51
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Jayson CBK, Arlt H, Fischer AW, Lai ZW, Farese RV, Walther TC. Rab18 is not necessary for lipid droplet biogenesis or turnover in human mammary carcinoma cells. Mol Biol Cell 2018; 29:2045-2054. [PMID: 29949452 PMCID: PMC6232964 DOI: 10.1091/mbc.e18-05-0282] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Rab GTPases recruit peripheral membrane proteins and can define organelle identity. Rab18 localizes to the endoplasmic reticulum (ER) but also to lipid droplets (LDs), where it has been implicated in effector protein recruitment and in defining LD identity. Here, we studied Rab18 localization and function in a human mammary carcinoma cell line. Rab18 localized to the ER and to LD membranes on LD induction, with the latter depending on the Rab18 activation state. In cells lacking Rab18, LDs were modestly reduced in size and numbers, but we found little evidence for Rab18 function in LD formation, LD turnover on cell starvation, or the targeting of several proteins to LDs. We conclude that Rab18 is not a general, necessary component of the protein machinery involved in LD biogenesis or turnover.
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Affiliation(s)
- Christina B K Jayson
- Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115.,Department of Cell Biology, Harvard Medical School, Boston, MA 02115
| | - Henning Arlt
- Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115.,Department of Cell Biology, Harvard Medical School, Boston, MA 02115
| | - Alexander W Fischer
- Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115.,Department of Cell Biology, Harvard Medical School, Boston, MA 02115.,Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, DE-20246 Hamburg, Germany
| | - Zon Weng Lai
- Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115.,Department of Cell Biology, Harvard Medical School, Boston, MA 02115
| | - Robert V Farese
- Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115.,Department of Cell Biology, Harvard Medical School, Boston, MA 02115.,Broad Institute of MIT and Harvard, Cambridge, MA 02142
| | - Tobias C Walther
- Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115.,Department of Cell Biology, Harvard Medical School, Boston, MA 02115.,Broad Institute of MIT and Harvard, Cambridge, MA 02142.,Howard Hughes Medical Institute, Boston, MA 02115
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52
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Glaser K, Dickie P, Neilson D, Osborn A, Dickie BH. Linkage of Metabolic Defects to Activated PIK3CA Alleles in Endothelial Cells Derived from Lymphatic Malformation. Lymphat Res Biol 2018; 16:43-55. [PMID: 29346025 DOI: 10.1089/lrb.2017.0033] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Lymphatic endothelial cells (LECs) derived from lymphatic malformations (LMs) bear activated PIK3CA alleles yet display an inflammatory gene expression profile. A basis for the inflammatory phenotype was sought by screening for coexisting somatic mutations. METHODS AND RESULTS Fourteen independent LEC populations bearing activated PIK3CA alleles were isolated from LM. These were characterized by the expression of growth and inflammatory genes (VEGFC, IL-6, COX-2, IL-8, HO-1, E-SEL) by qRT-PCR. Most commonly upregulated gene products were VEGFC, COX2, HO-1, and ANGPTL4. The specific inhibition of PI3K reduced VEGFC expression without resolving inflammation. Whole exome sequencing of six LM-LEC populations identified five novel somatically acquired alleles coexisting with activated PIK3CA alleles. Two affected genes regulate lipid droplet metabolism (FITM2 and ATG2A), two are gene regulators (MTA1 and TAF1L), and the fifth is an isoform of ANK3 (an endosomal/lysosomal protein). Inhibition of AMPK implicated its involvement in regulating COX-2 and HO-1 overexpression. ANGPTL4 expression was independent of AMPK and PI3K activity and reflected lipid stress demonstrated in normal LECs. AMPK activation with AICAR had a selective growth-limiting effect in a subset of LM-LEC isolates. CONCLUSIONS Inflammatory stress displayed by LM-LECs is consistent with errors in lipid metabolism that may be linked to acquired mutations. The acquisition of PIK3CA alleles may be a permissive event that antagonizes inflammation and metabolic defect.
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Affiliation(s)
- Kathryn Glaser
- 1 Department of Pediatric General and Thoracic Surgery, Cincinnati Children's Hospital and Medical Center , Cincinnati, Ohio
| | - Peter Dickie
- 1 Department of Pediatric General and Thoracic Surgery, Cincinnati Children's Hospital and Medical Center , Cincinnati, Ohio
| | - Derek Neilson
- 2 Division of Human Genetics, Cincinnati Children's Hospital and Medical Center , Cincinnati, Ohio
| | - Alexander Osborn
- 1 Department of Pediatric General and Thoracic Surgery, Cincinnati Children's Hospital and Medical Center , Cincinnati, Ohio
| | - Belinda Hsi Dickie
- 1 Department of Pediatric General and Thoracic Surgery, Cincinnati Children's Hospital and Medical Center , Cincinnati, Ohio
- 3 Department of Surgery, Harvard Medical School, Boston Children's Hospital , Boston, Massachusetts
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53
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Montserrat-de la Paz S, Bermudez B, Cardelo MP, Lopez S, Abia R, Muriana FJG. Olive oil and postprandial hyperlipidemia: implications for atherosclerosis and metabolic syndrome. Food Funct 2018; 7:4734-4744. [PMID: 27885367 DOI: 10.1039/c6fo01422d] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Olive oil is the primary source of fat in the Mediterranean diet, which is associated with a significant improvement in health status, as measured by reduced mortality from several chronic diseases. The current pandemic of obesity, metabolic syndrome, and type 2 diabetes is intimately associated with an atherogenic dyslipidemic phenotype. The core components of the dyslipidemia of the metabolic syndrome, which most likely initiate atherosclerosis, are the "lipid triad" consisting of high plasma triglycerides, low levels of high-density lipoproteins, and a preponderance of small, dense low-density lipoproteins at fasting. However, postprandial (non-fasting) TGs (postprandial hyperlipidemia) are also recognized as an important component for atherosclerosis. Herein, the purpose of this review was to provide an update on the effects and mechanisms related to olive oil on postprandial hyperlipidemia and its implications for the onset and progression of atherosclerosis and metabolic syndrome.
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Affiliation(s)
- Sergio Montserrat-de la Paz
- Laboratory of Cellular and Molecular Nutrition, Instituto de la Grasa, CSIC. Ctra. de Utrera Km. 1, 41013 Seville, Spain.
| | - Beatriz Bermudez
- Department of Cell Biology, Faculty of Biology, University of Seville. C/ Professor Garcia Gonzalez s/n, 41012 Seville, Spain
| | - Magdalena P Cardelo
- Laboratory of Cellular and Molecular Nutrition, Instituto de la Grasa, CSIC. Ctra. de Utrera Km. 1, 41013 Seville, Spain.
| | - Sergio Lopez
- Laboratory of Cellular and Molecular Nutrition, Instituto de la Grasa, CSIC. Ctra. de Utrera Km. 1, 41013 Seville, Spain.
| | - Rocio Abia
- Laboratory of Cellular and Molecular Nutrition, Instituto de la Grasa, CSIC. Ctra. de Utrera Km. 1, 41013 Seville, Spain.
| | - Francisco J G Muriana
- Laboratory of Cellular and Molecular Nutrition, Instituto de la Grasa, CSIC. Ctra. de Utrera Km. 1, 41013 Seville, Spain.
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54
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Xu D, Li Y, Wu L, Li Y, Zhao D, Yu J, Huang T, Ferguson C, Parton RG, Yang H, Li P. Rab18 promotes lipid droplet (LD) growth by tethering the ER to LDs through SNARE and NRZ interactions. J Cell Biol 2018; 217:975-995. [PMID: 29367353 PMCID: PMC5839781 DOI: 10.1083/jcb.201704184] [Citation(s) in RCA: 148] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Revised: 10/12/2017] [Accepted: 12/22/2017] [Indexed: 12/16/2022] Open
Abstract
Lipid incorporation from endoplasmic reticulum (ER) to lipid droplet (LD) is important in controlling LD growth and intracellular lipid homeostasis. However, the molecular link mediating ER and LD cross talk remains elusive. Here, we identified Rab18 as an important Rab guanosine triphosphatase in controlling LD growth and maturation. Rab18 deficiency resulted in a drastically reduced number of mature LDs and decreased lipid storage, and was accompanied by increased ER stress. Rab3GAP1/2, the GEF of Rab18, promoted LD growth by activating and targeting Rab18 to LDs. LD-associated Rab18 bound specifically to the ER-associated NAG-RINT1-ZW10 (NRZ) tethering complex and their associated SNAREs (Syntaxin18, Use1, BNIP1), resulting in the recruitment of ER to LD and the formation of direct ER-LD contact. Cells with defects in the NRZ/SNARE complex function showed reduced LD growth and lipid storage. Overall, our data reveal that the Rab18-NRZ-SNARE complex is critical protein machinery for tethering ER-LD and establishing ER-LD contact to promote LD growth.
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Affiliation(s)
- Dijin Xu
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yuqi Li
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Lizhen Wu
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Ying Li
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Dongyu Zhao
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Jinhai Yu
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Tuozhi Huang
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Charles Ferguson
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Australia
| | - Robert G Parton
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Australia.,Centre for Microscopy and Microanalysis, University of Queensland, Brisbane, Australia
| | - Hongyuan Yang
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
| | - Peng Li
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
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55
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Eisenberg-Bord M, Mari M, Weill U, Rosenfeld-Gur E, Moldavski O, Castro IG, Soni KG, Harpaz N, Levine TP, Futerman AH, Reggiori F, Bankaitis VA, Schuldiner M, Bohnert M. Identification of seipin-linked factors that act as determinants of a lipid droplet subpopulation. J Cell Biol 2017; 217:269-282. [PMID: 29187527 PMCID: PMC5748981 DOI: 10.1083/jcb.201704122] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 09/21/2017] [Accepted: 10/23/2017] [Indexed: 02/07/2023] Open
Abstract
Eisenberg-Bord et al. describe a lipid droplet (LD) subpopulation with a unique proteome, which is adjacent to the nucleus–vacuole junction contact site. They identify the LD machinery, which cooperates with the lipodystrophy factor seipin as a key determinant of LD identity and suggest a mechanism for functional organelle diversification. Functional heterogeneity within the lipid droplet (LD) pool of a single cell has been observed, yet the underlying mechanisms remain enigmatic. Here, we report on identification of a specialized LD subpopulation characterized by a unique proteome and a defined geographical location at the nucleus–vacuole junction contact site. In search for factors determining identity of these LDs, we screened ∼6,000 yeast mutants for loss of targeting of the subpopulation marker Pdr16 and identified Ldo45 (LD organization protein of 45 kD) as a crucial targeting determinant. Ldo45 is the product of a splicing event connecting two adjacent genes (YMR147W and YMR148W/OSW5/LDO16). We show that Ldo proteins cooperate with the LD biogenesis component seipin and establish LD identity by defining positioning and surface-protein composition. Our studies suggest a mechanism to establish functional differentiation of organelles, opening the door to better understanding of metabolic decisions in cells.
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Affiliation(s)
| | - Muriel Mari
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Uri Weill
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Eden Rosenfeld-Gur
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Ofer Moldavski
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Inês G Castro
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Krishnakant G Soni
- Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX
| | - Nofar Harpaz
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Tim P Levine
- UCL Institute of Ophthalmology, London, England, UK
| | - Anthony H Futerman
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Fulvio Reggiori
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Vytas A Bankaitis
- Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Maria Bohnert
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
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56
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de la Rosa Rodriguez MA, Kersten S. Regulation of lipid droplet-associated proteins by peroxisome proliferator-activated receptors. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:1212-1220. [DOI: 10.1016/j.bbalip.2017.07.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 07/13/2017] [Accepted: 07/14/2017] [Indexed: 12/24/2022]
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57
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Chirambo G, van Niekerk C, Crowther NJ. Specific knock-down of tissue non-specific alkaline phosphatase mRNA levels inhibits intracellular lipid accumulation in 3T3-L1 and HepG2 cells. Int J Exp Pathol 2017; 98:260-268. [PMID: 28925080 PMCID: PMC5743820 DOI: 10.1111/iep.12243] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 08/01/2017] [Indexed: 11/30/2022] Open
Abstract
The use of non-specific inhibitors of tissue non-specific alkaline phosphatase (TNSALP) in pre-adipocytes blocks intracellular lipid accumulation. TNSALP is also expressed in hepatocytes, which are known to accumulate lipid in a similar manner to pre-adipocytes. The purpose of this study was to use specific silencing of TNSALP mRNA, using short interfering (si) RNA, to investigate the role of TNSALP in intracellular lipid accumulation in 3T3-L1 and HepG2 cells. Cellular activity of TNSALP was measured using an automated colorimetric assay, and intracellular lipid accumulation was determined using the lipid-specific dye, Oil Red O. Cells were transfected with siRNA directed against TNSALP mRNA, and expression of the TNSALP gene was determined at selected time points postinduction of lipid droplet formation. Expression of the TNSALP gene was inhibited by a maximum of 88 ± 1.9% (P < 0.005 vs. control) 11 days after initiation of lipid droplet formation in the 3T3-L1 cells and 80 ± 8.9% (P < 0.05 vs. control) after 4 days in the HepG2 cells. This led to significant inhibition of both TNSALP activity and intracellular lipid accumulation in both cell lines. These data demonstrates that TNSALP plays an important role in the control of lipid droplet formation in both pre-adipocyte and hepatocyte cell lines.
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Affiliation(s)
- George Chirambo
- Department of Chemical PathologyNational Health Laboratory ServiceUniversity of Witwatersrand Medical SchoolJohannesburgSouth Africa
- Department of BiochemistryCollege Of MedicineUniversity of MalawiMalawiBlantyre
| | - Chantal van Niekerk
- Department of Chemical PathologyNational Health Laboratory ServiceUniversity of Witwatersrand Medical SchoolJohannesburgSouth Africa
| | - Nigel J. Crowther
- Department of Chemical PathologyNational Health Laboratory ServiceUniversity of Witwatersrand Medical SchoolJohannesburgSouth Africa
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58
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Bader CA, Carter EA, Safitri A, Simpson PV, Wright P, Stagni S, Massi M, Lay PA, Brooks DA, Plush SE. Unprecedented staining of polar lipids by a luminescent rhenium complex revealed by FTIR microspectroscopy in adipocytes. MOLECULAR BIOSYSTEMS 2017; 12:2064-8. [PMID: 27170554 DOI: 10.1039/c6mb00242k] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Fourier transform infrared (FTIR) microspectroscopy and confocal imaging have been used to demonstrate that the neutral rhenium(i) tricarbonyl 1,10-phenanthroline complex bound to 4-cyanophenyltetrazolate as the ancillary ligand is able to localise in regions with high concentrations of polar lipids such as phosphatidylethanolamine (PE), sphingomyelin, sphingosphine and lysophosphatidic acid (LPA) in mammalian adipocytes.
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Affiliation(s)
- C A Bader
- Mechanisms in Cell Biology and Disease Research Group, School of Pharmacy and Medical Sciences/Sansom Institute for Health Research, University of South Australia, Adelaide, Australia.
| | - E A Carter
- Vibrational Spectroscopy Core Facility and School of Chemistry, The University of Sydney, Sydney, Australia
| | - A Safitri
- Vibrational Spectroscopy Core Facility and School of Chemistry, The University of Sydney, Sydney, Australia
| | - P V Simpson
- School of Chemistry, Curtin University, Perth, Australia
| | - P Wright
- School of Chemistry, Curtin University, Perth, Australia
| | - S Stagni
- Department of Industrial Chemistry "Toso Montanari", University of Bologna, Bologna, Italy
| | - M Massi
- School of Chemistry, Curtin University, Perth, Australia
| | - P A Lay
- Vibrational Spectroscopy Core Facility and School of Chemistry, The University of Sydney, Sydney, Australia
| | - D A Brooks
- Mechanisms in Cell Biology and Disease Research Group, School of Pharmacy and Medical Sciences/Sansom Institute for Health Research, University of South Australia, Adelaide, Australia.
| | - S E Plush
- Mechanisms in Cell Biology and Disease Research Group, School of Pharmacy and Medical Sciences/Sansom Institute for Health Research, University of South Australia, Adelaide, Australia.
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59
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Kimmel AR, Sztalryd C. The Perilipins: Major Cytosolic Lipid Droplet-Associated Proteins and Their Roles in Cellular Lipid Storage, Mobilization, and Systemic Homeostasis. Annu Rev Nutr 2017; 36:471-509. [PMID: 27431369 DOI: 10.1146/annurev-nutr-071813-105410] [Citation(s) in RCA: 168] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The discovery by Dr. Constantine Londos of perilipin 1, the major scaffold protein at the surface of cytosolic lipid droplets in adipocytes, marked a fundamental conceptual change in the understanding of lipolytic regulation. Focus then shifted from the enzymatic activation of lipases to substrate accessibility, mediated by perilipin-dependent protein sequestration and recruitment. Consequently, the lipid droplet became recognized as a unique, metabolically active cellular organelle and its surface as the active site for novel protein-protein interactions. A new area of investigation emerged, centered on lipid droplets' biology and their role in energy homeostasis. The perilipin family is of ancient origin and has expanded to include five mammalian genes and a growing list of evolutionarily conserved members. Universally, the perilipins modulate cellular lipid storage. This review provides a summary that connects the perilipins to both cellular and whole-body homeostasis.
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Affiliation(s)
- Alan R Kimmel
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, The National Institutes of Health, Bethesda, Maryland 20892;
| | - Carole Sztalryd
- The Geriatric Research Education and Clinical Center, Baltimore Veterans Affairs Medical Center, Baltimore, Maryland 21201.,Division of Endocrinology, Department of Medicine, School of Medicine, University of Maryland, Baltimore, Maryland 21201;
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60
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Joshi AS, Zhang H, Prinz WA. Organelle biogenesis in the endoplasmic reticulum. Nat Cell Biol 2017; 19:876-882. [DOI: 10.1038/ncb3579] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Accepted: 06/21/2017] [Indexed: 12/16/2022]
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61
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Pyc M, Cai Y, Greer MS, Yurchenko O, Chapman KD, Dyer JM, Mullen RT. Turning Over a New Leaf in Lipid Droplet Biology. TRENDS IN PLANT SCIENCE 2017; 22:596-609. [PMID: 28454678 DOI: 10.1016/j.tplants.2017.03.012] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Revised: 03/22/2017] [Accepted: 03/24/2017] [Indexed: 05/08/2023]
Abstract
Lipid droplets (LDs) in plants have long been viewed as storage depots for neutral lipids that serve as sources of carbon, energy, and lipids for membrane biosynthesis. While much of our knowledge of LD function in plants comes from studies of oilseeds, a recent surge in research on LDs in non-seed cell types has led to an array of new discoveries. It is now clear that both evolutionarily conserved and kingdom-specific mechanisms underlie the biogenesis of LDs in eukaryotes, and proteomics and homology-based approaches have identified new protein players. This review highlights some of these recent discoveries and other new areas of plant LD research, including their role in stress responses and as targets of metabolic engineering strategies aimed at increasing oil content in bioenergy crops.
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Affiliation(s)
- Michal Pyc
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Yingqi Cai
- Department of Biological Sciences, Center for Plant Lipid Research, University of North Texas, Denton, TX 76203, USA
| | - Michael S Greer
- Department of Biological Sciences, Center for Plant Lipid Research, University of North Texas, Denton, TX 76203, USA
| | - Olga Yurchenko
- US Department of Agriculture, Agricultural Research Service, US Arid-Land Agricultural Research Center, Maricopa, AZ 85138, USA
| | - Kent D Chapman
- Department of Biological Sciences, Center for Plant Lipid Research, University of North Texas, Denton, TX 76203, USA
| | - John M Dyer
- US Department of Agriculture, Agricultural Research Service, US Arid-Land Agricultural Research Center, Maricopa, AZ 85138, USA.
| | - Robert T Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
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62
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Su X, Liu S, Zhang X, Lam SM, Hu X, Zhou Y, Chen J, Wang Y, Wu C, Shui G, Lu M, Pei R, Chen X. Requirement of cytosolic phospholipase A2 gamma in lipid droplet formation. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:692-705. [DOI: 10.1016/j.bbalip.2017.03.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 03/16/2017] [Accepted: 03/18/2017] [Indexed: 01/24/2023]
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63
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Onal G, Kutlu O, Gozuacik D, Dokmeci Emre S. Lipid Droplets in Health and Disease. Lipids Health Dis 2017; 16:128. [PMID: 28662670 PMCID: PMC5492776 DOI: 10.1186/s12944-017-0521-7] [Citation(s) in RCA: 166] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 06/16/2017] [Indexed: 12/16/2022] Open
Abstract
Lipids are essential building blocks synthesized by complex molecular pathways and deposited as lipid droplets (LDs) in cells. LDs are evolutionary conserved organelles found in almost all organisms, from bacteria to mammals. They are composed of a hydrophobic neutral lipid core surrounding by a phospholipid monolayer membrane with various decorating proteins. Degradation of LDs provide metabolic energy for divergent cellular processes such as membrane synthesis and molecular signaling. Lipolysis and autophagy are two main catabolic pathways of LDs, which regulate lipid metabolism and, thereby, closely engaged in many pathological conditons. In this review, we first provide an overview of the current knowledge on the structural properties and the biogenesis of LDs. We further focus on the recent findings of their catabolic mechanism by lipolysis and autophagy as well as their connection ragarding the regulation and function. Moreover, we discuss the relevance of LDs and their catabolism-dependent pathophysiological conditions.
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Affiliation(s)
- Gizem Onal
- Department of Medical Biology, Hacettepe University, 06100, Ankara, Turkey
| | - Ozlem Kutlu
- Nanotechnology Research and Application Center (SUNUM) & Center of Excellence for Functional Surfaces and Interfaces for Nano Diagnostics (EFSUN), Sabanci University, 34956, Istanbul, Turkey
| | - Devrim Gozuacik
- Molecular Biology, Genetics, and Bioengineering Program & Center of Excellence for Functional Surfaces and Interfaces for Nano Diagnostics (EFSUN), Sabanci University, 34956, Istanbul, Turkey
| | - Serap Dokmeci Emre
- Department of Medical Biology, Hacettepe University, 06100, Ankara, Turkey.
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64
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Lipid droplet growth and adipocyte development: mechanistically distinct processes connected by phospholipids. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:1273-1283. [PMID: 28668300 DOI: 10.1016/j.bbalip.2017.06.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Revised: 06/20/2017] [Accepted: 06/23/2017] [Indexed: 12/19/2022]
Abstract
The differentiation of preadipocytes into mature adipocytes is accompanied by the growth and formation of a giant, unilocular lipid droplet (LD). Mechanistically however, LD growth and adipogenesis are two different processes. Recent studies have uncovered a number of proteins that are able to regulate both LD dynamics and adipogenesis, such as SEIPIN, LIPIN and CDP-Diacylglycerol Synthases. It appears that phospholipids, phosphatidic acid in particular, play a critical role in both LD budding/growth and adipocyte development. This review summarizes recent advances, and aims to provide a better understanding of LD growth as well as adipogenesis, two critical aspects in mammalian fat storage. 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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65
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A snake venom group IIA PLA 2 with immunomodulatory activity induces formation of lipid droplets containing 15-d-PGJ 2 in macrophages. Sci Rep 2017. [PMID: 28642580 PMCID: PMC5481388 DOI: 10.1038/s41598-017-04498-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Crotoxin B (CB) is a catalytically active group IIA sPLA2 from Crotalus durissus terrificus snake venom. In contrast to most GIIA sPLA2s, CB exhibits anti-inflammatory effects, including the ability to inhibit leukocyte functions. Lipid droplets (LDs) are lipid-rich organelles associated with inflammation and recognized as a site for the synthesis of inflammatory lipid mediators. Here, the ability of CB to induce formation of LDs and the mechanisms involved in this effect were investigated in isolated macrophages. The profile of CB-induced 15-d-PGJ2 (15-Deoxy-Delta-12,14-prostaglandin J2) production and involvement of LDs in 15-d-PGJ2 biosynthesis were also investigated. Stimulation of murine macrophages with CB induced increased number of LDs and release of 15-d-PGJ2. LDs induced by CB were associated to PLIN2 recruitment and expression and required activation of PKC, PI3K, MEK1/2, JNK, iPLA2 and PLD. Both 15-d-PGJ2 and COX-1 were found in CB-induced LDs indicating that LDs contribute to the inhibitory effects of CB by acting as platform for synthesis of 15-d-PGJ2, a pro-resolving lipid mediator. Together, our data indicate that an immunomodulatory GIIA sPLA2 can directly induce LD formation and production of a pro-resolving mediator in an inflammatory cell and afford new insights into the roles of LDs in resolution of inflammatory processes.
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Cul3 neddylation is crucial for gradual lipid droplet formation during adipogenesis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:1405-1412. [PMID: 28499918 DOI: 10.1016/j.bbamcr.2017.05.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Accepted: 05/08/2017] [Indexed: 01/04/2023]
Abstract
Cullin 3 (Cul3) belongs to the family of cullins (Cul1-7) providing the scaffold for cullin-RING ubiquitin (Ub) ligases (CRLs), which are activated by neddylation and represent essential E3 ligases of the Ub proteasome system. During adipogenic differentiation neddylated Cul3 accumulates in LiSa-2 preadipocytes. Downregulation of Cul3 and inhibition of neddylation by MLN4924 blocks the formation of lipid droplets (LDs), the lipid storage organelles and markers of adipogenesis. Neddylation of Cul3 coincides with an increase of Rab18, a GTPase associated with LDs. Immunoprecipitation and confocal fluorescence microscopy revealed physical association of Cul3 and Rab18 at the membrane of LDs. RhoA, a suppressor of adipogenesis decreased during differentiation. Our results in LiSa-2 cells, but also mouse embryonic fibroblasts revealed a connection between Cul3, Rab18 and RhoA. Downregulation of Cul3 led to a marked increase in RhoA protein expression after 6days of LiSa-2 cell differentiation, suggesting that Cul3 is involved in the regulation of RhoA stability.
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67
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Perrotta I. Interaction between lipid droplets and endoplasmic reticulum in human atherosclerotic plaques. Ultrastruct Pathol 2017; 41:1-9. [DOI: 10.1080/01913123.2016.1269861] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Ida Perrotta
- Department of Biology, Ecology and Earth Sciences (Di.B.E.S.T.), Centre for Microscopy and Microanalysis (CM2), Transmission Electron Microscopy Laboratory, University of Calabria, Cosenza, Italy
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Lee LCC, Leung KK, Lo KKW. Recent development of luminescent rhenium(i) tricarbonyl polypyridine complexes as cellular imaging reagents, anticancer drugs, and antibacterial agents. Dalton Trans 2017; 46:16357-16380. [DOI: 10.1039/c7dt03465b] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
This Perspective summarizes recent advances in the biological applications of luminescent rhenium(i) tricarbonyl polypyridine complexes.
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Affiliation(s)
| | - Kam-Keung Leung
- Department of Chemistry
- City University of Hong Kong
- P. R. China
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69
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The size matters: regulation of lipid storage by lipid droplet dynamics. SCIENCE CHINA-LIFE SCIENCES 2016; 60:46-56. [PMID: 27981432 DOI: 10.1007/s11427-016-0322-x] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 10/28/2016] [Indexed: 12/14/2022]
Abstract
Adequate energy storage is essential for sustaining healthy life. Lipid droplet (LD) is the subcellular organelle that stores energy in the form of neutral lipids and releases fatty acids under energy deficient conditions. Energy storage capacity of LDs is primarily dependent on the sizes of LDs. Enlargement and growth of LDs is controlled by two molecular pathways: neutral lipid synthesis and atypical LD fusion. Shrinkage of LDs is mediated by the degradation of neutral lipids under energy demanding conditions and is controlled by neutral cytosolic lipases and lysosomal acidic lipases. In this review, we summarize recent progress regarding the regulatory pathways and molecular mechanisms that control the sizes and the energy storage capacity of LDs.
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70
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Pfeiler S, Khandagale AB, Magenau A, Nichols M, Heijnen HFG, Rinninger F, Ziegler T, Seveau S, Schubert S, Zahler S, Verschoor A, Latz E, Massberg S, Gaus K, Engelmann B. Distinct surveillance pathway for immunopathology during acute infection via autophagy and SR-BI. Sci Rep 2016; 6:34440. [PMID: 27694929 PMCID: PMC5046072 DOI: 10.1038/srep34440] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 09/13/2016] [Indexed: 12/21/2022] Open
Abstract
The mechanisms protecting from immunopathology during acute bacterial infections are incompletely known. We found that in response to apoptotic immune cells and live or dead Listeria monocytogenes scavenger receptor BI (SR-BI), an anti-atherogenic lipid exchange mediator, activated internalization mechanisms with characteristics of macropinocytosis and, assisted by Golgi fragmentation, initiated autophagic responses. This was supported by scavenger receptor-induced local increases in membrane cholesterol concentrations which generated lipid domains particularly in cell extensions and the Golgi. SR-BI was a key driver of beclin-1-dependent autophagy during acute bacterial infection of the liver and spleen. Autophagy regulated tissue infiltration of neutrophils, suppressed accumulation of Ly6C+ (inflammatory) macrophages, and prevented hepatocyte necrosis in the core of infectious foci. Perifocal levels of Ly6C+ macrophages and Ly6C− macrophages were unaffected, indicating predominant regulation of the focus core. SR-BI-triggered autophagy promoted co-elimination of apoptotic immune cells and dead bacteria but barely influenced bacterial sequestration and survival or inflammasome activation, thus exclusively counteracting damage inflicted by immune responses. Hence, SR-BI- and autophagy promote a surveillance pathway that partially responds to products of antimicrobial defenses and selectively prevents immunity-induced damage during acute infection. Our findings suggest that control of infection-associated immunopathology can be based on a unified defense operation.
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Affiliation(s)
- Susanne Pfeiler
- Institut für Laboratoriumsmedizin, Ludwig-Maximilians-Universität, Munich, 81377, Germany
| | - Avinash B Khandagale
- Institut für Laboratoriumsmedizin, Ludwig-Maximilians-Universität, Munich, 81377, Germany
| | - Astrid Magenau
- Centre for Vascular Research, ARC Centre for Excellence in Advanced Molecular Imaging and Australian Centre for Nanomedicine, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Maryana Nichols
- Institut für Laboratoriumsmedizin, Ludwig-Maximilians-Universität, Munich, 81377, Germany
| | - Harry F G Heijnen
- Laboratory of Clinical Chemistry and Haematology and Cell Microscopy Center, University Medical Center Utrecht, Utrecht, 3584CX, The Netherlands
| | - Franz Rinninger
- Universitätsklinik Hamburg-Eppendorf, Hamburg, 20246, Germany
| | - Tilman Ziegler
- Medizinische Klinik und Poliklinik I, Ludwig-Maximilians-Universität, Munich, 81377, Germany
| | - Stephanie Seveau
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Sören Schubert
- Max von Pettenkofer-Institut, Ludwig-Maximilians-Universität, Munich, 80336, Germany
| | - Stefan Zahler
- Institut für Pharmazeutische Biologie, Ludwig-Maximilians-Universität, Munich, 81377, Germany
| | - Admar Verschoor
- Institut für Systemische Entzündungsforschung, Universität zu Lübeck, Lübeck, 23538, Germany
| | - Eicke Latz
- Institute of Innate Immunity, University of Bonn, Bonn, 53127, Germany.,Department of Infectious Diseases and Immunology, UMass Medical School, Worcester, MA 01605, USA.,German Center for Neurodegenerative Diseases (DZNE), Bonn, 53127, Germany
| | - Steffen Massberg
- Medizinische Klinik und Poliklinik I, Ludwig-Maximilians-Universität, Munich, 81377, Germany
| | - Katharina Gaus
- Centre for Vascular Research, ARC Centre for Excellence in Advanced Molecular Imaging and Australian Centre for Nanomedicine, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Bernd Engelmann
- Institut für Laboratoriumsmedizin, Ludwig-Maximilians-Universität, Munich, 81377, Germany
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72
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Davis MR, Arner E, Duffy CRE, De Sousa PA, Dahlman I, Arner P, Summers KM. Expression of FBN1 during adipogenesis: Relevance to the lipodystrophy phenotype in Marfan syndrome and related conditions. Mol Genet Metab 2016; 119:174-85. [PMID: 27386756 PMCID: PMC5044862 DOI: 10.1016/j.ymgme.2016.06.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 06/18/2016] [Accepted: 06/18/2016] [Indexed: 01/27/2023]
Abstract
Fibrillin-1 is a large glycoprotein encoded by the FBN1 gene in humans. It provides strength and elasticity to connective tissues and is involved in regulating the bioavailability of the growth factor TGFβ. Mutations in FBN1 may be associated with depleted or abnormal adipose tissue, seen in some patients with Marfan syndrome and lipodystrophies. As this lack of adipose tissue does not result in high morbidity or mortality, it is generally under-appreciated, but is a cause of psychosocial problems particularly to young patients. We examined the role of fibrillin-1 in adipogenesis. In inbred mouse strains we found significant variation in the level of expression in the Fbn1 gene that correlated with variation in several measures of body fat, suggesting that mouse fibrillin-1 is associated with the level of fat tissue. Furthermore, we found that FBN1 mRNA was up-regulated in the adipose tissue of obese women compared to non-obese, and associated with an increase in adipocyte size. We used human mesenchymal stem cells differentiated in culture to adipocytes to show that fibrillin-1 declines after the initiation of differentiation. Gene expression results from a similar experiment (available through the FANTOM5 project) revealed that the decline in fibrillin-1 protein was paralleled by a decline in FBN1 mRNA. Examination of the FBN1 gene showed that the region commonly affected in FBN1-associated lipodystrophy is highly conserved both across the three human fibrillin genes and across genes encoding fibrillin-1 in vertebrates. These results suggest that fibrillin-1 is involved as the undifferentiated mesenchymal stem cells transition to adipogenesis but then declines as the developing adipocytes take on their final phenotype. Since the C-terminal peptide of fibrillin-1 is a glucogenic hormone, individuals with low fibrillin-1 (for example with FBN1 mutations associated with lipodystrophy) may fail to differentiate adipocytes and/or to accumulate adipocyte lipids, although this still needs to be shown experimentally.
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Affiliation(s)
- Margaret R Davis
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, EH25 9RG, UK.
| | - Erik Arner
- RIKEN Center for Life Science Technologies (Division of Genomic Technologies) (CLST (DGT)), 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
| | - Cairnan R E Duffy
- Centre for Clinical Brain Sciences, University of Edinburgh, Chancellors Building, 49 Little France Crescent, Edinburgh, EH16 4SB, UK.
| | - Paul A De Sousa
- Centre for Clinical Brain Sciences, University of Edinburgh, Chancellors Building, 49 Little France Crescent, Edinburgh, EH16 4SB, UK.
| | - Ingrid Dahlman
- Department of Medicine, Huddinge (Med H), Karolinska Universitetssjukhuset Huddinge, 141 86, Stockholm, Sweden.
| | - Peter Arner
- Department of Medicine, Huddinge (Med H), Karolinska Universitetssjukhuset Huddinge, 141 86, Stockholm, Sweden.
| | - Kim M Summers
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, EH25 9RG, UK.
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73
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Wang H, Becuwe M, Housden BE, Chitraju C, Porras AJ, Graham MM, Liu XN, Thiam AR, Savage DB, Agarwal AK, Garg A, Olarte MJ, Lin Q, Fröhlich F, Hannibal-Bach HK, Upadhyayula S, Perrimon N, Kirchhausen T, Ejsing CS, Walther TC, Farese RV. Seipin is required for converting nascent to mature lipid droplets. eLife 2016; 5. [PMID: 27564575 PMCID: PMC5035145 DOI: 10.7554/elife.16582] [Citation(s) in RCA: 253] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 08/25/2016] [Indexed: 12/16/2022] Open
Abstract
How proteins control the biogenesis of cellular lipid droplets (LDs) is poorly understood. Using Drosophila and human cells, we show here that seipin, an ER protein implicated in LD biology, mediates a discrete step in LD formation-the conversion of small, nascent LDs to larger, mature LDs. Seipin forms discrete and dynamic foci in the ER that interact with nascent LDs to enable their growth. In the absence of seipin, numerous small, nascent LDs accumulate near the ER and most often fail to grow. Those that do grow prematurely acquire lipid synthesis enzymes and undergo expansion, eventually leading to the giant LDs characteristic of seipin deficiency. Our studies identify a discrete step of LD formation, namely the conversion of nascent LDs to mature LDs, and define a molecular role for seipin in this process, most likely by acting at ER-LD contact sites to enable lipid transfer to nascent LDs.
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Affiliation(s)
- Huajin Wang
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, United States.,Department of Genetics and Complex Diseases, Harvard T H Chan School of Public Health, Boston, United States.,Department of Cell Biology, Harvard Medical School, Boston, United States
| | - Michel Becuwe
- Department of Genetics and Complex Diseases, Harvard T H Chan School of Public Health, Boston, United States.,Department of Cell Biology, Harvard Medical School, Boston, United States
| | | | - Chandramohan Chitraju
- Department of Genetics and Complex Diseases, Harvard T H Chan School of Public Health, Boston, United States.,Department of Cell Biology, Harvard Medical School, Boston, United States
| | - Ashley J Porras
- Department of Genetics and Complex Diseases, Harvard T H Chan School of Public Health, Boston, United States.,Department of Cell Biology, Harvard Medical School, Boston, United States
| | - Morven M Graham
- Center for Cellular and Molecular Imaging, Department of Cell Biology, Yale School of Medicine, New Haven, United States
| | - Xinran N Liu
- Center for Cellular and Molecular Imaging, Department of Cell Biology, Yale School of Medicine, New Haven, United States
| | - Abdou Rachid Thiam
- Laboratoire de Physique Statistique, École Normale Supérieure, PSL Research University, Université Paris Diderot Sorbonne Paris-Cité, Sorbonne Universités UPMC Univ Paris 06, CNRS UMR 8550, Paris, France
| | - David B Savage
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, United Kingdom
| | - Anil K Agarwal
- Division of Nutrition and Metabolic Diseases, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, United States
| | - Abhimanyu Garg
- Division of Nutrition and Metabolic Diseases, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, United States
| | - Maria-Jesus Olarte
- Department of Genetics and Complex Diseases, Harvard T H Chan School of Public Health, Boston, United States.,Department of Cell Biology, Harvard Medical School, Boston, United States
| | - Qingqing Lin
- Department of Genetics and Complex Diseases, Harvard T H Chan School of Public Health, Boston, United States.,Department of Cell Biology, Harvard Medical School, Boston, United States
| | - Florian Fröhlich
- Department of Genetics and Complex Diseases, Harvard T H Chan School of Public Health, Boston, United States.,Department of Cell Biology, Harvard Medical School, Boston, United States.,Molecular Membrane Biology Section, Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Hans Kristian Hannibal-Bach
- VILLUM Center for Bioanalytical Sciences, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Srigokul Upadhyayula
- Department of Cell Biology, Harvard Medical School, Boston, United States.,Department of Pediatrics, Harvard Medical School, Boston, United States.,Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, United States
| | - Norbert Perrimon
- Department of Genetics, Harvard Medical School, Boston, United States.,Howard Hughes Medical Institute, Boston, United States
| | - Tomas Kirchhausen
- Department of Cell Biology, Harvard Medical School, Boston, United States.,Department of Pediatrics, Harvard Medical School, Boston, United States.,Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, United States
| | - Christer S Ejsing
- VILLUM Center for Bioanalytical Sciences, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Tobias C Walther
- Department of Genetics and Complex Diseases, Harvard T H Chan School of Public Health, Boston, United States.,Department of Cell Biology, Harvard Medical School, Boston, United States.,Howard Hughes Medical Institute, Boston, United States.,Broad Institute of Harvard and MIT, Cambridge, United States
| | - Robert V Farese
- Department of Genetics and Complex Diseases, Harvard T H Chan School of Public Health, Boston, United States.,Department of Cell Biology, Harvard Medical School, Boston, United States.,Broad Institute of Harvard and MIT, Cambridge, United States
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Choi SK, Park S, Jang S, Cho HH, Lee S, You S, Kim SH, Moon HS. Cascade regulation of PPARγ(2) and C/EBPα signaling pathways by celastrol impairs adipocyte differentiation and stimulates lipolysis in 3T3-L1 adipocytes. Metabolism 2016; 65:646-654. [PMID: 27085773 DOI: 10.1016/j.metabol.2016.01.009] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 01/05/2016] [Accepted: 01/20/2016] [Indexed: 11/21/2022]
Abstract
OBJECTIVE Celastrol, a triterpene from the root bark of the Chinese medicinal plant Tripterygium wilfordii, has been shown to exhibit anti-oxidant, anti-inflammatory, anti-cancer and insecticidal activities. Also, it has been demonstrated that celastrol has obesity-controlling effects in diet-induced obesity mice. However, direct evidence that celastrol contributes to the development of adipocyte differentiation and lipolysis has not been fully elucidated. Moreover, no previous studies have evaluated whether celastrol may regulate adipogenic transcriptional markers in adipocytes. MATERIALS/METHODS In order to address the questions above, we extended previous observations and investigated in vitro celastrol signaling study whether celastrol may regulate differentiation, lipolysis and key adipogenic transcriptional pathways in 3T3-L1 adipocytes. RESULTS Treatment of celastrol not only inhibited adipocyte differentiation (lipid accumulation, glyceraldehyde-3-phosphate dehydrogenase activity and triglyceride content) but also increased lipolysis (glycerol release and free fatty acid release) in 3T3-L1 adipocytes. In addition, all celastrol-regulated functional activities were controlled by PPARγ(2) and C/EBPα signaling pathways in duration of celastrol's treatment in 3T3-L1 adipocytes. CONCLUSION Our initial data from in vitro celastrol signaling studies suggest novel insights into the role of PPARγ(2) and C/EBPα as probable mediators of the action of celastrol in regulating adipocyte differentiation and lipolysis in 3T3-L1 adipocytes.
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Affiliation(s)
- Seung Kug Choi
- Laboratory of Metabolic Engineering, Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul 02841, South Korea; Institute of Animal Molecular Biotechnology, Korea University, Seoul 02841, South Korea
| | - Sunmi Park
- Laboratory of Metabolic Engineering, Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul 02841, South Korea; Institute of Animal Molecular Biotechnology, Korea University, Seoul 02841, South Korea
| | - Subin Jang
- Laboratory of Metabolic Engineering, Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul 02841, South Korea; Institute of Animal Molecular Biotechnology, Korea University, Seoul 02841, South Korea
| | - Hun Hee Cho
- Laboratory of Metabolic Engineering, Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul 02841, South Korea; Institute of Animal Molecular Biotechnology, Korea University, Seoul 02841, South Korea
| | - Siwoo Lee
- Mibyeong Research Center, Korea Institute of Oriental Medicine, Daejeon 34054, South Korea
| | - Seungkwon You
- Institute of Animal Molecular Biotechnology, Korea University, Seoul 02841, South Korea; Cell Function Regulation Laboratory, Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul 02841, South Korea
| | - Sang-Hyuk Kim
- Mibyeong Research Center, Korea Institute of Oriental Medicine, Daejeon 34054, South Korea.
| | - Hyun-Seuk Moon
- Laboratory of Metabolic Engineering, Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul 02841, South Korea; Institute of Animal Molecular Biotechnology, Korea University, Seoul 02841, South Korea; Biomedical Research Center of Guro Hospital, Research Driven Hospital, Korea University, Seoul 08308, South Korea.
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75
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D'Aquila T, Hung YH, Carreiro A, Buhman KK. Recent discoveries on absorption of dietary fat: Presence, synthesis, and metabolism of cytoplasmic lipid droplets within enterocytes. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:730-47. [PMID: 27108063 DOI: 10.1016/j.bbalip.2016.04.012] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 03/16/2016] [Accepted: 04/16/2016] [Indexed: 02/07/2023]
Abstract
Dietary fat provides essential nutrients, contributes to energy balance, and regulates blood lipid concentrations. These functions are important to health, but can also become dysregulated and contribute to diseases such as obesity, diabetes, cardiovascular disease, and cancer. Within enterocytes, the digestive products of dietary fat are re-synthesized into triacylglycerol, which is either secreted on chylomicrons or stored within cytoplasmic lipid droplets (CLDs). CLDs were originally thought to be inert stores of neutral lipids, but are now recognized as dynamic organelles that function in multiple cellular processes in addition to lipid metabolism. This review will highlight recent discoveries related to dietary fat absorption with an emphasis on the presence, synthesis, and metabolism of CLDs within this process.
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Affiliation(s)
- Theresa D'Aquila
- Department of Nutrition Science, Purdue University, West Lafayette, IN 47907, USA
| | - Yu-Han Hung
- Department of Nutrition Science, Purdue University, West Lafayette, IN 47907, USA
| | - Alicia Carreiro
- Department of Nutrition Science, Purdue University, West Lafayette, IN 47907, USA
| | - Kimberly K Buhman
- Department of Nutrition Science, Purdue University, West Lafayette, IN 47907, USA.
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76
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Tschapalda K, Zhang YQ, Liu L, Golovnina K, Schlemper T, Eichmann TO, Lal-Nag M, Sreenivasan U, McLenithan J, Ziegler S, Sztalryd C, Lass A, Auld D, Oliver B, Waldmann H, Li Z, Shen M, Boxer MB, Beller M. A Class of Diacylglycerol Acyltransferase 1 Inhibitors Identified by a Combination of Phenotypic High-throughput Screening, Genomics, and Genetics. EBioMedicine 2016; 8:49-59. [PMID: 27428418 PMCID: PMC4919474 DOI: 10.1016/j.ebiom.2016.04.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 04/02/2016] [Accepted: 04/12/2016] [Indexed: 12/13/2022] Open
Abstract
Excess lipid storage is an epidemic problem in human populations. Thus, the identification of small molecules to treat or prevent lipid storage-related metabolic complications is of great interest. Here we screened > 320.000 compounds for their ability to prevent a cellular lipid accumulation phenotype. We used fly cells because the multifarious tools available for this organism should facilitate unraveling the mechanism-of-action of active small molecules. Of the several hundred lipid storage inhibitors identified in the primary screen we concentrated on three structurally diverse and potent compound classes active in cells of multiple species (including human) and negligible cytotoxicity. Together with Drosophila in vivo epistasis experiments, RNA-Seq expression profiles suggested that the target of one of the small molecules was diacylglycerol acyltransferase 1 (DGAT1), a key enzyme in the production of triacylglycerols and prominent human drug target. We confirmed this prediction by biochemical and enzymatic activity tests. We identified > 600 potent small molecule inhibitors of cellular lipid storage deposition. RNA-Seq expression profiling discriminated the activity of three lead scaffolds and guided subsequent functional studies. We discovered a class of DGAT1 inhibitors, which is active in fly and mammalian cell lines as well as whole flies.
Obesity and other lipid storage associated diseases are a growing health threat of human populations. In an undirected phenotypic screen, we identified pharmacologically active small molecules that reduce or enhance lipid storage. Our work focuses on three lead structures that prevent lipid storage in diverse cellular systems including cells from a diabetes patient. In order to elucidate the compound mechanisms-of-action and cellular targets, we used a combination of RNA-Seq transcriptional profiling and diverse functional assays. Our results strongly suggest that one of our lead structures represents a class of inhibitors targeting the key lipogenic enzyme diacylglycerol acyltransferase 1.
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Affiliation(s)
- Kirsten Tschapalda
- Systems Biology of Lipid Metabolism, Heinrich Heine University Düsseldorf, Germany; Institute for Mathematical Modeling of Biological Systems, Heinrich Heine University Düsseldorf, Germany; Department of Chemical Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany; Department of Molecular Developmental Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Ya-Qin Zhang
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, USA
| | - Li Liu
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, USA
| | - Kseniya Golovnina
- National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, USA
| | - Thomas Schlemper
- Systems Biology of Lipid Metabolism, Heinrich Heine University Düsseldorf, Germany; Institute for Mathematical Modeling of Biological Systems, Heinrich Heine University Düsseldorf, Germany
| | | | - Madhu Lal-Nag
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, USA
| | - Urmila Sreenivasan
- Department of Medicine, Division of Endocrinology University of Maryland School of Medicine, USA
| | - John McLenithan
- Department of Medicine, Division of Endocrinology University of Maryland School of Medicine, USA
| | - Slava Ziegler
- Department of Chemical Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Carole Sztalryd
- Department of Medicine, Division of Endocrinology University of Maryland School of Medicine, USA; Baltimore VA Medical Center, VA Research Service, Geriatric Research, Education and Clinical Center (GRECC) and VA Maryland Health Care System, Department of Medicine, Division of Endocrinology University of Maryland School of Medicine, USA
| | - Achim Lass
- Institute of Molecular Biosciences, University of Graz, Austria
| | - Douglas Auld
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, USA
| | - Brian Oliver
- National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, USA
| | - Herbert Waldmann
- Department of Chemical Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Zhuyin Li
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, USA
| | - Min Shen
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, USA
| | - Matthew B Boxer
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, USA
| | - Mathias Beller
- Systems Biology of Lipid Metabolism, Heinrich Heine University Düsseldorf, Germany; Institute for Mathematical Modeling of Biological Systems, Heinrich Heine University Düsseldorf, Germany.
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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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78
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Targeting Fat: Mechanisms of Protein Localization to Lipid Droplets. Trends Cell Biol 2016; 26:535-546. [PMID: 26995697 DOI: 10.1016/j.tcb.2016.02.007] [Citation(s) in RCA: 206] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 02/22/2016] [Accepted: 02/23/2016] [Indexed: 12/18/2022]
Abstract
How proteins specifically localize to the phospholipid monolayer surface of lipid droplets (LDs) is being unraveled. We review here the major known pathways of protein targeting to LDs and suggest a classification framework based on the localization origin for the protein. Class I proteins often have a membrane-embedded, hydrophobic 'hairpin' motif, and access LDs from the endoplasmic reticulum (ER) either during LD formation or after formation via ER-LD membrane bridges. Class II proteins access the LD surface from the cytosol and bind through amphipathic helices or other hydrophobic domains. Other proteins require lipid modifications or protein-protein interactions to bind to LDs. We summarize knowledge for targeting and removal of the different classes, and highlight areas needing investigation.
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79
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Choudhary V, Ojha N, Golden A, Prinz WA. A conserved family of proteins facilitates nascent lipid droplet budding from the ER. J Cell Biol 2016; 211:261-71. [PMID: 26504167 PMCID: PMC4621845 DOI: 10.1083/jcb.201505067] [Citation(s) in RCA: 200] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Visualization of nascent lipid droplets reveals that they form lens-like structures inside the ER membrane bilayer and that FIT proteins are necessary for lipid droplet protrusion toward the cytoplasm. Lipid droplets (LDs) are found in all cells and play critical roles in lipid metabolism. De novo LD biogenesis occurs in the endoplasmic reticulum (ER) but is not well understood. We imaged early stages of LD biogenesis using electron microscopy and found that nascent LDs form lens-like structures that are in the ER membrane, raising the question of how these nascent LDs bud from the ER as they grow. We found that a conserved family of proteins, fat storage-inducing transmembrane (FIT) proteins, is required for proper budding of LDs from the ER. Elimination or reduction of FIT proteins in yeast and higher eukaryotes causes LDs to remain in the ER membrane. Deletion of the single FIT protein in Caenorhabditis elegans is lethal, suggesting that LD budding is an essential process in this organism. Our findings indicated that FIT proteins are necessary to promote budding of nascent LDs from the ER.
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Affiliation(s)
- Vineet Choudhary
- Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Namrata Ojha
- Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Andy Golden
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
| | - William A Prinz
- Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
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80
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Inborn Errors of Long-Chain Fatty Acid β-Oxidation Link Neural Stem Cell Self-Renewal to Autism. Cell Rep 2016; 14:991-999. [PMID: 26832401 DOI: 10.1016/j.celrep.2016.01.004] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 10/23/2015] [Accepted: 12/28/2015] [Indexed: 12/27/2022] Open
Abstract
Inborn errors of metabolism (IEMs) occur with high incidence in human populations. Especially prevalent among these are inborn deficiencies in fatty acid β-oxidation (FAO), which are clinically associated with developmental neuropsychiatric disorders, including autism. We now report that neural stem cell (NSC)-autonomous insufficiencies in the activity of TMLHE (an autism risk factor that supports long-chain FAO by catalyzing carnitine biosynthesis), of CPT1A (an enzyme required for long-chain FAO transport into mitochondria), or of fatty acid mobilization from lipid droplets reduced NSC pools in the mouse embryonic neocortex. Lineage tracing experiments demonstrated that reduced flux through the FAO pathway potentiated NSC symmetric differentiating divisions at the expense of self-renewing stem cell division modes. The collective data reveal a key role for FAO in controlling NSC-to-IPC transition in the mammalian embryonic brain and suggest NSC self renewal as a cellular mechanism underlying the association between IEMs and autism.
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81
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Zhang I, Cui Y, Amiri A, Ding Y, Campbell RE, Maysinger D. Pharmacological inhibition of lipid droplet formation enhances the effectiveness of curcumin in glioblastoma. Eur J Pharm Biopharm 2016; 100:66-76. [PMID: 26763536 DOI: 10.1016/j.ejpb.2015.12.008] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 12/14/2015] [Accepted: 12/18/2015] [Indexed: 02/08/2023]
Abstract
Increased lipid droplet number and fatty acid synthesis allow glioblastoma multiforme, the most common and aggressive type of brain cancer, to withstand accelerated metabolic rates and resist therapeutic treatments. Lipid droplets are postulated to sequester hydrophobic therapeutic agents, thereby reducing drug effectiveness. We hypothesized that the inhibition of lipid droplet accumulation in glioblastoma cells using pyrrolidine-2, a cytoplasmic phospholipase A2 alpha inhibitor, can sensitize cancer cells to the killing effect of curcumin, a promising anticancer agent isolated from the turmeric spice. We observed that curcumin localized in the lipid droplets of human U251N glioblastoma cells. Reduction of lipid droplet number using pyrrolidine-2 drastically enhanced the therapeutic effect of curcumin in both 2D and 3D glioblastoma cell models. The mode of cell death involved was found to be mediated by caspase-3. Comparatively, the current clinical chemotherapeutic standard, temozolomide, was significantly less effective in inducing glioblastoma cell death. Together, our results suggest that the inhibition of lipid droplet accumulation is an effective way to enhance the chemotherapeutic effect of curcumin against glioblastoma multiforme.
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Affiliation(s)
- Issan Zhang
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | - Yiming Cui
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | - Abdolali Amiri
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | - Yidan Ding
- Department of Chemistry, University of Alberta, Edmonton, Canada
| | | | - Dusica Maysinger
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada.
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82
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Heymsfield SB, Hu HH, Shen W, Carmichael O. Emerging Technologies and their Applications in Lipid Compartment Measurement. Trends Endocrinol Metab 2015; 26:688-698. [PMID: 26596676 PMCID: PMC4673021 DOI: 10.1016/j.tem.2015.10.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 10/19/2015] [Accepted: 10/19/2015] [Indexed: 12/22/2022]
Abstract
Non-Communicable diseases (NCDs), including obesity, are emerging as the major health concern of the 21st century. Excess adiposity and related NCD metabolic disturbances have stimulated development of new lipid compartment measurement technologies to help us to understand cellular energy exchange, to refine phenotypes, and to develop predictive markers of adverse clinical outcomes. Recent advances now allow quantification of multiple intracellular lipid and adipose tissue compartments that can be evaluated across the human lifespan. With magnetic resonance methods leading the way, newer approaches will give molecular structural and metabolic information beyond the laboratory in real-world settings. The union between these new technologies and the growing NCD population is creating an exciting interface in advancing our understanding of chronic disease mechanisms.
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Affiliation(s)
- Steven B Heymsfield
- Pennington Biomedical Research Center, Louisiana State University (LSU) System, 6400 Perkins Road, Baton Rouge, LA 70808, USA.
| | - Houchun Harry Hu
- Phoenix Children's Hospital, Department of Radiology, 1919 East Thomas Road, Phoenix, AZ 85016, USA
| | - Wei Shen
- New York Obesity Research Center, Department of Pediatrics and Institute of Human Nutrition, Columbia University, New York, NY 10032, USA
| | - Owen Carmichael
- Pennington Biomedical Research Center, Louisiana State University (LSU) System, 6400 Perkins Road, Baton Rouge, LA 70808, USA
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83
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Kentala H, Weber-Boyvat M, Olkkonen VM. OSBP-Related Protein Family: Mediators of Lipid Transport and Signaling at Membrane Contact Sites. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 321:299-340. [PMID: 26811291 DOI: 10.1016/bs.ircmb.2015.09.006] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Oxysterol-binding protein (OSBP) and its related protein homologs, ORPs, constitute a conserved family of lipid-binding/transfer proteins (LTPs) expressed ubiquitously in eukaryotes. The ligand-binding domain of ORPs accommodates cholesterol and oxysterols, but also glycerophospholipids, particularly phosphatidylinositol-4-phosphate (PI4P). ORPs have been implicated as intracellular lipid sensors or transporters. Most ORPs carry targeting determinants for the endoplasmic reticulum (ER) and non-ER organelle membrane. ORPs are located and function at membrane contact sites (MCSs), at which ER is closely apposed with other organelle limiting membranes. Such sites have roles in lipid transport and metabolism, control of Ca(2+) fluxes, and signaling events. ORPs are postulated either to transport lipids over MCSs to maintain the distinct lipid compositions of organelle membranes, or to control the activity of enzymes/protein complexes with functions in signaling and lipid metabolism. ORPs may transfer PI4P and another lipid class bidirectionally. Transport of PI4P followed by its hydrolysis would in this model provide the energy for transfer of the other lipid against its concentration gradient. Control of organelle lipid compositions by OSBP/ORPs is important for the life cycles of several pathogenic viruses. Targeting ORPs with small-molecular antagonists is proposed as a new strategy to combat viral infections. Several ORPs are reported to modulate vesicle transport along the secretory or endocytic pathways. Moreover, antagonists of certain ORPs inhibit cancer cell proliferation. Thus, ORPs are LTPs, which mediate interorganelle lipid transport and coordinate lipid signals with a variety of cellular regimes.
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Affiliation(s)
- Henriikka Kentala
- Minerva Foundation Institute for Medical Research, Biomedicum 2U, Helsinki, Finland
| | - Marion Weber-Boyvat
- Minerva Foundation Institute for Medical Research, Biomedicum 2U, Helsinki, Finland
| | - Vesa M Olkkonen
- Minerva Foundation Institute for Medical Research, Biomedicum 2U, Helsinki, Finland
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84
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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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85
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Hepatitis C virus and lipid droplets: finding a niche. Trends Mol Med 2014; 21:34-42. [PMID: 25496657 DOI: 10.1016/j.molmed.2014.11.003] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2014] [Revised: 11/11/2014] [Accepted: 11/17/2014] [Indexed: 12/14/2022]
Abstract
Hepatitis C virus (HCV) causes serious liver disease in chronically infected individuals. Infectious virions are released from hepatocytes as lipoprotein complexes, indicating that the virus interacts with very low density lipoprotein (VLDL) assembly to propagate. The primary source of lipid for incorporation into VLDL is cytoplasmic lipid droplets (LDs). This organelle is targeted by two virus-encoded proteins as part of a process essential for virion morphogenesis. Moreover, LDs regulate infection. A common condition in HCV-infected individuals is steatosis, characterized by an accumulation of LDs. The mechanisms underlying development of steatosis include direct effects of the virus on lipid metabolism. This review reveals new insights into HCV infection and a further twist to the growing list of functions performed by LDs.
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