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Oguro A, Kaga Y, Sato H, Fujiyama T, Fujimoto S, Nagai S, Matsuyama M, Miyara M, Ishihara Y, Yamazaki T, Imaoka S, Kotake Y. Mice deficient in the phosphatase activity of sEH show decreased levels of the endocannabinoid 2-AG in the olfactory bulb and depressive-like behavior. FEBS Lett 2024. [PMID: 39034140 DOI: 10.1002/1873-3468.14984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 06/03/2024] [Accepted: 06/19/2024] [Indexed: 07/23/2024]
Abstract
Soluble epoxide hydrolase (sEH) is a bifunctional enzyme that has epoxide hydrolase activity and phosphatase activity. Our earlier study revealed that lysophosphatidic acids are a substrate of the phosphatase activity of sEH in vitro, but its physiological function remained unknown. Herein, we used the CRISPR/Cas9 system and i-GONAD method to generate mice that are deficient in sEH phosphatase activity. In the mouse brain, sEH was highly expressed in the olfactory bulb. Deletion of the sEH phosphatase activity resulted in decreased levels of the endocannabinoid 2-arachidonoyl glycerol (2-AG), which is a dephosphorylated form of 2-arachidonoyl-lysophosphatidic acid in the olfactory bulb. The sEH-deficient mice showed depressive-like behavior. These results indicate that sEH can regulate the production of 2-AG and brain function in vivo.
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Affiliation(s)
- Ami Oguro
- Graduate School of Biomedical and Health Sciences, Hiroshima University, Japan
| | - Yurino Kaga
- Graduate School of Biomedical and Health Sciences, Hiroshima University, Japan
| | - Hideaki Sato
- Graduate School of Biomedical and Health Sciences, Hiroshima University, Japan
| | - Taichi Fujiyama
- Graduate School of Biomedical and Health Sciences, Hiroshima University, Japan
| | - Shinji Fujimoto
- Graduate School of Biomedical and Health Sciences, Hiroshima University, Japan
| | - Saki Nagai
- Graduate School of Biomedical and Health Sciences, Hiroshima University, Japan
| | - Makoto Matsuyama
- Division of Molecular Genetics, Shigei Medical Research Institute, Okayama, Japan
| | - Masatsugu Miyara
- Graduate School of Biomedical and Health Sciences, Hiroshima University, Japan
| | - Yasuhiro Ishihara
- Graduate School of Integrated Sciences for Life, Hiroshima University, Japan
| | - Takeshi Yamazaki
- Graduate School of Integrated Sciences for Life, Hiroshima University, Japan
| | - Susumu Imaoka
- Department of Biomedical Sciences, School of Biological and Environmental Sciences, Kwansei Gakuin University, Hyogo, Japan
| | - Yaichiro Kotake
- Graduate School of Biomedical and Health Sciences, Hiroshima University, Japan
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2
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Dalen KT, Li Y. Regulation of lipid droplets and cholesterol metabolism in adrenal cortical cells. VITAMINS AND HORMONES 2023; 124:79-136. [PMID: 38408810 DOI: 10.1016/bs.vh.2023.06.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
The adrenal gland is composed of two distinctly different endocrine moieties. The interior medulla consists of neuroendocrine chromaffin cells that secrete catecholamines like adrenaline and noradrenaline, while the exterior cortex consists of steroidogenic cortical cells that produce steroid hormones, such as mineralocorticoids (aldosterone), glucocorticoids (cortisone and cortisol) and androgens. Synthesis of steroid hormones in cortical cells requires substantial amounts of cholesterol, which is the common precursor for steroidogenesis. Cortical cells may acquire cholesterol from de novo synthesis and uptake from circulating low- and high-density lipoprotein particles (LDL and HDL). As cholesterol is part of the plasma membrane in all mammalian cells and an important regulator of membrane fluidity, cellular levels of free cholesterol are tightly regulated. To ensure a robust supply of cholesterol for steroidogenesis and to avoid cholesterol toxicity, cortical cells store large amounts of cholesterol as cholesteryl esters in intracellular lipid droplets. Cortical steroidogenesis relies on both mobilization of cholesterol from lipid droplets and constant uptake of circulating cholesterol to replenish lipid droplet stores. This chapter will describe mechanisms involved in cholesterol uptake, cholesteryl ester synthesis, lipid droplet formation, hydrolysis of stored cholesteryl esters, as well as their impact on steroidogenesis. Additionally, animal models and human diseases characterized by altered cortical cholesteryl ester storage, with or without abnormal steroidogenesis, will be discussed.
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Affiliation(s)
- Knut Tomas Dalen
- Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Norway; The Norwegian Transgenic Center, Institute of Basic Medical Sciences, University of Oslo, Norway.
| | - Yuchuan Li
- Department of Hepato-Pancreato-Biliary Surgery, Institute of Clinical Medicine, University of Oslo, Norway
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Peroxisome Proliferator-Activated Receptor α Has a Protective Effect on Fatty Liver Caused by Excessive Sucrose Intake. Biomedicines 2022; 10:biomedicines10092199. [PMID: 36140300 PMCID: PMC9496554 DOI: 10.3390/biomedicines10092199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 08/31/2022] [Accepted: 09/01/2022] [Indexed: 11/16/2022] Open
Abstract
Sterol regulatory element binding protein (SREBP)-1c is a transcription factor that regulates lipid synthesis from glucose in the liver. It is activated by sucrose, which activates the fatty acid synthesis pathway. On the other hand, peroxisome proliferator-activated receptor (PPAR) α regulates the transcription of several genes encoding enzymes involved in fatty acid β-oxidation in the liver. To evaluate the beneficial effects of PPARα on fatty liver caused by excessive sucrose intake, we investigated the molecular mechanisms related to the development of fatty liver in PPARα-deficient mice that were fed a high-sucrose diet (Suc). The SREBP-1c target gene expression was increased by sucrose intake, leading to the development of fatty liver. Furthermore, PPARα−/− mice developed severe fatty liver. Male and female PPARα−/− mice fed Suc showed 3.7- and 3.1-fold higher liver fat content than Suc-fed male and female wild-type mice, respectively. Thus, PPARα may work to prevent the development of fatty liver caused by excessive sucrose intake. Liver TG accumulation differed between male and female PPARα−/− mice. A possible explanation is that male mice show the increased expression of Pparγ, which usually contributes to triglyceride synthesis in the liver, to compensate for Pparα deficiency. In contrast, female wild-type mice inherently have low Pparα levels. Thus, Pparα deficiency has less pronounced effects in female mice. A diet that activates PPARα may be effective for preventing the development of fatty liver due to excessive sucrose intake.
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Busato S, Ford HR, Abdelatty AM, Estill CT, Bionaz M. Peroxisome Proliferator-Activated Receptor Activation in Precision-Cut Bovine Liver Slices Reveals Novel Putative PPAR Targets in Periparturient Dairy Cows. Front Vet Sci 2022; 9:931264. [PMID: 35903133 PMCID: PMC9315222 DOI: 10.3389/fvets.2022.931264] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 06/06/2022] [Indexed: 12/24/2022] Open
Abstract
Metabolic challenges experienced by dairy cows during the transition between pregnancy and lactation (also known as peripartum), are of considerable interest from a nutrigenomic perspective. The mobilization of large amounts of non-esterified fatty acids (NEFA) leads to an increase in NEFA uptake in the liver, the excess of which can cause hepatic accumulation of lipids and ultimately fatty liver. Interestingly, peripartum NEFA activate the Peroxisome Proliferator-activated Receptor (PPAR), a transcriptional regulator with known nutrigenomic properties. The study of PPAR activation in the liver of periparturient dairy cows is thus crucial; however, current in vitro models of the bovine liver are inadequate, and the isolation of primary hepatocytes is time consuming, resource intensive, and prone to errors, with the resulting cells losing characteristic phenotypical traits within hours. The objective of the current study was to evaluate the use of precision-cut liver slices (PCLS) from liver biopsies as a model for PPAR activation in periparturient dairy cows. Three primiparous Jersey cows were enrolled in the experiment, and PCLS from each were prepared prepartum (−8.0 ± 3.6 DIM) and postpartum (+7.7± 1.2 DIM) and treated independently with a variety of PPAR agonists and antagonists: the PPARα agonist WY-14643 and antagonist GW-6471; the PPARδ agonist GW-50156 and antagonist GSK-3787; and the PPARγ agonist rosiglitazone and antagonist GW-9662. Gene expression was assayed through RT-qPCR and RNAseq, and intracellular triacylglycerol (TAG) concentration was measured. PCLS obtained from postpartum cows and treated with a PPARγ agonist displayed upregulation of ACADVL and LIPC while those treated with PPARδ agonist had increased expression of LIPC, PPARD, and PDK4. In PCLS from prepartum cows, transcription of LIPC was increased by all PPAR agonists and NEFA. TAG concentration tended to be larger in tissue slices treated with PPARδ agonist compared to CTR. Use of PPAR isotype-specific antagonists in PCLS cultivated in autologous blood serum failed to decrease expression of PPAR targets, except for PDK4, which was confirmed to be a PPARδ target. Transcriptome sequencing revealed considerable differences in response to PPAR agonists at a false discovery rate-adjusted p-value of 0.2, with the most notable effects exerted by the PPARδ and PPARγ agonists. Differentially expressed genes were mainly related to pathways involved with lipid metabolism and the immune response. Among differentially expressed genes, a subset of 91 genes were identified as novel putative PPAR targets in the bovine liver, by cross-referencing our results with a publicly available dataset of predicted PPAR target genes, and supplementing our findings with prior literature. Our results provide important insights on the use of PCLS as a model for assaying PPAR activation in the periparturient dairy cow.
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Affiliation(s)
- Sebastiano Busato
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, OR, United States
| | - Hunter R. Ford
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, OR, United States
| | - Alzahraa M. Abdelatty
- Department of Nutrition and Clinical Nutrition, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt
| | - Charles T. Estill
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, OR, United States
- College of Veterinary Medicine, Oregon State University, Corvallis, OR, United States
| | - Massimo Bionaz
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, OR, United States
- *Correspondence: Massimo Bionaz
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Lu H, Lei X, Winkler R, John S, Kumar D, Li W, Alnouti Y. Crosstalk of hepatocyte nuclear factor 4a and glucocorticoid receptor in the regulation of lipid metabolism in mice fed a high-fat-high-sugar diet. Lipids Health Dis 2022; 21:46. [PMID: 35614477 PMCID: PMC9134643 DOI: 10.1186/s12944-022-01654-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 05/06/2022] [Indexed: 12/15/2022] Open
Abstract
Background Hepatocyte nuclear factor 4α (HNF4α) and glucocorticoid receptor (GR), master regulators of liver metabolism, are down-regulated in fatty liver diseases. The present study aimed to elucidate the role of down-regulation of HNF4α and GR in fatty liver and hyperlipidemia. Methods Adult mice with liver-specific heterozygote (HET) and knockout (KO) of HNF4α or GR were fed a high-fat-high-sugar diet (HFHS) for 15 days. Alterations in hepatic and circulating lipids were determined with analytical kits, and changes in hepatic mRNA and protein expression in these mice were quantified by real-time PCR and Western blotting. Serum and hepatic levels of bile acids were quantified by LC-MS/MS. The roles of HNF4α and GR in regulating hepatic gene expression were determined using luciferase reporter assays. Results Compared to HFHS-fed wildtype mice, HNF4α HET mice had down-regulation of lipid catabolic genes, induction of lipogenic genes, and increased hepatic and blood levels of lipids, whereas HNF4α KO mice had fatty liver but mild hypolipidemia, down-regulation of lipid-efflux genes, and induction of genes for uptake, synthesis, and storage of lipids. Serum levels of chenodeoxycholic acid and deoxycholic acid tended to be decreased in the HNF4α HET mice but dramatically increased in the HNF4α KO mice, which was associated with marked down-regulation of cytochrome P450 7a1, the rate-limiting enzyme for bile acid synthesis. Hepatic mRNA and protein expression of sterol-regulatory-element-binding protein-1 (SREBP-1), a master lipogenic regulator, was induced in HFHS-fed HNF4α HET mice. In reporter assays, HNF4α cooperated with the corepressor small heterodimer partner to potently inhibit the transactivation of mouse and human SREBP-1C promoter by liver X receptor. Hepatic nuclear GR proteins tended to be decreased in the HNF4α KO mice. HFHS-fed mice with liver-specific KO of GR had increased hepatic lipids and induction of SREBP-1C and PPARγ, which was associated with a marked decrease in hepatic levels of HNF4α proteins in these mice. In reporter assays, GR and HNF4α synergistically/additively induced lipid catabolic genes. Conclusions induction of lipid catabolic genes and suppression of lipogenic genes by HNF4α and GR may mediate the early resistance to HFHS-induced fatty liver and hyperlipidemia. Graphical abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s12944-022-01654-6.
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Affiliation(s)
- Hong Lu
- Department of Pharmacology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA.
| | - Xiaohong Lei
- Department of Pharmacology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Rebecca Winkler
- Department of Pharmacology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Savio John
- Department of Medicine, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Devendra Kumar
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Wenkuan Li
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Yazen Alnouti
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, NE, 68198, USA
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Vecera R, Poruba M, Hüttl M, Malinska H, Oliyarnyk O, Markova I, Racova Z, Soukop J, Kazdova L. Beneficial Effect of Fenofibrate and Silymarin on Hepatic Steatosis and Gene Expression of Lipogenic and Cytochrome P450 Enzymes in Non-Obese Hereditary Hypertriglyceridemic Rats. Curr Issues Mol Biol 2022; 44:1889-1900. [PMID: 35678658 PMCID: PMC9164080 DOI: 10.3390/cimb44050129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 04/14/2022] [Accepted: 04/22/2022] [Indexed: 11/16/2022] Open
Abstract
The efficacy of fenofibrate in the treatment of hepatic steatosis has not been clearly demonstrated. In this study, we investigated the effects of fenofibrate and silymarin, administered as monotherapy and in combination to existing hepatic steatosis in a unique strain of hereditary hypertriglyceridemic rats (HHTg), a non-obese model of metabolic syndrome. HHTg rats were fed a standard diet without or with fenofibrate (100 mg/kg b.wt./day) or with silymarin (1%) or with a combination of fenofibrate with silymarin for four weeks. Fenofibrate alone and in combination with silymarin decreased serum and liver triglycerides and cholesterol and increased HDL cholesterol. These effects were associated with the decreased gene expression of enzymes involved in lipid synthesis and transport, while enzymes of lipid conversion were upregulated. The combination treatment had a beneficial effect on the gene expression of hepatic cytochrome P450 (CYP) enzymes. The expression of the CYP2E1 enzyme, which is source of hepatic reactive oxygen species, was reduced. In addition, fenofibrate-induced increased CYP4A1 expression was decreased, suggesting a reduction in the pro-inflammatory effects of fenofibrate. These results show high efficacy and mechanisms of action of the combination of fenofibrate with silymarin in treating hepatic steatosis and indicate the possibility of protection against disorders in which oxidative stress and inflammation are involved.
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Affiliation(s)
- Rostislav Vecera
- Department of Pharmacology, Faculty of Medicine and Dentistry, Palacky University, 77515 Olomouc, Czech Republic; (R.V.); (Z.R.); (J.S.)
| | - Martin Poruba
- Department of Pharmacology, Faculty of Medicine and Dentistry, Palacky University, 77515 Olomouc, Czech Republic; (R.V.); (Z.R.); (J.S.)
- Correspondence: ; Tel.: +420-585-632-556
| | - Martina Hüttl
- Centre for Experimental Medicine, Institute for Clinical and Experimental Medicine, 14021 Prague, Czech Republic; (M.H.); (H.M.); (O.O.); (I.M.); (L.K.)
| | - Hana Malinska
- Centre for Experimental Medicine, Institute for Clinical and Experimental Medicine, 14021 Prague, Czech Republic; (M.H.); (H.M.); (O.O.); (I.M.); (L.K.)
| | - Olena Oliyarnyk
- Centre for Experimental Medicine, Institute for Clinical and Experimental Medicine, 14021 Prague, Czech Republic; (M.H.); (H.M.); (O.O.); (I.M.); (L.K.)
| | - Irena Markova
- Centre for Experimental Medicine, Institute for Clinical and Experimental Medicine, 14021 Prague, Czech Republic; (M.H.); (H.M.); (O.O.); (I.M.); (L.K.)
| | - Zuzana Racova
- Department of Pharmacology, Faculty of Medicine and Dentistry, Palacky University, 77515 Olomouc, Czech Republic; (R.V.); (Z.R.); (J.S.)
| | - Jan Soukop
- Department of Pharmacology, Faculty of Medicine and Dentistry, Palacky University, 77515 Olomouc, Czech Republic; (R.V.); (Z.R.); (J.S.)
| | - Ludmila Kazdova
- Centre for Experimental Medicine, Institute for Clinical and Experimental Medicine, 14021 Prague, Czech Republic; (M.H.); (H.M.); (O.O.); (I.M.); (L.K.)
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Erol SA, Anuk AT, Tanaçan A, Semiz H, Keskin HL, Neşelioğlu S, Erel Ö, Moraloğlu Tekin Ö, Şahin D. An evaluation of maternal serum dynamic thiol-disulfide homeostasis and ischemia modified albumin changes in pregnant women with COVID-19. Turk J Obstet Gynecol 2022; 19:21-27. [PMID: 35343216 PMCID: PMC8966320 DOI: 10.4274/tjod.galenos.2022.72929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Objective: It is thought that oxidative stress, free radicals, reactive oxygen species and reactive nitrogen species affect the pathophysiology of coronavirus disease-2019 (COVID-19). This study aimed to evaluate the oxidative status in pregnant patients with COVID-19 infection according to the changes seen in the levels of maternal serum thiol-disulfide and ischemia-modified albumin (IMA). Materials and Methods: A study group was formed of 40 pregnant women with confirmed COVID-19 infection (study group) and a control group of 40 healthy pregnant women with no risk factors determined. In this prospective, case-controlled study, analyses were made of the maternal serum native thiol, total thiol, disulfide, IMA, and disulfide/native thiol concentrations. Results: The maternal serum native thiol and total thiol concentrations in the study group were determined to be statistically significantly lower (p=0.007 and p=0.006, respectively), and the disulfide/native thiol ratio was higher but not to a level of statistical significance (p=0.473). There was no difference between the two groups regarding IMA levels (p=0.731). Conclusion: The thiol-disulfide balance was seen to shift in the oxidant direction in pregnancies with COVID-19, which might support the view that ischemic processes play a role in the etiopathogenesis of this novel disease.
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Physicochemical Properties and Effects of Honeys on Key Biomarkers of Oxidative Stress and Cholesterol Homeostasis in HepG2 Cells. Nutrients 2021; 13:nu13010151. [PMID: 33466262 PMCID: PMC7824776 DOI: 10.3390/nu13010151] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 12/03/2020] [Accepted: 12/18/2020] [Indexed: 12/21/2022] Open
Abstract
Manuka honey and newly developed honeys (arjuna, guggul, jiaogulan and olive) were examined for their physicochemical, biochemical properties and effects on oxidative stress and cholesterol homeostasis in fatty acid-induced HepG2 cells. The honeys exhibited standard moisture content (<20%), electrical conductivity (<0.8 mS/cm), acidic pH, and monosaccharides (>60%), except olive honey (<60% total monosaccharides). They all expressed non-Newtonian behavior and 05 typical regions of the FTIR spectra as those of natural ones. Guggul and arjuna, manuka honeys showed the highest phenolic contents, correlating with their significant antioxidant activities. Arjuna, guggul and manuka honeys demonstrated the agreement of total cholesterol reduction and the transcriptional levels of AMPK, SREBP2, HCMGR, LDLR, LXRα. Jiaogulan honey showed the least antioxidant content and activity, but it was the most cytotoxic. Both jiaogulan and olive honeys modulated the tested gene in the pattern that should lead to a lower TC content, but this reduction did not occur after 24 h. All 2% concentrations of tested honeys elicited a clearer effect on NQO1 gene expression. In conclusion, the new honeys complied with international norms for natural honeys and we provide partial evidence for the protective effects of manuka, arjuna and guggul honeys amongst the tested ones on key biomarkers of oxidative stress and cholesterol homeostasis, pending further studies to better understand their modes of action.
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Nagaraju R, Joshi AKR, Vamadeva SG, Rajini PS. Deregulation of hepatic lipid metabolism associated with insulin resistance in rats subjected to chronic monocrotophos exposure. J Biochem Mol Toxicol 2020; 34:e22506. [PMID: 32267039 DOI: 10.1002/jbt.22506] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 02/24/2020] [Accepted: 03/26/2020] [Indexed: 12/19/2022]
Abstract
In our previous study, we demonstrated the potential of monocrotophos (MCP), an organophosphorus insecticide (OPI), to induce glucose intolerance, insulin resistance (IR), and dyslipidemia with hyperinsulinemia in rats after chronic exposure. As hyperinsulinemia is likely to exert an impact on hepatic lipid metabolism, we carried out this study to establish the effect of chronic MCP exposure (0.9 and 1.8 mg/kg/day for 180 days) on hepatic lipid metabolism in rats. The state of IR induced by MCP in rats was associated with an increase in the liver lipid content (triglyceride and cholesterol) and expression levels of sterol regulatory element-binding proteins, PPARγ, acetyl-CoA carboxylase, and fatty acid synthase in the liver. Similarly, activities of key enzymes (acetyl-COA carboxylase, fatty acid synthase, lipin 1, malic enzyme, glucose-6-phosphate dehydrogenase, and glycerol-3-phosphate dehydrogenase), which regulate lipogenesis, were enhanced in livers of pesticide-treated rats. A strong correlation was observed between insulin levels, hepatic lipid content, and plasma lipid profile in treated rats. Our study suggests that long-term exposure to OPIs not only has a propensity to induce a state of hyperinsulinemic IR, but it is also associated with augmented hepatic lipogenesis, which may explain dyslipidemia induced by chronic exposure to MCP.
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Affiliation(s)
- Raju Nagaraju
- Food Protectants and Infestation Control Department, CSIR-Central Food Technological Research Institute, Mysore, Karnataka, India
| | - Apurva K R Joshi
- Food Protectants and Infestation Control Department, CSIR-Central Food Technological Research Institute, Mysore, Karnataka, India
| | - Sowmya G Vamadeva
- Food Protectants and Infestation Control Department, CSIR-Central Food Technological Research Institute, Mysore, Karnataka, India
| | - Padmanabhan S Rajini
- Food Protectants and Infestation Control Department, CSIR-Central Food Technological Research Institute, Mysore, Karnataka, India
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10
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The Puzzling Conservation and Diversification of Lipid Droplets from Bacteria to Eukaryotes. Results Probl Cell Differ 2020; 69:281-334. [PMID: 33263877 DOI: 10.1007/978-3-030-51849-3_11] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Membrane compartments are amongst the most fascinating markers of cell evolution from prokaryotes to eukaryotes, some being conserved and the others having emerged via a series of primary and secondary endosymbiosis events. Membrane compartments comprise the system limiting cells (one or two membranes in bacteria, a unique plasma membrane in eukaryotes) and a variety of internal vesicular, subspherical, tubular, or reticulated organelles. In eukaryotes, the internal membranes comprise on the one hand the general endomembrane system, a dynamic network including organelles like the endoplasmic reticulum, the Golgi apparatus, the nuclear envelope, etc. and also the plasma membrane, which are linked via direct lateral connectivity (e.g. between the endoplasmic reticulum and the nuclear outer envelope membrane) or indirectly via vesicular trafficking. On the other hand, semi-autonomous organelles, i.e. mitochondria and chloroplasts, are disconnected from the endomembrane system and request vertical transmission following cell division. Membranes are organized as lipid bilayers in which proteins are embedded. The budding of some of these membranes, leading to the formation of the so-called lipid droplets (LDs) loaded with hydrophobic molecules, most notably triacylglycerol, is conserved in all clades. The evolution of eukaryotes is marked by the acquisition of mitochondria and simple plastids from Gram-positive bacteria by primary endosymbiosis events and the emergence of extremely complex plastids, collectively called secondary plastids, bounded by three to four membranes, following multiple and independent secondary endosymbiosis events. There is currently no consensus view of the evolution of LDs in the Tree of Life. Some features are conserved; others show a striking level of diversification. Here, we summarize the current knowledge on the architecture, dynamics, and multitude of functions of the lipid droplets in prokaryotes and in eukaryotes deriving from primary and secondary endosymbiosis events.
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Rodriguez‐Cuenca S, Carobbio S, Barceló‐Coblijn G, Prieur X, Relat J, Amat R, Campbell M, Dias AR, Bahri M, Gray SL, Vidal‐Puig A. P465L-PPARγ mutation confers partial resistance to the hypolipidaemic action of fibrates. Diabetes Obes Metab 2018; 20:2339-2350. [PMID: 29790245 PMCID: PMC6589924 DOI: 10.1111/dom.13370] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 05/04/2018] [Accepted: 05/12/2018] [Indexed: 12/13/2022]
Abstract
AIMS Familial partial lipodystrophic syndrome 3 (FPLD3) is associated with mutations in the transcription factor PPARγ. One of these mutations, the P467L, confers a dominant negative effect. We and others have previously investigated the pathophysiology associated with this mutation using a humanized mouse model that recapitulates most of the clinical symptoms observed in patients who have been phenotyped under different experimental conditions. One of the key clinical manifestations observed, both in humans and mouse models, is the ectopic accumulation of fat in the liver. With this study we aim to dissect the molecular mechanisms that contribute to the excessive accumulation of lipids in the liver and characterize the negative effect of this PPARγ mutation on the activity of PPARα in vivo when activated by fibrates. MATERIAL AND METHODS P465L-PPAR mutant and wild-type mice were divided into 8 experimental groups, 4 different conditions per genotype. Briefly, mice were fed a chow diet or a high-fat diet (HFD 45% Kcal from fat) for a period of 28 days and treated with WY14643 or vehicle for five days before culling. At the end of the experiment, tissues and plasma were collected. We performed extensive gene expression, fatty acid composition and histological analysis in the livers. The serum collected was used to measure several metabolites and to perform basic lipoprotein profile. RESULTS P465L mice showed increased levels of insulin and free fatty acids (FFA) as well as increased liver steatosis. They also exhibit decreased levels of very low density lipoproteins (VLDL) when fed an HFD. We also provide evidence of impaired expression of a number of well-established PPARα target genes in the P465L mutant livers. CONCLUSION Our data demonstrate that P465L confers partial resistance to the hypolipidemic action of fibrates. These results show that the fatty liver phenotype observed in P465L mutant mice is not only the consequence of dysfunctional adipose tissue, but also involves defective liver metabolism. All in all, the deleterious effects of P465L-PPARγ mutation may be magnified by their collateral negative effect on PPARα function.
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Affiliation(s)
- Sergio Rodriguez‐Cuenca
- University of Cambridge Metabolic Research Laboratories, Level 4Wellcome Trust‐MRC Institute of Metabolic ScienceCambridgeUK
| | - Stefania Carobbio
- University of Cambridge Metabolic Research Laboratories, Level 4Wellcome Trust‐MRC Institute of Metabolic ScienceCambridgeUK
- Wellcome Trust Sanger Institute, Wellcome Trust Genome CampusHinxtonUK
| | - Gwendolyn Barceló‐Coblijn
- Institut d'Investigació Sanitària Illes Balears (IdISBa, Balearic Islands Health Research Institute)PalmaSpain
| | - Xavier Prieur
- Département des Sciences de la Vie, L'Institut du Thorax, INSERM, CNRSUniversité de NantesNantesFrance
| | - Joana Relat
- Department of Nutrition, Food Science and Gastronomy, School of Pharmacy and Food Science, Food and Nutrition Torribera Campus. University of Barcelona (UB), Santa Coloma de Gramenet (Spain); INSA‐UB, Nutrition and Food Safety Research InstituteUniversity of BarcelonaBarcelonaSpain
| | - Ramon Amat
- Cell Signaling Unit, Departament de Ciències Experimentals i de la SalutUniversitat Pompeu Fabra (UPF)BarcelonaSpain
| | - Mark Campbell
- University of Cambridge Metabolic Research Laboratories, Level 4Wellcome Trust‐MRC Institute of Metabolic ScienceCambridgeUK
| | - Ana Rita Dias
- University of Cambridge Metabolic Research Laboratories, Level 4Wellcome Trust‐MRC Institute of Metabolic ScienceCambridgeUK
| | - Myriam Bahri
- University of Cambridge Metabolic Research Laboratories, Level 4Wellcome Trust‐MRC Institute of Metabolic ScienceCambridgeUK
- Wellcome Trust Sanger Institute, Wellcome Trust Genome CampusHinxtonUK
| | - Sarah L. Gray
- Northern Medical ProgramUniversity of Northern British ColumbiaPrince GeorgeCanada
| | - Antonio Vidal‐Puig
- University of Cambridge Metabolic Research Laboratories, Level 4Wellcome Trust‐MRC Institute of Metabolic ScienceCambridgeUK
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12
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Oleoylethanolamide treatment reduces neurobehavioral deficits and brain pathology in a mouse model of Gulf War Illness. Sci Rep 2018; 8:12921. [PMID: 30150699 PMCID: PMC6110778 DOI: 10.1038/s41598-018-31242-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 08/15/2018] [Indexed: 12/12/2022] Open
Abstract
There are nearly 250,000 Gulf War (GW) veterans who suffer from Gulf War Illness (GWI), a multi-symptom condition that remains untreatable. The main objective was to determine if targeting peroxisomal function could be of therapeutic value in GWI. We performed a pilot study that showed accumulation of very long chain fatty acids (VLCFA), which are metabolized in peroxisomes, in plasma from veterans with GWI. We then examined if targeting peroxisomal β-oxidation with oleoylethanolamide (OEA) restores these lipids to the normal levels and mitigates neuroinflammation and neurobehavioral deficits in a well-established mouse model of GWI. In GWI mice, treatment with OEA corresponded with cognitive benefits and reduced fatigue and disinhibition-like behavior in GWI mice. Biochemical and molecular analysis of the brain tissue showed reduced astroglia and microglia staining, decreased levels of chemokines and cytokines, and decreased NFκB phosphorylation. Treatment with OEA reduced accumulation of peroxisome specific VLCFA in the brains of GWI mice. These studies further support the translational value of targeting peroxisomes. We expect that OEA may be a potential therapy for treating neurobehavioral symptoms and the underlying lipid dysfunction and neuroinflammation associated with GWI. Oleoylethanolamide is available as a dietary supplement, making it appealing for human translational studies.
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Oscarsson J, Önnerhag K, Risérus U, Sundén M, Johansson L, Jansson PA, Moris L, Nilsson PM, Eriksson JW, Lind L. Effects of free omega-3 carboxylic acids and fenofibrate on liver fat content in patients with hypertriglyceridemia and non-alcoholic fatty liver disease: A double-blind, randomized, placebo-controlled study. J Clin Lipidol 2018; 12:1390-1403.e4. [PMID: 30197273 DOI: 10.1016/j.jacl.2018.08.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 07/04/2018] [Accepted: 08/01/2018] [Indexed: 12/31/2022]
Abstract
BACKGROUND Treatment with omega-3 fatty acids and fenofibrates reduces serum triglyceride levels, but few studies have compared the effect of these agents on liver fat. OBJECTIVE The aim of the EFFECT I trial (NCT02354976) was to determine the effects of free omega-3 carboxylic acids (OM-3CA) and fenofibrate on liver fat in overweight or obese individuals with non-alcoholic fatty liver disease and hypertriglyceridemia. METHODS Seventy-eight patients were randomized to receive oral doses of 4 g OM-3CA (n = 25), 200 mg fenofibrate (n = 27), or placebo (n = 26) for 12 weeks in a double-blind, parallel-group study. Liver proton density fat fraction (PDFF) and volume, pancreas volume, and adipose tissue volumes were assessed by magnetic resonance imaging. RESULTS Changes in liver PDFF at 12 weeks were not significantly different across treatment groups (relative changes from baseline: placebo, +4%; OM-3CA, -2%; and fenofibrate, +17%). The common PNPLA3 genetic polymorphism (I148M) did not significantly influence the effects of OM-3CA or fenofibrate on liver PDFF. Fenofibrate treatment significantly increased liver and pancreas volumes vs placebo treatment, and the changes in liver and pancreas volumes were positively correlated (rho 0.45, P = .02). Total liver fat volume increased significantly in patients using fenofibrate vs OM-3CA (+23% vs -3%, P = .04). Compared with OM-3CA, fenofibrate increased total liver fat and liver volume. Serum triglycerides decreased with OM-3CA (-26%, P = .02) and fenofibrate (-38%, P < .001) vs placebo. In contrast to OM-3CA, fenofibrate reduced plasma docosahexaenoic acid levels and increased plasma acetylcarnitine and butyrylcarnitine levels, estimated delta-9 desaturase activity and the concentration of urine F2-isoprostanes. CONCLUSIONS OM-3CA and fenofibrate reduced serum triglycerides but did not reduce liver fat. Fenofibrate increased total liver volume and total liver fat volume vs OM-3CA, indicating a complex effect of fenofibrate on human hepatic lipid metabolism.
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Affiliation(s)
| | | | - Ulf Risérus
- Department of Public Health and Caring Sciences, Uppsala University, Uppsala, Sweden
| | | | | | - Per-Anders Jansson
- Department of Molecular and Clinical Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Linda Moris
- Karolinska Trial Alliance, Karolinska University Hospital, Solna, Sweden
| | - Peter M Nilsson
- Department of Clinical Sciences, Lund University, Malmö, Sweden
| | - Jan W Eriksson
- Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Lars Lind
- Department of Medical Sciences, Uppsala University, Uppsala, Sweden
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14
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Bahirat UA, Talwar R, Shenoy RR, Nemmani KVS, Goel RN. Combination of APD668, a G protein-coupled receptor 119 agonist with linagliptin, a DPPIV inhibitor, prevents progression of steatohepatitis in a murine model of non-alcoholic steatohepatitis with diabetes. Med Mol Morphol 2018; 52:36-43. [PMID: 29959534 DOI: 10.1007/s00795-018-0200-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 06/26/2018] [Indexed: 12/13/2022]
Abstract
Non-alcoholic steatohepatitis (NASH) is characterized by the presence of hepatic steatosis, oxidative stress, inflammation, and hepatocyte injury with or without fibrosis. In this study, we explored the effect of APD668, a GPR119 agonist alone or in combination with linagliptin, a DPPIV inhibitor, on the progression of steatohepatitis in a murine model of NASH with diabetes. A novel NASH model with diabetes was generated by administration of streptozotocin injection to neonatal C57BL/6 mice (2-3 days old) combined with a high-fat diet feeding from the age of 4 weeks. The plasma biochemical parameters, oxidative stress, inflammation and histopathological changes were assessed. APD668 alone showed reduction in plasma glucose (- 39%, P < 0.05) and triglyceride level (- 26%) whereas a combined treatment of APD668 with linagliptin resulted in a more pronounced reduction in plasma glucose (- 52%, P < 0.001) and triglyceride (- 50%, P < 0.05) in NASH mice. In addition, co-administration of APD668 with linagliptin demonstrated a significant decrease in hepatic triglyceride, NAS score, hepatic TBARS and hepatic TNF-α in NASH mice with diabetes. These findings suggest that GPR119 receptor agonists in combination with DPPIV inhibitors may represent a promising therapeutic strategy for the treatment of NASH.
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Affiliation(s)
- Umakant Ashok Bahirat
- Department of Pharmacology, Novel Drug Discovery and Development (NDDD), Lupin Limited (Research Park), 46A/47A, Village Nande, Taluka Mulshi, Pune, Maharashtra, 412115, India.
| | - Rashmi Talwar
- Department of Pharmacology, Novel Drug Discovery and Development (NDDD), Lupin Limited (Research Park), 46A/47A, Village Nande, Taluka Mulshi, Pune, Maharashtra, 412115, India
| | - Rekha Raghuveer Shenoy
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Kumar V S Nemmani
- Department of Pharmacology, Novel Drug Discovery and Development (NDDD), Lupin Limited (Research Park), 46A/47A, Village Nande, Taluka Mulshi, Pune, Maharashtra, 412115, India
| | - Rajan Naresh Goel
- Department of Pharmacology, Novel Drug Discovery and Development (NDDD), Lupin Limited (Research Park), 46A/47A, Village Nande, Taluka Mulshi, Pune, Maharashtra, 412115, India
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15
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Zhang P, Meng L, Song L, Du J, Du S, Cui W, Liu C, Li F. Roles of Perilipins in Diseases and Cancers. Curr Genomics 2018; 19:247-257. [PMID: 29755288 PMCID: PMC5930447 DOI: 10.2174/1389202918666170915155948] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 01/03/2017] [Accepted: 04/25/2017] [Indexed: 12/14/2022] Open
Abstract
Perilipins, an ancient family of lipid droplet-associated proteins, are embedded in a phospho-lipid monolayer of intracellular lipid droplets. The core of lipid droplets is composed of neutral fat, which mainly includes triglyceride and cholesterol ester. Perilipins are closely related to the function of lipid droplets, and they mediate lipid metabolism and storage. Therefore, perilipins play an important role in the development of obesity, diabetes, cancer, hepatic diseases, atherosclerosis, and carcinoma, which are caused by abnormal lipid metabolism. Accumulation of lipid droplets is a common phenomenon in tumor cells. Available data on the pathophysiology of perilipins and the relationship of perilipins with endocrine metabolic diseases and cancers are summarized in this mini-review. The research progress on this family offers novel insights into the therapeutic strategies for these diseases.
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Affiliation(s)
- Pengpeng Zhang
- Department of Pathology and The Key Laboratories for Xinjiang Endemic and Ethnic Diseases, School of Medicine, Shihezi University, Shihezi 832002, Xinjiang, China
| | - Lian Meng
- Department of Pathology and The Key Laboratories for Xinjiang Endemic and Ethnic Diseases, School of Medicine, Shihezi University, Shihezi 832002, Xinjiang, China
| | - Lingxie Song
- Department of Pathology and The Key Laboratories for Xinjiang Endemic and Ethnic Diseases, School of Medicine, Shihezi University, Shihezi 832002, Xinjiang, China
| | - Juan Du
- Department of Pathology and The Key Laboratories for Xinjiang Endemic and Ethnic Diseases, School of Medicine, Shihezi University, Shihezi 832002, Xinjiang, China
| | - Shutong Du
- Department of Pathology and The Key Laboratories for Xinjiang Endemic and Ethnic Diseases, School of Medicine, Shihezi University, Shihezi 832002, Xinjiang, China
| | - Wenwen Cui
- Department of Pathology and The Key Laboratories for Xinjiang Endemic and Ethnic Diseases, School of Medicine, Shihezi University, Shihezi 832002, Xinjiang, China
| | - Chunxia Liu
- Department of Pathology and The Key Laboratories for Xinjiang Endemic and Ethnic Diseases, School of Medicine, Shihezi University, Shihezi 832002, Xinjiang, China
| | - Feng Li
- Department of Pathology and The Key Laboratories for Xinjiang Endemic and Ethnic Diseases, School of Medicine, Shihezi University, Shihezi 832002, Xinjiang, China.,Department of Pathology, Beijing Chaoyang Hospital, Capital Medical University, Beijing100020, China
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16
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Bahirat UA, Shenoy RR, Talwar R, Goel RN, Nemmani KVS. Co-administration of APD668, a G protein-coupled receptor 119 agonist and linagliptin, a DPPIV inhibitor, prevents progression of steatohepatitis in mice fed on a high trans-fat diet. Biochem Biophys Res Commun 2017; 495:1608-1613. [PMID: 29203247 DOI: 10.1016/j.bbrc.2017.12.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 12/01/2017] [Indexed: 12/16/2022]
Abstract
Non-Alcoholic SteatoHepatitis (NASH) is the more severe form of Non-Alcoholic Fatty Liver Disease (NAFLD) and is characterized by the presence of hepatic steatosis, oxidative stress, inflammation, hepatocyte injury with or without fibrosis. Recently, GPR119 receptor has emerged as a novel therapeutic target for the treatment of dyslipidemia and non-alcoholic steatohepatitis. In the present study, we investigated the effect of APD668, a GPR119 agonist alone or in combination with linagliptin, a DPPIV inhibitor on the progression of steatohepatitis in mice fed on a high trans-fat diet. In this study, monotherapy with either APD668 or linagliptin caused a reduction in the levels of ALT, AST, glucose, cholesterol and epididymal fat mass but the effect was more pronounced upon treatment with combination of both drugs. On the other hand, combined treatment of APD668 with linagliptin demonstrated a non-significant additive effect in reduction of hepatic triglyceride (-78%) and cholesterol (-56%) compared to monotherapy groups. Moreover, co-administration of APD668 and linagliptin resulted in enhanced levels of active GLP-1 with additional benefit of significant synergistic decrease in body weight gain (-19%) in mice. We speculated that the enhanced effect observed with the combination treatment could be due to either 1) direct activation of GPR119 receptors present in liver and intestine or 2) enhanced active GLP-1 levels or 3) decreased degradation of GLP-1 in-vivo through DPPIV inhibition. Therefore, these findings clearly suggest that GPR119 receptor agonists in combination with DPPIV inhibitors may represent a promising therapeutic strategy for the treatment of non-alcoholic steatohepatitis.
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Affiliation(s)
- Umakant Ashok Bahirat
- Lupin Limited (Research Park), Department of Pharmacology, Novel Drug Discovery and Development (NDDD), 46A/47A, Village Nande, Mulshi, Pune, 412 115, Maharashtra, India.
| | - Rekha Raghuveer Shenoy
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal University, Manipal, 576104, Karnataka, India
| | - Rashmi Talwar
- Lupin Limited (Research Park), Department of Pharmacology, Novel Drug Discovery and Development (NDDD), 46A/47A, Village Nande, Mulshi, Pune, 412 115, Maharashtra, India
| | - Rajan Naresh Goel
- Lupin Limited (Research Park), Department of Pharmacology, Novel Drug Discovery and Development (NDDD), 46A/47A, Village Nande, Mulshi, Pune, 412 115, Maharashtra, India
| | - Kumar V S Nemmani
- Lupin Limited (Research Park), Department of Pharmacology, Novel Drug Discovery and Development (NDDD), 46A/47A, Village Nande, Mulshi, Pune, 412 115, Maharashtra, India
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17
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Rajamoorthi A, Arias N, Basta J, Lee RG, Baldán Á. Amelioration of diet-induced steatohepatitis in mice following combined therapy with ASO-Fsp27 and fenofibrate. J Lipid Res 2017; 58:2127-2138. [PMID: 28874443 PMCID: PMC5665668 DOI: 10.1194/jlr.m077941] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 08/18/2017] [Indexed: 12/16/2022] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease. NAFLD progresses from benign steatosis to steatohepatitis (NASH) to cirrhosis and is linked to hepatocellular carcinoma. No targeted treatment is currently approved for NAFLD/NASH. We previously showed that fat-specific protein 27 (FSP27), a lipid droplet-associated protein that controls triglyceride turnover in the hepatocyte, is required for fasting- and diet-induced triglyceride accumulation in the liver. However, silencing Fsp27 with antisense oligonucleotides (ASOs) did not improve hepatosteatosis in genetic nor nutritional mouse models of obesity. Herein, we tested the therapeutic potential of ASO-Fsp27 when used in combination with the PPARα agonist fenofibrate. C57BL/6 mice were fed a high-trans-fat, high-cholesterol, high-fructose diet for eight weeks to establish NASH, then kept on diet for six additional weeks while dosed with ASOs and fenofibrate, alone or in combination. Data show that ASO-Fsp27 and fenofibrate synergize to promote resistance to diet-induced obesity and hypertriglyceridemia and to reverse hepatic steatosis, inflammation, oxidative stress, and fibrosis. This multifactorial improvement of liver disease noted when combining both drugs suggests that a course of treatment that includes both reduced FSP27 activity and activation of PPARα could provide therapeutic benefit to patients with NAFLD/NASH.
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Affiliation(s)
- Ananthi Rajamoorthi
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University, Saint Louis, MO
| | - Noemí Arias
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University, Saint Louis, MO
| | - Jeannine Basta
- Department of Internal Medicine, Saint Louis University, Saint Louis, MO
| | - Richard G Lee
- Cardiovascular Group, Antisense Drug Discovery, Ionis Pharmaceuticals, Carlsbad, CA
| | - Ángel Baldán
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University, Saint Louis, MO .,Center for Cardiovascular Research, Saint Louis University, Saint Louis, MO.,Liver Center, Saint Louis University, Saint Louis, MO
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18
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Kimmel AR, Sztalryd C. The Perilipins: Major Cytosolic Lipid Droplet-Associated Proteins and Their Roles in Cellular Lipid Storage, Mobilization, and Systemic Homeostasis. Annu Rev Nutr 2017; 36:471-509. [PMID: 27431369 DOI: 10.1146/annurev-nutr-071813-105410] [Citation(s) in RCA: 176] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The discovery by Dr. Constantine Londos of perilipin 1, the major scaffold protein at the surface of cytosolic lipid droplets in adipocytes, marked a fundamental conceptual change in the understanding of lipolytic regulation. Focus then shifted from the enzymatic activation of lipases to substrate accessibility, mediated by perilipin-dependent protein sequestration and recruitment. Consequently, the lipid droplet became recognized as a unique, metabolically active cellular organelle and its surface as the active site for novel protein-protein interactions. A new area of investigation emerged, centered on lipid droplets' biology and their role in energy homeostasis. The perilipin family is of ancient origin and has expanded to include five mammalian genes and a growing list of evolutionarily conserved members. Universally, the perilipins modulate cellular lipid storage. This review provides a summary that connects the perilipins to both cellular and whole-body homeostasis.
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Affiliation(s)
- Alan R Kimmel
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, The National Institutes of Health, Bethesda, Maryland 20892;
| | - Carole Sztalryd
- The Geriatric Research Education and Clinical Center, Baltimore Veterans Affairs Medical Center, Baltimore, Maryland 21201.,Division of Endocrinology, Department of Medicine, School of Medicine, University of Maryland, Baltimore, Maryland 21201;
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19
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Dijk W, Mattijssen F, de la Rosa Rodriguez M, Loza Valdes A, Loft A, Mandrup S, Kalkhoven E, Qi L, Borst JW, Kersten S. Hypoxia-Inducible Lipid Droplet-Associated Is Not a Direct Physiological Regulator of Lipolysis in Adipose Tissue. Endocrinology 2017; 158:1231-1251. [PMID: 28323980 PMCID: PMC5460841 DOI: 10.1210/en.2016-1809] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 03/13/2017] [Indexed: 12/20/2022]
Abstract
Triglycerides are stored in specialized organelles called lipid droplets. Numerous proteins have been shown to be physically associated with lipid droplets and govern their function. Previously, the protein hypoxia-inducible lipid droplet-associated (HILPDA) was localized to lipid droplets and was suggested to inhibit triglyceride lipolysis in hepatocytes. We confirm the partial localization of HILPDA to lipid droplets and show that HILPDA is highly abundant in adipose tissue, where its expression is controlled by the peroxisome proliferator-activated receptor γ and by β-adrenergic stimulation. Levels of HILPDA markedly increased during 3T3-L1 adipocyte differentiation. Nevertheless, silencing of Hilpda using small interfering RNA or overexpression of Hilpda using adenovirus did not show a clear impact on 3T3-L1 adipogenesis. Following β-adrenergic stimulation, the silencing of Hilpda in adipocytes did not significantly alter the release of nonesterified fatty acids (NEFA) and glycerol. By contrast, adenoviral-mediated overexpression of Hilpda modestly attenuated the release of NEFA from adipocytes following β-adrenergic stimulation. In mice, adipocyte-specific inactivation of Hilpda had no effect on plasma levels of NEFA and glycerol after fasting, cold exposure, or pharmacological β-adrenergic stimulation. In addition, other relevant metabolic parameters were unchanged by adipocyte-specific inactivation of Hilpda. Taken together, we find that HILPDA is highly abundant in adipose tissue, where its levels are induced by peroxisome proliferator-activated receptor γ and β-adrenergic stimulation. In contrast to the reported inhibition of lipolysis by HILPDA in hepatocytes, our data do not support an important direct role of HILPDA in the regulation of lipolysis in adipocytes in vivo and in vitro.
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Affiliation(s)
- Wieneke Dijk
- Nutrition, Metabolism, and Genomics Group, Division of Human Nutrition, Wageningen University, 6708 WE Wageningen, The Netherlands
| | - Frits Mattijssen
- Nutrition, Metabolism, and Genomics Group, Division of Human Nutrition, Wageningen University, 6708 WE Wageningen, The Netherlands
| | - Montserrat de la Rosa Rodriguez
- Nutrition, Metabolism, and Genomics Group, Division of Human Nutrition, Wageningen University, 6708 WE Wageningen, The Netherlands
| | - Angel Loza Valdes
- Nutrition, Metabolism, and Genomics Group, Division of Human Nutrition, Wageningen University, 6708 WE Wageningen, The Netherlands
| | - Anne Loft
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Susanne Mandrup
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Eric Kalkhoven
- Molecular Cancer Research and Center for Molecular Medicine, University Medical Centre Utrecht, 3584 CG Utrecht, The Netherlands
| | - Ling Qi
- University of Michigan Medical School, Ann Arbor, Michigan 48105
| | - Jan Willem Borst
- Laboratory of Biochemistry, Microspectroscopy Centre, Wageningen University, 6708 WE Wageningen, The Netherlands
| | - Sander Kersten
- Nutrition, Metabolism, and Genomics Group, Division of Human Nutrition, Wageningen University, 6708 WE Wageningen, The Netherlands
- University of Michigan Medical School, Ann Arbor, Michigan 48105
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20
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Hanging Drop, A Best Three-Dimensional (3D) Culture Method for Primary Buffalo and Sheep Hepatocytes. Sci Rep 2017; 7:1203. [PMID: 28446763 PMCID: PMC5430879 DOI: 10.1038/s41598-017-01355-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 03/27/2017] [Indexed: 02/07/2023] Open
Abstract
Livestock, having close resemblance to humans, could be a better source of primary hepatocytes than rodents. Herein, we successfully developed three-dimensional (3D) culturing system for primary sheep and buffalo hepatocytes. The 3D-structures of sheep hepatocytes were formed on the fifth-day and maintained until the tenth-day on polyHEMA-coated plates and in hanging drops with William’s E media (HDW). Between the cultured and fresh cells, we observed a similar expression of GAPDH, HNF4α, ALB, CYP1A1, CK8 and CK18. Interestingly, a statistically significant increase was noted in the TAT, CPS, AFP, AAT, GSP and PCNA expression. In buffalo hepatocytes culture, 3D-like structures were formed on the third-day and maintained until the sixth-day on polyHEMA and HDW. The expression of HNF4α, GSP, CPS, AFP, AAT, PCNA and CK18 was similar between cultured and fresh cells. Further, a statistically significant increase in the TAT and CK8 expression, and a decrease in the GAPDH, CYP1A1 and ALB expression were noted. Among the culture systems, HDW maintained the liver transcript markers more or less similar to the fresh hepatocytes of the sheep and buffalo for ten and six days, respectively. Taken together, hanging drop is an efficient method for 3D culturing of primary sheep and buffalo hepatocytes.
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21
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Bahirat UA, Shenoy RR, Goel RN, Nemmani KVS. APD668, a G protein-coupled receptor 119 agonist improves fat tolerance and attenuates fatty liver in high-trans fat diet induced steatohepatitis model in C57BL/6 mice. Eur J Pharmacol 2017; 801:35-45. [PMID: 28274625 DOI: 10.1016/j.ejphar.2017.02.043] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 02/23/2017] [Accepted: 02/24/2017] [Indexed: 01/09/2023]
Abstract
G-protein coupled receptor 119 (GPR119) receptor is a rhodopsin-like, class A Gαs-coupled receptor, predominantly expressed in pancreatic islet cells and intestinal entero-endocrine cells. GPR119 has been emerged as a novel therapeutic target for the treatment of dyslipidemia in type 2 diabetes. In this study, we investigated the effect of APD668, a GPR119 agonist alone and in combination with linagliptin, a DPPIV inhibitor on oral fat tolerance test. Our findings demonstrate that APD668, a GPR119 agonist inhibits the intestinal triglyceride absorption after acute fat load in mice. Single dose administration of APD668 increases incretin secretion and enhances total PYY levels in presence of fat load in mice. We found that, the anti-dyslipidemic action of APD668 was reversed in presence of exendin-3 in oral fat tolerance test. In addition, our results showed that exendin-3 (9-39) failed to block the effect of APD668 on gastric emptying indicating that gastric emptying effects of APD668 are indeed mediated through GPR119 receptor dependent mechanism. Combined administration of APD668 and linagliptin significantly increased plasma active GLP-1 levels in-vivo and showed improvement in fat tolerance. However, APD668 failed to show anti-dyslipidemic activity in tyloxapol-induced hyperlipidemia in mice. Furthermore, we investigated the chronic effects of APD668 on hepatic steatosis in high trans-fat diet fed steatohepatitis model in mice. Oral administration of APD668 in HTF diet fed mice ameliorated hepatic endpoints such as plasma ALT, AST, liver weight and steatosis. These findings suggest that GPR119 agonists may represent a promising therapeutic strategy for the treatment of dyslipidemia and non-alcoholic steatohepatitis.
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Affiliation(s)
- Umakant Ashok Bahirat
- Lupin Limited (Research Park), Department of Pharmacology, Novel Drug Discovery and Development (NDDD), 46A/47A, Village Nande, Mulshi, Pune 412115, Maharashtra, India.
| | - Rekha Raghuveer Shenoy
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal University, Manipal 576104, Karnataka, India
| | - Rajan Naresh Goel
- Lupin Limited (Research Park), Department of Pharmacology, Novel Drug Discovery and Development (NDDD), 46A/47A, Village Nande, Mulshi, Pune 412115, Maharashtra, India
| | - Kumar V S Nemmani
- Lupin Limited (Research Park), Department of Pharmacology, Novel Drug Discovery and Development (NDDD), 46A/47A, Village Nande, Mulshi, Pune 412115, Maharashtra, India
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22
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Sentinelli F, Capoccia D, Incani M, Bertoccini L, Severino A, Pani MG, Manconi E, Cossu E, Leonetti F, Baroni MG. The perilipin 2 (PLIN2) gene Ser251Pro missense mutation is associated with reduced insulin secretion and increased insulin sensitivity in Italian obese subjects. Diabetes Metab Res Rev 2016; 32:550-6. [PMID: 26443937 DOI: 10.1002/dmrr.2751] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Revised: 09/07/2015] [Accepted: 10/05/2015] [Indexed: 01/23/2023]
Abstract
BACKGROUND Perilipin 2 (PLIN2), a member of the family of perilipin lipid droplets coating proteins, is very widely expressed. The Ser251Pro (rs35568725) missense mutation in exon 6 of PLIN2 gene was previously associated with increased lipid accumulation, decreased lipolysis and increased number of small lipid droplets per cell. Furthermore, the Pro251 mutation was associated with decreased plasma triglyceride and very low density lipoprotein concentrations in population studies. The aim of this study was to evaluate the effect of the Ser251Pro mutation of PLIN2 gene in a cohort with a higher predisposition to obesity-associated metabolic alterations, such as insulin resistance, decreased insulin-secretion, hyperglycaemia, and dyslipidaemia. METHODS A large cohort (N = 1692) of Italian obese subjects (mean body mass index = 41 kg/m(2) ) was genotyped for the Ser251Pro mutation. All participants underwent oral glucose tolerance tests (OGTT), with measurement of glucose and insulin levels. Indices of insulin resistance and of insulin secretion were also calculated. Clinical and biochemical parameters were collected for all participants. RESULTS We observed that insulin concentration was significantly reduced at 120 min after the administration of glucose in Pro251 allele carriers, whereas glucose levels were similar in Pro251 allele carriers and non-carriers throughout the OGTT. Furthermore, the CIR120 index of insulin secretion was significantly lower (P < 0.035) and the ISI index of insulin-sensitivity was significantly higher (P < 0.031) in carriers of the Pro251 allele. When we analysed men and women separately to test for gender-specific associations, we observed that in women insulin levels were significantly lower in Pro251 allele carriers compared with wild-type subjects throughout the whole OGTT. In men, we confirmed a significant reduction in insulin concentration only at 120 min after the OGTT. No significant differences between genotype groups regarding triglyceride levels and anyother clinical and metabolic parameters were observed. CONCLUSION We observed a strong significant association between the PLIN2 Pro251 mutation and lower insulin secretion associated with an increased insulin sensitivity. Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
- Federica Sentinelli
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - Danila Capoccia
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - Michela Incani
- Endocrinology and Diabetes, Department of Medical Sciences, University of Cagliari, Cagliari, Italy
| | - Laura Bertoccini
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - Anna Severino
- Institute of Cardiology, Catholic University, Rome, Italy
| | - Maria Grazia Pani
- Endocrinology and Diabetes, Department of Medical Sciences, University of Cagliari, Cagliari, Italy
| | - Ettore Manconi
- Endocrinology and Diabetes, Department of Medical Sciences, University of Cagliari, Cagliari, Italy
| | - Efisio Cossu
- Endocrinology and Diabetes, Department of Medical Sciences, University of Cagliari, Cagliari, Italy
| | - Frida Leonetti
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - Marco G Baroni
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
- Endocrinology and Diabetes, Department of Medical Sciences, University of Cagliari, Cagliari, Italy
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Kaneko T, Chihara T, Shimpo K, Beppu H, Higashiguchi T, Sonoda S. Inhibition of Azoxymethane-induced Colorectal Aberrant Crypt Foci in Mice Fed a High-fat Diet by Pleurotus eryngii (Eringi) and Hypsizygus marmoreus (Bunashimeji). Asian Pac J Cancer Prev 2016; 16:3881-5. [PMID: 25987054 DOI: 10.7314/apjcp.2015.16.9.3881] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Obesity markedly increases the risk of colorectal cancer. Recently, the preventive effects of edible mushrooms on triglyceride elevation and visceral fat accumulation have been reported. Here, the effects of Pleurotus eryngii (Eringi) and Hypsizygus marmoreus (Bunashimeji) on azoxymethane (AOM)-induced aberrant crypt foci (ACF; precancerous lesions) in the colorectums of mice fed a high-fat diet were examined. Eringi (ER) and Bunashimeji (BU) mushroom powder samples were used. Six-week-old male C57BL/6J mice received an intraperitoneal injection of AOM (10 mg/kg) once a week for two weeks, and were sacrificed and dissected at 6 weeks after the start of the experiment. After the initiation of the experiment, they received a normal diet (ND), high-fat diet (HFD), HFD + ER (1 or 5% of diet), or HFD + BU (1 or 5% of diet). As a result, body and fat weights were significantly lower in the 5% ER and BU groups than in the HFD group. Liver triglyceride levels were also significantly lower in the 5% ER and BU groups. Total liver cholesterol levels were significantly lower in the 5% ER group. The numbers of ACF (especially large ACF) showed strong inhibitory effects in both ER and BU groups. Measurement of the cell proliferation marker Ki-67 labeling index in the colonic mucosa demonstrated more significant suppression in both ER and BU groups than in the HFD group. These results suggest that the simultaneous intake of ER and BU may inhibit colorectal tumorigenesis in HFD-fed mice.
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Affiliation(s)
- Takaaki Kaneko
- Division of Biochemistry, Fujita Memorial Nanakuri Institute, Fujita Health University, Tsu, Mie, Japan E-mail :
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PPARα Is Required for PPARδ Action in Regulation of Body Weight and Hepatic Steatosis in Mice. PPAR Res 2015; 2015:927057. [PMID: 26604919 PMCID: PMC4641930 DOI: 10.1155/2015/927057] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 09/09/2015] [Indexed: 12/24/2022] Open
Abstract
Peroxisome proliferator activated receptors alpha (PPARα) and delta (PPARδ) belong to the nuclear receptor superfamily. PPARα is a target of well established lipid-lowering drugs. PPARδ (also known as PPARβ/δ) has been investigated as a promising antidiabetic drug target; however, the evidence in the literature on PPARδ effect on hepatic lipid metabolism is inconsistent. Mice conditionally expressing human PPARδ demonstrated pronounced weight loss and promoted hepatic steatosis when treated with GW501516 (PPARδ-agonist) when compared to wild type mice. This effect was completely absent in mice with either a dominant negative form of PPARδ or deletion of the DNA binding domain of PPARδ. This confirmed the absolute requirement for PPARδ in the physiological actions of GW501516 and confirmed the potential utility against the human form of this receptor. Surprisingly the genetic deletion of PPARα also abrogated the effect of GW501516 in terms of both weight loss and hepatic lipid accumulation. Also the levels of the PPARα endogenous agonist 16:0/18:1-GPC were shown to be modulated by PPARδ in wild type mice. Our results show that both PPARδ and PPARα receptors are essential for GW501516-driven adipose tissue reduction and subsequently hepatic steatosis, with PPARα working downstream of PPARδ.
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Csak T, Bala S, Lippai D, Kodys K, Catalano D, Iracheta-Vellve A, Szabo G. MicroRNA-155 Deficiency Attenuates Liver Steatosis and Fibrosis without Reducing Inflammation in a Mouse Model of Steatohepatitis. PLoS One 2015; 10:e0129251. [PMID: 26042593 PMCID: PMC4456142 DOI: 10.1371/journal.pone.0129251] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 05/06/2015] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND & AIM MicroRNAs (miRs) regulate hepatic steatosis, inflammation and fibrosis. Fibrosis is the consequence of chronic tissue damage and inflammation. We hypothesized that deficiency of miR-155, a master regulator of inflammation, attenuates steatohepatitis and fibrosis. METHODS Wild type (WT) and miR-155-deficient (KO) mice were fed methionine-choline-deficient (MCD) or -supplemented (MCS) control diet for 5 weeks. Liver injury, inflammation, steatosis and fibrosis were assessed. RESULTS MCD diet resulted in steatohepatitis and increased miR-155 expression in total liver, hepatocytes and Kupffer cells. Steatosis and expression of genes involved in fatty acid metabolism were attenuated in miR-155 KO mice after MCD feeding. In contrast, miR-155 deficiency failed to attenuate inflammatory cell infiltration, nuclear factor κ beta (NF-κB) activation and enhanced the expression of the pro-inflammatory cytokines tumor necrosis factor alpha (TNFα) and monocyte chemoattractant protein-1 (MCP1) in MCD diet-fed mice. We found a significant attenuation of apoptosis (cleaved caspase-3) and reduction in collagen and α smooth muscle actin (αSMA) levels in miR-155 KO mice compared to WTs on MCD diet. In addition, we found attenuation of platelet derived growth factor (PDGF), a pro-fibrotic cytokine; SMAD family member 3 (Smad3), a protein involved in transforming growth factor-β (TGFβ) signal transduction and vimentin, a mesenchymal marker and indirect indicator of epithelial-to-mesenchymal transition (EMT) in miR-155 KO mice. Nuclear binding of CCAAT enhancer binding protein β (C/EBPβ) a miR-155 target involved in EMT was significantly increased in miR-155 KO compared to WT mice. CONCLUSIONS Our novel data demonstrate that miR-155 deficiency can reduce steatosis and fibrosis without decreasing inflammation in steatohepatitis.
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Affiliation(s)
- Timea Csak
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Shashi Bala
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Dora Lippai
- 2nd Department of Medicine, Semmelweis University, Budapest, Hungary
| | - Karen Kodys
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Donna Catalano
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Arvin Iracheta-Vellve
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Gyongyi Szabo
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
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Arisqueta L, Navarro-Imaz H, Rueda Y, Fresnedo O. Cholesterol mobilization from hepatic lipid droplets during endotoxemia is altered in obese ob/ob mice. J Biochem 2015; 158:321-9. [DOI: 10.1093/jb/mvv047] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 03/31/2015] [Indexed: 11/12/2022] Open
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Langhi C, Baldán Á. CIDEC/FSP27 is regulated by peroxisome proliferator-activated receptor alpha and plays a critical role in fasting- and diet-induced hepatosteatosis. Hepatology 2015; 61:1227-38. [PMID: 25418138 PMCID: PMC4376564 DOI: 10.1002/hep.27607] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 11/10/2014] [Indexed: 12/16/2022]
Abstract
UNLABELLED The cell death-inducing DNA fragmentation factor alpha-like effector c (CIDEC; also known in rodents as FSP27 or fat-specific protein 27) is a lipid droplet-associated protein that promotes intracellular triglyceride (TAG) storage. CIDEC/Fsp27 is highly expressed in adipose tissue, but undetectable in normal liver. However, its hepatic expression rises during fasting or under genetic or diet-induced hepatosteatosis in both mice and patients. Herein, we demonstrate that CIDEC/Fsp27 is a direct transcriptional target of the nuclear receptor PPARα (peroxisome proliferator-activated receptor alpha) in both mouse and human hepatocytes, and that preventing Fsp27 induction accelerates PPARα-stimulated fatty acid oxidation. We show that adenoviral-mediated silencing of hepatic Fsp27 abolishes fasting-induced liver steatosis in the absence of changes in plasma lipids. Finally, we report that anti-Fsp27 short hairpin RNA and PPARα agonists synergize to ameliorate hepatosteatosis in mice fed a high fat diet. CONCLUSIONS Together, our data highlight the physiological importance of CIDEC/Fsp27 in TAG homeostasis under both physiological and pathological liver steatosis. Our results also suggest that patients taking fibrates likely have elevated levels of hepatic CIDEC, which may limit the efficient mobilization and catabolism of hepatic TAGs.
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Affiliation(s)
- Cédric Langhi
- Edward A. Doisy Department of Biochemistry & Molecular Biology, Center for Cardiovascular Research, Saint Louis University, Saint Louis, MO
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Abstract
Microsomal triglyceride transfer protein (MTP) is one of the promising targets for the therapy of dyslipidemia and MTP inhibition can lead to robust plasma low-density lipoprotein cholesterol (LDL-C) reduction. Lomitapide, a small-molecule MTP inhibitor, was recently approved by the US FDA as an additional treatment for homozygous familial hypercholesterolemia (hoFH). However, liver-related side effects, including hepatic fat accumulation and transaminase elevations, are the main safety concerns associated with MTP inhibitors. Here, we review recent knowledge on the mechanisms underlying liver toxicity of MTP inhibitors. The contribution of altered levels of intracellular triglycerides, cholesteryl esters, and free cholesterols toward cellular dysfunction is specifically addressed. On this basis, therapies targeted to attenuate cellular lipid accumulation, to reduce risk factors for non-alcoholic fatty liver disease (NAFLD) (i.e., insulin resistance and oxidative stress) and to specifically inhibit intestinal MTP may be useful for ameliorating liver damage induced by MTP inhibitors. In particular, weight loss through lifestyle interventions is expected to be the most effective and safest way to minimize the undesirable side effects. Specific dietary supplementation might also have protective effects against hepatosteatosis. Despite that, to date, few clinical data support these therapeutic options in MTP inhibition-related liver damage, such proposed approaches may be further explored in the future for their use in preventing unwanted effects of MTP inhibitors.
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Abstract
Accumulation of triacylglycerols within the cytoplasm of hepatocytes to the degree that lipid droplets are visible microscopically is called liver steatosis. Most commonly, it occurs when there is an imbalance between the delivery or synthesis of fatty acids in the liver and their disposal through oxidative pathways or secretion into the blood as a component of triacylglycerols in very low density lipoprotein. This disorder is called nonalcoholic fatty liver disease (NAFLD) in the absence of alcoholic abuse and viral hepatitis, and it is often associated with insulin resistance, obesity and type 2 diabetes. Also, liver steatosis can be induced by many other causes including excessive alcohol consumption, infection with genotype 3 hepatitis C virus and certain medications. Whereas hepatic triacylglycerol accumulation was once considered the ultimate effector of hepatic lipotoxicity, triacylglycerols per se are quite inert and do not induce insulin resistance or cellular injury. Rather, lipotoxic injury in the liver appears to be mediated by the global ongoing fatty acid enrichment in the liver, paralleling the development of insulin resistance. A considerable number of fatty acid metabolites may be responsible for hepatic lipotoxicity and liver injury. Additional key contributors include hepatic cytosolic lipases and the "lipophagy" of lipid droplets, as sources of hepatic fatty acids. The specific origin of the lipids, mainly triacylglycerols, accumulating in liver has been unraveled by recent kinetic studies, and identifying the origin of the accumulated triacylglycerols in the liver of patients with NAFLD may direct the prevention and treatment of this condition.
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Affiliation(s)
- David Q-H Wang
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, Saint Louis University School of Medicine, St. Louis, Missouri
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Paland N, Gamliel-Lazarovich A, Coleman R, Fuhrman B. Urokinase-type plasminogen activator (uPA) stimulates triglyceride synthesis in Huh7 hepatoma cells via p38-dependent upregulation of DGAT2. Atherosclerosis 2014; 237:200-7. [PMID: 25244504 DOI: 10.1016/j.atherosclerosis.2014.09.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 08/28/2014] [Accepted: 09/01/2014] [Indexed: 01/22/2023]
Abstract
OBJECTIVE The liver is the central organ of fatty acid and triglyceride metabolism. Oxidation and synthesis of fatty acids and triglycerides is under the control of peroxisome-proliferator-activated receptors (PPAR) α. Impairment of these receptors' function contributes to the accumulation of triglycerides in the liver resulting in non-alcoholic fatty liver disease. Urokinase-type plasminogen activator (uPA) was shown to regulate gene expression in the liver involving PPARγ transcriptional activity. In this study we questioned whether uPA modulates triglyceride metabolism in the liver, and investigated the mechanisms involved in the observed processes. METHODS AND RESULTS Huh7 hepatoma cells were incubated with increasing concentrations of uPA for 24 h uPA dose-dependently increased the cellular triglyceride mass, and this effect resulted from increased de novo triglyceride synthesis mediated by the enzyme diglyceride acyltransferase 2 (DGAT2). Also, the amount of free fatty acids was highly up regulated by uPA through activation of the transcription factor SREBP-1. Chemical activation of PPARα further increased uPA-stimulated triglyceride synthesis, whereas inhibition of p38, an upstream activator of PPARα, completely abolished the stimulatory effect of uPA on both triglyceride synthesis and DGAT2 upregulation. The effect of uPA on triglyceride synthesis in Huh7 cells was mediated via binding to its receptor, the uPAR. In vivo studies in uPAR(-/-) mice demonstrated that no lipid droplets were observed in their livers compared to C57BL/6 mice and the triglyceride levels were significantly lower. CONCLUSION This study presents a new biological function of the uPA/uPAR system in the metabolism of triglycerides and might present a new target for an early therapeutic intervention for NAFLD.
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Affiliation(s)
- Nicole Paland
- The Lipid Research Laboratory, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | | | - Raymond Coleman
- Department of Anatomy and Cell Biology, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Bianca Fuhrman
- The Lipid Research Laboratory, Technion Faculty of Medicine and Rambam Health Care Campus, Haifa 31096, Israel.
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Perilipin-5 is regulated by statins and controls triglyceride contents in the hepatocyte. J Hepatol 2014; 61:358-65. [PMID: 24768901 PMCID: PMC4104237 DOI: 10.1016/j.jhep.2014.04.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 02/26/2014] [Accepted: 04/07/2014] [Indexed: 01/28/2023]
Abstract
BACKGROUND & AIMS Perilipin-5 (PLIN5) is a member of the perilipin family of lipid droplet (LD)-associated proteins. PLIN5 is expressed in oxidative tissues including the liver, and is critical during LD biogenesis. Studies showed that statins reduce hepatic triglyceride contents in some patients with non-alcoholic fatty liver disease and in rodent models of diet-induced hepatosteatosis. Whether statins alter triglyceride synthesis, storage, and/or utilization within the hepatocyte is unknown, though. Here we tested the hypothesis that statins alter the metabolism of LD in the hepatocyte during physiological conditions, such as fasting-induced steatosis. METHODS Mice were gavaged with saline or atorvastatin, and the expression of LD-associated genes was determined in fed and fasted animals. The accumulation of triglycerides and LD was studied in mouse or human primary hepatocytes in response to statins, and following knock-down of SREBP2 or PLIN5. RESULTS We show that statins decrease the levels of PLIN5, but not other LD-associated genes, in both mouse liver and mouse/human primary hepatocytes, which is paralleled by a significant reduction in both intracellular triglycerides and the number of LD. We identify an atypical negative sterol regulatory sequence in the proximal promoter of mouse/human PLIN5 that recruits the transcription factor SREBP2 and confers response to statins. Finally, we show that the statin-dependent reduction of hepatocyte triglyceride contents is mimicked by partial knock-down of PLIN5; conversely, ectopic overexpression of PLIN5 reverts the statin effect. CONCLUSIONS PLIN5 is a physiological regulator of triglyceride metabolism in the liver, and likely contributes to the pleiotropic effects of statins.
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Mattijssen F, Georgiadi A, Andasarie T, Szalowska E, Zota A, Krones-Herzig A, Heier C, Ratman D, De Bosscher K, Qi L, Zechner R, Herzig S, Kersten S. Hypoxia-inducible lipid droplet-associated (HILPDA) is a novel peroxisome proliferator-activated receptor (PPAR) target involved in hepatic triglyceride secretion. J Biol Chem 2014; 289:19279-93. [PMID: 24876382 DOI: 10.1074/jbc.m114.570044] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Peroxisome proliferator-activated receptors (PPARs) play major roles in the regulation of hepatic lipid metabolism through the control of numerous genes involved in processes such as lipid uptake and fatty acid oxidation. Here we identify hypoxia-inducible lipid droplet-associated (Hilpda/Hig2) as a novel PPAR target gene and demonstrate its involvement in hepatic lipid metabolism. Microarray analysis revealed that Hilpda is one of the most highly induced genes by the PPARα agonist Wy14643 in mouse precision cut liver slices. Induction of Hilpda mRNA by Wy14643 was confirmed in mouse and human hepatocytes. Oral dosing with Wy14643 similarly induced Hilpda mRNA levels in livers of wild-type mice but not Ppara(-/-) mice. Transactivation studies and chromatin immunoprecipitation showed that Hilpda is a direct PPARα target gene via a conserved PPAR response element located 1200 base pairs upstream of the transcription start site. Hepatic overexpression of HILPDA in mice via adeno-associated virus led to a 4-fold increase in liver triglyceride storage, without any changes in key genes involved in de novo lipogenesis, β-oxidation, or lipolysis. Moreover, intracellular lipase activity was not affected by HILPDA overexpression. Strikingly, HILPDA overexpression significantly impaired hepatic triglyceride secretion. Taken together, our data uncover HILPDA as a novel PPAR target that raises hepatic triglyceride storage via regulation of triglyceride secretion.
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Affiliation(s)
- Frits Mattijssen
- From the Nutrition, Metabolism, and Genomics Group, Division of Human Nutrition, Wageningen University, 6700 EV Wageningen, The Netherlands
| | - Anastasia Georgiadi
- From the Nutrition, Metabolism, and Genomics Group, Division of Human Nutrition, Wageningen University, 6700 EV Wageningen, The Netherlands
| | - Tresty Andasarie
- From the Nutrition, Metabolism, and Genomics Group, Division of Human Nutrition, Wageningen University, 6700 EV Wageningen, The Netherlands
| | - Ewa Szalowska
- the RIKILT-Institute of Food Safety, Wageningen University and Research Centre, 6700AE Wageningen, The Netherlands
| | - Annika Zota
- the Joint Division Molecular Metabolic Control, DKFZ-ZMBH Alliance, Network Aging Research, German Cancer Research Center (DKFZ) Heidelberg, Center for Molecular Biology (ZMBH), and University Hospital, Heidelberg University, 69120 Heidelberg, Germany
| | - Anja Krones-Herzig
- the Joint Division Molecular Metabolic Control, DKFZ-ZMBH Alliance, Network Aging Research, German Cancer Research Center (DKFZ) Heidelberg, Center for Molecular Biology (ZMBH), and University Hospital, Heidelberg University, 69120 Heidelberg, Germany
| | - Christoph Heier
- the Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Dariusz Ratman
- the Cytokine Receptor Laboratory, Nuclear Receptor Signaling Unit, Department of Medical Protein Research, Flanders Institute for Biotechnology, University of Ghent, Albert Baertsoenkaai 3, B-9000 Gent, Belgium, and
| | - Karolien De Bosscher
- the Cytokine Receptor Laboratory, Nuclear Receptor Signaling Unit, Department of Medical Protein Research, Flanders Institute for Biotechnology, University of Ghent, Albert Baertsoenkaai 3, B-9000 Gent, Belgium, and
| | - Ling Qi
- the Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853
| | - Rudolf Zechner
- the Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Stephan Herzig
- the Joint Division Molecular Metabolic Control, DKFZ-ZMBH Alliance, Network Aging Research, German Cancer Research Center (DKFZ) Heidelberg, Center for Molecular Biology (ZMBH), and University Hospital, Heidelberg University, 69120 Heidelberg, Germany
| | - Sander Kersten
- From the Nutrition, Metabolism, and Genomics Group, Division of Human Nutrition, Wageningen University, 6700 EV Wageningen, The Netherlands, the Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853
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Morris EM, Jackman MR, Meers GME, Johnson GC, Lopez JL, MacLean PS, Thyfault JP. Reduced hepatic mitochondrial respiration following acute high-fat diet is prevented by PGC-1α overexpression. Am J Physiol Gastrointest Liver Physiol 2013; 305:G868-80. [PMID: 24091599 PMCID: PMC3882433 DOI: 10.1152/ajpgi.00179.2013] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Changes in substrate utilization and reduced mitochondrial respiratory capacity following exposure to energy-dense, high-fat diets (HFD) are putatively key components in the development of obesity-related metabolic disease. We examined the effect of a 3-day HFD on isolated liver mitochondrial respiration and whole body energy utilization in obesity-prone (OP) rats. We also examined if hepatic overexpression of peroxisomal proliferator-activated receptor-γ coactivator-1α (PGC-1α), a master regulator of mitochondrial respiratory capacity and biogenesis, would modify liver and whole body responses to the HFD. Acute, 3-day HFD (45% kcal) in OP rats resulted in increased daily energy intake, energy balance, weight gain, and adiposity, without an increase in liver triglyceride (triacylglycerol) accumulation. HFD-fed OP rats also displayed decreased whole body substrate switching from the dark to the light cycle, which was paired with reductions in hepatic mitochondrial respiration of multiple substrates in multiple respiratory states. Hepatic PGC-1α overexpression was observed to protect whole body substrate switching, as well as maintain mitochondrial respiration, following the acute HFD. Additionally, liver PGC-1α overexpression did not alter whole body dietary fatty acid oxidation but resulted in greater storage of dietary free fatty acids in liver lipid, primarily as triacylglycerol. Together, these data demonstrate that a short-term HFD can result in a decrease in metabolic flexibility and hepatic mitochondrial respiratory capacity in OP rats that is completely prevented by hepatic overexpression of PGC-1α.
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Affiliation(s)
- E. Matthew Morris
- 1Department of Internal Medicine-Gastroenterology, University of Missouri, Columbia, Missouri;
| | - Matthew R. Jackman
- 4Center for Human Nutrition, University of Colorado Denver, Denver, Colorado; ,6Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Colorado Denver, Denver, Colorado
| | - Grace M. E. Meers
- 1Department of Internal Medicine-Gastroenterology, University of Missouri, Columbia, Missouri;
| | - Ginger C. Johnson
- 4Center for Human Nutrition, University of Colorado Denver, Denver, Colorado; ,6Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Colorado Denver, Denver, Colorado
| | - Jordan L. Lopez
- 4Center for Human Nutrition, University of Colorado Denver, Denver, Colorado; ,6Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Colorado Denver, Denver, Colorado
| | - Paul S. MacLean
- 4Center for Human Nutrition, University of Colorado Denver, Denver, Colorado; ,5Department of Physiology and Biophysics, University of Colorado Denver, Denver, Colorado; and ,6Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Colorado Denver, Denver, Colorado
| | - John P. Thyfault
- 1Department of Internal Medicine-Gastroenterology, University of Missouri, Columbia, Missouri; ,2Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri; ,3Research Service, Harry S. Truman Memorial Veterans Hospital, Columbia, Missouri;
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Wang Y, Zhang Y, Qian H, Lu J, Zhang Z, Min X, Lang M, Yang H, Wang N, Zhang P. The g0/g1 switch gene 2 is an important regulator of hepatic triglyceride metabolism. PLoS One 2013; 8:e72315. [PMID: 23951308 PMCID: PMC3741160 DOI: 10.1371/journal.pone.0072315] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Accepted: 07/10/2013] [Indexed: 02/06/2023] Open
Abstract
Nonalcoholic fatty liver disease is associated with obesity and insulin resistance. Factors that regulate the disposal of hepatic triglycerides contribute to the development of hepatic steatosis. G0/G1 switch gene 2 (G0S2) is a target of peroxisome proliferator-activated receptors and plays an important role in regulating lipolysis in adipocytes. Therefore, we investigated whether G0S2 plays a role in hepatic lipid metabolism. Adenovirus-mediated expression of G0S2 (Ad-G0S2) potently induced fatty liver in mice. The liver mass of Ad-G0S2-infected mice was markedly increased with excess triglyceride content compared to the control mice. G0S2 did not change cellular cholesterol levels in hepatocytes. G0S2 was found to be co-localized with adipose triglyceride lipase at the surface of lipid droplets. Hepatic G0S2 overexpression resulted in an increase in plasma Low-density lipoprotein (LDL)/Very-Low-density (VLDL) lipoprotein cholesterol level. Plasma High-density lipoprotein (HDL) cholesterol and ketone body levels were slightly decreased in Ad-G0S2 injected mice. G0S2 also increased the accumulation of neutral lipids in cultured HepG2 and L02 cells. However, G0S2 overexpression in the liver significantly improved glucose tolerance in mice. Livers expressing G0S2 exhibited increased 6-(N-(7-nitrobenz-2-oxa-1-3-diazol-4-yl) amino)-6-deoxyglucose uptake compared with livers transfected with control adenovirus. Taken together, our results provide evidence supporting an important role for G0S2 as a regulator of triglyceride content in the liver and suggest that G0S2 may be a molecular target for the treatment of insulin resistance and other obesity-related metabolic disorders.
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Affiliation(s)
- Yinfang Wang
- Cardiovascular Research Center, Hubei University of Medicine, Hubei, China
- Department of Physiology, Hubei University of Medicine, Hubei, China
| | - Yahui Zhang
- Department of Pathophysiology, Hubei University of Medicine, Hubei, China
| | - Hang Qian
- Cardiovascular Research Center, Hubei University of Medicine, Hubei, China
| | - Juan Lu
- Cardiovascular Research Center, Hubei University of Medicine, Hubei, China
- Department of Physiology, Hubei University of Medicine, Hubei, China
| | - Zhifeng Zhang
- Cardiovascular Research Center, Hubei University of Medicine, Hubei, China
- Department of Physiology, Hubei University of Medicine, Hubei, China
| | - Xinwen Min
- Cardiovascular Research Center, Hubei University of Medicine, Hubei, China
| | - Mingjian Lang
- Cardiovascular Research Center, Hubei University of Medicine, Hubei, China
| | - Handong Yang
- Cardiovascular Research Center, Hubei University of Medicine, Hubei, China
| | - Nanping Wang
- Cardiovascular Research Center, Xi’an Jiaotong University School of Medicine, Xi’an, China
| | - Peng Zhang
- Cardiovascular Research Center, Hubei University of Medicine, Hubei, China
- Department of Physiology, Hubei University of Medicine, Hubei, China
- * E-mail:
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Involvement of lipid droplets in hepatic responses to lipopolysaccharide treatment in mice. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1831:1357-67. [DOI: 10.1016/j.bbalip.2013.04.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Revised: 04/05/2013] [Accepted: 04/30/2013] [Indexed: 01/07/2023]
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Nose F, Yamaguchi T, Kato R, Aiuchi T, Obama T, Hara S, Yamamoto M, Itabe H. Crucial role of perilipin-3 (TIP47) in formation of lipid droplets and PGE2 production in HL-60-derived neutrophils. PLoS One 2013; 8:e71542. [PMID: 23936516 PMCID: PMC3731282 DOI: 10.1371/journal.pone.0071542] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2013] [Accepted: 06/29/2013] [Indexed: 11/18/2022] Open
Abstract
Cytosolic lipid droplets (LDs), which are now recognized as multifunctional organelles, accumulate in leukocytes under various inflammatory conditions. However, little is known about the characteristic features of LDs in neutrophils. In this study, we show that perilipin-3 (PLIN3; formerly called TIP47) is involved in LD formation and the inflammatory response in HL-60-derived neutrophils. HL-60, a promyelocytic cell line, was differentiated into neutrophils via treatment with all-trans retinoic acid. After differentiation, cells were stimulated with Porphyromonas gingivalis lipopolysaccharide (P.g-LPS), a major pathogen in adult periodontitis. When HL-60-derived neutrophils were stimulated with P.g-LPS, LDs increased in both number and size. In the differentiated cells, PLIN3 was induced while PLIN1, PLIN2 and PLIN5 were not detected. PGE2 production and the PLIN3 protein level were increased by the P.g-LPS treatment of the cells in a dose-dependent manner. When PLIN3 was down-regulated with siRNA treatment, LDs essentially disappeared and the level of PGE2 secreted in the cell culture medium decreased by 65%. In addition, the suppression of PLIN3 repressed the PGE2 producing enzymes; i.e., microsomal PGE synthase-1, -2 and cyclooxygenase-2. These findings indicate that PLIN3 has a pivotal role in LD-biogenesis in HL-60-derived neutrophils, and that PLIN3 is associated with the synthesis and secretion of PGE2.
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Affiliation(s)
- Fuyuki Nose
- Department of Periodontology, Showa University School of Dentistry, Tokyo, Japan
- Division of Biological Chemistry, Department of Molecular Biology, Showa University School of Pharmacy, Tokyo, Japan
| | - Tomohiro Yamaguchi
- Division of Biological Chemistry, Department of Molecular Biology, Showa University School of Pharmacy, Tokyo, Japan
| | - Rina Kato
- Division of Biological Chemistry, Department of Molecular Biology, Showa University School of Pharmacy, Tokyo, Japan
| | - Toshihiro Aiuchi
- Division of Biological Chemistry, Department of Molecular Biology, Showa University School of Pharmacy, Tokyo, Japan
| | - Takashi Obama
- Division of Biological Chemistry, Department of Molecular Biology, Showa University School of Pharmacy, Tokyo, Japan
| | - Shuntaro Hara
- Division of Health Chemistry, Department of Healthcare and Regulatory Sciences, Showa University School of Pharmacy, Tokyo, Japan
| | - Matsuo Yamamoto
- Department of Periodontology, Showa University School of Dentistry, Tokyo, Japan
| | - Hiroyuki Itabe
- Division of Biological Chemistry, Department of Molecular Biology, Showa University School of Pharmacy, Tokyo, Japan
- * E-mail:
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Abstract
Though the pharmaceutical industry's infatuation with the therapeutic potential of RNA interference (RNAi) technology has finally come down from its initial lofty levels,[1] hope is by no means lost for the once-burgeoning enterprise, as recent clinical trials are beginning to show efficacy in areas ranging from amyloidosis to hypercholesterolemia to muscular dystrophy. With such resurgence comes a more informed perspective on the needs of such therapeutics: a renewed focus on true RNA drug development, and a desire for enhanced site-specific delivery.[2] In this review, we will discuss the latter with regard to hepatic targeting by synthetic vectors, covering the implications of organ and cellular physiology on conjugate structure, particle morphology, and active targeting. In presenting efficacy in a variety of disease models, we emphasize as well the extraordinary degree to which synthetic formulation improves upon and coordinates efforts with oligonucleotide development. Such advances in the understanding of and the technology behind RNAi have the potential to finally stabilize the long-term prospects RNA therapeutic development.
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Bjursell M, Wedin M, Admyre T, Hermansson M, Böttcher G, Göransson M, Lindén D, Bamberg K, Oscarsson J, Bohlooly-Y M. Ageing Fxr deficient mice develop increased energy expenditure, improved glucose control and liver damage resembling NASH. PLoS One 2013; 8:e64721. [PMID: 23700488 PMCID: PMC3659114 DOI: 10.1371/journal.pone.0064721] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 04/17/2013] [Indexed: 12/17/2022] Open
Abstract
Nuclear receptor subfamily 1, group H, member 4 (Nr1h4, FXR) is a bile acid activated nuclear receptor mainly expressed in the liver, intestine, kidney and adrenal glands. Upon activation, the primary function is to suppress cholesterol 7 alpha-hydroxylase (Cyp7a1), the rate-limiting enzyme in the classic or neutral bile acid synthesis pathway. In the present study, a novel Fxr deficient mouse line was created and studied with respect to metabolism and liver function in ageing mice fed chow diet. The Fxr deficient mice were similar to wild type mice in terms of body weight, body composition, energy intake and expenditure as well as behaviours at a young age. However, from 15 weeks of age and onwards, the Fxr deficient mice had almost no body weight increase up to 39 weeks of age mainly because of lower body fat mass. The lower body weight gain was associated with increased energy expenditure that was not compensated by increased food intake. Fasting levels of glucose and insulin were lower and glucose tolerance was improved in old and lean Fxr deficient mice. However, the Fxr deficient mice displayed significantly increased liver weight, steatosis, hepatocyte ballooning degeneration and lobular inflammation together with elevated plasma levels of ALT, bilirubin and bile acids, findings compatible with non-alcoholic steatohepatitis (NASH) and cholestasis. In conclusion, ageing Fxr deficient mice display late onset leanness associated with elevated energy expenditure and improved glucose control but develop severe NASH-like liver pathology.
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Bindesbøll C, Berg O, Arntsen B, Nebb HI, Dalen KT. Fatty acids regulate perilipin5 in muscle by activating PPARδ. J Lipid Res 2013; 54:1949-63. [PMID: 23606724 DOI: 10.1194/jlr.m038992] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The surface of lipid droplets (LDs) in various cell types is coated with perilipin proteins encoded by the Plin genes. Perilipins regulate LD metabolism by selectively recruiting lipases and other proteins to LDs. We have studied the expression of perilipins in mouse muscle. The glycolytic fiber-enriched gastrocnemius muscle expresses predominantly Plin2-4. The oxidative fiber-enriched soleus muscle expresses Plin2-5. Expression of Plin2 and Plin4-5 is elevated in gastrocnemius and soleus muscles from mice fed a high-fat diet. This effect is preserved in peroxisome proliferator-activated receptor (PPAR)α-deficient mice. Mouse muscle derived C2C12 cells differentiated into glycolytic fibers increase transcription of these Plins when exposed to various long chain fatty acids (FAs). To understand how FAs regulate Plin genes, we used specific activators and antagonists against PPARs, Plin promoter reporter assays, chromatin immunoprecipitation, siRNA, and animal models. Our analyses demonstrate that FAs require PPARδ to induce transcription of Plin4 and Plin5. We further identify a functional PPAR binding site in the Plin5 gene and establish Plin5 as a novel direct PPARδ target in muscle. Our study reveals that muscle cells respond to elevated FAs by increasing transcription of several perilipin LD-coating proteins. This induction renders the muscle better equipped to sequester incoming FAs into cytosolic LDs.
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Affiliation(s)
- Christian Bindesbøll
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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Galzio R, Cristiano L, Fidoamore A, Cifone MG, Benedetti E, Cinque B, Menghini P, Raysi Dehcordi S, Ippoliti R, Giordano A, Cimini A. Hypoxia modulation of peroxisome proliferator-activated receptors (PPARs) in human glioblastoma stem cells. Implications for therapy. J Cell Biochem 2013; 113:3342-52. [PMID: 22644833 DOI: 10.1002/jcb.24210] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Gliobastoma (GB), the most common adult brain tumor, infiltrates normal brain area rendering impossible the complete surgical resection, resulting in a poor median survival (14-15 months), despite the aggressive multimodality treatments post-surgery, such as radiation and chemo-therapy. GB is characterized by hypoxic and necrotic regions due to a poorly organized tumor vascularization, leading to inadequate blood supply and consequently to hypoxic and necrotic areas. We have previously shown that, under hypoxia GB primary cells increased the expression of stemness markers as well as the expression of the nuclear receptor peroxisome proliferator-activated receptor α (PPARα) and also the crucial role played by PPARs in mouse neural stem cells maintenance and differentiation. Due to the importance of lipid signaling in cell proliferation and differentiation, in this work, we analyzed the expression of PPARs in GB neurospheres both in normoxic and hypoxic conditions. The results obtained suggest a differential regulation of the three PPARs by hypoxia, thus indicating a possible therapeutic strategy to counteract GB recurrencies.
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Affiliation(s)
- Renato Galzio
- Department of Health Sciences, University of L'Aquila, L'Aquila, Italy
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Murphy DJ. The dynamic roles of intracellular lipid droplets: from archaea to mammals. PROTOPLASMA 2012; 249:541-85. [PMID: 22002710 DOI: 10.1007/s00709-011-0329-7] [Citation(s) in RCA: 170] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Accepted: 09/28/2011] [Indexed: 05/02/2023]
Abstract
During the past decade, there has been a paradigm shift in our understanding of the roles of intracellular lipid droplets (LDs). New genetic, biochemical and imaging technologies have underpinned these advances, which are revealing much new information about these dynamic organelles. This review takes a comparative approach by examining recent work on LDs across the whole range of biological organisms from archaea and bacteria, through yeast and Drosophila to mammals, including humans. LDs probably evolved originally in microorganisms as temporary stores of excess dietary lipid that was surplus to the immediate requirements of membrane formation/turnover. LDs then acquired roles as long-term carbon stores that enabled organisms to survive episodic lack of nutrients. In multicellular organisms, LDs went on to acquire numerous additional roles including cell- and organism-level lipid homeostasis, protein sequestration, membrane trafficking and signalling. Many pathogens of plants and animals subvert their host LD metabolism as part of their infection process. Finally, malfunctions in LDs and associated proteins are implicated in several degenerative diseases of modern humans, among the most serious of which is the increasingly prevalent constellation of pathologies, such as obesity and insulin resistance, which is associated with metabolic syndrome.
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Affiliation(s)
- Denis J Murphy
- Division of Biological Sciences, University of Glamorgan, Cardiff, CF37 4AT, UK.
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Kovacs WJ, Charles KN, Walter KM, Shackelford JE, Wikander TM, Richards MJ, Fliesler SJ, Krisans SK, Faust PL. Peroxisome deficiency-induced ER stress and SREBP-2 pathway activation in the liver of newborn PEX2 knock-out mice. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1821:895-907. [PMID: 22441164 DOI: 10.1016/j.bbalip.2012.02.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Revised: 01/20/2012] [Accepted: 02/29/2012] [Indexed: 12/26/2022]
Abstract
Disruption of the Pex2 gene leads to peroxisome deficiency and widespread metabolic dysfunction. We previously demonstrated that peroxisomes are critical for maintaining cholesterol homeostasis, using peroxisome-deficient Pex2(-/-) mice on a hybrid Swiss Webster×129S6/SvEv (SW/129) genetic background. Peroxisome deficiency activates hepatic endoplasmic reticulum (ER) stress pathways, leading to dysregulation of the endogenous sterol response mechanism. Herein, we demonstrate a more profound dysregulation of cholesterol homeostasis in newborn Pex2(-/-) mice congenic on a 129S6/SvEv (129) genetic background, and substantial differences between newborn versus postnatal Pex2(-/-) mice in factors that activate ER stress. These differences extend to relationships between activation of genes regulated by SREBP-2 versus PPARα. The SREBP-2 pathway is induced in neonatal Pex2(-/-) livers from 129 and SW/129 strains, despite normal hepatic cholesterol levels. ER stress markers are increased in newborn 129 Pex2(-/-) livers, which occurs in the absence of hepatic steatosis or accumulation of peroxins in the ER. Moreover, the induction of SREBP-2 and ER stress pathways is independent of PPARα activation in livers of newborn 129 and SW/129 Pex2(-/-) mice. Two-week-old wild-type mice treated with the peroxisome proliferator WY-14,643 show strong induction of PPARα-regulated genes and decreased expression of SREBP-2 and its target genes, further demonstrating that SREBP-2 pathway induction is not dependent on PPARα activation. Lastly, there is no activation of either SREBP-2 or ER stress pathways in kidney and lung of newborn Pex2(-/-) mice, suggesting a parallel induction of these pathways in peroxisome-deficient mice. These findings establish novel associations between SREBP-2, ER stress and PPARα pathway inductions.
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Affiliation(s)
- Werner J Kovacs
- Institute of Cell Biology, ETH Zuerich, CH-8093 Zuerich, Switzerland.
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Greenberg AS, Coleman RA, Kraemer FB, McManaman JL, Obin MS, Puri V, Yan QW, Miyoshi H, Mashek DG. The role of lipid droplets in metabolic disease in rodents and humans. J Clin Invest 2011; 121:2102-10. [PMID: 21633178 DOI: 10.1172/jci46069] [Citation(s) in RCA: 475] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Lipid droplets (LDs) are intracellular organelles that store neutral lipids within cells. Over the last two decades there has been a dramatic growth in our understanding of LD biology and, in parallel, our understanding of the role of LDs in health and disease. In its simplest form, the LD regulates the storage and hydrolysis of neutral lipids, including triacylglycerol and/or cholesterol esters. It is becoming increasingly evident that alterations in the regulation of LD physiology and metabolism influence the risk of developing metabolic diseases such as diabetes. In this review we provide an update on the role of LD-associated proteins and LDs in metabolic disease.
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Affiliation(s)
- Andrew S Greenberg
- Obesity and Metabolism Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts 02111, USA.
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Chu JH, Wang H, Ye Y, Chan PK, Pan SY, Fong WF, Yu ZL. Inhibitory effect of schisandrin B on free fatty acid-induced steatosis in L-02 cells. World J Gastroenterol 2011; 17:2379-88. [PMID: 21633637 PMCID: PMC3103790 DOI: 10.3748/wjg.v17.i19.2379] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 08/13/2010] [Accepted: 08/20/2010] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the effects of schisandrin B (Sch B) on free fatty acid (FFA)-induced steatosis in L-02 cells.
METHODS: Cellular steatosis was induced by incubating L-02 cells with a FFA mixture (oleate and palmitate at the ratio of 2:1) for 24 h. Cytotoxicity and apoptosis were evaluated by 3-(4, 5-dmethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide assay and Annexin V/propidium iodide staining, respectively. Cellular total lipid was determined using a photocolorimetric method after Nile red staining, and triglyceride content was measured using an enzymatic kit. To study the effects of Sch B on steatosis, L-02 cells were treated with Sch B (1-100 μmol/L) in the absence or presence of 1 mmol/L FFA for 24 h, and cellular total lipid and triglyceride levels were measured. To explore the mechanisms of action of Sch B in the steatotic L-02 cells, mRNA levels of several regulators of hepatic lipid metabolism including adipose differentiation related protein (ADRP), sterol regulatory element binding protein 1 (SREBP-1), peroxisome proliferator-activated receptor (PPAR)-α and PPAR-γ were measured by quantitative real-time polymerase chain reaction (PCR), and protein levels of ADRP and SREBP-1 were measured by immunoblotting.
RESULTS: Treatment with 1 mmol/L FFA for 24 h induced intracellular lipid accumulation in L-02 cells comparable to that in human steatotic livers without causing apparent apoptosis and cytotoxicity. Sch B mitigated cellular total lipid and triglyceride accumulations in the steatotic L-02 cells in a dose-dependent manner. Quantitative real-time PCR and Western blot analyses revealed that treatment of L-02 cells with 100 μmol/L Sch B reverted the FFA-stimulated up-regulation of ADRP and SREBP-1.
CONCLUSION: Sch B inhibits FFA-induced steatosis in L-02 cells by, at least in part, reversing the up-regulation of ADRP and SREBP-1.
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Pan Z, Wang J, Kang B, Lu L, Han C, Tang H, Li L, Xu F, Zhou Z, Lv J. Screening and identification of differentially expressed genes in goose hepatocytes exposed to free fatty acid. J Cell Biochem 2011; 111:1482-92. [PMID: 20872794 DOI: 10.1002/jcb.22878] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The overaccumulation of triglycerides in hepatocytes induces hepatic steatosis; however, little is known about the mechanism of goose hepatic steatosis. The aim of this study was to define an experimental model of hepatocellular steatosis with TG overaccumulation and minimal cytotoxicity, using a mixture of various proportions of oleate and palmitate free fatty acids (FFAs) to induce fat-overloading, then using suppressive subtractive hybridization and a quantitative PCR approach to identify genes with higher or lower expression levels after the treatment of cells with FFA mixtures. Overall, 502 differentially expressed clones, representing 21 novel genes and 87 known genes, were detected by SSH. Based on functional clustering, up- and down-regulated genes were mostly related to carbohydrate and lipid metabolism, enzyme activity and signal transduction. The expression of 20 selected clones involved with carbohydrate and lipid metabolism pathways was further studied by quantitative PCR. The data indicated that six clones similar to the genes ChREBP, FoxO1, apoB, IHPK2, KIF1B, and FSP27, which participate in de novo synthesis of fatty acid and secretion of very low density lipoproteins, had significantly lower expression levels in the hepatocytes treated with FFA mixtures. Meanwhile, 13 clones similar to the genes DGAT-1, ACSL1, DHRS7, PPARα, L-FABP, DGAT-2, PCK, ACSL3, CPT-1, A-FABP, PPARβ, MAT, and ALDOB had significantly higher expression levels in the hepatocytes treated with FFA mixtures. These results suggest that several metabolic pathways are altered in goose hepatocytes, which may be useful for further research into the molecular mechanism of goose hepatic steatosis.
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Affiliation(s)
- Zhixiong Pan
- Key Laboratory of Animal Genetic Resources, College of Animal Science and Technology, Sichuan Agricultural University, Ya'an, Sichuan 625014, PR China
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Uchida A, Slipchenko MN, Cheng JX, Buhman KK. Fenofibrate, a peroxisome proliferator-activated receptor α agonist, alters triglyceride metabolism in enterocytes of mice. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1811:170-6. [PMID: 21215818 DOI: 10.1016/j.bbalip.2010.12.011] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Revised: 12/17/2010] [Accepted: 12/21/2010] [Indexed: 11/17/2022]
Abstract
Fenofibrate, a drug in the fibrate class of amphiphathic carboxylic acids, has multiple blood lipid modifying actions, which are beneficial to the prevention of atherosclerosis. One of its benefits is in lowering fasting and postprandial blood triglyceride (TG) concentrations. The goal of this study was to determine whether the hypotriglyceridemic actions of fenofibrate in the postprandial state include alterations in TG and fatty acid metabolism in the small intestine. We found that the hypotriglyceridemic actions of fenofibrate in the postprandial state of high-fat (HF) fed mice include a decrease in supply of TG for secretion by the small intestine. A decreased supply of TG for secretion was due in part to the decreased dietary fat absorption and increased intestinal fatty acid oxidation in fenofibrate compared to vehicle treated HF fed mice. These results suggest that the effects of fenofibrate on the small intestine play a critical role in the hypotriglyceridemic effects of fenofibrate.
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Affiliation(s)
- Aki Uchida
- Department of Foods and Nutrition, Purdue University, West Lafayette, IN 47907, USA
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47
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Abstract
OBJECTIVE Toll-like receptor 4 (TLR4) has been reported to induce insulin resistance through inflammation in high-fat-fed mice. However, the physiological role of TLR4 in metabolism is unknown. Here, we investigated the involvement of TLR4 in fasting metabolism. RESEARCH DESIGN AND METHODS Wild-type and TLR4 deficient (TLR4(-/-)) mice were either fed or fasted for 24 h. Glucose and lipid levels in circulation and tissues were measured. Glucose and lipid metabolism in tissues, as well as the expression of related enzymes, was examined. RESULTS Mice lacking TLR4 displayed aggravated fasting hypoglycemia, along with normal hepatic gluconeogenesis, but reversed activity of pyruvate dehydrogenase complex (PDC) in skeletal muscle, which might account for the fasting hypoglycemia. TLR4(-/-) mice also exhibited higher lipid levels in circulation and skeletal muscle after fasting and reversed expression of lipogenic enzymes in skeletal muscle but not liver and adipose tissue. Adipose tissue lipolysis is normal and muscle fatty acid oxidation is increased in TLR4(-/-) mice after fasting. Inhibition of fatty acid synthesis in TLR4(-/-) mice abolished hyperlipidemia, hypoglycemia, and PDC activity increase, suggesting that TLR4-dependent inhibition of muscle lipogenesis may contribute to glucose and lipid homeostasis during fasting. Further studies showed that TLR4 deficiency had no effect on insulin signaling and muscle proinflammatory cytokine production in response to fasting. CONCLUSIONS These data suggest that TLR4 plays a critical role in glucose and lipid metabolism independent of insulin during fasting and identify a novel physiological role for TLR4 in fuel homeostasis.
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Affiliation(s)
- Shanshan Pang
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China; and the Graduate School of Chinese Academy of Sciences, Shanghai, China
| | - Haiqing Tang
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China; and the Graduate School of Chinese Academy of Sciences, Shanghai, China
| | - Shu Zhuo
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China; and the Graduate School of Chinese Academy of Sciences, Shanghai, China
| | - Ying Qin Zang
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China; and the Graduate School of Chinese Academy of Sciences, Shanghai, China
- Corresponding author: Yingying Le, , or Ying Qin Zang,
| | - Yingying Le
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China; and the Graduate School of Chinese Academy of Sciences, Shanghai, China
- Corresponding author: Yingying Le, , or Ying Qin Zang,
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Kim MJ, Wainwright HC, Locketz M, Bekker LG, Walther GB, Dittrich C, Visser A, Wang W, Hsu FF, Wiehart U, Tsenova L, Kaplan G, Russell DG. Caseation of human tuberculosis granulomas correlates with elevated host lipid metabolism. EMBO Mol Med 2010; 2:258-74. [PMID: 20597103 PMCID: PMC2913288 DOI: 10.1002/emmm.201000079] [Citation(s) in RCA: 336] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The progression of human tuberculosis (TB) to active disease and transmission involves the development of a caseous granuloma that cavitates and releases infectious Mycobacterium tuberculosis bacilli. In the current study, we exploited genome-wide microarray analysis to determine that genes for lipid sequestration and metabolism were highly expressed in caseous TB granulomas. Immunohistological analysis of these granulomas confirmed the disproportionate abundance of the proteins involved in lipid metabolism in cells surrounding the caseum; namely, adipophilin, acyl-CoA synthetase long-chain family member 1 and saposin C. Biochemical analysis of the lipid species within the caseum identified cholesterol, cholesteryl esters, triacylglycerols and lactosylceramide, which implicated low-density lipoprotein-derived lipids as the most likely source. M. tuberculosis infection in vitro induced lipid droplet formation in murine and human macrophages. Furthermore, the M. tuberculosis cell wall lipid, trehalose dimycolate, induced a strong granulomatous response in mice, which was accompanied by foam cell formation. These results provide molecular and biochemical evidence that the development of the human TB granuloma to caseation correlates with pathogen-mediated dysregulation of host lipid metabolism.
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Affiliation(s)
- Mi-Jeong Kim
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA
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Abnormal hepatic apolipoprotein B metabolism in type 2 diabetes. Atherosclerosis 2010; 211:353-60. [DOI: 10.1016/j.atherosclerosis.2010.01.028] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Revised: 01/20/2010] [Accepted: 01/21/2010] [Indexed: 11/24/2022]
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Takahashi K, Sasabe N, Ohshima K, Kitazato K, Kato R, Masuda Y, Tsurumaki M, Obama T, Okudaira SI, Aoki J, Arai H, Yamaguchi T, Itabe H. Glucagon regulates intracellular distribution of adipose differentiation-related protein during triacylglycerol accumulation in the liver. J Lipid Res 2010; 51:2571-80. [PMID: 20529882 DOI: 10.1194/jlr.m004648] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cellular lipid droplets (LD) are organelles involved in cellular lipid metabolism. When liver cellular components were fractionated using sucrose density gradient centrifugation, adipose differentiation-related protein (ADRP) was distributed in both the top and bottom fractions, which correspond to the LD and membranous fractions, respectively, in the mouse liver under normal feeding conditions. After overnight fasting, triacylglycerol and ADRP increased nearly 2.5-fold in the mouse liver, and a portion appeared in the intermediate-density LD (iLD) fractions. ADRP in the iLD fractions was also increased in a mouse nonalcoholic steatohepatitis model induced by methione/choline-deficient diet. When HuH-7 human hepatoma cells were incubated with oleic acid for 24 h, the amount of ADRP increased, and it was distributed in both the LD and membrane fractions. However, ADRP appeared in the iLD fractions upon treatment of HuH-7 cells with glucagon. This behavior of ADRP was cAMP-dependent, as the ADRP-positive iLD fractions were induced by dibutylyl cAMP and were blocked by protein kinase A inhibitors. A portion of ADRP colocalized microscopically with calnexin, which is present in the iLD fractions, by treatment of HuH-7 cells or human primary hepatocytes with oleic acid and glucagon, but not by treatment with oleic acid alone. Glucagon has a role in the reorganization of endoplasmic reticulum membranes to generate ADRP-associated lipid-poor particles in hepatic cells, which is related to LD formation during lipid storage.
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Affiliation(s)
- Katsuhiko Takahashi
- Department of Biological Chemistry, School of Pharmacy, Showa University, Tokyo, Japan
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