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Gopinath V, Mariya Davis A, Menon TK, Raghavamenon AC. Alcohol promotes liver fibrosis in high fat diet induced diabetic rats. J Basic Clin Physiol Pharmacol 2024; 0:jbcpp-2024-0042. [PMID: 39023980 DOI: 10.1515/jbcpp-2024-0042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Accepted: 06/18/2024] [Indexed: 07/20/2024]
Abstract
OBJECTIVES Type 2 diabetes (T2DM) and alcoholism are considered to be lifestyle-associated independent risk factors in fatty liver diseases (FLD) mediated cirrhosis and hepatocellular carcinoma (HCC). A combined effect of both these conditions may exacerbate the pathological changes and a pre-clinical exploration of this is expected to provide a mechanical detail of the pathophysiology. The present study aims to understand the effect of alcohol on pre- diabetic and type 2 diabetic female Wistar rats. METHODS In this experimental study, 12 Wistar rats (180-220 g) were randomly assigned into three groups: Normal (fed normal rat chow), alcohol (20 %) fed diabetic (HFD + STZ), and pre-diabetic rats (HFD alone). After, two months of the experimental period, blood and liver tissues were collected lipid metabolic alteration, liver injury, and fibrosis were determined following biochemical and histological methods. Data were analyzed using one-way ANOVA and Dunnett's Post Hoc test. RESULTS Significant dyslipidemia was observed in the liver tissues of diabetic and pre-diabetic rats following alcohol ingestion. A significant (p<0.05) increase in lipid peroxidation status, and hepatic marker enzyme activities (p<0.0001) were observed in diabetic animals. In corroborating with these observations, hematoxylin and eosin staining of hepatic tissue revealed the presence of sinusoidal dilation along with heavily damaged hepatocytes and inflammatory cell infiltration. Further, significantly (p<0.001) increased hepatic hydroxyproline content and extended picrosirius red stained areas of collagen in liver tissue indicated initiation of fibrosis in alcohol-fed diabetic rats. CONCLUSIONS Overall, the results indicate that alcohol consumption in T2DM conditions is more deleterious than pre diabetic conditions in progressing to hepatic fibrosis.
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Affiliation(s)
- Veena Gopinath
- Department of Biochemistry, Amala Cancer Research Center (Recognized Centre of the University of Calicut), Thrissur, Kerala, India
| | - Aleena Mariya Davis
- Department of Biochemistry, Amala Cancer Research Center (Recognized Centre of the University of Calicut), Thrissur, Kerala, India
| | - Thara K Menon
- Department of Biotechnology, University of Calicut, Thenhipalam, Kerala, India
| | - Achuthan C Raghavamenon
- Department of Biochemistry, Amala Cancer Research Center (Recognized Centre of the University of Calicut), Thrissur, Kerala, India
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2
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Carulla P, Badia-Villanueva M, Civit S, Carrascal M, Abian J, Ricart-Jané D, Llobera M, Casanovas A, López-Tejero MD. The response to fasting and refeeding reveals functional regulation of lipoprotein lipase proteoforms. Front Physiol 2023; 14:1271149. [PMID: 37916217 PMCID: PMC10617031 DOI: 10.3389/fphys.2023.1271149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 10/04/2023] [Indexed: 11/03/2023] Open
Abstract
Lipoprotein lipase (LPL) is responsible for the intravascular catabolism of triglyceride-rich lipoproteins and plays a central role in whole-body energy balance and lipid homeostasis. As such, LPL is subject to tissue-specific regulation in different physiological conditions, but the mechanisms of this regulation remain incompletely characterized. Previous work revealed that LPL comprises a set of proteoforms with different isoelectric points, but their regulation and functional significance have not been studied thus far. Here we studied the distribution of LPL proteoforms in different rat tissues and their regulation under physiological conditions. First, analysis by two-dimensional electrophoresis and Western blot showed different patterns of LPL proteoforms (i.e., different pI or relative abundance of LPL proteoforms) in different rat tissues under basal conditions, which could be related to the tissue-specific regulation of the enzyme. Next, the comparison of LPL proteoforms from heart and brown adipose tissue between adults and 15-day-old rat pups, two conditions with minimal regulation of LPL in these tissues, yielded virtually the same tissue-specific patterns of LPL proteoforms. In contrast, the pronounced downregulation of LPL activity observed in white adipose tissue during fasting is accompanied by a prominent reconfiguration of the LPL proteoform pattern. Furthermore, refeeding reverts this downregulation of LPL activity and restores the pattern of LPL proteoforms in this tissue. Importantly, this reversible proteoform-specific regulation during fasting and refeeding indicates that LPL proteoforms are functionally diverse. Further investigation of potential differences in the functional properties of LPL proteoforms showed that all proteoforms exhibit lipolytic activity and have similar heparin-binding affinity, although other functional aspects remain to be investigated. Overall, this study demonstrates the ubiquity, differential distribution and specific regulation of LPL proteoforms in rat tissues and underscores the need to consider the existence of LPL proteoforms for a complete understanding of LPL regulation under physiological conditions.
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Affiliation(s)
- Pere Carulla
- Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona (UB), Barcelona, Spain
| | - Míriam Badia-Villanueva
- Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona (UB), Barcelona, Spain
| | - Sergi Civit
- Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona (UB), Barcelona, Spain
| | - Montserrat Carrascal
- Biological and Environmental Proteomics, Institute of Biomedical Research of Barcelona, Spanish National Research Council, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IIBB-CSIC/IDIBAPS), Barcelona, Spain
| | - Joaquin Abian
- Biological and Environmental Proteomics, Institute of Biomedical Research of Barcelona, Spanish National Research Council, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IIBB-CSIC/IDIBAPS), Barcelona, Spain
| | - David Ricart-Jané
- Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona (UB), Barcelona, Spain
| | - Miquel Llobera
- Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona (UB), Barcelona, Spain
| | - Albert Casanovas
- Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona (UB), Barcelona, Spain
| | - M. Dolores López-Tejero
- Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona (UB), Barcelona, Spain
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3
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Risti R, Gunn KH, Hiis-Hommuk K, Seeba NN, Karimi H, Villo L, Vendelin M, Neher SB, Lõokene A. Combined action of albumin and heparin regulates lipoprotein lipase oligomerization, stability, and ligand interactions. PLoS One 2023; 18:e0283358. [PMID: 37043509 PMCID: PMC10096250 DOI: 10.1371/journal.pone.0283358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 03/07/2023] [Indexed: 04/13/2023] Open
Abstract
Lipoprotein lipase (LPL), a crucial enzyme in the intravascular hydrolysis of triglyceride-rich lipoproteins, is a potential drug target for the treatment of hypertriglyceridemia. The activity and stability of LPL are influenced by a complex ligand network. Previous studies performed in dilute solutions suggest that LPL can appear in various oligomeric states. However, it was not known how the physiological environment, that is blood plasma, affects the action of LPL. In the current study, we demonstrate that albumin, the major protein component in blood plasma, has a significant impact on LPL stability, oligomerization, and ligand interactions. The effects induced by albumin could not solely be reproduced by the macromolecular crowding effect. Stabilization, isothermal titration calorimetry, and surface plasmon resonance studies revealed that albumin binds to LPL with affinity sufficient to form a complex in both the interstitial space and the capillaries. Negative stain transmission electron microscopy and raster image correlation spectroscopy showed that albumin, like heparin, induced reversible oligomerization of LPL. However, the albumin induced oligomers were structurally different from heparin-induced filament-like LPL oligomers. An intriguing observation was that no oligomers of either type were formed in the simultaneous presence of albumin and heparin. Our data also suggested that the oligomer formation protected LPL from the inactivation by its physiological regulator angiopoietin-like protein 4. The concentration of LPL and its environment could influence whether LPL follows irreversible inactivation and aggregation or reversible LPL oligomer formation, which might affect interactions with various ligands and drugs. In conclusion, the interplay between albumin and heparin could provide a mechanism for ensuring the dissociation of heparan sulfate-bound LPL oligomers into active LPL upon secretion into the interstitial space.
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Affiliation(s)
- Robert Risti
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia
| | - Kathryn H. Gunn
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Kristofer Hiis-Hommuk
- Laboratory of Systems Biology, Department of Cybernetics, Tallinn University of Technology, Tallinn, Estonia
| | - Natjan-Naatan Seeba
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia
| | - Hamed Karimi
- Laboratory of Systems Biology, Department of Cybernetics, Tallinn University of Technology, Tallinn, Estonia
| | - Ly Villo
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia
| | - Marko Vendelin
- Laboratory of Systems Biology, Department of Cybernetics, Tallinn University of Technology, Tallinn, Estonia
| | - Saskia B. Neher
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Aivar Lõokene
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia
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4
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Kersten S. The impact of fasting on adipose tissue metabolism. Biochim Biophys Acta Mol Cell Biol Lipids 2023; 1868:159262. [PMID: 36521736 DOI: 10.1016/j.bbalip.2022.159262] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 11/20/2022] [Accepted: 12/05/2022] [Indexed: 12/14/2022]
Abstract
Fasting and starvation were common occurrences during human evolution and accordingly have been an important environmental factor shaping human energy metabolism. Humans can tolerate fasting reasonably well through adaptative and well-orchestrated time-dependent changes in energy metabolism. Key features of the adaptive response to fasting are the breakdown of liver glycogen and muscle protein to produce glucose for the brain, as well as the gradual depletion of the fat stores, resulting in the release of glycerol and fatty acids into the bloodstream and the production of ketone bodies in the liver. In this paper, an overview is presented of our current understanding of the effects of fasting on adipose tissue metabolism. Fasting leads to reduced uptake of circulating triacylglycerols by adipocytes through inhibition of the activity of the rate-limiting enzyme lipoprotein lipase. In addition, fasting stimulates the degradation of stored triacylglycerols by activating the key enzyme adipose triglyceride lipase. The mechanisms underlying these events are discussed, with a special interest in insights gained from studies on humans. Furthermore, an overview is presented of the effects of fasting on other metabolic pathways in the adipose tissue, including fatty acid synthesis, glucose uptake, glyceroneogenesis, autophagy, and the endocrine function of adipose tissue.
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Affiliation(s)
- Sander Kersten
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition and Health, Wageningen University, the Netherlands.
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5
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Nyrén R, Scherman H, Axelsson J, Chang CL, Olivecrona G, Ericsson M. Visualizing increased uptake of [18F]FDG and [18F]FTHA in kidneys from obese high-fat diet fed C57BL/6J mice using PET/CT ex vivo. PLoS One 2023; 18:e0281705. [PMID: 36787333 PMCID: PMC9928095 DOI: 10.1371/journal.pone.0281705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 01/31/2023] [Indexed: 02/15/2023] Open
Abstract
It is known that high-fat diet (HFD) and/or diabetes may influence substrate preferences and energy demands in the heart preceding diabetic cardiomyopathy. They may also induce structural glomerular changes causing diabetic nephropathy. PET/CT has been utilized to examine uptake of energy substrates, and to study metabolic changes or shifts before onset of metabolic disorders. However, conventional PET/CT scanning of organs with relatively low uptake, such as the kidney, in small animals in vivo may render technical difficulties. To address this issue, we developed a PET/CT ex vivo protocol with radiolabeled glucose and fatty acid analouges, [18F]FDG and [18F]FTHA,to study substrate uptake in mouse kidneys. We also aimed to detect a possible energy substrate shift before onset of diabetic nephropathy. The ex vivo protocol reduced interfering background as well as interindividual variances. We found increased uptake of [18F]FDG and [18F]FTHA in kidneys after HFD, compared to kidneys from young mice on standard chow. Levels of kidney triglycerides also increased on HFD. Lipoprotein lipase (LPL) activity, the enzyme responsible for release of fatty acids from circulating lipoproteins, is normally increased in postprandial mice kidneys. After long-term HFD, we found that LPL activity was suppressed, and could therefore not explain the increased levels of stored triglycerides. Suppressed LPL activity was associated with increased expression of angiopoietin-like protein4, an inhibitor of LPL. HFD did not alter the transcriptional control of some common glucose and fatty acid transporters that may mediate uptake of [18F]FDG and [18F]FTHA. Performing PET/CT ex vivo reduced interfering background and interindividual variances. Obesity and insulin resistance induced by HFD increased the uptake of [18F]FDG and [18F]FTHA and triglyceride accumulation in mouse kidneys. Increased levels of [18F]FDG and [18F]FTHA in obese insulin resistant mice could be used clinically as an indicator of poor metabolic control, and a complementary test for incipient diabetic nephropathy.
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Affiliation(s)
- Rakel Nyrén
- Department of Medical Biosciences/Physiological Chemistry, Umeå University, Umeå, Sweden
- Department of Medical Biosciences/Pathology, Umeå University, Umeå, Sweden
| | - Henrik Scherman
- Department of Radiation Sciences, Umeå University, Umeå, Sweden
| | - Jan Axelsson
- Department of Radiation Sciences, Umeå University, Umeå, Sweden
| | - Chuchun L. Chang
- Institute of Human Nutrition, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York, United States of America
| | - Gunilla Olivecrona
- Department of Medical Biosciences/Physiological Chemistry, Umeå University, Umeå, Sweden
| | - Madelene Ericsson
- Department of Medical Biosciences/Physiological Chemistry, Umeå University, Umeå, Sweden
- Umeå Centre for Molecular Medicine, Umeå University, Umeå, Sweden
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6
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Obesity and cancer-extracellular matrix, angiogenesis, and adrenergic signaling as unusual suspects linking the two diseases. Cancer Metastasis Rev 2022; 41:517-547. [PMID: 36074318 PMCID: PMC9470659 DOI: 10.1007/s10555-022-10058-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 07/29/2022] [Indexed: 12/24/2022]
Abstract
Obesity is an established risk factor for several human cancers. Given the association between excess body weight and cancer, the increasing rates of obesity worldwide are worrisome. A variety of obesity-related factors has been implicated in cancer initiation, progression, and response to therapy. These factors include circulating nutritional factors, hormones, and cytokines, causing hyperinsulinemia, inflammation, and adipose tissue dysfunction. The impact of these conditions on cancer development and progression has been the focus of extensive literature. In this review, we concentrate on processes that can link obesity and cancer, and which provide a novel perspective: extracellular matrix remodeling, angiogenesis, and adrenergic signaling. We describe molecular mechanisms involved in these processes, which represent putative targets for intervention. Liver, pancreas, and breast cancers were chosen as exemplary disease models. In view of the expanding epidemic of obesity, a better understanding of the tumorigenic process in obese individuals might lead to more effective treatments and preventive measures.
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7
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Role and mechanism of the action of angiopoietin-like protein ANGPTL4 in plasma lipid metabolism. J Lipid Res 2021; 62:100150. [PMID: 34801488 PMCID: PMC8666355 DOI: 10.1016/j.jlr.2021.100150] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 10/27/2021] [Accepted: 10/29/2021] [Indexed: 11/24/2022] Open
Abstract
Triglycerides are carried in the bloodstream as the components of very low-density lipoproteins and chylomicrons. These circulating triglycerides are primarily hydrolyzed in muscle and adipose tissue by the enzyme lipoprotein lipase (LPL). The activity of LPL is regulated by numerous mechanisms, including by three members of the angiopoietin-like protein family: ANGPTL3, ANGPTL4, and ANGPTL8. In this review, we discuss the recent literature concerning the role and mechanism of action of ANGPTL4 in lipid metabolism. ANGPTL4 is a fasting- and lipid-induced factor secreted by numerous cells, including adipocytes, hepatocytes, (cardio)myocytes, and macrophages. In adipocytes, ANGPTL4 mediates the fasting-induced repression of LPL activity by promoting the unfolding of LPL, leading to the cleavage and subsequent degradation of LPL. The inhibition of LPL by ANGPTL4 is opposed by ANGPTL8, which keeps the LPL active after feeding. In macrophages and (cardio)myocytes, ANGPTL4 functions as a lipid-inducible feedback regulator of LPL-mediated lipid uptake. In comparison, in hepatocytes, ANGPTL4 functions as a local inhibitor of hepatic lipase and possibly as an endocrine inhibitor of LPL in extra-hepatic tissues. At the genetic level, loss-of-function mutations in ANGPTL4 are associated with lower plasma triglycerides and higher plasma HDL-C levels, and a reduced risk of coronary artery disease, suggesting that ANGPTL4 is a viable pharmacological target for reducing cardiovascular risk. Whole-body targeting of ANGPTL4 is contraindicated because of severe pathological complications, whereas liver-specific inactivation of ANGPTL4, either as monotherapy or coupled to anti-ANGPTL3 therapies might be a suitable strategy for lowering plasma triglycerides in selected patient groups. In conclusion, the tissue-specific targeting of ANGPTL4 appears to be a viable pharmacological approach to reduce circulating triglycerides.
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8
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Gopinath V, Shamsitha MKA, Penarveettil Nair V, Seena P, Uppu RM, C Raghavamenon A. Thermally Oxidized Coconut Oil as Fat Source in High-Fat Diet Induces Hepatic Fibrosis in Diabetic Rat Model. Cell Biochem Biophys 2021; 79:629-639. [PMID: 34106414 DOI: 10.1007/s12013-021-01009-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/28/2021] [Indexed: 02/07/2023]
Abstract
In the present study, HFD/STZ-mediated type 2 diabetic rodent model was used to comparatively evaluate coconut oil (CO) and thermally oxidized CO (TCO) as fat sources for the development of NAFLD. Female Wistar rats (six in each group; average bwt 200 g) fed HFD containing either CO or TCO for 2 months along with an intraperitoneal injection of streptozotocin (30 mg/kg bwt) at the end of 1-month feeding were found to develop fatty liver and subsequent inflammatory changes when compared to the normal laboratory diet-fed animals over 2-month period. Dyslipidemia as well as enhanced activities of serum hepatic marker enzymes (e.g., AST, ALT, and ALP) were prominent in TCO-fed animals. Further, HFD-fed animals showed alterations in their hepatic redox equilibrium. Hepatic GSH and antioxidant enzyme activities that form the part of a protective mechanism against oxidative/carbonyl stress were found to be increased in HFD-fed rats. Supporting this, CO- and TCO-containing-HFD-fed animals had enhanced lipid peroxidation (increased TBARs). Thus, fatty liver with heightened antioxidant defense, lipid peroxidation, and inflammation indicate hepatosteatosis. Histological details of the hepatic tissues corroborated sufficiently with these observations and showed an increased incidence of macrovesicles, inflammation, and hepatocyte ballooning in the TCO-fed rats than in CO-fed animals. Further, in support of this proposition, hydroxyproline, an index of collagen formation, was found to be significantly increased in TCO-fed rats than in the CO-fed group. Overall, the study shows that the formulation of HFD incorporated with TCO as a fat source, combined with STZ injection, is an efficient dietary model for developing hepatosteatosis with fibrotic stage in rats within 2 months. Administration of this modified diet for a more extended period may be a good model for cirrhotic and hepatocellular carcinoma studies, which need to be further assessed.
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Affiliation(s)
- Veena Gopinath
- Department of Biochemistry, Amala Cancer Research Centre, Amala Nagar, Thrissur, Kerala, India
| | | | | | - Punnakkal Seena
- Markaz Arts and Science College, Athavanad, Valanchery, Kerala, India
| | - Rao M Uppu
- Department of Environmental Toxicology, College of Sciences and Engineering, Southern University and A&M College, Baton Rouge, LA, USA
| | - Achuthan C Raghavamenon
- Department of Biochemistry, Amala Cancer Research Centre, Amala Nagar, Thrissur, Kerala, India.
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9
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Valladolid-Acebes I, Åvall K, Recio-López P, Moruzzi N, Bryzgalova G, Björnholm M, Krook A, Alonso EF, Ericsson M, Landfors F, Nilsson SK, Berggren PO, Juntti-Berggren L. Lowering apolipoprotein CIII protects against high-fat diet-induced metabolic derangements. SCIENCE ADVANCES 2021; 7:7/11/eabc2931. [PMID: 33712458 PMCID: PMC7954448 DOI: 10.1126/sciadv.abc2931] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 01/27/2021] [Indexed: 02/05/2023]
Abstract
Increased levels of apolipoprotein CIII (apoCIII), a key regulator of lipid metabolism, result in obesity-related metabolic derangements. We investigated mechanistically whether lowering or preventing high-fat diet (HFD)–induced increase in apoCIII protects against the detrimental metabolic consequences. Mice, first fed HFD for 10 weeks and thereafter also given an antisense (ASO) to lower apoCIII, already showed reduced levels of apoCIII and metabolic improvements after 4 weeks, despite maintained obesity. Prolonged ASO treatment reversed the metabolic phenotype due to increased lipase activity and receptor-mediated hepatic uptake of lipids. Fatty acids were transferred to the ketogenic pathway, and ketones were used in brown adipose tissue (BAT). This resulted in no fat accumulation and preserved morphology and function of liver and BAT. If ASO treatment started simultaneously with the HFD, mice remained lean and metabolically healthy. Thus, lowering apoCIII protects against and reverses the HFD-induced metabolic phenotype by promoting physiological insulin sensitivity.
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Affiliation(s)
- Ismael Valladolid-Acebes
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital L1, SE-171 76 Stockholm, Sweden
| | - Karin Åvall
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital L1, SE-171 76 Stockholm, Sweden
| | - Patricia Recio-López
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital L1, SE-171 76 Stockholm, Sweden
| | - Noah Moruzzi
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital L1, SE-171 76 Stockholm, Sweden
| | - Galyna Bryzgalova
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital L1, SE-171 76 Stockholm, Sweden
| | - Marie Björnholm
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Anna Krook
- Department of Physiology and Pharmacology, C3, Integrative Physiology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Elena Fauste Alonso
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital L1, SE-171 76 Stockholm, Sweden.,Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Montepríncipe, Boadilla del Monte, Madrid, Spain
| | - Madelene Ericsson
- Department of Medical Biosciences, Unit of Physiological Chemistry 6M, Umeå University, SE-901 85 Umeå, Sweden
| | - Fredrik Landfors
- Department of Medical Biosciences, Unit of Physiological Chemistry 6M, Umeå University, SE-901 85 Umeå, Sweden
| | - Stefan K Nilsson
- Department of Medical Biosciences, Unit of Physiological Chemistry 6M, Umeå University, SE-901 85 Umeå, Sweden
| | - Per-Olof Berggren
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital L1, SE-171 76 Stockholm, Sweden.,Division of Integrative Bioscience and Biotechnology, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Republic of Korea.,Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA.,Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 637553, Singapore.,Center for Diabetes and Metabolism Research, Department of Endocrinology and Metabolism, West China Hospital, Sichuan University, Chengdu 610041, Sichuan Province, PR China
| | - Lisa Juntti-Berggren
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital L1, SE-171 76 Stockholm, Sweden.
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10
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Ruppert PMM, Michielsen CCJR, Hazebroek EJ, Pirayesh A, Olivecrona G, Afman LA, Kersten S. Fasting induces ANGPTL4 and reduces LPL activity in human adipose tissue. Mol Metab 2020; 40:101033. [PMID: 32504883 PMCID: PMC7334813 DOI: 10.1016/j.molmet.2020.101033] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 05/28/2020] [Accepted: 05/31/2020] [Indexed: 02/06/2023] Open
Abstract
Objective Studies in mice have shown that the decrease in lipoprotein lipase (LPL) activity in adipose tissue upon fasting is mediated by induction of the inhibitor ANGPTL4. Here, we aimed to validate this concept in humans by determining the effect of a prolonged fast on ANGPTL4 and LPL gene and protein expression in human subcutaneous adipose tissue. Methods Twenty-three volunteers ate a standardized meal at 18.00 h and fasted until 20.00 h the next day. Blood was drawn and periumbilical adipose tissue biopsies were collected 2 h and 26 h after the meal. Results Consistent with previous mouse data, LPL activity in human adipose tissue was significantly decreased by fasting (−60%), concurrent with increased ANGPTL4 mRNA (+90%) and decreased ANGPTL8 mRNA (−94%). ANGPTL4 protein levels in adipose tissue were also significantly increased by fasting (+46%), whereas LPL mRNA and protein levels remained unchanged. In agreement with the adipose tissue data, plasma ANGPTL4 levels increased upon fasting (+100%), whereas plasma ANGPTL8 decreased (−79%). Insulin, levels of which significantly decreased upon fasting, downregulated ANGPTL4 mRNA and protein in primary human adipocytes. By contrast, cortisol, levels of which significantly increased upon fasting, upregulated ANGPTL4 mRNA and protein in primary human adipocytes as did fatty acids. Conclusion ANGPTL4 levels in human adipose tissue are increased by fasting, likely via increased plasma cortisol and free fatty acids and decreased plasma insulin, resulting in decreased LPL activity. This clinical trial was registered with identifier NCT03757767. 24-h fast in humans reduces LPL activity in subcutaneous adipose tissue. 24-h fast in humans increases adipose ANGPTL4 mRNA, protein, and plasma ANGPTL4 levels. Cortisol, fatty acids, and insulin regulate ANGPTL4 in vitro. ANGPTL4 mediates the reduction in adipose LPL activity during fasting. 24-h fast in humans decreases adipose ANGPTL8 mRNA and plasma ANGPTL8 levels.
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Affiliation(s)
- Philip M M Ruppert
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition and Health, Wageningen University, Wageningen, the Netherlands
| | - Charlotte C J R Michielsen
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition and Health, Wageningen University, Wageningen, the Netherlands
| | - Eric J Hazebroek
- Department of Bariatric Surgery, Rijnstate Hospital/Vitalys Clinic, Arnhem, the Netherlands; Nutrition and Disease Group, Division of Human Nutrition and Health, Wageningen University, Wageningen, the Netherlands
| | - Ali Pirayesh
- Amsterdam Plastic Surgery, Amsterdam, the Netherlands
| | - Gunilla Olivecrona
- Department of Medical Biosciences/Physiological Chemistry, Umeå University, Umeå, Sweden
| | - Lydia A Afman
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition and Health, Wageningen University, Wageningen, the Netherlands
| | - Sander Kersten
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition and Health, Wageningen University, Wageningen, the Netherlands.
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11
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Nyrén R, Makoveichuk E, Malla S, Kersten S, Nilsson SK, Ericsson M, Olivecrona G. Lipoprotein lipase in mouse kidney: effects of nutritional status and high-fat diet. Am J Physiol Renal Physiol 2019; 316:F558-F571. [PMID: 30698048 DOI: 10.1152/ajprenal.00474.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Activity of lipoprotein lipase (LPL) is high in mouse kidney, but the reason is poorly understood. The aim was to characterize localization, regulation, and function of LPL in kidney of C57BL/6J mice. We found LPL mainly in proximal tubules, localized inside the tubular epithelial cells, under all conditions studied. In fed mice, some LPL colocalized with the endothelial markers CD31 and GPIHBP1 and could be removed by perfusion with heparin, indicating a vascular location. The role of angiopoietin-like protein 4 (ANGPTL4) for nutritional modulation of LPL activity was studied in wild-type and Angptl4-/- mice. In Angptl4-/- mice, kidney LPL activity remained high in fasted animals, indicating that ANGPTL4 is involved in suppression of LPL activity on fasting, like in adipose tissue. The amount of ANGPTL4 protein in kidney was low, and the protein appeared smaller in size, compared with ANGPTL4 in heart and adipose tissue. To study the influence of obesity, mice were challenged with high-fat diet for 22 wk, and LPL was studied after an overnight fast compared with fasted mice given food for 3 h. High-fat diet caused blunting of the normal adaptation of LPL activity to feeding/fasting in adipose tissue, but in kidneys this adaptation was lost only in male mice. LPL activity increases to high levels in mouse kidney after feeding, but as no difference in uptake of chylomicron triglycerides in kidneys is found between fasted and fed states, our data confirm that LPL appears to have a minor role for lipid uptake in this organ.
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Affiliation(s)
- Rakel Nyrén
- Department of Medical Biosciences/Physiological Chemistry, Umeå University , Umeå , Sweden
| | - Elena Makoveichuk
- Department of Medical Biosciences/Physiological Chemistry, Umeå University , Umeå , Sweden
| | - Sandhya Malla
- Department of Medical Biosciences/Physiological Chemistry, Umeå University , Umeå , Sweden.,Wallenberg Center for Molecular Medicine, Umeå University , Umeå , Sweden
| | - Sander Kersten
- Nutrition, Metabolism, and Genomics Group, Division of Human Nutrition and Health, Wageningen University , Wageningen , The Netherlands
| | - Stefan K Nilsson
- Department of Medical Biosciences/Physiological Chemistry, Umeå University , Umeå , Sweden
| | - Madelene Ericsson
- Department of Medical Biosciences/Physiological Chemistry, Umeå University , Umeå , Sweden
| | - Gunilla Olivecrona
- Department of Medical Biosciences/Physiological Chemistry, Umeå University , Umeå , Sweden
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12
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Gutgsell AR, Ghodge SV, Bowers AA, Neher SB. Mapping the sites of the lipoprotein lipase (LPL)-angiopoietin-like protein 4 (ANGPTL4) interaction provides mechanistic insight into LPL inhibition. J Biol Chem 2018; 294:2678-2689. [PMID: 30591589 DOI: 10.1074/jbc.ra118.005932] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 12/21/2018] [Indexed: 12/29/2022] Open
Abstract
Cardiovascular disease has been the leading cause of death throughout the world for nearly 2 decades. Hypertriglyceridemia affects more than one-third of the population in the United States and is an independent risk factor for cardiovascular disease. Despite the frequency of hypertriglyceridemia, treatment options are primarily limited to diet and exercise. Lipoprotein lipase (LPL) is an enzyme responsible for clearing triglycerides from circulation, and its activity alone can directly control plasma triglyceride concentrations. Therefore, LPL is a good target for triglyceride-lowering therapeutics. One approach for treating hypertriglyceridemia may be to increase the amount of enzymatically active LPL by preventing its inhibition by angiopoietin-like protein 4 (ANGPTL4). However, little is known about how these two proteins interact. Therefore, we used hydrogen-deuterium exchange MS to identify potential binding sites between LPL and ANGPTL4. We validated sites predicted to be located at the protein-protein interface by using chimeric variants of LPL and an LPL peptide mimetic. We found that ANGPTL4 binds LPL near the active site at the lid domain and a nearby α-helix. Lipase lid domains cover the active site to control both enzyme activation and substrate specificity. Our findings suggest that ANGPTL4 specifically inhibits LPL by binding the lid domain, which could prevent substrate catalysis at the active site. The structural details of the LPL-ANGPTL4 interaction uncovered here may inform the development of therapeutics targeted to disrupt this interaction for the management of hypertriglyceridemia.
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Affiliation(s)
- Aspen R Gutgsell
- From the Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599 and
| | - Swapnil V Ghodge
- the Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Albert A Bowers
- the Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Saskia B Neher
- From the Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599 and
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13
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El Husseiny I, Elbrense H, Roeder T, El Kholy S. Hormonal modulation of cannibalistic behaviors in mosquito (Culex pipiens) larvae. JOURNAL OF INSECT PHYSIOLOGY 2018; 109:144-148. [PMID: 30077702 DOI: 10.1016/j.jinsphys.2018.08.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 08/01/2018] [Accepted: 08/01/2018] [Indexed: 06/08/2023]
Abstract
Cannibalism has been observed occasionally in a limited number of different animal species, but the underlying mechanisms that foster this behavior are mostly unknown. Here we show that mosquito (Culex pipiens) larvae show this behavior towards conspecifics under certain conditions. Cannibalism was only observed in 4th instar larvae and only in response to starvation. Well fed animals never showed any cannibalistic behavior. Starvation induced cannibalism of Culex 4th instar was predominantly directed towards 3rd instars rather than to 1st or 2nd instar larvae. Specific mandibular structures of these larvae enable this cannibalistic behavior. We could show that treatment with the biogenic amine octopamine, which is known to be involved in the control of starvation and aggression, increased the rate of cannibalism of food-deprived 4th instar larvae significantly. Incubation with the octopamine receptor antagonist phentolamine suppressed this cannibalistic behavior. Moreover, octopamine not only increased the rate of cannibalism, it also induced a shift towards smaller prey. A role of octopamine in this starvation induced behavior was further supported by direct measurements of the total content of this important neuroactive compound. Taken together, we could show that 4th instar mosquito larvae showed cannibalistic behavior after starvation and that this behavior apparently depends on octopamine.
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Affiliation(s)
- Iman El Husseiny
- Zoology Department, Faculty of Science, Tanta University, Tanta, Egypt
| | - Hanaa Elbrense
- Zoology Department, Faculty of Science, Tanta University, Tanta, Egypt
| | - Thomas Roeder
- Kiel University, Zoological Institute, Dept. Molecular Physiology, Kiel, Germany; German Center for Lung Research (DZL), Airway Research Center North (ARCN), Germany.
| | - Samar El Kholy
- Zoology Department, Faculty of Science, Tanta University, Tanta, Egypt
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14
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Klinger SC, Højland A, Jain S, Kjolby M, Madsen P, Svendsen AD, Olivecrona G, Bonifacino JS, Nielsen MS. Polarized trafficking of the sorting receptor SorLA in neurons and MDCK cells. FEBS J 2016; 283:2476-93. [PMID: 27192064 DOI: 10.1111/febs.13758] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 05/03/2016] [Accepted: 05/13/2016] [Indexed: 01/19/2023]
Abstract
The sorting receptor SorLA is highly expressed in neurons and is also found in other polarized cells. The receptor has been reported to participate in the trafficking of several ligands, some of which are linked to human diseases, including the amyloid precursor protein, TrkB, and Lipoprotein Lipase (LpL). Despite this, only the trafficking in nonpolarized cells has been described so far. Due to the many differences between polarized and nonpolarized cells, we examined the localization and trafficking of SorLA in epithelial Madin-Darby canine kidney (MDCK) cells and rat hippocampal neurons. We show that SorLA is mainly found in sorting endosomes and on the basolateral surface of MDCK cells and in the somatodendritic domain of neurons. This polarized distribution of SorLA respectively depends on an acidic cluster and an extended version of this cluster and involves the cellular adaptor complex AP-1. Furthermore, we show that SorLA can mediate transcytosis across a tight cell layer.
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Affiliation(s)
- Stine C Klinger
- Department of Biomedicine, The Lundbeck Foundation Initiative on Brain Barriers and Drug Delivery, Aarhus University, Denmark.,Department of Biomedicine, The MIND Centre, Aarhus University, Denmark.,Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Anne Højland
- Department of Biomedicine, The Lundbeck Foundation Initiative on Brain Barriers and Drug Delivery, Aarhus University, Denmark.,Department of Biomedicine, The MIND Centre, Aarhus University, Denmark
| | - Shweta Jain
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Mads Kjolby
- Department of Biomedicine, The MIND Centre, Aarhus University, Denmark.,Department of Biomedicine, The Danish Diabetes Academy, Aarhus University, Denmark
| | - Peder Madsen
- Department of Biomedicine, The Lundbeck Foundation Initiative on Brain Barriers and Drug Delivery, Aarhus University, Denmark.,Department of Biomedicine, The MIND Centre, Aarhus University, Denmark
| | - Anna Dorst Svendsen
- Department of Biomedicine, The Lundbeck Foundation Initiative on Brain Barriers and Drug Delivery, Aarhus University, Denmark.,Department of Biomedicine, The MIND Centre, Aarhus University, Denmark
| | - Gunilla Olivecrona
- Department of Medical Biosciences, Physiological Chemistry, Umeå University, Sweden
| | - Juan S Bonifacino
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Morten S Nielsen
- Department of Biomedicine, The Lundbeck Foundation Initiative on Brain Barriers and Drug Delivery, Aarhus University, Denmark.,Department of Biomedicine, The MIND Centre, Aarhus University, Denmark
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15
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Shimozuru M, Nagashima A, Tanaka J, Tsubota T. Seasonal changes in the expression of energy metabolism-related genes in white adipose tissue and skeletal muscle in female Japanese black bears. Comp Biochem Physiol B Biochem Mol Biol 2016; 196-197:38-47. [DOI: 10.1016/j.cbpb.2016.02.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 02/10/2016] [Accepted: 02/10/2016] [Indexed: 10/24/2022]
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16
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Fu Z, Abou-Samra AB, Zhang R. A lipasin/Angptl8 monoclonal antibody lowers mouse serum triglycerides involving increased postprandial activity of the cardiac lipoprotein lipase. Sci Rep 2015; 5:18502. [PMID: 26687026 PMCID: PMC4685196 DOI: 10.1038/srep18502] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 11/19/2015] [Indexed: 12/23/2022] Open
Abstract
Lipasin/Angptl8 is a feeding-induced hepatokine that regulates triglyceride (TAG) metabolism; its therapeutical potential, mechanism of action, and relation to the lipoprotein lipase (LPL), however, remain elusive. We generated five monoclonal lipasin antibodies, among which one lowered the serum TAG level when injected into mice, and the epitope was determined to be EIQVEE. Lipasin-deficient mice exhibited elevated postprandial activity of LPL in the heart and skeletal muscle, but not in white adipose tissue (WAT), suggesting that lipasin suppresses the activity of LPL specifically in cardiac and skeletal muscles. Consistently, mice injected with the effective antibody or with lipasin deficiency had increased postprandial cardiac LPL activity and lower TAG levels only in the fed state. These results suggest that lipasin acts, at least in part, in an endocrine manner. We propose the following model: feeding induces lipasin, activating the lipasin-Angptl3 pathway, which inhibits LPL in cardiac and skeletal muscles to direct circulating TAG to WAT for storage; conversely, fasting induces Angptl4, which inhibits LPL in WAT to direct circulating TAG to cardiac and skeletal muscles for oxidation. This model suggests a general mechanism by which TAG trafficking is coordinated by lipasin, Angptl3 and Angptl4 at different nutritional statuses.
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Affiliation(s)
- Zhiyao Fu
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, 540 East Canfield Street, Detroit, MI 48201, USA
| | - Abdul B Abou-Samra
- Division of Endocrinology, School of Medicine, Wayne State University, Detroit, MI 48201, USA.,Department of Medicine, Hamad Medical Corporation, Doha, Qatar
| | - Ren Zhang
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, 540 East Canfield Street, Detroit, MI 48201, USA.,Division of Endocrinology, School of Medicine, Wayne State University, Detroit, MI 48201, USA
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17
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Tsuzaki K, Kotani K, Yamada K, Sakane N. Fasting Lipoprotein Lipase Protein Levels Can Predict a Postmeal Increment of Triglyceride Levels in Fasting Normohypertriglyceridemic Subjects. J Clin Lab Anal 2015; 30:404-7. [PMID: 26303158 DOI: 10.1002/jcla.21869] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 06/27/2015] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Although a postprandial increment in triglyceride (TG) levels is considered to be a risk factor for atherogenesis, tests (e.g., fat load) to assess postprandial changes in TG levels cannot be easily applied to clinical practice. Therefore, fasting markers that predict postprandial TG states are needed to be developed. One current candidate is lipoprotein lipase (LPL) protein, a molecule that hydrides TGs. This study investigated whether fasting LPL levels could predict postprandial TG levels. METHODS A total of 17 subjects (11 men, 6 women, mean age 52 ± 11 years) with normotriglyceridemia during fasting underwent the meal test. Several fasting parameters, including LPL, were measured for the area under the curve of postprandial TGs (AUC-TG). RESULTS The subjects' mean fasting TG level was 1.30 mmol/l, and their mean LPL level was 41.6 ng/ml. The subjects' TG levels increased after loading (they peaked after two postprandial hours). Stepwise multiple regression analysis demonstrated that fasting TG levels were a predictor of the AUC-TG. In addition, fasting LPL mass levels were found to be a predictor of the AUC-TG (β = 0.65, P < 0.01), and this relationship was independent of fasting TG levels. CONCLUSION Fasting LPL levels may be useful to predict postprandial TG increment in this population.
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Affiliation(s)
- Kokoro Tsuzaki
- Division of Preventive Medicine, Clinical Research Institute, National Hospital Organization Kyoto Medical Center, Kyoto, Japan
| | - Kazuhiko Kotani
- Division of Preventive Medicine, Clinical Research Institute, National Hospital Organization Kyoto Medical Center, Kyoto, Japan. .,Division of Community and Family Medicine, Jichi Medical University, Tochigi, Japan.
| | - Kazunori Yamada
- Diabetes Center, National Hospital Organization Kyoto Medical Center, Kyoto, Japan
| | - Naoki Sakane
- Division of Preventive Medicine, Clinical Research Institute, National Hospital Organization Kyoto Medical Center, Kyoto, Japan
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18
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Chi X, Shetty SK, Shows HW, Hjelmaas AJ, Malcolm EK, Davies BSJ. Angiopoietin-like 4 Modifies the Interactions between Lipoprotein Lipase and Its Endothelial Cell Transporter GPIHBP1. J Biol Chem 2015; 290:11865-77. [PMID: 25809481 DOI: 10.1074/jbc.m114.623769] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Indexed: 12/26/2022] Open
Abstract
The release of fatty acids from plasma triglycerides for tissue uptake is critically dependent on the enzyme lipoprotein lipase (LPL). Hydrolysis of plasma triglycerides by LPL can be disrupted by the protein angiopoietin-like 4 (ANGPTL4), and ANGPTL4 has been shown to inactivate LPL in vitro. However, in vivo LPL is often complexed to glycosylphosphatidylinositol-anchored high density lipoprotein-binding protein 1 (GPIHBP1) on the surface of capillary endothelial cells. GPIHBP1 is responsible for trafficking LPL across capillary endothelial cells and anchors LPL to the capillary wall during lipolysis. How ANGPTL4 interacts with LPL in this context is not known. In this study, we investigated the interactions of ANGPTL4 with LPL-GPIHBP1 complexes on the surface of endothelial cells. We show that ANGPTL4 was capable of binding and inactivating LPL complexed to GPIHBP1 on the surface of endothelial cells. Once inactivated, LPL dissociated from GPIHBP1. We also show that ANGPTL4-inactivated LPL was incapable of binding GPIHBP1. ANGPTL4 was capable of binding, but not inactivating, LPL at 4 °C, suggesting that binding alone was not sufficient for ANGPTL4's inhibitory activity. We observed that although the N-terminal coiled-coil domain of ANGPTL4 by itself and full-length ANGPTL4 both bound with similar affinities to LPL, the N-terminal fragment was more potent in inactivating both free and GPIHBP1-bound LPL. These results led us to conclude that ANGPTL4 can both bind and inactivate LPL complexed to GPIHBP1 and that inactivation of LPL by ANGPTL4 greatly reduces the affinity of LPL for GPIHBP1.
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Affiliation(s)
- Xun Chi
- From the Department of Biochemistry, Fraternal Order of Eagles Diabetes Research Center and Obesity Research and Education Initiative, University of Iowa, Iowa City, Iowa 52242
| | - Shwetha K Shetty
- From the Department of Biochemistry, Fraternal Order of Eagles Diabetes Research Center and Obesity Research and Education Initiative, University of Iowa, Iowa City, Iowa 52242
| | - Hannah W Shows
- From the Department of Biochemistry, Fraternal Order of Eagles Diabetes Research Center and Obesity Research and Education Initiative, University of Iowa, Iowa City, Iowa 52242
| | - Alexander J Hjelmaas
- From the Department of Biochemistry, Fraternal Order of Eagles Diabetes Research Center and Obesity Research and Education Initiative, University of Iowa, Iowa City, Iowa 52242
| | - Emily K Malcolm
- From the Department of Biochemistry, Fraternal Order of Eagles Diabetes Research Center and Obesity Research and Education Initiative, University of Iowa, Iowa City, Iowa 52242
| | - Brandon S J Davies
- From the Department of Biochemistry, Fraternal Order of Eagles Diabetes Research Center and Obesity Research and Education Initiative, University of Iowa, Iowa City, Iowa 52242
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19
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Larsson M, Caraballo R, Ericsson M, Lookene A, Enquist PA, Elofsson M, Nilsson SK, Olivecrona G. Identification of a small molecule that stabilizes lipoprotein lipase in vitro and lowers triglycerides in vivo. Biochem Biophys Res Commun 2014; 450:1063-9. [DOI: 10.1016/j.bbrc.2014.06.114] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 06/23/2014] [Indexed: 01/04/2023]
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20
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Gisterå A, Robertson AKL, Andersson J, Ketelhuth DFJ, Ovchinnikova O, Nilsson SK, Lundberg AM, Li MO, Flavell RA, Hansson GK. Transforming growth factor-β signaling in T cells promotes stabilization of atherosclerotic plaques through an interleukin-17-dependent pathway. Sci Transl Med 2014; 5:196ra100. [PMID: 23903754 DOI: 10.1126/scitranslmed.3006133] [Citation(s) in RCA: 144] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Adaptive immunity has a major impact on atherosclerosis, with pro- and anti-atherosclerotic effects exerted by different subpopulations of T cells. Transforming growth factor-β (TGF-β) may promote development either of anti-atherosclerotic regulatory T cells or of T helper 17 (TH17) cells, depending on factors in the local milieu. We have addressed the effect on atherosclerosis of enhanced TGF-β signaling in T cells. Bone marrow from mice with a T cell-specific deletion of Smad7, a potent inhibitor of TGF-β signaling, was transplanted into hypercholesterolemic Ldlr(-/-) mice. Smad7-deficient mice had significantly larger atherosclerotic lesions that contained large collagen-rich caps, consistent with a more stable phenotype. The inflammatory cytokine interleukin-6 (IL-6) was expressed in the atherosclerotic aorta, and increased mRNA for IL-17A and the TH17-specific transcription factor RORγt were detected in draining lymph nodes. Treating Smad7-deficient chimeras with neutralizing IL-17A antibodies reversed stable cap formation. IL-17A stimulated collagen production by human vascular smooth muscle cells, and RORγt mRNA correlated positively with collagen type I and α-smooth muscle actin mRNA in a biobank of human atherosclerotic plaques. These data link IL-17A to induction of a stable plaque phenotype, could lead to new plaque-stabilizing therapies, and should prompt an evaluation of cardiovascular events in patients treated with IL-17 receptor blockade.
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Affiliation(s)
- Anton Gisterå
- Center for Molecular Medicine, Department of Medicine, Karolinska University Hospital, Karolinska Institutet, SE-17176 Stockholm, Sweden
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21
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Kersten S. Physiological regulation of lipoprotein lipase. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1841:919-33. [PMID: 24721265 DOI: 10.1016/j.bbalip.2014.03.013] [Citation(s) in RCA: 347] [Impact Index Per Article: 34.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 03/27/2014] [Accepted: 03/30/2014] [Indexed: 01/01/2023]
Abstract
The enzyme lipoprotein lipase (LPL), originally identified as the clearing factor lipase, hydrolyzes triglycerides present in the triglyceride-rich lipoproteins VLDL and chylomicrons. LPL is primarily expressed in tissues that oxidize or store fatty acids in large quantities such as the heart, skeletal muscle, brown adipose tissue and white adipose tissue. Upon production by the underlying parenchymal cells, LPL is transported and attached to the capillary endothelium by the protein GPIHBP1. Because LPL is rate limiting for plasma triglyceride clearance and tissue uptake of fatty acids, the activity of LPL is carefully controlled to adjust fatty acid uptake to the requirements of the underlying tissue via multiple mechanisms at the transcriptional and post-translational level. Although various stimuli influence LPL gene transcription, it is now evident that most of the physiological variation in LPL activity, such as during fasting and exercise, appears to be driven via post-translational mechanisms by extracellular proteins. These proteins can be divided into two main groups: the liver-derived apolipoproteins APOC1, APOC2, APOC3, APOA5, and APOE, and the angiopoietin-like proteins ANGPTL3, ANGPTL4 and ANGPTL8, which have a broader expression profile. This review will summarize the available literature on the regulation of LPL activity in various tissues, with an emphasis on the response to diverse physiological stimuli.
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Affiliation(s)
- Sander Kersten
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Bomenweg 2, 6703HD Wageningen, The Netherlands
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22
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Larsson M, Vorrsjö E, Talmud P, Lookene A, Olivecrona G. Apolipoproteins C-I and C-III inhibit lipoprotein lipase activity by displacement of the enzyme from lipid droplets. J Biol Chem 2013; 288:33997-34008. [PMID: 24121499 DOI: 10.1074/jbc.m113.495366] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Apolipoproteins (apo) C-I and C-III are known to inhibit lipoprotein lipase (LPL) activity, but the molecular mechanisms for this remain obscure. We present evidence that either apoC-I or apoC-III, when bound to triglyceride-rich lipoproteins, prevent binding of LPL to the lipid/water interface. This results in decreased lipolytic activity of the enzyme. Site-directed mutagenesis revealed that hydrophobic amino acid residues centrally located in the apoC-III molecule are critical for attachment to lipid emulsion particles and consequently inhibition of LPL activity. Triglyceride-rich lipoproteins stabilize LPL and protect the enzyme from inactivating factors such as angiopoietin-like protein 4 (angptl4). The addition of either apoC-I or apoC-III to triglyceride-rich particles severely diminished their protective effect on LPL and rendered the enzyme more susceptible to inactivation by angptl4. These observations were seen using chylomicrons as well as the synthetic lipid emulsion Intralipid. In the presence of the LPL activator protein apoC-II, more of apoC-I or apoC-III was needed for displacement of LPL from the lipid/water interface. In conclusion, we show that apoC-I and apoC-III inhibit lipolysis by displacing LPL from lipid emulsion particles. We also propose a role for these apolipoproteins in the irreversible inactivation of LPL by factors such as angptl4.
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Affiliation(s)
- Mikael Larsson
- Department of Medical Biosciences/Physiological Chemistry, Umeå University, SE-901 87 Umeå, Sweden
| | - Evelina Vorrsjö
- Department of Medical Biosciences/Physiological Chemistry, Umeå University, SE-901 87 Umeå, Sweden
| | - Philippa Talmud
- Centre for Cardiovascular Genetics, Institute of Cardiovascular Science, University College London, 5 University Street, London WC1E 6JF, United Kingdom
| | - Aivar Lookene
- Department of Chemistry, Tallinn University of Technology, Tallinn 12618, Estonia
| | - Gunilla Olivecrona
- Department of Medical Biosciences/Physiological Chemistry, Umeå University, SE-901 87 Umeå, Sweden.
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23
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Klingenberg R, Gerdes N, Badeau RM, Gisterå A, Strodthoff D, Ketelhuth DFJ, Lundberg AM, Rudling M, Nilsson SK, Olivecrona G, Zoller S, Lohmann C, Lüscher TF, Jauhiainen M, Sparwasser T, Hansson GK. Depletion of FOXP3+ regulatory T cells promotes hypercholesterolemia and atherosclerosis. J Clin Invest 2013; 123:1323-34. [PMID: 23426179 DOI: 10.1172/jci63891] [Citation(s) in RCA: 276] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 12/20/2012] [Indexed: 12/17/2022] Open
Abstract
Atherosclerosis is a chronic inflammatory disease promoted by hyperlipidemia. Several studies support FOXP3-positive regulatory T cells (Tregs) as inhibitors of atherosclerosis; however, the mechanism underlying this protection remains elusive. To define the role of FOXP3-expressing Tregs in atherosclerosis, we used the DEREG mouse, which expresses the diphtheria toxin (DT) receptor under control of the Treg-specific Foxp3 promoter, allowing for specific ablation of FOXP3+ Tregs. Lethally irradiated, atherosclerosis-prone, low-density lipoprotein receptor-deficient (Ldlr(-/-)) mice received DEREG bone marrow and were injected with DT to eliminate FOXP3(+) Tregs. Depletion of Tregs caused a 2.1-fold increase in atherosclerosis without a concomitant increase in vascular inflammation. These mice also exhibited a 1.7-fold increase in plasma cholesterol and an atherogenic lipoprotein profile with increased levels of VLDL. Clearance of VLDL and chylomicron remnants was hampered, leading to accumulation of cholesterol-rich particles in the circulation. Functional and protein analyses complemented by gene expression array identified reduced protein expression of sortilin-1 in liver and increased plasma enzyme activity of lipoprotein lipase, hepatic lipase, and phospholipid transfer protein as mediators of the altered lipid phenotype. These results demonstrate that FOXP3(+) Tregs inhibit atherosclerosis by modulating lipoprotein metabolism.
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Affiliation(s)
- Roland Klingenberg
- Center for Molecular Medicine, Department of Medicine, Karolinska University Hospital, Karolinska Institute, Stockholm, Sweden
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24
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Kroupa O, Vorrsjö E, Stienstra R, Mattijssen F, Nilsson SK, Sukonina V, Kersten S, Olivecrona G, Olivecrona T. Linking nutritional regulation of Angptl4, Gpihbp1, and Lmf1 to lipoprotein lipase activity in rodent adipose tissue. BMC PHYSIOLOGY 2012; 12:13. [PMID: 23176178 PMCID: PMC3562520 DOI: 10.1186/1472-6793-12-13] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 11/09/2012] [Indexed: 12/17/2022]
Abstract
Background Lipoprotein lipase (LPL) hydrolyzes triglycerides in lipoproteins and makes fatty acids available for tissue metabolism. The activity of the enzyme is modulated in a tissue specific manner by interaction with other proteins. We have studied how feeding/fasting and some related perturbations affect the expression, in rat adipose tissue, of three such proteins, LMF1, an ER protein necessary for folding of LPL into its active dimeric form, the endogenous LPL inhibitor ANGPTL4, and GPIHBP1, that transfers LPL across the endothelium. Results The system underwent moderate circadian oscillations, for LPL in phase with food intake, for ANGPTL4 and GPIHBP1 in the opposite direction. Studies with cycloheximide showed that whereas LPL protein turns over rapidly, ANGPTL4 protein turns over more slowly. Studies with the transcription blocker Actinomycin D showed that transcripts for ANGPTL4 and GPIHBP1, but not LMF1 or LPL, turn over rapidly. When food was withdrawn the expression of ANGPTL4 and GPIHBP1 increased rapidly, and LPL activity decreased. On re-feeding and after injection of insulin the expression of ANGPTL4 and GPIHBP1 decreased rapidly, and LPL activity increased. In ANGPTL4−/− mice adipose tissue LPL activity did not show these responses. In old, obese rats that showed signs of insulin resistance, the responses of ANGPTL4 and GPIHBP1 mRNA and of LPL activity were severely blunted (at 26 weeks of age) or almost abolished (at 52 weeks of age). Conclusions This study demonstrates directly that ANGPTL4 is necessary for rapid modulation of LPL activity in adipose tissue. ANGPTL4 message levels responded very rapidly to changes in the nutritional state. LPL activity always changed in the opposite direction. This did not happen in Angptl4−/− mice. GPIHBP1 message levels also changed rapidly and in the same direction as ANGPTL4, i.e. increased on fasting when LPL activity decreased. This was unexpected because GPIHBP1 is known to stabilize LPL. The plasticity of the LPL system is severely blunted or completely lost in insulin resistant rats.
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Affiliation(s)
- Olessia Kroupa
- Department of Medical Biosciences/Physiological Chemistry, Umeå University, Umeå SE-90187, Sweden
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Effect of ration size on fillet fatty acid composition, phospholipid allostasis and mRNA expression patterns of lipid regulatory genes in gilthead sea bream (Sparus aurata). Br J Nutr 2012; 109:1175-87. [PMID: 22856503 DOI: 10.1017/s000711451200311x] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The effect of ration size on muscle fatty acid (FA) composition and mRNA expression levels of key regulatory enzymes of lipid and lipoprotein metabolism have been addressed in juveniles of gilthead sea bream fed a practical diet over the course of an 11-week trial. The experimental setup included three feeding levels: (i) full ration until visual satiety, (ii) 70 % of satiation and (iii) 70 % of satiation with the last 2 weeks at the maintenance ration. Feed restriction reduced lipid content of whole body by 30 % and that of fillet by 50 %. In this scenario, the FA composition of fillet TAG was not altered by ration size, whereas that of phospholipids was largely modified with a higher retention of arachidonic acid and DHA. The mRNA transcript levels of lysophosphatidylcholine acyltransferases, phosphatidylethanolamine N-methyltransferase and FA desaturase 2 were not regulated by ration size in the present experimental model. In contrast, mRNA levels of stearoyl-CoA desaturases were markedly down-regulated by feed restriction. An opposite trend was found for a muscle-specific lipoprotein lipase, which is exclusive of fish lineage. Several upstream regulatory transcriptions were also assessed, although nutritionally mediated changes in mRNA transcripts were almost reduced to PPARα and β, which might act in a counter-regulatory way on lipolysis and lipogenic pathways. This gene expression pattern contributes to the construction of a panel of biomarkers to direct marine fish production towards muscle lean phenotypes with increased retentions of long-chain PUFA.
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Robal T, Larsson M, Martin M, Olivecrona G, Lookene A. Fatty acids bind tightly to the N-terminal domain of angiopoietin-like protein 4 and modulate its interaction with lipoprotein lipase. J Biol Chem 2012; 287:29739-52. [PMID: 22773878 DOI: 10.1074/jbc.m111.303529] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Angiopoietin-like protein 4 (Angptl4), a potent regulator of plasma triglyceride metabolism, binds to lipoprotein lipase (LPL) through its N-terminal coiled-coil domain (ccd-Angptl4) inducing dissociation of the dimeric enzyme to inactive monomers. In this study, we demonstrate that fatty acids reduce the inactivation of LPL by Angptl4. This was the case both with ccd-Angptl4 and full-length Angptl4, and the effect was seen in human plasma or in the presence of albumin. The effect decreased in the sequence oleic acid > palmitic acid > myristic acid > linoleic acid > linolenic acid. Surface plasmon resonance, isothermal titration calorimetry, fluorescence, and chromatography measurements revealed that fatty acids bind with high affinity to ccd-Angptl4. The interactions were characterized by fast association and slow dissociation rates, indicating formation of stable complexes. The highest affinity for ccd-Angptl4 was detected for oleic acid with a subnanomolar equilibrium dissociation constant (K(d)). The K(d) values for palmitic and myristic acid were in the nanomolar range. Linoleic and linolenic acid bound with much lower affinity. On binding of fatty acids, ccd-Angptl4 underwent conformational changes resulting in a decreased helical content, weakened structural stability, dissociation of oligomers, and altered fluorescence properties of the Trp-38 residue that is located close to the putative LPL-binding region. Based on these results, we propose that fatty acids play an important role in modulating the effects of Angptl4.
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Affiliation(s)
- Terje Robal
- Department of Chemistry, Tallinn University of Technology, Tallinn 12618, Estonia
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27
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Nilsson SK, Anderson F, Ericsson M, Larsson M, Makoveichuk E, Lookene A, Heeren J, Olivecrona G. Triacylglycerol-rich lipoproteins protect lipoprotein lipase from inactivation by ANGPTL3 and ANGPTL4. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1821:1370-8. [PMID: 22732211 DOI: 10.1016/j.bbalip.2012.06.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Revised: 05/13/2012] [Accepted: 06/08/2012] [Indexed: 10/28/2022]
Abstract
Lipoprotein lipase (LPL) is important for clearance of triacylglycerols (TG) from plasma both as an enzyme and as a bridging factor between lipoproteins and receptors for endocytosis. The amount of LPL at the luminal side of the capillary endothelium determines to what extent lipids are taken up. Mechanisms to control both the activity of LPL and its transport to the endothelial sites are regulated, but poorly understood. Angiopoietin-like proteins (ANGPTLs) 3 and 4 are potential control proteins for LPL, but plasma concentrations of ANGPTLs do not correlate with plasma TG levels. We investigated the effects of recombinant human N-terminal (NT) ANGPTLs3 and 4 on LPL-mediated bridging of TG-rich lipoproteins to primary mouse hepatocytes and found that the NT-ANGPTLs, in concentrations sufficient to cause inactivation of LPL in vitro, were unable to prevent LPL-mediated lipoprotein uptake. We therefore investigated the effects of lipoproteins (chylomicrons, VLDL and LDL) on the inactivation of LPL in vitro by NT-ANGPTLs3 and 4 and found that LPL activity was protected by TG-rich lipoproteins. In vivo, postprandial TG protected LPL from inactivation by recombinant NT-ANGPTL4 injected to mice. We conclude that lipoprotein-bound LPL is stabilized against inactivation by ANGPTLs. The levels of ANGPTLs found in blood may not be sufficient to overcome this stabilization. Therefore it is likely that the prime site of action of ANGPTLs on LPL is in subendothelial compartments where TG-rich lipoprotein concentration is lower than in blood. This could explain why the plasma levels of TG and ANGPTLs do not correlate.
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Affiliation(s)
- Stefan K Nilsson
- Department of Medical Biosciences/Physiological Chemistry, Umeå University, SE-901 87 Umeå, Sweden.
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28
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EZAKI O. The Optimal Dietary Fat to Carbohydrate Ratio to Prevent Obesity in the Japanese Population: A Review of the Epidemiological, Physiological and Molecular Evidence. J Nutr Sci Vitaminol (Tokyo) 2011; 57:383-93. [DOI: 10.3177/jnsv.57.383] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Bäckhed F, Crawford PA. Coordinated regulation of the metabolome and lipidome at the host-microbial interface. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1801:240-5. [PMID: 19782151 DOI: 10.1016/j.bbalip.2009.09.009] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2009] [Revised: 08/14/2009] [Accepted: 09/13/2009] [Indexed: 02/07/2023]
Abstract
The creative use of gnotobiotic animals, coupled with the development of modern metagenomic sequencing platforms and metabolomic profiling of biospecimens, has bestowed new insight into the remarkably intricate interface between the host mammal and its resident microbiota. As mutual benefactors, each partner exhibits evidence of adaptation: the host provides a hospitable habitat, giving consideration to its own species of origin, diet, genotype, geographical location, presence or absence of disease, and use of medications; the microbiota, in turn, configures its constituency, collective genome (microbiome), transcriptome, and metabolome to optimally suit its ecological niche. In this review, we discuss the mechanisms through which the gut microbiota and its host collaborate to regulate lipid metabolism, thereby influencing the metabolic response to nutrient intake and ultimately, the development of obesity and associated diseases such as lipotoxicity. These studies therefore demonstrate that the gut microbiota is an "environmental" influence whose synergistic interdependence with its host strongly suggests that we are in fact "supraorganisms."
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Affiliation(s)
- Fredrik Bäckhed
- Sahlgrenska Center for Cardiovascular and Metabolic Research/Wallenberg Laboratory and Department of Molecular and Clinical Medicine, University of Gothenburg, S-413 45 Gothenburg, Sweden.
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Mansouri M, Sevov M, Fahlgren E, Tobin G, Jondal M, Osorio L, Roos G, Olivecrona G, Rosenquist R. Lipoprotein lipase is differentially expressed in prognostic subsets of chronic lymphocytic leukemia but displays invariably low catalytical activity. Leuk Res 2009; 34:301-6. [PMID: 19709746 DOI: 10.1016/j.leukres.2009.07.032] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Revised: 06/18/2009] [Accepted: 07/22/2009] [Indexed: 11/29/2022]
Abstract
Lipoprotein lipase (LPL) expression has been shown to correlate with IGHV mutational status and to predict outcome in chronic lymphocytic leukemia (CLL). We here investigated the prognostic impact of LPL expression in relation to other prognostic markers including IGHV3-21 usage in 140 CLL patients. Additionally, we studied the catalytic activity of LPL in CLL cells. A significant difference in LPL mRNA expression was detected in IGHV unmutated compared to mutated CLL patients (p<0.001). However, the poor-prognostic mutated/stereotyped IGHV3-21 patients did not differ from other mutated CLL cases. Clinical outcome was significantly different in CLL cases with high versus low LPL expression (p<0.001), and LPL expression exceeded mutation status/IGHV3-21 usage as an independent prognostic marker. Finally, LPL protein expression correlated significantly with mRNA expression and was higher in IGHV unmutated versus mutated CLL (p=0.018), although the majority of synthesized protein was catalytically inactive indicating a non-catalytical function in CLL.
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Affiliation(s)
- Mahmoud Mansouri
- Department of Genetics and Pathology, Uppsala University, Uppsala, Sweden.
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31
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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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32
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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: 133] [Impact Index Per Article: 8.9] [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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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: 98] [Impact Index Per Article: 6.5] [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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Wang S, Soni KG, Semache M, Casavant S, Fortier M, Pan L, Mitchell GA. Lipolysis and the integrated physiology of lipid energy metabolism. Mol Genet Metab 2008; 95:117-26. [PMID: 18762440 DOI: 10.1016/j.ymgme.2008.06.012] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2008] [Revised: 06/30/2008] [Accepted: 06/30/2008] [Indexed: 11/18/2022]
Abstract
Fat cell lipolysis, the cleavage of triglycerides and release of fatty acids and glycerol, evolved to enable survival during prolonged food deprivation but is paradoxically increased in obesity, in which a surfeit of all energy metabolites is found. Essential, previously-unsuspected components have been discovered in the lipolytic machinery, at the protective interface of the lipid droplet surface and in the signaling pathways that control lipolysis. At least two adipocyte lipases are important for controlling lipolysis, hormone-sensitive lipase (HSL) and adipocyte triglyceride lipase (ATGL). Perilipin (PLIN) and possibly other proteins of the lipid droplet surface are master regulators of lipolysis, protecting or exposing the triglyceride core of the droplet to lipases. The prototypes for hormonal lipolytic control are beta adrenergic stimulation and suppression by insulin, both of which affect cyclic AMP levels and hence the protein kinase A-mediated phosphorylation of HSL and PLIN. Newly-recognized mediators of lipolysis include atrial natriuretic peptide, cyclic GMP, the ketone body 3-hydroxybutyrate, AMP kinase and mitogen-activated kinases. Lipolysis must be interpreted in its physiological context since similar rates of basal or stimulated lipolysis occur under different conditions and by different mechanisms. Age, sex, anatomical site, genotype and species differences are each important variables. Manipulation of lipolysis has therapeutic potential in several inborn errors and in the metabolic syndrome that frequently complicates obesity.
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Affiliation(s)
- Shupei Wang
- Division of Medical Genetics, CHU Sainte-Justine, Montréal, Quebec, Canada
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Intestinally derived lipids: Metabolic regulation and consequences—An overview. ATHEROSCLEROSIS SUPP 2008; 9:63-8. [DOI: 10.1016/j.atherosclerosissup.2008.05.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2008] [Revised: 04/03/2008] [Accepted: 05/13/2008] [Indexed: 01/17/2023]
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QIAO Y, HUANG ZG, LI QF, LIU ZS, DAI R, PAN ZX, XIE Z, LIU HL. Developmental Changes of the LPL mRNA Expression and Its Effect on IMF Content in Sheep Muscle. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/s1671-2927(08)60028-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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37
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Wu G, Zhang L, Gupta J, Olivecrona G, Olivecrona T. A transcription-dependent mechanism, akin to that in adipose tissue, modulates lipoprotein lipase activity in rat heart. Am J Physiol Endocrinol Metab 2007; 293:E908-15. [PMID: 17595214 DOI: 10.1152/ajpendo.00634.2006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The enzyme lipoprotein lipase (LPL) releases fatty acids from lipoprotein triglycerides for use in cell metabolism. LPL activity is rapidly modulated in a tissue-specific manner. Recent studies have shown that in rat adipose tissue this occurs by a shift of extracellular LPL toward an inactive form catalyzed by an LPL-controlling protein whose expression changes in response to the nutritional state. To explore whether a similar mechanism operates in other tissues we injected actinomycin D to block transcription of the putative LPL controlling protein(s). When actinomycin was given to fed rats, heparin-releasable LPL activity increased by 160% in heart and by 150% in a skeletal muscle (soleus) in 6 h. Postheparin LPL activity in blood increased by about 200%. To assess the state of extracellular LPL we subjected the spontaneously released LPL in heart perfusates to chromatography on heparin-agarose, which separates the active and inactive forms of the lipase. The amount of lipase protein released remained relatively constant on changes in the nutritional state and/or blockade of transcription, but the distribution between the active and inactive forms changed. Less of the LPL protein was in the active form in perfusates from hearts from fed compared with fasted rats. When glucose was given to fasted rats the proportion of LPL protein in the active form decreased. Actinomycin D increased the proportion that was active, in accord with the hypothesis that the message for a rapidly turning over LPL-controlling protein was being removed.
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Affiliation(s)
- Gengshu Wu
- Department of Medical Biosciences, Physiological Chemistry, Umeå University, Umeå, Sweden
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Magnusson-Olsson AL, Lager S, Jacobsson B, Jansson T, Powell TL. Effect of maternal triglycerides and free fatty acids on placental LPL in cultured primary trophoblast cells and in a case of maternal LPL deficiency. Am J Physiol Endocrinol Metab 2007; 293:E24-30. [PMID: 17299085 DOI: 10.1152/ajpendo.00571.2006] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Maternal hypertriglyceridemia is a normal condition in late gestation and is an adaptation to ensure an adequate nutrient supply to the fetus. Placental lipoprotein lipase (LPL) is involved in the initial step in transplacental fatty acid transport as it hydrolyzes maternal triglycerides (TG) to release free fatty acids (FFA). We investigated LPL activity and protein (Western blot) and mRNA expression (real-time RT-PCR) in the placenta of an LPL-deficient mother with marked hypertriglyceridemia. The LPL activity was fourfold lower, LPL protein expression 50% lower, and mRNA expression threefold higher than that of normal, healthy placentas at term (n = 4-7). To further investigate the role of maternal lipids in placental LPL regulation, we isolated placental cytotrophoblasts from term placentas and studied LPL activity and protein and mRNA expression after incubation in Intralipid (as a source of TG) and oleic, linoleic, and a combination of oleic, linoleic, and arachidonic acids as well as insulin. Intralipid (40 and 400 mg/dl) decreased LPL activity by approximately 30% (n = 10-14, P < 0.05) and 400 microM linoleic and linoleic-oleic-arachidonic acid (n = 10) decreased LPL activity by 37 and 34%, respectively. No major changes were observed in LPL protein or mRNA expression. We found no effect of insulin on LPL activity or protein expression in the cultured trophoblasts. To conclude, the activity of placental LPL is reduced by high levels of maternal TG and/or FFA. This regulatory mechanism may serve to counteract an excessive delivery of FFA to the fetus in conditions where maternal TG levels are markedly increased.
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Affiliation(s)
- Anne Liese Magnusson-Olsson
- Perinatal Center, Institute of Neuroscience and Physiology, Göteborg University, Box 432, S-405 30 Gothenburg, Sweden.
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Albalat A, Saera-Vila A, Capilla E, Gutiérrez J, Pérez-Sánchez J, Navarro I. Insulin regulation of lipoprotein lipase (LPL) activity and expression in gilthead sea bream (Sparus aurata). Comp Biochem Physiol B Biochem Mol Biol 2007; 148:151-9. [PMID: 17600746 DOI: 10.1016/j.cbpb.2007.05.004] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2007] [Revised: 05/10/2007] [Accepted: 05/11/2007] [Indexed: 11/20/2022]
Abstract
Lipoprotein lipase (LPL) is a key enzyme in lipoprotein metabolism by virtue of its capacity to hydrolyze triglycerides circulating in the form of lipoprotein particles. Here we analyzed the fasting effects of LPL in gilthead sea bream (Sparus aurata) and also present the first study in fish of the role of insulin as a potential modulator of both LPL activity and expression. Fasting for 2 weeks provoked a clear decrease in adipose tissue LPL activity, concomitant with lower levels of plasma insulin, while no effects were observed in red muscle. To elucidate the specific role of insulin, increases of plasma insulin were experimentally induced by arginine and insulin injections. However, arginine predominantly stimulated glucagon over insulin secretion in this fish species while LPL activity did not change significantly in adipose tissue. Instead, insulin administration induced an increase in adipose tissue LPL activity 3 h after the injection, whereas LPL activity in red muscle was not affected. Changes in LPL activity were accompanied by an increase in LPL mRNA levels in the adipose tissue of insulin-injected gilthead sea bream, although changes in LPL expression were delayed in time with respect to variations in LPL activity. Finally, LPL mRNA levels in red muscle were similar between control and insulin-injected gilthead sea bream, suggesting that insulin does not play a direct role in the regulation of LPL in this tissue. The current study shows that LPL activity is regulated by nutritional condition and underscores the importance of insulin as a modulator of LPL activity and expression in the adipose tissue of gilthead sea bream.
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Affiliation(s)
- A Albalat
- Departament de Fisiologia, Facultat de Biologia, Universitat de Barcelona, Avda. Diagonal 645, Barcelona, E-0807, Spain
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Saranteas T, Tachmintzis A, Katsikeris N, Lykoudis E, Mourouzis I, Anteriotis D, Alexopoulos C, Dimakopoulou A, Dimitriou V, Pantos C, Tesseromatis C. Perioperative thyroid hormone kinetics in patients undergoing major oral and maxillofacial operations. J Oral Maxillofac Surg 2007; 65:408-14. [PMID: 17307585 DOI: 10.1016/j.joms.2005.12.067] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2005] [Revised: 11/19/2005] [Accepted: 12/23/2005] [Indexed: 11/24/2022]
Abstract
PURPOSE The aim of this study was to investigate the perioperative response of serum thyroid hormones in patients who underwent extensive maxillofacial operations with desflurane (0.2 to 1.5 MAC) and remifentanil (0.05 to 0.3 microg/kg/min) anesthesia. MATERIALS AND METHODS Serum thyroxine, total and free triiodothyronine, thyroid-stimulating hormone, interleukin-1beta and 6, TNF-alpha, free fatty acids, S100B protein, CRP, as well as amyloid A protein were measured in 13 patients subjected to extensive oral and maxillofacial operations. Samples were collected before anesthesia induction, at the end, and 6, 12, 24, and 72 hours after the end of surgery. Patients during the study fasted, and at the postoperative period received Ringer's saline or with 5% dextrose alternatively, at the rate of 0.5 to 1.5 mL/kg/hr. RESULTS Thyroid hormones concentrations showed a significant decrease over time whereas their values recovered to the baseline 72 hours after surgery. Interleukin 1beta, 6, S100B protein, CRP, serum amyloid A protein, and free fatty acids showed a significant increase 6, 12, and 24 hours after the end of the operation as related to the basal value. No significant clinical complications were recorded over the study. CONCLUSION Patients undergoing extensive oral and maxillofacial surgery exhibit marked decrease in serum thyroid hormones. Stress response, anesthesia, and perioperative fasting may be decisive factors eliciting this response. These metabolic derangements do not deteriorate the clinical outcome and subsequently may be an adaptive response for energy preservation in various organs.
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Affiliation(s)
- Theodosios Saranteas
- Department of Pharmacology, University of Athens, and Department of Anaesthesiology, General Hospital of Athens, Greece.
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41
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Bonnet M, Faulconnier Y, Hocquette JF, Bocquier F, Leroux C, Martin P, Chilliard Y. Nutritional status induces divergent variations of GLUT4 protein content, but not lipoprotein lipase activity, between adipose tissues and muscles in adult cattle. Br J Nutr 2007; 92:617-25. [PMID: 15522130 DOI: 10.1079/bjn20041240] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Metabolic adaptations to variations in food supply are incompletely understood in ruminant animal adipose tissue (AT) and muscle. To explore this, we studied lipid metabolism and glucose transport potential in one internal and one external AT, as well as in one oxidative and one glycolytic muscle from control, 7 d underfed and 21 d refed adult cows. Refeeding increased (+79 to +307 %) the activities of enzymes involved inde novolipogenesis (fatty acid synthase, malic enzyme, glucose-6-phosphate dehydrogenase) in perirenal and subcutaneous AT; underfeeding did not modify these variables. Underfeeding decreased the activities of lipoprotein lipase (LPL) in perirenal AT (−70 %) and cardiac muscle (−67 %), but did not modify the activities in subcutaneous AT andlongissimus thoracis. Refeeding increased LPL activities in all tissues (+40 to +553 %) to levels comparable with (cardiac muscle) or greater than (AT,longissimus thoracis) those observed in control cows. Such variations in perirenal and cardiac muscle LPL activities did not result from variations in LPL mRNA levels, but suggest a post-transcriptional regulation of LPL in these nutritional conditions. Underfeeding did not modify GLUT4 contents in perirenal AT and muscles, while refeeding increased it only in perirenal AT (+250 %). Our present results contrast with previous results in rats, where LPL is regulated in opposite directions in AT and muscles, and GLUT4 is generally increased by fasting and decreased by refeeding in skeletal muscles. The present results highlight the bovine specificity of the response, which probably arises in part from peculiarities of ruminant animals for nutrient digestion and absorption.
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Affiliation(s)
- Muriel Bonnet
- INRA, Unité de Recherches sur les Herbivores, Theix, 63122 Saint-Genès-Champanelle, France
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42
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Frayn KN, Arner P, Yki-Järvinen H. Fatty acid metabolism in adipose tissue, muscle and liver in health and disease. Essays Biochem 2007; 42:89-103. [PMID: 17144882 DOI: 10.1042/bse0420089] [Citation(s) in RCA: 194] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Fat is the largest energy reserve in mammals. Most tissues are involved in fatty acid metabolism, but three are quantitatively more important than others: adipose tissue, skeletal muscle and liver. Each of these tissues has a store of triacylglycerol that can be hydrolysed (mobilized) in a regulated way to release fatty acids. In the case of adipose tissue, these fatty acids may be released into the circulation for delivery to other tissues, whereas in muscle they are a substrate for oxidation and in liver they are a substrate for re-esterification within the endoplasmic reticulum to make triacylglycerol that will be secreted as very-low-density lipoprotein. These pathways are regulated, most clearly in the case of adipose tissue. Adipose tissue fat storage is stimulated, and fat mobilization suppressed, by insulin, leading to a drive to store energy in the fed state. Muscle fatty acid metabolism is more sensitive to physical activity, during which fatty acid utilization from extracellular and intracellular sources may increase enormously. The uptake of fat by the liver seems to depend mainly upon delivery in the plasma, but the secretion of very-low-density lipoprotein triacylglycerol is suppressed by insulin. There is clearly cooperation amongst the tissues, so that, for instance, adipose tissue fat mobilization increases to meet the demands of skeletal muscle during exercise. When triacylglycerol accumulates excessively in skeletal muscle and liver, sometimes called ectopic fat deposition, then the condition of insulin resistance arises. This may reflect a lack of exercise and an excess of fat intake.
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Affiliation(s)
- Keith N Frayn
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LJ, UK.
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43
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Sukonina V, Lookene A, Olivecrona T, Olivecrona G. Angiopoietin-like protein 4 converts lipoprotein lipase to inactive monomers and modulates lipase activity in adipose tissue. Proc Natl Acad Sci U S A 2006; 103:17450-5. [PMID: 17088546 PMCID: PMC1859949 DOI: 10.1073/pnas.0604026103] [Citation(s) in RCA: 312] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Lipoprotein lipase (LPL) has a central role in lipoprotein metabolism to maintain normal lipoprotein levels in blood and, through tissue specific regulation of its activity, to determine when and in what tissues triglycerides are unloaded. Recent data indicate that angiopoietin-like protein (Angptl)-4 inhibits LPL and retards lipoprotein catabolism. We demonstrate here that the N-terminal coiled-coil domain of Angptl-4 binds transiently to LPL and that the interaction results in conversion of the enzyme from catalytically active dimers to inactive, but still folded, monomers with decreased affinity for heparin. Inactivation occurred with less than equimolar ratios of Angptl-4 to LPL, was strongly temperature-dependent, and did not consume the Angptl-4. Furthermore, we show that Angptl-4 mRNA in rat adipose tissue turns over rapidly and that changes in the Angptl-4 mRNA abundance are inversely correlated to LPL activity, both during the fed-to-fasted and fasted-to-fed transitions. We conclude that Angptl-4 is a fasting-induced controller of LPL in adipose tissue, acting extracellularly on the native conformation in an unusual fashion, like an unfolding molecular chaperone.
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Affiliation(s)
- Valentina Sukonina
- *Department of Medical Biosciences, Umeå University, SE-901 87 Umeå, Sweden; and
| | - Aivar Lookene
- *Department of Medical Biosciences, Umeå University, SE-901 87 Umeå, Sweden; and
- Department of Gene Technology, Tallinn University of Technology, 12618 Tallinn, Estonia
| | - Thomas Olivecrona
- *Department of Medical Biosciences, Umeå University, SE-901 87 Umeå, Sweden; and
| | - Gunilla Olivecrona
- *Department of Medical Biosciences, Umeå University, SE-901 87 Umeå, Sweden; and
- To whom correspondence should be addressed at:
Department of Medical Biosciences, Building 6M, Third Floor, Umeå University, SE-901 87 Umeå, Sweden. E-mail:
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Pulawa LK, Jensen DR, Coates A, Eckel RH. Reduction of plasma triglycerides in apolipoprotein C-II transgenic mice overexpressing lipoprotein lipase in muscle. J Lipid Res 2006; 48:145-51. [PMID: 17018885 DOI: 10.1194/jlr.m600384-jlr200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
LPL and its specific physiological activator, apolipoprotein C-II (apoC-II), regulate the hydrolysis of triglycerides (TGs) from circulating TG-rich lipoproteins. Previously, we developed a skeletal muscle-specific LPL transgenic mouse that had lower plasma TG levels. ApoC-II transgenic mice develop hypertriglyceridemia attributed to delayed clearance. To investigate whether overexpression of LPL could correct this apoC-II-induced hypertriglyceridemia, mice with overexpression of human apoC-II (CII) were cross-bred with mice with two levels of muscle-specific human LPL overexpression (LPL-L or LPL-H). Plasma TG levels were 319 +/- 39 mg/dl in CII mice and 39 +/- 5 mg/dl in wild-type mice. Compared with CII mice, apoC-II transgenic mice with the higher level of LPL overexpression (CIILPL-H) had a 50% reduction in plasma TG levels (P = 0.013). Heart LPL activity was reduced by approximately 30% in mice with the human apoC-II transgene, which accompanied a more modest 10% decrease in total LPL protein. Overexpression of human LPL in skeletal muscle resulted in dose-dependent reduction of plasma TGs in apoC-II transgenic mice. Along with plasma apoC-II concentrations, heart and skeletal muscle LPL activities were predictors of plasma TGs. These data suggest that mice with the human apoC-II transgene may have alterations in the expression/activity of endogenous LPL in the heart. Furthermore, the decrease of LPL activity in the heart, along with the inhibitory effects of excess apoC-II, may contribute to the hypertriglyceridemia observed in apoC-II transgenic mice.
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Affiliation(s)
- Leslie K Pulawa
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado at Denver and Health Sciences Center, Aurora, CO, USA
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Vanisree AJ, Sudha N. Curcumin Combats Against Cigarette Smoke and Ethanol-Induced Lipid Alterationsin Rat Lung and Liver. Mol Cell Biochem 2006; 288:115-23. [PMID: 16691314 DOI: 10.1007/s11010-006-9127-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2005] [Accepted: 01/09/2006] [Indexed: 11/27/2022]
Abstract
BACKGROUND Human population, in spite of the medical and scientific achievements, still fall as a prey to the evils of habitual smoking and alcohol, thus necessitating safer counteracting measures. OBJECTIVE To evaluate the effect of cotreatment of curcumin (Curcuma longa) in rats subjected to acute exposure to cigarette smoke (CS) and ethanol (EtOH). METHODOLOGY Of the four groups of experimental rats, a set of rats was subjected to whole body exposure to cigarette smoke along with ethanol administration serving as a model of CS+EtOH injury. Curcumin treatment was given to two sets of rats: (i) one set receiving simultaneous CS+EtOH and (ii) one set of normal rats without any administration. The other group of rats served as control. Blood, liver and lung of rats were selected for assessment of CS+EtOH injury as well as curcumin treatment. RESULT Altered lipid, lipoprotein profile and bile acid excretion were observed in CS+EtOH rats along with premalignant pathological state in tissues. In treated rats, the levels were maintained at near-normal levels along with near-normal histology. CONCLUSION This biochemical picture on cotreatment with curcumin suggests that curcumin could counteract the injurious effects of combined CS and EtOH and thus might help to reduce the risk of hyperlipidemic disorders which develop due to smoking and drinking.
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Affiliation(s)
- A J Vanisree
- Department of Biochemistry, University of Madras, Guindy Campus, Chennai, 600033, Tamilnadu, India.
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Albalat A, Sánchez-Gurmaches J, Gutiérrez J, Navarro I. Regulation of lipoprotein lipase activity in rainbow trout (Oncorhynchus mykiss) tissues. Gen Comp Endocrinol 2006; 146:226-35. [PMID: 16457827 DOI: 10.1016/j.ygcen.2005.11.011] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2005] [Revised: 11/14/2005] [Accepted: 11/21/2005] [Indexed: 10/25/2022]
Abstract
Lipoprotein lipase (LPL) is considered as a key enzyme in the lipid deposition and metabolism of many tissues. Information on LPL activity and its regulation in fish remains very scarce. In the present study, we have examined the nutritional regulation of LPL activity by conducting post-feeding and fasting experiments in rainbow trout (Oncorhynchus mykiss). As insulin plays an important role in the nutritional regulation of LPL activity in mammals, the effects of this hormone were tested in vivo by intraperitoneal administration. Moreover, we conducted in vitro studies using fat pads of rainbow trout to better clarify the direct role of insulin and tumor necrosis factor-alpha (TNFalpha) as possible regulators of LPL activity in rainbow trout. LPL activity in adipose tissue increased in response to feeding, 4h after ingestion of food, then decreasing to basal levels at 6h. No clear response was found in either red or white muscles, where LPL values were lower. Moreover, fasting produced a down-regulation of LPL activity in adipose tissue, concomitant with low levels of plasma insulin. While insulin administration stimulated LPL activity of adipose tissue 3h after injection, no response was observed in red or white muscles. Finally, in vitro studies using fat pads revealed that insulin significantly stimulated the proportion of LPL in active conformation at the extracellular level. On the other hand, TNFalpha did not greatly affect LPL activity using this in vitro model. These data indicate that LPL activity is regulated in a tissue-specific manner following food intake, and suggest that insulin is an important regulator of LPL activity in the adipose tissue of rainbow trout.
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Affiliation(s)
- Amaya Albalat
- Departament de Fisiologia, Facultat de Biologia, Universitat de Barcelona, Avda. Diagonal 645, Barcelona, Spain
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47
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Lindegaard MLS, Olivecrona G, Christoffersen C, Kratky D, Hannibal J, Petersen BL, Zechner R, Damm P, Nielsen LB. Endothelial and lipoprotein lipases in human and mouse placenta. J Lipid Res 2005; 46:2339-46. [PMID: 16150822 DOI: 10.1194/jlr.m500277-jlr200] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Placenta expresses various lipase activities. However, a detailed characterization of the involved genes and proteins is lacking. In this study, we compared the expression of endothelial lipase (EL) and LPL in human term placenta. When placental protein extracts were separated by heparin-Sepharose affinity chromatography, the EL protein eluted as a single peak without detectable phospholipid or triglyceride (TG) lipase activity. The major portion of LPL protein eluted slightly after EL. This peak also had no lipase activity and most likely contained monomeric LPL. Fractions eluting at a higher NaCl concentration contained small amounts of LPL protein (most likely dimeric LPL) and had substantial TG lipase activity. In situ hybridization studies showed EL mRNA expression in syncytiotrophoblasts and endothelial cells and LPL mRNA in syncytiotrophoblasts. In contrast, immunohistochemistry showed EL and LPL protein associated with both cell types. In mouse placentas, lack of LPL expression resulted in increased EL mRNA expression. These results suggest that the cellular expression of EL and LPL in human placenta is different. Nevertheless, the two lipases might have overlapping functions in the mouse placenta. Our data also suggest that the major portions of both proteins are stored in an inactive form in human term placenta.
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Affiliation(s)
- Marie L S Lindegaard
- Department of Clinical Biochemistry, Rigshospitalet, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark
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Zhang L, Lookene A, Wu G, Olivecrona G. Calcium triggers folding of lipoprotein lipase into active dimers. J Biol Chem 2005; 280:42580-91. [PMID: 16179346 DOI: 10.1074/jbc.m507252200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The active form of lipoprotein lipase (LPL) is a noncovalent homodimer of 55-kDa subunits. The dimer is unstable and tends to undergo irreversible dissociation into inactive monomers. We noted that a preparation of such monomers slowly regained traces of activity under assay conditions with substrate, heparin, and serum or in cell culture medium containing serum. We therefore studied the refolding pathway of LPL after full denaturation in 6 M guanidinium chloride or after dissociation into monomers in 1 M guanidinium chloride. In crude systems, we identified serum as the factor promoting reactivation. Further investigations demonstrated that Ca2+ was the crucial component in serum for reactivation of LPL and that refolding involved at least two steps. Studies of far-UV circular dichroism, fluorescence, and proteolytic cleavage patterns showed that LPL started to refold from the C-terminal domain, independent of calcium. The first step was rapid and resulted in formation of an inactive monomer with a completely folded C-terminal domain, whereas the N-terminal domain was in the molten globule state. The second step was promoted by Ca2+ and converted LPL monomers from the molten globule state to dimerization-competent and more tightly folded monomers that rapidly formed active LPL dimers. The second step was slow, and it appears that proline isomerization (rather than dimerization as such) is rate-limiting. Inactive monomers isolated from human tissue recovered activity under the influence of Ca2+. We speculate that Ca2+-dependent control of LPL dimerization might be involved in the normal post-translational regulation of LPL activity.
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Affiliation(s)
- Liyan Zhang
- Department of Medical Biosciences, Physiological Chemistry, Umeå University, SE-901 87 Umeå, Sweden
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Lladó I, Pons A, Palou A. Effects of fasting on lipoprotein lipase activity in different depots of white and brown adipose tissues in diet-induced overweight rats. J Nutr Biochem 2005; 10:609-14. [PMID: 15539256 DOI: 10.1016/s0955-2863(99)00050-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/1999] [Accepted: 07/07/1999] [Indexed: 11/21/2022]
Abstract
The aim of the present study was to evaluate the effects of 24 hours of starvation on lipoprotein lipase (LPL) activity in various depots of white and brown adipose tissues in control rats and in rats with two different degrees of overweight, both induced by dietary treatment. In control rats, no changes in LPL immunoreactive mass were observed in either white or brown adipose tissues after fasting, whereas the effects of food deprivation on enzyme activity were opposite in white versus brown adipose tissues. The LPL activity response to fasting was impaired by obesity: White adipose depots of cafeteria obese rats showed a lower ability to downregulate LPL during fasting and the increased LPL activity induced by fasting in brown adipose depots was less intense in the obese rats compared with control animals. When the degree of overweight was reduced, the differences between obese and control rats were also attenuated.
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Affiliation(s)
- I Lladó
- Laboratori de Bioquímica i Biologia Molecular, Department de Biologia Fonamental i Ciències de la Salut, Universitat de les Illes Balears, Palma de Mallorca, Spain
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Ruge T, Svensson M, Eriksson JW, Olivecrona G. Tissue-specific regulation of lipoprotein lipase in humans: effects of fasting. Eur J Clin Invest 2005; 35:194-200. [PMID: 15733074 DOI: 10.1111/j.1365-2362.2005.01470.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND We have previously reported that the activity of lipoprotein lipase (LPL) measured in postheparin plasma from humans fasted for 30 h is increased relative to the fed state. This is in contrast to laboratory animals, where the strong down-regulation of LPL in their adipose tissue on fasting is reflected in decreased levels of LPL activity in postheparin plasma. MATERIALS AND METHODS To search for the tissue source of the increase in LPL activity on fasting of humans, young, healthy subjects were fasted for 10, 20 or 30 h, and LPL was measured in plasma (pre- and postheparin) and in biopsies from subcutaneous adipose tissue (abdominal) and from a skeletal muscle (tibialis anterior). Both LPL activity and LPL protein mass were measured in the tissue homogenates. Values after fasting were compared with values from postprandial samples obtained 2 h after a meal. RESULTS Fasting for up to 30 h did not alter LPL activity in basal plasma (preheparin). LPL activity in postheparin plasma remained unchanged after 10 and 20 h of fasting, but was increased by 50% after 30 h (P < 0.05). Ten hours of fasting caused a 25% (P < 0.05) decrease in LPL activity in subcutaneous adipose tissue, while LPL activity in skeletal muscle remained unchanged. After 30 h of fasting, both LPL activity and mass had decreased by approximately 50% (P < 0.05) in adipose tissue, but had increased by approximately 100% (P < 0.05) in muscle. CONCLUSIONS The increase in postheparin plasma LPL activity after 30 h of total food deprivation of healthy human subjects seemed to reflect an increased activity and mass of LPL in skeletal muscle.
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Affiliation(s)
- T Ruge
- Department of Public Health and Clinical Medicine, Umeå University, SE-901 87 Umeå, Sweden
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