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Issleny BM, Jamjoum R, Majumder S, Stiban J. Sphingolipids: From structural components to signaling hubs. Enzymes 2023; 54:171-201. [PMID: 37945171 DOI: 10.1016/bs.enz.2023.07.003] [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] [Indexed: 11/12/2023]
Abstract
In late November 2019, Prof. Lina M. Obeid passed away from cancer, a disease she spent her life researching and studying its intricate molecular underpinnings. Along with her husband, Prof. Yusuf A. Hannun, Obeid laid down the foundations of sphingolipid biochemistry and oversaw its remarkable evolution over the years. Lipids are a class of macromolecules that are primarily associated with cellular architecture. In fact, lipids constitute the perimeter of the cell in such a way that without them, there cannot be cells. Hence, much of the early research on lipids identified the function of this class of biological molecules as merely structural. Nevertheless, unlike proteins, carbohydrates, and nucleic acids, lipids are elaborately diverse as they are not made up of monomers in polymeric forms. This diversity in structure is clearly mirrored by functional pleiotropy. In this chapter, we focus on a major subset of lipids, sphingolipids, and explore their historic rise from merely inert structural components of plasma membranes to lively and necessary signaling molecules that transmit various signals and control many cellular processes. We will emphasize the works of Lina Obeid since she was an integral pillar of the sphingolipid research world.
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Affiliation(s)
- Batoul M Issleny
- Department of Pharmacy, Birzeit University, West Bank, Palestine
| | - Rama Jamjoum
- Department of Pharmacy, Birzeit University, West Bank, Palestine
| | | | - Johnny Stiban
- Department of Biology and Biochemistry, Birzeit University, West Bank, Palestine.
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Zhang J, van der Zon G, Ma J, Mei H, Cabukusta B, Agaser CC, Madunić K, Wuhrer M, Zhang T, Ten Dijke P. ST3GAL5-catalyzed gangliosides inhibit TGF-β-induced epithelial-mesenchymal transition via TβRI degradation. EMBO J 2023; 42:e110553. [PMID: 36504224 PMCID: PMC9841337 DOI: 10.15252/embj.2021110553] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 11/09/2022] [Accepted: 11/14/2022] [Indexed: 12/14/2022] Open
Abstract
Epithelial-mesenchymal transition (EMT) is pivotal in the initiation and development of cancer cell metastasis. We observed that the abundance of glycosphingolipids (GSLs), especially ganglioside subtypes, decreased significantly during TGF-β-induced EMT in NMuMG mouse mammary epithelial cells and A549 human lung adenocarcinoma cells. Transcriptional profiling showed that TGF-β/SMAD response genes and EMT signatures were strongly enriched in NMuMG cells, along with depletion of UDP-glucose ceramide glucosyltransferase (UGCG), the enzyme that catalyzes the initial step in GSL biosynthesis. Consistent with this finding, genetic or pharmacological inhibition of UGCG promoted TGF-β signaling and TGF-β-induced EMT. UGCG inhibition promoted A549 cell migration, extravasation in the zebrafish xenograft model, and metastasis in mice. Mechanistically, GSLs inhibited TGF-β signaling by promoting lipid raft localization of the TGF-β type I receptor (TβRI) and by increasing TβRI ubiquitination and degradation. Importantly, we identified ST3GAL5-synthesized a-series gangliosides as the main GSL subtype involved in inhibition of TGF-β signaling and TGF-β-induced EMT in A549 cells. Notably, ST3GAL5 is weakly expressed in lung cancer tissues compared to adjacent nonmalignant tissues, and its expression correlates with good prognosis.
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Affiliation(s)
- Jing Zhang
- Oncode Institute and Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Gerard van der Zon
- Oncode Institute and Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Jin Ma
- Oncode Institute and Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Hailiang Mei
- Sequencing Analysis Support Core, Leiden University Medical Center, Leiden, The Netherlands
| | - Birol Cabukusta
- Oncode Institute and Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Cedrick C Agaser
- Sequencing Analysis Support Core, Leiden University Medical Center, Leiden, The Netherlands
| | - Katarina Madunić
- Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, The Netherlands
| | - Manfred Wuhrer
- Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, The Netherlands
| | - Tao Zhang
- Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, The Netherlands
| | - Peter Ten Dijke
- Oncode Institute and Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
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Smith CD, Maines LW, Keller SN, Katz Ben-Yair V, Fathi R, Plasse TF, Levitt ML. Recent Progress in the Development of Opaganib for the Treatment of Covid-19. Drug Des Devel Ther 2022; 16:2199-2211. [PMID: 35855741 PMCID: PMC9288228 DOI: 10.2147/dddt.s367612] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 07/02/2022] [Indexed: 12/15/2022] Open
Abstract
The Covid-19 pandemic driven by the SARS-CoV-2 virus continues to exert extensive humanitarian and economic stress across the world. Although antivirals active against mild disease have been identified recently, new drugs to treat moderate and severe Covid-19 patients are needed. Sphingolipids regulate key pathologic processes, including viral proliferation and pathologic host inflammation. Opaganib (aka ABC294640) is a first-in-class clinical drug targeting sphingolipid metabolism for the treatment of cancer and inflammatory diseases. Recent work demonstrates that opaganib also has antiviral activity against several viruses including SARS-CoV-2. A recently completed multinational Phase 2/3 clinical trial of opaganib in patients hospitalized with Covid-19 demonstrated that opaganib can be safely administered to these patients, and more importantly, resulted in a 62% decrease in mortality in a large subpopulation of patients with moderately severe Covid-19. Furthermore, acceleration of the clearance of the virus was observed in opaganib-treated patients. Understanding the biochemical mechanism for the anti-SARS-CoV-2 activity of opaganib is essential for optimizing Covid-19 treatment protocols. Opaganib inhibits three key enzymes in sphingolipid metabolism: sphingosine kinase-2 (SK2); dihydroceramide desaturase (DES1); and glucosylceramide synthase (GCS). Herein, we describe a tripartite model by which opaganib suppresses infection and replication of SARS-CoV-2 by inhibiting SK2, DES1 and GCS. The potential impact of modulation of sphingolipid signaling on multi-organ dysfunction in Covid-19 patients is also discussed.
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Affiliation(s)
- Charles D Smith
- Apogee Biotechnology Corporation, Hummelstown, PA, USA
- Correspondence: Charles D Smith, Apogee Biotechnology Corporation, 1214 Research Blvd, Suite 2015, Hummelstown, PA, 17036, USA, Tel +1 843 814 9257, Email
| | - Lynn W Maines
- Apogee Biotechnology Corporation, Hummelstown, PA, USA
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Arumugam S, Schmieder S, Pezeshkian W, Becken U, Wunder C, Chinnapen D, Ipsen JH, Kenworthy AK, Lencer W, Mayor S, Johannes L. Ceramide structure dictates glycosphingolipid nanodomain assembly and function. Nat Commun 2021; 12:3675. [PMID: 34135326 PMCID: PMC8209009 DOI: 10.1038/s41467-021-23961-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 05/28/2021] [Indexed: 02/08/2023] Open
Abstract
Gangliosides in the outer leaflet of the plasma membrane of eukaryotic cells are essential for many cellular functions and pathogenic interactions. How gangliosides are dynamically organized and how they respond to ligand binding is poorly understood. Using fluorescence anisotropy imaging of synthetic, fluorescently labeled GM1 gangliosides incorporated into the plasma membrane of living cells, we found that GM1 with a fully saturated C16:0 acyl chain, but not with unsaturated C16:1 acyl chain, is actively clustered into nanodomains, which depends on membrane cholesterol, phosphatidylserine and actin. The binding of cholera toxin B-subunit (CTxB) leads to enlarged membrane domains for both C16:0 and C16:1, owing to binding of multiple GM1 under a toxin, and clustering of CTxB. The structure of the ceramide acyl chain still affects these domains, as co-clustering with the glycosylphosphatidylinositol (GPI)-anchored protein CD59 occurs only when GM1 contains the fully saturated C16:0 acyl chain, and not C16:1. Thus, different ceramide species of GM1 gangliosides dictate their assembly into nanodomains and affect nanodomain structure and function, which likely underlies many endogenous cellular processes.
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Affiliation(s)
- Senthil Arumugam
- Institut Curie, PSL Research University, U1143 INSERM, UMR3666 CNRS, Cellular and Chemical Biology unit, Paris, Cedex, France
- National Centre for Biological Sciences (NCBS), Bangalore, India
- Monash Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton/Melbourne, VIC, Australia
- European Molecular Biological Laboratory Australia (EMBL Australia), Monash University, Clayton/ Melbourne, VIC, Australia
| | - Stefanie Schmieder
- Division of Gastroenterology, Boston Children's Hospital, Boston, MA, USA
| | - Weria Pezeshkian
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
| | - Ulrike Becken
- Institut Curie, PSL Research University, U1143 INSERM, UMR3666 CNRS, Cellular and Chemical Biology unit, Paris, Cedex, France
| | - Christian Wunder
- Institut Curie, PSL Research University, U1143 INSERM, UMR3666 CNRS, Cellular and Chemical Biology unit, Paris, Cedex, France
| | - Dan Chinnapen
- Division of Gastroenterology, Boston Children's Hospital, Boston, MA, USA
| | - John Hjort Ipsen
- MEMPHYS/PhyLife, Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense M, Denmark
| | - Anne K Kenworthy
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA
| | - Wayne Lencer
- Division of Gastroenterology, Boston Children's Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
- Harvard Digestive Diseases Center, Boston, MA, USA
| | - Satyajit Mayor
- National Centre for Biological Sciences (NCBS), Bangalore, India.
| | - Ludger Johannes
- Institut Curie, PSL Research University, U1143 INSERM, UMR3666 CNRS, Cellular and Chemical Biology unit, Paris, Cedex, France.
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Leite-Lima F, Bastos VC, Vitório JG, Duarte-Andrade FF, Pereira TDSF, Martins-Chaves RR, Cruz AF, de Lacerda JCT, Lebron YAR, Moreira VR, Santos LVDS, Lange LC, de Macedo AN, Diniz MG, Gomes CC, de Castro WH, Canuto GAB, Gomez RS. Unveiling metabolic changes in marsupialized odontogenic keratocyst: A pilot study. Oral Dis 2021; 28:2219-2229. [PMID: 33978981 DOI: 10.1111/odi.13913] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 04/08/2021] [Accepted: 05/05/2021] [Indexed: 01/03/2023]
Abstract
OBJECTIVE We aimed to assess which metabolic pathways would be implicated in the phenotypic changes of the epithelial lining of odontogenic keratocyst after marsupialization, comparing pre- and post-marsupialized lesions with adjacent oral mucosa. MATERIALS AND METHODS Eighteen formalin-fixed and paraffin-embedded tissues from six subjects were divided into three paired groups: odontogenic keratocyst pre- (n = 6) and post-marsupialization (n = 6), and adjacent oral mucosa (n = 6). The metabolic pathways found in these groups were obtained by high-performance liquid chromatography-mass spectrometry-based untargeted metabolomics performed. RESULTS Through putative metabolite annotation followed by pathway enrichment and predictive analysis with automated algorithms (Mummichog and Gene Set Enrichment Analysis), we found differences in many cellular processes that may be involved in inflammation, oxidative stress response, keratinocyte-basal membrane attachment, differentiation, and proliferation functions, all relevant to odontogenic keratocyst pathobiology and the phenotype acquired after marsupialization. CONCLUSION Our study was able to identify several metabolic pathways potentially involved in the metaplastic changes induced by marsupialization of odontogenic keratocysts. An improved comprehension of this process could pave the way for the development of targeted therapies.
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Affiliation(s)
- Flávia Leite-Lima
- Department of Oral Surgery and Pathology, School of Dentistry, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Victor Coutinho Bastos
- Department of Oral Surgery and Pathology, School of Dentistry, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Jéssica Gardone Vitório
- Department of Oral Surgery and Pathology, School of Dentistry, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Filipe Fideles Duarte-Andrade
- Department of Oral Surgery and Pathology, School of Dentistry, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Thaís Dos Santos Fontes Pereira
- Department of Oral Surgery and Pathology, School of Dentistry, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Roberta Rayra Martins-Chaves
- Department of Oral Surgery and Pathology, School of Dentistry, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Aline Fernanda Cruz
- Department of Oral Surgery and Pathology, School of Dentistry, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Júlio César Tanos de Lacerda
- Department of Oral Surgery and Pathology, School of Dentistry, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Yuri Abner Rocha Lebron
- Department of Sanitation and Environmental Engineering, School of Engineering, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Victor Rezende Moreira
- Department of Sanitation and Environmental Engineering, School of Engineering, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Lucilaine Valéria de Souza Santos
- Department of Sanitation and Environmental Engineering, School of Engineering, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Liséte Celina Lange
- Department of Sanitation and Environmental Engineering, School of Engineering, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Adriana Nori de Macedo
- Department of Chemistry, Exact Sciences Institute, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Marina Gonçalves Diniz
- Department of Pathology, Biological Sciences Institute, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Carolina Cavaliéri Gomes
- Department of Pathology, Biological Sciences Institute, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Wagner Henriques de Castro
- Department of Oral Surgery and Pathology, School of Dentistry, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Gisele André Baptista Canuto
- Department of Analytical Chemistry, Institute of Chemistry, Universidade Federal da Bahia (UFBA), Salvador, Brazil
| | - Ricardo Santiago Gomez
- Department of Oral Surgery and Pathology, School of Dentistry, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil
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Bagheri Y, Ali AA, You M. Current Methods for Detecting Cell Membrane Transient Interactions. Front Chem 2020; 8:603259. [PMID: 33365301 PMCID: PMC7750205 DOI: 10.3389/fchem.2020.603259] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Accepted: 10/16/2020] [Indexed: 12/28/2022] Open
Abstract
Short-lived cell membrane complexes play a key role in regulating cell signaling and communication. Many of these complexes are formed based on low-affinity and transient interactions among various lipids and proteins. New techniques have emerged to study these previously overlooked membrane transient interactions. Exciting functions of these transient interactions have been discovered in cellular events such as immune signaling, host-pathogen interactions, and diseases such as cancer. In this review, we have summarized current experimental methods that allow us to detect and analyze short-lived cell membrane protein-protein, lipid-protein, and lipid-lipid interactions. These methods can provide useful information about the strengths, kinetics, and/or spatial patterns of membrane transient interactions. However, each method also has its own limitations. We hope this review can be used as a guideline to help the audience to choose proper approaches for studying membrane transient interactions in different membrane trafficking and cell signaling events.
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Affiliation(s)
| | | | - Mingxu You
- Department of Chemistry, University of Massachusetts, Amherst, MA, United States
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Yeast Mpo1 Is a Novel Dioxygenase That Catalyzes the α-Oxidation of a 2-Hydroxy Fatty Acid in an Fe 2+-Dependent Manner. Mol Cell Biol 2019; 39:MCB.00428-18. [PMID: 30530523 DOI: 10.1128/mcb.00428-18] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 12/02/2018] [Indexed: 01/05/2023] Open
Abstract
Phytosphingosine (PHS) is the major long-chain base component of sphingolipids in Saccharomyces cerevisiae The PHS metabolic pathway includes a fatty acid (FA) α-oxidation reaction. Recently, we identified the novel protein Mpo1, which is involved in PHS metabolism. However, the details of the FA α-oxidation reaction and the role of Mpo1 in PHS metabolism remained unclear. In the present study, we revealed that Mpo1 is involved in the α-oxidation of 2-hydroxy (2-OH) palmitic acid (C16:0-COOH) in the PHS metabolic pathway. Our in vitro assay revealed that not only the Mpo1-containing membrane fraction but also the soluble fraction was required for the α-oxidation of 2-OH C16:0-COOH. The addition of Fe2+ eliminated the need for the soluble fraction. Purified Mpo1 converted 2-OH C16:0-COOH to C15:0-COOH in the presence of Fe2+, indicating that Mpo1 is the enzyme body responsible for catalyzing the FA α-oxidation reaction. This reaction was also found to require an oxygen molecule. Our findings indicate that Mpo1 catalyzes the FA α-oxidation reaction as 2-OH fatty acid dioxygenase, mediated by iron(IV) peroxide. Although numerous Mpo1 homologs exist in bacteria, fungi, protozoa, and plants, their functions had not yet been clarified. However, our findings suggest that these family members function as dioxygenases.
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ABO blood group antigens may be associated with increased susceptibility to schistosomiasis: a systematic review and meta-analysis. J Helminthol 2018; 94:e21. [PMID: 30526698 DOI: 10.1017/s0022149x18001116] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Schistosomiasis or bilharzia is a widespread parasitic disease caused by blood flukes of the genus Schistosoma. Some factors have been investigated previously regarding their effect on the pathophysiological mechanism of human schistosomiasis, but the possible influence of the ABO blood group on the severity of Schistosoma infection has been the most promising. Hence, we performed a systematic review and meta-analysis to further investigate the association of the ABO blood group with schistosomiasis susceptibility. Selected publications were retrieved from PubMed up to 21 August 2018, for related studies written in English. Number of cases (with schistosomiasis) and controls (without schistosomiasis) were extracted across all ABO blood types. Odds ratios (OR) and 95% confidence intervals (CI) were computed, pooled and interpreted. Subgroup analysis by the species of Schistosoma infecting the population and the participants' ethnicity was also performed. The overall analysis revealed heterogeneity in the outcomes, which warranted the identification of the cause using the Galbraith plot. Post-outlier outcomes of the pooled ORs show that individuals who are not blood type O are more susceptible (OR: 1.40; 95% CI: 1.17-1.67; PA < 0.001) to schistosomiasis than those who are blood type O (OR: 0.71; 95% CI: 0.60-0.85; PA < 0.001). Subgroup analysis yielded the same observations regardless of the species of schistosome and the ethnicity of the participants. Results of this meta-analysis suggest that individuals who are blood type B and A are more susceptible to schistosomiasis than those who are blood type O. However, more studies are needed to confirm our claims.
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Suckling RJ, Korona B, Whiteman P, Chillakuri C, Holt L, Handford PA, Lea SM. Structural and functional dissection of the interplay between lipid and Notch binding by human Notch ligands. EMBO J 2017; 36:2204-2215. [PMID: 28572448 PMCID: PMC5538765 DOI: 10.15252/embj.201796632] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 04/06/2017] [Accepted: 04/07/2017] [Indexed: 12/30/2022] Open
Abstract
Recent data have expanded our understanding of Notch signalling by identifying a C2 domain at the N-terminus of Notch ligands, which has both lipid- and receptor-binding properties. We present novel structures of human ligands Jagged2 and Delta-like4 and human Notch2, together with functional assays, which suggest that ligand-mediated coupling of membrane recognition and Notch binding is likely to be critical in establishing the optimal context for Notch signalling. Comparisons between the Jagged and Delta family show a huge diversity in the structures of the loops at the apex of the C2 domain implicated in membrane recognition and Jagged1 missense mutations, which affect these loops and are associated with extrahepatic biliary atresia, lead to a loss of membrane recognition, but do not alter Notch binding. Taken together, these data suggest that C2 domain binding to membranes is an important element in tuning ligand-dependent Notch signalling in different physiological contexts.
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Affiliation(s)
| | | | - Pat Whiteman
- Department of BiochemistryUniversity of OxfordOxfordUK
| | | | - Laurie Holt
- Department of BiochemistryUniversity of OxfordOxfordUK
| | | | - Susan M Lea
- Sir William Dunn School of PathologyUniversity of OxfordOxfordUK
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10
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Johannes L, Wunder C, Shafaq-Zadah M. Glycolipids and Lectins in Endocytic Uptake Processes. J Mol Biol 2016; 428:S0022-2836(16)30453-3. [PMID: 27984039 DOI: 10.1016/j.jmb.2016.10.027] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 10/24/2016] [Accepted: 10/24/2016] [Indexed: 01/04/2023]
Abstract
A host of endocytic processes has been described at the plasma membrane of eukaryotic cells. Their categorization has most commonly referenced cytosolic machinery, of which the clathrin coat has occupied a preponderant position. In what concerns intra-membrane constituents, the focus of interest has been on phosphatidylinositol lipids and their capacity to orchestrate endocytic events on the cytosolic leaflet of the membrane. The contribution of extracellular determinants to the construction of endocytic pits has received much less attention, depite the fact that (glyco)sphingolipids are exoplasmic leaflet fabric of membrane domains, termed rafts, whose contributions to predominantly clathrin-independent internalization processes is well recognized. Furthermore, sugar modifications on extracellular domains of proteins, and sugar-binding proteins, termed lectins, have also been linked to the uptake of endocytic cargoes at the plasma membrane. In this review, we first summarize these contributions by extracellular determinants to the endocytic process. We thus propose a molecular hypothesis - termed the GL-Lect hypothesis - on how GlycoLipids and Lectins drive the formation of compositional nanoenvrionments from which the endocytic uptake of glycosylated cargo proteins is operated via clathrin-independent carriers. Finally, we position this hypothesis within the global context of endocytic pathway proposals that have emerged in recent years.
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Affiliation(s)
- Ludger Johannes
- Institut Curie, PSL Research University, Chemical Biology of Membranes and Therapeutic Delivery unit, INSERM, U 1143, CNRS, UMR 3666, 26 rue d'Ulm, 75248 Paris Cedex 05, France.
| | - Christian Wunder
- Institut Curie, PSL Research University, Chemical Biology of Membranes and Therapeutic Delivery unit, INSERM, U 1143, CNRS, UMR 3666, 26 rue d'Ulm, 75248 Paris Cedex 05, France
| | - Massiullah Shafaq-Zadah
- Institut Curie, PSL Research University, Chemical Biology of Membranes and Therapeutic Delivery unit, INSERM, U 1143, CNRS, UMR 3666, 26 rue d'Ulm, 75248 Paris Cedex 05, France
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11
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Majewski J, André S, Jones E, Chi E, Gabius HJ. X-ray reflectivity and grazing incidence diffraction studies of interaction between human adhesion/growth-regulatory galectin-1 and DPPE-GM1 lipid monolayer at an air/water interface. BIOCHEMISTRY (MOSCOW) 2016; 80:943-56. [PMID: 26542007 DOI: 10.1134/s0006297915070135] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The specific interaction of ganglioside GM1 with the homodimeric (prototype) endogenous lectin galectin-1 triggers growth regulation in tumor and activated effector T cells. This proven biorelevance directed interest to studying association of the lectin to a model surface, i.e. a 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine/ganglioside GM1 (80 : 20 mol%) monolayer, at a bioeffective concentration. Surface expansion by the lectin insertion was detected at a surface pressure of 20 mN/m. On combining the methods of grazing incidence X-ray diffraction and X-ray reflectivity, a transient decrease in lipid-ordered phase of the monolayer was observed. The measured electron density distribution indicated that galectin-1 is oriented with its long axis in the surface plane, ideal for cis-crosslinking. The data reveal a conspicuous difference to the way the pentameric lectin part of the cholera toxin, another GM1-specific lectin, is bound to the monolayer. They also encourage further efforts to monitor effects of structurally different members of the galectin family such as the functionally antagonistic chimera-type galectin-3.
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Affiliation(s)
- J Majewski
- Manuel Lujan Jr. Neutron Scattering Center, Los Alamos Neutron Science Center, Los Alamos National Laboratory, Los Alamos, NM, USA
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12
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Narita T, Naganuma T, Sase Y, Kihara A. Long-chain bases of sphingolipids are transported into cells via the acyl-CoA synthetases. Sci Rep 2016; 6:25469. [PMID: 27136724 PMCID: PMC4853782 DOI: 10.1038/srep25469] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 04/18/2016] [Indexed: 01/19/2023] Open
Abstract
Transport of dietary lipids into small-intestinal epithelial cells is pathologically and nutritionally important. However, lipid uptake remains an almost unexplored research area. Although we know that long-chain bases (LCBs), constituents of sphingolipids, can enter into cells efficiently, the molecular mechanism of LCB uptake is completely unclear. Here, we found that the yeast acyl-CoA synthetases (ACSs) Faa1 and Faa4 are redundantly involved in LCB uptake. In addition to fatty acid-activating activity, transporter activity toward long-chain fatty acids (LCFAs) has been suggested for ACSs. Both LCB and LCFA transports were largely impaired in faa1Δ faa4Δ cells. Furthermore, LCB and LCFA uptakes were mutually competitive. However, the energy dependency was different for their transports. Sodium azide/2-deoxy-D-glucose treatment inhibited import of LCFA but not that of LCB. Furthermore, the ATP-AMP motif mutation FAA1 S271A largely impaired the metabolic activity and LCFA uptake, while leaving LCB import unaffected. These results indicate that only LCFA transport requires ATP. Since ACSs do not metabolize LCBs as substrates, Faa1 and Faa4 are likely directly involved in LCB transport. Furthermore, we revealed that ACSs are also involved in LCB transport in mammalian cells. Thus, our findings provide strong support for the hypothesis that ACSs directly transport LCFAs.
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Affiliation(s)
- Tomomi Narita
- Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12-jo, Nishi 6-chome, Kita-ku, Sapporo 060-0812, Japan
| | - Tatsuro Naganuma
- Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12-jo, Nishi 6-chome, Kita-ku, Sapporo 060-0812, Japan
| | - Yurie Sase
- Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12-jo, Nishi 6-chome, Kita-ku, Sapporo 060-0812, Japan
| | - Akio Kihara
- Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12-jo, Nishi 6-chome, Kita-ku, Sapporo 060-0812, Japan
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Adada M, Luberto C, Canals D. Inhibitors of the sphingomyelin cycle: Sphingomyelin synthases and sphingomyelinases. Chem Phys Lipids 2016. [DOI: 10.1016/j.chemphyslip.2015.07.008] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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14
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Kihara A. Synthesis and degradation pathways, functions, and pathology of ceramides and epidermal acylceramides. Prog Lipid Res 2016; 63:50-69. [PMID: 27107674 DOI: 10.1016/j.plipres.2016.04.001] [Citation(s) in RCA: 145] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 04/08/2016] [Accepted: 04/20/2016] [Indexed: 10/21/2022]
Abstract
Ceramide (Cer) is a structural backbone of sphingolipids and is composed of a long-chain base and a fatty acid. Existence of a variety of Cer species, which differ in chain-length, hydroxylation status, and/or double bond number of either of their hydrophobic chains, has been reported. Ceramide is produced by Cer synthases. Mammals have six Cer synthases (CERS1-6), each of which exhibits characteristic substrate specificity toward acyl-CoAs with different chain-lengths. Knockout mice for each Cer synthase show corresponding, isozyme-specific phenotypes, revealing the functional differences of Cers with different chain-lengths. Cer diversity is especially prominent in epidermis. Changes in Cer levels, composition, and chain-lengths are associated with atopic dermatitis. Acylceramide (acyl-Cer) specifically exists in epidermis and plays an essential role in skin permeability barrier formation. Accordingly, defects in acyl-Cer synthesis cause the cutaneous disorder ichthyosis with accompanying severe skin barrier defects. Although the molecular mechanism by which acyl-Cer is generated was long unclear, most genes involved in its synthesis have been identified recently. In Cer degradation pathways, the long-chain base moiety of Cer is converted to acyl-CoA, which is then incorporated mainly into glycerophospholipids. This pathway generates the lipid mediator sphingosine 1-phosphate. This review will focus on recent advances in our understanding of the synthesis and degradation pathways, physiological functions, and pathology of Cers/acyl-Cers.
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Affiliation(s)
- Akio Kihara
- Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12-jo, Nishi 6-choume, Kita-ku, Sapporo 060-0812, Japan.
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Gene Signature of Human Oral Mucosa Fibroblasts: Comparison with Dermal Fibroblasts and Induced Pluripotent Stem Cells. BIOMED RESEARCH INTERNATIONAL 2015; 2015:121575. [PMID: 26339586 PMCID: PMC4538314 DOI: 10.1155/2015/121575] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 04/03/2015] [Accepted: 04/10/2015] [Indexed: 01/27/2023]
Abstract
Oral mucosa is a useful material for regeneration therapy with the advantages of its accessibility and versatility regardless of age and gender. However, little is known about the molecular characteristics of oral mucosa. Here we report the first comparative profiles of the gene signatures of human oral mucosa fibroblasts (hOFs), human dermal fibroblasts (hDFs), and hOF-derived induced pluripotent stem cells (hOF-iPSCs), linking these with biological roles by functional annotation and pathway analyses. As a common feature of fibroblasts, both hOFs and hDFs expressed glycolipid metabolism-related genes at higher levels compared with hOF-iPSCs. Distinct characteristics of hOFs compared with hDFs included a high expression of glycoprotein genes, involved in signaling, extracellular matrix, membrane, and receptor proteins, besides a low expression of HOX genes, the hDFs-markers. The results of the pathway analyses indicated that tissue-reconstructive, proliferative, and signaling pathways are active, whereas senescence-related genes in p53 pathway are inactive in hOFs. Furthermore, more than half of hOF-specific genes were similarly expressed to those of hOF-iPSC genes and might be controlled by WNT signaling. Our findings demonstrated that hOFs have unique cellular characteristics in specificity and plasticity. These data may provide useful insight into application of oral fibroblasts for direct reprograming.
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Abstract
Blood group antigens represent polymorphic traits inherited among individuals and populations. At present, there are 34 recognized human blood groups and hundreds of individual blood group antigens and alleles. Differences in blood group antigen expression can increase or decrease host susceptibility to many infections. Blood groups can play a direct role in infection by serving as receptors and/or coreceptors for microorganisms, parasites, and viruses. In addition, many blood group antigens facilitate intracellular uptake, signal transduction, or adhesion through the organization of membrane microdomains. Several blood groups can modify the innate immune response to infection. Several distinct phenotypes associated with increased host resistance to malaria are overrepresented in populations living in areas where malaria is endemic, as a result of evolutionary pressures. Microorganisms can also stimulate antibodies against blood group antigens, including ABO, T, and Kell. Finally, there is a symbiotic relationship between blood group expression and maturation of the gastrointestinal microbiome.
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Affiliation(s)
- Laura Cooling
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, USA
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17
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Takeuchi J, Ohkubo A, Yuasa H. A ring-flippable sugar as a stimuli-responsive component of liposomes. Chem Asian J 2015; 10:586-94. [PMID: 25573604 DOI: 10.1002/asia.201403271] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Indexed: 11/07/2022]
Abstract
For the development of a liposome that takes in and out a drug in response to stimuli, 2,4-diaminoxylose (Xyl), which allows stimuli-responsive conformational switches between (4)C1 and (1)C4, was incorporated into a lipid structure: Xyl derivatives with C8 and C16 methylene chains at the 1,3-positions (C8Xyl and C16Xyl) were synthesized. (1)H NMR spectroscopy indicates that the addition of Zn(2+) and then H(+) induces conformational switches from the chair ((4)C1) to the reverse chair ((1)C4) and (1)C4-to-(4)C1, respectively, at Xyl; this leads to transformation of the lipids between linear and bent structures. Osmotic pressure and electron microscopy studies demonstrate that C8Xyl in water forms spherical solid aggregates (C8Xyl-Zn), which are converted into liposomes (C8Xyl+Zn) upon the addition of Zn(2+), and C16Xyl forms liposomes regardless of the presence of Zn(2+). The aggregates of C8Xyl±Zn incorporated a fluorophore and only C8Xyl+Zn released the content upon the addition of HCl. This study shows that Xyl could be a stimuli-responsive component of a liposome.
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Affiliation(s)
- Junji Takeuchi
- Department of Life Science, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259J2-10, Nagatsutacho, Midoriku, Yokohama 226-8501 (Japan)
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18
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Azevedo-Pereira RL, Morrot A, Machado GS, Paredes BD, Rodrigues DDC, de Carvalho ACC, Mendez-Otero R. Expression of ganglioside 9-O acetyl GD3 in undifferentiated embryonic stem cells. Cell Biol Int 2015; 39:121-7. [PMID: 25045067 DOI: 10.1002/cbin.10335] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 06/25/2014] [Indexed: 02/05/2023]
Abstract
Embryonic stem cells (ES cells) express a transient and heterogeneous pattern of molecules, which suggests a notable mechanism to control self-renewal avoid the differentiation into germ layers. We show that 9-O-acetyl GD3 (9OacGD3), a highly expressed b-series ganglioside in neural stem (NS) cells, is expressed in undifferentiated mouse ES cells in a heterogeneous fashion. After sorting, undifferentiated 9OacGD3(+) ES cell population had higher levels of nestin and Sox2 mRNA than the 9OacGD3(-) cells. Even with elevated expression of these neural transcription factors, 9OacGD3(+) cells did not give rise to more neural progenitors than 9OacGD3(-) cells. Expression of 9OacGD3 was recovered from 9OacGD3(-) cell population, demonstrating that expression of this ganglioside in mouse embryonic stem cells is transient, and does not reflect cell fate. Our findings show that the ganglioside 9OacGD3 is expressed heterogeneously and transiently in ES cells, and this expression corresponds to higher levels of Sox2 and Nestin transcripts.
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Affiliation(s)
- Ricardo Luiz Azevedo-Pereira
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil; Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Brazil
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19
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Schiffmann R. The consequences of genetic and pharmacologic reduction in sphingolipid synthesis. J Inherit Metab Dis 2015; 38:77-84. [PMID: 25164785 DOI: 10.1007/s10545-014-9758-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 07/28/2014] [Accepted: 07/31/2014] [Indexed: 10/24/2022]
Abstract
A new therapy based on substrate synthesis reduction in sphingolipidoses is showing promise. The consequences of decreasing sphingolipid synthesis depend on the level at which synthetic blockage occurs and on the extent of the blockage. Complete synthetic blockage may be lethal if it includes all sphingolipids, such as in a global knockout of serine palmitoyltransferase. Partial inhibition of sphingolipid synthetic pathways is usually benign and may have beneficial effects in a number of lysosomal diseases and in more common pathologies, as seen in animal models for atherosclerosis, polycystic kidney disease, diabetes, and asthma. Studies of various forms of sphingolipid synthesis reduction serve to highlight not only the cellular role of these lipids but also the potential risks and therapeutic benefits of pharmacological agents to be used in therapy for human diseases.
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Affiliation(s)
- Raphael Schiffmann
- Institute of Metabolic Disease, Baylor Research Institute, 3812 Elm Street, Dallas, TX, USA,
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20
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Identification of the phytosphingosine metabolic pathway leading to odd-numbered fatty acids. Nat Commun 2014; 5:5338. [DOI: 10.1038/ncomms6338] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 09/20/2014] [Indexed: 12/19/2022] Open
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21
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Quinn PJ. Sphingolipid symmetry governs membrane lipid raft structure. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:1922-30. [DOI: 10.1016/j.bbamem.2014.02.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 02/24/2014] [Accepted: 02/27/2014] [Indexed: 02/07/2023]
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Phuyal S, Hessvik NP, Skotland T, Sandvig K, Llorente A. Regulation of exosome release by glycosphingolipids and flotillins. FEBS J 2014; 281:2214-27. [PMID: 24605801 DOI: 10.1111/febs.12775] [Citation(s) in RCA: 140] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 02/06/2014] [Accepted: 03/04/2014] [Indexed: 12/14/2022]
Abstract
Exosomes are released by cells after fusion of multivesicular bodies with the plasma membrane. The molecular mechanism of this process is still unclear. We investigated the role of sphingolipids and flotillins, which constitute a raft-associated family of proteins, in the release of exosomes. Interestingly, our results show that dl-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol, an inhibitor of glucosylceramide synthase, seemed to affect the composition of exosomes released from PC-3 cells. However, the inhibition of ceramide formation from the de novo pathway by fumonisin B1 did not affect exosome secretion. Moreover, in contrast to findings obtained with other cell lines published so far, inhibition of neutral sphingomyelinase 2, an enzyme that catalyzes the formation of ceramide from sphingomyelin, did not inhibit the secretion of exosomes in PC-3 cells. Finally, small interfering RNA-mediated downregulation of flotillin-1 and flotillin-2 did not significantly change the levels of released exosomes as such, but seemed to affect the composition of exosomes. In conclusion, our results reveal the involvement of glycosphingolipids and flotillins in the release of exosomes from PC-3 cells, and indicate that the role of ceramide in exosome formation may be cell-dependent.
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Affiliation(s)
- Santosh Phuyal
- Department of Biochemistry, Institute for Cancer Research, Oslo University Hospital - The Norwegian Radium Hospital, Norway; Center for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Norway
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Sasamura T, Matsuno K, Fortini ME. Disruption of Drosophila melanogaster lipid metabolism genes causes tissue overgrowth associated with altered developmental signaling. PLoS Genet 2013; 9:e1003917. [PMID: 24244188 PMCID: PMC3820792 DOI: 10.1371/journal.pgen.1003917] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 09/09/2013] [Indexed: 12/16/2022] Open
Abstract
Developmental patterning requires the precise interplay of numerous intercellular signaling pathways to ensure that cells are properly specified during tissue formation and organogenesis. The spatiotemporal function of many developmental pathways is strongly influenced by the biosynthesis and intracellular trafficking of signaling components. Receptors and ligands must be trafficked to the cell surface where they interact, and their subsequent endocytic internalization and endosomal trafficking is critical for both signal propagation and its down-modulation. In a forward genetic screen for mutations that alter intracellular Notch receptor trafficking in Drosophila melanogaster, we recovered mutants that disrupt genes encoding serine palmitoyltransferase and acetyl-CoA carboxylase. Both mutants cause Notch, Wingless, the Epidermal Growth Factor Receptor (EFGR), and Patched to accumulate abnormally in endosomal compartments. In mosaic animals, mutant tissues exhibit an unusual non-cell-autonomous effect whereby mutant cells are functionally rescued by secreted activities emanating from adjacent wildtype tissue. Strikingly, both mutants display prominent tissue overgrowth phenotypes that are partially attributable to altered Notch and Wnt signaling. Our analysis of the mutants demonstrates genetic links between abnormal lipid metabolism, perturbations in developmental signaling, and aberrant cell proliferation. The development of complex, multicellular animal tissues requires the coordinated function of many different cell-cell communication pathways, in which secreted or cell-surface-anchored ligands from one cell typically activate a receptor on the surface of other cells, which in turn regulates downstream gene transcription and other cellular processes. We used a genetic approach in the fruit fly Drosophila melanogaster to search directly for mutations that perturb intracellular trafficking of a major signaling receptor, namely the Notch receptor, which controls cell differentiation in various tissue contexts. The Notch signaling pathway, like other key developmental signaling pathways, is evolutionarily conserved and functions in a similar manner in D. melanogaster and mammals, including humans. We recovered and characterized mutations in two genes that encode different enzymes involved in cellular lipid metabolism. Both mutants alter not only Notch signaling but also downstream activity of another highly conserved signaling pathway mediated by the Wingless protein, illustrating that alterations in cellular enzymes of lipid metabolism can exert complex effects on multiple critical signaling pathways. We also found that the new mutants exhibit dramatic cell overproliferation effects, reinforcing findings from mammalian studies suggesting that lipid metabolism might play an important role in oncogenesis and tumor progression.
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Affiliation(s)
- Takeshi Sasamura
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America ; Department of Biological Science, Osaka University, Machikaneyama, Toyonaka, Osaka, Japan
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Sphingosine 1-phosphate is a key metabolite linking sphingolipids to glycerophospholipids. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1841:766-72. [PMID: 23994042 DOI: 10.1016/j.bbalip.2013.08.014] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 08/09/2013] [Accepted: 08/13/2013] [Indexed: 12/18/2022]
Abstract
The sphingolipid metabolite sphingosine 1-phosphate (S1P) is a well-known lipid mediator. As a lipid mediator, S1P must be present in extracellular space and bind to its cell surface receptors (S1P1-5). However, most S1P, synthesized intracellularly, is metabolized without being released into extracellular space, in other words, without functioning as a lipid mediator in the vast majority of cells except those supplying plasma and lymph S1P such as blood cells and endothelial cells. Instead, intracellular S1P plays an important role as an intermediate of the sole sphingolipid-to-glycerophospholipid metabolic pathway. The degradation of S1P by S1P lyase is the first irreversible reaction (committed step) of this pathway. This metabolic pathway is conserved in eukaryotes from yeast to human, indicating its much older origin than the function of S1P as a lipid mediator, which is found to be present only in vertebrates and chordates. The sphingolipid-to-glycerophospholipid metabolism takes place ubiquitously in mammalian tissues, and its defect causes an aberration of several tissue functions as well as abnormal lipid metabolism. Although this metabolic pathway has been known for over four decades, only recently the precise reactions and enzymes involved in this pathway have been revealed. This review will focus on the recent advances in our understanding of the sphingolipid metabolic pathway via S1P and its physiological and pathological roles. This article is part of a Special Issue entitled New Frontiers in Sphingolipid Biology.
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Abstract
There is growing evidence that cell membranes can contain domains with different lipid and protein compositions and with different physical properties. Furthermore, it is increasingly appreciated that sphingolipids play a crucial role in the formation and properties of ordered lipid domains (rafts) in cell membranes. This review describes recent advances in our understanding of ordered membrane domains in both cells and model membranes. In addition, how the structure of sphingolipids influences their ability to participate in the formation of ordered domains, as well as how sphingolipid structure alters ordered domain properties, is described. The diversity of sphingolipid structure is likely to play an important role in modulating the biologically relevant properties of "rafts" in cell membranes.
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Abstract
Protein glycosylation is a ubiquitous post-translational modification found in all domains of life. Despite their significant complexity in animal systems, glycan structures have crucial biological and physiological roles, from contributions in protein folding and quality control to involvement in a large number of biological recognition events. As a result, they impart an additional level of 'information content' to underlying polypeptide structures. Improvements in analytical methodologies for dissecting glycan structural diversity, along with recent developments in biochemical and genetic approaches for studying glycan biosynthesis and catabolism, have provided a greater understanding of the biological contributions of these complex structures in vertebrates.
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