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Xiang X, Ji R, Han S, Xu X, Zhu S, Li Y, Du J, Mai K, Ai Q. Differences in diacylglycerol acyltransferases expression patterns and regulation cause distinct hepatic triglyceride deposition in fish. Commun Biol 2024; 7:480. [PMID: 38641731 PMCID: PMC11031565 DOI: 10.1038/s42003-024-06022-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 03/07/2024] [Indexed: 04/21/2024] Open
Abstract
Triglyceride (TAG) deposition in the liver is associated with metabolic disorders. In lower vertebrate, the propensity to accumulate hepatic TAG varies widely among fish species. Diacylglycerol acyltransferases (DGAT1 and DGAT2) are major enzymes for TAG synthesis. Here we show that large yellow croaker (Larimichthys crocea) has significantly higher hepatic TAG level than that in rainbow trout (Oncorhynchus mykiss) fed with same diet. Hepatic expression of DGATs genes in croaker is markedly higher compared with trout under physiological condition. Meanwhile, DGAT1 and DGAT2 in both croaker and trout are required for TAG synthesis and lipid droplet formation in vitro. Furthermore, oleic acid treatment increases DGAT1 expression in croaker hepatocytes rather than in trout and has no significant difference in DGAT2 expression in two fish species. Finally, effects of various transcription factors on croaker and trout DGAT1 promoter are studied. We find that DGAT1 is a target gene of the transcription factor CREBH in croaker rather than in trout. Overall, hepatic expression and transcriptional regulation of DGATs display significant species differences between croaker and trout with distinct hepatic triglyceride deposition, which bring new perspectives on the use of fish models for studying hepatic TAG deposition.
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Affiliation(s)
- Xiaojun Xiang
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) & Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, Qingdao, Shandong, 266003, P.R. China
| | - Renlei Ji
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) & Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, Qingdao, Shandong, 266003, P.R. China
| | - Shangzhe Han
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) & Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, Qingdao, Shandong, 266003, P.R. China
| | - Xiang Xu
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) & Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, Qingdao, Shandong, 266003, P.R. China
| | - Si Zhu
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) & Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, Qingdao, Shandong, 266003, P.R. China
| | - Yongnan Li
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) & Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, Qingdao, Shandong, 266003, P.R. China
| | - Jianlong Du
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) & Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, Qingdao, Shandong, 266003, P.R. China
| | - Kangsen Mai
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) & Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, Qingdao, Shandong, 266003, P.R. China
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, 1 Wenhai Road, Qingdao, Shandong, 266237, People's Republic of China
| | - Qinghui Ai
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) & Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, Qingdao, Shandong, 266003, P.R. China.
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, 1 Wenhai Road, Qingdao, Shandong, 266237, People's Republic of China.
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2
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Castillo HB, Shuster SO, Tarekegn LH, Davis CM. Oleic acid differentially affects lipid droplet storage of de novo synthesized lipids in hepatocytes and adipocytes. Chem Commun (Camb) 2024; 60:3138-3141. [PMID: 38329230 PMCID: PMC10939124 DOI: 10.1039/d3cc04829b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 01/29/2024] [Indexed: 02/09/2024]
Abstract
Lipogenesis is a vital but often dysregulated metabolic pathway. Here we use optical photothermal infrared imaging to quantify lipogenesis rates of isotopically labelled oleic acid and glucose concomitantly in live cells. In hepatocytes, but not adipocytes, we find that oleic acid feeding at 60 μM increases the number and size of lipid droplets (LDs) while simultaneously inhibiting storage of de novo synthesized lipids in LDs. Our results demonstrate alternate regulation of lipogenesis between cell types.
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Affiliation(s)
- Hannah B Castillo
- Department of Chemistry, Yale University, New Haven, Connecticut, 06511, USA.
| | - Sydney O Shuster
- Department of Chemistry, Yale University, New Haven, Connecticut, 06511, USA.
| | - Lydia H Tarekegn
- Department of Chemistry, Yale University, New Haven, Connecticut, 06511, USA.
| | - Caitlin M Davis
- Department of Chemistry, Yale University, New Haven, Connecticut, 06511, USA.
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3
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Soto A, Spongberg C, Martinino A, Giovinazzo F. Exploring the Multifaceted Landscape of MASLD: A Comprehensive Synthesis of Recent Studies, from Pathophysiology to Organoids and Beyond. Biomedicines 2024; 12:397. [PMID: 38397999 PMCID: PMC10886580 DOI: 10.3390/biomedicines12020397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 02/04/2024] [Accepted: 02/05/2024] [Indexed: 02/25/2024] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is a widespread contributor to chronic liver disease globally. A recent consensus on renaming liver disease was established, and metabolic dysfunction-associated steatotic liver disease, MASLD, was chosen as the replacement for NAFLD. The disease's range extends from the less severe MASLD, previously known as non-alcoholic fatty liver (NAFL), to the more intense metabolic dysfunction-associated steatohepatitis (MASH), previously known as non-alcoholic steatohepatitis (NASH), characterized by inflammation and apoptosis. This research project endeavors to comprehensively synthesize the most recent studies on MASLD, encompassing a wide spectrum of topics such as pathophysiology, risk factors, dietary influences, lifestyle management, genetics, epigenetics, therapeutic approaches, and the prospective trajectory of MASLD, particularly exploring its connection with organoids.
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Affiliation(s)
- Allison Soto
- Department of Surgery, University of Illinois College of Medicine, Chicago, IL 60607, USA;
| | - Colby Spongberg
- Touro College of Osteopathic Medicine, Great Falls, MT 59405, USA
| | | | - Francesco Giovinazzo
- General Surgery and Liver Transplant Unit, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, 00168 Rome, Italy
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4
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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: 0] [Impact Index Per Article: 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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5
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Li H, Seessle J, Staffer S, Tuma-Kellner S, Poschet G, Herrmann T, Chamulitrat W. FATP4 deletion in liver cells induces elevation of extracellular lipids via metabolic channeling towards triglycerides and lipolysis. Biochem Biophys Res Commun 2023; 687:149161. [PMID: 37931418 DOI: 10.1016/j.bbrc.2023.149161] [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: 08/14/2023] [Revised: 10/13/2023] [Accepted: 10/26/2023] [Indexed: 11/08/2023]
Abstract
Evidence from mice with global deletion of fatty-acid transport protein4 (FATP4) indicates its role on β-oxidation and triglycerides (TG) metabolism. We reported that plasma glycerol and free fatty acids (FA) were increased in liver-specific Fatp4 deficient (L-FATP4-/-) mice under dietary stress. We hypothesized that FATP4 may mediate hepatocellular TG lipolysis. Here, we demonstrated that L-FATP4-/- mice showed an increase in these blood lipids, liver TG, and subcutaneous fat weights. We therefore studied TG metabolism in response to oleate treatment in two experimental models using FATP4-knockout HepG2 (HepKO) cells and L-FATP4-/- hepatocytes. Both FATP4-deificient liver cells showed a significant decrease in β-oxidation products by ∼30-35% concomitant with marked upregulation of CD36, FATP2, and FATP5 as well as lipoprotein microsomal-triglyceride-transfer protein genes. By using 13C3D5-glycerol, HepKO cells displayed an increase in metabolically labelled TG species which were further increased with oleate treatment. This increase was concomitant with a step-wise elevation of TG in cells and supernatants as well as the secretion of cholesterol very low-density and high-density lipoproteins. Upon analyzing TG lipolytic enzymes, both mutant liver cells showed marked upregulated expression of hepatic lipase, while that of hormone-sensitive lipase and adipose-triglyceride lipase was downregulated. Lipolysis measured by extracellular glycerol and free FA was indeed increased in mutant cells, and this event was exacerbated by oleate treatment. Taken together, FATP4 deficiency in liver cells led to a metabolic shift from β-oxidation towards lipolysis-directed TG and lipoprotein secretion, which is in line with an association of FATP4 polymorphisms with blood lipids.
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Affiliation(s)
- Huili Li
- Department of Internal Medicine IV, University Hospital Heidelberg, 69120, Heidelberg, Germany; Department of Gastrointestinal Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 430022, Wuhan, Hubei, China
| | - Jessica Seessle
- Department of Internal Medicine IV, University Hospital Heidelberg, 69120, Heidelberg, Germany
| | - Simone Staffer
- Department of Internal Medicine IV, University Hospital Heidelberg, 69120, Heidelberg, Germany
| | - Sabine Tuma-Kellner
- Department of Internal Medicine IV, University Hospital Heidelberg, 69120, Heidelberg, Germany
| | - Gernot Poschet
- Metabolomics Core Technology Platform, Centre for Organismal Studies, University of Heidelberg, 69120, Heidelberg, Germany
| | - Thomas Herrmann
- Westkuesten Hospital, Esmarchstraße 50, 25746, Heide, Germany
| | - Walee Chamulitrat
- Department of Internal Medicine IV, University Hospital Heidelberg, 69120, Heidelberg, Germany.
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6
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Hendriks D, Brouwers JF, Hamer K, Geurts MH, Luciana L, Massalini S, López-Iglesias C, Peters PJ, Rodríguez-Colman MJ, Chuva de Sousa Lopes S, Artegiani B, Clevers H. Engineered human hepatocyte organoids enable CRISPR-based target discovery and drug screening for steatosis. Nat Biotechnol 2023; 41:1567-1581. [PMID: 36823355 PMCID: PMC10635827 DOI: 10.1038/s41587-023-01680-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 01/19/2023] [Indexed: 02/25/2023]
Abstract
The lack of registered drugs for nonalcoholic fatty liver disease (NAFLD) is partly due to the paucity of human-relevant models for target discovery and compound screening. Here we use human fetal hepatocyte organoids to model the first stage of NAFLD, steatosis, representing three different triggers: free fatty acid loading, interindividual genetic variability (PNPLA3 I148M) and monogenic lipid disorders (APOB and MTTP mutations). Screening of drug candidates revealed compounds effective at resolving steatosis. Mechanistic evaluation of effective drugs uncovered repression of de novo lipogenesis as the convergent molecular pathway. We present FatTracer, a CRISPR screening platform to identify steatosis modulators and putative targets using APOB-/- and MTTP-/- organoids. From a screen targeting 35 genes implicated in lipid metabolism and/or NAFLD risk, FADS2 (fatty acid desaturase 2) emerged as an important determinant of hepatic steatosis. Enhancement of FADS2 expression increases polyunsaturated fatty acid abundancy which, in turn, reduces de novo lipogenesis. These organoid models facilitate study of steatosis etiology and drug targets.
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Affiliation(s)
- Delilah Hendriks
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences, Utrecht, The Netherlands.
- Oncode Institute, Utrecht, The Netherlands.
| | - Jos F Brouwers
- Research Group Analysis Techniques in the Life Sciences, School of Life Sciences and Technology, Avans University of Applied Sciences, Breda, The Netherlands
- Molecular Cancer Research, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Karien Hamer
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences, Utrecht, The Netherlands
- Oncode Institute, Utrecht, The Netherlands
| | - Maarten H Geurts
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences, Utrecht, The Netherlands
- Oncode Institute, Utrecht, The Netherlands
| | - Léa Luciana
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences, Utrecht, The Netherlands
- Oncode Institute, Utrecht, The Netherlands
| | - Simone Massalini
- The Princess Maxima Center for Pediatric Oncology, Utrecht, The Netherlands
| | - Carmen López-Iglesias
- The Maastricht Multimodal Molecular Imaging Institute, Maastricht University, Maastricht, The Netherlands
| | - Peter J Peters
- The Maastricht Multimodal Molecular Imaging Institute, Maastricht University, Maastricht, The Netherlands
| | - Maria J Rodríguez-Colman
- Molecular Cancer Research, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | - Benedetta Artegiani
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences, Utrecht, The Netherlands.
- The Princess Maxima Center for Pediatric Oncology, Utrecht, The Netherlands.
| | - Hans Clevers
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences, Utrecht, The Netherlands.
- Oncode Institute, Utrecht, The Netherlands.
- The Princess Maxima Center for Pediatric Oncology, Utrecht, The Netherlands.
- University Medical Center Utrecht, Utrecht, The Netherlands.
- Pharma, Research and Early Development of F. Hoffmann-La Roche Ltd, Basel, Switzerland.
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7
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Farhan F, Trivedi M, Di Wu P, Cui W. Extracellular matrix modulates the spatial hepatic features in hepatocyte-like cells derived from human embryonic stem cells. Stem Cell Res Ther 2023; 14:314. [PMID: 37907977 PMCID: PMC10619266 DOI: 10.1186/s13287-023-03542-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 10/20/2023] [Indexed: 11/02/2023] Open
Abstract
BACKGROUND Human pluripotent stem cell (hPSC)-derived hepatocyte-like cells (HLCs) can provide a valuable in vitro model for disease modelling and drug development. However, generating HLCs with characteristics comparable to hepatocytes in vivo is challenging. Extracellular matrix (ECM) plays an important role in supporting liver development and hepatocyte functions, but their impact on hepatocyte differentiation and maturation during hPSC differentiation remains unclear. Here, we investigate the effects of two ECM components-Matrigel and type I collagen on hepatic differentiation of human embryonic stem cells (hESCs). METHODS hESC-derived HLCs were generated through multistage differentiation in two-dimensional (2D) and three-dimensional (3D) cultures, incorporating either type I collagen or Matrigel during hepatic specification and maturation. The resulting HLCs was characterized for their gene expression and functionality using various molecular and cellular techniques. RESULTS Our results showed that HLCs cultured with collagen exhibited a significant increase in albumin and alpha-1 anti-trypsin expression with reduced AFP compared to HLCs cultured with Matrigel. They also secreted more urea than Matrigel cultures. However, these HLCs exhibited lower CYP3A4 activity and glycogen storage than those cultured with Matrigel. These functional differences in HLCs between collagen and Matrigel cultures closely resembled the hepatocytes of periportal and pericentral zones, respectively. CONCLUSION Our study demonstrates that Matrigel and collagen have differential effects on the differentiation and functionality of HLCs, which resemble, to an extent, hepatic zonation in the liver lobules. Our finding has an important impact on the generation of hPSC-HLCs for biomedical and medical applications.
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Affiliation(s)
- Faiza Farhan
- Institute of Reproductive and Developmental Biology, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
| | - Manjari Trivedi
- Institute of Reproductive and Developmental Biology, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
| | - Priscilla Di Wu
- Institute of Reproductive and Developmental Biology, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
| | - Wei Cui
- Institute of Reproductive and Developmental Biology, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK.
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8
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Castillo HB, Shuster SO, Tarekegn LH, Davis CM. Oleic acid differentially affects de novo lipogenesis in adipocytes and hepatocytes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.04.560581. [PMID: 37873279 PMCID: PMC10592964 DOI: 10.1101/2023.10.04.560581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Lipogenesis is a vital but often dysregulated metabolic pathway. We report super-resolution multiplexed vibrational imaging of lipogenesis rates and pathways using isotopically labelled oleic acid and glucose as probes in live adipocytes and hepatocytes. These findings suggest oleic acid inhibits de novo lipogenesis (DNL), but not total lipogenesis, in hepatocytes. No significant effect is seen in adipocytes. These differential effects may be due to alternate regulation of DNL between cell types and could help explain the complicated role oleic acid plays in metabolism.
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Affiliation(s)
- Hannah B. Castillo
- Department of Chemistry, Yale University, New Haven, Connecticut, 06511, United States
| | - Sydney O. Shuster
- Department of Chemistry, Yale University, New Haven, Connecticut, 06511, United States
| | - Lydia H. Tarekegn
- Department of Chemistry, Yale University, New Haven, Connecticut, 06511, United States
| | - Caitlin M. Davis
- Department of Chemistry, Yale University, New Haven, Connecticut, 06511, United States
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9
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Dai G, Huang S, Li Y, Tu X, Xia J, Zhou Z, Chen W, Zhang A, Lin J, Li Y, He D, Lin T, Cong J, Lei Y, Han L, Yao Z, Liu W, Zhou Y, Li Q, Li J, Zhang Y, Wu A, Xiao D, Wang W, Zhao W, Jia J, Lin X. Mettl3-mediated m 6A modification plays a role in lipid metabolism disorders and progressive liver damage in mice by regulating lipid metabolism-related gene expression. Aging (Albany NY) 2023; 15:5550-5568. [PMID: 37335109 PMCID: PMC10333091 DOI: 10.18632/aging.204810] [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: 02/23/2023] [Accepted: 05/23/2023] [Indexed: 06/21/2023]
Abstract
AIMS N6-methyladenosine (m6A), the most abundant and conserved epigenetic modification of mRNA, participates in various physiological and pathological processes. However, the roles of m6A modification in liver lipid metabolism have yet to be understood entirely. We aimed to investigate the roles of the m6A "writer" protein methyltransferase-like 3 (Mettl3) in liver lipid metabolism and the underlying mechanisms. MAIN METHODS We assessed the expression of Mettl3 in liver tissues of diabetes (db/db) mice, obese (ob/ob) mice, high saturated fat-, cholesterol-, and fructose-induced non-alcoholic fatty liver disease (NAFLD) mice, and alcohol abuse and alcoholism (NIAAA) mice by quantitative reverse-transcriptase PCR (qRT-PCR). Hepatocyte-specific Mettl3 knockout mice were used to evaluate the effects of Mettl3 deficiency in mouse liver. The molecular mechanisms underlying the roles of Mettl3 deletion in liver lipid metabolism were explored by multi-omics joint analysis of public data from the Gene Expression Omnibus database and further validated by qRT-PCR and Western blot. KEY FINDINGS Significantly decreased Mettl3 expression was associated with NAFLD progression. Hepatocyte-specific knockout of Mettl3 resulted in significant lipid accumulation in the liver, increased serum total cholesterol levels, and progressive liver damage in mice. Mechanistically, loss of Mettl3 significantly downregulated the expression levels of multiple m6A-modified mRNAs related to lipid metabolism, including Adh7, Cpt1a, and Cyp7a1, further promoting lipid metabolism disorders and liver injury in mice. SIGNIFICANCE In summary, our findings demonstrate that the expression alteration of genes related to lipid metabolism by Mettl3-mediated m6A modification contributes to the development of NAFLD.
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Affiliation(s)
- Guanqi Dai
- Cancer Research Institute, Experimental Education/Administration Center, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
- Department of Radiation Oncology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Shihao Huang
- Cancer Research Institute, Experimental Education/Administration Center, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Yonglong Li
- Cancer Research Institute, Experimental Education/Administration Center, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
- Laboratory Animal Management Center, Southern Medical University, Guangzhou 510515, China
| | - Xueyi Tu
- Cancer Research Institute, Experimental Education/Administration Center, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Jiawei Xia
- The Third People’s Hospital of Kunming (The Sixth Affiliated Hospital of Dali University), Kunming 650041, China
| | - Zhihao Zhou
- Cancer Research Institute, Experimental Education/Administration Center, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Wanyi Chen
- Cancer Research Institute, Experimental Education/Administration Center, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Ao Zhang
- Cancer Research Institute, Experimental Education/Administration Center, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Jintao Lin
- Cancer Research Institute, Experimental Education/Administration Center, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Yingchun Li
- Cancer Research Institute, Experimental Education/Administration Center, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Danhua He
- Cancer Research Institute, Experimental Education/Administration Center, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Taoyan Lin
- Department of Pharmacy, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Jinge Cong
- Cancer Research Institute, Experimental Education/Administration Center, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
- Laboratory Animal Management Center, Southern Medical University, Guangzhou 510515, China
| | - Ye Lei
- Cancer Research Institute, Experimental Education/Administration Center, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
- Laboratory Animal Management Center, Southern Medical University, Guangzhou 510515, China
| | - Liuxin Han
- The Third People’s Hospital of Kunming (The Sixth Affiliated Hospital of Dali University), Kunming 650041, China
| | - Zhenxia Yao
- Cancer Research Institute, Experimental Education/Administration Center, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Weiwei Liu
- Cancer Research Institute, Experimental Education/Administration Center, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Ying Zhou
- Cancer Research Institute, Experimental Education/Administration Center, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Qiwen Li
- Cancer Research Institute, Experimental Education/Administration Center, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Jing Li
- Radiotherapy Center, The First People's Hospital of Chenzhou, Xiangnan University, Chenzhou 423000, China
| | - Yuqin Zhang
- Department of Radiation Oncology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Aibing Wu
- Department of Oncology, The Central People's Hospital of Zhanjiang, Zhanjiang 524000, China
| | - Dong Xiao
- Cancer Research Institute, Experimental Education/Administration Center, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
- Laboratory Animal Management Center, Southern Medical University, Guangzhou 510515, China
| | - Wanshan Wang
- Laboratory Animal Management Center, Southern Medical University, Guangzhou 510515, China
| | - Wentao Zhao
- Cancer Research Institute, Experimental Education/Administration Center, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
- Department of Gastrointestinal Oncology, The Third Affiliated Hospital of Kunming Medical University (Yunnan Cancer Hospital, Yunnan Cancer Center), Kunming 650118, China
| | - Junshuang Jia
- Cancer Research Institute, Experimental Education/Administration Center, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Xiaolin Lin
- Cancer Center, Integrated Hospital of Traditional Chinese Medicine, Southern Medical University, Guangzhou 510315, China
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10
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Yu D, Zhou L, Liu X, Xu G. Stable isotope-resolved metabolomics based on mass spectrometry: Methods and their applications. Trends Analyt Chem 2023. [DOI: 10.1016/j.trac.2023.116985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
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11
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Amin NB, Saxena AR, Somayaji V, Dullea R. Inhibition of Diacylglycerol Acyltransferase 2 Versus Diacylglycerol Acyltransferase 1: Potential Therapeutic Implications of Pharmacology. Clin Ther 2023; 45:55-70. [PMID: 36690550 DOI: 10.1016/j.clinthera.2022.12.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 12/01/2022] [Accepted: 12/15/2022] [Indexed: 01/22/2023]
Abstract
PURPOSE Hepatic steatosis due to altered lipid metabolism and accumulation of hepatic triglycerides is a hallmark of nonalcoholic fatty liver disease (NAFLD). Diacylglycerol acyltransferase (DGAT) enzymes, DGAT1 and DGAT2, catalyze the terminal reaction in triglyceride synthesis, making them attractive targets for pharmacologic intervention. There is a common misconception that these enzymes are related; however, despite their similar names, DGAT1 and DGAT2 differ significantly on multiple levels. As we look ahead to future clinical studies of DGAT2 inhibitors in patients with NAFLD and nonalcoholic steatohepatitis (NASH), we review key differences and include evidence to highlight and support DGAT2 inhibitor (DGAT2i) pharmacology. METHODS Three Phase I, randomized, double-blind, placebo-controlled trials assessed the safety, tolerability, and pharmacokinetic properties of the DGAT2i ervogastat (PF-06865571) in healthy adult participants (Single Dose Study to Assess the Safety, Tolerability and Pharmacokinetics of PF-06865571 [study C2541001] and Study to Assess the Safety, Tolerability, and Pharmacokinetics of Multiple Doses of PF-06865571 in Healthy, Including Overweight and Obese, Adult Subjects [study C2541002]) or participants with NAFLD (2-Week Study in People With Nonalcoholic Fatty Liver Disease [study C2541005]). Data from 2 Phase I, randomized, double-blind, placebo-controlled trials of the DGAT1i PF-04620110 in healthy participants (A Single Dose Study of PF-04620110 in Overweight and Obese, Otherwise Healthy Volunteers [study B0961001] and A Multiple Dose Study of PF-04620110 in Overweight and Obese, Otherwise Healthy Volunteers [study B0961002]) were included for comparison. Safety outcomes were the primary end point in all studies, except in study C2541005, in which safety was the secondary end point, with relative change from baseline in whole liver fat at day 15 assessed as the primary end point. Safety data were analyzed across studies by total daily dose of ervogastat (5, 15, 50, 100, 150, 500, 600, 1000, and 1500 mg) or PF-04620110 (0.3, 1, 3, 5, 7, 10, 14, and 21 mg), with placebo data pooled separately across ervogastat and PF-04620110 studies. FINDINGS Published data indicate that DGAT1 and DGAT2 differ in multiple dimensions, including gene family, subcellular localization, substrate preference, and specificity, with unrelated pharmacologic inhibition properties and differing safety profiles. Although initial nonclinical studies suggested a potentially attractive therapeutic profile with DGAT1 inhibition, genetic and pharmacologic data suggest otherwise, with common gastrointestinal adverse events, including nausea, vomiting, and diarrhea, limiting further clinical development. Conversely, DGAT2 inhibition, although initially not pursued as aggressively as a potential target for pharmacologic intervention, has consistent efficacy in nonclinical studies, with reduced triglyceride synthesis accompanied by reduced expression of genes essential for de novo lipogenesis. In addition, early clinical data indicate antisteatotic effects with DGAT2i ervogastat, in participants with NAFLD, accompanied by a well-tolerated safety profile. IMPLICATIONS Although pharmacologic DGAT1is are limited by an adverse safety profile, data support use of DGAT2i as an effective and well-tolerated therapeutic strategy for patients with NAFLD, NASH, and NASH with liver fibrosis. CLINICALTRIALS gov identifiers: NCT03092232, NCT03230383, NCT03513588, NCT00799006, and NCT00959426.
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Affiliation(s)
- Neeta B Amin
- Internal Medicine Research Unit, Pfizer Inc, Cambridge, Massachusetts
| | - Aditi R Saxena
- Internal Medicine Research Unit, Pfizer Inc, Cambridge, Massachusetts
| | - Veena Somayaji
- Early Clinical Development, Pfizer Inc, Cambridge, Massachusetts
| | - Robert Dullea
- Internal Medicine Research Unit, Pfizer Inc, Cambridge, Massachusetts.
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12
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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: 10] [Impact Index Per Article: 5.0] [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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13
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Winichayakul S, Curran A, Moraga R, Cookson R, Xue H, Crowther T, Roldan M, Bryan G, Roberts N. An alternative angiosperm DGAT1 topology and potential motifs in the N-terminus. FRONTIERS IN PLANT SCIENCE 2022; 13:951389. [PMID: 36186081 PMCID: PMC9523541 DOI: 10.3389/fpls.2022.951389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 08/05/2022] [Indexed: 06/16/2023]
Abstract
The highly variable cytoplasmic N-terminus of the plant diacylglycerol acyltransferase 1 (DGAT1) has been shown to have roles in oligomerization as well as allostery; however, the biological significance of the variation within this region is not understood. Comparing the coding sequences over the variable N-termini revealed the Poaceae DGAT1s contain relatively high GC compositional gradients as well as numerous direct and inverted repeats in this region. Using a variety of reciprocal chimeric DGAT1s from angiosperms we show that related N-termini had similar effects (positive or negative) on the accumulation of the recombinant protein in Saccharomyces cerevisiae. When expressed in Camelina sativa seeds the recombinant proteins of specific chimeras elevated total lipid content of the seeds as well as increased seed size. In addition, we combine N- and C-terminal as well as internal tags with high pH membrane reformation, protease protection and differential permeabilization. This led us to conclude the C-terminus is in the ER lumen; this contradicts earlier reports of the cytoplasmic location of plant DGAT1 C-termini.
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Affiliation(s)
- Somrutai Winichayakul
- Resilient Agriculture Innovation Centre of Excellence, AgResearch Ltd., Palmerston North, New Zealand
| | - Amy Curran
- ZeaKal Inc., San Diego, CA, United States
| | - Roger Moraga
- Bioinformatics and Statistics, AgResearch Ltd., Palmerston North, New Zealand
| | - Ruth Cookson
- Resilient Agriculture Innovation Centre of Excellence, AgResearch Ltd., Palmerston North, New Zealand
| | - Hong Xue
- Resilient Agriculture Innovation Centre of Excellence, AgResearch Ltd., Palmerston North, New Zealand
| | - Tracey Crowther
- Resilient Agriculture Innovation Centre of Excellence, AgResearch Ltd., Palmerston North, New Zealand
| | - Marissa Roldan
- Resilient Agriculture Innovation Centre of Excellence, AgResearch Ltd., Palmerston North, New Zealand
| | - Greg Bryan
- Resilient Agriculture Innovation Centre of Excellence, AgResearch Ltd., Palmerston North, New Zealand
- ZeaKal Inc., San Diego, CA, United States
| | - Nick Roberts
- Resilient Agriculture Innovation Centre of Excellence, AgResearch Ltd., Palmerston North, New Zealand
- ZeaKal Inc., San Diego, CA, United States
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Kou Y, Geng F, Guo D. Lipid Metabolism in Glioblastoma: From De Novo Synthesis to Storage. Biomedicines 2022; 10:1943. [PMID: 36009491 PMCID: PMC9405736 DOI: 10.3390/biomedicines10081943] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/01/2022] [Accepted: 08/06/2022] [Indexed: 12/12/2022] Open
Abstract
Glioblastoma (GBM) is the most lethal primary brain tumor. With limited therapeutic options, novel therapies are desperately needed. Recent studies have shown that GBM acquires large amounts of lipids for rapid growth through activation of sterol regulatory element-binding protein 1 (SREBP-1), a master transcription factor that regulates fatty acid and cholesterol synthesis, and cholesterol uptake. Interestingly, GBM cells divert substantial quantities of lipids into lipid droplets (LDs), a specific storage organelle for neutral lipids, to prevent lipotoxicity by increasing the expression of diacylglycerol acyltransferase 1 (DGAT1) and sterol-O-acyltransferase 1 (SOAT1), which convert excess fatty acids and cholesterol to triacylglycerol and cholesteryl esters, respectively. In this review, we will summarize recent progress on our understanding of lipid metabolism regulation in GBM to promote tumor growth and discuss novel strategies to specifically induce lipotoxicity to tumor cells through disrupting lipid storage, a promising new avenue for treating GBM.
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Affiliation(s)
- Yongjun Kou
- Department of Radiation Oncology, Ohio State Comprehensive Cancer Center, Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, College of Medicine at The Ohio State University, Columbus, OH 43012, USA
| | - Feng Geng
- Department of Radiation Oncology, Ohio State Comprehensive Cancer Center, Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, College of Medicine at The Ohio State University, Columbus, OH 43012, USA
| | - Deliang Guo
- Department of Radiation Oncology, Ohio State Comprehensive Cancer Center, Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, College of Medicine at The Ohio State University, Columbus, OH 43012, USA
- Center for Cancer Metabolism, James Comprehensive Cancer Center at The Ohio State University, Columbus, OH 43210, 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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Kuerschner L, Thiele C. Tracing Lipid Metabolism by Alkyne Lipids and Mass Spectrometry: The State of the Art. Front Mol Biosci 2022; 9:880559. [PMID: 35669564 PMCID: PMC9163959 DOI: 10.3389/fmolb.2022.880559] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 04/19/2022] [Indexed: 01/22/2023] Open
Abstract
Lipid tracing studies are a key method to gain a better understanding of the complex metabolic network lipids are involved in. In recent years, alkyne lipid tracers and mass spectrometry have been developed as powerful tools for such studies. This study aims to review the present standing of the underlying technique, highlight major findings the strategy allowed for, summarize its advantages, and discuss some limitations. In addition, an outlook on future developments is given.
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17
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Yang W, Wang S, Loor JJ, Lopes MG, Zhao Y, Ma X, Li M, Zhang B, Xu C. Role of diacylglycerol O-acyltransferase (DGAT) isoforms in bovine hepatic fatty acid metabolism. J Dairy Sci 2022; 105:3588-3600. [PMID: 35181144 DOI: 10.3168/jds.2021-21140] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 12/23/2021] [Indexed: 12/17/2022]
Abstract
Fatty acid accumulation in hepatocytes induced by high concentrations of fatty acids due to lipolysis and the associated oxidative damage they cause occur most frequently after calving. Because of their role in esterification of fatty acids, diacylglycerol acyltransferase isoforms (DGAT1 and DGAT2) could play a role in the susceptibility of dairy cows to develop fatty liver. To gain mechanistic insights, we performed in vivo and in vitro analyses using liver biopsies or isolated primary hepatocytes. The in vivo study (n = 5 cows/group) involved healthy cows [average liver triacylglycerol (TAG) = 0.78%; 0.58 to 0.93%, ratio of triglyceride weight to wet liver weight] or cows diagnosed with fatty liver (average TAG = 7.60%; 5.31 to 10.54%). In vitro, hepatocytes isolated from 3 healthy female calves (1 d old, 44 to 53 kg) were challenged with (fatty acids) or without (control) a 1.2 mM mixture of fatty acids in an attempt to induce metabolic stress. Furthermore, hepatocytes were treated with DGAT1 inhibitor or DGAT2 inhibitor for 2 h followed by a challenge with (DGAT1 inhibitor + fatty acids or DGAT2 inhibitor + fatty acids) or without (DGAT1 inhibitor or DGAT2 inhibitor) the 1.2 mM mixture of fatty acids for 12 h. Data analysis of liver biopsies was compared using a 2-tailed unpaired Student's t-test. Data from calf hepatocyte treatment comparisons were assessed by one-way ANOVA, and multiplicity for each experiment was adjusted by the Holm's procedure. Data indicated that both fatty liver and in vitro challenge with fatty acids were associated with greater mRNA and protein abundance of SREBF1, FASN, DGAT1, and DGAT2. In contrast, mRNA and protein abundance of CPT1A and very low-density lipoprotein synthesis-related proteins MTTP and APOB were markedly lower. However, compared with fatty acid challenge alone, DGAT1 inhibitor + fatty acids led to greater mRNA and protein abundance of CPT1A and APOB, and greater mRNA abundance of SREBF1 and MTTP. Furthermore, this treatment led to lower mRNA abundance of FASN and DGAT2 and TAG concentrations. Compared with fatty acid challenge alone, DGAT2 inhibitor + fatty acids led to greater mRNA and protein abundance of CPT1A, MTTP, and APOB, and lower mRNA and protein abundance of SREBF1 and FASN. In addition, compared with control and fatty acids, there was greater protein abundance of GRP78 and PERK in both DGAT1 and DGAT2 inhibitor with or without fatty acids. Furthermore, compared with control and fatty acids, reactive oxygen species concentrations in the DGAT1 inhibitor with or without fatty acid group was greater. Overall, data suggested that DGAT1 is particularly relevant in the context of hepatocyte TAG synthesis from exogenous fatty acids. Disruption of both DGAT1 and DGAT2 altered lipid homeostasis, channeling fatty acids toward oxidation and generation of reactive oxygen species. Both DGAT isoforms play a role in promoting fatty acid storage into TAG and lipid droplets to protect hepatocytes from oxidative damage.
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Affiliation(s)
- Wei Yang
- Heilongjiang Provincial Key Laboratory of Prevention and Control of Bovine Diseases, College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, Daqing 163319, China
| | - Shuang Wang
- Heilongjiang Provincial Key Laboratory of Prevention and Control of Bovine Diseases, College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, Daqing 163319, China
| | - Juan J Loor
- Mammalian NutriPhysioGenomics, Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana 61801
| | - Matheus G Lopes
- Mammalian NutriPhysioGenomics, Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana 61801
| | - Yingying Zhao
- Heilongjiang Provincial Key Laboratory of Prevention and Control of Bovine Diseases, College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, Daqing 163319, China
| | - Xinru Ma
- Heilongjiang Provincial Key Laboratory of Prevention and Control of Bovine Diseases, College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, Daqing 163319, China
| | - Ming Li
- Heilongjiang Provincial Key Laboratory of Prevention and Control of Bovine Diseases, College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, Daqing 163319, China
| | - Bingbing Zhang
- College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, China
| | - Chuang Xu
- Heilongjiang Provincial Key Laboratory of Prevention and Control of Bovine Diseases, College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, Daqing 163319, China.
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18
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Prikhodko VA, Bezborodkina NN, Okovityi SV. Pharmacotherapy for Non-Alcoholic Fatty Liver Disease: Emerging Targets and Drug Candidates. Biomedicines 2022; 10:274. [PMID: 35203484 PMCID: PMC8869100 DOI: 10.3390/biomedicines10020274] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/22/2022] [Accepted: 01/24/2022] [Indexed: 02/08/2023] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD), or metabolic (dysfunction)-associated fatty liver disease (MAFLD), is characterized by high global incidence and prevalence, a tight association with common metabolic comorbidities, and a substantial risk of progression and associated mortality. Despite the increasingly high medical and socioeconomic burden of NAFLD, the lack of approved pharmacotherapy regimens remains an unsolved issue. In this paper, we aimed to provide an update on the rapidly changing therapeutic landscape and highlight the major novel approaches to the treatment of this disease. In addition to describing the biomolecules and pathways identified as upcoming pharmacological targets for NAFLD, we reviewed the current status of drug discovery and development pipeline with a special focus on recent evidence from clinical trials.
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Affiliation(s)
- Veronika A. Prikhodko
- Department of Pharmacology and Clinical Pharmacology, Saint Petersburg State Chemical and Pharmaceutical University, 14A Prof. Popov Str., 197022 St. Petersburg, Russia;
| | - Natalia N. Bezborodkina
- Zoological Institute, Russian Academy of Sciences, 1 Universitetskaya emb., 199034 St. Petersburg, Russia;
| | - Sergey V. Okovityi
- Department of Pharmacology and Clinical Pharmacology, Saint Petersburg State Chemical and Pharmaceutical University, 14A Prof. Popov Str., 197022 St. Petersburg, Russia;
- Scientific, Clinical and Educational Center of Gastroenterology and Hepatology, Saint Petersburg State University, 7/9 Universitetskaya emb., 199034 St. Petersburg, Russia
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Satapati S, Downes DP, Metzger D, Shankaran H, Talukdar S, Zhou Y, Ren Z, Chen M, Lim YH, Hatcher NG, Wen X, Sheth PR, McLaren DG, Previs SF. Using measures of metabolic flux to align screening and clinical development: Avoiding pitfalls to enable translational studies. SLAS DISCOVERY : ADVANCING LIFE SCIENCES R & D 2022; 27:20-28. [PMID: 35058172 DOI: 10.1016/j.slasd.2021.10.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Screening campaigns, especially those aimed at modulating enzyme activity, often rely on measuring substrate→product conversions. Unfortunately, the presence of endogenous substrates and/or products can limit one's ability to measure conversions. As well, coupled detection systems, often used to facilitate optical readouts, are subject to interference. Stable isotope labeled substrates can overcome background contamination and yield a direct readout of enzyme activity. Not only can isotope kinetic assays enable early screening, but they can also be used to follow hit progression in translational (pre)clinical studies. Herein, we consider a case study surrounding lipid biology to exemplify how metabolic flux analyses can connect stages of drug development, caveats are highlighted to ensure reliable data interpretations. For example, when measuring enzyme activity in early biochemical screening it may be enough to quantify the formation of a labeled product. In contrast, cell-based and in vivo studies must account for variable exposure to a labeled substrate (or precursor) which occurs via tracer dilution and/or isotopic exchange. Strategies are discussed to correct for these complications. We believe that measures of metabolic flux can help connect structure-activity relationships with pharmacodynamic mechanisms of action and determine whether mechanistically differentiated biophysical interactions lead to physiologically relevant outcomes. Adoption of this logic may allow research programs to (i) build a critical bridge between primary screening and (pre)clinical development, (ii) elucidate biology in parallel with screening and (iii) suggest a strategy aimed at in vivo biomarker development.
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Affiliation(s)
- Santhosh Satapati
- Merck & Co., Inc, 213 E. Grand Ave, South San Francisco, CA, 94080, USA
| | - Daniel P Downes
- Merck & Co., Inc, 2000 Galloping Hill Rd, Kenilworth, NJ, 07033, USA
| | - Daniel Metzger
- Merck & Co., Inc, 213 E. Grand Ave, South San Francisco, CA, 94080, USA
| | - Harish Shankaran
- Merck & Co., Inc, 213 E. Grand Ave, South San Francisco, CA, 94080, USA
| | - Saswata Talukdar
- Merck & Co., Inc, 213 E. Grand Ave, South San Francisco, CA, 94080, USA
| | - Yingjiang Zhou
- Merck & Co., Inc, 213 E. Grand Ave, South San Francisco, CA, 94080, USA
| | - Zhao Ren
- Merck & Co., Inc, 213 E. Grand Ave, South San Francisco, CA, 94080, USA
| | - Michelle Chen
- Merck & Co., Inc, 213 E. Grand Ave, South San Francisco, CA, 94080, USA
| | - Yeon-Hee Lim
- Merck & Co., Inc, 213 E. Grand Ave, South San Francisco, CA, 94080, USA
| | - Nathan G Hatcher
- Merck & Co., Inc, 770 Sumneytown Pike, West Point, PA, 19486, USA
| | - Xiujuan Wen
- Merck & Co., Inc, 2000 Galloping Hill Rd, Kenilworth, NJ, 07033, USA
| | - Payal R Sheth
- Merck & Co., Inc, 2000 Galloping Hill Rd, Kenilworth, NJ, 07033, USA
| | - David G McLaren
- Merck & Co., Inc, 2000 Galloping Hill Rd, Kenilworth, NJ, 07033, USA
| | - Stephen F Previs
- Merck & Co., Inc, 2000 Galloping Hill Rd, Kenilworth, NJ, 07033, USA.
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20
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Heeren J, Scheja L. Metabolic-associated fatty liver disease and lipoprotein metabolism. Mol Metab 2021; 50:101238. [PMID: 33892169 PMCID: PMC8324684 DOI: 10.1016/j.molmet.2021.101238] [Citation(s) in RCA: 191] [Impact Index Per Article: 63.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/01/2021] [Accepted: 04/15/2021] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Non-alcoholic fatty liver disease, or as recently proposed 'metabolic-associated fatty liver disease' (MAFLD), is characterized by pathological accumulation of triglycerides and other lipids in hepatocytes. This common disease can progress from simple steatosis to steatohepatitis, and eventually end-stage liver diseases. MAFLD is closely related to disturbances in systemic energy metabolism, including insulin resistance and atherogenic dyslipidemia. SCOPE OF REVIEW The liver is the central organ in lipid metabolism by secreting very low density lipoproteins (VLDL) and, on the other hand, by internalizing fatty acids and lipoproteins. This review article discusses recent research addressing hepatic lipid synthesis, VLDL production, and lipoprotein internalization as well as the lipid exchange between adipose tissue and the liver in the context of MAFLD. MAJOR CONCLUSIONS Liver steatosis in MAFLD is triggered by excessive hepatic triglyceride synthesis utilizing fatty acids derived from white adipose tissue (WAT), de novo lipogenesis (DNL) and endocytosed remnants of triglyceride-rich lipoproteins. In consequence of high hepatic lipid content, VLDL secretion is enhanced, which is the primary cause of complex dyslipidemia typical for subjects with MAFLD. Interventions reducing VLDL secretory capacity attenuate dyslipidemia while they exacerbate MAFLD, indicating that the balance of lipid storage versus secretion in hepatocytes is a critical parameter determining disease outcome. Proof of concept studies have shown that promoting lipid storage and energy combustion in adipose tissues reduces hepatic lipid load and thus ameliorates MAFLD. Moreover, hepatocellular triglyceride synthesis from DNL and WAT-derived fatty acids can be targeted to treat MAFLD. However, more research is needed to understand how individual transporters, enzymes, and their isoforms affect steatosis and dyslipidemia in vivo, and whether these two aspects of MAFLD can be selectively treated. Processing of cholesterol-enriched lipoproteins appears less important for steatosis. It may, however, modulate inflammation and consequently MAFLD progression.
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Affiliation(s)
- Joerg Heeren
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
| | - Ludger Scheja
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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Abstract
PURPOSE OF REVIEW Nonalcoholic fatty liver disease (NAFLD) is defined as the abnormal accumulation of lipids in the liver, called hepatic steatosis, which occurs most often as a concomitant of the metabolic syndrome. Its incidence has surged significantly in recent decades concomitant with the obesity pandemic and increasing consumption of refined carbohydrates and saturated fats. This makes a review of the origins of NAFLD timely and relevant. RECENT FINDINGS This disorder, which shares histologic markers found in alcoholic fatty liver disease, was named NAFLD to distinguish it from the latter. Recently, however, the term metabolic-associated fatty liver disease (MAFLD) has been suggested as a refinement of NAFLD that should highlight the central, etiologic role of insulin resistance, obesity, and diabetes mellitus. The complexity of the pathways involved in the regulation of hepatic triglyceride synthesis and utilization have become obvious over the past 10 years, including the recent identification of monogenic causes of metabolic-associated fatty liver disease. These include PNPLA3, transmembrane 6 superfamily member 2, GCKR, membrane-bound O-acyltransferase 7 suggest targets for new therapies for hepatic steatosis. SUMMARY The current review can serve as a guide to the complex pathways involved in the maintenance of hepatic triglyceride levels as well as an introduction to the most recent discoveries, including those of key genes that have provided opportunities for new and novel therapeutics.
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Affiliation(s)
- Leinys S Santos-Baez
- Division of Preventive Medicine and Nutrition, Department of Medicine, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
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Broadfield LA, Pane AA, Talebi A, Swinnen JV, Fendt SM. Lipid metabolism in cancer: New perspectives and emerging mechanisms. Dev Cell 2021; 56:1363-1393. [PMID: 33945792 DOI: 10.1016/j.devcel.2021.04.013] [Citation(s) in RCA: 198] [Impact Index Per Article: 66.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 03/15/2021] [Accepted: 04/08/2021] [Indexed: 12/12/2022]
Abstract
Tumors undergo metabolic transformations to sustain uncontrolled proliferation, avoid cell death, and seed in secondary organs. An increased focus on cancer lipid metabolism has unveiled a number of mechanisms that promote tumor growth and survival, many of which are independent of classical cellular bioenergetics. These mechanisms include modulation of ferroptotic-mediated cell death, support during tumor metastasis, and interactions with the cells of the tumor microenvironment. As such, targeting lipid metabolism for anti-cancer therapies is attractive, with recent work on small-molecule inhibitors identifying compounds to target lipid metabolism. Here, we discuss these topics and identify open questions.
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Affiliation(s)
- Lindsay A Broadfield
- Laboratory of Cellular Metabolism and Metabolic Regulation, VIB-KU Leuven Center for Cancer Biology, VIB, Leuven, Belgium; Laboratory of Cellular Metabolism and Metabolic Regulation, Department of Oncology, KU Leuven and Leuven Cancer Institute (LKI), Leuven, Belgium
| | - Antonino Alejandro Pane
- Laboratory of Cellular Metabolism and Metabolic Regulation, VIB-KU Leuven Center for Cancer Biology, VIB, Leuven, Belgium; Laboratory of Cellular Metabolism and Metabolic Regulation, Department of Oncology, KU Leuven and Leuven Cancer Institute (LKI), Leuven, Belgium
| | - Ali Talebi
- Department of Oncology, Laboratory of Lipid Metabolism and Cancer, Leuven Cancer Institute (LKI), KU Leuven, University of Leuven, Leuven, Belgium
| | - Johannes V Swinnen
- Department of Oncology, Laboratory of Lipid Metabolism and Cancer, Leuven Cancer Institute (LKI), KU Leuven, University of Leuven, Leuven, Belgium
| | - Sarah-Maria Fendt
- Laboratory of Cellular Metabolism and Metabolic Regulation, VIB-KU Leuven Center for Cancer Biology, VIB, Leuven, Belgium; Laboratory of Cellular Metabolism and Metabolic Regulation, Department of Oncology, KU Leuven and Leuven Cancer Institute (LKI), Leuven, Belgium.
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23
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An SJ, Lee EJ, Jeong SH, Hong YP, Ahn S, Yang YJ. Perinatal exposure to di-(2-ethylhexyl) phthalate induces hepatic lipid accumulation mediated by diacylglycerol acyltransferase 1. Hum Exp Toxicol 2021; 40:1698-1709. [PMID: 33832334 DOI: 10.1177/09603271211003314] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
INTRODUCTION Di-(2-ethylhexyl) phthalate (DEHP) is a commonly used plasticizer in consumer products and medical devices. It is also suspected to exacerbate the development of fatty liver. However, the mechanisms underlying excessive lipid synthesis and its deposition in the liver are yet to be identified. This study was aimed to evaluate the molecular mechanisms of hepatic lipid accumulation in adult male offspring after perinatal exposure to DEHP. METHOD Corn oil and DEHP (0.75 mg/kg/day) were administered once per day to dam from gestation day 6 to postnatal day (PND) 21 by oral gavage. After the weaning period, DEHP treated male pups were categorized into early life stage- and lifelong period group. Male rats both control and early life stage group administered corn oil, and lifelong period group administered DEHP from PND 22 to 70. Histological examination and triglyceride (TG) levels in the liver were analyzed. Expressions of transcription factors associated with lipid accumulation in the liver were analyzed. RESULTS Both early life stage- and lifelong period group, hepatic TG levels, and mRNA and protein expression of diacylglycerol acyltransferase 1 (DGAT1) were significantly higher than control (TG: all p < 0.05, mRNA & protein: p < 0.05 and p < 0.001, respectively). The average body weight from PND 35 to 63, and mRNA and protein expression of sterol regulatory element binding protein 1c in lifelong period group were significantly lower than control (all p < 0.05); however, alanine transaminase were significantly higher than control (p < 0.01). CONCLUSION Perinatal exposure to DEHP may induce the hepatic lipid accumulation through up-regulation of DGAT1 expression.
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Affiliation(s)
- S J An
- Department of Neurology, Catholic Kwandong University International St Mary's Hospital, Incheon, Republic of Korea.,These authors are equally contributed to this work
| | - E J Lee
- Institute for Catholic Integrative Medicine, Incheon St Mary's Hospital, College of Medicine, The Catholic University of Korea, Incheon, Republic of Korea.,These authors are equally contributed to this work
| | - S-H Jeong
- Division of Gastroenterology, Department of Internal Medicine, Catholic Kwandong University International St Mary's Hospital, Incheon, Republic of Korea
| | - Y-P Hong
- Department of Preventive Medicine, College of Medicine, Chung-Ang University, Seoul, Republic of Korea
| | - S Ahn
- Department of Pathology, Catholic Kwandong University International St Mary's Hospital, Incheon, Republic of Korea
| | - Y-J Yang
- Institute of Biomedical Science, Catholic Kwandong University International St Mary's Hospital, Incheon, Republic of Korea
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de la Rosa Rodriguez MA, Deng L, Gemmink A, van Weeghel M, Aoun ML, Warnecke C, Singh R, Borst JW, Kersten S. Hypoxia-inducible lipid droplet-associated induces DGAT1 and promotes lipid storage in hepatocytes. Mol Metab 2021; 47:101168. [PMID: 33465519 PMCID: PMC7881268 DOI: 10.1016/j.molmet.2021.101168] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 01/08/2021] [Accepted: 01/12/2021] [Indexed: 12/26/2022] Open
Abstract
Objective Storage of triglycerides in lipid droplets is governed by a set of lipid droplet-associated proteins. One of these lipid droplet-associated proteins, hypoxia-inducible lipid droplet-associated (HILPDA), was found to impair lipid droplet breakdown in macrophages and cancer cells by inhibiting adipose triglyceride lipase. Here, we aimed to better characterize the role and mechanism of action of HILPDA in hepatocytes. Methods We performed studies in HILPDA-deficient and HILPDA-overexpressing liver cells, liver slices, and mice. The functional role and physical interactions of HILPDA were investigated using a variety of biochemical and microscopic techniques, including real-time fluorescence live-cell imaging and Förster resonance energy transfer-fluorescence lifetime imaging microscopy (FRET-FLIM). Results Levels of HILPDA were markedly induced by fatty acids in several hepatoma cell lines. Hepatocyte-specific deficiency of HILPDA in mice modestly but significantly reduced hepatic triglycerides in mice with non-alcoholic steatohepatitis. Similarly, deficiency of HILPDA in mouse liver slices and primary hepatocytes reduced lipid storage and accumulation of fluorescently-labeled fatty acids in lipid droplets, respectively, which was independent of adipose triglyceride lipase. Fluorescence microscopy showed that HILPDA partly colocalizes with lipid droplets and with the endoplasmic reticulum, is especially abundant in perinuclear areas, and mainly associates with newly added fatty acids. Real-time fluorescence live-cell imaging further revealed that HILPDA preferentially localizes to lipid droplets that are being remodeled. Overexpression of HILPDA in liver cells increased the activity of diacylglycerol acyltransferases (DGAT) and DGAT1 protein levels, concurrent with increased lipid storage. Confocal microscopy coupled to FRET-FLIM analysis demonstrated that HILPDA physically interacts with DGAT1 in living liver cells. The stimulatory effect of HILPDA on lipid storage via DGAT1 was corroborated in adipocytes. Conclusions Our data indicate that HILPDA physically interacts with DGAT1 and increases DGAT activity. Our findings suggest a novel regulatory mechanism by which fatty acids promote triglyceride synthesis and storage. HILPDA expression is induced by fatty acids in hepatoma cells. HILPDA deficiency modestly decreases liver triglyceride storage in mice with NASH. HILPDA preferentially associates with newly synthesized lipid droplets and active lipid droplets. HILPDA promotes lipid storage at least in part independently of ATGL. HILPDA physically interacts and induces DGAT1.
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Affiliation(s)
- Montserrat A de la Rosa Rodriguez
- Nutrition, Metabolism, and Genomics Group, Division of Human Nutrition and Health, Wageningen University, Stippeneng 4, Wageningen, 6708 WE, the Netherlands
| | - Lei Deng
- Nutrition, Metabolism, and Genomics Group, Division of Human Nutrition and Health, Wageningen University, Stippeneng 4, Wageningen, 6708 WE, the Netherlands
| | - Anne Gemmink
- Department of Nutrition and Movement Sciences, Maastricht University Medical Center+, Maastricht, 6200 MD, the Netherlands
| | - Michel van Weeghel
- Laboratory Genetic Metabolic Diseases, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, Amsterdam, 1105 AZ, the Netherlands
| | - Marie Louise Aoun
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Forchheimer 505D, Bronx, NY, 10461, USA
| | - Christina Warnecke
- Department of Nephrology and Hypertension, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Rajat Singh
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Forchheimer 505D, Bronx, NY, 10461, USA
| | - Jan Willem Borst
- Laboratory of Biochemistry, Microspectroscopy Research Facility, Wageningen University, Stippeneng 4, Wageningen, 6708 WE, the Netherlands
| | - Sander Kersten
- Nutrition, Metabolism, and Genomics Group, Division of Human Nutrition and Health, Wageningen University, Stippeneng 4, Wageningen, 6708 WE, the Netherlands.
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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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Kim IY, Park S, Kim Y, Chang Y, Choi CS, Suh SH, Wolfe RR. In Vivo and In Vitro Quantification of Glucose Kinetics: From Bedside to Bench. Endocrinol Metab (Seoul) 2020; 35:733-749. [PMID: 33397035 PMCID: PMC7803595 DOI: 10.3803/enm.2020.406] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 11/27/2020] [Indexed: 12/16/2022] Open
Abstract
Like other substrates, plasma glucose is in a dynamic state of constant turnover (i.e., rates of glucose appearance [Ra glucose] into and disappearance [Rd glucose] from the plasma) while staying within a narrow range of normal concentrations, a physiological priority. Persistent imbalance of glucose turnover leads to elevations (i.e., hyperglycemia, Ra>Rd) or falls (i.e., hypoglycemia, Ra<Rd) in the pool size, leading to clinical conditions such as diabetes. Endogenous Ra glucose is divided into hepatic glucose production via glycogenolysis and gluconeogenesis (GNG) and renal GNG. On the other hand, Rd glucose, the summed rate of glucose uptake by tissues/organs, involves various intracellular metabolic pathways including glycolysis, the tricarboxylic acid (TCA) cycle, and oxidation at varying rates depending on the metabolic status. Despite the dynamic nature of glucose metabolism, metabolic studies typically rely on measurements of static, snapshot information such as the abundance of mRNAs and proteins and (in)activation of implicated signaling networks without determining actual flux rates. In this review, we will discuss the importance of obtaining kinetic information, basic principles of stable isotope tracer methodology, calculations of in vivo glucose kinetics, and assessments of metabolic flux in experimental models in vivo and in vitro.
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Affiliation(s)
- Il-Young Kim
- Department of Molecular Medicine, College of Medicine, Gachon University, Incheon, Seoul,
Korea
- Korea Mouse Metabolic Phenotyping Center, Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, Seoul,
Korea
| | - Sanghee Park
- Department of Molecular Medicine, College of Medicine, Gachon University, Incheon, Seoul,
Korea
- Korea Mouse Metabolic Phenotyping Center, Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, Seoul,
Korea
| | - Yeongmin Kim
- Department of Health Sciences and Technology, Gachon Advanced Institute for Health Sciences & Technology (GAIHST), Gachon University, Incheon, Seoul,
Korea
| | - Yewon Chang
- Department of Health Sciences and Technology, Gachon Advanced Institute for Health Sciences & Technology (GAIHST), Gachon University, Incheon, Seoul,
Korea
| | - Cheol Soo Choi
- Department of Molecular Medicine, College of Medicine, Gachon University, Incheon, Seoul,
Korea
- Korea Mouse Metabolic Phenotyping Center, Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, Seoul,
Korea
| | - Sang-Hoon Suh
- Department of Physical Education, Yonsei University, Seoul,
Korea
| | - Robert R. Wolfe
- Department of Geriatrics, the Center for Translational Research in Aging & Longevity, Donald W. Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR,
USA
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Mashek DG. Hepatic lipid droplets: A balancing act between energy storage and metabolic dysfunction in NAFLD. Mol Metab 2020; 50:101115. [PMID: 33186758 PMCID: PMC8324678 DOI: 10.1016/j.molmet.2020.101115] [Citation(s) in RCA: 100] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 10/21/2020] [Accepted: 11/06/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Non-alcoholic fatty liver disease (NAFLD) is defined by the abundance of lipid droplets (LDs) in hepatocytes. While historically considered simply depots for energy storage, LDs are increasingly recognized to impact a wide range of biological processes that influence cellular metabolism, signaling, and function. While progress has been made toward understanding the factors leading to LD accumulation (i.e. steatosis) and its progression to advanced stages of NAFLD and/or systemic metabolic dysfunction, much remains to be resolved. SCOPE OF REVIEW This review covers many facets of LD biology. We provide a brief overview of the major pathways of lipid accretion and degradation that contribute to steatosis and how they are altered in NAFLD. The major focus is on the relationship between LDs and cell function and the detailed mechanisms that couple or uncouple steatosis from the severity and progression of NAFLD and systemic comorbidities. The importance of specific lipids and proteins within or on LDs as key components that determine whether LD accumulation is linked to cellular and metabolic dysfunction is presented. We discuss emerging areas of LD biology and future research directions that are needed to advance our understanding of the role of LDs in NAFLD etiology. MAJOR CONCLUSIONS Impairments in LD breakdown appear to contribute to disease progression, but inefficient incorporation of fatty acids (FAs) into LD-containing triacylglycerol (TAG) and the consequential changes in FA partitioning also affect NAFLD etiology. Increased LD abundance in hepatocytes does not necessarily equate to cellular dysfunction. While LD accumulation is the prerequisite step for most NAFLD cases, the protein and lipid composition of LDs are critical factors in determining the progression from simple steatosis. Further defining the detailed molecular mechanisms linking LDs to metabolic dysfunction is important for designing effective therapeutic approaches targeting NAFLD and its comorbidities.
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Affiliation(s)
- Douglas G Mashek
- Department of Biochemistry, Molecular Biology, and Biophysics, Department of Medicine, Division of Diabetes, Endocrinology, and Metabolism, University of Minnesota, Suite 6-155, 321 Church St. SE, Minneapolis, MN, 55455, USA.
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Playing Jekyll and Hyde-The Dual Role of Lipids in Fatty Liver Disease. Cells 2020; 9:cells9102244. [PMID: 33036257 PMCID: PMC7601321 DOI: 10.3390/cells9102244] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 09/27/2020] [Accepted: 10/01/2020] [Indexed: 12/12/2022] Open
Abstract
Lipids play Jekyll and Hyde in the liver. On the one hand, the lipid-laden status of hepatic stellate cells is a hallmark of healthy liver. On the other hand, the opposite is true for lipid-laden hepatocytes—they obstruct liver function. Neglected lipid accumulation in hepatocytes can progress into hepatic fibrosis, a condition induced by the activation of stellate cells. In their resting state, these cells store substantial quantities of fat-soluble vitamin A (retinyl esters) in large lipid droplets. During activation, these lipid organelles are gradually degraded. Hence, treatment of fatty liver disease is treading a tightrope—unsophisticated targeting of hepatic lipid accumulation might trigger problematic side effects on stellate cells. Therefore, it is of great importance to gain more insight into the highly dynamic lipid metabolism of hepatocytes and stellate cells in both quiescent and activated states. In this review, part of the special issue entitled “Cellular and Molecular Mechanisms underlying the Pathogenesis of Hepatic Fibrosis 2020”, we discuss current and highly versatile aspects of neutral lipid metabolism in the pathogenesis of non-alcoholic fatty liver disease (NAFLD).
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29
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Heikelä H, Ruohonen ST, Adam M, Viitanen R, Liljenbäck H, Eskola O, Gabriel M, Mairinoja L, Pessia A, Velagapudi V, Roivainen A, Zhang FP, Strauss L, Poutanen M. Hydroxysteroid (17β) dehydrogenase 12 is essential for metabolic homeostasis in adult mice. Am J Physiol Endocrinol Metab 2020; 319:E494-E508. [PMID: 32691632 DOI: 10.1152/ajpendo.00042.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hydroxysteroid 17β dehydrogenase 12 (HSD17B12) is suggested to be involved in the elongation of very long chain fatty acids. Previously, we have shown a pivotal role for the enzyme during mouse development. In the present study we generated a conditional Hsd17b12 knockout (HSD17B12cKO) mouse model by breeding mice homozygous for a floxed Hsd17b12 allele with mice expressing the tamoxifen-inducible Cre recombinase at the ROSA26 locus. Gene inactivation was induced by administering tamoxifen to adult mice. The gene inactivation led to a 20% loss of body weight within 6 days, associated with drastic reduction in both white (83% males, 75% females) and brown (65% males, 60% females) fat, likely due to markedly reduced food and water intake. Furthermore, the knockout mice showed sickness behavior and signs of liver toxicity, specifically microvesicular hepatic steatosis and increased serum alanine aminotransferase (4.6-fold in males, 7.7-fold in females). The hepatic changes were more pronounced in females than males. Proinflammatory cytokines, such as interleukin-6 (IL-6), IL-17, and granulocyte colony-stimulating factor, were increased in the HSD17B12cKO mice indicating an inflammatory response. Serum lipidomics study showed an increase in the amount of dihydroceramides, despite the dramatic overall loss of lipids. In line with the proposed role for HSD17B12 in fatty acid elongation, we observed accumulation of ceramides, dihydroceramides, hexosylceramides, and lactosylceramides with shorter than 18-carbon fatty acid side chains in the serum. The results indicate that HSD17B12 is essential for proper lipid homeostasis and HSD17B12 deficiency rapidly results in fatal systemic inflammation and lipolysis in adult mice.
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Affiliation(s)
- Hanna Heikelä
- Turku Center for Disease Modeling, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Suvi T Ruohonen
- Turku Center for Disease Modeling, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Marion Adam
- Turku Center for Disease Modeling, Institute of Biomedicine, University of Turku, Turku, Finland
| | | | - Heidi Liljenbäck
- Turku Center for Disease Modeling, Institute of Biomedicine, University of Turku, Turku, Finland
- Turku PET Centre, University of Turku, Turku, Finland
| | - Olli Eskola
- Turku PET Centre, University of Turku, Turku, Finland
| | - Michael Gabriel
- Turku Center for Disease Modeling, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Laura Mairinoja
- Turku Center for Disease Modeling, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Alberto Pessia
- Institute for Molecular Medicine Finland, University of Helsinki, Helsinki, Finland
| | - Vidya Velagapudi
- Institute for Molecular Medicine Finland, University of Helsinki, Helsinki, Finland
| | - Anne Roivainen
- Turku Center for Disease Modeling, Institute of Biomedicine, University of Turku, Turku, Finland
- Turku PET Centre, University of Turku, Turku, Finland
- Turku PET Centre, Turku University Hospital, Turku, Finland
| | - Fu-Ping Zhang
- Turku Center for Disease Modeling, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Leena Strauss
- Turku Center for Disease Modeling, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Matti Poutanen
- Turku Center for Disease Modeling, Institute of Biomedicine, University of Turku, Turku, Finland
- Department of Internal Medicine, Institute of Medicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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Bayerle A, Marsching C, Rabionet M, Dworski S, Kamani MA, Chitraju C, Gluchowski NL, Gabriel KR, Herzer S, Jennemann R, Levade T, Medin JA, Sandhoff R. Endogenous levels of 1-O-acylceramides increase upon acidic ceramidase deficiency and decrease due to loss of Dgat1 in a tissue-dependent manner. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158741. [PMID: 32474112 DOI: 10.1016/j.bbalip.2020.158741] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 04/19/2020] [Accepted: 05/15/2020] [Indexed: 02/03/2023]
Abstract
Except for epidermis and liver, little is known about endogenous expression of 1-O-acylceramides (1-OACs) in mammalian tissue. Therefore, we screened several organs (brain, lung, liver, spleen, lymph nodes, heart, kidney, thymus, small intestine, and colon) from mice for the presence of 1-OACs by LC-MS2. In most organs, low levels of about 0.25-1.3 pmol 1-OACs/mg wet weight were recorded. Higher levels were detected in liver, small and large intestines, with about 4-13 pmol 1-OACs/mg wet weight. 1-OACs were esterified mainly with palmitic, stearic, or oleic acids. Esterification with saturated very long-chain fatty acids, as in epidermis, was not observed. Western-type diet induced 3-fold increased 1-OAC levels in mice livers while ceramides were unaltered. In a mouse model of Farber disease with a decrease of acid ceramidase activity, we observed a strong, up to 50-fold increase of 1-OACs in lung, thymus, and spleen. In contrast, 1-OAC levels were reduced 0.54-fold in liver. Only in lung 1-OAC levels correlated to changes in ceramide levels - indicating tissue-specific mechanisms of regulation. Glucosylceramide synthase deficiency in liver did not cause changes in 1-OAC or ceramide levels, whereas increased ceramide levels in glucosylceramide synthase-deficient small intestine caused an increase in 1-OAC levels. Deficiency of Dgat1 in mice resulted in a reduction of 1-OACs to 30% in colon, but not in small intestine and liver, going along with constant free ceramides levels. From these data, we conclude that Dgat1 as well as lysosomal lipid metabolism contribute in vivo to homeostatic 1-OAC levels in an organ-specific manner.
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Affiliation(s)
- Aline Bayerle
- Lipid Pathobiochemistry Group, German Cancer Research Center, Heidelberg, Germany
| | - Christian Marsching
- Lipid Pathobiochemistry Group, German Cancer Research Center, Heidelberg, Germany; Center for Applied Research in Biomedical Mass Spectrometry (ABIMAS), Mannheim, Germany; Instrumental Analytics and Bioanalytics, Mannheim University of Applied Sciences, Mannheim, Germany; Center for Mass Spectrometry and Optical Spectroscopy (CeMOS), Mannheim University of Applied Sciences, Mannheim, Germany
| | - Mariona Rabionet
- Lipid Pathobiochemistry Group, German Cancer Research Center, Heidelberg, Germany
| | - Shaalee Dworski
- Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada
| | | | - Chandramohan Chitraju
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA; Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Nina L Gluchowski
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA; Department of Cell Biology, Harvard Medical School, Boston, MA, USA; Division of Gastroenterology and Nutrition, Boston Children's Hospital, Boston, MA, USA
| | - Katlyn R Gabriel
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA; Department of Cell Biology, Harvard Medical School, Boston, MA, USA; Howard Hughes Medical Institute, Boston, MA, USA
| | - Silke Herzer
- Lipid Pathobiochemistry Group, German Cancer Research Center, Heidelberg, Germany
| | - Richard Jennemann
- Lipid Pathobiochemistry Group, German Cancer Research Center, Heidelberg, Germany
| | - Thierry Levade
- Laboratoire de Biochimie Métabolique, Institut Fédératif de Biologie, CHU Purpan, INSERM UMR1037 CRCT, Toulouse, France
| | - Jeffrey A Medin
- Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada; University Health Network, Toronto, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada; Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Roger Sandhoff
- Lipid Pathobiochemistry Group, German Cancer Research Center, Heidelberg, Germany; Center for Applied Research in Biomedical Mass Spectrometry (ABIMAS), Mannheim, Germany.
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31
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Jeon S, Carr R. Alcohol effects on hepatic lipid metabolism. J Lipid Res 2020; 61:470-479. [PMID: 32029510 DOI: 10.1194/jlr.r119000547] [Citation(s) in RCA: 108] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 01/28/2020] [Indexed: 12/16/2022] Open
Abstract
Alcoholic liver disease (ALD) is the most prevalent type of chronic liver disease with significant morbidity and mortality worldwide. ALD begins with simple hepatic steatosis and progresses to alcoholic steatohepatitis, fibrosis, and cirrhosis. The severity of hepatic steatosis is highly associated with the development of later stages of ALD. This review explores the disturbances of alcohol-induced hepatic lipid metabolism through altered hepatic lipid uptake, de novo lipid synthesis, fatty acid oxidation, hepatic lipid export, and lipid droplet formation and catabolism. In addition, we review emerging data on the contributions of genetics and bioactive lipid metabolism in alcohol-induced hepatic lipid accumulation.
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Affiliation(s)
- Sookyoung Jeon
- Division of Gastroenterology, University of Pennsylvania, Philadelphia, PA
| | - Rotonya Carr
- Division of Gastroenterology, University of Pennsylvania, Philadelphia, PA
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32
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Løvsletten NG, Vu H, Skagen C, Lund J, Kase ET, Thoresen GH, Zammit VA, Rustan AC. Treatment of human skeletal muscle cells with inhibitors of diacylglycerol acyltransferases 1 and 2 to explore isozyme-specific roles on lipid metabolism. Sci Rep 2020; 10:238. [PMID: 31937853 PMCID: PMC6959318 DOI: 10.1038/s41598-019-57157-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 12/19/2019] [Indexed: 12/30/2022] Open
Abstract
Diacylglycerol acyltransferases (DGAT) 1 and 2 catalyse the final step in triacylglycerol (TAG) synthesis, the esterification of fatty acyl-CoA to diacylglycerol. Despite catalysing the same reaction and being present in the same cell types, they exhibit different functions on lipid metabolism in various tissues. Yet, their roles in skeletal muscle remain poorly defined. In this study, we investigated how selective inhibitors of DGAT1 and DGAT2 affected lipid metabolism in human primary skeletal muscle cells. The results showed that DGAT1 was dominant in human skeletal muscle cells utilizing fatty acids (FAs) derived from various sources, both exogenously supplied FA, de novo synthesised FA, or FA derived from lipolysis, to generate TAG, as well as being involved in de novo synthesis of TAG. On the other hand, DGAT2 seemed to be specialised for de novo synthesis of TAG from glycerol-3-posphate only. Interestingly, DGAT activities were also important for regulating FA oxidation, indicating a key role in balancing FAs between storage in TAG and efficient utilization through oxidation. Finally, we observed that inhibition of DGAT enzymes could potentially alter glucose-FA interactions in skeletal muscle. In summary, treatment with DGAT1 or DGAT2 specific inhibitors resulted in different responses on lipid metabolism in human myotubes, indicating that the two enzymes play distinct roles in TAG metabolism in skeletal muscle.
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Affiliation(s)
- Nils G Løvsletten
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, Oslo, Norway
| | - Helene Vu
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, Oslo, Norway
| | - Christine Skagen
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, Oslo, Norway
| | - Jenny Lund
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, Oslo, Norway
| | - Eili T Kase
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, Oslo, Norway
| | - G Hege Thoresen
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, Oslo, Norway.,Department of Pharmacology, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Victor A Zammit
- Division of Translational and Experimental medicine, Warwick Medical School, University of Warwick, Coventry, UK
| | - Arild C Rustan
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, Oslo, Norway.
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33
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Schlame M, Xu Y, Erdjument-Bromage H, Neubert TA, Ren M. Lipidome-wide 13C flux analysis: a novel tool to estimate the turnover of lipids in organisms and cultures. J Lipid Res 2020; 61:95-104. [PMID: 31712250 PMCID: PMC6939592 DOI: 10.1194/jlr.d119000318] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 11/07/2019] [Indexed: 01/12/2023] Open
Abstract
Lipid metabolism plays an important role in the regulation of cellular homeostasis. However, because it is difficult to measure the actual rates of synthesis and degradation of individual lipid species, lipid compositions are often used as a surrogate to evaluate lipid metabolism even though they provide only static snapshots of the lipodome. Here, we designed a simple method to determine the turnover rate of phospholipid and acylglycerol species based on the incorporation of 13C6-glucose combined with LC-MS/MS. We labeled adult Drosophila melanogaster with 13C6-glucose that incorporates into the entire lipidome, derived kinetic parameters from mass spectra, and studied effects of deletion of CG6718, the fly homolog of the calcium-independent phospholipase A2β, on lipid metabolism. Although 13C6-glucose gave rise to a complex pattern of 13C incorporation, we were able to identify discrete isotopomers in which 13C atoms were confined to the glycerol group. With these isotopomers, we calculated turnover rate constants, half-life times, and fluxes of the glycerol backbone of multiple lipid species. To perform these calculations, we estimated the fraction of labeled molecules in glycerol-3-phosphate, the lipid precursor, by mass isotopomer distribution analysis of the spectra of phosphatidylglycerol. When we applied this method to D. melanogaster, we found a range of lipid half-lives from 2 to 200 days, demonstrated tissue-specific fluxes of individual lipid species, and identified a novel function of CG6718 in triacylglycerol metabolism. This method provides fluxomics-type data with significant potential to improve the understanding of complex lipid regulation in a variety of research models.
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Affiliation(s)
- Michael Schlame
- Departments of Anesthesiology, New York University School of Medicine, New York, NY 10016; Cell Biology, New York University School of Medicine, New York, NY 10016.
| | - Yang Xu
- Departments of Anesthesiology, New York University School of Medicine, New York, NY 10016
| | - Hediye Erdjument-Bromage
- Cell Biology, New York University School of Medicine, New York, NY 10016; Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY 10016
| | - Thomas A Neubert
- Cell Biology, New York University School of Medicine, New York, NY 10016; Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY 10016
| | - Mindong Ren
- Departments of Anesthesiology, New York University School of Medicine, New York, NY 10016; Cell Biology, New York University School of Medicine, New York, NY 10016
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34
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Gluchowski NL, Gabriel KR, Chitraju C, Bronson RT, Mejhert N, Boland S, Wang K, Lai ZW, Farese RV, Walther TC. Hepatocyte Deletion of Triglyceride-Synthesis Enzyme Acyl CoA: Diacylglycerol Acyltransferase 2 Reduces Steatosis Without Increasing Inflammation or Fibrosis in Mice. Hepatology 2019; 70:1972-1985. [PMID: 31081165 PMCID: PMC6893913 DOI: 10.1002/hep.30765] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 05/05/2019] [Indexed: 12/31/2022]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is characterized by excess lipid accumulation in hepatocytes and represents a huge public health problem owing to its propensity to progress to nonalcoholic steatohepatitis, fibrosis, and liver failure. The lipids stored in hepatic steatosis (HS) are primarily triglycerides (TGs) synthesized by two acyl-CoA:diacylglycerol acyltransferase (DGAT) enzymes. Either DGAT1 or DGAT2 catalyzes this reaction, and these enzymes have been suggested to differentially utilize exogenous or endogenously synthesized fatty acids, respectively. DGAT2 has been linked to storage of fatty acids from de novo lipogenesis, a process increased in NAFLD. However, whether DGAT2 is more responsible for lipid accumulation in NAFLD and progression to fibrosis is currently unknown. Also, it is unresolved whether DGAT2 can be safely inhibited as a therapy for NAFLD. Here, we induced NAFLD-like disease in mice by feeding a diet rich in fructose, saturated fat, and cholesterol and found that hepatocyte-specific Dgat2 deficiency reduced expression of de novo lipogenesis genes and lowered liver TGs by ~70%. Importantly, the reduction in steatosis was not accompanied by increased inflammation or fibrosis, and insulin and glucose metabolism were unchanged. Conclusion: This study suggests that hepatic DGAT2 deficiency successfully reduces diet-induced HS and supports development of DGAT2 inhibitors as a therapeutic strategy for treating NAFLD and preventing downstream consequences.
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Affiliation(s)
- Nina L. Gluchowski
- Division of Gastroenterology and Nutrition, Boston Children’s Hospital, Boston, MA
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA
- Department of Cell Biology, Harvard Medical School, Boston, MA
| | - Katlyn R. Gabriel
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA
- Department of Cell Biology, Harvard Medical School, Boston, MA
- Howard Hughes Medical Institute, Boston, MA
| | - Chandramohan Chitraju
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA
- Department of Cell Biology, Harvard Medical School, Boston, MA
| | | | - Niklas Mejhert
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA
- Department of Cell Biology, Harvard Medical School, Boston, MA
| | - Sebastian Boland
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA
- Department of Cell Biology, Harvard Medical School, Boston, MA
| | - Kun Wang
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA
- Department of Cell Biology, Harvard Medical School, Boston, MA
| | - Zon Weng Lai
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA
- Department of Cell Biology, Harvard Medical School, Boston, MA
| | - Robert V. Farese
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA
- Department of Cell Biology, Harvard Medical School, Boston, MA
- Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA
| | - Tobias C. Walther
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA
- Department of Cell Biology, Harvard Medical School, Boston, MA
- Howard Hughes Medical Institute, Boston, MA
- Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA
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35
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Multiplexed and single cell tracing of lipid metabolism. Nat Methods 2019; 16:1123-1130. [DOI: 10.1038/s41592-019-0593-6] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 09/10/2019] [Indexed: 12/19/2022]
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36
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Jiang Y, Xie M, Fan W, Xue J, Zhou Z, Tang J, Chen G, Hou S. Transcriptome Analysis Reveals Differential Expression of Genes Regulating Hepatic Triglyceride Metabolism in Pekin Ducks During Dietary Threonine Deficiency. Front Genet 2019; 10:710. [PMID: 31428138 PMCID: PMC6688585 DOI: 10.3389/fgene.2019.00710] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Accepted: 07/04/2019] [Indexed: 12/12/2022] Open
Abstract
Dietary threonine (Thr) deficiency increases hepatic triglyceride accumulation in Pekin ducks, which results in fatty liver disease and impairs hepatic function. However, the underlying molecular mechanisms altered by dietary Thr deficiency are still unknown. To identify the underlying molecular changes, 180 one-day-old ducklings were divided into three groups, including Thr deficiency group (Thr-D), Thr sufficiency group (Thr-S), and pair-fed group (Pair-F) that was fed with a Thr-sufficient diet but with reduced daily feed intake. The results showed that feed intake was similar between Thr-D and Pair-F groups, but weight gain rate and final body weight in the Thr-D group were lower than those in the Pair-F group. Feed intake, weight gain, and body weight in Thr-D and Pair-F groups were lower than those in the Thr-S group. The Thr-D diet reduced abdominal fat percentage but increased hepatic triglyceride content when compared with that of the Thr-S and Pair-F groups. The Pair-F reduced hepatic levels of C15:0, C17:0, C18:0, C20:0, C20:4n6, and C22:0 and also reduced total fatty acid, saturated fatty acid, and unsaturated fatty acid content when compared with those of the Thr-D and Thr-S groups. The Thr-D diet increased hepatic content of C6:0, C17:1, C18:3n6, C20:0, C20:1n9, and C22:2, as well as reduced the content of C18:2n6t and C23:0 when compared with those of the Thr-S group. Transcriptome analysis in the liver indicated that the Thr-D diet upregulated genes related to fatty acid and triglyceride synthesis and downregulated genes related to fatty acid oxidation and triglyceride transport. Gene ontology analysis showed that more genes related to lipid metabolism processes and molecular function were differentially expressed in the Thr-D group relative to Thr-S and Pair-F groups than in the Pair-F group relative to the Thr-S group. KEGG pathway analysis showed that differentially expressed genes were enriched in signal transduction, immune, hormone, lipid, and amino acid metabolism pathways. Our findings indicated that the Thr-D diet increased hepatic triglyceride and fatty acid accumulation via increasing fatty acid and triglyceride synthesis and reducing fatty acid oxidation and triglyceride transport. These findings provide novel insights into our understanding of the molecular mechanisms underlying fat accumulation in the liver caused by dietary threonine deficiency.
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Affiliation(s)
- Yong Jiang
- Key Laboratory of Animal (Poultry) Genetics Breeding and Reproduction, Ministry of Agriculture and Rural Affairs; Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China.,College of Animal Science and Technology, Yangzhou University, Yangzhou, China
| | - Ming Xie
- Key Laboratory of Animal (Poultry) Genetics Breeding and Reproduction, Ministry of Agriculture and Rural Affairs; Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Wenlei Fan
- Key Laboratory of Animal (Poultry) Genetics Breeding and Reproduction, Ministry of Agriculture and Rural Affairs; Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China.,College of Food Science and Engineering, Qingdao Agricultural University, Qingdao, China
| | - Jiajia Xue
- Key Laboratory of Animal (Poultry) Genetics Breeding and Reproduction, Ministry of Agriculture and Rural Affairs; Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Zhengkui Zhou
- Key Laboratory of Animal (Poultry) Genetics Breeding and Reproduction, Ministry of Agriculture and Rural Affairs; Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jing Tang
- Key Laboratory of Animal (Poultry) Genetics Breeding and Reproduction, Ministry of Agriculture and Rural Affairs; Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Guohong Chen
- College of Animal Science and Technology, Yangzhou University, Yangzhou, China
| | - Shuisheng Hou
- Key Laboratory of Animal (Poultry) Genetics Breeding and Reproduction, Ministry of Agriculture and Rural Affairs; Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
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37
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Alves-Bezerra M, Li Y, Acuña M, Ivanova AA, Corey KE, Ortlund EA, Cohen DE. Thioesterase Superfamily Member 2 Promotes Hepatic VLDL Secretion by Channeling Fatty Acids Into Triglyceride Biosynthesis. Hepatology 2019; 70:496-510. [PMID: 30516845 PMCID: PMC6551314 DOI: 10.1002/hep.30411] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 11/30/2018] [Indexed: 12/18/2022]
Abstract
In nonalcoholic fatty liver disease (NAFLD), triglycerides accumulate within the liver because the rates of fatty acid accrual by uptake from plasma and de novo synthesis exceed elimination by mitochondrial oxidation and secretion as very low-density lipoprotein (VLDL) triglycerides. Thioesterase superfamily member 2 (Them2) is an acyl-coenzyme A (CoA) thioesterase that catalyzes the hydrolysis of fatty acyl-CoAs into free fatty acids plus CoASH. Them2 is highly expressed in the liver, as well as other oxidative tissues. Mice globally lacking Them2 are resistant to diet-induced obesity and hepatic steatosis, and exhibit improved glucose homeostasis. These phenotypes are attributable, at least in part, to roles of Them2 in the suppression of thermogenesis in brown adipose tissue and insulin signaling in skeletal muscle. To elucidate the hepatic function of Them2, we created mice with liver-specific deletion of Them2 (L-Them2-/- ). Although L-Them2-/- mice were not protected against excess weight gain, hepatic steatosis or glucose intolerance, they exhibited marked decreases in plasma triglyceride and apolipoprotein B100 concentrations. These were attributable to reduced rates of VLDL secretion owing to decreased incorporation of plasma-derived fatty acids into triglycerides. The absence of hepatic steatosis in L-Them2-/- mice fed chow was explained by compensatory increases in rates of fatty acid oxidation and by decreased de novo lipogenesis in high fat-fed mice. Consistent with a role for Them2 in hepatic VLDL secretion, THEM2 levels were increased in livers of obese patients with NAFLD characterized by simple steatosis. Conclusion: Them2 functions in the liver to direct fatty acids toward triglyceride synthesis for incorporation into VLDL particles. When taken together with its functions in brown adipose and muscle, these findings suggest that Them2 is a target for the management of NAFLD and dyslipidemia.
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Affiliation(s)
- Michele Alves-Bezerra
- Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY 10021, USA
| | - Yingxia Li
- Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY 10021, USA
| | - Mariana Acuña
- Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY 10021, USA
| | - Anna A. Ivanova
- Emory Integrated Lipidomics Core, Emory University, Atlanta, GA 30322, USA
| | - Kathleen E. Corey
- Gastrointestinal Unit, Massachusetts General Hospital, Boston, MA, 02114, USA,Harvard Medical School, Boston, MA 02115, USA
| | - Eric A. Ortlund
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - David E. Cohen
- Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY 10021, USA,Corresponding author at: Weill Cornell Medical College, Belfer Research Building, 413 E. 69 Street, room 630, New York, NY 10021, USA. Tel.: +1 (646) 962 7681; Fax: +1 (646) 962 0427;
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38
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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: 82] [Impact Index Per Article: 16.4] [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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39
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Beaudry KM, Devries MC. Sex-based differences in hepatic and skeletal muscle triglyceride storage and metabolism 1. Appl Physiol Nutr Metab 2019; 44:805-813. [PMID: 30702924 DOI: 10.1139/apnm-2018-0635] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Women and men store lipid differently within the body with men storing more fat in the android region and women storing more fat in the gynoid region. Fat is predominately stored in adipose tissue as triacylglycerides (TG); however, TG are also stored in other tissues including the liver and skeletal muscle. Excess hepatic TG storage, defined as a TG concentration >5% of liver weight and known as nonalcoholic fatty liver disease (NAFLD), is related to the metabolic syndrome. Similarly, elevated skeletal muscle TG, termed intramyocellular lipids (IMCL), are related to insulin resistance in obesity and type II diabetes. Men store more hepatic TG than women and, unsurprisingly, NAFLD is more prevalent in men than women. Women store more IMCL than men, yet type II diabetes risk is not greater, which is likely due to the manner in which women store TG within muscle. Sex-based differences in TG storage between men and women are underpinned by differences in messenger RNA expression, protein content, and enzyme activities of skeletal muscle and hepatic lipid metabolic pathways. Furthermore, women have a greater reliance on lipid during exercise because of upregulation of lipid oxidative pathways. The purpose of this review is to discuss the role of sex in mediating lipid storage and metabolism within skeletal muscle and the liver at rest and during exercise and its relationship with metabolic disease.
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Affiliation(s)
- Kayleigh M Beaudry
- Department of Kinesiology, Faculty of Applied Health Sciences, University of Waterloo, Waterloo, ON N2L 3G1, Canada.,Department of Kinesiology, Faculty of Applied Health Sciences, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Michaela C Devries
- Department of Kinesiology, Faculty of Applied Health Sciences, University of Waterloo, Waterloo, ON N2L 3G1, Canada.,Department of Kinesiology, Faculty of Applied Health Sciences, University of Waterloo, Waterloo, ON N2L 3G1, Canada
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40
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Irshad Z, Chmel N, Adya R, Zammit VA. Hepatic VLDL secretion: DGAT1 determines particle size but not particle number, which can be supported entirely by DGAT2. J Lipid Res 2019; 60:111-120. [PMID: 30397187 PMCID: PMC6314258 DOI: 10.1194/jlr.m089300] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 10/08/2018] [Indexed: 12/25/2022] Open
Abstract
We investigated whether, in view of its activity being expressed on both aspects of the endoplasmic reticulum (ER; dual membrane topology), diacylglycerol acyltransferase 1 (DGAT1) plays a distinctive role in determining the triglyceride (TAG) content of VLDL particles secreted by the liver. Mice in which the DGAT1 gene was specifically ablated in hepatocytes (DGAT1-LKO mice) had the same number of VLDL particles (apoB concentration) in the plasma 1 h after Triton 1339 treatment, but these particles were approximately half the size of VLDL particles secreted by control mice and had a proportionately decreased content of TAG, with normal cholesterol and cholesteryl ester contents. Analyses of purified microsomal fractions prepared from 16 h fasted control and DAGT1-LKO mice showed that the TAG/protein ratio in the ER was significantly lower in the latter. Electron micrographs of these livers showed that those from DGAT1-LKO mice did not show the increased lipid content of the smooth ER shown by control livers. The effects of DGAT1- and DGAT2-specific inhibitors on apoB secretion by HepG2 cells showed that DGAT1 is not indispensable for apoB secretion and demonstrated redundancy in the ability of the two enzymes to support apoB secretion. Therefore, our findings show that DGAT1 is essential for the complete lipidation and maturation of VLDL particles within the lumen of the ER, consistent with its dual topology within the ER membrane. In the mouse, DGAT2 can support apoB secretion (particle number) even when TAG availability for full VLDL lipidation is restricted in the absence of DGAT1.
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Affiliation(s)
- Zehra Irshad
- Translational and Experimental Medicine, Warwick Medical School, Coventry CV4 7AL, United Kingdom
| | - Nikola Chmel
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Raghu Adya
- Translational and Experimental Medicine, Warwick Medical School, Coventry CV4 7AL, United Kingdom
| | - Victor A Zammit
- Translational and Experimental Medicine, Warwick Medical School, Coventry CV4 7AL, United Kingdom
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41
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Hernández-Corbacho MJ, Obeid LM. A novel role for DGATs in cancer. Adv Biol Regul 2018; 72:89-101. [PMID: 30579761 DOI: 10.1016/j.jbior.2018.12.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 12/09/2018] [Accepted: 12/10/2018] [Indexed: 02/06/2023]
Affiliation(s)
- María José Hernández-Corbacho
- Stony Brook Cancer Center and the Department of Medicine, Stony Brook University, Health Sciences Center, Stony Brook, NY, 11794, USA
| | - Lina M Obeid
- Stony Brook Cancer Center and the Department of Medicine, Stony Brook University, Health Sciences Center, Stony Brook, NY, 11794, USA; The Northport VA Medical Center, Northport, NY, 11768, USA.
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Lane AN, Higashi RM, Fan TWM. NMR and MS-based Stable Isotope-Resolved Metabolomics and Applications in Cancer Metabolism. Trends Analyt Chem 2018; 120. [PMID: 32523238 DOI: 10.1016/j.trac.2018.11.020] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
There is considerable interest in defining metabolic reprogramming in human diseases, which is recognized as a hallmark of human cancer. Although radiotracers have a long history in specific metabolic studies, stable isotope-enriched precursors coupled with modern high resolution mass spectrometry and NMR spectroscopy have enabled systematic mapping of metabolic networks and fluxes in cells, tissues and living organisms including humans. These analytical platforms are high in information content, are complementary and cross-validating in terms of compound identification, quantification, and isotope labeling pattern analysis of a large number of metabolites simultaneously. Furthermore, new developments in chemoselective derivatization and in vivo spectroscopy enable tracking of labile/low abundance metabolites and metabolic kinetics in real-time. Here we review developments in Stable Isotope Resolved Metabolomics (SIRM) and recent applications in cancer metabolism using a wide variety of stable isotope tracers that probe both broad and specific aspects of cancer metabolism required for proliferation and survival.
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Affiliation(s)
- Andrew N Lane
- Center for Environmental and Systems Biochemistry, Dept. Toxicology and Cancer Biology, Markey Cancer Center, University of Kentucky, 789 S. Limestone St., Lexington, KY 40536 USA
| | - Richard M Higashi
- Center for Environmental and Systems Biochemistry, Dept. Toxicology and Cancer Biology, Markey Cancer Center, University of Kentucky, 789 S. Limestone St., Lexington, KY 40536 USA
| | - Teresa W-M Fan
- Center for Environmental and Systems Biochemistry, Dept. Toxicology and Cancer Biology, Markey Cancer Center, University of Kentucky, 789 S. Limestone St., Lexington, KY 40536 USA
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43
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Triebl A, Wenk MR. Analytical Considerations of Stable Isotope Labelling in Lipidomics. Biomolecules 2018; 8:biom8040151. [PMID: 30453585 PMCID: PMC6315579 DOI: 10.3390/biom8040151] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 11/12/2018] [Accepted: 11/13/2018] [Indexed: 12/26/2022] Open
Abstract
Over the last two decades, lipids have come to be understood as far more than merely components of cellular membranes and forms of energy storage, and are now also being implicated to play important roles in a variety of diseases, with lipid biomarker research one of the most widespread applications of lipidomic techniques both in research and in clinical settings. Stable isotope labelling has become a staple technique in the analysis of small molecule metabolism and dynamics, as it is the only experimental setup by which biosynthesis, remodelling and degradation of biomolecules can be directly measured. Using state-of-the-art analytical technologies such as chromatography-coupled high resolution tandem mass spectrometry, the stable isotope label can be precisely localized and quantified within the biomolecules. The application of stable isotope labelling to lipidomics is however complicated by the diversity of lipids and the complexity of the necessary data analysis. This article discusses key experimental aspects of stable isotope labelling in the field of mass spectrometry-based lipidomics, summarizes current applications and provides an outlook on future developments and potential.
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Affiliation(s)
- Alexander Triebl
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore; Singapore 117596, Singapore.
| | - Markus R Wenk
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore; Singapore 117596, Singapore.
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Pabst B, Futatsugi K, Li Q, Ahn K. Mechanistic Characterization of Long Residence Time Inhibitors of Diacylglycerol Acyltransferase 2 (DGAT2). Biochemistry 2018; 57:6997-7010. [DOI: 10.1021/acs.biochem.8b01096] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Steinbrenner H, Micoogullari M, Hoang NA, Bergheim I, Klotz LO, Sies H. Selenium-binding protein 1 (SELENBP1) is a marker of mature adipocytes. Redox Biol 2018; 20:489-495. [PMID: 30469030 PMCID: PMC6249406 DOI: 10.1016/j.redox.2018.11.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 11/01/2018] [Accepted: 11/06/2018] [Indexed: 12/18/2022] Open
Abstract
Selenium-binding protein 1 (SELENBP1) has recently been reported to catalyse the oxidation of methanethiol, an organosulfur compound produced by gut microbiota. Two of the reaction products of methanethiol oxidation, hydrogen peroxide and hydrogen sulphide, serve as signalling molecules for cell differentiation. Indeed, colonocyte differentiation has been found to be associated with SELENBP1 induction. Here, we show that SELENBP1 is induced when 3T3-L1 preadipocytes undergo terminal differentiation and maturation to adipocytes. SELENBP1 induction succeeded the up-regulation of known marker proteins of white adipocytes and the intracellular accumulation of lipids. Immunofluorescence microscopy revealed predominant cytoplasmic localisation of SELENBP1 in 3T3-L1 adipocytes, as demonstrated by co-staining with the key lipogenic enzyme, acetyl-CoA-carboxylase (ACC), located in cytosol. In differentiating 3T3-L1 cells, the mTOR inhibitor rapamycin and the pro-inflammatory cytokine tumour necrosis factor alpha (TNF-α) likewise suppressed SELENBP1 induction, adipocyte differentiation and lipid accumulation. However, lipid accumulation per se is not linked to SELENBP1 induction, as hepatic SELENBP1 was down-regulated in high fructose-fed mice despite increased lipogenesis in the liver and development of non-alcoholic fatty liver disease (NAFLD). In conclusion, SELENBP1 is a marker of cell differentiation/maturation rather than being linked to lipogenesis/lipid accumulation.
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Affiliation(s)
- Holger Steinbrenner
- Institute of Nutritional Sciences, Nutrigenomics, Friedrich Schiller University Jena, Jena, Germany.
| | - Mustafa Micoogullari
- Institute of Biochemistry and Molecular Biology I, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Ngoc Anh Hoang
- Institute of Nutritional Sciences, Nutrigenomics, Friedrich Schiller University Jena, Jena, Germany
| | - Ina Bergheim
- Department of Nutritional Sciences, Molecular Nutritional Science, University Vienna, Vienna, Austria
| | - Lars-Oliver Klotz
- Institute of Nutritional Sciences, Nutrigenomics, Friedrich Schiller University Jena, Jena, Germany
| | - Helmut Sies
- Institute of Biochemistry and Molecular Biology I, Heinrich Heine University Düsseldorf, Düsseldorf, Germany; Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
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46
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Huang LS, Yuen JJ, Trites MJ, Saha A, Epps CT, Hu Y, Kerolle S, Lee SA, Jiang H, Goldberg IJ, Blaner WS, Clugston RD. Dietary Macronutrient Composition Determines the Contribution of DGAT1 to Alcoholic Steatosis. Alcohol Clin Exp Res 2018; 42:2298-2312. [PMID: 30192394 PMCID: PMC6286229 DOI: 10.1111/acer.13881] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 09/02/2018] [Indexed: 01/01/2023]
Abstract
Background The first stage of alcoholic liver disease is hepatic steatosis. While alcohol is known to profoundly impact hepatic lipid metabolism, gaps in our knowledge remain regarding the mechanisms leading to alcohol‐induced hepatic triglyceride (TG) accumulation. As the sole enzymes catalyzing the final step in TG synthesis, diacylglycerol O‐acyltransferase (DGAT) 1 and 2 are potentially important contributors to alcoholic steatosis. Our goal was to study the effects of dietary fat content on alcohol‐induced hepatic TG accumulation, and the relative contribution of DGAT1 and DGAT2 to alcoholic steatosis. Methods These studies were carried out in wild‐type (WT) mice fed alcohol‐containing high‐fat or low‐fat formulations of Lieber‐DeCarli liquid diets, as well as follow‐up studies in Dgat1−/− mice. Results A direct comparison of the low‐fat and high‐fat liquid diet in WT mice revealed surprisingly similar levels of alcoholic steatosis, although there were underlying differences in the pattern of hepatic lipid accumulation and expression of genes involved in hepatic lipid metabolism. Follow‐up studies in Dgat1−/− mice revealed that these animals are protected from alcoholic steatosis when consumed as part of a high‐fat diet, but not a low‐fat diet. Conclusions Dietary macronutrient composition influences the relative contribution of DGAT1 and DGAT2 to alcoholic steatosis, such that in the context of alcohol and a high‐fat diet, DGAT1 predominates.
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Affiliation(s)
- Li-Shin Huang
- Department of Medicine, Columbia University, New York, New York
| | - Jason J Yuen
- Department of Medicine, Columbia University, New York, New York
| | - Michael J Trites
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
| | - Amit Saha
- Department of Medicine, Columbia University, New York, New York
| | - Caleb T Epps
- Department of Medicine, Columbia University, New York, New York
| | - Yungying Hu
- Department of Medicine, New York University Langone Medical Center, New York, New York
| | | | - Seung-Ah Lee
- Department of Medicine, Columbia University, New York, New York
| | - Hongfeng Jiang
- Department of Medicine, Columbia University, New York, New York
| | - Ira J Goldberg
- Department of Medicine, New York University Langone Medical Center, New York, New York
| | | | - Robin D Clugston
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
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Bhatt-Wessel B, Jordan TW, Miller JH, Peng L. Role of DGAT enzymes in triacylglycerol metabolism. Arch Biochem Biophys 2018; 655:1-11. [PMID: 30077544 DOI: 10.1016/j.abb.2018.08.001] [Citation(s) in RCA: 107] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 07/25/2018] [Accepted: 08/02/2018] [Indexed: 01/22/2023]
Abstract
The esterification of a fatty acyl moiety to diacylglycerol to form triacylglycerol (TAG) is catalysed by two diacylglycerol O-acyltransferases (DGATs) encoded by genes belonging to two distinct gene families. The enzymes are referred to as DGAT1 and DGAT2 in order of their identification. Both proteins are transmembrane proteins localized in the endoplasmic reticulum. Their membrane topologies are however significantly different. This difference is hypothesized to give the two isozymes different abilities to interact with other proteins and organelles and access to different pools of fatty acids, thereby creating a distinction between the enzymes in terms of their role and contribution to lipid metabolism. DGAT1 is proposed to have dual topology contributing to TAG synthesis on both sides of the ER membrane and esterifying only the pre-formed fatty acids. There is evidence to suggest that DGAT2 translocates to the lipid droplet (LD), associates with other proteins, and synthesizes cytosolic and luminal apolipoprotein B associated LD-TAG from both endogenous and exogenous fatty acids. The aim of this review is to differentiate between the two DGAT enzymes by comparing the genes that encode them, their proposed topologies, the proteins they interact with, and their roles in lipid metabolism.
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Affiliation(s)
- Bhumika Bhatt-Wessel
- Centre for Biodiscovery and School of Biological Sciences, Victoria University of Wellington, New Zealand
| | - T William Jordan
- Centre for Biodiscovery and School of Biological Sciences, Victoria University of Wellington, New Zealand
| | - John H Miller
- Centre for Biodiscovery and School of Biological Sciences, Victoria University of Wellington, New Zealand
| | - Lifeng Peng
- Centre for Biodiscovery and School of Biological Sciences, Victoria University of Wellington, New Zealand.
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Kawashima Y, Eguchi Y, Yamazaki T, Karahashi M, Kawai H, Kudo N. Reduction in Secretion of Very Low Density Lipoprotein–Triacylglycerol by a Matrix Metalloproteinase Inhibitor in a Rat Model of Diet-Induced Hypertriglyceridemia. J Pharmacol Exp Ther 2018; 366:194-204. [DOI: 10.1124/jpet.117.246165] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 05/03/2018] [Indexed: 01/11/2023] Open
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Goh B, Kim J, Seo S, Kim TY. High-Throughput Measurement of Lipid Turnover Rates Using Partial Metabolic Heavy Water Labeling. Anal Chem 2018; 90:6509-6518. [DOI: 10.1021/acs.analchem.7b05428] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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50
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Bai J, Wang P, Liu Y, Zhang Y, Li Y, He Z, Hou L, Liang R. Formaldehyde alters triglyceride synthesis and very low-density lipoprotein secretion in a time-dependent manner. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2017; 56:15-20. [PMID: 28866046 DOI: 10.1016/j.etap.2017.08.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 08/26/2017] [Indexed: 05/10/2023]
Abstract
Formaldehyde is a common indoor air pollutant that is toxic to the liver. This study aimed to investigate the effects of formaldehyde on triglyceride metabolism in human hepatocellular carcinoma cells (HepG2). Cell viability was detected using a MTT (3-(4,5-dimethylthiazol-2-Yl)-2,5-diphenyltetrazolium bromide) assay. Following treatment with different concentrations of formaldehyde for 24 and 48h, the intra and extra-hepatocellular triglyceride (TG) content was determined using a chemical-enzymatic method; Western blotting was used to detect the levels of fatty acid synthesis and VLDL-related proteins. Our results showed that cell viability significantly decreased after formaldehyde treatment (0.5-12.5mM, 24/48h). Extracellular TG levels in the hepatocytes increased after formaldehyde treatment at 0.004mM-0.1mM for 24h. SREBP-1c, ACC, FASN, and MTP, CES3 and DGAT1 proteins increased significantly after 24h of formaldehyde treatment. Intracellular TG levels decreased for 48h treatment of formaldehyde. AMPKα increased significantly in all tested groups and p-AMPK increased significantly after 0.1mM formaldehyde treatment for 48h. Our results indicated that short-term formaldehyde exposure balances triglyceride metabolism by promoting hepatocellular TG synthesis and VLDL secretion; Long-term formaldehyde disturbs the TG metabolism balance in the hepatocytes.
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Affiliation(s)
- Jianying Bai
- Department of Environmental Health, School of Public Health, Shanxi Medical University, Taiyuan 030001, PR China.
| | - Pan Wang
- Department of Environmental Health, School of Public Health, Shanxi Medical University, Taiyuan 030001, PR China
| | - Yanfei Liu
- Department of Environmental Health, School of Public Health, Shanxi Medical University, Taiyuan 030001, PR China
| | - Yan Zhang
- Department of Environmental Health, School of Public Health, Shanxi Medical University, Taiyuan 030001, PR China
| | - Yaofu Li
- Department of Environmental Health, School of Public Health, Shanxi Medical University, Taiyuan 030001, PR China
| | - Zhen He
- Department of Environmental Health, School of Public Health, Shanxi Medical University, Taiyuan 030001, PR China
| | - Lifang Hou
- Department of Environmental Health, School of Public Health, Shanxi Medical University, Taiyuan 030001, PR China; Center for Population Epigenetics, Robert H. Lurie Comprehensive Cancer Center and Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Ruifeng Liang
- Department of Environmental Health, School of Public Health, Shanxi Medical University, Taiyuan 030001, PR China
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