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Fu L, Zhang J, Wang Y, Wu H, Xu X, Li C, Li J, Liu J, Wang H, Jiang X, Li Z, He Y, Liu P, Wu Y, Zou X, Liang B. LET-767 determines lipid droplet protein targeting and lipid homeostasis. J Cell Biol 2024; 223:e202311024. [PMID: 38551495 PMCID: PMC10982117 DOI: 10.1083/jcb.202311024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 02/22/2024] [Accepted: 03/12/2024] [Indexed: 04/02/2024] Open
Abstract
Lipid droplets (LDs) are composed of a core of neutral lipids wrapped by a phospholipid (PL) monolayer containing several hundred proteins that vary between different cells or organisms. How LD proteins target to LDs is still largely unknown. Here, we show that RNAi knockdown or gene mutation of let-767, encoding a member of hydroxysteroid dehydrogenase (HSD), displaced the LD localization of three well-known LD proteins: DHS-3 (dehydrogenase/reductase), PLIN-1 (perilipin), and DGAT-2 (diacylglycerol O-acyltransferase 2), and also prevented LD growth in Caenorhabditis elegans. LET-767 interacts with ARF-1 (ADP-ribosylation factor 1) to prevent ARF-1 LD translocation for appropriate LD protein targeting and lipid homeostasis. Deficiency of LET-767 leads to the release of ARF-1, which further recruits and promotes translocation of ATGL-1 (adipose triglyceride lipase) to LDs for lipolysis. The displacement of LD proteins caused by LET-767 deficiency could be reversed by inhibition of either ARF-1 or ATGL-1. Our work uncovers a unique LET-767 for determining LD protein targeting and maintaining lipid homeostasis.
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Affiliation(s)
- Lin Fu
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, School of Life Sciences, Yunnan University, Kunming, China
| | - Jingjing Zhang
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, School of Life Sciences, Yunnan University, Kunming, China
| | - Yanli Wang
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, School of Life Sciences, Yunnan University, Kunming, China
| | - Huiyin Wu
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, School of Life Sciences, Yunnan University, Kunming, China
| | - Xiumei Xu
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, School of Life Sciences, Yunnan University, Kunming, China
| | - Chunxia Li
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, School of Life Sciences, Yunnan University, Kunming, China
| | - Jirong Li
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, School of Life Sciences, Yunnan University, Kunming, China
| | - Jing Liu
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, School of Life Sciences, Yunnan University, Kunming, China
| | - Haizhen Wang
- College of Veterinary Medicine, Yunnan Agricultural University, Kunming, China
| | - Xue Jiang
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and Yunnan province, Kunming Institute of Zoology, Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming, China
| | - Zhihao Li
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, School of Life Sciences, Yunnan University, Kunming, China
| | - Yaomei He
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, School of Life Sciences, Yunnan University, Kunming, China
| | - Pingsheng Liu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Yingjie Wu
- School of Laboratory Animal and Shandong Laboratory Animal Center, Science and Technology Innovation Center, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
- Institute for Genome Engineered Animal Models of Human Diseases, National Center of Genetically Engineered Animal Models for International Research, Liaoning Provence Key Lab of Genome Engineered Animal Models Dalian Medical University, Dalian, China
| | - Xiaoju Zou
- College of Chinese Materia Medica and Yunnan Key Laboratory of Southern Medicinal Utilization, Yunnan University of Chinese Medicine, Kunming, China
| | - Bin Liang
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, School of Life Sciences, Yunnan University, Kunming, China
- Southwest United Graduate School, Kunming, China
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2
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Malis Y, Armoza-Eilat S, Nevo-Yassaf I, Dukhovny A, Sklan EH, Hirschberg K. Rab1b facilitates lipid droplet growth by ER-to-lipid droplet targeting of DGAT2. SCIENCE ADVANCES 2024; 10:eade7753. [PMID: 38809969 PMCID: PMC11135398 DOI: 10.1126/sciadv.ade7753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Accepted: 04/16/2024] [Indexed: 05/31/2024]
Abstract
Lipid droplets (LDs) comprise a triglyceride core surrounded by a lipid monolayer enriched with proteins, many of which function in LD homeostasis. How proteins are targeted to the growing LD is still unclear. Rab1b, a GTPase regulating secretory transport, was recently associated with targeting proteins to LDs in a Drosophila RNAi screen. LD formation was prevented in human hepatoma cells overexpressing dominant-negative Rab1b. We thus hypothesized that Rab1b recruits lipid-synthesizing enzymes, facilitating LD growth. Here, FRET between diacylglycerol acyltransferase 2 (DGAT2) and Rab1b and activity mutants of the latter demonstrated that Rab1b promotes DGAT2 ER to the LD surface redistribution. Last, alterations in LD metabolism and DGAT2 redistribution, consistent with Rab1b activity, were caused by mutations in the Rab1b-GTPase activating protein TBC1D20 in Warburg Micro syndrome (WARBM) model mice fibroblasts. These data contribute to our understanding of the mechanism of Rab1b in LD homeostasis and WARBM, a devastating autosomal-recessive disorder caused by mutations in TBC1D20.
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Affiliation(s)
- Yehonathan Malis
- Department of Pathology, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Shir Armoza-Eilat
- Department of Clinical Microbiology and Immunology, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Inbar Nevo-Yassaf
- Department of Pathology, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Anna Dukhovny
- Department of Clinical Microbiology and Immunology, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ella H. Sklan
- Department of Clinical Microbiology and Immunology, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Koret Hirschberg
- Department of Pathology, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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3
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Evergren E, Mills IG, Kennedy G. Adaptations of membrane trafficking in cancer and tumorigenesis. J Cell Sci 2024; 137:jcs260943. [PMID: 38770683 DOI: 10.1242/jcs.260943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024] Open
Abstract
Membrane trafficking, a fundamental cellular process encompassing the transport of molecules to specific organelles, endocytosis at the plasma membrane and protein secretion, is crucial for cellular homeostasis and signalling. Cancer cells adapt membrane trafficking to enhance their survival and metabolism, and understanding these adaptations is vital for improving patient responses to therapy and identifying therapeutic targets. In this Review, we provide a concise overview of major membrane trafficking pathways and detail adaptations in these pathways, including COPII-dependent endoplasmic reticulum (ER)-to-Golgi vesicle trafficking, COPI-dependent retrograde Golgi-to-ER trafficking and endocytosis, that have been found in cancer. We explore how these adaptations confer growth advantages or resistance to cell death and conclude by discussing the potential for utilising this knowledge in developing new treatment strategies and overcoming drug resistance for cancer patients.
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Affiliation(s)
- Emma Evergren
- Patrick G. Johnston Centre for Cancer Research, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Ian G Mills
- Patrick G. Johnston Centre for Cancer Research, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford OX3 9DU, UK
| | - Grace Kennedy
- Patrick G. Johnston Centre for Cancer Research, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK
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4
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Dudka W, Salo VT, Mahamid J. Zooming into lipid droplet biology through the lens of electron microscopy. FEBS Lett 2024; 598:1127-1142. [PMID: 38726814 DOI: 10.1002/1873-3468.14899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 04/08/2024] [Accepted: 04/24/2024] [Indexed: 05/25/2024]
Abstract
Electron microscopy (EM), in its various flavors, has significantly contributed to our understanding of lipid droplets (LD) as central organelles in cellular metabolism. For example, EM has illuminated that LDs, in contrast to all other cellular organelles, are uniquely enclosed by a single phospholipid monolayer, revealed the architecture of LD contact sites with different organelles, and provided near-atomic resolution maps of key enzymes that regulate neutral lipid biosynthesis and LD biogenesis. In this review, we first provide a brief history of pivotal findings in LD biology unveiled through the lens of an electron microscope. We describe the main EM techniques used in the context of LD research and discuss their current capabilities and limitations, thereby providing a foundation for utilizing suitable EM methodology to address LD-related questions with sufficient level of structural preservation, detail, and resolution. Finally, we highlight examples where EM has recently been and is expected to be instrumental in expanding the frontiers of LD biology.
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Affiliation(s)
- Wioleta Dudka
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Veijo T Salo
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Julia Mahamid
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
- Cell Biology and Biophysics Unit, EMBL, Heidelberg, Germany
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5
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Griseti E, Bello AA, Bieth E, Sabbagh B, Iacovoni JS, Bigay J, Laurell H, Čopič A. Molecular mechanisms of perilipin protein function in lipid droplet metabolism. FEBS Lett 2024; 598:1170-1198. [PMID: 38140813 DOI: 10.1002/1873-3468.14792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2023] [Revised: 11/27/2023] [Accepted: 12/11/2023] [Indexed: 12/24/2023]
Abstract
Perilipins are abundant lipid droplet (LD) proteins present in all metazoans and also in Amoebozoa and fungi. Humans express five perilipins, which share a similar domain organization: an amino-terminal PAT domain and an 11-mer repeat region, which can fold into amphipathic helices that interact with LDs, followed by a structured carboxy-terminal domain. Variations of this organization that arose during vertebrate evolution allow for functional specialization between perilipins in relation to the metabolic needs of different tissues. We discuss how different features of perilipins influence their interaction with LDs and their cellular targeting. PLIN1 and PLIN5 play a direct role in lipolysis by regulating the recruitment of lipases to LDs and LD interaction with mitochondria. Other perilipins, particularly PLIN2, appear to protect LDs from lipolysis, but the molecular mechanism is not clear. PLIN4 stands out with its long repetitive region, whereas PLIN3 is most widely expressed and is used as a nascent LD marker. Finally, we discuss the genetic variability in perilipins in connection with metabolic disease, prominent for PLIN1 and PLIN4, underlying the importance of understanding the molecular function of perilipins.
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Affiliation(s)
- Elena Griseti
- Institut des Maladies Métaboliques et Cardiovasculaires - I2MC, Université de Toulouse, Inserm, Université Toulouse III - Paul Sabatier (UPS), France
| | - Abdoul Akim Bello
- Institut de Pharmacologie Moléculaire et Cellulaire - IPMC, Université Côte d'Azur, CNRS, Valbonne, France
| | - Eric Bieth
- Institut des Maladies Métaboliques et Cardiovasculaires - I2MC, Université de Toulouse, Inserm, Université Toulouse III - Paul Sabatier (UPS), France
- Departement de Génétique Médicale, Centre Hospitalier Universitaire de Toulouse, France
| | - Bayane Sabbagh
- Centre de Recherche en Biologie Cellulaire de Montpellier - CRBM, Université de Montpellier, CNRS, France
| | - Jason S Iacovoni
- Institut des Maladies Métaboliques et Cardiovasculaires - I2MC, Université de Toulouse, Inserm, Université Toulouse III - Paul Sabatier (UPS), France
| | - Joëlle Bigay
- Institut de Pharmacologie Moléculaire et Cellulaire - IPMC, Université Côte d'Azur, CNRS, Valbonne, France
| | - Henrik Laurell
- Institut des Maladies Métaboliques et Cardiovasculaires - I2MC, Université de Toulouse, Inserm, Université Toulouse III - Paul Sabatier (UPS), France
| | - Alenka Čopič
- Centre de Recherche en Biologie Cellulaire de Montpellier - CRBM, Université de Montpellier, CNRS, France
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6
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Ding L, Huwyler F, Long F, Yang W, Binz J, Wernlé K, Pfister M, Klug M, Balaz M, Ukropcova B, Ukropec J, Wu C, Wang T, Gao M, Clavien PA, Dutkowski P, Tibbitt MW, Wolfrum C. Glucose controls lipolysis through Golgi PtdIns4P-mediated regulation of ATGL. Nat Cell Biol 2024; 26:552-566. [PMID: 38561547 PMCID: PMC11021197 DOI: 10.1038/s41556-024-01386-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 02/23/2024] [Indexed: 04/04/2024]
Abstract
Metabolic crosstalk of the major nutrients glucose, amino acids and fatty acids (FAs) ensures systemic metabolic homeostasis. The coordination between the supply of glucose and FAs to meet various physiological demands is especially important as improper nutrient levels lead to metabolic disorders, such as diabetes and metabolic dysfunction-associated steatohepatitis (MASH). In response to the oscillations in blood glucose levels, lipolysis is thought to be mainly regulated hormonally to control FA liberation from lipid droplets by insulin, catecholamine and glucagon. However, whether general cell-intrinsic mechanisms exist to directly modulate lipolysis via glucose sensing remains largely unknown. Here we report the identification of such an intrinsic mechanism, which involves Golgi PtdIns4P-mediated regulation of adipose triglyceride lipase (ATGL)-driven lipolysis via intracellular glucose sensing. Mechanistically, depletion of intracellular glucose results in lower Golgi PtdIns4P levels, and thus reduced assembly of the E3 ligase complex CUL7FBXW8 in the Golgi apparatus. Decreased levels of the E3 ligase complex lead to reduced polyubiquitylation of ATGL in the Golgi and enhancement of ATGL-driven lipolysis. This cell-intrinsic mechanism regulates both the pool of intracellular FAs and their extracellular release to meet physiological demands during fasting and glucose deprivation. Moreover, genetic and pharmacological manipulation of the Golgi PtdIns4P-CUL7FBXW8-ATGL axis in mouse models of simple hepatic steatosis and MASH, as well as during ex vivo perfusion of a human steatotic liver graft leads to the amelioration of steatosis, suggesting that this pathway might be a promising target for metabolic dysfunction-associated steatotic liver disease and possibly MASH.
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Affiliation(s)
- Lianggong Ding
- Institute of Food, Nutrition and Health, ETH Zürich, Schwerzenbach, Switzerland
| | - Florian Huwyler
- Macromolecular Engineering Laboratory, Institute of Energy and Process Engineering, ETH Zürich, Zurich, Switzerland
| | - Fen Long
- Institute of Food, Nutrition and Health, ETH Zürich, Schwerzenbach, Switzerland
| | - Wu Yang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Jonas Binz
- Macromolecular Engineering Laboratory, Institute of Energy and Process Engineering, ETH Zürich, Zurich, Switzerland
| | - Kendra Wernlé
- Department of Surgery and Transplantation, University of Zurich, Zurich, Switzerland
- Wyss Zurich Translational Center, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Matthias Pfister
- Department of Surgery and Transplantation, University of Zurich, Zurich, Switzerland
- Wyss Zurich Translational Center, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Manuel Klug
- Institute of Food, Nutrition and Health, ETH Zürich, Schwerzenbach, Switzerland
| | - Miroslav Balaz
- Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Barbara Ukropcova
- Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Jozef Ukropec
- Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Chunyan Wu
- Institute of Food, Nutrition and Health, ETH Zürich, Schwerzenbach, Switzerland
| | - Tongtong Wang
- Institute of Food, Nutrition and Health, ETH Zürich, Schwerzenbach, Switzerland
| | - Min Gao
- Institute of Food, Nutrition and Health, ETH Zürich, Schwerzenbach, Switzerland
- Department of Pharmacy, the Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Pierre-Alain Clavien
- Department of Surgery and Transplantation, University of Zurich, Zurich, Switzerland
- Wyss Zurich Translational Center, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Philipp Dutkowski
- Department of Surgery and Transplantation, University of Zurich, Zurich, Switzerland
| | - Mark W Tibbitt
- Macromolecular Engineering Laboratory, Institute of Energy and Process Engineering, ETH Zürich, Zurich, Switzerland
- Wyss Zurich Translational Center, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Christian Wolfrum
- Institute of Food, Nutrition and Health, ETH Zürich, Schwerzenbach, Switzerland.
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7
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Mathiowetz AJ, Olzmann JA. Lipid droplets and cellular lipid flux. Nat Cell Biol 2024; 26:331-345. [PMID: 38454048 DOI: 10.1038/s41556-024-01364-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Accepted: 01/24/2024] [Indexed: 03/09/2024]
Abstract
Lipid droplets are dynamic organelles that store neutral lipids, serve the metabolic needs of cells, and sequester lipids to prevent lipotoxicity and membrane damage. Here we review the current understanding of the mechanisms of lipid droplet biogenesis and turnover, the transfer of lipids and metabolites at membrane contact sites, and the role of lipid droplets in regulating fatty acid flux in lipotoxicity and cell death.
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Affiliation(s)
- Alyssa J Mathiowetz
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA, USA
| | - James A Olzmann
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA.
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA, USA.
- Chan Zuckerberg Biohub - San Francisco, San Francisco, CA, USA.
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8
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Wit M, Belykh A, Sumara G. Protein kinase D (PKD) on the crossroad of lipid absorption, synthesis and utilization. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119653. [PMID: 38104800 DOI: 10.1016/j.bbamcr.2023.119653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Revised: 10/19/2023] [Accepted: 11/30/2023] [Indexed: 12/19/2023]
Abstract
Inappropriate lipid levels in the blood, as well as its content and composition in different organs, underlie multiple metabolic disorders including obesity, non-alcoholic fatty liver disease, type 2 diabetes, and atherosclerosis. Multiple processes contribute to the complex metabolism of triglycerides (TGs), fatty acids (FAs), and other lipid species. These consist of digestion and absorption of dietary lipids, de novo FAs synthesis (lipogenesis), uptake of TGs and FAs by peripheral tissues, TGs storage in the intracellular depots as well as lipid utilization for β-oxidation and their conversion to lipid-derivatives. A majority of the enzymatic reactions linked to lipogenesis, TGs synthesis, lipid absorption, and transport are happening at the endoplasmic reticulum, while β-oxidation takes place in mitochondria and peroxisomes. The Golgi apparatus is a central sorting, protein- and lipid-modifying organelle and hence is involved in lipid metabolism as well. However, the impact of the processes taking part in the Golgi apparatus are often overseen. The protein kinase D (PKD) family (composed of three members, PKD1, 2, and 3) is the master regulator of Golgi dynamics. PKDs are also a sensor of different lipid species in distinct cellular compartments. In this review, we discuss the roles of PKD family members in the regulation of lipid metabolism including the processes executed by PKDs at the Golgi apparatus. We also discuss the role of PKDs-dependent signaling in different cellular compartments and organs in the context of the development of metabolic disorders.
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Affiliation(s)
- Magdalena Wit
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warszawa, Poland
| | - Andrei Belykh
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warszawa, Poland
| | - Grzegorz Sumara
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warszawa, Poland.
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9
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Maestri A, Garagnani P, Pedrelli M, Hagberg CE, Parini P, Ehrenborg E. Lipid droplets, autophagy, and ageing: A cell-specific tale. Ageing Res Rev 2024; 94:102194. [PMID: 38218464 DOI: 10.1016/j.arr.2024.102194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Revised: 12/22/2023] [Accepted: 01/08/2024] [Indexed: 01/15/2024]
Abstract
Lipid droplets are the essential organelle for storing lipids in a cell. Within the variety of the human body, different cells store, utilize and release lipids in different ways, depending on their intrinsic function. However, these differences are not well characterized and, especially in the context of ageing, represent a key factor for cardiometabolic diseases. Whole body lipid homeostasis is a central interest in the field of cardiometabolic diseases. In this review we characterize lipid droplets and their utilization via autophagy and describe their diverse fate in three cells types central in cardiometabolic dysfunctions: adipocytes, hepatocytes, and macrophages.
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Affiliation(s)
- Alice Maestri
- Division of Cardiovascular Medicine, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden; Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Paolo Garagnani
- Department of Medical and Surgical Sciences (DIMEC), University of Bologna, Bologna, Italy; IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
| | - Matteo Pedrelli
- Cardio Metabolic Unit, Department of Laboratory Medicine, and Department of Medicine (Huddinge), Karolinska Institutet, Stockholm, Sweden; Medicine Unit of Endocrinology, Theme Inflammation and Ageing, Karolinska University Hospital, Stockholm, Sweden
| | - Carolina E Hagberg
- Division of Cardiovascular Medicine, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden; Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Paolo Parini
- Cardio Metabolic Unit, Department of Laboratory Medicine, and Department of Medicine (Huddinge), Karolinska Institutet, Stockholm, Sweden; Medicine Unit of Endocrinology, Theme Inflammation and Ageing, Karolinska University Hospital, Stockholm, Sweden
| | - Ewa Ehrenborg
- Division of Cardiovascular Medicine, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden; Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.
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10
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López-Alcalá J, Gordon A, Trávez A, Tercero-Alcázar C, Correa-Sáez A, González-Rellán MJ, Rangel-Zúñiga OA, Rodríguez A, Membrives A, Frühbeck G, Nogueiras R, Calzado MA, Guzmán-Ruiz R, Malagón MM. Localization, traffic and function of Rab34 in adipocyte lipid and endocrine functions. J Biomed Sci 2024; 31:2. [PMID: 38183057 PMCID: PMC10770960 DOI: 10.1186/s12929-023-00990-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 12/20/2023] [Indexed: 01/07/2024] Open
Abstract
BACKGROUND Excessive lipid accumulation in the adipose tissue in obesity alters the endocrine and energy storage functions of adipocytes. Adipocyte lipid droplets represent key organelles coordinating lipid storage and mobilization in these cells. Recently, we identified the small GTPase, Rab34, in the lipid droplet proteome of adipocytes. Herein, we have characterized the distribution, intracellular transport, and potential contribution of this GTPase to adipocyte physiology and its regulation in obesity. METHODS 3T3-L1 and human primary preadipocytes were differentiated in vitro and Rab34 distribution and trafficking were analyzed using markers of cellular compartments. 3T3-L1 adipocytes were transfected with expression vectors and/or Rab34 siRNA and assessed for secretory activity, lipid accumulation and expression of proteins regulating lipid metabolism. Proteomic and protein interaction analyses were employed for the identification of the Rab34 interactome. These studies were combined with functional analysis to unveil the role played by the GTPase in adipocytes, with a focus on the actions conveyed by Rab34 interacting proteins. Finally, Rab34 regulation in response to obesity was also evaluated. RESULTS Our results show that Rab34 localizes at the Golgi apparatus in preadipocytes. During lipid droplet biogenesis, Rab34 translocates from the Golgi to endoplasmic reticulum-related compartments and then reaches the surface of adipocyte lipid droplets. Rab34 exerts distinct functions related to its intracellular location. Thus, at the Golgi, Rab34 regulates cisternae integrity as well as adiponectin trafficking and oligomerization. At the lipid droplets, this GTPase controls lipid accumulation and lipolysis through its interaction with the E1-ubiquitin ligase, UBA1, which induces the ubiquitination and proteasomal degradation of the fatty acid transporter and member of Rab34 interactome, FABP5. Finally, Rab34 levels in the adipose tissue and adipocytes are regulated in response to obesity and related pathogenic insults (i.e., fibrosis). CONCLUSIONS Rab34 plays relevant roles during adipocyte differentiation, including from the regulation of the oligomerization (i.e., biological activity) and secretion of a major adipokine with insulin-sensitizing actions, adiponectin, to lipid storage and mobilization from lipid droplets. Rab34 dysregulation in obesity may contribute to the altered adipokine secretion and lipid metabolism that characterize adipocyte dysfunction in conditions of excess adiposity.
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Affiliation(s)
- Jaime López-Alcalá
- Department of Cell Biology, Physiology, and Immunology, Maimonides Institute for Biomedical Research of Córdoba (IMIBIC), University of Córdoba (UCO), Reina Sofía University Hospital (HURS), Córdoba, Spain
| | - Ana Gordon
- Department of Cell Biology, Physiology, and Immunology, Maimonides Institute for Biomedical Research of Córdoba (IMIBIC), University of Córdoba (UCO), Reina Sofía University Hospital (HURS), Córdoba, Spain.
| | - Andrés Trávez
- Department of Cell Biology, Physiology, and Immunology, Maimonides Institute for Biomedical Research of Córdoba (IMIBIC), University of Córdoba (UCO), Reina Sofía University Hospital (HURS), Córdoba, Spain
| | - Carmen Tercero-Alcázar
- Department of Cell Biology, Physiology, and Immunology, Maimonides Institute for Biomedical Research of Córdoba (IMIBIC), University of Córdoba (UCO), Reina Sofía University Hospital (HURS), Córdoba, Spain
| | - Alejandro Correa-Sáez
- Department of Cell Biology, Physiology, and Immunology, Maimonides Institute for Biomedical Research of Córdoba (IMIBIC), University of Córdoba (UCO), Reina Sofía University Hospital (HURS), Córdoba, Spain
| | - María Jesús González-Rellán
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), ISCIII, Madrid, Spain
- Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
| | - Oriol A Rangel-Zúñiga
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), ISCIII, Madrid, Spain
- Lipids and Atherosclerosis Unit, IMIBIC/University of Córdoba (UCO), Reina Sofía University Hospital (HURS), Córdoba, Spain
| | - Amaia Rodríguez
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), ISCIII, Madrid, Spain
- Metabolic Research Laboratory, Department of Endocrinology & Nutrition, Clinic, University of Navarra, IdiSNA, Pamplona, Spain
| | - Antonio Membrives
- Department of Medical-Surgical Specialties, University of Córdoba (UCO), Reina Sofia University Hospital (HURS), Córdoba, Spain
| | - Gema Frühbeck
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), ISCIII, Madrid, Spain
- Metabolic Research Laboratory, Department of Endocrinology & Nutrition, Clinic, University of Navarra, IdiSNA, Pamplona, Spain
| | - Rubén Nogueiras
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), ISCIII, Madrid, Spain
- Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
| | - Marco A Calzado
- Department of Cell Biology, Physiology, and Immunology, Maimonides Institute for Biomedical Research of Córdoba (IMIBIC), University of Córdoba (UCO), Reina Sofía University Hospital (HURS), Córdoba, Spain
| | - Rocío Guzmán-Ruiz
- Department of Cell Biology, Physiology, and Immunology, Maimonides Institute for Biomedical Research of Córdoba (IMIBIC), University of Córdoba (UCO), Reina Sofía University Hospital (HURS), Córdoba, Spain
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), ISCIII, Madrid, Spain
| | - María M Malagón
- Department of Cell Biology, Physiology, and Immunology, Maimonides Institute for Biomedical Research of Córdoba (IMIBIC), University of Córdoba (UCO), Reina Sofía University Hospital (HURS), Córdoba, Spain.
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), ISCIII, Madrid, Spain.
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11
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López-Alcalá J, Soler-Vázquez MC, Tercero-Alcázar C, Sánchez-Ceinos J, Guzmán-Ruiz R, Malagón MM, Gordon A. Rab18 Drift in Lipid Droplet and Endoplasmic Reticulum Interactions of Adipocytes under Obesogenic Conditions. Int J Mol Sci 2023; 24:17177. [PMID: 38139006 PMCID: PMC10743551 DOI: 10.3390/ijms242417177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 12/01/2023] [Accepted: 12/04/2023] [Indexed: 12/24/2023] Open
Abstract
The adipose tissue stores excess energy in the form of neutral lipids within adipocyte lipid droplets (LDs). The correct function of LDs requires the interaction with other organelles, such as the endoplasmic reticulum (ER) as well as with LD coat-associated proteins, including Rab18, a mediator of intracellular lipid trafficking and ER-LD interaction. Although perturbations of the inter-organelle contact sites have been linked to several diseases, such as cancer, no information regarding ER-LD contact sites in dysfunctional adipocytes from the obese adipose tissue has been published to date. Herein, the ER-LD connection and Rab18 distribution at ER-LD contact sites are examined in adipocytes challenged with fibrosis and inflammatory conditions, which represent known hallmarks of the adipose tissue in obesity. Our results show that adipocytes differentiated in fibrotic conditions caused ER fragmentation, the expansion of ER-LD contact sites, and modified Rab18 dynamics. Likewise, adipocytes exposed to inflammatory conditions favored ER-LD contact, Rab18 accumulation in the ER, and Rab18 redistribution to large LDs. Finally, our studies in human adipocytes supported the suggestion that Rab18 transitions to the LD coat from the ER. Taken together, our results suggest that obesity-related pathogenic processes alter the maintenance of ER-LD interactions and interfere with Rab18 trafficking through these contact sites.
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Affiliation(s)
- Jaime López-Alcalá
- Department of Cell Biology, Physiology, and Immunology, Adipobiology Group, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Córdoba, 14004 Córdoba, Spain; (J.L.-A.); (M.C.S.-V.); (C.T.-A.); (R.G.-R.)
| | - M. Carmen Soler-Vázquez
- Department of Cell Biology, Physiology, and Immunology, Adipobiology Group, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Córdoba, 14004 Córdoba, Spain; (J.L.-A.); (M.C.S.-V.); (C.T.-A.); (R.G.-R.)
- Department of Biochemistry and Physiology, School of Pharmacy and Food Sciences, Instituto de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, 08028 Barcelona, Spain
| | - Carmen Tercero-Alcázar
- Department of Cell Biology, Physiology, and Immunology, Adipobiology Group, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Córdoba, 14004 Córdoba, Spain; (J.L.-A.); (M.C.S.-V.); (C.T.-A.); (R.G.-R.)
| | - Julia Sánchez-Ceinos
- Cardiology Unit, Department of Medicine-Solna, Karolinska Institute (KI), Karolinska University Hospital (NKS), 17177 Stockholm, Sweden;
| | - Rocío Guzmán-Ruiz
- Department of Cell Biology, Physiology, and Immunology, Adipobiology Group, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Córdoba, 14004 Córdoba, Spain; (J.L.-A.); (M.C.S.-V.); (C.T.-A.); (R.G.-R.)
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - María M. Malagón
- Department of Cell Biology, Physiology, and Immunology, Adipobiology Group, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Córdoba, 14004 Córdoba, Spain; (J.L.-A.); (M.C.S.-V.); (C.T.-A.); (R.G.-R.)
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Ana Gordon
- Department of Cell Biology, Physiology, and Immunology, Adipobiology Group, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Córdoba, 14004 Córdoba, Spain; (J.L.-A.); (M.C.S.-V.); (C.T.-A.); (R.G.-R.)
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12
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Cho CH, Patel S, Rajbhandari P. Adipose tissue lipid metabolism: lipolysis. Curr Opin Genet Dev 2023; 83:102114. [PMID: 37738733 DOI: 10.1016/j.gde.2023.102114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 08/15/2023] [Accepted: 08/23/2023] [Indexed: 09/24/2023]
Abstract
White adipose tissue stores fatty acid (FA) as triglyceride in the lipid droplet organelle of highly specialized cells known as fat cells or adipocytes. Depending on the nutritional state and energy demand, hormonal and biochemical signals converge on activating an elegant and fundamental process known as lipolysis, which involves triglyceride hydrolysis to FAs. Almost six decades of work have vastly expanded our knowledge of lipolysis from enzymatic processes to complex protein assembly, disassembly, and post-translational modification. Research in recent decades ushered in the discovery of new lipolytic enzymes and coregulators and the characterization of numerous factors and signaling pathways that regulate lipid hydrolysis on transcriptional and post-transcriptional levels. This review will discuss recent developments with particular emphasis on the past two years in enzymatic lipolytic pathways and transcriptional regulation of lipolysis. We will summarize the positive and negative regulators of lipolysis, the adipose tissue microenvironment in lipolysis, and the systemic effects of lipolysis. The dynamic nature of adipocyte lipolysis is emerging as an essential regulator of metabolism and energy balance, and we will discuss recent developments in this area.
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Affiliation(s)
- Chung Hwan Cho
- Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Sanil Patel
- Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Prashant Rajbhandari
- Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Diabetes, Obesity, and Metabolism Institute, Department of Endocrinology and Bone Disease, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place New York, NY 10029 USA.
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13
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Qin Z, Wang T, Zhao Y, Ma C, Shao Q. Molecular Machinery of Lipid Droplet Degradation and Turnover in Plants. Int J Mol Sci 2023; 24:16039. [PMID: 38003229 PMCID: PMC10671748 DOI: 10.3390/ijms242216039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 10/23/2023] [Accepted: 10/29/2023] [Indexed: 11/26/2023] Open
Abstract
Lipid droplets (LDs) are important organelles conserved across eukaryotes with a fascinating biogenesis and consumption cycle. Recent intensive research has focused on uncovering the cellular biology of LDs, with emphasis on their degradation. Briefly, two major pathways for LD degradation have been recognized: (1) lipolysis, in which lipid degradation is catalyzed by lipases on the LD surface, and (2) lipophagy, in which LDs are degraded by autophagy. Both of these pathways require the collective actions of several lipolytic and proteolytic enzymes, some of which have been purified and analyzed for their in vitro activities. Furthermore, several genes encoding these proteins have been cloned and characterized. In seed plants, seed germination is initiated by the hydrolysis of stored lipids in LDs to provide energy and carbon equivalents for the germinating seedling. However, little is known about the mechanism regulating the LD mobilization. In this review, we focus on recent progress toward understanding how lipids are degraded and the specific pathways that coordinate LD mobilization in plants, aiming to provide an accurate and detailed outline of the process. This will set the stage for future studies of LD dynamics and help to utilize LDs to their full potential.
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Affiliation(s)
| | | | | | - Changle Ma
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Jinan 250358, China
| | - Qun Shao
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Jinan 250358, China
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14
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Viktorova EG, Gabaglio S, Moghimi S, Zimina A, Wynn BG, Sztul E, Belov GA. The development of resistance to an inhibitor of a cellular protein reveals a critical interaction between the enterovirus protein 2C and a small GTPase Arf1. PLoS Pathog 2023; 19:e1011673. [PMID: 37721955 PMCID: PMC10538752 DOI: 10.1371/journal.ppat.1011673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 09/28/2023] [Accepted: 09/08/2023] [Indexed: 09/20/2023] Open
Abstract
The cellular protein GBF1, an activator of Arf GTPases (ArfGEF: Arf guanine nucleotide exchange factor), is recruited to the replication organelles of enteroviruses through interaction with the viral protein 3A, and its ArfGEF activity is required for viral replication, however how GBF1-dependent Arf activation supports the infection remains enigmatic. Here, we investigated the development of resistance of poliovirus, a prototype enterovirus, to increasing concentrations of brefeldin A (BFA), an inhibitor of GBF1. High level of resistance required a gradual accumulation of multiple mutations in the viral protein 2C. The 2C mutations conferred BFA resistance even in the context of a 3A mutant previously shown to be defective in the recruitment of GBF1 to replication organelles, and in cells depleted of GBF1, suggesting a GBF1-independent replication mechanism. Still, activated Arfs accumulated on the replication organelles of this mutant even in the presence of BFA, its replication was inhibited by a pan-ArfGEF inhibitor LM11, and the BFA-resistant phenotype was compromised in Arf1-knockout cells. Importantly, the mutations strongly increased the interaction of 2C with the activated form of Arf1. Analysis of other enteroviruses revealed a particularly strong interaction of 2C of human rhinovirus 1A with activated Arf1. Accordingly, the replication of this virus was significantly less sensitive to BFA than that of poliovirus. Thus, our data demonstrate that enterovirus 2Cs may behave like Arf1 effector proteins and that GBF1 but not Arf activation can be dispensable for enterovirus replication. These findings have important implications for the development of host-targeted anti-viral therapeutics.
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Affiliation(s)
- Ekaterina G. Viktorova
- Department of Veterinary Medicine and Virginia-Maryland College of Veterinary Medicine, University of Maryland, College Park, Maryland, United States of America
| | - Samuel Gabaglio
- Department of Veterinary Medicine and Virginia-Maryland College of Veterinary Medicine, University of Maryland, College Park, Maryland, United States of America
| | - Seyedehmahsa Moghimi
- Department of Veterinary Medicine and Virginia-Maryland College of Veterinary Medicine, University of Maryland, College Park, Maryland, United States of America
| | - Anna Zimina
- Department of Veterinary Medicine and Virginia-Maryland College of Veterinary Medicine, University of Maryland, College Park, Maryland, United States of America
| | - Bridge G. Wynn
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham; Birmingham, Alabama, United States of America
| | - Elizabeth Sztul
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham; Birmingham, Alabama, United States of America
| | - George A. Belov
- Department of Veterinary Medicine and Virginia-Maryland College of Veterinary Medicine, University of Maryland, College Park, Maryland, United States of America
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15
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Enkler L, Szentgyörgyi V, Pennauer M, Prescianotto-Baschong C, Riezman I, Wiesyk A, Avraham RE, Spiess M, Zalckvar E, Kucharczyk R, Riezman H, Spang A. Arf1 coordinates fatty acid metabolism and mitochondrial homeostasis. Nat Cell Biol 2023; 25:1157-1172. [PMID: 37400497 PMCID: PMC10415182 DOI: 10.1038/s41556-023-01180-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 06/05/2023] [Indexed: 07/05/2023]
Abstract
Lipid mobilization through fatty acid β-oxidation is a central process essential for energy production during nutrient shortage. In yeast, this catabolic process starts in the peroxisome from where β-oxidation products enter mitochondria and fuel the tricarboxylic acid cycle. Little is known about the physical and metabolic cooperation between these organelles. Here we found that expression of fatty acid transporters and of the rate-limiting enzyme involved in β-oxidation is decreased in cells expressing a hyperactive mutant of the small GTPase Arf1, leading to an accumulation of fatty acids in lipid droplets. Consequently, mitochondria became fragmented and ATP synthesis decreased. Genetic and pharmacological depletion of fatty acids phenocopied the arf1 mutant mitochondrial phenotype. Although β-oxidation occurs in both mitochondria and peroxisomes in mammals, Arf1's role in fatty acid metabolism is conserved. Together, our results indicate that Arf1 integrates metabolism into energy production by regulating fatty acid storage and utilization, and presumably organelle contact sites.
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Affiliation(s)
| | | | | | | | - Isabelle Riezman
- Department of Biochemistry, NCCR Chemical Biology, University of Geneva, Geneva, Switzerland
| | - Aneta Wiesyk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Reut Ester Avraham
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | | | - Einat Zalckvar
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Roza Kucharczyk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Howard Riezman
- Department of Biochemistry, NCCR Chemical Biology, University of Geneva, Geneva, Switzerland
| | - Anne Spang
- Biozentrum, University of Basel, Basel, Switzerland.
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16
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Ho NI, Huis In 't Veld LGM, van Eck van der Sluijs J, Heuts BMH, Looman MWG, Kers-Rebel ED, van den Dries K, Dolstra H, Martens JHA, Hobo W, Adema GJ. Saponin-based adjuvants enhance antigen cross-presentation in human CD11c + CD1c + CD5 - CD163 + conventional type 2 dendritic cells. J Immunother Cancer 2023; 11:e007082. [PMID: 37612044 PMCID: PMC10450066 DOI: 10.1136/jitc-2023-007082] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/31/2023] [Indexed: 08/25/2023] Open
Abstract
BACKGROUND Adjuvants are key for effective vaccination against cancer and chronic infectious diseases. Saponin-based adjuvants (SBAs) are unique among adjuvants in their ability to induce robust cell-mediated immune responses in addition to antibody responses. Recent preclinical studies revealed that SBAs induced cross-presentation and lipid bodies in otherwise poorly cross-presenting CD11b+ murine dendritic cells (DCs). METHOD Here, we investigated the response of human DC subsets to SBAs with RNA sequencing and pathway analyses, lipid body induction visualized by laser scanning microscopy, antigen translocation to the cytosol, and antigen cross-presentation to CD8+ T cells. RESULTS RNA sequencing of SBA-treated conventional type 1 DC (cDC1) and type 2 DC (cDC2) subsets uncovered that SBAs upregulated lipid-related pathways in CD11c+ CD1c+ cDC2s, especially in the CD5- CD163+ CD14+ cDC2 subset. Moreover, SBAs induced lipid bodies and enhanced endosomal antigen translocation into the cytosol in this particular cDC2 subset. Finally, SBAs enhanced cross-presentation only in cDC2s, which requires the CD163+ CD14+ cDC2 subset. CONCLUSIONS These data thus identify the CD163+ CD14+ cDC2 subset as the main SBA-responsive DC subset in humans and imply new strategies to optimize the application of saponin-based adjuvants in a potent cancer vaccine.
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Affiliation(s)
- Nataschja I Ho
- Radiotherapy and OncoImmunology Laboratory, Department of Radiation Oncology, Radboud University Nijmegen Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands
| | - Lisa G M Huis In 't Veld
- Radiotherapy and OncoImmunology Laboratory, Department of Radiation Oncology, Radboud University Nijmegen Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands
| | - Jesper van Eck van der Sluijs
- Radiotherapy and OncoImmunology Laboratory, Department of Radiation Oncology, Radboud University Nijmegen Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands
- Department of Laboratory Medicine, Laboratory of Hematology, Radboud University Nijmegen Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands
| | - Branco M H Heuts
- Department of Molecular Biology, Faculty of Science, Radboud University Nijmegen Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands
| | - Maaike W G Looman
- Radiotherapy and OncoImmunology Laboratory, Department of Radiation Oncology, Radboud University Nijmegen Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands
| | - Esther D Kers-Rebel
- Radiotherapy and OncoImmunology Laboratory, Department of Radiation Oncology, Radboud University Nijmegen Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands
| | - Koen van den Dries
- Radboud Technology Center Microscopy, Radboud University Nijmegen Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands
| | - Harry Dolstra
- Department of Laboratory Medicine, Laboratory of Hematology, Radboud University Nijmegen Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands
| | - Joost H A Martens
- Department of Molecular Biology, Faculty of Science, Radboud University Nijmegen Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands
| | - Willemijn Hobo
- Department of Laboratory Medicine, Laboratory of Hematology, Radboud University Nijmegen Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands
| | - Gosse J Adema
- Radiotherapy and OncoImmunology Laboratory, Department of Radiation Oncology, Radboud University Nijmegen Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands
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17
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Farese RV, Walther TC. Glycerolipid Synthesis and Lipid Droplet Formation in the Endoplasmic Reticulum. Cold Spring Harb Perspect Biol 2023; 15:a041246. [PMID: 36096640 PMCID: PMC10153804 DOI: 10.1101/cshperspect.a041246] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
More than 60 years ago, Eugene Kennedy and coworkers elucidated the endoplasmic reticulum (ER)-based pathways of glycerolipid synthesis, including the synthesis of phospholipids and triacylglycerols (TGs). The reactions of the Kennedy pathway were identified by studying the conversion of lipid intermediates and the isolation of biochemical enzymatic activities, but the molecular basis for most of these reactions was unknown. With recent progress in the cell biology, biochemistry, and structural biology in this area, we have a much more mechanistic understanding of this pathway and its reactions. In this review, we provide an overview of molecular aspects of glycerolipid synthesis, focusing on recent insights into the synthesis of TGs. Further, we go beyond the Kennedy pathway to describe the mechanisms for storage of TG in cytosolic lipid droplets and discuss how overwhelming these pathways leads to ER stress and cellular toxicity, as seen in diseases linked to lipid overload and obesity.
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Affiliation(s)
- Robert V Farese
- Department of Molecular Metabolism, Harvard T. H. Chan School of Public Health, Boston, Massachusetts 02115, USA
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts 02142, USA
- Center for Causes and Prevention of Cardiovascular Disease (CAP-CVD), Harvard T. H. Chan School of Public Health, Boston, Massachusetts 02115, USA
| | - Tobias C Walther
- Department of Molecular Metabolism, Harvard T. H. Chan School of Public Health, Boston, Massachusetts 02115, USA
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts 02142, USA
- Center for Causes and Prevention of Cardiovascular Disease (CAP-CVD), Harvard T. H. Chan School of Public Health, Boston, Massachusetts 02115, USA
- Howard Hughes Medical Institute Boston, Boston, Massachusetts 02115, USA
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18
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Ibayashi M, Aizawa R, Mitsui J, Tsukamoto S. Lipid droplet synthesis is associated with angiogenesis in mouse ovarian follicles†. Biol Reprod 2023; 108:492-503. [PMID: 36579469 DOI: 10.1093/biolre/ioac223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 11/21/2022] [Accepted: 12/24/2022] [Indexed: 12/30/2022] Open
Abstract
Lipid droplets (LDs) are endoplasmic reticulum (ER)-derived organelles comprising a core of neutral lipids surrounded by a phospholipid monolayer. Lipid droplets play important roles in lipid metabolism and energy homeostasis. Mammalian ovaries have been hypothesized to use neutral lipids stored in LDs to produce the hormones and nutrients necessary for rapid follicular development; however, our understanding of LD synthesis remains incomplete. In this study, we generated transgenic reporter mice that express mCherry fused to HPos, a minimal peptide that localizes specifically to nascent LDs synthesized at the ER. With this tool for visualizing initial LD synthesis in ovaries, we found that LDs are synthesized continuously in theca cells but rarely in inner granulosa cells (Gc) during early follicular development. Administration of exogenous gonadotropin enhances LD synthesis in the Gc, suggesting that LD synthesis is hormonally regulated. In contrast, we observed copious LD synthesis in the corpus luteum, and excessive LDs accumulation in atretic follicles. Furthermore, we demonstrated that LD synthesis is synchronized with angiogenesis around the follicle and that suppressing angiogenesis caused defective LD biosynthesis in developing follicles. Overall, our study is the first to demonstrate a spatiotemporally regulated interplay between LD synthesis and neovascularization during mammalian follicular development.
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Affiliation(s)
- Megumi Ibayashi
- Laboratory Animal and Genome Sciences Section, National Institutes for Quantum Science and Technology, Anagawa, Chiba, Japan
| | - Ryutaro Aizawa
- Laboratory Animal and Genome Sciences Section, National Institutes for Quantum Science and Technology, Anagawa, Chiba, Japan
| | - Junichiro Mitsui
- Laboratory Animal and Genome Sciences Section, National Institutes for Quantum Science and Technology, Anagawa, Chiba, Japan
- Department of Comprehensive Reproductive Medicine, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
| | - Satoshi Tsukamoto
- Laboratory Animal and Genome Sciences Section, National Institutes for Quantum Science and Technology, Anagawa, Chiba, Japan
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19
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A Perspective on the Link between Mitochondria-Associated Membranes (MAMs) and Lipid Droplets Metabolism in Neurodegenerative Diseases. BIOLOGY 2023; 12:biology12030414. [PMID: 36979106 PMCID: PMC10045954 DOI: 10.3390/biology12030414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 03/03/2023] [Accepted: 03/06/2023] [Indexed: 03/11/2023]
Abstract
Mitochondria interact with the endoplasmic reticulum (ER) through contacts called mitochondria-associated membranes (MAMs), which control several processes, such as the ER stress response, mitochondrial and ER dynamics, inflammation, apoptosis, and autophagy. MAMs represent an important platform for transport of non-vesicular phospholipids and cholesterol. Therefore, this region is highly enriched in proteins involved in lipid metabolism, including the enzymes that catalyze esterification of cholesterol into cholesteryl esters (CE) and synthesis of triacylglycerols (TAG) from fatty acids (FAs), which are then stored in lipid droplets (LDs). LDs, through contact with other organelles, prevent the toxic consequences of accumulation of unesterified (free) lipids, including lipotoxicity and oxidative stress, and serve as lipid reservoirs that can be used under multiple metabolic and physiological conditions. The LDs break down by autophagy releases of stored lipids for energy production and synthesis of membrane components and other macromolecules. Pathological lipid deposition and autophagy disruption have both been reported to occur in several neurodegenerative diseases, supporting that lipid metabolism alterations are major players in neurodegeneration. In this review, we discuss the current understanding of MAMs structure and function, focusing on their roles in lipid metabolism and the importance of autophagy in LDs metabolism, as well as the changes that occur in neurogenerative diseases.
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20
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The role of CaMKK2 in Golgi-associated vesicle trafficking. Biochem Soc Trans 2023; 51:331-342. [PMID: 36815702 PMCID: PMC9987998 DOI: 10.1042/bst20220833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 02/03/2023] [Accepted: 02/07/2023] [Indexed: 02/24/2023]
Abstract
Calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2) is a serine/threonine-protein kinase, that is involved in maintaining various physiological and cellular processes within the cell that regulate energy homeostasis and cell growth. CaMKK2 regulates glucose metabolism by the activation of downstream kinases, AMP-activated protein kinase (AMPK) and other calcium/calmodulin-dependent protein kinases. Consequently, its deregulation has a role in multiple human metabolic diseases including obesity and cancer. Despite the importance of CaMKK2, its signalling pathways and pathological mechanisms are not completely understood. Recent work has been aimed at broadening our understanding of the biological functions of CaMKK2. These studies have uncovered new interaction partners that have led to the description of new functions that include lipogenesis and Golgi vesicle trafficking. Here, we review recent insights into the role of CaMKK2 in membrane trafficking mechanisms and discuss the functional implications in a cellular context and for disease.
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21
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Xu M, Chen X, Yu Z, Li X. Receptors that bind to PEDF and their therapeutic roles in retinal diseases. Front Endocrinol (Lausanne) 2023; 14:1116136. [PMID: 37139333 PMCID: PMC10149954 DOI: 10.3389/fendo.2023.1116136] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 04/04/2023] [Indexed: 05/05/2023] Open
Abstract
Retinal neovascular, neurodegenerative, and inflammatory diseases represented by diabetic retinopathy are the main types of blinding eye disorders that continually cause the increased burden worldwide. Pigment epithelium-derived factor (PEDF) is an endogenous factor with multiple effects including neurotrophic activity, anti-angiogenesis, anti-tumorigenesis, and anti-inflammatory activity. PEDF activity depends on the interaction with the proteins on the cell surface. At present, seven independent receptors, including adipose triglyceride lipase, laminin receptor, lipoprotein receptor-related protein, plexin domain-containing 1, plexin domain-containing 2, F1-ATP synthase, and vascular endothelial growth factor receptor 2, have been demonstrated and confirmed to be high affinity receptors for PEDF. Understanding the interactions between PEDF and PEDF receptors, their roles in normal cellular metabolism and the response the initiate in disease will be accommodating for elucidating the ways in which inflammation, angiogenesis, and neurodegeneration exacerbate disease pathology. In this review, we firstly introduce PEDF receptors comprehensively, focusing particularly on their expression pattern, ligands, related diseases, and signal transduction pathways, respectively. We also discuss the interactive ways of PEDF and receptors to expand the prospective understanding of PEDF receptors in the diagnosis and treatment of retinal diseases.
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22
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Nur EAA, Kobayashi K, Ohte S, Tomoda H, Ohshiro T. Screening for microbial potentiators of neutral lipid degradation in CHO-K1 cells. Drug Discov Ther 2022; 16:273-279. [PMID: 36450503 DOI: 10.5582/ddt.2022.01087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
A cell-based assay was conducted to screen microbial culture broths for potentiators of neutral lipid degradation in Chinese Hamster Ovary K1 cells. A total of 5,363 microbial cultures from fungi and actinomycetes were screened in this assay. Brefeldin A (1) from fungal cultures was found to promote the degradation of triacylglycerol (TG) with an EC50 of 2.6 µM. Beauveriolides I (2), III (3), beauverolides A (4), B (5), and K (6) from fungal cultures showed potentiating effect on cholesteryl ester (CE) degradation with EC50s ranging from 0.02 to 0.13 µM. Among these compounds, 2 and 6 exhibited the strongest activities (EC50, 0.02 µM). From actinomycete cultures, oxohygrolidin (7) (EC50 for TG and CE, > 1.7 and 0.8 µM, respectively) and hygrolidin (8) (EC50 for TG and CE, 0.08 and 0.004 µM, respectively) promoted degradation of CE more preferably than TG.
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Affiliation(s)
- Elyza Aiman Azizah Nur
- Department of Microbial Chemistry, Graduate School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan
| | - Keisuke Kobayashi
- Department of Microbial Chemistry, Graduate School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan.,Medicinal Research Laboratories, School of Pharmacy, Kitasato University, Tokyo, Japan
| | - Satoshi Ohte
- Department of Microbial Chemistry, Graduate School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan.,Medicinal Research Laboratories, School of Pharmacy, Kitasato University, Tokyo, Japan
| | - Hiroshi Tomoda
- Department of Microbial Chemistry, Graduate School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan.,Laboratory of Drug Discovery, Graduate School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan
| | - Taichi Ohshiro
- Department of Microbial Chemistry, Graduate School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan.,Medicinal Research Laboratories, School of Pharmacy, Kitasato University, Tokyo, Japan
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23
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Campbell LE, Anderson AM, Chen Y, Johnson SM, McMahon CE, Liu J. Identification of motifs and mechanisms for lipid droplet targeting of the lipolytic inhibitors G0S2 and HIG2. J Cell Sci 2022; 135:285951. [PMID: 36420951 PMCID: PMC10112975 DOI: 10.1242/jcs.260236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 11/15/2022] [Indexed: 11/27/2022] Open
Abstract
G0S2 and HIG2 are two selective inhibitors of ATGL (also known as PNPLA2), the key enzyme for intracellular lipolysis. Whereas G0S2 regulates triglyceride (TG) mobilization in adipocytes and hepatocytes, HIG2 functions to enhance intracellular TG accumulation under hypoxic conditions. A homologous hydrophobic domain (HD) is shared by G0S2 and HIG2 (also known as HILPDA) for binding to ATGL. However, the determinants of their lipid droplet (LD) localization are unknown. Here, we study how G0S2 and HIG2 are targeted to LDs, and identify both ATGL-independent and -dependent mechanisms. Structural prediction and studies in cells reveal that ATGL-independent localization of G0S2 to both the endoplasmic reticulum (ER) and LDs is mediated by a hairpin structure consisting of two hydrophobic sequences. Positively charged residues in the hinge region play a crucial role in sorting G0S2, which initially localizes to ER, to LDs. Interestingly, the role of these positive charges becomes dispensable when ATGL is co-expressed. In comparison, HIG2, which lacks a similar hairpin structure, is dependent on ATGL for its full LD targeting. Thus, our studies identify specific structural features and mechanisms for mediating accumulation of these two ATGL inhibitors on LDs.
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Affiliation(s)
- Latoya E Campbell
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine & Science, Rochester, MN 55905, USA.,College of Health Solutions, Arizona State University, Tempe, AZ 85281, USA
| | - Aaron M Anderson
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine & Science, Rochester, MN 55905, USA.,Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Yongbin Chen
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine & Science, Rochester, MN 55905, USA
| | - Scott M Johnson
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine & Science, Rochester, MN 55905, USA.,Mayo Clinic Graduate School of Biomedical Sciences, Rochester, MN 55905, USA
| | - Cailin E McMahon
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine & Science, Rochester, MN 55905, USA
| | - Jun Liu
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine & Science, Rochester, MN 55905, USA.,Division of Endocrinology, Diabetes, Metabolism and Nutrition, Mayo Clinic in Rochester, Rochester, MN 55905, USA
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24
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Gasparian A, Aksenova M, Oliver D, Levina E, Doran R, Lucius M, Piroli G, Oleinik N, Ogretmen B, Mythreye K, Frizzell N, Broude E, Wyatt MD, Shtutman M. Depletion of COPI in cancer cells: the role of reactive oxygen species in the induction of lipid accumulation, noncanonical lipophagy and apoptosis. Mol Biol Cell 2022; 33:ar135. [PMID: 36222847 PMCID: PMC9727790 DOI: 10.1091/mbc.e21-08-0420] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The coatomer protein complex 1 (COPI) is a multisubunit complex that coats intracellular vesicles and is involved in intracellular protein trafficking. Recently we and others found that depletion of COPI complex subunits zeta (COPZ1) and delta (ARCN1) preferentially kills tumor cells relative to normal cells. Here we delineate the specific cellular effects and sequence of events of COPI complex depletion in tumor cells. We find that this depletion leads to the inhibition of mitochondrial oxidative phosphorylation and the elevation of reactive oxygen species (ROS) production, followed by accumulation of lipid droplets (LDs) and autophagy-associated proteins LC3-II and SQSTM1/p62 and, finally, apoptosis of the tumor cells. Inactivation of ROS in COPI-depleted cells with the mitochondrial-specific quencher, mitoquinone mesylate, attenuated apoptosis and markedly decreased both the size and the number of LDs. COPI depletion caused ROS-dependent accumulation of LC3-II and SQSTM1 which colocalizes with LDs. Lack of double-membrane autophagosomes and insensitivity to Atg5 deletion suggested an accumulation of a microlipophagy complex on the surface of LDs induced by depletion of the COPI complex. Our findings suggest a sequence of cellular events triggered by COPI depletion, starting with inhibition of oxidative phosphorylation, followed by ROS activation and accumulation of LDs and apoptosis.
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Affiliation(s)
- A. Gasparian
- Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, University of South Carolina, Columbia, SC 29208
| | - M. Aksenova
- Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, University of South Carolina, Columbia, SC 29208
| | - D. Oliver
- Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, University of South Carolina, Columbia, SC 29208
| | - E. Levina
- Department of Biological Sciences College of Art and Science, University of South Carolina, Columbia, SC 29208
| | - R. Doran
- Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, University of South Carolina, Columbia, SC 29208
| | - M. Lucius
- Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, University of South Carolina, Columbia, SC 29208
| | - G. Piroli
- Department of Pharmacology, Physiology & Neuroscience, School of Medicine, University of South Carolina, Columbia, SC 29208
| | - N. Oleinik
- Department of Biochemistry and Molecular Biology, Hollings Cancer Center, Medical University of South Carolina, Charleston, SC 29425
| | - B. Ogretmen
- Department of Biochemistry and Molecular Biology, Hollings Cancer Center, Medical University of South Carolina, Charleston, SC 29425
| | - K. Mythreye
- Department of Pathology, Division of Molecular and Cellular Pathology, University of Alabama at Birmingham, Birmingham, AL 35233
| | - N. Frizzell
- Department of Pharmacology, Physiology & Neuroscience, School of Medicine, University of South Carolina, Columbia, SC 29208
| | - E. Broude
- Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, University of South Carolina, Columbia, SC 29208
| | - M. D. Wyatt
- Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, University of South Carolina, Columbia, SC 29208
| | - M. Shtutman
- Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, University of South Carolina, Columbia, SC 29208,*Address correspondence to: M. Shtutman ()
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25
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Navare AT, Mast FD, Olivier JP, Bertomeu T, Neal ML, Carpp LN, Kaushansky A, Coulombe-Huntington J, Tyers M, Aitchison JD. Viral protein engagement of GBF1 induces host cell vulnerability through synthetic lethality. J Cell Biol 2022; 221:213618. [PMID: 36305789 PMCID: PMC9623979 DOI: 10.1083/jcb.202011050] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 06/15/2022] [Accepted: 08/26/2022] [Indexed: 12/14/2022] Open
Abstract
Viruses co-opt host proteins to carry out their lifecycle. Repurposed host proteins may thus become functionally compromised; a situation analogous to a loss-of-function mutation. We term such host proteins as viral-induced hypomorphs. Cells bearing cancer driver loss-of-function mutations have successfully been targeted with drugs perturbing proteins encoded by the synthetic lethal (SL) partners of cancer-specific mutations. Similarly, SL interactions of viral-induced hypomorphs can potentially be targeted as host-based antiviral therapeutics. Here, we use GBF1, which supports the infection of many RNA viruses, as a proof-of-concept. GBF1 becomes a hypomorph upon interaction with the poliovirus protein 3A. Screening for SL partners of GBF1 revealed ARF1 as the top hit, disruption of which selectively killed cells that synthesize 3A alone or in the context of a poliovirus replicon. Thus, viral protein interactions can induce hypomorphs that render host cells selectively vulnerable to perturbations that leave uninfected cells otherwise unscathed. Exploiting viral-induced vulnerabilities could lead to broad-spectrum antivirals for many viruses, including SARS-CoV-2.
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Affiliation(s)
- Arti T. Navare
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA
| | - Fred D. Mast
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA
| | - Jean Paul Olivier
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA
| | - Thierry Bertomeu
- Institute for Research in Immunology and Cancer, Université de Montréal, Montreal, Quebec, Canada
| | - Maxwell L. Neal
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA
| | | | - Alexis Kaushansky
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA,Department of Pediatrics, University of Washington, Seattle, WA
| | | | - Mike Tyers
- Institute for Research in Immunology and Cancer, Université de Montréal, Montreal, Quebec, Canada
| | - John D. Aitchison
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA,Department of Pediatrics, University of Washington, Seattle, WA,Department of Biochemistry, University of Washington, Seattle, WA,Correspondence to John D. Aitchison:
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26
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Huang S, Liu Z, Cao W, Li H, Zhang W, Cui Y, Hu S, Luo M, Zhu Y, Zhao Q, Xie L, Gao C, Xiao S, Jiang L. The plant ESCRT component FREE1 regulates peroxisome-mediated turnover of lipid droplets in germinating Arabidopsis seedlings. THE PLANT CELL 2022; 34:4255-4273. [PMID: 35775937 PMCID: PMC9614499 DOI: 10.1093/plcell/koac195] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 06/20/2022] [Indexed: 05/28/2023]
Abstract
Lipid droplets (LDs) stored during seed development are mobilized and provide essential energy and lipids to support seedling growth upon germination. Triacylglycerols (TAGs) are the main neutral lipids stored in LDs. The lipase SUGAR DEPENDENT 1 (SDP1), which hydrolyzes TAGs in Arabidopsis thaliana, is localized on peroxisomes and traffics to the LD surface through peroxisomal extension, but the underlying mechanism remains elusive. Here, we report a previously unknown function of a plant-unique endosomal sorting complex required for transport (ESCRT) component FYVE DOMAIN PROTEIN REQUIRED FOR ENDOSOMAL SORTING 1 (FREE1) in regulating peroxisome/SDP1-mediated LD turnover in Arabidopsis. We showed that LD degradation was impaired in germinating free1 mutant; moreover, the tubulation of SDP1- or PEROXIN 11e (PEX11e)-marked peroxisomes and the migration of SDP1-positive peroxisomes to the LD surface were altered in the free1 mutant. Electron tomography analysis showed that peroxisomes failed to form tubules to engulf LDs in free1, unlike in the wild-type. FREE1 interacted directly with both PEX11e and SDP1, suggesting that these interactions may regulate peroxisomal extension and trafficking of the lipase SDP1 to LDs. Taken together, our results demonstrate a pivotal role for FREE1 in LD degradation in germinating seedlings via regulating peroxisomal tubulation and SDP1 targeting.
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Affiliation(s)
- Shuxian Huang
- School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, China
| | - Zhiqi Liu
- School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, China
| | - Wenhan Cao
- School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, China
| | - Hongbo Li
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University (SCNU), Guangzhou, 510631, China
| | - Wenxin Zhang
- School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, China
| | - Yong Cui
- School of Life Sciences, State Key Laboratory of Cellular Stress Biology, Xiamen University, Xiamen, 361102, China
| | - Shuai Hu
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, China
| | - Mengqian Luo
- School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, China
| | - Ying Zhu
- School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, China
| | - Qiong Zhao
- School of Life Sciences, East China Normal University, Shanghai, 200062, China
| | - Lijuan Xie
- College of Plant Protection, State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou, 510642, China
| | - Caiji Gao
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University (SCNU), Guangzhou, 510631, China
| | - Shi Xiao
- School of Life Sciences, State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources, Sun Yat-sen University, Guangzhou, 510275, China
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27
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Raja R, Fonseka O, Ganenthiran H, Liu W. The multifaceted roles of ER and Golgi in metabolic cardiomyopathy. Front Cardiovasc Med 2022; 9:999044. [PMID: 36119738 PMCID: PMC9479098 DOI: 10.3389/fcvm.2022.999044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 08/15/2022] [Indexed: 01/10/2023] Open
Abstract
Metabolic cardiomyopathy is a significant global financial and health challenge; however, pathophysiological mechanisms governing this entity remain poorly understood. Among the main features of metabolic cardiomyopathy, the changes to cellular lipid metabolism have been studied and targeted for the discovery of novel treatment strategies obtaining contrasting results. The endoplasmic reticulum (ER) and Golgi apparatus (GA) carry out protein modification, sorting, and secretion activities that are more commonly studied from the perspective of protein quality control; however, they also drive the maintenance of lipid homeostasis. In response to metabolic stress, ER and GA regulate the expression of genes involved in cardiac lipid biogenesis and participate in lipid droplet formation and degradation. Due to the varied roles these organelles play, this review will focus on recapitulating the alterations and crosstalk between ER, GA, and lipid metabolism in cardiac metabolic syndrome.
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28
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Identification of two pathways mediating protein targeting from ER to lipid droplets. Nat Cell Biol 2022; 24:1364-1377. [PMID: 36050470 PMCID: PMC9481466 DOI: 10.1038/s41556-022-00974-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 07/05/2022] [Indexed: 11/20/2022]
Abstract
Pathways localizing proteins to their sites of action are essential for eukaryotic cell organization and function. Although mechanisms of protein targeting to many organelles have been defined, how proteins, such as metabolic enzymes, target from the endoplasmic reticulum (ER) to cellular lipid droplets (LDs) is poorly understood. Here we identify two distinct pathways for ER-to-LD protein targeting: early targeting at LD formation sites during formation, and late targeting to mature LDs after their formation. Using systematic, unbiased approaches in Drosophila cells, we identified specific membrane-fusion machinery, including regulators, a tether and SNARE proteins, that are required for the late targeting pathway. Components of this fusion machinery localize to LD–ER interfaces and organize at ER exit sites. We identified multiple cargoes for early and late ER-to-LD targeting pathways. Our findings provide a model for how proteins target to LDs from the ER either during LD formation or by protein-catalysed formation of membrane bridges. Song et al. identify two protein-targeting pathways from the endoplasmic reticulum to (1) early lipid droplets (LDs) and (2) mature lipid droplets. They define key factors mediating the second, late pathway and its many cargoes.
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29
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Sánchez-Álvarez M, Del Pozo MÁ, Bosch M, Pol A. Insights Into the Biogenesis and Emerging Functions of Lipid Droplets From Unbiased Molecular Profiling Approaches. Front Cell Dev Biol 2022; 10:901321. [PMID: 35756995 PMCID: PMC9213792 DOI: 10.3389/fcell.2022.901321] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 05/17/2022] [Indexed: 11/30/2022] Open
Abstract
Lipid droplets (LDs) are spherical, single sheet phospholipid-bound organelles that store neutral lipids in all eukaryotes and some prokaryotes. Initially conceived as relatively inert depots for energy and lipid precursors, these highly dynamic structures play active roles in homeostatic functions beyond metabolism, such as proteostasis and protein turnover, innate immunity and defense. A major share of the knowledge behind this paradigm shift has been enabled by the use of systematic molecular profiling approaches, capable of revealing and describing these non-intuitive systems-level relationships. Here, we discuss these advances and some of the challenges they entail, and highlight standing questions in the field.
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Affiliation(s)
- Miguel Sánchez-Álvarez
- Cell and Developmental Biology Area, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Miguel Ángel Del Pozo
- Cell and Developmental Biology Area, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Marta Bosch
- Lipid Trafficking and Disease Group, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.,Department of Biomedical Sciences, Faculty of Medicine, Universitat de Barcelona, Barcelona, Spain
| | - Albert Pol
- Lipid Trafficking and Disease Group, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.,Department of Biomedical Sciences, Faculty of Medicine, Universitat de Barcelona, Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
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30
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Sar1 Affects the Localization of Perilipin 2 to Lipid Droplets. Int J Mol Sci 2022; 23:ijms23126366. [PMID: 35742827 PMCID: PMC9223735 DOI: 10.3390/ijms23126366] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 06/03/2022] [Accepted: 06/03/2022] [Indexed: 02/05/2023] Open
Abstract
Lipid droplets (LDs) are intracellular organelles that are ubiquitous in many types of cells. The LD core consists of triacylglycerols (TGs) surrounded by a phospholipid monolayer and surface proteins such as perilipin 2 (PLIN2). Although TGs accumulate in the phospholipid bilayer of the endoplasmic reticulum (ER) and subsequently nascent LDs buds from ER, the mechanism by which LD proteins are transported to LD particles is not fully understood. Sar1 is a GTPase known as a regulator of coat protein complex Ⅱ (COPⅡ) vesicle budding, and its role in LD formation was investigated in this study. HuH7 human hepatoma cells were infected with adenoviral particles containing genes coding GFP fused with wild-type Sar1 (Sar1 WT) or a GTPase mutant form (Sar1 H79G). When HuH7 cells were treated with oleic acid, Sar1 WT formed a ring-like structure around the LDs. The transient expression of Sar1 did not significantly alter the levels of TG and PLIN2 in the cells. However, the localization of PLIN2 to the LDs decreased in the cells expressing Sar1 H79G. Furthermore, the effects of Sar1 on PLIN2 localization to the LDs were verified by the suppression of endogenous Sar1 using the short hairpin RNA technique. In conclusion, it was found that Sar1 has some roles in the intracellular distribution of PLIN2 to LDs in liver cells.
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31
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McPhee MJ, Salsman J, Foster J, Thompson J, Mathavarajah S, Dellaire G, Ridgway ND. Running 'LAPS' Around nLD: Nuclear Lipid Droplet Form and Function. Front Cell Dev Biol 2022; 10:837406. [PMID: 35178392 PMCID: PMC8846306 DOI: 10.3389/fcell.2022.837406] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 01/10/2022] [Indexed: 12/12/2022] Open
Abstract
The nucleus harbours numerous protein subdomains and condensates that regulate chromatin organization, gene expression and genomic stress. A novel nuclear subdomain that is formed following exposure of cells to excess fatty acids is the nuclear lipid droplet (nLD), which is composed of a neutral lipid core surrounded by a phospholipid monolayer and associated regulatory and lipid biosynthetic enzymes. While structurally resembling cytoplasmic LDs, nLDs are formed by distinct but poorly understood mechanisms that involve the emergence of lipid droplets from the lumen of the nucleoplasmic reticulum and de novo lipid synthesis. Luminal lipid droplets that emerge into the nucleoplasm do so at regions of the inner nuclear membrane that become enriched in promyelocytic leukemia (PML) protein. The resulting nLDs that retain PML on their surface are termed lipid-associated PML structures (LAPS), and are distinct from canonical PML nuclear bodies (NB) as they lack key proteins and modifications associated with these NBs. PML is a key regulator of nuclear signaling events and PML NBs are sites of gene regulation and post-translational modification of transcription factors. Therefore, the subfraction of nLDs that form LAPS could regulate lipid stress responses through their recruitment and retention of the PML protein. Both nLDs and LAPS have lipid biosynthetic enzymes on their surface suggesting they are active sites for nuclear phospholipid and triacylglycerol synthesis as well as global lipid regulation. In this review we have summarized the current understanding of nLD and LAPS biogenesis in different cell types, their structure and composition relative to other PML-associated cellular structures, and their role in coordinating a nuclear response to cellular overload of fatty acids.
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Affiliation(s)
- Michael J McPhee
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, NS, Canada
| | - Jayme Salsman
- Department of Pathology, Dalhousie University, Halifax, NS, Canada
| | - Jason Foster
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, NS, Canada
| | - Jordan Thompson
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, NS, Canada
| | | | - Graham Dellaire
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, NS, Canada.,Department of Pathology, Dalhousie University, Halifax, NS, Canada
| | - Neale D Ridgway
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, NS, Canada.,Department of Pediatrics, Dalhousie University, Halifax, NS, Canada
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32
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Khodayari N, Wang RL, Oshins R, Lu Y, Millett M, Aranyos AM, Mostofizadeh S, Scindia Y, Flagg TO, Brantly M. The Mechanism of Mitochondrial Injury in Alpha-1 Antitrypsin Deficiency Mediated Liver Disease. Int J Mol Sci 2021; 22:13255. [PMID: 34948056 PMCID: PMC8704552 DOI: 10.3390/ijms222413255] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 12/03/2021] [Accepted: 12/07/2021] [Indexed: 12/13/2022] Open
Abstract
Alpha-1 antitrypsin deficiency (AATD) is caused by a single mutation in the SERPINA1 gene, which culminates in the accumulation of misfolded alpha-1 antitrypsin (ZAAT) within the endoplasmic reticulum (ER) of hepatocytes. AATD is associated with liver disease resulting from hepatocyte injury due to ZAAT-mediated toxic gain-of-function and ER stress. There is evidence of mitochondrial damage in AATD-mediated liver disease; however, the mechanism by which hepatocyte retention of aggregated ZAAT leads to mitochondrial injury is unknown. Previous studies have shown that ER stress is associated with both high concentrations of fatty acids and mitochondrial dysfunction in hepatocytes. Using a human AAT transgenic mouse model and hepatocyte cell lines, we show abnormal mitochondrial morphology and function, and dysregulated lipid metabolism, which are associated with hepatic expression and accumulation of ZAAT. We also describe a novel mechanism of ZAAT-mediated mitochondrial dysfunction. We provide evidence that misfolded ZAAT translocates to the mitochondria for degradation. Furthermore, inhibition of ZAAT expression restores the mitochondrial function in ZAAT-expressing hepatocytes. Altogether, our results show that ZAAT aggregation in hepatocytes leads to mitochondrial dysfunction. Our findings suggest a plausible model for AATD liver injury and the possibility of mechanism-based therapeutic interventions for AATD liver disease.
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Affiliation(s)
- Nazli Khodayari
- Division of Pulmonary, Department of Medicine, University of Florida, Gainesville, FL 32610, USA; (R.L.W.); (R.O.); (Y.L.); (M.M.); (A.M.A.); (Y.S.); (T.O.F.)
| | - Rejean L. Wang
- Division of Pulmonary, Department of Medicine, University of Florida, Gainesville, FL 32610, USA; (R.L.W.); (R.O.); (Y.L.); (M.M.); (A.M.A.); (Y.S.); (T.O.F.)
| | - Regina Oshins
- Division of Pulmonary, Department of Medicine, University of Florida, Gainesville, FL 32610, USA; (R.L.W.); (R.O.); (Y.L.); (M.M.); (A.M.A.); (Y.S.); (T.O.F.)
| | - Yuanqing Lu
- Division of Pulmonary, Department of Medicine, University of Florida, Gainesville, FL 32610, USA; (R.L.W.); (R.O.); (Y.L.); (M.M.); (A.M.A.); (Y.S.); (T.O.F.)
| | - Michael Millett
- Division of Pulmonary, Department of Medicine, University of Florida, Gainesville, FL 32610, USA; (R.L.W.); (R.O.); (Y.L.); (M.M.); (A.M.A.); (Y.S.); (T.O.F.)
| | - Alek M. Aranyos
- Division of Pulmonary, Department of Medicine, University of Florida, Gainesville, FL 32610, USA; (R.L.W.); (R.O.); (Y.L.); (M.M.); (A.M.A.); (Y.S.); (T.O.F.)
| | - Sayedamin Mostofizadeh
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida, Gainesville, FL 32610, USA;
| | - Yogesh Scindia
- Division of Pulmonary, Department of Medicine, University of Florida, Gainesville, FL 32610, USA; (R.L.W.); (R.O.); (Y.L.); (M.M.); (A.M.A.); (Y.S.); (T.O.F.)
| | - Tammy O. Flagg
- Division of Pulmonary, Department of Medicine, University of Florida, Gainesville, FL 32610, USA; (R.L.W.); (R.O.); (Y.L.); (M.M.); (A.M.A.); (Y.S.); (T.O.F.)
| | - Mark Brantly
- Division of Pulmonary, Department of Medicine, University of Florida, Gainesville, FL 32610, USA; (R.L.W.); (R.O.); (Y.L.); (M.M.); (A.M.A.); (Y.S.); (T.O.F.)
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Huang W, Gao F, Zhang Y, Chen T, Xu C. Lipid Droplet-Associated Proteins in Cardiomyopathy. ANNALS OF NUTRITION AND METABOLISM 2021; 78:1-13. [PMID: 34856540 DOI: 10.1159/000520122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 10/08/2021] [Indexed: 11/19/2022]
Abstract
BACKGROUND The heart requires a high rate of fatty-acid oxidation (FAO) to meet its energy needs. Neutral lipids are the main source of energy for the heart and are stored in lipid droplets (LDs), which are cytosolic organelles that primarily serve to store neutral lipids and regulate cellular lipid metabolism. LD-associated proteins (LDAPs) are proteins either located on the surface of the LDs or reside in the cytosol and contribute to lipid metabolism. Therefore, abnormal cardiac lipid accumulation or FAO can alter the redox state of the heart, resulting in cardiomyopathy, a group of diseases that negatively affect the myocardial function, thereby leading to heart failure and even cardiac death. SUMMARY LDs, along with LDAPs, are pivotal for modulating heart lipid homeostasis. The proper cardiac development and the maintenance of its normal function depend largely on lipid homeostasis regulated by LDs and LDAPs. Overexpression or deletion of specific LDAPs can trigger myocardial dysfunction and may contribute to the development of cardiomyopathy. Extensive connections and interactions may also exist between LDAPs. Key Message: In this review, the various mechanisms involved in LDAP-mediated regulation of lipid metabolism, the association between cardiac development and lipid metabolism, as well as the role of LDAPs in cardiomyopathy progression are discussed.
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Affiliation(s)
- Weiwei Huang
- Obstetrics and Gynecology Hospital, Fudan University, Shanghai, China.,Department of Physiology and Pathophysiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Fei Gao
- Department of Physiology and Pathophysiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Yuting Zhang
- Department of Physiology and Pathophysiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Tianhui Chen
- Department of Ophthalmology and Vision Science, Eye and ENT Hospital of Fudan University, Shanghai, China.,Key Laboratory of Myopia of State Health Ministry, and Key Laboratory of Visual Impairment and Restoration of Shanghai, Shanghai, China
| | - Chen Xu
- Department of Physiology and Pathophysiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
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34
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Ajjaji D, Ben M'barek K, Boson B, Omrane M, Gassama-Diagne A, Blaud M, Penin F, Diaz E, Ducos B, Cosset FL, Thiam AR. Hepatitis C virus core protein uses triacylglycerols to fold onto the endoplasmic reticulum membrane. Traffic 2021; 23:63-80. [PMID: 34729868 DOI: 10.1111/tra.12825] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 10/16/2021] [Accepted: 11/01/2021] [Indexed: 12/12/2022]
Abstract
Lipid droplets (LDs) are involved in viral infections, but exactly how remains unclear. Here, we study the hepatitis C virus (HCV) whose core capsid protein binds to LDs but is also involved in the assembly of virions at the endoplasmic reticulum (ER) bilayer. We found that the amphipathic helix-containing domain of core, D2, senses triglycerides (TGs) rather than LDs per se. In the absence of LDs, D2 can bind to the ER membrane but only if TG molecules are present in the bilayer. Accordingly, the pharmacological inhibition of the diacylglycerol O-acyltransferase enzymes, mediating TG synthesis in the ER, inhibits D2 association with the bilayer. We found that TG molecules enable D2 to fold into alpha helices. Sequence analysis reveals that D2 resembles the apoE lipid-binding region. Our data support that TG in LDs promotes the folding of core, which subsequently relocalizes to contiguous ER regions. During this motion, core may carry TG molecules to these regions where HCV lipoviroparticles likely assemble. Consistent with this model, the inhibition of Arf1/COPI, which decreases LD surface accessibility to proteins and ER-LD material exchange, severely impedes the assembly of virions. Altogether, our data uncover a critical function of TG in the folding of core and HCV replication and reveals, more broadly, how TG accumulation in the ER may provoke the binding of soluble amphipathic helix-containing proteins to the ER bilayer.
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Affiliation(s)
- Dalila Ajjaji
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 24 rue Lhomond, Paris, 75005, France
| | - Kalthoum Ben M'barek
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 24 rue Lhomond, Paris, 75005, France
| | - Bertrand Boson
- CIRI-Centre International de Recherche en Infectiologie, Univ Lyon, Université Claude Bernard Lyon 1, Inserm, U1111, CNRS, UMR5308, ENS Lyon, Lyon, France
| | - Mohyeddine Omrane
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 24 rue Lhomond, Paris, 75005, France
| | - Ama Gassama-Diagne
- INSERM, Unité 1193, Villejuif, France.,Université Paris-Sud, UMR-S 1193, Villejuif, France
| | - Magali Blaud
- Université de Paris, CiTCoM, CNRS, Paris, France
| | - François Penin
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, UMR 5086, CNRS, Labex Ecofect, University of Lyon, Lyon, France
| | - Elise Diaz
- High Throughput qPCR Core Facility of the ENS, IBENS, PSL Research University, Paris, France
| | - Bertrand Ducos
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 24 rue Lhomond, Paris, 75005, France.,High Throughput qPCR Core Facility of the ENS, IBENS, PSL Research University, Paris, France
| | - François-Loïc Cosset
- CIRI-Centre International de Recherche en Infectiologie, Univ Lyon, Université Claude Bernard Lyon 1, Inserm, U1111, CNRS, UMR5308, ENS Lyon, Lyon, France
| | - Abdou Rachid Thiam
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 24 rue Lhomond, Paris, 75005, France
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35
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Grabner GF, Xie H, Schweiger M, Zechner R. Lipolysis: cellular mechanisms for lipid mobilization from fat stores. Nat Metab 2021; 3:1445-1465. [PMID: 34799702 DOI: 10.1038/s42255-021-00493-6] [Citation(s) in RCA: 185] [Impact Index Per Article: 61.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 10/15/2021] [Indexed: 12/13/2022]
Abstract
The perception that intracellular lipolysis is a straightforward process that releases fatty acids from fat stores in adipose tissue to generate energy has experienced major revisions over the last two decades. The discovery of new lipolytic enzymes and coregulators, the demonstration that lipophagy and lysosomal lipolysis contribute to the degradation of cellular lipid stores and the characterization of numerous factors and signalling pathways that regulate lipid hydrolysis on transcriptional and post-transcriptional levels have revolutionized our understanding of lipolysis. In this review, we focus on the mechanisms that facilitate intracellular fatty-acid mobilization, drawing on canonical and noncanonical enzymatic pathways. We summarize how intracellular lipolysis affects lipid-mediated signalling, metabolic regulation and energy homeostasis in multiple organs. Finally, we examine how these processes affect pathogenesis and how lipolysis may be targeted to potentially prevent or treat various diseases.
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Affiliation(s)
- Gernot F Grabner
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Hao Xie
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Martina Schweiger
- Institute of Molecular Biosciences, University of Graz, Graz, Austria.
- BioTechMed-Graz, Graz, Austria.
| | - Rudolf Zechner
- Institute of Molecular Biosciences, University of Graz, Graz, Austria.
- BioTechMed-Graz, Graz, Austria.
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36
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Intertwined and Finely Balanced: Endoplasmic Reticulum Morphology, Dynamics, Function, and Diseases. Cells 2021; 10:cells10092341. [PMID: 34571990 PMCID: PMC8472773 DOI: 10.3390/cells10092341] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/02/2021] [Accepted: 09/04/2021] [Indexed: 02/07/2023] Open
Abstract
The endoplasmic reticulum (ER) is an organelle that is responsible for many essential subcellular processes. Interconnected narrow tubules at the periphery and thicker sheet-like regions in the perinuclear region are linked to the nuclear envelope. It is becoming apparent that the complex morphology and dynamics of the ER are linked to its function. Mutations in the proteins involved in regulating ER structure and movement are implicated in many diseases including neurodegenerative diseases such as Alzheimer’s, Parkinson’s, and amyotrophic lateral sclerosis (ALS). The ER is also hijacked by pathogens to promote their replication. Bacteria such as Legionella pneumophila and Chlamydia trachomatis, as well as the Zika virus, bind to ER morphology and dynamics-regulating proteins to exploit the functions of the ER to their advantage. This review covers our understanding of ER morphology, including the functional subdomains and membrane contact sites that the organelle forms. We also focus on ER dynamics and the current efforts to quantify ER motion and discuss the diseases related to ER morphology and dynamics.
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37
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Cai XT, Li H, Jensen MB, Maksoud E, Borneo J, Liang Y, Quake SR, Luo L, Haghighi P, Jasper H. Gut cytokines modulate olfaction through metabolic reprogramming of glia. Nature 2021; 596:97-102. [PMID: 34290404 PMCID: PMC8911385 DOI: 10.1038/s41586-021-03756-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 06/22/2021] [Indexed: 02/06/2023]
Abstract
Infection-induced aversion against enteropathogens is a conserved sickness behaviour that can promote host survival1,2. The aetiology of this behaviour remains poorly understood, but studies in Drosophila have linked olfactory and gustatory perception to avoidance behaviours against toxic microorganisms3-5. Whether and how enteric infections directly influence sensory perception to induce or modulate such behaviours remains unknown. Here we show that enteropathogen infection in Drosophila can modulate olfaction through metabolic reprogramming of ensheathing glia of the antennal lobe. Infection-induced unpaired cytokine expression in the intestine activates JAK-STAT signalling in ensheathing glia, inducing the expression of glial monocarboxylate transporters and the apolipoprotein glial lazarillo (GLaz), and affecting metabolic coupling of glia and neurons at the antennal lobe. This modulates olfactory discrimination, promotes the avoidance of bacteria-laced food and increases fly survival. Although transient in young flies, gut-induced metabolic reprogramming of ensheathing glia becomes constitutive in old flies owing to age-related intestinal inflammation, which contributes to an age-related decline in olfactory discrimination. Our findings identify adaptive glial metabolic reprogramming by gut-derived cytokines as a mechanism that causes lasting changes in a sensory system in ageing flies.
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Affiliation(s)
- Xiaoyu Tracy Cai
- Immunology Discovery, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA.,Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA 94945-1400, USA.,University of Southern California, Los Angeles, CA 90007, USA
| | - Hongjie Li
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA,Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Martin Borch Jensen
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA 94945-1400, USA.,Gordian Biotechnology, 953 Indiana St., San Francisco, CA 94107, USA
| | - Elie Maksoud
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA 94945-1400, USA
| | - Jovencio Borneo
- FACS lab, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Yuxin Liang
- NGS lab, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Stephen R. Quake
- Department of Bioengineering and Department of Applied Physics, Stanford University, Stanford, CA 94305, USA,Chan Zuckerberg Biohub, Stanford, CA 94305, USA
| | - Liqun Luo
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Pejmun Haghighi
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA 94945-1400, USA
| | - Heinrich Jasper
- Immunology Discovery, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA.,Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA 94945-1400, USA.,Corresponding author: Heinrich Jasper, Genentech, 1 DNA Way, South San Francisco, California 94080, USA.
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38
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Nakatsu F, Kawasaki A. Functions of Oxysterol-Binding Proteins at Membrane Contact Sites and Their Control by Phosphoinositide Metabolism. Front Cell Dev Biol 2021; 9:664788. [PMID: 34249917 PMCID: PMC8264513 DOI: 10.3389/fcell.2021.664788] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Accepted: 05/06/2021] [Indexed: 01/10/2023] Open
Abstract
Lipids must be correctly transported within the cell to the right place at the right time in order to be fully functional. Non-vesicular lipid transport is mediated by so-called lipid transfer proteins (LTPs), which contain a hydrophobic cavity that sequesters lipid molecules. Oxysterol-binding protein (OSBP)-related proteins (ORPs) are a family of LTPs known to harbor lipid ligands, such as cholesterol and phospholipids. ORPs act as a sensor or transporter of those lipid ligands at membrane contact sites (MCSs) where two different cellular membranes are closely apposed. In particular, a characteristic functional property of ORPs is their role as a lipid exchanger. ORPs mediate counter-directional transport of two different lipid ligands at MCSs. Several, but not all, ORPs transport their lipid ligand from the endoplasmic reticulum (ER) in exchange for phosphatidylinositol 4-phosphate (PI4P), the other ligand, on apposed membranes. This ORP-mediated lipid “countertransport” is driven by the concentration gradient of PI4P between membranes, which is generated by its kinases and phosphatases. In this review, we will discuss how ORP function is tightly coupled to metabolism of phosphoinositides such as PI4P. Recent progress on the role of ORP-mediated lipid transport/countertransport at multiple MCSs in cellular functions will be also discussed.
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Affiliation(s)
- Fubito Nakatsu
- Department of Neurochemistry and Molecular Cell Biology, Niigata University School of Medicine and Graduate School of Medical/Dental Sciences, Niigata, Japan
| | - Asami Kawasaki
- Department of Neurochemistry and Molecular Cell Biology, Niigata University School of Medicine and Graduate School of Medical/Dental Sciences, Niigata, Japan
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39
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Mosquera JV, Bacher MC, Priess JR. Nuclear lipid droplets and nuclear damage in Caenorhabditis elegans. PLoS Genet 2021; 17:e1009602. [PMID: 34133414 PMCID: PMC8208577 DOI: 10.1371/journal.pgen.1009602] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 05/14/2021] [Indexed: 01/01/2023] Open
Abstract
Fat stored in the form of lipid droplets has long been considered a defining characteristic of cytoplasm. However, recent studies have shown that nuclear lipid droplets occur in multiple cells and tissues, including in human patients with fatty liver disease. The function(s) of stored fat in the nucleus has not been determined, and it is possible that nuclear fat is beneficial in some situations. Conversely, nuclear lipid droplets might instead be deleterious by disrupting nuclear organization or triggering aggregation of hydrophobic proteins. We show here that nuclear lipid droplets occur normally in C. elegans intestinal cells and germ cells, but appear to be associated with damage only in the intestine. Lipid droplets in intestinal nuclei can be associated with novel bundles of microfilaments (nuclear actin) and membrane tubules that might have roles in damage repair. To increase the normal, low frequency of nuclear lipid droplets in wild-type animals, we used a forward genetic screen to isolate mutants with abnormally large or abundant nuclear lipid droplets. Genetic analysis and cloning of three such mutants showed that the genes encode the lipid regulator SEIP-1/seipin, the inner nuclear membrane protein NEMP-1/Nemp1/TMEM194A, and a component of COPI vesicles called COPA-1/α-COP. We present several lines of evidence that the nuclear lipid droplet phenotype of copa-1 mutants results from a defect in retrieving mislocalized membrane proteins that normally reside in the endoplasmic reticulum. The seip-1 mutant causes most germ cells to have nuclear lipid droplets, the largest of which occupy more than a third of the nuclear volume. Nevertheless, the nuclear lipid droplets do not trigger apoptosis, and the germ cells differentiate into gametes that produce viable, healthy progeny. Thus, our results suggest that nuclear lipid droplets are detrimental to intestinal nuclei, but have no obvious deleterious effect on germ nuclei. Several human disorders such as obesity are associated with abnormal fat storage. Cells normally store fat in cytoplasmic organelles called lipid droplets. However, recent studies have shown that fat can also form inside of the cell nucleus, and the effects of nuclear fat are not known. Here we use the cell biology and genetics of the model organism C. elegans to study the causes and consequences of nuclear fat. We show that intestinal cells can contain nuclear fat, particularly during high-low-high changes in cytoplasmic fat that involve de novo fat synthesis. Nuclear fat is associated with multiple changes in intestinal nuclei that appear to represent damage and repair. Germ nuclei that normally differentiate into oocytes can also contain nuclear fat. In germ cells, however, even high levels of nuclear fat appear to cause little or no damage. Our results suggest that intestinal nuclei and germ cell nuclei might have different responses to nuclear fat in part because they differ in chromosomal organization at the nuclear envelope.
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Affiliation(s)
| | - Meghan C. Bacher
- Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - James R. Priess
- Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- Molecular and Cellular Biology Program, University of Washington, Seattle, Washington, United States of America
- Department of Biology, University of Washington, Seattle, Washington, United States of America
- * E-mail:
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40
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Giménez-Andrés M, Emeršič T, Antoine-Bally S, D'Ambrosio JM, Antonny B, Derganc J, Čopič A. Exceptional stability of a perilipin on lipid droplets depends on its polar residues, suggesting multimeric assembly. eLife 2021; 10:61401. [PMID: 33856341 PMCID: PMC8064757 DOI: 10.7554/elife.61401] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 04/14/2021] [Indexed: 12/23/2022] Open
Abstract
Numerous proteins target lipid droplets (LDs) through amphipathic helices (AHs). It is generally assumed that AHs insert bulky hydrophobic residues in packing defects at the LD surface. However, this model does not explain the targeting of perilipins, the most abundant and specific amphipathic proteins of LDs, which are weakly hydrophobic. A striking example is Plin4, whose gigantic and repetitive AH lacks bulky hydrophobic residues. Using a range of complementary approaches, we show that Plin4 forms a remarkably immobile and stable protein layer at the surface of cellular or in vitro generated oil droplets, and decreases LD size. Plin4 AH stability on LDs is exquisitely sensitive to the nature and distribution of its polar residues. These results suggest that Plin4 forms stable arrangements of adjacent AHs via polar/electrostatic interactions, reminiscent of the organization of apolipoproteins in lipoprotein particles, thus pointing to a general mechanism of AH stabilization via lateral interactions.
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Affiliation(s)
- Manuel Giménez-Andrés
- Institut Jacques Monod, CNRS, Université de Paris, Paris, France.,Université Paris-Saclay, Saint-Aubin, France
| | - Tadej Emeršič
- Institute of Biophysics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | | | - Juan Martin D'Ambrosio
- Institut Jacques Monod, CNRS, Université de Paris, Paris, France.,CRBM, University of Montpellier and CNRS, Montpellier, France
| | - Bruno Antonny
- Université Côte d'Azur, CNRS, IPMC, Valbonne, France
| | - Jure Derganc
- Institute of Biophysics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.,Chair of Microprocess Engineering and Technology - COMPETE, University of Ljubljana, Ljubljana, Slovenia
| | - Alenka Čopič
- Institut Jacques Monod, CNRS, Université de Paris, Paris, France.,CRBM, University of Montpellier and CNRS, Montpellier, France
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41
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Abstract
Eukaryotic cells are complicated factories that need ensure productivity and functionality on the cellular level as well as being able to communicate with their environment. In order to do so cells developed intracellular communication systems. For a long time, research focused mainly on the secretory/biosynthetic and endocytic routes for communication, leaving the communication with other organelles apart. In the last decade, this view has changed dramatically and a more holistic view of intracellular communication is emerging. We are still at the tip of the iceberg, but a common theme of touching, kissing, fusing is emerging as general principles of communication.
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Affiliation(s)
- Anne Spang
- Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland
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42
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Fan L, Shi C, Hu X, Zhang Z, Zheng H, Luo H, Fan Y, Zhang S, Hu Z, Yang J, Mao C, Xu Y. Analysis of 12 GWAS-Linked Loci With Parkinson's Disease in the Chinese Han Population. Front Neurol 2021; 12:623913. [PMID: 33897588 PMCID: PMC8058430 DOI: 10.3389/fneur.2021.623913] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 03/04/2021] [Indexed: 11/13/2022] Open
Abstract
A recent large-scale European-originated genome-wide association study identified 38 novel independent risk signals in 37 loci for Parkinson's disease (PD). However, whether these new loci are associated with PD in Asian populations remains elusive. The present study aimed to explore the relationship between the 12 most relevant loci with larger absolute values for these new risk loci and PD in the Chinese Han population. We performed a case-control study including 527 PD patients and 435 healthy controls. In the allele model, it was found that rs10748818/GBF1 was associated with PD in the Chinese Han population [p = 0.035, odds ratio (OR) 1.221, 95% confidence interval (CI) 1.014–1.472
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Affiliation(s)
- Liyuan Fan
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China.,The Academy of Medical Sciences of Zhengzhou University, Zhengzhou University, Zhengzhou, China.,Henan Key Laboratory of Cerebrovascular Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China
| | - Changhe Shi
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China.,Henan Key Laboratory of Cerebrovascular Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China.,Institute of Neuroscience, Zhengzhou University, Zhengzhou, China
| | - Xinchao Hu
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China.,The Academy of Medical Sciences of Zhengzhou University, Zhengzhou University, Zhengzhou, China.,Henan Key Laboratory of Cerebrovascular Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China
| | - Zhongxian Zhang
- The Academy of Medical Sciences of Zhengzhou University, Zhengzhou University, Zhengzhou, China.,Sino-British Research Centre for Molecular Oncology, National Centre for International Research in Cell and Gene Therapy, School of Basic Medical Sciences, Academy of Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Huimin Zheng
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China.,The Academy of Medical Sciences of Zhengzhou University, Zhengzhou University, Zhengzhou, China.,Henan Key Laboratory of Cerebrovascular Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China
| | - Haiyang Luo
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China.,The Academy of Medical Sciences of Zhengzhou University, Zhengzhou University, Zhengzhou, China.,Henan Key Laboratory of Cerebrovascular Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China
| | - Yu Fan
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China.,The Academy of Medical Sciences of Zhengzhou University, Zhengzhou University, Zhengzhou, China.,Henan Key Laboratory of Cerebrovascular Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China
| | - Shuo Zhang
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China.,The Academy of Medical Sciences of Zhengzhou University, Zhengzhou University, Zhengzhou, China.,Henan Key Laboratory of Cerebrovascular Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China
| | - Zhengwei Hu
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China.,The Academy of Medical Sciences of Zhengzhou University, Zhengzhou University, Zhengzhou, China
| | - Jing Yang
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China.,Henan Key Laboratory of Cerebrovascular Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China
| | - Chengyuan Mao
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China.,The Academy of Medical Sciences of Zhengzhou University, Zhengzhou University, Zhengzhou, China.,Henan Key Laboratory of Cerebrovascular Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China.,Sino-British Research Centre for Molecular Oncology, National Centre for International Research in Cell and Gene Therapy, School of Basic Medical Sciences, Academy of Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Yuming Xu
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China.,Henan Key Laboratory of Cerebrovascular Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China.,Institute of Neuroscience, Zhengzhou University, Zhengzhou, China
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43
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Jackson T, Belsham GJ. Picornaviruses: A View from 3A. Viruses 2021; 13:v13030456. [PMID: 33799649 PMCID: PMC7999760 DOI: 10.3390/v13030456] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 03/08/2021] [Accepted: 03/09/2021] [Indexed: 12/14/2022] Open
Abstract
Picornaviruses are comprised of a positive-sense RNA genome surrounded by a protein shell (or capsid). They are ubiquitous in vertebrates and cause a wide range of important human and animal diseases. The genome encodes a single large polyprotein that is processed to structural (capsid) and non-structural proteins. The non-structural proteins have key functions within the viral replication complex. Some, such as 3Dpol (the RNA dependent RNA polymerase) have conserved functions and participate directly in replicating the viral genome, whereas others, such as 3A, have accessory roles. The 3A proteins are highly divergent across the Picornaviridae and have specific roles both within and outside of the replication complex, which differ between the different genera. These roles include subverting host proteins to generate replication organelles and inhibition of cellular functions (such as protein secretion) to influence virus replication efficiency and the host response to infection. In addition, 3A proteins are associated with the determination of host range. However, recent observations have challenged some of the roles assigned to 3A and suggest that other viral proteins may carry them out. In this review, we revisit the roles of 3A in the picornavirus life cycle. The 3AB precursor and mature 3A have distinct functions during viral replication and, therefore, we have also included discussion of some of the roles assigned to 3AB.
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Affiliation(s)
- Terry Jackson
- The Pirbright Institute, Pirbright, Woking, Surrey GU24 0NF, UK;
| | - Graham J. Belsham
- Department of Veterinary and Animal Sciences, University of Copenhagen, 1870 Frederiksberg, Denmark
- Correspondence:
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Interactions of Lipid Droplets with the Intracellular Transport Machinery. Int J Mol Sci 2021; 22:ijms22052776. [PMID: 33803444 PMCID: PMC7967230 DOI: 10.3390/ijms22052776] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 02/27/2021] [Accepted: 02/27/2021] [Indexed: 12/16/2022] Open
Abstract
Historically, studies of intracellular membrane trafficking have focused on the secretory and endocytic pathways and their major organelles. However, these pathways are also directly implicated in the biogenesis and function of other important intracellular organelles, the best studied of which are peroxisomes and lipid droplets. There is a large recent body of work on these organelles, which have resulted in the introduction of new paradigms regarding the roles of membrane trafficking organelles. In this review, we discuss the roles of membrane trafficking in the life cycle of lipid droplets. This includes the complementary roles of lipid phase separation and proteins in the biogenesis of lipid droplets from endoplasmic reticulum (ER) membranes, and the attachment of mature lipid droplets to membranes by lipidic bridges and by more conventional protein tethers. We also discuss the catabolism of neutral lipids, which in part results from the interaction of lipid droplets with cytosolic molecules, but with important roles for both macroautophagy and microautophagy. Finally, we address their eventual demise, which involves interactions with the autophagocytotic machinery. We pay particular attention to the roles of small GTPases, particularly Rab18, in these processes.
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45
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Veerabagu M, Rinne PLH, Skaugen M, Paul LK, van der Schoot C. Lipid Body Dynamics in Shoot Meristems: Production, Enlargement, and Putative Organellar Interactions and Plasmodesmal Targeting. FRONTIERS IN PLANT SCIENCE 2021; 12:674031. [PMID: 34367200 PMCID: PMC8335594 DOI: 10.3389/fpls.2021.674031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 06/14/2021] [Indexed: 05/20/2023]
Abstract
Post-embryonic cells contain minute lipid bodies (LBs) that are transient, mobile, engage in organellar interactions, and target plasmodesmata (PD). While LBs can deliver γ-clade 1,3-β-glucanases to PD, the nature of other cargo is elusive. To gain insight into the poorly understood role of LBs in meristems, we investigated their dynamics by microscopy, gene expression analyzes, and proteomics. In developing buds, meristems accumulated LBs, upregulated several LB-specific OLEOSIN genes and produced OLEOSINs. During bud maturation, the major gene OLE6 was strongly downregulated, OLEOSINs disappeared from bud extracts, whereas lipid biosynthesis genes were upregulated, and LBs were enlarged. Proteomic analyses of the LB fraction of dormant buds confirmed that OLEOSINs were no longer present. Instead, we identified the LB-associated proteins CALEOSIN (CLO1), Oil Body Lipase 1 (OBL1), Lipid Droplet Interacting Protein (LDIP), Lipid Droplet Associated Protein1a/b (LDAP1a/b) and LDAP3a/b, and crucial components of the OLEOSIN-deubiquitinating and degradation machinery, such as PUX10 and CDC48A. All mRFP-tagged LDAPs localized to LBs when transiently expressed in Nicotiana benthamiana. Together with gene expression analyzes, this suggests that during bud maturation, OLEOSINs were replaced by LDIP/LDAPs at enlarging LBs. The LB fraction contained the meristem-related actin7 (ACT7), "myosin XI tail-binding" RAB GTPase C2A, an LB/PD-associated γ-clade 1,3-β-glucanase, and various organelle- and/or PD-localized proteins. The results are congruent with a model in which LBs, motorized by myosin XI-k/1/2, traffic on F-actin, transiently interact with other organelles, and deliver a diverse cargo to PD.
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Affiliation(s)
- Manikandan Veerabagu
- Faculty of Biosciences, Department of Plant Sciences, Norwegian University of Life Sciences, Ås, Norway
| | - Päivi L. H. Rinne
- Faculty of Biosciences, Department of Plant Sciences, Norwegian University of Life Sciences, Ås, Norway
| | - Morten Skaugen
- Faculty of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Laju K. Paul
- Faculty of Biosciences, Department of Plant Sciences, Norwegian University of Life Sciences, Ås, Norway
| | - Christiaan van der Schoot
- Faculty of Biosciences, Department of Plant Sciences, Norwegian University of Life Sciences, Ås, Norway
- *Correspondence: Christiaan van der Schoot
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46
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Deregulation of Lipid Homeostasis: A Fa(c)t in the Development of Metabolic Diseases. Cells 2020; 9:cells9122605. [PMID: 33291746 PMCID: PMC7761975 DOI: 10.3390/cells9122605] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 12/01/2020] [Accepted: 12/02/2020] [Indexed: 02/06/2023] Open
Abstract
Lipids are important molecules for human health. The quantity and quality of fats consumed in the diet have important effects on the modulation of both the natural biosynthesis and degradation of lipids. There is an important number of lipid-failed associated metabolic diseases and an increasing number of studies suggesting that certain types of lipids might be beneficial to the treatment of many metabolic diseases. The aim of the present work is to expose an overview of de novo biosynthesis, storage, and degradation of lipids in mammalian cells, as well as, to review the published data describing the beneficial effects of these processes and the potential of some dietary lipids to improve metabolic diseases.
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47
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Leyland B, Zarka A, Didi-Cohen S, Boussiba S, Khozin-Goldberg I. High Resolution Proteome of Lipid Droplets Isolated from the Pennate Diatom Phaeodactylum tricornutum (Bacillariophyceae) Strain pt4 provides mechanistic insights into complex intracellular coordination during nitrogen deprivation. JOURNAL OF PHYCOLOGY 2020; 56:1642-1663. [PMID: 32779202 DOI: 10.1111/jpy.13063] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 05/14/2020] [Accepted: 07/12/2020] [Indexed: 05/08/2023]
Abstract
Lipid droplets (LDs) are an organelle conserved amongst all eukaryotes, consisting of a neutral lipid core surrounded by a polar lipid monolayer. Many species of microalgae accumulate LDs in response to stress conditions, such as nitrogen starvation. Here, we report the isolation and proteomic profiling of LD proteins from the model oleaginous pennate diatom Phaeodactylum tricornutum, strain Pt4 (UTEX 646). We also provide a quantitative description of LD morphological ontogeny, and fatty acid content. Novel cell disruption and LD isolation methods, combined with suspension-trapping and nanoflow liquid chromatography coupled to high resolution mass spectrometry, yielded an unprecedented number of LD proteins. Predictive annotation of the LD proteome suggests a broad assemblage of proteins with diverse functions, including lipid metabolism and vesicle trafficking, as well as ribosomal and proteasomal machinery. These proteins provide mechanistic insights into LD processes, and evidence for interactions between LDs and other organelles. We identify for the first time several key steps in diatom LD-associated triacylglycerol biosynthesis. Bioinformatic analyses of the LD proteome suggests multiple protein targeting mechanisms, including amphipathic helices, post-translational modifications, and translocation machinery. This work corroborates recent findings from other strains of P. tricornutum, other diatoms, and other eukaryotic organisms, suggesting that the fundamental proteins orchestrating LDs are conserved, and represent an ancient component of the eukaryotic endomembrane system. We postulate a comprehensive model of nitrogen starvation-induced diatom LDs on a molecular scale, and provide a wealth of candidates for metabolic engineering, with the potential to eventually customize LD contents.
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Affiliation(s)
- Ben Leyland
- The Microalgal Biotechnology Laboratory, The French Associates Institute for Agriculture and Biotechnology, Jacob Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Sede Boker Campus, Be'er Sheva, 84990, Israel
| | - Aliza Zarka
- The Microalgal Biotechnology Laboratory, The French Associates Institute for Agriculture and Biotechnology, Jacob Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Sede Boker Campus, Be'er Sheva, 84990, Israel
| | - Shoshana Didi-Cohen
- The Microalgal Biotechnology Laboratory, The French Associates Institute for Agriculture and Biotechnology, Jacob Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Sede Boker Campus, Be'er Sheva, 84990, Israel
| | - Sammy Boussiba
- The Microalgal Biotechnology Laboratory, The French Associates Institute for Agriculture and Biotechnology, Jacob Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Sede Boker Campus, Be'er Sheva, 84990, Israel
| | - Inna Khozin-Goldberg
- The Microalgal Biotechnology Laboratory, The French Associates Institute for Agriculture and Biotechnology, Jacob Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Sede Boker Campus, Be'er Sheva, 84990, Israel
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48
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Cross-Kingdom Activation of Vibrio Toxins by ADP-Ribosylation Factor Family GTPases. J Bacteriol 2020; 202:JB.00278-20. [PMID: 32900828 DOI: 10.1128/jb.00278-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pathogenic Vibrio species use many different approaches to subvert, attack, and undermine the host response. The toxins they produce are often responsible for the devastating effects associated with their diseases. These toxins target a variety of host proteins, which leads to deleterious effects, including dissolution of cell organelle integrity and inhibition of protein secretion. Becoming increasingly prevalent as cofactors for Vibrio toxins are proteins of the small GTPase families. ADP-ribosylation factor small GTPases (ARFs) in particular are emerging as a common host cofactor necessary for full activation of Vibrio toxins. While ARFs are not the direct target of Vibrio cholerae cholera toxin (CT), ARF binding is required for its optimal activity as an ADP-ribosyltransferase. The makes caterpillars floppy (MCF)-like and the domain X (DmX) effectors of the Vibrio vulnificus multifunctional autoprocessing repeats-in-toxin (MARTX) toxin also both require ARFs to initiate autoprocessing and activation as independent effectors. ARFs are ubiquitously expressed in eukaryotes and are key regulators of many cellular processes, and as such they are ideal cofactors for Vibrio pathogens that infect many host species. In this review, we cover in detail the known Vibrio toxins that use ARFs as cross-kingdom activators to both stimulate and optimize their activity. We further discuss how these contrast to toxins and effectors from other bacterial species that coactivate, stimulate, or directly modify host ARFs as their mechanisms of action.
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49
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Navare AT, Mast FD, Olivier JP, Bertomeu T, Neal M, Carpp LN, Kaushansky A, Coulombe-Huntington J, Tyers M, Aitchison JD. Viral protein engagement of GBF1 induces host cell vulnerability through synthetic lethality. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2020; 221:2020.10.12.336487. [PMID: 33173868 PMCID: PMC7654857 DOI: 10.1101/2020.10.12.336487] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Viruses co-opt host proteins to carry out their lifecycle. Repurposed host proteins may thus become functionally compromised; a situation analogous to a loss-of-function mutation. We term such host proteins viral-induced hypomorphs. Cells bearing cancer driver loss-of-function mutations have successfully been targeted with drugs perturbing proteins encoded by the synthetic lethal partners of cancer-specific mutations. Synthetic lethal interactions of viral-induced hypomorphs have the potential to be similarly targeted for the development of host-based antiviral therapeutics. Here, we use GBF1, which supports the infection of many RNA viruses, as a proof-of-concept. GBF1 becomes a hypomorph upon interaction with the poliovirus protein 3A. Screening for synthetic lethal partners of GBF1 revealed ARF1 as the top hit, disruption of which, selectively killed cells that synthesize poliovirus 3A. Thus, viral protein interactions can induce hypomorphs that render host cells vulnerable to perturbations that leave uninfected cells intact. Exploiting viral-induced vulnerabilities could lead to broad-spectrum antivirals for many viruses, including SARS-CoV-2. SUMMARY Using a viral-induced hypomorph of GBF1, Navare et al., demonstrate that the principle of synthetic lethality is a mechanism to selectively kill virus-infected cells.
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Affiliation(s)
- Arti T Navare
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, USA
| | - Fred D Mast
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, USA
| | - Jean Paul Olivier
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, USA
| | - Thierry Bertomeu
- Institute for Research in Immunology and Cancer, Université de Montréal, Montreal, Quebec, Canada
| | - Maxwell Neal
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, USA
| | - Lindsay N Carpp
- Center for Infectious Disease Research, Seattle, Washington, USA
| | - Alexis Kaushansky
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, USA
- Department of Pediatrics, University of Washington, Seattle, Washington, USA
| | | | - Mike Tyers
- Institute for Research in Immunology and Cancer, Université de Montréal, Montreal, Quebec, Canada
| | - John D Aitchison
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, USA
- Department of Pediatrics, University of Washington, Seattle, Washington, USA
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
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50
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Martínez JL, Arias CF. Role of the Guanine Nucleotide Exchange Factor GBF1 in the Replication of RNA Viruses. Viruses 2020; 12:E682. [PMID: 32599855 PMCID: PMC7354614 DOI: 10.3390/v12060682] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 04/06/2020] [Accepted: 04/06/2020] [Indexed: 12/12/2022] Open
Abstract
The guanine nucleotide exchange factor GBF1 is a well-known factor that can activate different ADP-ribosylation factor (Arf) proteins during the regulation of different cellular vesicular transport processes. In the last decade, it has become increasingly evident that GBF1 can also regulate different steps of the replication cycle of RNA viruses belonging to different virus families. GBF1 has been shown not only to facilitate the intracellular traffic of different viral and cellular elements during infection, but also to modulate the replication of viral RNA, the formation and maturation of viral replication complexes, and the processing of viral proteins through mechanisms that do not depend on its canonical role in intracellular transport. Here, we review the various roles that GBF1 plays during the replication of different RNA viruses.
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Affiliation(s)
| | - Carlos F. Arias
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 4510, Morelos, Mexico;
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