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Borodavka A, Acker J. Seeing Biomolecular Condensates Through the Lens of Viruses. Annu Rev Virol 2023; 10:163-182. [PMID: 37040799 DOI: 10.1146/annurev-virology-111821-103226] [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: 04/13/2023]
Abstract
Phase separation of viral biopolymers is a key factor in the formation of cytoplasmic viral inclusions, known as sites of virus replication and assembly. This review describes the mechanisms and factors that affect phase separation in viral replication and identifies potential areas for future research. Drawing inspiration from studies on cellular RNA-rich condensates, we compare the hierarchical coassembly of ribosomal RNAs and proteins in the nucleolus to the coordinated coassembly of viral RNAs and proteins taking place within viral factories in viruses containing segmented RNA genomes. We highlight the common characteristics of biomolecular condensates in viral replication and how this new understanding is reshaping our views of virus assembly mechanisms. Such studies have the potential to uncover unexplored antiviral strategies targeting these phase-separated states.
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Affiliation(s)
- Alexander Borodavka
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom;
| | - Julia Acker
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom;
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2
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Qu Y, Wang W, Xiao MZX, Zheng Y, Liang Q. The interplay between lipid droplets and virus infection. J Med Virol 2023; 95:e28967. [PMID: 37496184 DOI: 10.1002/jmv.28967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 07/06/2023] [Accepted: 07/07/2023] [Indexed: 07/28/2023]
Abstract
As an intracellular parasite, the virus usurps cellular machinery and modulates cellular metabolism pathways to replicate itself in cells. Lipid droplets (LDs) are universally conserved energy storage organelles that not only play vital roles in maintaining lipid homeostasis but are also involved in viral replication. Increasing evidence has demonstrated that viruses take advantage of cellular lipid metabolism by targeting the biogenesis, hydrolysis, and lipophagy of LD during viral infection. In this review, we summarize the current knowledge about the modulation of cellular LD by different viruses, with a special emphasis on the Hepatitis C virus, Dengue virus, and SARS-CoV-2.
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Affiliation(s)
- Yafei Qu
- Center for Immune-Related Diseases at Shanghai Institute of Immunology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Weili Wang
- Center for Immune-Related Diseases at Shanghai Institute of Immunology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Maggie Z X Xiao
- Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Yuejuan Zheng
- The Research Center for Traditional Chinese Medicine, Shanghai Institute of Infectious Disease and Biosecurity, Shanghai University of Traditional Medicine, Shanghai, China
- Center for Traditional Chinese Medicine and Immunology Research, School of Basic Medical Sciences, Shanghai University of Traditional Medicine, Shanghai, China
| | - Qiming Liang
- Center for Immune-Related Diseases at Shanghai Institute of Immunology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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3
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Hammoudeh N, Soukkarieh C, Murphy DJ, Hanano A. Mammalian lipid droplets: structural, pathological, immunological and anti-toxicological roles. Prog Lipid Res 2023; 91:101233. [PMID: 37156444 DOI: 10.1016/j.plipres.2023.101233] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 04/30/2023] [Accepted: 05/05/2023] [Indexed: 05/10/2023]
Abstract
Mammalian lipid droplets (LDs) are specialized cytosolic organelles consisting of a neutral lipid core surrounded by a membrane made up of a phospholipid monolayer and a specific population of proteins that varies according to the location and function of each LD. Over the past decade, there have been significant advances in the understanding of LD biogenesis and functions. LDs are now recognized as dynamic organelles that participate in many aspects of cellular homeostasis plus other vital functions. LD biogenesis is a complex, highly-regulated process with assembly occurring on the endoplasmic reticulum although aspects of the underpinning molecular mechanisms remain elusive. For example, it is unclear how many enzymes participate in the biosynthesis of the neutral lipid components of LDs and how this process is coordinated in response to different metabolic cues to promote or suppress LD formation and turnover. In addition to enzymes involved in the biosynthesis of neutral lipids, various scaffolding proteins play roles in coordinating LD formation. Despite their lack of ultrastructural diversity, LDs in different mammalian cell types are involved in a wide range of biological functions. These include roles in membrane homeostasis, regulation of hypoxia, neoplastic inflammatory responses, cellular oxidative status, lipid peroxidation, and protection against potentially toxic intracellular fatty acids and lipophilic xenobiotics. Herein, the roles of mammalian LDs and their associated proteins are reviewed with a particular focus on their roles in pathological, immunological and anti-toxicological processes.
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Affiliation(s)
- Nour Hammoudeh
- Department of Animal Biology, Faculty of Sciences, University of Damascus, Damascus, Syria
| | - Chadi Soukkarieh
- Department of Animal Biology, Faculty of Sciences, University of Damascus, Damascus, Syria
| | - Denis J Murphy
- School of Applied Sciences, University of South Wales, Pontypridd, CF37 1DL, Wales, United Kingdom..
| | - Abdulsamie Hanano
- Department of Molecular Biology and Biotechnology, Atomic Energy Commission of Syria (AECS), P.O. Box 6091, Damascus, Syria..
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4
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Clark SA, Vazquez A, Furiya K, Splattstoesser MK, Bashmail AK, Schwartz H, Russell M, Bhark SJ, Moreno OK, McGovern M, Owsley ER, Nelson TA, Sanchez EL, Delgado T. Rewiring of the Host Cell Metabolome and Lipidome during Lytic Gammaherpesvirus Infection Is Essential for Infectious-Virus Production. J Virol 2023; 97:e0050623. [PMID: 37191529 PMCID: PMC10308918 DOI: 10.1128/jvi.00506-23] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 04/20/2023] [Indexed: 05/17/2023] Open
Abstract
Oncogenic virus infections are estimated to cause ~15% of all cancers. Two prevalent human oncogenic viruses are members of the gammaherpesvirus family: Epstein-Barr virus (EBV) and Kaposi's sarcoma herpesvirus (KSHV). We use murine herpesvirus 68 (MHV-68), which shares significant homology with KSHV and EBV, as a model system to study gammaherpesvirus lytic replication. Viruses implement distinct metabolic programs to support their life cycle, such as increasing the supply of lipids, amino acids, and nucleotide materials necessary to replicate. Our data define the global changes in the host cell metabolome and lipidome during gammaherpesvirus lytic replication. Our metabolomics analysis found that MHV-68 lytic infection induces glycolysis, glutaminolysis, lipid metabolism, and nucleotide metabolism. We additionally observed an increase in glutamine consumption and glutamine dehydrogenase protein expression. While both glucose and glutamine starvation of host cells decreased viral titers, glutamine starvation led to a greater loss in virion production. Our lipidomics analysis revealed a peak in triacylglycerides early during infection and an increase in free fatty acids and diacylglyceride later in the viral life cycle. Furthermore, we observed an increase in the protein expression of multiple lipogenic enzymes during infection. Interestingly, pharmacological inhibitors of glycolysis or lipogenesis resulted in decreased infectious virus production. Taken together, these results illustrate the global alterations in host cell metabolism during lytic gammaherpesvirus infection, establish essential pathways for viral production, and recommend targeted mechanisms to block viral spread and treat viral induced tumors. IMPORTANCE Viruses are intracellular parasites which lack their own metabolism, so they must hijack host cell metabolic machinery in order to increase the production of energy, proteins, fats, and genetic material necessary to replicate. Using murine herpesvirus 68 (MHV-68) as a model system to understand how similar human gammaherpesviruses cause cancer, we profiled the metabolic changes that occur during lytic MHV-68 infection and replication. We found that MHV-68 infection of host cells increases glucose, glutamine, lipid, and nucleotide metabolic pathways. We also showed inhibition or starvation of glucose, glutamine, or lipid metabolic pathways results in an inhibition of virus production. Ultimately, targeting changes in host cell metabolism due to viral infection can be used to treat gammaherpesvirus-induced cancers and infections in humans.
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Affiliation(s)
- Sarah A. Clark
- Northwest University, Department of Biology, Kirkland, Washington, USA
| | - Angie Vazquez
- Seattle Pacific University, Department of Biology, Seattle, Washington, USA
| | - Kelsey Furiya
- Seattle Pacific University, Department of Biology, Seattle, Washington, USA
| | | | | | - Haleigh Schwartz
- Northwest University, Department of Biology, Kirkland, Washington, USA
| | - Makaiya Russell
- Seattle Pacific University, Department of Biology, Seattle, Washington, USA
| | - Shun-Je Bhark
- Seattle Pacific University, Department of Biology, Seattle, Washington, USA
| | - Osvaldo K. Moreno
- San Francisco State University, Department of Biology, San Francisco, California, USA
| | - Morgan McGovern
- Seattle Pacific University, Department of Biology, Seattle, Washington, USA
| | - Eric R. Owsley
- Seattle Pacific University, Department of Biology, Seattle, Washington, USA
| | - Timothy A. Nelson
- Seattle Pacific University, Department of Biology, Seattle, Washington, USA
| | - Erica L. Sanchez
- San Francisco State University, Department of Biology, San Francisco, California, USA
- University of Texas at Dallas, Department of Biological Sciences, Richardson, Texas, USA
| | - Tracie Delgado
- Seattle Pacific University, Department of Biology, Seattle, Washington, USA
- Northwest University, Department of Biology, Kirkland, Washington, USA
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5
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Ng YS, Cheng CS, Ando M, Tseng YT, He ST, Li CY, Cheng SW, Chen YM, Kumar R, Liu CH, Takeyama H, Hirono I, Wang HC. White spot syndrome virus (WSSV) modulates lipid metabolism in white shrimp. Commun Biol 2023; 6:546. [PMID: 37210461 PMCID: PMC10199447 DOI: 10.1038/s42003-023-04924-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 05/08/2023] [Indexed: 05/22/2023] Open
Abstract
In addition to the Warburg effect, which increases the availability of energy and biosynthetic building blocks in WSSV-infected shrimp, WSSV also induces both lipolysis at the viral genome replication stage (12 hpi) to provide material and energy for the virus replication, and lipogenesis at the viral late stage (24 hpi) to complete virus morphogenesis by supplying particular species of long-chain fatty acids (LCFAs). Here, we further show that WSSV causes a reduction in lipid droplets (LDs) in hemocytes at the viral genome replication stage, and an increase in LDs in the nuclei of WSSV-infected hemocytes at the viral late stage. In the hepatopancreas, lipolysis is triggered by WSSV infection, and this leads to fatty acids being released into the hemolymph. β-oxidation inhibition experiment reveals that the fatty acids generated by WSSV-induced lipolysis can be diverted into β-oxidation for energy production. At the viral late stage, WSSV infection leads to lipogenesis in both the stomach and hepatopancreas, suggesting that fatty acids are in high demand at this stage for virion morphogenesis. Our results demonstrate that WSSV modulates lipid metabolism specifically at different stages to facilitate its replication.
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Affiliation(s)
- Yen Siong Ng
- Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan
| | - Cheng-Shun Cheng
- Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan
| | - Masahiro Ando
- Research Organization for Nano and Life Innovations, Waseda University, Tokyo, Japan
| | - Yi-Ting Tseng
- Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan
| | - Shu-Ting He
- Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan
| | - Chun-Yuan Li
- Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan
| | - Shu-Wen Cheng
- Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan
| | - Yi-Min Chen
- Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan
| | - Ramya Kumar
- Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan
- International Center for the Scientific Development of Shrimp Aquaculture, National Cheng Kung University, Tainan, Taiwan
| | - Chun-Hung Liu
- Department of Aquaculture, National Pingtung University of Science and Technology, Pingtung, Taiwan
| | - Haruko Takeyama
- Research Organization for Nano and Life Innovations, Waseda University, Tokyo, Japan
- Department of Life Science and Medical Bioscience, Waseda University, Tokyo, Japan
- Computational Bio Big-Data Open Innovation Laboratory (CBBD-OIL), National Institute of Advanced Industrial Science and Technology, Tokyo, Japan
- Institute for Advanced Research of Biosystem Dynamics, Waseda Research Institute for Science and Engineering, Tokyo, Japan
| | - Ikuo Hirono
- Department of Marine Biosciences, Tokyo University of Marine Science and Technology, Tokyo, Japan
| | - Han-Ching Wang
- Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan.
- International Center for the Scientific Development of Shrimp Aquaculture, National Cheng Kung University, Tainan, Taiwan.
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6
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Chen G, Harwood JL, Lemieux MJ, Stone SJ, Weselake RJ. Acyl-CoA:diacylglycerol acyltransferase: Properties, physiological roles, metabolic engineering and intentional control. Prog Lipid Res 2022; 88:101181. [PMID: 35820474 DOI: 10.1016/j.plipres.2022.101181] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 05/31/2022] [Accepted: 07/04/2022] [Indexed: 12/15/2022]
Abstract
Acyl-CoA:diacylglycerol acyltransferase (DGAT, EC 2.3.1.20) catalyzes the last reaction in the acyl-CoA-dependent biosynthesis of triacylglycerol (TAG). DGAT activity resides mainly in membrane-bound DGAT1 and DGAT2 in eukaryotes and bifunctional wax ester synthase-diacylglycerol acyltransferase (WSD) in bacteria, which are all membrane-bound proteins but exhibit no sequence homology to each other. Recent studies also identified other DGAT enzymes such as the soluble DGAT3 and diacylglycerol acetyltransferase (EaDAcT), as well as enzymes with DGAT activities including defective in cuticular ridges (DCR) and steryl and phytyl ester synthases (PESs). This review comprehensively discusses research advances on DGATs in prokaryotes and eukaryotes with a focus on their biochemical properties, physiological roles, and biotechnological and therapeutic applications. The review begins with a discussion of DGAT assay methods, followed by a systematic discussion of TAG biosynthesis and the properties and physiological role of DGATs. Thereafter, the review discusses the three-dimensional structure and insights into mechanism of action of human DGAT1, and the modeled DGAT1 from Brassica napus. The review then examines metabolic engineering strategies involving manipulation of DGAT, followed by a discussion of its therapeutic applications. DGAT in relation to improvement of livestock traits is also discussed along with DGATs in various other eukaryotic organisms.
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Affiliation(s)
- Guanqun Chen
- Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta T6H 2P5, Canada.
| | - John L Harwood
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, UK
| | - M Joanne Lemieux
- Department of Biochemistry, University of Alberta, Membrane Protein Disease Research Group, Edmonton T6G 2H7, Canada
| | - Scot J Stone
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada.
| | - Randall J Weselake
- Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta T6H 2P5, Canada
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7
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Monette A, Niu M, Chen L, Rao S, Gorelick RJ, Mouland AJ. Pan-retroviral Nucleocapsid-Mediated Phase Separation Regulates Genomic RNA Positioning and Trafficking. Cell Rep 2020; 31:107520. [PMID: 32320662 PMCID: PMC8965748 DOI: 10.1016/j.celrep.2020.03.084] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 02/12/2020] [Accepted: 03/24/2020] [Indexed: 02/07/2023] Open
Abstract
The duality of liquid-liquid phase separation (LLPS) of cellular components into membraneless organelles defines the nucleation of both normal and disease processes including stress granule (SG) assembly. From mounting evidence of LLPS utility by viruses, we discover that HIV-1 nucleocapsid (NC) protein condenses into zinc-finger (ZnF)-dependent LLPSs that are dynamically influenced by cytosolic factors. ZnF-dependent and Zinc (Zn2+)-chelation-sensitive NC-LLPS are formed in live cells. NC-Zn2+ ejection reverses the HIV-1 blockade on SG assembly, inhibits NC-SG assembly, disrupts NC/Gag-genomic RNA (vRNA) ribonucleoprotein complexes, and causes nuclear sequestration of NC and the vRNA, inhibiting Gag expression and virus release. NC ZnF mutagenesis eliminates the HIV-1 blockade of SG assembly and repositions vRNA to SGs. We find that NC-mediated, Zn2+-coordinated phase separation is conserved among diverse retrovirus subfamilies, illustrating that this exquisitely evolved Zn2+-dependent feature of virus replication represents a critical target for pan-antiretroviral therapies. Monette et al. discover a high degree of conservation of zinc-finger embedded, intrinsically disordered prion-like domains across retrovirus Gag proteins. These domains within the Gag Nucleocapsid regulate the formation of zinc-dependent liquid-liquid phase condensates and stress granules in HIV-1-expressing cells to induce repositioning of the viral genomic RNA.
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Affiliation(s)
- Anne Monette
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute at the Jewish General Hospital, Montréal, QC H3T 1E2, Canada.
| | - Meijuan Niu
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute at the Jewish General Hospital, Montréal, QC H3T 1E2, Canada
| | - Lois Chen
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute at the Jewish General Hospital, Montréal, QC H3T 1E2, Canada; Department of Microbiology and Immunology, McGill University, Montréal, QC H3A 2B4, Canada
| | - Shringar Rao
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute at the Jewish General Hospital, Montréal, QC H3T 1E2, Canada; Department of Biochemistry, Erasmus University Medical Center, Ee634, PO Box 2040, 3000CA Rotterdam, the Netherlands
| | - Robert James Gorelick
- AIDS and Cancer Virus Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21701, USA
| | - Andrew John Mouland
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute at the Jewish General Hospital, Montréal, QC H3T 1E2, Canada; Department of Microbiology and Immunology, McGill University, Montréal, QC H3A 2B4, Canada; Department of Medicine, McGill University, Montréal, QC H3G 2M1, Canada.
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8
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Glingston RS, Deb R, Kumar S, Nagotu S. Organelle dynamics and viral infections: at cross roads. Microbes Infect 2018; 21:20-32. [PMID: 29953921 PMCID: PMC7110583 DOI: 10.1016/j.micinf.2018.06.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 06/14/2018] [Accepted: 06/15/2018] [Indexed: 01/12/2023]
Abstract
Viruses are obligate intracellular parasites of the host cells. A commonly accepted view is the requirement of internal membranous structures for various aspects of viral life cycle. Organelles enable favourable intracellular environment for several viruses. However, studies reporting organelle dynamics upon viral infections are scant. In this review, we aim to summarize and highlight modulations caused to various organelles upon viral infection or expression of its proteins.
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Affiliation(s)
- R Sahaya Glingston
- Organelle Biology and Cellular Ageing Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Rachayeeta Deb
- Organelle Biology and Cellular Ageing Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Sachin Kumar
- Viral Immunology Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India.
| | - Shirisha Nagotu
- Organelle Biology and Cellular Ageing Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India.
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9
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Conti B, Porcu C, Viscomi C, Minutolo A, Costantini S, Corazzari M, Iannucci G, Barbaro B, Balsano C. Small heterodimer partner 1 directly interacts with NS5A viral protein and has a key role in HCV related liver cell transformation. Oncotarget 2018; 7:84575-84586. [PMID: 27661118 PMCID: PMC5356682 DOI: 10.18632/oncotarget.12144] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 08/20/2016] [Indexed: 12/14/2022] Open
Abstract
HCV life cycle is strictly correlated with the hepatocyte lipid metabolism; moreover, the progression of HCV chronic hepatitis is accelerated by the presence of liver steatosis. Among the steatogenic genes deregulated during the HCV infection one of the most attractive is the Small Heterodimer Protein 1 (SHP1; NR0B2), that is involved in a remarkable number of metabolic functions. HCV NS5A is an essential and integral component of the HCV membranous-web replicon complex (RC) and plays an essential role to transfer the viral genome from the RCs to the surface of the lipid droplets (LDs) that, in turn, play a key function during HCV life cycle. With the help of a HCV infection model, we demonstrate a functional interaction between SHP1 and HCV NS5A protein. SHP1 silencing (siSHP1) reversed the pro-oncogenic effects of HCV infection, inducing a significant decrease in liver lipid accumulation and in NS5A protein expression. Moreover, siSHP1 causes a strong modulation of some genes involved in HCV-related EMT, such as: HNF4, a central regulators of hepatocyte differentiation, E-Cadherin, SNAILs. Our data suggest that SHP1 results not only to be strictly connected to the pathogenesis of HCV-related liver steatosis, but also to its progression towards the liver transformation.
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Affiliation(s)
- Beatrice Conti
- Laboratory of Molecular Virology and Oncoloy, Francesco Balsano Foundation, ex A. Cesalpino Foundation, Rome, Italy
| | - Cristiana Porcu
- Institute of Biology and Molecular Pathology (IBPM) - CNR (National Research Council), Rome, Italy
| | - Carmela Viscomi
- Laboratory of Molecular Virology and Oncoloy, Francesco Balsano Foundation, ex A. Cesalpino Foundation, Rome, Italy
| | - Antonella Minutolo
- Laboratory of Molecular Virology and Oncoloy, Francesco Balsano Foundation, ex A. Cesalpino Foundation, Rome, Italy.,Department of Biology, University of Rome 'Tor Vergata', Rome, Italy
| | - Susan Costantini
- CROM, Istituto Nazionale Tumori "Fondazione G.Pascale", IRCSS, Napoli, Italy
| | - Marco Corazzari
- Department of Biology, University of Rome 'Tor Vergata', Rome, Italy
| | - Gino Iannucci
- Laboratory of Molecular Virology and Oncoloy, Francesco Balsano Foundation, ex A. Cesalpino Foundation, Rome, Italy
| | - Barbara Barbaro
- Institute of Biology and Molecular Pathology (IBPM) - CNR (National Research Council), Rome, Italy
| | - Clara Balsano
- Laboratory of Molecular Virology and Oncoloy, Francesco Balsano Foundation, ex A. Cesalpino Foundation, Rome, Italy.,Institute of Biology and Molecular Pathology (IBPM) - CNR (National Research Council), Rome, Italy
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10
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Remenyi R, Roberts GC, Zothner C, Merits A, Harris M. SNAP-tagged Chikungunya Virus Replicons Improve Visualisation of Non-Structural Protein 3 by Fluorescence Microscopy. Sci Rep 2017; 7:5682. [PMID: 28720784 PMCID: PMC5515888 DOI: 10.1038/s41598-017-05820-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 06/06/2017] [Indexed: 11/09/2022] Open
Abstract
Chikungunya virus (CHIKV), a mosquito-borne alphavirus, causes febrile disease, muscle and joint pain, which can become chronic in some individuals. The non-structural protein 3 (nsP3) plays essential roles during infection, but a complete understanding of its function is lacking. Here we used a microscopy-based approach to image CHIKV nsP3 inside human cells. The SNAP system consists of a self-labelling enzyme tag, which catalyses the covalent linking of exogenously supplemented synthetic ligands. Genetic insertion of this tag resulted in viable replicons and specific labelling while preserving the effect of nsP3 on stress granule responses and co-localisation with GTPase Activating Protein (SH3 domain) Binding Proteins (G3BPs). With sub-diffraction, three-dimensional, optical imaging, we visualised nsP3-positive structures with variable density and morphology, including high-density rod-like structures, large spherical granules, and small, low-density structures. Next, we confirmed the utility of the SNAP-tag for studying protein turnover by pulse-chase labelling. We also revealed an association of nsP3 with cellular lipid droplets and examined the spatial relationships between nsP3 and the non-structural protein 1 (nsP1). Together, our study provides a sensitive, specific, and versatile system for fundamental research into the individual functions of a viral non-structural protein during infection with a medically important arthropod-borne virus (arbovirus).
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Affiliation(s)
- Roland Remenyi
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, West Yorkshire, LS2 9JT, United Kingdom
| | - Grace C Roberts
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, West Yorkshire, LS2 9JT, United Kingdom
| | - Carsten Zothner
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, West Yorkshire, LS2 9JT, United Kingdom
| | - Andres Merits
- Institute of Technology, University of Tartu, Tartu, Estonia
| | - Mark Harris
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, West Yorkshire, LS2 9JT, United Kingdom.
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11
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Gluchowski NL, Becuwe M, Walther TC, Farese RV. Lipid droplets and liver disease: from basic biology to clinical implications. Nat Rev Gastroenterol Hepatol 2017; 14:343-355. [PMID: 28428634 PMCID: PMC6319657 DOI: 10.1038/nrgastro.2017.32] [Citation(s) in RCA: 366] [Impact Index Per Article: 52.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Lipid droplets are dynamic organelles that store neutral lipids during times of energy excess and serve as an energy reservoir during deprivation. Many prevalent metabolic diseases, such as the metabolic syndrome or obesity, often result in abnormal lipid accumulation in lipid droplets in the liver, also called hepatic steatosis. Obesity-related steatosis, or NAFLD in particular, is a major public health concern worldwide and is frequently associated with insulin resistance and type 2 diabetes mellitus. Here, we review the latest insights into the biology of lipid droplets and their role in maintaining lipid homeostasis in the liver. We also offer a perspective of liver diseases that feature lipid accumulation in these lipid storage organelles, which include NAFLD and viral hepatitis. Although clinical applications of this knowledge are just beginning, we highlight new opportunities for identifying molecular targets for treating hepatic steatosis and steatohepatitis.
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Affiliation(s)
- Nina L. Gluchowski
- Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, 655 Huntington Avenue, Boston, Massachusetts 02115, USA.,Boston Children’s Hospital Department of Gastroenterology, Hepatology and Nutrition, 300 Longwood Avenue Boston, Massachusetts 02115, USA
| | - Michel Becuwe
- Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, 655 Huntington Avenue, Boston, Massachusetts 02115, USA
| | - Tobias C. Walther
- Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, 655 Huntington Avenue, Boston, Massachusetts 02115, USA.,Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue Boston, Massachusetts 02115, USA.,Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur Boston, Massachusetts 02115, USA.,Howard Hughes Medical Institute, Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, 655 Huntington Avenue, Boston, Massachusetts 02115, USA
| | - Robert V. Farese
- Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, 655 Huntington Avenue, Boston, Massachusetts 02115, USA.,Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue Boston, Massachusetts 02115, USA.,Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur Boston, Massachusetts 02115, USA
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12
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Wei Q, Hu B, Xue Y, Mburu DK, Tao X, Su J. Effects of methimazole on Drosophila glucolipid metabolism in vitro and in vivo. Comp Biochem Physiol C Toxicol Pharmacol 2017; 196:54-60. [PMID: 28341216 DOI: 10.1016/j.cbpc.2017.03.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Revised: 03/12/2017] [Accepted: 03/19/2017] [Indexed: 12/17/2022]
Abstract
Methimazole (MMI) is an antithyroid agent widely used in the treatment of hyperthyroidism, and metabolized by cytochrome P450 enzymes and flavin-containing monooxygenases in mammals. However, drug overdose and the inadequate detoxification of the metabolite(s) are responsible for hepatocellular damage and organ dysfunction. Depending on the desired properties, Drosophila melanogaster has recently emerged as an ideal model organism for the study of human diseases. Here we investigated the changes in metabolic profiles and mRNA expressions related to glucolipid metabolism in response to treatment with MMI in Drosophila. Remarkable loss of lifespan occurred in fruit flies fed on the diets containing 10 or 30mM MMI compared to unsupplemented controls. To examine whether MMI affects glucolipid metabolism in vitro and in vivo, fruit flies were fed diets containing 30mM MMI for two weeks and Drosophila S2 cells were incubated with 300μM MMI for 48h. Measurements of metabolites showed that triglyceride content dramatically decreased (30.56% in vivo and 18.13% in vitro), and glycogen content significantly increased (10.7% in vivo and 126.8% in vitro). Quantitative analyses indicated that mRNA expression levels of Dmfmo1, s6k, dilp2, acc and dilp5 genes involved in metabolic homeostasis were remarkably down-regulated in vivo and in vitro. Meanwhile, the addition of MMI could significantly reduce the lipid droplet content in S2 cells by approximately 25% compared to control subjects. These data may provide a biological basis for the study of MMI on disease symptoms and complications, and discovery of therapeutic treatments.
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Affiliation(s)
- Qi Wei
- Department of Pesticide Sciences, College of Plant Protection, Nanjing Agricultural University, State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Nanjing, China
| | - Bo Hu
- Department of Pesticide Sciences, College of Plant Protection, Nanjing Agricultural University, State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Nanjing, China
| | - Yuan Xue
- Department of Pesticide Sciences, College of Plant Protection, Nanjing Agricultural University, State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Nanjing, China
| | - David Kibe Mburu
- Department of Pesticide Sciences, College of Plant Protection, Nanjing Agricultural University, State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Nanjing, China
| | - Xian Tao
- Department of Pesticide Sciences, College of Plant Protection, Nanjing Agricultural University, State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Nanjing, China
| | - Jianya Su
- Department of Pesticide Sciences, College of Plant Protection, Nanjing Agricultural University, State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Nanjing, China.
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13
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The size matters: regulation of lipid storage by lipid droplet dynamics. SCIENCE CHINA-LIFE SCIENCES 2016; 60:46-56. [PMID: 27981432 DOI: 10.1007/s11427-016-0322-x] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 10/28/2016] [Indexed: 12/14/2022]
Abstract
Adequate energy storage is essential for sustaining healthy life. Lipid droplet (LD) is the subcellular organelle that stores energy in the form of neutral lipids and releases fatty acids under energy deficient conditions. Energy storage capacity of LDs is primarily dependent on the sizes of LDs. Enlargement and growth of LDs is controlled by two molecular pathways: neutral lipid synthesis and atypical LD fusion. Shrinkage of LDs is mediated by the degradation of neutral lipids under energy demanding conditions and is controlled by neutral cytosolic lipases and lysosomal acidic lipases. In this review, we summarize recent progress regarding the regulatory pathways and molecular mechanisms that control the sizes and the energy storage capacity of LDs.
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14
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Bayer K, Banning C, Bruss V, Wiltzer-Bach L, Schindler M. Hepatitis C Virus Is Released via a Noncanonical Secretory Route. J Virol 2016; 90:10558-10573. [PMID: 27630244 PMCID: PMC5110177 DOI: 10.1128/jvi.01615-16] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 09/11/2016] [Indexed: 12/12/2022] Open
Abstract
We analyzed hepatitis C virus (HCV) morphogenesis using viral genomes encoding a mCherry-tagged E1 glycoprotein. HCV-E1-mCherry polyprotein expression, intracellular localization, and replication kinetics were comparable to those of untagged HCV, and E1-mCherry-tagged viral particles were assembled and released into cell culture supernatants. Expression and localization of structural E1 and nonstructural NS5A followed a temporospatial pattern with a succinct decrease in the number of replication complexes and the appearance of E1-mCherry punctae. Interaction of the structural proteins E1, Core, and E2 increased at E1-mCherry punctae in a time-dependent manner, indicating that E1-mCherry punctae represent assembled or assembling virions. E1-mCherry did not colocalize with Golgi markers. Furthermore, the bulk of viral glycoproteins within released particles revealed an EndoH-sensitive glycosylation pattern, indicating an absence of viral glycoprotein processing by the Golgi apparatus. In contrast, HCV-E1-mCherry trafficked with Rab9-positive compartments and inhibition of endosomes specifically suppressed HCV release. Our data suggest that assembled HCV particles are released via a noncanonical secretory route involving the endosomal compartment. IMPORTANCE The goal of this study was to shed light on the poorly understood trafficking and release routes of hepatitis C virus (HCV). For this, we generated novel HCV genomes which resulted in the production of fluorescently labeled viral particles. We used live-cell microscopy and other imaging techniques to follow up on the temporal dynamics of virus particle formation and trafficking in HCV-expressing liver cells. While viral particles and viral structural protein were found in endosomal compartments, no overlap of Golgi structures could be observed. Furthermore, biochemical and inhibitor-based experiments support a HCV release route which is distinguishable from canonical Golgi-mediated secretion. Since viruses hijack cellular pathways to generate viral progeny, our results point toward the possible existence of a not-yet-described cellular secretion route.
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Affiliation(s)
- Karen Bayer
- Institute of Virology, Helmholtz Zentrum München-German Research Center for Environmental Health, Munich, Germany
| | - Carina Banning
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Volker Bruss
- Institute of Virology, Helmholtz Zentrum München-German Research Center for Environmental Health, Munich, Germany
| | - Linda Wiltzer-Bach
- University Hospital Tübingen, Institute for Medical Virology and Epidemiology of Viral Diseases, Tübingen, Germany
| | - Michael Schindler
- Institute of Virology, Helmholtz Zentrum München-German Research Center for Environmental Health, Munich, Germany
- University Hospital Tübingen, Institute for Medical Virology and Epidemiology of Viral Diseases, Tübingen, Germany
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
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15
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Hanano A, Almousally I, Shaban M, Rahman F, Blee E, Murphy DJ. Biochemical, Transcriptional, and Bioinformatic Analysis of Lipid Droplets from Seeds of Date Palm (Phoenix dactylifera L.) and Their Use as Potent Sequestration Agents against the Toxic Pollutant, 2,3,7,8-Tetrachlorinated Dibenzo-p-Dioxin. FRONTIERS IN PLANT SCIENCE 2016; 7:836. [PMID: 27375673 PMCID: PMC4896926 DOI: 10.3389/fpls.2016.00836] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 05/27/2016] [Indexed: 05/25/2023]
Abstract
Contamination of aquatic environments with dioxins, the most toxic group of persistent organic pollutants (POPs), is a major ecological issue. Dioxins are highly lipophilic and bioaccumulate in fatty tissues of marine organisms used for seafood where they constitute a potential risk for human health. Lipid droplets (LDs) purified from date palm, Phoenix dactylifera, seeds were characterized and their capacity to extract dioxins from aquatic systems was assessed. The bioaffinity of date palm LDs toward 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most toxic congener of dioxins was determined. Fractioned LDs were spheroidal with mean diameters of 2.5 µm, enclosing an oil-rich core of 392.5 mg mL(-1). Isolated LDs did not aggregate and/or coalesce unless placed in acidic media and were strongly associated with three major groups of polypeptides of relative mass 32-37, 20-24, and 16-18 kDa. These masses correspond to the LD-associated proteins, oleosins, caleosins, and steroleosins, respectively. Efficient partitioning of TCDD into LDs occurred with a coefficient of log K LB/w,TCDD = 7.528 ± 0.024; it was optimal at neutral pH and was dependent on the presence of the oil-rich core, but was independent of the presence of LD-associated proteins. Bioinformatic analysis of the date palm genome revealed nine oleosin-like, five caleosin-like, and five steroleosin-like sequences, with predicted structures having putative lipid-binding domains that match their LD stabilizing roles and use as bio-based encapsulation systems. Transcriptomic analysis of date palm seedlings exposed to TCDD showed strong up-regulation of several caleosin and steroleosin genes, consistent with increased LD formation. The results suggest that the plant LDs could be used in ecological remediation strategies to remove POPs from aquatic environments. Recent reports suggest that several fungal and algal species also use LDs to sequester both external and internally derived hydrophobic toxins, which indicates that our approach could be used as a broader biomimetic strategy for toxin removal.
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Affiliation(s)
- Abdulsamie Hanano
- Department of Molecular Biology and Biotechnology, Atomic Energy Commission of SyriaDamascus, Syria
| | - Ibrahem Almousally
- Department of Molecular Biology and Biotechnology, Atomic Energy Commission of SyriaDamascus, Syria
| | - Mouhnad Shaban
- Department of Molecular Biology and Biotechnology, Atomic Energy Commission of SyriaDamascus, Syria
| | - Farzana Rahman
- Genomics and Computational Biology Group, University of South WalesPontypridd, UK
| | - Elizabeth Blee
- Institut de Biologie Moléculaire des PlantesStrasbourg, France
| | - Denis J. Murphy
- Genomics and Computational Biology Group, University of South WalesPontypridd, UK
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16
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Malitsky S, Ziv C, Rosenwasser S, Zheng S, Schatz D, Porat Z, Ben-Dor S, Aharoni A, Vardi A. Viral infection of the marine alga Emiliania huxleyi triggers lipidome remodeling and induces the production of highly saturated triacylglycerol. THE NEW PHYTOLOGIST 2016; 210:88-96. [PMID: 26856244 DOI: 10.1111/nph.13852] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2015] [Accepted: 12/15/2015] [Indexed: 05/04/2023]
Abstract
Viruses that infect marine photosynthetic microorganisms are major ecological and evolutionary drivers of microbial food webs, estimated to turn over more than a quarter of the total photosynthetically fixed carbon. Viral infection of the bloom-forming microalga Emiliania huxleyi induces the rapid remodeling of host primary metabolism, targeted towards fatty acid metabolism. We applied a liquid chromatography-mass spectrometry (LC-MS)-based lipidomics approach combined with imaging flow cytometry and gene expression profiling to explore the impact of viral-induced metabolic reprogramming on lipid composition. Lytic viral infection led to remodeling of the cellular lipidome, by predominantly inducing the biosynthesis of highly saturated triacylglycerols (TAGs), coupled with a significant accumulation of neutral lipids within lipid droplets. Furthermore, TAGs were found to be a major component (77%) of the lipidome of isolated virions. Interestingly, viral-induced TAGs were significantly more saturated than TAGs produced under nitrogen starvation. This study highlights TAGs as major products of the viral-induced metabolic reprogramming during the host-virus interaction and indicates a selective mode of membrane recruitment during viral assembly, possibly by budding of the virus from specialized subcellular compartments. These findings provide novel insights into the role of viruses infecting microalgae in regulating metabolism and energy transfer in the marine environment and suggest their possible biotechnological application in biofuel production.
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Affiliation(s)
- Sergey Malitsky
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Carmit Ziv
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Shilo Rosenwasser
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Shuning Zheng
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Daniella Schatz
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Ziv Porat
- Biological Services Department, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Shifra Ben-Dor
- Biological Services Department, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Asaph Aharoni
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Assaf Vardi
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel
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17
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Fernández de Castro I, Tenorio R, Risco C. Virus assembly factories in a lipid world. Curr Opin Virol 2016; 18:20-6. [PMID: 26985879 DOI: 10.1016/j.coviro.2016.02.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 02/11/2016] [Accepted: 02/19/2016] [Indexed: 12/15/2022]
Abstract
Many viruses build specialized structures known as viral factories, a protected environment in which viral genome replication and morphogenesis take place. Recent findings show that viruses manipulate lipid flows to assemble these replication platforms. Viruses are thus able to create new membranes by interfering with lipid metabolism, targeting and transport; they make use of specific lipid transfer proteins (LTP) at membrane contact sites, and frequently recruit endoplasmic reticulum (ER), ER export sites, and mitochondria. Some factories, such as those built by plant and certain animal viruses, are motile membranous structures involved in intracellular or intercellular transport of the replicated viral genome. The identification of lipids and LTP subverted by viruses might lead to better understand and fight viral infections.
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Affiliation(s)
- Isabel Fernández de Castro
- Cell Structure Laboratory, Centro Nacional de Biotecnología, CNB-CSIC, UAM, Campus de Cantoblanco, 28049 Madrid, Spain.
| | - Raquel Tenorio
- Cell Structure Laboratory, Centro Nacional de Biotecnología, CNB-CSIC, UAM, Campus de Cantoblanco, 28049 Madrid, Spain
| | - Cristina Risco
- Cell Structure Laboratory, Centro Nacional de Biotecnología, CNB-CSIC, UAM, Campus de Cantoblanco, 28049 Madrid, Spain.
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18
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Abstract
Many postitive-stranded RNA viruses, such as Hepatitis C virus (HCV), highjack cellular membranes, including the Golgi, ER, mitchondria, lipid droplets, and utilize them for replication of their RNA genome or assembly of new virions. By investigating how viral proteins associate with cellular membranes we will better understand the roles of cellular membranes in the viral life cycle. Our lab has focused specifically on the role of lipid droplets and lipid-rich membranes in the life cycle of HCV. To analyze the role of lipid-rich membranes in HCV RNA replication, we utilized a membrane flotation assay based on an 10-20-30% iodixanol density gradient developed by Yeaman et al. (2001). This gradient results in a linear increase in density over almost the entire length of the gradient, and membrane particles are separated in the gradient based on their buoyant characteristics. To preserve membranes in the lysate, cells are broken mechanically in a buffer lacking detergent. The cell lysate is loaded on the bottom of the gradient, overlaid with the gradient, and membranes float up as the iodixanol gradient self-generates. The lipid content of membranes and the concentration of associated proteins will determine the separation of different membranes within the gradient. After centrifugation, fractions can be sampled from the top of the gradient and analyzed using standard SDS-PAGE and western blot analysis for proteins of interest.
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Affiliation(s)
- Dorothee A Vogt
- Gladstone Institute for Virology and Immunology, San Francisco, USA
| | - Melanie Ott
- Gladstone Institute for Virology and Immunology, San Francisco, USA
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19
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O'Sullivan D, van der Windt GJW, Huang SCC, Curtis JD, Chang CH, Buck MD, Qiu J, Smith AM, Lam WY, DiPlato LM, Hsu FF, Birnbaum MJ, Pearce EJ, Pearce EL. Memory CD8(+) T cells use cell-intrinsic lipolysis to support the metabolic programming necessary for development. Immunity 2014; 41:75-88. [PMID: 25001241 DOI: 10.1016/j.immuni.2014.06.005] [Citation(s) in RCA: 562] [Impact Index Per Article: 56.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Accepted: 06/18/2014] [Indexed: 12/11/2022]
Abstract
Generation of CD8(+) memory T cells requires metabolic reprogramming that is characterized by enhanced mitochondrial fatty-acid oxidation (FAO). However, where the fatty acids (FA) that fuel this process come from remains unclear. While CD8(+) memory T cells engage FAO to a greater extent, we found that they acquired substantially fewer long-chain FA from their external environment than CD8(+) effector T (Teff) cells. Rather than using extracellular FA directly, memory T cells used extracellular glucose to support FAO and oxidative phosphorylation (OXPHOS), suggesting that lipids must be synthesized to generate the substrates needed for FAO. We have demonstrated that memory T cells rely on cell intrinsic expression of the lysosomal hydrolase LAL (lysosomal acid lipase) to mobilize FA for FAO and memory T cell development. Our observations link LAL to metabolic reprogramming in lymphocytes and show that cell intrinsic lipolysis is deterministic for memory T cell fate.
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Affiliation(s)
- David O'Sullivan
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Gerritje J W van der Windt
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Stanley Ching-Cheng Huang
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jonathan D Curtis
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Chih-Hao Chang
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Michael D Buck
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jing Qiu
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Amber M Smith
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Wing Y Lam
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Lisa M DiPlato
- The Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Fong-Fu Hsu
- Mass Spectrometry Resource, Division of Endocrinology, Diabetes, Metabolism, and Lipid Research, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Morris J Birnbaum
- The Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Edward J Pearce
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Erika L Pearce
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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