51
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Renne MF, Hariri H. Lipid Droplet-Organelle Contact Sites as Hubs for Fatty Acid Metabolism, Trafficking, and Metabolic Channeling. Front Cell Dev Biol 2021; 9:726261. [PMID: 34595176 PMCID: PMC8477659 DOI: 10.3389/fcell.2021.726261] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 08/12/2021] [Indexed: 01/21/2023] Open
Abstract
Cells prepare for fluctuations in nutrient availability by storing energy in the form of neutral lipids in organelles called Lipid Droplets (LDs). Upon starvation, fatty acids (FAs) released from LDs are trafficked to different cellular compartments to be utilized for membrane biogenesis or as a source of energy. Despite the biochemical pathways being known in detail, the spatio-temporal regulation of FA synthesis, storage, release, and breakdown is not completely understood. Recent studies suggest that FA trafficking and metabolism are facilitated by inter-organelle contact sites that form between LDs and other cellular compartments such as the Endoplasmic Reticulum (ER), mitochondria, peroxisomes, and lysosomes. LD-LD contact sites are also sites where FAs are transferred in a directional manner to support LD growth and expansion. As the storage site of neutral lipids, LDs play a central role in FA homeostasis. In this mini review, we highlight the role of LD contact sites with other organelles in FA trafficking, channeling, and metabolism and discuss the implications for these pathways on cellular lipid and energy homeostasis.
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Affiliation(s)
- Mike F. Renne
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Hanaa Hariri
- Department of Biological Sciences, Wayne State University, Detroit, MI, United States
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52
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Subcellular Localizations of Catalase and Exogenously Added Fatty Acid in Chlamydomonas reinhardtii. Cells 2021; 10:cells10081940. [PMID: 34440712 PMCID: PMC8391285 DOI: 10.3390/cells10081940] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 07/22/2021] [Accepted: 07/26/2021] [Indexed: 02/01/2023] Open
Abstract
Fatty acids are important biological components, yet the metabolism of fatty acids in microalgae is not clearly understood. Previous studies found that Chlamydomonas reinhardtii, the model microalga, incorporates exogenously added fatty acids but metabolizes them differently from animals and yeast. Furthermore, a recent metabolic flux analysis found that the majority of lipid turnover in C. reinhardtii is the recycling of acyl chains from and to membranes, rather than β -oxidation. This indicates that for the alga, the maintenance of existing acyl chains may be more valuable than their breakdown for energy. To gain cell-biological knowledge of fatty acid metabolism in C. reinhardtii, we conducted microscopy analysis with fluorescent probes. First, we found that CAT1 (catalase isoform 1) is in the peroxisomes while CAT2 (catalase isoform 2) is localized in the endoplasmic reticulum, indicating the alga is capable of detoxifying hydrogen peroxide that would be produced during β-oxidation in the peroxisomes. Second, we compared the localization of exogenously added FL-C16 (fluorescently labelled palmitic acid) with fluorescently marked endosomes, mitochondria, peroxisomes, lysosomes, and lipid droplets. We found that exogenously added FL-C16 are incorporated and compartmentalized via a non-endocytic route within 10 min. However, the fluorescence signals from FL-C16 did not colocalize with any marked organelles, including peroxisomes. During triacylglycerol accumulation, the fluorescence signals from FL-C16 were localized in lipid droplets. These results support the idea that membrane turnover is favored over β-oxidation in C. reinhardtii. The knowledge gained in these analyses would aid further studies of the fatty acid metabolism.
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53
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Rahman MA, Kumar R, Sanchez E, Nazarko TY. Lipid Droplets and Their Autophagic Turnover via the Raft-Like Vacuolar Microdomains. Int J Mol Sci 2021; 22:8144. [PMID: 34360917 PMCID: PMC8348048 DOI: 10.3390/ijms22158144] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 07/26/2021] [Accepted: 07/26/2021] [Indexed: 01/01/2023] Open
Abstract
Although once perceived as inert structures that merely serve for lipid storage, lipid droplets (LDs) have proven to be the dynamic organelles that hold many cellular functions. The LDs' basic structure of a hydrophobic core consisting of neutral lipids and enclosed in a phospholipid monolayer allows for quick lipid accessibility for intracellular energy and membrane production. Whereas formed at the peripheral and perinuclear endoplasmic reticulum, LDs are degraded either in the cytosol by lipolysis or in the vacuoles/lysosomes by autophagy. Autophagy is a regulated breakdown of dysfunctional, damaged, or surplus cellular components. The selective autophagy of LDs is called lipophagy. Here, we review LDs and their degradation by lipophagy in yeast, which proceeds via the micrometer-scale raft-like lipid domains in the vacuolar membrane. These vacuolar microdomains form during nutrient deprivation and facilitate internalization of LDs via the vacuolar membrane invagination and scission. The resultant intra-vacuolar autophagic bodies with LDs inside are broken down by vacuolar lipases and proteases. This type of lipophagy is called microlipophagy as it resembles microautophagy, the type of autophagy when substrates are sequestered right at the surface of a lytic compartment. Yeast microlipophagy via the raft-like vacuolar microdomains is a great model system to study the role of lipid domains in microautophagic pathways.
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Affiliation(s)
- Muhammad Arifur Rahman
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA; (M.A.R.); (E.S.)
| | - Ravinder Kumar
- Department of Obstetrics, Gynecology and Reproductive Science, University of California, San Francisco, CA 94143, USA;
| | - Enrique Sanchez
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA; (M.A.R.); (E.S.)
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Taras Y. Nazarko
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA; (M.A.R.); (E.S.)
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54
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Molenaar MR, Yadav KK, Toulmay A, Wassenaar TA, Mari MC, Caillon L, Chorlay A, Lukmantara IE, Haaker MW, Wubbolts RW, Houweling M, Vaandrager AB, Prieur X, Reggiori F, Choudhary V, Yang H, Schneiter R, Thiam AR, Prinz WA, Helms JB. Retinyl esters form lipid droplets independently of triacylglycerol and seipin. J Cell Biol 2021; 220:212517. [PMID: 34323918 PMCID: PMC8327380 DOI: 10.1083/jcb.202011071] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 05/21/2021] [Accepted: 07/07/2021] [Indexed: 11/23/2022] Open
Abstract
Lipid droplets store neutral lipids, primarily triacylglycerol and steryl esters. Seipin plays a role in lipid droplet biogenesis and is thought to determine the site of lipid droplet biogenesis and the size of newly formed lipid droplets. Here we show a seipin-independent pathway of lipid droplet biogenesis. In silico and in vitro experiments reveal that retinyl esters have the intrinsic propensity to sequester and nucleate in lipid bilayers. Production of retinyl esters in mammalian and yeast cells that do not normally produce retinyl esters causes the formation of lipid droplets, even in a yeast strain that produces only retinyl esters and no other neutral lipids. Seipin does not determine the size or biogenesis site of lipid droplets composed of only retinyl esters or steryl esters. These findings indicate that the role of seipin in lipid droplet biogenesis depends on the type of neutral lipid stored in forming droplets.
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Affiliation(s)
- Martijn R Molenaar
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| | - Kamlesh K Yadav
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - Alexandre Toulmay
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - Tsjerk A Wassenaar
- Groningen Biomolecular Sciences and Biotechnology Institute, Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
| | - Muriel C Mari
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Lucie Caillon
- Laboratoire de Physique Statistique, Ecole Normale Supérieure, Paris Sciences et Lettres Research University, Sorbonne Université, Université Pierre-et-Marie-Curie Université Paris 06, Université Paris Diderot, Centre national de la recherche scientifique, Paris, France
| | - Aymeric Chorlay
- Laboratoire de Physique Statistique, Ecole Normale Supérieure, Paris Sciences et Lettres Research University, Sorbonne Université, Université Pierre-et-Marie-Curie Université Paris 06, Université Paris Diderot, Centre national de la recherche scientifique, Paris, France
| | - Ivan E Lukmantara
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Maya W Haaker
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| | - Richard W Wubbolts
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| | - Martin Houweling
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| | - Arie Bas Vaandrager
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| | - Xavier Prieur
- Université de Nantes, Centre national de la recherche scientifique, Institut national de la santé et de la recherche médicale, l'institut du thorax, Nantes, France
| | - Fulvio Reggiori
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Vineet Choudhary
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Hongyuan Yang
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Roger Schneiter
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Abdou Rachid Thiam
- Laboratoire de Physique Statistique, Ecole Normale Supérieure, Paris Sciences et Lettres Research University, Sorbonne Université, Université Pierre-et-Marie-Curie Université Paris 06, Université Paris Diderot, Centre national de la recherche scientifique, Paris, France
| | - William A Prinz
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - J Bernd Helms
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
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55
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Encinar Del Dedo J, Fernández-Golbano IM, Pastor L, Meler P, Ferrer-Orta C, Rebollo E, Geli MI. Coupled sterol synthesis and transport machineries at ER-endocytic contact sites. J Cell Biol 2021; 220:212484. [PMID: 34283201 PMCID: PMC8294947 DOI: 10.1083/jcb.202010016] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Revised: 05/27/2021] [Accepted: 06/29/2021] [Indexed: 12/17/2022] Open
Abstract
Sterols are unevenly distributed within cellular membranes. How their biosynthetic and transport machineries are organized to generate heterogeneity is largely unknown. We previously showed that the yeast sterol transporter Osh2 is recruited to endoplasmic reticulum (ER)–endocytic contacts to facilitate actin polymerization. We now find that a subset of sterol biosynthetic enzymes also localizes at these contacts and interacts with Osh2 and the endocytic machinery. Following the sterol dynamics, we show that Osh2 extracts sterols from these subdomains, which we name ERSESs (ER sterol exit sites). Further, we demonstrate that coupling of the sterol synthesis and transport machineries is required for endocytosis in mother cells, but not in daughters, where plasma membrane loading with accessible sterols and endocytosis are linked to secretion.
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Affiliation(s)
| | | | - Laura Pastor
- Institute for Molecular Biology of Barcelona, Spanish Research Council, Barcelona, Spain
| | - Paula Meler
- Institute for Molecular Biology of Barcelona, Spanish Research Council, Barcelona, Spain
| | - Cristina Ferrer-Orta
- Institute for Molecular Biology of Barcelona, Spanish Research Council, Barcelona, Spain
| | - Elena Rebollo
- Institute for Molecular Biology of Barcelona, Spanish Research Council, Barcelona, Spain
| | - Maria Isabel Geli
- Institute for Molecular Biology of Barcelona, Spanish Research Council, Barcelona, Spain
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56
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Rao MJ, Goodman JM. Seipin: harvesting fat and keeping adipocytes healthy. Trends Cell Biol 2021; 31:912-923. [PMID: 34215489 DOI: 10.1016/j.tcb.2021.06.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 05/29/2021] [Accepted: 06/03/2021] [Indexed: 01/17/2023]
Abstract
Seipin is a key protein in the assembly of cytoplasmic lipid droplets (cLDs) and their maintenance at endoplasmic reticulum (ER)-LD junctions; the absence of seipin results in generalized lipodystrophy. How seipin mediates LD dynamics and prevents lipodystrophy are not well understood. New evidence suggests that seipin attracts triglyceride monomers from the ER to sites of droplet formation. By contrast, seipin may not be directly involved in the assembly of nuclear LDs and may actually suppress their formation at a distance. Seipin promotes adipogenesis, but lipodystrophy may also involve postadipogenic effects. We hypothesize that among these are a cycle of runaway lipolysis and lipotoxicity caused by aberrant LDs, resulting in a depletion of fat stores and a failure of adipose and other cells to thrive.
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Affiliation(s)
- Monala Jayaprakash Rao
- Department of Pharmacology, University of Texas Southwestern Medical School, Dallas, TX 75390-9041, USA
| | - Joel M Goodman
- Department of Pharmacology, University of Texas Southwestern Medical School, Dallas, TX 75390-9041, USA.
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57
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Sanya DRA, Onésime D, Passoth V, Maiti MK, Chattopadhyay A, Khot MB. Yeasts of the Blastobotrys genus are promising platform for lipid-based fuels and oleochemicals production. Appl Microbiol Biotechnol 2021; 105:4879-4897. [PMID: 34110474 DOI: 10.1007/s00253-021-11354-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 04/29/2021] [Accepted: 05/16/2021] [Indexed: 12/31/2022]
Abstract
Strains of the yeast genus Blastobotrys (subphylum Saccharomycotina) represent a valuable biotechnological resource for basic biochemistry research, single-cell protein, and heterologous protein production processes. Species of this genus are dimorphic, non-pathogenic, thermotolerant, and can assimilate a variety of hydrophilic and hydrophobic substrates. These can constitute a single-cell oil platform in an emerging bio-based economy as oleaginous traits have been discovered recently. However, the regulatory network of lipogenesis in these yeasts is poorly understood. To keep pace with the growing market demands for lipid-derived products, it is critical to understand the lipid biosynthesis in these unconventional yeasts to pinpoint what governs the preferential channelling of carbon flux into lipids instead of the competing pathways. This review summarizes information relevant to the regulation of lipid metabolic pathways and prospects of metabolic engineering in Blastobotrys yeasts for their application in food, feed, and beyond, particularly for fatty acid-based fuels and oleochemicals. KEY POINTS: • The production of biolipids by heterotrophic yeasts is reviewed. • Summary of information concerning lipid metabolism regulation is highlighted. • Special focus on the importance of diacylglycerol acyltransferases encoding genes in improving lipid production is made.
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Affiliation(s)
- Daniel Ruben Akiola Sanya
- Université Paris-Saclay, Institut Micalis, Diversité génomique et fonctionnelle des levures, domaine de Vilvert, 78350, Jouy-en-Josas, France.
| | - Djamila Onésime
- Université Paris-Saclay, Institut Micalis, Diversité génomique et fonctionnelle des levures, domaine de Vilvert, 78350, Jouy-en-Josas, France
| | - Volkmar Passoth
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, PO Box 7015, SE-750 07, Uppsala, Sweden
| | - Mrinal K Maiti
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India
| | - Atrayee Chattopadhyay
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India
| | - Mahesh B Khot
- Laboratorio de Recursos Renovables, Centro de Biotecnologia, Universidad de Concepcion, Barrio Universitario s/n, Concepcion, Chile
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58
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Gao M, Liu L, Wang X, Mak HY, Liu G, Yang H. GPAT3 deficiency alleviates insulin resistance and hepatic steatosis in a mouse model of severe congenital generalized lipodystrophy. Hum Mol Genet 2021; 29:432-443. [PMID: 31873720 DOI: 10.1093/hmg/ddz300] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 11/12/2019] [Accepted: 12/05/2019] [Indexed: 12/17/2022] Open
Abstract
Berardinelli-Seip congenital lipodystrophy type 2 (BSCL2) is the most severe form of human lipodystrophy and is caused by loss-of-function mutations in the BSCL2/seipin gene. Exactly how seipin may regulate adipogenesis remains unclear. A recent study in vitro suggested that seipin may function to inhibit the activity of glycerol-3-phosphate acyltransferases (GPATs), and increased GPAT activity may be responsible for the defective adipogenesis under seipin deficiency. Here we generated Seipin-/-Gpat3-/- mice, which had mild but significant recovery of white adipose tissue mass over Seipin-/- mice. The mass of brown adipose tissue (BAT) of the Seipin-/-Gpat3-/- mice was almost completely restored to normal level. Importantly, the Seipin-/-Gpat3-/- mice showed significant improvement in liver steatosis and insulin sensitivity over Seipin-/- mice, which is attributable to the increased BAT mass and to the enhanced browning of the subcutaneous fat of the Seipin-/-Gpat3-/- mice. Together, our results establish a functional link between seipin and GPAT3 in vivo and suggest that GPAT inhibitors may have beneficial effects on BSCL2 patients.
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Affiliation(s)
- Mingming Gao
- Laboratory of Lipid Metabolism, Hebei Medical University, Shijiazhuang, Hebei 050017, China
| | - Lin Liu
- Laboratory of Lipid Metabolism, Hebei Medical University, Shijiazhuang, Hebei 050017, China
| | - Xiaowei Wang
- Laboratory of Lipid Metabolism, Hebei Medical University, Shijiazhuang, Hebei 050017, China
| | - Hoi Yin Mak
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia
| | - George Liu
- Institute of Cardiovascular Sciences and Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Peking University Health Science Center, Beijing 100191, China
| | - Hongyuan Yang
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia
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59
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Joshi AS, Ragusa JV, Prinz WA, Cohen S. Multiple C2 domain-containing transmembrane proteins promote lipid droplet biogenesis and growth at specialized endoplasmic reticulum subdomains. Mol Biol Cell 2021; 32:1147-1157. [PMID: 33826368 PMCID: PMC8351558 DOI: 10.1091/mbc.e20-09-0590] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 03/23/2021] [Accepted: 03/29/2021] [Indexed: 12/11/2022] Open
Abstract
Lipid droplets (LDs) are neutral lipid-containing organelles enclosed in a single monolayer of phospholipids. LD formation begins with the accumulation of neutral lipids within the bilayer of the endoplasmic reticulum (ER) membrane. It is not known how the sites of formation of nascent LDs in the ER membrane are determined. Here we show that multiple C2 domain-containing transmembrane proteins, MCTP1 and MCTP2, are at sites of LD formation in specialized ER subdomains. We show that the transmembrane domain (TMD) of these proteins is similar to a reticulon homology domain. Like reticulons, these proteins tubulate the ER membrane and favor highly curved regions of the ER. Our data indicate that the MCTP TMDs promote LD biogenesis, increasing LD number. MCTPs colocalize with seipin, a protein involved in LD biogenesis, but form more stable microdomains in the ER. The MCTP C2 domains bind charged lipids and regulate LD size, likely by mediating ER-LD contact sites. Together, our data indicate that MCTPs form microdomains within ER tubules that regulate LD biogenesis, size, and ER-LD contacts. Interestingly, MCTP punctae colocalized with other organelles as well, suggesting that these proteins may play a general role in linking tubular ER to organelle contact sites.
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Affiliation(s)
- Amit S. Joshi
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
- Department of Biochemistry, Cell and Molecular Biology, University of Tennessee, Knoxville, TN 37916
| | - Joey V. Ragusa
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - William A. Prinz
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20814
| | - Sarah Cohen
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
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60
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Khaddaj R, Mari M, Cottier S, Reggiori F, Schneiter R. The surface of lipid droplets constitutes a barrier for endoplasmic reticulum-resident integral membrane proteins. J Cell Sci 2021; 135:268334. [PMID: 34028531 DOI: 10.1242/jcs.256206] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 04/14/2021] [Indexed: 12/12/2022] Open
Abstract
Lipid droplets (LDs) are globular subcellular structures that store neutral lipids. LDs are closely associated with the endoplasmic reticulum (ER) and are limited by a phospholipid monolayer harboring a specific set of proteins. Most of these proteins associate with LDs through either an amphipathic helix or a membrane-embedded hairpin motif. Here, we address the question of whether integral membrane proteins can localize to the surface of LDs. To test this, we fused perilipin 3 (PLIN3), a mammalian LD-targeted protein, to ER-resident proteins. The resulting fusion proteins localized to the periphery of LDs in both yeast and mammalian cells. This peripheral LD localization of the fusion proteins, however, was due to a redistribution of the ER around LDs, as revealed by bimolecular fluorescence complementation between ER- and LD-localized partners. A LD-tethering function of PLIN3-containing membrane proteins was confirmed by fusing PLIN3 to the cytoplasmic domain of an outer mitochondrial membrane protein, OM14. Expression of OM14-PLIN3 induced a close apposition between LDs and mitochondria. These data indicate that the ER-LD junction constitutes a barrier for ER-resident integral membrane proteins.
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Affiliation(s)
- Rasha Khaddaj
- Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland
| | - Muriel Mari
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Stéphanie Cottier
- Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland
| | - Fulvio Reggiori
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Roger Schneiter
- Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland
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61
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Jansen RLM, Santana-Molina C, van den Noort M, Devos DP, van der Klei IJ. Comparative Genomics of Peroxisome Biogenesis Proteins: Making Sense of the PEX Proteins. Front Cell Dev Biol 2021; 9:654163. [PMID: 34095119 PMCID: PMC8172628 DOI: 10.3389/fcell.2021.654163] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 04/21/2021] [Indexed: 11/29/2022] Open
Abstract
PEX genes encode proteins involved in peroxisome biogenesis and proliferation. Using a comparative genomics approach, we clarify the evolutionary relationships between the 37 known PEX proteins in a representative set of eukaryotes, including all common model organisms, pathogenic unicellular eukaryotes and human. A large number of previously unknown PEX orthologs were identified. We analyzed all PEX proteins, their conservation and domain architecture and defined the core set of PEX proteins that is required to make a peroxisome. The molecular processes in peroxisome biogenesis in different organisms were put into context, showing that peroxisomes are not static organelles in eukaryotic evolution. Organisms that lack peroxisomes still contain a few PEX proteins, which probably play a role in alternative processes. Finally, the relationships between PEX proteins of two large families, the Pex11 and Pex23 families, were analyzed, thereby contributing to the understanding of their complicated and sometimes incorrect nomenclature. We provide an exhaustive overview of this important eukaryotic organelle.
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Affiliation(s)
- Renate L M Jansen
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
| | - Carlos Santana-Molina
- Centro Andaluz de Biología del Desarrollo, Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Seville, Spain
| | - Marco van den Noort
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
| | - Damien P Devos
- Centro Andaluz de Biología del Desarrollo, Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Seville, Spain
| | - Ida J van der Klei
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
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62
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Roberts MA, Segura-Roman A, Olzmann JA. Organelle Biogenesis: ER Shape Influences Lipid Droplet Nucleation. Curr Biol 2021; 30:R770-R773. [PMID: 32634419 DOI: 10.1016/j.cub.2020.05.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Lipid droplets (LDs) are neutral lipid storage organelles assembled at the endoplasmic reticulum (ER). A new study reveals that the high membrane curvature of ER tubules catalyzes the nucleation of a neutral lipid lens, an early step in LD biogenesis.
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Affiliation(s)
- Melissa A Roberts
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Ashley Segura-Roman
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - James A Olzmann
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Chan Zuckerberg Biohub, San Francisco, CA 94720, USA.
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63
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Guéguen N, Le Moigne D, Amato A, Salvaing J, Maréchal E. Lipid Droplets in Unicellular Photosynthetic Stramenopiles. FRONTIERS IN PLANT SCIENCE 2021; 12:639276. [PMID: 33968100 PMCID: PMC8100218 DOI: 10.3389/fpls.2021.639276] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 03/17/2021] [Indexed: 06/12/2023]
Abstract
The Heterokonta or Stramenopile phylum comprises clades of unicellular photosynthetic species, which are promising for a broad range of biotechnological applications, based on their capacity to capture atmospheric CO2 via photosynthesis and produce biomolecules of interest. These molecules include triacylglycerol (TAG) loaded inside specific cytosolic bodies, called the lipid droplets (LDs). Understanding TAG production and LD biogenesis and function in photosynthetic stramenopiles is therefore essential, and is mostly based on the study of a few emerging models, such as the pennate diatom Phaeodactylum tricornutum and eustigmatophytes, such as Nannochloropsis and Microchloropsis species. The biogenesis of cytosolic LD usually occurs at the level of the endoplasmic reticulum. However, stramenopile cells contain a complex plastid deriving from a secondary endosymbiosis, limited by four membranes, the outermost one being connected to the endomembrane system. Recent cell imaging and proteomic studies suggest that at least some cytosolic LDs might be associated to the surface of the complex plastid, via still uncharacterized contact sites. The carbon length and number of double bonds of the acyl groups contained in the TAG molecules depend on their origin. De novo synthesis produces long-chain saturated or monounsaturated fatty acids (SFA, MUFA), whereas subsequent maturation processes lead to very long-chain polyunsaturated FA (VLC-PUFA). TAG composition in SFA, MUFA, and VLC-PUFA reflects therefore the metabolic context that gave rise to the formation of the LD, either via an early partitioning of carbon following FA de novo synthesis and/or a recycling of FA from membrane lipids, e.g., plastid galactolipids or endomembrane phosphor- or betaine lipids. In this review, we address the relationship between cytosolic LDs and the complex membrane compartmentalization within stramenopile cells, the metabolic routes leading to TAG accumulation, and the physiological conditions that trigger LD production, in response to various environmental factors.
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64
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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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65
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Rosado A, Bayer EM. Geometry and cellular function of organelle membrane interfaces. PLANT PHYSIOLOGY 2021; 185:650-662. [PMID: 33793898 PMCID: PMC8133572 DOI: 10.1093/plphys/kiaa079] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 10/17/2020] [Indexed: 05/09/2023]
Abstract
A vast majority of cellular processes take root at the surface of biological membranes. By providing a two-dimensional platform with limited diffusion, membranes are, by nature, perfect devices to concentrate signaling and metabolic components. As such, membranes often act as "key processors" of cellular information. Biological membranes are highly dynamic and deformable and can be shaped into curved, tubular, or flat conformations, resulting in differentiated biophysical properties. At membrane contact sites, membranes from adjacent organelles come together into a unique 3D configuration, forming functionally distinct microdomains, which facilitate spatially regulated functions, such as organelle communication. Here, we describe the diversity of geometries of contact site-forming membranes in different eukaryotic organisms and explore the emerging notion that their shape, 3D architecture, and remodeling jointly define their cellular activity. The review also provides selected examples highlighting changes in membrane contact site architecture acting as rapid and local responses to cellular perturbations, and summarizes our current understanding of how those structural changes confer functional specificity to those cellular territories.
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Affiliation(s)
- Abel Rosado
- Department of Botany, University of British Columbia, Vancouver, BC, Canada
| | - Emmanuelle M Bayer
- Univ. Bordeaux, CNRS, Laboratoire de Biogenèse Membranaire, UMR 5200, F-33140 Villenave d’Ornon, France
- Author for communication:
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66
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Santinho A, Chorlay A, Foret L, Thiam AR. Fat inclusions strongly alter membrane mechanics. Biophys J 2021; 120:607-617. [PMID: 33460598 PMCID: PMC7896029 DOI: 10.1016/j.bpj.2021.01.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 12/04/2020] [Accepted: 01/07/2021] [Indexed: 12/18/2022] Open
Abstract
Neutral lipids (NLs) are apolar oil molecules synthesized in the endoplasmic reticulum bilayer upon diverse biological stimuli. NLs synthesized are released in the hydrophobic core of the bilayer. At a critical concentration, NLs condense by phase separation and nucleate a lipid droplet (LD). After an LD forms, a fraction of NLs can be present in the bilayer but at a concentration below that of the nucleation. Here, we study whether and how the accumulation of NLs alters a lipid bilayer's mechanical properties. In synthetic systems, we found that NLs proffer unusual bilayer stretching capacities, especially in the presence of negatively curved phospholipids. This impact becomes spectacular when an LD is contiguous with the bilayer and supplies it with NLs. The tested NLs markedly decrease the bilayer area expansion modulus and significantly increase lysis tension but had opposite effects on membrane bending rigidity. Our data unveil how NL molecules modify overall membrane mechanics, the alteration of which may be linked to pathologies or anticancer treatments targeting NLs.
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Affiliation(s)
- Alexandre Santinho
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, Paris, France
| | - Aymeric Chorlay
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, Paris, France
| | - Lionel Foret
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, Paris, France
| | - Abdou Rachid Thiam
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, Paris, France.
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67
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Wang L, Liu J, Miao Z, Pan Q, Cao W. Lipid droplets and their interactions with other organelles in liver diseases. Int J Biochem Cell Biol 2021; 133:105937. [PMID: 33529713 DOI: 10.1016/j.biocel.2021.105937] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 12/07/2020] [Accepted: 01/06/2021] [Indexed: 02/01/2023]
Abstract
Lipid droplets are cellular organelles used for lipid storage with a hydrophobic core of neutral lipids enclosed by a phospholipid monolayer. Besides presenting as giant single organelles in fat tissue, lipid droplets are also widely present as a multitude of small structures in hepatocytes, where they play key roles in health and disease of the liver. In addition to lipid storage, lipid droplets are also directly involved in lipid metabolism, membrane biosynthesis, cell signaling, inflammation, pathogen-host interaction and cancer development. In addition, they interact with other cellular organelles to regulate cellular biology. It is fair to say that the exact functions of lipid droplets in cellular physiology remain largely obscure. Thus prompted, here we aim to analyze the corpus of contemporary biomedical literature to create a framework as to how the role of lipid droplets in hepatocyte physiology and pathophysiology should be understood. The resulting framework should help understanding the interaction of lipid droplets with other organelles in important liver diseases, including fatty liver disease, viral hepatitis and liver cancer and direct further research directions.
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Affiliation(s)
- Ling Wang
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, the Netherlands
| | - Jiaye Liu
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, the Netherlands
| | - Zhijiang Miao
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, the Netherlands
| | - Qiuwei Pan
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, the Netherlands.
| | - Wanlu Cao
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, the Netherlands.
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68
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Shiino H, Furuta S, Kojima R, Kimura K, Endo T, Tamura Y. Phosphatidylserine flux into mitochondria unveiled by organelle-targeted Escherichia coli phosphatidylserine synthase PssA. FEBS J 2020; 288:3285-3299. [PMID: 33283454 DOI: 10.1111/febs.15657] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 11/12/2020] [Accepted: 12/04/2020] [Indexed: 11/26/2022]
Abstract
Most phospholipids are synthesised in the endoplasmic reticulum and distributed to other cellular membranes. Although the vesicle transport contributes to the phospholipid distribution among the endomembrane system, exactly how phospholipids are transported to, from and between mitochondrial membranes remains unclear. To gain insights into phospholipid transport routes into mitochondria, we expressed the Escherichia coli phosphatidylserine (PS) synthase PssA in various membrane compartments with distinct membrane topologies in yeast cells lacking a sole PS synthase (Cho1). Interestingly, PssA could complement loss of Cho1 when targeted to the endoplasmic reticulum (ER), peroxisome, or lipid droplet membranes. Synthesised PS could be converted to phosphatidylethanolamine (PE) by Psd1, the mitochondrial PS decarboxylase, suggesting that phospholipids synthesised in the peroxisomes and low doses (LDs) can efficiently reach mitochondria. Furthermore, we found that PssA which has been integrated into the mitochondrial inner membrane (MIM) from the matrix side could partially complement the loss of Cho1. The PS synthesised in the MIM was also converted to PE, indicating that PS flops across the MIM to become PE. These findings expand our understanding of the intracellular phospholipid transport routes via mitochondria.
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Affiliation(s)
| | | | | | | | - Toshiya Endo
- Faculty of Life Sciences, Kyoto Sangyo University, Japan.,Institute for Protein Dynamics, Kyoto Sangyo University, Japan
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69
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Thiam AR, Ikonen E. Lipid Droplet Nucleation. Trends Cell Biol 2020; 31:108-118. [PMID: 33293168 DOI: 10.1016/j.tcb.2020.11.006] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 11/11/2020] [Accepted: 11/12/2020] [Indexed: 02/06/2023]
Abstract
All living organisms can make lipid droplets (LDs), intracellular oil-in-water droplets, surrounded by a phospholipid and protein monolayer. LDs are at the nexus of cellular lipid metabolism and function in diverse biological processes. During the past decade, multidisciplinary approaches have shed light on LD assembly steps from the endoplasmic reticulum (ER): nucleation, growth, budding, and formation of a separate organelle. However, the molecular mechanisms underpinning these steps remain elusive. In this review, we focus on the nucleation step, defining where and how LD assembly is initiated. We present how membrane biophysical and physicochemical properties control this step and how proteins act on it to orchestrate LD biogenesis.
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Affiliation(s)
- Abdou Rachid Thiam
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, F-75005 Paris, France.
| | - Elina Ikonen
- Department of Anatomy and Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland; Minerva Foundation Institute for Medical Research, 00290 Helsinki, Finland.
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70
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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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71
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Cao Z, Wang X, Huang X, Mak HY. Are endoplasmic reticulum subdomains shaped by asymmetric distribution of phospholipids? Evidence from a C. elegans model system. Bioessays 2020; 43:e2000199. [PMID: 33169432 DOI: 10.1002/bies.202000199] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 09/13/2020] [Accepted: 09/18/2020] [Indexed: 12/19/2022]
Abstract
Physical contact between organelles are widespread, in part to facilitate the shuttling of protein and lipid cargoes for cellular homeostasis. How do protein-protein and protein-lipid interactions shape organelle subdomains that constitute contact sites? The endoplasmic reticulum (ER) forms extensive contacts with multiple organelles, including lipid droplets (LDs) that are central to cellular fat storage and mobilization. Here, we focus on ER-LD contacts that are highlighted by the conserved protein seipin, which promotes LD biogenesis and expansion. Seipin is enriched in ER tubules that form cage-like structures around a subset of LDs. Such enrichment is strongly dependent on polyunsaturated and cyclopropane fatty acids. Based on these findings, we speculate on molecular events that lead to the formation of seipin-positive peri-LD cages in which protein movement is restricted. We hypothesize that asymmetric distribution of specific phospholipids distinguishes cage membrane tubules from the bulk ER.
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Affiliation(s)
- Zhe Cao
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Xiaowei Wang
- Department of Chemistry, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Xuhui Huang
- Department of Chemistry, The Hong Kong University of Science and Technology, 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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72
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Xu C, Fan J, Shanklin J. Metabolic and functional connections between cytoplasmic and chloroplast triacylglycerol storage. Prog Lipid Res 2020; 80:101069. [DOI: 10.1016/j.plipres.2020.101069] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 10/23/2020] [Accepted: 10/24/2020] [Indexed: 12/14/2022]
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73
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Goetzman ES, Bharathi SS, Zhang Y, Zhao XJ, Dobrowolski SF, Peasley K, Sims-Lucas S, Monga SP. Impaired mitochondrial medium-chain fatty acid oxidation drives periportal macrovesicular steatosis in sirtuin-5 knockout mice. Sci Rep 2020; 10:18367. [PMID: 33110171 PMCID: PMC7591893 DOI: 10.1038/s41598-020-75615-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 10/08/2020] [Indexed: 12/14/2022] Open
Abstract
Medium-chain triglycerides (MCT), containing C8-C12 fatty acids, are used to treat several pediatric disorders and are widely consumed as a nutritional supplement. Here, we investigated the role of the sirtuin deacylase Sirt5 in MCT metabolism by feeding Sirt5 knockout mice (Sirt5KO) high-fat diets containing either C8/C10 fatty acids or coconut oil, which is rich in C12, for five weeks. Coconut oil, but not C8/C10 feeding, induced periportal macrovesicular steatosis in Sirt5KO mice. 14C-C12 degradation was significantly reduced in Sirt5KO liver. This decrease was localized to the mitochondrial β-oxidation pathway, as Sirt5KO mice exhibited no change in peroxisomal C12 β-oxidation. Endoplasmic reticulum ω-oxidation, a minor fatty acid degradation pathway known to be stimulated by C12 accumulation, was increased in Sirt5KO liver. Mice lacking another mitochondrial C12 oxidation enzyme, long-chain acyl-CoA dehydrogenase (LCAD), also developed periportal macrovesicular steatosis when fed coconut oil, confirming that defective mitochondrial C12 oxidation is sufficient to induce the steatosis phenotype. Sirt5KO liver exhibited normal LCAD activity but reduced mitochondrial acyl-CoA synthetase activity with C12. These studies reveal a role for Sirt5 in regulating the hepatic response to MCT and may shed light into the pathogenesis of periportal steatosis, a hallmark of human pediatric non-alcoholic fatty liver disease.
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Affiliation(s)
- Eric S Goetzman
- Department of Pediatrics, Children's Hospital of Pittsburgh of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
- Pittsburgh Liver Research Center, University of Pittsburgh Medical Center, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
| | - Sivakama S Bharathi
- Department of Pediatrics, Children's Hospital of Pittsburgh of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Yuxun Zhang
- Department of Pediatrics, Children's Hospital of Pittsburgh of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Xue-Jun Zhao
- Department of Pediatrics, Children's Hospital of Pittsburgh of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Steven F Dobrowolski
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Kevin Peasley
- Department of Pediatrics, Children's Hospital of Pittsburgh of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Sunder Sims-Lucas
- Department of Pediatrics, Children's Hospital of Pittsburgh of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Satdarshan P Monga
- Division of Experimental Pathology, Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Division of Gastroenterology, Hepatology and Nutrition, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Pittsburgh Liver Research Center, University of Pittsburgh Medical Center, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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74
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Mast FD, Rachubinski RA, Aitchison JD. Peroxisome prognostications: Exploring the birth, life, and death of an organelle. J Cell Biol 2020; 219:133827. [PMID: 32211898 PMCID: PMC7054992 DOI: 10.1083/jcb.201912100] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 01/30/2020] [Accepted: 01/31/2020] [Indexed: 02/07/2023] Open
Abstract
Peroxisomes play a central role in human health and have biochemical properties that promote their use in many biotechnology settings. With a primary role in lipid metabolism, peroxisomes share a niche with lipid droplets within the endomembrane-secretory system. Notably, factors in the ER required for the biogenesis of peroxisomes also impact the formation of lipid droplets. The dynamic interface between peroxisomes and lipid droplets, and also between these organelles and the ER and mitochondria, controls their metabolic flux and their dynamics. Here, we review our understanding of peroxisome biogenesis to propose and reframe models for understanding how peroxisomes are formed in cells. To more fully understand the roles of peroxisomes and to take advantage of their many properties that may prove useful in novel therapeutics or biotechnology applications, we recast mechanisms controlling peroxisome biogenesis in a framework that integrates inference from these models with experimental data.
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Affiliation(s)
- Fred D Mast
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle WA
| | | | - John D Aitchison
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle WA.,Department of Pediatrics, University of Washington, Seattle, WA
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75
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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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76
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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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77
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Ganesan S, Tavassoli M, Shabits BN, Zaremberg V. Tubular ER Associates With Diacylglycerol-Rich Structures During Lipid Droplet Consumption. Front Cell Dev Biol 2020; 8:700. [PMID: 32850820 PMCID: PMC7403446 DOI: 10.3389/fcell.2020.00700] [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: 05/31/2020] [Accepted: 07/09/2020] [Indexed: 11/13/2022] Open
Abstract
Growth resumption from stationary phase in Saccharomyces cerevisiae, is characterized by lipid droplet (LD) consumption and channeling of lipid precursors toward synthesis of membranes. We have previously determined that triacylglycerol lipolysis contributes to a pool of diacylglycerol (DAG) associated with the yeast vacuole that is enriched in structures that are in close proximity to LDs. In this study we have monitored these structures using a DAG sensor fused to GFP during isolation of LDs. A unique fraction containing the DAG sensor, with low presence of LDs, was identified. Membranes enriched in the DAG probe were obtained by immunoaffinity purification using a GFP nanobody, and the associated proteome was investigated by mass spectrometry. It was determined this LD-associated fraction was enriched in proteins known to shape the tubular endoplasmic reticulum (ER) like Yop1, Sey1, Rtn1, and Rtn2. Consistently, cells lacking three of these proteins (rtn1Δ rtn2Δ yop1Δ) exhibited delayed LD consumption, larger LDs and abnormal LD distribution. In addition, the triple mutant displayed aberrant localization of the DAG sensor after 5 h of growth resumption from stationary phase. Manipulation of DAG levels by overexpression of the DAG kinase Dgk1, impacted localization of the DAG probe and affected fitness of the triple mutant. Altogether these results link LD consumption to tubular ER expansion as a gateway of lipid precursors that otherwise accumulate in vacuolar associated membranes or other internal compartments. Furthermore, conversion of DAG to phosphatidic acid (PA) in the absence of a functional tubular ER was toxic to cells, suggesting the ratio of PA to DAG is critical to allow growth progression.
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Affiliation(s)
| | - Marjan Tavassoli
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Brittney N Shabits
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Vanina Zaremberg
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
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78
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Wu F, de Boer R, Krikken AM, Akşit A, Bordin N, Devos DP, van der Klei IJ. Pex24 and Pex32 are required to tether peroxisomes to the ER for organelle biogenesis, positioning and segregation in yeast. J Cell Sci 2020; 133:jcs246983. [PMID: 32665322 DOI: 10.1242/jcs.246983] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 07/06/2020] [Indexed: 12/12/2022] Open
Abstract
The yeast Hansenula polymorpha contains four members of the Pex23 family of peroxins, which characteristically contain a DysF domain. Here we show that all four H. polymorpha Pex23 family proteins localize to the endoplasmic reticulum (ER). Pex24 and Pex32, but not Pex23 and Pex29, predominantly accumulate at peroxisome-ER contacts. Upon deletion of PEX24 or PEX32 - and to a much lesser extent, of PEX23 or PEX29 - peroxisome-ER contacts are lost, concomitant with defects in peroxisomal matrix protein import, membrane growth, and organelle proliferation, positioning and segregation. These defects are suppressed by the introduction of an artificial peroxisome-ER tether, indicating that Pex24 and Pex32 contribute to tethering of peroxisomes to the ER. Accumulation of Pex32 at these contact sites is lost in cells lacking the peroxisomal membrane protein Pex11, in conjunction with disruption of the contacts. This indicates that Pex11 contributes to Pex32-dependent peroxisome-ER contact formation. The absence of Pex32 has no major effect on pre-peroxisomal vesicles that occur in pex3 atg1 deletion cells.
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Affiliation(s)
- Fei Wu
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9300CC Groningen, The Netherlands
| | - Rinse de Boer
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9300CC Groningen, The Netherlands
| | - Arjen M Krikken
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9300CC Groningen, The Netherlands
| | - Arman Akşit
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9300CC Groningen, The Netherlands
| | - Nicola Bordin
- Centro Andaluz de Biología del Desarrollo, CSIC, Universidad Pablo de Olavide, Carretera de Utrera, Km.1, Seville 41013, Spain
| | - Damien P Devos
- Centro Andaluz de Biología del Desarrollo, CSIC, Universidad Pablo de Olavide, Carretera de Utrera, Km.1, Seville 41013, Spain
| | - Ida J van der Klei
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9300CC Groningen, The Netherlands
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79
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80
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Determinants of Endoplasmic Reticulum-to-Lipid Droplet Protein Targeting. Dev Cell 2020; 54:471-487.e7. [PMID: 32730754 DOI: 10.1016/j.devcel.2020.07.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 05/11/2020] [Accepted: 07/07/2020] [Indexed: 02/06/2023]
Abstract
Lipid droplet (LD) formation from the endoplasmic reticulum (ER) is accompanied by the targeting and accumulation of specific hydrophobic, membrane-embedded proteins on LDs. The determinants of this process are unknown. Here, we study the hydrophobic membrane motifs of two Drosophila melanogaster proteins, GPAT4 and ALG14, that utilize this pathway, and we identify crucial sequence features that mediate LD accumulation. Molecular dynamics simulations and studies in cells reveal that LD targeting of these motifs requires deeply inserted tryptophans that have lower free energy in the LD oil phase and positively charged residues near predicted hairpin hinges that become less constrained in the LD environment. Analyzing hydrophobic motifs from similar LD-targeting proteins, it appears that the distribution of tryptophan and positively charged residues distinguishes them from non-LD-targeting membrane motifs. Our studies identify specific sequence features and principles of hydrophobic membrane motifs that mediate their accumulation on LDs.
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81
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Silva BSC, DiGiovanni L, Kumar R, Carmichael RE, Kim PK, Schrader M. Maintaining social contacts: The physiological relevance of organelle interactions. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118800. [PMID: 32712071 PMCID: PMC7377706 DOI: 10.1016/j.bbamcr.2020.118800] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 07/12/2020] [Accepted: 07/19/2020] [Indexed: 02/07/2023]
Abstract
Membrane-bound organelles in eukaryotic cells form an interactive network to coordinate and facilitate cellular functions. The formation of close contacts, termed "membrane contact sites" (MCSs), represents an intriguing strategy for organelle interaction and coordinated interplay. Emerging research is rapidly revealing new details of MCSs. They represent ubiquitous and diverse structures, which are important for many aspects of cell physiology and homeostasis. Here, we provide a comprehensive overview of the physiological relevance of organelle contacts. We focus on mitochondria, peroxisomes, the Golgi complex and the plasma membrane, and discuss the most recent findings on their interactions with other subcellular organelles and their multiple functions, including membrane contacts with the ER, lipid droplets and the endosomal/lysosomal compartment.
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Affiliation(s)
- Beatriz S C Silva
- College of Life and Environmental Sciences, Biosciences, University of Exeter, Exeter EX4 4QD, Devon, UK
| | - Laura DiGiovanni
- Program in Cell Biology, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Rechal Kumar
- College of Life and Environmental Sciences, Biosciences, University of Exeter, Exeter EX4 4QD, Devon, UK
| | - Ruth E Carmichael
- College of Life and Environmental Sciences, Biosciences, University of Exeter, Exeter EX4 4QD, Devon, UK.
| | - Peter K Kim
- Program in Cell Biology, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada.
| | - Michael Schrader
- College of Life and Environmental Sciences, Biosciences, University of Exeter, Exeter EX4 4QD, Devon, UK.
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82
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Téllez-Arreola JL, Silva M, Martínez-Torres A. MCTP-1 modulates neurotransmitter release in C. elegans. Mol Cell Neurosci 2020; 107:103528. [PMID: 32650044 DOI: 10.1016/j.mcn.2020.103528] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 06/17/2020] [Accepted: 06/23/2020] [Indexed: 11/30/2022] Open
Abstract
Multiple C2 and Transmembrane Domain Proteins (MCTPs) are putative calcium sensors. Proteins that contain C2 domains play essential roles in membrane trafficking and exocytosis; however, MCTPs functions in neurotransmitter release are not known. Here we report that in C. elegans mctp-1 is under the control of two promoters - one active in the nervous system and the second in the spermatheca. We generated and characterized a loss of function amt1 mutant and compared it to a previously published loss of function mutant (av112). Loss of mctp-1 function causes defects in egg-laying, crawling velocity, and thrashing rates. Both amt1 and av112 mutants are hyposensitive to the acetylcholinesterase blocker aldicarb, suggesting that MCTP-1 may play a role in synaptic vesicle release.
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Affiliation(s)
- José Luis Téllez-Arreola
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, C.P. 76215 Juriquilla, Querétaro, México; School of Biological Sciences, University of Utah, Salt Lake City, United States
| | - Malan Silva
- School of Biological Sciences, University of Utah, Salt Lake City, United States
| | - Ataúlfo Martínez-Torres
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, C.P. 76215 Juriquilla, Querétaro, México.
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83
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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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84
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Abstract
In this issue, Choudhary et al. (2020. J. Cell Biol.https://doi.org/10.1083/jcb.201910177) address the nature of the ER subdomain from which lipid droplets emanate and how several assembly proteins interact. Their data indicate that seipin/Nem1 marks these sites and provide a detailed working model for assembling the protein complex.
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Affiliation(s)
- Joel M. Goodman
- Department of Pharmacology, University of Texas Southwestern Medical School, Dallas, TX
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85
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Abstract
Lipid droplets (LDs) are now recognized as omnipresent and dynamic subcellular organelles of amazing morphological and functional diversity. Beyond the obvious benefit of having molecules full of chemical energy stored in a dedicated structural entity, LDs may also be viewed as a safe harbor for potentially damaging metabolites. This protective function might in many cases even supersede the relevance of lipid storage for eventual energy gain and membrane biogenesis. Furthermore, the LD surface constitutes a unique membrane environment, creating a platform for hosting specific proteins and thus enabling their interactions. These metabolic hotspots would contribute decisively to compartmentalized metabolism in the cytosol. LDs are also communicating extensively with other subcellular organelles in directing and regulating lipid metabolism. Deciphering the relevance of LD storage and regulation at the organismic level will be essential for the understanding of widespread and serious metabolic complications in humans. Increasing attention is also devoted to pathogens appropriating LDs for their own benefit. LD biology is still considered an emerging research area in rapid and vibrant development, attracting scientists from all disciplines of the life sciences and beyond, which is mirrored by the accompanying review collection. Here, we present our personal views on areas we believe are especially exciting and hold great potential for future developments. Particularly, we address issues relating to LD biogenesis and heterogeneity, required technological advances, and the complexity of human physiology.
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86
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Bohnert M. Tether Me, Tether Me Not—Dynamic Organelle Contact Sites in Metabolic Rewiring. Dev Cell 2020; 54:212-225. [DOI: 10.1016/j.devcel.2020.06.026] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 06/17/2020] [Accepted: 06/20/2020] [Indexed: 02/04/2023]
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87
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Zung N, Schuldiner M. New horizons in mitochondrial contact site research. Biol Chem 2020; 401:793-809. [PMID: 32324151 DOI: 10.1515/hsz-2020-0133] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 04/14/2020] [Indexed: 12/18/2022]
Abstract
Contact sites, areas where two organelles are held in close proximity through the action of molecular tethers, enable non-vesicular communication between compartments. Mitochondria have been center stage in the contact site field since the discovery of the first contact between mitochondria and the endoplasmic reticulum (ER) over 60 years ago. However, only now, in the last decade, has there been a burst of discoveries regarding contact site biology in general and mitochondrial contacts specifically. The number and types of characterized contacts increased dramatically, new molecular mechanisms enabling contact formation were discovered, additional unexpected functions for contacts were shown, and their roles in cellular and organismal physiology were emphasized. Here, we focus on mitochondria as we highlight the most recent developments, future goals and unresolved questions in the field.
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Affiliation(s)
- Naama Zung
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 7610001, Israel
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88
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Santinho A, Salo VT, Chorlay A, Li S, Zhou X, Omrane M, Ikonen E, Thiam AR. Membrane Curvature Catalyzes Lipid Droplet Assembly. Curr Biol 2020; 30:2481-2494.e6. [PMID: 32442467 DOI: 10.1016/j.cub.2020.04.066] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 03/24/2020] [Accepted: 04/23/2020] [Indexed: 12/20/2022]
Abstract
Lipid droplet (LD) biogenesis begins in the endoplasmic reticulum (ER) bilayer, but how the ER topology impacts this process is unclear. An early step in LD formation is nucleation, wherein free neutral lipids, mainly triacylglycerols (TGs) and sterol esters (SEs), condense into a nascent LD. How this transition occurs is poorly known. Here, we found that LDs preferably assemble at ER tubules, with higher curvature than ER sheets, independently of the LD assembly protein seipin. Indeed, the critical TG concentration required for initiating LD assembly is lower at curved versus flat membrane regions. In agreement with this finding, flat ER regions bear higher amounts of free TGs than tubular ones and present less LDs. By using an in vitro approach, we discovered that the presence of free TGs in tubules is energetically unfavorable, leading to outflow of TGs to flat membrane regions or condensation into LDs. Accordingly, in vitro LD nucleation can be achieved by the sole increase of membrane curvature. In contrast to TGs, the presence of free SEs is favored at tubules and increasing SE levels is inhibitory to the curvature-induced nucleation of TG LDs. Finally, we found that seipin is enriched at ER tubules and controls the condensation process, preventing excessive tubule-induced nucleation. The absence of seipin provokes erratic LD nucleation events determined by the abundance of ER tubules. In summary, our data indicate that membrane curvature catalyzes LD assembly.
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Affiliation(s)
- Alexandre Santinho
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 75005 Paris, France
| | - Veijo T Salo
- Department of Anatomy and Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland; Minerva Foundation Institute for Medical Research, 00290 Helsinki, Finland
| | - Aymeric Chorlay
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 75005 Paris, France
| | - Shiqian Li
- Department of Anatomy and Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland; Minerva Foundation Institute for Medical Research, 00290 Helsinki, Finland
| | - Xin Zhou
- Department of Anatomy and Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland; Minerva Foundation Institute for Medical Research, 00290 Helsinki, Finland
| | - Mohyeddine Omrane
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 75005 Paris, France
| | - Elina Ikonen
- Department of Anatomy and Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland; Minerva Foundation Institute for Medical Research, 00290 Helsinki, Finland
| | - Abdou Rachid Thiam
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 75005 Paris, France.
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89
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Hepatic lipid droplet homeostasis and fatty liver disease. Semin Cell Dev Biol 2020; 108:72-81. [PMID: 32444289 DOI: 10.1016/j.semcdb.2020.04.011] [Citation(s) in RCA: 76] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 03/17/2020] [Accepted: 04/17/2020] [Indexed: 12/14/2022]
Abstract
In cells, lipids are stored in lipid droplets, dynamic organelles that adapt their size, abundance, lipid and protein composition and organelle interactions to metabolic changes. Lipid droplet accumulation in the liver is the hallmark of non-alcoholic fatty liver disease (NAFLD). Due to the prevalence of obesity, the strongest risk factor for steatosis, NAFLD and its associated complications are currently affecting more than 1 billion people worldwide. Here, we review how triglyceride and phospholipid homeostasis are regulated in hepatocytes and how imbalances between lipid storage, degradation and lipoprotein secretion lead to NAFLD. We discuss how organelle interactions are altered in NAFLD and provide insights how NAFLD progression is associated with changes in hepatocellular signaling and organ-crosstalk. Finally, we highlight unsolved questions in hepatic LD and lipoprotein biology and give an outlook on therapeutic options counteracting hepatic lipid accumulation.
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90
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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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91
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Huang X, Jiang C, Yu L, Yang A. Current and Emerging Approaches for Studying Inter-Organelle Membrane Contact Sites. Front Cell Dev Biol 2020; 8:195. [PMID: 32292782 PMCID: PMC7118198 DOI: 10.3389/fcell.2020.00195] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 03/09/2020] [Indexed: 12/24/2022] Open
Abstract
Inter-organelle membrane contact sites (MCSs) are classically defined as areas of close proximity between heterologous membranes and established by specific proteins (termed tethers). The interest on MCSs has rapidly increased in the last years, since MCSs play a crucial role in the transfer of cellular components between different organelles and have been involved in important cellular functions such as apoptosis, organelle division and biogenesis, and cell growth. Recently, an unprecedented depth and breadth in insights into the details of MCSs have been uncovered. On one hand, extensive MCSs (organelles interactome) are revealed by comprehensive analysis of organelle network with high temporal-spatial resolution at the system level. On the other hand, more and more tethers involving in MCSs are identified and further works are focusing on addressing the role of these tethers in regulating the function of MCSs at the molecular level. These enormous progresses largely depend on the powerful approaches, including several different types of microscopies and various biochemical techniques. These approaches have greatly accelerated recent advances in MCSs at the system and molecular level. In this review, we summarize the current and emerging approaches for studying MCSs, such as various microscopies, proximity-driven fluorescent signal generation and proximity-dependent biotinylation. In addition, we highlight the advantages and disadvantages of the techniques to provide a general guidance for the study of MCSs.
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Affiliation(s)
- Xue Huang
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Chen Jiang
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Lihua Yu
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Aimin Yang
- School of Life Sciences, Chongqing University, Chongqing, China
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92
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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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93
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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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94
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Öztürk Z, O’Kane CJ, Pérez-Moreno JJ. Axonal Endoplasmic Reticulum Dynamics and Its Roles in Neurodegeneration. Front Neurosci 2020; 14:48. [PMID: 32116502 PMCID: PMC7025499 DOI: 10.3389/fnins.2020.00048] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 01/13/2020] [Indexed: 12/13/2022] Open
Abstract
The physical continuity of axons over long cellular distances poses challenges for their maintenance. One organelle that faces this challenge is endoplasmic reticulum (ER); unlike other intracellular organelles, this forms a physically continuous network throughout the cell, with a single membrane and a single lumen. In axons, ER is mainly smooth, forming a tubular network with occasional sheets or cisternae and low amounts of rough ER. It has many potential roles: lipid biosynthesis, glucose homeostasis, a Ca2+ store, protein export, and contacting and regulating other organelles. This tubular network structure is determined by ER-shaping proteins, mutations in some of which are causative for neurodegenerative disorders such as hereditary spastic paraplegia (HSP). While axonal ER shares many features with the tubular ER network in other contexts, these features must be adapted to the long and narrow dimensions of axons. ER appears to be physically continuous throughout axons, over distances that are enormous on a subcellular scale. It is therefore a potential channel for long-distance or regional communication within neurons, independent of action potentials or physical transport of cargos, but involving its physiological roles such as Ca2+ or organelle homeostasis. Despite its apparent stability, axonal ER is highly dynamic, showing features like anterograde and retrograde transport, potentially reflecting continuous fusion and breakage of the network. Here we discuss the transport processes that must contribute to this dynamic behavior of ER. We also discuss the model that these processes underpin a homeostatic process that ensures both enough ER to maintain continuity of the network and repair breaks in it, but not too much ER that might disrupt local cellular physiology. Finally, we discuss how failure of ER organization in axons could lead to axon degenerative diseases, and how a requirement for ER continuity could make distal axons most susceptible to degeneration in conditions that disrupt ER continuity.
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Affiliation(s)
| | - Cahir J. O’Kane
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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95
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Spatiotemporal contact between peroxisomes and lipid droplets regulates fasting-induced lipolysis via PEX5. Nat Commun 2020; 11:578. [PMID: 31996685 PMCID: PMC6989686 DOI: 10.1038/s41467-019-14176-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 12/17/2019] [Indexed: 01/05/2023] Open
Abstract
Lipid droplets (LDs) are key subcellular organelles for regulating lipid metabolism. Although several subcellular organelles participate in lipid metabolism, it remains elusive whether physical contacts between subcellular organelles and LDs might be involved in lipolysis upon nutritional deprivation. Here, we demonstrate that peroxisomes and peroxisomal protein PEX5 mediate fasting-induced lipolysis by stimulating adipose triglyceride lipase (ATGL) translocation onto LDs. During fasting, physical contacts between peroxisomes and LDs are increased by KIFC3-dependent movement of peroxisomes toward LDs, which facilitates spatial translocations of ATGL onto LDs. In addition, PEX5 could escort ATGL to contact points between peroxisomes and LDs in the presence of fasting cues. Moreover, in adipocyte-specific PEX5-knockout mice, the recruitment of ATGL onto LDs was defective and fasting-induced lipolysis is attenuated. Collectively, these data suggest that physical contacts between peroxisomes and LDs are required for spatiotemporal translocation of ATGL, which is escorted by PEX5 upon fasting, to maintain energy homeostasis. Lipid droplets are organelles that regulate lipid metabolism but if organellar contacts play a role during lipolysis is unclear. Here, the authors show that peroxisomes and peroxisomal protein PEX5 play pivotal roles in the spatial and temporal regulation of fasting-induced lipolysis by translocating ATGL onto lipid droplets
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96
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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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97
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Schrader M, Kamoshita M, Islinger M. Organelle interplay-peroxisome interactions in health and disease. J Inherit Metab Dis 2020; 43:71-89. [PMID: 30864148 PMCID: PMC7041636 DOI: 10.1002/jimd.12083] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 02/28/2019] [Accepted: 03/06/2019] [Indexed: 01/04/2023]
Abstract
Peroxisomes are multifunctional, dynamic, membrane-bound organelles with important functions in cellular lipid metabolism, rendering them essential for human health and development. Important roles for peroxisomes in signaling and the fine-tuning of cellular processes are emerging, which integrate them in a complex network of interacting cellular compartments. Like many other organelles, peroxisomes communicate through membrane contact sites. For example, peroxisomal growth, positioning, and lipid metabolism involves contacts with the endoplasmic reticulum (ER). Here, we discuss the most recent findings on peroxisome-organelle interactions including peroxisome-ER interplay at membrane contacts sites, and functional interplay with mitochondria, lysosomes, and lipid droplets in mammalian cells. We address tether proteins, metabolic cooperation, and the impact of peroxisome interactions on human health and disease.
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Affiliation(s)
- Michael Schrader
- College of Life and Environmental Sciences, BiosciencesUniversity of ExeterExeterUK
| | - Maki Kamoshita
- College of Life and Environmental Sciences, BiosciencesUniversity of ExeterExeterUK
| | - Markus Islinger
- Institute of Neuroanatomy, Center for Biomedicine and Medical Technology Mannheim, Medical Faculty ManheimUniversity of HeidelbergMannheimGermany
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98
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Kiegerl B, Tavassoli M, Smart H, Shabits BN, Zaremberg V, Athenstaedt K. Phosphorylation of the lipid droplet localized glycerol‑3‑phosphate acyltransferase Gpt2 prevents a futile triacylglycerol cycle in yeast. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1864:158509. [DOI: 10.1016/j.bbalip.2019.08.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 08/09/2019] [Accepted: 08/12/2019] [Indexed: 11/30/2022]
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99
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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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100
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Staying in Healthy Contact: How Peroxisomes Interact with Other Cell Organelles. Trends Mol Med 2019; 26:201-214. [PMID: 31727543 DOI: 10.1016/j.molmed.2019.09.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 08/24/2019] [Accepted: 09/24/2019] [Indexed: 11/24/2022]
Abstract
Peroxisomes share extensive metabolic connections with other cell organelles. Membrane contact sites (MCSs) establish and maintain such interactions, and they are vital for organelle positioning and motility. In the past few years peroxisome interactions and MCSs with other cellular organelles have been explored extensively, resulting in the identification of new MCSs, the tethering molecules involved, and their functional characterization. Defective tethering and compartmental communication can lead to pathological conditions that can be termed 'organelle interaction diseases'. We review peroxisome-organelle interactions in mammals and summarize the most recent knowledge of mammalian peroxisomal organelle contacts in health and disease.
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