251
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Brown adipose tissue activity controls triglyceride clearance. Nat Med 2011; 17:200-5. [PMID: 21258337 DOI: 10.1038/nm.2297] [Citation(s) in RCA: 1213] [Impact Index Per Article: 93.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 12/22/2010] [Indexed: 12/19/2022]
Abstract
Brown adipose tissue (BAT) burns fatty acids for heat production to defend the body against cold and has recently been shown to be present in humans. Triglyceride-rich lipoproteins (TRLs) transport lipids in the bloodstream, where the fatty acid moieties are liberated by the action of lipoprotein lipase (LPL). Peripheral organs such as muscle and adipose tissue take up the fatty acids, whereas the remaining cholesterol-rich remnant particles are cleared by the liver. Elevated plasma triglyceride concentrations and prolonged circulation of cholesterol-rich remnants, especially in diabetic dyslipidemia, are risk factors for cardiovascular disease. However, the precise biological role of BAT for TRL clearance remains unclear. Here we show that increased BAT activity induced by short-term cold exposure controls TRL metabolism in mice. Cold exposure drastically accelerated plasma clearance of triglycerides as a result of increased uptake into BAT, a process crucially dependent on local LPL activity and transmembrane receptor CD36. In pathophysiological settings, cold exposure corrected hyperlipidemia and improved deleterious effects of insulin resistance. In conclusion, BAT activity controls vascular lipoprotein homeostasis by inducing a metabolic program that boosts TRL turnover and channels lipids into BAT. Activation of BAT might be a therapeutic approach to reduce elevated triglyceride concentrations and combat obesity in humans.
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252
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Faulconnier Y, Chilliard Y, Torbati MBM, Leroux C. The transcriptomic profiles of adipose tissues are modified by feed deprivation in lactating goats. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS 2010; 6:139-49. [PMID: 21256818 DOI: 10.1016/j.cbd.2010.12.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Revised: 12/15/2010] [Accepted: 12/15/2010] [Indexed: 10/18/2022]
Abstract
A major function of ruminant adipose tissue is to store lipids for use in productive functions. Body fat mobilization is required during periods of negative energy balance such as lactation or undernutrition. Until now, gene expression profiling of ruminant adipose tissue in response to nutritional restriction has not been performed. To gain a better understanding of the molecular mechanisms in adipose tissue in response to dietary factors, microarray analysis was used to compare the effects of two extreme nutritional conditions (control diet vs. 48-h feed deprivation) in the omental and perirenal adipose tissues of lactating goats (Capra hircus). We observed the altered expression of 456 and 199 genes in omental and perirenal adipose tissues, respectively. Similar biological processes were altered by feed deprivation in these two sites, although twice as many genes were differentially expressed in the omental than in the perirenal adipose tissue. Taken together, the transcriptional changes involved in lipid metabolism (decreased lipid synthesis and triglyceride storage capacity as well as increased fatty acid oxidation) were consistent with reduced energy deposition in goat adipose tissues in response to a 48-h fast. An inflammatory state of the adipose tissue was observed following the 48-h fast.
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Affiliation(s)
- Y Faulconnier
- Unité de Recherches sur les Herbivores, Institut National de la Recherche Agronomique, Theix, Saint Genès-Champanelle, France
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253
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Abstract
Increased dietary saturated fat intake can lead to detrimental effects on human health. In this issue of Cell Metabolism, Lichtenstein et al. (2010) show that by inhibiting lipoprotein lipase (LPL) activity in mesenteric lymph nodes, Angiopoietin-like protein 4 (Angptl4) protects resident macrophages from dietary saturated fatty acid (SFA)-induced inflammation.
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Affiliation(s)
- Olivia Osborn
- Department of Medicine, Division of Endocrinology and Metabolism, University of California, San Diego, La Jolla, CA 92093, USA
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254
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Lichtenstein L, Mattijssen F, de Wit NJ, Georgiadi A, Hooiveld GJ, van der Meer R, He Y, Qi L, Köster A, Tamsma JT, Tan NS, Müller M, Kersten S. Angptl4 protects against severe proinflammatory effects of saturated fat by inhibiting fatty acid uptake into mesenteric lymph node macrophages. Cell Metab 2010; 12:580-92. [PMID: 21109191 PMCID: PMC3387545 DOI: 10.1016/j.cmet.2010.11.002] [Citation(s) in RCA: 201] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Revised: 08/12/2010] [Accepted: 09/09/2010] [Indexed: 02/07/2023]
Abstract
Dietary saturated fat is linked to numerous chronic diseases, including cardiovascular disease. Here we study the role of the lipoprotein lipase inhibitor Angptl4 in the response to dietary saturated fat. Strikingly, in mice lacking Angptl4, saturated fat induces a severe and lethal phenotype characterized by fibrinopurulent peritonitis, ascites, intestinal fibrosis, and cachexia. These abnormalities are preceded by a massive acute phase response induced by saturated but not unsaturated fat or medium-chain fat, originating in mesenteric lymph nodes (MLNs). MLNs undergo dramatic expansion and contain numerous lipid-laden macrophages. In peritoneal macrophages incubated with chyle, Angptl4 dramatically reduced foam cell formation, inflammatory gene expression, and chyle-induced activation of ER stress. Induction of macrophage Angptl4 by fatty acids is part of a mechanism that serves to reduce postprandial lipid uptake from chyle into MLN-resident macrophages by inhibiting triglyceride hydrolysis, thereby preventing macrophage activation and foam cell formation and protecting against progressive, uncontrolled saturated fat-induced inflammation.
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Affiliation(s)
- Laeticia Lichtenstein
- Nutrigenomics Consortium, TI Food and Nutrition, 6700AN, Wageningen, The Netherlands
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255
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Smart-Halajko MC, Robciuc MR, Cooper JA, Jauhiainen M, Kumari M, Kivimaki M, Khaw KT, Boekholdt SM, Wareham NJ, Gaunt TR, Day IN, Braund PS, Nelson CP, Hall AS, Samani NJ, Humphries SE, Ehnholm C, Talmud PJ. The relationship between plasma angiopoietin-like protein 4 levels, angiopoietin-like protein 4 genotype, and coronary heart disease risk. Arterioscler Thromb Vasc Biol 2010; 30:2277-82. [PMID: 20829508 PMCID: PMC3319296 DOI: 10.1161/atvbaha.110.212209] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To investigate the relationship between angiopoietin-like protein 4 (Angptl4) levels, coronary heart disease (CHD) biomarkers, and ANGPTL4 variants. METHODS AND RESULTS Plasma Angptl4 was quantified in 666 subjects of the Northwick Park Heart Study II using a validated ELISA. Seven ANGPTL4 single-nucleotide polymorphisms were genotyped, and CHD biomarkers were assessed in the whole cohort (N=2775). Weighted mean±SD plasma Angptl4 levels were 10.0±11.0 ng/mL. Plasma Angptl4 concentration correlated positively with age (r=0.15, P<0.001) and body fat mass (r=0.19, P=0.003) but negatively with plasma high-density lipoprotein cholesterol (r=-0.13, P=0.01). No correlation with triglycerides (TGs) was observed. T266M was independently associated with plasma Angptl4 levels (P<0.001) but was not associated with TGs or CHD risk in the meta-analysis of 5 studies (4061 cases/15 395 controls). E40K showed no independent association with plasma Angptl4 levels. In human embryonic kidney 293 and human hepatoma 7 cells compared with wild type, E40K and T266M showed significantly altered synthesis and secretion, respectively. CONCLUSIONS Circulating Angptl4 levels may not influence TG levels or CHD risk for the following reasons: (1) Angptl4 levels were not correlated with TGs; (2) T266M, although associated with Angptl4 levels, showed no association with plasma TGs; and (3) TG-lowering E40K did not influence Angptl4 levels. These results provide new insights into the role of Angptl4 in TG metabolism.
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Affiliation(s)
- Melissa C Smart-Halajko
- Centre for Cardiovascular Genetics, University College London, 5 University St, London WC1E 6JF, England.
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256
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Goh YY, Pal M, Chong HC, Zhu P, Tan MJ, Punugu L, Lam CRI, Yau YH, Tan CK, Huang RL, Tan SM, Tang MBY, Ding JL, Kersten S, Tan NS. Angiopoietin-like 4 interacts with integrins beta1 and beta5 to modulate keratinocyte migration. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 177:2791-803. [PMID: 20952587 DOI: 10.2353/ajpath.2010.100129] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Adipose tissue secretes adipocytokines for energy homeostasis, but recent evidence indicates that some adipocytokines also have a profound local impact on wound healing. Upon skin injury, keratinocytes use various signaling molecules to promote reepithelialization for efficient wound closure. In this study, we identify a novel function of adipocytokine angiopoietin-like 4 (ANGPTL4) in keratinocytes during wound healing through the control of both integrin-mediated signaling and internalization. Using two different in vivo models based on topical immuno-neutralization of ANGPTL4 as well as ablation of the ANGPTL4 gene, we show that ANGPTL4-deficient mice exhibit delayed wound reepithelialization with impaired keratinocyte migration. Human keratinocytes in which endogenous ANGPTL4 expression was suppressed by either siRNA or a neutralizing antibody show impaired migration associated with diminished integrin-mediated signaling. Importantly, we identify integrins β1 and β5, but not β3, as novel binding partners of ANGPTL4. ANGPTL4-bound integrin β1 activated the FAK-Src-PAK1 signaling pathway, which is important for cell migration. The findings presented herein reveal an unpredicted role of ANGPTL4 during wound healing and demonstrate how ANGPTL4 stimulates intracellular signaling mechanisms to coordinate cellular behavior. Our findings provide insight into a novel cell migration control mechanism and underscore the physiological importance of the modulation of integrin activity in cancer metastasis.
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Affiliation(s)
- Yan Yih Goh
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
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257
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Abstract
PURPOSE OF REVIEW There are strong epidemiologic connections between plasma triglycerides and atherosclerosis. We will consider to what extent this goes back to derangements of the lipoprotein lipase (LPL) system. The roles of hepatic lipase and endothelial lipase will also be touched upon. RECENT FINDINGS Understanding of LPL action has taken major steps with the discovery of lipase maturation factor 1 as a specific endoplasmic reticulum chaperon needed for proper folding of the lipases, glycosylphosphatidylinositol-anchored HDL-binding protein 1 as an endothelial cell protein needed for transport and binding of LPL and some angiopoietin-like proteins that can modulate LPL activity. Studies of genetic variants continue to support the important roles of the lipases in lipoprotein metabolism and in atherosclerosis. CONCLUSION There are several ways by which derangement of the lipases may contribute to atherogenesis. Lipase actions are major determinants of plasma lipoprotein patterns. LPL activity must be modulated in relation to the physiological situation (feeding, fasting, exercise, etc.). Fatty acids and monoglycerides generated must be efficiently removed so that they do not endanger the integrity of the endothelium, cause lipotoxic reactions or both. In addition, the lipases may cause binding and endocytosis of lipoprotein particles in the artery wall.
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Affiliation(s)
- Gunilla Olivecrona
- Department of Medical Biosciences, Section on Physiological Chemistry, Umeå University, Umeå, Sweden.
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258
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Decreased fat storage by Lactobacillus paracasei is associated with increased levels of angiopoietin-like 4 protein (ANGPTL4). PLoS One 2010; 5. [PMID: 20927337 PMCID: PMC2948012 DOI: 10.1371/journal.pone.0013087] [Citation(s) in RCA: 200] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Accepted: 09/08/2010] [Indexed: 02/07/2023] Open
Abstract
Background Intervention strategies for obesity are global issues that require immediate attention. One approach is to exploit the growing consensus that beneficial gut microbiota could be of use in intervention regimes. Our objective was to determine the mechanism by which the probiotic bacteria Lactobacillus paracasei ssp paracasei F19 (F19) could alter fat storage. Angiopoietin-like 4 (ANGPTL4) is a circulating lipoprotein lipase (LPL) inhibitor that controls triglyceride deposition into adipocytes and has been reported to be regulated by gut microbes. Methodology/Principal Findings A diet intervention study of mice fed high-fat chow supplemented with F19 was carried out to study potential mechanistic effects on fat storage. Mice given F19 displayed significantly less body fat, as assessed by magnetic resonance imaging, and a changed lipoprotein profile. Given that previous studies on fat storage have identified ANGPTL4 as an effector, we also investigated circulating levels of ANGPTL4, which proved to be higher in the F19-treated group. This increase, together with total body fat and triglyceride levels told a story of inhibited LPL action through ANGPTL4 leading to decreased fat storage. Co-culture experiments of colonic cell lines and F19 were set up in order to monitor any ensuing alterations in ANGPTL4 expression by qPCR. We observed that potentially secreted factors from F19 can induce ANGPTL4 gene expression, acting in part through the peroxisome proliferator activated receptors alpha and gamma. To prove validity of in vitro findings, germ-free mice were monocolonized with F19. Here we again found changes in serum triglycerides as well as ANGPTL4 in response to F19. Conclusions/Significance Our results provide an interesting mechanism whereby modifying ANGPTL4, a central player in fat storage regulation, through manipulating gut flora could be an important gateway upon which intervention trials of weight management can be based.
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259
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Vrablik M, Hubacek JA. Genetic determination of triglyceridemia with special focus on apolipoprotein gene variants. ACTA ACUST UNITED AC 2010. [DOI: 10.2217/clp.10.38] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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260
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Beigneux AP. GPIHBP1 and the processing of triglyceride-rich lipoproteins. ACTA ACUST UNITED AC 2010; 5:575-582. [PMID: 20953295 DOI: 10.2217/clp.10.43] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
GPIHBP1 is a new addition to a group of proteins required for the lipolysis of triglyceride-rich lipoproteins. GPIHBP1 contains an acidic domain and an Ly6 domain with ten cysteines. GPIHBP1 binds lipoprotein lipase (LPL) avidly and likely tethers LPL to the luminal surface of capillaries.Inactivation of Gpihbp1 in mice is associated with milky plasma and severe chylomicronemia, even on a low-fat chow diet. Recently, four missense mutations in GPIHBP1 were identified in humans with severe chylomicronemia (C65Y, C65S, C68G, and Q115P). All four mutations involve highly conserved residues within GPIHBP1's Ly6 domain.This review will provide an update on GPIHBP1's role in the processing of chylomicrons and the pathogenesis of chylomicronemia.
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Affiliation(s)
- Anne P Beigneux
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
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261
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Georgiadi A, Lichtenstein L, Degenhardt T, Boekschoten MV, van Bilsen M, Desvergne B, Müller M, Kersten S. Induction of Cardiac Angptl4 by Dietary Fatty Acids Is Mediated by Peroxisome Proliferator-Activated Receptor β/δ and Protects Against Fatty Acid–Induced Oxidative Stress. Circ Res 2010; 106:1712-21. [DOI: 10.1161/circresaha.110.217380] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Rationale
:
Although dietary fatty acids are a major fuel for the heart, little is known about the direct effects of dietary fatty acids on gene regulation in the intact heart.
Objective
:
To study the effect of dietary fatty acids on cardiac gene expression and explore the functional consequences.
Methods and Results
:
Oral administration of synthetic triglycerides composed of one single fatty acid altered cardiac expression of numerous genes, many of which are involved in the oxidative stress response. The gene most significantly and consistently upregulated by dietary fatty acids encoded Angiopoietin-like protein (Angptl)4, a circulating inhibitor of lipoprotein lipase expressed by cardiomyocytes. Induction of Angptl4 by the fatty acid linolenic acid was specifically abolished in peroxisome proliferator-activated receptor (PPAR)β/δ
−/−
and not PPARα
−/−
mice and was blunted on siRNA-mediated PPARβ/δ knockdown in cultured cardiomyocytes. Consistent with these data, linolenic acid stimulated binding of PPARβ/δ but not PPARα to the Angptl4 gene. Upregulation of Angptl4 resulted in decreased cardiac uptake of plasma triglyceride-derived fatty acids and decreased fatty acid-induced oxidative stress and lipid peroxidation. In contrast, Angptl4 deletion led to enhanced oxidative stress in the heart, both after an acute oral fat load and after prolonged high fat feeding.
Conclusions
:
Stimulation of cardiac Angptl4 gene expression by dietary fatty acids and via PPARβ/δ is part of a feedback mechanism aimed at protecting the heart against lipid overload and consequently fatty acid–induced oxidative stress.
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Affiliation(s)
- Anastasia Georgiadi
- From the Nutrition, Metabolism and Genomics Group (A.G., L.L., M.V.B., M.M., S.K.), Division of Human Nutrition, Wageningen University. The Netherlands; Nutrigenomics Consortium (L.L., M.V.B., M.M., S.K.), TI Food and Nutrition, Wageningen, The Netherlands; Department of Biochemistry (T.D.), University of Kuopio, Finland; Department of Physiology (M.v.B.), Maastricht University, The Netherlands; and Centre Intégrative Génomique (B.D.), University of Lausanne, Switzerland
| | - Laeticia Lichtenstein
- From the Nutrition, Metabolism and Genomics Group (A.G., L.L., M.V.B., M.M., S.K.), Division of Human Nutrition, Wageningen University. The Netherlands; Nutrigenomics Consortium (L.L., M.V.B., M.M., S.K.), TI Food and Nutrition, Wageningen, The Netherlands; Department of Biochemistry (T.D.), University of Kuopio, Finland; Department of Physiology (M.v.B.), Maastricht University, The Netherlands; and Centre Intégrative Génomique (B.D.), University of Lausanne, Switzerland
| | - Tatjana Degenhardt
- From the Nutrition, Metabolism and Genomics Group (A.G., L.L., M.V.B., M.M., S.K.), Division of Human Nutrition, Wageningen University. The Netherlands; Nutrigenomics Consortium (L.L., M.V.B., M.M., S.K.), TI Food and Nutrition, Wageningen, The Netherlands; Department of Biochemistry (T.D.), University of Kuopio, Finland; Department of Physiology (M.v.B.), Maastricht University, The Netherlands; and Centre Intégrative Génomique (B.D.), University of Lausanne, Switzerland
| | - Mark V. Boekschoten
- From the Nutrition, Metabolism and Genomics Group (A.G., L.L., M.V.B., M.M., S.K.), Division of Human Nutrition, Wageningen University. The Netherlands; Nutrigenomics Consortium (L.L., M.V.B., M.M., S.K.), TI Food and Nutrition, Wageningen, The Netherlands; Department of Biochemistry (T.D.), University of Kuopio, Finland; Department of Physiology (M.v.B.), Maastricht University, The Netherlands; and Centre Intégrative Génomique (B.D.), University of Lausanne, Switzerland
| | - Marc van Bilsen
- From the Nutrition, Metabolism and Genomics Group (A.G., L.L., M.V.B., M.M., S.K.), Division of Human Nutrition, Wageningen University. The Netherlands; Nutrigenomics Consortium (L.L., M.V.B., M.M., S.K.), TI Food and Nutrition, Wageningen, The Netherlands; Department of Biochemistry (T.D.), University of Kuopio, Finland; Department of Physiology (M.v.B.), Maastricht University, The Netherlands; and Centre Intégrative Génomique (B.D.), University of Lausanne, Switzerland
| | - Beatrice Desvergne
- From the Nutrition, Metabolism and Genomics Group (A.G., L.L., M.V.B., M.M., S.K.), Division of Human Nutrition, Wageningen University. The Netherlands; Nutrigenomics Consortium (L.L., M.V.B., M.M., S.K.), TI Food and Nutrition, Wageningen, The Netherlands; Department of Biochemistry (T.D.), University of Kuopio, Finland; Department of Physiology (M.v.B.), Maastricht University, The Netherlands; and Centre Intégrative Génomique (B.D.), University of Lausanne, Switzerland
| | - Michael Müller
- From the Nutrition, Metabolism and Genomics Group (A.G., L.L., M.V.B., M.M., S.K.), Division of Human Nutrition, Wageningen University. The Netherlands; Nutrigenomics Consortium (L.L., M.V.B., M.M., S.K.), TI Food and Nutrition, Wageningen, The Netherlands; Department of Biochemistry (T.D.), University of Kuopio, Finland; Department of Physiology (M.v.B.), Maastricht University, The Netherlands; and Centre Intégrative Génomique (B.D.), University of Lausanne, Switzerland
| | - Sander Kersten
- From the Nutrition, Metabolism and Genomics Group (A.G., L.L., M.V.B., M.M., S.K.), Division of Human Nutrition, Wageningen University. The Netherlands; Nutrigenomics Consortium (L.L., M.V.B., M.M., S.K.), TI Food and Nutrition, Wageningen, The Netherlands; Department of Biochemistry (T.D.), University of Kuopio, Finland; Department of Physiology (M.v.B.), Maastricht University, The Netherlands; and Centre Intégrative Génomique (B.D.), University of Lausanne, Switzerland
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262
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Weissglas-Volkov D, Pajukanta P. Genetic causes of high and low serum HDL-cholesterol. J Lipid Res 2010; 51:2032-57. [PMID: 20421590 DOI: 10.1194/jlr.r004739] [Citation(s) in RCA: 147] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Plasma levels of HDL cholesterol (HDL-C) have a strong inherited basis with heritability estimates of 40-60%. The well-established inverse relationship between plasma HDL-C levels and the risk of coronary artery disease (CAD) has led to an extensive search for genetic factors influencing HDL-C concentrations. Over the past 30 years, candidate gene, genome-wide linkage, and most recently genome-wide association (GWA) studies have identified several genetic variations for plasma HDL-C levels. However, the functional role of several of these variants remains unknown, and they do not always correlate with CAD. In this review, we will first summarize what is known about HDL metabolism, monogenic disorders associated with both low and high HDL-C levels, and candidate gene studies. Then we will focus this review on recent genetic findings from the GWA studies and future strategies to elucidate the remaining substantial proportion of HDL-C heritability. Comprehensive investigation of the genetic factors conferring to low and high HDL-C levels using integrative approaches is important to unravel novel pathways and their relations to CAD, so that more effective means of diagnosis, treatment, and prevention will be identified.
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263
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Abstract
The growth of lymphatic vessels (lymphangiogenesis) is actively involved in a number of pathological processes including tissue inflammation and tumor dissemination but is insufficient in patients suffering from lymphedema, a debilitating condition characterized by chronic tissue edema and impaired immunity. The recent explosion of knowledge on the molecular mechanisms governing lymphangiogenesis provides new possibilities to treat these diseases.
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Affiliation(s)
- Tuomas Tammela
- Molecular/Cancer Biology Laboratory and Haartman Institute, University of Helsinki, Finland
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264
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Niki D, Katsu K, Yokouchi Y. Ontogeny of angiopoietin-like protein 1, 2, 3, 4, 5, and 7 genes during chick embryonic development. Dev Growth Differ 2010; 51:821-32. [PMID: 19951324 DOI: 10.1111/j.1440-169x.2009.01145.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Angiopoietin-like proteins (ANGPTLs) are secreted proteins possessing an amino-terminal coiled-coil domain and a carboxyl-terminal fibrinogen-like domain and are known as angiogenic factors. Several members of ANGPTLs also regulate lipid metabolism independently of angiogenic effects, but most of their functions during vertebrate development are not demonstrated. To ascertain their developmental functions, we examined the expression patterns of Angptl1, 2, 3, 4, 5, and 7 orthologues during chick development using whole-mount in situ hybridization. Angptl1 was first detected at embryonic day 3 (E3) in the somite. At E4, Angptl1 was expressed in somite-derivatives and limb mesenchyme. Angptl2 was first detected at E3 in the hindbrain. At E4, Angptl2 was expressed in neuroepithelium of forebrain and hindbrain and partly in the heart. Angptl3 was first detected at E3 and continued to be expressed in the liver and yolk sac at E4. Angptl4 was first detected at E3 in the somites and liver. At E4, Angptl4 was also observed in the heart. Angptl5 was not detected in these developmental stages. Angptl7 was first detected at E3 in the ectoderm overlying the lenses of the eyes. At E4, Angptl7 was specifically expressed in cornea. These data suggest that each member of the ANGPTL family could be related to angiogenesis during various organogeneses of the developing chick embryo.
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Affiliation(s)
- Daisuke Niki
- Division of Organogenesis, Department of Pattern Formation, Institute of Molecular Embryology and Genetics, Kumamoto University, 2-2-1 Honjo, Kumamoto, Japan
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265
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Lopaschuk GD, Ussher JR, Folmes CDL, Jaswal JS, Stanley WC. Myocardial fatty acid metabolism in health and disease. Physiol Rev 2010; 90:207-58. [PMID: 20086077 DOI: 10.1152/physrev.00015.2009] [Citation(s) in RCA: 1441] [Impact Index Per Article: 102.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
There is a constant high demand for energy to sustain the continuous contractile activity of the heart, which is met primarily by the beta-oxidation of long-chain fatty acids. The control of fatty acid beta-oxidation is complex and is aimed at ensuring that the supply and oxidation of the fatty acids is sufficient to meet the energy demands of the heart. The metabolism of fatty acids via beta-oxidation is not regulated in isolation; rather, it occurs in response to alterations in contractile work, the presence of competing substrates (i.e., glucose, lactate, ketones, amino acids), changes in hormonal milieu, and limitations in oxygen supply. Alterations in fatty acid metabolism can contribute to cardiac pathology. For instance, the excessive uptake and beta-oxidation of fatty acids in obesity and diabetes can compromise cardiac function. Furthermore, alterations in fatty acid beta-oxidation both during and after ischemia and in the failing heart can also contribute to cardiac pathology. This paper reviews the regulation of myocardial fatty acid beta-oxidation and how alterations in fatty acid beta-oxidation can contribute to heart disease. The implications of inhibiting fatty acid beta-oxidation as a potential novel therapeutic approach for the treatment of various forms of heart disease are also discussed.
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Affiliation(s)
- Gary D Lopaschuk
- Cardiovascular Research Group, Mazankowski Alberta Heart Institute, University of Alberta, Alberta T6G 2S2, Canada.
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266
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Hodson L, Fielding BA. Trafficking and partitioning of fatty acids: the transition from fasted to fed state. ACTA ACUST UNITED AC 2010. [DOI: 10.2217/clp.09.72] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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267
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Lichtenstein L, Kersten S. Modulation of plasma TG lipolysis by Angiopoietin-like proteins and GPIHBP1. Biochim Biophys Acta Mol Cell Biol Lipids 2010; 1801:415-20. [PMID: 20056168 DOI: 10.1016/j.bbalip.2009.12.015] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Revised: 11/21/2009] [Accepted: 12/24/2009] [Indexed: 02/07/2023]
Abstract
There is evidence that elevated plasma triglycerides (TG) serve as an independent risk factor for coronary heart disease. Plasma TG levels are determined by the balance between the rate of production of chylomicrons and VLDL in intestine and liver, respectively, and their rate of clearance in peripheral tissues. Lipolytic processing of TG-rich lipoproteins is mediated by the enzyme lipoprotein lipase (LPL), which is tethered to the capillary endothelium via heparin sulphate proteoglycans. In recent years the Angiopoietin-like proteins ANGPTL3 and ANGPTL4 have emerged as novel modulators of LPL activity. Studies in transgenic animals supported by in vitro experiments have demonstrated that ANGPTL3 and ANGPTL4 impair plasma TG clearance by inhibiting LPL activity. In humans, genetic variation within the ANGPTL3 and ANGPTL4 genes contributes to variation in plasma TG and HDL levels, thereby validating the importance of ANGPTLs in the regulation of lipoprotein metabolism in humans. Combined with the discovery of GPIHBP1 as a likely LPL anchor, these findings have led to a readjustment of the mechanism of LPL function. This review provides an overview of our current understanding of the role and regulation of ANGPTL3, ANGPTL4 and GPIHBP1, and places the newly acquired knowledge in the context of the established function and mechanism of LPL-mediated lipolysis.
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268
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Lu B, Moser A, Shigenaga JK, Grunfeld C, Feingold KR. The acute phase response stimulates the expression of angiopoietin like protein 4. Biochem Biophys Res Commun 2010; 391:1737-41. [DOI: 10.1016/j.bbrc.2009.12.145] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Accepted: 12/23/2009] [Indexed: 12/11/2022]
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269
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Dallinga-Thie GM, Franssen R, Mooij HL, Visser ME, Hassing HC, Peelman F, Kastelein JJP, Péterfy M, Nieuwdorp M. The metabolism of triglyceride-rich lipoproteins revisited: new players, new insight. Atherosclerosis 2009; 211:1-8. [PMID: 20117784 DOI: 10.1016/j.atherosclerosis.2009.12.027] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2009] [Revised: 12/17/2009] [Accepted: 12/18/2009] [Indexed: 12/31/2022]
Abstract
Peripheral lipoprotein lipase (LPL)-mediated lipolysis of triglycerides is the first step in chylomicron/VLDL clearance involving heparan sulfate proteoglycans (HSPGs) displayed at the cell surface of the capillaries in adipose tissue, heart and skeletal muscle. The newly generated chylomicron remnant particles are then cleared by the liver, whereas VLDL remnant particles are either further modified, through the action of hepatic lipase (HL) and cholesteryl ester transfer protein (CETP), into LDL particles or alternatively directly cleared by the liver. Two proteins, lipase maturation factor 1 (LMF1) and glycosylphosphatidylinositol-anchored high density lipoprotein binding protein 1 (GPIHBP1), have been recently identified and have revised our current understanding of LPL maturation and LPL-mediated lipolysis. Moreover, new insights have been gained with respect to hepatic remnant clearance using genetically modified mice targeting the sulfation of HSPGs and even deletion of the most abundant heparan sulfate proteoglycan: syndecan1. In this review, we will provide an overview of novel data on both peripheral TG hydrolysis and hepatic remnant clearance that will improve our knowledge of plasma triglyceride metabolism.
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Affiliation(s)
- Geesje M Dallinga-Thie
- Department of Experimental Vascular Medicine, Academic Medical Center, Amsterdam, The Netherlands.
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270
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Cefalù AB, Noto D, Arpi ML, Yin F, Spina R, Hilden H, Barbagallo CM, Carroccio A, Tarugi P, Squatrito S, Vigneri R, Taskinen MR, Péterfy M, Averna MR. Novel LMF1 nonsense mutation in a patient with severe hypertriglyceridemia. J Clin Endocrinol Metab 2009; 94:4584-90. [PMID: 19820022 PMCID: PMC2819827 DOI: 10.1210/jc.2009-0594] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Lipase maturation factor 1 (LMF1) gene is a novel candidate gene in severe hypertriglyceridemia. Lmf1 is involved in the maturation of lipoprotein lipase (LPL) and hepatic lipase in endoplasmic reticulum. To date only one patient with severe hypertriglyceridemia and related disorders was found to be homozygous for a nonsense mutation in LMF1 gene (Y439X). OBJECTIVE The objective of the study was to investigate LMF1 gene in hypertriglyceridemic patients in whom mutations in LPL, APOC2, and APOA5 genes had been excluded. RESULTS The resequencing of LMF1 gene led to the discovery of a novel homozygous nonsense mutation in one patient with severe hypertriglyceridemia and recurrent episodes of pancreatitis. The mutation causes a G>A substitution in exon 9 (c.1395G>A), leading to a premature stop codon (W464X). LPL activity and mass were reduced by 76 and 50%, respectively, compared with normolipidemic controls. The proband over the years has shown a good response to treatment. The proband's son, heterozygous for the W464X, shows normal plasma triglyceride levels. CONCLUSIONS We identified the second novel pathogenic mutation in LMF1 gene in a patient with severe hypertriglyceridemia. LPL deficiency in our patient was milder than in the carrier of the Y439X previously described.
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Affiliation(s)
- Angelo B Cefalù
- Department of Clinical Medicine and Emerging Diseases, University of Palermo, 90127 Palermo, Italy
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271
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Watson E, Fargali S, Okamoto H, Sadahiro M, Gordon RE, Chakraborty T, Sleeman MW, Salton SR. Analysis of knockout mice suggests a role for VGF in the control of fat storage and energy expenditure. BMC PHYSIOLOGY 2009; 9:19. [PMID: 19863797 PMCID: PMC2774661 DOI: 10.1186/1472-6793-9-19] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Accepted: 10/28/2009] [Indexed: 11/29/2022]
Abstract
Background Previous studies of mixed background mice have demonstrated that targeted deletion of Vgf produces a lean, hypermetabolic mouse that is resistant to diet-, lesion-, and genetically-induced obesity. To investigate potential mechanism(s) and site(s) of action of VGF, a neuronal and endocrine secreted protein and neuropeptide precursor, we further analyzed the metabolic phenotypes of two independent VGF knockout lines on C57Bl6 backgrounds. Results Unlike hyperactive VGF knockout mice on a mixed C57Bl6-129/SvJ background, homozygous mutant mice on a C57Bl6 background were hypermetabolic with similar locomotor activity levels to Vgf+/Vgf+ mice, during day and night cycles, indicating that mechanism(s) other than hyperactivity were responsible for their increased energy expenditure. In Vgf-/Vgf- knockout mice, morphological analysis of brown and white adipose tissues (BAT and WAT) indicated decreased fat storage in both tissues, and decreased adipocyte perimeter and area in WAT. Changes in gene expression measured by real-time RT-PCR were consistent with increased fatty acid oxidation and uptake in BAT, and increased lipolysis, decreased lipogenesis, and brown adipocyte differentiation in WAT, suggesting that increased sympathetic nervous system activity in Vgf-/Vgf- mice may be associated with or responsible for alterations in energy expenditure and fat storage. In addition, uncoupling protein 1 (UCP1) and UCP2 protein levels, mitochondrial number, and mitochondrial cristae density were upregulated in Vgf-/Vgf- BAT. Using immunohistochemical and histochemical techniques, we detected VGF in nerve fibers innervating BAT and Vgf promoter-driven reporter expression in cervical and thoracic spinal ganglia that project to and innervate the chest wall and tissues including BAT. Moreover, VGF peptide levels were quantified by radioimmunoassay in BAT, and were found to be down-regulated by a high fat diet. Lastly, despite being hypermetabolic, VGF knockout mice were cold intolerant. Conclusion We propose that VGF and/or VGF-derived peptides modulate sympathetic outflow pathways to regulate fat storage and energy expenditure.
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Affiliation(s)
- Elizabeth Watson
- Department of Neuroscience, Mount Sinai School of Medicine, New York, NY, USA.
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272
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Mamedova LK, Robbins K, Johnson BJ, Bradford BJ. Tissue expression of angiopoietin-like protein 4 in cattle. J Anim Sci 2009; 88:124-30. [PMID: 19783696 DOI: 10.2527/jas.2009-2258] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Angiopoietin-like protein 4 (ANGPTL4; also known as fasting-induced adipose factor) is a plasma protein that stimulates oxidation of fatty acids and inhibits fat accumulation. The gastrointestinal tract appears to play an important role in regulating plasma ANGPTL4 concentration in some situations and may be influenced by microbes within the gastrointestinal tract. Our aim was to determine which tissues express ANGPTL4 in the bovine. Rumen, omasum, abomasum, duodenum, jejunum, ileum, colon, pancreas, liver, and subcutaneous adipose tissue samples were collected postmortem from 2 steers. Abundance of ANGPTL4 messenger RNA was quantified by quantitative real-time PCR, and was most abundant in liver and adipose tissue (P < 0.05). We also detected ANGPTL4 messenger RNA throughout the gastrointestinal tract, although its abundance was approximately 10% of that found in liver and adipose tissue. Western blot analysis revealed that ANGPTL4 protein was most abundant in liver and adipose tissue (P < 0.05), but omasal, abomasal, and ileal samples contained at least 60% as much ANGPTL4 protein as the liver and adipose tissue samples, and the protein was detected in all tissues. Finally, cross-sections of the liver, pancreas, and rumen wall were used for indirect immunofluorescent detection of ANGPTL4. Despite the low abundance of ANGPTL4 measured by quantitative real-time PCR and Western blot in ruminal tissue, immunofluorescence demonstrated that expression of ANGPTL4 in ruminal epithelial cells was equivalent to or greater than that in liver hepatocytes. These findings indicate that, as in other species studied, liver and adipose tissue are key sources of ANGPTL4 in cattle. However, the protein was also highly abundant in ruminal epithelium, making it possible that commensal microbes may influence ANGPTL4 synthesis and secretion in the ruminant gastrointestinal tract.
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Affiliation(s)
- L K Mamedova
- Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506, USA
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273
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Affiliation(s)
- Sander Kersten
- Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University.
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274
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Abstract
Lipoprotein lipase (LPL) is a multifunctional enzyme produced by many tissues, including adipose tissue, cardiac and skeletal muscle, islets, and macrophages. LPL is the rate-limiting enzyme for the hydrolysis of the triglyceride (TG) core of circulating TG-rich lipoproteins, chylomicrons, and very low-density lipoproteins (VLDL). LPL-catalyzed reaction products, fatty acids, and monoacylglycerol are in part taken up by the tissues locally and processed differentially; e.g., they are stored as neutral lipids in adipose tissue, oxidized, or stored in skeletal and cardiac muscle or as cholesteryl ester and TG in macrophages. LPL is regulated at transcriptional, posttranscriptional, and posttranslational levels in a tissue-specific manner. Nutrient states and hormonal levels all have divergent effects on the regulation of LPL, and a variety of proteins that interact with LPL to regulate its tissue-specific activity have also been identified. To examine this divergent regulation further, transgenic and knockout murine models of tissue-specific LPL expression have been developed. Mice with overexpression of LPL in skeletal muscle accumulate TG in muscle, develop insulin resistance, are protected from excessive weight gain, and increase their metabolic rate in the cold. Mice with LPL deletion in skeletal muscle have reduced TG accumulation and increased insulin action on glucose transport in muscle. Ultimately, this leads to increased lipid partitioning to other tissues, insulin resistance, and obesity. Mice with LPL deletion in the heart develop hypertriglyceridemia and cardiac dysfunction. The fact that the heart depends increasingly on glucose implies that free fatty acids are not a sufficient fuel for optimal cardiac function. Overall, LPL is a fascinating enzyme that contributes in a pronounced way to normal lipoprotein metabolism, tissue-specific substrate delivery and utilization, and the many aspects of obesity and other metabolic disorders that relate to energy balance, insulin action, and body weight regulation.
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Affiliation(s)
- Hong Wang
- Division of Endocrinology, Metabolism and Diabetes, University of Colorado Denver Anschutz Medical Campus, Aurora, Colorado 80045, USA
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275
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Trost Z, Sok M, Marc J, Cerne D. Increased lipoprotein lipase activity in non-small cell lung cancer tissue predicts shorter patient survival. Arch Med Res 2009; 40:364-8. [PMID: 19766899 DOI: 10.1016/j.arcmed.2009.05.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2008] [Accepted: 04/27/2009] [Indexed: 11/15/2022]
Abstract
BACKGROUND AND AIMS Cumulative evidence suggests the involvement of lipoprotein lipase (LPL) in tumor progression. We tested the hypothesis that increased LPL activity in resectable non-small cell lung cancer (NSCLC) tissue and the increased LPL gene expression in the surrounding non-cancer lung tissue found in our previous study are predictors of patient survival. METHODS Forty two consecutive patients with resected NSCLC were enrolled in the study. Paired samples of lung cancer tissue and adjacent non-cancer lung tissue were collected from resected specimens for baseline LPL activity and gene expression estimation. During a 4-year follow-up, 21 patients died due to tumor progression. One patient died due to a non-cancer reason and was not included in Cox regression analysis. RESULTS High LPL activity in cancer tissue (relative to the adjacent non-cancer lung tissue) predicted shorter survival, independently of standard prognostic factors (p=0.003). High gene expression in the non-cancer lung tissue surrounding the tumor had no predictive value. CONCLUSIONS Our study further underlines the involvement of cancer tissue LPL activity in tumor progression.
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Affiliation(s)
- Zoran Trost
- Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia
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276
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Biesecker LG, Mullikin JC, Facio FM, Turner C, Cherukuri PF, Blakesley RW, Bouffard GG, Chines PS, Cruz P, Hansen NF, Teer JK, Maskeri B, Young AC, Manolio TA, Wilson AF, Finkel T, Hwang P, Arai A, Remaley AT, Sachdev V, Shamburek R, Cannon RO, Green ED. The ClinSeq Project: piloting large-scale genome sequencing for research in genomic medicine. Genome Res 2009; 19:1665-74. [PMID: 19602640 DOI: 10.1101/gr.092841.109] [Citation(s) in RCA: 214] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
ClinSeq is a pilot project to investigate the use of whole-genome sequencing as a tool for clinical research. By piloting the acquisition of large amounts of DNA sequence data from individual human subjects, we are fostering the development of hypothesis-generating approaches for performing research in genomic medicine, including the exploration of issues related to the genetic architecture of disease, implementation of genomic technology, informed consent, disclosure of genetic information, and archiving, analyzing, and displaying sequence data. In the initial phase of ClinSeq, we are enrolling roughly 1000 participants; the evaluation of each includes obtaining a detailed family and medical history, as well as a clinical evaluation. The participants are being consented broadly for research on many traits and for whole-genome sequencing. Initially, Sanger-based sequencing of 300-400 genes thought to be relevant to atherosclerosis is being performed, with the resulting data analyzed for rare, high-penetrance variants associated with specific clinical traits. The participants are also being consented to allow the contact of family members for additional studies of sequence variants to explore their potential association with specific phenotypes. Here, we present the general considerations in designing ClinSeq, preliminary results based on the generation of an initial 826 Mb of sequence data, the findings for several genes that serve as positive controls for the project, and our views about the potential implications of ClinSeq. The early experiences with ClinSeq illustrate how large-scale medical sequencing can be a practical, productive, and critical component of research in genomic medicine.
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Affiliation(s)
- Leslie G Biesecker
- National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
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277
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Sonnenburg WK, Yu D, Lee EC, Xiong W, Gololobov G, Key B, Gay J, Wilganowski N, Hu Y, Zhao S, Schneider M, Ding ZM, Zambrowicz BP, Landes G, Powell DR, Desai U. GPIHBP1 stabilizes lipoprotein lipase and prevents its inhibition by angiopoietin-like 3 and angiopoietin-like 4. J Lipid Res 2009; 50:2421-9. [PMID: 19542565 DOI: 10.1194/jlr.m900145-jlr200] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Glycosylphosphatidylinositol-anchored HDL-binding protein (GPIHBP1) binds both LPL and chylomicrons, suggesting that GPIHBP1 is a platform for LPL-dependent processing of triglyceride (TG)-rich lipoproteins. Here, we investigated whether GPIHBP1 affects LPL activity in the absence and presence of LPL inhibitors angiopoietin-like (ANGPTL)3 and ANGPTL4. Like heparin, GPIHBP1 stabilized but did not activate LPL. ANGPTL4 potently inhibited nonstabilized LPL as well as heparin-stabilized LPL but not GPIHBP1-stabilized LPL. Like ANGPTL4, ANGPTL3 inhibited nonstabilized LPL but not GPIHBP1-stabilized LPL. ANGPTL3 also inhibited heparin-stabilized LPL but with less potency than nonstabilized LPL. Consistent with these in vitro findings, fasting serum TGs of Angptl4(-/-)/Gpihbp1(-/-) mice were lower than those of Gpihbp1(-/-) mice and approached those of wild-type littermates. In contrast, serum TGs of Angptl3(-/-)/Gpihbp1(-/-) mice were only slightly lower than those of Gpihbp1(-/-) mice. Treating Gpihbp1(-/-) mice with ANGPTL4- or ANGPTL3-neutralizing antibodies recapitulated the double knockout phenotypes. These data suggest that GPIHBP1 functions as an LPL stabilizer. Moreover, therapeutic agents that prevent LPL inhibition by ANGPTL4 or, to a lesser extent, ANGPTL3, may benefit individuals with hyperlipidemia caused by gene mutations associated with decreased LPL stability.
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Affiliation(s)
- William K Sonnenburg
- Department of Biotherapeutics, Lexicon Pharmaceuticals, Inc., 8800 Technology Forest Place, The Woodlands, TX 77381, USA
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278
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Lee EC, Desai U, Gololobov G, Hong S, Feng X, Yu XC, Gay J, Wilganowski N, Gao C, Du LL, Chen J, Hu Y, Zhao S, Kirkpatrick L, Schneider M, Zambrowicz BP, Landes G, Powell DR, Sonnenburg WK. Identification of a new functional domain in angiopoietin-like 3 (ANGPTL3) and angiopoietin-like 4 (ANGPTL4) involved in binding and inhibition of lipoprotein lipase (LPL). J Biol Chem 2009; 284:13735-13745. [PMID: 19318355 PMCID: PMC2679475 DOI: 10.1074/jbc.m807899200] [Citation(s) in RCA: 127] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2008] [Revised: 03/23/2009] [Indexed: 11/06/2022] Open
Abstract
Angiopoietin-like 3 (ANGPTL3) and angiopoietin-like 4 (ANGPTL4) are secreted proteins that regulate triglyceride (TG) metabolism in part by inhibiting lipoprotein lipase (LPL). Recently, we showed that treatment of wild-type mice with monoclonal antibody (mAb) 14D12, specific for ANGPTL4, recapitulated the Angptl4 knock-out (-/-) mouse phenotype of reduced serum TG levels. In the present study, we mapped the region of mouse ANGPTL4 recognized by mAb 14D12 to amino acids Gln(29)-His(53), which we designate as specific epitope 1 (SE1). The 14D12 mAb prevented binding of ANGPTL4 with LPL, consistent with its ability to neutralize the LPL-inhibitory activity of ANGPTL4. Alignment of all angiopoietin family members revealed that a sequence similar to ANGPTL4 SE1 was present only in ANGPTL3, corresponding to amino acids Glu(32)-His(55). We produced a mouse mAb against this SE1-like region in ANGPTL3. This mAb, designated 5.50.3, inhibited the binding of ANGPTL3 to LPL and neutralized ANGPTL3-mediated inhibition of LPL activity in vitro. Treatment of wild-type as well as hyperlipidemic mice with mAb 5.50.3 resulted in reduced serum TG levels, recapitulating the lipid phenotype found in Angptl3(-/-) mice. These results show that the SE1 region of ANGPTL3 and ANGPTL4 functions as a domain important for binding LPL and inhibiting its activity in vitro and in vivo. Moreover, these results demonstrate that therapeutic antibodies that neutralize ANGPTL4 and ANGPTL3 may be useful for treatment of some forms of hyperlipidemia.
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Affiliation(s)
- E-Chiang Lee
- Departments of Biotherapeutics Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381.
| | - Urvi Desai
- Pharmaceutical Biology Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381
| | - Gennady Gololobov
- Departments of Biotherapeutics Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381
| | - Seokjoo Hong
- Departments of Biotherapeutics Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381
| | - Xiao Feng
- Departments of Biotherapeutics Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381
| | - Xuan-Chuan Yu
- Pharmaceutical Discovery Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381
| | - Jason Gay
- Pharmaceutical Biology Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381
| | - Nat Wilganowski
- Pharmaceutical Biology Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381
| | - Cuihua Gao
- Departments of Biotherapeutics Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381
| | - Ling-Ling Du
- Departments of Biotherapeutics Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381
| | - Joan Chen
- Departments of Biotherapeutics Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381
| | - Yi Hu
- Molecular Biology, Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381
| | - Sharon Zhao
- Molecular Biology, Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381
| | - Laura Kirkpatrick
- Departments of Biotherapeutics Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381
| | - Matthias Schneider
- Pharmaceutical Biology Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381
| | - Brian P Zambrowicz
- Departments of Biotherapeutics Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381; Pharmaceutical Biology Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381; Pharmaceutical Discovery Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381; Molecular Biology, Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381
| | - Greg Landes
- Departments of Biotherapeutics Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381
| | - David R Powell
- Pharmaceutical Biology Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381
| | - William K Sonnenburg
- Departments of Biotherapeutics Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381.
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279
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Lkhagvadorj S, Qu L, Cai W, Couture OP, Barb CR, Hausman GJ, Nettleton D, Anderson LL, Dekkers JCM, Tuggle CK. Microarray gene expression profiles of fasting induced changes in liver and adipose tissues of pigs expressing the melanocortin-4 receptor D298N variant. Physiol Genomics 2009; 38:98-111. [PMID: 19366786 DOI: 10.1152/physiolgenomics.90372.2008] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Transcriptional profiling coupled with blood metabolite analyses were used to identify porcine genes and pathways that respond to a fasting treatment or to a D298N missense mutation in the melanocortin-4 receptor (MC4R) gene. Gilts (12 homozygous for D298 and 12 homozygous for N298) were either fed ad libitum or fasted for 3 days. Fasting decreased body weight, backfat, and serum urea concentration and increased serum nonesterified fatty acid. In response to fasting, 7,029 genes in fat and 1,831 genes in liver were differentially expressed (DE). MC4R genotype did not significantly affect gene expression, body weight, backfat depth, or any measured serum metabolite concentration. Pathway analyses of fasting-induced DE genes indicated that lipid and steroid synthesis was downregulated in both liver and fat. Fasting increased expression of genes involved in glucose sparing pathways, such as oxidation of amino acids and fatty acids in liver, and in extracellular matrix pathways, such as cell adhesion and adherens junction in fat. Additionally, we identified DE transcription factors (TF) that regulate many DE genes. This confirms the involvement of TF, such as PPARG, SREBF1, and CEBPA, which are known to regulate the fasting response, and implicates additional TF, such as ESR1. Interestingly, ESR1 controls several fasting induced genes in fat that are involved in cell matrix morphogenesis. Our findings indicate a transcriptional response to fasting in two key metabolic tissues of pigs, which was corroborated by changes in blood metabolites, and the involvement of novel putative transcriptional regulators in the immediate adaptive response to fasting.
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Affiliation(s)
- Sender Lkhagvadorj
- Department of Animal Science, Iowa State University, Ames, Iowa 50011-3150, USA
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280
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Kersten S, Lichtenstein L, Steenbergen E, Mudde K, Hendriks HFJ, Hesselink MK, Schrauwen P, Müller M. Caloric restriction and exercise increase plasma ANGPTL4 levels in humans via elevated free fatty acids. Arterioscler Thromb Vasc Biol 2009; 29:969-74. [PMID: 19342599 DOI: 10.1161/atvbaha.108.182147] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Plasma lipoprotein levels are determined by the balance between lipoprotein production and clearance. Recently, angiopoietin-like protein 4 (ANGPTL4) was uncovered as a novel endocrine factor that potently raises plasma triglyceride levels by inhibiting triglyceride clearance. However, very little is known about ANGPTL4 in human. Here we set out to identify physiological determinants of plasma ANGPTL4 levels in humans, focusing on the effect of energy restriction and plasma FFAs. METHODS AND RESULTS We developed an ELISA for quantitative measurement of ANGPTL4 in human plasma. Using this assay we found major variations in baseline plasma ANGPTL4 levels between individuals. Within an individual, plasma ANGPTL4 levels remain stable throughout the day but increase significantly in response to long-term fasting, chronic caloric restriction, and endurance exercise. Intralipid injection as well as treatment with a beta-adrenergic agonist, both of which lead to elevated plasma FFA levels, increased plasma ANGPTL4 levels compared to control treatment. Fatty acids markedly induced ANGPTL4 gene expression in rat hepatoma FAO cells, human primary myocytes, and mouse intestinal MSIE cells. CONCLUSIONS In conclusion, our results show that plasma ANGPTL4 levels are increased by fasting, caloric restriction, and exercise, which is likely mediated by elevated plasma FFAs.
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Affiliation(s)
- Sander Kersten
- Nutrigenomics Consortium, TI Food and Nutrition, Wageningen, The Netherlands.
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281
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Yin W, Romeo S, Chang S, Grishin NV, Hobbs HH, Cohen JC. Genetic variation in ANGPTL4 provides insights into protein processing and function. J Biol Chem 2009; 284:13213-22. [PMID: 19270337 PMCID: PMC2676053 DOI: 10.1074/jbc.m900553200] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Angiopoietin-like protein 4 (ANGPTL4) is a secreted protein that modulates
the disposition of circulating triglycerides (TG) by inhibiting lipoprotein
lipase (LPL). Here we examine the steps involved in the synthesis and
post-translational processing of ANGPTL4, and the effects of a naturally
occurring sequence variant (E40K) that is associated with lower plasma TG
levels in humans. Expression of the wild-type and mutant proteins in HEK-293A
cells indicated that ANGPTL4 formed dimers and tetramers in cells prior to
secretion and cleavage of the protein. After cleavage at a canonical
proprotein convertase cleavage site (161RRKR164), the
oligomeric structure of the N-terminal domain was retained whereas the
C-terminal fibrinogen-like domain dissociated into monomers. Inhibition of
cleavage did not interfere with oligomerization of ANGPTL4 or with its ability
to inhibit LPL, whereas mutations that prevented oligomerization severely
compromised the capacity of the protein to inhibit LPL. ANGPTL4 containing the
E40K substitution was synthesized and processed normally, but no monomers or
oligomers of the N-terminal fragments accumulated in the medium; medium from
these cells failed to inhibit LPL activity. Parallel experiments performed in
mice recapitulated these results. Our findings indicate that oligomerization,
but not cleavage, of ANGPTL4 is required for LPL inhibition, and that the E40K
substitution destabilizes the protein after secretion, preventing the
extracellular accumulation of oligomers and abolishing the ability of the
protein to inhibit LPL activity.
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Affiliation(s)
- Wu Yin
- Eugene McDermott Center for Human Growth and Development, Department of Molecular Genetics, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-8591, USA
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282
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Abstract
The treatment of elevated levels of low-density lipoprotein cholesterol is standard medical practice supported by conclusive outcome data. Less definitive information exists for hypertriglyceridemia. Only in the setting of severe hyperchylomicronemia is the benefit of triglyceride lowering clear: it is a means to reduce the risk of pancreatitis. The relationship of triglycerides and cardiovascular disease is still unclear. Moreover, the cardiovascular benefits of reducing triglycerides and of using triglyceride-lowering medications remain unproved. Nonetheless it has become almost standard to reduce the levels of triglyceride-rich lipoproteins that are a major component of plasma non-high-density lipoprotein cholesterol.
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Affiliation(s)
- Ira J Goldberg
- Division of Preventive Medicine and Nutrition, Department of Medicine, Columbia University College of Physicians and Surgeons, 630 West 168th Street, New York, NY10032, USA.
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283
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Yau MH, Wang Y, Lam KSL, Zhang J, Wu D, Xu A. A highly conserved motif within the NH2-terminal coiled-coil domain of angiopoietin-like protein 4 confers its inhibitory effects on lipoprotein lipase by disrupting the enzyme dimerization. J Biol Chem 2009; 284:11942-52. [PMID: 19246456 DOI: 10.1074/jbc.m809802200] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lipoprotein lipase (LPL) is a principal enzyme responsible for the clearance of chylomicrons and very low density lipoproteins from the bloodstream. Two members of the Angptl (angiopoietin-like protein) family, namely Angptl3 and Angptl4, have been shown to inhibit LPL activity in vitro and in vivo. Here, we further investigated the structural basis underlying the LPL inhibition by Angptl3 and Angptl4. By multiple sequence alignment analysis, we have identified a highly conserved 12-amino acid consensus motif that is present within the coiled-coil domain (CCD) of both Angptl3 and Angptl4, but not other members of the Angptl family. Substitution of the three polar amino acid residues (His(46), Gln(50), and Gln(53)) within this motif with alanine abolishes the inhibitory effect of Angptl4 on LPL in vitro and also abrogates the ability of Angptl4 to elevate plasma triglyceride levels in mice. The CCD of Angptl4 interacts with LPL and converts the catalytically active dimers of LPL to its inactive monomers, whereas the mutant protein with the three polar amino acids being replaced by alanine loses such a property. Furthermore, a synthetic peptide consisting of the 12-amino acid consensus motif is sufficient to inhibit LPL activity, although the potency is much lower than the recombinant CCD of Angptl4. In summary, our data suggest that the 12-amino acid consensus motif within the CCD of Angptl4, especially the three polar residues within this motif, is responsible for its interaction with and inhibition of LPL by blocking the enzyme dimerization.
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Affiliation(s)
- Ming-Hon Yau
- Department of Medicine, Research Centre of Heart, Brain, Hormone and Healthy Aging, and Department of Pharmacology and Pharmacy, University of Hong Kong, Hong Kong
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284
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Adachi H, Fujiwara Y, Kondo T, Nishikawa T, Ogawa R, Matsumura T, Ishii N, Nagai R, Miyata K, Tabata M, Motoshima H, Furukawa N, Tsuruzoe K, Kawashima J, Takeya M, Yamashita S, Koh GY, Nagy A, Suda T, Oike Y, Araki E. Angptl 4 deficiency improves lipid metabolism, suppresses foam cell formation and protects against atherosclerosis. Biochem Biophys Res Commun 2009; 379:806-11. [DOI: 10.1016/j.bbrc.2008.12.018] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Accepted: 12/05/2008] [Indexed: 12/21/2022]
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285
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Effect of plasma triglyceride metabolism on lipid storage in adipose tissue: studies using genetically engineered mouse models. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:479-85. [PMID: 19168150 DOI: 10.1016/j.bbalip.2008.12.015] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2008] [Revised: 12/11/2008] [Accepted: 12/23/2008] [Indexed: 01/15/2023]
Abstract
The obesity epidemic is associated with an increased incidence of type 2 diabetes, cardiovascular morbidity and various types of cancer. A better insight into the molecular mechanisms that underlie adipogenesis and obesity may result in novel therapeutic handles to fight obesity and these associated diseases. Adipogenesis is determined by the balance between uptake of fatty acids (FA) from plasma into adipocytes, intracellular FA oxidation versus esterification of FA into triglycerides (TG), lipolysis of TG by intracellular lipases, and secretion of FA from adipocytes. Here, we review the mechanisms that are specifically involved in the entry of FA into adipose tissue. In plasma, these originating FA are either present as TG within apoB-containing lipoproteins (i.e. chylomicrons and VLDL) or as free FA bound to albumin. Kinetic studies, however, have revealed that TG are the major source of FA entering adipose tissue, both in the fed and fasted condition. In fact, studies with genetically engineered mice have revealed that the activity of lipoprotein lipase (LPL) is a major determinant for the development of obesity. As a general rule, high fat diet-induced adipogenesis is aggravated by stimulated LPL activity (e.g. by adipose tissue-specific overexpression of LPL or deficiency for apoCIII), and attenuated by inhibited LPL activity (e.g. by adipose-specific deficiency for LPL, overexpression of apoCI or angptl4, or by deficiency for apoE or the VLDL receptor). In addition, we describe that the trans-membrane transport of FA and cytoplasmic binding of FA in adipocytes can also dramatically affect adipogenesis. The relevance of these findings for human pathophysiology is discussed.
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286
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Romeo S, Yin W, Kozlitina J, Pennacchio LA, Boerwinkle E, Hobbs HH, Cohen JC. Rare loss-of-function mutations in ANGPTL family members contribute to plasma triglyceride levels in humans. J Clin Invest 2008; 119:70-9. [PMID: 19075393 DOI: 10.1172/jci37118] [Citation(s) in RCA: 199] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Accepted: 11/05/2008] [Indexed: 01/18/2023] Open
Abstract
The relative activity of lipoprotein lipase (LPL) in different tissues controls the partitioning of lipoprotein-derived fatty acids between sites of fat storage (adipose tissue) and oxidation (heart and skeletal muscle). Here we used a reverse genetic strategy to test the hypothesis that 4 angiopoietin-like proteins (ANGPTL3, -4, -5, and -6) play key roles in triglyceride (TG) metabolism in humans. We re-sequenced the coding regions of the genes encoding these proteins and identified multiple rare nonsynonymous (NS) sequence variations that were associated with low plasma TG levels but not with other metabolic phenotypes. Functional studies revealed that all mutant alleles of ANGPTL3 and ANGPTL4 that were associated with low plasma TG levels interfered either with the synthesis or secretion of the protein or with the ability of the ANGPTL protein to inhibit LPL. A total of 1% of the Dallas Heart Study population and 4% of those participants with a plasma TG in the lowest quartile had a rare loss-of-function mutation in ANGPTL3, ANGPTL4, or ANGPTL5. Thus, ANGPTL3, ANGPTL4, and ANGPTL5, but not ANGPTL6, play nonredundant roles in TG metabolism, and multiple alleles at these loci cumulatively contribute to variability in plasma TG levels in humans.
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Affiliation(s)
- Stefano Romeo
- Donald W. Reynolds Cardiovascular Clinical Research Center and Eugene McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX, USA
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287
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Goldberg IJ, Eckel RH, Abumrad NA. Regulation of fatty acid uptake into tissues: lipoprotein lipase- and CD36-mediated pathways. J Lipid Res 2008; 50 Suppl:S86-90. [PMID: 19033209 DOI: 10.1194/jlr.r800085-jlr200] [Citation(s) in RCA: 279] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Cells obtain FAs either from LPL-catalyzed hydrolysis of lipoprotein triglyceride or from unesterified FFAs associated with albumin. LPL also influences uptake of esterified lipids such as cholesteryl and retinyl esters that are not hydrolyzed in the plasma. This process might not involve LPL enzymatic activity. LPL is regulated by feeding/fasting, insulin, and exercise. Although a number of molecules may affect cellular uptake of FFAs, the best characterized is CD36. Genetic deletion of this multiligand receptor reduces FFA uptake into skeletal muscle, heart, and adipose tissue, and impairs intestinal chylomicron production and clearance of lipoproteins from the blood. CD36 is regulated by some of the same factors that regulate LPL, including insulin, muscle contraction, and fasting, in part, via ubiquitination. LPL and CD36 actions in various tissues coordinate biodistribution of fat-derived calories.
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Affiliation(s)
- Ira J Goldberg
- Division of Preventive Medicine and Nutrition, Department of Medicine, Columbia University, New York, NY, USA.
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288
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Shan L, Yu XC, Liu Z, Hu Y, Sturgis LT, Miranda ML, Liu Q. The angiopoietin-like proteins ANGPTL3 and ANGPTL4 inhibit lipoprotein lipase activity through distinct mechanisms. J Biol Chem 2008; 284:1419-24. [PMID: 19028676 DOI: 10.1074/jbc.m808477200] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Two members of the angiopoietin-like family of proteins, ANGPTL3 and ANGPTL4, have been shown to play important roles in modulating lipoprotein metabolism in the body. Both proteins were found to suppress lipoprotein lipase (LPL) activity in vitro as well as in vivo. However, their mechanisms of inhibition remained poorly understood. Using enzyme kinetic analysis with purified recombinant proteins, we have found key mechanistic differences between ANGPTL3 and ANGPTL4. ANGPTL3 reduced LPL catalytic activity but did not significantly alter its self-inactivation rate. In contrast, ANGPTL4 suppressed LPL by accelerating the irreversible inactivation of LPL. Furthermore, heparin was able to overcome the inhibitory effect of ANGPTL3 on LPL but not that of ANGPTL4. Site-directed mutagenesis demonstrated the critical function of Glu(40) in ANGPTL4. In contrast, when cysteine residues involved in disulfide bond formation were mutated to serines, ANGPTL4 retained its activity. Taken together, our data provide a more detailed view of the structure and mechanisms of these proteins. The finding that ANGPTL3 and ANGPTL4 inhibit LPL activity through distinct mechanisms indicates that the two proteins play unique roles in modulation of lipid metabolism in vivo.
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Affiliation(s)
- Lu Shan
- Department of Pharmaceutical Discovery, Lexicon Pharmaceuticals, The Woodlands, Texas 77381, USA
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289
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Babin PJ, Gibbons GF. The evolution of plasma cholesterol: direct utility or a "spandrel" of hepatic lipid metabolism? Prog Lipid Res 2008; 48:73-91. [PMID: 19049814 DOI: 10.1016/j.plipres.2008.11.002] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Revised: 11/06/2008] [Accepted: 11/07/2008] [Indexed: 02/07/2023]
Abstract
Fats provide a concentrated source of energy for multicellular organisms. The efficient transport of fats through aqueous biological environments raises issues concerning effective delivery to target tissues. Furthermore, the utilization of fatty acids presents a high risk of cytotoxicity. Improving the efficiency of fat transport while simultaneously minimizing the cytotoxic risk confers distinct selective advantages. In humans, most of the plasma cholesterol is associated with low-density lipoprotein (LDL), a metabolic by-product of very-low-density lipoprotein (VLDL), which originates in the liver. However, the functions of VLDL are not clear. This paper reviews the evidence that LDL arose as a by-product during the natural selection of VLDL. The latter, in turn, evolved as a means of improving the efficiency of diet-derived fatty acid storage and utilization, as well as neutralizing the potential cytotoxicity of fatty acids while conserving their advantages as a concentrated energy source. The evolutionary biology of lipid transport processes has provided a fascinating insight into how and why these VLDL functions emerged during animal evolution. As causes of historical origin must be separated from current utilities, our spandrel-LDL theory proposes that LDL is a spandrel of VLDL selection, which appeared non-adaptively and may later have become crucial for vertebrate fitness.
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Affiliation(s)
- Patrick J Babin
- Université Bordeaux 1, Génomique et Physiologie des Poissons, UMR NuAGe, 33405 Talence, France
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290
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Chomel C, Cazes A, Faye C, Bignon M, Gomez E, Ardidie‐Robouant C, Barret A, Ricard‐Blum S, Muller L, Germain S, Monnot C. Interaction of the coiled‐coil domain with glycosaminoglycans protects angiopoietin‐like 4 from proteolysis and regulates its antiangiogenic activity. FASEB J 2008; 23:940-9. [DOI: 10.1096/fj.08-115170] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Clémence Chomel
- INSERM U833ParisFrance
- College de FranceExperimental Medicine UnitParisFrance
| | - Aurelie Cazes
- INSERM U833ParisFrance
- Service d'Anatomie PathologiqueHopital Europeen Georges PompidouParisFrance
- Facultede Médecine Paris DescartesParisFrance
| | - Clement Faye
- Institut de Biologie et Chimie des ProteinesUMR CNRS 5086, Université Claude Bernard Lyon 1LyonFrance
| | - Marine Bignon
- INSERM U833ParisFrance
- College de FranceExperimental Medicine UnitParisFrance
| | - Elisa Gomez
- INSERM U833ParisFrance
- College de FranceExperimental Medicine UnitParisFrance
| | | | - Alain Barret
- INSERM U833ParisFrance
- College de FranceExperimental Medicine UnitParisFrance
| | - Sylvie Ricard‐Blum
- Institut de Biologie et Chimie des ProteinesUMR CNRS 5086, Université Claude Bernard Lyon 1LyonFrance
| | - Laurent Muller
- INSERM U833ParisFrance
- College de FranceExperimental Medicine UnitParisFrance
| | - Stephane Germain
- INSERM U833ParisFrance
- College de FranceExperimental Medicine UnitParisFrance
- Service d'Hematologie Biologique AHopital Europeen Georges PompidouParisFrance
| | - Catherine Monnot
- INSERM U833ParisFrance
- College de FranceExperimental Medicine UnitParisFrance
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291
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Williams KJ. Molecular processes that handle -- and mishandle -- dietary lipids. J Clin Invest 2008; 118:3247-59. [PMID: 18830418 DOI: 10.1172/jci35206] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Overconsumption of lipid-rich diets, in conjunction with physical inactivity, disables and kills staggering numbers of people worldwide. Recent advances in our molecular understanding of cholesterol and triglyceride transport from the small intestine to the rest of the body provide a detailed picture of the fed/fasted and active/sedentary states. Key surprises include the unexpected nature of many pivotal molecular mediators, as well as their dysregulation - but possible reversibility - in obesity, diabetes, inactivity, and related conditions. These mechanistic insights provide new opportunities to correct dyslipoproteinemia, accelerated atherosclerosis, insulin resistance, and other deadly sequelae of overnutrition and underexertion.
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Affiliation(s)
- Kevin Jon Williams
- Division of Endocrinology, Diabetes, and Metabolic Diseases, Department of Medicine, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107-5005, USA.
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292
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Folsom AR, Peacock JM, Demerath E, Boerwinkle E. Variation in ANGPTL4 and risk of coronary heart disease: the Atherosclerosis Risk in Communities Study. Metabolism 2008; 57:1591-6. [PMID: 18940399 PMCID: PMC2707767 DOI: 10.1016/j.metabol.2008.06.016] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2008] [Accepted: 06/24/2008] [Indexed: 11/26/2022]
Abstract
An E40K loss-of-function variant in the ANGPTL4 gene is associated with substantially reduced plasma triglyceride levels in white persons, but its association with cardiovascular disease occurrence has not been reported. The prospective, population-based Atherosclerosis Risk in Communities Study measured the E40K ANGPTL4 variant in approximately 10000 white participants and determined its association with coronary heart disease (CHD) incidence (n = 1318 events) between 1987-1989 and 2004. Compared with noncarriers, carriers of 1 or 2 copies of the 40K variant (3.8% frequency) had a 19-mg/dL lower age- and sex-adjusted mean triglyceride level, 5-mg/dL lower low-density lipoprotein cholesterol, and 4-mg/dL higher high-density lipoprotein cholesterol. The age-, sex-, and field center-adjusted hazard ratio of CHD was 0.63 (95% confidence interval, 0.45-0.89). Adjustment for nonlipid confounding factors did not change this hazard ratio appreciably. Carriers also appeared to have reduced risk of incident stroke, prevalent peripheral artery disease, and carotid atherosclerosis; but these associations were based on few events among 40K carriers and were not statistically significant. In conclusion, in this prospective study, the 40K variant of ANGPTL4 appeared to confer reduced genetic risk for CHD.
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Affiliation(s)
- Aaron R Folsom
- Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, MN 55454, USA.
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293
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Talmud PJ, Smart M, Presswood E, Cooper JA, Nicaud V, Drenos F, Palmen J, Marmot MG, Boekholdt SM, Wareham NJ, Khaw KT, Kumari M, Humphries SE. ANGPTL4 E40K and T266M: effects on plasma triglyceride and HDL levels, postprandial responses, and CHD risk. Arterioscler Thromb Vasc Biol 2008; 28:2319-25. [PMID: 18974381 DOI: 10.1161/atvbaha.108.176917] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Angiopoietin-like 4 is a dual-function protein: an inhibitor of LPL, influencing plasma triglycerides (TGs), with angiogenic properties. We examined the association of common ANGPTL4 variants with CHD traits and risk in 5 studies (13,527 individuals). METHODS AND RESULTS The effects on plasma lipids of 6 tagging SNPs and the recently identified E40K were examined in a study of 2772 men. Only T266M (rs1044250, MAF=30%) and E40K (MAF=2%) were significantly associated with TG-lowering (-10.4%, P<0.004 and -20.4%, P<0.0001), respectively. T266M no longer showed significant associations when K40 carriers (K40+) were excluded (P=0.2). Combining data from 5 studies confirmed the TG-lowering effect of K40+ (weighted mean difference: -0.12 [95% CI -0.18, -0.05] mmol/L TG P=0.0001). Surprisingly, in the 3 prospective studies, the combined OR for CHD was 1.48 (1.11 to 1.96, P=0.007), independent of TG. In individuals with a paternal history of MI (n=332) T266M, but not E40K, showed effects on postprandial AUC TG and glucose (P=0.009 and P=0.017, respectively) compared to controls (n=370). CONCLUSIONS Although associated with an atheroprotective lipid profile, E40K was associated with increased CHD risk, suggesting Angptl4 influences parameters beyond lipid levels. T266M showed effects only under conditions of postprandial stress. The functionality of these potential "loss-of-function" variants needs validation.
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Affiliation(s)
- Philippa J Talmud
- Division of Cardiovascular Genetics, Department of Medicine, University College London Medical School, 5 University St, London WC1E 6JF, United Kingdom.
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294
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Cheng Y, Hauton D. Cold acclimation induces physiological cardiac hypertrophy and increases assimilation of triacylglycerol metabolism through lipoprotein lipase. Biochim Biophys Acta Mol Cell Biol Lipids 2008; 1781:618-26. [PMID: 18722549 PMCID: PMC2568868 DOI: 10.1016/j.bbalip.2008.07.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2008] [Revised: 07/15/2008] [Accepted: 07/15/2008] [Indexed: 12/24/2022]
Abstract
The contribution of triacylglycerol to energy provision in the hypertrophied heart, mediated through lipoprotein lipase (LPL) is largely unknown and the contribution of very-low-density lipoprotein (VLDL) receptor to control of LPL presentation at the endothelium is unclear. For isolated perfused rat hearts, cold acclimation (CA) induced volume-overload hypertrophy, with decreased developed pressure (P < 0.01), increased end-diastolic volume of the left ventricle (P < 0.001) and a loss of contractile reserve in response to dobutamine challenge (P < 0.01). Oleate utilisation by perfused hearts was unchanged by CA, however uptake of intralipid emulsion increased 3-fold (P < 0.01). CA increased the proportion of lipid deposited in tissue lipids from 10% in euthermic controls to 40% (P < 0.01) although the overall contribution of individual lipid classes was unaffected. Cold acclimation significantly increased heparin-releasable LPL (P < 0.05) and tissue residual LPL (P < 0.01). Western blot analysis indicated preserved expression of proteins coding for SERCA2, muscle-CPT1 and VLDL-receptor following CA, while AMPKα2 and phospho-AMPKα2 were unaffected. These observations indicate that for physiological hypertrophy AMPK phosphorylation does not mediate the enhanced translocation of LPL to cardiac endothelium.
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Affiliation(s)
- Y Cheng
- Department of Physiology, Division of Medical Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
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295
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Li M, Zhu L, Li X, Shuai S, Teng X, Xiao H, Li Q, Chen L, Guo Y, Wang J. Expression profiling analysis for genes related to meat quality and carcass traits during postnatal development of backfat in two pig breeds. ACTA ACUST UNITED AC 2008; 51:718-33. [PMID: 18677600 DOI: 10.1007/s11427-008-0090-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2007] [Accepted: 04/05/2008] [Indexed: 02/05/2023]
Abstract
The competitive equilibrium of fatty acid biosynthesis and oxidation in vivo determines porcine subcutaneous fat thickness (SFT) and intramuscular fat (IMF) content. Obese and lean-type pig breeds show obvious differences in adipose deposition; however, the molecular mechanism underlying this phenotypic variation remains unclear. We used pathway-focused oligo microarray studies to examine the expression changes of 140 genes associated with meat quality and carcass traits in backfat at five growth stages (1-5 months) of Landrace (a leaner, Western breed) and Taihu pigs (a fatty, indigenous, Chinese breed). Variance analysis (ANOVA) revealed that differences in the expression of 25 genes in Landrace pigs were significant (FDR adjusted permutation, P<0.05) among 5 growth stages. Gene class test (GCT) indicated that a gene-group was very significant between 2 pig breeds across 5 growth stages (P (ErmineJ)<0.01), which consisted of 23 genes encoding enzymes and regulatory proteins associated with lipid and steroid metabolism. These findings suggest that the distinct differences in fat deposition ability between Landrace and Taihu pigs may closely correlate with the expression changes of these genes. Clustering analysis revealed a very high level of significance (FDR adjusted, P<0.01) for 2 gene expression patterns in Landrace pigs and a high level of significance (FDR adjusted, P<0.05) for 2 gene expression patterns in Taihu pigs. Also, expression patterns of genes were more diversified in Taihu pigs than those in Landrace pigs, which suggests that the regulatory mechanism of micro-effect polygenes in adipocytes may be more complex in Taihu pigs than in Landrace pigs. Based on a dynamic Bayesian network (DBN) model, gene regulatory networks (GRNs) were reconstructed from time-series data for each pig breed. These two GRNs initially revealed the distinct differences in physiological and biochemical aspects of adipose metabolism between the two pig breeds; from these results, some potential key genes could be identified. Quantitative, real-time RT-PCR (QRT-PCR) was used to verify the microarray data for five modulated genes, and a good correlation between the two measures of expression was observed for both 2 pig breeds at different growth stages (R=0.874+/-0.071). These results highlight some possible candidate genes for porcine fat characteristics and provide some data on which to base further study of the molecular basis of adipose metabolism.
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Affiliation(s)
- Mingzhou Li
- College of Animal Science and Technology, Sichuan Agricultural University, Ya'an 625014, China
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296
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Franssen R, Visser ME, Kuivenhoven JA, Kastelein JJP, Dallinga-Thie GM, Stroes ESG. Role of lipoprotein lipase in triglyceride metabolism: potential therapeutic target. ACTA ACUST UNITED AC 2008. [DOI: 10.2217/17460875.3.4.385] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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297
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Lindegaard MLS, Nielsen LB. Maternal diabetes causes coordinated down-regulation of genes involved with lipid metabolism in the murine fetal heart. Metabolism 2008; 57:766-73. [PMID: 18502258 DOI: 10.1016/j.metabol.2008.01.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2007] [Accepted: 01/10/2008] [Indexed: 01/13/2023]
Abstract
Maternal diabetes is associated with increased transport of lipids to the fetus and increased risk of hypertrophic cardiomyopathy in the fetus. During fetal life, the heart normally has limited capacity to use lipids as fuel; and, at least in adults, cardiac lipid accumulation may lead to cardiomyopathy. Postnatally, lipid supply is increased when the offspring begins to suckle. We examined offspring from hypoinsulinemic Ins2(Akita) mice to assess whether maternal diabetes results in fetal myocardial hypertrophy and triglyceride accumulation and compared these with fetal hearts collected postnatally. On embryonic days 16 to 19, the fetal heart weight and triglyceride content were similar in offspring from Ins2(Akita) and nondiabetic wild-type mothers. The heart expression of lipid-metabolizing genes (peroxisomal proliferator-activated receptor alpha, lipoprotein lipase, fatty acid translocase, and fatty acid transport protein 1) was reduced in offspring from Ins2(Akita) mothers with high blood glucose levels and were closely intercorrelated, suggesting coordinated down-regulation. In contrast, on day 1 postnatally where the lipid availability to the heart is markedly increased, heart triglycerides and expression of several lipid-metabolizing genes (including lipoprotein lipase and fatty acid transport protein 1) were increased in offspring from wild-type mice. The results suggest that maternal type 1 diabetes mellitus in Ins2(Akita) mice does not cause cardiac hypertrophy or triglycerides accumulation in the fetal heart, possibly because of a coordinated down-regulation of genes controlling fatty acid uptake.
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298
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Zhang Z, Cao L, Li J, Liang X, Liu Y, Liu H, Du J, Qu Z, Cui M, Liu S, Gao L, Ma C, Zhang L, Han L, Sun W. Acquisition of anoikis resistance reveals a synoikis-like survival style in BEL7402 hepatoma cells. Cancer Lett 2008; 267:106-15. [PMID: 18433990 DOI: 10.1016/j.canlet.2008.03.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2007] [Revised: 03/04/2008] [Accepted: 03/10/2008] [Indexed: 10/22/2022]
Abstract
Resistance to anoikis is a hallmark of human malignancies. Our results showed that hepatoma cells resisted anoikis by non-proliferation, non-apoptosis and cell cycle arrest which were termed synoikis-like. These synoikis-like cells are more resistant to extracellular stimuli and could spontaneously attach and proliferate again under suitable conditions, which indicate a reversible property of these cells. Microarray expression profile reveals the change of molecules involved in the synoikis-like hepatoma cells and our data indicated that ANGPTL4 contributed to anoikis resistance of hepatoma cells. These results demonstrated that hepatoma cells might resist anoikis through a synoikis-like survival style, which may facilitate tumor metastasis.
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Affiliation(s)
- Zhiyong Zhang
- Department of Immunology, School of Medicine, Shandong University, Jinan 250012, China
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299
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Kuchtey J, Källberg ME, Gelatt KN, Rinkoski T, Komàromy AM, Kuchtey RW. Angiopoietin-like 7 secretion is induced by glaucoma stimuli and its concentration is elevated in glaucomatous aqueous humor. Invest Ophthalmol Vis Sci 2008; 49:3438-48. [PMID: 18421092 DOI: 10.1167/iovs.07-1347] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To investigate the possibility that Angiopoietin-like 7 (ANGPTL7) protein is involved in the pathogenesis of glaucoma. METHODS Primary human trabecular meshwork (TM) cells and corneoscleral explants were stimulated with either dexamethasone (DEX) or transforming growth factor beta (TGFbeta), and ANGPTL7 protein secreted into culture medium was determined by Western blot analysis. The effect of stable overexpression of ANGPTL7 in transfected immortalized TM cell lines on collagen expression was investigated by immunocytochemistry. Localization of ANGPTL7 protein in human eyes was determined by immunohistochemistry. The concentration of ANGPTL7 protein in aqueous humor (AH) from patients with glaucoma and control patients was compared by Western blot analysis. The beagle model of primary open-angle glaucoma (POAG) was used to correlate ANGPTL7 protein levels in canine AH with disease progression. RESULTS TGFbeta and DEX stimulated secretion of ANGPTL7 protein by TM cells and corneoscleral explants. Overexpression of ANGPTL7 by immortalized TM cell lines increased expression of type I collagen. Expression of ANGPTL7 protein was located in the corneal stroma, near the limbus, and throughout the sclera, with lower expression in the TM. In the lamina cribrosa, ANGPTL7 expression was associated with the cribriform plates. The concentration of ANGPTL7 protein was elevated in AH from patients with glaucoma and increased as disease progressed in POAG beagle dogs. CONCLUSIONS Induction of ANGPTL7 secretion by glaucoma stimuli and increased concentration of ANGPTL7 in glaucomatous AH suggest that ANGPTL7 is overexpressed in glaucoma. Since overexpression of ANGPTL7 increases collagen expression, a potential disease mechanism, ANGPTL7 could have a pathogenic role in glaucoma, and may serve as a potential therapeutic target.
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Affiliation(s)
- John Kuchtey
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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300
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Hato T, Tabata M, Oike Y. The role of angiopoietin-like proteins in angiogenesis and metabolism. Trends Cardiovasc Med 2008; 18:6-14. [PMID: 18206803 DOI: 10.1016/j.tcm.2007.10.003] [Citation(s) in RCA: 260] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2007] [Revised: 10/27/2007] [Accepted: 10/30/2007] [Indexed: 01/01/2023]
Abstract
Recently, a family of proteins structurally similar to the angiogenic regulating factors angiopoietins was identified and designated "angiopoietin-like proteins" (Angptls). Encoded by seven genes, Angptls 1 to 7 all possess an N-terminal coiled-coil domain and a C-terminal fibrinogen-like domain, both characteristic of angiopoietins. However, Angptls do not bind to either the angiopoietin receptor Tie2 or the related protein Tie1 and remain orphan ligands. Nonetheless, Angptls 1, 2, 3, 4, and Angptl6/angiopoietin-related growth factor function to regulate angiogenesis. Angptls 3, 4, and Angptl6/angiopoietin-related growth factor also appear to directly regulate lipid, glucose, and energy metabolism independently of angiogenic effects. Recently, several lines of evidence reveal differential roles of Angptl structural domains in both angiogenesis and metabolism. Here, we briefly review what is currently known about Angptls function.
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Affiliation(s)
- Tai Hato
- Laboratory of Vascular Biology and Metabolism, Center for Integrated Medical Research, Department of General Thoracic Surgery, Keio University, Shinjuku-ku, Tokyo 160-8582, Japan
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