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Bays HE. Obesity, dyslipidemia, and cardiovascular disease: A joint expert review from the Obesity Medicine Association and the National Lipid Association 2024. Obes Pillars 2024; 10:100108. [PMID: 38706496 PMCID: PMC11066689 DOI: 10.1016/j.obpill.2024.100108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2024] [Revised: 03/06/2024] [Accepted: 03/07/2024] [Indexed: 05/07/2024]
Abstract
Background This joint expert review by the Obesity Medicine Association (OMA) and National Lipid Association (NLA) provides clinicians an overview of the pathophysiologic and clinical considerations regarding obesity, dyslipidemia, and cardiovascular disease (CVD) risk. Methods This joint expert review is based upon scientific evidence, clinical perspectives of the authors, and peer review by the OMA and NLA leadership. Results Among individuals with obesity, adipose tissue may store over 50% of the total body free cholesterol. Triglycerides may represent up to 99% of lipid species in adipose tissue. The potential for adipose tissue expansion accounts for the greatest weight variance among most individuals, with percent body fat ranging from less than 5% to over 60%. While population studies suggest a modest increase in blood low-density lipoprotein cholesterol (LDL-C) levels with excess adiposity, the adiposopathic dyslipidemia pattern most often described with an increase in adiposity includes elevated triglycerides, reduced high density lipoprotein cholesterol (HDL-C), increased non-HDL-C, elevated apolipoprotein B, increased LDL particle concentration, and increased small, dense LDL particles. Conclusions Obesity increases CVD risk, at least partially due to promotion of an adiposopathic, atherogenic lipid profile. Obesity also worsens other cardiometabolic risk factors. Among patients with obesity, interventions that reduce body weight and improve CVD outcomes are generally associated with improved lipid levels. Given the modest improvement in blood LDL-C with weight reduction in patients with overweight or obesity, early interventions to treat both excess adiposity and elevated atherogenic cholesterol (LDL-C and/or non-HDL-C) levels represent priorities in reducing the risk of CVD.
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Affiliation(s)
- Harold Edward Bays
- Corresponding author. Louisville Metabolic and Atherosclerosis Research Center, Louisville, KY, 40213, USA.
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2
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Jin Y, Kozan D, Anderson JL, Hensley M, Shen MC, Wen J, Moll T, Kozan H, Rawls JF, Farber SA. A high-cholesterol zebrafish diet promotes hypercholesterolemia and fasting-associated liver triglycerides accumulation. bioRxiv 2023:2023.11.01.565134. [PMID: 37961364 PMCID: PMC10635069 DOI: 10.1101/2023.11.01.565134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Zebrafish are an ideal model organism to study lipid metabolism and to elucidate the molecular underpinnings of human lipid-associated disorders. In this study, we provide an improved protocol to assay the impact of a high-cholesterol diet (HCD) on zebrafish lipid deposition and lipoprotein regulation. Fish fed HCD developed hypercholesterolemia as indicated by significantly elevated ApoB-containing lipoproteins (ApoB-LP) and increased plasma levels of cholesterol and cholesterol esters. Feeding of the HCD to larvae (8 days followed by a 1 day fast) and adult female fish (2 weeks, followed by 3 days of fasting) was also associated with a fatty liver phenotype that presented as severe hepatic steatosis. The HCD feeding paradigm doubled the levels of liver triacylglycerol (TG), which was striking because our HCD was only supplemented with cholesterol. The accumulated liver TG was unlikely due to increased de novo lipogenesis or inhibited β-oxidation since no differentially expressed genes in these pathways were found between the livers of fish fed the HCD versus control diets. However, fasted HCD fish had significantly increased lipogenesis gene fasn in adipose tissue and higher free fatty acids (FFA) in plasma. This suggested that elevated dietary cholesterol resulted in lipid accumulation in adipocytes, which supplied more FFA during fasting, promoting hepatic steatosis. In conclusion, our HCD zebrafish protocol represents an effective and reliable approach for studying the temporal characteristics of the physiological and biochemical responses to high levels of dietary cholesterol and provides insights into the mechanisms that may underlie fatty liver disease.
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Affiliation(s)
- Yang Jin
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, United States
- Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Aas, Norway
| | - Darby Kozan
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, United States
- Department of Biology, Johns Hopkins University, Baltimore, MD, United States
| | - Jennifer L Anderson
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, United States
| | - Monica Hensley
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, United States
| | - Meng-Chieh Shen
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, United States
| | - Jia Wen
- Department of Molecular Genetics and Microbiology, Duke Microbiome Center, Duke University School of Medicine, Durham, NC, United States
| | - Tabea Moll
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, United States
- Department of Biology, Johns Hopkins University, Baltimore, MD, United States
| | - Hannah Kozan
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, United States
| | - John F. Rawls
- Department of Molecular Genetics and Microbiology, Duke Microbiome Center, Duke University School of Medicine, Durham, NC, United States
| | - Steven A. Farber
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, United States
- Department of Biology, Johns Hopkins University, Baltimore, MD, United States
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3
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Awadh AA. The Role of Cytosolic Lipid Droplets in Hepatitis C Virus Replication, Assembly, and Release. Biomed Res Int 2023; 2023:5156601. [PMID: 37090186 PMCID: PMC10121354 DOI: 10.1155/2023/5156601] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Revised: 03/02/2023] [Accepted: 03/09/2023] [Indexed: 04/25/2023]
Abstract
The hepatitis C virus (HCV) causes chronic hepatitis by establishing a persistent infection. Patients with chronic hepatitis frequently develop hepatic cirrhosis, which can lead to liver cancer-the progressive liver damage results from the host's immune response to the unresolved infection. The HCV replication process, including the entry, replication, assembly, and release stages, while the virus circulates in the bloodstream, it is intricately linked to the host's lipid metabolism, including the dynamic of the cytosolic lipid droplets (cLDs). This review article depicts how this interaction regulates viral cell tropism and aids immune evasion by coining viral particle characteristics. cLDs are intracellular organelles that store most of the cytoplasmic components of neutral lipids and are assumed to play an increasingly important role in the pathophysiology of lipid metabolism and host-virus interactions. cLDs are involved in the replication of several clinically significant viruses, where viruses alter the lipidomic profiles of host cells to improve viral life cycles. cLDs are involved in almost every phase of the HCV life cycle. Indeed, pharmacological modulators of cholesterol synthesis and intracellular trafficking, lipoprotein maturation, and lipid signaling molecules inhibit the assembly of HCV virions. Likewise, small-molecule inhibitors of cLD-regulating proteins inhibit HCV replication. Thus, addressing the molecular architecture of HCV replication will aid in elucidating its pathogenesis and devising preventive interventions that impede persistent infection and prevent disease progression. This is possible via repurposing the available therapeutic agents that alter cLDs metabolism. This review highlights the role of cLD in HCV replication.
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Affiliation(s)
- Abdullah A. Awadh
- Department of Basic Medical Sciences, College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Jeddah 21423, Saudi Arabia
- King Abdullah International Medical Research Center, Jeddah 21423, Saudi Arabia
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4
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Abstract
Lipid droplet biogenesis comprises the emergence of cytosolic lipid droplets with a typical diameter 0.1-5 μm via synthesis of fat in the endoplasmatic reticulum, the formation of membrane-embedded lenses, and the eventual budding of lenses into solution as droplets. Lipid droplets in cells are increasingly being viewed as highly dynamic organelles with multiple functions in cell physiology. However, the mechanism of droplet formation in cells remains poorly understood, partly because their formation involves the rapid transformation of transient lipid structures that are difficult to capture. Thus, the development of controlled experimental systems that model lipid biogenesis is highly relevant for an enhanced mechanistic understanding. Here we prepare and characterize triolein (TO) lenses in a multilamellar spin-coated phosphatidylcholine (POPC) film and determine the lens nucleation threshold to 0.25-0.5% TO. The TO lens shapes are characterized by atomic force microscopy (AFM) including their mean cap angle ⟨α⟩ = 27.3° and base radius ⟨a⟩ = 152.7 nm. A cross-correlation analysis of corresponding AFM and fluorescence images confirms that TO is localized to lenses. Hydration of the lipid/lens film induces the gel to fluid membrane phase transition and makes the lenses more mobile. The budding of free droplets into solution from membrane lenses is detected by observing a change in motion from confined wiggling to ballistic motion of droplets in solution. The results confirm that droplet budding can occur spontaneously without being facilitated by proteins. The developed model system provides a controlled platform for testing mechanisms of lipid droplet biogenesis in vitro and addressing questions related to lens formation and droplet budding by quantitative image analysis.
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Affiliation(s)
- Frederik Viktor Hegaard
- Department of Physics, Chemistry and Pharmacy (FKF), PhyLife - Physical LifeScience, University of Southern Denmark (SDU), Campusvej 55, 5230 Odense M, Denmark
| | - Martin Berg Klenow
- Department of Physics, Chemistry and Pharmacy (FKF), PhyLife - Physical LifeScience, University of Southern Denmark (SDU), Campusvej 55, 5230 Odense M, Denmark
| | - Adam Cohen Simonsen
- Department of Physics, Chemistry and Pharmacy (FKF), PhyLife - Physical LifeScience, University of Southern Denmark (SDU), Campusvej 55, 5230 Odense M, Denmark
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Karakus E, Schmid A, Leiting S, Fühler B, Schäffler A, Jakob T, Geyer J. Role of the Steroid Sulfate Uptake Transporter Soat (Slc10a6) in Adipose Tissue and 3T3-L1 Adipocytes. Front Mol Biosci 2022; 9:863912. [PMID: 35573729 PMCID: PMC9095825 DOI: 10.3389/fmolb.2022.863912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 03/24/2022] [Indexed: 11/22/2022] Open
Abstract
In addition to the endocrine and paracrine systems, peripheral tissues such as gonads, skin, and adipose tissue are involved in the intracrine mechanisms responsible for the formation of sex steroids via the transformation of dehydroepiandrosterone and dehydroepiandrosterone sulfate (DHEA/DHEAS) into potent androgenic and estrogenic hormones. Numerous studies have examined the relationship between overweight, central obesity, and plasma levels of DHEA and DHEAS. The sodium-dependent organic anion transporter Soat (Slc10a6) is a plasma membrane uptake transporter for sulfated steroids. Significantly increased expression of Slc10a6 mRNA has been previously described in organs and tissues of lipopolysaccharide (LPS)-treated mice, including white adipose tissue. These findings suggest that Soat plays a role in the supply of steroids in peripheral target tissues. The present study aimed to investigate the expression of Soat in adipocytes and its role in adipogenesis. Soat expression was analyzed in mouse white intra-abdominal (WAT), subcutaneous (SAT), and brown (BAT) adipose tissue samples and in murine 3T3-L1 adipocytes. In addition, adipose tissue mass and size of the adipocytes were analyzed in wild-type and Slc10a6−/− knockout mice. Soat expression was detected in mouse WAT, SAT, and BAT using immunofluorescence. The expression of Slc10a6 mRNA was significantly higher in 3T3-L1 adipocytes than that of preadipocytes and was significantly upregulated by exposure to lipopolysaccharide (LPS). Slc10a6 mRNA levels were also upregulated in the adipose tissue of LPS-treated mice. In Slc10a6−/− knockout mice, adipocytes increased in size in the WAT and SAT of female mice and in the BAT of male mice, suggesting adipocyte hypertrophy. The serum levels of adiponectin, resistin, and leptin were comparable in wild-type and Slc10a6−/− knockout mice. The treatment of 3T3-L1 adipocytes with DHEA significantly reduced lipid accumulation, while DHEAS did not have a significant effect. However, following LPS-induced Soat upregulation, DHEAS also significantly inhibited lipid accumulation in adipocytes. In conclusion, Soat-mediated import of DHEAS and other sulfated steroids could contribute to the complex pathways of sex steroid intracrinology in adipose tissues. Although in cell cultures the Soat-mediated uptake of DHEAS appears to reduce lipid accumulation, in Slc10a6−/− knockout mice, the Soat deletion induced adipocyte hyperplasia through hitherto unknown mechanisms.
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Affiliation(s)
- Emre Karakus
- Institute of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Justus Liebig University, Giessen, Germany
| | - Andreas Schmid
- Department of Internal Medicine III, Giessen University Hospital, Justus Liebig University, Giessen, Germany
| | - Silke Leiting
- Institute of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Justus Liebig University, Giessen, Germany
| | - Bärbel Fühler
- Institute of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Justus Liebig University, Giessen, Germany
| | - Andreas Schäffler
- Department of Internal Medicine III, Giessen University Hospital, Justus Liebig University, Giessen, Germany
| | - Thilo Jakob
- Department of Dermatology and Allergology, Giessen University Hospital, Justus Liebig University, Giessen, Germany
| | - Joachim Geyer
- Institute of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Justus Liebig University, Giessen, Germany
- *Correspondence: Joachim Geyer,
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6
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Jurášek M, Valečka J, Novotný I, Kejík Z, Fähnrich J, Marešová A, Tauchen J, Bartůněk P, Dolenský B, Jakubek M, Drašar PB, Králová J. Synthesis and biological evaluation of cationic TopFluor cholesterol analogues. Bioorg Chem 2021; 117:105410. [PMID: 34700109 DOI: 10.1016/j.bioorg.2021.105410] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 04/25/2021] [Accepted: 10/03/2021] [Indexed: 12/17/2022]
Abstract
Cholesterol is not only a major component of the cell membrane, but also plays an important role in a wide range of biological processes and pathologies. It is therefore crucial to develop appropriate tools for visualizing intracellular cholesterol transport. Here, we describe new cationic analogues of BODIPY-Cholesterol (TopFluor-Cholesterol, TF-Chol), which combine a positive charge on the sterol side chain and a BODIPY group connected via a C-4 linker. In contrast to TF-Chol, the new analogues TF-1 and TF-3 possessing acetyl groups on the A ring (C-3 position on steroid) internalized much faster and displayed slightly different levels of intracellular localization. Their applicability for cholesterol monitoring was indicated by the fact that they strongly label compartments with accumulated cholesterol in cells carrying a mutation of the Niemann-Pick disease-associated cholesterol transporter, NPC1.
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Affiliation(s)
- Michal Jurášek
- University of Chemistry and Technology, Technická 5, 166 28 Prague 6, Czech Republic
| | - Jan Valečka
- Light microscopy core facility, Institute of Molecular Genetics of the Czech Academy of Sciences, v.v.i., Vídeňská 1083, 142 20 Prague 4, Czech Republic
| | - Ivan Novotný
- Light microscopy core facility, Institute of Molecular Genetics of the Czech Academy of Sciences, v.v.i., Vídeňská 1083, 142 20 Prague 4, Czech Republic
| | - Zdeněk Kejík
- University of Chemistry and Technology, Technická 5, 166 28 Prague 6, Czech Republic
| | - Jan Fähnrich
- University of Chemistry and Technology, Technická 5, 166 28 Prague 6, Czech Republic
| | - Anna Marešová
- University of Chemistry and Technology, Technická 5, 166 28 Prague 6, Czech Republic
| | - Jan Tauchen
- Czech University of Life Sciences Prague, Kamýcká 129, 165 00 Prague 6, Czech Republic
| | - Petr Bartůněk
- CZ-OPENSCREEN, Institute of Molecular Genetics of the Czech Academy of Sciences, v.v.i., Vídeňská 1083, 142 20 Prague 4, Czech Republic
| | - Bohumil Dolenský
- University of Chemistry and Technology, Technická 5, 166 28 Prague 6, Czech Republic
| | - Milan Jakubek
- University of Chemistry and Technology, Technická 5, 166 28 Prague 6, Czech Republic
| | - Pavel B Drašar
- University of Chemistry and Technology, Technická 5, 166 28 Prague 6, Czech Republic
| | - Jarmila Králová
- CZ-OPENSCREEN, Institute of Molecular Genetics of the Czech Academy of Sciences, v.v.i., Vídeňská 1083, 142 20 Prague 4, Czech Republic.
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7
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Yu L, Fan J, Zhou C, Xu C. Sterols are required for the coordinated assembly of lipid droplets in developing seeds. Nat Commun 2021; 12:5598. [PMID: 34552075 DOI: 10.1038/s41467-021-25908-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 09/09/2021] [Indexed: 12/23/2022] Open
Abstract
Lipid droplets (LDs) are intracellular organelles critical for energy storage and lipid metabolism. They are typically composed of an oil core coated by a monolayer of phospholipids and proteins such as oleosins. The mechanistic details of LD biogenesis remain poorly defined. However, emerging evidence suggest that their formation is a spatiotemporally regulated process, occurring at specific sites of the endoplasmic reticulum defined by a specific set of lipids and proteins. Here, we show that sterols are required for formation of oleosin-coated LDs in Arabidopsis. Analysis of sterol pathway mutants revealed that deficiency in several ∆5-sterols accounts for the phenotype. Importantly, mutants deficient in these sterols also display reduced LD number, increased LD size and reduced oil content in seeds. Collectively, our data reveal a role of sterols in coordinating the synthesis of oil and oleosins and their assembly into LDs, highlighting the importance of membrane lipids in regulating LD biogenesis. Lipid droplet biogenesis originates at the endoplasmic reticulum and is defined by a specific set of lipids and proteins. Here, the authors show that sterols play an important role in coordinating oil and oleosin biosynthesis for the formation of lipid droplets in plant leaves and seeds.
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8
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González-Hódar L, McDonald JG, Vale G, Thompson BM, Figueroa AM, Tapia PJ, Robledo F, Agarwal AK, Garg A, Horton JD, Cortés V. Decreased caveolae in AGPAT2 lacking adipocytes is independent of changes in cholesterol or sphingolipid levels: A whole cell and plasma membrane lipidomic analysis of adipogenesis. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166167. [PMID: 33989739 DOI: 10.1016/j.bbadis.2021.166167] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 04/19/2021] [Accepted: 05/04/2021] [Indexed: 12/17/2022]
Abstract
BACKGROUND Adipocytes from lipodystrophic Agpat2-/- mice have impaired adipogenesis and fewer caveolae. Herein, we examined whether these defects are associated with changes in lipid composition or abnormal levels of caveolae-associated proteins. Lipidome changes were quantified in differentiated Agpat2-/- adipocytes to identify lipids with potential adipogenic roles. METHODS Agpat2-/- and wild type brown preadipocytes were differentiated in vitro. Plasma membrane was purified by ultracentrifugation. Number of caveolae and caveolae-associated proteins, as well as sterol, sphingolipid, and phospholipid lipidome were determined across differentiation. RESULTS Differentiated Agpat2-/- adipocytes had decreased caveolae number but conserved insulin signaling. Caveolin-1 and cavin-1 levels were equivalent between Agpat2-/- and wild type adipocytes. No differences in PM cholesterol and sphingolipids abundance were detected between genotypes. Levels of phosphatidylserine at day 10 of differentiation were increased in Agpat2-/- adipocytes. Wild type adipocytes had increased whole cell triglyceride, diacylglycerol, phosphatidylglycerol, phosphatidic acid, lysophosphatidylcholine, lysophosphatidylethanolamine, and trihexosyl ceramide, and decreased 24,25-dihydrolanosterol and sitosterol, as a result of adipogenic differentiation. By contrast, adipogenesis did not modify whole cell neutral lipids but increased lysophosphatidylcholine, sphingomyelin, and trihexosyl ceramide levels in Agpat2-/- adipocytes. Unexpectedly, adipogenesis decreased PM levels of main phospholipids in both genotypes. CONCLUSION In Agpat2-/- adipocytes, decreased caveolae is not associated with changes in PM cholesterol nor sphingolipid levels; however, increased PM phosphatidylserine content may be implicated. Abnormal lipid composition is associated with the adipogenic abnormalities of Agpat2 -/- adipocytes but does not prevent insulin signaling.
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Affiliation(s)
- Lila González-Hódar
- Department of Nutrition, Diabetes and Metabolism, School of Medicine, Pontificia Universidad Católica de Chile, 8331150, Chile
| | - Jeffrey G McDonald
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States; Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, United States
| | - Goncalo Vale
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Bonne M Thompson
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Ana-María Figueroa
- Department of Nutrition, Diabetes and Metabolism, School of Medicine, Pontificia Universidad Católica de Chile, 8331150, Chile
| | - Pablo J Tapia
- Department of Nutrition, Diabetes and Metabolism, School of Medicine, Pontificia Universidad Católica de Chile, 8331150, Chile
| | - Fermín Robledo
- Department of Nutrition, Diabetes and Metabolism, School of Medicine, Pontificia Universidad Católica de Chile, 8331150, Chile
| | - Anil K Agarwal
- Division of Nutrition and Metabolic Diseases, Center for Human Nutrition, Department of Internal Medicine, University of Texas Southwestern Medical Center at Dallas, TX 75390, United States
| | - Abhimanyu Garg
- Division of Nutrition and Metabolic Diseases, Center for Human Nutrition, Department of Internal Medicine, University of Texas Southwestern Medical Center at Dallas, TX 75390, United States
| | - Jay D Horton
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States; Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, United States; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, United States.
| | - Víctor Cortés
- Department of Nutrition, Diabetes and Metabolism, School of Medicine, Pontificia Universidad Católica de Chile, 8331150, Chile.
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Ndiaye H, Liu JY, Hall A, Minogue S, Morgan MY, Waugh MG. Immunohistochemical staining reveals differential expression of ACSL3 and ACSL4 in hepatocellular carcinoma and hepatic gastrointestinal metastases. Biosci Rep 2020; 40:BSR20200219. [PMID: 32286604 DOI: 10.1042/BSR20200219] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 04/08/2020] [Accepted: 04/09/2020] [Indexed: 12/24/2022] Open
Abstract
Long-chain fatty acyl CoA synthetases (ACSLs) activate fatty acids by CoA addition thus facilitating their intracellular metabolism. Dysregulated ACSL expression features in several cancers and can affect processes such as ferroptosis, fatty acid β-oxidation, prostaglandin biosynthesis, steroidogenesis and phospholipid acyl chain remodelling. Here we investigate long chain acyl-CoA synthetase 3 (ACSL3) and long chain acyl-CoA synthetase 4 (ACSL4) expression in liver malignancies. The expression and subcellular localisations of the ACSL3 and ACSL4 isoforms in hepatocellular carcinoma (HCC), cholangiocarcinoma (CCA) and hepatic metastases were assessed by immunohistochemical analyses of multiple tumour tissue arrays and by subcellular fractionation of cultured HepG2 cells. The expression of both enzymes was increased in HCC compared with normal liver. Expression of ACSL3 was similar in HCC and hepatic metastases but lower in healthy tissue. Increased ACSL3 expression distinguished HCC from CCA with a sensitivity of 87.2% and a specificity of 75%. ACSL4 expression was significantly greater in HCC than in all other tumours and distinguished HCC from normal liver tissue with a sensitivity of 93.8% and specificity of 93.6%. Combined ACSL3 and ACSL4 staining scores distinguished HCC from hepatic metastases with 80.1% sensitivity and 77.1% specificity. These enzymes had partially overlapping intracellular distributions, ACSL4 localised to the plasma membrane and both isoforms associated with lipid droplets and the endoplasmic reticulum (ER). In conclusion, analysis of ACSL3 and ACSL4 expression can distinguish different classes of hepatic tumours.
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10
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Heier C, Knittelfelder O, Hofbauer HF, Mende W, Pörnbacher I, Schiller L, Schoiswohl G, Xie H, Grönke S, Shevchenko A, Kühnlein RP. Hormone-sensitive lipase couples intergenerational sterol metabolism to reproductive success. eLife 2021; 10:63252. [PMID: 33538247 PMCID: PMC7880688 DOI: 10.7554/elife.63252] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 02/03/2021] [Indexed: 12/13/2022] Open
Abstract
Triacylglycerol (TG) and steryl ester (SE) lipid storage is a universal strategy to maintain organismal energy and membrane homeostasis. Cycles of building and mobilizing storage fat are fundamental in (re)distributing lipid substrates between tissues or to progress ontogenetic transitions. In this study, we show that Hormone-sensitive lipase (Hsl) specifically controls SE mobilization to initiate intergenerational sterol transfer in Drosophila melanogaster. Tissue-autonomous Hsl functions in the maternal fat body and germline coordinately prevent adult SE overstorage and maximize sterol allocation to embryos. While Hsl-deficiency is largely dispensable for normal development on sterol-rich diets, animals depend on adipocyte Hsl for optimal fecundity when dietary sterol becomes limiting. Notably, accumulation of SE but not of TG is a characteristic of Hsl-deficient cells across phyla including murine white adipocytes. In summary, we identified Hsl as an ancestral regulator of SE degradation, which improves intergenerational sterol transfer and reproductive success in flies.
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Affiliation(s)
- Christoph Heier
- Institute of Molecular Biosciences, University of Graz, Graz, Austria.,BioTechMed-Graz, Graz, Austria
| | - Oskar Knittelfelder
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Harald F Hofbauer
- Institute of Molecular Biosciences, University of Graz, Graz, Austria.,BioTechMed-Graz, Graz, Austria
| | - Wolfgang Mende
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Ingrid Pörnbacher
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Laura Schiller
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Gabriele Schoiswohl
- Institute of Molecular Biosciences, University of Graz, Graz, Austria.,Field of Excellence BioHealth - University of Graz, Graz, Austria
| | - Hao Xie
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Sebastian Grönke
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Andrej Shevchenko
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Ronald P Kühnlein
- Institute of Molecular Biosciences, University of Graz, Graz, Austria.,BioTechMed-Graz, Graz, Austria.,Field of Excellence BioHealth - University of Graz, Graz, Austria.,Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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11
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Abstract
Adipose tissue plays a major role in regulating whole-body energy metabolism. While the biochemical processes regulating storage and release of excess energy are well known, the temporal organization of these events is much less defined. In this study, we have characterized the presence of small surface-associated lipid droplets, distinct from the central droplet, in primary human adipocytes. Based on microscopy analyses, we illustrate the distribution of mitochondria, endoplasmic reticulum and lysosomes in the vicinity of these specialized lipid droplets. Ultrastructure analysis confirmed the presence of small droplets in intact adipose tissue. Further, CIDEC, known to bind and regulate lipid droplet expansion, clearly localized at these lipid droplets. Neither acute or prolonged stimulation with insulin or isoprenaline, or pharmacologic intervention to suppress lipid flux, affected the presence of these lipid droplets. Still, phosphorylated perilipin and hormone-sensitive lipase accumulated at these droplets following adrenergic stimuli, which supports metabolic activity at these locations. Altogether, we propose these lipid droplet clusters represent an intermediate site involved in lipid transport in primary adipocytes.
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Affiliation(s)
- Björn Morén
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Claes Fryklund
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Karin Stenkula
- Department of Experimental Medical Science, Lund University, Lund, Sweden
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12
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Kurokawa Y, Konishi R, Yoshida A, Tomioku K, Tanabe K, Fujita A. Microautophagy in the yeast vacuole depends on the activities of phosphatidylinositol 4-kinases, Stt4p and Pik1p. Biochim Biophys Acta Biomembr 2020; 1862:183416. [PMID: 32726584 DOI: 10.1016/j.bbamem.2020.183416] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 07/10/2020] [Accepted: 07/12/2020] [Indexed: 12/30/2022]
Abstract
Morphologically, the lipophagy in yeast cell mimics microautophagy, which includes a direct amendment of the vacuolar membrane that engulfs lipid droplets (LDs). The molecular mechanism of the membrane modifications that elicits microautophagy still remains elusive. In this study, an analysis of membrane lipid distribution at a nanoscale level showed that PtdIns(4)P is localized in the cytoplasmic leaflet of microautophagic vesicles, which are derived when the vacuole's membrane domains engulfed LDs both in the stationary phase and in acute nitrogen starvation. Furthermore, the PtdIns(4)P-positive raft-like domains engulf LDs through a microautophagic mechanism. When single temperature-conditional mutants of STT4 or PIK1 PtdIns 4-kinases were used, in the vacuole of STT4 and PIK1 mutant cells, microautophagic vesicles drastically decreased at restrictive temperatures, and the labeling density of PtdIns(4)P on the microautophagic vesicles and the sizes of the mutants' microautophagic vesicles also decreased. These results suggest that both Stt4p and Pik1p have important roles in the microautophagy of the vacuole in the stationary phase and under nitrogen starvation conditions.
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Affiliation(s)
- Yuna Kurokawa
- Department of Molecular and Cell Biology and Biochemistry, Basic Veterinary Science, Faculty of Veterinary Medicine, Kagoshima University, Korimoto 1-21-24, Kagoshima 890-0065, Japan
| | - Rikako Konishi
- Department of Molecular and Cell Biology and Biochemistry, Basic Veterinary Science, Faculty of Veterinary Medicine, Kagoshima University, Korimoto 1-21-24, Kagoshima 890-0065, Japan
| | - Akane Yoshida
- Department of Molecular and Cell Biology and Biochemistry, Basic Veterinary Science, Faculty of Veterinary Medicine, Kagoshima University, Korimoto 1-21-24, Kagoshima 890-0065, Japan
| | - Kanna Tomioku
- Department of Molecular and Cell Biology and Biochemistry, Basic Veterinary Science, Faculty of Veterinary Medicine, Kagoshima University, Korimoto 1-21-24, Kagoshima 890-0065, Japan
| | - Kenji Tanabe
- Medical Research Institute, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan
| | - Akikazu Fujita
- Department of Molecular and Cell Biology and Biochemistry, Basic Veterinary Science, Faculty of Veterinary Medicine, Kagoshima University, Korimoto 1-21-24, Kagoshima 890-0065, Japan.
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13
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Xu Y, Du X, Turner N, Brown AJ, Yang H. Enhanced acyl-CoA:cholesterol acyltransferase activity increases cholesterol levels on the lipid droplet surface and impairs adipocyte function. J Biol Chem 2019; 294:19306-19321. [PMID: 31727739 DOI: 10.1074/jbc.ra119.011160] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 11/11/2019] [Indexed: 01/21/2023] Open
Abstract
Cholesterol plays essential structural and signaling roles in mammalian cells, but too much cholesterol can cause cytotoxicity. Acyl-CoA:cholesterol acyltransferases 1 and 2 (ACAT1/2) convert cholesterol into its storage form, cholesteryl esters, regulating a key step in cellular cholesterol homeostasis. Adipose tissue can store >50% of whole-body cholesterol. Interestingly, however, almost no ACAT activity is present in adipose tissue, and most adipose cholesterol is stored in its free form. We therefore hypothesized that increased cholesterol esterification may have detrimental effects on adipose tissue function. Here, using several approaches, including protein overexpression, quantitative RT-PCR, immunofluorescence, and various biochemical assays, we found that ACAT1 expression is significantly increased in the adipose tissue of the ob/ob mice. We further demonstrated that ACAT1/2 overexpression partially inhibited the differentiation of 3T3-L1 preadipocytes. In mature adipocytes, increased ACAT activity reduced the size of lipid droplets (LDs) and inhibited lipolysis and insulin signaling. Paradoxically, the amount of free cholesterol increased on the surface of LDs in ACAT1/2-overexpressing adipocytes, accompanied by increased LD localization of caveolin-1. Moreover, cholesterol depletion in adipocytes by treating the cells with cholesterol-deficient media or β-cyclodextrins induced changes in cholesterol distribution that were similar to those caused by ACAT1/2 overexpression. Our results suggest that ACAT1/2 overexpression increases the level of free cholesterol on the LD surface, thereby impeding adipocyte function. These findings provide detailed insights into the role of free cholesterol in LD and adipocyte function and suggest that ACAT inhibitors have potential utility for managing disorders associated with extreme obesity.
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Affiliation(s)
- Yanqing Xu
- School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Ximing Du
- School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Nigel Turner
- School of Medical Sciences, the University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Andrew J Brown
- School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Hongyuan Yang
- School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney, New South Wales 2052, Australia
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14
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Yu J, Zhang L, Li Y, Zhu X, Xu S, Zhou XM, Wang H, Zhang H, Liang B, Liu P. The Adrenal Lipid Droplet is a New Site for Steroid Hormone Metabolism. Proteomics 2019; 18:e1800136. [PMID: 30358111 DOI: 10.1002/pmic.201800136] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Revised: 10/08/2018] [Indexed: 01/25/2023]
Abstract
Steroid hormones play essential roles for living organisms. It has been long and well established that the endoplasmic reticulum (ER) and mitochondria are essential sites for steroid hormone biosynthesis because several steroidogenic enzymes are located in these organelles. The adrenal gland lipid droplet (LD) proteomes from human, macaque monkey, and rodent are analyzed, revealing that steroidogenic enzymes are also present in abundance on LDs. The enzymes found include 3β-hydroxysteroid dehydrogenase (HSD3B) and estradiol 17β-dehydrogenase 11 (HSD17B11). Analyses by Western blot and subcellular localization consistently demonstrate that HSD3B2 is localized on LDs. Furthermore, in vitro experiments confirm that the isolated LDs from HeLa cell stably expressing HSD3B2 or from rat adrenal glands have the capacity to convert pregnenolone to progesterone. Collectively, these data suggest that LDs may be important sites of steroid hormone metabolism. These findings may bring novel insights into the biosynthesis and metabolism of steroid hormones and the development of treatments for adrenal disorders.
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Affiliation(s)
- Jinhai Yu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Institute of Biophysics, Beijing, 100101, P. R. China
| | - Linqiang Zhang
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan province, Chinese Academy of Sciences, Center for Excellence in Animal Evolution and Genetics, Kunming Institute of Zoology, Kunming, 650223, P. R. China
| | - Yunhai Li
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan province, Chinese Academy of Sciences, Center for Excellence in Animal Evolution and Genetics, Kunming Institute of Zoology, Kunming, 650223, P. R. China
| | - Xiaotong Zhu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Institute of Biophysics, Beijing, 100101, P. R. China.,Academy of Sciences, University of Chinese, Beijing, 100049, P. R. China
| | - Shimeng Xu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Institute of Biophysics, Beijing, 100101, P. R. China.,Academy of Sciences, University of Chinese, Beijing, 100049, P. R. China
| | - Xiao-Ming Zhou
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Institute of Biophysics, Beijing, 100101, P. R. China
| | - Haizhen Wang
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan province, Chinese Academy of Sciences, Center for Excellence in Animal Evolution and Genetics, Kunming Institute of Zoology, Kunming, 650223, P. R. China
| | - Hongchao Zhang
- General Hospital of Air Force, Beijing, 100142, P. R. China
| | - Bin Liang
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan province, Chinese Academy of Sciences, Center for Excellence in Animal Evolution and Genetics, Kunming Institute of Zoology, Kunming, 650223, P. R. China
| | - Pingsheng Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Institute of Biophysics, Beijing, 100101, P. R. China.,Academy of Sciences, University of Chinese, Beijing, 100049, P. R. China
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15
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Sun S, Adyshev D, Dudek S, Paul A, McColloch A, Cho M. Cholesterol-dependent Modulation of Stem Cell Biomechanics: Application to Adipogenesis. J Biomech Eng 2019; 141:2729412. [PMID: 30901381 DOI: 10.1115/1.4043253] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Indexed: 11/08/2022]
Abstract
Cell mechanics has been shown to regulate stem cell differentiation. We have previously reported that altered cell stiffness of mesenchymal stem cells can delay or facilitate biochemically directed differentiation. One of the factors that can affect the cell stiffness is cholesterol. However, the effect of cholesterol on differentiation of human mesenchymal stem cells (hMSCs) remains elusive. In this paper, we demonstrate that cholesterol is involved in the modulation of the cell stiffness and subsequent adipogenic differentiation. Rapid cytoskeletal actin reorganization was evident and correlated with the cell's Young's modulus measured using atomic force microscopy (AFM). In addition, the level of membrane-bound cholesterol was found to increase during adipogenic differentiation and inversely varied with the cell stiffness. Furthermore, cholesterol played a key role in the regulation of the cell morphology and biomechanics, suggesting its crucial involvement in mechanotransduction. To better understand the underlying mechanisms, we investigated the effect of cholesterol on the membrane-cytoskeleton linker proteins (ezrin and moesin). Cholesterol depletion was found to up-regulate the ezrin expression which promoted cell spreading, increased Young's modulus, and hindered adipogenesis. In contrast, cholesterol enrichment increased the moesin expression, decreased Young's modulus, and induced cell rounding and facilitated adipogenesis. Taken together, cholesterol appears to regulate the stem cell mechanics and adipogenesis through the membrane-associated linker proteins.
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Affiliation(s)
- Shan Sun
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607
| | - Djanybek Adyshev
- Department of Medicine, University of Illinois at Chicago, Chicago, IL 60607
| | - Steve Dudek
- Department of Medicine, University of Illinois at Chicago, Chicago, IL 60607
| | - Amit Paul
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607
| | - Andrew McColloch
- Department of Bioengineering, University of Texas at Arlington, Arlington, TX 76019
| | - Michael Cho
- Department of Bioengineering, University of Texas at Arlington, Arlington, TX 76019
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16
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Bordicchia M, Spannella F, Ferretti G, Bacchetti T, Vignini A, Di Pentima C, Mazzanti L, Sarzani R. PCSK9 is Expressed in Human Visceral Adipose Tissue and Regulated by Insulin and Cardiac Natriuretic Peptides. Int J Mol Sci 2019; 20:ijms20020245. [PMID: 30634533 PMCID: PMC6358804 DOI: 10.3390/ijms20020245] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 12/05/2018] [Accepted: 01/04/2019] [Indexed: 01/14/2023] Open
Abstract
Proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to and degrades the low-density lipoprotein receptor (LDLR), contributing to hypercholesterolemia. Adipose tissue plays a role in lipoprotein metabolism, but there are almost no data about PCSK9 and LDLR regulation in human adipocytes. We studied PCSK9 and LDLR regulation by insulin, atrial natriuretic peptide (ANP, a potent lipolytic agonist that antagonizes insulin), and LDL in visceral adipose tissue (VAT) and in human cultured adipocytes. PCSK9 was expressed in VAT and its expression was positively correlated with body mass index (BMI). Both intracellular mature and secreted PCSK9 were abundant in cultured human adipocytes. Insulin induced PCSK9, LDLR, and sterol-regulatory element-binding protein-1c (SREBP-1c) and -2 expression (SREBP-2). ANP reduced insulin-induced PCSK9, especially in the context of a medium simulating hyperglycemia. Human LDL induced both mature and secreted PCSK9 and reduced LDLR. ANP indirectly blocked the LDLR degradation, reducing the positive effect of LDL on PCSK9. In conclusion, PCSK9 is expressed in human adipocytes. When the expression of PCSK9 is induced, LDLR is reduced through the PCSK9-mediated degradation. On the contrary, when the induction of PCSK9 by insulin and LDL is partially blocked by ANP, the LDLR degradation is reduced. This suggests that NPs could be able to control LDLR levels, preventing PCSK9 overexpression.
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Affiliation(s)
- Marica Bordicchia
- Internal Medicine and Geriatrics, Department of Clinical and Molecular Sciences, University "Politecnica delle Marche", 60126 Ancona, Italy.
| | - Francesco Spannella
- Internal Medicine and Geriatrics, Department of Clinical and Molecular Sciences, University "Politecnica delle Marche", 60126 Ancona, Italy.
- Internal Medicine and Geriatrics, "Hypertension Excellence Centre" of the European Society of Hypertension, IRCCS-INRCA, 60127 Ancona, Italy.
| | - Gianna Ferretti
- Department of Clinical Sciences, Section of Biochemistry, Biology and Physics, School of Nutrition, University "Politecnica delle Marche", 60126 Ancona, Italy.
| | - Tiziana Bacchetti
- Department of Clinical Sciences, Section of Biochemistry, Biology and Physics, School of Nutrition, University "Politecnica delle Marche", 60126 Ancona, Italy.
| | - Arianna Vignini
- Department of Clinical Sciences, Section of Biochemistry, Biology and Physics, School of Nutrition, University "Politecnica delle Marche", 60126 Ancona, Italy.
| | - Chiara Di Pentima
- Internal Medicine and Geriatrics, Department of Clinical and Molecular Sciences, University "Politecnica delle Marche", 60126 Ancona, Italy.
- Internal Medicine and Geriatrics, "Hypertension Excellence Centre" of the European Society of Hypertension, IRCCS-INRCA, 60127 Ancona, Italy.
| | - Laura Mazzanti
- Department of Clinical Sciences, Section of Biochemistry, Biology and Physics, School of Nutrition, University "Politecnica delle Marche", 60126 Ancona, Italy.
| | - Riccardo Sarzani
- Internal Medicine and Geriatrics, Department of Clinical and Molecular Sciences, University "Politecnica delle Marche", 60126 Ancona, Italy.
- Internal Medicine and Geriatrics, "Hypertension Excellence Centre" of the European Society of Hypertension, IRCCS-INRCA, 60127 Ancona, Italy.
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17
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Abstract
Adipose tissue is necessary to harbor energy. To handle excess energy, adipose tissue expands by increasing adipocyte size (hypertrophy) and number (hyperplasia). Here, we have summarized the different experimental techniques used to study adipocyte cell size and describe adipocyte size in relation to insulin resistance, type 2 diabetes, and diet interventions. Hypertrophic adipocytes have an impaired cellular function, and inherent mechanisms restrict their expansion to protect against cell breakage and subsequent inflammation. Reduction of large fat cells by diet restriction, physical activity, or bariatric surgery therefore is necessary to improve cellular function and health. Small fat cells may also be dysfunctional and unable to expand. The distribution and function of the entire cell size range of fat cells, from small to very large fat cells, are an important but understudied aspect of adipose tissue biology. To prevent dysmetabolism, therapeutic strategies to expand small fat cells, recruit new fat cells, and reduce large fat cells are needed.
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Affiliation(s)
- Karin G. Stenkula
- Glucose Transport and Protein Trafficking, Biomedical Center, Lund University, Lund, Sweden
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18
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Tomioku KN, Shigekuni M, Hayashi H, Yoshida A, Futagami T, Tamaki H, Tanabe K, Fujita A. Nanoscale domain formation of phosphatidylinositol 4-phosphate in the plasma and vacuolar membranes of living yeast cells. Eur J Cell Biol 2018; 97:269-78. [PMID: 29609807 DOI: 10.1016/j.ejcb.2018.03.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 02/27/2018] [Accepted: 03/20/2018] [Indexed: 12/31/2022] Open
Abstract
In budding yeast Saccharomyces cerevisiae, PtdIns(4)P serves as an essential signalling molecule in the Golgi complex, endosomal system, and plasma membrane, where it is involved in the control of multiple cellular functions via direct interactions with PtdIns(4)P-binding proteins. To analyse the distribution of PtdIns(4)P in yeast cells at a nanoscale level, we employed an electron microscopy technique that specifically labels PtdIns(4)P on the freeze-fracture replica of the yeast membrane. This method minimizes the possibility of artificial perturbation, because molecules in the membrane are physically immobilised in situ. We observed that PtdIns(4)P is localised on the cytoplasmic leaflet, but not the exoplasmic leaflet, of the plasma membrane, Golgi body, vacuole, and vesicular structure membranes. PtdIns(4)P labelling was not observed in the membrane of the endoplasmic reticulum, and in the outer and inner membranes of the nuclear envelope or mitochondria. PtdIns(4)P forms clusters of <100 nm in diameter in the plasma membrane and vacuolar membrane according to point pattern analysis of immunogold labelling. There are three kinds of compartments in the cytoplasmic leaflet of the plasma membrane. In the present study, we showed that PtdIns(4)P is specifically localised in the flat undifferentiated plasma membrane compartment. In the vacuolar membrane, PtdIns(4)P was concentrated in intramembrane particle (IMP)-deficient raft-like domains, which are tightly bound to lipid droplets, but not surrounding IMP-rich non-raft domains in geometrical IMP-distributed patterns in the stationary phase. This is the first report showing microdomain formations of PtdIns(4)P in the plasma membrane and vacuolar membrane of budding yeast cells at a nanoscale level, which will illuminate the functionality of PtdIns(4)P in each membrane.
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19
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Zhu Y, Chen CY, Li J, Cheng JX, Jang M, Kim KH. In vitro exploration of ACAT contributions to lipid droplet formation during adipogenesis. J Lipid Res 2018; 59:820-829. [PMID: 29549095 DOI: 10.1194/jlr.m081745] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 03/12/2018] [Indexed: 12/11/2022] Open
Abstract
As adipose tissue is the major cholesterol storage organ and most of the intracellular cholesterol is distributed to lipid droplets (LDs), cholesterol homeostasis may have a role in the regulation of adipocyte size and function. ACATs catalyze the formation of cholesteryl ester (CE) from free cholesterol to modulate the cholesterol balance. Despite the well-documented role of ACATs in hypercholesterolemia, their role in LD development during adipogenesis remains elusive. Here, we identify ACATs as regulators of de novo lipogenesis and LD formation in murine 3T3-L1 adipocytes. Pharmacological inhibition of ACAT activity suppressed intracellular cholesterol and CE levels, and reduced expression of genes involved in cholesterol uptake and efflux. ACAT inhibition resulted in decreased de novo lipogenesis, as demonstrated by reduced maturation of SREBP1 and SREBP1-downstream lipogenic gene expression. Consistent with this observation, knockdown of either ACAT isoform reduced total adipocyte lipid content by approximately 40%. These results demonstrate that ACATs are required for storage ability of lipids and cholesterol in adipocytes.
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Affiliation(s)
- Yuyan Zhu
- Department of Food Science Purdue University, West Lafayette, IN 47907
| | - Chih-Yu Chen
- Department of Food Science Purdue University, West Lafayette, IN 47907
| | - Junjie Li
- Department of Biomedical Engineering, Department of Electrical and Computer Engineering, Boston University, Boston, MA 02215
| | - Ji-Xin Cheng
- Department of Biomedical Engineering, Department of Electrical and Computer Engineering, Boston University, Boston, MA 02215
| | - Miran Jang
- Department of Food Science Purdue University, West Lafayette, IN 47907
| | - Kee-Hong Kim
- Department of Food Science Purdue University, West Lafayette, IN 47907 .,Purdue Center for Cancer Research, Purdue University, West Lafayette, IN 47907
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20
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Haczeyni F, Bell-Anderson KS, Farrell GC. Causes and mechanisms of adipocyte enlargement and adipose expansion. Obes Rev 2018; 19:406-420. [PMID: 29243339 DOI: 10.1111/obr.12646] [Citation(s) in RCA: 120] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 09/28/2017] [Accepted: 10/23/2017] [Indexed: 02/06/2023]
Abstract
Adipose tissue plays a significant role in whole body energy homeostasis. Obesity-associated diabetes, fatty liver and metabolic syndrome are closely linked to adipose stress and dysfunction. Genetic predisposition, overeating and physical inactivity influence the expansion of adipose tissues. Under conditions of constant energy surplus, adipocytes become hypertrophic and adipose tissues undergo hyperplasia so as to increase their lipid storage capacity, thereby keeping circulating blood glucose and fatty acids below toxic levels. Nonetheless, adipocytes have a saturation point where they lose capacity to store more lipids. At this stage, when adipocytes are fully lipid-engorged, they express stress signals. Adipose depots (particularly visceral compartments) from obese individuals with a severe metabolic phenotype are characterized by the high proportion of hypertrophic adipocytes. This review focuses on the mechanisms of adipocyte enlargement in relation to adipose fatty acid and cholesterol metabolism, and considers how this may be related to adipose dysfunction.
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Affiliation(s)
- F Haczeyni
- Liver Research Group, Australian National University Medical School at The Canberra Hospital, Canberra, ACT, Australia
| | - K S Bell-Anderson
- Charles Perkins Centre, School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
| | - G C Farrell
- Liver Research Group, Australian National University Medical School at The Canberra Hospital, Canberra, ACT, Australia
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21
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Chien CY, Hung YJ, Shieh YS, Hsieh CH, Lu CH, Lin FH, Su SC, Lee CH. A novel potential biomarker for metabolic syndrome in Chinese adults: Circulating protein disulfide isomerase family A, member 4. PLoS One 2017. [PMID: 28650993 PMCID: PMC5484513 DOI: 10.1371/journal.pone.0179963] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND/OBJECTIVES Protein disulfide isomerase (PDI) family members are specific endoplasmic reticulum proteins that are involved in the pathogenesis of numerous diseases including neurodegenerative diseases, cancer and obesity. However, the metabolic effects of PDIA4 remain unclear in humans. The aims of this study were to investigate the associations of serum PDIA4 with the metabolic syndrome (MetS) and its components in Chinese adults. SUBJECTS/METHODS A total of 669 adults (399 men and 270 women) were recruited. Serum PDIA4 concentrations and biochemical variables were recorded. Insulin sensitivity and β-cell function were examined by homeostasis model assessment. MetS was defined based on the modified National Cholesterol Education Program Adult Treatment Panel III criteria for Asia Pacific. RESULTS The participants with MetS had significantly higher serum PDIA4 levels than those without MetS (P<0.001). After adjustments, the individuals with the highest PDIA4 tertile were associated with a higher risk of MetS than those with the lowest tertile (OR = 4.83, 95% CI: 2.71-8.60). The concentration of PDIA4 showed a stepwise increase with the components of MetS (P<0.001 for trend). The individuals with the highest PDIA4 tertile were significantly associated with waist circumference (OR = 2.41, 95% CI 1.34-4.32), blood pressure (OR = 2.71, 95% CI 1.57-4.67), fasting glucose concentration (OR = 3.17, 95% CI 1.80-5.57), and serum triglycerides (OR = 4.12, 95% CI 2.30-7.37) than those with the lowest tertile. At cutoff point of 15.24 ng/ml, the diagnostic sensitivity and specificity of PDIA4 for the metabolic syndrome were 67 and 72%, respectively, in male patients and 60 and 78%, respectively, in female patients. Finally, the result showed that PDIA4 had a significantly higher area under the curve compared with blood pressure to detect MetS using receiver operating characteristic analysis. CONCLUSIONS Serum PDIA4 concentrations are closely associated to MetS and its components in Chinese adults.
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Affiliation(s)
- Chu-Yen Chien
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, R.O.C
| | - Yi-Jen Hung
- Division of Endocrinology and Metabolism, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, R.O.C
| | - Yi-Shing Shieh
- School of Dentistry, National Defense Medical Center, Taipei, Taiwan, R.O.C
- Department of Oral Diagnosis and Pathology, Tri-Service General Hospital, Taipei, Taiwan, R.O.C
| | - Chang-Hsun Hsieh
- Division of Endocrinology and Metabolism, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, R.O.C
| | - Chieh-Hua Lu
- Division of Endocrinology and Metabolism, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, R.O.C
| | - Fu-Huang Lin
- School of Public Health, National Defense Medical Center, Taipei, Taiwan, R.O.C
| | - Sheng-Chiang Su
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, R.O.C
- Division of Endocrinology and Metabolism, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, R.O.C
| | - Chien-Hsing Lee
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, R.O.C
- Division of Endocrinology and Metabolism, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, R.O.C
- * E-mail:
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22
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Abstract
Mitochondria are considered cholesterol-poor organelles, and obtain their cholesterol load by the action of specialized proteins involved in its delivery from extramitochondrial sources and trafficking within mitochondrial membranes. Although mitochondrial cholesterol fulfills vital physiological functions, such as the synthesis of bile acids in the liver or the formation of steroid hormones in specialized tissues, recent evidence indicates that the accumulation of cholesterol in mitochondria may be a key event in prevalent human diseases, in particular in the development of steatohepatitis (SH) and its progression to hepatocellular carcinoma (HCC). Mitochondrial cholesterol accumulation promotes the transition from simple steatosis to SH due to the sensitization to oxidative stress and cell death. However, mitochondrial cholesterol loading in HCC determines apoptosis resistance and insensitivity to chemotherapy. These opposing functions of mitochondrial cholesterol in SH and HCC define its paradoxical role in cell death as a pro- and anti-apoptotic factor. Further understanding of this conundrum may be useful to modulate the progression from SH to HCC by targeting mitochondrial cholesterol trafficking.
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Affiliation(s)
- Carmen García-Ruiz
- Department of Cell Death and Proliferation, Instituto Investigaciones Biomedicas de Barcelona, CSIC, C/Rosello 161, 08036, Barcelona, Spain
- Liver Unit, Hospital Clinic, IDIBAPS, Barcelona, Spain
- Centro de Investigación Biomédica en Red (CIBERehd), Barcelona, Spain
- Keck School of Medicine, USC, University of Southern California Research Center for Alcohol Liver and Pancreatic Diseases and Cirrhosis, Los Angeles, CA, USA
| | - Vicente Ribas
- Department of Cell Death and Proliferation, Instituto Investigaciones Biomedicas de Barcelona, CSIC, C/Rosello 161, 08036, Barcelona, Spain
- Liver Unit, Hospital Clinic, IDIBAPS, Barcelona, Spain
- Centro de Investigación Biomédica en Red (CIBERehd), Barcelona, Spain
| | - Anna Baulies
- Department of Cell Death and Proliferation, Instituto Investigaciones Biomedicas de Barcelona, CSIC, C/Rosello 161, 08036, Barcelona, Spain
- Liver Unit, Hospital Clinic, IDIBAPS, Barcelona, Spain
- Centro de Investigación Biomédica en Red (CIBERehd), Barcelona, Spain
| | - Jose C Fernández-Checa
- Department of Cell Death and Proliferation, Instituto Investigaciones Biomedicas de Barcelona, CSIC, C/Rosello 161, 08036, Barcelona, Spain.
- Liver Unit, Hospital Clinic, IDIBAPS, Barcelona, Spain.
- Centro de Investigación Biomédica en Red (CIBERehd), Barcelona, Spain.
- Keck School of Medicine, USC, University of Southern California Research Center for Alcohol Liver and Pancreatic Diseases and Cirrhosis, Los Angeles, CA, USA.
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23
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Abstract
Cellular cholesterol homeostasis relies on precise control of the sterol content of organelle membranes. Obtaining insight into cholesterol trafficking pathways and kinetics by live-cell imaging relies on two conditions. First, one needs to develop suitable analogs that resemble cholesterol as closely as possible with respect to their biophysical and biochemical properties. Second, the cholesterol analogs should have good fluorescence properties. This interferes, however, often with the first requirement, such that the imaging instrumentation must be optimized to collect photons from suboptimal fluorophores, but good cholesterol mimics, such as the intrinsically fluorescent sterols, cholestatrienol (CTL) or dehydroergosterol (DHE). CTL differs from cholesterol only in having two additional double bonds in the ring system, which is why it is slightly fluorescent in the ultraviolet (UV). In the first part of this protocol, we describe how to synthesize and image CTL in living cells relative to caveolin, a structural component of caveolae. In the second part, we explain in detail how to perform time-lapse experiments of commercially available BODIPY-tagged cholesterol (TopFluor-cholesterol®; TF-Chol) in comparison to DHE. Finally, using two-photon time-lapse imaging data of TF-Chol, we demonstrate how to use our imaging toolbox SpatTrack for tracking sterol rich vesicles in living cells over time.
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Affiliation(s)
- Maciej Modzel
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, Odense M, 5230, Denmark
| | - Frederik W Lund
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, Odense M, 5230, Denmark.,Department of Biochemistry, Weill Medical College of Cornell University, New York, NY, 10065, USA
| | - Daniel Wüstner
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, Odense M, 5230, Denmark.
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Makino A, Hullin-Matsuda F, Murate M, Abe M, Tomishige N, Fukuda M, Yamashita S, Fujimoto T, Vidal H, Lagarde M, Delton I, Kobayashi T. Acute accumulation of free cholesterol induces the degradation of perilipin 2 and Rab18-dependent fusion of ER and lipid droplets in cultured human hepatocytes. Mol Biol Cell 2016; 27:3293-3304. [PMID: 27582390 PMCID: PMC5170862 DOI: 10.1091/mbc.e15-10-0730] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 08/26/2016] [Indexed: 01/19/2023] Open
Abstract
Free cholesterol accumulation in the liver is relevant to the pathogenesis of nonalcoholic steatohepatitis. Acute free cholesterol accumulation induced the fusion of LDs, followed by degradation of the coat protein of LDs, perilipin 2, and association of apolipoprotein 100 to LDs in Rab18-dependent manner. Dysregulated hepatic cholesterol homeostasis with free cholesterol accumulation in the liver is relevant to the pathogenesis of nonalcoholic steatohepatitis, contributing to the chronicity of liver toxicity. Here we examined the effect of free cholesterol accumulation on the morphology and biochemical properties of lipid droplets (LDs) in cultured hepatocytes. Acute free cholesterol accumulation induced the fusion of LDs, followed by degradation of the coat protein of LDs, perilipin 2 (PLIN2; also called adipophilin or adipose differentiation–related protein), and association of apolipoprotein B 100 (ApoB 100) to LDs. The degradation of PLIN2 was inhibited by inhibitors of ubiquitination, autophagy, and protein synthesis. The results indicate that association of ApoB 100 with LDs is dependent on the activity of low–molecular weight GTP-binding protein Rab18 and highlight the role of LDs as targets of free cholesterol toxicity in hepatocytes.
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Affiliation(s)
- Asami Makino
- INSERM-RIKEN Lipidomics Unit, Université Lyon 1, 69621 Villeurbanne, France.,INSERM U1060, INSA-Lyon, Université Lyon 1, 69621 Villeurbanne, France.,Lipid Biology Laboratory, RIKEN, Wako 351-0198, Japan
| | - Françoise Hullin-Matsuda
- INSERM-RIKEN Lipidomics Unit, Université Lyon 1, 69621 Villeurbanne, France.,INSERM U1060, INSA-Lyon, Université Lyon 1, 69621 Villeurbanne, France.,Lipid Biology Laboratory, RIKEN, Wako 351-0198, Japan
| | | | - Mitsuhiro Abe
- Lipid Biology Laboratory, RIKEN, Wako 351-0198, Japan
| | | | - Mitsunori Fukuda
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Shizuya Yamashita
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan
| | - Toyoshi Fujimoto
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Hubert Vidal
- INSERM-RIKEN Lipidomics Unit, Université Lyon 1, 69621 Villeurbanne, France.,INSERM U1060, INSA-Lyon, Université Lyon 1, 69621 Villeurbanne, France
| | - Michel Lagarde
- INSERM-RIKEN Lipidomics Unit, Université Lyon 1, 69621 Villeurbanne, France.,INSERM U1060, INSA-Lyon, Université Lyon 1, 69621 Villeurbanne, France
| | - Isabelle Delton
- INSERM-RIKEN Lipidomics Unit, Université Lyon 1, 69621 Villeurbanne, France.,INSERM U1060, INSA-Lyon, Université Lyon 1, 69621 Villeurbanne, France
| | - Toshihide Kobayashi
- INSERM-RIKEN Lipidomics Unit, Université Lyon 1, 69621 Villeurbanne, France .,INSERM U1060, INSA-Lyon, Université Lyon 1, 69621 Villeurbanne, France.,Lipid Biology Laboratory, RIKEN, Wako 351-0198, Japan.,UMR 7213 CNRS, University of Strasbourg, 67401 Illkirch, France
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25
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Honvo-Houéto E, Henry C, Chat S, Layani S, Truchet S. The endoplasmic reticulum and casein-containing vesicles contribute to milk fat globule membrane. Mol Biol Cell 2016; 27:2946-64. [PMID: 27535430 PMCID: PMC5042581 DOI: 10.1091/mbc.e16-06-0364] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 08/03/2016] [Indexed: 12/28/2022] Open
Abstract
The endoplasmic reticulum and the secretory vesicles contribute to the formation of the milk fat globule membrane. In addition, lipid raft microdomains may play a role in the transport and/or secretion of the milk fat globule, and SNARE proteins appear to coordinate membrane exchanges during milk product secretion. During lactation, mammary epithelial cells secrete huge amounts of milk from their apical side. The current view is that caseins are secreted by exocytosis, whereas milk fat globules are released by budding, enwrapped by the plasma membrane. Owing to the number and large size of milk fat globules, the membrane surface needed for their release might exceed that of the apical plasma membrane. A large-scale proteomics analysis of both cytoplasmic lipid droplets and secreted milk fat globule membranes was used to decipher the cellular origins of the milk fat globule membrane. Surprisingly, differential analysis of protein profiles of these two organelles strongly suggest that, in addition to the plasma membrane, the endoplasmic reticulum and the secretory vesicles contribute to the milk fat globule membrane. Analysis of membrane-associated and raft microdomain proteins reinforces this possibility and also points to a role for lipid rafts in milk product secretion. Our results provide evidence for a significant contribution of the endoplasmic reticulum to the milk fat globule membrane and a role for SNAREs in membrane dynamics during milk secretion. These novel aspects point to a more complex model for milk secretion than currently envisioned.
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Affiliation(s)
- Edith Honvo-Houéto
- INRA, UR1196 Génomique et Physiologie de la Lactation, F-78352 Jouy-en-Josas Cedex, France
| | - Céline Henry
- INRA, UMR1319, MICALIS, PAPPSO, F-78352 Jouy-en-Josas Cedex, France
| | - Sophie Chat
- INRA, UR1196 Génomique et Physiologie de la Lactation, F-78352 Jouy-en-Josas Cedex, France
| | - Sarah Layani
- INRA, UR1196 Génomique et Physiologie de la Lactation, F-78352 Jouy-en-Josas Cedex, France
| | - Sandrine Truchet
- INRA, UR1196 Génomique et Physiologie de la Lactation, F-78352 Jouy-en-Josas Cedex, France
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26
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Kessler SM, Laggai S, Van Wonterg E, Gemperlein K, Müller R, Haybaeck J, Vandenbroucke RE, Ogris M, Libert C, Kiemer AK. Transient Hepatic Overexpression of Insulin-Like Growth Factor 2 Induces Free Cholesterol and Lipid Droplet Formation. Front Physiol 2016; 7:147. [PMID: 27199763 PMCID: PMC4843762 DOI: 10.3389/fphys.2016.00147] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 04/04/2016] [Indexed: 12/12/2022] Open
Abstract
Although insulin-like growth factor 2 (IGF2) has been reported to be overexpressed in steatosis and steatohepatitis, a causal role of IGF2 in steatosis development remains elusive. Aim of our study was to decipher the role of IGF2 in steatosis development. Hydrodynamic gene delivery of an Igf2 plasmid used for transient Igf2 overexpression employing codon-optimized plasmid DNA resulted in a strong induction of hepatic Igf2 expression. The exogenously delivered Igf2 had no influence on endogenous Igf2 expression. The downstream kinase AKT was activated in Igf2 animals. Decreased ALT levels mirrored the cytoprotective effect of IGF2. Serum cholesterol was increased and sulfo-phospho-vanillin colorimetric assay confirmed lipid accumulation in Igf2-livers while no signs of inflammation were observed. Interestingly, hepatic cholesterol and phospholipids, determined by thin layer chromatography, and free cholesterol by filipin staining, were specifically increased. Lipid droplet (LD) size was not changed, but their number was significantly elevated. Furthermore, free cholesterol, which can be stored in LDs and has been reported to be critical for steatosis progression, was elevated in Igf2 overexpressing mice. Accordingly, Hmgcr/HmgCoAR was upregulated. To have a closer look at de novo lipid synthesis we investigated expression of the lipogenic transcription factor SREBF1 and its target genes. SREBF1 was induced and also SREBF1 target genes were slightly upregulated. Interestingly, the expression of Cpt1a, which is responsible for mitochondrial fatty acid oxidation, was induced. Hepatic IGF2 expression induces a fatty liver, characterized by increased cholesterol and phospholipids leading to accumulation of LDs. We therefore suggest a causal role for IGF2 in hepatic lipid accumulation.
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Affiliation(s)
- Sonja M Kessler
- Department of Pharmacy, Pharmaceutical Biology, Saarland University Saarbrücken, Germany
| | - Stephan Laggai
- Department of Pharmacy, Pharmaceutical Biology, Saarland University Saarbrücken, Germany
| | - Elien Van Wonterg
- Inflammation Research Center, VIBGhent, Belgium; Department of Biomedical Molecular Biology, Ghent UniversityGhent, Belgium
| | - Katja Gemperlein
- Department of Microbial Natural Products, Helmholtz Institute for Pharmaceutical Research Saarland, Helmholtz Centre for Infection Research and Pharmaceutical Biotechnology, Saarland University Saarbrücken, Germany
| | - Rolf Müller
- Department of Microbial Natural Products, Helmholtz Institute for Pharmaceutical Research Saarland, Helmholtz Centre for Infection Research and Pharmaceutical Biotechnology, Saarland University Saarbrücken, Germany
| | | | - Roosmarijn E Vandenbroucke
- Inflammation Research Center, VIBGhent, Belgium; Department of Biomedical Molecular Biology, Ghent UniversityGhent, Belgium
| | - Manfred Ogris
- Department of Pharmaceutical Chemistry, University of Vienna Vienna, Austria
| | - Claude Libert
- Inflammation Research Center, VIBGhent, Belgium; Department of Biomedical Molecular Biology, Ghent UniversityGhent, Belgium
| | - Alexandra K Kiemer
- Department of Pharmacy, Pharmaceutical Biology, Saarland University Saarbrücken, Germany
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27
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Padilla-Benavides T, Velez-delValle C, Marsch-Moreno M, Castro-Muñozledo F, Kuri-Harcuch W. Lipogenic Enzymes Complexes and Cytoplasmic Lipid Droplet Formation During Adipogenesis. J Cell Biochem 2016; 117:2315-26. [DOI: 10.1002/jcb.25529] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 02/26/2016] [Indexed: 11/06/2022]
Affiliation(s)
- Teresita Padilla-Benavides
- Department of Cell Biology; Center for Research and Advanced Studies-IPN (CINVESTAV-IPN); México City 07360 Mexico
| | - Cristina Velez-delValle
- Department of Cell Biology; Center for Research and Advanced Studies-IPN (CINVESTAV-IPN); México City 07360 Mexico
| | - Meytha Marsch-Moreno
- Department of Cell Biology; Center for Research and Advanced Studies-IPN (CINVESTAV-IPN); México City 07360 Mexico
| | - Federico Castro-Muñozledo
- Department of Cell Biology; Center for Research and Advanced Studies-IPN (CINVESTAV-IPN); México City 07360 Mexico
| | - Walid Kuri-Harcuch
- Department of Cell Biology; Center for Research and Advanced Studies-IPN (CINVESTAV-IPN); México City 07360 Mexico
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28
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Wang M, Gao M, Liao J, Qi Y, Du X, Wang Y, Li L, Liu G, Yang H. Adipose tissue deficiency results in severe hyperlipidemia and atherosclerosis in the low-density lipoprotein receptor knockout mice. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:410-8. [PMID: 26921684 DOI: 10.1016/j.bbalip.2016.02.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 02/11/2016] [Accepted: 02/23/2016] [Indexed: 12/17/2022]
Abstract
Adipose tissue can store over 50% of whole-body cholesterol; however, the physiological role of adipose tissue in cholesterol metabolism and atherogenesis has not been directly assessed. Here, we examined lipoprotein metabolism and atherogenesis in a unique mouse model of severe lipodystrophy: the Seipin(-/-) mice, and also in mice deficient in both low-density lipoprotein receptor (Ldlr) and Seipin: the Ldlr(-/-)Seipin(-/-) mice. Plasma cholesterol was moderately increased in the Seipin(-/-) mice when fed an atherogenic diet. Strikingly, plasma cholesterol reached ~6000 mg/dl in the Seipin(-/-)Ldlr(-/-) mice on an atherogenic diet, as compared to ~1000 mg/dl in the Ldlr(-/-) mice on the same diet. The Seipin(-/-)Ldlr(-/-) mice also developed spontaneous atherosclerosis on chow diet and severe atherosclerosis on an atherogenic diet. Rosiglitazone treatment significantly reduced the hypercholesterolemia of the Seipin(-/-)Ldlr(-/-) mice, and also alleviated the severity of atherosclerosis. Our results provide direct evidence, for the first time, that the adipose tissue plays a critical role in the clearance of plasma cholesterol. Our results also reveal a previously unappreciated strong link between adipose tissue and LDLR in plasma cholesterol metabolism.
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Abstract
As the major storage site for triglycerides and free cholesterol, adipose tissue plays a central role in energy metabolism. ApoA-I is the main constituent of HDL and plays an important role in removal of excess cholesterol from peripheral tissues. Recently, multiple studies have shown beneficial effects of apoA-I on adipose metabolism and function. ApoA-I was reported to improve insulin sensitivity and exert anti-inflammatory, anti-obesity effect in animal studies. Interestingly, Uptake and resecretion of apoA-I by adipocytes has been detected. However, the significance of apoA-I recycling by adipocytes is still not clear. This article reviewed methods used to study cellular recycling of apoA-I and summarized the current knowledge on the mechanisms involved in apoA-I uptake by adipocytes. Since the main function of apoA-I is to mediate reverse cholesterol transport from peripheral tissues, the role of apoA-I internalization and re-secretion by adipocytes in intracellular cholesterol transport under physiological and pathological conditions were discussed. In addition, findings on the correlation between apoA-I recycling and obesity were discussed. Finally, it was proposed that during intracellular transport, apoA-I-protein complex may acquire cargoes other than lipids and deliver regulatory information when they were resecreted into the plasma. Although apoA-I recycling by adipocytes is still an unsolved mystery, it's likely that it is more than a redundant pathway especially under pathological conditions.
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Affiliation(s)
- Shuai Wang
- Department of Cardiology, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Dao-quan Peng
- Department of Cardiology, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China.
| | - Yuhong Yi
- The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
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30
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Abstract
PURPOSE OF REVIEW Adipose tissue is a critical endocrine and immunological organ that regulates systemic energy homeostasis. During the pathogenesis of obesity, adipocyte hypertrophy is accompanied by adipose tissue inflammation, impeding insulin sensitivity and endocrine function of adipose tissue and other tissues. Adipocyte cholesterol accumulates in proportion to triglyceride as adipocytes undergo hypertrophy. Recent studies suggest that dietary cholesterol contributes to increased adipocyte cholesterol. However, how dietary cholesterol accumulates in adipocytes and its metabolic consequences are poorly understood. This review summarizes recent advances in knowledge of adipocyte cholesterol balance and highlights the emerging role of dietary cholesterol in adipose tissue cholesterol balance, inflammation, and systemic energy metabolism. RECENT FINDINGS Perturbation of cholesterol balance in adipocytes alters intracellular cholesterol distribution and modulates adipocyte insulin and proinflammatory signaling. Adipocyte cholesterol levels are maintained by a balance between dietary cholesterol uptake from triglyceride-enriched lipoproteins and cellular cholesterol efflux to HDL. Recent animal studies established a critical role for dietary cholesterol in promoting adipose tissue inflammation, thereby worsening obesity-mediated metabolic complications. SUMMARY Recent studies identified high dietary cholesterol as a potentiator of adipose tissue inflammation and dysfunction. Reducing excessive dietary cholesterol intake is suggested as a simple, but novel, way to attenuate obesity-associated metabolic diseases.
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Affiliation(s)
- Soonkyu Chung
- Department of Nutrition and Health Sciences, University of Nebraska, Lincoln, NE 68516
| | - John S. Parks
- Department of Internal Medicine/Molecular Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27157
- Department of Biochemistry, Wake Forest School of Medicine, Winston-Salem, NC 27157
- Corresponding author: John S. Parks; Department of Internal Medicine/Section on Molecular Medicine, Wake Forest School of Medicine, Medical Center Blvd, Winston-Salem, NC 27157 phone: 336-716-2145 fax: 336-716-6279
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31
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Bays HE, Jones PH, Jacobson TA, Cohen DE, Orringer CE, Kothari S, Azagury DE, Morton J, Nguyen NT, Westman EC, Horn DB, Scinta W, Primack C. Lipids and bariatric procedures part 1 of 2: Scientific statement from the National Lipid Association, American Society for Metabolic and Bariatric Surgery, and Obesity Medicine Association: FULL REPORT. J Clin Lipidol 2016; 10:33-57. [DOI: 10.1016/j.jacl.2015.12.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 12/01/2015] [Indexed: 02/06/2023]
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32
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Wüstner D, Lund FW, Röhrl C, Stangl H. Potential of BODIPY-cholesterol for analysis of cholesterol transport and diffusion in living cells. Chem Phys Lipids 2016; 194:12-28. [DOI: 10.1016/j.chemphyslip.2015.08.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 08/07/2015] [Accepted: 08/12/2015] [Indexed: 01/04/2023]
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Lindahl M, Petrlova J, Dalla-Riva J, Wasserstrom S, Rippe C, Domingo-Espin J, Kotowska D, Krupinska E, Berggreen C, Jones HA, Swärd K, Lagerstedt JO, Göransson O, Stenkula KG. ApoA-I Milano stimulates lipolysis in adipose cells independently of cAMP/PKA activation. J Lipid Res 2015; 56:2248-59. [PMID: 26504176 DOI: 10.1194/jlr.m054767] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Indexed: 11/20/2022] Open
Abstract
ApoA-I, the main protein component of HDL, is suggested to be involved in metabolic homeostasis. We examined the effects of Milano, a naturally occurring ApoA-I variant, about which little mechanistic information is available. Remarkably, high-fat-fed mice treated with Milano displayed a rapid weight loss greater than ApoA-I WT treated mice, and a significantly reduced adipose tissue mass, without an inflammatory response. Further, lipolysis in adipose cells isolated from mice treated with either WT or Milano was increased. In primary rat adipose cells, Milano stimulated cholesterol efflux and increased glycerol release, independently of β-adrenergic stimulation and phosphorylation of hormone sensitive lipase (Ser563) and perilipin (Ser522). Stimulation with Milano had a significantly greater effect on glycerol release compared with WT but similar effect on cholesterol efflux. Pharmacological inhibition or siRNA silencing of ABCA1 did not diminish Milano-stimulated lipolysis, although binding to the cell surface was decreased, as analyzed by fluorescence microscopy. Interestingly, methyl-β-cyclodextrin, a well-described cholesterol acceptor, dose-dependently stimulated lipolysis. Together, these results suggest that decreased fat mass and increased lipolysis following Milano treatment in vivo is partly explained by a novel mechanism at the adipose cell level comprising stimulation of lipolysis independently of the canonical cAMP/protein kinase A signaling pathway.
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Affiliation(s)
- Maria Lindahl
- Medical Protein Science, Lund University, 221 84 Lund, Sweden Glucose Transport and Protein Trafficking, Lund University, 221 84 Lund, Sweden
| | - Jitka Petrlova
- Medical Protein Science, Lund University, 221 84 Lund, Sweden
| | | | | | - Catarina Rippe
- Cellular Biomechanics, Lund University, 221 84 Lund, Sweden
| | | | - Dorota Kotowska
- Glucose Transport and Protein Trafficking, Lund University, 221 84 Lund, Sweden
| | - Ewa Krupinska
- Medical Protein Science, Lund University, 221 84 Lund, Sweden
| | | | - Helena A Jones
- Molecular Endocrinology, Department of Experimental Medical Science, Biomedical Center, Lund University, 221 84 Lund, Sweden
| | - Karl Swärd
- Cellular Biomechanics, Lund University, 221 84 Lund, Sweden
| | | | - Olga Göransson
- Protein Phosphorylation, Lund University, 221 84 Lund, Sweden
| | - Karin G Stenkula
- Glucose Transport and Protein Trafficking, Lund University, 221 84 Lund, Sweden
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Makdissy N, Haddad K, Mouawad C, Popa I, Younsi M, Valet P, Brunaud L, Ziegler O, Quilliot D. Regulation of SREBPs by Sphingomyelin in Adipocytes via a Caveolin and Ras-ERK-MAPK-CREB Signaling Pathway. PLoS One 2015; 10:e0133181. [PMID: 26230734 DOI: 10.1371/journal.pone.0133181] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 06/23/2015] [Indexed: 01/07/2023] Open
Abstract
Sterol response element binding protein (SREBP) is a key transcription factor in insulin and glucose metabolism. We previously demonstrated that elevated levels of membrane sphingomyelin (SM) were related to peroxisome proliferator–activated receptor-γ (PPARγ), which is a known target gene of SREBP-1 in adipocytes. However, the role of SM in SREBP expression in adipocytes remains unknown. In human abdominal adipose tissue from obese women with various concentrations of fasting plasma insulin, SREBP-1 proteins decreased in parallel with increases in membrane SM levels. An inverse correlation was found between the membrane SM content and the levels of SREBP-1c/ERK/Ras/PPARγ/CREB proteins. For the first time, we demonstrate the effects of SM and its signaling pathway in 3T3-F442A adipocytes. These cells were enriched or unenriched with SM in a range of concentrations similar to those observed in obese subjects by adding exogenous natural SMs (having different acyl chain lengths) or by inhibiting neutral sphingomyelinase. SM accumulated in caveolae of the plasma membrane within 24 h and then in the intracellular space. SM enrichment decreased SREBP-1 through the inhibition of extracellular signal-regulated protein kinase (ERK) but not JNK or p38 mitogen-activated protein kinase (MAPK). Ras/Raf-1/MEK1/2 and KSR proteins, which are upstream mediators of ERK, were down-regulated, whereas SREBP-2/caveolin and cholesterol were up-regulated. In SM-unmodulated adipocytes treated with DL-1-Phenyl-2-Palmitoylamino-3-morpholino-1-propanol (PPMP), where the ceramide level increased, the expression levels of SREBPs and ERK were modulated in an opposite direction relative to the SM-enriched cells. SM inhibited the insulin-induced expression of SREBP-1. Rosiglitazone, which is an anti-diabetic agent and potent activator of PPARγ, reversed the effects of SM on SREBP-1, PPARγ and CREB. Taken together, these findings provide novel insights indicating that excess membrane SM might be critical for regulating SREBPs in adipocytes via a MAPK-dependent pathway.
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35
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Mihai AD, Schröder M. Glucose starvation and hypoxia, but not the saturated fatty acid palmitic acid or cholesterol, activate the unfolded protein response in 3T3-F442A and 3T3-L1 adipocytes. Adipocyte 2015; 4:188-202. [PMID: 26257992 DOI: 10.4161/21623945.2014.989728] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 11/08/2014] [Accepted: 11/14/2014] [Indexed: 12/26/2022] Open
Abstract
Obesity is associated with endoplasmic reticulum (ER) stress and activation of the unfolded protein response (UPR) in adipose tissue. In this study we identify physiological triggers of ER stress and of the UPR in adipocytes in vitro. We show that two markers of adipose tissue remodelling in obesity, glucose starvation and hypoxia, cause ER stress in 3T3-F442A and 3T3-L1 adipocytes. Both conditions induced molecular markers of the IRE1α and PERK branches of the UPR, such as splicing of XBP1 mRNA and CHOP, as well as transcription of the ER stress responsive gene BiP. Hypoxia also induced an increase in phosphorylation of the PERK substrate eIF2α. By contrast, physiological triggers of ER stress in many other cell types, such as the saturated fatty acid palmitic acid, cholesterol, or several inflammatory cytokines including TNF-α, IL-1β, and IL-6, do not cause ER stress in 3T3-F442A and 3T3-L1 adipocytes. Our data suggest that physiological changes associated with remodelling of adipose tissue in obesity, such as hypoxia and glucose starvation, are more likely physiological ER stressors of adipocytes than the lipid overload or hyperinsulinemia associated with obesity.
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36
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Urrutia RA, Kalinec F. Biology and pathobiology of lipid droplets and their potential role in the protection of the organ of Corti. Hear Res 2015; 330:26-38. [PMID: 25987503 DOI: 10.1016/j.heares.2015.04.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 04/17/2015] [Accepted: 04/21/2015] [Indexed: 12/20/2022]
Abstract
The current review article seeks to extend our understanding on the role of lipid droplets within the organ of Corti. In addition to presenting an overview of the current information about the origin, structure and function of lipid droplets we draw inferences from the collective body of knowledge about this cellular organelle to build a conceptual framework to better understanding their role in auditory function. This conceptual model considers that lipid droplets play a significant role in the synthesis, storage, and release of lipids and proteins for energetic use and/or modulating cell signaling pathways. We describe the role and mechanism by which LD play a role in human diseases, and we also review emerging data from our laboratory revealing the potential role of lipid droplets from Hensen cells in the auditory organ. We suggest that lipid droplets might help to develop rapidly and efficiently the resolution phase of inflammatory responses in the mammalian cochlea, preventing inflammatory damage of the delicate inner ear structures and, consequently, sensorineural hearing loss.
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Affiliation(s)
- Raul A Urrutia
- Epigenetics and Chromatin Dynamics Laboratory, Translational Epigenomic Program, Center for Individualized Medicine (CIM) Mayo Clinic, Rochester, MN 55905, USA
| | - Federico Kalinec
- Laboratory of Auditory Cell Biology, Department of Head & Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
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37
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Affiliation(s)
- Andrew J Murphy
- Baker IDI Heart and Diabetes Institute, Melbourne, Australia
| | - Laurent Yvan-Charvet
- Institut National de la Santé et de la Recherche Médicale U1065, Centre Mediterranéen de Médecine Moléculaire, Nice, France
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Adaikalakoteswari A, Finer S, Voyias PD, McCarthy CM, Vatish M, Moore J, Smart-Halajko M, Bawazeer N, Al-Daghri NM, McTernan PG, Kumar S, Hitman GA, Saravanan P, Tripathi G. Vitamin B12 insufficiency induces cholesterol biosynthesis by limiting s-adenosylmethionine and modulating the methylation of SREBF1 and LDLR genes. Clin Epigenetics 2015; 7:14. [PMID: 25763114 PMCID: PMC4356060 DOI: 10.1186/s13148-015-0046-8] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 01/14/2015] [Indexed: 12/23/2022] Open
Abstract
Background The dietary supply of methyl donors such as folate, vitamin B12, betaine, methionine, and choline is essential for normal growth, development, and physiological functions through the life course. Both human and animal studies have shown that vitamin B12 deficiency is associated with altered lipid profile and play an important role in the prediction of metabolic risk, however, as of yet, no direct mechanism has been investigated to confirm this. Results Three independent clinical studies of women (i) non-pregnant at child-bearing age, (ii) in early pregnancy, and (iii) at delivery showed that low vitamin B12 status was associated with higher total cholesterol, LDL cholesterol, and cholesterol-to-HDL ratio. These results guided the investigation into the cellular mechanisms of induced cholesterol biosynthesis due to vitamin B12 deficiency, using human adipocytes as a model system. Adipocytes cultured in low or no vitamin B12 conditions had increased cholesterol and homocysteine levels compared to control. The induction of cholesterol biosynthesis was associated with reduced s-adenosylmethionine (AdoMet)-to-s-adenosylhomocysteine (AdoHcy) ratio, also known as methylation potential (MP). We therefore studied whether reduced MP could lead to hypomethylation of genes involved in the regulation of cholesterol biosynthesis. Genome-wide and targeted DNA methylation analysis identified that the promoter regions of SREBF1 and LDLR, two key regulators of cholesterol biosynthesis, were hypomethylated under vitamin B12-deficient conditions, and as a result, their expressions and cholesterol biosynthesis were also significantly increased. This finding was further confirmed by the addition of the methylation inhibitor, 5-aza-2′-deoxycytidine, which resulted in increased SREBF1 and LDLR expressions and cholesterol accumulation in vitamin B12-sufficient conditions. Finally, we observed that the expression of SREBF1, LDLR, and cholesterol biosynthesis genes were increased in adipose tissue of vitamin B12 deficient mothers compared to control group. Conclusions Clinical data suggests that vitamin B12 deficiency is an important metabolic risk factor. Regulation of AdoMet-to-AdoHcy levels by vitamin B12 could be an important mechanism by which it can influence cholesterol biosynthesis pathway in human adipocytes. Electronic supplementary material The online version of this article (doi:10.1186/s13148-015-0046-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Antonysunil Adaikalakoteswari
- Division of Metabolic and Vascular Health, Clinical Sciences Research Laboratories, Warwick Medical School, University Hospital Coventry and Warwickshire, University of Warwick, Clifford Bridge Road, Coventry, CV2 2DX UK
| | - Sarah Finer
- Centre for Diabetes, Blizard Institute, Queen Mary University of London, 4 Newark Street, London, E1 2AT UK ; Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Level 4, University of Cambridge, Addenbrooke's Hospital, Box 289, Cambridge, CB2 0QQ UK
| | - Philip D Voyias
- Division of Metabolic and Vascular Health, Clinical Sciences Research Laboratories, Warwick Medical School, University Hospital Coventry and Warwickshire, University of Warwick, Clifford Bridge Road, Coventry, CV2 2DX UK
| | - Ciara M McCarthy
- Division of Metabolic and Vascular Health, Clinical Sciences Research Laboratories, Warwick Medical School, University Hospital Coventry and Warwickshire, University of Warwick, Clifford Bridge Road, Coventry, CV2 2DX UK
| | - Manu Vatish
- Nuffield Department of Obstetrics and Gynaecology University of Oxford Level 3, John Radcliffe Hospital, Oxford, University of Oxford, Oxford, OX3 9DU UK
| | - Jonathan Moore
- Warwick Systems Biology, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL UK
| | - Melissa Smart-Halajko
- Centre for Diabetes, Blizard Institute, Queen Mary University of London, 4 Newark Street, London, E1 2AT UK
| | - Nahla Bawazeer
- Division of Metabolic and Vascular Health, Clinical Sciences Research Laboratories, Warwick Medical School, University Hospital Coventry and Warwickshire, University of Warwick, Clifford Bridge Road, Coventry, CV2 2DX UK
| | - Nasser M Al-Daghri
- Biochemistry Department, College of Science, King Saud University, Riyadh, 11451 Saudi Arabia
| | - Philip G McTernan
- Division of Metabolic and Vascular Health, Clinical Sciences Research Laboratories, Warwick Medical School, University Hospital Coventry and Warwickshire, University of Warwick, Clifford Bridge Road, Coventry, CV2 2DX UK
| | - Sudhesh Kumar
- Division of Metabolic and Vascular Health, Clinical Sciences Research Laboratories, Warwick Medical School, University Hospital Coventry and Warwickshire, University of Warwick, Clifford Bridge Road, Coventry, CV2 2DX UK
| | - Graham A Hitman
- Centre for Diabetes, Blizard Institute, Queen Mary University of London, 4 Newark Street, London, E1 2AT UK
| | - Ponnusamy Saravanan
- Division of Metabolic and Vascular Health, Clinical Sciences Research Laboratories, Warwick Medical School, University Hospital Coventry and Warwickshire, University of Warwick, Clifford Bridge Road, Coventry, CV2 2DX UK ; iDEA Centre, George Eliot Hospital, Nuneton, CV10 7DJ UK
| | - Gyanendra Tripathi
- Division of Metabolic and Vascular Health, Clinical Sciences Research Laboratories, Warwick Medical School, University Hospital Coventry and Warwickshire, University of Warwick, Clifford Bridge Road, Coventry, CV2 2DX UK
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Chung S, Cuffe H, Marshall SM, McDaniel AL, Ha JH, Kavanagh K, Hong C, Tontonoz P, Temel RE, Parks JS. Dietary cholesterol promotes adipocyte hypertrophy and adipose tissue inflammation in visceral, but not in subcutaneous, fat in monkeys. Arterioscler Thromb Vasc Biol 2014; 34:1880-7. [PMID: 24969772 DOI: 10.1161/atvbaha.114.303896] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECTIVE Excessive caloric intake is associated with obesity and adipose tissue dysfunction. However, the role of dietary cholesterol in this process is unknown. The aim of this study was to determine whether increasing dietary cholesterol intake alters adipose tissue cholesterol content, adipocyte size, and endocrine function in nonhuman primates. APPROACH AND RESULTS Age-matched, male African Green monkeys (n=5 per group) were assigned to 1 of 3 diets containing 0.002 (low [Lo]), 0.2 (medium [Med]), or 0.4 (high [Hi]) mg cholesterol/kcal. After 10 weeks of diet feeding, animals were euthanized for adipose tissue, liver, and plasma collection. With increasing dietary cholesterol, free cholesterol (FC) content and adipocyte size increased in a stepwise manner in visceral, but not in subcutaneous fat, with a significant association between visceral adipocyte size and FC content (r(2)=0.298; n=15; P=0.035). In visceral fat, dietary cholesterol intake was associated with (1) increased proinflammatory gene expression and macrophage recruitment, (2) decreased expression of genes involved in cholesterol biosynthesis and lipoprotein uptake, and (3) increased expression of proteins involved in FC efflux. CONCLUSIONS Increasing dietary cholesterol selectively increases visceral fat adipocyte size, FC and macrophage content, and proinflammatory gene expression in nonhuman primates. Visceral fat cells seem to compensate for increased dietary cholesterol by limiting cholesterol uptake/synthesis and increasing FC efflux pathways.
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Affiliation(s)
- Soonkyu Chung
- From the Department of Pathology, Sections on Lipid Sciences (S.C., H.C., S.M.M., A.L.M., R.E.T., J.S.P.) and Comparative Medicine (K.K.), and Department of Biochemistry (J.S.P.), Wake Forest School of Medicine, Winston-Salem, NC; Department of Nutrition and Health Sciences, University of Nebraska, Lincoln (S.C.); Department of Food Science and Human Nutrition, University of Florida, Gainesville (S.C., J.-H.H.); and Department of Pathology and Laboratory Medicine, Howard Hughes Medical Institute, University of California, Los Angeles (C.H., P.T.)
| | - Helen Cuffe
- From the Department of Pathology, Sections on Lipid Sciences (S.C., H.C., S.M.M., A.L.M., R.E.T., J.S.P.) and Comparative Medicine (K.K.), and Department of Biochemistry (J.S.P.), Wake Forest School of Medicine, Winston-Salem, NC; Department of Nutrition and Health Sciences, University of Nebraska, Lincoln (S.C.); Department of Food Science and Human Nutrition, University of Florida, Gainesville (S.C., J.-H.H.); and Department of Pathology and Laboratory Medicine, Howard Hughes Medical Institute, University of California, Los Angeles (C.H., P.T.)
| | - Stephanie M Marshall
- From the Department of Pathology, Sections on Lipid Sciences (S.C., H.C., S.M.M., A.L.M., R.E.T., J.S.P.) and Comparative Medicine (K.K.), and Department of Biochemistry (J.S.P.), Wake Forest School of Medicine, Winston-Salem, NC; Department of Nutrition and Health Sciences, University of Nebraska, Lincoln (S.C.); Department of Food Science and Human Nutrition, University of Florida, Gainesville (S.C., J.-H.H.); and Department of Pathology and Laboratory Medicine, Howard Hughes Medical Institute, University of California, Los Angeles (C.H., P.T.)
| | - Allison L McDaniel
- From the Department of Pathology, Sections on Lipid Sciences (S.C., H.C., S.M.M., A.L.M., R.E.T., J.S.P.) and Comparative Medicine (K.K.), and Department of Biochemistry (J.S.P.), Wake Forest School of Medicine, Winston-Salem, NC; Department of Nutrition and Health Sciences, University of Nebraska, Lincoln (S.C.); Department of Food Science and Human Nutrition, University of Florida, Gainesville (S.C., J.-H.H.); and Department of Pathology and Laboratory Medicine, Howard Hughes Medical Institute, University of California, Los Angeles (C.H., P.T.)
| | - Jung-Heun Ha
- From the Department of Pathology, Sections on Lipid Sciences (S.C., H.C., S.M.M., A.L.M., R.E.T., J.S.P.) and Comparative Medicine (K.K.), and Department of Biochemistry (J.S.P.), Wake Forest School of Medicine, Winston-Salem, NC; Department of Nutrition and Health Sciences, University of Nebraska, Lincoln (S.C.); Department of Food Science and Human Nutrition, University of Florida, Gainesville (S.C., J.-H.H.); and Department of Pathology and Laboratory Medicine, Howard Hughes Medical Institute, University of California, Los Angeles (C.H., P.T.)
| | - Kylie Kavanagh
- From the Department of Pathology, Sections on Lipid Sciences (S.C., H.C., S.M.M., A.L.M., R.E.T., J.S.P.) and Comparative Medicine (K.K.), and Department of Biochemistry (J.S.P.), Wake Forest School of Medicine, Winston-Salem, NC; Department of Nutrition and Health Sciences, University of Nebraska, Lincoln (S.C.); Department of Food Science and Human Nutrition, University of Florida, Gainesville (S.C., J.-H.H.); and Department of Pathology and Laboratory Medicine, Howard Hughes Medical Institute, University of California, Los Angeles (C.H., P.T.)
| | - Cynthia Hong
- From the Department of Pathology, Sections on Lipid Sciences (S.C., H.C., S.M.M., A.L.M., R.E.T., J.S.P.) and Comparative Medicine (K.K.), and Department of Biochemistry (J.S.P.), Wake Forest School of Medicine, Winston-Salem, NC; Department of Nutrition and Health Sciences, University of Nebraska, Lincoln (S.C.); Department of Food Science and Human Nutrition, University of Florida, Gainesville (S.C., J.-H.H.); and Department of Pathology and Laboratory Medicine, Howard Hughes Medical Institute, University of California, Los Angeles (C.H., P.T.)
| | - Peter Tontonoz
- From the Department of Pathology, Sections on Lipid Sciences (S.C., H.C., S.M.M., A.L.M., R.E.T., J.S.P.) and Comparative Medicine (K.K.), and Department of Biochemistry (J.S.P.), Wake Forest School of Medicine, Winston-Salem, NC; Department of Nutrition and Health Sciences, University of Nebraska, Lincoln (S.C.); Department of Food Science and Human Nutrition, University of Florida, Gainesville (S.C., J.-H.H.); and Department of Pathology and Laboratory Medicine, Howard Hughes Medical Institute, University of California, Los Angeles (C.H., P.T.)
| | - Ryan E Temel
- From the Department of Pathology, Sections on Lipid Sciences (S.C., H.C., S.M.M., A.L.M., R.E.T., J.S.P.) and Comparative Medicine (K.K.), and Department of Biochemistry (J.S.P.), Wake Forest School of Medicine, Winston-Salem, NC; Department of Nutrition and Health Sciences, University of Nebraska, Lincoln (S.C.); Department of Food Science and Human Nutrition, University of Florida, Gainesville (S.C., J.-H.H.); and Department of Pathology and Laboratory Medicine, Howard Hughes Medical Institute, University of California, Los Angeles (C.H., P.T.)
| | - John S Parks
- From the Department of Pathology, Sections on Lipid Sciences (S.C., H.C., S.M.M., A.L.M., R.E.T., J.S.P.) and Comparative Medicine (K.K.), and Department of Biochemistry (J.S.P.), Wake Forest School of Medicine, Winston-Salem, NC; Department of Nutrition and Health Sciences, University of Nebraska, Lincoln (S.C.); Department of Food Science and Human Nutrition, University of Florida, Gainesville (S.C., J.-H.H.); and Department of Pathology and Laboratory Medicine, Howard Hughes Medical Institute, University of California, Los Angeles (C.H., P.T.).
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Abstract
The main cells of the adipose tissue of animals, adipocytes, are characterized by the presence of large cytosolic lipid droplets (LDs) that store triglyceride (TG) and cholesterol. However, most cells have LDs and the ability to store lipids. LDs have a well-known central role in storage and provision of fatty acids and cholesterol. However, the complexity of the regulation of lipid metabolism on the surface of the LDs is still a matter of intense study. Beyond this role, a number of recent studies have suggested that LDs have major functions in other cellular processes, such as protein storage and degradation, infection, and immunity. Thus, our perception of LDs has been radically transformed from simple globules of fat to highly dynamic organelles of unexpected complexity. Here, we compiled some recent evidence supporting the emerging view that LDs act as platforms connecting a number of relevant metabolic and cellular functions.
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Affiliation(s)
- Estela L Arrese
- Department of Biochemistry and Molecular Biology; Oklahoma State University; Stillwater, OK, 74078, USA
| | - Fredy Z Saudale
- Department of Biochemistry and Molecular Biology; Oklahoma State University; Stillwater, OK, 74078, USA
| | - Jose L Soulages
- Department of Biochemistry and Molecular Biology; Oklahoma State University; Stillwater, OK, 74078, USA
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Heid H, Rickelt S, Zimbelmann R, Winter S, Schumacher H, Dörflinger Y, Kuhn C, Franke WW. On the formation of lipid droplets in human adipocytes: the organization of the perilipin-vimentin cortex. PLoS One 2014; 9:e90386. [PMID: 24587346 DOI: 10.1371/journal.pone.0090386] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 01/29/2014] [Indexed: 12/22/2022] Open
Abstract
We report on the heterogeneity and diversity of lipid droplets (LDs) in early stages of adipogenesis by elucidating the cell and molecular biology of amphiphilic and cytoskeletal proteins regulating and stabilizing the generation of LDs in human adipose cells. A plethora of distinct and differently sized LDs was detected by a brief application of adipocyte differentiation medium and additional short treatment with oleic acid. Using these cells and highly specific antibodies for LD-binding proteins of the perilipin (PLIN) family, we could distinguish between endogenously derived LDs (endogenous LDs) positive for perilipin from exogenously induced LDs (exogenous LDs) positive for adipophilin, TIP47 and S3-12. Having optimized these stimulation conditions, we used early adipogenic differentiation stages to investigate small-sized LDs and concentrated on LD-protein associations with the intermediate-sized filament (IF) vimentin. This IF protein was described earlier to surround lipid globules, showing spherical, cage-like structures. Consequently - by biochemical methods, by immunofluorescence microscopy and by electron- and immunoelectron microscopy - various stages of emerging lipid globules were revealed with perilipin as linking protein between LDs and vimentin. For this LD-PLIN-Vimentin connection, a model is now proposed, suggesting an interaction of proteins via opposed charged amino acid domains respectively. In addition, multiple sheaths of smooth endoplasmic reticulum cisternae surrounding concentrically nascent LDs are shown. Based on our comprehensive localization studies we present and discuss a novel pathway for the LD formation.
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Wei H, Averill MM, McMillen TS, Dastvan F, Mitra P, Subramanian S, Tang C, Chait A, Leboeuf RC. Modulation of adipose tissue lipolysis and body weight by high-density lipoproteins in mice. Nutr Diabetes 2014; 4:e108. [PMID: 24567123 DOI: 10.1038/nutd.2014.4] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Accepted: 01/05/2014] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Obesity is associated with reduced levels of circulating high-density lipoproteins (HDLs) and its major protein, apolipoprotein (apo) A-I. As a result of the role of HDL and apoA-I in cellular lipid transport, low HDL and apoA-I may contribute directly to establishing or maintaining the obese condition. METHODS To test this, male C57BL/6 wild-type (WT), apoA-I deficient (apoA-I(-/-)) and apoA-I transgenic (apoA-I(tg/tg)) mice were fed obesogenic diets (ODs) and monitored for several clinical parameters. We also performed cell culture studies. RESULTS ApoA-I(-/-) mice gained significantly more body weight and body fat than WT mice over 20 weeks despite their reduced food intake. During a caloric restriction regime imposed on OD-fed mice, apoA-I deficiency significantly inhibited the loss of body fat as compared with WT mice. Reduced body fat loss with caloric restriction in apoA-I(-/-) mice was associated with blunted stimulated adipose tissue lipolysis as verified by decreased levels of phosphorylated hormone-sensitive lipase (p-HSL) and lipolytic enzyme mRNA. In contrast to apoA-I(-/-) mice, apoA-I(tg/tg) mice gained relatively less weight than WT mice, consistent with other reports. ApoA-I(tg/tg) mice showed increased adipose tissue lipolysis, verified by increased levels of p-HSL and lipolytic enzyme mRNA. In cell culture studies, HDL and apoA-I specifically increased catecholamine-induced lipolysis possibly through modulating the adipocyte plasma membrane cholesterol content. CONCLUSIONS Thus, apoA-I and HDL contribute to modulating body fat content by controlling the extent of lipolysis. ApoA-I and HDL are key components of lipid metabolism in adipose tissue and constitute new therapeutic targets in obesity.
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Ohsaki Y, Suzuki M, Fujimoto T. Open Questions in Lipid Droplet Biology. ACTA ACUST UNITED AC 2014; 21:86-96. [DOI: 10.1016/j.chembiol.2013.08.009] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2013] [Revised: 08/12/2013] [Accepted: 08/23/2013] [Indexed: 12/31/2022]
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Crunk AE, Monks J, Murakami A, Jackman M, MacLean PS, Ladinsky M, Bales ES, Cain S, Orlicky DJ, McManaman JL. Dynamic regulation of hepatic lipid droplet properties by diet. PLoS One 2013; 8:e67631. [PMID: 23874434 PMCID: PMC3708958 DOI: 10.1371/journal.pone.0067631] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Accepted: 05/20/2013] [Indexed: 12/21/2022] Open
Abstract
Cytoplasmic lipid droplets (CLD) are organelle-like structures that function in neutral lipid storage, transport and metabolism through the actions of specific surface-associated proteins. Although diet and metabolism influence hepatic CLD levels, how they affect CLD protein composition is largely unknown. We used non-biased, shotgun, proteomics in combination with metabolic analysis, quantitative immunoblotting, electron microscopy and confocal imaging to define the effects of low- and high-fat diets on CLD properties in fasted-refed mice. We found that the hepatic CLD proteome is distinct from that of CLD from other mammalian tissues, containing enzymes from multiple metabolic pathways. The hepatic CLD proteome is also differentially affected by dietary fat content and hepatic metabolic status. High fat feeding markedly increased the CLD surface density of perilipin-2, a critical regulator of hepatic neutral lipid storage, whereas it reduced CLD levels of betaine-homocysteine S-methyltransferase, an enzyme regulator of homocysteine levels linked to fatty liver disease and hepatocellular carcinoma. Collectively our data demonstrate that the hepatic CLD proteome is enriched in metabolic enzymes, and that it is qualitatively and quantitatively regulated by diet and metabolism. These findings implicate CLD in the regulation of hepatic metabolic processes, and suggest that their properties undergo reorganization in response to hepatic metabolic demands.
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Affiliation(s)
- Amanda E. Crunk
- Graduate Program of Molecular Biology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- Division of Basic Reproductive Sciences, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Jenifer Monks
- Division of Basic Reproductive Sciences, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Aya Murakami
- Graduate Program of Molecular Biology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Matthew Jackman
- Division of Endocrinology and Metabolism, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- The Center for Human Nutrition, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- The Colorado Obesity Research Initiative, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Paul S. MacLean
- Division of Endocrinology and Metabolism, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- The Center for Human Nutrition, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- The Colorado Obesity Research Initiative, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Mark Ladinsky
- The Boulder Laboratory for 3D Electron Microscopy, University of Colorado Boulder, Boulder Colorado, United States of America
| | - Elise S. Bales
- Division of Basic Reproductive Sciences, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Shannon Cain
- The Colorado Obesity Research Initiative, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - David J. Orlicky
- Department of Pathology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - James L. McManaman
- Graduate Program of Molecular Biology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- Division of Basic Reproductive Sciences, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- The Center for Human Nutrition, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- The Colorado Obesity Research Initiative, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- * E-mail:
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Takahashi Y, Shinoda A, Furuya N, Harada E, Arimura N, Ichi I, Fujiwara Y, Inoue J, Sato R. Perilipin-mediated lipid droplet formation in adipocytes promotes sterol regulatory element-binding protein-1 processing and triacylglyceride accumulation. PLoS One 2013; 8:e64605. [PMID: 23734208 PMCID: PMC3667186 DOI: 10.1371/journal.pone.0064605] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 04/16/2013] [Indexed: 11/18/2022] Open
Abstract
Sterol regulatory element-binding protein-1 (SREBP-1) has been thought to be a critical factor that assists adipogenesis. During adipogenesis SREBP-1 stimulates lipogenic gene expression, and peroxisome proliferator-activated receptor γ (PPARγ) enhances perilipin (plin) gene expression, resulting in generating lipid droplets (LDs) to store triacylglycerol (TAG) in adipocytes. Plin coats adipocyte LDs and protects them from lipolysis. Here we show in white adipose tissue (WAT) of plin-/- mice that nuclear active SREBP-1 and its target gene expression, but not nuclear SREBP-2, significantly decreased on attenuated LD formation. When plin-/- mouse embryonic fibroblasts (MEFs) differentiated into adipocytes, attenuated LDs were formed and nuclear SREBP-1 decreased, but enforced plin expression restored them to their original state. Since LDs are largely derived from the endoplasmic reticulum (ER), alterations in the ER cholesterol content were investigated during adipogenesis of 3T3-L1 cells. The ER cholesterol greatly reduced in differentiated adipocytes. The ER cholesterol level in plin-/- WAT was significantly higher than that of wild-type mice, suggesting that increased LD formation caused a change in ER environment along with a decrease in cholesterol. When GFP-SREBP-1 fusion proteins were exogenously expressed in 3T3-L1 cells, a mutant protein lacking the S1P cleavage site was poorly processed during adipogenesis, providing evidence of the increased canonical pathway for SREBP processing in which SREBP-1 is activated by two cleavage enzymes in the Golgi. Therefore, LD biogenesis may create the ER microenvironment favorable for SREBP-1 activation. We describe the novel interplay between LD formation and SREBP-1 activation through a positive feedback loop.
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Affiliation(s)
- Yu Takahashi
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Akihiro Shinoda
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Norihiko Furuya
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Eri Harada
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Naoto Arimura
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Ikuyo Ichi
- Department of Nutrition and Food Science, Ochanomizu University, Tokyo, Japan
| | - Yoko Fujiwara
- Department of Nutrition and Food Science, Ochanomizu University, Tokyo, Japan
| | - Jun Inoue
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Ryuichiro Sato
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
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Abstract
The esterification of amphiphilic alcohols with fatty acids is a ubiquitous strategy implemented by eukaryotes and some prokaryotes to conserve energy and membrane progenitors and simultaneously detoxify fatty acids and other lipids. This key reaction is performed by at least four evolutionarily unrelated multigene families. The synthesis of this "neutral lipid" leads to the formation of a lipid droplet, which despite the clear selective advantage it confers is also a harbinger of cellular and organismal malaise. Neutral lipid deposition as a cytoplasmic lipid droplet may be thermodynamically favored but nevertheless is elaborately regulated. Optimal utilization of these resources by lipolysis is similarly multigenic in determination and regulation. We present here a perspective on these processes that originates from studies in model organisms, and we include our thoughts on interventions that target reductions in neutral lipids as therapeutics for human diseases such as obesity and diabetes.
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Affiliation(s)
- Kelly V Ruggles
- Institute of Human Nutrition, Columbia University Medical Center, New York, NY 10032, USA.
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Konige M, Wang H, Sztalryd C. Role of adipose specific lipid droplet proteins in maintaining whole body energy homeostasis. Biochim Biophys Acta Mol Basis Dis 2013; 1842:393-401. [PMID: 23688782 DOI: 10.1016/j.bbadis.2013.05.007] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Revised: 04/10/2013] [Accepted: 05/03/2013] [Indexed: 12/15/2022]
Abstract
Excess or insufficient lipid storage in white adipose tissue lipid droplets is associated with dyslipidemia, insulin resistance and increased risk for diabetes type 2. Thus, maintenance of adipose lipid droplet growth and function is critical to preserve whole body insulin sensitivity and energy homeostasis. Progress in understanding biology of lipid droplets has underscored the role of proteins that interact with lipid droplets. Here, we review the current knowledge of adipose specific lipid droplet proteins, which share unique functions controlling adipocyte lipid storage, limiting lipid spill-over and lipotoxic effects thought to contribute to disease. This article is part of a Special Issue entitled: Modulation of Adipose Tissue in Health and Disease.
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Affiliation(s)
- Manige Konige
- Department of Medicine, Division of Endocrinology, School of Medicine, University of Maryland, Baltimore, MD 21201, USA
| | - Hong Wang
- Department of Medicine, Division of Endocrinology, School of Medicine, University of Maryland, Baltimore, MD 21201, USA
| | - Carole Sztalryd
- Department of Medicine, Division of Endocrinology, School of Medicine, University of Maryland, Baltimore, MD 21201, USA; Geriatric Research, Education, and Clinical Center, Baltimore Veterans Affairs Health Care Center, Baltimore, MD 21201, USA.
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Penno A, Hackenbroich G, Thiele C. Phospholipids and lipid droplets. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:589-94. [PMID: 23246574 DOI: 10.1016/j.bbalip.2012.12.001] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Revised: 12/03/2012] [Accepted: 12/04/2012] [Indexed: 11/29/2022]
Abstract
Lipid droplets are ubiquitous cellular organelles that allow cells to store large amounts of neutral lipids for membrane synthesis and energy supply in times of starvation. Compared to other cellular organelles, lipid droplets are structurally unique as they are made of a hydrophobic core of neutral lipids and are separated to the cytosol only by a surrounding phospholipid monolayer. This phospholipid monolayer consists of over a hundred different phospholipid molecular species of which phosphatidylcholine is the most abundant lipid class. However, lipid droplets lack some indispensable activities of the phosphatidylcholine biogenic pathways suggesting that they partially depend on other organelles for phosphatidylcholine synthesis. Here, we discuss very recent data on the composition, origin, transport and function of the phospholipid monolayer with a particular emphasis on the phosphatidylcholine metabolism on and for lipid droplets. In addition, we highlight two very important quantitative aspects: (i) The amount of phospholipid required for lipid droplet monolayer expansion is remarkably small and (ii) to maintain the invariably round shape of lipid droplets, a cell must have a highly sensitive but so far unknown mechanism that regulates the ratio of phospholipid to neutral lipid in lipid droplets. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.
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Affiliation(s)
- Anke Penno
- Life and Medical Sciences (LIMES) Institute, University of Bonn, Carl-Troll-Str. 31, 53115 Bonn, Germany
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McIntosh AL, Senthivinayagam S, Moon KC, Gupta S, Lwande JS, Murphy CC, Storey SM, Atshaves BP. Direct interaction of Plin2 with lipids on the surface of lipid droplets: a live cell FRET analysis. Am J Physiol Cell Physiol 2012; 303:C728-42. [PMID: 22744009 DOI: 10.1152/ajpcell.00448.2011] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Despite increasing awareness of the health risks associated with excess lipid storage in cells and tissues, knowledge of events governing lipid exchange at the surface of lipid droplets remains unclear. To address this issue, fluorescence resonance energy transfer (FRET) was performed to examine live cell interactions of Plin2 with lipids involved in maintaining lipid droplet structure and function. FRET efficiencies (E) between CFP-labeled Plin2 and fluorescently labeled phosphatidylcholine, sphingomyelin, stearic acid, and cholesterol were quantitated on a pixel-by-pixel basis to generate FRET image maps that specified areas with high E (>60%) in lipid droplets. The mean E and the distance R between the probes indicated a high yield of energy transfer and demonstrated molecular distances on the order of 44-57 Å, in keeping with direct molecular contact. In contrast, FRET between CFP-Plin2 and Nile red was not detected, indicating that the CFP-Plin2/Nile red interaction was beyond FRET proximity (>100 Å). An examination of the effect of Plin2 on cellular metabolism revealed that triacylglycerol, fatty acid, and cholesteryl ester content increased while diacylglycerol remained constant in CFP-Plin2-overexpressing cells. Total phospholipids also increased, reflecting increased phosphatidylcholine and sphingomyelin. Consistent with these results, expression levels of enzymes involved in triacylglycerol, cholesteryl ester, and phospholipid synthesis were significantly upregulated in CFP-Plin2-expressing cells while those associated with lipolysis either decreased or were unaffected. Taken together, these data show for the first time that Plin2 interacts directly with lipids on the surface of lipid droplets and influences levels of key enzymes and lipids involved in maintaining lipid droplet structure and function.
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Affiliation(s)
- Avery L McIntosh
- Dept. of Biochemistry and Molecular Biology, Michigan State Univ., East Lansing, MI 48824, USA
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