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Safi R, Menéndez P, Pol A. Lipid droplets provide metabolic flexibility for cancer progression. FEBS Lett 2024; 598:1301-1327. [PMID: 38325881 DOI: 10.1002/1873-3468.14820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 01/08/2024] [Accepted: 01/10/2024] [Indexed: 02/09/2024]
Abstract
A hallmark of cancer cells is their remarkable ability to efficiently adapt to favorable and hostile environments. Due to a unique metabolic flexibility, tumor cells can grow even in the absence of extracellular nutrients or in stressful scenarios. To achieve this, cancer cells need large amounts of lipids to build membranes, synthesize lipid-derived molecules, and generate metabolic energy in the absence of other nutrients. Tumor cells potentiate strategies to obtain lipids from other cells, metabolic pathways to synthesize new lipids, and mechanisms for efficient storage, mobilization, and utilization of these lipids. Lipid droplets (LDs) are the organelles that collect and supply lipids in eukaryotes and it is increasingly recognized that the accumulation of LDs is a new hallmark of cancer cells. Furthermore, an active role of LD proteins in processes underlying tumorigenesis has been proposed. Here, by focusing on three major classes of LD-resident proteins (perilipins, lipases, and acyl-CoA synthetases), we provide an overview of the contribution of LDs to cancer progression and discuss the role of LD proteins during the proliferation, invasion, metastasis, apoptosis, and stemness of cancer cells.
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Affiliation(s)
- Rémi Safi
- Josep Carreras Leukemia Research Institute, Barcelona, Spain
- Lipid Trafficking and Disease Group, Institut d'Investigacions Biomèdiques August Pi I Sunyer (IDIBAPS), Barcelona, Spain
| | - Pablo Menéndez
- Josep Carreras Leukemia Research Institute, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
- Department of Biomedical Sciences, Faculty of Medicine, Universitat de Barcelona, Spain
- Consorcio Investigación Biomédica en Red de Cancer, CIBER-ONC, ISCIII, Barcelona, Spain
- Spanish Network for Advanced Cell Therapies (TERAV), Barcelona, Spain
| | - Albert Pol
- Lipid Trafficking and Disease Group, Institut d'Investigacions Biomèdiques August Pi I Sunyer (IDIBAPS), Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
- Department of Biomedical Sciences, Faculty of Medicine, Universitat de Barcelona, Spain
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2
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Kovacs M, Geltinger F, Schartel L, Pöschl S, Briza P, Paschinger M, Boros K, Felder TK, Wimmer H, Duschl J, Rinnerthaler M. Ola1p trafficking indicates an interaction network between mitochondria, lipid droplets, and stress granules in times of stress. J Lipid Res 2023; 64:100473. [PMID: 37949369 PMCID: PMC10757043 DOI: 10.1016/j.jlr.2023.100473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 09/25/2023] [Accepted: 11/01/2023] [Indexed: 11/12/2023] Open
Abstract
Protein aggregates arise naturally under normal physiological conditions, but their formation is accelerated by age or stress-induced protein misfolding. When the stressful event dissolves, these aggregates are removed by mechanisms, such as aggrephagy, chaperone-mediated autophagy, refolding attempts, or the proteasome. It was recently shown that mitochondria in yeast cells may support these primarily cytosolic processes. Protein aggregates attach to mitochondria, and misfolded proteins are transported into the matrix and degraded by mitochondria-specific proteases. Using a proximity labeling method and colocalization with an established stress granule (SG) marker, we were able to show that these mitochondria-localized aggregates that harbor the "super aggregator" Ola1p are, in fact, SGs. Our in vivo and in vitro studies have revealed that Ola1p can be transferred from mitochondria to lipid droplets (LDs). This "mitochondria to LD" aggregate transfer dampens proteotoxic effects. The LD-based protein aggregate removal system gains importance when other proteolytic systems fail. Furthermore, we were able to show that the distribution of SGs is drastically altered in LD-deficient yeast cells, demonstrating that LDs play a role in the SG life cycle.
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Affiliation(s)
- Melanie Kovacs
- Department of Biosciences, Paris-Lodron University Salzburg, Salzburg, Austria
| | - Florian Geltinger
- Department of Biosciences, Paris-Lodron University Salzburg, Salzburg, Austria; Institute of Functional Anatomy, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Lukas Schartel
- Department of Biosciences, Paris-Lodron University Salzburg, Salzburg, Austria; Biocentre, Departments of Biology and Chemistry, Johannes Gutenberg University and Institute of Molecular Biology, Mainz, Germany
| | - Simon Pöschl
- Department of Biosciences, Paris-Lodron University Salzburg, Salzburg, Austria
| | - Peter Briza
- Department of Biosciences, Paris-Lodron University Salzburg, Salzburg, Austria
| | - Manuel Paschinger
- Department of Biosciences, Paris-Lodron University Salzburg, Salzburg, Austria
| | - Kitti Boros
- Department of Biosciences, Paris-Lodron University Salzburg, Salzburg, Austria
| | - Thomas Klaus Felder
- Department of Laboratory Medicine, Paracelsus Medical University, Salzburg, Austria
| | - Herbert Wimmer
- Department of Biosciences, Paris-Lodron University Salzburg, Salzburg, Austria
| | - Jutta Duschl
- Department of Biosciences, Paris-Lodron University Salzburg, Salzburg, Austria
| | - Mark Rinnerthaler
- Department of Biosciences, Paris-Lodron University Salzburg, Salzburg, Austria.
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3
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Nisticò C, Chiarella E. An Overview on Lipid Droplets Accumulation as Novel Target for Acute Myeloid Leukemia Therapy. Biomedicines 2023; 11:3186. [PMID: 38137407 PMCID: PMC10741140 DOI: 10.3390/biomedicines11123186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Revised: 11/28/2023] [Accepted: 11/28/2023] [Indexed: 12/24/2023] Open
Abstract
Metabolic reprogramming is a key alteration in tumorigenesis. In cancer cells, changes in metabolic fluxes are required to cope with large demands on ATP, NADPH, and NADH, as well as carbon skeletons. In particular, dysregulation in lipid metabolism ensures a great energy source for the cells and sustains cell membrane biogenesis and signaling molecules, which are necessary for tumor progression. Increased lipid uptake and synthesis results in intracellular lipid accumulation as lipid droplets (LDs), which in recent years have been considered hallmarks of malignancies. Here, we review current evidence implicating the biogenesis, composition, and functions of lipid droplets in acute myeloid leukemia (AML). This is an aggressive hematological neoplasm originating from the abnormal expansion of myeloid progenitor cells in bone marrow and blood and can be fatal within a few months without treatment. LD accumulation positively correlates with a poor prognosis in AML since it involves the activation of oncogenic signaling pathways and cross-talk between the tumor microenvironment and leukemic cells. Targeting altered LD production could represent a potential therapeutic strategy in AML. From this perspective, we discuss the main inhibitors tested in in vitro AML cell models to block LD formation, which is often associated with leukemia aggressiveness and which may find clinical application in the future.
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Affiliation(s)
- Clelia Nisticò
- Candiolo Cancer Institute, FPO-IRCCS, Department of Oncology, University of Torino, 10124 Candiolo, Italy
| | - Emanuela Chiarella
- Laboratory of Molecular Haematopoiesis and Stem Cell Biology, Department of Experimental and Clinical Medicine, University “Magna Græcia”, 88100 Catanzaro, Italy
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4
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Delmas D, Cotte AK, Connat JL, Hermetet F, Bouyer F, Aires V. Emergence of Lipid Droplets in the Mechanisms of Carcinogenesis and Therapeutic Responses. Cancers (Basel) 2023; 15:4100. [PMID: 37627128 PMCID: PMC10452604 DOI: 10.3390/cancers15164100] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 07/04/2023] [Accepted: 08/09/2023] [Indexed: 08/27/2023] Open
Abstract
Cancer shares common risk factors with cardiovascular diseases such as dyslipidemia, obesity and inflammation. In both cases, dysregulations of lipid metabolism occur, and lipid vesicles emerge as important factors that can influence carcinogenesis. In this review, the role of different lipids known to be involved in cancer and its response to treatments is detailed. In particular, lipid droplets (LDs), initially described for their role in lipid storage, exert multiple functions, from the physiological prevention of LD coalescence and regulation of endoplasmic reticulum homeostasis to pathological involvement in tumor progression and aggressiveness. Analysis of LDs highlights the importance of phosphatidylcholine metabolism and the diversity of lipid synthesis enzymes. In many cancers, the phosphatidylcholine pathways are disrupted, modifying the expression of genes coding for metabolic enzymes. Tumor microenvironment conditions, such as hypoxia, different types of stress or inflammatory conditions, are also important determinants of LD behavior in cancer cells. Therefore, LDs represent therapeutic targets in cancer, and many lipid mediators have emerged as potential biomarkers for cancer onset, progression, and/or resistance.
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Affiliation(s)
- Dominique Delmas
- UFR of Heatlh Sciences, Université de Bourgogne, 21000 Dijon, France; (A.K.C.); (J.-L.C.); (F.H.); (F.B.); (V.A.)
- INSERM Research Center U1231—Bioactive Molecules and Health Research Group, Cancer and Adaptive Immune Response Team, 21000 Dijon, France
- Centre de Lutte Contre le Cancer Georges François Leclerc, 21000 Dijon, France
| | - Alexia K. Cotte
- UFR of Heatlh Sciences, Université de Bourgogne, 21000 Dijon, France; (A.K.C.); (J.-L.C.); (F.H.); (F.B.); (V.A.)
- INSERM Research Center U1231—Bioactive Molecules and Health Research Group, Cancer and Adaptive Immune Response Team, 21000 Dijon, France
| | - Jean-Louis Connat
- UFR of Heatlh Sciences, Université de Bourgogne, 21000 Dijon, France; (A.K.C.); (J.-L.C.); (F.H.); (F.B.); (V.A.)
- INSERM Research Center U1231—Bioactive Molecules and Health Research Group, Cancer and Adaptive Immune Response Team, 21000 Dijon, France
| | - François Hermetet
- UFR of Heatlh Sciences, Université de Bourgogne, 21000 Dijon, France; (A.K.C.); (J.-L.C.); (F.H.); (F.B.); (V.A.)
- INSERM Research Center U1231—Bioactive Molecules and Health Research Group, Cancer and Adaptive Immune Response Team, 21000 Dijon, France
| | - Florence Bouyer
- UFR of Heatlh Sciences, Université de Bourgogne, 21000 Dijon, France; (A.K.C.); (J.-L.C.); (F.H.); (F.B.); (V.A.)
- INSERM Research Center U1231—Bioactive Molecules and Health Research Group, Cancer and Adaptive Immune Response Team, 21000 Dijon, France
| | - Virginie Aires
- UFR of Heatlh Sciences, Université de Bourgogne, 21000 Dijon, France; (A.K.C.); (J.-L.C.); (F.H.); (F.B.); (V.A.)
- INSERM Research Center U1231—Bioactive Molecules and Health Research Group, Cancer and Adaptive Immune Response Team, 21000 Dijon, France
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5
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Safi R, Sánchez-Álvarez M, Bosch M, Demangel C, Parton RG, Pol A. Defensive-lipid droplets: Cellular organelles designed for antimicrobial immunity. Immunol Rev 2023; 317:113-136. [PMID: 36960679 DOI: 10.1111/imr.13199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/25/2023]
Abstract
Microbes have developed many strategies to subvert host organisms, which, in turn, evolved several innate immune responses. As major lipid storage organelles of eukaryotes, lipid droplets (LDs) are an attractive source of nutrients for invaders. Intracellular viruses, bacteria, and protozoan parasites induce and physically interact with LDs, and the current view is that they "hijack" LDs to draw on substrates for host colonization. This dogma has been challenged by the recent demonstration that LDs are endowed with a protein-mediated antibiotic activity, which is upregulated in response to danger signals and sepsis. Dependence on host nutrients could be a generic "Achilles' heel" of intracellular pathogens and LDs a suitable chokepoint harnessed by innate immunity to organize a front-line defense. Here, we will provide a brief overview of the state of the conflict and discuss potential mechanisms driving the formation of the 'defensive-LDs' functioning as hubs of innate immunity.
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Affiliation(s)
- Rémi Safi
- Lipid Trafficking and Disease Group, Institut d'Investigacions Biomèdiques August Pi I Sunyer (IDIBAPS), Barcelona, Spain
- Josep Carreras Leukemia Research Institute, Barcelona, Spain
| | - Miguel Sánchez-Álvarez
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
- Instituto de Investigaciones Biomédicas Alberto Sols (IIB), Madrid, Spain
| | - Marta Bosch
- Lipid Trafficking and Disease Group, Institut d'Investigacions Biomèdiques August Pi I Sunyer (IDIBAPS), Barcelona, Spain
- Department of Biomedical Sciences, Faculty of Medicine, Universitat de Barcelona, Barcelona, Spain
| | - Caroline Demangel
- Immunobiology and Therapy Unit, Institut Pasteur, Université Paris Cité, INSERM U1224, Paris, France
| | - Robert G Parton
- Institute for Molecular Bioscience (IMB), Brisbane, Queensland, Australia
- Centre for Microscopy and Microanalysis (CMM), University of Queensland, Brisbane, Queensland, Australia
| | - Albert Pol
- Lipid Trafficking and Disease Group, Institut d'Investigacions Biomèdiques August Pi I Sunyer (IDIBAPS), Barcelona, Spain
- Department of Biomedical Sciences, Faculty of Medicine, Universitat de Barcelona, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
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6
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Hammoudeh N, Soukkarieh C, Murphy DJ, Hanano A. Mammalian lipid droplets: structural, pathological, immunological and anti-toxicological roles. Prog Lipid Res 2023; 91:101233. [PMID: 37156444 DOI: 10.1016/j.plipres.2023.101233] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 04/30/2023] [Accepted: 05/05/2023] [Indexed: 05/10/2023]
Abstract
Mammalian lipid droplets (LDs) are specialized cytosolic organelles consisting of a neutral lipid core surrounded by a membrane made up of a phospholipid monolayer and a specific population of proteins that varies according to the location and function of each LD. Over the past decade, there have been significant advances in the understanding of LD biogenesis and functions. LDs are now recognized as dynamic organelles that participate in many aspects of cellular homeostasis plus other vital functions. LD biogenesis is a complex, highly-regulated process with assembly occurring on the endoplasmic reticulum although aspects of the underpinning molecular mechanisms remain elusive. For example, it is unclear how many enzymes participate in the biosynthesis of the neutral lipid components of LDs and how this process is coordinated in response to different metabolic cues to promote or suppress LD formation and turnover. In addition to enzymes involved in the biosynthesis of neutral lipids, various scaffolding proteins play roles in coordinating LD formation. Despite their lack of ultrastructural diversity, LDs in different mammalian cell types are involved in a wide range of biological functions. These include roles in membrane homeostasis, regulation of hypoxia, neoplastic inflammatory responses, cellular oxidative status, lipid peroxidation, and protection against potentially toxic intracellular fatty acids and lipophilic xenobiotics. Herein, the roles of mammalian LDs and their associated proteins are reviewed with a particular focus on their roles in pathological, immunological and anti-toxicological processes.
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Affiliation(s)
- Nour Hammoudeh
- Department of Animal Biology, Faculty of Sciences, University of Damascus, Damascus, Syria
| | - Chadi Soukkarieh
- Department of Animal Biology, Faculty of Sciences, University of Damascus, Damascus, Syria
| | - Denis J Murphy
- School of Applied Sciences, University of South Wales, Pontypridd, CF37 1DL, Wales, United Kingdom..
| | - Abdulsamie Hanano
- Department of Molecular Biology and Biotechnology, Atomic Energy Commission of Syria (AECS), P.O. Box 6091, Damascus, Syria..
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7
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Bosch M, Pol A. Eukaryotic lipid droplets: metabolic hubs, and immune first responders. Trends Endocrinol Metab 2022; 33:218-229. [PMID: 35065875 DOI: 10.1016/j.tem.2021.12.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 12/23/2021] [Accepted: 12/23/2021] [Indexed: 12/18/2022]
Abstract
As major eukaryotic lipid storage organelles, lipid droplets (LDs) are metabolic hubs coordinating energy flux and building block distribution. Infectious pathogens often promote accumulation and physically interact with LDs. The most accepted view is that host LDs are hijacked by invaders to draw on nutrients for host colonisation. However, unique traits such as biogenesis plasticity, dynamic proteome, signalling capacity, and ability to interact with other organelles endow LDs with competencies to face complex biological challenges. Here, we focus on published data suggesting that LDs are not usurped organelles but innate immunity first responders. By comparison with analogous mechanisms activated on LDs in nutrient-poor environments, our review supports the hypothesis that host LDs actively participate in immunometabolism, immune signalling, and microbial killing.
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Affiliation(s)
- Marta Bosch
- Lipid Trafficking and Disease Group, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain; Department of Biomedical Sciences, Faculty of Medicine, Universitat de Barcelona, 08036 Barcelona, Spain.
| | - Albert Pol
- Lipid Trafficking and Disease Group, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain; Department of Biomedical Sciences, Faculty of Medicine, Universitat de Barcelona, 08036 Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010, Barcelona
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8
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Mura A, Moriel-Carretero M. Lack of evidence for condensin or cohesin sequestration on lipid droplets with packing defects. MICROPUBLICATION BIOLOGY 2021; 2021. [PMID: 34746685 PMCID: PMC8569452 DOI: 10.17912/micropub.biology.000497] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 10/27/2021] [Accepted: 10/31/2021] [Indexed: 11/06/2022]
Abstract
Lipid droplets (LD) are organelles born from the endoplasmic reticulum that store fats and sterols in an apolar manner both as an energy reservoir and for protective purposes. The LD is delimited by a phospholipid monolayer covered by a rich proteome that dynamically evolves depending on the nutritional, genetic, pharmacological and environmental cues. Some of these contexts lead to discontinuities in the phospholipid monolayer, termed "packing defects", that expose LD hydrophobic contents to the surrounding water environment. This triggers the unscheduled binding of proteins with affinity for hydrophobic surfaces, a thermodynamically favorable reaction. We have raised in the past the concern that this titration includes proteins with important roles in the nucleus, which entails a risk of genome instability. Analysis of previously published LD proteomes isolated from cells lacking the transcription factor Ino2p, a prototype of LD bearing packing defects, made us concentrate on two subunits of the cohesin (Smc1p and Smc3p) and one of the condensin (Smc2p) complexes, both essential to promote genome integrity by structuring chromosomes. We report that, in disagreement with the proteomic data, we find no evidence of titration of condensin or cohesin subunits onto LD in ino2∆ cells. Importantly, during our analysis to label LD, we discovered that the addition of the widely used vital dye AUTODOTTM, which emits in the blue range of the spectrum, leads, specifically in ino2∆, to the artefactual emission of signals in the green channel. We therefore take the opportunity to warn the community of this undesirable aspect when using this dye.
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Affiliation(s)
- Anaïs Mura
- Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), Université de Montpellier, Centre National de la Recherche Scientifique, 34293 Montpellier CEDEX 05, France
| | - María Moriel-Carretero
- Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), Université de Montpellier, Centre National de la Recherche Scientifique, 34293 Montpellier CEDEX 05, France
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9
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Royo-García A, Courtois S, Parejo-Alonso B, Espiau-Romera P, Sancho P. Lipid droplets as metabolic determinants for stemness and chemoresistance in cancer. World J Stem Cells 2021; 13:1307-1317. [PMID: 34630864 PMCID: PMC8474722 DOI: 10.4252/wjsc.v13.i9.1307] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 05/13/2021] [Accepted: 08/18/2021] [Indexed: 02/06/2023] Open
Abstract
Previously regarded as simple fat storage particles, new evidence suggests that lipid droplets (LDs) are dynamic and functional organelles involved in key cellular processes such as membrane biosynthesis, lipid metabolism, cell signalling and inflammation. Indeed, an increased LD content is one of the most apparent features resulting from lipid metabolism reprogramming necessary to support the basic functions of cancer cells. LDs have been associated to different cellular processes involved in cancer progression and aggressiveness, such as tumorigenicity, invasion and metastasis, as well as chemoresistance. Interestingly, all of these processes are controlled by a subpopulation of highly aggressive tumoral cells named cancer stem cells (CSCs), suggesting that LDs may be fundamental elements for stemness in cancer. Considering the key role of CSCs on chemoresistance and disease relapse, main factors of therapy failure, the design of novel therapeutic approaches targeting these cells may be the only chance for long-term survival in cancer patients. In this sense, their biology and functional properties render LDs excellent candidates for target discovery and design of combined therapeutic strategies. In this review, we summarise the current knowledge identifying LDs and CSCs as main contributors to cancer aggressiveness, metastasis and chemoresistance.
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Affiliation(s)
- Alba Royo-García
- Hospital Universitario Miguel Servet, IIS Aragón, Zaragoza 50009, Spain
| | - Sarah Courtois
- Hospital Universitario Miguel Servet, IIS Aragón, Zaragoza 50009, Spain
| | | | | | - Patricia Sancho
- Hospital Universitario Miguel Servet, IIS Aragón, Zaragoza 50009, Spain
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10
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Abstract
Embryonic stem (ES) cells, derived from the inner cell mass of a blastocyst, are believed to pluripotent cells and give rise to embryonic, but not extraembryonic, tissues. In mice, totipotent 2-cell stage embryo-like (2-cell-like) cells, which are identified by reactivation of murine endogenous retrovirus with leucin transfer RNA primer (MuERV-L), arise at a very few frequencies in ES cell cultures. Here, we found that a lipid droplet forms during the transition from ES cells to 2-cell-like cells, and we propose that 2-cell-like cells utilize a unique energy storage and production pathway.
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Affiliation(s)
- Asuka Furuta
- Laboratory for Epigenetic Regulation, Department of Bio-Science, Nagahama Institute of Bio-Science and Technology, Shiga 526-0829, Japan
| | - Toshinobu Nakamura
- Laboratory for Epigenetic Regulation, Department of Bio-Science, Nagahama Institute of Bio-Science and Technology, Shiga 526-0829, Japan
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11
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Sheneman L, Stephanopoulos G, Vasdekis AE. Deep learning classification of lipid droplets in quantitative phase images. PLoS One 2021; 16:e0249196. [PMID: 33819277 PMCID: PMC8021159 DOI: 10.1371/journal.pone.0249196] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 03/12/2021] [Indexed: 12/15/2022] Open
Abstract
We report the application of supervised machine learning to the automated classification of lipid droplets in label-free, quantitative-phase images. By comparing various machine learning methods commonly used in biomedical imaging and remote sensing, we found convolutional neural networks to outperform others, both quantitatively and qualitatively. We describe our imaging approach, all implemented machine learning methods, and their performance with respect to computational efficiency, required training resources, and relative method performance measured across multiple metrics. Overall, our results indicate that quantitative-phase imaging coupled to machine learning enables accurate lipid droplet classification in single living cells. As such, the present paradigm presents an excellent alternative of the more common fluorescent and Raman imaging modalities by enabling label-free, ultra-low phototoxicity, and deeper insight into the thermodynamics of metabolism of single cells.
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Affiliation(s)
- Luke Sheneman
- Northwest Knowledge Network, University of Idaho, Moscow, Idaho, United States of America
| | - Gregory Stephanopoulos
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Andreas E. Vasdekis
- Department of Physics, University of Idaho, Moscow, Idaho, United States of America
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12
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Kumanski S, Viart BT, Kossida S, Moriel-Carretero M. Lipid Droplets Are a Physiological Nucleoporin Reservoir. Cells 2021; 10:472. [PMID: 33671805 PMCID: PMC7926788 DOI: 10.3390/cells10020472] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 02/09/2021] [Accepted: 02/19/2021] [Indexed: 12/13/2022] Open
Abstract
Lipid Droplets (LD) are dynamic organelles that originate in the Endoplasmic Reticulum and mostly bud off toward the cytoplasm, where they store neutral lipids for energy and protection purposes. LD also have diverse proteins on their surface, many of which are necessary for the their correct homeostasis. However, these organelles also act as reservoirs of proteins that can be made available elsewhere in the cell. In this sense, they act as sinks that titrate key regulators of many cellular processes. Among the specialized factors that reside on cytoplasmic LD are proteins destined for functions in the nucleus, but little is known about them and their impact on nuclear processes. By screening for nuclear proteins in publicly available LD proteomes, we found that they contain a subset of nucleoporins from the Nuclear Pore Complex (NPC). Exploring this, we demonstrate that LD act as a physiological reservoir, for nucleoporins, that impacts the conformation of NPCs and hence their function in nucleo-cytoplasmic transport, chromatin configuration, and genome stability. Furthermore, our in silico modeling predicts a role for LD-released fatty acids in regulating the transit of nucleoporins from LD through the cytoplasm and to nuclear pores.
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Affiliation(s)
- Sylvain Kumanski
- Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), Université de Montpellier, Centre National de la Recherche Scientifique, 34293 Montpellier CEDEX 05, France;
| | - Benjamin T. Viart
- International ImMunoGeneTics Information System (IMGT®), Institut de Génétique Humaine (IGH), Université de Montpellier, Centre National de la Recherche Scientifique, 34396 Montpellier CEDEX 05, France; (B.T.V.); (S.K.)
| | - Sofia Kossida
- International ImMunoGeneTics Information System (IMGT®), Institut de Génétique Humaine (IGH), Université de Montpellier, Centre National de la Recherche Scientifique, 34396 Montpellier CEDEX 05, France; (B.T.V.); (S.K.)
| | - María Moriel-Carretero
- Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), Université de Montpellier, Centre National de la Recherche Scientifique, 34293 Montpellier CEDEX 05, France;
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Snuggs JW, Tessier S, Bunning RAB, Shapiro IM, Risbud MV, Le Maitre CL. TonEBP regulates the hyperosmotic expression of aquaporin 1 and 5 in the intervertebral disc. Sci Rep 2021; 11:3164. [PMID: 33542263 PMCID: PMC7862284 DOI: 10.1038/s41598-021-81838-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 12/22/2020] [Indexed: 01/30/2023] Open
Abstract
The central region of the intervertebral disc (IVD) is rich in proteoglycans, leading to a hyperosmotic environment, which fluctuates with daily loading. The cells of the nucleus pulposus (NP cells) have adapted to this environment via the function of tonicity enhancer binding protein (TonEBP), and NP cells have been shown to express several water channels known as aquaporins (AQP). We have previously shown that AQP1 and 5 decrease during IVD degeneration. Here, the regulation of AQP1 and 5 by hyperosmotic conditions and the role of TonEBP in this regulation was investigated. AQP1 and 5 gene expression was upregulated by hyperosmotic conditions mimicking the osmolality of the healthy IVD, which was abrogated by TonEBP knockdown. Furthermore, AQP1 and 5 immunopositivity was significantly reduced in TonEBPΔ/Δ E17.5 mice when compared with wildtype controls, indicating in vivo expression of AQP1 and 5 is controlled at least in part by TonEBP. This hyperosmotic regulation of AQP1 and 5 could help to explain the decreased AQP1 and 5 expression during degeneration, when the osmolality of the NP decreases. Together this data suggests that TonEBP-regulated osmo-adaptation may be disrupted during IVD degeneration when the expression of both AQPs is reduced.
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Affiliation(s)
- J. W. Snuggs
- grid.5884.10000 0001 0303 540XBiomolecular Sciences Research Centre, Sheffield Hallam University, City Campus, Howard Street, Sheffield, S1 1WB UK
| | - S. Tessier
- grid.265008.90000 0001 2166 5843Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA USA
| | - R. A. B. Bunning
- grid.5884.10000 0001 0303 540XBiomolecular Sciences Research Centre, Sheffield Hallam University, City Campus, Howard Street, Sheffield, S1 1WB UK
| | - I. M. Shapiro
- grid.265008.90000 0001 2166 5843Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA USA ,grid.265008.90000 0001 2166 5843Graduate Program in Cell Biology and Regenerative Medicine, Thomas Jefferson University, Philadelphia, PA USA
| | - M. V. Risbud
- grid.265008.90000 0001 2166 5843Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA USA ,grid.265008.90000 0001 2166 5843Graduate Program in Cell Biology and Regenerative Medicine, Thomas Jefferson University, Philadelphia, PA USA
| | - C. L. Le Maitre
- grid.5884.10000 0001 0303 540XBiomolecular Sciences Research Centre, Sheffield Hallam University, City Campus, Howard Street, Sheffield, S1 1WB UK
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14
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Doner NM, Seay D, Mehling M, Sun S, Gidda SK, Schmitt K, Braus GH, Ischebeck T, Chapman KD, Dyer JM, Mullen RT. Arabidopsis thaliana EARLY RESPONSIVE TO DEHYDRATION 7 Localizes to Lipid Droplets via Its Senescence Domain. FRONTIERS IN PLANT SCIENCE 2021; 12:658961. [PMID: 33936146 PMCID: PMC8079945 DOI: 10.3389/fpls.2021.658961] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 03/23/2021] [Indexed: 05/09/2023]
Abstract
Lipid droplets (LDs) are neutral-lipid-containing organelles found in all kingdoms of life and are coated with proteins that carry out a vast array of functions. Compared to mammals and yeast, relatively few LD proteins have been identified in plants, particularly those associated with LDs in vegetative (non-seed) cell types. Thus, to better understand the cellular roles of LDs in plants, a more comprehensive inventory and characterization of LD proteins is required. Here, we performed a proteomics analysis of LDs isolated from drought-stressed Arabidopsis leaves and identified EARLY RESPONSIVE TO DEHYDRATION 7 (ERD7) as a putative LD protein. mCherry-tagged ERD7 localized to both LDs and the cytosol when ectopically expressed in plant cells, and the protein's C-terminal senescence domain (SD) was both necessary and sufficient for LD targeting. Phylogenetic analysis revealed that ERD7 belongs to a six-member family in Arabidopsis that, along with homologs in other plant species, is separated into two distinct subfamilies. Notably, the SDs of proteins from each subfamily conferred targeting to either LDs or mitochondria. Further, the SD from the ERD7 homolog in humans, spartin, localized to LDs in plant cells, similar to its localization in mammals; although, in mammalian cells, spartin also conditionally localizes to other subcellular compartments, including mitochondria. Disruption of ERD7 gene expression in Arabidopsis revealed no obvious changes in LD numbers or morphology under normal growth conditions, although this does not preclude a role for ERD7 in stress-induced LD dynamics. Consistent with this possibility, a yeast two-hybrid screen using ERD7 as bait identified numerous proteins involved in stress responses, including some that have been identified in other LD proteomes. Collectively, these observations provide new insight to ERD7 and the SD-containing family of proteins in plants and suggest that ERD7 may be involved in functional aspects of plant stress response that also include localization to the LD surface.
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Affiliation(s)
- Nathan M. Doner
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - Damien Seay
- United States Department of Agriculture, US Arid-Land Agricultural Research Center, Agriculture Research Service, Maricopa, AZ, United States
| | - Marina Mehling
- United States Department of Agriculture, US Arid-Land Agricultural Research Center, Agriculture Research Service, Maricopa, AZ, United States
| | - Siqi Sun
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Satinder K. Gidda
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - Kerstin Schmitt
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Gerhard H. Braus
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Till Ischebeck
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Kent D. Chapman
- BioDiscovery Institute and Department of Biological Sciences, University of North Texas, Denton, TX, United States
| | - John M. Dyer
- United States Department of Agriculture, US Arid-Land Agricultural Research Center, Agriculture Research Service, Maricopa, AZ, United States
| | - Robert T. Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
- *Correspondence: Robert T. Mullen,
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15
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Subedi NR, Jung PS, Bredeweg EL, Nemati S, Baker SE, Christodoulides DN, Vasdekis AE. Integrative quantitative-phase and airy light-sheet imaging. Sci Rep 2020; 10:20150. [PMID: 33214600 PMCID: PMC7678854 DOI: 10.1038/s41598-020-76730-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 10/30/2020] [Indexed: 01/05/2023] Open
Abstract
Light-sheet microscopy enables considerable speed and phototoxicity gains, while quantitative-phase imaging confers label-free recognition of cells and organelles, and quantifies their number-density that, thermodynamically, is more representative of metabolism than size. Here, we report the fusion of these two imaging modalities onto a standard inverted microscope that retains compatibility with microfluidics and open-source software for image acquisition and processing. An accelerating Airy-beam light-sheet critically enabled imaging areas that were greater by more than one order of magnitude than a Gaussian beam illumination and matched exactly those of quantitative-phase imaging. Using this integrative imaging system, we performed a demonstrative multivariate investigation of live-cells in microfluidics that unmasked that cellular noise can affect the compartmental localization of metabolic reactions. We detail the design, assembly, and performance of the integrative imaging system, and discuss potential applications in biotechnology and evolutionary biology.
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Affiliation(s)
- N R Subedi
- Department of Physics, University of Idaho, Moscow, ID, 83844, USA
| | - P S Jung
- CREOL-The College of Optics and Photonics, University of Central Florida, Orlando, FL, 32816-2700, USA
- Faculty of Physics, Warsaw University of Technology, Warsaw, Poland
| | - E L Bredeweg
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
| | - S Nemati
- Department of Physics, University of Idaho, Moscow, ID, 83844, USA
| | - S E Baker
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
| | - D N Christodoulides
- CREOL-The College of Optics and Photonics, University of Central Florida, Orlando, FL, 32816-2700, USA
| | - A E Vasdekis
- Department of Physics, University of Idaho, Moscow, ID, 83844, USA.
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16
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Friend or Foe: Lipid Droplets as Organelles for Protein and Lipid Storage in Cellular Stress Response, Aging and Disease. Molecules 2020; 25:molecules25215053. [PMID: 33143278 PMCID: PMC7663626 DOI: 10.3390/molecules25215053] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 10/20/2020] [Accepted: 10/22/2020] [Indexed: 02/06/2023] Open
Abstract
Lipid droplets (LDs) were considered as a mere lipid storage organelle for a long time. Recent evidence suggests that LDs are in fact distinct and dynamic organelles with a specialized proteome and functions in many cellular roles. As such, LDs contribute to cellular signaling, protein and lipid homeostasis, metabolic diseases and inflammation. In line with the multitude of functions, LDs interact with many cellular organelles including mitochondria, peroxisomes, lysosomes, the endoplasmic reticulum and the nucleus. LDs are highly mobile and dynamic organelles and impaired motility disrupts the interaction with other organelles. The reduction of interorganelle contacts results in a multitude of pathophysiologies and frequently in neurodegenerative diseases. Contacts not only supply lipids for β-oxidation in mitochondria and peroxisomes, but also may include the transfer of toxic lipids as well as misfolded and harmful proteins to LDs. Furthermore, LDs assist in the removal of protein aggregates when severe proteotoxic stress overwhelms the proteasomal system. During imbalance of cellular lipid homeostasis, LDs also support cellular detoxification. Fine-tuning of LD function is of crucial importance and many diseases are associated with dysfunctional LDs. We summarize the current understanding of LDs and their interactions with organelles, providing a storage site for harmful proteins and lipids during cellular stress, aging inflammation and various disease states.
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17
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Samuel AZ, Miyaoka R, Ando M, Gaebler A, Thiele C, Takeyama H. Molecular profiling of lipid droplets inside HuH7 cells with Raman micro-spectroscopy. Commun Biol 2020; 3:372. [PMID: 32651434 PMCID: PMC7351753 DOI: 10.1038/s42003-020-1100-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 06/22/2020] [Indexed: 02/07/2023] Open
Abstract
Raman imaging has become an attractive technology in molecular biology because of its ability to detect multiple molecular components simultaneously without labeling. Two major limitations in accurately accounting for spectral features, viz., background removal and spectral unmixing, have been overcome by employing a modified and effective routine in multivariate curve resolution (MCR). With our improved strategy, we have spectrally isolated seven structurally specific biomolecules without any post-acquisition spectral treatments. Consequently, the isolated intensity profiles reflected concentrations of corresponding biomolecules with high statistical accuracy. Our study reveals the changes in the molecular composition of lipid droplets (LDs) inside HuH7 cells and its relation to the physiological state of the cell. Further, we show that the accurate separation of spectral components permits analysis of structural modification of molecules after cellular uptake. A detailed discussion is presented to highlight the potential of Raman spectroscopy with MCR in semi-quantitative molecular profiling of living cells. Samuel, Miyaoka et al. investigate the changes in the molecular composition of lipid droplets inside HuH7 cells and its relation to the physiological state of the cell, using Raman spectroscopy and multivariate curve resolution. This study underscores the importance of separation of spectral components in semi-quantitative molecular profiling of living cells.
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Affiliation(s)
- Ashok Zachariah Samuel
- Research Organization for Nano & Life Innovation, Waseda University, 513, Wasedatsurumaki-cho, Shinjuku-ku, Tokyo, 162-0041, Japan
| | - Rimi Miyaoka
- Department of Life Science and Medical Bioscience, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480, Japan
| | - Masahiro Ando
- Research Organization for Nano & Life Innovation, Waseda University, 513, Wasedatsurumaki-cho, Shinjuku-ku, Tokyo, 162-0041, Japan.,JST, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan
| | - Anne Gaebler
- LIMES Life and Medical Sciences Institute, University of Bonn, Carl-Troll-Strasse 31, 53115, Bonn, Germany
| | - Christoph Thiele
- LIMES Life and Medical Sciences Institute, University of Bonn, Carl-Troll-Strasse 31, 53115, Bonn, Germany
| | - Haruko Takeyama
- Department of Life Science and Medical Bioscience, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480, Japan. .,Computational Bio Big-Data Open Innovation Laboratory, National Institute of Advanced Industrial Science and Technology and Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo, 169-8555, Japan. .,Insituture for Advances Research of Biosystem Dynamics, Waseda Research Institute for Science and Engineering, Tokyo, Japan.
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18
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Jin C, Yuan P. Implications of lipid droplets in lung cancer: Associations with drug resistance. Oncol Lett 2020; 20:2091-2104. [PMID: 32782526 PMCID: PMC7399769 DOI: 10.3892/ol.2020.11769] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 05/27/2020] [Indexed: 12/12/2022] Open
Abstract
Cancer cells usually show different metabolic patterns compared with healthy cells due to the reprogramming of metabolic processes. The process of lipid metabolism undergoes notable changes, leading to the accumulation of lipid droplets in cells. Additionally, this phenotype is considered an important marker of cancer cells. Lipid droplets are a highly dynamic type of organelle in the cell, which is composed of a neutral lipid core, a monolayer phospholipid membrane and lipid droplet-related proteins. Lipid droplets are involved in several biological processes, including cell proliferation, apoptosis, lipid metabolism, stress, immunity, signal transduction and protein trafficking. Epidermal growth factor receptor (EGFR)-activating mutations are currently the most effective therapeutic targets for non-small cell lung cancer. Several EGFR tyrosine kinase inhibitors (EGFR-TKIs) that target these mutations, including gefitinib, erlotinib, afatinib and osimertinib, have been widely used clinically. However, the development of acquired resistance has a major impact on the efficacy of these drugs. A number of previous studies have reported that the expression of lipid droplets in the tumor tissues of patients with lung cancer are elevated, whereas the association between elevated numbers of lipid droplets and drug resistance has received little attention. The present review describes the potential association between lipid droplets and drug resistance. Furthermore, the mechanisms and implications of lipid droplet accumulation in cancer cells are analyzed, as wells as the mechanism by which lipid droplets suppress endoplasmic reticulum stress and apoptosis, which are essential for the development and treatment of lung cancer.
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Affiliation(s)
- Chunlai Jin
- Department of Surgery, First People's Hospital of Jinan, Jinan, Shandong 250011, P.R. China
| | - Peng Yuan
- Department of Surgery, First People's Hospital of Jinan, Jinan, Shandong 250011, P.R. China
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19
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Jarc E, Petan T. A twist of FATe: Lipid droplets and inflammatory lipid mediators. Biochimie 2020; 169:69-87. [DOI: 10.1016/j.biochi.2019.11.016] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 11/25/2019] [Indexed: 12/14/2022]
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20
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Abstract
Lipid droplets have a unique structure among organelles consisting of a dense hydrophobic core of neutral lipids surrounded by a single layer of phospholipids decorated with various proteins. Often labeled merely as passive fat storage repositories, they in fact have a remarkably dynamic life cycle. Being formed within the endoplasmic reticulum membrane, lipid droplets rapidly grow, shrink, traverse the cytosol, and engage in contacts with other organelles to exchange proteins and lipids. Their lipid and protein composition changes dynamically in response to cellular states and nutrient availability. Remarkably, their biogenesis is induced when cells experience various forms of nutrient, energy, and redox imbalances, including lipid excess and complete nutrient deprivation. Cancer cells are continuously exposed to nutrient and oxygen fluctuations and have the capacity to switch between alternative nutrient acquisition and metabolic pathways in order to strive even during severe stress. Their supply of lipids is ensured by a series of nutrient uptake and scavenging mechanisms, upregulation of de novo lipid synthesis, repurposing of their structural lipids via enzymatic remodeling, or lipid recycling through autophagy. Importantly, most of these pathways of lipid acquisition converge at lipid droplets, which combine different lipid fluxes and control their usage based on specific cellular needs. It is thus not surprising that lipid droplet breakdown is an elaborately regulated process that occurs via a complex interplay of neutral lipases and autophagic degradation. Cancer cells employ lipid droplets to ensure energy production and redox balance, modulate autophagy, drive membrane synthesis, and control its composition, thereby minimizing stress and fostering tumor progression. As regulators of (poly)unsaturated fatty acid trafficking, lipid droplets are also emerging as modulators of lipid peroxidation and sensitivity to ferroptosis. Clearly, dysregulated lipid droplet turnover may also be detrimental to cancer cells, which should provide potential therapeutic opportunities in the future. In this review, we explore how lipid droplets consolidate lipid acquisition and trafficking pathways in order to match lipid supply with the requirements for cancer cell survival, growth, and metastasis.
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21
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Jarc E, Petan T. Lipid Droplets and the Management of Cellular Stress. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2019; 92:435-452. [PMID: 31543707 PMCID: PMC6747940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Lipid droplets are cytosolic fat storage organelles present in most eukaryotic cells. Long regarded merely as inert fat reservoirs, they are now emerging as major regulators of cellular metabolism. They act as hubs that coordinate the pathways of lipid uptake, distribution, storage, and use in the cell. Recent studies have revealed that they are also essential components of the cellular stress response. One of the hallmark characteristics of lipid droplets is their capacity to buffer excess lipids and to finely tune their subsequent release based on specific cellular requirements. This simple feature of lipid droplet biology, buffering and delayed release of lipids, forms the basis for their pleiotropic roles in the cellular stress response. In stressed cells, lipid droplets maintain energy and redox homeostasis and protect against lipotoxicity by sequestering toxic lipids into their neutral lipid core. Their mobility and dynamic interactions with mitochondria enable an efficient delivery of fatty acids for optimal energy production. Lipid droplets are also involved in the maintenance of membrane and organelle homeostasis by regulating membrane composition, preventing lipid peroxidation and removing damaged proteins and lipids. Finally, they also engage in a symbiotic relationship with autophagy and act as reservoirs of bioactive lipids that regulate inflammation and immunity. Thus, lipid droplets are central managers of lipid metabolism that function as safeguards against various types of cellular stress.
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Affiliation(s)
- Eva Jarc
- Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, Ljubljana, Slovenia,Jožef Stefan International Postgraduate School, Ljubljana, Slovenia
| | - Toni Petan
- Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, Ljubljana, Slovenia,To whom all correspondence should be addressed: Toni Petan, Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana, Slovenia; Tel: +386 1 477 3713, Fax: +386 1 477 3984,
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22
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Howie D, Ten Bokum A, Cobbold SP, Yu Z, Kessler BM, Waldmann H. A Novel Role for Triglyceride Metabolism in Foxp3 Expression. Front Immunol 2019; 10:1860. [PMID: 31456800 PMCID: PMC6701200 DOI: 10.3389/fimmu.2019.01860] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Accepted: 07/23/2019] [Indexed: 12/17/2022] Open
Abstract
Lipid metabolism plays a key role in many cellular processes. We show here that regulatory T cells have enhanced lipid storage within subcellular lipid droplets (LD). They also express elevated amounts of both isoforms of diacylglycerol acyl transferase (DGAT1 & 2), enzymes required for the terminal step of triacylglycerol synthesis. In regulatory T-cells (Tregs), the conversion of diacylglycerols to triacylglycerols serves two additional purposes other than lipid storage. First, we demonstrate that it protects T cells from the toxic effects of saturated long chain fatty acids. Second, we show that Triglyceride formation is essential for limiting activation of protein kinase C via free diacyl glycerol moieties. Inhibition of DGAT1 resulted in elevated active PKC and nuclear NFKB, as well as impaired Foxp3 induction in response to TGFβ. Thus, Tregs utilize a positive feedback mechanism to promote sustained expression of Foxp3 associated with control of LD formation.
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Affiliation(s)
- Duncan Howie
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Annemieke Ten Bokum
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Stephen Paul Cobbold
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Zhanru Yu
- Nuffield Department of Medicine, Target Discovery Institute, University of Oxford, Oxford, United Kingdom
| | - Benedikt M Kessler
- Nuffield Department of Medicine, Target Discovery Institute, University of Oxford, Oxford, United Kingdom
| | - Herman Waldmann
- Nuffield Department of Medicine, Target Discovery Institute, University of Oxford, Oxford, United Kingdom
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23
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Arbogast F, Gros F. Lymphocyte Autophagy in Homeostasis, Activation, and Inflammatory Diseases. Front Immunol 2018; 9:1801. [PMID: 30127786 PMCID: PMC6087746 DOI: 10.3389/fimmu.2018.01801] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 07/23/2018] [Indexed: 12/12/2022] Open
Abstract
Autophagy is a catabolic mechanism, allowing the degradation of cytoplasmic content via lysosomal activity. Several forms of autophagy are described in mammals. Macroautophagy leads to integration of cytoplasmic portions into vesicles named autophagosomes that ultimately fuse with lysosomes. Chaperone-mediated autophagy is in contrast the direct translocation of protein in lysosomes. Macroautophagy is central to lymphocyte homeostasis. Although its role is controversial in lymphocyte development and in naive cell survival, it seems particularly involved in the maintenance of certain lymphocyte subtypes. Its importance in memory B and T cells biology has recently emerged. Moreover, some effector cells like plasma cells rely on autophagy for survival. Autophagy is central to glucose and lipid metabolism, and to the maintenance of organelles like mitochondria and endoplasmic reticulum. In addition macroautophagy, or individual components of its machinery, are also actors in antigen presentation by B cells, a crucial step to receive help from T cells, this crosstalk favoring their final differentiation into memory or plasma cells. Autophagy is deregulated in several autoimmune or autoinflammatory diseases like systemic lupus erythematosus, rheumatoid arthritis, multiple sclerosis, and Crohn’s disease. Some treatments used in these pathologies impact autophagic activity, even if the causal link between autophagy regulation and the efficiency of the treatments has not yet been clearly established. In this review, we will first discuss the mechanisms linking autophagy to lymphocyte subtype survival and the signaling pathways involved. Finally, potential impacts of autophagy modulation in lymphocytes on the course of these diseases will be approached.
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Affiliation(s)
- Florent Arbogast
- CNRS UPR3572, Immunology, Immunopathology and Therapeutic Chemistry/Laboratory of Excellence MEDALIS, Institut de Biologie Moléculaire et Cellulaire, Strasbourg, France.,University of Strasbourg, Strasbourg, France
| | - Frédéric Gros
- CNRS UPR3572, Immunology, Immunopathology and Therapeutic Chemistry/Laboratory of Excellence MEDALIS, Institut de Biologie Moléculaire et Cellulaire, Strasbourg, France.,University of Strasbourg, Strasbourg, France
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24
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Johnson MR, Stephenson RA, Ghaemmaghami S, Welte MA. Developmentally regulated H2Av buffering via dynamic sequestration to lipid droplets in Drosophila embryos. eLife 2018; 7:36021. [PMID: 30044219 PMCID: PMC6089599 DOI: 10.7554/elife.36021] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 07/24/2018] [Indexed: 12/23/2022] Open
Abstract
Regulating nuclear histone balance is essential for survival, yet in early Drosophila melanogaster embryos many regulatory strategies employed in somatic cells are unavailable. Previous work had suggested that lipid droplets (LDs) buffer nuclear accumulation of the histone variant H2Av. Here, we elucidate the buffering mechanism and demonstrate that it is developmentally controlled. Using live imaging, we find that H2Av continuously exchanges between LDs. Our data suggest that the major driving force for H2Av accumulation in nuclei is H2Av abundance in the cytoplasm and that LD binding slows nuclear import kinetically, by limiting this cytoplasmic pool. Nuclear H2Av accumulation is indeed inversely regulated by overall buffering capacity. Histone exchange between LDs abruptly ceases during the midblastula transition, presumably to allow canonical regulatory mechanisms to take over. These findings provide a mechanistic basis for the emerging role of LDs as regulators of protein homeostasis and demonstrate that LDs can control developmental progression.
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Affiliation(s)
| | | | - Sina Ghaemmaghami
- Department of Biology, University of Rochester, Rochester, United States
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25
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Logan SM, Storey KB. Pro-inflammatory AGE-RAGE signaling is activated during arousal from hibernation in ground squirrel adipose. PeerJ 2018; 6:e4911. [PMID: 29888131 PMCID: PMC5991297 DOI: 10.7717/peerj.4911] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 05/15/2018] [Indexed: 12/26/2022] Open
Abstract
Background Inflammation is generally suppressed during hibernation, but select tissues (e.g. lung) have been shown to activate both antioxidant and pro-inflammatory pathways, particularly during arousal from torpor when breathing rates increase and oxidative metabolism fueling the rewarming process produces more reactive oxygen species. Brown and white adipose tissues are now understood to be major hubs for the regulation of immune and inflammatory responses, yet how these potentially damaging processes are regulated by fat tissues during hibernation has hardly been studied. The advanced glycation end-product receptor (RAGE) can induce pro-inflammatory responses when bound by AGEs (which are glycated and oxidized proteins, lipids, or nucleic acids) or damage associated molecular pattern molecules (DAMPs, which are released from dying cells). Methods Since gene expression and protein synthesis are largely suppressed during torpor, increases in AGE-RAGE pathway proteins relative to a euthermic control could suggest some role for these pro-inflammatory mediators during hibernation. This study determined how the pro-inflammatory AGE-RAGE signaling pathway is regulated at six major time points of the torpor-arousal cycle in brown and white adipose from a model hibernator, Ictidomys tridecemlineatus. Immunoblotting, RT-qPCR, and a competitive ELISA were used to assess the relative gene expression and protein levels of key regulators of the AGE-RAGE pathway during a hibernation bout. Results The results of this study revealed that RAGE is upregulated as animals arouse from torpor in both types of fat, but AGE and DAMP levels either remain unchanged or decrease. Downstream of the AGE-RAGE cascade, nfat5 was more highly expressed during arousal in brown adipose. Discussion An increase in RAGE protein levels and elevated mRNA levels of the downstream transcription factor nfat5 during arousal suggest the pro-inflammatory response is upregulated in adipose tissue of the hibernating ground squirrel. It is unlikely that this cascade is activated by AGEs or DAMPs. This research sheds light on how a fat-but-fit organism with highly regulated metabolism may control the pro-inflammatory AGE-RAGE pathway, a signaling cascade that is often dysregulated in other obese organisms.
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Affiliation(s)
- Samantha M Logan
- Institute of Biochemistry, Departments of Biology and Chemistry, Carleton University, Ottawa, Ontario, Canada
| | - Kenneth B Storey
- Institute of Biochemistry, Departments of Biology and Chemistry, Carleton University, Ottawa, Ontario, Canada
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26
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Luo WJ, Cheng TY, Wong KI, Fang WH, Liao KM, Hsieh YT, Su KY. Novel therapeutic drug identification and gene correlation for fatty liver disease using high-content screening: Proof of concept. Eur J Pharm Sci 2018; 121:106-117. [PMID: 29800612 DOI: 10.1016/j.ejps.2018.05.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 05/13/2018] [Accepted: 05/18/2018] [Indexed: 02/06/2023]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is a problem in obese people caused by increasing intake of high-calorie food such as fructose implicated in the elevated prevalence. It is necessary to identify novel drugs to develop effective therapies. In this study, we combined LOPAC® (The Library of Pharmacologically Active Compounds) and High-Content screening to identify compounds that significantly reduced intracellular lipid droplets (LD) after high fat medium (HFM) treatment. Among 1280 compounds, we identified 239 compounds that reduced LD by >50%. Of these, 17 maintained cell viability. Nine of them were selected for validation using normal primary hepatocytes, of which five compounds showed dose-dependent efficacy. Whole genome transcriptomic network analysis was performed to construct the underlying regulatory network. There were 831 (711 up-regulated and 120 down-regulated genes) and 3480 (2009 up-regulated and 1471 down-regulated genes) genes that showed a significant change (>2-fold; p < 0.05) after 12 and 24 h HFM treatment, respectively. Gene enrichment and pathway analysis showed several immune responses mediated by MIF, IL-17, TLR, and IL-6. These compounds modulate lipogenesis via GSK3β and CREB1, which is followed by an alteration in the expression of several downstream genes related to hepatocellular carcinoma and hepatitis. CREB1 is a core transcription factor and may be a potential therapeutic target for liver disease. In conclusion, this proof of concept provides a strategy for identifying novel drugs for treatment of fatty liver disease as well as elucidates their underlying mechanisms. This research provides opportunity for developing future pharmaceutical therapeutics.
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Affiliation(s)
- Wei-Jia Luo
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Ting-Yu Cheng
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Keng-Ieng Wong
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Woei-Horng Fang
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Keng-Mao Liao
- Genome and Systems Biology Degree Program, National Taiwan University and Academia Sinica, Taipei, Taiwan
| | - Yun-Ting Hsieh
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Kang-Yi Su
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan; Genome and Systems Biology Degree Program, National Taiwan University and Academia Sinica, Taipei, Taiwan; Center of Genomic Medicine, National Taiwan University, Taipei, Taiwan; Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan.
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27
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Ueno M, Suzuki J, Hirose M, Sato S, Imagawa M, Zenimaru Y, Takahashi S, Ikuyama S, Koizumi T, Konoshita T, Kraemer FB, Ishizuka T. Cardiac overexpression of perilipin 2 induces dynamic steatosis: prevention by hormone-sensitive lipase. Am J Physiol Endocrinol Metab 2017; 313:E699-E709. [PMID: 28851734 PMCID: PMC6415650 DOI: 10.1152/ajpendo.00098.2017] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 08/24/2017] [Accepted: 08/24/2017] [Indexed: 11/22/2022]
Abstract
Cardiac intracellular lipid accumulation (steatosis) is a pathophysiological phenomenon observed in starvation and diabetes mellitus. Perilipin 2 (PLIN2) is a lipid droplet (LD)-associated protein expressed in nonadipose tissues, including the heart. To explore the pathophysiological function of myocardial PLIN2, we generated transgenic (Tg) mice by cardiac-specific overexpression of PLIN2. Tg hearts showed accumulation of numerous small LDs associated with mitochondrial chains and high cardiac triacylglycerol (TAG) content [8-fold greater than wild-type (WT) mice]. Despite massive steatosis, cardiac uptake of glucose, fatty acids and VLDL, systolic function, and expression of metabolic genes were comparable in the two genotypes, and no morphological changes were observed by electron microscopy in the Tg hearts. Twenty-four hours of fasting markedly reduced steatosis in Tg hearts, whereas WT mice showed accumulation of LDs. Although activity of adipose triglyceride lipase in heart homogenate was comparable between WT and Tg mice, activity of hormone-sensitive lipase (HSL) was 40-50% less in Tg than WT mice under both feeding and fasting conditions, suggesting interference of PLIN2 with HSL. Mice generated through crossing of PLIN2-Tg mice and HSL-Tg mice showed cardiac-specific HSL overexpression and complete lack of steatosis. The results suggest that cardiac PLIN2 plays an important pathophysiological role in the development of dynamic steatosis and that the latter was prevented by upregulation of intracellular lipases, including HSL.
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Affiliation(s)
- Masami Ueno
- Third Department of Internal Medicine, University of Fukui, Faculty of Medical Sciences, Fukui, Japan
- Veterans Affairs Palo Alto Health Care System, Palo Alto, California; and
- Division of Endocrinology, Stanford University, Stanford, California
| | - Jinya Suzuki
- Third Department of Internal Medicine, University of Fukui, Faculty of Medical Sciences, Fukui, Japan;
| | | | - Satsuki Sato
- Third Department of Internal Medicine, University of Fukui, Faculty of Medical Sciences, Fukui, Japan
| | - Michiko Imagawa
- Third Department of Internal Medicine, University of Fukui, Faculty of Medical Sciences, Fukui, Japan
| | - Yasuo Zenimaru
- Third Department of Internal Medicine, University of Fukui, Faculty of Medical Sciences, Fukui, Japan
| | - Sadao Takahashi
- Division of Diabetes Medicine, Ageo Central General Hospital, Saitama, Japan
| | - Shoichiro Ikuyama
- Division of Endocrinology and Metabolism, Oita San-ai Medical Center, Oita, Japan
| | - Tsutomu Koizumi
- Research and Education Program for Life Science, University of Fukui, Faculty of Medical Sciences, Fukui, Japan
| | - Tadashi Konoshita
- Third Department of Internal Medicine, University of Fukui, Faculty of Medical Sciences, Fukui, Japan
| | - Fredric B Kraemer
- Veterans Affairs Palo Alto Health Care System, Palo Alto, California; and
- Division of Endocrinology, Stanford University, Stanford, California
| | - Tamotsu Ishizuka
- Third Department of Internal Medicine, University of Fukui, Faculty of Medical Sciences, Fukui, Japan
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28
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Zhang C, Liu P. The lipid droplet: A conserved cellular organelle. Protein Cell 2017; 8:796-800. [PMID: 28913786 PMCID: PMC5676593 DOI: 10.1007/s13238-017-0467-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 08/23/2017] [Indexed: 12/12/2022] Open
Abstract
The lipid droplet (LD) is a unique multi-functional organelle that contains a neutral lipid core covered with a phospholipid monolayer membrane. The LDs have been found in almost all organisms from bacteria to humans with similar shape. Several conserved functions of LDs have been revealed by recent studies, including lipid metabolism and trafficking, as well as nucleic acid binding and protection. We summarized these findings and proposed a hypothesis that the LD is a conserved organelle.
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Affiliation(s)
- Congyan Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Pingsheng Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China. .,University of Chinese Academy of Sciences, Beijing, 100049, China.
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29
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Johnson ZI, Doolittle AC, Snuggs JW, Shapiro IM, Le Maitre CL, Risbud MV. TNF-α promotes nuclear enrichment of the transcription factor TonEBP/NFAT5 to selectively control inflammatory but not osmoregulatory responses in nucleus pulposus cells. J Biol Chem 2017; 292:17561-17575. [PMID: 28842479 DOI: 10.1074/jbc.m117.790378] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 08/03/2017] [Indexed: 01/07/2023] Open
Abstract
Intervertebral disc degeneration (IDD) causes chronic back pain and is linked to production of proinflammatory molecules by nucleus pulposus (NP) and other disc cells. Activation of tonicity-responsive enhancer-binding protein (TonEBP)/NFAT5 by non-osmotic stimuli, including proinflammatory molecules, occurs in cells involved in immune response. However, whether inflammatory stimuli activate TonEBP in NP cells and whether TonEBP controls inflammation during IDD is unknown. We show that TNF-α, but not IL-1β or LPS, promoted nuclear enrichment of TonEBP protein. However, TNF-α-mediated activation of TonEBP did not cause induction of osmoregulatory genes. RNA sequencing showed that 8.5% of TNF-α transcriptional responses were TonEBP-dependent and identified genes regulated by both TNF-α and TonEBP. These genes were over-enriched in pathways and diseases related to inflammatory response and inhibition of matrix metalloproteases. Based on RNA-sequencing results, we further investigated regulation of novel TonEBP targets CXCL1, CXCL2, and CXCL3 TonEBP acted synergistically with TNF-α and LPS to induce CXCL1-proximal promoter activity. Interestingly, this regulation required a highly conserved NF-κB-binding site but not a predicted TonE, suggesting cross-talk between these two members of the Rel family. Finally, analysis of human NP tissue showed that TonEBP expression correlated with canonical osmoregulatory targets TauT/SLC6A6, SMIT/SLC5A3, and AR/AKR1B1, supporting in vitro findings that the inflammatory milieu during IDD does not interfere with TonEBP osmoregulation. In summary, whereas TonEBP participates in the proinflammatory response to TNF-α, therapeutic strategies targeting this transcription factor for treatment of disc disease must spare osmoprotective, prosurvival, and matrix homeostatic activities.
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Affiliation(s)
- Zariel I Johnson
- From the Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania 19107 and
| | - Alexandra C Doolittle
- From the Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania 19107 and
| | - Joseph W Snuggs
- the Biomolecular Sciences Research Centre, Sheffield Hallam University, S1 1WB Sheffield, United Kingdom
| | - Irving M Shapiro
- From the Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania 19107 and
| | - Christine L Le Maitre
- the Biomolecular Sciences Research Centre, Sheffield Hallam University, S1 1WB Sheffield, United Kingdom
| | - Makarand V Risbud
- From the Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania 19107 and
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30
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Welte MA, Gould AP. Lipid droplet functions beyond energy storage. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:1260-1272. [PMID: 28735096 PMCID: PMC5595650 DOI: 10.1016/j.bbalip.2017.07.006] [Citation(s) in RCA: 331] [Impact Index Per Article: 47.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 07/17/2017] [Accepted: 07/17/2017] [Indexed: 02/07/2023]
Abstract
Lipid droplets are cytoplasmic organelles that store neutral lipids and are critically important for energy metabolism. Their function in energy storage is firmly established and increasingly well characterized. However, emerging evidence indicates that lipid droplets also play important and diverse roles in the cellular handling of lipids and proteins that may not be directly related to energy homeostasis. Lipid handling roles of droplets include the storage of hydrophobic vitamin and signaling precursors, and the management of endoplasmic reticulum and oxidative stress. Roles of lipid droplets in protein handling encompass functions in the maturation, storage, and turnover of cellular and viral polypeptides. Other potential roles of lipid droplets may be connected with their intracellular motility and, in some cases, their nuclear localization. This diversity highlights that lipid droplets are very adaptable organelles, performing different functions in different biological contexts. This article is part of a Special Issue entitled: Recent Advances in Lipid Droplet Biology edited by Rosalind Coleman and Matthijs Hesselink.
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Affiliation(s)
- Michael A Welte
- Department of Biology, University of Rochester, Rochester, NY, United States.
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31
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Zhang C, Yang L, Ding Y, Wang Y, Lan L, Ma Q, Chi X, Wei P, Zhao Y, Steinbüchel A, Zhang H, Liu P. Bacterial lipid droplets bind to DNA via an intermediary protein that enhances survival under stress. Nat Commun 2017; 8:15979. [PMID: 28681845 PMCID: PMC5504291 DOI: 10.1038/ncomms15979] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 05/16/2017] [Indexed: 02/06/2023] Open
Abstract
Lipid droplets (LDs) are multi-functional organelles consisting of a neutral lipid core surrounded by a phospholipid monolayer, and exist in organisms ranging from bacteria to humans. Here we study the functions of LDs in the oleaginous bacterium Rhodococcus jostii. We show that these LDs bind to genomic DNA through the major LD protein, MLDS, which increases survival rate of the bacterial cells under nutritional and genotoxic stress. MLDS expression is regulated by a transcriptional regulator, MLDSR, that binds to the operator and promoter of the operon encoding both proteins. LDs sequester MLDSR, controlling its availability for transcriptional regulation. Our findings support the idea that bacterial LDs can regulate nucleic acid function and facilitate bacterial survival under stress. The MLDS protein is a major component of lipid droplets (LDs) in oleaginous bacteria. Here, Zhang et al. show that LDs bind to genomic DNA via MLDS, which enhances bacterial survival under certain stress conditions.
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Affiliation(s)
- Congyan Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Li Yang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yunfeng Ding
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yang Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Lan Lan
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qin Ma
- University of Chinese Academy of Sciences, Beijing 100049, China.,Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Xiang Chi
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Peng Wei
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yongfang Zhao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Alexander Steinbüchel
- Institute of Molecular Microbiology and Biotechnology, University of Münster, Corrensstrasse 3, D-48149 Münster, Germany.,Environmental Science Department, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Hong Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Pingsheng Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
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32
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Johnson ZI, Shapiro IM, Risbud MV. RNA Sequencing Reveals a Role of TonEBP Transcription Factor in Regulation of Pro-inflammatory Genes in Response to Hyperosmolarity in Healthy Nucleus Pulposus Cells: A HOMEOSTATIC RESPONSE? J Biol Chem 2016; 291:26686-26697. [PMID: 27875309 DOI: 10.1074/jbc.m116.757732] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 10/12/2016] [Indexed: 11/06/2022] Open
Abstract
Transcription factor tonicity-responsive enhancer-binding protein (TonEBP/NFAT5) is critical for osmo-adaptation and extracellular matrix homeostasis of nucleus pulposus (NP) cells in their hypertonic tissue niche. Recent studies implicate TonEBP signaling in inflammatory disease and rheumatoid arthritis pathogenesis. However, broader functions of TonEBP in the disc remain unknown. RNA sequencing was performed on NP cells with TonEBP knockdown under hypertonic conditions. 1140 TonEBP-dependent genes were identified and categorized using Ingenuity Pathway Analysis. Bioinformatic analysis showed enrichment of matrix homeostasis and cytokine/chemokine signaling pathways. C-C motif chemokine ligand 2 (CCL2), interleukin 6 (IL6), tumor necrosis factor (TNF), and nitric oxide synthase 2 (NOS2) were studied further. Knockdown experiments showed that TonEBP was necessary to maintain expression levels of these genes. Gain- and loss-of-function experiments and site-directed mutagenesis demonstrated that TonEBP binding to a specific site in the CCL2 promoter is required for hypertonic inducibility. Despite inhibition by dominant-negative TonEBP, IL6 and NOS2 promoters were not hypertonicity-inducible. Whole-disc response to hypertonicity was studied in an ex vivo organ culture model, using wild-type and haploinsufficient TonEBP mice. Pro-inflammatory targets were induced by hypertonicity in discs from wild-type but not TonEBP-haploinsufficient mice. Mechanistically, NF-κB activity increased with hypertonicity and was necessary for hypertonic induction of target genes IL6, TNF, and NOS2 but not CCL2 Although TonEBP maintains transcription of genes traditionally considered pro-inflammatory, it is important to note that some of these genes also serve anabolic and pro-survival roles. Therefore, in NP cells, this phenomenon may reflect a physiological adaptation to diurnal osmotic loading of the intervertebral disc.
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Affiliation(s)
- Zariel I Johnson
- Graduate Program in Cell and Developmental Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
| | - Irving M Shapiro
- Graduate Program in Cell and Developmental Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107.,From the Department of Orthopaedic Surgery and
| | - Makarand V Risbud
- Graduate Program in Cell and Developmental Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107 .,From the Department of Orthopaedic Surgery and
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33
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Liangpunsakul S, Gao B. Alcohol and fat promote steatohepatitis: a critical role for fat-specific protein 27/CIDEC. J Investig Med 2016; 64:1078-81. [PMID: 27342423 DOI: 10.1136/jim-2016-000204] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/11/2016] [Indexed: 12/20/2022]
Abstract
Alcoholic liver disease (ALD) is a major public health problem worldwide and is the leading cause of end-stage liver disease. While the ultimate control of ALD will require the prevention of alcohol abuse, better understanding of the mechanisms of alcohol-induced liver injury may lead to treatments of fatty liver, alcoholic hepatitis, and prevention or delay of occurrence of cirrhosis. The elucidation and the discovery of several new concepts in ALD pathogenesis have raised our understanding on the complex mechanisms and the potential in developing the new strategies for therapeutic benefits. In this review, we provide the most up-to-date information on the basic molecular mechanisms focusing on the role of fat-specific protein 27/CIDEC in the pathogenesis of ALD.
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Affiliation(s)
- Suthat Liangpunsakul
- Division of Gastroenterology and Hepatology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA Indiana University School of Medicine, Indianapolis, Indiana, USA Roudebush Veterans Administration Medical Center, Indianapolis, Indiana, USA
| | - Bin Gao
- Laboratory of Liver Diseases, National Institute of Alcohol Abuse and Alcoholism, Rockville, Maryland, USA
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34
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Abstract
Lipid droplets are the intracellular sites for neutral lipid storage. They are critical for lipid metabolism and energy homeostasis, and their dysfunction has been linked to many diseases. Accumulating evidence suggests that the roles lipid droplets play in biology are significantly broader than previously anticipated. Lipid droplets are the source of molecules important in the nucleus: they can sequester transcription factors and chromatin components and generate the lipid ligands for certain nuclear receptors. Lipid droplets have also emerged as important nodes for fatty acid trafficking, both inside the cell and between cells. In immunity, new roles for droplets, not directly linked to lipid metabolism, have been uncovered, with evidence that they act as assembly platforms for specific viruses and as reservoirs for proteins that fight intracellular pathogens. Until recently, knowledge about droplets in the nervous system has been minimal, but now there are multiple links between lipid droplets and neurodegeneration: many candidate genes for hereditary spastic paraplegia also have central roles in lipid-droplet formation and maintenance, and mitochondrial dysfunction in neurons can lead to transient accumulation of lipid droplets in neighboring glial cells, an event that may, in turn, contribute to neuronal damage. As the cell biology and biochemistry of lipid droplets become increasingly well understood, the next few years should yield many new mechanistic insights into these novel functions of lipid droplets.
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35
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Shen WJ, Azhar S, Kraemer FB. Lipid droplets and steroidogenic cells. Exp Cell Res 2015; 340:209-14. [PMID: 26639173 DOI: 10.1016/j.yexcr.2015.11.024] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 11/23/2015] [Accepted: 11/25/2015] [Indexed: 02/05/2023]
Abstract
Lipid droplets (LDs) in steroidogenic tissues have a cholesteryl ester (CE) core surrounded by a phospholipid monolayer that is coated with associated proteins. Compared with other tissues, they tend to be smaller in size and more numerous in numbers. These LDs are enriched with PLIN1c, PLIN2 and PLIN3. Both CIDE A and B are found in mouse ovary. Free cholesterol (FC) released upon hormone stimulation from LDs is the preferred source of cholesterol substrate for steroidogenesis, and HSL is the major neutral cholesterol esterase mediating the conversion of CEs to FC. Through the interaction of HSL with vimentin and StAR, FC is translocated to mitochondria for steroid hormone production. Proteomic analyses of LDs isolated from loaded primary ovarian granulosa cells, mouse MLTC-1 Leydig tumor cells and mouse testes revealed LD associated proteins that are actively involved in modulating lipid homeostasis along with a number of steroidogenic enzymes. Microscopy analysis confirmed the localization of many of these proteins to LDs. These studies broaden the role of LDs to include being a platform for functional steroidogenic enzyme activity or as a port for transferring steroidogenic enzymes and/or steroid intermediates, in addition to being a storage depot for CEs.
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Affiliation(s)
- Wen-Jun Shen
- Division of Endocrinology, Gerontology and Metabolism, Stanford University, Stanford, CA 94305, United States; Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304, United States
| | - Salman Azhar
- Division of Endocrinology, Gerontology and Metabolism, Stanford University, Stanford, CA 94305, United States; Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304, United States
| | - Fredric B Kraemer
- Division of Endocrinology, Gerontology and Metabolism, Stanford University, Stanford, CA 94305, United States; Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304, United States.
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36
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Mashek DG, Khan SA, Sathyanarayan A, Ploeger JM, Franklin MP. Hepatic lipid droplet biology: Getting to the root of fatty liver. Hepatology 2015; 62:964-7. [PMID: 25854913 PMCID: PMC4549163 DOI: 10.1002/hep.27839] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 04/04/2015] [Indexed: 12/22/2022]
Abstract
Hepatic steatosis is defined by the accumulation of lipid droplets (LDs). Once thought to be only inert energy storage depots, LDs are increasingly recognized as organelles that have important functions in hepatocytes beyond lipid storage. The lipid and protein composition of LDs is highly dynamic and influences their intrinsic metabolism and signaling properties, which ultimately links them to the changes in hepatic function. This concise review highlights recent discoveries in LD biology and unique aspects of hepatic LDs and their role in liver disease.
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Affiliation(s)
- Douglas G Mashek
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN
| | - Salmaan A Khan
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN
| | | | - Jonathan M Ploeger
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN
| | - Mallory P Franklin
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN
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37
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Timucin AC, Bodur C, Basaga H. SIRT1 contributes to aldose reductase expression through modulating NFAT5 under osmotic stress: In vitro and in silico insights. Cell Signal 2015; 27:2160-72. [PMID: 26297866 DOI: 10.1016/j.cellsig.2015.08.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 08/18/2015] [Indexed: 12/13/2022]
Abstract
So far, a myriad of molecules were characterized to modulate NFAT5 and its downstream targets. Among these NFAT5 modifiers, SIRT1 was proposed to have a promising role in NFAT5 dependent events, yet the exact underlying mechanism still remains obscure. Hence, the link between SIRT1 and NFAT5-aldose reductase (AR) axis under osmotic stress, was aimed to be delineated in this study. A unique osmotic stress model was generated and its mechanistic components were deciphered in U937 monocytes. In this model, AR expression and nuclear NFAT5 stabilization were revealed to be positively regulated by SIRT1 through utilization of pharmacological modulators. Overexpression and co-transfection studies of NFAT5 and SIRT1 further validated the contribution of SIRT1 to AR and NFAT5. The involvement of SIRT1 activity in these events was mediated via modification of DNA binding of NFAT5 to AR ORE region. Besides, NFAT5 and SIRT1 were also shown to co-immunoprecipitate under isosmotic conditions and this interaction was disrupted by osmotic stress. Further in silico experiments were conducted to investigate if SIRT1 directly targets NFAT5. In this regard, certain lysine residues of NFAT5, when kept deacetylated, were found to contribute to its DNA binding and SIRT1 was shown to directly bind K282 of NFAT5. Based on these in vitro and in silico findings, SIRT1 was identified, for the first time, as a novel positive regulator of NFAT5 dependent AR expression under osmotic stress in U937 monocytes.
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Affiliation(s)
- Ahmet Can Timucin
- Molecular Biology, Genetics and Bioengineering Program, Faculty of Engineering and Natural Sciences, Sabanci University, 34956, Orhanli, Tuzla, Istanbul, Turkey.
| | - Cagri Bodur
- Molecular Biology, Genetics and Bioengineering Program, Faculty of Engineering and Natural Sciences, Sabanci University, 34956, Orhanli, Tuzla, Istanbul, Turkey.
| | - Huveyda Basaga
- Molecular Biology, Genetics and Bioengineering Program, Faculty of Engineering and Natural Sciences, Sabanci University, 34956, Orhanli, Tuzla, Istanbul, Turkey.
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38
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Gao Q, Goodman JM. The lipid droplet-a well-connected organelle. Front Cell Dev Biol 2015; 3:49. [PMID: 26322308 PMCID: PMC4533013 DOI: 10.3389/fcell.2015.00049] [Citation(s) in RCA: 159] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 07/24/2015] [Indexed: 12/19/2022] Open
Abstract
Our knowledge of inter-organellar communication has grown exponentially in recent years. This review focuses on the interactions that cytoplasmic lipid droplets have with other organelles. Twenty-five years ago droplets were considered simply particles of coalesced fat. Ten years ago there were hints from proteomics studies that droplets might interact with other structures to share lipids and proteins. Now it is clear that the droplets interact with many if not most cellular structures to maintain cellular homeostasis and to buffer against insults such as starvation. The evidence for this statement, as well as probes to understand the nature and results of droplet interactions, are presented.
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Affiliation(s)
- Qiang Gao
- Department of Pharmacology, University of Texas Southwestern Medical Center Dallas, TX, USA
| | - Joel M Goodman
- Department of Pharmacology, University of Texas Southwestern Medical Center Dallas, TX, USA
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Extracellular osmolarity regulates matrix homeostasis in the intervertebral disc and articular cartilage: evolving role of TonEBP. Matrix Biol 2014; 40:10-6. [PMID: 25172826 PMCID: PMC4390124 DOI: 10.1016/j.matbio.2014.08.014] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 08/18/2014] [Accepted: 08/19/2014] [Indexed: 12/20/2022]
Abstract
Degeneration of the intervertebral disc is characterized by changes in proteoglycan status, loss of bound water molecules, decreased tissue osmotic pressure and a resulting mechanical failure of the disc. A similar spectrum of changes is evident in osteoarthritic articular cartilage. When healthy, resident cells in these skeletal tissues respond to applied mechanical loads by regulating their own osmotic state and the hydration of the extracellular matrix. The transcription factor Tonicity-Responsive Enhancer Binding Protein (TonEBP or NFAT5) is known to mediate the osmoadaptive response in these and other tissues. While the molecular basis of how osmotic loading controls matrix homeostasis is not completely understood, TonEBP regulates the expression of aggrecan and β1,3-glucoronosyltransferase in nucleus pulposus cells, in addition to targets that allow for survival under hypertonic stress. Moreover, in chondrocytes, TonEBP controls expression of several collagen subtypes and Sox9, a master regulator of aggrecan and collagen II expression. Thus, TonEBP-mediated regulation of the matrix composition allows disc cells and chondrocytes to modify the extracellular osmotic state itself. On the other hand, TonEBP in immune cells induces expression of TNF-α, IL-6 and MCP-1, pro-inflammatory molecules closely linked to matrix catabolism and pathogenesis of both disc degeneration and osteoarthritis, warranting investigations of this aspect of TonEBP function in skeletal cells. In summary, the TonEBP system, through its effects on extracellular matrix and osmoregulatory genes can be viewed primarily as a protective or homeostatic response to physiological loading.
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Abstract
PURPOSE OF REVIEW With the realization that lipid droplets are not merely inert fat storage organelles, but highly dynamic and actively involved in cellular lipid homeostasis, there has been an increased interest in lipid droplet biology. Recent studies have begun to unravel the roles that lipid dropletss play in cellular physiology and provide insights into the mechanisms by which lipid droplets contribute to cellular homeostasis. This review provides a summary of these recent publications on lipid droplet metabolism. RECENT FINDINGS Perilipins have different preferences for associating with triacylglycerol (TAG) or cholesteryl esters, different tissue distributions, and each contributes to lipid metabolism in its unique way. Cell death-inducing DFF45-like effector proteins are not only involved in lipid droplet expansion, but also in the cellular response to stress and lipid secretion. Lipid droplets undergo an active cycle of lipolysis and re-esterification to form microlipid droplets. TAG synthesis for lipid droplet formation and expansion occurs in the endoplasmic reticulum and on lipid droplets, and TAG transfers between lipid droplets during lipid droplet fusion. Lipid droplets interact with the endoplasmic reticulum and mitochondria to facilitate lipid transfer, lipid droplet expansion, and metabolism. SUMMARY Lipid droplets are dynamically active, responding to changes in cellular physiology, as well as interacting with cytosolic proteins and other organelles to control lipid homeostasis.
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Affiliation(s)
- Victor K Khor
- aVeterans Affairs Palo Alto Healthcare System, Palo Alto bDivision of Endocrinology, Stanford University, Stanford, California, USA
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Dugail I. Lysosome/lipid droplet interplay in metabolic diseases. Biochimie 2013; 96:102-5. [PMID: 23880642 DOI: 10.1016/j.biochi.2013.07.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 07/08/2013] [Indexed: 01/22/2023]
Abstract
Lysosomes and lipid droplets are generally considered as intracellular compartments with divergent roles in cell metabolism, lipid droplets serving as lipid reservoirs in anabolic pathways, whereas lysosomes are specialized in the catabolism of intracellular components. During the last few years, new insights in the biology of lysosomes has challenged this view by providing evidence for the importance of lysosome recycling as a sparing mechanism to maintain cellular fitness. On the other hand the understanding of lipid droplets has evolved from an inert intracellular deposit toward the status of an intracellular organelle with dynamic roles in cellular homeostasis beyond storage. These unrelated aspects have also recently converged in the finding of unexpected lipid droplet/lysosome communication through autophagy, and the discovery of lysosome-mediated lipid droplet degradation called lipopagy. Furthermore, adipocytes which are professional cells for lipid droplet formation were also shown to be active in peptide antigen presentation a pathway requiring lysosomal activity. The potential importance of lipid droplet/lysosome interplay is discussed in the context of metabolic diseases and the setting of chronic inflammation.
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Affiliation(s)
- Isabelle Dugail
- Centre de Recherche des Cordeliers, INSERM, U872, Paris F-75006, France; Université Pierre et Marie Curie - Paris6, UMR S872, Paris F-75006, France.
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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] [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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