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Iwaki M, Yoneda M, Wada N, Otani T, Kobayashi T, Nogami A, Saito S, Nakajima A. Emerging drugs for the treatment of hepatic fibrosis on nonalcoholic steatohepatitis. Expert Opin Emerg Drugs 2024; 29:127-137. [PMID: 38469871 DOI: 10.1080/14728214.2024.2328036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Accepted: 03/05/2024] [Indexed: 03/13/2024]
Abstract
INTRODUCTION Approved drug therapies for nonalcoholic steatohepatitis (NASH) are lacking, for which various agents are currently being tested in clinical trials. Effective drugs for liver fibrosis, the factor most associated with prognosis in NASH, are important. AREAS COVERED This study reviewed the treatment of NASH with a focus on the effects of existing drugs and new drugs on liver fibrosis. EXPERT OPINION Considering the complex pathophysiology of fibrosis in NASH, drug therapy may target multiple pathways. The method of assessing fibrosis is important when considering treatment for liver fibrosis in NASH. The Food and Drug Administration considers an important fibrosis endpoint to be histological improvement in at least one fibrosis stage while preventing worsening of fatty hepatitis. To obtain approval as a drug for NASH, efficacy needs to be demonstrated on endpoints such as liver-related events and myocardial infarction. Among the current therapeutic agents for NASH, thiazolidinedione, sodium-glucose co-transporter 2, and selective peroxisome proliferator-activated receptors α modulator have been reported to be effective against fibrosis, although further evidence is required. The effects of pan-peroxisome proliferator-activated receptors, obeticholic acid, and fibroblast growth factor-21 analogs on liver fibrosis in the development stage therapeutics for NASH are of particular interest.
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Affiliation(s)
- Michihiro Iwaki
- Department of Gastroenterology and Hepatology, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Masato Yoneda
- Department of Gastroenterology and Hepatology, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Naohiro Wada
- Department of Gastroenterology and Hepatology, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Tomohiro Otani
- Department of Gastroenterology and Hepatology, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Takashi Kobayashi
- Department of Gastroenterology and Hepatology, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Asako Nogami
- Department of Gastroenterology and Hepatology, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Satoru Saito
- Department of Gastroenterology, Sanno Hospital, Minato-Ku, Tokyo, Japan
| | - Atsushi Nakajima
- Department of Gastroenterology and Hepatology, Yokohama City University Graduate School of Medicine, Yokohama, Japan
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Liu C, Lin Y, Wang Y, Lin S, Zhou J, Tang H, Yi X, Ma Z, Xia T, Jiang B, Tian F, Ju Z, Liu B, Gu X, Yang Z, Wang W. HuR promotes triglyceride synthesis and intestinal fat absorption. Cell Rep 2024; 43:114238. [PMID: 38748875 DOI: 10.1016/j.celrep.2024.114238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2023] [Revised: 04/02/2024] [Accepted: 04/30/2024] [Indexed: 06/01/2024] Open
Abstract
Triacylglyceride (TAG) synthesis in the small intestine determines the absorption of dietary fat, but the underlying mechanisms remain to be further studied. Here, we report that the RNA-binding protein HuR (ELAVL1) promotes TAG synthesis in the small intestine. HuR associates with the 3' UTR of Dgat2 mRNA and intron 1 of Mgat2 pre-mRNA. Association of HuR with Dgat2 3' UTR stabilizes Dgat2 mRNA, while association of HuR with intron 1 of Mgat2 pre-mRNA promotes the processing of Mgat2 pre-mRNA. Intestinal epithelium-specific HuR knockout reduces the expression of DGAT2 and MGAT2, thereby reducing the dietary fat absorption through TAG synthesis and mitigating high-fat-diet (HFD)-induced non-alcoholic fatty liver disease (NAFLD) and obesity. Our findings highlight a critical role of HuR in promoting dietary fat absorption.
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Affiliation(s)
- Cihang Liu
- Department of Anesthesiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing 210008, China; Department of Biochemistry and Molecular Biology, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, School of Basic Medical Sciences, Peking University Health Science Center, 38 Xueyuan Road, Beijing 100191, China
| | - Yunping Lin
- Department of Biochemistry and Molecular Biology, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, School of Basic Medical Sciences, Peking University Health Science Center, 38 Xueyuan Road, Beijing 100191, China
| | - Ying Wang
- Department of Biochemistry and Molecular Biology, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, School of Basic Medical Sciences, Peking University Health Science Center, 38 Xueyuan Road, Beijing 100191, China
| | - Shuyong Lin
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Jing Zhou
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Hao Tang
- National Health Commission Key Laboratory of Cardiovascular Regenerative Medicine, Heart Center of Henan Provincial People's Hospital, Central China Fuwai Hospital of Zhengzhou University, Central China Fuwai Hospital and Central China Branch of National Center for Cardiovascular Diseases, Zhengzhou, Henan 450003, China
| | - Xia Yi
- Department of Biochemistry and Molecular Biology, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, School of Basic Medical Sciences, Peking University Health Science Center, 38 Xueyuan Road, Beijing 100191, China
| | - Zhengliang Ma
- Department of Anesthesiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing 210008, China
| | - Tianjiao Xia
- Medical School, Nanjing University, Nanjing 210093, China
| | - Bin Jiang
- Department of Biochemistry and Molecular Biology, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, School of Basic Medical Sciences, Peking University Health Science Center, 38 Xueyuan Road, Beijing 100191, China
| | - Feng Tian
- Department of Laboratory Animal Science, Peking University Health Science Center, 38 Xueyuan Road, Beijing 100191, China
| | - Zhenyu Ju
- Key Laboratory of Regenerative Medicine of Ministry of Education, Institute of Aging and Regenerative Medicine, Jinan University, Guangzhou 510632, China
| | - Baohua Liu
- Guangdong Key Laboratory of Genome Stability and Human Disease Prevention, Carson International Cancer Center, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Shenzhen University Health Science Center, Shenzhen 518060, China
| | - Xiaoping Gu
- Department of Anesthesiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing 210008, China.
| | - Zhongzhou Yang
- Medical School, Nanjing University, Nanjing 210093, China.
| | - Wengong Wang
- Department of Biochemistry and Molecular Biology, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, School of Basic Medical Sciences, Peking University Health Science Center, 38 Xueyuan Road, Beijing 100191, China; Center for Healthy Aging, Changzhi Medical College, Changzhi 046000, China; Liaoning Technology and Engineering Center for Tumor Immunology and Molecular Theranostics, Collaborative Innovation Center for Age-related Disease, Life Science Institute of Jinzhou Medical University, Jinzhou 121001, Liaoning, China.
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3
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Esler WP, Cohen DE. Pharmacologic inhibition of lipogenesis for the treatment of NAFLD. J Hepatol 2024; 80:362-377. [PMID: 37977245 PMCID: PMC10842769 DOI: 10.1016/j.jhep.2023.10.042] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 10/13/2023] [Accepted: 10/23/2023] [Indexed: 11/19/2023]
Abstract
The hepatic accumulation of excess triglycerides is a seminal event in the initiation and progression of non-alcoholic fatty liver disease (NAFLD). Hepatic steatosis occurs when the hepatic accrual of fatty acids from the plasma and de novo lipogenesis (DNL) is no longer balanced by rates of fatty acid oxidation and secretion of very low-density lipoprotein-triglycerides. Accumulating data indicate that increased rates of DNL are central to the development of hepatic steatosis in NAFLD. Whereas the main drivers in NAFLD are transcriptional, owing to both hyperinsulinemia and hyperglycaemia, the effectors of DNL are a series of well-characterised enzymes. Several have proven amenable to pharmacologic inhibition or oligonucleotide-mediated knockdown, with lead compounds showing liver fat-lowering efficacy in phase II clinical trials. In humans with NAFLD, percent reductions in liver fat have closely mirrored percent inhibition of DNL, thereby affirming the critical contributions of DNL to NAFLD pathogenesis. The safety profiles of these compounds have so far been encouraging. It is anticipated that inhibitors of DNL, when administered alone or in combination with other therapeutic agents, will become important agents in the management of human NAFLD.
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Affiliation(s)
- William P Esler
- Internal Medicine Research Unit, Pfizer Worldwide Research Development and Medical, Cambridge, MA 02139 United States.
| | - David E Cohen
- Division of Gastroenterology, Hepatology and Endoscopy, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115 United States.
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Gugliucci A. The chylomicron saga: time to focus on postprandial metabolism. Front Endocrinol (Lausanne) 2024; 14:1322869. [PMID: 38303975 PMCID: PMC10830840 DOI: 10.3389/fendo.2023.1322869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 12/28/2023] [Indexed: 02/03/2024] Open
Abstract
Since statins have had such tremendous therapeutic success over the last three decades, the field of atherosclerosis has become somewhat LDL-centric, dismissing the relevance of triglycerides (TG), particularly chylomicrons, in atherogenesis. Nonetheless, 50% of patients who take statins are at risk of developing atherosclerotic cardiovascular disease (ASCVD) and are unable to achieve their goal LDL-C levels. This residual risk is mediated, in part by triglyceride rich lipoproteins (TRL) and their remnants. Following his seminal investigation on the subject, Zilversmit proposed that atherosclerosis is a postprandial event in 1979 (1-4). In essence, the concept suggests that remnant cholesterol-rich chylomicron (CM) and very-low density lipoprotein (VLDL) particles play a role in atherogenesis. Given the foregoing, this narrative review addresses the most recent improvements in our understanding of postprandial dyslipidemia. The primary metabolic pathways of chylomicrons are discussed, emphasizing the critical physiological role of lipoprotein lipase and apoCIII, the importance of these particles' fluxes in the postprandial period, their catabolic rate, the complexities of testing postprandial metabolism, and the role of angiopoietin-like proteins in the partition of CM during the fed cycle. The narrative is rounded out by the dysregulation of postprandial lipid metabolism in insulin resistance states and consequent CVD risk, the clinical evaluation of postprandial dyslipidemia, current research limits, and potential future study directions.
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Affiliation(s)
- Alejandro Gugliucci
- Glycation, Oxidation and Disease Laboratory, Department of Research, Touro University California, Vallejo, CA, United States
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Pierce MR, Hougland JL. A rising tide lifts all MBOATs: recent progress in structural and functional understanding of membrane bound O-acyltransferases. Front Physiol 2023; 14:1167873. [PMID: 37250116 PMCID: PMC10213974 DOI: 10.3389/fphys.2023.1167873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 04/19/2023] [Indexed: 05/31/2023] Open
Abstract
Acylation modifications play a central role in biological and physiological processes. Across a range of biomolecules from phospholipids to triglycerides to proteins, introduction of a hydrophobic acyl chain can dramatically alter the biological function and cellular localization of these substrates. Amongst the enzymes catalyzing these modifications, the membrane bound O-acyltransferase (MBOAT) family occupies an intriguing position as the combined substrate selectivities of the various family members span all three classes of these biomolecules. MBOAT-dependent substrates are linked to a wide range of health conditions including metabolic disease, cancer, and neurodegenerative disease. Like many integral membrane proteins, these enzymes have presented challenges to investigation due to their intractability to solubilization and purification. However, over the last several years new solubilization approaches coupled with computational modeling, crystallography, and cryoelectron microscopy have brought an explosion of structural information for multiple MBOAT family members. These studies enable comparison of MBOAT structure and function across members catalyzing modifications of all three substrate classes, revealing both conserved features amongst all MBOATs and distinct architectural features that correlate with different acylation substrates ranging from lipids to proteins. We discuss the methods that led to this renaissance of MBOAT structural investigations, our new understanding of MBOAT structure and implications for catalytic function, and the potential impact of these studies for development of new therapeutics targeting MBOAT-dependent physiological processes.
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Affiliation(s)
- Mariah R. Pierce
- Department of Chemistry, Syracuse University, Syracuse, NY, United States
| | - James L. Hougland
- Department of Chemistry, Syracuse University, Syracuse, NY, United States
- Department of Biology, Syracuse University, Syracuse, NY, United States
- BioInspired Syracuse, Syracuse University, Syracuse, NY, United States
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6
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Hull KL, Greenwood MP, Lloyd M, Bester-van der Merwe AE, Rhode C. Gene expression differentials driven by mass rearing and artificial selection in black soldier fly colonies. INSECT MOLECULAR BIOLOGY 2023; 32:86-105. [PMID: 36322045 DOI: 10.1111/imb.12816] [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: 02/03/2022] [Accepted: 10/25/2022] [Indexed: 06/16/2023]
Abstract
The micro-evolutionary forces that shape genetic diversity during domestication have been assessed in many plant and animal systems. However, the impact of these processes on gene expression, and consequent functional adaptation to artificial environments, remains under-investigated. In this study, whole-transcriptome dynamics associated with the early stages of domestication of the black soldier fly (BSF), Hermetia illucens, were assessed. Differential gene expression (DGE) was evaluated in relation to (i) generational time within the cultured environment (F2 vs. F3), and (ii) two selection strategies [no artificial selective pressure (NS); and selection for greater larval mass (SEL)]. RNA-seq was conducted on 5th instar BSF larvae (n = 36), representing equal proportions of the NS (F2 = 9; F3 = 9) and SEL (F2 = 9; F3 = 9) groups. A multidimensional scaling plot revealed greater gene expression variability within the NS and F2 subgroups, while the SEL group clustered separately with lower levels of variation. Comparisons between generations revealed 898 differentially expressed genes (DEGs; FDR-corrected p < 0.05), while between selection strategies, 213 DEGs were observed (FDR-corrected p < 0.05). Enrichment analyses revealed that metabolic, developmental, and defence response processes were over-expressed in the comparison between F2 and F3 larvae, while metabolic processes were the main differentiating factor between NS and SEL lines. This illustrates the functional adaptations that occur in BSF colonies across generations due to mass rearing; as well as highlighting genic dynamics associated with artificial selection for production traits that might inform future selective breeding strategies.
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Affiliation(s)
- Kelvin L Hull
- Department of Genetics, Stellenbosch University, Stellenbosch, South Africa
| | | | - Melissa Lloyd
- Research and Development Department, Insect Technology Group Holdings UK Ltd., Guildford, UK
| | | | - Clint Rhode
- Department of Genetics, Stellenbosch University, Stellenbosch, South Africa
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7
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Li X, Liu Q, Pan Y, Chen S, Zhao Y, Hu Y. New insights into the role of dietary triglyceride absorption in obesity and metabolic diseases. Front Pharmacol 2023; 14:1097835. [PMID: 36817150 PMCID: PMC9932209 DOI: 10.3389/fphar.2023.1097835] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 01/20/2023] [Indexed: 02/05/2023] Open
Abstract
The incidence of obesity and associated metabolic diseases is increasing globally, adversely affecting human health. Dietary fats, especially triglycerides, are an important source of energy for the body, and the intestine absorbs lipids through a series of orderly and complex steps. A long-term high-fat diet leads to intestinal dysfunction, inducing obesity and metabolic disorders. Therefore, regulating dietary triglycerides absorption is a promising therapeutic strategy. In this review, we will discuss diverse aspects of the dietary triglycerides hydrolysis, fatty acid uptake, triglycerides resynthesis, chylomicron assembly, trafficking, and secretion processes in intestinal epithelial cells, as well as potential targets in this process that may influence dietary fat-induced obesity and metabolic diseases. We also mention the possible shortcomings and deficiencies in modulating dietary lipid absorption targets to provide a better understanding of their administrability as drugs in obesity and related metabolic disorders.
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Affiliation(s)
- Xiaojing Li
- Key Laboratory of Liver and Kidney Diseases (Ministry of Education), Institute of Liver Diseases, Shanghai Key Laboratory of Traditional Chinese Clinical Medicine, Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Qiaohong Liu
- Institute of Clinical Pharmacology, Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Yuqing Pan
- Key Laboratory of Liver and Kidney Diseases (Ministry of Education), Institute of Liver Diseases, Shanghai Key Laboratory of Traditional Chinese Clinical Medicine, Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Si Chen
- Key Laboratory of Liver and Kidney Diseases (Ministry of Education), Institute of Liver Diseases, Shanghai Key Laboratory of Traditional Chinese Clinical Medicine, Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Yu Zhao
- Key Laboratory of Liver and Kidney Diseases (Ministry of Education), Institute of Liver Diseases, Shanghai Key Laboratory of Traditional Chinese Clinical Medicine, Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, Shanghai, China,*Correspondence: Yu Zhao, ; Yiyang Hu,
| | - Yiyang Hu
- Key Laboratory of Liver and Kidney Diseases (Ministry of Education), Institute of Liver Diseases, Shanghai Key Laboratory of Traditional Chinese Clinical Medicine, Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, Shanghai, China,Institute of Clinical Pharmacology, Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, Shanghai, China,*Correspondence: Yu Zhao, ; Yiyang Hu,
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8
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Syed-Abdul MM, Stahel P, Zembroski A, Tian L, Xiao C, Nahmias A, Bookman I, Buhman KK, Lewis GF. Glucagon-like peptide-2 acutely enhances chylomicron secretion in humans without mobilizing cytoplasmic lipid droplets. J Clin Endocrinol Metab 2022; 108:1084-1092. [PMID: 36458872 DOI: 10.1210/clinem/dgac690] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 11/21/2022] [Accepted: 11/29/2022] [Indexed: 12/05/2022]
Abstract
CONTEXT A portion of ingested fats are retained in the intestine for many hours before they are mobilized and secreted in chylomicron (CM) particles. Factors like glucagon-like peptide-2 (GLP-2) and glucose can mobilize these stored intestinal lipids and enhance CM secretion. We have recently demonstrated in rodents that GLP-2 acutely enhances CM secretion by mechanisms that do not involve the canonical CM synthetic assembly and secretory pathways. OBJECTIVE To further investigate the mechanism of GLP-2's potent intestinal lipid mobilizing effect, we examined intracellular cytoplasmic lipid droplets (CLDs) in intestinal biopsies of humans administered GLP-2 or placebo. DESIGN, SETTING, PATIENTS, AND INTERVENTIONS A single dose of placebo or GLP-2 was administered subcutaneously five hours after ingesting a high-fat bolus. In one subset of participants, plasma samples were collected to quantify lipid and lipoprotein concentrations for 3 hours post-placebo or GLP-2. In another subset, a duodenal biopsy was obtained one-hour post-placebo or GLP-2 administration for transmission electron microscopy (TEM) and proteomic analysis. RESULTS GLP-2 significantly increased plasma-TG by 46% (P = 0.009), mainly in CM-sized particles (CM-TG) by 133% (P = 0.003), without reducing duodenal CLD size or number. Several proteins of interest were identified that require further investigation to elucidate their potential role in GLP-2-mediated CM secretion. CONCLUSIONS Unlike glucose that mobilizes enterocyte CLDs and enhances CM secretion, GLP-2 acutely increased plasma CMs without significant mobilization of CLDs, supporting our previous findings that GLP-2 does not act directly on enterocytes to enhance CM secretion and most likely mobilizes secreted CMs in the lamina propria and lymphatics.
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Affiliation(s)
- Majid Mufaqam Syed-Abdul
- Departments of Medicine and Physiology and Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, CANADA
| | - Priska Stahel
- Departments of Medicine and Physiology and Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, CANADA
| | - Alyssa Zembroski
- Department of Nutrition Science, Purdue University, West Lafayette, Indiana, USA
| | - Lili Tian
- Departments of Medicine and Physiology and Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, CANADA
| | - Changting Xiao
- Department of Anatomy, Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, CANADA
| | - Avital Nahmias
- Maccabi Healthcare Services, Endocrinology Division, Tel Aviv, Israel
| | - Ian Bookman
- Kensington Screening Clinic, Department of Medicine, University of Toronto, Toronto, Ontario, CANADA
| | - Kimberly K Buhman
- Department of Nutrition Science, Purdue University, West Lafayette, Indiana, USA
| | - Gary F Lewis
- Departments of Medicine and Physiology and Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, CANADA
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Futatsugi K, Cabral S, Kung DW, Huard K, Lee E, Boehm M, Bauman J, Clark RW, Coffey SB, Crowley C, Dechert-Schmitt AM, Dowling MS, Dullea R, Gosset JR, Kalgutkar AS, Kou K, Li Q, Lian Y, Loria PM, Londregan AT, Niosi M, Orozco C, Pettersen JC, Pfefferkorn JA, Polivkova J, Ross TT, Sharma R, Stock IA, Tesz G, Wisniewska H, Goodwin B, Price DA. Discovery of Ervogastat (PF-06865571): A Potent and Selective Inhibitor of Diacylglycerol Acyltransferase 2 for the Treatment of Non-alcoholic Steatohepatitis. J Med Chem 2022; 65:15000-15013. [PMID: 36322383 DOI: 10.1021/acs.jmedchem.2c01200] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Discovery efforts leading to the identification of ervogastat (PF-06865571), a systemically acting diacylglycerol acyltransferase (DGAT2) inhibitor that has advanced into clinical trials for the treatment of non-alcoholic steatohepatitis (NASH) with liver fibrosis, are described herein. Ervogastat is a first-in-class DGAT2 inhibitor that addressed potential development risks of the prototype liver-targeted DGAT2 inhibitor PF-06427878. Key design elements that culminated in the discovery of ervogastat are (1) replacement of the metabolically labile motif with a 3,5-disubstituted pyridine system, which addressed potential safety risks arising from a cytochrome P450-mediated O-dearylation of PF-06427878 to a reactive quinone metabolite precursor, and (2) modifications of the amide group to a 3-THF group, guided by metabolite identification studies coupled with property-based drug design.
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Affiliation(s)
- Kentaro Futatsugi
- Pfizer Inc. Medicine Design, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Shawn Cabral
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Daniel W Kung
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Kim Huard
- Pfizer Inc. Medicine Design, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Esther Lee
- Pfizer Inc. Medicine Design, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Markus Boehm
- Pfizer Inc. Medicine Design, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Jonathan Bauman
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Ronald W Clark
- Pfizer Inc. Internal Medicine Research Unit, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Steven B Coffey
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Collin Crowley
- Pfizer Inc. Internal Medicine Research Unit, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | | | - Matthew S Dowling
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Robert Dullea
- Pfizer Inc. Internal Medicine Research Unit, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - James R Gosset
- Pfizer Inc. Medicine Design, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Amit S Kalgutkar
- Pfizer Inc. Medicine Design, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Kou Kou
- Pfizer Inc. Internal Medicine Research Unit, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Qifang Li
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Yajing Lian
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Paula M Loria
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Allyn T Londregan
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Mark Niosi
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Christine Orozco
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - John C Pettersen
- Pfizer Inc. Drug Safety R&D, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Jeffrey A Pfefferkorn
- Pfizer Inc. Internal Medicine Research Unit, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Jana Polivkova
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Trenton T Ross
- Pfizer Inc. Internal Medicine Research Unit, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Raman Sharma
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Ingrid A Stock
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Gregory Tesz
- Pfizer Inc. Internal Medicine Research Unit, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Hanna Wisniewska
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Bryan Goodwin
- Pfizer Inc. Internal Medicine Research Unit, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - David A Price
- Pfizer Inc. Medicine Design, 1 Portland Street, Cambridge, Massachusetts 02139, United States
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10
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Paalvast Y, Zhou E, Rozendaal YJW, Wang Y, Gerding A, van Dijk TH, de Boer JF, Rensen PCN, van Dijk KW, Kuivenhoven JA, Bakker BM, van Riel NAW, Groen AK. A Systems Analysis of Phenotype Heterogeneity in APOE*3Leiden.CETP Mice Induced by Long-Term High-Fat High-Cholesterol Diet Feeding. Nutrients 2022; 14:nu14224936. [PMID: 36432620 PMCID: PMC9698005 DOI: 10.3390/nu14224936] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 11/11/2022] [Accepted: 11/15/2022] [Indexed: 11/23/2022] Open
Abstract
Within the human population, considerable variability exists between individuals in their susceptibility to develop obesity and dyslipidemia. In humans, this is thought to be caused by both genetic and environmental variation. APOE*3-Leiden.CETP mice, as part of an inbred mouse model in which mice develop the metabolic syndrome upon being fed a high-fat high-cholesterol diet, show large inter-individual variation in the parameters of the metabolic syndrome, despite a lack of genetic and environmental variation. In the present study, we set out to resolve what mechanisms could underlie this variation. We used measurements of glucose and lipid metabolism from a six-month longitudinal study on the development of the metabolic syndrome. Mice were classified as mice with either high plasma triglyceride (responders) or low plasma triglyceride (non-responders) at the baseline. Subsequently, we fitted the data to a dynamic computational model of whole-body glucose and lipid metabolism (MINGLeD) by making use of a hybrid modelling method called Adaptations in Parameter Trajectories (ADAPT). ADAPT integrates longitudinal data, and predicts how the parameters of the model must change through time in order to comply with the data and model constraints. To explain the phenotypic variation in plasma triglycerides, the ADAPT analysis suggested a decreased cholesterol absorption, higher energy expenditure and increased fecal fatty acid excretion in non-responders. While decreased cholesterol absorption and higher energy expenditure could not be confirmed, the experimental validation demonstrated that the non-responders were indeed characterized by increased fecal fatty acid excretion. Furthermore, the amount of fatty acids excreted strongly correlated with bile acid excretion, in particular deoxycholate. Since bile acids play an important role in the solubilization of lipids in the intestine, these results suggest that variation in bile acid homeostasis may in part drive the phenotypic variation in the APOE*3-Leiden.CETP mice.
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Affiliation(s)
- Yared Paalvast
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, The Netherlands
| | - Enchen Zhou
- Department of Medicine, Division of Endocrinology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
| | - Yvonne J. W. Rozendaal
- Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
| | - Yanan Wang
- Department of Medicine, Division of Endocrinology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
| | - Albert Gerding
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, The Netherlands
| | - Theo H. van Dijk
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, The Netherlands
| | - Jan Freark de Boer
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, The Netherlands
| | - Patrick C. N. Rensen
- Department of Medicine, Division of Endocrinology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
- Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
| | - Ko Willems van Dijk
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
- Department of Human Genetics, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
| | - Jan A. Kuivenhoven
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, The Netherlands
| | - Barbara M. Bakker
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, The Netherlands
| | - Natal A. W. van Riel
- Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
- Laboratory of Experimental Vascular Medicine, University of Amsterdam, Amsterdam UMC, Meibergdreef, 1105 AZ Amsterdam, The Netherlands
| | - Albert K. Groen
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, The Netherlands
- Laboratory of Experimental Vascular Medicine, University of Amsterdam, Amsterdam UMC, Meibergdreef, 1105 AZ Amsterdam, The Netherlands
- Correspondence:
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11
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Otaibi AA, Mubarak SA, Qarni AA, Hawwari A, Bakillah A, Iqbal J. ATP-Binding Cassette Protein ABCC10 Deficiency Prevents Diet-Induced Obesity but Not Atherosclerosis in Mice. Int J Mol Sci 2022; 23:ijms232213813. [PMID: 36430292 PMCID: PMC9694421 DOI: 10.3390/ijms232213813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 09/20/2022] [Accepted: 09/20/2022] [Indexed: 11/11/2022] Open
Abstract
Excess plasma lipid levels are a risk factor for various cardiometabolic disorders. Studies have shown that improving dyslipidemia lowers the progression of these disorders. In this study, we investigated the role of ATP-binding cassette transporter C10 (ABCC10) in regulating lipid metabolism. Our data indicate that deletion of the Abcc10 gene in male mice results in lower plasma and intestinal triglycerides by around 38% and 36%, respectively. Furthermore, deletion of ABCC10 ameliorates diet-induced obesity in mice and leads to a better response during insulin and glucose tolerance tests. Unexpectedly, ABCC10 deficiency does not affect triglyceride levels or atherosclerosis in ApoE-deficient mice. In addition, our studies demonstrate low oleate uptake by enterocytes (~25-30%) and less absorption (~37%) of triglycerides in the small intestine of ABCC10 knockout mice. Deletion of the Abcc10 gene also alters several lipid metabolism genes in the intestine, suggesting that ABCC10 regulates dietary fat absorption, which may contribute to diet-induced obesity in mice.
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12
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Meszaros M, Bikov A. Obstructive Sleep Apnoea and Lipid Metabolism: The Summary of Evidence and Future Perspectives in the Pathophysiology of OSA-Associated Dyslipidaemia. Biomedicines 2022; 10:2754. [PMID: 36359273 PMCID: PMC9687681 DOI: 10.3390/biomedicines10112754] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 10/27/2022] [Accepted: 10/27/2022] [Indexed: 09/29/2023] Open
Abstract
Obstructive sleep apnoea (OSA) is associated with cardiovascular and metabolic comorbidities, including hypertension, dyslipidaemia, insulin resistance and atherosclerosis. Strong evidence suggests that OSA is associated with an altered lipid profile including elevated levels of triglyceride-rich lipoproteins and decreased levels of high-density lipoprotein (HDL). Intermittent hypoxia; sleep fragmentation; and consequential surges in the sympathetic activity, enhanced oxidative stress and systemic inflammation are the postulated mechanisms leading to metabolic alterations in OSA. Although the exact mechanisms of OSA-associated dyslipidaemia have not been fully elucidated, three main points have been found to be impaired: activated lipolysis in the adipose tissue, decreased lipid clearance from the circulation and accelerated de novo lipid synthesis. This is further complicated by the oxidisation of atherogenic lipoproteins, adipose tissue dysfunction, hormonal changes, and the reduced function of HDL particles in OSA. In this comprehensive review, we summarise and critically evaluate the current evidence about the possible mechanisms involved in OSA-associated dyslipidaemia.
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Affiliation(s)
- Martina Meszaros
- Department of Pulmonology and Sleep Disorders Centre, University Hospital Zurich, 8091 Zurich, Switzerland
- Department of Pulmonology, Semmelweis University, 1083 Budapest, Hungary
| | - Andras Bikov
- North West Lung Centre, Wythenshawe Hospital, Manchester University NHS Foundation Trust, Manchester M23 9LT, UK
- Division of Infection, Immunity and Respiratory Medicine, University of Manchester, Manchester M13 9MT, UK
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13
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Burchat N, Akal T, Ntambi JM, Trivedi N, Suresh R, Sampath H. SCD1 is nutritionally and spatially regulated in the intestine and influences systemic postprandial lipid homeostasis and gut-liver crosstalk. Biochim Biophys Acta Mol Cell Biol Lipids 2022; 1867:159195. [PMID: 35718096 PMCID: PMC11287785 DOI: 10.1016/j.bbalip.2022.159195] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 04/21/2022] [Accepted: 06/01/2022] [Indexed: 01/27/2023]
Abstract
Stearoyl-CoA desaturase-1 is an endoplasmic reticulum (ER)-membrane resident protein that inserts a double bond into saturated fatty acids, converting them into their monounsaturated counterparts. Previous studies have demonstrated an important role for SCD1 in modulating tissue and systemic health. Specifically, lack of hepatic or cutaneous SCD1 results in significant reductions in tissue esterified lipids. While the intestine is an important site of lipid esterification and assimilation into the body, the regulation of intestinal SCD1 or its impact on lipid composition in the intestine and other tissues has not been investigated. Here we report that unlike other lipogenic enzymes, SCD1 is enriched in the distal small intestine and in the colon of chow-fed mice and is robustly upregulated by acute refeeding of a high-sucrose diet. We generated a mouse model lacking SCD1 specifically in the intestine (iKO mice). These mice have significant reductions not only in intestinal lipids, but also in plasma triacylglycerols, diacylglycerols, cholesterol esters, and free cholesterol. Additionally, hepatic accumulation of diacylglycerols is significantly reduced in iKO mice. Comprehensive targeted lipidomic profiling revealed a consistent reduction in the myristoleic (14:1) to myristic (14:0) acid ratios in intestine, liver, and plasma of iKO mice. Consistent with the reduction of the monounsaturated fatty acid myristoleic acid in hepatic lipids of chow fed iKO mice, hepatic expression of Pgc-1α, Sirt1, and related fatty acid oxidation genes were reduced in chow-fed iKO mice. Further, lack of intestinal SCD1 reduced expression of de novo lipogenic genes in distal intestine of chow-fed mice and in the livers of mice fed a lipogenic high-sucrose diet. Taken together, these studies reveal a novel pattern of expression of SCD1 in the intestine. They also demonstrate that intestinal SCD1 modulates lipid content and composition of not only intestinal tissues, but also that of plasma and liver. Further, these data point to intestinal SCD1 as a modulator of gut-liver crosstalk, potentially through the production of novel signaling lipids such as myristoleic acid. These data have important implications to understanding how intestinal SCD1 may modulate risk for post-prandial lipemia, hepatic steatosis, and related pathologies.
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Affiliation(s)
- Natalie Burchat
- Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, United States of America
| | - Tasleenpal Akal
- Department of Nutritional Sciences, Rutgers University, United States of America
| | - James M Ntambi
- Departments of Biochemistry and Nutritional Sciences, University of Wisconsin-Madison, United States of America
| | - Nirali Trivedi
- Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, United States of America
| | - Ranjita Suresh
- Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, United States of America
| | - Harini Sampath
- Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, United States of America; Department of Nutritional Sciences, Rutgers University, United States of America.
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14
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Catlin NR, Bowman CJ, Campion SN, Lewis EM, Nowland WS, Stethem C, Cappon GD. The postnatal resolution of developmental toxicity induced by pharmacological diacylglycerol acyltransferase 2 (DGAT2) inhibition during gestation in rats. Toxicol Sci 2022; 189:225-236. [PMID: 35866640 DOI: 10.1093/toxsci/kfac077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Ervogastat (PF-06865571) is a small molecule diacylglycerol acyltransferase 2 (DGAT2) inhibitor being developed for the oral treatment of non-alcoholic steatohepatitis (NASH) with liver fibrosis. DGAT2 is a key enzyme in triglyceride synthesis in tissues and in regulating energy metabolism. Fertility and developmental toxicity studies with ervogastat were conducted in female rats and rabbits. There were no effects on female rat fertility or rabbit embryo-fetal development. Administration of ervogastat to pregnant rats during organogenesis reduced fetal weight and caused higher incidences of bent bones in fetuses that were shown to resolve by postnatal day 28 and were therefore considered to be transient variations secondary to developmental delay. Extended dosing in rats through the end of gestation and lactation (pre- and post-natal development study) caused impaired skin development, reduced offspring viability and growth retardation. The spectrum of developmental effects in rats is consistent with the intended pharmacology (altered triglyceride metabolism) and the transient nature of the skeletal findings, along with the late gestational window of sensitivity for the effects on skin barrier development, reduce the concern for potential adverse developmental effects following unintended early gestational exposure to ervogastat in humans where treatment can be discontinued once pregnancy is determined.
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Affiliation(s)
- Natasha R Catlin
- Drug Safety Research, Development, & Medical, Pfizer Worldwide Research & Development, Groton, CT, USA
| | - Christopher J Bowman
- Drug Safety Research, Development, & Medical, Pfizer Worldwide Research & Development, Groton, CT, USA
| | - Sarah N Campion
- Drug Safety Research, Development, & Medical, Pfizer Worldwide Research & Development, Groton, CT, USA
| | - Elise M Lewis
- Charles River Laboratories, Inc, Safety Assessment, Horsham, PA, USA
| | - William S Nowland
- Drug Safety Research, Development, & Medical, Pfizer Worldwide Research & Development, Groton, CT, USA
| | - Christine Stethem
- Drug Safety Research, Development, & Medical, Pfizer Worldwide Research & Development, Groton, CT, USA
| | - Gregg D Cappon
- Drug Safety Research, Development, & Medical, Pfizer Worldwide Research & Development, Groton, CT, USA
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15
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Chen G, Harwood JL, Lemieux MJ, Stone SJ, Weselake RJ. Acyl-CoA:diacylglycerol acyltransferase: Properties, physiological roles, metabolic engineering and intentional control. Prog Lipid Res 2022; 88:101181. [PMID: 35820474 DOI: 10.1016/j.plipres.2022.101181] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 05/31/2022] [Accepted: 07/04/2022] [Indexed: 12/15/2022]
Abstract
Acyl-CoA:diacylglycerol acyltransferase (DGAT, EC 2.3.1.20) catalyzes the last reaction in the acyl-CoA-dependent biosynthesis of triacylglycerol (TAG). DGAT activity resides mainly in membrane-bound DGAT1 and DGAT2 in eukaryotes and bifunctional wax ester synthase-diacylglycerol acyltransferase (WSD) in bacteria, which are all membrane-bound proteins but exhibit no sequence homology to each other. Recent studies also identified other DGAT enzymes such as the soluble DGAT3 and diacylglycerol acetyltransferase (EaDAcT), as well as enzymes with DGAT activities including defective in cuticular ridges (DCR) and steryl and phytyl ester synthases (PESs). This review comprehensively discusses research advances on DGATs in prokaryotes and eukaryotes with a focus on their biochemical properties, physiological roles, and biotechnological and therapeutic applications. The review begins with a discussion of DGAT assay methods, followed by a systematic discussion of TAG biosynthesis and the properties and physiological role of DGATs. Thereafter, the review discusses the three-dimensional structure and insights into mechanism of action of human DGAT1, and the modeled DGAT1 from Brassica napus. The review then examines metabolic engineering strategies involving manipulation of DGAT, followed by a discussion of its therapeutic applications. DGAT in relation to improvement of livestock traits is also discussed along with DGATs in various other eukaryotic organisms.
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Affiliation(s)
- Guanqun Chen
- Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta T6H 2P5, Canada.
| | - John L Harwood
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, UK
| | - M Joanne Lemieux
- Department of Biochemistry, University of Alberta, Membrane Protein Disease Research Group, Edmonton T6G 2H7, Canada
| | - Scot J Stone
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada.
| | - Randall J Weselake
- Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta T6H 2P5, Canada
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16
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Ghanem M, Lewis GF, Xiao C. Recent advances in cytoplasmic lipid droplet metabolism in intestinal enterocyte. Biochim Biophys Acta Mol Cell Biol Lipids 2022; 1867:159197. [PMID: 35820577 DOI: 10.1016/j.bbalip.2022.159197] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 06/03/2022] [Accepted: 06/14/2022] [Indexed: 11/30/2022]
Abstract
Processing of dietary fats in the intestine is a highly regulated process that influences whole-body energy homeostasis and multiple physiological functions. Dysregulated lipid handling in the intestine leads to dyslipidemia and atherosclerotic cardiovascular disease. In intestinal enterocytes, lipids are incorporated into lipoproteins and cytoplasmic lipid droplets (CLDs). Lipoprotein synthesis and CLD metabolism are inter-connected pathways with multiple points of regulation. This review aims to highlight recent advances in the regulatory mechanisms of lipid processing in the enterocyte, with particular focus on CLDs. In-depth understanding of the regulation of lipid metabolism in the enterocyte may help identify therapeutic targets for the treatment and prevention of metabolic disorders.
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Affiliation(s)
- Murooj Ghanem
- Department of Anatomy, Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Gary F Lewis
- Departments of Medicine and Physiology, University of Toronto, and University Health Network, Toronto, ON, Canada
| | - Changting Xiao
- Department of Anatomy, Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
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17
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Goo YT, Sa CK, Kim MS, Sin GH, Kim CH, Kim HK, Kang MJ, Lee S, Choi YW. Enhanced dissolution and bioavailability of revaprazan using self-nanoemulsifying drug delivery system. Pharm Dev Technol 2022; 27:414-424. [PMID: 35467467 DOI: 10.1080/10837450.2022.2070644] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A self-nanoemulsifying drug delivery system (SNEDDS) was developed to enhance the dissolution and oral bioavailability (BA) of revaprazan (RVP). Various SNEDDSs containing 200 mg of RVP were formulated using Capmul MCM, Tween 80, and Brij L4, and they were characterized according to their size, polydispersity index, and dissolution behavior. Dissolution rates of all SNEDDS formulations significantly (p <0.05) improved with the formation of nanoemulsion with monodispersity. Formulation D resulted in RVP dissolution exceeding 70% at 2 h. Compared to raw RVP, SNEDDS exhibited a 4.8- to 7.4-fold improved effective permeability coefficient (Peff) throughout the intestine in the in situ single pass intestinal permeability study and a 5.1-fold increased oral BA in the in vivo oral absorption assessment in rats. To evaluate the degree of lymphatic uptake, cycloheximide (CYC), a chylomicron flowing blocker, was pretreated prior to the experiment. This pretreatment barely affected the absorption of raw RVP; however, it greatly influenced the absorption of SNEDDS, resulting in an approximately 40% reduction in both the Peff value and oral BA representing lymphatic transport. Thus, we suggest that the SNEDDS formulation is a good candidate for improving oral absorption of RVP through enhanced lymphatic uptake.
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Affiliation(s)
- Yoon Tae Goo
- College of Pharmacy, Chung-Ang University, 84 Heuksuk-ro, Dongjak-gu, Seoul 06974, Republic of Korea
| | - Cheol-Ki Sa
- College of Pharmacy, Chung-Ang University, 84 Heuksuk-ro, Dongjak-gu, Seoul 06974, Republic of Korea
| | - Min Song Kim
- College of Pharmacy, Chung-Ang University, 84 Heuksuk-ro, Dongjak-gu, Seoul 06974, Republic of Korea
| | - Gi Hyeong Sin
- College of Pharmacy, Chung-Ang University, 84 Heuksuk-ro, Dongjak-gu, Seoul 06974, Republic of Korea
| | - Chang Hyun Kim
- College of Pharmacy, Chung-Ang University, 84 Heuksuk-ro, Dongjak-gu, Seoul 06974, Republic of Korea
| | - Hyeon Kyun Kim
- College of Pharmacy, Chung-Ang University, 84 Heuksuk-ro, Dongjak-gu, Seoul 06974, Republic of Korea
| | - Myung Joo Kang
- College of Pharmacy, Dankook University, 119 Dandae-ro, Dongnam-gu, Cheonan, Chungnam 330-714, Republic of Korea
| | - Sangkil Lee
- College of Pharmacy, Keimyung University, 1095 Dalgubeol-daero, Daegu 704-701, Republic of Korea
| | - Young Wook Choi
- College of Pharmacy, Chung-Ang University, 84 Heuksuk-ro, Dongjak-gu, Seoul 06974, Republic of Korea
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18
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Jiao P, Zhang M, Wang Z, Liang G, Xie X, Zhang Y, Chen Z, Jiang Q, Loor JJ. Circ003429 Regulates Unsaturated Fatty Acid Synthesis in the Dairy Goat Mammary Gland by Interacting with miR-199a-3p, Targeting the YAP1 Gene. Int J Mol Sci 2022; 23:ijms23074068. [PMID: 35409428 PMCID: PMC8999533 DOI: 10.3390/ijms23074068] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 03/31/2022] [Accepted: 04/05/2022] [Indexed: 02/01/2023] Open
Abstract
Fatty acid composition is a key factor affecting the flavor and quality of goat milk. CircRNAs are now recognized as important regulators of transcription, and they play an important role in the control of fatty acid synthesis. Thus, understanding the regulatory mechanisms controlling this process in ruminant mammary glands is of great significance. In the present study, mammary tissue from dairy goats during early lactation and the dry period (nonlactating) were collected and used for high-throughput sequencing. Compared to levels during the dry period, the expression level of circ003429 during early lactation was lower (12.68-fold downregulated). In isolated goat mammary epithelial cells, circ003429 inhibited the synthesis of triglycerides (TAG) and decreased the content of unsaturated fatty acids (C16:1, C18:1, and C18:2), indicating that this circRNA plays an important role in regulating lipid synthesis. A binding site for miR-199a-3p in the circ003429 sequence was detected, and a dual-luciferase reporter system revealed that circ003429 targets miR-199a-3p. Overexpression of circ003429 (pcDNA-circ003429) downregulated the abundance of miR-199a-3p. In contrast, overexpression of miR-199a-3p increased TAG content and decreased mRNA abundance of Yes-associated protein 1 (YAP1) (a target gene of miR-199a-3p), and TAG content was decreased and mRNA abundance was increased in response to overexpression of circ003429. These results indicate that circ003429 alleviates the inhibitory effect of miR-199a-3p on the mRNA abundance of YAP1 by binding miR-199a-3p, resulting in subsequent regulation of the synthesis of TAG and unsaturated fatty acids.
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Affiliation(s)
- Peixin Jiao
- College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China; (P.J.); (M.Z.); (Z.W.); (G.L.); (X.X.); (Y.Z.)
| | - Meimei Zhang
- College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China; (P.J.); (M.Z.); (Z.W.); (G.L.); (X.X.); (Y.Z.)
| | - Ziwei Wang
- College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China; (P.J.); (M.Z.); (Z.W.); (G.L.); (X.X.); (Y.Z.)
| | - Gege Liang
- College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China; (P.J.); (M.Z.); (Z.W.); (G.L.); (X.X.); (Y.Z.)
| | - Xiaolai Xie
- College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China; (P.J.); (M.Z.); (Z.W.); (G.L.); (X.X.); (Y.Z.)
| | - Yonggen Zhang
- College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China; (P.J.); (M.Z.); (Z.W.); (G.L.); (X.X.); (Y.Z.)
| | - Zhi Chen
- Jiangsu Key Laboratory of Animal Genetic Breeding and Molecular Design, College of Animal Science and Technology, Yangzhou University, Yangzhou 225009, China
- Correspondence: (Z.C.); (J.J.L.)
| | - Qianming Jiang
- Mammalian Nutrition Physiology Genomics, Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, IL 61801, USA;
| | - Juan J. Loor
- Mammalian Nutrition Physiology Genomics, Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, IL 61801, USA;
- Correspondence: (Z.C.); (J.J.L.)
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19
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The monoacylglycerol acyltransferase pathway contributes to triacylglycerol synthesis in HepG2 cells. Sci Rep 2022; 12:4943. [PMID: 35322811 PMCID: PMC8943211 DOI: 10.1038/s41598-022-08946-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 03/14/2022] [Indexed: 12/19/2022] Open
Abstract
The monoacylglycerol acyltransferase (MGAT) pathway has a well-established role in the small intestine where it facilitates the absorption of dietary fat. In enterocytes, MGAT participates in the resynthesis of triacylglycerol using substrates (monoacylglycerol and fatty acids) generated in the gut lumen from the breakdown of triacylglycerol consumed in the diet. MGAT activity is also present in the liver, but its role in triacylglycerol metabolism in this tissue remains unclear. The predominant MGAT isoforms present in human liver appear to be MGAT2 and MGAT3. The objective of this study was to use selective small molecule inhibitors of MGAT2 and MGAT3 to determine the contributions of these enzymes to triacylglycerol production in liver cells. We found that pharmacological inhibition of either enzyme had no effect on TG mass in HepG2 cells but did alter lipid droplet size and number. Inhibition of MGAT2 did result in decreased DG and TG synthesis and TG secretion. Interestingly, MGAT2 preferentially utilized 2-monoacylglycerol derived from free glycerol and not from exogenously added 2-monoacylglycerol. In contrast, inhibition of MGAT3 had very little effect on TG metabolism in HepG2 cells. Additionally, we demonstrated that the MGAT activity of DGAT1 only makes a minor contribution to TG synthesis in intact HepG2 cells. Our data demonstrated that the MGAT pathway has a role in hepatic lipid metabolism with MGAT2, more so than MGAT3, contributing to TG synthesis and secretion.
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20
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Stone SJ. Mechanisms of intestinal triacylglycerol synthesis. Biochim Biophys Acta Mol Cell Biol Lipids 2022; 1867:159151. [PMID: 35296424 DOI: 10.1016/j.bbalip.2022.159151] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 01/13/2022] [Accepted: 02/16/2022] [Indexed: 02/07/2023]
Abstract
Triacylglycerols are a major source of stored energy that are obtained either from the diet or can be synthesized to some extent by most tissues. Alterations in pathways of triacylglycerol metabolism can result in their excessive accumulation leading to obesity, insulin resistance, cardiovascular disease and nonalcoholic fatty liver disease. Most tissues in mammals synthesize triacylglycerols via the glycerol 3-phosphate pathway. However, in the small intestine the monoacylglycerol acyltransferase pathway is the predominant pathway for triacylglycerol biosynthesis where it participates in the absorption of dietary triacylglycerol. In this review, the enzymes that are part of both the glycerol 3-phosphate and monoacylglycerol acyltransferase pathways and their contributions to intestinal triacylglycerol metabolism are reviewed. The potential of some of the enzymes involved in triacylglycerol synthesis in the small intestine as possible therapeutic targets for treating metabolic disorders associated with elevated triacylglycerol is briefly discussed.
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Affiliation(s)
- Scot J Stone
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada.
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21
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Control of Cholesterol Metabolism Using a Systems Approach. BIOLOGY 2022; 11:biology11030430. [PMID: 35336806 PMCID: PMC8945167 DOI: 10.3390/biology11030430] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 03/06/2022] [Accepted: 03/08/2022] [Indexed: 11/25/2022]
Abstract
Simple Summary Cholesterol is the main sterol in mammals that is essential for healthy cell functionining. It plays a key role in metabolic regulation and signaling, it is a precursor molecule of bile acids, oxysterols, and all steroid hormones. It also contributes to the structural makeup of the membranes. Its homeostasis is tightly controlled since it can harm the body if it is allowed to reach abnormal blood concentrations. One of the diseases associated with elevated cholesterol levels being the major cause of morbidities and mortalities worldwide, is atherosclerosis. In this study, we have developed a model of the cholesterol metabolism taking into account local inflammation and oxidative stress. The aim was to investigate the impact of the interplay of those processes and cholesterol metabolism disturbances on the atherosclerosis development and progression. We have also analyzed the effect of combining different classes of drugs targeting selected components of cholesterol metabolism. Abstract Cholesterol is an essential component of mammalian cells and is involved in many fundamental physiological processes; hence, its homeostasis in the body is tightly controlled, and any disturbance has serious consequences. Disruption of the cellular metabolism of cholesterol, accompanied by inflammation and oxidative stress, promotes the formation of atherosclerotic plaques and, consequently, is one of the leading causes of death in the Western world. Therefore, new drugs to regulate disturbed cholesterol metabolism are used and developed, which help to control cholesterol homeostasis but still do not entirely cure atherosclerosis. In this study, a Petri net-based model of human cholesterol metabolism affected by a local inflammation and oxidative stress, has been created and analyzed. The use of knockout of selected pathways allowed us to observe and study the effect of various combinations of commonly used drugs on atherosclerosis. The analysis results led to the conclusion that combination therapy, targeting multiple pathways, may be a fundamental concept in the development of more effective strategies for the treatment and prevention of atherosclerosis.
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22
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McFie PJ, Chumala P, Katselis GS, Stone SJ. DGAT2 stability is increased in response to DGAT1 inhibition in gene edited HepG2 cells. Biochim Biophys Acta Mol Cell Biol Lipids 2021; 1866:158991. [PMID: 34116261 DOI: 10.1016/j.bbalip.2021.158991] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 05/21/2021] [Accepted: 06/05/2021] [Indexed: 12/14/2022]
Abstract
In eukaryotic organisms, two unrelated acyl-CoA:diacylglycerol acyltransferase (DGAT) enzymes, DGAT1 and DGAT2, catalyze the final step of the triacylglycerol biosynthetic pathway. Both enzymes are highly expressed in lipogenic tissues, such as adipose tissue, small intestine and the liver. DGAT2 has a prominent role in hepatocyte lipid metabolism synthesizing triacylglycerols that are utilized for very low-density lipoprotein assembly. However, due to the lack of useful antibodies to detect endogenous DGAT2 protein, it has been difficult to determine how this enzyme functions at the cellular level. We have unsuccessfully tested many commercial antibodies as well as our own "in-house" antibodies. There is currently no evidence that DGAT2 undergoes processing such that antigenic epitopes to these antibodies are removed. As an alternative, many studies have utilized epitope tagged versions of DGAT2 overexpressed in cells. These approaches can provide valuable information about a protein, but can be subject to artifacts, such as mislocalization, misregulation, protein aggregation and abnormal protein-protein interactions. In this study, we used gene editing with CRISPR/Cas9 to add three consecutive FLAG epitopes to the C-terminus of endogenous DGAT2 in HepG2 cells. HepG2 cells, derived from a human hepatocellular carcinoma, have been routinely used as a cell model to study human hepatocyte lipid and lipoprotein metabolism. Using this system allowed us to successfully detect DGAT2 expressed from its endogenous locus in HepG2 cells by immunoblotting with anti-FLAG antibodies.
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Affiliation(s)
- Pamela J McFie
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
| | - Paulos Chumala
- Department of Medicine and the Canadian Centre for Health and Safety in Agriculture, University of Saskatchewan, Saskatoon, Saskatchewan S7N 2Z4, Canada
| | - George S Katselis
- Department of Medicine and the Canadian Centre for Health and Safety in Agriculture, University of Saskatchewan, Saskatoon, Saskatchewan S7N 2Z4, Canada
| | - Scot J Stone
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada.
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23
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Eldredge JA, Couper MR, Barnett CP, Rawlings L, Couper RTL. New Pathogenic Mutations Associated with Diacylglycerol O-Acyltransferase 1 Deficiency. J Pediatr 2021; 233:268-272. [PMID: 33607125 DOI: 10.1016/j.jpeds.2021.02.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 02/11/2021] [Accepted: 02/12/2021] [Indexed: 11/16/2022]
Abstract
Diacylglycerol O-acyltransferase 1 deficiency is a recently discovered, rare congenital diarrheal disorder. We report 2 patients with newly described pathogenic mutations in diacylglycerol O-acyltransferase 1 with compound heterozygous inheritance and unusual phenotypes. This included a macrophage activation syndrome-like response seen in one patient, ameliorated with low dietary fat.
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Affiliation(s)
- Jessica A Eldredge
- Department of Gastroenterology, Women's & Children's Hospital, Adelaide, South Australia
| | - Michael R Couper
- Department of Gastroenterology, Women's & Children's Hospital, Adelaide, South Australia
| | - Christopher P Barnett
- Paediatric and Reproductive Genetics Unit, Women's & Children's Hospital, Adelaide, South Australia; School of Paediatrics, University of Adelaide, Adelaide, South Australia
| | - Lesley Rawlings
- Genomics Unit, Genetics & Molecular Pathology, SA Pathology, Adelaide, South Australia
| | - Richard T L Couper
- Department of Gastroenterology, Women's & Children's Hospital, Adelaide, South Australia; School of Paediatrics, University of Adelaide, Adelaide, South Australia.
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24
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Levy E, Beaulieu JF, Spahis S. From Congenital Disorders of Fat Malabsorption to Understanding Intra-Enterocyte Mechanisms Behind Chylomicron Assembly and Secretion. Front Physiol 2021; 12:629222. [PMID: 33584351 PMCID: PMC7873531 DOI: 10.3389/fphys.2021.629222] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 01/06/2021] [Indexed: 11/13/2022] Open
Abstract
During the last two decades, a large body of information on the events responsible for intestinal fat digestion and absorption has been accumulated. In particular, many groups have extensively focused on the absorptive phase in order to highlight the critical "players" and the main mechanisms orchestrating the assembly and secretion of chylomicrons (CM) as essential vehicles of alimentary lipids. The major aim of this article is to review understanding derived from basic science and clinical conditions associated with impaired packaging and export of CM. We have particularly insisted on inborn metabolic pathways in humans as well as on genetically modified animal models (recapitulating pathological features). The ultimate goal of this approach is that "experiments of nature" and in vivo model strategy collectively allow gaining novel mechanistic insight and filling the gap between the underlying genetic defect and the apparent clinical phenotype. Thus, uncovering the cause of disease contributes not only to understanding normal physiologic pathway, but also to capturing disorder onset, progression, treatment and prognosis.
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Affiliation(s)
- Emile Levy
- Research Centre, CHU Ste-Justine, Université de Montréal, Montreal, QC, Canada
- Department of Nutrition, Université de Montréal, Montreal, QC, Canada
- Department of Pediatrics, Université de Montréal, Montreal, QC, Canada
| | - Jean François Beaulieu
- Laboratory of Intestinal Physiopathology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Schohraya Spahis
- Research Centre, CHU Ste-Justine, Université de Montréal, Montreal, QC, Canada
- Department of Nutrition, Université de Montréal, Montreal, QC, Canada
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25
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Hepatic synthesis of triacylglycerols containing medium-chain fatty acids is dominated by diacylglycerol acyltransferase 1 and efficiently inhibited by etomoxir. Mol Metab 2020; 45:101150. [PMID: 33359403 PMCID: PMC7843514 DOI: 10.1016/j.molmet.2020.101150] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 12/07/2020] [Accepted: 12/16/2020] [Indexed: 11/30/2022] Open
Abstract
Objective Medium-chain fatty acids (MCFAs) play an increasing role in human nutrition. In the liver, one fraction is used for synthesis of MCFA-containing triacylglycerol (MCFA-TG), and the rest is used for oxidative energy production or ketogenesis. We investigated which enzymes catalyse the synthesis of MCFA-TG and how inhibition of MCFA-TG synthesis or fatty acid (FA) oxidation influences the metabolic fate of the MCFAs. Methods FA metabolism was followed by time-resolved tracing of alkyne-labelled FAs in freshly isolated mouse hepatocytes. Quantitative data were obtained by mass spectrometry of several hundred labelled lipid species. Wild-type hepatocytes and cells from diacylglycerol acyltransferase (DGAT)1−/− mice were treated with inhibitors against DGAT1, DGAT2, or FA β-oxidation. Results Inhibition or deletion of DGAT1 resulted in a reduction of MCFA-TG synthesis by 70%, while long-chain (LC)FA-TG synthesis was reduced by 20%. In contrast, DGAT2 inhibition increased MCFA-TG formation by 50%, while LCFA-TG synthesis was reduced by 5–25%. Inhibition of β-oxidation by the specific inhibitor teglicar strongly increased MCFA-TG synthesis. In contrast, the widely used β-oxidation inhibitor etomoxir blocked MCFA-TG synthesis, phenocopying DGAT1 inhibition. Conclusions DGAT1 is the major enzyme for hepatic MCFA-TG synthesis. Its loss can only partially be compensated by DGAT2. Specific inhibition of β-oxidation leads to a compensatory increase in MCFA-TG synthesis, whereas etomoxir blocks both β-oxidation and MCFA-TG synthesis, indicating a strong off-target effect on DGAT1.
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26
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Huang JS, Guo BB, Lin FF, Zeng LM, Wang T, Dang XY, Yang Y, Hu YH, Liu J, Wang HY. A novel low systemic diacylglycerol acyltransferase 1 inhibitor, Yhhu2407, improves lipid metabolism. Eur J Pharm Sci 2020; 158:105683. [PMID: 33347980 DOI: 10.1016/j.ejps.2020.105683] [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] [Received: 08/16/2020] [Revised: 12/11/2020] [Accepted: 12/15/2020] [Indexed: 01/27/2023]
Abstract
Diacylglycerol acyltransferase 1 (DGAT1) plays a pivotal role in lipid metabolism by catalyzing the committed step in triglyceride (TG) synthesis and has been considered as a potential therapeutic target of multiple metabolic diseases, including dyslipidemia, obesity and type 2 diabetes. Here we report a novel DGAT1 inhibitor, Yhhu2407, which showed a stronger DGAT1 inhibitory activity (IC50 = 18.24 ± 4.72 nM) than LCQ908 (IC50 = 78.24 ± 8.16 nM) in an enzymatic assay and led to a significant reduction in plasma TG after an acute lipid challenge in mice. Pharmacokinetic studies illustrated that Yhhu2407 displayed a low systemic, liver- and intestine-targeted distribution pattern, which is consistent with the preferential tissue expression pattern of DGAT1 and therefore might help to maximize the beneficial pharmacological effects and prevent the occurrence of side effects. Cell-based investigations demonstrated that Yhhu2407 inhibited free fatty acid (FFA)-induced TG accumulation and apolipoprotein B (ApoB)-100 secretion in HepG2 cells. In vivo study also disclosed that Yhhu2407 exerted a beneficial effect on regulating plasma TG and lipoprotein levels in rats, and effectively ameliorated high-fat diet (HFD)-induced dyslipidemia in hamsters. In conclusion, we identified Yhhu2407 as a novel DGAT1 inhibitor with potent efficacy on improving lipid metabolism in rats and HFD-fed hamsters without causing obvious adverse effects.
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Affiliation(s)
- Jun-Shang Huang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Bin-Bin Guo
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Fei-Fei Lin
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Li-Min Zeng
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Ting Wang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Xiang-Yu Dang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Yang Yang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - You-Hong Hu
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Jia Liu
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
| | - He-Yao Wang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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27
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Vujić N, Korbelius M, Sachdev V, Rainer S, Zimmer A, Huber A, Radović B, Kratky D. Intestine-specific DGAT1 deficiency improves atherosclerosis in apolipoprotein E knockout mice by reducing systemic cholesterol burden. Atherosclerosis 2020; 310:26-36. [PMID: 32882484 PMCID: PMC7116265 DOI: 10.1016/j.atherosclerosis.2020.07.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 06/25/2020] [Accepted: 07/31/2020] [Indexed: 12/17/2022]
Abstract
Background and aims Acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) is the rate-limiting enzyme catalyzing the final step of triglyceride synthesis by esterifying a diglyceride with a fatty acid. We have previously shown that apolipoprotein E-knockout (ApoE−/−) mice lacking Dgat1 have reduced intestinal cholesterol absorption and potentiated macrophage cholesterol efflux, and consequently, exhibit attenuated atherogenesis. However, he-matopoietic Dgat1 deficiency lacked beneficial effects on atherosclerosis. Due to our recent results on the critical role of intestinal Dgat1 in murine cholesterol homeostasis, we delineated whether intestinal Dgat1 deficiency regulates atherogenesis in mice. Methods We generated intestine-specific Dgat1−/− mice on the ApoE−/− background (iDgat1−/−ApoE−/−) and determined cholesterol homeostasis and atherosclerosis development. Results When fed a Western-type diet, iDgat1−/−ApoE−/− mice exhibited a substantial decrease in fasting plasma cholesterol content in ApoB-containing lipoproteins. Although lipid absorption was delayed, iDgat1−/−ApoE−/− mice had reduced acute and fractional cholesterol absorption coupled with an elevated fecal caloric loss. In line, increased appearance of i.v. administered [3H]cholesterol in duodena and stool of iDgat1−/−ApoE−/− animals suggested potentiated cholesterol elimination. Atherosclerotic lesions were markedly smaller with beneficial alterations in plaque composition as evidenced by reduced macrophage infiltration and necrotic core size despite unaltered collagen content, indicating improved plaque stability. Conclusions Disruption of Dgat1 activity solely in the small intestine of ApoE−/− mice strongly decreased plasma cholesterol levels by abrogating the assimilation of dietary cholesterol, partly by reduced absorption and increased excretion. Consequently, the reduced cholesterol burden significantly attenuated atherogenesis and improved the lesion phenotype in iDgat1−/−ApoE−/− mice.
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Affiliation(s)
- Nemanja Vujić
- Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria; BioTechMed-Graz, Graz, Austria
| | - Melanie Korbelius
- Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria; BioTechMed-Graz, Graz, Austria
| | - Vinay Sachdev
- Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Silvia Rainer
- Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Andreas Zimmer
- Institute of Pharmaceutical Sciences, University of Graz, Graz, Austria; BioTechMed-Graz, Graz, Austria
| | - Anton Huber
- Institute of Chemistry, University of Graz, Graz, Austria
| | - Branislav Radović
- Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria; BioTechMed-Graz, Graz, Austria
| | - Dagmar Kratky
- Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria; BioTechMed-Graz, Graz, Austria.
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28
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Takemoto K, Fukasaka Y, Yoshimoto R, Nambu H, Yukioka H. Diacylglycerol acyltransferase 1/2 inhibition induces dysregulation of fatty acid metabolism and leads to intestinal barrier failure and diarrhea in mice. Physiol Rep 2020; 8:e14542. [PMID: 32786057 PMCID: PMC7422801 DOI: 10.14814/phy2.14542] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 07/19/2020] [Accepted: 07/20/2020] [Indexed: 02/06/2023] Open
Abstract
The intestinal metabolism and transport of triacylglycerol (TAG) play a critical role in dietary TAG absorption, and defects in the process are associated with congenital diarrhea. The final reaction in TAG synthesis is catalyzed by diacylglycerol acyltransferase (DGAT1 and DGAT2), which uses activated fatty acids (FA) as substrates. Loss-of-function mutations in DGAT1 cause watery diarrhea in humans, but mechanisms underlying the relationship between altered DGAT activity and diarrhea remain largely unclear. Here, the effects of DGAT1 and DGAT2 inhibition, alone or in combination, on dietary TAG absorption and diarrhea in mice were investigated by using a selective DGAT1 inhibitor (PF-04620110) and DGAT2 inhibitor (PF-06424439). Simultaneous administration of a single dosing of these inhibitors drastically decreased intestinal TAG secretion into the blood circulatory system and TAG accumulation in the duodenum at 60 min after lipid gavage. Under 60% high-fat diet (HFD) feeding, their repeated simultaneous administration for 2 days induced severe watery diarrhea and occasionally led to death. The diarrhea was accompanied by enhanced fecal FA excretion, intestinal injury and barrier failure. DGAT1 or DGAT2 inhibition alone did not induce the phenotypic changes observed in DGAT1/2 inhibitor-treated mice. The results demonstrate that DGAT1/2 inhibition alters TAG absorption and results in watery diarrhea in mice. DGAT1/2 inhibition-induced diarrhea may be caused by intestinal barrier dysfunction due to dysregulation of the cytotoxic FA metabolism. These findings suggest that DGAT-mediated intestinal TAG synthesis is a vital step for maintaining intestinal barrier integrity under HFD feeding.
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Affiliation(s)
- Kosuke Takemoto
- Drug Discovery & Disease Research LaboratoryShionogi & Co., LtdOsakaJapan
- Laboratory of Veterinary Pathology, Joint Faculty of Veterinary MedicineYamaguchi UniversityYamaguchiJapan
| | - Yumiko Fukasaka
- Drug Discovery & Disease Research LaboratoryShionogi & Co., LtdOsakaJapan
| | - Ryo Yoshimoto
- Drug Discovery & Disease Research LaboratoryShionogi & Co., LtdOsakaJapan
| | - Hirohide Nambu
- Drug Discovery & Disease Research LaboratoryShionogi & Co., LtdOsakaJapan
| | - Hideo Yukioka
- Drug Discovery & Disease Research LaboratoryShionogi & Co., LtdOsakaJapan
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29
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Hoa Chung L, Qi Y. Lipodystrophy - A Rare Condition with Serious Metabolic Abnormalities. Rare Dis 2020. [DOI: 10.5772/intechopen.88667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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30
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Taïb B, Aboussalah AM, Moniruzzaman M, Chen S, Haughey NJ, Kim SF, Ahima RS. Lipid accumulation and oxidation in glioblastoma multiforme. Sci Rep 2019; 9:19593. [PMID: 31863022 PMCID: PMC6925201 DOI: 10.1038/s41598-019-55985-z] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 11/29/2019] [Indexed: 01/07/2023] Open
Abstract
Glioblastoma multiforme (GBM) is the most common and lethal primary malignant brain tumor in adults. Despite the multimodal standard treatments for GBM, the median survival is still about one year. Analysis of brain tissues from GBM patients shows that lipid droplets are highly enriched in tumor tissues while undetectable in normal brain tissues, yet the identity and functions of lipid species in GBM are not well understood. The aims of the present work are to determine how GBM utilizes fatty acids, and assess their roles in GBM proliferation. Treatment of U138 GBM cells with a monounsaturated fatty acid, oleic acid, induces accumulation of perilipin 2-coated lipid droplets containing triglycerides enriched in C18:1 fatty acid, and increases fatty acid oxidation. Interestingly, oleic acid also increases glucose utilization and proliferation of GBM cells. In contrast, pharmacologic inhibition of monoacylglycerol lipase attenuates GBM proliferation. Our findings demonstrate that monounsaturated fatty acids promote GBM proliferation via triglyceride metabolism, suggesting a novel lipid droplet-mediated pathway which may be targeted for GBM treatment.
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Affiliation(s)
- Bouchra Taïb
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, Johns Hopkins University, Baltimore, Maryland, USA
| | - Amine M Aboussalah
- Department of Mechanical & Industrial Engineering, University of Toronto, Toronto, Canada
| | | | - Suming Chen
- Department of Neurology, Johns Hopkins University, Baltimore, Maryland, USA
| | - Norman J Haughey
- Department of Neurology, Johns Hopkins University, Baltimore, Maryland, USA
| | - Sangwon F Kim
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, Johns Hopkins University, Baltimore, Maryland, USA
- Department of Neuroscience, Johns Hopkins University, Baltimore, Maryland, USA
| | - Rexford S Ahima
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, Johns Hopkins University, Baltimore, Maryland, USA.
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31
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Florentin M, Kostapanos MS, Anagnostis P, Liamis G. Recent developments in pharmacotherapy for hypertriglyceridemia: what’s the current state of the art? Expert Opin Pharmacother 2019; 21:107-120. [PMID: 31738617 DOI: 10.1080/14656566.2019.1691523] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Matilda Florentin
- Department of Internal Medicine, School of Medicine, University of Ioannina, Ioannina, Greece
| | - Michael S Kostapanos
- Lipid clinic, Department of General Medicine, Addenbrooke’s Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Panagiotis Anagnostis
- Unit of reproductive endocrinology, 1st Department of Obstetrics and Gynecology, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - George Liamis
- Department of Internal Medicine, School of Medicine, University of Ioannina, Ioannina, Greece
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32
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van Rijn JM, van Hoesel M, de Heus C, van Vugt AHM, Klumperman J, Nieuwenhuis EES, Houwen RHJ, Middendorp S. DGAT2 partially compensates for lipid-induced ER stress in human DGAT1-deficient intestinal stem cells. J Lipid Res 2019; 60:1787-1800. [PMID: 31315900 DOI: 10.1194/jlr.m094201] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 07/17/2019] [Indexed: 12/16/2022] Open
Abstract
Dietary lipids are taken up as FAs by the intestinal epithelium and converted by diacylglycerol acyltransferase (DGAT) enzymes into triglycerides, which are packaged in chylomicrons or stored in cytoplasmic lipid droplets (LDs). DGAT1-deficient patients suffer from vomiting, diarrhea, and protein losing enteropathy, illustrating the importance of this process to intestinal homeostasis. Previously, we have shown that DGAT1 deficiency causes decreased LD formation and resistance to unsaturated FA lipotoxicity in patient-derived intestinal organoids. However, LD formation was not completely abolished in patient-derived organoids, suggesting the presence of an alternative mechanism for LD formation. Here, we show an unexpected role for DGAT2 in lipid metabolism, as DGAT2 partially compensates for LD formation and lipotoxicity in DGAT1-deficient intestinal stem cells. Furthermore, we show that (un)saturated FA-induced lipotoxicity is mediated by ER stress. More importantly, we demonstrate that overexpression of DGAT2 fully compensates for the loss of DGAT1 in organoids, indicating that induced DGAT2 expression in patient cells may serve as a therapeutic target in the future.
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Affiliation(s)
- Jorik M van Rijn
- Division of Pediatrics, Department of Pediatric Gastroenterology, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands.,Regenerative Medicine Center, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Marliek van Hoesel
- Division of Pediatrics, Department of Pediatric Gastroenterology, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands.,Regenerative Medicine Center, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Cecilia de Heus
- Department of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Anke H M van Vugt
- Division of Pediatrics, Department of Pediatric Gastroenterology, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands.,Regenerative Medicine Center, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Judith Klumperman
- Department of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Edward E S Nieuwenhuis
- Division of Pediatrics, Department of Pediatric Gastroenterology, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Roderick H J Houwen
- Division of Pediatrics, Department of Pediatric Gastroenterology, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Sabine Middendorp
- Division of Pediatrics, Department of Pediatric Gastroenterology, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands .,Regenerative Medicine Center, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
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33
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Zhang X, Zhang CC, Yang H, Soni KG, Wang SP, Mitchell GA, Wu JW. An Epistatic Interaction between Pnpla2 and Lipe Reveals New Pathways of Adipose Tissue Lipolysis. Cells 2019; 8:cells8050395. [PMID: 31035700 PMCID: PMC6563012 DOI: 10.3390/cells8050395] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 04/17/2019] [Accepted: 04/23/2019] [Indexed: 12/20/2022] Open
Abstract
White adipose tissue (WAT) lipolysis contributes to energy balance during fasting. Lipolysis can proceed by the sequential hydrolysis of triglycerides (TGs) by adipose triglyceride lipase (ATGL), then of diacylglycerols (DGs) by hormone-sensitive lipase (HSL). We showed that the combined genetic deficiency of ATGL and HSL in mouse adipose tissue produces a striking different phenotype from that of isolated ATGL deficiency, inconsistent with the linear model of lipolysis. We hypothesized that the mechanism might be functional redundancy between ATGL and HSL. To test this, the TG hydrolase activity of HSL was measured in WAT. HSL showed TG hydrolase activity. Then, to test ATGL for activity towards DGs, radiolabeled DGs were incubated with HSL-deficient lipid droplet fractions. The content of TG increased, suggesting DG-to-TG synthesis rather than DG hydrolysis. TG synthesis was abolished by a specific ATGL inhibitor, suggesting that ATGL functions as a transacylase when HSL is deficient, transferring an acyl group from one DG to another, forming a TG plus a monoglyceride (MG) that could be hydrolyzed by monoglyceride lipase. These results reveal a previously unknown physiological redundancy between ATGL and HSL, a mechanism for the epistatic interaction between Pnpla2 and Lipe. It provides an alternative lipolytic pathway, potentially important in patients with deficient lipolysis.
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Affiliation(s)
- Xiao Zhang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling 712100, China.
| | - Cong Cong Zhang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling 712100, China.
| | - Hao Yang
- Division of Medical Genetics, Department of Pediatrics, Université de Montréal and CHU Sainte-Justine, 3175 Côte Sainte-Catherine, Montreal, QC H3T 1C5, Canada.
| | - Krishnakant G Soni
- Section of Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, Baylor College of Medicine and Texas Children's Hospital, Houston, TX 77030, USA.
| | - Shu Pei Wang
- Division of Medical Genetics, Department of Pediatrics, Université de Montréal and CHU Sainte-Justine, 3175 Côte Sainte-Catherine, Montreal, QC H3T 1C5, Canada.
| | - Grant A Mitchell
- Division of Medical Genetics, Department of Pediatrics, Université de Montréal and CHU Sainte-Justine, 3175 Côte Sainte-Catherine, Montreal, QC H3T 1C5, Canada.
| | - Jiang Wei Wu
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling 712100, China.
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Esler WP, Bence KK. Metabolic Targets in Nonalcoholic Fatty Liver Disease. Cell Mol Gastroenterol Hepatol 2019; 8:247-267. [PMID: 31004828 PMCID: PMC6698700 DOI: 10.1016/j.jcmgh.2019.04.007] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 04/09/2019] [Accepted: 04/11/2019] [Indexed: 12/18/2022]
Abstract
The prevalence and diagnosis of nonalcoholic fatty liver disease (NAFLD) is on the rise worldwide and currently has no FDA-approved pharmacotherapy. The increase in disease burden of NAFLD and a more severe form of this progressive liver disease, nonalcoholic steatohepatitis (NASH), largely mirrors the increase in obesity and type 2 diabetes (T2D) and reflects the hepatic manifestation of an altered metabolic state. Indeed, metabolic syndrome, defined as a constellation of obesity, insulin resistance, hyperglycemia, dyslipidemia and hypertension, is the major risk factor predisposing the NAFLD and NASH. There are multiple potential pharmacologic strategies to rebalance aspects of disordered metabolism in NAFLD. These include therapies aimed at reducing hepatic steatosis by directly modulating lipid metabolism within the liver, inhibiting fructose metabolism, altering delivery of free fatty acids from the adipose to the liver by targeting insulin resistance and/or adipose metabolism, modulating glycemia, and altering pleiotropic metabolic pathways simultaneously. Emerging data from human genetics also supports a role for metabolic drivers in NAFLD and risk for progression to NASH. In this review, we highlight the prominent metabolic drivers of NAFLD pathogenesis and discuss the major metabolic targets of NASH pharmacotherapy.
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Key Words
- acc, acetyl-coa carboxylase
- alt, alanine aminotransferase
- aso, anti-sense oligonucleotide
- ast, aspartate aminotransferase
- chrebp, carbohydrate response element binding protein
- ci, confidence interval
- dgat, diacylglycerol o-acyltransferase
- dnl, de novo lipogenesis
- fas, fatty acid synthase
- ffa, free fatty acid
- fgf, fibroblast growth factor
- fxr, farnesoid x receptor
- glp-1, glucagon-like peptide-1
- hdl, high-density lipoprotein
- homa-ir, homeostatic model assessment of insulin resistance
- ldl, low-density lipoprotein
- nafld, nonalcoholic fatty liver disease
- nas, nonalcoholic fatty liver disease activity score
- nash, nonalcoholic steatohepatitis
- or, odds ratio
- pdff, proton density fat fraction
- ppar, peroxisome proliferator-activated receptor
- sglt2, sodium glucose co-transporter 2
- srebp-1c, sterol regulatory element binding protein-1c
- t2d, type 2 diabetes
- t2dm, type 2 diabetes mellitus
- tg, triglyceride
- th, thyroid hormone
- thr, thyroid hormone receptor
- treg, regulatory t cells
- tzd, thiazolidinedione
- vldl, very low-density lipoprotein
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Affiliation(s)
- William P Esler
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, Massachusetts
| | - Kendra K Bence
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, Massachusetts.
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Morentin Gutierrez P, Yates J, Nilsson C, Birtles S. Evolving data analysis of an Oral Lipid Tolerance Test toward the standard for the Oral Glucose Tolerance Test: Cross species modeling effects of AZD7687 on plasma triacylglycerol. Pharmacol Res Perspect 2019; 7:e00465. [PMID: 30899516 PMCID: PMC6408865 DOI: 10.1002/prp2.465] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 12/03/2018] [Accepted: 12/28/2018] [Indexed: 12/28/2022] Open
Abstract
We have developed a novel mechanistic pharmacokinetic-pharmacodynamic (PK/PD) model to describe the time course of plasma triglyceride (TAG) after Oral Lipid Tolerance Test (OLTT) and the effects of AZD7687, an inhibitor of diacylglycerol acyltransferase 1 (DGAT1), in humans, rats, and mice. Pharmacokinetic and plasma TAG data were obtained both in animals and in two phase I OLTT studies. In the PK/PD model, the introduction of exogenous TAG is represented by a first order process. The endogenous production and removal of TAG from plasma are described with a turnover model. AZD7687 inhibits the contribution of exogenous TAG into circulation. One or two compartment models with first order absorption was used to describe the PK of AZD7687 for the different species. Nonlinear mixed effect modeling was used to fit the model to the data. The effects of AZD7687 on the plasma TAG time course during an OLTT as well as interindividual variability were well described by the model in all three species. Meal fat content or data from single vs repeated dosing did not affect model parameter estimates. Body mass index was found to be a significant covariate on the plasma TAG baseline. The system parameters of the model will facilitate analysis for other compounds and provide tools to bring the standard of OLTT data analysis closer to the analyses of Oral Glucose Tolerance Test data maximizing knowledge gain.
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Affiliation(s)
| | - James Yates
- AstraZeneca R&DIMEDDMPKChesterford Science ParkUK
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Cao H. Identification of the major diacylglycerol acyltransferase mRNA in mouse adipocytes and macrophages. BMC BIOCHEMISTRY 2018; 19:11. [PMID: 30547742 PMCID: PMC6293574 DOI: 10.1186/s12858-018-0103-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 12/06/2018] [Indexed: 01/09/2023]
Abstract
Background Triacylglycerols (TAGs) are the major form of energy storage in eukaryotes. Diacylglycerol acyltransferases (DGATs) catalyze the final and rate-limiting step of TAG biosynthesis. Mammalian DGATs are classified into DGAT1 and DGAT2 subfamilies. It was unclear which DGAT was the major isoform expressed in animal cells. The objective was to identify the major DGAT mRNA expressed in cultured mouse adipocytes and macrophages and compared it to that expressed in tung tree seeds. Methods qPCR evaluated DGAT mRNA levels in mouse 3 T3-L1 adipocytes and RAW264.7 macrophages and tung tree seeds. Results TaqMan qPCR showed that DGAT2 mRNA levels were 10–30 fold higher than DGAT1 in adipocytes and macrophages, and DGAT mRNA levels in adipocytes were 50–100-fold higher than those in macrophages. In contrast, the anti-inflammatory tristetraprolin/zinc finger protein 36 (TTP/ZFP36) mRNA levels were 2–4-fold higher in macrophages than those in adipocytes and similar to DGAT1 in adipocytes but 100-fold higher than DGAT1 in macrophages. SYBR Green qPCR analyses confirmed TaqMan qPCR results. DGAT2 mRNA as the major DGAT mRNA in the mouse cells was similar to that in tung tree seeds where DGAT2 mRNA levels were 10–20-fold higher than DGAT1 or DGAT3. Conclusion The results demonstrated that DGAT2 mRNA was the major form of DGAT mRNA expressed in mouse adipocytes and macrophages and tung tree seeds.
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Affiliation(s)
- Heping Cao
- U.S. Department of Agriculture, Agricultural Research Service, Southern Regional Research Center, New Orleans, LA, 70124, USA.
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Zhang P, Csaki LS, Ronquillo E, Baufeld LJ, Lin JY, Gutierrez A, Dwyer JR, Brindley DN, Fong LG, Tontonoz P, Young SG, Reue K. Lipin 2/3 phosphatidic acid phosphatases maintain phospholipid homeostasis to regulate chylomicron synthesis. J Clin Invest 2018; 129:281-295. [PMID: 30507612 DOI: 10.1172/jci122595] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 10/09/2018] [Indexed: 12/31/2022] Open
Abstract
The lipin phosphatidic acid phosphatase (PAP) enzymes are required for triacylglycerol (TAG) synthesis from glycerol 3-phosphate in most mammalian tissues. The 3 lipin proteins (lipin 1, lipin 2, and lipin 3) each have PAP activity, but have distinct tissue distributions, with lipin 1 being the predominant PAP enzyme in many metabolic tissues. One exception is the small intestine, which is unique in expressing exclusively lipin 2 and lipin 3. TAG synthesis in small intestinal enterocytes utilizes 2-monoacylglycerol and does not require the PAP reaction, making the role of lipin proteins in enterocytes unclear. Enterocyte TAGs are stored transiently as cytosolic lipid droplets or incorporated into lipoproteins (chylomicrons) for secretion. We determined that lipin enzymes are critical for chylomicron biogenesis, through regulation of membrane phospholipid composition and association of apolipoprotein B48 with nascent chylomicron particles. Lipin 2/3 deficiency caused phosphatidic acid accumulation and mammalian target of rapamycin complex 1 (mTORC1) activation, which were associated with enhanced protein levels of a key phospholipid biosynthetic enzyme (CTP:phosphocholine cytidylyltransferase α) and altered membrane phospholipid composition. Impaired chylomicron synthesis in lipin 2/3 deficiency could be rescued by normalizing phospholipid synthesis levels. These data implicate lipin 2/3 as a control point for enterocyte phospholipid homeostasis and chylomicron biogenesis.
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Affiliation(s)
- Peixiang Zhang
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Lauren S Csaki
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Emilio Ronquillo
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Lynn J Baufeld
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Jason Y Lin
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Alexis Gutierrez
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Jennifer R Dwyer
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - David N Brindley
- Signal Transduction Research Group, Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Loren G Fong
- Department of Medicine, Division of Cardiology, and
| | - Peter Tontonoz
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.,Molecular Biology Institute, UCLA, Los Angeles, California, USA
| | - Stephen G Young
- Department of Medicine, Division of Cardiology, and.,Molecular Biology Institute, UCLA, Los Angeles, California, USA
| | - Karen Reue
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.,Molecular Biology Institute, UCLA, Los Angeles, California, USA
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Hung YH, Buhman KK. DGAT1 deficiency disrupts lysosome function in enterocytes during dietary fat absorption. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1864:587-595. [PMID: 30342099 DOI: 10.1016/j.bbalip.2018.10.007] [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: 05/08/2018] [Revised: 09/27/2018] [Accepted: 10/13/2018] [Indexed: 11/25/2022]
Abstract
Enterocytes, the absorptive cells of the small intestine, mediate the process of dietary fat absorption by secreting triacylglycerol (TAG) into circulation. When levels of dietary fat are high, TAG is stored in cytoplasmic lipid droplets (CLDs) and sequentially hydrolyzed for ultimate secretion. Mice with deficiency in acyl CoA: diacylglycerol acyltransferase 1 (Dgat1-/- mice) were previously reported to have a reduced rate of intestinal TAG secretion and abnormal TAG accumulation in enterocyte CLDs. This unique intestinal phenotype is critical to their resistance to diet-induced obesity; however, the underlying mechanism remains unclear. Emerging evidence shows that lysosomal TAG hydrolysis contributes to autophagy-mediated CLD mobilization termed lipophagy, and when disrupted results in CLD accumulation. In order to study how lipophagy contributes to the unique intestinal phenotype of Dgat1-/- mice, enterocytes from wild-type (WT) and Dgat1-/- mice were examined at 2 and 6 h after oral oil gavage. Through ultrastructural analysis we observed TAG present within autophagic vesicles (AVs) in mouse enterocytes, suggesting the role of lipophagy in intestinal CLD mobilization during dietary fat absorption. Furthermore, we found that Dgat1-/- mice had abnormal TAG accumulation within AVs and less acidic lysosomes compared to WT mice. Together these findings suggest that the delayed dietary fat absorption seen in Dgat1-/- mice is, in part, due to the dysregulated flux of autophagy-mediated CLD mobilization and impairment of lysosomal acidification in enterocytes. The present study highlights the critical role of lysosome in enterocyte CLD mobilization for proper dietary fat absorption.
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Affiliation(s)
- Yu-Han Hung
- Department of Nutrition Science, Purdue University, West Lafayette, IN, United States of America
| | - Kimberly K Buhman
- Department of Nutrition Science, Purdue University, West Lafayette, IN, United States of America.
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Chae YJ, Song JS, Ahn JH, Bae MA, Lee KR. Model-based pharmacokinetic and pharmacodynamic analysis for acute effects of a small molecule inhibitor of diacylglycerol acyltransferase-1 in the TallyHo/JngJ polygenic mouse. Xenobiotica 2018; 49:823-832. [PMID: 29972081 DOI: 10.1080/00498254.2018.1496303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
The purpose of this study was to evaluate the acute effect of a small molecule inhibitor of DGAT-1 on triglycerides (TG) and cholesterol in polygenic type 2 diabetic TallyHo/JngJ (TH) mice. PF-04620110, a potent and selective DGAT-1 inhibitor, was used as a model compound in this study and which was administered to TH and ICR mice. The concentration of the model compound that produced 50% of maximum lowering of TG level (IC50) in TH mice was not significantly different from that in ICR mice, when estimated using the model-based pharmacokinetic and pharmacodynamic assay, a two-compartmental model and an indirect response model. The clearance of the inhibitor in TH mice was fivefold higher than that in ICR mice, suggesting significantly altered pharmacokinetics. Moreover, the in vitro metabolic elimination kinetic parameters (ke,met), determined using liver microsomes from TH and ICR mice were 1.24 ± 0.14 and 0.174 ± 0.116 min-1, respectively. Thus, we report that the differences in the acute effects of the small molecule DAGT-1 inhibitor between TH mice and ICR mice can be attributed to altered pharmacokinetics caused by an altered metabolic rate for the compound in TH mice.
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Affiliation(s)
- Yoon-Jee Chae
- a CKD Research Institute , Gyeonggi-do, Republic of Korea
| | - Jin Sook Song
- b Bio & Drug Discovery Division , Korea Research Institute of Chemical Technology , Daejeon , Republic of Korea
| | - Jin Hee Ahn
- c Department of Chemistry , Gwangju Institute of Science and Technology , Gwangju , Republic of Korea
| | - Myung Ae Bae
- b Bio & Drug Discovery Division , Korea Research Institute of Chemical Technology , Daejeon , Republic of Korea.,d Department of Medicinal Chemistry and Pharmacology , University of Science & Technology , Daejeon , Republic of Korea
| | - Kyeong-Ryoon Lee
- e Laboratory Animal Resource Center, Korea Research Institute of Bioscience and Biotechnology , Chungbuk , Republic of Korea
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40
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van Rijn JM, Ardy RC, Kuloğlu Z, Härter B, van Haaften-Visser DY, van der Doef HP, van Hoesel M, Kansu A, van Vugt AH, Thian M, Kokke FT, Krolo A, Başaran MK, Kaya NG, Aksu AÜ, Dalgıç B, Ozcay F, Baris Z, Kain R, Stigter EC, Lichtenbelt KD, Massink MP, Duran KJ, Verheij JB, Lugtenberg D, Nikkels PG, Brouwer HG, Verkade HJ, Scheenstra R, Spee B, Nieuwenhuis EE, Coffer PJ, Janecke AR, van Haaften G, Houwen RH, Müller T, Middendorp S, Boztug K. Intestinal Failure and Aberrant Lipid Metabolism in Patients With DGAT1 Deficiency. Gastroenterology 2018; 155:130-143.e15. [PMID: 29604290 PMCID: PMC6058035 DOI: 10.1053/j.gastro.2018.03.040] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 03/19/2018] [Accepted: 03/22/2018] [Indexed: 12/20/2022]
Abstract
BACKGROUND & AIMS Congenital diarrheal disorders are rare inherited intestinal disorders characterized by intractable, sometimes life-threatening, diarrhea and nutrient malabsorption; some have been associated with mutations in diacylglycerol-acyltransferase 1 (DGAT1), which catalyzes formation of triacylglycerol from diacylglycerol and acyl-CoA. We investigated the mechanisms by which DGAT1 deficiency contributes to intestinal failure using patient-derived organoids. METHODS We collected blood samples from 10 patients, from 6 unrelated pedigrees, who presented with early-onset severe diarrhea and/or vomiting, hypoalbuminemia, and/or (fatal) protein-losing enteropathy with intestinal failure; we performed next-generation sequencing analysis of DNA from 8 patients. Organoids were generated from duodenal biopsies from 3 patients and 3 healthy individuals (controls). Caco-2 cells and patient-derived dermal fibroblasts were transfected or transduced with vectors that express full-length or mutant forms of DGAT1 or full-length DGAT2. We performed CRISPR/Cas9-guided disruption of DGAT1 in control intestinal organoids. Cells and organoids were analyzed by immunoblot, immunofluorescence, flow cytometry, chromatography, quantitative real-time polymerase chain reaction, and for the activity of caspases 3 and 7. RESULTS In the 10 patients, we identified 5 bi-allelic loss-of-function mutations in DGAT1. In patient-derived fibroblasts and organoids, the mutations reduced expression of DGAT1 protein and altered triacylglycerol metabolism, resulting in decreased lipid droplet formation after oleic acid addition. Expression of full-length DGAT2 in patient-derived fibroblasts restored formation of lipid droplets. Organoids derived from patients with DGAT1 mutations were more susceptible to lipid-induced cell death than control organoids. CONCLUSIONS We identified a large cohort of patients with congenital diarrheal disorders with mutations in DGAT1 that reduced expression of its product; dermal fibroblasts and intestinal organoids derived from these patients had altered lipid metabolism and were susceptible to lipid-induced cell death. Expression of full-length wildtype DGAT1 or DGAT2 restored normal lipid metabolism in these cells. These findings indicate the importance of DGAT1 in fat metabolism and lipotoxicity in the intestinal epithelium. A fat-free diet might serve as the first line of therapy for patients with reduced DGAT1 expression. It is important to identify genetic variants associated with congenital diarrheal disorders for proper diagnosis and selection of treatment strategies.
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Affiliation(s)
- Jorik M. van Rijn
- Division of Pediatrics, Department of Pediatric Gastroenterology, Wilhelmina Children’s Hospital, Utrecht University, Utrecht, The Netherlands,Regenerative Medicine Center, Utrecht University, Utrecht, The Netherlands
| | - Rico Chandra Ardy
- Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases, Vienna, Austria,CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Zarife Kuloğlu
- Department of Pediatric Gastroenterology, Ankara University School of Medicine, Ankara, Turkey
| | - Bettina Härter
- Division of Paediatric Surgery, Department of Visceral, Transplant and Thoracic Surgery, Center of Operative Medicine, Innsbruck, Austria
| | - Désirée Y. van Haaften-Visser
- Division of Pediatrics, Department of Pediatric Gastroenterology, Wilhelmina Children’s Hospital, Utrecht University, Utrecht, The Netherlands,Regenerative Medicine Center, Utrecht University, Utrecht, The Netherlands
| | - Hubert P.J. van der Doef
- Department of Pediatric Gastroenterology and Hepatology, University Medical Center Groningen, Groningen, The Netherlands
| | - Marliek van Hoesel
- Division of Pediatrics, Department of Pediatric Gastroenterology, Wilhelmina Children’s Hospital, Utrecht University, Utrecht, The Netherlands,Regenerative Medicine Center, Utrecht University, Utrecht, The Netherlands
| | - Aydan Kansu
- Department of Pediatric Gastroenterology, Ankara University School of Medicine, Ankara, Turkey
| | - Anke H.M. van Vugt
- Division of Pediatrics, Department of Pediatric Gastroenterology, Wilhelmina Children’s Hospital, Utrecht University, Utrecht, The Netherlands,Regenerative Medicine Center, Utrecht University, Utrecht, The Netherlands
| | - Marini Thian
- Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases, Vienna, Austria,CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Freddy T.M. Kokke
- Division of Pediatrics, Department of Pediatric Gastroenterology, Wilhelmina Children’s Hospital, Utrecht University, Utrecht, The Netherlands
| | - Ana Krolo
- Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases, Vienna, Austria,CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Meryem Keçeli Başaran
- Pediatric Gastroenterology Department, Akdeniz University Medicine Hospital, Antalya, Turkey
| | - Neslihan Gurcan Kaya
- Department of Pediatric Gastroenterology, Gazi University School of Medicine, Ankara, Turkey
| | - Aysel Ünlüsoy Aksu
- Department of Pediatric Gastroenterology, Gazi University School of Medicine, Ankara, Turkey
| | - Buket Dalgıç
- Department of Pediatric Gastroenterology, Gazi University School of Medicine, Ankara, Turkey
| | - Figen Ozcay
- Department of Pediatric Gastroenterology, Hepatology, and Nutrition, Faculty of Medicine, Başkent University, Ankara, Turkey
| | - Zeren Baris
- Department of Pediatric Gastroenterology, Hepatology, and Nutrition, Faculty of Medicine, Başkent University, Ankara, Turkey
| | - Renate Kain
- Clinical Institute of Pathology, Medical University of Vienna, Vienna, Austria
| | - Edwin C.A. Stigter
- Molecular Cancer Research, Center Molecular Medicine, Utrecht University, Utrecht, The Netherlands
| | - Klaske D. Lichtenbelt
- Department of Medical Genetics, Center for Molecular Medicine, Utrecht University, Utrecht, The Netherlands
| | - Maarten P.G. Massink
- Department of Medical Genetics, Center for Molecular Medicine, Utrecht University, Utrecht, The Netherlands
| | - Karen J. Duran
- Department of Medical Genetics, Center for Molecular Medicine, Utrecht University, Utrecht, The Netherlands
| | - Joke B.G.M Verheij
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Dorien Lugtenberg
- Department of Human Genetics, Radboud University Nijmegen Medical Center, Nijmegen The Netherlands
| | - Peter G.J. Nikkels
- Department of Pathology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | | | - Henkjan J. Verkade
- Department of Pediatric Gastroenterology and Hepatology, University Medical Center Groningen, Groningen, The Netherlands
| | - René Scheenstra
- Department of Pediatric Gastroenterology and Hepatology, University Medical Center Groningen, Groningen, The Netherlands
| | - Bart Spee
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Sciences, Utrecht University, Utrecht, The Netherlands
| | - Edward E.S. Nieuwenhuis
- Division of Pediatrics, Department of Pediatric Gastroenterology, Wilhelmina Children’s Hospital, Utrecht University, Utrecht, The Netherlands
| | - Paul J. Coffer
- Regenerative Medicine Center, Utrecht University, Utrecht, The Netherlands
| | - Andreas R. Janecke
- Department of Pediatrics I, Medical University of Innsbruck, Innsbruck, Austria
| | - Gijs van Haaften
- Department of Medical Genetics, Center for Molecular Medicine, Utrecht University, Utrecht, The Netherlands
| | - Roderick H.J. Houwen
- Division of Pediatrics, Department of Pediatric Gastroenterology, Wilhelmina Children’s Hospital, Utrecht University, Utrecht, The Netherlands
| | - Thomas Müller
- Department of Pediatrics I, Medical University of Innsbruck, Innsbruck, Austria
| | - Sabine Middendorp
- Division of Pediatrics, Department of Pediatric Gastroenterology, Wilhelmina Children's Hospital, Utrecht University, Utrecht, The Netherlands; Regenerative Medicine Center, Utrecht University, Utrecht, The Netherlands.
| | - Kaan Boztug
- Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases, Vienna, Austria; CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria; Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria; St. Anna Kinderspital and Children's Cancer Research Institute, Department of Pediatrics, Medical University of Vienna, Vienna, Austria.
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Kim MO, Seo JH, Kwon EB, Kang MJ, Lee SU, Moon DO, Lee MK, Lee CH, Lee HS. Aceriphyllum rossii Exerts Lipid-Lowering Action in Both Normal and Hyperlipidemic Mice. Nat Prod Commun 2018. [DOI: 10.1177/1934578x1801300423] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
This study aimed to evaluate the lipid-lowering effect of the MeOH extract of Aceriphyllum rossii and its CHCl3 fraction, as well as its inhibitory activity on DGAT in vitro, in normal and hyperlipidemic mice. We separated the MeOH extract of A. rossii into two portions, a CHCl3-soluble part and the remaining water residue, and performed DGAT enzymatic activity assay on them. Further assessment carried out to reveal that the MeOH extract and its CHCl3 fraction suppress the intestinal TG absorption after an acute lipid challenge, and ameliorate hyperlipidemia as well as obesity-related parameters (body weight gain, serum lipid profiles, and several adipose tissue weights) in HFD-induced obese mice. First, the MeOH extract and its CHCl3 fraction strongly inhibit DGAT1 and DGAT2 in vitro enzymatic activity. Second, the MeOH extract and the CHCl3 fraction inhibit intestinal TG absorption after an acute lipid challenge in mice. Finally, the CHCl3 fraction ameliorates various parameters of HFD-induced obesity mice, including body weight gain and serum levels of TG and glucose. Data obtained from the results obviously indicated that A. rossii prevents HFD-induced hyperlipidemia as well as obesity in mice possibly by inhibiting DGAT activity. We suggest that A. rossii MeOH extract and its CHCl3 fraction would be a useful material for the therapy of hyperlipidemia.
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Affiliation(s)
- Mun Ock Kim
- Natural Medicine Research Center, Korea Research Institute of Bioscience and Biotechnology, 30, Yeongudanji-ro, Ochang, Cheongju, Chungbuk 28116, Republic of Korea
| | - Jee Hee Seo
- Natural Medicine Research Center, Korea Research Institute of Bioscience and Biotechnology, 30, Yeongudanji-ro, Ochang, Cheongju, Chungbuk 28116, Republic of Korea
| | - Eun Bin Kwon
- Natural Medicine Research Center, Korea Research Institute of Bioscience and Biotechnology, 30, Yeongudanji-ro, Ochang, Cheongju, Chungbuk 28116, Republic of Korea
- College of Pharmacy, Chungbuk National University, Cheongju, Chungbuk 28644, Republic of Korea
| | - Myung Ji Kang
- Natural Medicine Research Center, Korea Research Institute of Bioscience and Biotechnology, 30, Yeongudanji-ro, Ochang, Cheongju, Chungbuk 28116, Republic of Korea
- College of Pharmacy, Chungbuk National University, Cheongju, Chungbuk 28644, Republic of Korea
| | - Su Ui Lee
- Natural Medicine Research Center, Korea Research Institute of Bioscience and Biotechnology, 30, Yeongudanji-ro, Ochang, Cheongju, Chungbuk 28116, Republic of Korea
| | - Dong Oh Moon
- Department of Biology Education, Daegu University, Gyeongsan-si, Gyeongsangbuk 38453, Republic of Korea
| | - Mi Kyeong Lee
- College of Pharmacy, Chungbuk National University, Cheongju, Chungbuk 28644, Republic of Korea
| | - Chul-Ho Lee
- Laboratory Animal Center, Korea Research Institute of Bioscience and Biotechnology, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Hyun Sun Lee
- Natural Medicine Research Center, Korea Research Institute of Bioscience and Biotechnology, 30, Yeongudanji-ro, Ochang, Cheongju, Chungbuk 28116, Republic of Korea
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Maciejewski BS, Manion TB, Steppan CM. Pharmacological inhibition of diacylglycerol acyltransferase-1 and insights into postprandial gut peptide secretion. World J Gastrointest Pathophysiol 2017; 8:161-175. [PMID: 29184702 PMCID: PMC5696614 DOI: 10.4291/wjgp.v8.i4.161] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Revised: 07/25/2017] [Accepted: 09/04/2017] [Indexed: 02/06/2023] Open
Abstract
AIM To examine the role that enzyme Acyl-CoA:diacylglycerol acyltransferase-1 (DGAT1) plays in postprandial gut peptide secretion and signaling.
METHODS The standard experimental paradigm utilized to evaluate the incretin response was a lipid challenge. Following a lipid challenge, plasma was collected via cardiac puncture at each time point from a cohort of 5-8 mice per group from baseline at time zero to 10 h. Incretin hormones [glucagon like peptide-1 (GLP-1), peptide tyrosine-tyrosine (PYY) and glucose dependent insulinotropic polypeptide (GIP)] were then quantitated. The impact of pharmacological inhibition of DGAT1 on the incretin effect was evaluated in WT mice. Additionally, a comparison of loss of DGAT1 function either by genetic ablation or pharmacological inhibition. To further elucidate the pathways and mechanisms involved in the incretin response to DGAT1 inhibition, other interventions [inhibitors of dipeptidyl peptidase-IV (sitagliptin), pancreatic lipase (Orlistat), GPR119 knockout mice] were evaluated.
RESULTS DGAT1 deficient mice and wildtype C57/BL6J mice were lipid challenged and levels of both active and total GLP-1 in the plasma were increased. This response was further augmented with DGAT1 inhibitor PF-04620110 treated wildtype mice. Furthermore, PF-04620110 was able to dose responsively increase GLP-1 and PYY, but blunt GIP at all doses of PF-04620110 during lipid challenge. Combination treatment of PF-04620110 and Sitagliptin in wildtype mice during a lipid challenge synergistically enhanced postprandial levels of active GLP-1. In contrast, in a combination study with Orlistat, the ability of PF-04620110 to elicit an enhanced incretin response was abrogated. To further explore this observation, GPR119 knockout mice were evaluated. In response to a lipid challenge, GPR119 knockout mice exhibited no increase in active or total GLP-1 and PYY. However, PF-04620110 was able to increase total GLP-1 and PYY in GPR119 knockout mice as compared to vehicle treated wildtype mice.
CONCLUSION Collectively, these data provide some insight into the mechanism by which inhibition of DGAT1 enhances intestinal hormone release.
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Affiliation(s)
- Benjamin S Maciejewski
- Pfizer Worldwide Research and Development, Cardiovascular and Metabolic Diseases Research Unit, Cambridge, MA 02139, United States
| | - Tara B Manion
- Pfizer Worldwide Research and Development, Cardiovascular and Metabolic Diseases Research Unit, Cambridge, MA 02139, United States
| | - Claire M Steppan
- Pfizer Worldwide Research and Development, Cardiovascular and Metabolic Diseases Research Unit, Cambridge, MA 02139, United States
- Pfizer Inc., Groton, CT 06340, United States
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Wang H, Airola MV, Reue K. How lipid droplets "TAG" along: Glycerolipid synthetic enzymes and lipid storage. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:1131-1145. [PMID: 28642195 PMCID: PMC5688854 DOI: 10.1016/j.bbalip.2017.06.010] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 06/15/2017] [Accepted: 06/15/2017] [Indexed: 02/06/2023]
Abstract
Triacylglycerols (TAG) serve as the predominant form of energy storage in mammalian cells, and TAG synthesis influences conditions such as obesity, fatty liver, and insulin resistance. In most tissues, the glycerol 3-phosphate pathway enzymes are responsible for TAG synthesis, and the regulation and function of these enzymes is therefore important for metabolic homeostasis. Here we review the sites and regulation of glycerol-3-phosphate acyltransferase (GPAT), acylglycerol-3-phosphate acyltransferase (AGPAT), lipin phosphatidic acid phosphatase (PAP), and diacylglycerol acyltransferase (DGAT) enzyme action. We highlight the critical roles that these enzymes play in human health by reviewing Mendelian disorders that result from mutation in the corresponding genes. We also summarize the valuable insights that genetically engineered mouse models have provided into the cellular and physiological roles of GPATs, AGPATs, lipins and DGATs. Finally, we comment on the status and feasibility of therapeutic approaches to metabolic disease that target enzymes of the glycerol 3-phosphate pathway. This article is part of a Special Issue entitled: Recent Advances in Lipid Droplet Biology edited by Rosalind Coleman and Matthijs Hesselink.
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Affiliation(s)
- Huan Wang
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Michael V Airola
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, United States
| | - Karen Reue
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States; Molecular Biology Institute, University of California, Los Angeles, CA, United States.
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Chitraju C, Mejhert N, Haas JT, Diaz-Ramirez LG, Grueter CA, Imbriglio JE, Pinto S, Koliwad SK, Walther TC, Farese RV. Triglyceride Synthesis by DGAT1 Protects Adipocytes from Lipid-Induced ER Stress during Lipolysis. Cell Metab 2017; 26:407-418.e3. [PMID: 28768178 PMCID: PMC6195226 DOI: 10.1016/j.cmet.2017.07.012] [Citation(s) in RCA: 214] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 04/10/2017] [Accepted: 07/17/2017] [Indexed: 12/29/2022]
Abstract
Triglyceride (TG) storage in adipose tissue provides the major reservoir for metabolic energy in mammals. During lipolysis, fatty acids (FAs) are hydrolyzed from adipocyte TG stores and transported to other tissues for fuel. For unclear reasons, a large portion of hydrolyzed FAs in adipocytes is re-esterified to TGs in a "futile," ATP-consuming, energy dissipating cycle. Here we show that FA re-esterification during adipocyte lipolysis is mediated by DGAT1, an ER-localized DGAT enzyme. Surprisingly, this re-esterification cycle does not preserve TG mass but instead functions to protect the ER from lipotoxic stress and related consequences, such as adipose tissue inflammation. Our data reveal an important role for DGAT activity and TG synthesis generally in averting ER stress and lipotoxicity, with specifically DGAT1 performing this function during stimulated lipolysis in adipocytes.
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Affiliation(s)
- Chandramohan Chitraju
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Niklas Mejhert
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Joel T Haas
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, USA
| | | | - Carrie A Grueter
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, USA
| | | | | | - Suneil K Koliwad
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, USA; Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Tobias C Walther
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA.
| | - Robert V Farese
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA.
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45
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Hung YH, Carreiro AL, Buhman KK. Dgat1 and Dgat2 regulate enterocyte triacylglycerol distribution and alter proteins associated with cytoplasmic lipid droplets in response to dietary fat. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:600-614. [PMID: 28249764 PMCID: PMC5503214 DOI: 10.1016/j.bbalip.2017.02.014] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 01/31/2017] [Accepted: 02/24/2017] [Indexed: 12/16/2022]
Abstract
Enterocytes, the absorptive cells of the small intestine, mediate efficient absorption of dietary fat (triacylglycerol, TAG). The digestive products of dietary fat are taken up by enterocytes, re-esterified into TAG, and packaged on chylomicrons (CMs) for secretion into blood or temporarily stored within cytoplasmic lipid droplets (CLDs). Altered enterocyte TAG distribution impacts susceptibility to high fat diet associated diseases, but molecular mechanisms directing TAG toward these fates are unclear. Two enzymes, acyl CoA: diacylglycerol acyltransferase 1 (Dgat1) and Dgat2, catalyze the final, committed step of TAG synthesis within enterocytes. Mice with intestine-specific overexpression of Dgat1 (Dgat1Int) or Dgat2 (Dgat2Int), or lack of Dgat1 (Dgat1-/-), were previously found to have altered intestinal TAG secretion and storage. We hypothesized that varying intestinal Dgat1 and Dgat2 levels alters TAG distribution in subcellular pools for CM synthesis as well as the morphology and proteome of CLDs. To test this we used ultrastructural and proteomic methods to investigate intracellular TAG distribution and CLD-associated proteins in enterocytes from Dgat1Int, Dgat2Int, and Dgat1-/- mice 2h after a 200μl oral olive oil gavage. We found that varying levels of intestinal Dgat1 and Dgat2 altered TAG pools involved in CM assembly and secretion, the number or size of CLDs present in enterocytes, and the enterocyte CLD proteome. Overall, these results support a model where Dgat1 and Dgat2 function coordinately to regulate the process of dietary fat absorption by preferentially synthesizing TAG for incorporation into distinct subcellular TAG pools in enterocytes.
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Affiliation(s)
- Yu-Han Hung
- Department of Nutrition Science, Purdue University, West Lafayette, IN 47907, USA
| | - Alicia L Carreiro
- Department of Nutrition Science, Purdue University, West Lafayette, IN 47907, USA
| | - Kimberly K Buhman
- Department of Nutrition Science, Purdue University, West Lafayette, IN 47907, USA.
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46
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Abstract
The heart utilizes large amounts of fatty acids as energy providing substrates. The physiological balance of lipid uptake and oxidation prevents accumulation of excess lipids. Several processes that affect cardiac function, including ischemia, obesity, diabetes mellitus, sepsis, and most forms of heart failure lead to altered fatty acid oxidation and often also to the accumulation of lipids. There is now mounting evidence associating certain species of these lipids with cardiac lipotoxicity and subsequent myocardial dysfunction. Experimental and clinical data are discussed and paths to reduction of toxic lipids as a means to improve cardiac function are suggested.
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Affiliation(s)
- P Christian Schulze
- From the Divisions of Cardiology, Friedrich-Schiller-University Jena, Germany, and Columbia University, New York, NY (P.C.S.); Metabolic Biology Laboratory, Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA (K.D.); and Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, New York University School of Medicine, New York, NY (I.J.G.).
| | - Konstantinos Drosatos
- From the Divisions of Cardiology, Friedrich-Schiller-University Jena, Germany, and Columbia University, New York, NY (P.C.S.); Metabolic Biology Laboratory, Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA (K.D.); and Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, New York University School of Medicine, New York, NY (I.J.G.)
| | - Ira J Goldberg
- From the Divisions of Cardiology, Friedrich-Schiller-University Jena, Germany, and Columbia University, New York, NY (P.C.S.); Metabolic Biology Laboratory, Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA (K.D.); and Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, New York University School of Medicine, New York, NY (I.J.G.)
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47
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Analysis of Differentially Expressed Genes in Gastrocnemius Muscle between DGAT1 Transgenic Mice and Wild-Type Mice. BIOMED RESEARCH INTERNATIONAL 2017; 2017:5404682. [PMID: 28386555 PMCID: PMC5366756 DOI: 10.1155/2017/5404682] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 01/22/2017] [Indexed: 11/17/2022]
Abstract
Adipose tissue was the major energy deposition site of the mammals and provided the energy for the body and released the external pressure to the internal organs. In animal production, fat deposition in muscle can affect the meat quality, especially the intramuscular fat (IMF) content. Diacylglycerol acyltransferase-1 (DGAT1) was the key enzyme to control the synthesis of the triacylglycerol in adipose tissue. In order to better understand the regulation mechanism of the DGAT1 in the intramuscular fat deposition, the global gene expression profiling was performed in gastrocnemius muscle between DGAT1 transgenic mice and wild-type mice by microarray. 281 differentially expressed transcripts were identified with at least 1.5-fold change and the p value < 0.05. 169 transcripts were upregulated and 112 transcripts were downregulated. Ten genes (SREBF1, DUSP1, PLAGL1, FKBP5, ZBTB16, PPP1R3C, CDC14A, GLUL, PDK4, and UCP3) were selected to validate the reliability of the chip's results by the real-time PCR. The finding of RT-PCR was consistent with the gene chip. Seventeen signal pathways were analyzed using KEGG pathway database and the pathways concentrated mainly on the G-protein coupled receptor protein signaling pathway, signal transduction, oxidation-reduction reaction, olfactory receptor activity, protein binding, and zinc ion binding. This study implied a function role of DGAT1 in the synthesis of TAG, insulin resistance, and IMF deposition.
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48
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Senkal CE, Salama MF, Snider AJ, Allopenna JJ, Rana NA, Koller A, Hannun YA, Obeid LM. Ceramide Is Metabolized to Acylceramide and Stored in Lipid Droplets. Cell Metab 2017; 25:686-697. [PMID: 28273483 PMCID: PMC5472424 DOI: 10.1016/j.cmet.2017.02.010] [Citation(s) in RCA: 156] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 11/22/2016] [Accepted: 02/16/2017] [Indexed: 12/26/2022]
Abstract
In an approach aimed at defining interacting partners of ceramide synthases (CerSs), we found that fatty acyl-CoA synthase ACSL5 interacts with all CerSs. We demonstrate that ACSL5-generated FA-CoA was utilized with de novo ceramide for the generation of acylceramides, poorly studied ceramide metabolites. Functionally, inhibition of ceramide channeling to acylceramide enhanced accumulation of de novo ceramide and resulted in augmentation of ceramide-mediated apoptosis. Mechanistically, we show that acylceramide generation is catalyzed by diacylglycerol acyltransferase 2 (DGAT2) on lipid droplets. In summary, this study identifies a metabolic pathway of acylceramide generation and its sequestration in LDs in cells and in livers of mice on a high-fat diet. The study also implicates this pathway in ceramide-mediated apoptosis, and has implications in co-regulation of triglyceride and sphingolipid metabolisms.
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Affiliation(s)
- Can E Senkal
- Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; Stony Brook Cancer Center, Stony Brook University, Stony Brook, NY 11794, USA
| | - Mohamed F Salama
- Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; Department of Biochemistry, Faculty of Veterinary Medicine, Mansoura University, Mansoura, Dakahlia Governorate 35516, Egypt
| | - Ashley J Snider
- Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; Stony Brook Cancer Center, Stony Brook University, Stony Brook, NY 11794, USA; Northport Veterans Affairs Medical Center, Northport, NY 11768, USA
| | - Janet J Allopenna
- Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA
| | - Nadia A Rana
- Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA
| | - Antonius Koller
- Proteomics Center, Stony Brook University, Stony Brook, NY 11794, USA
| | - Yusuf A Hannun
- Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; Stony Brook Cancer Center, Stony Brook University, Stony Brook, NY 11794, USA
| | - Lina M Obeid
- Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; Stony Brook Cancer Center, Stony Brook University, Stony Brook, NY 11794, USA; Northport Veterans Affairs Medical Center, Northport, NY 11768, USA.
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49
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Overeem AW, Posovszky C, Rings EHMM, Giepmans BNG, van IJzendoorn SCD. The role of enterocyte defects in the pathogenesis of congenital diarrheal disorders. Dis Model Mech 2016; 9:1-12. [PMID: 26747865 PMCID: PMC4728335 DOI: 10.1242/dmm.022269] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Congenital diarrheal disorders are rare, often fatal, diseases that are difficult to diagnose (often requiring biopsies) and that manifest in the first few weeks of life as chronic diarrhea and the malabsorption of nutrients. The etiology of congenital diarrheal disorders is diverse, but several are associated with defects in the predominant intestinal epithelial cell type, enterocytes. These particular congenital diarrheal disorders (CDDENT) include microvillus inclusion disease and congenital tufting enteropathy, and can feature in other diseases, such as hemophagocytic lymphohistiocytosis type 5 and trichohepatoenteric syndrome. Treatment options for most of these disorders are limited and an improved understanding of their molecular bases could help to drive the development of better therapies. Recently, mutations in genes that are involved in normal intestinal epithelial physiology have been associated with different CDDENT. Here, we review recent progress in understanding the cellular mechanisms of CDDENT. We highlight the potential of animal models and patient-specific stem-cell-based organoid cultures, as well as patient registries, to integrate basic and clinical research, with the aim of clarifying the pathogenesis of CDDENT and expediting the discovery of novel therapeutic strategies. Summary: Overview of the recent progress in our understanding of congenital diarrheal disorders, and the available models to study these diseases.
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Affiliation(s)
- Arend W Overeem
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Carsten Posovszky
- Department of Pediatrics and Adolescent Medicine, University Medical Center Ulm, 89075 Ulm, Germany
| | - Edmond H M M Rings
- Department of Pediatrics, Erasmus Medical Center Rotterdam, Erasmus University Rotterdam, 3000 CB Rotterdam, The Netherlands Department of Pediatrics, Leiden University Medical Center, Leiden University, 2300 RC Leiden, The Netherlands
| | - Ben N G Giepmans
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Sven C D van IJzendoorn
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, 9713 AV Groningen, The Netherlands
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50
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Costa DK, Huckestein BR, Edmunds LR, Petersen MC, Nasiri A, Butrico GM, Abulizi A, Harmon DB, Lu C, Mantell BS, Hartman DJ, Camporez JPG, O'Doherty RM, Cline GW, Shulman GI, Jurczak MJ. Reduced intestinal lipid absorption and body weight-independent improvements in insulin sensitivity in high-fat diet-fed Park2 knockout mice. Am J Physiol Endocrinol Metab 2016; 311:E105-16. [PMID: 27166280 PMCID: PMC4967148 DOI: 10.1152/ajpendo.00042.2016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 05/06/2016] [Indexed: 12/21/2022]
Abstract
Mitochondrial dysfunction is associated with many human diseases and results from mismatch of damage and repair over the life of the organelle. PARK2 is a ubiquitin E3 ligase that regulates mitophagy, a repair mechanism that selectively degrades damaged mitochondria. Deletion of PARK2 in multiple in vivo models results in susceptibility to stress-induced mitochondrial and cellular dysfunction. Surprisingly, Park2 knockout (KO) mice are protected from nutritional stress and do not develop obesity, hepatic steatosis or insulin resistance when fed a high-fat diet (HFD). However, these phenomena are casually related and the physiological basis for this phenotype is unknown. We therefore undertook a series of acute HFD studies to more completely understand the physiology of Park2 KO during nutritional stress. We find that intestinal lipid absorption is impaired in Park2 KO mice as evidenced by increased fecal lipids and reduced plasma triglycerides after intragastric fat challenge. Park2 KO mice developed hepatic steatosis in response to intravenous lipid infusion as well as during incubation of primary hepatocytes with fatty acids, suggesting that hepatic protection from nutritional stress was secondary to changes in energy balance due to altered intestinal triglyceride absorption. Park2 KO mice showed reduced adiposity after 1-wk HFD, as well as improved hepatic and peripheral insulin sensitivity. These studies suggest that changes in intestinal lipid absorption may play a primary role in protection from nutritional stress in Park2 KO mice by preventing HFD-induced weight gain and highlight the need for tissue-specific models to address the role of PARK2 during metabolic stress.
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Affiliation(s)
- Diana K Costa
- Department of Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Brydie R Huckestein
- Department of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Lia R Edmunds
- Department of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Max C Petersen
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
| | - Ali Nasiri
- Department of Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Gina M Butrico
- Department of Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Abudukadier Abulizi
- Department of Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Daniel B Harmon
- Department of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Canying Lu
- Department of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Benjamin S Mantell
- Department of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Douglas J Hartman
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | | | - Robert M O'Doherty
- Department of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; Center for Metabolic and Mitochondrial Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Gary W Cline
- Department of Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Gerald I Shulman
- Department of Medicine, Yale University School of Medicine, New Haven, Connecticut; Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut; The Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut; and
| | - Michael J Jurczak
- Department of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; Center for Metabolic and Mitochondrial Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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