1
|
Sharma AK, Wang T, Othman A, Khandelwal R, Balaz M, Modica S, Zamboni N, Wolfrum C. Basal re-esterification finetunes mitochondrial fatty acid utilization. Mol Metab 2023; 71:101701. [PMID: 36878315 PMCID: PMC10011057 DOI: 10.1016/j.molmet.2023.101701] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 02/27/2023] [Accepted: 02/28/2023] [Indexed: 03/06/2023] Open
Abstract
OBJECTIVE Emerging evidence suggest the existence of constant basal lipolysis and re-esterification of a substantial fraction of thus liberated fatty acids. In stimulated lipolysis, the re-esterification is proposed to be a protective mechanism against lipotoxicity; however, the role of the lipolysis coupled to re-esterification under basal conditions has not been deciphered. METHODS We used adipocytes (in vitro differentiated brown and white adipocytes derived from a cell line or primary SVF culture) to study the effect of inhibition of re-esterification by pharmacological DGAT1 and DGAT2 inhibitors alone or in combination. We then evaluated cellular energetics, lipolysis flux, and lipidomic parameters along with mitochondrial properties and fuel utilization. RESULTS In adipocytes, DGAT1 and 2 mediated re-esterification is a moderator of fatty acid oxidation. Combined inhibition of both DGATs (D1+2i) increases oxygen consumption, which is largely due to enhanced mitochondrial respiration by lipolysis-derived fatty acids (FAs). Acute D1+2i selectively affects mitochondrial respiration without affecting the transcriptional homeostasis of genes relevant to mitochondrial health and lipid metabolism. D1+2i enhances the mitochondrial import of pyruvate and activates AMP Kinase to counteract CPT1 antagonism, thus facilitating the mitochondrial import of fatty acyl-CoA. CONCLUSIONS These data implicate the process of re-esterification in the regulation of mitochondrial FA usage and uncover a mechanism of FAO regulation via crosstalk with FA re-esterification.
Collapse
Affiliation(s)
- Anand Kumar Sharma
- Laboratory of Translational Nutrition Biology, Institute of Food, Nutrition and Health, ETH Zurich, Schwerzenbach, Switzerland
| | - Tongtong Wang
- Laboratory of Translational Nutrition Biology, Institute of Food, Nutrition and Health, ETH Zurich, Schwerzenbach, Switzerland
| | - Alaa Othman
- Department of Biology, Institute of Molecular Systems Biology, ETH Zürich, Zürich, Switzerland
| | - Radhika Khandelwal
- Laboratory of Translational Nutrition Biology, Institute of Food, Nutrition and Health, ETH Zurich, Schwerzenbach, Switzerland
| | - Miroslav Balaz
- Laboratory of Translational Nutrition Biology, Institute of Food, Nutrition and Health, ETH Zurich, Schwerzenbach, Switzerland; Laboratory of Cellular and Molecular Metabolism, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Salvatore Modica
- Laboratory of Translational Nutrition Biology, Institute of Food, Nutrition and Health, ETH Zurich, Schwerzenbach, Switzerland
| | - Nicola Zamboni
- Department of Biology, Institute of Molecular Systems Biology, ETH Zürich, Zürich, Switzerland
| | - Christian Wolfrum
- Laboratory of Translational Nutrition Biology, Institute of Food, Nutrition and Health, ETH Zurich, Schwerzenbach, Switzerland.
| |
Collapse
|
2
|
Otaibi AA, Mubarak SA, Qarni AA, Hawwari A, Bakillah A, Iqbal J. ATP-Binding Cassette Protein ABCC10 Deficiency Prevents Diet-Induced Obesity but Not Atherosclerosis in Mice. Int J Mol Sci 2022; 23:ijms232213813. [PMID: 36430292 PMCID: PMC9694421 DOI: 10.3390/ijms232213813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 09/20/2022] [Accepted: 09/20/2022] [Indexed: 11/11/2022] Open
Abstract
Excess plasma lipid levels are a risk factor for various cardiometabolic disorders. Studies have shown that improving dyslipidemia lowers the progression of these disorders. In this study, we investigated the role of ATP-binding cassette transporter C10 (ABCC10) in regulating lipid metabolism. Our data indicate that deletion of the Abcc10 gene in male mice results in lower plasma and intestinal triglycerides by around 38% and 36%, respectively. Furthermore, deletion of ABCC10 ameliorates diet-induced obesity in mice and leads to a better response during insulin and glucose tolerance tests. Unexpectedly, ABCC10 deficiency does not affect triglyceride levels or atherosclerosis in ApoE-deficient mice. In addition, our studies demonstrate low oleate uptake by enterocytes (~25-30%) and less absorption (~37%) of triglycerides in the small intestine of ABCC10 knockout mice. Deletion of the Abcc10 gene also alters several lipid metabolism genes in the intestine, suggesting that ABCC10 regulates dietary fat absorption, which may contribute to diet-induced obesity in mice.
Collapse
|
3
|
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.
Collapse
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
| |
Collapse
|
4
|
Huang JS, Guo BB, Wang GH, Zeng LM, Hu YH, Wang T, Wang HY. DGAT1 inhibitors protect pancreatic β-cells from palmitic acid-induced apoptosis. Acta Pharmacol Sin 2021; 42:264-271. [PMID: 32737468 DOI: 10.1038/s41401-020-0482-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 07/14/2020] [Indexed: 12/24/2022] Open
Abstract
Previous studies demonstrated that prolonged exposure to elevated levels of free fatty acids (FFA), especially saturated fatty acids, could lead to pancreatic β-cell apoptosis, which plays an important role in the progression of type 2 diabetes (T2D). Diacylglycerol acyltransferase 1 (DGAT1), an enzyme that catalyzes the final step of triglyceride (TG) synthesis, has been reported as a novel target for the treatment of multiple metabolic diseases. In this study we evaluated the potential beneficial effects of DGAT1 inhibitors on pancreatic β-cells, and further verified their antidiabetic effects in db/db mice. We showed that DGAT1 inhibitors (4a and LCQ908) at the concentration of 1 μM significantly ameliorated palmitic acid (PA)-induced apoptosis in MIN6 pancreatic β-cells and primary cultured mouse islets; oral administration of a DGAT1 inhibitor (4a) (100 mg/kg) for 4 weeks significantly reduced the apoptosis of pancreatic islets in db/db mice. Meanwhile, 4a administration significantly decreased fasting blood glucose and TG levels, and improved glucose tolerance and insulin tolerance in db/db mice. Furthermore, we revealed that pretreatment with 4a (1 μM) significantly alleviated PA-induced intracellular lipid accumulation, endoplasmic reticulum (ER) stress, and proinflammatory responses in MIN6 cells, which might contribute to the protective effects of DGAT1 inhibitors on pancreatic β-cells. These findings provided a better understanding of the antidiabetic effects of DGAT1 inhibitors.
Collapse
|
5
|
Huang JS, Guo BB, Lin FF, Zeng LM, Wang T, Dang XY, Yang Y, Hu YH, Liu J, Wang HY. A novel low systemic diacylglycerol acyltransferase 1 inhibitor, Yhhu2407, improves lipid metabolism. Eur J Pharm Sci 2020; 158:105683. [PMID: 33347980 DOI: 10.1016/j.ejps.2020.105683] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Revised: 12/11/2020] [Accepted: 12/15/2020] [Indexed: 01/27/2023]
Abstract
Diacylglycerol acyltransferase 1 (DGAT1) plays a pivotal role in lipid metabolism by catalyzing the committed step in triglyceride (TG) synthesis and has been considered as a potential therapeutic target of multiple metabolic diseases, including dyslipidemia, obesity and type 2 diabetes. Here we report a novel DGAT1 inhibitor, Yhhu2407, which showed a stronger DGAT1 inhibitory activity (IC50 = 18.24 ± 4.72 nM) than LCQ908 (IC50 = 78.24 ± 8.16 nM) in an enzymatic assay and led to a significant reduction in plasma TG after an acute lipid challenge in mice. Pharmacokinetic studies illustrated that Yhhu2407 displayed a low systemic, liver- and intestine-targeted distribution pattern, which is consistent with the preferential tissue expression pattern of DGAT1 and therefore might help to maximize the beneficial pharmacological effects and prevent the occurrence of side effects. Cell-based investigations demonstrated that Yhhu2407 inhibited free fatty acid (FFA)-induced TG accumulation and apolipoprotein B (ApoB)-100 secretion in HepG2 cells. In vivo study also disclosed that Yhhu2407 exerted a beneficial effect on regulating plasma TG and lipoprotein levels in rats, and effectively ameliorated high-fat diet (HFD)-induced dyslipidemia in hamsters. In conclusion, we identified Yhhu2407 as a novel DGAT1 inhibitor with potent efficacy on improving lipid metabolism in rats and HFD-fed hamsters without causing obvious adverse effects.
Collapse
Affiliation(s)
- Jun-Shang Huang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Bin-Bin Guo
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Fei-Fei Lin
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Li-Min Zeng
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Ting Wang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Xiang-Yu Dang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Yang Yang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - You-Hong Hu
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Jia Liu
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
| | - He-Yao Wang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| |
Collapse
|
6
|
Vujić N, Korbelius M, Sachdev V, Rainer S, Zimmer A, Huber A, Radović B, Kratky D. Intestine-specific DGAT1 deficiency improves atherosclerosis in apolipoprotein E knockout mice by reducing systemic cholesterol burden. Atherosclerosis 2020; 310:26-36. [PMID: 32882484 PMCID: PMC7116265 DOI: 10.1016/j.atherosclerosis.2020.07.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 06/25/2020] [Accepted: 07/31/2020] [Indexed: 12/17/2022]
Abstract
Background and aims Acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) is the rate-limiting enzyme catalyzing the final step of triglyceride synthesis by esterifying a diglyceride with a fatty acid. We have previously shown that apolipoprotein E-knockout (ApoE−/−) mice lacking Dgat1 have reduced intestinal cholesterol absorption and potentiated macrophage cholesterol efflux, and consequently, exhibit attenuated atherogenesis. However, he-matopoietic Dgat1 deficiency lacked beneficial effects on atherosclerosis. Due to our recent results on the critical role of intestinal Dgat1 in murine cholesterol homeostasis, we delineated whether intestinal Dgat1 deficiency regulates atherogenesis in mice. Methods We generated intestine-specific Dgat1−/− mice on the ApoE−/− background (iDgat1−/−ApoE−/−) and determined cholesterol homeostasis and atherosclerosis development. Results When fed a Western-type diet, iDgat1−/−ApoE−/− mice exhibited a substantial decrease in fasting plasma cholesterol content in ApoB-containing lipoproteins. Although lipid absorption was delayed, iDgat1−/−ApoE−/− mice had reduced acute and fractional cholesterol absorption coupled with an elevated fecal caloric loss. In line, increased appearance of i.v. administered [3H]cholesterol in duodena and stool of iDgat1−/−ApoE−/− animals suggested potentiated cholesterol elimination. Atherosclerotic lesions were markedly smaller with beneficial alterations in plaque composition as evidenced by reduced macrophage infiltration and necrotic core size despite unaltered collagen content, indicating improved plaque stability. Conclusions Disruption of Dgat1 activity solely in the small intestine of ApoE−/− mice strongly decreased plasma cholesterol levels by abrogating the assimilation of dietary cholesterol, partly by reduced absorption and increased excretion. Consequently, the reduced cholesterol burden significantly attenuated atherogenesis and improved the lesion phenotype in iDgat1−/−ApoE−/− mice.
Collapse
Affiliation(s)
- Nemanja Vujić
- Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria; BioTechMed-Graz, Graz, Austria
| | - Melanie Korbelius
- Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria; BioTechMed-Graz, Graz, Austria
| | - Vinay Sachdev
- Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Silvia Rainer
- Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Andreas Zimmer
- Institute of Pharmaceutical Sciences, University of Graz, Graz, Austria; BioTechMed-Graz, Graz, Austria
| | - Anton Huber
- Institute of Chemistry, University of Graz, Graz, Austria
| | - Branislav Radović
- Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria; BioTechMed-Graz, Graz, Austria
| | - Dagmar Kratky
- Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria; BioTechMed-Graz, Graz, Austria.
| |
Collapse
|
7
|
UCP1-independent thermogenesis. Biochem J 2020; 477:709-725. [PMID: 32059055 DOI: 10.1042/bcj20190463] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 01/20/2020] [Accepted: 01/21/2020] [Indexed: 12/24/2022]
Abstract
Obesity results from energy imbalance, when energy intake exceeds energy expenditure. Brown adipose tissue (BAT) drives non-shivering thermogenesis which represents a powerful mechanism of enhancing the energy expenditure side of the energy balance equation. The best understood thermogenic system in BAT that evolved to protect the body from hypothermia is based on the uncoupling of protonmotive force from oxidative phosphorylation through the actions of uncoupling protein 1 (UCP1), a key regulator of cold-mediated thermogenesis. Similarly, energy expenditure is triggered in response to caloric excess, and animals with reduced thermogenic fat function can succumb to diet-induced obesity. Thus, it was surprising when inactivation of Ucp1 did not potentiate diet-induced obesity. In recent years, it has become clear that multiple thermogenic mechanisms exist, based on ATP sinks centered on creatine, lipid, or calcium cycling, along with Fatty acid-mediated UCP1-independent leak pathways driven by the ADP/ATP carrier (AAC). With a key difference between cold- and diet-induced thermogenesis being the dynamic changes in purine nucleotide (primarily ATP) levels, ATP-dependent thermogenic pathways may play a key role in diet-induced thermogenesis. Additionally, the ubiquitous expression of AAC may facilitate increased energy expenditure in many cell types, in the face of over feeding. Interest in UCP1-independent energy expenditure has begun to showcase the therapeutic potential that lies in refining our understanding of the diversity of biochemical pathways controlling thermogenic respiration.
Collapse
|
8
|
Regulation of intestinal lipid metabolism: current concepts and relevance to disease. Nat Rev Gastroenterol Hepatol 2020; 17:169-183. [PMID: 32015520 DOI: 10.1038/s41575-019-0250-7] [Citation(s) in RCA: 208] [Impact Index Per Article: 52.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/02/2019] [Indexed: 12/21/2022]
Abstract
Lipids entering the gastrointestinal tract include dietary lipids (triacylglycerols, cholesteryl esters and phospholipids) and endogenous lipids from bile (phospholipids and cholesterol) and from shed intestinal epithelial cells (enterocytes). Here, we comprehensively review the digestion, uptake and intracellular re-synthesis of intestinal lipids as well as their packaging into pre-chylomicrons in the endoplasmic reticulum, their modification in the Golgi apparatus and the exocytosis of the chylomicrons into the lamina propria and subsequently to lymph. We also discuss other fates of intestinal lipids, including intestinal HDL and VLDL secretion, cytosolic lipid droplets and fatty acid oxidation. In addition, we highlight the applicability of these findings to human disease and the development of therapeutics targeting lipid metabolism. Finally, we explore the emerging role of the gut microbiota in modulating intestinal lipid metabolism and outline key questions for future research.
Collapse
|
9
|
Johnson AA, Stolzing A. The role of lipid metabolism in aging, lifespan regulation, and age-related disease. Aging Cell 2019; 18:e13048. [PMID: 31560163 PMCID: PMC6826135 DOI: 10.1111/acel.13048] [Citation(s) in RCA: 215] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 08/11/2019] [Accepted: 09/04/2019] [Indexed: 12/18/2022] Open
Abstract
An emerging body of data suggests that lipid metabolism has an important role to play in the aging process. Indeed, a plethora of dietary, pharmacological, genetic, and surgical lipid‐related interventions extend lifespan in nematodes, fruit flies, mice, and rats. For example, the impairment of genes involved in ceramide and sphingolipid synthesis extends lifespan in both worms and flies. The overexpression of fatty acid amide hydrolase or lysosomal lipase prolongs life in Caenorhabditis elegans, while the overexpression of diacylglycerol lipase enhances longevity in both C. elegans and Drosophila melanogaster. The surgical removal of adipose tissue extends lifespan in rats, and increased expression of apolipoprotein D enhances survival in both flies and mice. Mouse lifespan can be additionally extended by the genetic deletion of diacylglycerol acyltransferase 1, treatment with the steroid 17‐α‐estradiol, or a ketogenic diet. Moreover, deletion of the phospholipase A2 receptor improves various healthspan parameters in a progeria mouse model. Genome‐wide association studies have found several lipid‐related variants to be associated with human aging. For example, the epsilon 2 and epsilon 4 alleles of apolipoprotein E are associated with extreme longevity and late‐onset neurodegenerative disease, respectively. In humans, blood triglyceride levels tend to increase, while blood lysophosphatidylcholine levels tend to decrease with age. Specific sphingolipid and phospholipid blood profiles have also been shown to change with age and are associated with exceptional human longevity. These data suggest that lipid‐related interventions may improve human healthspan and that blood lipids likely represent a rich source of human aging biomarkers.
Collapse
|
10
|
Chitraju C, Walther TC, Farese RV. The triglyceride synthesis enzymes DGAT1 and DGAT2 have distinct and overlapping functions in adipocytes. J Lipid Res 2019; 60:1112-1120. [PMID: 30936184 PMCID: PMC6547635 DOI: 10.1194/jlr.m093112] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 03/28/2019] [Indexed: 12/22/2022] Open
Abstract
Mammals store metabolic energy as triacylglycerols (TGs) in adipose tissue. TG synthesis is catalyzed by the evolutionarily unrelated acyl-CoA:diacylglycerol acyltransferase (DGAT) enzymes DGAT1 and DGAT2, which catalyze the same reaction and account for nearly all TG synthesis. The reasons for their convergent evolution to synthesize TGs remain unclear. Mice lacking DGAT1 are viable with reduced fat stores of TGs, whereas DGAT2 KO mice die postnatally just after birth with >90% reduction of TGs, suggesting that DGAT2 is the predominant enzyme for TG storage. To better understand the functional differences between the DGATs, we studied mice fed chow or high-fat diets lacking either enzyme in adipose tissue. Unexpectedly, mice lacking DGAT2 in adipocytes have normal TG storage and glucose metabolism on regular or high-fat diets, indicating DGAT2 is not essential for fat storage. In contrast, mice lacking DGAT1 in adipocytes have normal TG storage on a chow diet but moderately decreased body fat accompanied by glucose intolerance when challenged with a high-fat diet. The latter changes were associated with the activation of ER stress pathways. We conclude that DGAT1 and DGAT2 can largely compensate for each other for TG storage but that DGAT1 uniquely has an important role in protecting the ER from the lipotoxic effects of high-fat diets.
Collapse
Affiliation(s)
- Chandramohan Chitraju
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115.,Department of Cell Biology, Harvard Medical School, Boston, MA 02115
| | - Tobias C Walther
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115 .,Department of Cell Biology, Harvard Medical School, Boston, MA 02115.,Broad Institute of MIT and Harvard, Cambridge, MA 02142.,Howard Hughes Medical Institute, Boston, MA 02115
| | - Robert V Farese
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115 .,Department of Cell Biology, Harvard Medical School, Boston, MA 02115.,Broad Institute of MIT and Harvard, Cambridge, MA 02142
| |
Collapse
|
11
|
Nardi F, Franco OE, Fitchev P, Morales A, Vickman RE, Hayward SW, Crawford SE. DGAT1 Inhibitor Suppresses Prostate Tumor Growth and Migration by Regulating Intracellular Lipids and Non-Centrosomal MTOC Protein GM130. Sci Rep 2019; 9:3035. [PMID: 30816200 PMCID: PMC6395665 DOI: 10.1038/s41598-019-39537-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 12/31/2018] [Indexed: 11/10/2022] Open
Abstract
Acyl-CoA:diacylglycerol acyltransferase I (DGAT1) is a key enzyme in lipogenesis which is increased in metabolically active cells to meet nutrient requirements. DGAT1 has been recognized as an anti-obesity target; however, its role in the tumor microenvironment remains unclear. We postulated that, in prostate cancer (PCa) cells, augmented lipogenesis and growth are due to increased DGAT1 expression leading to microtubule-organizing center (MTOC) amplification. Thus, therapeutic targeting of DGAT1 potentially has tumor suppressive activity. We tested whether blocking DGAT1 in PCa cells altered MTOC and lipid signaling. Western blot and immunofluorescence were performed for MTOC and triglyceride mediators. Treatment with a DGAT1 inhibitor was evaluated. We found a stepwise increase in DGAT1 protein levels when comparing normal prostate epithelial cells to PCa cells, LNCaP and PC-3. Lipid droplets, MTOCs, and microtubule-regulating proteins were reduced in tumor cells treated with a DGAT1 inhibitor. Depletion of the non-centrosomal MTOC protein GM130 reduced PCa cell proliferation and migration. Inhibition of DGAT1 reduced tumor growth both in vitro and in vivo, and a negative feedback loop was discovered between DGAT1, PEDF, and GM130. These data identify DGAT1 as a promising new target for suppressing PCa growth by regulating GM130, MTOC number and disrupting microtubule integrity.
Collapse
Affiliation(s)
- Francesca Nardi
- Department of Surgery, NorthShore University Research Institute, Affiliate of University of Chicago Pritzker School of Medicine, Evanston, IL, 60201, United States
| | - Omar E Franco
- Department of Surgery, NorthShore University Research Institute, Affiliate of University of Chicago Pritzker School of Medicine, Evanston, IL, 60201, United States
| | - Philip Fitchev
- Department of Surgery, NorthShore University Research Institute, Affiliate of University of Chicago Pritzker School of Medicine, Evanston, IL, 60201, United States
| | - Alejandro Morales
- Department of Surgery, NorthShore University Research Institute, Affiliate of University of Chicago Pritzker School of Medicine, Evanston, IL, 60201, United States
| | - Renee E Vickman
- Department of Surgery, NorthShore University Research Institute, Affiliate of University of Chicago Pritzker School of Medicine, Evanston, IL, 60201, United States
| | - Simon W Hayward
- Department of Surgery, NorthShore University Research Institute, Affiliate of University of Chicago Pritzker School of Medicine, Evanston, IL, 60201, United States
| | - Susan E Crawford
- Department of Surgery, NorthShore University Research Institute, Affiliate of University of Chicago Pritzker School of Medicine, Evanston, IL, 60201, United States.
| |
Collapse
|
12
|
Yasuno K, Kumagai K, Iguchi T, Tsuchiya Y, Kai K, Mori K. DS-7250, a Diacylglycerol Acyltransferase 1 Inhibitor, Enhances Hepatic Steatosis in Zucker Fatty Rats via Upregulation of Fatty Acid Synthesis. Toxicol Pathol 2018; 46:302-311. [PMID: 29587622 DOI: 10.1177/0192623318765909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Diacylglycerol acyltransferase 1 (DGAT1) catalyzes the final step in triglyceride synthesis. Since Dgat1-/- mice fed a high-fat diet (HFD) are resistant to hepatic steatosis, DGAT1 inhibitors are expected to have antifatty liver effects. To evaluate the hepatic effects of DS-7250, a selective DGAT1 inhibitor, vehicle or 10 mg/kg of DS-7250 was administered orally to male Fisher 344 (F344) and Zucker fatty (ZF) rats fed a standard diet or HFD for 14 or 28 days. ZF rats showed slight hepatic steatosis regardless of feeding conditions. DS-7250 exacerbated hepatic steatosis in ZF rats fed an HFD compared with the vehicle control. Hepatic steatosis did not occur in F344 rats fed an HFD, in which systemic exposures of DS-7250 were comparable to those in ZF rats. There was a higher expression of genes involved in lipid uptake and fatty acid synthesis in ZF rats compared to F344 rats under HFD conditions. DS-7250 upregulated key genes involved in de novo lipogenesis, which causes hepatic steatosis independently of DGAT1, in ZF rats fed an HFD compared with the vehicle control. These data suggest that ZF rats were more susceptible to hepatic steatosis due to their genetic characteristics and DS-7250 exacerbated hepatic steatosis independently of DGAT1.
Collapse
Affiliation(s)
- Kyohei Yasuno
- 1 Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., Edogawa, Tokyo, Japan
| | - Kazuyoshi Kumagai
- 1 Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., Edogawa, Tokyo, Japan
| | - Takuma Iguchi
- 1 Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., Edogawa, Tokyo, Japan
| | - Yoshimi Tsuchiya
- 2 Quantitative Clinical Pharmacology and Translational Sciences, Daiichi Sankyo, Inc., Basking Ridge, New Jersey, USA
| | - Kiyonori Kai
- 1 Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., Edogawa, Tokyo, Japan
| | - Kazuhiko Mori
- 1 Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., Edogawa, Tokyo, Japan
| |
Collapse
|
13
|
Maciejewski BS, Manion TB, Steppan CM. Pharmacological inhibition of diacylglycerol acyltransferase-1 and insights into postprandial gut peptide secretion. World J Gastrointest Pathophysiol 2017; 8:161-175. [PMID: 29184702 PMCID: PMC5696614 DOI: 10.4291/wjgp.v8.i4.161] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Revised: 07/25/2017] [Accepted: 09/04/2017] [Indexed: 02/06/2023] Open
Abstract
AIM To examine the role that enzyme Acyl-CoA:diacylglycerol acyltransferase-1 (DGAT1) plays in postprandial gut peptide secretion and signaling.
METHODS The standard experimental paradigm utilized to evaluate the incretin response was a lipid challenge. Following a lipid challenge, plasma was collected via cardiac puncture at each time point from a cohort of 5-8 mice per group from baseline at time zero to 10 h. Incretin hormones [glucagon like peptide-1 (GLP-1), peptide tyrosine-tyrosine (PYY) and glucose dependent insulinotropic polypeptide (GIP)] were then quantitated. The impact of pharmacological inhibition of DGAT1 on the incretin effect was evaluated in WT mice. Additionally, a comparison of loss of DGAT1 function either by genetic ablation or pharmacological inhibition. To further elucidate the pathways and mechanisms involved in the incretin response to DGAT1 inhibition, other interventions [inhibitors of dipeptidyl peptidase-IV (sitagliptin), pancreatic lipase (Orlistat), GPR119 knockout mice] were evaluated.
RESULTS DGAT1 deficient mice and wildtype C57/BL6J mice were lipid challenged and levels of both active and total GLP-1 in the plasma were increased. This response was further augmented with DGAT1 inhibitor PF-04620110 treated wildtype mice. Furthermore, PF-04620110 was able to dose responsively increase GLP-1 and PYY, but blunt GIP at all doses of PF-04620110 during lipid challenge. Combination treatment of PF-04620110 and Sitagliptin in wildtype mice during a lipid challenge synergistically enhanced postprandial levels of active GLP-1. In contrast, in a combination study with Orlistat, the ability of PF-04620110 to elicit an enhanced incretin response was abrogated. To further explore this observation, GPR119 knockout mice were evaluated. In response to a lipid challenge, GPR119 knockout mice exhibited no increase in active or total GLP-1 and PYY. However, PF-04620110 was able to increase total GLP-1 and PYY in GPR119 knockout mice as compared to vehicle treated wildtype mice.
CONCLUSION Collectively, these data provide some insight into the mechanism by which inhibition of DGAT1 enhances intestinal hormone release.
Collapse
Affiliation(s)
- Benjamin S Maciejewski
- Pfizer Worldwide Research and Development, Cardiovascular and Metabolic Diseases Research Unit, Cambridge, MA 02139, United States
| | - Tara B Manion
- Pfizer Worldwide Research and Development, Cardiovascular and Metabolic Diseases Research Unit, Cambridge, MA 02139, United States
| | - Claire M Steppan
- Pfizer Worldwide Research and Development, Cardiovascular and Metabolic Diseases Research Unit, Cambridge, MA 02139, United States
- Pfizer Inc., Groton, CT 06340, United States
| |
Collapse
|
14
|
Costa DK, Huckestein BR, Edmunds LR, Petersen MC, Nasiri A, Butrico GM, Abulizi A, Harmon DB, Lu C, Mantell BS, Hartman DJ, Camporez JPG, O'Doherty RM, Cline GW, Shulman GI, Jurczak MJ. Reduced intestinal lipid absorption and body weight-independent improvements in insulin sensitivity in high-fat diet-fed Park2 knockout mice. Am J Physiol Endocrinol Metab 2016; 311:E105-16. [PMID: 27166280 PMCID: PMC4967148 DOI: 10.1152/ajpendo.00042.2016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 05/06/2016] [Indexed: 12/21/2022]
Abstract
Mitochondrial dysfunction is associated with many human diseases and results from mismatch of damage and repair over the life of the organelle. PARK2 is a ubiquitin E3 ligase that regulates mitophagy, a repair mechanism that selectively degrades damaged mitochondria. Deletion of PARK2 in multiple in vivo models results in susceptibility to stress-induced mitochondrial and cellular dysfunction. Surprisingly, Park2 knockout (KO) mice are protected from nutritional stress and do not develop obesity, hepatic steatosis or insulin resistance when fed a high-fat diet (HFD). However, these phenomena are casually related and the physiological basis for this phenotype is unknown. We therefore undertook a series of acute HFD studies to more completely understand the physiology of Park2 KO during nutritional stress. We find that intestinal lipid absorption is impaired in Park2 KO mice as evidenced by increased fecal lipids and reduced plasma triglycerides after intragastric fat challenge. Park2 KO mice developed hepatic steatosis in response to intravenous lipid infusion as well as during incubation of primary hepatocytes with fatty acids, suggesting that hepatic protection from nutritional stress was secondary to changes in energy balance due to altered intestinal triglyceride absorption. Park2 KO mice showed reduced adiposity after 1-wk HFD, as well as improved hepatic and peripheral insulin sensitivity. These studies suggest that changes in intestinal lipid absorption may play a primary role in protection from nutritional stress in Park2 KO mice by preventing HFD-induced weight gain and highlight the need for tissue-specific models to address the role of PARK2 during metabolic stress.
Collapse
Affiliation(s)
- Diana K Costa
- Department of Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Brydie R Huckestein
- Department of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Lia R Edmunds
- Department of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Max C Petersen
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
| | - Ali Nasiri
- Department of Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Gina M Butrico
- Department of Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Abudukadier Abulizi
- Department of Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Daniel B Harmon
- Department of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Canying Lu
- Department of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Benjamin S Mantell
- Department of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Douglas J Hartman
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | | | - Robert M O'Doherty
- Department of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; Center for Metabolic and Mitochondrial Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Gary W Cline
- Department of Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Gerald I Shulman
- Department of Medicine, Yale University School of Medicine, New Haven, Connecticut; Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut; The Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut; and
| | - Michael J Jurczak
- Department of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; Center for Metabolic and Mitochondrial Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| |
Collapse
|
15
|
Acyl-CoA:Diacylglycerol Acyltransferase 1 Expression Level in the Hematopoietic Compartment Impacts Inflammation in the Vascular Plaques of Atherosclerotic Mice. PLoS One 2016; 11:e0156364. [PMID: 27223895 PMCID: PMC4880185 DOI: 10.1371/journal.pone.0156364] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 05/12/2016] [Indexed: 01/09/2023] Open
Abstract
The final step of triacylglycerol synthesis is catalyzed by acyl-CoA:diacylglycerol acyltransferases (DGATs). We have previously shown that ApoE-/-Dgat1-/- mice are protected from developing atherosclerosis in association with reduced foam cell formation. However, the role of DGAT1, specifically in myeloid and other hematopoietic cell types, in determining this protective phenotype is unknown. To address this question, we reconstituted the bone marrow of irradiated Ldlr–/–mice with that from wild-type (WT→ Ldlr–/–) and Dgat1–/–(Dgat1–/–→ Ldlr–/–) donor mice. We noted that DGAT1 in the hematopoietic compartment exerts a sex-specific effect on systemic cholesterol homeostasis. However, both male and female Dgat1–/–→ Ldlr–/–mice had higher circulating neutrophil and lower lymphocyte counts than control mice, suggestive of a classical inflammatory phenotype. Moreover, specifically examining the aortae of these mice revealed that Dgat1–/–→ Ldlr–/–mice have atherosclerotic plaques with increased macrophage content. This increase was coupled to a reduced plaque collagen content, leading to a reduced collagen-to-macrophage ratio. Together, these findings point to a difference in the inflammatory contribution to plaque composition between Dgat1–/–→ Ldlr–/–and control mice. By contrast, DGAT1 deficiency did not affect the transcriptional responses of cultured macrophages to lipoprotein treatment in vitro, suggesting that the alterations seen in the plaques of Dgat1–/–→ Ldlr–/–mice in vivo do not reflect a cell intrinsic effect of DGAT1 in macrophages. We conclude that although DGAT1 in the hematopoietic compartment does not impact the overall lipid content of atherosclerotic plaques, it exerts reciprocal effects on inflammation and fibrosis, two processes that control plaque vulnerability.
Collapse
|
16
|
Lv Y, Xue L, Cai C, Liu QH, Shen J. Deficiency of myotubularin-related protein 14 influences body weight, metabolism, and inflammation in an age-dependent manner. Cell Biosci 2015; 5:69. [PMID: 26697164 PMCID: PMC4687302 DOI: 10.1186/s13578-015-0062-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 12/14/2015] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Myotubularin-related protein 14 (MTMR14) is a novel phosphoinositide phosphatase with roles in the maintenance of normal muscle performance, autophagy, and aging in mice. Our initial pilot study demonstrated that MTMR14 knock out (KO) mice gain weight earlier than their wild-type (WT) littermates, which suggests that this gene may also be involved in metabolism regulation. RESULTS The present study evaluated the role of MTMR14 in the development of aging-associated obesity. We found that aged MTMR14 KO mice fed a normal chow diet exhibited increased serum triglyceride, total cholesterol, and glucose levels compared to age-matched WT controls. Lipid accumulation was also increased in aged KO mice. Several inflammatory cytokines and adipokines were dramatically dysregulated in the metabolic tissues of aged MTMR14 KO mice compared to control mice. Circulating inflammatory cytokines were significantly elevated and plasma adipokine levels were abnormally regulated in aged MTMR14 KO mice. These data suggest that MTMR14 deficiency caused a late-onset inflammation and metabolic dysfunction. Further study demonstrated that this exacerbated metabolic dysfunction and inflammation may be regulated by the phosphoinositide 3 kinase/protein kinase B and extracellular signal-regulated protein kinase signaling pathways. CONCLUSIONS Our current research suggests that MTMR14 deletion induces overweight and adult obesity accompanied by chronic inflammation in an age-dependent manner.
Collapse
Affiliation(s)
- Yin Lv
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, 182 MinZu Ave, Wuhan, 430074 Hubei China
| | - Lu Xue
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, 182 MinZu Ave, Wuhan, 430074 Hubei China
| | - Congli Cai
- Wuhan Youzhiyou Biopharmaceutical Co., Ltd., Wuhan, 430075 China
| | - Qing-Hua Liu
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, 182 MinZu Ave, Wuhan, 430074 Hubei China
| | - Jinhua Shen
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, 182 MinZu Ave, Wuhan, 430074 Hubei China
| |
Collapse
|
17
|
Discovery and optimization of adamantane carboxylic acid derivatives as potent diacylglycerol acyltransferase 1 inhibitors for the potential treatment of obesity and diabetes. Eur J Med Chem 2015. [DOI: 10.1016/j.ejmech.2015.06.043] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
18
|
Liu L, Trent CM, Fang X, Son NH, Jiang H, Blaner WS, Hu Y, Yin YX, Farese RV, Homma S, Turnbull AV, Eriksson JW, Hu SL, Ginsberg HN, Huang LS, Goldberg IJ. Cardiomyocyte-specific loss of diacylglycerol acyltransferase 1 (DGAT1) reproduces the abnormalities in lipids found in severe heart failure. J Biol Chem 2014; 289:29881-91. [PMID: 25157099 DOI: 10.1074/jbc.m114.601864] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Diacylglycerol acyltransferase 1 (DGAT1) catalyzes the final step in triglyceride synthesis, the conversion of diacylglycerol (DAG) to triglyceride. Dgat1(-/-) mice exhibit a number of beneficial metabolic effects including reduced obesity and improved insulin sensitivity and no known cardiac dysfunction. In contrast, failing human hearts have severely reduced DGAT1 expression associated with accumulation of DAGs and ceramides. To test whether DGAT1 loss alone affects heart function, we created cardiomyocyte-specific DGAT1 knock-out (hDgat1(-/-)) mice. hDgat1(-/-) mouse hearts had 95% increased DAG and 85% increased ceramides compared with floxed controls. 50% of these mice died by 9 months of age. The heart failure marker brain natriuretic peptide increased 5-fold in hDgat1(-/-) hearts, and fractional shortening (FS) was reduced. This was associated with increased expression of peroxisome proliferator-activated receptor α and cluster of differentiation 36. We crossed hDgat1(-/-) mice with previously described enterocyte-specific Dgat1 knock-out mice (hiDgat1(-/-)). This corrected the early mortality, improved FS, and reduced cardiac ceramide and DAG content. Treatment of hDgat1(-/-) mice with the glucagon-like peptide 1 receptor agonist exenatide also improved FS and reduced heart DAG and ceramide content. Increased fatty acid uptake into hDgat1(-/-) hearts was normalized by exenatide. Reduced activation of protein kinase Cα (PKCα), which is increased by DAG and ceramides, paralleled the reductions in these lipids. Our mouse studies show that loss of DGAT1 reproduces the lipid abnormalities seen in severe human heart failure.
Collapse
Affiliation(s)
- Li Liu
- From the Divisions of Preventive Medicine and Nutrition and Institute of Systems Biomedicine, Peking University Health Science Center, 100083 Beijing, China
| | - Chad M Trent
- From the Divisions of Preventive Medicine and Nutrition and
| | - Xiang Fang
- From the Divisions of Preventive Medicine and Nutrition and Department of Geriatrics, Affiliated Provincial Hospital, Anhui Medical University, 230001 Hefei, China
| | - Ni-Huiping Son
- From the Divisions of Preventive Medicine and Nutrition and
| | - HongFeng Jiang
- From the Divisions of Preventive Medicine and Nutrition and
| | | | - Yunying Hu
- From the Divisions of Preventive Medicine and Nutrition and
| | - Yu-Xin Yin
- Institute of Systems Biomedicine, Peking University Health Science Center, 100083 Beijing, China
| | - Robert V Farese
- Gladstone Institute of Cardiovascular Disease and Departments of Medicine and Biochemistry and Biophysics, University of California, San Francisco, California 94158
| | - Shunichi Homma
- Cardiology, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | | | - Jan W Eriksson
- Astra-Zeneca Company, 431 50 Mölndal, Sweden, Department of Medical Sciences, Uppsala University, 751 05 Uppsala, Sweden, and
| | - Shi-Lian Hu
- Department of Geriatrics, Affiliated Provincial Hospital, Anhui Medical University, 230001 Hefei, China
| | | | - Li-Shin Huang
- From the Divisions of Preventive Medicine and Nutrition and
| | - Ira J Goldberg
- From the Divisions of Preventive Medicine and Nutrition and Cardiology, Columbia University College of Physicians and Surgeons, New York, New York 10032, Division of Endocrinology, Diabetes, and Metabolism, New York University Langone School of Medicine, New York, New York 10016
| |
Collapse
|
19
|
Zhou G, Zorn N, Ting P, Aslanian R, Lin M, Cook J, Lachowicz J, Lin A, Smith M, Hwa J, van Heek M, Walker S. Development of novel benzomorpholine class of diacylglycerol acyltransferase I inhibitors. ACS Med Chem Lett 2014; 5:544-9. [PMID: 24900877 DOI: 10.1021/ml400527n] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Accepted: 03/01/2014] [Indexed: 11/30/2022] Open
Abstract
Diacylglycerol acyltransferase 1 (DGAT1) presents itself as a potential therapeutic target for obesity and diabetes for its important role in triglyceride biosynthesis. Herein we report the rational design of a novel class of DGAT1 inhibitors featuring a benzomorpholine core (23n). SAR exploration yielded compounds with good potency and selectivity as well as reasonable physical and pharmacokinetic properties. This class of DGAT1 inhibitors was tested in rodent models to evaluate DGAT1 inhibition as a novel approach for the treatment of metabolic diseases. Compound 23n conferred weight loss and a reduction in liver triglycerides when dosed chronically in mice with diet-induced obesity and depleted serum triglycerides following a lipid challenge.
Collapse
Affiliation(s)
- Gang Zhou
- Discovery and Preclinical
Sciences, Merck Research Laboratories, 126 East Lincoln Avenue, Rahway, New Jersey 07065, United States
| | - Nicolas Zorn
- Discovery and Preclinical
Sciences, Merck Research Laboratories, 126 East Lincoln Avenue, Rahway, New Jersey 07065, United States
| | - Pauline Ting
- Discovery and Preclinical
Sciences, Merck Research Laboratories, 126 East Lincoln Avenue, Rahway, New Jersey 07065, United States
| | - Robert Aslanian
- Discovery and Preclinical
Sciences, Merck Research Laboratories, 126 East Lincoln Avenue, Rahway, New Jersey 07065, United States
| | - Mingxiang Lin
- Discovery and Preclinical
Sciences, Merck Research Laboratories, 126 East Lincoln Avenue, Rahway, New Jersey 07065, United States
| | - John Cook
- Discovery and Preclinical
Sciences, Merck Research Laboratories, 126 East Lincoln Avenue, Rahway, New Jersey 07065, United States
| | - Jean Lachowicz
- Discovery and Preclinical
Sciences, Merck Research Laboratories, 126 East Lincoln Avenue, Rahway, New Jersey 07065, United States
| | - Albert Lin
- Discovery and Preclinical
Sciences, Merck Research Laboratories, 126 East Lincoln Avenue, Rahway, New Jersey 07065, United States
| | - Michelle Smith
- Discovery and Preclinical
Sciences, Merck Research Laboratories, 126 East Lincoln Avenue, Rahway, New Jersey 07065, United States
| | - Joyce Hwa
- Discovery and Preclinical
Sciences, Merck Research Laboratories, 126 East Lincoln Avenue, Rahway, New Jersey 07065, United States
| | - Margaret van Heek
- Discovery and Preclinical
Sciences, Merck Research Laboratories, 126 East Lincoln Avenue, Rahway, New Jersey 07065, United States
| | - Scott Walker
- Discovery and Preclinical
Sciences, Merck Research Laboratories, 126 East Lincoln Avenue, Rahway, New Jersey 07065, United States
| |
Collapse
|
20
|
Nakamura MT, Yudell BE, Loor JJ. Regulation of energy metabolism by long-chain fatty acids. Prog Lipid Res 2013; 53:124-44. [PMID: 24362249 DOI: 10.1016/j.plipres.2013.12.001] [Citation(s) in RCA: 467] [Impact Index Per Article: 42.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Revised: 12/03/2013] [Accepted: 12/04/2013] [Indexed: 12/12/2022]
Abstract
In mammals, excess energy is stored primarily as triglycerides, which are mobilized when energy demands arise. This review mainly focuses on the role of long chain fatty acids (LCFAs) in regulating energy metabolism as ligands of peroxisome proliferator-activated receptors (PPARs). PPAR-alpha expressed primarily in liver is essential for metabolic adaptation to starvation by inducing genes for beta-oxidation and ketogenesis and by downregulating energy expenditure through fibroblast growth factor 21. PPAR-delta is highly expressed in skeletal muscle and induces genes for LCFA oxidation during fasting and endurance exercise. PPAR-delta also regulates glucose metabolism and mitochondrial biogenesis by inducing FOXO1 and PGC1-alpha. Genes targeted by PPAR-gamma in adipocytes suggest that PPAR-gamma senses incoming non-esterified LCFAs and induces the pathways to store LCFAs as triglycerides. Adiponectin, another important target of PPAR-gamma may act as a spacer between adipocytes to maintain their metabolic activity and insulin sensitivity. Another topic of this review is effects of skin LCFAs on energy metabolism. Specific LCFAs are required for the synthesis of skin lipids, which are essential for water barrier and thermal insulation functions of the skin. Disturbance of skin lipid metabolism often causes apparent resistance to developing obesity at the expense of normal skin function.
Collapse
Affiliation(s)
- Manabu T Nakamura
- Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, 905 South Goodwin Avenue, Urbana, IL 61801, USA.
| | - Barbara E Yudell
- Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, 905 South Goodwin Avenue, Urbana, IL 61801, USA
| | - Juan J Loor
- Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, 905 South Goodwin Avenue, Urbana, IL 61801, USA
| |
Collapse
|
21
|
Gajda AM, Zhou YX, Agellon LB, Fried SK, Kodukula S, Fortson W, Patel K, Storch J. Direct comparison of mice null for liver or intestinal fatty acid-binding proteins reveals highly divergent phenotypic responses to high fat feeding. J Biol Chem 2013; 288:30330-30344. [PMID: 23990461 DOI: 10.1074/jbc.m113.501676] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The enterocyte expresses two fatty acid-binding proteins (FABP), intestinal FABP (IFABP; FABP2) and liver FABP (LFABP; FABP1). LFABP is also expressed in liver. Despite ligand transport and binding differences, it has remained uncertain whether these intestinally coexpressed proteins, which both bind long chain fatty acids (FA), are functionally distinct. Here, we directly compared IFABP(-/-) and LFABP(-/-) mice fed high fat diets containing long chain saturated or unsaturated fatty acids, reasoning that providing an abundance of dietary lipid would reveal unique functional properties. The results showed that mucosal lipid metabolism was indeed differentially modified, with significant decreases in FA incorporation into triacylglycerol (TG) relative to phospholipid (PL) in IFABP(-/-) mice, whereas LFABP(-/-) mice had reduced monoacylglycerol incorporation in TG relative to PL, as well as reduced FA oxidation. Interestingly, striking differences were found in whole body energy homeostasis; LFABP(-/-) mice fed high fat diets became obese relative to WT, whereas IFABP(-/-) mice displayed an opposite, lean phenotype. Fuel utilization followed adiposity, with LFABP(-/-) mice preferentially utilizing lipids, and IFABP(-/-) mice preferentially metabolizing carbohydrate for energy production. Changes in body weight and fat may arise, in part, from altered food intake; mucosal levels of the endocannabinoids 2-arachidonoylglycerol and arachidonoylethanolamine were elevated in LFABP(-/-), perhaps contributing to increased energy intake. This direct comparison provides evidence that LFABP and IFABP have distinct roles in intestinal lipid metabolism; differential intracellular functions in intestine and in liver, for LFABP(-/-) mice, result in divergent downstream effects at the systemic level.
Collapse
Affiliation(s)
- Angela M Gajda
- From the Department of Nutritional Sciences and; the Rutgers Center for Lipid Research, Rutgers University, New Brunswick, New Jersey 08901
| | | | - Luis B Agellon
- the School of Dietetics and Human Nutrition, McGill University, Montréal, Québec H9X 3V9, Canada, and
| | - Susan K Fried
- the Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118
| | | | | | | | - Judith Storch
- From the Department of Nutritional Sciences and; the Rutgers Center for Lipid Research, Rutgers University, New Brunswick, New Jersey 08901,.
| |
Collapse
|
22
|
Maciejewski BS, LaPerle JL, Chen D, Ghosh A, Zavadoski WJ, McDonald TS, Manion TB, Mather D, Patterson TA, Hanna M, Watkins S, Gibbs EM, Calle RA, Steppan CM. Pharmacological inhibition to examine the role of DGAT1 in dietary lipid absorption in rodents and humans. Am J Physiol Gastrointest Liver Physiol 2013; 304:G958-69. [PMID: 23558010 DOI: 10.1152/ajpgi.00384.2012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Alterations in fat metabolism, in particular elevated plasma concentrations of free fatty acids and triglycerides (TG), have been implicated in the pathogenesis of Type 2 diabetes, obesity, and cardiovascular disease. Acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1), a member of the large family of membrane-bound O-acyltransferases, catalyzes the final step in triacylglycerol formation. In the intestine, DGAT1 is one of the acyltransferases responsible for the reesterficiation of dietary TG. Following a single dose of a selective pharmacological inhibitor of DGAT1, PF-04620110, a dose-dependent inhibition of TG and vitamin A absorption postprandially was demonstrated in rodents and human subjects. In C57/BL6J mice, acute DGAT1 inhibition alters the temporal and spatial pattern of dietary lipid absorption. To understand the impact of DGAT1 inhibition on enterocyte lipid metabolism, lipomic profiling was performed in rat intestine and plasma as well as human plasma. DGAT1 inhibition causes an enrichment of polyunsaturated fatty acids within the TG class of lipids. This pharmacological intervention gives us insight as to the role of DGAT1 in human dietary lipid absorption.
Collapse
Affiliation(s)
- Benjamin S Maciejewski
- Pfizer Worldwide Research and Development, Cardiovascular and Metabolic Diseases Research Unit, Cambridge, MA, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Diacylglycerol acyltransferase-1 (DGAT1) inhibition perturbs postprandial gut hormone release. PLoS One 2013; 8:e54480. [PMID: 23336002 PMCID: PMC3545956 DOI: 10.1371/journal.pone.0054480] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 12/12/2012] [Indexed: 12/27/2022] Open
Abstract
Diacylglycerol acyltransferase-1 (DGAT1) is a potential therapeutic target for treatment of obesity and related metabolic diseases. However, the degree of DGAT1 inhibition required for metabolic benefits is unclear. Here we show that partial DGAT1 deficiency in mice suppressed postprandial triglyceridemia, led to elevations in glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) only following meals with very high lipid content, and did not protect from diet-induced obesity. Maximal DGAT1 inhibition led to enhanced GLP-1 and PYY secretion following meals with physiologically relevant lipid content. Finally, combination of DGAT1 inhibition with dipeptidyl-peptidase-4 (DPP-4) inhibition led to further enhancements in active GLP-1 in mice and dogs. The current study suggests that targeting DGAT1 to enhance postprandial gut hormone secretion requires maximal inhibition, and suggests combination with DPP-4i as a potential strategy to develop DGAT1 inhibitors for treatment of metabolic diseases.
Collapse
|
24
|
Over-expression of monoacylglycerol lipase (MGL) in small intestine alters endocannabinoid levels and whole body energy balance, resulting in obesity. PLoS One 2012; 7:e43962. [PMID: 22937137 PMCID: PMC3429419 DOI: 10.1371/journal.pone.0043962] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Accepted: 07/30/2012] [Indexed: 12/27/2022] Open
Abstract
The function of small intestinal monoacylglycerol lipase (MGL) is unknown. Its expression in this tissue is surprising because one of the primary functions of the small intestine is to convert diet-derived MGs to triacylglycerol (TG), and not to degrade them. To elucidate the function of intestinal MGL, we generated transgenic mice that over-express MGL specifically in small intestine (iMGL mice). After only 3 weeks of high fat feeding, iMGL mice showed an obese phenotype; body weight gain and body fat mass were markedly higher in iMGL mice, along with increased hepatic and plasma TG levels compared to wild type littermates. The iMGL mice were hyperphagic and displayed reduced energy expenditure despite unchanged lean body mass, suggesting that the increased adiposity was due to both increased caloric intake and systemic effects resulting in a hypometabolic rate. The presence of the transgene resulted in lower levels of most MG species in intestinal mucosa, including the endocannabinoid 2-arachidonoyl glycerol (2-AG). The results therefore suggest a role for intestinal MGL, and intestinal 2-AG and perhaps other MG species, in whole body energy balance via regulation of food intake as well as metabolic rate.
Collapse
|
25
|
Sampath H, Ntambi JM. The role of stearoyl-CoA desaturase in obesity, insulin resistance, and inflammation. Ann N Y Acad Sci 2012; 1243:47-53. [PMID: 22211892 DOI: 10.1111/j.1749-6632.2011.06303.x] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Stearoyl-CoA desaturase 1 (SCD1) is an essential lipogenic enzyme that has been shown to play an intrinsic role in the development of obesity and related conditions, such as insulin resistance. Through the generation of various mouse models of SCD1 deficiency, we have come to understand that SCD1 plays a role, directly or indirectly, in diverse metabolic processes, including lipogenesis, fatty acid oxidation, insulin signaling, thermogenesis, and inflammation. This review will address recent advances in our understanding of this key regulator of cellular metabolic processes, including the role of SCD1 in maintaining skin barrier integrity and the role of skin SCD1 in the metabolic phenotype elicited by global SCD1 deficiency.
Collapse
Affiliation(s)
- Harini Sampath
- Center for Research on Occupational and Environmental Toxicology, Oregon Health & Science University, Portland, Oregon, USA
| | | |
Collapse
|
26
|
Yeh VSC, Beno DWA, Brodjian S, Brune ME, Cullen SC, Dayton BD, Dhaon MK, Falls HD, Gao J, Grihalde N, Hajduk P, Hansen TM, Judd AS, King AJ, Klix RC, Larson KJ, Lau YY, Marsh KC, Mittelstadt SW, Plata D, Rozema MJ, Segreti JA, Stoner EJ, Voorbach MJ, Wang X, Xin X, Zhao G, Collins CA, Cox BF, Reilly RM, Kym PR, Souers AJ. Identification and preliminary characterization of a potent, safe, and orally efficacious inhibitor of acyl-CoA:diacylglycerol acyltransferase 1. J Med Chem 2012; 55:1751-7. [PMID: 22263872 DOI: 10.1021/jm201524g] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A high-throughput screen against human DGAT-1 led to the identification of a core structure that was subsequently optimized to afford the potent, selective, and orally bioavailable compound 14. Oral administration at doses ≥0.03 mg/kg significantly reduced postprandial triglycerides in mice following an oral lipid challenge. Further assessment in both acute and chronic safety pharmacology and toxicology studies demonstrated a clean profile up to high plasma levels, thus culminating in the nomination of 14 as clinical candidate ABT-046.
Collapse
Affiliation(s)
- Vince S C Yeh
- Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064-6100, United States
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Streeper RS, Grueter CA, Salomonis N, Cases S, Levin MC, Koliwad SK, Zhou P, Hirschey MD, Verdin E, Farese RV. Deficiency of the lipid synthesis enzyme, DGAT1, extends longevity in mice. Aging (Albany NY) 2012; 4:13-27. [PMID: 22291164 PMCID: PMC3292902 DOI: 10.18632/aging.100424] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2012] [Accepted: 01/28/2012] [Indexed: 12/17/2022]
Abstract
Calorie restriction results in leanness, which is linked to metabolic conditions that favor longevity. We show here that deficiency of the triglyceride synthesis enzyme acyl CoA:diacylglycerol acyltransferase 1 (DGAT1), which promotes leanness, also extends longevity without limiting food intake. Female DGAT1-deficient mice were protected from age-related increases in body fat, tissue triglycerides, and inflammation in white adipose tissue. This protection was accompanied by increased mean and maximal life spans of ~25% and ~10%, respectively. Middle-agedDgat1-/- mice exhibited several features associated with longevity, including decreased levels of circulating insulin growth factor 1 (IGF1) and reduced fecundity. Thus, deletion of DGAT1 in mice provides a model of leanness and extended lifespan that is independent of calorie restriction.
Collapse
Affiliation(s)
- Ryan S. Streeper
- Gladstone Institute of Cardiovascular Disease, San Francisco, California, USA
- Cardiovascular Research Institute, San Francisco, California, USA
| | - Carrie A. Grueter
- Gladstone Institute of Cardiovascular Disease, San Francisco, California, USA
| | - Nathan Salomonis
- Gladstone Institute of Cardiovascular Disease, San Francisco, California, USA
| | - Sylvaine Cases
- Gladstone Institute of Cardiovascular Disease, San Francisco, California, USA
| | - Malin C. Levin
- Gladstone Institute of Cardiovascular Disease, San Francisco, California, USA
| | - Suneil K. Koliwad
- Gladstone Institute of Cardiovascular Disease, San Francisco, California, USA
- Cardiovascular Research Institute, San Francisco, California, USA
- Department of Medicine, University of California, San Francisco, California, USA
| | - Ping Zhou
- Gladstone Institute of Cardiovascular Disease, San Francisco, California, USA
| | - Matthew D. Hirschey
- Gladstone Institute of Virology and Immunology, San Francisco, California, USA
| | - Eric Verdin
- Gladstone Institute of Virology and Immunology, San Francisco, California, USA
- Department of Medicine, University of California, San Francisco, California, USA
| | - Robert V. Farese
- Gladstone Institute of Cardiovascular Disease, San Francisco, California, USA
- Cardiovascular Research Institute, San Francisco, California, USA
- Department of Medicine, University of California, San Francisco, California, USA
- Departments of Biochemistry and Biophysics, University of California, San Francisco, California, USA
| |
Collapse
|
28
|
Peeters A, Swinnen JV, Van Veldhoven PP, Baes M. Hepatosteatosis in peroxisome deficient liver despite increased β-oxidation capacity and impaired lipogenesis. Biochimie 2011; 93:1828-38. [PMID: 21756965 DOI: 10.1016/j.biochi.2011.06.034] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Accepted: 06/27/2011] [Indexed: 11/26/2022]
Abstract
Peroxisome deficiency in liver causes hepatosteatosis both in patients and in mice. Here, we studied the mechanisms that contribute to this lipid accumulation and to activation of peroxisome proliferator activated receptor α (PPARα) by using liver-specific Pex5(-/-) mice (L-Pex5(-/-) mice). Surprisingly, steatosis was accompanied both by increased mitochondrial β-oxidation capacity, confirming previous observations, and by impaired de novo lipid synthesis mediated by reduced expression of sterol regulatory element binding protein 1c and its targets. As a consequence, when challenged with a high fat diet, L-Pex5(-/-) mice were protected from adiposity. Hepatic fatty acid uptake was strongly increased whereas the expression of apolipoproteins and the lipoprotein assembly factor microsomal triglyceride transfer protein were markedly reduced resulting in reduced secretion of very low density lipoproteins. Most of these changes seemed to be orchestrated by the endogenous activation of PPARα, challenging the assumption that PPARα activation in hepatocytes requires fatty acid synthase dependent de novo fatty acid synthesis. Expression of cholesterol synthesizing enzymes and cholesterol levels were not affected in peroxisome deficient liver. In conclusion, increased fatty acid uptake driven by endogenous PPARα activation and reduced fatty acid secretion cause hepatosteatosis in peroxisome deficient livers.
Collapse
Affiliation(s)
- Annelies Peeters
- Laboratory of Cell Metabolism, Department of Pharmaceutical Sciences, K.U.Leuven, B-3000 Leuven, Belgium
| | | | | | | |
Collapse
|
29
|
Abstract
Exercise, together with a low-energy diet, is the first-line treatment for type 2 diabetes type 2 diabetes . Exercise improves insulin sensitivity insulin sensitivity by increasing the number or function of muscle mitochondria mitochondria and the capacity for aerobic metabolism, all of which are low in many insulin-resistant subjects. Cannabinoid 1-receptor antagonists and β-adrenoceptor agonists improve insulin sensitivity in humans and promote fat oxidation in rodents independently of reduced food intake. Current drugs for the treatment of diabetes are not, however, noted for their ability to increase fat oxidation, although the thiazolidinediones increase the capacity for fat oxidation in skeletal muscle, whilst paradoxically increasing weight gain.There are a number of targets for anti-diabetic drugs that may improve insulin sensitivity insulin sensitivity by increasing the capacity for fat oxidation. Their mechanisms of action are linked, notably through AMP-activated protein kinase, adiponectin, and the sympathetic nervous system. If ligands for these targets have obvious acute thermogenic activity, it is often because they increase sympathetic activity. This promotes fuel mobilisation, as well as fuel oxidation. When thermogenesis thermogenesis is not obvious, researchers often argue that it has occurred by using the inappropriate device of treating animals for days or weeks until there is weight (mainly fat) loss and then expressing energy expenditure energy expenditure relative to body weight. In reality, thermogenesis may have occurred, but it is too small to detect, and this device distracts us from really appreciating why insulin sensitivity has improved. This is that by increasing fatty acid oxidation fatty acid oxidation more than fatty acid supply, drugs lower the concentrations of fatty acid metabolites that cause insulin resistance. Insulin sensitivity improves long before any anti-obesity effect can be detected.
Collapse
Affiliation(s)
- Jonathan R S Arch
- Clore Laboratory, University of Buckingham, Buckingham, MK18 1EG, UK
| |
Collapse
|
30
|
Simon R, Britsch S, Bergemann A. Ablation of Sax2 gene expression prevents diet-induced obesity. FEBS J 2010; 278:371-82. [DOI: 10.1111/j.1742-4658.2010.07960.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
|
31
|
Matsuda D, Tomoda H. Triazolo compounds useful as diacylglycerol acyltransferase1 inhibitor - WO2009126624. Expert Opin Ther Pat 2010; 20:1097-102. [PMID: 20509774 DOI: 10.1517/13543776.2010.493877] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The accumulation of triacylglycerol in adipocytes causes obesity. Diacylglycerol acyltransferase (DGAT) catalyzes the final reaction of triacylglycerol synthesis. Two isozymes, DGAT1 and DGAT2, have been reported, and DGAT1 is considered a potential therapeutic target of inhibition for obesity control. Patent WO2009126624 proposes 69 new triazolopyridine compounds as DGAT1 inhibitors by Bristol-Myers Squibb. The inhibitory activity of these triazolopyridine compounds was assessed in an enzyme assay using microsomal fractions prepared from human DGAT1-expressing insect cells. Among them, four derivatives inhibited DGAT activity with IC(50) values of < 0.1 microM.
Collapse
|
32
|
Zhang XD, Yan JW, Yan GR, Sun XY, Ji J, Li YM, Hu YH, Wang HY. Pharmacological inhibition of diacylglycerol acyltransferase 1 reduces body weight gain, hyperlipidemia, and hepatic steatosis in db/db mice. Acta Pharmacol Sin 2010; 31:1470-7. [PMID: 21052084 DOI: 10.1038/aps.2010.104] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
AIM To test whether pharmacological inhibition of Diacylglycerol acyltransferase 1 (DGAT1) by a small-molecule inhibitor H128 can improve metabolism disorders in leptin receptor-deficient db/db mice. METHODS To investigate the effect of H128 on intestinal fat absorption,db/db mice were acutely given a bolus of corn oil by gavage. The mice were further orally administered H128 (3 and 10 mg/kg) for 5 weeks. Blood glucose, lipids, insulin, ALT, and AST as well as hepatic triglycerides were measured. The insulin tolerance test was performed to evaluate insulin sensitivity. The expression of genes involved in fatty acid oxidation was detected by RT-PCR. RESULTS Oral administration of H128 (10 mg/kg) acutely inhibited intestinal fat absorption following a lipid challenge in db/db mice. Chronic treatment with H128 significantly inhibited body weight gain, decreased food intake, and induced a pronounced reduction of serum triglycerides. In addition, H128 treatment markedly ameliorated hepatic steatosis, characterized by decreased liver weight, lipid droplets, and triglyceride content as well as serum ALT and AST levels. Furthermore, H128 treatment increased the expression of the CPT1 and PPARα genes in liver, suggesting that H128 enhanced fatty acid oxidation in db/db mice. However, neither blood glucose nor insulin tolerance was affected by H128 treatment throughout the 5-week experimental period. CONCLUSION DGAT1 may be an effective therapeutic target for the treatment of obesity, hyperlipidemia and hepatic steatosis.
Collapse
|
33
|
Eberwine J, Bartfai T. Single cell transcriptomics of hypothalamic warm sensitive neurons that control core body temperature and fever response Signaling asymmetry and an extension of chemical neuroanatomy. Pharmacol Ther 2010; 129:241-59. [PMID: 20970451 DOI: 10.1016/j.pharmthera.2010.09.010] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Accepted: 09/30/2010] [Indexed: 12/11/2022]
Abstract
We report on an 'unbiased' molecular characterization of individual, adult neurons, active in a central, anterior hypothalamic neuronal circuit, by establishing cDNA libraries from each individual, electrophysiologically identified warm sensitive neuron (WSN). The cDNA libraries were analyzed by Affymetrix microarray. The presence and frequency of cDNAs were confirmed and enhanced with Illumina sequencing of each single cell cDNA library. cDNAs encoding the GABA biosynthetic enzyme Gad1 and of adrenomedullin, galanin, prodynorphin, somatostatin, and tachykinin were found in the WSNs. The functional cellular and in vivo studies on dozens of the more than 500 neurotransmitters, hormone receptors and ion channels, whose cDNA was identified and sequence confirmed, suggest little or no discrepancy between the transcriptional and functional data in WSNs; whenever agonists were available for a receptor whose cDNA was identified, a functional response was found. Sequencing single neuron libraries permitted identification of rarely expressed receptors like the insulin receptor, adiponectin receptor 2 and of receptor heterodimers; information that is lost when pooling cells leads to dilution of signals and mixing signals. Despite the common electrophysiological phenotype and uniform Gad1 expression, WSN transcriptomes show heterogeneity, suggesting strong epigenetic influence on the transcriptome. Our study suggests that it is well-worth interrogating the cDNA libraries of single neurons by sequencing and chipping.
Collapse
Affiliation(s)
- James Eberwine
- Department of Pharmacology, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | | |
Collapse
|
34
|
Abstract
The absorption of dietary fat is of increasing concern given the rise of obesity not only in the United States but throughout the developed world. This review explores what happens to dietary fat within the enterocyte. Absorbed fatty acids and monoacylglycerols are required to be bound to intracellular proteins and/or to be rapidly converted to triacylglycerols to prevent cellular membrane disruption. The triacylglycerol produced at the level of the endoplasmic reticulum (ER) is either incorporated into prechylomicrons within the ER lumen or shunted to triacylglycerol storage pools. The prechylomicrons exit the ER in a specialized transport vesicle in the rate-limiting step in the intracellular transit of triacylglycerol across the enterocyte. The prechylomicrons are further processed in the Golgi and are transported to the basolateral membrane via a separate vesicular system for exocytosis into the intestinal lamina propria. Fatty acids and monoacylglycerols entering the enterocyte via the basolateral membrane are also incorporated into triacylglycerol, but the basolaterally entering lipid is much more likely to enter the triacylglycerol storage pool than the lipid entering via the apical membrane.
Collapse
Affiliation(s)
- Charles M Mansbach
- The University of Tennessee Health Science Center and the Veterans Administration Medical Center, Memphis, TN 38163, USA.
| | | |
Collapse
|
35
|
King AJ, Judd AS, Souers AJ. Inhibitors of diacylglycerol acyltransferase: a review of 2008 patents. Expert Opin Ther Pat 2010; 20:19-29. [PMID: 20021283 DOI: 10.1517/13543770903499305] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Postprandial hypertriglyceridemia has been identified as a major independent risk factor for future cardiovascular events. Therefore, inhibition of triglyceride synthesis has enormous therapeutic potential in the treatment of metabolic disorders. Diacylglycerol acyltransferase (DGAT) enzymes catalyze the final and only committed step in triglyceride biosynthesis and have thus been identified as potential therapeutic targets to combat human cardio-metabolic diseases. OBJECTIVE/METHOD Significant interest in DGAT-1 inhibitors has emerged in the last several years. To provide a perspective on the exciting features of this enzyme for targeting metabolic diseases, a summary of the biology and pharmacology surrounding the DGAT enzymes is presented. Following this is a discussion of the various chemotypes that have been disclosed within relevant patent applications published in 2008. Specifically, the similarities and differences of the chemical structures and the biological data that are provided to support the corresponding claims are presented. CONCLUSION Small molecule and biologic-based DGAT inhibitors have been successfully used for the preclinical validation of DGAT enzymes as targets for the treatment of metabolic diseases. Given the advanced stage in which some of the chemical matter resides, it is expected that DGAT inhibitors will enter the clinic in the coming years.
Collapse
Affiliation(s)
- Andrew J King
- Global Pharmaceutical Research & Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, IL 60064, USA
| | | | | |
Collapse
|
36
|
Tao H, Aakula S, Abumrad NN, Hajri T. Peroxisome proliferator-activated receptor-gamma regulates the expression and function of very-low-density lipoprotein receptor. Am J Physiol Endocrinol Metab 2010; 298:E68-79. [PMID: 19861583 PMCID: PMC2806108 DOI: 10.1152/ajpendo.00367.2009] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Very-low-density lipoprotein receptor (VLDLR) is a member of the low-density receptor family, highly expressed in adipose tissue, heart, and skeletal muscle. It binds apolipoprotein E-triglyceride-rich lipoproteins and plays a significant role in triglyceride metabolism. PPARgamma is a primary regulator of lipid metabolism in adipocytes and controls the expression of an array of genes involved in lipid trafficking in adipocytes. However, it is not known whether VLDLR is also under the control of PPARgamma. In this study, we investigated the role of PPARgamma in the regulation of VLDLR expression and function in vivo and in vitro. During the differentiation of 3T3-L1 preadipocytes, the levels of VLDLR protein and mRNA increased in parallel with the induction of PPARgamma expression and reached maximum in mature adipocytes. Treatment of differentiated adipocytes with PPARgamma agonist pioglitazone upregulated VLDLR expression in dose- and time-dependent manners. In contrast, specific inhibition of PPARgamma significantly downregulated the protein level of VLDLR. Induction of VLDLR is also demonstrated in vivo in adipose tissue of wild-type (WT) mice treated with pioglitazone. In addition, pioglitazone increased plasma triglyceride-rich lipoprotein clearance and increased epididymal fat mass in WT mice but failed to induce similar effects in vldlr(-/-) mice. These results were further corroborated by the finding that pioglitazone treatment enhanced adipogenesis and lipid deposition in preadipocytes of WT mice, while its effect in VLDLR-null preadipocytes was significantly blunted. These findings provide direct evidence that VLDLR expression is regulated by PPARgamma and contributes in lipid uptake and adipogenesis.
Collapse
Affiliation(s)
- Huan Tao
- Department of Surgical Sciences, Vanderbilt University School of Medicine, Nashville, TN 37212, USA
| | | | | | | |
Collapse
|
37
|
Shi Y, Cheng D. Beyond triglyceride synthesis: the dynamic functional roles of MGAT and DGAT enzymes in energy metabolism. Am J Physiol Endocrinol Metab 2009; 297:E10-8. [PMID: 19116371 PMCID: PMC3735925 DOI: 10.1152/ajpendo.90949.2008] [Citation(s) in RCA: 157] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Monoacyglycerol acyltransferases (MGATs) and diacylglycerol acyltransferases (DGATs) catalyze two consecutive steps of enzyme reactions in the synthesis of triacylglycerols (TAGs). The metabolic complexity of TAG synthesis is reflected by the presence of multiple isoforms of MGAT and DGAT enzymes that differ in catalytic properties, subcellular localization, tissue distribution, and physiological functions. MGAT and DGAT enzymes play fundamental roles in the metabolism of monoacylglycerol (MAG), diacylglycerol (DAG), and triacylglycerol (TAG) that are involved in many aspects of physiological functions, such as intestinal fat absorption, lipoprotein assembly, adipose tissue formation, signal transduction, satiety, and lactation. The recent progress in the phenotypic characterization of mice deficient in MGAT and DGAT enzymes and the development of chemical inhibitors have revealed important roles of these enzymes in the regulation of energy homeostasis and insulin sensitivity. Consequently, selective inhibition of MGAT or DGAT enzymes by synthetic compounds may provide novel treatment for obesity and its related metabolic complications.
Collapse
Affiliation(s)
- Yuguang Shi
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, 500 University Dr., Hershey, PA, USA.
| | | |
Collapse
|
38
|
King AJ, Segreti JA, Larson KJ, Souers AJ, Kym PR, Reilly RM, Zhao G, Mittelstadt SW, Cox BF. Diacylglycerol Acyltransferase 1 Inhibition Lowers Serum Triglycerides in the Zucker Fatty Rat and the Hyperlipidemic Hamster. J Pharmacol Exp Ther 2009; 330:526-31. [DOI: 10.1124/jpet.109.154047] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
|
39
|
Gelling RW, Yan W, Al-Noori S, Pardini A, Morton GJ, Ogimoto K, Schwartz MW, Dempsey PJ. Deficiency of TNFalpha converting enzyme (TACE/ADAM17) causes a lean, hypermetabolic phenotype in mice. Endocrinology 2008; 149:6053-64. [PMID: 18687778 PMCID: PMC2734496 DOI: 10.1210/en.2008-0775] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Energy homeostasis involves central nervous system integration of afferent inputs that coordinately regulate food intake and energy expenditure. Here, we report that adult homozygous TNFalpha converting enzyme (TACE)-deficient mice exhibit one of the most dramatic examples of hypermetabolism yet reported in a rodent system. Because this effect is not matched by increased food intake, mice lacking TACE exhibit a lean phenotype. In the hypothalamus of these mice, neurons in the arcuate nucleus exhibit intact responses to reduced fat mass and low circulating leptin levels, suggesting that defects in other components of the energy homeostasis system explain the phenotype of Tace(DeltaZn/DeltaZn) mice. Elevated levels of uncoupling protein-1 in brown adipose tissue from Tace(DeltaZn/DeltaZn) mice when compared with weight-matched controls suggest that deficient TACE activity is linked to increased sympathetic outflow. These findings collectively identify a novel and potentially important role for TACE in energy homeostasis.
Collapse
Affiliation(s)
- Richard W Gelling
- Division of Metabolism, Endocrinology, and Nutrition, Department of Medicine, University of Washington, Seattle, Washington 98195, USA
| | | | | | | | | | | | | | | |
Collapse
|
40
|
Yen CLE, Stone SJ, Koliwad S, Harris C, Farese RV. Thematic review series: glycerolipids. DGAT enzymes and triacylglycerol biosynthesis. J Lipid Res 2008; 49:2283-301. [PMID: 18757836 PMCID: PMC3837458 DOI: 10.1194/jlr.r800018-jlr200] [Citation(s) in RCA: 748] [Impact Index Per Article: 46.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2008] [Revised: 08/29/2008] [Indexed: 12/18/2022] Open
Abstract
Triacylglycerols (triglycerides) (TGs) are the major storage molecules of metabolic energy and FAs in most living organisms. Excessive accumulation of TGs, however, is associated with human diseases, such as obesity, diabetes mellitus, and steatohepatitis. The final and the only committed step in the biosynthesis of TGs is catalyzed by acyl-CoA:diacylglycerol acyltransferase (DGAT) enzymes. The genes encoding two DGAT enzymes, DGAT1 and DGAT2, were identified in the past decade, and the use of molecular tools, including mice deficient in either enzyme, has shed light on their functions. Although DGAT enzymes are involved in TG synthesis, they have distinct protein sequences and differ in their biochemical, cellular, and physiological functions. Both enzymes may be useful as therapeutic targets for diseases. Here we review the current knowledge of DGAT enzymes, focusing on new advances since the cloning of their genes, including possible roles in human health and diseases.
Collapse
Affiliation(s)
- Chi-Liang Eric Yen
- Department of Nutritional Sciences, University of Wisconsin, Madison, WI
53706
| | - Scot J. Stone
- Department of Biochemistry, University of Saskatchewan, Saskatoon,
Saskatchewan, Canada
| | - Suneil Koliwad
- Gladstone Institute of Cardiovascular Disease, University of California, San
Francisco, San Francisco, CA 94141
- Cardiovascular Research Institute, University of California, San
Francisco, San Francisco, CA 94141
- Department of Medicine, University of California, San Francisco,
San Francisco, CA 94141
| | - Charles Harris
- Gladstone Institute of Cardiovascular Disease, University of California, San
Francisco, San Francisco, CA 94141
- Cardiovascular Research Institute, University of California, San
Francisco, San Francisco, CA 94141
- Department of Medicine, University of California, San Francisco,
San Francisco, CA 94141
| | - Robert V. Farese
- Gladstone Institute of Cardiovascular Disease, University of California, San
Francisco, San Francisco, CA 94141
- Cardiovascular Research Institute, University of California, San
Francisco, San Francisco, CA 94141
- Department of Medicine, University of California, San Francisco,
San Francisco, CA 94141
- Department of Biochemistry and Biophysics, University of
California, San Francisco, San Francisco, CA 94141
| |
Collapse
|
41
|
Abstract
PURPOSE OF REVIEW One of the critical complications of obesity and diabetes is nonalcoholic fatty liver disease, a disorder of triacylglycerol accumulation in the liver that has potential to develop into end stage liver failure. In this review, the recent progress in understanding the role of hepatic triacylglycerol synthesis in the development of nonalcoholic fatty liver disease is discussed. RECENT FINDINGS It has become apparent that the development of hepatic steatosis is a complex, multifactorial process. Although the molecular pathways underlying its development have been described, there are no established therapies for nonalcoholic fatty liver disease. Recently, however, DGAT1 and DGAT2, the enzymes responsible for the final step in triacylglycerol synthesis, have been characterized as playing a vital role in hepatic triacylglycerol metabolism. Cellular and murine models in which diacylglycerol acyltransferase expression is altered suggest that these enzymes may play a role in the development hepatic steatosis, are feasible targets in the treatment of nonalcoholic fatty liver disease, but also function as lipotoxic buffers. SUMMARY Hepatic steatosis remains the watershed event in the progression of nonalcoholic fatty liver disease. The diacylglycerol acyltransferases are emerging as important mediators of hepatic triacylglycerol accumulation. Therefore, these enzymes are attractive targets in the development of therapies to prevent liver triacylglycerol accumulation and the consequences of nonalcoholic fatty liver disease.
Collapse
Affiliation(s)
- Aaron R Turkish
- Department of Pediatrics, Columbia University, New York, New York, USA.
| |
Collapse
|
42
|
Liu L, Zhang Y, Chen N, Shi X, Tsang B, Yu YH. Upregulation of myocellular DGAT1 augments triglyceride synthesis in skeletal muscle and protects against fat-induced insulin resistance. J Clin Invest 2007; 117:1679-89. [PMID: 17510710 PMCID: PMC1866250 DOI: 10.1172/jci30565] [Citation(s) in RCA: 255] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2006] [Accepted: 03/12/2007] [Indexed: 01/03/2023] Open
Abstract
Increased fat deposition in skeletal muscle is associated with insulin resistance. However, exercise increases both intramyocellular fat stores and insulin sensitivity, a phenomenon referred to as "the athlete's paradox". In this study, we provide evidence that augmenting triglyceride synthesis in skeletal muscle is intrinsically connected with increased insulin sensitivity. Exercise increased diacylglycerol (DAG) acyltransferase (DGAT) activity in skeletal muscle. Channeling fatty acid substrates into TG resulted in decreased DAG and ceramide levels. Transgenic overexpression of DGAT1 in mouse skeletal muscle replicated these findings and protected mice against high-fat diet-induced insulin resistance. Moreover, in isolated muscle, DGAT1 deficiency exacerbated insulin resistance caused by fatty acids, whereas DGAT1 overexpression mitigated the detrimental effect of fatty acids. The heightened insulin sensitivity in the transgenic mice was associated with attenuated fat-induced activation of DAG-responsive PKCs and the stress mediator JNK1. Consistent with these changes, serine phosphorylation of insulin receptor substrate 1 was reduced, and Akt activation and glucose 4 membrane translocation were increased. In conclusion, upregulation of DGAT1 in skeletal muscle is sufficient to recreate the athlete's paradox and illustrates a mechanism of exercise-induced enhancement of muscle insulin sensitivity. Thus, increasing muscle DGAT activity may offer a new approach to prevent and treat insulin resistance and type 2 diabetes mellitus.
Collapse
Affiliation(s)
- Li Liu
- Department of Medicine and
Department of Pediatrics, Columbia University, New York, New York, USA
| | - Yiying Zhang
- Department of Medicine and
Department of Pediatrics, Columbia University, New York, New York, USA
| | - Nancy Chen
- Department of Medicine and
Department of Pediatrics, Columbia University, New York, New York, USA
| | - Xiaojing Shi
- Department of Medicine and
Department of Pediatrics, Columbia University, New York, New York, USA
| | - Bonny Tsang
- Department of Medicine and
Department of Pediatrics, Columbia University, New York, New York, USA
| | - Yi-Hao Yu
- Department of Medicine and
Department of Pediatrics, Columbia University, New York, New York, USA
| |
Collapse
|
43
|
Wang SJY, Cornick C, O'Dowd J, Cawthorne MA, Arch JRS. Improved glucose tolerance in acyl CoA:diacylglycerol acyltransferase 1-null mice is dependent on diet. Lipids Health Dis 2007; 6:2. [PMID: 17239230 PMCID: PMC1794239 DOI: 10.1186/1476-511x-6-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2006] [Accepted: 01/19/2007] [Indexed: 12/22/2022] Open
Abstract
Background Mice that lack acyl CoA:diacylglycerol acyltransferase (Dgat1-/- mice) are reported to have a reduced body fat content and improved glucose tolerance and insulin sensitivity. Studies so far have focussed on male null mice fed a high fat diet and there are few data on heterozygotes. We compared male and female Dgat1-/-, Dgat1+/- and Dgat1+/+ C57Bl/6 mice fed on either standard chow or a high fat diet. Results Body fat content was lower in the Dgat1-/- than the Dgat1+/+ mice in both experiments; lean body mass was higher in male Dgat1-/- than Dgat1+/+ mice fed on the high fat diet. Energy intake and expenditure were higher in male Dgat1-/- than Dgat1+/+ mice; these differences were less marked or absent in females. The body fat content of female Dgat1+/- mice was intermediate between that of Dgat1-/- and Dgat1+/+ mice, whereas male Dgat1+/- mice were similar to or fatter than Dgat1+/+ mice. Glucose tolerance was improved and plasma insulin reduced in Dgat1-/- mice fed on the high fat diet, but not on the chow diet. Both male and female Dgat1+/- mice had similar glucose tolerance to Dgat1+/+ mice. Conclusion These results suggest that although ablation of DGAT1 improves glucose tolerance by preventing obesity in mice fed on a high fat diet, it does not improve glucose tolerance in mice fed on a low fat diet.
Collapse
Affiliation(s)
- Steven JY Wang
- Clore Laboratory, University of Buckingham, Buckingham MK18 1EG, UK
| | - Claire Cornick
- Clore Laboratory, University of Buckingham, Buckingham MK18 1EG, UK
| | | | | | - Jonathan RS Arch
- Clore Laboratory, University of Buckingham, Buckingham MK18 1EG, UK
| |
Collapse
|
44
|
Conti B, Sanchez-Alavez M, Winsky-Sommerer R, Morale MC, Lucero J, Brownell S, Fabre V, Huitron-Resendiz S, Henriksen S, Zorrilla EP, de Lecea L, Bartfai T. Transgenic mice with a reduced core body temperature have an increased life span. Science 2006; 314:825-8. [PMID: 17082459 DOI: 10.1126/science.1132191] [Citation(s) in RCA: 274] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Reduction of core body temperature has been proposed to contribute to the increased life span and the antiaging effects conferred by calorie restriction (CR). Validation of this hypothesis has been difficult in homeotherms, primarily due to a lack of experimental models. We report that transgenic mice engineered to overexpress the uncoupling protein 2 in hypocretin neurons (Hcrt-UCP2) have elevated hypothalamic temperature. The effects of local temperature elevation on the central thermostat resulted in a 0.3 degrees to 0.5 degrees C reduction of the core body temperature. Fed ad libitum, Hcrt-UCP2 transgenic mice had the same caloric intake as their wild-type littermates but had increased energy efficiency and a greater median life span (12% increase in males; 20% increase in females). Thus, modest, sustained reduction of core body temperature prolonged life span independent of altered diet or CR.
Collapse
Affiliation(s)
- Bruno Conti
- Harold L. Dorris Neurological Research Center, Scripps Research Institute, La Jolla, CA 92037, USA.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
45
|
Streeper RS, Koliwad SK, Villanueva CJ, Farese RV. Effects of DGAT1 deficiency on energy and glucose metabolism are independent of adiponectin. Am J Physiol Endocrinol Metab 2006; 291:E388-94. [PMID: 16595853 PMCID: PMC1552042 DOI: 10.1152/ajpendo.00621.2005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mice lacking acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1), an enzyme that catalyzes the terminal step in triacylglycerol synthesis, have enhanced insulin sensitivity and are protected from obesity, a result of increased energy expenditure. In these mice, factors derived from white adipose tissue (WAT) contribute to the systemic changes in metabolism. One such factor, adiponectin, increases fatty acid oxidation and enhances insulin sensitivity. To test the hypothesis that adiponectin is required for the altered energy and glucose metabolism in DGAT1-deficient mice, we generated adiponectin-deficient mice and introduced adiponectin deficiency into DGAT1-deficient mice by genetic crosses. Although adiponectin-deficient mice fed a high-fat diet were heavier, exhibited worse glucose tolerance, and had more hepatic triacylglycerol accumulation than wild-type controls, mice lacking both DGAT1 and adiponectin, like DGAT1-deficient mice, were protected from diet-induced obesity, glucose intolerance, and hepatic steatosis. These findings indicate that adiponectin is required for normal energy, glucose, and lipid metabolism but that the metabolic changes induced by DGAT1-deficient WAT are independent of adiponectin and are likely due to other WAT-derived factors. Our findings also suggest that the pharmacological inhibition of DGAT1 may be useful for treating human obesity and insulin resistance associated with low circulating adiponectin levels.
Collapse
Affiliation(s)
- Ryan S. Streeper
- Gladstone Institute of Cardiovascular Disease
- Cardiovascular Research Institute and
| | - Suneil K. Koliwad
- Gladstone Institute of Cardiovascular Disease
- Cardiovascular Research Institute and
- Departments of Medicine and
| | | | - Robert V. Farese
- Gladstone Institute of Cardiovascular Disease
- Cardiovascular Research Institute and
- Departments of Medicine and
- Biochemistry and Biophysics, and
- The Diabetes Center, University of California, San Francisco, California
- Address for reprint requests and other correspondence: Robert V. Farese, Jr., Gladstone Institute of Cardiovascular Disease, 1650 Owens St., San Francisco, CA 94158 (e-mail: )
| |
Collapse
|
46
|
Chen HC. Enhancing energy and glucose metabolism by disrupting triglyceride synthesis: Lessons from mice lacking DGAT1. Nutr Metab (Lond) 2006; 3:10. [PMID: 16448557 PMCID: PMC1382234 DOI: 10.1186/1743-7075-3-10] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Accepted: 01/31/2006] [Indexed: 01/09/2023] Open
Abstract
Although the ability to make triglycerides is essential for normal physiology, excess accumulation of triglycerides results in obesity and is associated with insulin resistance. Inhibition of triglyceride synthesis, therefore, may represent a feasible strategy for the treatment of obesity and type 2 diabetes. Acyl CoA:diacylglycerol acyltransferase 1 (DGAT1) is one of two DGAT enzymes that catalyze the final reaction in the known pathways of mammalian triglyceride synthesis. Mice lacking DGAT1 have increased energy expenditure and insulin sensitivity and are protected against diet-induced obesity and glucose intolerance. These metabolic effects of DGAT1 deficiency result in part from the altered secretion of adipocyte-derived factors. Studies of DGAT1-deficient mice have helped to provide insights into the mechanisms by which cellular lipid metabolism modulates systemic carbohydrate and insulin metabolism, and a better understanding of how DGAT1 deficiency enhances energy expenditure and insulin sensitivity may identify additional targets or strategies for the treatment of obesity and type 2 diabetes.
Collapse
Affiliation(s)
- Hubert C Chen
- Department of Medicine, University of California, San Francisco, CA 94103, USA.
| |
Collapse
|
47
|
Vergnes L, Beigneux AP, Davis R, Watkins SM, Young SG, Reue K. Agpat6 deficiency causes subdermal lipodystrophy and resistance to obesity. J Lipid Res 2006; 47:745-54. [PMID: 16436371 PMCID: PMC2901549 DOI: 10.1194/jlr.m500553-jlr200] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Triglyceride synthesis in most mammalian tissues involves the sequential addition of fatty acids to a glycerol backbone, with unique enzymes required to catalyze each acylation step. Acylation at the sn-2 position requires 1-acylglycerol-3-phosphate O-acyltransferase (AGPAT) activity. To date, seven Agpat genes have been identified based on activity and/or sequence similarity, but their physiological functions have not been well established. We have generated a mouse model deficient in AGPAT6, which is normally expressed at high levels in brown adipose tissue (BAT), white adipose tissue (WAT), and liver. Agpat6-deficient mice exhibit a 25% reduction in body weight and resistance to both diet-induced and genetically induced obesity. The reduced body weight is associated with increased energy expenditure, reduced triglyceride accumulation in BAT and WAT, reduced white adipocyte size, and lack of adipose tissue in the subdermal region. In addition, the fatty acid composition of triacylglycerol, diacylglycerol, and phospholipid is altered, with proportionally greater polyunsaturated fatty acids at the expense of monounsaturated fatty acids. Thus, Agpat6 plays a unique role in determining triglyceride content and composition in adipose tissue and liver that cannot be compensated by other members of the Agpat family.
Collapse
Affiliation(s)
- Laurent Vergnes
- Departments of Medicine and Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, and VA Greater Los Angeles Healthcare System, Los Angeles, CA 90073
| | - Anne P. Beigneux
- Division of Cardiology, Department of Internal Medicine, University of California, Los Angeles, CA 90095
| | - Ryan Davis
- Lipomics Technologies, West Sacramento, CA 95691
| | | | - Stephen G. Young
- Division of Cardiology, Department of Internal Medicine, University of California, Los Angeles, CA 90095
| | - Karen Reue
- Departments of Medicine and Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, and VA Greater Los Angeles Healthcare System, Los Angeles, CA 90073
- To whom correspondence should be addressed.
| |
Collapse
|
48
|
Good DJ. Using Obese Mouse Models in Research: Special Considerations for IACUC Members, Animal Care Technicians, and Researchers. Lab Anim (NY) 2005; 34:30-7. [PMID: 15685190 DOI: 10.1038/laban0205-30] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2004] [Accepted: 11/09/2004] [Indexed: 11/09/2022]
Abstract
The mouse is the animal most commonly used to study the underlying causes of and treatments for obesity. The author reviews many of the issues that should be considered by all involved in research with mice expressing this phenotype, and describes some procedures exclusive to obesity research.
Collapse
Affiliation(s)
- Deborah J Good
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, MA 01003, USA.
| |
Collapse
|
49
|
Vaccaro O, Masulli M, Cuomo V, Rivellese AA, Uusitupa M, Vessby B, Hermansen K, Tapsell L, Riccardi G. Comparative evaluation of simple indices of insulin resistance. Metabolism 2004; 53:1522-6. [PMID: 15562393 DOI: 10.1016/j.metabol.2004.05.017] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Various surrogate methods for the quantification of insulin sensitivity have been proposed. A comparative evaluation is lacking and is relevant for the standardization of investigative methods and comparability of results. The aims of the study were to perform a comparative validation of fasting insulin, homeostasis model assessment (HOMA), Quantitative Insulin Sensitivity Check Index (QUICKI), and revised-QUICKI (R-QUICKI) against minimal model derived estimates of insulin sensitivity (SI(MM)) in nondiabetic people and to carry out a comparative evaluation of the ability of these indices as means for the identification of individuals with the metabolic syndrome (MS) on a population basis. We used 2 data sets defined as "validation sample" and "prevalence sample". Validation sample: a total of 162 healthy men and women aged 30 to 65 years were studied by frequently sampled intravenous glucose tolerance test (FSIVGTT). SI(MM) was calculated with the Minmod program. Prevalence sample: a total of 2,731 nondiabetic men and women aged 35 to 65 years were studied. In both samples, anthropometry, blood pressure, fasting glucose, insulin, triglycerides, high-density lipoprotein (HDL) cholesterol, and free fatty acid (FFA) were measured. HOMA, QUICKI, and R-QUICKI were calculated. The MS was defined according to the Adult Treatment Panel III. Validation sample: insulin, HOMA, QUICKI, and R-QUICKI significantly correlated with SI(MM) (r = -0,53, -0.52, 0.41, 0.33; all P < .001). The finding was confirmed in obese (body mass index [BMI] > or =25 kg/m(2)), but in the normal weight, the correlation coefficient for QUICKI was significantly smaller than for the other indices. Receiver operator characteristic (ROC) curve analysis performed with SI(MM) below or above the lowest 25th percentile (ie, insulin resistance yes, no) as the outcome variable and each of the 4 indices as the test variable showed no significant differences in the areas under the curve. Prevalence sample: prevalence of the MS progressively increased across quartiles of insulin resistance as evaluated by any of the 4 indices, with no significant differences between them. The novel indices QUICKI and R-QUICKI do not perform better than HOMA and fasting insulin as surrogate measures of insulin resistance or means for the identification of people with MS in the general population.
Collapse
Affiliation(s)
- Olga Vaccaro
- Department of Clinical and Experimental Medicine, Federico II University of Naples, Italy
| | | | | | | | | | | | | | | | | |
Collapse
|
50
|
Chen HC, Farese RV. Inhibition of triglyceride synthesis as a treatment strategy for obesity: lessons from DGAT1-deficient mice. Arterioscler Thromb Vasc Biol 2004; 25:482-6. [PMID: 15569818 DOI: 10.1161/01.atv.0000151874.81059.ad] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Because the ability to make triglycerides is essential for the accumulation of adipose tissue, inhibition of triglyceride synthesis may ameliorate obesity and its related medical consequences. Acyl coenzyme A (CoA):diacylglycerol acyltransferase 1 (DGAT1) is 1 of 2 DGAT enzymes that catalyze the final reaction in the known pathways of mammalian triglyceride synthesis. Mice lacking DGAT1 are resistant to obesity and have increased sensitivity to insulin and leptin. DGAT1-deficient mice are also resistant to diet-induced hepatic steatosis. The effects of DGAT1 deficiency on energy and glucose metabolism result in part from the altered secretion of adipocyte-derived factors. Although complete DGAT1 deficiency causes alopecia and impairs development of the mammary gland, these abnormalities are not observed in mice with partial DGAT1 deficiency. These findings suggest that pharmacological inhibition of DGAT1 may be a feasible therapeutic strategy for human obesity and type 2 diabetes.
Collapse
Affiliation(s)
- Hubert C Chen
- Department of Medical Sciences, Amgen Inc, Thousand Oaks, USA
| | | |
Collapse
|