid bioavailability and largely contributes to the regulation of postprandial hyperlipemia (triacylglycerols (TG) and free fatty acids (FFA)). Several Lipid-Binding Proteins (LBP) are expressed in the small intestine. Their supposed intestinal functions were initially based on what was reported in other tissues, and took no account of the physiological specificity of the small intestine. Progressively, the identification of regulating factors of intestinal LBP and the description of the phenotype of their deletion have provided new insights into cellular and molecular mechanisms involved in fat absorption. This review will discuss the physiological contribution of each LBP in the main steps of intestinal absorption of long-chain fatty acids (LCFA): uptake, trafficking and reassembly into chylomicrons (CM). Moreover, current data indicate that the small intestine is able to adapt its lipid absorption capacity to the fat content of the diet, especially through the coordinated induction of LBP. This adaptation requires the existence of a mechanism of intestinal lipid sensing. Emerging data suggest that the membrane LBP CD36 may operate as a lipid receptor that triggers an intracellular signal leading to the modulation of the expression of LBP involved in CM formation. This event could be the starting point for the optimized synthesis of large CM, which are efficiently degraded in blood. Better understanding of this intestinal lipid sensing might provide new approaches to decrease the prevalence of postprandial hypertriglyceridemia, which is associated with cardiovascular diseases, insulin resistance and obesity.
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Affiliation(s)
- Marjorie Buttet
- Physiologie de la Nutrition et Toxicologie Team (NUTox), UMR U866 INSERM, Université de Bourgogne, AgroSup Dijon, 1 Esplanade Erasme, 21000 Dijon, France
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Octreotide promotes weight loss via suppression of intestinal MTP and apoB48 expression in diet-induced obesity rats. Nutrition 2013; 29:1259-65. [PMID: 23911221 DOI: 10.1016/j.nut.2013.01.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Revised: 01/11/2013] [Accepted: 01/14/2013] [Indexed: 02/05/2023]
Abstract
OBJECTIVE The goal of this study was to investigate the effect of octreotide on the expression of intestinal fat absorption-associated apolipoproteinB48 (apoB48), microsomal triglyceride transfer protein (MTP) and apolipoproteinAIV (apoAIV) in a high-fat diet-induced obesity rat model. METHODS Sprague-Dawley rats were placed into a control or high-fat diet group. Obese rats from the high-fat diet group were further divided into an obese group and an octreotide-treated group. Rats in the octreotide-treated group were subcutaneously injected with octreotide (40 μg/kg body weight) twice daily for 8 d. Body weight, fasting plasma glucose (FPG), fasting serum insulin, triglyceride (TG), total cholesterol (TC), and high density lipoprotein-cholesterol (HDL-C) were measured. Intestinal MTP, apoB48, and apoAIV expression levels were determined by real-time polymerase chain reaction, Western blot, or enzyme-linked immunosorbent assay analysis. RESULTS We found high-fat diet-induced obesity rats express more apoB, MTP, and apoAIV mRNA as well as apoB48 and MTP protein in the intestine than normal chow-fed rats. This observation occurred along with increased body weight, FPG, TG, TC, fasting serum insulin, and Homeostatic Model Assessment value. Octreotide intervention significantly decreased body weight and blood parameters, and down-regulated expression of apoB mRNA and apoB48 protein, as well as MTP mRNA and proteins. However, apoAIV mRNA was not significantly different between obese and octreotide-treated rats although it was decreased by 47%. CONCLUSION High-fat diet-induced obesity is associated with increased expression of apoB48, MTP, and apoAIV in the intestine. Octreotide intervention inhibited the overexpression of apoB48 and MTP, and consequently brought about reduced fat absorption and weight loss.
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Prince E, Lazare FB, Treem WR, Xu J, Iqbal J, Pan X, Josekutty J, Walsh M, Anderson V, Hussain MM, Schwarz SM. Ω-3 fatty acids prevent hepatic steatosis, independent of PPAR-α activity, in a murine model of parenteral nutrition-associated liver disease. JPEN J Parenter Enteral Nutr 2013; 38:608-16. [PMID: 23757305 DOI: 10.1177/0148607113491436] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 04/30/2013] [Indexed: 12/21/2022]
Abstract
OBJECTIVES ω-3 Fatty acids (FAs), natural ligands for the peroxisome proliferator-activated receptor-α (PPAR-α), attenuate parenteral nutrition-associated liver disease (PNALD). However, the mechanisms underlying the protective role of ω-3 FAs are still unknown. The aim of this study was to determine the effects of ω-3 FAs on hepatic triglyceride (TG) accumulation in a murine model of PNALD and to investigate the role of PPAR-α and microsomal triglyceride transfer protein (MTP) in this experimental setting. METHODS 129S1/SvImJ wild-type or 129S4/SvJaePparatm/Gonz/J PPAR-α knockout mice were fed chow and water (controls); oral, fat-free PN solution only (PN-O); PN-O plus intraperitoneal (IP) ω-6 FA-predominant supplements (PN-ω-6); or PN-O plus IP ω-3 FA (PN-ω-3). Control and PN-O groups received sham IP injections of 0.9% NaCl. Hepatic histology, TG and cholesterol, MTP activity, and PPAR-α messenger RNA were assessed after 19 days. RESULTS In all experimental groups, PN feeding increased hepatic TG and MTP activity compared with controls. Both PN-O and PN-ω-6 groups accumulated significantly greater amounts of TG when compared with PN-ω-3 mice. Studies in PPAR-α null animals showed that PN feeding increases hepatic TG as in wild-type mice. PPAR-α null mice in the PN-O and PN-ω-6 groups demonstrated variable degrees of hepatic steatosis, whereas no evidence of hepatic fat accumulation was found after 19 days of oral PN plus IP ω-3 FAs. CONCLUSIONS PN induces TG accumulation (steatosis) in wild-type and PPAR-α null mice. In PN-fed wild-type and PPAR-α null mice given IP ω-3 FAs, reduced hepatic TG accumulation and absent steatosis are found. Prevention of steatosis by ω-3 FAs results from PPAR-α-independent pathways.
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Affiliation(s)
- Esther Prince
- Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, State University of New York Downstate Medical Center, Brooklyn, New York
| | - Farrah B Lazare
- Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, State University of New York Downstate Medical Center, Brooklyn, New York Department of Pediatrics, Winthrop University Medical Center, Mineola, New York
| | - William R Treem
- Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, State University of New York Downstate Medical Center, Brooklyn, New York Johnson & Johnson Pharmaceutical Research and Development, LLC, Titusville, New Jersey
| | - Jiliu Xu
- Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, State University of New York Downstate Medical Center, Brooklyn, New York
| | - Jahangir Iqbal
- Department of Cell Biology, State University of New York Downstate Medical Center, Brooklyn, New York
| | - Xiaoyue Pan
- Department of Cell Biology, State University of New York Downstate Medical Center, Brooklyn, New York
| | - Joby Josekutty
- Department of Cell Biology, State University of New York Downstate Medical Center, Brooklyn, New York
| | - Meghan Walsh
- Department of Cell Biology, State University of New York Downstate Medical Center, Brooklyn, New York
| | - Virginia Anderson
- Department of Pathology, State University of New York Downstate Medical Center, Brooklyn, New York
| | - M Mahmood Hussain
- Department of Cell Biology, State University of New York Downstate Medical Center, Brooklyn, New York
| | - Steven M Schwarz
- Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, State University of New York Downstate Medical Center, Brooklyn, New York
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Shi L, Shi L, Zhang H, Hu Z, Wang C, Zhang D, Song G. Oxymatrine ameliorates non-alcoholic fatty liver disease in rats through peroxisome proliferator-activated receptor-α activation. Mol Med Rep 2013; 8:439-45. [PMID: 23754536 DOI: 10.3892/mmr.2013.1512] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 05/30/2013] [Indexed: 01/18/2023] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is the most common type of liver disease worldwide. Recent studies have reported that oxymatrine (OMT), an active monomer isolated from Sophora flavescens Ait. (kushen), ameliorates NAFLD in rats. In order to explore the possible molecular mechanism involved, we used an NAFLD rat model with hyperlipidemia, which had been established by feeding a high‑fructose diet (HFD) for eight weeks, and the model rats were subsequently treated with OMT (80 mg/kg/day) for a further four weeks. We evaluated the expression of genes and proteins regulating fatty acid oxidation and lipid export in the liver using quantitative (q)PCR and western blot analysis. The NAFLD model rats developed dyslipidaemia, hepatic steatosis and insulin resistance (IR). OMT administration for four weeks reduced body weight gain and visceral fat weight, decreased serum triglyceride (TG), total cholesterol (TC), free fatty acid (FFA) and fasting serum insulin (FinS) levels and lowered liver TG contents. It also increased the glucose infusion rate (GIR), indicative of a reduction in IR. Moreover, OMT treatment markedly increased the mRNA and protein levels of peroxisome proliferator-activated receptor-α (PPARα), carnitine palmitoyltransferase 1A (CPT1A) and microsomal triglyceride transfer protein (MTTP). The beneficial effects of OMT were further confirmed by the observation of a decrease in lipid accumulation in the histology of the liver. Our results indicate that OMT may be used to treat NAFLD.
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Affiliation(s)
- Lijuan Shi
- Department of Internal Medicine, Hebei Medical University, Shijiazhuang 050017, P.R. China
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Deciphering Emerging Toxicological Effects of Pharmaceuticals on Aquatic Organisms by Using Daphnia magna and Danio rerio as Model Organisms. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/b978-0-444-62657-8.00017-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2023]
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Guardiola M, Alvaro A, Vallvé JC, Rosales R, Solà R, Girona J, Serra N, Duran P, Esteve E, Masana L, Ribalta J. APOA5 gene expression in the human intestinal tissue and its response to in vitro exposure to fatty acid and fibrate. Nutr Metab Cardiovasc Dis 2012; 22:756-762. [PMID: 21489765 DOI: 10.1016/j.numecd.2010.12.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Revised: 10/05/2010] [Accepted: 12/11/2010] [Indexed: 01/11/2023]
Abstract
BACKGROUND AND AIMS APOA5, a key gene regulating triglyceride (TG) levels, is reported to be expressed exclusively in the liver where it may regulate TG-rich particle synthesis and secretion. Since the same lipoprotein processing occurs in the intestine, we have postulated that this organ would also express APOA5. METHODS AND RESULTS We have detected the APOA5 gene expression in C57BL/6J mouse and in human small intestine samples. In humans, it is expressed mainly in the duodenum and colon, with messenger RNA (mRNA) levels four orders of magnitude lower than in the liver, and the protein product being one-sixth of the liver equivalent. Subsequently, we carried out in vitro experiments in TC-7/CaCo(2) human intestinal cells to analyse the expression of APOA5, APOC3, APOB and MTP genes after the incubation with long- and short-chain fatty acids, and a peroxisome proliferator-activated receptor alpha (PPARα) agonist (Wy 14643, a fibrate therapeutic agent). In the TC-7 cell line, APOA5 expression was significantly upregulated by saturated fatty acids. The short-chain fatty acid butyrate increased APOA5 expression almost fourfold while APOB was downregulated by increasing butyrate concentrations. When TC-7 cells were incubated with PPARα agonist, the APOA5 expression was increased by 60%, while the expression of APOB, MTP and APOC3 was decreased by 50%, 30% and 45%, respectively. CONCLUSION Our results demonstrate that APOA5 is expressed in the intestine, albeit at a much lower concentration than in the liver. While it remains to be determined whether intestinal apo A-V is functional, our in vitro experiments show that its expression is modifiable by dietary and pharmacological stimuli.
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Affiliation(s)
- M Guardiola
- Unitat de Recerca en Lípids i Arteriosclerosi, Institut d'Investigacions Sanitàries Pere, Virgili, Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas, Universitat Rovira i Virgili, Reus, Spain
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Plasticizers May Activate Human Hepatic Peroxisome Proliferator-Activated Receptor α Less Than That of a Mouse but May Activate Constitutive Androstane Receptor in Liver. PPAR Res 2012; 2012:201284. [PMID: 22792086 PMCID: PMC3388330 DOI: 10.1155/2012/201284] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 03/19/2012] [Accepted: 03/21/2012] [Indexed: 12/05/2022] Open
Abstract
Dibutylphthalate (DBP), di(2-ethylhexyl)phthalate (DEHP), and di(2-ethylhexyl)adipate (DEHA) are used as plasticizers. Their metabolites activate peroxisome proliferator-activated receptor (PPAR) α, which may be related to their toxicities. However, species differences in the receptor functions between rodents and human make it difficult to precisely extrapolate their toxicity from animal studies to human. In this paper, we compared the species differences in the activation of mouse and human hepatic PPARα by these plasticizers using wild-type (mPPARα) and humanized PPARα (hPPARα) mice. At 12 weeks old, each genotyped male mouse was classified into three groups, and fed daily for 2 weeks per os with corn oil (vehicle control), 2.5 or 5.0 mmol/kg DBP (696, 1392 mg/kg), DEHP (977, 1953 mg/kg), and DEHA (926, 1853 mg/kg), respectively. Generally, hepatic PPARα of mPPARα mice was more strongly activated than that of hPPARα mice when several target genes involving β-oxidation of fatty acids were evaluated. Interestingly, all plasticizers also activated hepatic constitutive androstane receptor (CAR) more in hPPARα mice than in mPPARα mice. Taken together, these plasticizers activated mouse and human hepatic PPARα as well as CAR. The activation of PPARα was stronger in mPPARα mice than in hPPARα mice, while the opposite was true of CAR.
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Hepatic Cerebroside Sulfotransferase Is Induced by PPARα Activation in Mice. PPAR Res 2012; 2012:174932. [PMID: 22645601 PMCID: PMC3356938 DOI: 10.1155/2012/174932] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Accepted: 02/16/2012] [Indexed: 11/23/2022] Open
Abstract
Sulfatides are one of the major sphingoglycolipids in mammalian serum and are synthesized and secreted mainly from the liver as a component of lipoproteins. Recent studies revealed a protective role for serum sulfatides against arteriosclerosis and hypercoagulation. Although peroxisome proliferator-activated receptor (PPAR) α has important functions in hepatic lipoprotein metabolism, its association with sulfatides has not been investigated. In this study, sulfatide levels and the expression of enzymes related to sulfatide metabolism were examined using wild-type (+/+), Ppara-heterozygous (+/−), and Ppara-null (−/−) mice given a control diet or one containing 0.1% fenofibrate, a clinically used hypolipidemic drug and PPARα activator. Fenofibrate treatment increased serum and hepatic sulfatides in Ppara (+/+) and (+/−) mice through a marked induction of hepatic cerebroside sulfotransferase (CST), a key enzyme in sulfatide synthesis, in a PPARα-dependent manner. Furthermore, increases in CST mRNA levels were correlated with mRNA elevations of several known PPARα target genes, and such changes were not observed for other sulfatide-metabolism enzymes in the liver. These results suggest that PPARα activation enhances hepatic sulfatide synthesis via CST induction and implicate CST as a novel PPARα target gene.
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Higuchi N, Kato M, Tanaka M, Miyazaki M, Takao S, Kohjima M, Kotoh K, Enjoji M, Nakamuta M, Takayanagi R. Effects of insulin resistance and hepatic lipid accumulation on hepatic mRNA expression levels of apoB, MTP and L-FABP in non-alcoholic fatty liver disease. Exp Ther Med 2011; 2:1077-1081. [PMID: 22977624 DOI: 10.3892/etm.2011.328] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Accepted: 07/25/2011] [Indexed: 12/15/2022] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is considered a hepatic manifestation of metabolic syndrome, which is known to be associated with insulin resistance (IR). NAFLD occurs when the rate of hepatic fatty acid uptake from plasma and de novo fatty acid synthesis is greater than the rate of fatty acid oxidation and excretion as very low-density lipoprotein (VLDL). To estimate the effects of IR on hepatic lipid excretion, mRNA expression levels of genes involved in VLDL assembly were analyzed in NAFLD liver. Twenty-two histologically proven NAFLD patients and 10 healthy control subjects were enrolled in this study. mRNA was extracted from liver biopsy samples and real-time PCR was performed to quantify the expression levels of apolipoprotein B (apoB), microsomal triglyceride transfer protein (MTP) and liver fatty-acid binding protein (L-FABP). Hepatic expression levels of the genes were compared between NAFLD patients and control subjects. In NAFLD patients, we also examined correlations between expression levels of the genes and metabolic factors, including IR, and the extent of obesity and hepatic lipid accumulation. Hepatic expression levels of apoB, MTP and L-FABP were significantly up-regulated in NAFLD patients compared to control subjects. The expression levels of MTP were correlated with those of apoB, but not with those of L-FABP. In the NAFLD liver, the expression levels of MTP were significantly reduced in patients with HOMA-IR >2.5. In addition, a significant reduction in MTP expression was observed in livers with advanced steatosis. Enhanced expression of genes involved in VLDL assembly may be promoted to release excess lipid from NAFLD livers. However, the progression of IR and hepatic steatosis may attenuate this compensatory process.
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Affiliation(s)
- Nobito Higuchi
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582
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41
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Peroxisome proliferator activated receptors and lipoprotein metabolism. PPAR Res 2011; 2008:132960. [PMID: 18288277 PMCID: PMC2220040 DOI: 10.1155/2008/132960] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2007] [Accepted: 09/03/2007] [Indexed: 12/24/2022] Open
Abstract
Plasma lipoproteins are responsible for carrying triglycerides and cholesterol in the blood and ensuring their delivery to target organs. Regulation of lipoprotein metabolism takes place at numerous levels including via changes in gene transcription. An important group of transcription factors that mediates the effect of dietary fatty acids and certain drugs on plasma lipoproteins are the peroxisome proliferator activated receptors (PPARs). Three PPAR isotypes can be distinguished, all of which have a major role in regulating lipoprotein metabolism. PPARalpha is the molecular target for the fibrate class of drugs. Activation of PPARalpha in mice and humans markedly reduces hepatic triglyceride production and promotes plasma triglyceride clearance, leading to a clinically significant reduction in plasma triglyceride levels. In addition, plasma high-density lipoprotein (HDL)-cholesterol levels are increased upon PPARalpha activation in humans. PPARgamma is the molecular target for the thiazolidinedione class of drugs. Activation of PPARgamma in mice and human is generally associated with a modest increase in plasma HDL-cholesterol and a decrease in plasma triglycerides. The latter effect is caused by an increase in lipoprotein lipase-dependent plasma triglyceride clearance. Analogous to PPARalpha, activation of PPARbeta/delta leads to increased plasma HDL-cholesterol and decreased plasma triglyceride levels. In this paper, a fresh perspective on the relation between PPARs and lipoprotein metabolism is presented. The emphasis is on the physiological role of PPARs and the mechanisms underlying the effect of synthetic PPAR agonists on plasma lipoprotein levels.
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Peeters A, Swinnen JV, Van Veldhoven PP, Baes M. Hepatosteatosis in peroxisome deficient liver despite increased β-oxidation capacity and impaired lipogenesis. Biochimie 2011; 93:1828-38. [PMID: 21756965 DOI: 10.1016/j.biochi.2011.06.034] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Accepted: 06/27/2011] [Indexed: 11/26/2022]
Abstract
Peroxisome deficiency in liver causes hepatosteatosis both in patients and in mice. Here, we studied the mechanisms that contribute to this lipid accumulation and to activation of peroxisome proliferator activated receptor α (PPARα) by using liver-specific Pex5(-/-) mice (L-Pex5(-/-) mice). Surprisingly, steatosis was accompanied both by increased mitochondrial β-oxidation capacity, confirming previous observations, and by impaired de novo lipid synthesis mediated by reduced expression of sterol regulatory element binding protein 1c and its targets. As a consequence, when challenged with a high fat diet, L-Pex5(-/-) mice were protected from adiposity. Hepatic fatty acid uptake was strongly increased whereas the expression of apolipoproteins and the lipoprotein assembly factor microsomal triglyceride transfer protein were markedly reduced resulting in reduced secretion of very low density lipoproteins. Most of these changes seemed to be orchestrated by the endogenous activation of PPARα, challenging the assumption that PPARα activation in hepatocytes requires fatty acid synthase dependent de novo fatty acid synthesis. Expression of cholesterol synthesizing enzymes and cholesterol levels were not affected in peroxisome deficient liver. In conclusion, increased fatty acid uptake driven by endogenous PPARα activation and reduced fatty acid secretion cause hepatosteatosis in peroxisome deficient livers.
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Affiliation(s)
- Annelies Peeters
- Laboratory of Cell Metabolism, Department of Pharmaceutical Sciences, K.U.Leuven, B-3000 Leuven, Belgium
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Hussain MM, Nijstad N, Franceschini L. Regulation of microsomal triglyceride transfer protein. ACTA ACUST UNITED AC 2011; 6:293-303. [PMID: 21808658 DOI: 10.2217/clp.11.21] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Microsomal triglyceride transfer protein (MTP) facilitates the transport of dietary and endogenous fat by the intestine and liver by assisting in the assembly and secretion of triglyceride-rich apolipoprotein B-containing lipoproteins. Higher concentrations of apolipoprotein B lipoproteins predispose individuals to various cardiovascular and metabolic diseases such as atherosclerosis, diabetes, obesity and the metabolic syndrome. These can potentially be avoided by reducing MTP activity. In this article, we discuss regulation of MTP during development, cellular differentiation and diurnal variation. Furthermore, we focus on the regulation of MTP that occurs at transcriptional, post-transcriptional and post-translational levels. Transcriptional regulation of MTP depends on a few highly conserved cis-elements in the promoter. Several transcription factors that bind to these elements and either increase or decrease MTP expression have been identified. Additionally, MTP is regulated by macronutrients, hormones and other factors. This article will address the many ways in which MTP is regulated and advance the idea that reducing MTP levels, rather than its inhibition, might be an option to lower plasma lipids.
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Affiliation(s)
- M Mahmood Hussain
- Departments of Cell Biology and Pediatrics, The State University of New York, Downstate Medical Center, 450 Clarkson Ave, Brooklyn, NY 11203, USA
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Hayashi Y, Ito Y, Yamagishi N, Yanagiba Y, Tamada H, Wang D, Ramdhan DH, Naito H, Harada Y, Kamijima M, Gonzales FJ, Nakajima T. Hepatic peroxisome proliferator-activated receptor α may have an important role in the toxic effects of di(2-ethylhexyl)phthalate on offspring of mice. Toxicology 2011; 289:1-10. [PMID: 21354252 DOI: 10.1016/j.tox.2011.02.007] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2011] [Revised: 02/18/2011] [Accepted: 02/18/2011] [Indexed: 02/02/2023]
Abstract
Maternal exposure to di(2-ethylhexyl)phthalate (DEHP) is associated with adverse effects on offspring, and the metabolites are agonists of peroxisome proliferator-activated receptor (PPAR) α, which exhibits species differences in expression and function. This study aimed to clarify the mechanism of DEHP-induced adverse effects on offspring in relation to maternal mouse and human PPARα. Male and female Sv/129 wild-type (mPPARα), Pparα-null and humanized PPARα (hPPARα) mice were treated with diets containing 0%, 0.01%, 0.05% (medium) or 0.1% (high) DEHP. After 4 weeks, males and females were mated. Dams were killed on gestational day 18 and postnatal day (PND) 2. High-dose DEHP decreased the number of total and live fetuses, and increased resorptions in mPPARα mice. In hPPARα mice, resorptions were increased above the medium dose, and the number of births was decreased at the high dose. The number of live pups on PND2 was decreased over the medium dose in mPPARα and at the high dose in hPPARα mice. No such findings were observed in Pparα-null mice. High-dose DEHP decreased plasma triglyceride in pregnant mPPARα mice, but not in Pparα-null and hPPARα ones. Above the medium dose in mPPARα mice significantly reduced hepatic microsomal triglyceride transfer protein (MTP) expression. Medium- and/or high-dose DEHP increased the levels of maternal PPARα target genes in mPPARα and hPPARα mice. Taken together, PPARα expression is required for the toxicity of DEHP in fetuses and pups and altered plasma triglyceride levels, through regulation of MTP may be important in mPPARα mice and not in hPPARα mice.
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Affiliation(s)
- Yumi Hayashi
- Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
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Ryan MC, Desmond PV, Slavin JL, Congiu M. Expression of genes involved in lipogenesis is not increased in patients with HCV genotype 3 in human liver. J Viral Hepat 2011; 18:53-60. [PMID: 20196803 DOI: 10.1111/j.1365-2893.2010.01283.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Hepatitis C virus (HCV) infection is frequently associated with hepatic steatosis, particularly in patients with HCV genotype-3 (HCVGT3). It has variously been hypothesized, largely from in-vitro studies, to be the result of increased synthesis, decreased metabolism and export of triglycerides. We measured by real-time PCR the expression of genes involved in lipid metabolism [acetyl-Coenzyme A carboxylase alpha, apolipoprotein B (APOB), diacylglycerol O-acyltransferase 2, fatty acid-binding protein 1, fatty acid synthase, microsomal triglyceride transfer protein (MTTP), peroxisome proliferator-activated receptor alpha (PPARA), peroxisome proliferator-activated receptor gamma (PPARG), protein kinase AMP-activated alpha 1 catalytic subunit (PRKAA1) and sterol regulatory element-binding transcription factor 1 (SREBF1)] in liver biopsies from patients infected with HCV genotype-1 (HCVGT1), HCVGT3 and Hepatitis B (HBV) using β-glucuronidase (GUSB) and splicing factor arginine/serine-rich 4 (SFRS4) as housekeeping genes. Patients infected with HCVGT3 were younger than those infected with HCVGT1 (36.3 ± 2.5 vs 45.6 ± 1.5, P < 0.05, Mann-Whitney) and were more likely to have steatosis (69.2%vs 11.8%). No significant difference was found in the expression of genes involved in lipogenesis or transport in patients infected with HBV or HCV of either genotype. Contrary to expectation, given the greater degree of steatosis in HCVGT3-infected liver, expression of enzymes involved in lipogenesis was not elevated in HCVGT3 compared with HCVGT1 or HBV-infected liver. Significantly less mRNA for SREBF1 was found in HCVGT3-infected liver tissue compared with HCVGT1-infected liver (1.00 ± 0.06 vs 0.70 ± 0.15 P < 0.05). These results suggest that steatosis in patients infected with HCVGT3 is not the result of a sustained SREBF1 driven increase in expression of genes involved in lipogenesis. In addition, a significant genotype-independent correlation was found between the expression of APOB, MTTP, PRKAA1 and PPARA, indicating that these networks are functional in HCV-infected liver.
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Affiliation(s)
- M C Ryan
- Department of Gastroenterology, St Vincent's Hospital Melbourne, Fitzroy, Vic., Australia
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Rakhshandehroo M, Knoch B, Müller M, Kersten S. Peroxisome proliferator-activated receptor alpha target genes. PPAR Res 2010; 2010:612089. [PMID: 20936127 PMCID: PMC2948931 DOI: 10.1155/2010/612089] [Citation(s) in RCA: 532] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Accepted: 08/09/2010] [Indexed: 12/11/2022] Open
Abstract
The peroxisome proliferator-activated receptor alpha (PPARα) is a ligand-activated transcription factor involved in the regulation of a variety of processes, ranging from inflammation and immunity to nutrient metabolism and energy homeostasis. PPARα serves as a molecular target for hypolipidemic fibrates drugs which bind the receptor with high affinity. Furthermore, PPARα binds and is activated by numerous fatty acids and fatty acid-derived compounds. PPARα governs biological processes by altering the expression of a large number of target genes. Accordingly, the specific role of PPARα is directly related to the biological function of its target genes. Here, we present an overview of the involvement of PPARα in lipid metabolism and other pathways through a detailed analysis of the different known or putative PPARα target genes. The emphasis is on gene regulation by PPARα in liver although many of the results likely apply to other organs and tissues as well.
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Affiliation(s)
- Maryam Rakhshandehroo
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Bomenweg 2, 6703 HD Wageningen, The Netherlands
| | - Bianca Knoch
- Food, Metabolism & Microbiology, Food & Textiles Group, AgResearch, Palmerston North 4442, New Zealand
- Institute of Food, Nutrition & Human Health, Massey University, Tennent Drive, Palmerston North 4442, New Zealand
| | - Michael Müller
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Bomenweg 2, 6703 HD Wageningen, The Netherlands
| | - Sander Kersten
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Bomenweg 2, 6703 HD Wageningen, The Netherlands
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Bijland S, Pieterman EJ, Maas ACE, van der Hoorn JWA, van Erk MJ, van Klinken JB, Havekes LM, van Dijk KW, Princen HMG, Rensen PCN. Fenofibrate increases very low density lipoprotein triglyceride production despite reducing plasma triglyceride levels in APOE*3-Leiden.CETP mice. J Biol Chem 2010; 285:25168-75. [PMID: 20501652 DOI: 10.1074/jbc.m110.123992] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The peroxisome proliferator-activated receptor alpha (PPARalpha) activator fenofibrate efficiently decreases plasma triglycerides (TG), which is generally attributed to enhanced very low density lipoprotein (VLDL)-TG clearance and decreased VLDL-TG production. However, because data on the effect of fenofibrate on VLDL production are controversial, we aimed to investigate in (more) detail the mechanism underlying the TG-lowering effect by studying VLDL-TG production and clearance using APOE*3-Leiden.CETP mice, a unique mouse model for human-like lipoprotein metabolism. Male mice were fed a Western-type diet for 4 weeks, followed by the same diet without or with fenofibrate (30 mg/kg bodyweight/day) for 4 weeks. Fenofibrate strongly lowered plasma cholesterol (-38%) and TG (-60%) caused by reduction of VLDL. Fenofibrate markedly accelerated VLDL-TG clearance, as judged from a reduced plasma half-life of glycerol tri[(3)H]oleate-labeled VLDL-like emulsion particles (-68%). This was associated with an increased post-heparin lipoprotein lipase (LPL) activity (+110%) and an increased uptake of VLDL-derived fatty acids by skeletal muscle, white adipose tissue, and liver. Concomitantly, fenofibrate markedly increased the VLDL-TG production rate (+73%) but not the VLDL-apolipoprotein B (apoB) production rate. Kinetic studies using [(3)H]palmitic acid showed that fenofibrate increased VLDL-TG production by equally increasing incorporation of re-esterified plasma fatty acids and liver TG into VLDL, which was supported by hepatic gene expression profiling data. We conclude that fenofibrate decreases plasma TG by enhancing LPL-mediated VLDL-TG clearance, which results in a compensatory increase in VLDL-TG production by the liver.
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Affiliation(s)
- Silvia Bijland
- Department of Human Genetics, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
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48
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Abstract
Nonalcoholic fatty liver disease (NAFLD) is the most frequent liver disease worldwide, and is commonly associated with the metabolic syndrome. Secular trends in the prevalence of these diseases may be associated with the increased fructose consumption observed in the Western diet. NAFLD is characterized by two steps of liver injury: intrahepatic lipid accumulation (hepatic steatosis), and inflammatory progression to nonalcoholic steatohepatitis (NASH) (the 'two-hit' theory). In the first 'hit', hepatic metabolism of fructose promotes de novo lipogenesis and intrahepatic lipid, inhibition of mitochondrial beta-oxidation of long-chain fatty acids, triglyceride formation and steatosis, hepatic and skeletal muscle insulin resistance, and hyperglycemia. In the second 'hit', owing to the molecular instability of its five-membered furanose ring, fructose promotes protein fructosylation and formation of reactive oxygen species (ROS), which require quenching by hepatic antioxidants. Many patients with NASH also have micronutrient deficiencies and do not have enough antioxidant capacity to prevent synthesis of ROS, resulting in necroinflammation. We postulate that excessive dietary fructose consumption may underlie the development of NAFLD and the metabolic syndrome. Furthermore, we postulate that NAFLD and alcoholic fatty liver disease share the same pathogenesis.
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49
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Sandoval JC, Nakagawa-Toyama Y, Masuda D, Tochino Y, Nakaoka H, Kawase R, Yuasa-Kawase M, Nakatani K, Inagaki M, Tsubakio-Yamamoto K, Ohama T, Nishida M, Ishigami M, Komuro I, Yamashita S. Fenofibrate reduces postprandial hypertriglyceridemia in CD36 knockout mice. J Atheroscler Thromb 2010; 17:610-8. [PMID: 20351468 DOI: 10.5551/jat.3988] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
AIM Metabolic syndrome (MetS) and postprandial hypertriglyceridemia (PHTG) are closely related and both are associated with coronary heart disease. We have demonstrated that CD36 deficiency is prevalent in the genetic background of MetS and is accompanied by PHTG concomitantly with an increase in remnants and a decrease in high density lipoprotein cholesterol. These findings make CD36 knockout mice (CD36KO) an interesting model for evaluating PHTG in MetS. Fenofibrate was reported to reduce fasting and postprandial triglyceride (TG) levels in hypertriglyceridemic subjects with MetS. To define its mechanism, we investigated the effect of fenofibrate on PHTG in CD36KO. METHODS Wild-type (WT) and CD36KO mice were fed chow diet and fenofibrate for two weeks. TG concentrations and lipoprotein profiles were assessed during fasting and in the postprandial state in plasma; intestinal mucosa and lymph were collected after oral fat loading for both treatment groups. RESULTS Fenofibrate treatment markedly suppressed the postprandial TG response in CD36KO along with decreased apoB-48 levels in plasma. HPLC analysis depicted the decrease of TG content in chylomicrons (CM) and CM remnant-sized lipoproteins contributed to this suppression, suggesting that CM and CM remnant production in the intestines might be attenuated by fenofibrate. ApoB-48 and TG levels in intestinal lymph were markedly reduced after treatment. Intestinal mRNA expression of apoB was also reduced in the postprandial state after fenofibrate administration without affecting any other genes related to CM assembly and production. CONCLUSION Fenofibrate reduces PHTG in CD36KO partially through attenuating intestinal CM production.
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Affiliation(s)
- José C Sandoval
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan
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50
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PPAR/RXR Regulation of Fatty Acid Metabolism and Fatty Acid omega-Hydroxylase (CYP4) Isozymes: Implications for Prevention of Lipotoxicity in Fatty Liver Disease. PPAR Res 2010; 2009:952734. [PMID: 20300478 PMCID: PMC2840373 DOI: 10.1155/2009/952734] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2009] [Accepted: 12/30/2009] [Indexed: 02/08/2023] Open
Abstract
Fatty liver disease is a common lipid metabolism disorder influenced by the combination of individual genetic makeup, drug exposure, and life-style choices that are frequently associated with metabolic syndrome, which encompasses obesity, dyslipidemia, hypertension, hypertriglyceridemia, and insulin resistant diabetes. Common to obesity related dyslipidemia is the excessive storage of hepatic fatty acids (steatosis), due to a decrease in mitochondria β-oxidation with an increase in both peroxisomal β-oxidation, and microsomal ω-oxidation of fatty acids through peroxisome proliferator activated receptors (PPARs). How steatosis increases PPARα activated gene expression of fatty acid transport proteins, peroxisomal and mitochondrial fatty acid β-oxidation and ω-oxidation of fatty acids genes regardless of whether dietary fatty acids are polyunsaturated (PUFA), monounsaturated (MUFA), or saturated (SFA) may be determined by the interplay of PPARs and HNF4α with the fatty acid transport proteins L-FABP and ACBP. In hepatic steatosis and steatohepatitis, the ω-oxidation cytochrome P450 CYP4A gene expression is increased even with reduced hepatic levels of PPARα. Although numerous studies have suggested the role ethanol-inducible CYP2E1 in contributing to increased oxidative stress, Cyp2e1-null mice still develop steatohepatitis with a dramatic increase in CYP4A gene expression. This strongly implies that CYP4A fatty acid ω-hydroxylase P450s may play an important role in the development of steatohepatitis. In this review and tutorial, we briefly describe how fatty acids are partitioned by fatty acid transport proteins to either anabolic or catabolic pathways regulated by PPARs, and we explore how medium-chain fatty acid (MCFA) CYP4A and long-chain fatty acid (LCFA) CYP4Fω-hydroxylase genes are regulated in fatty liver. We finally propose a hypothesis that increased CYP4A expression with a decrease in CYP4F genes may promote the progression of steatosis to steatohepatitis.
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