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LSDP5 enhances triglyceride storage in hepatocytes by influencing lipolysis and fatty acid β-oxidation of lipid droplets. PLoS One 2012; 7:e36712. [PMID: 22675471 PMCID: PMC3365886 DOI: 10.1371/journal.pone.0036712] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 04/09/2012] [Indexed: 12/25/2022] Open
Abstract
Lipid storage droplet protein 5 (LSDP5) is a lipid droplet-associated protein of the PAT (perilipin, adipophilin, and TIP47) family that is expressed in the liver in a peroxisome proliferator-activated receptor alpha (PPARα)-dependent manner; however, its exact function has not been elucidated. We noticed that LSDP5 was localized to the surface of lipid droplets in hepatocytes. Overexpression of LSDP5 enhanced lipid accumulation in the hepatic cell line AML12 and in primary hepatocytes. Knock-down of LSDP5 significantly decreased the triglyceride content of lipid droplets, stimulated lipolysis, and modestly increased the mitochondrial content and level of fatty-acid β-oxidation in the mitochondria. The expression of PPARα was increased in LSDP5-deficient cells and required for the increase in the level of fatty acid β-oxidation in LSDP5-deficient cells. Using serial deletions of LSDP5, we determined that the lipid droplet-targeting domain and the domain directing lipid droplet clustering overlapped and were localized to the 188 amino acid residues at the N-terminus of LSDP5. Our findings suggest that LSDP5, a novel lipid droplet protein, may contribute to triglyceride accumulation by negatively regulating lipolysis and fatty acid oxidation in hepatocytes.
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102
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Abstract
PURPOSE OF REVIEW Cyclic-AMP-responsive-element-binding protein H (CREB-H) is a transcription factor that is highly and selectively expressed in liver and small intestine. Here I summarize recent findings on the role of CREB-H in lipid metabolism. RECENT FINDINGS Recent studies have demonstrated that hepatic CREB-H is transcriptionally activated by fasting, and induces lipid metabolism genes, such as Apoa4, Apoa5, and Apoc2 apolipoproteins which exhibit stimulatory effects on lipoprotein lipase (LPL). Consistent with the essential role of LPL in triglyceride clearance, CREB-H-deficient mice showed hypertriglyceridemia, associated with defective production of these apolipoproteins and decreased LPL activity. DNA sequencing of the CREB3L3 gene (encoding CREB-H) identified multiple nonsynonymous mutations in CREB3L3 in individuals with extreme hypertriglyceridemia. SUMMARY Recent studies uncover a novel function of CREB-H in the regulation of triglyceride metabolism in rodents and humans. In liver and small intestine, CREB-H induces LPL coactivators, Apoa4, Apoa5, and Apoc2 that facilitate triglyceride clearance from plasma.
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Affiliation(s)
- Ann-Hwee Lee
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, USA.
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103
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Madsen M, Krusenstjerna-Hafstrøm T, Møller L, Christensen B, Vendelbo MH, Pedersen SB, Frystyk J, Jessen N, Hansen TK, Stødkilde-Jørgensen H, Flyvbjerg A, Jørgensen JOL. Fat content in liver and skeletal muscle changes in a reciprocal manner in patients with acromegaly during combination therapy with a somatostatin analog and a GH receptor antagonist: a randomized clinical trial. J Clin Endocrinol Metab 2012; 97:1227-35. [PMID: 22298804 DOI: 10.1210/jc.2011-2681] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
CONTEXT Pegvisomant is a GH antagonist, which is used for the treatment of acromegalic patients. It effectively blocks the hepatic and peripheral effects of GH, but transient elevations in circulating liver enzymes of unknown pathogenesis may occur, which seems to be more prevalent when the treatment is combined with a somatostatin analog (SA). Accumulation of intrahepatic lipid is a known cause of elevated liver enzymes, and there is evidence to suggest that GH impacts lipid content in liver and skeletal muscle. OBJECTIVE Our objective was to measure lipid content in liver and skeletal muscle in acromegalic patients before and after cotreatment with pegvisomant and SA as compared with SA monotherapy. DESIGN Eighteen acromegalic patients well controlled on SA monotherapy were randomized in a parallel study over 24 wk to 1) unchanged SA monotherapy, or 2) cotreatment with pegvisomant (15-30 mg twice a week) and SA (half the usual dosage). SETTING This was an investigator-initiated study in a single tertiary referral center. MAIN OUTCOME MEASURES Intrahepatic lipid (IHL) and intramyocellular lipid (IMCL) was assessed by ¹H magnetic resonance spectroscopy. RESULTS IHL increased in the cotreatment group compared with SA only (P = 0.002). The increase was positively correlated to weekly pegvisomant dose (r² = 0.52; P = 0.01). By contrast, IMCL decreased in the cotreatment group compared with SA only (P = 0.01). These changes related neither to insulin sensitivity nor inflammatory markers. CONCLUSION Cotreatment with pegvisomant and a reduced SA dose increase IHL and decrease IMCL compared with SA monotherapy. The clinical implications remain unclear, but increased IHL may be causally linked to the transient elevations in liver enzymes observed during pegvisomant treatment.
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Affiliation(s)
- Michael Madsen
- Department of Internal Medicine and Endocriniology (MEA), Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus C, Denmark.
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104
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Yuan Y, Li P, Ye J. Lipid homeostasis and the formation of macrophage-derived foam cells in atherosclerosis. Protein Cell 2012; 3:173-81. [PMID: 22447659 DOI: 10.1007/s13238-012-2025-6] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2011] [Accepted: 02/04/2012] [Indexed: 01/18/2023] Open
Abstract
Atherosclerosis is a chronic, inflammatory disorder characterized by the deposition of excess lipids in the arterial intima. The formation of macrophage-derived foam cells in a plaque is a hallmark of the development of atherosclerosis. Lipid homeostasis, especially cholesterol homeostasis, plays a crucial role during the formation of foam cells. Recently, lipid droplet-associated proteins, including PAT and CIDE family proteins, have been shown to control the development of atherosclerosis by regulating the formation, growth, stabilization and functions of lipid droplets in macrophage-derived foam cells. This review focuses on the potential mechanisms of formation of macrophage-derived foam cells in atherosclerosis with particular emphasis on the role of lipid homeostasis and lipid droplet-associated proteins. Understanding the process of foam cell formation will aid in the future discovery of novel therapeutic interventions for atherosclerosis.
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Affiliation(s)
- Yuan Yuan
- Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, China
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105
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Li H, Song Y, Zhang LJ, Li FF, Gu Y, Zhang J, Dong WP, Xue L, Zhang LY, Liu F, Wang J, Jiang LN, Ye J, Li Q. Cell death-inducing DFF45-like effector b (Cideb) is present in pancreatic beta-cells and involved in palmitate induced beta-cell apoptosis. Diabetes Metab Res Rev 2012; 28:145-55. [PMID: 21948526 DOI: 10.1002/dmrr.1295] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND Excessive accumulation of long-chain fatty acids in the pancreatic islets is associated with beta cell dysfunction and ultimately contributes to the pathogenesis of type 2 diabetes. It has been well proved that the cell death-inducing DFF45-like effector b (Cideb) is involved in cell apoptosis and lipid metabolism. However, the expression and function of Cideb in endocrine pancreas remain to be investigated. METHODS By using reverse transcript polymerase chain reaction, immunohistochemistry and Western blot, we observed the expression of Cideb in pancreas tissues and clonal beta-cell lines. The physiological role of Cideb was examined under the free fatty acid (FFA) administration and Cideb ribonucleic acid interference, and further analysis on apoptosis was measured by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling assay and caspase-3 activity. Nile red staining and quantitative evaluation of triglyceride were used to detect the lipid accumulation. The changes in esterification of FFA were traced by radiolabelled palmitate. RESULTS Cideb was abundantly expressed in pancreas and mainly localized in beta cells. FFAs, especially palmitate, induced an obvious increase of Cideb expression in beta cell lines. Adenoviral-mediated overexpression of Cideb increased the apoptosis, whereas ribonucleic acid interference-based Cideb depletion in beta-TC3 cells had no effect on apoptosis in normal condition. Palmitate supplementation led to beta cell lipoapoptosis, and Cideb silencing exacerbated the apoptosis induced by palmitate, reduced intracellular triglyceride content and aggravated FFA overload in beta cells. CONCLUSIONS The present results suggest that increased Cideb expression upon palmitate exposure may be involved in beta cell lipoapoptosis through its influence on conversion of FFAs to lipid esters in lipid droplets.
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Affiliation(s)
- H Li
- State Key Laboratory of Cancer Biology and Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi'an, China
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106
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Decreased proteasomal activity causes age-related phenotypes and promotes the development of metabolic abnormalities. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 180:963-972. [PMID: 22210478 DOI: 10.1016/j.ajpath.2011.11.012] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 10/14/2011] [Accepted: 11/04/2011] [Indexed: 11/21/2022]
Abstract
The proteasome is a multicatalytic enzyme complex responsible for the degradation of both normal and damaged proteins. An age-related decline in proteasomal activity has been implicated in various age-related pathologies. The relevance of decreased proteasomal activity to aging and age-related diseases remains unclear, however, because suitable animal models are not available. In the present study, we established a transgenic (Tg) mouse model with decreased proteasomal chymotrypsin-like activity. Tg mice exhibited a shortened life span and developed age-related phenotypes. In Tg mice, polyubiquitinated and oxidized proteins accumulated, and the expression levels of cellular proteins such as Bcl-xL and RNase L were altered. When Tg mice were fed a high-fat diet, they developed more pronounced obesity and hepatic steatosis than did wild-type mice. Consistent with its role in lipid droplet formation, the expression of adipose differentiation-related protein (ADRP) was elevated in the livers of Tg mice. Of note, obesity and hepatic steatosis induced by a high-fat diet were more pronounced in aged than in young wild-type mice, and aged wild-type mice had elevated levels of ADRP, suggesting that the metabolic abnormalities present in Tg mice mimic those in aged mice. Our results provide the first in vivo evidence that decreased proteasomal chymotrypsin-like activity affects longevity and aggravates age-related metabolic disorders, such as obesity and hepatic steatosis.
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107
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Begriche K, Levasseur PR, Zhang J, Rossi J, Skorupa D, Solt LA, Young B, Burris TP, Marks DL, Mynatt RL, Butler AA. Genetic dissection of the functions of the melanocortin-3 receptor, a seven-transmembrane G-protein-coupled receptor, suggests roles for central and peripheral receptors in energy homeostasis. J Biol Chem 2011; 286:40771-81. [PMID: 21984834 PMCID: PMC3220494 DOI: 10.1074/jbc.m111.278374] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 09/05/2011] [Indexed: 01/29/2023] Open
Abstract
The melanocortin-3 receptor (MC3R) gene is pleiotropic, influencing body composition, natriuresis, immune function, and entrainment of circadian rhythms to nutrient intake. MC3Rs are expressed in hypothalamic and limbic regions of the brain and in peripheral tissues. To investigate the roles of central MC3Rs, we inserted a "lox-stop-lox" (LoxTB) 5' of the translation initiation codon of the mouse Mc3r gene and reactivated transcription using neuron-specific Cre transgenic mice. As predicted based on earlier observations of Mc3r knock-out mice, Mc3r(TB/TB) mice displayed reduced lean mass, increased fat mass, and accelerated diet-induced obesity. Surprisingly, rescuing Mc3r expression in the nervous system using the Nestin-Cre transgene only partially rescued obesity in chow-fed conditions and had no impact on the accelerated diet-induced obesity phenotype. The ventromedial hypothalamus (VMH), a critical node in the neural networks regulating feeding-related behaviors and metabolic homeostasis, exhibits dense Mc3r expression relative to other brain regions. To target VMH MC3R expression, we used the steroidogenic factor-1 Cre transgenic mouse. Although restoring VMH MC3R signaling also had a modest impact on obesity, marked improvements in metabolic homeostasis were observed. VMH MC3R signaling was not sufficient to rescue the lean mass phenotype or the regulation of behaviors anticipating food anticipation. These results suggest that actions of MC3Rs impacting on energy homeostasis involve both central and peripheral sites of action. The impact of central MC3Rs on behavior and metabolism involves divergent pathways; VMH MC3R signaling improves metabolic homeostasis but does not significantly impact on the expression of behaviors anticipating nutrient availability.
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Affiliation(s)
| | - Peter R. Levasseur
- the Department of Pediatrics, Oregon Health and Science University, Portland, Oregon 97239, and
| | - Jingying Zhang
- the Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana 70808
| | - Jari Rossi
- From the Departments of Metabolism and Aging and
| | | | | | - Brandon Young
- the Genomics Core, The Scripps Research Institute, Jupiter, Florida 33458
| | | | - Daniel L. Marks
- the Department of Pediatrics, Oregon Health and Science University, Portland, Oregon 97239, and
| | - Randall L. Mynatt
- the Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana 70808
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108
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Swist E, Chen Q, Qiao C, Caldwell D, Gruber H, Scoggan KA. Excess dietary iodine differentially affects thyroid gene expression in diabetes, thyroiditis-prone versus -resistant BioBreeding (BB) rats. Mol Nutr Food Res 2011; 55:1875-86. [PMID: 22058052 DOI: 10.1002/mnfr.201100299] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 06/29/2011] [Accepted: 07/04/2011] [Indexed: 12/11/2022]
Abstract
SCOPE To identify genes involved in the susceptibility to iodine-induced autoimmune thyroiditis. METHODS AND RESULTS Diabetes, thyroiditis-prone (BBdp) and -resistant (BBc) rats were fed either a control or a high-iodine diet for 9 wk. Excess iodine intake increased the incidence of insulitis and thyroiditis in BBdp rats. BBdp rats fed the high-iodine diet that did not develop thyroiditis had higher mRNA levels of Fabp4, Cidec, perilipin, Pparγ and Slc36a2 than BBdp rats fed the control diet and BBc rats fed either the control or the high-iodine diet. BBdp rats fed the high-iodine diet that did develop thyroiditis had higher mRNA levels of Cidec, Icam1, Ifitm1, and Slpi than BBdp rats fed the control diet and BBc rats fed either the control or the high-iodine diet. BBdp rats that did develop thyroiditis had lower mRNA levels of Fabp4, perilipin and Slc36a2 but higher mRNA levels of Icam1, Ifitm1 and Slpi than BBdp that did not develop thyroiditis. Excess dietary iodine also increased the protein levels of Fabp4, Cidec and perilipin in BBdp rats. CONCLUSION Differential expression of thyroid genes in BBdp versus BBc rats caused by excess dietary iodine may be implicated in autoimmune thyroiditis and insulitis pathogenesis.
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Affiliation(s)
- Eleonora Swist
- Nutrition Research Division, Food Directorate, Health Products and Food Branch, Health Canada, Banting Research Centre, Ottawa, Ontario, Canada
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109
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Rosiglitazone Induces Mitochondrial Biogenesis in Differentiated Murine 3T3-L1 and C3H/10T1/2 Adipocytes. PPAR Res 2011; 2011:179454. [PMID: 22013433 PMCID: PMC3195302 DOI: 10.1155/2011/179454] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 07/20/2011] [Accepted: 08/04/2011] [Indexed: 01/14/2023] Open
Abstract
Growing evidence indicates that PPARγ agonists, including rosiglitazone (RSG), induce adipose mitochondrial biogenesis. By systematically analyzing mitochondrial gene expression in two common murine adipocyte models, the current study aimed to further establish the direct role of RSG and capture temporal changes in gene transcription. Microarray profiling revealed that in fully differentiated 3T3-L1 and C3H/10T1/2 adipocytes treated with RSG or DMSO vehicle for 1, 2, 4, 7, 24, and 48 hrs, RSG overwhelmingly increased mitochondrial gene transcripts time dependently. The timing of the increases was consistent with the cascade of organelle biogenesis, that is, initiated by induction of transcription factor(s), followed by increases in the biosynthesis machinery, and then by increases in functional components. The transcriptional increases were further validated by increased mitochondrial staining, citrate synthase activity, and O2 consumption, and were found to be associated with increased adiponectin secretion. The work provided further insight on the mechanism of PPARγ-induced mitochondrial biogenesis in differentiated adipocytes.
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110
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Choi SH, Ginsberg HN. Increased very low density lipoprotein (VLDL) secretion, hepatic steatosis, and insulin resistance. Trends Endocrinol Metab 2011; 22:353-63. [PMID: 21616678 PMCID: PMC3163828 DOI: 10.1016/j.tem.2011.04.007] [Citation(s) in RCA: 249] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2011] [Revised: 04/18/2011] [Accepted: 04/19/2011] [Indexed: 12/14/2022]
Abstract
Insulin resistance (IR) affects not only the regulation of carbohydrate metabolism but all aspects of lipid and lipoprotein metabolism. IR is associated with increased secretion of VLDL and increased plasma triglycerides, as well as with hepatic steatosis, despite the increased VLDL secretion. Here we link IR with increased VLDL secretion and hepatic steatosis at both the physiologic and molecular levels. Increased VLDL secretion, together with the downstream effects on high density lipoprotein (HDL) cholesterol and low density lipoprotein (LDL) size, is proatherogenic. Hepatic steatosis is a risk factor for steatohepatitis and cirrhosis. Understanding the complex inter-relationships between IR and these abnormalities of liver lipid homeostasis will provide insights relevant to new therapies for these increasing clinical problems.
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Affiliation(s)
- Sung Hee Choi
- Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seoul, Korea
| | - Henry N Ginsberg
- Columbia University College of Physicians and Surgeons, New York, NY, USA
- whom correspondence should be addressed.
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111
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Role of lipid droplet proteins in liver steatosis. J Physiol Biochem 2011; 67:629-36. [DOI: 10.1007/s13105-011-0110-6] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2011] [Accepted: 07/31/2011] [Indexed: 12/28/2022]
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112
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Uno K, Yamada T, Ishigaki Y, Imai J, Hasegawa Y, Gao J, Kaneko K, Matsusue K, Yamazaki T, Oka Y, Katagiri H. Hepatic peroxisome proliferator-activated receptor-γ-fat-specific protein 27 pathway contributes to obesity-related hypertension via afferent vagal signals. Eur Heart J 2011; 33:1279-89. [PMID: 21825308 DOI: 10.1093/eurheartj/ehr265] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
AIMS Obesity is commonly associated with hypertension. Increased sympathetic tonus in obese subjects contributes to the underlying mechanism. However, the precise mechanisms whereby obesity induces this sympathetic activation remain unclear. Hepatic peroxisome proliferator-activated receptor (PPAR)-γ2 expression, which is reportedly upregulated during obesity development, affects sympathetic activation via hepatic vagal afferents. Herein, we report involvement of this neuronal relay in obesity-related hypertension. METHODS AND RESULTS Peroxisome proliferator-activated receptor-γ and a direct PPARγ target, fat-specific protein 27 (Fsp27), were adenovirally overexpressed or knocked down in the liver, in combination with surgical dissection or pharmacological deafferentation of the hepatic vagus. Adenoviral PPARγ2 expression in the liver raised blood pressure (BP) in wild-type but not in β1/β2/β3 adrenergic receptor-deficient mice. In addition, knockdown of endogenous PPARγ in the liver lowered BP in murine obesity models. Either surgical dissection or pharmacological deafferentation of the hepatic vagus markedly blunted BP elevation in mice with diet-induced and genetically-induced obesity. In contrast, BP was not elevated in other models of hepatic steatosis, DGAT1 and DGAT2 overexpressions, in which PPARγ is not upregulated in the liver. Thus, hepatic PPARγ upregulation associated with obesity is involved in BP elevation during obesity development. Furthermore, hepatic expression of Fsp27 raised BP and the effect was blocked by hepatic vagotomy. Hepatic Fsp27 is actually upregulated in murine obesity models and its knockdown reversed BP elevation. CONCLUSION The hepatic PPARγ-Fsp27 pathway plays important roles in the development of obesity-related hypertension via afferent vagal signals from the liver.
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Affiliation(s)
- Kenji Uno
- Department of Metabolic Diseases, Center for Metabolic Diseases, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Japan
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113
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Lee JH, Giannikopoulos P, Duncan SA, Wang J, Johansen CT, Brown JD, Plutzky J, Hegele RA, Glimcher LH, Lee AH. The transcription factor cyclic AMP-responsive element-binding protein H regulates triglyceride metabolism. Nat Med 2011; 17:812-5. [PMID: 21666694 DOI: 10.1038/nm.2347] [Citation(s) in RCA: 164] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2010] [Accepted: 03/07/2011] [Indexed: 12/16/2022]
Abstract
Here we report that the transcription factor cyclic AMP-responsive element-binding protein H (CREB-H, encoded by CREB3L3) is required for the maintenance of normal plasma triglyceride concentrations. CREB-H-deficient mice showed hypertriglyceridemia secondary to inefficient triglyceride clearance catalyzed by lipoprotein lipase (Lpl), partly due to defective expression of the Lpl coactivators Apoc2, Apoa4 and Apoa5 (encoding apolipoproteins C2, A4 and A5, respectively) and concurrent augmentation of the Lpl inhibitor Apoc3. We identified multiple nonsynonymous mutations in CREB3L3 that produced hypomorphic or nonfunctional CREB-H protein in humans with extreme hypertriglyceridemia, implying a crucial role for CREB-H in human triglyceride metabolism.
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Affiliation(s)
- Jung Hoon Lee
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, USA
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114
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Oberer M, Boeszoermenyi A, Nagy HM, Zechner R. Recent insights into the structure and function of comparative gene identification-58. Curr Opin Lipidol 2011; 22:149-58. [PMID: 21494142 PMCID: PMC5808844 DOI: 10.1097/mol.0b013e328346230e] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
PURPOSE OF REVIEW Comparative gene identification-58 (CGI-58) is an important player in lipid metabolism. It acts as activator of triglyceride hydrolases and as acyl-CoA-dependent lysophosphatidic acid acyltransferase. This review aims at establishing a structure-function relationship of this still rather enigmatic protein based on recent studies characterizing different functions of CGI-58. RECENT FINDINGS Novel studies confirm the important regulatory role of CGI-58 as activator of the triglyceride hydrolase adipose triglyceride lipase. New evidence, corroborated by the characterization of a CGI-58 knockout mouse model, also suggests the existence of yet unknown lipases that are activated by CGI-58. Additionally, CGI-58 was identified to exert acyl-CoA-dependent lysophosphatidic acid acyltransferase activity, which implies possible roles in triglyceride or phospholipid synthesis or signaling processes. Unlike mammalian CGI-58 proteins, orthologs from plants and yeast additionally act as weak triglyceride and phospholipid hydrolases. A first three-dimensional model was calculated and allows preliminary structural considerations for the functions of CGI-58. SUMMARY Despite important progress concerning the different biochemical functions of CGI-58, the physiological importance of these activities requires better characterization. Furthermore, three-dimensional structural data for CGI-58 are required to unveil the molecular mechanism of how CGI-58 acts as activator of lipases and exerts its enzymatic functions.
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Affiliation(s)
- Monika Oberer
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50/3, 8010 Graz, Austria
| | - Andras Boeszoermenyi
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50/3, 8010 Graz, Austria
| | - Harald Manuel Nagy
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50/3, 8010 Graz, Austria
| | - Rudolf Zechner
- Institute of Molecular Biosciences, University of Graz, Heinrichstrasse 31, 8010 Graz, Austria
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115
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Kang HS, Okamoto K, Takeda Y, Beak JY, Gerrish K, Bortner CD, DeGraff LM, Wada T, Xie W, Jetten AM. Transcriptional profiling reveals a role for RORalpha in regulating gene expression in obesity-associated inflammation and hepatic steatosis. Physiol Genomics 2011; 43:818-28. [PMID: 21540300 DOI: 10.1152/physiolgenomics.00206.2010] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Retinoid-related orphan receptor (ROR)α4 is the major RORα isoform expressed in adipose tissues and liver. In this study we demonstrate that RORα-deficient staggerer mice (RORα(sg/sg)) fed with a high-fat diet (HFD) exhibited reduced adiposity and hepatic triglyceride levels compared with wild-type (WT) littermates and were resistant to the development of hepatic steatosis, adipose-associated inflammation, and insulin resistance. Gene expression profiling showed that many genes involved in triglyceride synthesis and storage, including Cidec, Cidea, and Mogat1, were expressed at much lower levels in liver of RORα(sg/sg) mice. In contrast, overexpression of RORα in mouse hepatoma Hepa1-6 cells significantly increased the expression of genes that were repressed in RORα(sg/sg) liver, including Sult1b1, Adfp, Cidea, and ApoA4. ChIP and promoter analysis suggested that several of these genes were regulated directly by RORα. In addition to reduced lipid accumulation, inflammation was greatly diminished in white adipose tissue (WAT) of RORα(sg/sg) mice fed with an HFD. The infiltration of macrophages and the expression of many immune response and proinflammatory genes, including those encoding various chemo/cytokines, Toll-like receptors, and TNF signaling proteins, were significantly reduced in RORα(sg/sg) WAT. Moreover, RORα(sg/sg) mice fed with an HFD were protected from the development of insulin resistance. RORα(sg/sg) mice consumed more oxygen and produced more carbon dioxide, suggesting increased energy expenditure in this genotype. Our study indicates that RORα plays a critical role in the regulation of several aspects of metabolic syndrome. Therefore, RORα may provide a novel therapeutic target in the management of obesity and associated metabolic diseases.
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Affiliation(s)
- Hong Soon Kang
- Cell Biology Section, Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA
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Ashrafian H, Athanasiou T, Li JV, Bueter M, Ahmed K, Nagpal K, Holmes E, Darzi A, Bloom SR. Diabetes resolution and hyperinsulinaemia after metabolic Roux-en-Y gastric bypass. Obes Rev 2011; 12:e257-72. [PMID: 20880129 DOI: 10.1111/j.1467-789x.2010.00802.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The global prevalence of type 2 diabetes mellitus and impaired glucose metabolism continues to rise in conjunction with the pandemic of obesity. The metabolic Roux-en-Y gastric bypass operation offers the successful resolution of diabetes in addition to sustained weight loss and excellent long-term outcomes in morbidly obese individuals. The procedure consists of the physiological BRAVE effects: (i) Bile flow alteration; (ii) Reduction of gastric size; (iii) Anatomical gut rearrangement and altered flow of nutrients; (iv) Vagal manipulation and (v) Enteric gut hormone modulation. This operation provides anti-diabetic effects through decreasing insulin resistance and increasing the efficiency of insulin secretion. These metabolic outcomes are achieved through weight-independent and weight-dependent mechanisms. These include the foregut, midgut and hindgut mechanisms, decreased inflammation, fat, adipokine and bile metabolism, metabolic modulation, shifts in gut microbial composition and intestinal gluconeogenesis. In a small minority of patients, gastric bypass results in hyperinsulinaemic hypoglycaemia that may lead to nesidioblastosis (pancreatic beta-cell hypertrophy with islet hyperplasia). Elucidating the precise metabolic mechanisms of diabetes resolution and hyperinsulinaemia after surgery can lead to improved operations and disease-specific procedures including 'diabetes surgery'. It can also improve our understanding of diabetes pathogenesis that may provide novel strategies for the management of metabolic syndrome and impaired glucose metabolism.
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Affiliation(s)
- H Ashrafian
- The Department of Surgery and Cancer, Imperial College London, London, UK.
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117
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Müller G, Schneider M, Biemer-Daub G, Wied S. Microvesicles released from rat adipocytes and harboring glycosylphosphatidylinositol-anchored proteins transfer RNA stimulating lipid synthesis. Cell Signal 2011; 23:1207-23. [PMID: 21435393 DOI: 10.1016/j.cellsig.2011.03.013] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Accepted: 03/14/2011] [Indexed: 12/20/2022]
Abstract
Small microvesicles, such as microparticles and exosomes, have been demonstrated to transfer proteins and nucleic acids from a variety of donor to acceptor cells with corresponding (patho)physiological consequences. Recently the in vitro transfer of glycosylphosphatidylinositol (GPI)-anchored proteins from microvesicles released from large rat adipocytes to intracellular lipid droplets (LDs) of small adipocytes has been shown to be upregulated by physiological (palmitate, H(2)O(2)) and pharmacological (anti-diabetic sulfonylurea drug glimepiride) stimuli and to increase the esterification into as well as to reduce the release of fatty acids from triacylglycerol. Here microvesicles derived from (preferentially large) rat adipocytes or plasma and harboring the GPI-anchored proteins, Gce1 and CD73, were demonstrated to contain specific transcripts and microRNAs that are both transferred into and expressed in acceptor adipocytes and are involved in the upregulation of lipogenesis and cell size. The transferred transcripts were specific for fatty acid esterification (glycerol-3-phosphate acyltransferase-3, diacylglycerol acyltransferase-2), lipid droplet biogenesis (FSP27, caveolin-1) and adipokines (leptin, adiponectin). The transfer and lipogenic activity were more efficient for small rather than large acceptor adipocytes and significantly upregulated by palmitate, glimepiride and H(2)O(2). Together the data suggest that microvesicles released from large adipocytes stimulate lipid storage in small adipocytes by mediating horizontal transfer of lipogenic information which is encoded by relevant (micro)RNA and GPI-anchored protein species. Paracrine and endocrine regulation of lipid storage and, in parallel, cell size of white adipocytes by specific (micro)RNAs in GPI-anchored protein-harboring microvesicles may represent a novel target for interference with metabolic diseases, such as obesity and metabolic syndrome.
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Affiliation(s)
- Günter Müller
- Sanofi-Aventis Deutschland GmbH, R & D Diabetes, Industrial Park Höchst, Frankfurt am Main, Germany.
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118
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Fujimoto T, Parton RG. Not just fat: the structure and function of the lipid droplet. Cold Spring Harb Perspect Biol 2011; 3:cshperspect.a004838. [PMID: 21421923 DOI: 10.1101/cshperspect.a004838] [Citation(s) in RCA: 335] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Lipid droplets (LDs) are independent organelles that are composed of a lipid ester core and a surface phospholipid monolayer. Recent studies have revealed many new proteins, functions, and phenomena associated with LDs. In addition, a number of diseases related to LDs are beginning to be understood at the molecular level. It is now clear that LDs are not an inert store of excess lipids but are dynamically engaged in various cellular functions, some of which are not directly related to lipid metabolism. Compared to conventional membrane organelles, there are still many uncertainties concerning the molecular architecture of LDs and how each function is placed in a structural context. Recent findings and remaining questions are discussed.
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Affiliation(s)
- Toyoshi Fujimoto
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Japan.
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119
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Kulyté A, Pettersson AT, Antonson P, Stenson BM, Langin D, Gustafsson JA, Staels B, Rydén M, Arner P, Laurencikiene J. CIDEA interacts with liver X receptors in white fat cells. FEBS Lett 2011; 585:744-8. [PMID: 21315073 DOI: 10.1016/j.febslet.2011.02.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Revised: 01/10/2011] [Accepted: 02/04/2011] [Indexed: 10/18/2022]
Abstract
Cell death-inducing DNA fragmentation factor alpha-like effector A (CIDEA) is endogenously expressed in human but not rodent white adipocytes. We performed a bioinformatic analysis of the human CIDEA sequence and found conserved amino-acid motifs involved in binding to nuclear receptors. Protein-protein binding experiments and transactivation assays confirmed that CIDEA binds to liver X receptors and regulates their activity in vitro. Cell fractionation demonstrated that CIDEA localizes to both the cytoplasm and the nucleus in human white adipocytes. The interaction between CIDEA and nuclear receptors could therefore be of importance for the regulation of metabolic processes in human adipose tissue.
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Affiliation(s)
- Agné Kulyté
- Department of Medicine, Karolinska Institutet, Karolinska University Hospital, Huddinge, 141 86 Stockholm, Sweden
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120
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Ross KA. Evidence for somatic gene conversion and deletion in bipolar disorder, Crohn's disease, coronary artery disease, hypertension, rheumatoid arthritis, type-1 diabetes, and type-2 diabetes. BMC Med 2011; 9:12. [PMID: 21291537 PMCID: PMC3048570 DOI: 10.1186/1741-7015-9-12] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Accepted: 02/03/2011] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND During gene conversion, genetic information is transferred unidirectionally between highly homologous but non-allelic regions of DNA. While germ-line gene conversion has been implicated in the pathogenesis of some diseases, somatic gene conversion has remained technically difficult to investigate on a large scale. METHODS A novel analysis technique is proposed for detecting the signature of somatic gene conversion from SNP microarray data. The Wellcome Trust Case Control Consortium has gathered SNP microarray data for two control populations and cohorts for bipolar disorder (BD), cardiovascular disease (CAD), Crohn's disease (CD), hypertension (HT), rheumatoid arthritis (RA), type-1 diabetes (T1D) and type-2 diabetes (T2D). Using the new analysis technique, the seven disease cohorts are analyzed to identify cohort-specific SNPs at which conversion is predicted. The quality of the predictions is assessed by identifying known disease associations for genes in the homologous duplicons, and comparing the frequency of such associations with background rates. RESULTS Of 28 disease/locus pairs meeting stringent conditions, 22 show various degrees of disease association, compared with only 8 of 70 in a mock study designed to measure the background association rate (P < 10-9). Additional candidate genes are identified using less stringent filtering conditions. In some cases, somatic deletions appear likely. RA has a distinctive pattern of events relative to other diseases. Similarities in patterns are apparent between BD and HT. CONCLUSIONS The associations derived represent the first evidence that somatic gene conversion could be a significant causative factor in each of the seven diseases. The specific genes provide potential insights about disease mechanisms, and are strong candidates for further study.
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Affiliation(s)
- Kenneth Andrew Ross
- Department of Computer Science, Columbia University, New York, NY 10027, USA.
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121
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Zhang L, Dai Y, Bian L, Wang W, Wang W, Muramatsu M, Hua Q. Association of the cell death-inducing DNA fragmentation factor alpha-like effector A (CIDEA) gene V115F (G/T) polymorphism with phenotypes of metabolic syndrome in a Chinese population. Diabetes Res Clin Pract 2011; 91:233-8. [PMID: 21106268 DOI: 10.1016/j.diabres.2010.10.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Revised: 10/09/2010] [Accepted: 10/26/2010] [Indexed: 01/18/2023]
Abstract
AIMS The CIDEA gene is involved in energy metabolism and a non-synonymous single nucleotide polymorphism (SNP), V115F (G/T), is a risk factor for obesity in Swedish subjects and metabolic syndrome (MetS) in Japanese subjects. However, the risk allele was a G in Swedish subjects and a T in Japanese subjects. The present study investigated the association between this SNP and MetS in a Chinese population. METHODS Three hundred and fifty-one subjects evaluated at the Cardiac Clinic in Xuanwu Hospital for MetS risks were recruited. Anthropometric measurements, blood pressure, fasting blood glucose, and blood lipid levels were determined in addition to the polymorphism. RESULTS The proportion of subjects with MetS was significantly higher based on genotype, in the order: GG<GT<TT (p=0.003). In multiple logistic regression analysis, the odds ratios for MetS in the GT and TT genotypes, compared to the referent GG genotype, were 2.26 (p=0.003) and 2.89 (p=0.002), respectively. Similar trends were observed for the related phenotypes of central obesity (GT: OR=2.20, p=0.004; TT: OR=3.31, p=0.002) and dyslipidemia (GT: OR=1.73, p=0.047; TT: OR=2.10, p=0.03). CONCLUSIONS The T allele of the CIDEA V115F SNP is a risk factor for MetS and its related phenotypes in a Chinese population.
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Affiliation(s)
- Ling Zhang
- Department of Epidemiology and Biostatistics, School of Public Health and Family Medicine, Capital Medical University, No. 129 Mail Box, No. 10 Xitoutiao, Youanmenwai, Beijing 100069, PR China
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122
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Kang HS, Okamoto K, Kim YS, Takeda Y, Bortner CD, Dang H, Wada T, Xie W, Yang XP, Liao G, Jetten AM. Nuclear orphan receptor TAK1/TR4-deficient mice are protected against obesity-linked inflammation, hepatic steatosis, and insulin resistance. Diabetes 2011; 60:177-88. [PMID: 20864514 PMCID: PMC3012170 DOI: 10.2337/db10-0628] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
OBJECTIVE The nuclear receptor TAK1/TR4/NR2C2 is expressed in several tissues that are important in the control of energy homeostasis. In this study, we investigate whether TAK1 functions as a regulator of lipid and energy homeostasis and has a role in metabolic syndrome. RESEARCH DESIGN AND METHODS We generated TAK1-deficient (TAK1⁻(/)⁻) mice to study the function of TAK1 in the development of metabolic syndrome in aged mice and mice fed a high-fat diet (HFD). (Immuno)histochemical, biochemical, and gene expression profile analyses were performed to determine the effect of the loss of TAK1 expression on lipid homeostasis in liver and adipose tissues. In addition, insulin sensitivity, energy expenditure, and adipose-associated inflammation were compared in wild-type (WT) and TAK1⁻(/)⁻ mice fed a HFD. RESULTS TAK1-deficient (TAK1⁻(/)⁻) mice are resistant to the development of age- and HFD-induced metabolic syndrome. Histo- and biochemical analyses showed significantly lower hepatic triglyceride levels and reduced lipid accumulation in adipose tissue in TAK1⁻(/)⁻ mice compared with WT mice. Gene expression profiling analysis revealed that the expression of several genes encoding proteins involved in lipid uptake and triglyceride synthesis and storage, including Cidea, Cidec, Mogat1, and CD36, was greatly decreased in the liver and primary hepatocytes of TAK1⁻(/)⁻ mice. Restoration of TAK1 expression in TAK1⁻(/)⁻ hepatocytes induced expression of several lipogenic genes. Moreover, TAK1⁻(/)⁻ mice exhibited reduced infiltration of inflammatory cells and expression of inflammatory genes in white adipose tissue, and were resistant to the development of glucose intolerance and insulin resistance. TAK1⁻(/)⁻ mice consume more oxygen and produce more carbon dioxide than WT mice, suggesting increased energy expenditure. CONCLUSIONS Our data reveal that TAK1 plays a critical role in the regulation of energy and lipid homeostasis, and promotes the development of metabolic syndrome. TAK1 may provide a new therapeutic target in the management of obesity, diabetes, and liver steatosis.
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Affiliation(s)
- Hong Soon Kang
- Cell Biology Section, Laboratory of Respiratory Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina
| | - Kyoko Okamoto
- Cell Biology Section, Laboratory of Respiratory Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina
| | - Yong-Sik Kim
- Cell Biology Section, Laboratory of Respiratory Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina
| | - Yukimasa Takeda
- Cell Biology Section, Laboratory of Respiratory Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina
| | - Carl D. Bortner
- Laboratory of Signal Transduction, Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina
| | - Huaixin Dang
- Cell Biology Section, Laboratory of Respiratory Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina
| | - Taira Wada
- Center for Pharmacogenetics and Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Wen Xie
- Center for Pharmacogenetics and Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Xiao-Ping Yang
- Cell Biology Section, Laboratory of Respiratory Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina
| | - Grace Liao
- Cell Biology Section, Laboratory of Respiratory Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina
| | - Anton M. Jetten
- Cell Biology Section, Laboratory of Respiratory Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina
- Corresponding author: Anton M. Jetten,
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Abstract
The lipid droplet (LD), an organelle that exists ubiquitously in various organisms, from bacteria to mammals, has attracted much attention from both medical and cell biology fields. The LD in white adipocytes is often treated as the prototype LD, but is rather a special example, considering that its size, intracellular localization and molecular composition are vastly different from those of non-adipocyte LDs. These differences confer distinct properties on adipocyte and non-adipocyte LDs. In this article, we address the current understanding of LDs by discussing the differences between adipocyte and non-adipocyte LDs.
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Affiliation(s)
- Michitaka Suzuki
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
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124
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Yang X, Dunning KR, Wu LLY, Hickey TE, Norman RJ, Russell DL, Liang X, Robker RL. Identification of perilipin-2 as a lipid droplet protein regulated in oocytes during maturation. Reprod Fertil Dev 2010; 22:1262-71. [PMID: 20883652 DOI: 10.1071/rd10091] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Accepted: 06/28/2010] [Indexed: 12/16/2022] Open
Abstract
Lipid droplet proteins regulate the storage and utilisation of intracellular lipids. Evidence is emerging that oocyte lipid utilisation impacts embryo development, but lipid droplet proteins have not been studied in oocytes. The aim of the present study was to characterise the size and localisation of lipid droplets in mouse oocytes during the periovulatory period and to identify lipid droplet proteins as potential biomarkers of oocyte lipid content. Oocyte lipid droplets, visualised using a novel method of staining cumulus-oocyte complexes (COCs) with BODIPY 493/503, were small and diffuse in oocytes of preovulatory COCs, but larger and more centrally located after maturation in response to ovulatory human chorionic gonadotrophin (hCG) in vivo, or FSH + epidermal growth factor in vitro. Lipid droplet proteins perilipin, perilipin-2, cell death-inducing DNA fragmentation factor 45-like effector (CIDE)-A and CIDE-B were detected in the mouse ovary by immunohistochemistry, but only perilipin-2 was associated with lipid droplets in the oocyte. In COCs, perilipin-2 mRNA and protein increased in response to ovulatory hCG. IVM failed to induce perilipin-2 mRNA, yet oocyte lipid content was increased in this context, indicating that perilipin-2 is not necessarily reflective of relative oocyte lipid content. Thus, perilipin-2 is a lipid droplet protein in oocytes and its induction in the COC concurrent with dynamic reorganisation of lipid droplets suggests marked changes in lipid utilisation during oocyte maturation.
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Affiliation(s)
- Xing Yang
- The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong Province, 510080, China
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125
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Li F, Gu Y, Dong W, Li H, Zhang L, Li N, Li W, Zhang L, Song Y, Jiang L, Ye J, Li Q. Cell death-inducing DFF45-like effector, a lipid droplet-associated protein, might be involved in the differentiation of human adipocytes. FEBS J 2010; 277:4173-83. [PMID: 20945533 DOI: 10.1111/j.1742-4658.2010.07806.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Cell death-inducing DFF45-like effector (CIDE) family proteins, including cell death-inducing DFF45-like effector A (CIDEA), cell death-inducing DFF45-like effector B (CIDEB) and cell death-inducing DFF45-like effector C (CIDEC) [fat-specific protein of 27 kDa in rodent (FSP27) in rodents], were originally identified by their sequence homology to the N-terminal region of DNA fragmentation factor DFF40/45. Recent reports have revealed that CIDE family proteins play important roles in lipid metabolism. Several studies involving knockdown mice revealed that FSP27 is a lipid droplet-targeting protein that can promote the formation of lipid droplets. However, the detailed roles of human CIDEC in the differentiation of human adipocytes remain unknown. In the present study, we found that the expression of CIDEC increased during the differentiation of fetal adipose tissues, but decreased during the de-differentiation of adipocytic tumors, suggesting that the expression of CIDEC should be positively correlated with the differentiation of adipocytes. Furthermore, we verified that human CIDEC was localized on the surface of lipid droplets. Using human primary pre-adipocytes, we confirmed that the expression of CIDEC was elevated during the differentiation of pre-adipocytes, and knockdown of CIDEC in human primary pre-adipocytes resulted in differentiation defects. These data demonstrate that CIDEC is essential for the differentiation of adipose tissue. Together with regulating adipocyte lipid metabolism, CIDEC should be a potential target for regulating adipocyte differentiation and reducing fat cell mass.
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Affiliation(s)
- Fanfan Li
- State Key Laboratory of Cancer Biology, Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi’an, China
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126
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Min J, Zhang W, Gu Y, Hong L, Yao L, Li F, Zhao D, Feng Y, Zhang H, Li Q. CIDE-3 interacts with lipopolysaccharide-induced tumor necrosis factor, and overexpression increases apoptosis in hepatocellular carcinoma. Med Oncol 2010; 28 Suppl 1:S219-27. [PMID: 20957525 DOI: 10.1007/s12032-010-9702-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Accepted: 09/21/2010] [Indexed: 01/07/2023]
Abstract
Cell death-inducing DFF45-like effector-3 (CIDE-3) is a novel member of an apoptosis-inducing protein family, but its function is unknown. CIDE-3 shows a different distribution pattern in hepatocellular carcinoma (HCC) tissues and normal adjacent tissues. Therefore, this work tested the hypothesis that CIDE-3 induces apoptosis in HCC cells, inhibiting oncogenesis and tumor development. We used immunohistochemistry to evaluate the expression of CIDE-3 in 82 HCC samples and 51 adjacent liver tissues. Overexpression of CIDE-3 induced apoptosis, as detected by flow cytometry, in the HCC cell line SMMC-7721, which had undetectable levels of CIDE-3 in the absence of CIDE-3 overexpression. A yeast two-hybrid system was employed to screen for proteins that interact with CIDE-3. The expression of CIDE-3 was decreased in HCC tissue, compared to adjacent normal tissues, and CIDE-3 expression and HCC differentiation were positively correlated. CIDE-3 expression levels were lower in poorly differentiated HCC tissue than in well-differentiated HCC tissue. Overexpressed CIDE-3 inhibited proliferation and induced apoptosis in HCC cells. We found that lipopolysaccharide-induced tumor necrosis factor (LITAF) interacted with CIDE-3 in hepatic cells. This is the first demonstrated interaction between CIDE-3 and LITAF, and the first report that CIDE-3 induces apoptosis in hepatocellular carcinoma.
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Affiliation(s)
- Jie Min
- State Key Laboratory Of Cancer Biology, Department of pathology, Xijing Hospital, The Fourth Military Medical University, 710032 Xi'an, China
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127
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Identification and Characterization of a Novel Mouse Cidea N-terminal Truncated Isoform*. PROG BIOCHEM BIOPHYS 2010. [DOI: 10.3724/sp.j.1206.2010.00159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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128
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Jinno Y, Nakakuki M, Sato A, Kawano H, Notsu T, Mizuguchi K, Shimano H. Cide-a and Cide-c are induced in the progression of hepatic steatosis and inhibited by eicosapentaenoic acid. Prostaglandins Leukot Essent Fatty Acids 2010; 83:75-81. [PMID: 20542418 DOI: 10.1016/j.plefa.2010.05.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Accepted: 05/24/2010] [Indexed: 01/12/2023]
Abstract
Cide-a and Cide-c belong to the cell death-inducing DNA fragmentation factor-alpha-like effector family. Recent evidences suggest that these proteins may be involved in lipid accumulation in liver and adipose tissues. We confirmed that in the high-fat/high-sucrose diet-induced murine model of hepatic steatosis, the expression levels of the Cide-a and Cide-c genes were markedly and time-dependently increased, but returned to normal levels following improvement of hepatic steatosis by eicosapentaenoic acid (EPA) administration. Levels of expression of the Cide-a and Cide-c genes correlated well with plasma ALT. EPA inhibited the promoter activity of the Cide-a gene in vitro. Sterol regulatory element-binding protein-1 (SREBP-1) markedly enhanced the promoter activity of Cide-a, and EPA inhibited the expression of Cide-a mRNA. SREBP-1 and EPA did not affect those of Cide-c. These findings indicate that Cide-a and Cide-c are closely involved in the progression of hepatic steatosis, and that EPA inhibits Cide-a gene expression through SREBP-1 regulation.
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Affiliation(s)
- Yasutaka Jinno
- Development Research, Pharmaceutical Research Center, Mochida Pharmaceutical Co., Ltd., Shizuoka 412-8524, Japan
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129
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Li D, Zhang Y, Xu L, Zhou L, Wang Y, Xue B, Wen Z, Li P, Sang J. Regulation of gene expression by FSP27 in white and brown adipose tissue. BMC Genomics 2010; 11:446. [PMID: 20649970 PMCID: PMC3091643 DOI: 10.1186/1471-2164-11-446] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Accepted: 07/22/2010] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Brown and white adipose tissues (BAT and WAT) play critical roles in controlling energy homeostasis and in the development of obesity and diabetes. The mouse Fat-Specific protein 27 (FSP27), a member of the cell death-inducing DFF45-like effector (CIDE) family, is expressed in both BAT and WAT and is associated with lipid droplets. Over-expression of FSP27 promotes lipid storage, whereas FSP27 deficient mice have improved insulin sensitivity and are resistant to diet-induced obesity. In addition, FSP27-deficient white adipocytes have reduced lipid storage, smaller lipid droplets, increased mitochondrial activity and a higher expression of several BAT-selective genes. To elucidate the molecular mechanism by which FSP27 controls lipid storage and gene expression in WAT and BAT, we systematically analyzed the gene expression profile of FSP27-deficient WAT by microarray analysis and compared the expression levels of a specific set of genes in WAT and BAT by semi-quantitative real-time PCR analysis. RESULTS BAT-selective genes were significantly up-regulated, whereas WAT-selective genes were down-regulated in the WAT of FSP27-deficient mice. The expression of the BAT-selective genes was also dramatically up-regulated in the WAT of leptin/FSP27 double deficient mice. In addition, the expression levels of genes involved in multiple metabolic pathways, including oxidative phosphorylation, the TCA cycle, fatty acid synthesis and fatty acid oxidation, were increased in the FSP27-deficient WAT. In contrast, the expression levels for genes involved in extracellular matrix remodeling, the classic complement pathway and TGF-beta signaling were down-regulated in the FSP27-deficient WAT. Most importantly, the expression levels of regulatory factors that determine BAT identity, such as CEBP alpha/beta, PRDM16 and major components of the cAMP pathway, were markedly up-regulated in the WAT of FSP27-deficient mice. The expression levels of these regulatory factors were also up-regulated in leptin/FSP27 double deficient mice. Interestingly, distinct gene expression profiles were observed in the BAT of FSP27-deficient mice. Taken together, these data suggest that the WAT of FSP27-deficient mice have a gene expression profile similar to that of BAT. CONCLUSIONS FSP27 acts as a molecular determinant that controls gene expression for a diversity of metabolic and signaling pathways and, in particular, the expression of regulatory factors, including CEBP alpha/beta, PRDM16 and components of the cAMP signaling pathway, that control the identity of WAT and BAT.
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Affiliation(s)
- De Li
- College of Life Sciences, Beijing Normal University Xinjiekouwai Street 19, Xichen District Beijing 100875, China
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130
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Chen Z, Norris JY, Finck BN. Peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha) stimulates VLDL assembly through activation of cell death-inducing DFFA-like effector B (CideB). J Biol Chem 2010; 285:25996-6004. [PMID: 20551328 DOI: 10.1074/jbc.m110.141598] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Abnormalities in very low density lipoprotein (VLDL) assembly and secretion impact intrahepatic lipid homeostasis, plasma lipoprotein profile, and energy metabolism of distal peripheral tissues. We have evaluated the role of the transcriptional coactivator, the peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha), in VLDL assembly and secretion. PGC-1alpha overexpression in HepG2 cells led to diminished rates of triglyceride (TG) synthesis but strongly stimulated VLDL-TG secretion, markedly increasing the efficiency of secretion of newly synthesized TG. PGC-1alpha overexpression increased the rate of secretion of apoB100 and promoted secretion of larger, less dense VLDL particles. PGC-1alpha overexpression in intact mouse liver also stimulated rates of VLDL TG secretion and attenuated hepatic TG accumulation resulting from high fat diet feeding. To determine the molecular mechanisms mediating the effect of PGC-1alpha on VLDL assembly, we evaluated the expression of several candidate mediators known to be involved in VLDL assembly or hepatic lipid homeostasis. Cell death-inducing DFFA-like effector B (CideB) expression was greatly induced by PGC-1alpha, and siRNA against CideB reversed the effects of PGC-1alpha on the secretion of TG and VLDL-sized particles by HepG2 cells, indicating that CideB is a critical mediator of stimulatory effects of PGC-1alpha on VLDL secretion. Collectively, these data suggest that PGC-1alpha plays an important role in partitioning cytoplasmic TG toward the VLDL secretory compartments and promoting VLDL secretion via transcriptional induction of CideB.
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Affiliation(s)
- Zhouji Chen
- Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University School of Medicine, St Louis, Missouri 63110, USA.
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131
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Human adenovirus 36 decreases fatty acid oxidation and increases de novo lipogenesis in primary cultured human skeletal muscle cells by promoting Cidec/FSP27 expression. Int J Obes (Lond) 2010; 34:1355-64. [PMID: 20440297 DOI: 10.1038/ijo.2010.77] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
BACKGROUND It has been well documented that human adenovirus type 36 (Ad-36) is associated with obesity. However, the underlying molecular mechanism of Ad-36 inducing obesity remains unknown. We sought to investigate the effect of Ad-36 infection on Cidec, AMPK pathway and lipid metabolism in primary cultured human skeletal muscle cells. METHODS Cidec/fat-specific protein 27 (FSP27), fatty acid oxidation, AMPK signaling and the abundance of proteins involved in lipid synthesis were determined in muscle cells infected with various doses (1.9-7.6 MOI) of Ad-36 and non-lipogenic adenovirus type 2 (Ad-2) as a negative control as well as an uninfected control. Cidec/FSP27 siRNA transfection was performed in Ad-36-infected muscle cells. RESULTS Our data show that Ad-36 significantly reduced fatty acid oxidation in a dose-dependent manner (all P values are <0.01), but Ad-2 did not affect fatty acid oxidation. Ad-36 substantially increased Cidec/FSP27, ACC, sterol regulatory element-binding protein 1c (SREBP-1c), SREBP-2 and 3-hydroxy-3-methylglutaryl-CoA reductase protein abundance, but significantly reduced AMPK activity, mitochondrial mass and uncoupling protein 3 (UCP3) abundance in comparison with control cells (all P values are <0.01). Oil Red O staining revealed that there was substantial fat accumulation in the Ad-36-infected muscle cells. Furthermore, Cidec/FSP27 siRNA transfection significantly reduced FSP27 expression and partially restored AMPK signaling, increased UCP3 and decreased SERBP 1c and perilipin proteins in Ad-36-infected muscle cells. Interestingly, neither Ad-36 nor Ad-2 affected peroxisome proliferator-activated receptor γ protein expression in muscle cells. CONCLUSION This study suggests that Ad-36 induced lipid droplets in the cultured skeletal muscle cells and this process may be mediated by promoting Cidec/FSP27 expression.
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Fain JN, Cheema P, Madan AK, Tichansky DS. Dexamethasone and the inflammatory response in explants of human omental adipose tissue. Mol Cell Endocrinol 2010; 315:292-8. [PMID: 19853017 DOI: 10.1016/j.mce.2009.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Revised: 09/15/2009] [Accepted: 10/09/2009] [Indexed: 12/01/2022]
Abstract
Dexamethasone is a synthetic glucocorticoid that is a potent anti-inflammatory agent. The present studies examined the changes in gene expression of 64 proteins in human omental adipose tissue explants incubated for 48h both in the absence and presence of dexamethasone as well as the release of 8 of these proteins that are putative adipokines. The proteins were chosen because they are inflammatory response proteins in other cells, are key regulatory proteins or are proteins with known functions. About 50% were significantly up-regulated while about 10% were unchanged and the remaining 40% were down-regulated. Dexamethasone significantly up-regulated the expression of about 33% of the proteins but down-regulated the expression of about 12% of the proteins. We conclude that dexamethasone is a selective anti-inflammatory agent since it inhibits only about one-fourth of the proteins up-regulated during in vitro incubation of human omental adipose tissue.
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Affiliation(s)
- John N Fain
- Department of Molecular Sciences, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
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133
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Nian Z, Sun Z, Yu L, Toh SY, Sang J, Li P. Fat-specific protein 27 undergoes ubiquitin-dependent degradation regulated by triacylglycerol synthesis and lipid droplet formation. J Biol Chem 2010; 285:9604-9615. [PMID: 20089860 DOI: 10.1074/jbc.m109.043786] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The fat-specific protein 27 (Fsp27), a protein localized to lipid droplets (LDs), plays an important role in controlling lipid storage and mitochondrial activity in adipocytes. Fsp27-null mice display increased energy expenditure and are resistant to high fat diet-induced obesity and diabetes. However, little is known about how the Fsp27 protein is regulated. Here, we show that Fsp27 stability is controlled by the ubiquitin-dependent proteasomal degradation pathway in adipocytes. The ubiquitination of Fsp27 is regulated by three lysine residues located in the C-terminal region. Substitution of these lysine residues with alanines greatly increased Fsp27 stability and enhanced lipid storage in adipocytes. Furthermore, Fsp27 was stabilized and rapidly accumulated following treatment with beta-agonists that induce lipolysis and fatty acid re-esterification in adipocytes. More importantly, Fsp27 stabilization was dependent on triacylglycerol synthesis and LD formation, because knockdown of diacylglycerol acyltransferase in adipocytes significantly reduced Fsp27 accumulation in adipocytes. Finally, we observed that increased Fsp27 during beta-agonist treatment preferentially associated with LDs. Taken together, our data revealed that Fsp27 can be stabilized by free fatty acid availability, triacylglycerol synthesis, and LD formation. The stabilization of Fsp27 when free fatty acids are abundant further enhances lipid storage, providing positive feedback to regulate lipid storage in adipocytes.
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Affiliation(s)
- Zongqian Nian
- Protein Science Laboratory of Ministry of Education, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Zhiqi Sun
- Protein Science Laboratory of Ministry of Education, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Luxin Yu
- College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Shen Yon Toh
- Institute of Molecular and Cell Biology, 138673 Singapore
| | - Jianli Sang
- College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Peng Li
- Protein Science Laboratory of Ministry of Education, School of Life Sciences, Tsinghua University, Beijing 100084, China.
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Svensson PA, Gummesson A, Carlsson LMS, Sjöholm K. Changes in human adipose tissue gene expression during diet-induced weight loss. JOURNAL OF NUTRIGENETICS AND NUTRIGENOMICS 2010; 3:239-50. [PMID: 21474955 DOI: 10.1159/000324360] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Per-Arne Svensson
- Sahlgrenska Center for Cardiovascular and Metabolic Research, Department of Molecular and Clinical Medicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden.
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135
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Abstract
Long underappreciated as important cellular organelles, lipid droplets are finally being recognized as dynamic structures with a complex and interesting biology. In light of this newfound respect, we discuss emerging views on lipid droplet biology and speculate on the major advances to come.
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Affiliation(s)
- Robert V Farese
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, USA.
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136
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Hall AM, Brunt EM, Chen Z, Viswakarma N, Reddy JK, Wolins NE, Finck BN. Dynamic and differential regulation of proteins that coat lipid droplets in fatty liver dystrophic mice. J Lipid Res 2009; 51:554-63. [PMID: 19749180 DOI: 10.1194/jlr.m000976] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Lipid droplet proteins (LDPs) coat the surface of triglyceride-rich lipid droplets and regulate their formation and lipolysis. We profiled hepatic LDP expression in fatty liver dystrophic (fld) mice, a unique model of neonatal hepatic steatosis that predictably resolves between postnatal day 14 (P14) and P17. Western blotting revealed that perilipin-2/ADRP and perilipin-5/OXPAT were markedly increased in steatotic fld liver but returned to normal by P17. However, the changes in perilipin-2 and perilipin-5 protein content in fld mice were exaggerated compared with relatively modest increases in corresponding mRNAs encoding these proteins, a phenomenon likely mediated by increased protein stability. Conversely, cell death-inducing DFFA-like effector (Cide) family genes were strongly induced at the level of mRNA expression in steatotic fld mouse liver. Surprisingly, levels of peroxisome proliferator-activated receptor gamma, which is known to regulate Cide expression, were unchanged in fld mice. However, sterol-regulatory element binding protein 1 (SREBP-1) was activated in fld liver and CideA was revealed as a new direct target gene of SREBP-1. In summary, LDP content is markedly increased in liver of fld mice. However, whereas perilipin-2 and perilipin-5 levels are primarily regulated posttranslationally, Cide family mRNA expression is induced, suggesting that these families of LDP are controlled at different regulatory checkpoints.
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Affiliation(s)
- Angela M Hall
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
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