51
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Chen F, Yan B, Ren J, Lyu R, Wu Y, Guo Y, Li D, Zhang H, Hu J. FIT2 organizes lipid droplet biogenesis with ER tubule-forming proteins and septins. J Cell Biol 2021; 220:211999. [PMID: 33861319 PMCID: PMC8056755 DOI: 10.1083/jcb.201907183] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 12/29/2020] [Accepted: 02/09/2021] [Indexed: 12/20/2022] Open
Abstract
Lipid droplets (LDs) are critical for lipid storage and energy metabolism. LDs form in the endoplasmic reticulum (ER). However, the molecular basis for LD biogenesis remains elusive. Here, we show that fat storage–inducing transmembrane protein 2 (FIT2) interacts with ER tubule-forming proteins Rtn4 and REEP5. The association is mainly transmembrane domain based and stimulated by oleic acid. Depletion of ER tubule-forming proteins decreases the number and size of LDs in cells and Caenorhabditis elegans, mimicking loss of FIT2. Through cytosolic loops, FIT2 binds to cytoskeletal protein septin 7, an interaction that is also required for normal LD biogenesis. Depletion of ER tubule-forming proteins or septins delays nascent LD formation. In addition, FIT2-interacting proteins are up-regulated during adipocyte differentiation, and ER tubule-forming proteins, septin 7, and FIT2 are transiently enriched at LD formation sites. Thus, FIT2-mediated nascent LD biogenesis is facilitated by ER tubule-forming proteins and septins.
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Affiliation(s)
- Fang Chen
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Bing Yan
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Jie Ren
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Rui Lyu
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yanfang Wu
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Yuting Guo
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Dong Li
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Hong Zhang
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Junjie Hu
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
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52
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Choudhary V, Schneiter R. A Unique Junctional Interface at Contact Sites Between the Endoplasmic Reticulum and Lipid Droplets. Front Cell Dev Biol 2021; 9:650186. [PMID: 33898445 PMCID: PMC8060488 DOI: 10.3389/fcell.2021.650186] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 03/09/2021] [Indexed: 12/19/2022] Open
Abstract
Lipid droplets (LDs) constitute compartments dedicated to the storage of metabolic energy in the form of neutral lipids. LDs originate from the endoplasmic reticulum (ER) with which they maintain close contact throughout their life cycle. These ER-LD junctions facilitate the exchange of both proteins and lipids between these two compartments. In recent years, proteins that are important for the proper formation of LDs and localize to ER-LD junctions have been identified. This junction is unique as it is generally believed to invoke a transition from the ER bilayer membrane to a lipid monolayer that delineates LDs. Proper formation of this junction requires the ordered assembly of proteins and lipids at specialized ER subdomains. Without such a well-ordered assembly of LD biogenesis factors, neutral lipids are synthesized throughout the ER membrane, resulting in the formation of aberrant LDs. Such ectopically formed LDs impact ER and lipid homeostasis, resulting in different types of lipid storage diseases. In response to starvation, the ER-LD junction recruits factors that tether the vacuole to these junctions to facilitate LD degradation. In addition, LDs maintain close contacts with peroxisomes and mitochondria for metabolic channeling of the released fatty acids toward beta-oxidation. In this review, we discuss the function of different components that ensure proper functioning of LD contact sites, their role in lipogenesis and lipolysis, and their relation to lipid storage diseases.
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Affiliation(s)
- Vineet Choudhary
- Department of Biotechnology, All India Institute of Medical Sciences (AIIMS), New Delhi, India
| | - Roger Schneiter
- Department of Biology, University of Fribourg, Fribourg, Switzerland
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53
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Motility Plays an Important Role in the Lifetime of Mammalian Lipid Droplets. Int J Mol Sci 2021; 22:ijms22083802. [PMID: 33916886 PMCID: PMC8067576 DOI: 10.3390/ijms22083802] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 03/25/2021] [Accepted: 04/01/2021] [Indexed: 01/31/2023] Open
Abstract
The lipid droplet is a kind of organelle that stores neutral lipids in cells. Recent studies have found that in addition to energy storage, lipid droplets also play an important role in biological processes such as resistance to stress, immunity, cell proliferation, apoptosis, and signal transduction. Lipid droplets are formed at the endoplasmic reticulum, and mature lipid droplets participate in various cellular processes. Lipid droplets are decomposed by lipase and lysosomes. In the life of a lipid droplet, the most important thing is to interact with other organelles, including the endoplasmic reticulum, mitochondria, peroxisomes, and autophagic lysosomes. The interaction between lipid droplets and other organelles requires them to be close to each other, which inevitably involves the motility of lipid droplets. In fact, through many microscopic observation techniques, researchers have discovered that lipid droplets are highly dynamic organelles that move quickly. This paper reviews the process of lipid droplet motility, focusing on explaining the molecular basis of lipid droplet motility, the factors that regulate lipid droplet motility, and the influence of motility on the formation and decomposition of lipid droplets. In addition, this paper also proposes several unresolved problems for lipid droplet motility. Finally, this paper makes predictions about the future research of lipid droplet motility.
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54
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Zoni V, Khaddaj R, Lukmantara I, Shinoda W, Yang H, Schneiter R, Vanni S. Seipin accumulates and traps diacylglycerols and triglycerides in its ring-like structure. Proc Natl Acad Sci U S A 2021; 118:e2017205118. [PMID: 33674387 PMCID: PMC7958289 DOI: 10.1073/pnas.2017205118] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Lipid droplets (LDs) are intracellular organelles responsible for lipid storage, and they emerge from the endoplasmic reticulum (ER) upon the accumulation of neutral lipids, mostly triglycerides (TG), between the two leaflets of the ER membrane. LD biogenesis takes place at ER sites that are marked by the protein seipin, which subsequently recruits additional proteins to catalyze LD formation. Deletion of seipin, however, does not abolish LD biogenesis, and its precise role in controlling LD assembly remains unclear. Here, we use molecular dynamics simulations to investigate the molecular mechanism through which seipin promotes LD formation. We find that seipin clusters TG, as well as its precursor diacylglycerol, inside its unconventional ring-like oligomeric structure and that both its luminal and transmembrane regions contribute to this process. This mechanism is abolished upon mutations of polar residues involved in protein-TG interactions into hydrophobic residues. Our results suggest that seipin remodels the membrane of specific ER sites to prime them for LD biogenesis.
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Affiliation(s)
- Valeria Zoni
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Rasha Khaddaj
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Ivan Lukmantara
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Wataru Shinoda
- Department of Materials Chemistry, Nagoya University, Chikusa-ku, 464-8603 Nagoya, Japan
| | - Hongyuan Yang
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Roger Schneiter
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Stefano Vanni
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland;
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55
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Herker E, Vieyres G, Beller M, Krahmer N, Bohnert M. Lipid Droplet Contact Sites in Health and Disease. Trends Cell Biol 2021; 31:345-358. [PMID: 33546922 DOI: 10.1016/j.tcb.2021.01.004] [Citation(s) in RCA: 80] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 01/05/2021] [Accepted: 01/08/2021] [Indexed: 01/04/2023]
Abstract
After having been disregarded for a long time as inert fat drops, lipid droplets (LDs) are now recognized as ubiquitous cellular organelles with key functions in lipid biology and beyond. The identification of abundant LD contact sites, places at which LDs are physically attached to other organelles, has uncovered an unexpected level of communication between LDs and the rest of the cell. In recent years, many disease factors mutated in hereditary disorders have been recognized as LD contact site proteins. Furthermore, LD contact sites are dramatically rearranged in response to infections with intracellular pathogens, as well as under pathological metabolic conditions such as hepatic steatosis. Collectively, it is emerging that LD-organelle contacts are important players in development and progression of disease.
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Affiliation(s)
- Eva Herker
- Institute of Virology, Philipps-University Marburg, 35043 Marburg, Germany.
| | - Gabrielle Vieyres
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany; Leibniz ScienceCampus InterACt, Hamburg, Germany.
| | - Mathias Beller
- Institute for Mathematical Modeling of Biological Systems, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany; Systems Biology of Lipid Metabolism, Heinrich Heine University Düsseldorf, Germany.
| | - Natalie Krahmer
- Institute for Diabetes and Obesity, Helmholtz Zentrum München, 85764 Neuherberg, Germany; German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany.
| | - Maria Bohnert
- Institute of Cell Dynamics and Imaging, University of Münster, 48149 Münster, Germany; Cells in Motion Interfaculty Centre (CiM), University of Münster, Münster, Germany.
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56
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Prasanna X, Salo VT, Li S, Ven K, Vihinen H, Jokitalo E, Vattulainen I, Ikonen E. Seipin traps triacylglycerols to facilitate their nanoscale clustering in the endoplasmic reticulum membrane. PLoS Biol 2021; 19:e3000998. [PMID: 33481779 PMCID: PMC7857593 DOI: 10.1371/journal.pbio.3000998] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 02/03/2021] [Accepted: 11/02/2020] [Indexed: 11/19/2022] Open
Abstract
Seipin is a disk-like oligomeric endoplasmic reticulum (ER) protein important for lipid droplet (LD) biogenesis and triacylglycerol (TAG) delivery to growing LDs. Here we show through biomolecular simulations bridged to experiments that seipin can trap TAGs in the ER bilayer via the luminal hydrophobic helices of the protomers delineating the inner opening of the seipin disk. This promotes the nanoscale sequestration of TAGs at a concentration that by itself is insufficient to induce TAG clustering in a lipid membrane. We identify Ser166 in the α3 helix as a favored TAG occupancy site and show that mutating it compromises the ability of seipin complexes to sequester TAG in silico and to promote TAG transfer to LDs in cells. While the S166D-seipin mutant colocalizes poorly with promethin, the association of nascent wild-type seipin complexes with promethin is promoted by TAGs. Together, these results suggest that seipin traps TAGs via its luminal hydrophobic helices, serving as a catalyst for seeding the TAG cluster from dissolved monomers inside the seipin ring, thereby generating a favorable promethin binding interface.
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Affiliation(s)
- Xavier Prasanna
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Veijo T. Salo
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Shiqian Li
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Katharina Ven
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Helena Vihinen
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Eija Jokitalo
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Ilpo Vattulainen
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Elina Ikonen
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
- * E-mail:
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57
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Klemm RW. Getting in Touch Is an Important Step: Control of Metabolism at Organelle Contact Sites. CONTACT (THOUSAND OAKS (VENTURA COUNTY, CALIF.)) 2021; 4:2515256421993708. [PMID: 37366381 PMCID: PMC10243586 DOI: 10.1177/2515256421993708] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 01/19/2021] [Accepted: 01/19/2021] [Indexed: 06/28/2023]
Abstract
Metabolic pathways are often spread over several organelles and need to be functionally integrated by controlled organelle communication. Physical organelle contact-sites have emerged as critical hubs in the regulation of cellular metabolism, but the molecular understanding of mechanisms that mediate formation or regulation of organelle interfaces was until recently relatively limited. Mitochondria are central organelles in anabolic and catabolic pathways and therefore interact with a number of other cellular compartments including the endoplasmic reticulum (ER) and lipid droplets (LDs). An interesting set of recent work has shed new light on the molecular basis forming these contact sites. This brief overview describes the discovery of unanticipated functions of contact sites between the ER, mitochondria and LDs in de novo synthesis of storage lipids of brown and white adipocytes. Interestingly, the factors involved in mediating the interaction between these organelles are subject to unexpected modes of regulation through newly uncovered Phospho-FFAT motifs. These results suggest dynamic regulation of contact sites between organelles and indicate that spatial organization of organelles within the cell contributes to the control of metabolism.
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Affiliation(s)
- Robin W. Klemm
- Department of Physiology,
Anatomy and Genetics, University of Oxford, UK
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58
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Tashiro S, Kakimoto Y, Shinmyo M, Fujimoto S, Tamura Y. Improved Split-GFP Systems for Visualizing Organelle Contact Sites in Yeast and Human Cells. Front Cell Dev Biol 2020; 8:571388. [PMID: 33330450 PMCID: PMC7714769 DOI: 10.3389/fcell.2020.571388] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 10/26/2020] [Indexed: 12/27/2022] Open
Abstract
Inter-organelle contact sites have attracted a lot of attention as functionally specialized regions that mediate the exchange of metabolites, including lipids and ions, between distinct organelles. However, studies on inter-organelle contact sites are at an early stage and it remains enigmatic what directly mediates the organelle-organelle interactions and how the number and degree of the contacts are regulated. As a first step to answer these questions, we previously developed split-GFP probes that could visualize and quantify multiple inter-organelle contact sites in the yeast and human cultured cells. However, the split-GFP probes possessed a disadvantage of inducing artificial connections between two different organelle membranes, especially when overexpressed. In the present study, we developed a way to express the split-GFP probes whose expressions remained at low levels, with minimal variations between different yeast cells. Besides, we constructed a HeLa cell line in which the expression of the split-GFP probes could be induced by the addition of doxycycline to minimize the artificial effects. The improved split-GFP systems may be faithful tools to quantify organelle contact sites and screen new factors involved in organelle-organelle tethering in yeast and mammalian cells.
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Affiliation(s)
- Shinya Tashiro
- Faculty of Science, Yamagata University, Yamagata, Japan
| | - Yuriko Kakimoto
- Department of Biochemistry and Molecular Biology, Graduate School of Medical Science, Yamagata University, Yamagata, Japan
| | | | | | - Yasushi Tamura
- Faculty of Science, Yamagata University, Yamagata, Japan
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59
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High-Throughput Identification of Nuclear Envelope Protein Interactions in Schizosaccharomyces pombe Using an Arrayed Membrane Yeast-Two Hybrid Library. G3-GENES GENOMES GENETICS 2020; 10:4649-4663. [PMID: 33109728 PMCID: PMC7718735 DOI: 10.1534/g3.120.401880] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The nuclear envelope (NE) contains a specialized set of integral membrane proteins that maintain nuclear shape and integrity and influence chromatin organization and gene expression. Advances in proteomics techniques and studies in model organisms have identified hundreds of proteins that localize to the NE. However, the function of many of these proteins at the NE remains unclear, in part due to a lack of understanding of the interactions that these proteins participate in at the NE membrane. To assist in the characterization of NE transmembrane protein interactions we developed an arrayed library of integral and peripheral membrane proteins from the fission yeast Schizosaccharomyces pombe for high-throughput screening using the split-ubiquitin based membrane yeast two -hybrid system. We used this approach to characterize protein interactions for three conserved proteins that localize to the inner nuclear membrane: Cut11/Ndc1, Lem2 and Ima1/Samp1/Net5. Additionally, we determined how the interaction network for Cut11 is altered in canonical temperature-sensitive cut11-ts mutants. This library and screening approach is readily applicable to characterizing the interactomes of integral membrane proteins localizing to various subcellular compartments.
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60
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New friends for seipin — Implications of seipin partner proteins in the life cycle of lipid droplets. Semin Cell Dev Biol 2020; 108:24-32. [DOI: 10.1016/j.semcdb.2020.04.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 03/20/2020] [Accepted: 04/17/2020] [Indexed: 12/31/2022]
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61
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Huang J, Chen X, Zhang F, Lin M, Lin G, Zhang Z. Lipid Droplet Metabolism Across Eukaryotes: Evidence from Yeast to Humans. J EVOL BIOCHEM PHYS+ 2020. [DOI: 10.1134/s0022093020050026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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62
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Jin Y, Tan Y, Zhao P, Ren Z. SEIPIN: A Key Factor for Nuclear Lipid Droplet Generation and Lipid Homeostasis. Int J Mol Sci 2020; 21:ijms21218208. [PMID: 33147895 PMCID: PMC7663086 DOI: 10.3390/ijms21218208] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 10/27/2020] [Accepted: 10/28/2020] [Indexed: 12/28/2022] Open
Abstract
Lipid homeostasis is essential for normal cell physiology. Generally, lipids are stored in a lipid droplet (LD), a ubiquitous organelle consisting of a neutral lipid core and a single layer of phospholipid membrane. It is thought that LDs are generated from the endoplasmic reticulum and then released into the cytosol. Recent studies indicate that LDs can exist in the nucleus, where they play an important role in the maintenance of cell phospholipid homeostasis. However, the details of nuclear lipid droplet (nLD) generation have not yet been clearly characterized. SEIPIN is a nonenzymatic protein encoded by the Berardinelli-Seip congenital lipodystrophy type 2 (BSCL2) gene. It is associated with lipodystrophy diseases. Many recent studies have indicated that SEIPIN is essential for LDs generation. Here, we review much of this research in an attempt to explain the role of SEIPIN in nLD generation. From an integrative perspective, we conclude by proposing a theoretical model to explain how SEIPIN might participate in maintaining homeostasis of lipid metabolism.
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Affiliation(s)
- Yi Jin
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of the Ministry of Education & Key Laboratory of Swine Genetics and Breeding of the Ministry of Agriculture and Rural Affairs, College of Animal Science, Huazhong Agricultural University, Wuhan 430070, Hubei, China; (Y.J.); (Y.T.); (P.Z.)
- Bio-Medical Center of Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Yanjie Tan
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of the Ministry of Education & Key Laboratory of Swine Genetics and Breeding of the Ministry of Agriculture and Rural Affairs, College of Animal Science, Huazhong Agricultural University, Wuhan 430070, Hubei, China; (Y.J.); (Y.T.); (P.Z.)
- Institute of Biomedical Sciences, Key Laboratory of Animal Resistance Biology of Shandong Province, College of Life Sciences, Shandong Normal University, Jinan 250014, Shandong, China
| | - Pengxiang Zhao
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of the Ministry of Education & Key Laboratory of Swine Genetics and Breeding of the Ministry of Agriculture and Rural Affairs, College of Animal Science, Huazhong Agricultural University, Wuhan 430070, Hubei, China; (Y.J.); (Y.T.); (P.Z.)
| | - Zhuqing Ren
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of the Ministry of Education & Key Laboratory of Swine Genetics and Breeding of the Ministry of Agriculture and Rural Affairs, College of Animal Science, Huazhong Agricultural University, Wuhan 430070, Hubei, China; (Y.J.); (Y.T.); (P.Z.)
- Bio-Medical Center of Huazhong Agricultural University, Wuhan 430070, Hubei, China
- Correspondence:
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63
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Barbosa AD, Siniossoglou S. New kid on the block: lipid droplets in the nucleus. FEBS J 2020; 287:4838-4843. [PMID: 32243071 DOI: 10.1111/febs.15307] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 03/11/2020] [Accepted: 03/14/2020] [Indexed: 12/30/2022]
Abstract
The regulation of lipid homeostasis is essential for normal cell physiology, and its disruption can lead to disease. Lipid droplets (LDs) are ubiquitous organelles dedicated to storing nonpolar lipids that are used for metabolic energy production or membrane biogenesis. LDs normally emerge from, and associate with, the endoplasmic reticulum and interact with other cytoplasmic organelles to deliver the stored lipids. Recently, LDs were found to reside also at the inner side of the nuclear envelope and inside the nucleus in yeast and mammalian cells. This unexpected finding raises fundamental questions about the nature of the inner nuclear membrane, its connection with the endoplasmic reticulum and the pathways of LD formation. In this viewpoint, we will highlight recent developments relating to these questions and discuss possible roles of LDs in nuclear physiology.
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Affiliation(s)
- Antonio D Barbosa
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Symeon Siniossoglou
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
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64
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Bai X, Huang LJ, Chen SW, Nebenfuehr B, Wysolmerski B, Wu JC, Olson SK, Golden A, Wang CW. Loss of the seipin gene perturbs eggshell formation in Caenorhabditiselegans. Development 2020; 147:dev192997. [PMID: 32820022 PMCID: PMC7578359 DOI: 10.1242/dev.192997] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 08/11/2020] [Indexed: 12/13/2022]
Abstract
Seipin, an evolutionary conserved protein, plays pivotal roles during lipid droplet (LD) biogenesis and is associated with various human diseases with unclear mechanisms. Here, we analyzed Caenorhabditis elegans mutants deleted of the sole SEIPIN gene, seip-1 Homozygous seip-1 mutants displayed penetrant embryonic lethality, which is caused by the disruption of the lipid-rich permeability barrier, the innermost layer of the C. elegans embryonic eggshell. In C. elegans oocytes and embryos, SEIP-1 is associated with LDs and is crucial for controlling LD size and lipid homeostasis. The seip-1 deletion mutants reduced the ratio of polyunsaturated fatty acids (PUFAs) in their embryonic fatty acid pool. Interestingly, dietary supplementation of selected n-6 PUFAs rescued the embryonic lethality and defective permeability barrier. Accordingly, we propose that SEIP-1 may maternally regulate LD biogenesis and lipid homeostasis to orchestrate the formation of the permeability barrier for eggshell synthesis during embryogenesis. A lipodystrophy allele of seip-1 resulted in embryonic lethality as well and could be rescued by PUFA supplementation. These experiments support a great potential for using C. elegans to model SEIPIN-associated human diseases.
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Affiliation(s)
- Xiaofei Bai
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Leng-Jie Huang
- Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Taipei 11529, Taiwan
| | - Sheng-Wen Chen
- Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Taipei 11529, Taiwan
| | - Benjamin Nebenfuehr
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Brian Wysolmerski
- Department of Biology and Program in Molecular Biology, Pomona College, Claremont, CA 91711, USA
| | - Jui-Ching Wu
- Department of Clinical Laboratory Science and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei 10048, Taiwan
| | - Sara K Olson
- Department of Biology and Program in Molecular Biology, Pomona College, Claremont, CA 91711, USA
| | - Andy Golden
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Chao-Wen Wang
- Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Taipei 11529, Taiwan
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65
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Antidiabetic effects of novel ellagic acid nanoformulation: Insulin-secreting and anti-apoptosis effects. Saudi J Biol Sci 2020; 27:3474-3480. [PMID: 33304158 PMCID: PMC7715050 DOI: 10.1016/j.sjbs.2020.09.060] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 09/28/2020] [Accepted: 09/30/2020] [Indexed: 12/18/2022] Open
Abstract
Antioxidants are one of the effective treatment lines in managing type 2 diabetes (typ2diab) and its complications. Nanoformulations could help in ameliorating the oral bioavailability and biocompatibility properties. Ellagic acid (Ella) is a natural antioxidant compound commonly present in fruits. This study examined the effect Ella nanoparticles (Ella NPs) alone and combined with metformin, the standard antidiabetic drug, on controlling blood glucose in typ2diab. Forty-eight adult Sprague-Dawley rats were used in this study. Except for the control group that was fed a regular pellet diet, all animals were fed a high-fat diet (HFD) for 9 weeks. For the last 4 weeks, rats were injected with streptozotocin (35 mg/kg). Then the rats were randomized into 8 groups: control, HFD, diabetic, Ella, Ella + metformin, Ella NPs, and Ella NPs + metformin. Data showed that Ella NPs improved blood glucose levels and the body weights of diabetic rats throughout all the weeks of the experiment whereas effects of the regular Ella were limited to the last two weeks of the treatment. Additionally, data demonstrated that the antidiabetic action of Ella NPs and its effective duration were similar to metformin. Ella NPs led to a lowering effect on lipid profile markers (total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL), and very-low-density lipoprotein (VLDL)), superior to the regular Ella, which reduced only TG and VLDL. Results of the pathological examination showed improved number and activity of beta islets in all treatment groups. The most enhanced islets were in the Ella NPs and metformin group. The different treatments decreased caspase 3 and increased insulin gene expression, and the effect was superior in the Ella NPs and metformin group. The results of this study confirmed that Ella could manage typ2diab by lowering glucose and lipid levels and improving body weight with the superiority of Ella NPs. The mechanisms behind these effects are inhibition of beta-cell apoptosis and stimulation of insulin production.
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66
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Teixeira V, Maciel P, Costa V. Leading the way in the nervous system: Lipid Droplets as new players in health and disease. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1866:158820. [PMID: 33010453 DOI: 10.1016/j.bbalip.2020.158820] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 09/01/2020] [Accepted: 09/21/2020] [Indexed: 12/28/2022]
Abstract
Lipid droplets (LDs) are ubiquitous fat storage organelles composed of a neutral lipid core, comprising triacylglycerols (TAG) and sterol esters (SEs), surrounded by a phospholipid monolayer membrane with several decorating proteins. Recently, LD biology has come to the foreground of research due to their importance for energy homeostasis and cellular stress response. As aberrant LD accumulation and lipid depletion are hallmarks of numerous diseases, addressing LD biogenesis and turnover provides a new framework for understanding disease-related mechanisms. Here we discuss the potential role of LDs in neurodegeneration, while making some predictions on how LD imbalance can contribute to pathophysiology in the brain.
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Affiliation(s)
- Vitor Teixeira
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade of Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.
| | - Patrícia Maciel
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Vítor Costa
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade of Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal; ICBAS, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
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67
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Salo VT, Hölttä-Vuori M, Ikonen E. Seipin-Mediated Contacts as Gatekeepers of Lipid Flux at the Endoplasmic Reticulum–Lipid Droplet Nexus. ACTA ACUST UNITED AC 2020. [DOI: 10.1177/2515256420945820] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Lipid droplets (LDs) are dynamic cellular hubs of lipid metabolism. While LDs contact a plethora of organelles, they have the most intimate relationship with the endoplasmic reticulum (ER). Indeed, LDs are initially assembled at specialized ER subdomains, and recent work has unraveled an increasing array of proteins regulating ER-LD contacts. Among these, seipin, a highly conserved lipodystrophy protein critical for LD growth and adipogenesis, deserves special attention. Here, we review recent insights into the role of seipin in LD biogenesis and as a regulator of ER-LD contacts. These studies have also highlighted the evolving concept of ER and LDs as a functional continuum for lipid partitioning and pinpointed a role for seipin at the ER-LD nexus in controlling lipid flux between these compartments.
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Affiliation(s)
- Veijo T. Salo
- Department of Anatomy and Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Maarit Hölttä-Vuori
- Department of Anatomy and Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Elina Ikonen
- Department of Anatomy and Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
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68
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Triacylglycerols sequester monotopic membrane proteins to lipid droplets. Nat Commun 2020; 11:3944. [PMID: 32769983 PMCID: PMC7414839 DOI: 10.1038/s41467-020-17585-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 07/08/2020] [Indexed: 01/05/2023] Open
Abstract
Triacylglycerols (TG) are synthesized at the endoplasmic reticulum (ER) bilayer and packaged into organelles called lipid droplets (LDs). LDs are covered by a single phospholipid monolayer contiguous with the ER bilayer. This connection is used by several monotopic integral membrane proteins, with hydrophobic membrane association domains (HDs), to diffuse between the organelles. However, how proteins partition between ER and LDs is not understood. Here, we employed synthetic model systems and found that HD-containing proteins strongly prefer monolayers and returning to the bilayer is unfavorable. This preference for monolayers is due to a higher affinity of HDs for TG over membrane phospholipids. Protein distribution is regulated by PC/PE ratio via alterations in monolayer packing and HD-TG interaction. Thus, HD-containing proteins appear to non-specifically accumulate to the LD surface. In cells, protein editing mechanisms at the ER membrane would be necessary to prevent unspecific relocation of HD-containing proteins to LDs. Triacylglycerols (TG) are synthesized at the endoplasmic reticulum (ER) bilayer and packaged into monolayer lipid droplets (LDs), but how proteins partition between ER and LDs is poorly understood. Here authors use synthetic model systems and find that proteins containing hydrophobic membrane association domains strongly prefer monolayers and that returning to the bilayer is unfavorable.
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69
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Jiang G, Jin Y, Li M, Wang H, Xiong M, Zeng W, Yuan H, Liu C, Ren Z, Liu C. Faster and More Specific: Excited-State Intramolecular Proton Transfer-Based Dyes for High-Fidelity Dynamic Imaging of Lipid Droplets within Cells and Tissues. Anal Chem 2020; 92:10342-10349. [PMID: 32615751 DOI: 10.1021/acs.analchem.0c00390] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Lipid droplets (LDs), a type of dynamic organelle residing at the center of cellular lipid storage, have been identified to play important roles in multiple biological processes, metabolic disorders, and diseases. The highly dynamic characters of LDs were found to correspond to their physiological and pathological functions. Hence, the fluorescent probes which enable dynamic tracking of LDs should be very helpful for better understanding the mechanisms of LDs involved biological processes and diseases. Herein we present, to the best of our knowledge, the first class of excited-state intramolecular proton transfer (ESIPT) fluorescence dyes (Flp-(11-13, 19)) for dynamic imaging of LDs based on 3-hydroxyflavone (3HF) derivatives. Flp-(11-13, 19) display strong fluorescence from yellow to NIR in lipid but exhibit almost nonfluorescence in aqueous solution. Besides, they also show large Stokes shifts (>150 nm), narrow absorption and emission peaks, and good oil-water separation efficiency, which makes them specifically target and stain LDs with very low background noisy in both living cells and fixed cells. They stain intracellular LDs quite quickly (within 30 s) with very low dosage (as low as 500 nM). Benefitting from these advantages, Flp-(11-13, 19) are applied successfully in tracking the dynamic nature of LDs and accumulation of LDs in both aqueous solution and living cells, 3D imaging of LDs for visualization of their repartition within the cells, and visualizing LDs in tissues of diseases mice models including adipose, skeletal muscle, and fatty liver tissues, underscoring the potential utility of these dyes in both LDs biology research and medical diagnosis of LDs involved diseases.
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Affiliation(s)
- Gangwei Jiang
- Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, Chemical Biology Center, College of Chemistry, and International Joint Research Center for Intelligent Biosensing Technology and Health, Central China Normal University, Wuhan 430079, P. R. China
| | - Yi Jin
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of the Ministry of Education, College of Animal Science, Huazhong Agricultural University, Wuhan 430070, P. R. China
| | - Man Li
- Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, Chemical Biology Center, College of Chemistry, and International Joint Research Center for Intelligent Biosensing Technology and Health, Central China Normal University, Wuhan 430079, P. R. China
| | - Huiling Wang
- Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, Chemical Biology Center, College of Chemistry, and International Joint Research Center for Intelligent Biosensing Technology and Health, Central China Normal University, Wuhan 430079, P. R. China
| | - Mengyao Xiong
- Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, Chemical Biology Center, College of Chemistry, and International Joint Research Center for Intelligent Biosensing Technology and Health, Central China Normal University, Wuhan 430079, P. R. China
| | - Weili Zeng
- Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, Chemical Biology Center, College of Chemistry, and International Joint Research Center for Intelligent Biosensing Technology and Health, Central China Normal University, Wuhan 430079, P. R. China
| | - Hong Yuan
- Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, Chemical Biology Center, College of Chemistry, and International Joint Research Center for Intelligent Biosensing Technology and Health, Central China Normal University, Wuhan 430079, P. R. China
| | - Changlin Liu
- Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, Chemical Biology Center, College of Chemistry, and International Joint Research Center for Intelligent Biosensing Technology and Health, Central China Normal University, Wuhan 430079, P. R. China
| | - Zhuqing Ren
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of the Ministry of Education, College of Animal Science, Huazhong Agricultural University, Wuhan 430070, P. R. China
| | - Chunrong Liu
- Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, Chemical Biology Center, College of Chemistry, and International Joint Research Center for Intelligent Biosensing Technology and Health, Central China Normal University, Wuhan 430079, P. R. China
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70
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Choudhary V, El Atab O, Mizzon G, Prinz WA, Schneiter R. Seipin and Nem1 establish discrete ER subdomains to initiate yeast lipid droplet biogenesis. J Cell Biol 2020; 219:e201910177. [PMID: 32349126 PMCID: PMC7337503 DOI: 10.1083/jcb.201910177] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 02/26/2020] [Accepted: 04/03/2020] [Indexed: 02/03/2023] Open
Abstract
Lipid droplets (LDs) are fat storage organelles that originate from the endoplasmic reticulum (ER). Relatively little is known about how sites of LD formation are selected and which proteins/lipids are necessary for the process. Here, we show that LDs induced by the yeast triacylglycerol (TAG)-synthases Lro1 and Dga1 are formed at discrete ER subdomains defined by seipin (Fld1), and a regulator of diacylglycerol (DAG) production, Nem1. Fld1 and Nem1 colocalize to ER-LD contact sites. We find that Fld1 and Nem1 localize to ER subdomains independently of each other and of LDs, but both are required for the subdomains to recruit the TAG-synthases and additional LD biogenesis factors: Yft2, Pex30, Pet10, and Erg6. These subdomains become enriched in DAG. We conclude that Fld1 and Nem1 are both necessary to recruit proteins to ER subdomains where LD biogenesis occurs.
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Affiliation(s)
- Vineet Choudhary
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Ola El Atab
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Giulia Mizzon
- Electron Microscopy Core Facility, European Molecular Biology Laboratory, Heidelberg, Germany
| | - William A. Prinz
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - Roger Schneiter
- Department of Biology, University of Fribourg, Fribourg, Switzerland
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71
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Lundquist PK, Shivaiah KK, Espinoza-Corral R. Lipid droplets throughout the evolutionary tree. Prog Lipid Res 2020; 78:101029. [PMID: 32348789 DOI: 10.1016/j.plipres.2020.101029] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 04/11/2020] [Accepted: 04/18/2020] [Indexed: 12/11/2022]
Abstract
Intracellular lipid droplets are utilized for lipid storage and metabolism in organisms as evolutionarily diverse as animals, fungi, plants, bacteria, and archaea. These lipid droplets demonstrate great diversity in biological functions and protein and lipid compositions, yet fundamentally share common molecular and ultrastructural characteristics. Lipid droplet research has been largely fragmented across the diversity of lipid droplet classes and sub-classes. However, we suggest that there is great potential benefit to the lipid community in better integrating the lipid droplet research fields. To facilitate such integration, we survey the protein and lipid compositions, functional roles, and mechanisms of biogenesis across the breadth of lipid droplets studied throughout the natural world. We depict the big picture of lipid droplet biology, emphasizing shared characteristics and unique differences seen between different classes. In presenting the known diversity of lipid droplets side-by-side it becomes necessary to offer for the first time a consistent system of categorization and nomenclature. We propose a division into three primary classes that reflect their sub-cellular location: i) cytoplasmic lipid droplets (CYTO-LDs), that are present in the eukaryotic cytoplasm, ii) prokaryotic lipid droplets (PRO-LDs), that exist in the prokaryotic cytoplasm, and iii) plastid lipid droplets (PL-LDs), that are found in plant plastids, organelles of photosynthetic eukaryotes. Within each class there is a remarkable array of sub-classes displaying various sizes, shapes and compositions. A more integrated lipid droplet research field will provide opportunities to better build on discoveries and accelerate the pace of research in ways that have not been possible.
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Affiliation(s)
- Peter K Lundquist
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824, USA; Plant Resilience Institute, Michigan State University, East Lansing, MI, 48824, USA.
| | - Kiran-Kumar Shivaiah
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824, USA; Plant Resilience Institute, Michigan State University, East Lansing, MI, 48824, USA
| | - Roberto Espinoza-Corral
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824, USA; Plant Resilience Institute, Michigan State University, East Lansing, MI, 48824, USA
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72
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Dhiman R, Caesar S, Thiam AR, Schrul B. Mechanisms of protein targeting to lipid droplets: A unified cell biological and biophysical perspective. Semin Cell Dev Biol 2020; 108:4-13. [PMID: 32201131 DOI: 10.1016/j.semcdb.2020.03.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 02/23/2020] [Accepted: 03/13/2020] [Indexed: 12/22/2022]
Abstract
Lipid droplets (LDs), or oil bodies in plants, are specialized organelles that primarily serve as hubs of cellular metabolic energy storage and consumption. These ubiquitous cytoplasmic organelles are derived from the endoplasmic reticulum (ER) and consist of a hydrophobic neutral lipid core - mainly consisting of triglycerides and sterol esters - that is encircled by a phospholipid monolayer. The dynamic metabolic functions of the LDs are mainly executed and regulated by proteins on the monolayer surface. However, its unique architecture puts some structural constraints on the types of proteins that can associate with LDs. The lipid monolayer is decorated with either peripheral proteins or with integral membrane proteins that adopt a monotopic topology. Due to its oil-water interface, which is energetically costly, the LD surface happens to be favorable to the recruitment of many proteins involved in metabolic but also non-metabolic functions. We only started very recently to understand biophysical and biochemical principles controlling protein targeting to LDs. This review aims to summarize the most recent findings regarding this topic and proposes directions that will potentially lead to a better understanding of LD surface characteristics, as compared to bilayer membranes, and how that impacts protein-LD interactions.
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Affiliation(s)
- Ravi Dhiman
- Medical Biochemistry and Molecular Biology, Center for Molecular Signaling (PZMS), Faculty of Medicine, Saarland University, 66421 Homburg, Saar, Germany
| | - Stefanie Caesar
- Medical Biochemistry and Molecular Biology, Center for Molecular Signaling (PZMS), Faculty of Medicine, Saarland University, 66421 Homburg, Saar, Germany
| | - Abdou Rachid Thiam
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, F-75005 Paris, France.
| | - Bianca Schrul
- Medical Biochemistry and Molecular Biology, Center for Molecular Signaling (PZMS), Faculty of Medicine, Saarland University, 66421 Homburg, Saar, Germany.
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73
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Sosa Ponce ML, Moradi-Fard S, Zaremberg V, Cobb JA. SUNny Ways: The Role of the SUN-Domain Protein Mps3 Bridging Yeast Nuclear Organization and Lipid Homeostasis. Front Genet 2020; 11:136. [PMID: 32184804 PMCID: PMC7058695 DOI: 10.3389/fgene.2020.00136] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 02/04/2020] [Indexed: 12/14/2022] Open
Abstract
Mps3 is a SUN (Sad1-UNC-84) domain-containing protein that is located in the inner nuclear membrane (INM). Genetic screens with multiple Mps3 mutants have suggested that distinct regions of Mps3 function in relative isolation and underscore the broad involvement of Mps3 in multiple pathways including mitotic spindle formation, telomere maintenance, and lipid metabolism. These pathways have largely been characterized in isolation, without a holistic consideration for how key regulatory events within one pathway might impinge on other aspects of biology at the nuclear membrane. Mps3 is uniquely positioned to function in these multiple pathways as its N- terminus is in the nucleoplasm, where it is important for telomere anchoring at the nuclear periphery, and its C-terminus is in the lumen, where it has links with lipid metabolic processes. Emerging work suggests that the role of Mps3 in nuclear organization and lipid homeostasis are not independent, but more connected. For example, a failure in regulating Mps3 levels through the cell cycle leads to nuclear morphological abnormalities and loss of viability, suggesting a link between the N-terminal domain of Mps3 and nuclear envelope homeostasis. We will highlight work suggesting that Mps3 is pivotal factor in communicating events between the nucleus and the lipid bilayer.
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Affiliation(s)
- Maria Laura Sosa Ponce
- Departments of Biochemistry & Molecular Biology and Oncology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine, Calgary, AB, Canada.,Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Sarah Moradi-Fard
- Departments of Biochemistry & Molecular Biology and Oncology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine, Calgary, AB, Canada
| | - Vanina Zaremberg
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Jennifer A Cobb
- Departments of Biochemistry & Molecular Biology and Oncology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine, Calgary, AB, Canada
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74
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Renne MF, Klug YA, Carvalho P. Lipid droplet biogenesis: A mystery "unmixing"? Semin Cell Dev Biol 2020; 108:14-23. [PMID: 32192830 DOI: 10.1016/j.semcdb.2020.03.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 03/06/2020] [Accepted: 03/07/2020] [Indexed: 12/19/2022]
Abstract
Lipid droplets (LDs) are versatile organelles with central roles in lipid and energy metabolism in all eukaryotes. They primarily buffer excess fatty acids by storing them as neutral lipids, mainly triglycerides and steryl esters. The neutral lipids form a core, surrounded by a unique phospholipid monolayer coated with a defined set of proteins. Thus, the architecture of LDs sets them apart from all other membrane-bound organelles. The origin of LDs remained controversial for a long time. However, it has become clear that their biogenesis occurs at the endoplasmic reticulum (ER) and is a lipid driven process. LD formation is intiatied by the demixing of neutral lipids from membrane phospholipids, leading to the formation of a neutral lipid "lens" like structure between the leaflets of the ER bilayer. As this lens grows, it buds out of the membrane towards the cytosol to give rise to a LD. Recent biophysical and cell biological experiments indicate that LD biogenesis occurs at specific ER domains. These domains are enriched in various proteins required for normal LD formation and possibly have a lipid composition distinct from the remaining ER membrane. Here, we describe the prevailing model for LD formation and discuss recent insights on how proteins organize ER domains involved in LD biogenesis.
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Affiliation(s)
- Mike F Renne
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK.
| | - Yoel A Klug
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK.
| | - Pedro Carvalho
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK.
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75
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Affiliation(s)
- Maria Bohnert
- Institute of Cell Dynamics and Imaging, University of Münster
- Cells-in-Motion Cluster of Excellence (EXC 1003—CiM), University of Münster
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76
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Ischebeck T, Krawczyk HE, Mullen RT, Dyer JM, Chapman KD. Lipid droplets in plants and algae: Distribution, formation, turnover and function. Semin Cell Dev Biol 2020; 108:82-93. [PMID: 32147380 DOI: 10.1016/j.semcdb.2020.02.014] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 01/28/2020] [Accepted: 02/29/2020] [Indexed: 01/02/2023]
Abstract
Plant oils represent an energy-rich and carbon-dense group of hydrophobic compounds. These oils are not only of economic interest, but also play important, fundamental roles in plant and algal growth and development. The subcellular storage compartments of plant lipids, referred to as lipid droplets (LDs), have long been considered relatively inert oil vessels. However, research in the last decade has revealed that LDs play far more dynamic roles in plant biology than previously appreciated, including transient neutral lipid storage, membrane remodeling, lipid signaling, and stress responses. Here we discuss recent developments in the understanding of LD formation, turnover and function in land plants and algae.
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Affiliation(s)
- Till Ischebeck
- University of Göttingen, Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, 37077, Göttingen, Germany.
| | - Hannah E Krawczyk
- University of Göttingen, Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, 37077, Göttingen, Germany
| | - Robert T Mullen
- University of Guelph, Department of Molecular Cell Biology, Guelph, Ontario, N1G 2W1, Canada
| | - John M Dyer
- United States Department of Agriculture, Agriculture Research Service, US Arid-Land Agricultural Research Center, Maricopa, AZ, 85138, USA
| | - Kent D Chapman
- University of North Texas, BioDiscovery Institute, Department of Biological Sciences, Denton, TX, 76203, USA
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77
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Leyland B, Boussiba S, Khozin-Goldberg I. A Review of Diatom Lipid Droplets. BIOLOGY 2020; 9:biology9020038. [PMID: 32098118 PMCID: PMC7168155 DOI: 10.3390/biology9020038] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 02/12/2020] [Accepted: 02/14/2020] [Indexed: 12/20/2022]
Abstract
The dynamic nutrient availability and photon flux density of diatom habitats necessitate buffering capabilities in order to maintain metabolic homeostasis. This is accomplished by the biosynthesis and turnover of storage lipids, which are sequestered in lipid droplets (LDs). LDs are an organelle conserved among eukaryotes, composed of a neutral lipid core surrounded by a polar lipid monolayer. LDs shield the intracellular environment from the accumulation of hydrophobic compounds and function as a carbon and electron sink. These functions are implemented by interconnections with other intracellular systems, including photosynthesis and autophagy. Since diatom lipid production may be a promising objective for biotechnological exploitation, a deeper understanding of LDs may offer targets for metabolic engineering. In this review, we provide an overview of diatom LD biology and biotechnological potential.
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78
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Tashiro S, Kakimoto Y, Shinmyo M, Fujimoto S, Tamura Y. Improved Split-GFP Systems for Visualizing Organelle Contact Sites in Yeast and Human Cells. Front Cell Dev Biol 2020. [PMID: 33330450 DOI: 10.3389/fcell.2020.571388.ecollection2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/24/2023] Open
Abstract
Inter-organelle contact sites have attracted a lot of attention as functionally specialized regions that mediate the exchange of metabolites, including lipids and ions, between distinct organelles. However, studies on inter-organelle contact sites are at an early stage and it remains enigmatic what directly mediates the organelle-organelle interactions and how the number and degree of the contacts are regulated. As a first step to answer these questions, we previously developed split-GFP probes that could visualize and quantify multiple inter-organelle contact sites in the yeast and human cultured cells. However, the split-GFP probes possessed a disadvantage of inducing artificial connections between two different organelle membranes, especially when overexpressed. In the present study, we developed a way to express the split-GFP probes whose expressions remained at low levels, with minimal variations between different yeast cells. Besides, we constructed a HeLa cell line in which the expression of the split-GFP probes could be induced by the addition of doxycycline to minimize the artificial effects. The improved split-GFP systems may be faithful tools to quantify organelle contact sites and screen new factors involved in organelle-organelle tethering in yeast and mammalian cells.
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Affiliation(s)
- Shinya Tashiro
- Faculty of Science, Yamagata University, Yamagata, Japan
| | - Yuriko Kakimoto
- Department of Biochemistry and Molecular Biology, Graduate School of Medical Science, Yamagata University, Yamagata, Japan
| | | | | | - Yasushi Tamura
- Faculty of Science, Yamagata University, Yamagata, Japan
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79
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Henne M, Goodman JM, Hariri H. Spatial compartmentalization of lipid droplet biogenesis. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158499. [PMID: 31352131 PMCID: PMC7050823 DOI: 10.1016/j.bbalip.2019.07.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 07/08/2019] [Accepted: 07/09/2019] [Indexed: 12/18/2022]
Abstract
Lipid droplets (LDs) are ubiquitous organelles that store metabolic energy in the form of neutral lipids (typically triacylglycerols and steryl esters). Beyond being inert energy storage compartments, LDs are dynamic organelles that participate in numerous essential metabolic functions. Cells generate LDs de novo from distinct sub-regions at the endoplasmic reticulum (ER), but what determines sites of LD formation remains a key unanswered question. Here, we review the factors that determine LD formation at the ER, and discuss how they work together to spatially and temporally coordinate LD biogenesis. These factors include lipid synthesis enzymes, assembly proteins, and membrane structural requirements. LDs also make contact with other organelles, and these inter-organelle contacts contribute to defining sites of LD production. Finally, we highlight emerging non-canonical roles for LDs in maintaining cellular homeostasis during stress.
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Affiliation(s)
- Mike Henne
- Department of Cell Biology and Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Joel M Goodman
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Hanaa Hariri
- Department of Cell Biology and Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, United States of America.
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80
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Chung J, Wu X, Lambert TJ, Lai ZW, Walther TC, Farese RV. LDAF1 and Seipin Form a Lipid Droplet Assembly Complex. Dev Cell 2019; 51:551-563.e7. [PMID: 31708432 PMCID: PMC7235935 DOI: 10.1016/j.devcel.2019.10.006] [Citation(s) in RCA: 122] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 08/12/2019] [Accepted: 10/08/2019] [Indexed: 10/25/2022]
Abstract
Lipid droplets (LDs) originate from the endoplasmic reticulum (ER) to store triacylglycerol (TG) and cholesterol esters. The ER protein seipin was shown to localize to ER-LD contacts soon after LDs form, but what determines the sites of initial LD biogenesis in the ER is unknown. Here, we identify TMEM159, now re-named lipid droplet assembly factor 1 (LDAF1), as an interaction partner of seipin. Together, LDAF1 and seipin form an ∼600 kDa oligomeric complex that copurifies with TG. LDs form at LDAF1-seipin complexes, and re-localization of LDAF1 to the plasma membrane co-recruits seipin and redirects LD formation to these sites. Once LDs form, LDAF1 dissociates from seipin and moves to the LD surface. In the absence of LDAF1, LDs form only at significantly higher cellular TG concentrations. Our data suggest that the LDAF1-seipin complex is the core protein machinery that facilitates LD biogenesis and determines the sites of their formation in the ER.
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Affiliation(s)
- Jeeyun Chung
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Xudong Wu
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Talley J Lambert
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Zon Weng Lai
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Harvard Chan Advanced Multi-omics Platform, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Tobias C Walther
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Harvard Chan Advanced Multi-omics Platform, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02124, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA.
| | - Robert V Farese
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02124, USA.
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81
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Hugenroth M, Bohnert M. Come a little bit closer! Lipid droplet-ER contact sites are getting crowded. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1867:118603. [PMID: 31733263 DOI: 10.1016/j.bbamcr.2019.118603] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 10/26/2019] [Accepted: 10/29/2019] [Indexed: 12/12/2022]
Abstract
Not so long ago, contact sites between the endoplasmic reticulum (ER) and lipid droplets (LDs) were largely unexplored on a molecular level. In recent years however, numerous proteins have been identified that are enriched or exclusively located at the interfaces between LDs and the ER. These comprise members of protein classes typically found in diverse types of contacts, such as organelle tethers and lipid transfer proteins, but also proteins that have no similarities to known contact site machineries. This structurally heterogeneous group of contact site residents might be required to fulfill unique aspects of LD-ER contact biology, such as de novo LD biogenesis, and maintenance of lipidic connections between LDs and ER. Here, we summarize the current knowledge on the molecular components of this special organelle contact site, and discuss their features and functions.
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Affiliation(s)
- Marie Hugenroth
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Str. 56, 48149 Münster, Germany; Cells-in-Motion Cluster of Excellence (EXC 1003 - CiM), University of Münster, Germany
| | - Maria Bohnert
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Str. 56, 48149 Münster, Germany; Cells-in-Motion Cluster of Excellence (EXC 1003 - CiM), University of Münster, Germany.
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82
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Tan Y, Jin Y, Wang Q, Huang J, Wu X, Ren Z. Perilipin 5 Protects against Cellular Oxidative Stress by Enhancing Mitochondrial Function in HepG2 Cells. Cells 2019; 8:cells8101241. [PMID: 31614673 PMCID: PMC6830103 DOI: 10.3390/cells8101241] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 09/29/2019] [Accepted: 10/08/2019] [Indexed: 12/20/2022] Open
Abstract
: Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver diseases worldwide. Reactive oxygen species (ROS), as potent oxidants in cells, have been shown to promote the development of NAFLD. Previous studies reported that for ROS-induced cellular oxidative stress, promoting lipid droplet (LD) accumulation is associated with the cellular antioxidation process. However, the regulatory role of LDs in relieving cellular oxidative stress is poorly understood. Here, we showed that Perilipin 5 (PLIN5), a key LD protein related to mitochondria-LD contact, reduced ROS levels and improved mitochondrial function in HepG2 cells. Both mRNA and protein levels of PLIN5 were significantly increased in cells with hydrogen peroxide or lipopolysaccharide (LPS) treatment (p < 0.05). Additionally, the overexpression of PLIN5 promoted LD formation and mitochondria-LD contact, reduced cellular ROS levels and up-regulated mitochondrial function-related genes such as COX and CS. Knockdown PLIN5, meanwhile, showed opposite effects. Furthermore, we identified that cellular oxidative stress up-regulated PLIN5 expression via the JNK-p38-ATF pathway. This study shows that the up-regulation of PLIN5 is a kind of survival strategy for cells in response to stress. PLIN5 can be a potential therapeutic target in NAFLD.
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Affiliation(s)
- Yanjie Tan
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of the Ministry of Education, College of Animal Science, Huazhong Agricultural University, Wuhan 430070, Hubei, China.
| | - Yi Jin
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of the Ministry of Education, College of Animal Science, Huazhong Agricultural University, Wuhan 430070, Hubei, China.
| | - Qian Wang
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of the Ministry of Education, College of Animal Science, Huazhong Agricultural University, Wuhan 430070, Hubei, China.
| | - Jin Huang
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of the Ministry of Education, College of Animal Science, Huazhong Agricultural University, Wuhan 430070, Hubei, China.
| | - Xiang Wu
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of the Ministry of Education, College of Animal Science, Huazhong Agricultural University, Wuhan 430070, Hubei, China.
| | - Zhuqing Ren
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of the Ministry of Education, College of Animal Science, Huazhong Agricultural University, Wuhan 430070, Hubei, China.
- The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan 430070, Hubei, China.
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83
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Su WC, Lin YH, Pagac M, Wang CW. Seipin negatively regulates sphingolipid production at the ER-LD contact site. J Cell Biol 2019; 218:3663-3680. [PMID: 31594806 PMCID: PMC6829658 DOI: 10.1083/jcb.201902072] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 06/23/2019] [Accepted: 08/08/2019] [Indexed: 01/06/2023] Open
Abstract
Su et al. show that seipin negatively regulates the production of sphingoid intermediates by binding the enzymes serine palmitoyltransferase and fatty acid elongase at discrete regions of the ER in close vicinity to lipid droplets, thereby mediating the synthesis of two major building blocks for sphingolipids. Seipin is known for its critical role in controlling lipid droplet (LD) assembly at the LD-forming subdomain of the endoplasmic reticulum (ER). Here, we identified a new function of seipin as a negative regulator for sphingolipid production. We show that yeast cells lacking seipin displayed altered sensitivity to sphingolipid inhibitors, accumulated sphingoid precursors and intermediates, and increased serine palmitoyltransferase (SPT) and fatty acid (FA) elongase activities. Seipin associated with SPT and FA elongase, and the interaction was reduced by inhibitors for sphingolipid synthesis in a concentration-dependent manner. We further show that the interactions of seipin with SPT and FA elongase occurred at ER–LD contacts and were likely regulated differentially. Further evidence indicated that LD biogenesis was intact when SPT activity was blocked, whereas excess sphingoid intermediates may affect LD morphology. Expression of human seipin rescued the altered sphingolipids in yeast seipin mutants, suggesting that the negative regulation of sphingolipid synthesis by seipin is likely an evolutionarily conserved process.
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Affiliation(s)
- Wei-Cheng Su
- Institute of Plant and Microbial Biology, Academia Sinica, Nangang, Taipei, Taiwan
| | - Yi-Hsiu Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Nangang, Taipei, Taiwan
| | - Martin Pagac
- Institute of Plant and Microbial Biology, Academia Sinica, Nangang, Taipei, Taiwan
| | - Chao-Wen Wang
- Institute of Plant and Microbial Biology, Academia Sinica, Nangang, Taipei, Taiwan
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84
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Xu Y, Mak HY, Lukmantara I, Li YE, Hoehn KL, Huang X, Du X, Yang H. CDP-DAG synthase 1 and 2 regulate lipid droplet growth through distinct mechanisms. J Biol Chem 2019; 294:16740-16755. [PMID: 31548309 DOI: 10.1074/jbc.ra119.009992] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 08/17/2019] [Indexed: 12/25/2022] Open
Abstract
Lipid droplets (LDs) are evolutionarily conserved organelles that play critical roles in mammalian lipid storage and metabolism. However, the molecular mechanisms governing the biogenesis and growth of LDs remain poorly understood. Phosphatidic acid (PA) is a precursor of phospholipids and triacylglycerols and substrate of CDP-diacylglycerol (CDP-DAG) synthase 1 (CDS1) and CDS2, which catalyze the formation of CDP-DAG. Here, using siRNA-based gene knockdowns and CRISPR/Cas9-mediated gene knockouts, along with immunological, molecular, and fluorescence microscopy approaches, we examined the role of CDS1 and CDS2 in LD biogenesis and growth. Knockdown of either CDS1 or CDS2 expression resulted in the formation of giant or supersized LDs in cultured mammalian cells. Interestingly, down-regulation of cell death-inducing DFF45-like effector C (CIDEC), encoding a prominent regulator of LD growth in adipocytes, restored LD size in CDS1- but not in CDS2-deficient cells. On the other hand, reducing expression of two enzymes responsible for triacylglycerol synthesis, diacylglycerol O-acyltransferase 2 (DGAT2) and glycerol-3-phosphate acyltransferase 4 (GPAT4), rescued the LD phenotype in CDS2-deficient, but not CDS1-deficient, cells. Moreover, CDS2 deficiency, but not CDS1 deficiency, promoted the LD association of DGAT2 and GPAT4 and impaired initial LD maturation. Finally, although both CDS1 and CDS2 appeared to regulate PA levels on the LD surface, CDS2 had a stronger effect. We conclude that CDS1 and CDS2 regulate LD dynamics through distinct mechanisms.
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Affiliation(s)
- Yanqing Xu
- School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Hoi Yin Mak
- School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Ivan Lukmantara
- School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Yang E Li
- School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Kyle L Hoehn
- School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Xun Huang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100049, China
| | - Ximing Du
- School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Hongyuan Yang
- School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney, New South Wales 2052, Australia
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85
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Barbosa AD, Lim K, Mari M, Edgar JR, Gal L, Sterk P, Jenkins BJ, Koulman A, Savage DB, Schuldiner M, Reggiori F, Wigge PA, Siniossoglou S. Compartmentalized Synthesis of Triacylglycerol at the Inner Nuclear Membrane Regulates Nuclear Organization. Dev Cell 2019; 50:755-766.e6. [PMID: 31422915 PMCID: PMC6859503 DOI: 10.1016/j.devcel.2019.07.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 04/22/2019] [Accepted: 07/03/2019] [Indexed: 01/08/2023]
Abstract
Cells dynamically adjust organelle organization in response to growth and environmental cues. This requires regulation of synthesis of phospholipids, the building blocks of organelle membranes, or remodeling of their fatty-acyl (FA) composition. FAs are also the main components of triacyglycerols (TGs), which enable energy storage in lipid droplets. How cells coordinate FA metabolism with organelle biogenesis during cell growth remains unclear. Here, we show that Lro1, an acyltransferase that generates TGs from phospholipid-derived FAs in yeast, relocates from the endoplasmic reticulum to a subdomain of the inner nuclear membrane. Lro1 nuclear targeting is regulated by cell cycle and nutrient starvation signals and is inhibited when the nucleus expands. Lro1 is active at this nuclear subdomain, and its compartmentalization is critical for nuclear integrity. These data suggest that Lro1 nuclear targeting provides a site of TG synthesis, which is coupled with nuclear membrane remodeling. Nutrients regulate the phospholipid:diacylglycerol acyltransferase Lro1 Lro1 targets the INM subdomain bordering the nucleolus Lro1 is active at the INM and can sustain cell survival during starvation Compartmentalized synthesis of nuclear TG is important for nuclear envelope integrity
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Affiliation(s)
- Antonio D Barbosa
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Koini Lim
- Metabolic Research Laboratories, Wellcome Trust-Medical Research, Council Institute of Metabolic Science, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Muriel Mari
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, 9713AV Groningen, Netherlands
| | - James R Edgar
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Lihi Gal
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Peter Sterk
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Benjamin J Jenkins
- NIHR BRC Core Metabolomics and Lipidomics Laboratory and University of Cambridge Metabolic Research Laboratories, Wellcome Trust-Medical Research Council Institute of Metabolic Science, Cambridge CB2 0QQ, UK
| | - Albert Koulman
- NIHR BRC Core Metabolomics and Lipidomics Laboratory and University of Cambridge Metabolic Research Laboratories, Wellcome Trust-Medical Research Council Institute of Metabolic Science, Cambridge CB2 0QQ, UK
| | - David B Savage
- Metabolic Research Laboratories, Wellcome Trust-Medical Research, Council Institute of Metabolic Science, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Fulvio Reggiori
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, 9713AV Groningen, Netherlands
| | - Philip A Wigge
- Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, UK
| | - Symeon Siniossoglou
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK.
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86
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The biogenesis of lipid droplets: Lipids take center stage. Prog Lipid Res 2019; 75:100989. [PMID: 31351098 DOI: 10.1016/j.plipres.2019.100989] [Citation(s) in RCA: 95] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 05/21/2019] [Accepted: 06/27/2019] [Indexed: 11/20/2022]
Abstract
Lipid droplets (LDs) are multi-functional cellular organelles that store energy, and regulate many aspects of cell physiology. However, our understanding of the biogenesis of LDs remains very limited. Originating from the endoplasmic reticulum (ER), LDs are highly unique organelles in that each LD is bounded by a monolayer of amphipathic lipids. Recent progress has unveiled critical roles of non-bilayer lipids in LD formation. For instance, non-bilayer lipids such as lysophospholipids, diacylglycerol and phosphatidic acid (PA) can impact the curvature, surface and line tension of the ER, thereby impacting LD biogenesis. Two well-known regulators of LD formation, FIT2/FITM2 and seipin, have both been implicated in controlling the metabolism and/or distribution of non-bilayer lipids. We summarize and integrate these recent advances and propose that non-bilayer lipids may play a critical role in each step of LD biogenesis.
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87
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Mechanisms of lipid droplet biogenesis. Biochem J 2019; 476:1929-1942. [DOI: 10.1042/bcj20180021] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 06/11/2019] [Accepted: 06/13/2019] [Indexed: 12/28/2022]
Abstract
Abstract
Lipid droplets (LDs) are organelles that compartmentalize nonbilayer-forming lipids in the aqueous cytoplasm of cells. They are ubiquitous in most organisms, including in animals, protists, plants and microorganisms. In eukaryotes, LDs are believed to be derived by a budding and scission process from the surface of the endoplasmic reticulum, and this occurs concomitantly with the accumulation of neutral lipids, most often triacylglycerols and steryl esters. Overall, the mechanisms underlying LD biogenesis are difficult to generalize, in part because of the involvement of different sets of both evolutionarily conserved and organism-specific LD-packaging proteins. Here, we briefly compare and contrast these proteins and the allied processes responsible for LD biogenesis in cells of animals, yeasts and plants.
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88
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Cao Z, Hao Y, Fung CW, Lee YY, Wang P, Li X, Xie K, Lam WJ, Qiu Y, Tang BZ, Shui G, Liu P, Qu J, Kang BH, Mak HY. Dietary fatty acids promote lipid droplet diversity through seipin enrichment in an ER subdomain. Nat Commun 2019; 10:2902. [PMID: 31263173 PMCID: PMC6602954 DOI: 10.1038/s41467-019-10835-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 06/03/2019] [Indexed: 02/06/2023] Open
Abstract
Exogenous metabolites from microbial and dietary origins have profound effects on host metabolism. Here, we report that a sub-population of lipid droplets (LDs), which are conserved organelles for fat storage, is defined by metabolite-modulated targeting of the C. elegans seipin ortholog, SEIP-1. Loss of SEIP-1 function reduces the size of a subset of LDs while over-expression of SEIP-1 has the opposite effect. Ultrastructural analysis reveals SEIP-1 enrichment in an endoplasmic reticulum (ER) subdomain, which co-purifies with LDs. Analyses of C. elegans and bacterial genetic mutants indicate a requirement of polyunsaturated fatty acids (PUFAs) and microbial cyclopropane fatty acids (CFAs) for SEIP-1 enrichment, as confirmed by dietary supplementation experiments. In mammalian cells, heterologously expressed SEIP-1 engages nascent lipid droplets and promotes their subsequent expansion in a conserved manner. Our results suggest that microbial and polyunsaturated fatty acids serve unexpected roles in regulating cellular fat storage by promoting LD diversity. Lipid droplets (LDs) are fat storage organelles that are initiated and expanded by seipins at ER contact sites. Here the authors show that the C. elegans seipin ortholog SEIP-1 is recruited to these sites by certain dietary fatty acids to support the expansion of a subset of LDs.
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Affiliation(s)
- Zhe Cao
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Yan Hao
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Chun Wing Fung
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Yiu Yiu Lee
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Pengfei Wang
- School of Life Science, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Xuesong Li
- Biophotonics Research Laboratory, Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Kang Xie
- Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Wen Jiun Lam
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Yifei Qiu
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Ben Zhong Tang
- Department of Chemistry, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Guanghou Shui
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Pingsheng Liu
- Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Jianan Qu
- Biophotonics Research Laboratory, Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Byung-Ho Kang
- School of Life Science, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Ho Yi Mak
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China.
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89
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Salo VT, Li S, Vihinen H, Hölttä-Vuori M, Szkalisity A, Horvath P, Belevich I, Peränen J, Thiele C, Somerharju P, Zhao H, Santinho A, Thiam AR, Jokitalo E, Ikonen E. Seipin Facilitates Triglyceride Flow to Lipid Droplet and Counteracts Droplet Ripening via Endoplasmic Reticulum Contact. Dev Cell 2019; 50:478-493.e9. [PMID: 31178403 DOI: 10.1016/j.devcel.2019.05.016] [Citation(s) in RCA: 128] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 02/27/2019] [Accepted: 05/03/2019] [Indexed: 01/02/2023]
Abstract
Seipin is an oligomeric integral endoplasmic reticulum (ER) protein involved in lipid droplet (LD) biogenesis. To study the role of seipin in LD formation, we relocalized it to the nuclear envelope and found that LDs formed at these new seipin-defined sites. The sites were characterized by uniform seipin-mediated ER-LD necks. At low seipin content, LDs only grew at seipin sites, and tiny, growth-incompetent LDs appeared in a Rab18-dependent manner. When seipin was removed from ER-LD contacts within 1 h, no lipid metabolic defects were observed, but LDs became heterogeneous in size. Studies in seipin-ablated cells and model membranes revealed that this heterogeneity arises via a biophysical ripening process, with triglycerides partitioning from smaller to larger LDs through droplet-bilayer contacts. These results suggest that seipin supports the formation of structurally uniform ER-LD contacts and facilitates the delivery of triglycerides from ER to LDs. This counteracts ripening-induced shrinkage of small LDs.
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Affiliation(s)
- Veijo T Salo
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland; Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Shiqian Li
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland; Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Helena Vihinen
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Maarit Hölttä-Vuori
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland; Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | | | | | - Ilya Belevich
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Johan Peränen
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland; Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | | | - Pentti Somerharju
- Department of Biochemistry, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Hongxia Zhao
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Alexandre Santinho
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Universite de Paris, Paris, France
| | - Abdou Rachid Thiam
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Universite de Paris, Paris, France.
| | - Eija Jokitalo
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
| | - Elina Ikonen
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland; Minerva Foundation Institute for Medical Research, Helsinki, Finland.
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90
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Joshi AS, Cohen S. Lipid Droplet and Peroxisome Biogenesis: Do They Go Hand-in-Hand? Front Cell Dev Biol 2019; 7:92. [PMID: 31214588 PMCID: PMC6554619 DOI: 10.3389/fcell.2019.00092] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 05/14/2019] [Indexed: 01/19/2023] Open
Abstract
All eukaryotic cells contain membrane bound structures called organelles. Each organelle has specific composition and function. Some of the organelles are generated de novo in a cell. The endoplasmic reticulum (ER) is a major contributor of proteins and membranes for most of the organelles. In this mini review, we discuss de novo biogenesis of two such organelles, peroxisomes and lipid droplets (LDs), that are formed in the ER membrane. LDs and peroxisomes are highly conserved ubiquitously present membrane-bound organelles. Both these organelles play vital roles in lipid metabolism and human health. Here, we discuss the current understanding of de novo biogenesis of LDs and peroxisomes, recent advances on how biogenesis of both the organelles might be linked, physical interaction between LDs and peroxisomes and other organelles, and their physiological importance.
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Affiliation(s)
- Amit S. Joshi
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Sarah Cohen
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
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91
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Chorlay A, Monticelli L, Veríssimo Ferreira J, Ben M'barek K, Ajjaji D, Wang S, Johnson E, Beck R, Omrane M, Beller M, Carvalho P, Rachid Thiam A. Membrane Asymmetry Imposes Directionality on Lipid Droplet Emergence from the ER. Dev Cell 2019; 50:25-42.e7. [PMID: 31155466 DOI: 10.1016/j.devcel.2019.05.003] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 01/11/2019] [Accepted: 05/02/2019] [Indexed: 01/18/2023]
Abstract
During energy bursts, neutral lipids fabricated within the ER bilayer demix to form lipid droplets (LDs). LDs bud off mainly in the cytosol where they regulate metabolism and multiple biological processes. They indeed become accessible to most enzymes and can interact with other organelles. How such directional emergence is achieved remains elusive. Here, we found that this directionality is controlled by an asymmetry in monolayer surface coverage. Model LDs emerge on the membrane leaflet of higher coverage, which is improved by the insertion of proteins and phospholipids. In cells, continuous LD emergence on the cytosol would require a constant refill of phospholipids to the ER cytosolic leaflet. Consistent with this model, cells deficient in phospholipids present an increased number of LDs exposed to the ER lumen and compensate by remodeling ER shape. Our results reveal an active cooperation between phospholipids and proteins to extract LDs from ER.
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Affiliation(s)
- Aymeric Chorlay
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRSSorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France
| | - Luca Monticelli
- Laboratory of Molecular Microbiology and Structural Biochemistry, UMR5086 CNRS and University of Lyon, Lyon 69367, France
| | | | - Kalthoum Ben M'barek
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRSSorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France
| | - Dalila Ajjaji
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRSSorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France
| | - Sihui Wang
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Errin Johnson
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Rainer Beck
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - Mohyeddine Omrane
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRSSorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France
| | - Mathias Beller
- Institute for Mathematical Modeling of Biological Systems, Systems Biology of Lipid Metabolism, Heinrich Heine University, Düsseldorf, Germany
| | - Pedro Carvalho
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Abdou Rachid Thiam
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRSSorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France.
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92
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Li Q, Li Y, Zhang Z, Kang H, Zhang L, Zhang Y, Zhou L. SEIPIN overexpression in the liver may alleviate hepatic steatosis by influencing the intracellular calcium level. Mol Cell Endocrinol 2019; 488:70-78. [PMID: 30871963 DOI: 10.1016/j.mce.2019.03.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 03/06/2019] [Accepted: 03/08/2019] [Indexed: 12/13/2022]
Abstract
SEIPIN deficiency leads to a severe lipodystrophic phenotype with loss of fat tissue. Interestingly, SEIPIN knockout in non-adipocytes is reported to promote intracellular triacylglycerol (TG) accumulation. However, the underlying mechanisms remain unclear at present. Here, we have shown that SEIPIN knockdown and overexpression exert opposite effects on hepatic lipometabolism. Our experimental data suggest that depletion of SEIPIN induces an increase in intracellular TG via activation of ER stress while its overexpression triggers a decrease in the intracellular TG content via increasing PGC-1α, which drives increased mitochondrial activity. Adeno-associated virus-mediated SEIPIN overexpression alleviated high fat diet-induced hepatosteatosis in mice. The collective results indicate that the effects of SEIPIN on TG and PGC-1α are dependent on calcium concentrations, signifying regulatory activity on hepatic lipometabolism through alterations in the intracellular calcium level, and support the potential utility of modulating intracellular SEIPIN and calcium levels as novel therapeutic strategies for fatty liver.
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Affiliation(s)
- Qiang Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Animal Science and Technology, Guangxi University, PR China; Department of Life Science, Bengbu Medical College, PR China
| | - Yixing Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Animal Science and Technology, Guangxi University, PR China
| | - Zhiwang Zhang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Animal Science and Technology, Guangxi University, PR China
| | - Huifang Kang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Animal Science and Technology, Guangxi University, PR China
| | - Lifang Zhang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Animal Science and Technology, Guangxi University, PR China
| | - Yuxiang Zhang
- The Institute for Diabetes, Obesity and Metabolism, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Lei Zhou
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Animal Science and Technology, Guangxi University, PR China.
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93
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Jackson CL. Lipid droplet biogenesis. Curr Opin Cell Biol 2019; 59:88-96. [PMID: 31075519 DOI: 10.1016/j.ceb.2019.03.018] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 03/24/2019] [Accepted: 03/29/2019] [Indexed: 11/18/2022]
Abstract
Lipid droplets (LDs) store neutral lipids in their core as an energy source when nutrients are scarce. The center of an LD is hydrophobic, and hence it is surrounded by a phospholipid monolayer, unlike other organelles that have an aqueous interior and are bounded by a phospholipid bilayer. LDs arise from the ER, where neutral lipid synthesis enzymes are localized. A combination of biophysical analysis and modeling, in vitro reconstitution and cell biological analyses has provided a great deal of information over the past few years on the process of LD biogenesis from the ER. In addition to lipid composition, four protein families (seipin proteins, perilipins, FIT proteins and ER shaping proteins) are crucial for LD biogenesis. Recent studies have shown that LDs preferentially arise, along with peroxisomes, at special ER sites marked by the reticulon-like Pex30/MCTP2 protein. New functions for perilipins and FIT family proteins have been uncovered, and the cryo-electron microscopy structure of seipin coupled with high resolution imaging in cells has provided a more comprehensive picture of its function in LD biogenesis. Seipin, along with other proteins such as Rab18 and its effector NRZ, have been shown to carry out their functions at least in part through regulation of ER-LD contact sites, whose establishment and maintenance have emerged as an essential component of LD biogenesis and maturation.
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Affiliation(s)
- Catherine L Jackson
- Institut Jacques Monod, UMR7592 CNRS Université Paris-Diderot, Sorbonne Paris Cité, Paris, France.
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94
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Nettebrock NT, Bohnert M. Born this way - Biogenesis of lipid droplets from specialized ER subdomains. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1865:158448. [PMID: 31028912 DOI: 10.1016/j.bbalip.2019.04.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 12/20/2018] [Accepted: 01/06/2019] [Indexed: 01/21/2023]
Abstract
Both the endoplasmic reticulum (ER) and lipid droplets (LDs) are key players in lipid handling. In addition to this functional connection, the two organelles are also tightly linked due to the fact that the ER is the birthplace of LDs. LDs have an atypical architecture, consisting of a neutral lipid core that is covered by a phospholipid monolayer. LD biogenesis starts with neutral lipid synthesis in the ER membrane and formation of small neutral lipid lenses between its leaflets, followed by budding of mature LDs toward the cytosol. Several ER proteins have been identified that are required for efficient LD formation, among them seipin, Pex30, and FIT2. Recent evidence indicates that these LD biogenesis factors might cooperate with specific lipids, thus generating ER subdomains optimized for LD assembly. Intriguingly, LD biogenesis reacts dynamically to nutrient stress, resulting in a spatial reorganization of LD formation in the ER.
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Affiliation(s)
- Niclas T Nettebrock
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Str. 56, 48149 Münster, Germany; Cells-in-Motion Cluster of Excellence (EXC 1003 - CiM), University of Münster, Germany
| | - Maria Bohnert
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Str. 56, 48149 Münster, Germany; Cells-in-Motion Cluster of Excellence (EXC 1003 - CiM), University of Münster, Germany.
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95
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Rockenfeller P, Gourlay CW. Lipotoxicty in yeast: a focus on plasma membrane signalling and membrane contact sites. FEMS Yeast Res 2019; 18:4953420. [PMID: 29718175 PMCID: PMC5905628 DOI: 10.1093/femsyr/foy034] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 03/23/2018] [Indexed: 12/23/2022] Open
Abstract
Lipotoxicity is a pathophysiological process triggered by lipid overload. In metazoans, lipotoxicity is characterised by the ectopic deposition of lipids on organs other than adipose tissue. This leads to organ dysfunction, cell death, and is intimately linked to lipid-associated diseases such as cardiac dysfunction, atherosclerosis, stroke, hepatosteatosis, cancer and the metabolic syndrome. The molecules involved in eliciting lipotoxicity include FAs and their acyl-CoA derivatives, triacylglycerol (TG), diacylglycerol (DG), ceramides, acyl-carnitines and phospholipids. However, the cellular transport of toxic lipids through membrane contact sites (MCS) and vesicular mechanisms as well as lipid metabolism that progress lipotoxicity to the onset of disease are not entirely understood. Yeast has proven a useful model organism to study the molecular mechanisms of lipotoxicity. Recently, the Rim101 pathway, which senses alkaline pH and the lipid status at the plasmamembrane, has been connected to lipotoxicity. In this review article, we summarise recent research advances on the Rim101 pathway and MCS in the context of lipotoxicity in yeast and present a perspective for future research directions.
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Affiliation(s)
- Patrick Rockenfeller
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury, CT2 7NJ Kent, UK.,Institute of Molecular Biosciences, NAWI Graz, University of Graz, Humboldtstr. 50, 8010 Graz, Austria
| | - Campbell W Gourlay
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury, CT2 7NJ Kent, UK
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96
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Castro IG, Eisenberg-Bord M, Persiani E, Rochford JJ, Schuldiner M, Bohnert M. Promethin Is a Conserved Seipin Partner Protein. Cells 2019; 8:E268. [PMID: 30901948 PMCID: PMC6468817 DOI: 10.3390/cells8030268] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 03/03/2019] [Accepted: 03/14/2019] [Indexed: 11/16/2022] Open
Abstract
Seipin (BSCL2/SPG17) is a key factor in lipid droplet (LD) biology, and its dysfunction results in severe pathologies, including the fat storage disease Berardinelli-Seip congenital lipodystrophy type 2, as well as several neurological seipinopathies. Despite its importance for human health, the molecular role of seipin is still enigmatic. Seipin is evolutionarily conserved from yeast to humans. In yeast, seipin was recently found to cooperate with the lipid droplet organization (LDO) proteins, Ldo16 and Ldo45, two structurally-related proteins involved in LD function and identity that display remote homology to the human protein promethin/TMEM159. In this study, we show that promethin is indeed an LD-associated protein that forms a complex with seipin, and its localization to the LD surface can be modulated by seipin expression levels. We thus identify promethin as a novel seipin partner protein.
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Affiliation(s)
- Inês G Castro
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.
| | - Michal Eisenberg-Bord
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.
| | - Elisa Persiani
- Rowett Institute and Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Aberdeen, AB25 2ZD, UK.
| | - Justin J Rochford
- Rowett Institute and Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Aberdeen, AB25 2ZD, UK.
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.
| | - Maria Bohnert
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Str. 56, 48149 Münster, Germany.
- Cells-in-Motion Cluster of Excellence (EXC 1003-CiM), University of Münster, 48149 Münster, Germany.
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97
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Fanning S, Haque A, Imberdis T, Baru V, Barrasa MI, Nuber S, Termine D, Ramalingam N, Ho GPH, Noble T, Sandoe J, Lou Y, Landgraf D, Freyzon Y, Newby G, Soldner F, Terry-Kantor E, Kim TE, Hofbauer HF, Becuwe M, Jaenisch R, Pincus D, Clish CB, Walther TC, Farese RV, Srinivasan S, Welte MA, Kohlwein SD, Dettmer U, Lindquist S, Selkoe D. Lipidomic Analysis of α-Synuclein Neurotoxicity Identifies Stearoyl CoA Desaturase as a Target for Parkinson Treatment. Mol Cell 2019; 73:1001-1014.e8. [PMID: 30527540 PMCID: PMC6408259 DOI: 10.1016/j.molcel.2018.11.028] [Citation(s) in RCA: 168] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 09/05/2018] [Accepted: 11/19/2018] [Indexed: 01/08/2023]
Abstract
In Parkinson's disease (PD), α-synuclein (αS) pathologically impacts the brain, a highly lipid-rich organ. We investigated how alterations in αS or lipid/fatty acid homeostasis affect each other. Lipidomic profiling of human αS-expressing yeast revealed increases in oleic acid (OA, 18:1), diglycerides, and triglycerides. These findings were recapitulated in rodent and human neuronal models of αS dyshomeostasis (overexpression; patient-derived triplication or E46K mutation; E46K mice). Preventing lipid droplet formation or augmenting OA increased αS yeast toxicity; suppressing the OA-generating enzyme stearoyl-CoA-desaturase (SCD) was protective. Genetic or pharmacological SCD inhibition ameliorated toxicity in αS-overexpressing rat neurons. In a C. elegans model, SCD knockout prevented αS-induced dopaminergic degeneration. Conversely, we observed detrimental effects of OA on αS homeostasis: in human neural cells, excess OA caused αS inclusion formation, which was reversed by SCD inhibition. Thus, monounsaturated fatty acid metabolism is pivotal for αS-induced neurotoxicity, and inhibiting SCD represents a novel PD therapeutic approach.
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Affiliation(s)
- Saranna Fanning
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA; Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Aftabul Haque
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Thibaut Imberdis
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Valeriya Baru
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | | | - Silke Nuber
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Daniel Termine
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Nagendran Ramalingam
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Gary P H Ho
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Tallie Noble
- Mira Costa College, 1 Barnard Drive, Oceanside, CA 92056, USA
| | - Jackson Sandoe
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Yali Lou
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Dirk Landgraf
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Yelena Freyzon
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Gregory Newby
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, MIT, Cambridge, MA 02139, USA
| | - Frank Soldner
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Elizabeth Terry-Kantor
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Tae-Eun Kim
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Harald F Hofbauer
- Institute of Molecular Biosciences, BioTechMed-Graz, University of Graz, 8010 Graz, Austria
| | - Michel Becuwe
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, 655 Huntington Avenue, Boston, MA 02115, USA
| | - Rudolf Jaenisch
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, MIT, Cambridge, MA 02139, USA
| | - David Pincus
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Clary B Clish
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Tobias C Walther
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, 655 Huntington Avenue, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA; HHMI, Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, 655 Huntington Avenue, Boston, MA 02115, USA
| | - Robert V Farese
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, 655 Huntington Avenue, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Supriya Srinivasan
- Department of Chemical Physiology and The Dorris Neuroscience Center, 1 Barnard Drive, Oceanside, CA 92056, USA; The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Michael A Welte
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Sepp D Kohlwein
- Institute of Molecular Biosciences, BioTechMed-Graz, University of Graz, 8010 Graz, Austria
| | - Ulf Dettmer
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
| | - Susan Lindquist
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, MIT, Cambridge, MA 02139, USA; HHMI, Department of Biology, MIT, Cambridge, MA 02139, USA
| | - Dennis Selkoe
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
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98
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Abstract
Lipid droplets are storage organelles at the centre of lipid and energy homeostasis. They have a unique architecture consisting of a hydrophobic core of neutral lipids, which is enclosed by a phospholipid monolayer that is decorated by a specific set of proteins. Originating from the endoplasmic reticulum, lipid droplets can associate with most other cellular organelles through membrane contact sites. It is becoming apparent that these contacts between lipid droplets and other organelles are highly dynamic and coupled to the cycles of lipid droplet expansion and shrinkage. Importantly, lipid droplet biogenesis and degradation, as well as their interactions with other organelles, are tightly coupled to cellular metabolism and are critical to buffer the levels of toxic lipid species. Thus, lipid droplets facilitate the coordination and communication between different organelles and act as vital hubs of cellular metabolism.
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Affiliation(s)
- James A Olzmann
- Department of Nutritional Sciences and Toxicology, University of California-Berkeley, Berkeley, CA, USA.
| | - Pedro Carvalho
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.
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99
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Vanhercke T, Dyer JM, Mullen RT, Kilaru A, Rahman MM, Petrie JR, Green AG, Yurchenko O, Singh SP. Metabolic engineering for enhanced oil in biomass. Prog Lipid Res 2019; 74:103-129. [PMID: 30822461 DOI: 10.1016/j.plipres.2019.02.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 02/21/2019] [Accepted: 02/21/2019] [Indexed: 02/06/2023]
Abstract
The world is hungry for energy. Plant oils in the form of triacylglycerol (TAG) are one of the most reduced storage forms of carbon found in nature and hence represent an excellent source of energy. The myriad of applications for plant oils range across foods, feeds, biofuels, and chemical feedstocks as a unique substitute for petroleum derivatives. Traditionally, plant oils are sourced either from oilseeds or tissues surrounding the seed (mesocarp). Most vegetative tissues, such as leaves and stems, however, accumulate relatively low levels of TAG. Since non-seed tissues constitute the majority of the plant biomass, metabolic engineering to improve their low-intrinsic TAG-biosynthetic capacity has recently attracted significant attention as a novel, sustainable and potentially high-yielding oil production platform. While initial attempts predominantly targeted single genes, recent combinatorial metabolic engineering strategies have focused on the simultaneous optimization of oil synthesis, packaging and degradation pathways (i.e., 'push, pull, package and protect'). This holistic approach has resulted in dramatic, seed-like TAG levels in vegetative tissues. With the first proof of concept hurdle addressed, new challenges and opportunities emerge, including engineering fatty acid profile, translation into agronomic crops, extraction, and downstream processing to deliver accessible and sustainable bioenergy.
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Affiliation(s)
- Thomas Vanhercke
- CSIRO Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Canberra, ACT, Australia.
| | - John M Dyer
- USDA-ARS, US Arid-Land Agricultural Research Center, Maricopa, AZ, USA
| | - Robert T Mullen
- Department of Molecular and Cellular Biology, University of Guelph, ON, Canada
| | - Aruna Kilaru
- Department of Biological Sciences, East Tennessee State University, Johnson City, TN, USA
| | - Md Mahbubur Rahman
- Department of Biological Sciences, East Tennessee State University, Johnson City, TN, USA
| | - James R Petrie
- CSIRO Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Canberra, ACT, Australia; Folear, Goulburn, NSW, Australia
| | - Allan G Green
- CSIRO Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Canberra, ACT, Australia
| | - Olga Yurchenko
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
| | - Surinder P Singh
- CSIRO Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Canberra, ACT, Australia
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100
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Triacylglycerol Metabolism in Drosophila melanogaster. Genetics 2019; 210:1163-1184. [PMID: 30523167 DOI: 10.1534/genetics.118.301583] [Citation(s) in RCA: 107] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2018] [Accepted: 09/11/2018] [Indexed: 12/11/2022] Open
Abstract
Triacylglycerol (TAG) is the most important caloric source with respect to energy homeostasis in animals. In addition to its evolutionarily conserved importance as an energy source, TAG turnover is crucial to the metabolism of structural and signaling lipids. These neutral lipids are also key players in development and disease. Here, we review the metabolism of TAG in the Drosophila model system. Recently, the fruit fly has attracted renewed attention in research due to the unique experimental approaches it affords in studying the tissue-autonomous and interorgan regulation of lipid metabolism in vivo Following an overview of the systemic control of fly body fat stores, we will cover lipid anabolic, enzymatic, and regulatory processes, which begin with the dietary lipid breakdown and de novo lipogenesis that results in lipid droplet storage. Next, we focus on lipolytic processes, which mobilize storage TAG to make it metabolically accessible as either an energy source or as a building block for biosynthesis of other lipid classes. Since the buildup and breakdown of fat involves various organs, we highlight avenues of lipid transport, which are at the heart of functional integration of organismic lipid metabolism. Finally, we draw attention to some "missing links" in basic neutral lipid metabolism and conclude with a perspective on how fly research can be exploited to study functional metabolic roles of diverse lipids.
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