1
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Opadele AE, Nishioka S, Wu PH, Le QT, Shirato H, Nam JM, Onodera Y. The lipid-binding D4 domain of perfringolysin O facilitates the active loading of exogenous cargo into extracellular vesicles. FEBS Lett 2024; 598:446-456. [PMID: 38339784 DOI: 10.1002/1873-3468.14807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 12/07/2023] [Accepted: 12/15/2023] [Indexed: 02/12/2024]
Abstract
Whereas extracellular vesicles (EVs) have been engineered for cargo loading, innovative strategies for it can still be developed. Here, we describe domain 4 (D4), a cholesterol-binding domain derived from perfringolysin O, as a viable candidate for EV cargo loading. D4 and its mutants localized to the plasma membrane and the membranes of different vesicular structures in the cytoplasm, and facilitate the transport of proteins of interest (POIs) into EVs. D4-EVs were internalized by recipient cells analogous to EVs engineered with CD9. Intracellular cargo discharge from D4-EVs was successfully detected with the assistance of vesicular stomatitis virus glycoprotein. This study presents a novel strategy for recruiting POIs into EVs via a lipid-binding domain that ensures content release in recipient cells.
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Affiliation(s)
- Abayomi Emmanuel Opadele
- Laboratory for Molecular and Cellular Dynamics Research, Graduate School of Biomedical Science and Engineering, Hokkaido University, Sapporo, Japan
| | - Soichiro Nishioka
- Global Center for Biomedical Science and Engineering (GCB), Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Ping-Hsiu Wu
- Department of Radiology, School of Medicine, College of Medicine, Taipei Medical University, Taiwan
| | - Quynh-Thu Le
- Department of Radiation Oncology, Stanford University School of Medicine, CA, USA
| | - Hiroki Shirato
- Global Center for Biomedical Science and Engineering (GCB), Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Jin-Min Nam
- Global Center for Biomedical Science and Engineering (GCB), Faculty of Medicine, Hokkaido University, Sapporo, Japan
- Division of Systemic Life Science, Graduate School of Biostudies, Kyoto University, Japan
| | - Yasuhito Onodera
- Global Center for Biomedical Science and Engineering (GCB), Faculty of Medicine, Hokkaido University, Sapporo, Japan
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2
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Tomishige N, Bin Nasim M, Murate M, Pollet B, Didier P, Godet J, Richert L, Sako Y, Mély Y, Kobayashi T. HIV-1 Gag targeting to the plasma membrane reorganizes sphingomyelin-rich and cholesterol-rich lipid domains. Nat Commun 2023; 14:7353. [PMID: 37990014 PMCID: PMC10663554 DOI: 10.1038/s41467-023-42994-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 10/26/2023] [Indexed: 11/23/2023] Open
Abstract
Although the human immunodeficiency virus type 1 lipid envelope has been reported to be enriched with host cell sphingomyelin and cholesterol, the molecular mechanism of the enrichment is not well understood. Viral Gag protein plays a central role in virus budding. Here, we report the interaction between Gag and host cell lipids using different quantitative and super-resolution microscopy techniques in combination with specific probes that bind endogenous sphingomyelin and cholesterol. Our results indicate that Gag in the inner leaflet of the plasma membrane colocalizes with the outer leaflet sphingomyelin-rich domains and cholesterol-rich domains, enlarges sphingomyelin-rich domains, and strongly restricts the mobility of sphingomyelin-rich domains. Moreover, Gag multimerization induces sphingomyelin-rich and cholesterol-rich lipid domains to be in close proximity in a curvature-dependent manner. Our study suggests that Gag binds, coalesces, and reorganizes pre-existing lipid domains during assembly.
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Affiliation(s)
- Nario Tomishige
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France.
- Cellular Informatics Laboratory, RIKEN CPR, Wako, Saitama, Japan.
| | - Maaz Bin Nasim
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
- Faculty of Pharmacy, The University of Lahore, Lahore, Pakistan
| | - Motohide Murate
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
- Cellular Informatics Laboratory, RIKEN CPR, Wako, Saitama, Japan
| | - Brigitte Pollet
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Pascal Didier
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Julien Godet
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Ludovic Richert
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Yasushi Sako
- Cellular Informatics Laboratory, RIKEN CPR, Wako, Saitama, Japan
| | - Yves Mély
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France.
| | - Toshihide Kobayashi
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France.
- Cellular Informatics Laboratory, RIKEN CPR, Wako, Saitama, Japan.
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3
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Willet AH, Wos M, Igarashi MG, Ren L, Turner LA, Gould KL. Elevated levels of sphingolipid MIPC in the plasma membrane disrupt the coordination of cell growth with cell wall formation in fission yeast. PLoS Genet 2023; 19:e1010987. [PMID: 37792890 PMCID: PMC10578601 DOI: 10.1371/journal.pgen.1010987] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 10/16/2023] [Accepted: 09/19/2023] [Indexed: 10/06/2023] Open
Abstract
Coupling cell wall expansion with cell growth is a universal challenge faced by walled organisms. Mutations in Schizosaccharomyces pombe css1, which encodes a PM inositol phosphosphingolipid phospholipase C, prevent cell wall expansion but not synthesis of cell wall material. To probe how Css1 modulates cell wall formation we used classical and chemical genetics coupled with quantitative mass spectrometry. We found that elevated levels of the sphingolipid biosynthetic pathway's final product, mannosylinositol phosphorylceramide (MIPC), specifically correlated with the css1-3 phenotype. We also found that an apparent indicator of sphingolipids and a sterol biosensor accumulated at the cytosolic face of the PM at cell tips and the division site of css1-3 cells and, in accord, the PM in css1-3 was less dynamic than in wildtype cells. Interestingly, disrupting the protein glycosylation machinery recapitulated the css1-3 phenotype and led us to investigate Ghs2, a glycosylated PM protein predicted to modify cell wall material. Disrupting Ghs2 function led to aberrant cell wall material accumulation suggesting Ghs2 is dysfunctional in css1-3. We conclude that preventing an excess of MIPC in the S. pombe PM is critical to the function of key PM-localized proteins necessary for coupling growth with cell wall formation.
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Affiliation(s)
- Alaina H. Willet
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, United States of America
| | - Marcin Wos
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, United States of America
| | - Maya G. Igarashi
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, United States of America
| | - Liping Ren
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, United States of America
| | - Lesley A. Turner
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, United States of America
| | - Kathleen L. Gould
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, United States of America
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4
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Heckle LA, Kozminski KG. Osh-dependent and -independent Regulation of PI4P Levels During Polarized Growth of Saccharomyces cerevisiae. Mol Biol Cell 2023; 34:ar104. [PMID: 37556206 PMCID: PMC10559303 DOI: 10.1091/mbc.e23-03-0089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 07/03/2023] [Accepted: 07/31/2023] [Indexed: 08/11/2023] Open
Abstract
Polarized secretion facilitates polarized cell growth. For a secretory vesicle to dock at the plasma membrane, it must mature with a progressive association or dissociation of molecules that are, respectively, necessary for or inhibitory to vesicle docking, including an exchange of Rab GTPases. In current models, oxysterol-binding protein homologue 4 (Osh4p) establishes a phosphatidylinositol 4-phosphate (PI4P) gradient along the secretory trafficking pathway such that vesicles have higher PI4P levels after budding from the trans-Golgi relative to when vesicles arrive at the plasma membrane. In this study, using the lipid-binding domain P4M and live-cell imaging, we show that secretory vesicle-associated PI4P levels remain constant when vesicles traffic from the trans-Golgi to the plasma membrane. We also show that deletion of OSH4 does not alter vesicle-associated PI4P levels, though loss of any individual member of the OSH family or complete loss of OSH family function alters the intracellular distribution of PI4P. We propose a model in which the Rab GTPases Ypt32p and Sec4p remain associated with a secretory vesicle during trafficking, independent of PI4P levels and Osh4p. Together these data indicate the necessity of experiments revealing the location and timing of events required for vesicle maturation.
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Affiliation(s)
- Lindsay A. Heckle
- Department of Biology, University of Virginia, Charlottesville, VA 22904
| | - Keith G. Kozminski
- Department of Biology, University of Virginia, Charlottesville, VA 22904
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22908
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5
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Naito T, Yang H, Koh DHZ, Mahajan D, Lu L, Saheki Y. Regulation of cellular cholesterol distribution via non-vesicular lipid transport at ER-Golgi contact sites. Nat Commun 2023; 14:5867. [PMID: 37735529 PMCID: PMC10514280 DOI: 10.1038/s41467-023-41213-w] [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: 01/06/2023] [Accepted: 08/28/2023] [Indexed: 09/23/2023] Open
Abstract
Abnormal distribution of cellular cholesterol is associated with numerous diseases, including cardiovascular and neurodegenerative diseases. Regulated transport of cholesterol is critical for maintaining its proper distribution in the cell, yet the underlying mechanisms remain unclear. Here, we show that lipid transfer proteins, namely ORP9, OSBP, and GRAMD1s/Asters (GRAMD1a/GRAMD1b/GRAMD1c), control non-vesicular cholesterol transport at points of contact between the ER and the trans-Golgi network (TGN), thereby maintaining cellular cholesterol distribution. ORP9 localizes to the TGN via interaction between its tandem α-helices and ORP10/ORP11. ORP9 extracts PI4P from the TGN to prevent its overaccumulation and suppresses OSBP-mediated PI4P-driven cholesterol transport to the Golgi. By contrast, GRAMD1s transport excess cholesterol from the Golgi to the ER, thereby preventing its build-up. Cells lacking ORP9 exhibit accumulation of cholesterol at the Golgi, which is further enhanced by additional depletion of GRAMD1s with major accumulation in the plasma membrane. This is accompanied by chronic activation of the SREBP-2 signalling pathway. Our findings reveal the importance of regulated lipid transport at ER-Golgi contacts for maintaining cellular cholesterol distribution and homeostasis.
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Affiliation(s)
- Tomoki Naito
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, 308232, Singapore
| | - Haoning Yang
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, 308232, Singapore
| | - Dylan Hong Zheng Koh
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, 308232, Singapore
| | - Divyanshu Mahajan
- School of Biological Sciences, Nanyang Technological University, Singapore, 637551, Singapore
| | - Lei Lu
- School of Biological Sciences, Nanyang Technological University, Singapore, 637551, Singapore
| | - Yasunori Saheki
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, 308232, Singapore.
- Institute of Resource Development and Analysis, Kumamoto University, Kumamoto, 860-0811, Japan.
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6
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Erazo-Oliveras A, Muñoz-Vega M, Mlih M, Thiriveedi V, Salinas ML, Rivera-Rodríguez JM, Kim E, Wright RC, Wang X, Landrock KK, Goldsby JS, Mullens DA, Roper J, Karpac J, Chapkin RS. Mutant APC reshapes Wnt signaling plasma membrane nanodomains by altering cholesterol levels via oncogenic β-catenin. Nat Commun 2023; 14:4342. [PMID: 37468468 PMCID: PMC10356786 DOI: 10.1038/s41467-023-39640-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 06/21/2023] [Indexed: 07/21/2023] Open
Abstract
Although the role of the Wnt pathway in colon carcinogenesis has been described previously, it has been recently demonstrated that Wnt signaling originates from highly dynamic nano-assemblies at the plasma membrane. However, little is known regarding the role of oncogenic APC in reshaping Wnt nanodomains. This is noteworthy, because oncogenic APC does not act autonomously and requires activation of Wnt effectors upstream of APC to drive aberrant Wnt signaling. Here, we demonstrate the role of oncogenic APC in increasing plasma membrane free cholesterol and rigidity, thereby modulating Wnt signaling hubs. This results in an overactivation of Wnt signaling in the colon. Finally, using the Drosophila sterol auxotroph model, we demonstrate the unique ability of exogenous free cholesterol to disrupt plasma membrane homeostasis and drive Wnt signaling in a wildtype APC background. Collectively, these findings provide a link between oncogenic APC, loss of plasma membrane homeostasis and CRC development.
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Affiliation(s)
- Alfredo Erazo-Oliveras
- Program in Integrative Nutrition and Complex Diseases, Texas A&M University, College Station, TX, 77843, USA
- Department of Nutrition, Texas A&M University, College Station, TX, 77843, USA
- CPRIT Regional Center of Excellence in Cancer Research, Texas A&M University, College Station, TX, 77843, USA
| | - Mónica Muñoz-Vega
- Program in Integrative Nutrition and Complex Diseases, Texas A&M University, College Station, TX, 77843, USA
- Department of Nutrition, Texas A&M University, College Station, TX, 77843, USA
- CPRIT Regional Center of Excellence in Cancer Research, Texas A&M University, College Station, TX, 77843, USA
| | - Mohamed Mlih
- Department of Cell Biology and Genetics, Texas A&M University, School of Medicine, Bryan, TX, 77807, USA
| | - Venkataramana Thiriveedi
- Department of Medicine, Division of Gastroenterology, Duke University School of Medicine, Durham, NC, 27710, USA
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, 27710, USA
- Department of Cell Biology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Michael L Salinas
- Program in Integrative Nutrition and Complex Diseases, Texas A&M University, College Station, TX, 77843, USA
- Department of Nutrition, Texas A&M University, College Station, TX, 77843, USA
- CPRIT Regional Center of Excellence in Cancer Research, Texas A&M University, College Station, TX, 77843, USA
| | - Jaileen M Rivera-Rodríguez
- Program in Integrative Nutrition and Complex Diseases, Texas A&M University, College Station, TX, 77843, USA
- Department of Nutrition, Texas A&M University, College Station, TX, 77843, USA
- CPRIT Regional Center of Excellence in Cancer Research, Texas A&M University, College Station, TX, 77843, USA
| | - Eunjoo Kim
- Division of Pulmonary Sciences and Critical Care Medicine, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, CO, 80045, USA
| | - Rachel C Wright
- Program in Integrative Nutrition and Complex Diseases, Texas A&M University, College Station, TX, 77843, USA
- Department of Nutrition, Texas A&M University, College Station, TX, 77843, USA
| | - Xiaoli Wang
- Program in Integrative Nutrition and Complex Diseases, Texas A&M University, College Station, TX, 77843, USA
- Department of Nutrition, Texas A&M University, College Station, TX, 77843, USA
| | - Kerstin K Landrock
- Program in Integrative Nutrition and Complex Diseases, Texas A&M University, College Station, TX, 77843, USA
- Department of Nutrition, Texas A&M University, College Station, TX, 77843, USA
| | - Jennifer S Goldsby
- Program in Integrative Nutrition and Complex Diseases, Texas A&M University, College Station, TX, 77843, USA
- Department of Nutrition, Texas A&M University, College Station, TX, 77843, USA
- CPRIT Regional Center of Excellence in Cancer Research, Texas A&M University, College Station, TX, 77843, USA
| | - Destiny A Mullens
- Program in Integrative Nutrition and Complex Diseases, Texas A&M University, College Station, TX, 77843, USA
- Department of Nutrition, Texas A&M University, College Station, TX, 77843, USA
- CPRIT Regional Center of Excellence in Cancer Research, Texas A&M University, College Station, TX, 77843, USA
| | - Jatin Roper
- Department of Medicine, Division of Gastroenterology, Duke University School of Medicine, Durham, NC, 27710, USA
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, 27710, USA
- Department of Cell Biology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Jason Karpac
- Department of Cell Biology and Genetics, Texas A&M University, School of Medicine, Bryan, TX, 77807, USA
| | - Robert S Chapkin
- Program in Integrative Nutrition and Complex Diseases, Texas A&M University, College Station, TX, 77843, USA.
- Department of Nutrition, Texas A&M University, College Station, TX, 77843, USA.
- CPRIT Regional Center of Excellence in Cancer Research, Texas A&M University, College Station, TX, 77843, USA.
- Center for Environmental Health Research, Texas A&M University, College Station, TX, 77843, USA.
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7
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Haram CS, Moitra S, Keane R, Kuhlmann FM, Frankfater C, Hsu FF, Beverley SM, Zhang K, Keyel PA. The sphingolipids ceramide and inositol phosphorylceramide protect the Leishmania major membrane from sterol-specific toxins. J Biol Chem 2023; 299:104745. [PMID: 37094699 PMCID: PMC10209034 DOI: 10.1016/j.jbc.2023.104745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 04/19/2023] [Accepted: 04/21/2023] [Indexed: 04/26/2023] Open
Abstract
The accessibility of sterols in mammalian cells to exogenous sterol-binding agents has been well-described previously, but sterol accessibility in distantly related protozoa is unclear. The human pathogen Leishmania major uses sterols and sphingolipids distinct from those used in mammals. Sterols in mammalian cells can be sheltered from sterol-binding agents by membrane components, including sphingolipids, but the surface exposure of ergosterol in Leishmania remains unknown. Here, we used flow cytometry to test the ability of the Leishmania major sphingolipids inositol phosphorylceramide (IPC), and ceramide to shelter ergosterol by preventing binding of the sterol-specific toxins streptolysin O and perfringolysin O and subsequent cytotoxicity. In contrast to mammalian systems, we found that Leishmania sphingolipids did not preclude toxin binding to sterols in the membrane. However, we show that IPC reduced cytotoxicity, and that ceramide reduced perfringolysin O-, but not streptolysin O-, mediated cytotoxicity in cells. Furthermore, we demonstrate ceramide sensing was controlled by the toxin L3 loop, and that ceramide was sufficient to protect L. major promastigotes from the anti-leishmaniasis drug amphotericin B. Based on these results, we propose a mechanism whereby pore-forming toxins engage additional lipids like ceramide to determine the optimal environment to sustain pore formation. Thus, L. major could serve as a genetically tractable protozoan model organism for understanding toxin-membrane interactions.
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Affiliation(s)
- Chaitanya S Haram
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409
| | - Samrat Moitra
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409
| | - Rilee Keane
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409
| | - F Matthew Kuhlmann
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Cheryl Frankfater
- Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110
| | - Fong-Fu Hsu
- Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110
| | - Stephen M Beverley
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Kai Zhang
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409
| | - Peter A Keyel
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409.
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8
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Shaw TR, Wisser KC, Schaffner TA, Gaffney AD, Machta BB, Veatch SL. Chemical potential measurements constrain models of cholesterol-phosphatidylcholine interactions. Biophys J 2023; 122:1105-1117. [PMID: 36785512 PMCID: PMC10111267 DOI: 10.1016/j.bpj.2023.02.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 12/12/2022] [Accepted: 02/01/2023] [Indexed: 02/15/2023] Open
Abstract
Bilayer membranes composed of cholesterol and phospholipids exhibit diverse forms of nonideal mixing. In particular, many previous studies document macroscopic liquid-liquid phase separation as well as nanometer-scale heterogeneity in membranes of phosphatidylcholine (PC) lipids and cholesterol. Here, we present experimental measurements of cholesterol chemical potential (μc) in binary membranes containing dioleoyl PC (DOPC), 1-palmitoyl-2-oleoyl PC (POPC), or dipalmitoyl PC (DPPC), and in ternary membranes of DOPC and DPPC, referenced to crystalline cholesterol. μc is the thermodynamic quantity that dictates the availability of cholesterol to bind other factors, and notably must be equal between coexisting phases of a phase separated mixture. It is simply related to concentration under conditions of ideal mixing, but is far from ideal for the majority of lipid mixtures investigated here. Measurements of μc can vary with phospholipid composition by 1.5 kBT at constant cholesterol mole fraction implying a more than fivefold change in its availability for binding receptors and other reactions. Experimental measurements are fit to thermodynamic models including cholesterol-DPPC complexes or pairwise interactions between lipid species to provide intuition about the magnitude of interactions. These findings reinforce that μc depends on membrane composition overall, suggesting avenues for cells to alter the availability of cholesterol without varying cholesterol concentration.
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Affiliation(s)
- Thomas R Shaw
- Program in Biophysics, University of Michigan, Ann Arbor, Michigan; Program in Applied Physics, University of Michigan, Ann Arbor, Michigan
| | | | | | - Anna D Gaffney
- Program in Biophysics, University of Michigan, Ann Arbor, Michigan
| | | | - Sarah L Veatch
- Program in Biophysics, University of Michigan, Ann Arbor, Michigan; Program in Applied Physics, University of Michigan, Ann Arbor, Michigan.
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9
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Lange Y, Tabei SMA, Steck TL. A basic model for the association of ligands with membrane cholesterol: application to cytolysin binding. J Lipid Res 2023; 64:100344. [PMID: 36791915 PMCID: PMC10119614 DOI: 10.1016/j.jlr.2023.100344] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/19/2023] [Accepted: 02/07/2023] [Indexed: 02/16/2023] Open
Abstract
Almost all the cholesterol in cellular membranes is associated with phospholipids in simple stoichiometric complexes. This limits the binding of sterol ligands such as filipin and Perfringolysin O (PFO) to a small fraction of the total. We offer a simple mathematical model that characterizes this complexity. It posits that the cholesterol accessible to ligands has two forms: active cholesterol, which is that not complexed with phospholipids; and extractable cholesterol, that which ligands can capture competitively from the phospholipid complexes. Simulations based on the model match published data for the association of PFO oligomers with liposomes, plasma membranes and the isolated endoplasmic reticulum. The model shows how the binding of a probe greatly underestimates cholesterol abundance when its affinity for the sterol is so weak that it competes poorly with the membrane phospholipids. Two examples are the under-staining of plasma membranes by filipin and the failure of domain D4 of PFO to label their cytoplasmic leaflets. Conversely, the exaggerated staining of endolysosomes suggests that their cholesterol, being uncomplexed, is readily available. The model is also applicable to the association of cholesterol with intrinsic membrane proteins. For example, it supports the hypothesis that the sharp threshold in the regulation of homeostatic ER proteins by cholesterol derives from the cooperativity of their binding to the sterol weakly held by the phospholipid. § Thus, the model explicates the complexity inherent in the binding of ligands like PFO and filipin to the small accessible fraction of membrane cholesterol.
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Affiliation(s)
- Yvonne Lange
- 1Department of Pathology, Rush University Medical Center, Chicago, Il 60612, USA.
| | - S M Ali Tabei
- Department of Physics, University of Northern Iowa, Cedar Falls, Iowa 50614, USA
| | - Theodore L Steck
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Il 60637, USA
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10
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Refinement of Singer-Nicolson fluid-mosaic model by microscopy imaging: Lipid rafts and actin-induced membrane compartmentalization. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184093. [PMID: 36423676 DOI: 10.1016/j.bbamem.2022.184093] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 11/09/2022] [Accepted: 11/10/2022] [Indexed: 11/22/2022]
Abstract
This year celebrates the 50th anniversary of the Singer-Nicolson fluid mosaic model for biological membranes. The next level of sophistication we have achieved for understanding plasma membrane (PM) structures, dynamics, and functions during these 50 years includes the PM interactions with cortical actin filaments and the partial demixing of membrane constituent molecules in the PM, particularly raft domains. Here, first, we summarize our current knowledge of these two structures and emphasize that they are interrelated. Second, we review the structure, molecular dynamics, and function of raft domains, with main focuses on raftophilic glycosylphosphatidylinositol-anchored proteins (GPI-APs) and their signal transduction mechanisms. We pay special attention to the results obtained by single-molecule imaging techniques and other advanced microscopy methods. We also clarify the limitations of present optical microscopy methods for visualizing raft domains, but emphasize that single-molecule imaging techniques can "detect" raft domains associated with molecules of interest in the PM.
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11
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Senior MJT, Monico C, Weatherill EE, Gilbert RJ, Heuck AP, Wallace MI. Single-molecule tracking of perfringolysin O assembly and membrane insertion uncoupling. FEBS J 2023; 290:428-441. [PMID: 35989549 PMCID: PMC10086847 DOI: 10.1111/febs.16596] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 06/22/2022] [Accepted: 08/15/2022] [Indexed: 02/05/2023]
Abstract
We exploit single-molecule tracking and optical single channel recording in droplet interface bilayers to resolve the assembly pathway and pore formation of the archetypical cholesterol-dependent cytolysin nanopore, Perfringolysin O. We follow the stoichiometry and diffusion of Perfringolysin O complexes during assembly with 60 ms temporal resolution and 20 nm spatial precision. Our results suggest individual nascent complexes can insert into the lipid membrane where they continue active assembly. Overall, these data support a model of stepwise irreversible assembly dominated by monomer addition, but with infrequent assembly from larger partial complexes.
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Affiliation(s)
- Michael J T Senior
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, UK
| | - Carina Monico
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, UK.,Department of Chemistry, King's College London, UK
| | - Eve E Weatherill
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, UK.,Department of Chemistry, King's College London, UK
| | - Robert J Gilbert
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, UK
| | - Alejandro P Heuck
- Departments of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA, USA
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12
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Castro IG, Shortill SP, Dziurdzik SK, Cadou A, Ganesan S, Valenti R, David Y, Davey M, Mattes C, Thomas FB, Avraham RE, Meyer H, Fadel A, Fenech EJ, Ernst R, Zaremberg V, Levine TP, Stefan C, Conibear E, Schuldiner M. Systematic analysis of membrane contact sites in Saccharomyces cerevisiae uncovers modulators of cellular lipid distribution. eLife 2022; 11:74602. [DOI: 10.7554/elife.74602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 10/19/2022] [Indexed: 11/11/2022] Open
Abstract
Actively maintained close appositions between organelle membranes, also known as contact sites, enable the efficient transfer of biomolecules between cellular compartments. Several such sites have been described as well as their tethering machineries. Despite these advances we are still far from a comprehensive understanding of the function and regulation of most contact sites. To systematically characterize contact site proteomes, we established a high-throughput screening approach in Saccharomyces cerevisiae based on co-localization imaging. We imaged split fluorescence reporters for six different contact sites, several of which are poorly characterized, on the background of 1165 strains expressing a mCherry-tagged yeast protein that has a cellular punctate distribution (a hallmark of contact sites), under regulation of the strong TEF2 promoter. By scoring both co-localization events and effects on reporter size and abundance, we discovered over 100 new potential contact site residents and effectors in yeast. Focusing on several of the newly identified residents, we identified three homologs of Vps13 and Atg2 that are residents of multiple contact sites. These proteins share their lipid transport domain, thus expanding this family of lipid transporters. Analysis of another candidate, Ypr097w, which we now call Lec1 (Lipid-droplet Ergosterol Cortex 1), revealed that this previously uncharacterized protein dynamically shifts between lipid droplets and the cell cortex, and plays a role in regulation of ergosterol distribution in the cell. Overall, our analysis expands the universe of contact site residents and effectors and creates a rich database to mine for new functions, tethers, and regulators.
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Affiliation(s)
| | - Shawn P Shortill
- Centre for Molecular Medicine and Therapeutics, British Columbia Children’s Hospital Research Institute, University of British Columbia
- Department of Medical Genetics, University of British Columbia
| | - Samantha Katarzyna Dziurdzik
- Centre for Molecular Medicine and Therapeutics, British Columbia Children’s Hospital Research Institute, University of British Columbia
- Department of Medical Genetics, University of British Columbia
| | - Angela Cadou
- Laboratory for Molecular Cell Biology, University College London
| | | | - Rosario Valenti
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Yotam David
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Michael Davey
- Centre for Molecular Medicine and Therapeutics, British Columbia Children’s Hospital Research Institute, University of British Columbia
| | - Carsten Mattes
- Medical Biochemistry and Molecular Biology, PZMS, Medical Faculty, Saarland University
| | - Ffion B Thomas
- Laboratory for Molecular Cell Biology, University College London
| | | | - Hadar Meyer
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Amir Fadel
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Emma J Fenech
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Robert Ernst
- Medical Biochemistry and Molecular Biology, PZMS, Medical Faculty, Saarland University
| | | | - Tim P Levine
- UCL Institute of Ophthalmology, University College London
| | | | - Elizabeth Conibear
- Centre for Molecular Medicine and Therapeutics, British Columbia Children’s Hospital Research Institute, University of British Columbia
- Department of Medical Genetics, University of British Columbia
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science
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13
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Yamaji-Hasegawa A, Murate M, Inaba T, Dohmae N, Sato M, Fujimori F, Sako Y, Greimel P, Kobayashi T. A novel sterol-binding protein reveals heterogeneous cholesterol distribution in neurite outgrowth and in late endosomes/lysosomes. Cell Mol Life Sci 2022; 79:324. [PMID: 35644822 PMCID: PMC11072113 DOI: 10.1007/s00018-022-04339-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 04/26/2022] [Accepted: 04/29/2022] [Indexed: 11/24/2022]
Abstract
We identified a mushroom-derived protein, maistero-2 that specifically binds 3-hydroxy sterol including cholesterol (Chol). Maistero-2 bound lipid mixture in Chol-dependent manner with a binding threshold of around 30%. Changing lipid composition did not significantly affect the threshold concentration. EGFP-maistero-2 labeled cell surface and intracellular organelle Chol with higher sensitivity than that of well-established Chol probe, D4 fragment of perfringolysin O. EGFP-maistero-2 revealed increase of cell surface Chol during neurite outgrowth and heterogeneous Chol distribution between CD63-positive and LAMP1-positive late endosomes/lysosomes. The absence of strictly conserved Thr-Leu pair present in Chol-dependent cytolysins suggests a distinct Chol-binding mechanism for maistero-2.
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Affiliation(s)
| | - Motohide Murate
- Lipid Biology Laboratory, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
- Cellular Informatics Laboratory, RIKEN CPR, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
- UMR 7021, CNRS, Université de Strasbourg, 67401, Illkirch, France
| | - Takehiko Inaba
- Lipid Biology Laboratory, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
- Cellular Informatics Laboratory, RIKEN CPR, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Naoshi Dohmae
- Biomolecular Characterization Unit, RIKEN CSRS, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Masayuki Sato
- Yukiguni Maitake Co, Ltd. Yokawa 89, Minamiuonuma, Niigata, 949-6695, Japan
| | - Fumihiro Fujimori
- Laboratory of Biological Science and Technology, Tokyo Kasei University, 1-18-1 Kaga, Itabashi, Tokyo, 173-8062, Japan
| | - Yasushi Sako
- Cellular Informatics Laboratory, RIKEN CPR, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Peter Greimel
- Lipid Biology Laboratory, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Toshihide Kobayashi
- Lipid Biology Laboratory, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan.
- Cellular Informatics Laboratory, RIKEN CPR, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan.
- UMR 7021, CNRS, Université de Strasbourg, 67401, Illkirch, France.
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14
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Hodel AW, Rudd-Schmidt JA, Trapani JA, Voskoboinik I, Hoogenboom BW. Lipid specificity of the immune effector perforin. Faraday Discuss 2021; 232:236-255. [PMID: 34545865 PMCID: PMC8704153 DOI: 10.1039/d0fd00043d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 08/13/2020] [Indexed: 12/16/2022]
Abstract
Perforin is a pore forming protein used by cytotoxic T lymphocytes to remove cancerous or virus-infected cells during the immune response. During the response, the lymphocyte membrane becomes refractory to perforin function by accumulating densely ordered lipid rafts and externalizing negatively charged lipid species. The dense membrane packing lowers the capacity of perforin to bind, and the negatively charged lipids scavenge any residual protein before pore formation. Using atomic force microscopy on model membrane systems, we here provide insight into the molecular basis of perforin lipid specificity.
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Affiliation(s)
- Adrian W Hodel
- Killer Cell Biology Laboratory, Peter MacCallum Cancer Centre, 305 Grattan Street, Melbourne, VIC 3000, Australia.
- London Centre for Nanotechnology, University College London, 19 Gordon Street, London WC1H 0AH, UK.
- Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Jesse A Rudd-Schmidt
- Killer Cell Biology Laboratory, Peter MacCallum Cancer Centre, 305 Grattan Street, Melbourne, VIC 3000, Australia.
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, VIC 3000, Australia
| | - Joseph A Trapani
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, VIC 3000, Australia
- Cancer Cell Death Laboratory, Peter MacCallum Cancer Centre, 305 Grattan Street, Melbourne, VIC 3000, Australia
| | - Ilia Voskoboinik
- Killer Cell Biology Laboratory, Peter MacCallum Cancer Centre, 305 Grattan Street, Melbourne, VIC 3000, Australia.
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, VIC 3000, Australia
| | - Bart W Hoogenboom
- London Centre for Nanotechnology, University College London, 19 Gordon Street, London WC1H 0AH, UK.
- Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
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15
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Kinnebrew M, Luchetti G, Sircar R, Frigui S, Viti LV, Naito T, Beckert F, Saheki Y, Siebold C, Radhakrishnan A, Rohatgi R. Patched 1 reduces the accessibility of cholesterol in the outer leaflet of membranes. eLife 2021; 10:e70504. [PMID: 34698632 PMCID: PMC8654371 DOI: 10.7554/elife.70504] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 10/25/2021] [Indexed: 11/13/2022] Open
Abstract
A long-standing mystery in vertebrate Hedgehog signaling is how Patched 1 (PTCH1), the receptor for Hedgehog ligands, inhibits the activity of Smoothened, the protein that transmits the signal across the membrane. We previously proposed (Kinnebrew et al., 2019) that PTCH1 inhibits Smoothened by depleting accessible cholesterol from the ciliary membrane. Using a new imaging-based assay to directly measure the transport activity of PTCH1, we find that PTCH1 depletes accessible cholesterol from the outer leaflet of the plasma membrane. This transport activity is terminated by binding of Hedgehog ligands to PTCH1 or by dissipation of the transmembrane potassium gradient. These results point to the unexpected model that PTCH1 moves cholesterol from the outer to the inner leaflet of the membrane in exchange for potassium ion export in the opposite direction. Our study provides a plausible solution for how PTCH1 inhibits SMO by changing the organization of cholesterol in membranes and establishes a general framework for studying how proteins change cholesterol accessibility to regulate membrane-dependent processes in cells.
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Affiliation(s)
- Maia Kinnebrew
- Department of Biochemistry and Medicine, Stanford University School of MedicineStanfordUnited States
| | - Giovanni Luchetti
- Department of Biochemistry and Medicine, Stanford University School of MedicineStanfordUnited States
- Department of Physiological Chemistry, GenentechSouth San FranciscoUnited States
| | - Ria Sircar
- Department of Biochemistry and Medicine, Stanford University School of MedicineStanfordUnited States
| | - Sara Frigui
- Department of Biochemistry and Medicine, Stanford University School of MedicineStanfordUnited States
| | - Lucrezia Vittoria Viti
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of OxfordOxfordUnited Kingdom
| | - Tomoki Naito
- Lee Kong Chian School of Medicine, Nanyang Technological UniversitySingaporeSingapore
| | - Francis Beckert
- Department of Biochemistry and Medicine, Stanford University School of MedicineStanfordUnited States
| | - Yasunori Saheki
- Lee Kong Chian School of Medicine, Nanyang Technological UniversitySingaporeSingapore
| | - Christian Siebold
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of OxfordOxfordUnited Kingdom
| | - Arun Radhakrishnan
- Department of Molecular Genetics, University of Texas Southwestern Medical CenterDallasUnited States
| | - Rajat Rohatgi
- Department of Biochemistry and Medicine, Stanford University School of MedicineStanfordUnited States
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16
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Steck TL, Tabei SMA, Lange Y. A basic model for cell cholesterol homeostasis. Traffic 2021; 22:471-481. [PMID: 34528339 DOI: 10.1111/tra.12816] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 08/26/2021] [Accepted: 09/13/2021] [Indexed: 11/30/2022]
Abstract
Cells manage their cholesterol by negative feedback using a battery of sterol-responsive proteins. How these activities are coordinated so as to specify the abundance and distribution of the sterol is unclear. We present a simple mathematical model that addresses this question. It assumes that almost all of the cholesterol is associated with phospholipids in stoichiometric complexes. A small fraction of the sterol is uncomplexed and thermodynamically active. It equilibrates among the organelles, setting their sterol level according to the affinity of their phospholipids. The activity of the homeostatic proteins in the cytoplasmic membranes is then set by their fractional saturation with uncomplexed cholesterol in competition with the phospholipids. The high-affinity phospholipids in the plasma membrane (PM) are filled to near stoichiometric equivalence, giving it most of the cell sterol. Notably, the affinity of the phospholipids in the endomembranes (EMs) is lower by orders of magnitude than that of the phospholipids in the PM. Thus, the small amount of sterol in the EMs rests far below stoichiometric capacity. Simulations match a variety of experimental data. The model captures the essence of cell cholesterol homeostasis, makes coherent a diverse set of experimental findings, provides a surprising prediction and suggests new experiments.
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Affiliation(s)
- Theodore L Steck
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA
| | - S M Ali Tabei
- Department of Physics, University of Northern Iowa, Cedar Falls, Iowa, USA
| | - Yvonne Lange
- Department of Pathology, Rush University Medical Center, Chicago, Illinois, USA
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17
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Ridone P, Pandzic E, Vassalli M, Cox CD, Macmillan A, Gottlieb PA, Martinac B. Disruption of membrane cholesterol organization impairs the activity of PIEZO1 channel clusters. J Gen Physiol 2021; 152:151885. [PMID: 32582958 PMCID: PMC7398139 DOI: 10.1085/jgp.201912515] [Citation(s) in RCA: 80] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 05/12/2020] [Indexed: 11/20/2022] Open
Abstract
The human mechanosensitive ion channel PIEZO1 is gated by membrane tension and regulates essential biological processes such as vascular development and erythrocyte volume homeostasis. Currently, little is known about PIEZO1 plasma membrane localization and organization. Using a PIEZO1-GFP fusion protein, we investigated whether cholesterol enrichment or depletion by methyl-β-cyclodextrin (MBCD) and disruption of membrane cholesterol organization by dynasore affects PIEZO1-GFP's response to mechanical force. Electrophysiological recordings in the cell-attached configuration revealed that MBCD caused a rightward shift in the PIEZO1-GFP pressure-response curve, increased channel latency in response to mechanical stimuli, and markedly slowed channel inactivation. The same effects were seen in native PIEZO1 in N2A cells. STORM superresolution imaging revealed that, at the nanoscale, PIEZO1-GFP channels in the membrane associate as clusters sensitive to membrane manipulation. Both cluster distribution and diffusion rates were affected by treatment with MBCD (5 mM). Supplementation of polyunsaturated fatty acids appeared to sensitize the PIEZO1-GFP response to applied pressure. Together, our results indicate that PIEZO1 function is directly dependent on the membrane composition and lateral organization of membrane cholesterol domains, which coordinate the activity of clustered PIEZO1 channels.
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Affiliation(s)
- Pietro Ridone
- The Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
| | - Elvis Pandzic
- Biomedical Imaging Facility, Mark Wainwright Analytical Centre, Lowy Cancer Research Centre, The University of New South Wales, Sydney, NSW, Australia
| | - Massimo Vassalli
- Institute of Biophysics, National Research Council, Genova, Italy
| | - Charles D Cox
- The Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia.,St. Vincent's Clinical School, University of New South Wales, Darlinghurst, NSW, Australia
| | - Alexander Macmillan
- Biomedical Imaging Facility, Mark Wainwright Analytical Centre, Lowy Cancer Research Centre, The University of New South Wales, Sydney, NSW, Australia
| | - Philip A Gottlieb
- Physiology and Biophysics, State University of New York at Buffalo, Buffalo, NY
| | - Boris Martinac
- The Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia.,St. Vincent's Clinical School, University of New South Wales, Darlinghurst, NSW, Australia
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18
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Encinar Del Dedo J, Fernández-Golbano IM, Pastor L, Meler P, Ferrer-Orta C, Rebollo E, Geli MI. Coupled sterol synthesis and transport machineries at ER-endocytic contact sites. J Cell Biol 2021; 220:212484. [PMID: 34283201 PMCID: PMC8294947 DOI: 10.1083/jcb.202010016] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Revised: 05/27/2021] [Accepted: 06/29/2021] [Indexed: 12/17/2022] Open
Abstract
Sterols are unevenly distributed within cellular membranes. How their biosynthetic and transport machineries are organized to generate heterogeneity is largely unknown. We previously showed that the yeast sterol transporter Osh2 is recruited to endoplasmic reticulum (ER)–endocytic contacts to facilitate actin polymerization. We now find that a subset of sterol biosynthetic enzymes also localizes at these contacts and interacts with Osh2 and the endocytic machinery. Following the sterol dynamics, we show that Osh2 extracts sterols from these subdomains, which we name ERSESs (ER sterol exit sites). Further, we demonstrate that coupling of the sterol synthesis and transport machineries is required for endocytosis in mother cells, but not in daughters, where plasma membrane loading with accessible sterols and endocytosis are linked to secretion.
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Affiliation(s)
| | | | - Laura Pastor
- Institute for Molecular Biology of Barcelona, Spanish Research Council, Barcelona, Spain
| | - Paula Meler
- Institute for Molecular Biology of Barcelona, Spanish Research Council, Barcelona, Spain
| | - Cristina Ferrer-Orta
- Institute for Molecular Biology of Barcelona, Spanish Research Council, Barcelona, Spain
| | - Elena Rebollo
- Institute for Molecular Biology of Barcelona, Spanish Research Council, Barcelona, Spain
| | - Maria Isabel Geli
- Institute for Molecular Biology of Barcelona, Spanish Research Council, Barcelona, Spain
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19
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Schoop V, Martello A, Eden ER, Höglinger D. Cellular cholesterol and how to find it. Biochim Biophys Acta Mol Cell Biol Lipids 2021; 1866:158989. [PMID: 34118431 DOI: 10.1016/j.bbalip.2021.158989] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 06/01/2021] [Accepted: 06/02/2021] [Indexed: 01/06/2023]
Abstract
Cholesterol is an essential component of eukaryotic cellular membranes. Information about its subcellular localization and transport pathways inside cells are key for the understanding and treatment of cholesterol-related diseases. In this review we give an overview over the most commonly used methods that contributed to our current understanding of subcellular cholesterol localization and transport routes. First, we discuss methods that provide insights into cholesterol metabolism based on readouts of downstream effects such as esterification. Subsequently, we focus on the use of cholesterol-binding molecules as probes that facilitate visualization and quantification of sterols inside of cells. Finally, we explore different analogues of cholesterol which, when taken up by living cells, are integrated and transported in a similar fashion as endogenous sterols. Taken together, we highlight the challenges and advantages of each method such that researchers studying aspects of cholesterol transport may choose the most pertinent approach for their problem.
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Affiliation(s)
- Valentin Schoop
- Heidelberg University Biochemistry Center (BZH), 69120 Heidelberg, Germany
| | - Andrea Martello
- University College London (UCL), Institute of Ophthalmology, EC1V 9EL London, United Kingdom
| | - Emily R Eden
- University College London (UCL), Institute of Ophthalmology, EC1V 9EL London, United Kingdom
| | - Doris Höglinger
- Heidelberg University Biochemistry Center (BZH), 69120 Heidelberg, Germany.
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20
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Buwaneka P, Ralko A, Liu SL, Cho W. Evaluation of the available cholesterol concentration in the inner leaflet of the plasma membrane of mammalian cells. J Lipid Res 2021; 62:100084. [PMID: 33964305 PMCID: PMC8178126 DOI: 10.1016/j.jlr.2021.100084] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 04/21/2021] [Accepted: 04/27/2021] [Indexed: 12/11/2022] Open
Abstract
Cholesterol is an essential component of the mammalian plasma membrane involved in diverse cellular processes. Our recent quantitative imaging analysis using ratiometric cholesterol sensors showed that the available cholesterol concentration in the inner leaflet of the plasma membrane (IPM) is low in unstimulated cells and increased in a stimulus-specific manner to trigger cell signaling events. However, the transbilayer distribution of cholesterol in the plasma membrane of mammalian cells remains controversial. Here we report a systematic and rigorous evaluation of basal IPM cholesterol levels in a wide range of mammalian cells with different properties employing cholesterol sensors derived from the D4 domain of the Perfringolysin O toxin and a sterol-transfer protein, Osh4. Results consistently showed that, although basal IPM cholesterol levels vary significantly among cells, they remain significantly lower than cholesterol levels in the outer leaflets. We found that IPM cholesterol levels were particularly low in all tested primary cells. These results support the universality of the low basal IPM cholesterol concentration under physiological conditions. We also report here the presence of sequestered IPM cholesterol pools, which may become available to cytosolic proteins under certain physiological conditions. We hypothesize that these pools may partly account for the low basal level of available IPM cholesterol. In conclusion, we provide new experimental data that confirm the asymmetric transbilayer distribution of the plasma membrane cholesterol, which may contribute to regulation of various cellular signaling processes at the plasma membrane.
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Affiliation(s)
- Pawanthi Buwaneka
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL, USA
| | - Arthur Ralko
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL, USA
| | - Shu-Lin Liu
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL, USA
| | - Wonhwa Cho
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL, USA.
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21
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Tang Y, Guo H, Vermeulen AJ, Heuck AP. Topological analysis of type 3 secretion translocons in native membranes. Methods Enzymol 2021; 649:397-429. [PMID: 33712194 DOI: 10.1016/bs.mie.2021.01.036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PFPs (Pore-forming proteins) perforate cellular membranes to create an aqueous pore and allow the passage of ions and polar molecules. The molecular mechanisms for many of these PFPs have been elucidated by combining high resolution structural information of these proteins with biochemical and biophysical approaches. However, some PFPs do not adopt stable conformations and are difficult to study in vitro. An example of these proteins are the bacterial Type 3 Secretion (T3S) translocators. The translocators are secreted by the bacterium and insert into the target cell membrane to form a translocon pore providing a portal for the passage of T3S toxins into eukaryotic cells. Given the important role that the T3S systems play in pathogenesis, methods to study these translocon pores in cellular membranes are needed. Using a combination of protein modifications and methods to selectively permeate and solubilized eukaryotic membranes, we have established an experimental procedure to analyze the topology of the Pseudomonas aeruginosa T3S translocon using P. aeruginosa strain variants and HeLa cell lines.
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Affiliation(s)
- Yuzhou Tang
- Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA, United States
| | - Hanling Guo
- Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA, United States
| | - Arjan J Vermeulen
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA, United States
| | - Alejandro P Heuck
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA, United States.
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22
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Abstract
Pore forming proteins are released as water-soluble monomers that form-mostly oligomeric-pores in target membranes. Our understanding of such pore formation relies in part on the direct visualization of their assemblies on and in the membrane. Here, we discuss the application of atomic force microscopy (AFM) to visualize and understand membrane pore formation, illustrated specifically by studies of proteins of the MACPF/CDC superfamily on supported lipid bilayers. Besides detailed protocols, we also point out common imaging artefacts and strategies to avoid them, and briefly outline how AFM can be effectively used in conjunction with other methods.
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Affiliation(s)
- Adrian W Hodel
- Killer Cell Biology Laboratory, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
| | - Katharine Hammond
- National Physical Laboratory, Teddington, United Kingdom; London Centre for Nanotechnology, University College London, London, United Kingdom; Department of Physics & Astronomy, University College London, London, United Kingdom
| | - Bart W Hoogenboom
- London Centre for Nanotechnology, University College London, London, United Kingdom; Department of Physics & Astronomy, University College London, London, United Kingdom.
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23
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Krawczyk PA, Laub M, Kozik P. To Kill But Not Be Killed: Controlling the Activity of Mammalian Pore-Forming Proteins. Front Immunol 2020; 11:601405. [PMID: 33281828 PMCID: PMC7691655 DOI: 10.3389/fimmu.2020.601405] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 10/20/2020] [Indexed: 01/01/2023] Open
Abstract
Pore-forming proteins (PFPs) are present in all domains of life, and play an important role in host-pathogen warfare and in the elimination of cancers. They can be employed to deliver specific effectors across membranes, to disrupt membrane integrity interfering with cell homeostasis, and to lyse membranes either destroying intracellular organelles or entire cells. Considering the destructive potential of PFPs, it is perhaps not surprising that mechanisms controlling their activity are remarkably complex, especially in multicellular organisms. Mammalian PFPs discovered to date include the complement membrane attack complex (MAC), perforins, as well as gasdermins. While the primary function of perforin-1 and gasdermins is to eliminate infected or cancerous host cells, perforin-2 and MAC can target pathogens directly. Yet, all mammalian PFPs are in principle capable of generating pores in membranes of healthy host cells which-if uncontrolled-could have dire, and potentially lethal consequences. In this review, we will highlight the strategies employed to protect the host from destruction by endogenous PFPs, while enabling timely and efficient elimination of target cells.
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Affiliation(s)
- Patrycja A Krawczyk
- MRC Laboratory of Molecular Biology, Protein and Nucleic Acid Chemistry Division, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Marco Laub
- MRC Laboratory of Molecular Biology, Protein and Nucleic Acid Chemistry Division, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Patrycja Kozik
- MRC Laboratory of Molecular Biology, Protein and Nucleic Acid Chemistry Division, Cambridge Biomedical Campus, Cambridge, United Kingdom
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24
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Lange Y, Steck TL. Active cholesterol 20 years on. Traffic 2020; 21:662-674. [PMID: 32930466 DOI: 10.1111/tra.12762] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 09/08/2020] [Accepted: 09/10/2020] [Indexed: 12/13/2022]
Abstract
This review considers the following hypotheses, some well-supported and some speculative. Almost all of the sterol molecules in plasma membranes are associated with bilayer phospholipids in complexes of varied strength and stoichiometry. These complexes underlie many of the material properties of the bilayer. The small fraction of cholesterol molecules exceeding the binding capacity of the phospholipids is thermodynamically active and serves diverse functions. It circulates briskly among the cell membranes, particularly through contact sites linking the organelles. Active cholesterol provides the upstream feedback signal to multiple mechanisms governing plasma membrane homeostasis, pegging the sterol level to a threshold set by its phospholipids. Active cholesterol could also be the cargo for various inter-organelle transporters and the form excreted from cells by reverse transport. Furthermore, it is integral to the function of caveolae; a mediator of Hedgehog regulation; and a ligand for the binding of cytolytic toxins to membranes. Active cholesterol modulates a variety of plasma membrane proteins-receptors, channels and transporters-at least in vitro.
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Affiliation(s)
- Yvonne Lange
- Department of Pathology, Rush University Medical Center, Chicago, Illinois, USA
| | - Theodore L Steck
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA
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Marek M, Vincenzetti V, Martin SG. Sterol biosensor reveals LAM-family Ltc1-dependent sterol flow to endosomes upon Arp2/3 inhibition. J Cell Biol 2020; 219:e202001147. [PMID: 32320462 PMCID: PMC7265315 DOI: 10.1083/jcb.202001147] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 03/03/2020] [Accepted: 03/04/2020] [Indexed: 01/01/2023] Open
Abstract
Sterols are crucial components of biological membranes, which are synthetized in the ER and accumulate in the plasma membrane (PM). Here, by applying a genetically encoded sterol biosensor (D4H), we visualize a sterol flow between PM and endosomes in the fission yeast Schizosaccharomyces pombe. Using time-lapse and correlative light-electron microscopy, we found that inhibition of Arp2/3-dependent F-actin assembly promotes the reversible relocalization of D4H from the PM to internal sterol-rich compartments (STRIC) labeled by synaptobrevin Syb1. Retrograde sterol internalization to STRIC is independent of endocytosis or an intact Golgi, but depends on Ltc1, a LAM/StARkin-family protein localized to ER-PM contact sites. The PM in ltc1Δ cells over-accumulates sterols and upon Arp2/3 inhibition forms extended ER-interacting invaginations, indicating that sterol transfer contributes to PM size homeostasis. Anterograde sterol movement from STRIC is independent of canonical vesicular trafficking but requires Arp2/3, suggesting a novel role for this complex. Thus, transfer routes orthogonal to vesicular trafficking govern the flow of sterols in the cell.
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Affiliation(s)
| | | | - Sophie G. Martin
- Department of Fundamental Microbiology, University of Lausanne, Switzerland
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26
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Petrov AM, Mast N, Li Y, Denker J, Pikuleva IA. Brain sterol flux mediated by cytochrome P450 46A1 affects membrane properties and membrane-dependent processes. Brain Commun 2020; 2. [PMID: 32661514 PMCID: PMC7357967 DOI: 10.1093/braincomms/fcaa043] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Cytochrome P450 46A1 encoded by CYP46A1 catalyzes cholesterol 24-hydroxylation and is a CNS-specific enzyme that controls cholesterol removal and turnover in the brain. Accumulating data suggest that increases in cytochrome P450 46A1 activity in mouse models of common neurodegenerative diseases affect various, apparently unlinked biological processes and pathways. Yet, the underlying reason for these multiple enzyme activity effects is currently unknown. Herein, we tested the hypothesis that cytochrome P450 46A1-mediated sterol flux alters physico-chemical properties of the plasma membranes and thereby membrane-dependent events. We used 9-month old 5XFAD mice (an Alzheimer's disease model) treated for 6 months with the anti-HIV drug efavirenz. These animals have previously been shown to have improved behavioral performance, increased cytochrome P450 46A1 activity in the brain, and increased sterol flux through the plasma membranes. We further examined 9-month old Cyp46a1 -/- mice, which have previously been observed to have cognitive deficits and decreased sterol flux through brain membranes. Synaptosomal fractions from the brain of efavirenz-treated 5XFAD mice had essentially unchanged cholesterol levels as compared to control 5XFAD mice. However with efavirenz treatment in these mice, there were changes in the membrane properties (increased cholesterol accessibility, ordering, osmotic resistance, and thickness) as well as total glutamate content and ability to release glutamate in response to mild stimulation. Similarly, the cholesterol content in synaptosomal fractions from the brain of Cyp46a1 -/- mice was essentially the same as in wild type mice but knockout of Cyp46a1 was associated with changes in membrane properties and glutamate content and its exocytotic release. Changes in Cyp46a1 -/- mice were in the opposite direction to those observed in efavirenz-treated vs control 5XFAD mice. Incubation of synaptosomal fractions with the inhibitors of glycogen synthase kinase 3, cyclin-dependent kinase 5, protein phosphatase 1/2A or calcineurin, and protein phosphatase 2B revealed that increased sterol flux in efavirenz-treated vs control 5XFAD mice affected the ability of all four enzymes to modulate glutamate release. In contrast, in Cyp46a1 -/- vs wild type mice, decreased sterol flux altered the ability of only cyclin-dependent kinase 5 and protein phosphatase 2B to regulate the glutamate release. Collectively, our results support cytochrome P450 46A1-mediated sterol flux as an important contributor to the fundamental properties of the membranes, protein phosphorylation, and synaptic transmission Also, our data provide an explanation of how one enzyme, cytochrome P450 46A1, can affect multiple pathways and processes and serve as a common potential target for several neurodegenerative disorders.
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Affiliation(s)
- Alexey M Petrov
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH USA
| | - Natalia Mast
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH USA
| | - Young Li
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH USA
| | - John Denker
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH USA
| | - Irina A Pikuleva
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH USA
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27
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Dambal S, Alfaqih M, Sanders S, Maravilla E, Ramirez-Torres A, Galvan GC, Reis-Sobreiro M, Rotinen M, Driver LM, Behrove MS, Talisman TJ, Yoon J, You S, Turkson J, Chi JT, Freeman MR, Macias E, Freedland SJ. 27-Hydroxycholesterol Impairs Plasma Membrane Lipid Raft Signaling as Evidenced by Inhibition of IL6-JAK-STAT3 Signaling in Prostate Cancer Cells. Mol Cancer Res 2020; 18:671-684. [PMID: 32019810 DOI: 10.1158/1541-7786.mcr-19-0974] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 01/04/2020] [Accepted: 01/29/2020] [Indexed: 01/04/2023]
Abstract
We recently reported that restoring the CYP27A1-27hydroxycholesterol axis had antitumor properties. Thus, we sought to determine the mechanism by which 27HC exerts its anti-prostate cancer effects. As cholesterol is a major component of membrane microdomains known as lipid rafts, which localize receptors and facilitate cellular signaling, we hypothesized 27HC would impair lipid rafts, using the IL6-JAK-STAT3 axis as a model given its prominent role in prostate cancer. As revealed by single molecule imaging of DU145 prostate cancer cells, 27HC treatment significantly reduced detected cholesterol density on the plasma membranes. Further, 27HC treatment of constitutively active STAT3 DU145 prostate cancer cells reduced STAT3 activation and slowed tumor growth in vitro and in vivo. 27HC also blocked IL6-mediated STAT3 phosphorylation in nonconstitutively active STAT3 cells. Mechanistically, 27HC reduced STAT3 homodimerization, nuclear translocation, and decreased STAT3 DNA occupancy at target gene promoters. Combined treatment with 27HC and STAT3 targeting molecules had additive and synergistic effects on proliferation and migration, respectively. Hallmark IL6-JAK-STAT gene signatures positively correlated with CYP27A1 gene expression in a large set of human metastatic castrate-resistant prostate cancers and in an aggressive prostate cancer subtype. This suggests STAT3 activation may be a resistance mechanism for aggressive prostate cancers that retain CYP27A1 expression. In summary, our study establishes a key mechanism by which 27HC inhibits prostate cancer by disrupting lipid rafts and blocking STAT3 activation. IMPLICATIONS: Collectively, these data show that modulation of intracellular cholesterol by 27HC can inhibit IL6-JAK-STAT signaling and may synergize with STAT3-targeted compounds.
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Affiliation(s)
- Shweta Dambal
- Department of Pathology, Duke University School of Medicine, Durham, North Carolina
| | | | - Sergio Sanders
- Department of Surgery, Samuel Oschin Comprehensive Cancer Center, Cedars-Sinai Medical Center, Los Angeles, California
| | - Erick Maravilla
- Department of Pathology, Duke University School of Medicine, Durham, North Carolina
| | - Adela Ramirez-Torres
- Department of Surgery, Samuel Oschin Comprehensive Cancer Center, Cedars-Sinai Medical Center, Los Angeles, California
| | - Gloria C Galvan
- Department of Surgery, Samuel Oschin Comprehensive Cancer Center, Cedars-Sinai Medical Center, Los Angeles, California
| | - Mariana Reis-Sobreiro
- Department of Surgery, Samuel Oschin Comprehensive Cancer Center, Cedars-Sinai Medical Center, Los Angeles, California
| | - Mirja Rotinen
- Department of Surgery, Samuel Oschin Comprehensive Cancer Center, Cedars-Sinai Medical Center, Los Angeles, California
| | - Lucy M Driver
- Department of Pathology, Duke University School of Medicine, Durham, North Carolina
| | - Matthew S Behrove
- Department of Molecular Medicine, Beckman Research Institute of the City of Hope Comprehensive Cancer Center, Duarte, California
| | - Tijana Jovanovic Talisman
- Department of Molecular Medicine, Beckman Research Institute of the City of Hope Comprehensive Cancer Center, Duarte, California
| | - Junhee Yoon
- Department of Surgery, Samuel Oschin Comprehensive Cancer Center, Cedars-Sinai Medical Center, Los Angeles, California
| | - Sungyong You
- Department of Surgery, Samuel Oschin Comprehensive Cancer Center, Cedars-Sinai Medical Center, Los Angeles, California
| | - James Turkson
- Department of Biomedical Science, Samuel Oschin Comprehensive Cancer Center, Cedars-Sinai Medical Center, Los Angeles, California
| | - Jen-Tsan Chi
- Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina
| | - Michael R Freeman
- Department of Surgery, Samuel Oschin Comprehensive Cancer Center, Cedars-Sinai Medical Center, Los Angeles, California.,Department of Biomedical Science, Samuel Oschin Comprehensive Cancer Center, Cedars-Sinai Medical Center, Los Angeles, California
| | - Everardo Macias
- Department of Pathology, Duke University School of Medicine, Durham, North Carolina.
| | - Stephen J Freedland
- Department of Surgery, Samuel Oschin Comprehensive Cancer Center, Cedars-Sinai Medical Center, Los Angeles, California. .,Section of Urology, Durham VA Medical Center, Durham, North Carolina
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28
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Pleckaityte M. Cholesterol-Dependent Cytolysins Produced by Vaginal Bacteria: Certainties and Controversies. Front Cell Infect Microbiol 2020; 9:452. [PMID: 31998661 PMCID: PMC6966277 DOI: 10.3389/fcimb.2019.00452] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 12/12/2019] [Indexed: 01/16/2023] Open
Abstract
Bacterial vaginosis (BV) is a vaginal anaerobic dysbiosis that affects women of reproductive age worldwide. BV is microbiologically characterized by the depletion of vaginal lactobacilli and the overgrowth of anaerobic bacterial species. Accumulated evidence suggests that Gardnerella spp. have a pivotal role among BV-associated bacteria in the initiation and development of BV. However, Gardnerella spp. often colonize healthy women. Lactobacillus iners is considered as a prevalent constituent of healthy vaginal microbiota, and is abundant in BV. Gardnerella spp. and L. iners secrete the toxins vaginolysin (VLY) and inerolysin (INY), which have structural and activity features attributed to cholesterol-dependent cytolysins (CDCs). CDCs are produced by many pathogenic bacteria as virulence factors that participate in various stages of disease progression by forming lytic and non-lytic pores in cell membranes or via pore-independent pathways. VLY is expressed in the majority of Gardnerella spp. isolates; less is known about the prevalence of the gene that encodes INY. INY is a classical CDC; membrane cholesterol acts a receptor for INY. VLY uses human CD59 as its receptor, although cholesterol remains indispensable for VLY pore-forming activity. INY-induced damage of artificial membranes is directly dependent on cholesterol concentration in the bilayer, whereas VLY-induced damage occurs with high levels of membrane cholesterol (>40 mol%). VLY primarily forms membrane-embedded complete rings in the synthetic bilayer, whereas INY forms arciform structures with smaller pore sizes. VLY activity is high at elevated pH, which is characteristic of BV, whereas INY activity is high at more acidic pH, which is specific for a healthy vagina. Increased VLY levels in vaginal mucosa in vivo were associated with clinical indicators of BV. However, experimental evidence is lacking for the specific roles of VLY and INY in BV. The interplay between vaginal bacterial species affects the expression of the gene encoding VLY, thereby modulating the virulence of Gardnerella spp. This review discusses the current evidence for VLY and INY cytolysins, including their structures and activities, factors affecting their expression, and their potential impacts on the progression of anaerobic dysbiosis.
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Affiliation(s)
- Milda Pleckaityte
- Laboratory of Immunology and Cell Biology, Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania
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29
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Naito T, Ercan B, Krshnan L, Triebl A, Koh DHZ, Wei FY, Tomizawa K, Torta FT, Wenk MR, Saheki Y. Movement of accessible plasma membrane cholesterol by the GRAMD1 lipid transfer protein complex. eLife 2019; 8:51401. [PMID: 31724953 PMCID: PMC6905856 DOI: 10.7554/elife.51401] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 11/13/2019] [Indexed: 12/18/2022] Open
Abstract
Cholesterol is a major structural component of the plasma membrane (PM). The majority of PM cholesterol forms complexes with other PM lipids, making it inaccessible for intracellular transport. Transition of PM cholesterol between accessible and inaccessible pools maintains cellular homeostasis, but how cells monitor the accessibility of PM cholesterol remains unclear. We show that endoplasmic reticulum (ER)-anchored lipid transfer proteins, the GRAMD1s, sense and transport accessible PM cholesterol to the ER. GRAMD1s bind to one another and populate ER-PM contacts by sensing a transient expansion of the accessible pool of PM cholesterol via their GRAM domains. They then facilitate the transport of this cholesterol via their StART-like domains. Cells that lack all three GRAMD1s exhibit striking expansion of the accessible pool of PM cholesterol as a result of less efficient PM to ER transport of accessible cholesterol. Thus, GRAMD1s facilitate the movement of accessible PM cholesterol to the ER in order to counteract an acute increase of PM cholesterol, thereby activating non-vesicular cholesterol transport. The human body contains trillions of cells. At the outer edge of each cell is the plasma membrane, which protects the cell from the external environment. This membrane is mostly made of fatty molecules known as lipids and about half of these lipids are specifically cholesterol. Human cells can either take up cholesterol that were obtained via the diet or produce it within a compartment of the cell called the endoplasmic reticulum. Cells need to monitor the cholesterol levels in both the endoplasmic reticulum and the plasma membrane in order to regulate the uptake or production of this lipid. For example, if there is too much of cholesterol in the plasma membrane, then the cell transports some to the endoplasmic reticulum to tell it to shut down cholesterol production. However, how these different areas of the cell communicate with each other, and transport cholesterol, has remained unclear. Naito et al. set out to look for key regulators of cholesterol transport and identified a group of endoplasmic reticulum proteins called GRAMD1 proteins. Cholesterol in the plasma membrane is either accessible or inaccessible, meaning it either can or cannot be moved back into the cell. The GRAMD1 proteins sense accessible cholesterol, and experiments with human cells grown in the laboratory showed that, specifically, the GRAMD1 proteins work together in a complex to sense accessible cholesterol at or near the plasma membrane. One particular part of the protein senses when the amount of accessible cholesterol reaches a certain level at the plasma membrane; when this threshold is reached, the complex flips a switch to start the transport of cholesterol to the endoplasmic reticulum and tell it to shut down cholesterol production. This coupling of sensing and transporting lipids by one protein complex also helps maintain the right ratio of accessible and inaccessible cholesterol in the plasma membrane to prevent cells from activating unwanted cell-signaling events. Getting rid of the GRAMD1 proteins in cells, or removing sensing part of these proteins, leads to inefficient transport of cholesterol. A better understanding of how GRAMD1 proteins sense the accessibility of cholesterol could potentially help identify new approaches to control cholesterol transport inside cells. This may in turn eventually lead to new treatments that counteract the defects in cholesterol metabolism seen in some forms of neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease.
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Affiliation(s)
- Tomoki Naito
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Bilge Ercan
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Logesvaran Krshnan
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Alexander Triebl
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Dylan Hong Zheng Koh
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Fan-Yan Wei
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Kazuhito Tomizawa
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Federico Tesio Torta
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Markus R Wenk
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Yasunori Saheki
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.,Institute of Resource Development and Analysis, Kumamoto University, Kumamoto, Japan
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30
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Lamb CL, Price E, Field KP, Dayton C, McIndoo ER, Katahira EJ, Stevens DL, Hobdey SE. Enrichment of Antigen-Specific Class-Switched B Cells from Individuals Naturally Immunized by Infection with Group A Streptococcus. mSphere 2019; 4:e00598-19. [PMID: 31694896 PMCID: PMC6835209 DOI: 10.1128/msphere.00598-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 10/17/2019] [Indexed: 01/17/2023] Open
Abstract
The low frequency of circulating antigen-specific memory B cells is a considerable obstacle in the discovery and development of human monoclonal antibodies for therapeutic application. Here, we evaluate two solid-phase isolation methods to enrich the number of antigen-specific B cells from individuals naturally immunized against streptolysin O (SLO), a key virulence factor and known immunogen of group A streptococcus (GAS). Class-switched B cells obtained from individuals with a history of GAS infection were separated from peripheral blood mononuclear cells (PBMCs) by immunomagnetic methods. SLO-specific B cells were further enriched directly by binding to SLO monomers and captured by streptavidin-coated magnetic microbeads or indirectly by binding a fluorescently labeled SLO-streptavidin tetramer and captured by anti-fluorophore immunomagnetic microbeads. SLO-bound B cells were quantitated by flow cytometry and/or expanded in batch culture to determine IgG specificity. From individuals who have suffered a GAS infection ≥2 years prior, only the direct method enriched SLO-specific B cells, as determined by flow cytometry. Likewise, in batch culture, B cells isolated by the direct method resulted in an average of 375-fold enrichment in anti-SLO IgG, while no enrichment was observed for B cells isolated by the indirect method. The direct method established here provides a simple approach to increase low-frequency antigen-specific B cell populations supporting many downstream applications, such as immortalization of B cells, cloning of immunoglobulin genes, or purification of antibodies from supernatant for future study. Overall, this process is efficient, is inexpensive, and can be applied to many naturally immunogenic antigens.IMPORTANCE Bacteria called group A streptococci can cause a variety of skin and soft tissue infections ranging from mild pharyngitis ("strep throat") to deadly necrotizing fasciitis (sometimes called "flesh-eating" disease). In each case, the development of disease and the degree of tissue damage are mediated by toxins released from the bacteria during infection. Consequently, novel therapies aimed at clearing bacterial toxins are greatly needed. One promising new treatment is the utilization of monoclonal antibodies delivered as an immunotherapeutic for toxin neutralization. However, current methods of antibody development are laborious and costly. Here, we report a method to enrich and increase the detection of highly desirable antigen-specific memory B cells from individuals previously exposed to GAS using a cost-effective and less-time-intensive strategy. We envision that this method will be incorporated into many applications supporting the development of immunotherapeutics.
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Affiliation(s)
- Cheri L Lamb
- Infectious Diseases Section, Veteran Affairs Medical Center, Boise, Idaho, USA
- Idaho Veterans Research and Education Foundation, Boise, Idaho, USA
| | - Emily Price
- Infectious Diseases Section, Veteran Affairs Medical Center, Boise, Idaho, USA
- Idaho Veterans Research and Education Foundation, Boise, Idaho, USA
| | - Kevin P Field
- Infectious Diseases Section, Veteran Affairs Medical Center, Boise, Idaho, USA
- Idaho Veterans Research and Education Foundation, Boise, Idaho, USA
| | - Christopher Dayton
- Infectious Diseases Section, Veteran Affairs Medical Center, Boise, Idaho, USA
- Idaho Veterans Research and Education Foundation, Boise, Idaho, USA
| | - Eric R McIndoo
- Infectious Diseases Section, Veteran Affairs Medical Center, Boise, Idaho, USA
| | - Eva J Katahira
- Infectious Diseases Section, Veteran Affairs Medical Center, Boise, Idaho, USA
| | - Dennis L Stevens
- Infectious Diseases Section, Veteran Affairs Medical Center, Boise, Idaho, USA
- Idaho Veterans Research and Education Foundation, Boise, Idaho, USA
- University of Washington School of Medicine, Seattle, Washington, USA
| | - Sarah E Hobdey
- Infectious Diseases Section, Veteran Affairs Medical Center, Boise, Idaho, USA
- Idaho Veterans Research and Education Foundation, Boise, Idaho, USA
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31
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Inerolysin and vaginolysin, the cytolysins implicated in vaginal dysbiosis, differently impair molecular integrity of phospholipid membranes. Sci Rep 2019; 9:10606. [PMID: 31337831 PMCID: PMC6650466 DOI: 10.1038/s41598-019-47043-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 07/09/2019] [Indexed: 02/07/2023] Open
Abstract
The pore-forming toxins, inerolysin (INY) and vaginolysin (VLY), produced by vaginal bacteria Lactobacillus iners and Gardnerella vaginalis were studied using the artificial cholesterol-rich tethered bilayer membranes (tBLMs) by electrochemical techniques. The electrochemical impedance spectroscopy (EIS) of tBLMs attested for the toxin-induced impairment of the integrity of phospholipid membranes. This observation was in line with the atomic force microscopy data demonstrating formation of oligomeric protein assemblies in tBLMs. These assemblies exhibited different morphologies: VLY mostly formed complete rings, whereas INY produced arciform structures. We found that both EIS (membrane damage) and the surface plasmon resonance (protein binding) data obtained on tBLMs are in-line with the data obtained in human cell lysis experiments. EIS, however, is capable of capturing effects inaccessible for biological activity assays. Specifically, we found that the INY-induced damage of tBLMs is nearly a linear function of membrane cholesterol content, whereas VLY triggered significant damage only at high (50 mol%) cholesterol concentrations. The observed differences of INY and VLY activities on phospholipid membranes might have clinical importance: both toxin-producing bacteria have been found in healthy vagina and dysbiosis, suggesting the need for adaptation at different vaginal conditions. Our results broaden the possibilities of application of tBLMs in medical diagnostics.
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32
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Wilhelm LP, Voilquin L, Kobayashi T, Tomasetto C, Alpy F. Intracellular and Plasma Membrane Cholesterol Labeling and Quantification Using Filipin and GFP-D4. Methods Mol Biol 2019; 1949:137-152. [PMID: 30790254 DOI: 10.1007/978-1-4939-9136-5_11] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Cholesterol, a major component of biological membranes, is rapidly trafficked and unevenly distributed between organelles. Anomalies of intracellular cholesterol distribution are the hallmark of a number of lysosomal lipid storage disorders. A major methodological obstacle for studying cholesterol trafficking is tracing this molecule in situ. The use of fluorescent probes that specifically bind cholesterol allows the visualization and imaging of cellular cholesterol. Here, we describe a series of assays optimized for quantifying free cholesterol in cell populations and at the single cell level, both at the plasma membrane and inside cells. These methods use two fluorescent probes: the D4 fragment of perfringolysin O fused to GFP (GFP-D4) and the polyene macrolide filipin. First, we report a robust method for quantifying plasma membrane cholesterol by flow cytometry using the GFP-D4 probe. Second, to optically distinguish and quantify intracellular cholesterol accumulation, we have adapted the classical filipin cholesterol staining protocol. Indeed, we observed that treatment of living cells with methyl-β-cyclodextrin, a chemical known to extract cholesterol from the plasma membrane, improves the visualization of the intracellular cholesterol pool with filipin. To complement these staining procedures, we developed an image analysis protocol based on image segmentation to quantify, in a robust manner, intracellular cholesterol stained with filipin. Thus, this chapter is a guideline for cellular cholesterol staining and signal quantification.
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Affiliation(s)
- Léa P Wilhelm
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Institut National de la Santé et de la Recherche Médicale (INSERM), U1258, Centre National de la Recherche Scientifique (CNRS), UMR7104 and Université de Strasbourg, Illkirch, France
| | - Laetitia Voilquin
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Institut National de la Santé et de la Recherche Médicale (INSERM), U1258, Centre National de la Recherche Scientifique (CNRS), UMR7104 and Université de Strasbourg, Illkirch, France
| | - Toshihide Kobayashi
- Université de Strasbourg and Laboratory of Bioimaging and Pathologies, Centre National de la Recherche Scientifique (CNRS), UMR7021, Illkirch, France
| | - Catherine Tomasetto
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Institut National de la Santé et de la Recherche Médicale (INSERM), U1258, Centre National de la Recherche Scientifique (CNRS), UMR7104 and Université de Strasbourg, Illkirch, France.
| | - Fabien Alpy
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Institut National de la Santé et de la Recherche Médicale (INSERM), U1258, Centre National de la Recherche Scientifique (CNRS), UMR7104 and Université de Strasbourg, Illkirch, France.
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33
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Kulma M, Kacprzyk-Stokowiec A, Traczyk G, Kwiatkowska K, Dadlez M. Fine-tuning of the stability of β-strands by Y181 in perfringolysin O directs the prepore to pore transition. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1861:110-122. [PMID: 30463694 DOI: 10.1016/j.bbamem.2018.08.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2017] [Revised: 05/15/2018] [Accepted: 08/19/2018] [Indexed: 11/29/2022]
Abstract
Perfringolysin O (PFO) is a toxic protein that forms β-barrel transmembrane pores upon binding to cholesterol-containing membranes. The formation of lytic pores requires conformational changes in PFO that lead to the conversion of water-soluble monomers into membrane-bound oligomers. Although the general outline of stepwise pore formation has been established, the underlying mechanistic details await clarification. To extend our understanding of the molecular mechanisms that control the pore formation, we compared the hydrogen-deuterium exchange patterns of PFO with its derivatives bearing mutations in the D3 domain. In the case of two of these mutations F318A, Y181A, known from previous work to lead to a decreased lytic activity, global destabilization of all protein domains was observed in their water-soluble forms. This was accompanied by local changes in D3 β-sheet, including unexpected stabilization of functionally important β1 strand in Y181A. In case of the double mutation (F318A/Y181A) that completely abolished the lytic activity, several local changes were retained, but the global destabilization effects of single mutations were reverted and hydrogen-deuterium exchange (HDX) pattern returned to PFO level. Strong structural perturbations were not observed in case of remaining variants in which other residues of the hydrophobic core of D3 domain were substituted by alanine. Our results indicate the existence in PFO of a well-tuned H-bonding network that maintains the stability of the D3 β-strands at appropriate level at each transformation step. F318 and Y181 moieties participate in this network and their role extends beyond their direct intermolecular interaction during oligomerization that was identified previously.
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Affiliation(s)
- Magdalena Kulma
- Department of Biophysics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 5A Pawinskiego St., 02-106 Warsaw, Poland
| | - Aleksandra Kacprzyk-Stokowiec
- Department of Biophysics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 5A Pawinskiego St., 02-106 Warsaw, Poland
| | - Gabriela Traczyk
- Department of Cell Biology, The Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Katarzyna Kwiatkowska
- Department of Cell Biology, The Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Michał Dadlez
- Department of Biophysics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 5A Pawinskiego St., 02-106 Warsaw, Poland; Institute of Genetics and Biotechnology, Department of Biology, Warsaw University, 1 Miecznikowa St., 02-185 Warsaw, Poland.
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Christie MP, Johnstone BA, Tweten RK, Parker MW, Morton CJ. Cholesterol-dependent cytolysins: from water-soluble state to membrane pore. Biophys Rev 2018; 10:1337-1348. [PMID: 30117093 DOI: 10.1007/s12551-018-0448-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 08/07/2018] [Indexed: 12/22/2022] Open
Abstract
The cholesterol-dependent cytolysins (CDCs) are a family of bacterial toxins that are important virulence factors for a number of pathogenic Gram-positive bacterial species. CDCs are secreted as soluble, stable monomeric proteins that bind specifically to cholesterol-rich cell membranes, where they assemble into well-defined ring-shaped complexes of around 40 monomers. The complex then undergoes a concerted structural change, driving a large pore through the membrane, potentially lysing the target cell. Understanding the details of this process as the protein transitions from a discrete monomer to a complex, membrane-spanning protein machine is an ongoing challenge. While many of the details have been revealed, there are still questions that remain unanswered. In this review, we present an overview of some of the key features of the structure and function of the CDCs, including the structure of the secreted monomers, the process of interaction with target membranes, and the transition from bound monomers to complete pores. Future directions in CDC research and the potential of CDCs as research tools will also be discussed.
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Affiliation(s)
- Michelle P Christie
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Bronte A Johnstone
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Rodney K Tweten
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Michael W Parker
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3010, Australia.
- Australian Cancer Research Foundation Rational Drug Discovery Centre, St Vincent's Institute of Medical Research, Fitzroy, VIC, 3065, Australia.
| | - Craig J Morton
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3010, Australia.
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Vezočnik V, Hodnik V, Sitar S, Okur HI, Tušek-Žnidarič M, Lütgebaucks C, Sepčić K, Kogej K, Roke S, Žagar E, Maček P. Kinetically Stable Triglyceride-Based Nanodroplets and Their Interactions with Lipid-Specific Proteins. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:8983-8993. [PMID: 29983071 DOI: 10.1021/acs.langmuir.8b02180] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Understanding of the interactions between proteins and natural and artificially prepared lipid membrane surfaces and embedded nonpolar cores is important in studies of physiological processes and their pathologies and is applicable to nanotechnologies. In particular, rapidly growing interest in cellular droplets defines the need for simplified biomimetic lipid model systems to overcome in vivo complexity and variability. We present a protocol for the preparation of kinetically stable nanoemulsions with nanodroplets composed of sphingomyelin (SM) and cholesterol (Chol), as amphiphilic surfactants, and trioleoylglycerol (TOG), at various molar ratios. To prepare stable SM/Chol-coated monodisperse lipid nanodroplets, we modified a reverse phase evaporation method and combined it with ultrasonication. Lipid composition, ζ-potential, gyration and hydrodynamic radius, shape, and temporal stability of the lipid nanodroplets were characterized and compared to extruded SM/Chol large unilamellar vesicles. Lipid nanodroplets and large unilamellar vesicles with theoretical SM/Chol/TOG molar ratios of 1/1/4.7 and 4/1/11.7 were further investigated for the orientational order of their interfacial water molecules using a second harmonic scattering technique, and for interactions with the SM-binding and Chol-binding pore-forming toxins equinatoxin II and perfringolysin O, respectively. The surface characteristics (ζ-potential, orientational order of interfacial water molecules) and binding of these proteins to the nanodroplet SM/Chol monolayers were similar to those for the SM/Chol bilayers of the large unilamellar vesicles and SM/Chol Langmuir monolayers, in terms of their surface structures. We propose that such SM/Chol/TOG nanoparticles with the required lipid compositions can serve as experimental models for monolayer membrane to provide a system that imitates the natural lipid droplets.
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Affiliation(s)
- Valerija Vezočnik
- Department of Biology, Biotechnical Faculty , University of Ljubljana , Jamnikarjeva 101 , Ljubljana 1000 , Slovenia
| | - Vesna Hodnik
- Department of Biology, Biotechnical Faculty , University of Ljubljana , Jamnikarjeva 101 , Ljubljana 1000 , Slovenia
| | - Simona Sitar
- Department of Polymer Chemistry and Technology , National Institute of Chemistry , Hajdrihova 19 , Ljubljana 1000 , Slovenia
| | - Halil I Okur
- Laboratory for Fundamental BioPhotonics, Institute of Bio-Engineering, and Institute of Material Science, School of Engineering, and Lausanne Centre for Ultrafast Science , École Polytechnique Fédérale de Lausanne , CH-1015 Lausanne , Switzerland
| | | | - Cornelis Lütgebaucks
- Laboratory for Fundamental BioPhotonics, Institute of Bio-Engineering, and Institute of Material Science, School of Engineering, and Lausanne Centre for Ultrafast Science , École Polytechnique Fédérale de Lausanne , CH-1015 Lausanne , Switzerland
| | - Kristina Sepčić
- Department of Biology, Biotechnical Faculty , University of Ljubljana , Jamnikarjeva 101 , Ljubljana 1000 , Slovenia
| | - Ksenija Kogej
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology , University of Ljubljana , Večna pot 113 , Ljubljana 1000 , Slovenia
| | - Sylvie Roke
- Laboratory for Fundamental BioPhotonics, Institute of Bio-Engineering, and Institute of Material Science, School of Engineering, and Lausanne Centre for Ultrafast Science , École Polytechnique Fédérale de Lausanne , CH-1015 Lausanne , Switzerland
| | - Ema Žagar
- Department of Polymer Chemistry and Technology , National Institute of Chemistry , Hajdrihova 19 , Ljubljana 1000 , Slovenia
| | - Peter Maček
- Department of Biology, Biotechnical Faculty , University of Ljubljana , Jamnikarjeva 101 , Ljubljana 1000 , Slovenia
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36
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Steck TL, Lange Y. Transverse distribution of plasma membrane bilayer cholesterol: Picking sides. Traffic 2018; 19:750-760. [PMID: 29896788 DOI: 10.1111/tra.12586] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 06/04/2018] [Accepted: 06/05/2018] [Indexed: 12/23/2022]
Abstract
The transverse asymmetry (sidedness) of phospholipids in plasma membrane bilayers is well characterized, distinctive, actively maintained and functionally important. In contrast, numerous studies using a variety of techniques have concluded that plasma membrane bilayer cholesterol is either mostly in the outer leaflet or the inner leaflet or is fairly evenly distributed. Sterols might simply partition according to their differing affinities for the asymmetrically disposed phospholipids, but some studies have proposed that it is actively transported to the outer leaflet. Other work suggests that the sterol is enriched in the inner leaflet, driven by either positive interactions with the phosphatidylethanolamine on that side or by its exclusion from the outer leaflet by the long chain sphingomyelin molecules therein. This uncertainty raises three questions: is plasma membrane cholesterol sidedness fixed in a given cell or cell type; is it generally the same among mammalian species; and does it serve specific physiological functions? This review grapples with these issues.
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Affiliation(s)
- Theodore L Steck
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois
| | - Yvonne Lange
- Department of Pathology, Rush University Medical Center, Chicago, Illinois
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37
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Kozorog M, Sani MA, Lenarčič Živković M, Ilc G, Hodnik V, Separovic F, Plavec J, Anderluh G. 19F NMR studies provide insights into lipid membrane interactions of listeriolysin O, a pore forming toxin from Listeria monocytogenes. Sci Rep 2018; 8:6894. [PMID: 29720597 PMCID: PMC5931962 DOI: 10.1038/s41598-018-24692-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 03/28/2018] [Indexed: 11/12/2022] Open
Abstract
Listeria monocytogenes is a mammalian pathogen that causes gastroenteritis, miscarriages and infections of the central nervous system in immunocompromised individuals. Its main virulence factor is listeriolysin O (LLO), a pore-forming cholesterol-dependent cytolysin (CDC), which enables bacterial escape from the phagolysosome and contributes to bacterial pathogenicity. Details of cholesterol (Chol) recognition and membrane binding mechanisms by LLO are still not known. Here we used 19F-NMR spectroscopy in order to assess LLO-Chol interactions in solution and in a Chol-rich membrane environment. LLO has six tryptophan residues located in the region of the molecule that is first in contact with lipid membranes. 19F-LLO, which contained 5-fluoro-tryptophans, was prepared by using isotopic labelling in an E. coli expression system. Signals in the 19F-NMR spectrum of 19F-LLO were unambiguously assigned by using a series of single Trp → Phe point mutations. The results employing various cholesterol preparations in solution indicate that tryptophan residues are not directly involved in Chol binding in solution. However, significant chemical shift changes were observed upon LLO binding to Chol-rich membranes, highlighting the role of tryptophan residues in membrane interactions (W512) and oligomerisation (W189 and W489).
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Affiliation(s)
- Mirijam Kozorog
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1000, Ljubljana, Slovenia.,Graduate School of Biomedicine, Medical faculty, University of Ljubljana, 1000, Ljubljana, Slovenia
| | - Marc-Antoine Sani
- School of Chemistry, Bio21 Institute, The University of Melbourne, Melbourne, VIC 3010, Australia
| | | | - Gregor Ilc
- Slovenian NMR Centre, National Institute of Chemistry, Hajdrihova 19, 1000, Ljubljana, Slovenia
| | - Vesna Hodnik
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1000, Ljubljana, Slovenia
| | - Frances Separovic
- School of Chemistry, Bio21 Institute, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Janez Plavec
- Slovenian NMR Centre, National Institute of Chemistry, Hajdrihova 19, 1000, Ljubljana, Slovenia.,EN-FIST Centre of Excellence, Trg Osvobodilne fronte 13, 1001, Ljubljana, Slovenia.,Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, 1000, Ljubljana, Slovenia
| | - Gregor Anderluh
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1000, Ljubljana, Slovenia.
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38
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Interaction of Cholesterol with Perfringolysin O: What Have We Learned from Functional Analysis? Toxins (Basel) 2017; 9:toxins9120381. [PMID: 29168745 PMCID: PMC5744101 DOI: 10.3390/toxins9120381] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 11/16/2017] [Accepted: 11/17/2017] [Indexed: 12/27/2022] Open
Abstract
Cholesterol-dependent cytolysins (CDCs) constitute a family of pore-forming toxins secreted by Gram-positive bacteria. These toxins form transmembrane pores by inserting a large β-barrel into cholesterol-containing membranes. Cholesterol is absolutely required for pore-formation. For most CDCs, binding to cholesterol triggers conformational changes that lead to oligomerization and end in pore-formation. Perfringolysin O (PFO), secreted by Clostridium perfringens, is the prototype for the CDCs. The molecular mechanisms by which cholesterol regulates the cytolytic activity of the CDCs are not fully understood. In particular, the location of the binding site for cholesterol has remained elusive. We have summarized here the current body of knowledge on the CDCs-cholesterol interaction, with focus on PFO. We have employed sterols in aqueous solution to identify structural elements in the cholesterol molecule that are critical for its interaction with PFO. In the absence of high-resolution structural information, site-directed mutagenesis data combined with binding studies performed with different sterols, and molecular modeling are beginning to shed light on this interaction.
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Mechanistic Insights into the Cholesterol-dependent Binding of Perfringolysin O-based Probes and Cell Membranes. Sci Rep 2017; 7:13793. [PMID: 29061991 PMCID: PMC5653841 DOI: 10.1038/s41598-017-14002-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 10/05/2017] [Indexed: 11/18/2022] Open
Abstract
Cholesterol distribution in the cell is maintained by both vesicular and non-vesicular sterol transport. Non-vesicular transport is mediated by the interaction of membrane-embedded cholesterol and water-soluble proteins. Small changes to the lipid composition of the membrane that do not change the total cholesterol content, can significantly affect how cholesterol interacts with other molecules at the surface of the membrane. The cholesterol-dependent cytolysin Perfringolysin O (PFO) constitutes a powerful tool to detect cholesterol in membranes, and the use of PFO-based probes has flourished in recent years. By using a non-lytic PFO derivative, we showed that the sensitivity of the probes for cholesterol can be tuned by modifications introduced directly in the membrane-interacting loops and/or by modifying residues away from the membrane-interacting domain. Through the use of these biosensors on live RAW 264.7 cells, we found that changes in the overall cholesterol content have a limited effect on the average cholesterol accessibility at the surface of the membrane. We showed that these exquisite biosensors report on changes in cholesterol reactivity at the membrane surface independently of the overall cholesterol content in the membrane.
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40
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Divakaruni AS, Andreyev AY, Rogers GW, Murphy AN. In situ measurements of mitochondrial matrix enzyme activities using plasma and mitochondrial membrane permeabilization agents. Anal Biochem 2017; 552:60-65. [PMID: 28987935 DOI: 10.1016/j.ab.2017.09.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/27/2017] [Accepted: 09/29/2017] [Indexed: 12/16/2022]
Abstract
Activities of enzymes localized to the mitochondrial matrix of mammalian cells are often critical regulatory steps in cellular metabolism. As such, measurement of matrix enzyme activities in response to genetic modifications or drug interventions is often desired. However, measurements in intact cells are often hampered by the presence of other isozymes in the cytoplasm as well as the inability to deliver enzyme substrates across cellular membranes. Classic approaches to liberate matrix enzymes utilize harsh treatments that disrupt intracellular architecture or require significant starting material to allow mitochondrial isolation prior to sample extraction. We describe a method using permeabilization reagents for both the plasma and mitochondrial membranes to allow in situ measurement of matrix enzyme activities. It is applied to adherent cell monolayers in 96-well plates treated with perfringolysin O to permeabilize the plasma membrane and alamethicin to permeabilize the mitochondrial inner membrane. We present three examples validated with inhibitor sensitivity: (i) Complex I-mediated oxygen consumption driven by NADH, (ii) ATP hydrolysis by the F1FO complex measuring pH changes in an Agilent Seahorse XF Analyzer, and (iii) Mitochondrial glutaminase (GLS1) activity in a coupled reaction monitoring NADH fluorescence in a plate reader.
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Affiliation(s)
- Ajit S Divakaruni
- University of California, Los Angeles, Department of Molecular and Medical Pharmacology, 650 Charles E. Young Dr. South, 23-305 Center for Health Sciences, Los Angeles, CA 90095-1735, United States.
| | - Alexander Y Andreyev
- University of California, San Diego, Department of Pharmacology, 9500 Gilman Drive #0636, La Jolla, CA 92093, United States
| | - George W Rogers
- Agilent Technologies, 5301 Stevens Creek Blvd, Santa Clara, CA 95051, United States
| | - Anne N Murphy
- University of California, San Diego, Department of Pharmacology, 9500 Gilman Drive #0636, La Jolla, CA 92093, United States
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41
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Kulma M, Kacprzyk-Stokowiec A, Kwiatkowska K, Traczyk G, Sobota A, Dadlez M. R468A mutation in perfringolysin O destabilizes toxin structure and induces membrane fusion. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:1075-1088. [PMID: 28263714 DOI: 10.1016/j.bbamem.2017.03.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 02/20/2017] [Accepted: 03/01/2017] [Indexed: 11/30/2022]
Abstract
Perfringolysin O (PFO) belongs to the family of cholesterol-dependent cytolysins. Upon binding to a cholesterol-containing membrane, PFO undergoes a series of structural changes that result in the formation of a β-barrel pore and cell lysis. Recognition and binding to cholesterol are mediated by the D4 domain, one of four domains of PFO. The D4 domain contains a conserved tryptophan-rich loop named undecapeptide (E458CTGLAWEWWR468) in which arginine 468 is essential for retaining allosteric coupling between D4 and other domains during interaction of PFO with the membrane. In this report we studied the impact of R468A mutation on the whole protein structure using hydrogen-deuterium exchange coupled with mass spectrometry. We found that in aqueous solution, compared to wild type (PFO), PFOR468A showed increased deuterium uptake due to exposure of internal toxin regions to the solvent. This change reflected an overall structural destabilization of PFOR468A in solution. Conversely, upon binding to cholesterol-containing membranes, PFOR468A revealed a profound decrease of hydrogen-deuterium exchange when compared to PFO. This block of deuterium uptake resulted from PFOR468A-induced aggregation and fusion of liposomes, as found by dynamic light scattering, microscopic observations and FRET measurements. In the result of liposome aggregation and fusion, the entire PFOR468A molecule became shielded from aqueous solution and thereby was protected against proteolytic digestion and deuteration. We have established that structural changes induced by the R468A mutation lead to exposure of an additional cholesterol-independent liposome-binding site in PFO that confers its fusogenic property, altering the mode of the toxin action.
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Affiliation(s)
- Magdalena Kulma
- Department of Biophysics, Institute of Biochemistry and Biophysics of the Polish Academy of Sciences, 5A Pawinskiego St., 02-106 Warsaw, Poland
| | - Aleksandra Kacprzyk-Stokowiec
- Department of Biophysics, Institute of Biochemistry and Biophysics of the Polish Academy of Sciences, 5A Pawinskiego St., 02-106 Warsaw, Poland
| | - Katarzyna Kwiatkowska
- Laboratory of Molecular Membrane Biology, Department of Cell Biology, Nencki Institute of Experimental Biology of the Polish Academy of Sciences, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Gabriela Traczyk
- Laboratory of Molecular Membrane Biology, Department of Cell Biology, Nencki Institute of Experimental Biology of the Polish Academy of Sciences, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Andrzej Sobota
- Laboratory of Molecular Membrane Biology, Department of Cell Biology, Nencki Institute of Experimental Biology of the Polish Academy of Sciences, 3 Pasteur St., 02-093 Warsaw, Poland.
| | - Michał Dadlez
- Department of Biophysics, Institute of Biochemistry and Biophysics of the Polish Academy of Sciences, 5A Pawinskiego St., 02-106 Warsaw, Poland; Institute of Genetics and Biotechnology, Department of Biology, Warsaw University, 1 Miecznikowa St., 02-185 Warsaw, Poland.
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42
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Maekawa M. Domain 4 (D4) of Perfringolysin O to Visualize Cholesterol in Cellular Membranes-The Update. SENSORS 2017; 17:s17030504. [PMID: 28273804 PMCID: PMC5375790 DOI: 10.3390/s17030504] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2017] [Revised: 02/28/2017] [Accepted: 03/01/2017] [Indexed: 12/14/2022]
Abstract
The cellular membrane of eukaryotes consists of phospholipids, sphingolipids, cholesterol and membrane proteins. Among them, cholesterol is crucial for various cellular events (e.g., signaling, viral/bacterial infection, and membrane trafficking) in addition to its essential role as an ingredient of steroid hormones, vitamin D, and bile acids. From a micro-perspective, at the plasma membrane, recent emerging evidence strongly suggests the existence of lipid nanodomains formed with cholesterol and phospholipids (e.g., sphingomyelin, phosphatidylserine). Thus, it is important to elucidate how cholesterol behaves in membranes and how the behavior of cholesterol is regulated at the molecular level. To elucidate the complexed characteristics of cholesterol in cellular membranes, a couple of useful biosensors that enable us to visualize cholesterol in cellular membranes have been recently developed by utilizing domain 4 (D4) of Perfringolysin O (PFO, theta toxin), a cholesterol-binding toxin. This review highlights the current progress on development of novel cholesterol biosensors that uncover new insights of cholesterol in cellular membranes.
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Affiliation(s)
- Masashi Maekawa
- Department of Biochemistry and Molecular Genetics, Ehime University Graduate School of Medicine, Toon, Ehime 791-0295, Japan.
- Division of Cell Growth and Tumor Regulation, Proteo-Science Center, Ehime University; Toon, Ehime 791-0295, Japan.
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43
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Litz JP, Thakkar N, Portet T, Keller SL. Depletion with Cyclodextrin Reveals Two Populations of Cholesterol in Model Lipid Membranes. Biophys J 2017; 110:635-645. [PMID: 26840728 DOI: 10.1016/j.bpj.2015.11.021] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 11/06/2015] [Accepted: 11/10/2015] [Indexed: 10/22/2022] Open
Abstract
Recent results provide evidence that cholesterol is highly accessible for removal from both cell and model membranes above a threshold concentration that varies with membrane composition. Here we measured the rate at which methyl-β-cyclodextrin depletes cholesterol from a supported lipid bilayer as a function of cholesterol mole fraction. We formed supported bilayers from two-component mixtures of cholesterol and a PC (phosphatidylcholine) lipid, and we directly visualized the rate of decrease in area of the bilayers with fluorescence microscopy. Our technique yields the accessibility of cholesterol over a wide range of concentrations (30-66 mol %) for many individual bilayers, enabling fast acquisition of replicate data. We found that the bilayers contain two populations of cholesterol, one with low surface accessibility and the other with high accessibility. A larger fraction of the total membrane cholesterol appears in the more accessible population when the acyl chains of the PC-lipid tails are more unsaturated. Our findings are most consistent with the predictions of the condensed-complex and cholesterol bilayer domain models of cholesterol-phospholipid interactions in lipid membranes.
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Affiliation(s)
- Jonathan P Litz
- Department of Chemistry, University of Washington, Seattle, Washington
| | - Niket Thakkar
- Department of Chemistry, University of Washington, Seattle, Washington; Department of Applied Mathematics, University of Washington, Seattle, Washington
| | - Thomas Portet
- Department of Chemistry, University of Washington, Seattle, Washington
| | - Sarah L Keller
- Department of Chemistry, University of Washington, Seattle, Washington; Department of Physics, University of Washington, Seattle, Washington.
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44
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McCaw L, Shi Y, Wang G, Li YJ, Spaner DE. Low Density Lipoproteins Amplify Cytokine-signaling in Chronic Lymphocytic Leukemia Cells. EBioMedicine 2016; 15:24-35. [PMID: 27932296 PMCID: PMC5233814 DOI: 10.1016/j.ebiom.2016.11.033] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 11/26/2016] [Accepted: 11/28/2016] [Indexed: 11/18/2022] Open
Abstract
Recent studies suggest there is a high incidence of elevated low-density lipoprotein (LDL) levels in Chronic Lymphocytic Leukemia (CLL) patients and a survival benefit from cholesterol-lowering statin drugs. The mechanisms of these observations and the kinds of patients they apply to are unclear. Using an in vitro model of the pseudofollicles where CLL cells originate, LDLs were found to increase plasma membrane cholesterol, signaling molecules such as tyrosine-phosphorylated STAT3, and activated CLL cell numbers. The signaling effects of LDLs were not seen in normal lymphocytes or glycolytic lymphoma cell-lines but were restored by transduction with the nuclear receptor PPARδ, which mediates metabolic activity in CLL cells. Breakdown of LDLs in lysosomes was required for the amplification effect, which correlated with down-regulation of HMGCR expression and long lymphocyte doubling times (LDTs) of 53.6 ± 10.4 months. Cholesterol content of circulating CLL cells correlated directly with blood LDL levels in a subgroup of patients. These observations suggest LDLs may enhance proliferative responses of CLL cells to inflammatory signals. Prospective clinical trials are needed to confirm the therapeutic potential of lowering LDL concentrations in CLL, particularly in patients with indolent disease in the “watch-and-wait” phase of management. Slow-growing CLL cells use lysosomal lipase to break low density lipoproteins (LDLs) into free fatty acids and cholesterol. LdL degradation products increase survival of proliferating CLL cells. LDLs decrease oxidative stress and increase plasma membrane cholesterol. LDLs amplify signaling responses to cytokines but not antigens in proliferating CLL cells. Rapidly growing CLL cells, acute leukemia cells, and normal lymphocytes do not exhibit this dependence on LDLs.
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Affiliation(s)
- Lindsay McCaw
- Biology Platform, Sunnybrook Research Institute, Toronto, ON M4N 3M5, Canada; Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada
| | - Yonghong Shi
- Biology Platform, Sunnybrook Research Institute, Toronto, ON M4N 3M5, Canada
| | - Guizhi Wang
- Biology Platform, Sunnybrook Research Institute, Toronto, ON M4N 3M5, Canada
| | - You-Jun Li
- Biology Platform, Sunnybrook Research Institute, Toronto, ON M4N 3M5, Canada; Department of Human Anatomy, College of Basic Medical Sciences, Jilin University, Changchun, Jilin 130021, China
| | - David E Spaner
- Biology Platform, Sunnybrook Research Institute, Toronto, ON M4N 3M5, Canada; Department of Immunology, University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Medicine, University of Toronto, Toronto, ON M5G 2C4, Canada; Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 2M9, Canada; Sunnybrook Odette Cancer Center, Toronto, ON M4N 3M5, Canada.
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45
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Venugopal S, Martinez-Arguelles DB, Chebbi S, Hullin-Matsuda F, Kobayashi T, Papadopoulos V. Plasma Membrane Origin of the Steroidogenic Pool of Cholesterol Used in Hormone-induced Acute Steroid Formation in Leydig Cells. J Biol Chem 2016; 291:26109-26125. [PMID: 27815506 DOI: 10.1074/jbc.m116.740928] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Revised: 11/03/2016] [Indexed: 02/05/2023] Open
Abstract
Hormone-sensitive acute steroid biosynthesis requires trafficking of cholesterol from intracellular sources to the inner mitochondrial membrane. The precise location of the intracellular cholesterol and its transport mechanism are uncertain. Perfringolysin O, produced by Clostridium perfringens, binds cholesterol. Its fourth domain (D4) retains cholesterol-binding properties but not cytotoxicity. We transfected steroidogenic MA-10 cells of mouse Leydig cell tumors with the mCherry-D4 plasmid. Tagged D4 with fluorescent proteins enabled us to track cholesterol. The staining was primarily localized to the inner leaflet of the plasma membrane and was partially released upon treatment with dibutyryl-cAMP (Bt2cAMP), a cAMP analog. Inhibitors of cholesterol import into mitochondria blocked steroidogenesis and prevented release of D4 (and presumably cholesterol) from the plasma membrane. We conclude that the bulk of the steroidogenic pool of cholesterol, mobilized by Bt2cAMP for acute steroidogenesis, originates from the plasma membrane. Treatment of the cells with steroid metabolites, 22(R)-hydroxycholesterol and pregnenolone, also reduced D4 release from the plasma membrane, perhaps evidence for a feedback effect of elevated steroid formation on cholesterol release. Interestingly, D4 staining was localized to endosomes during Bt2cAMP stimulation suggesting that these organelles are on the route of cholesterol trafficking from the plasma membrane to mitochondria. Finally, D4 was expressed in primary rat Leydig cells with a lentivirus and was released from the plasma membrane following Bt2cAMP treatment. We conclude that the plasma membrane is the source of cholesterol for steroidogenesis in these cells as well as in MA-10 cells.
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Affiliation(s)
- Sathvika Venugopal
- From the Research Institute of the McGill University Health Centre and the Department of Medicine, McGill University, Montreal H4A 3J1, Canada
| | - Daniel Benjamin Martinez-Arguelles
- From the Research Institute of the McGill University Health Centre and the Department of Medicine, McGill University, Montreal H4A 3J1, Canada
| | - Seimia Chebbi
- From the Research Institute of the McGill University Health Centre and the Department of Medicine, McGill University, Montreal H4A 3J1, Canada
| | - Françoise Hullin-Matsuda
- the Lipid Biology Laboratory, RIKEN Advanced Science Institute, Wako, Saitama 351-0198, Japan.,INSERM U1060, Université Lyon 1, INSA Lyon, 69621 Villeurbanne, France
| | - Toshihide Kobayashi
- the Lipid Biology Laboratory, RIKEN Advanced Science Institute, Wako, Saitama 351-0198, Japan.,INSERM U1060, Université Lyon 1, INSA Lyon, 69621 Villeurbanne, France.,UMR 7213 CNRS, University of Strasbourg, 67401 Illkirch, France, and
| | - Vassilios Papadopoulos
- From the Research Institute of the McGill University Health Centre and the Department of Medicine, McGill University, Montreal H4A 3J1, Canada, .,the Departments of Pharmacology and Therapeutics and.,Biochemistry, McGill University, Montreal H3G 1Y6, Canada
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46
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Shoji A, Ikeya K, Aoyagi M, Takatsuji R, Yanagida A, Shibusawa Y, Sugawara M. Monitoring of cholesterol oxidation in a lipid bilayer membrane using streptolysin O as a sensing and signal transduction element. J Pharm Biomed Anal 2016; 128:455-461. [DOI: 10.1016/j.jpba.2016.06.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 06/03/2016] [Accepted: 06/07/2016] [Indexed: 11/26/2022]
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47
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Hodel AW, Leung C, Dudkina NV, Saibil HR, Hoogenboom BW. Atomic force microscopy of membrane pore formation by cholesterol dependent cytolysins. Curr Opin Struct Biol 2016; 39:8-15. [DOI: 10.1016/j.sbi.2016.03.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 03/08/2016] [Accepted: 03/14/2016] [Indexed: 11/16/2022]
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48
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Gay A, Rye D, Radhakrishnan A. Switch-like responses of two cholesterol sensors do not require protein oligomerization in membranes. Biophys J 2016; 108:1459-1469. [PMID: 25809258 DOI: 10.1016/j.bpj.2015.02.008] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 01/27/2015] [Accepted: 02/12/2015] [Indexed: 10/23/2022] Open
Abstract
Many cellular processes are sensitive to levels of cholesterol in specific membranes and show a strongly sigmoidal dependence on membrane composition. The sigmoidal responses of the cholesterol sensors involved in these processes could arise from several mechanisms, including positive cooperativity (protein effects) and limited cholesterol accessibility (membrane effects). Here, we describe a sigmoidal response that arises primarily from membrane effects due to sharp changes in the chemical activity of cholesterol. Our models for eukaryotic membrane-bound cholesterol sensors are soluble bacterial toxins that show an identical switch-like specificity for endoplasmic reticulum membrane cholesterol. We show that truncated versions of these toxins fail to form oligomers but still show sigmoidal binding to cholesterol-containing membranes. The nonlinear response emerges because interactions between bilayer lipids control cholesterol accessibility to toxins in a threshold-like fashion. Around these thresholds, the affinity of toxins for membrane cholesterol varies by >100-fold, generating highly cooperative lipid-dependent responses independently of protein-protein interactions. Such lipid-driven cooperativity may control the sensitivity of many cholesterol-dependent processes.
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Affiliation(s)
- Austin Gay
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Daphne Rye
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Arun Radhakrishnan
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas.
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49
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Kishimoto T, Ishitsuka R, Kobayashi T. Detectors for evaluating the cellular landscape of sphingomyelin- and cholesterol-rich membrane domains. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:812-829. [PMID: 26993577 DOI: 10.1016/j.bbalip.2016.03.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 02/09/2016] [Accepted: 03/09/2016] [Indexed: 12/11/2022]
Abstract
Although sphingomyelin and cholesterol are major lipids of mammalian cells, the detailed distribution of these lipids in cellular membranes remains still obscure. However, the recent development of protein probes that specifically bind sphingomyelin and/or cholesterol provides new information about the landscape of the lipid domains that are enriched with sphingomyelin or cholesterol or both. Here, we critically summarize the tools to study distribution and dynamics of sphingomyelin and cholesterol. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.
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Affiliation(s)
| | - Reiko Ishitsuka
- Lipid Biology Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - Toshihide Kobayashi
- Lipid Biology Laboratory, RIKEN, Wako, Saitama 351-0198, Japan; INSERM U1060, Université Lyon 1, Villeurbanne 69621, France.
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50
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Maekawa M, Yang Y, Fairn GD. Perfringolysin O Theta Toxin as a Tool to Monitor the Distribution and Inhomogeneity of Cholesterol in Cellular Membranes. Toxins (Basel) 2016; 8:toxins8030067. [PMID: 27005662 PMCID: PMC4810212 DOI: 10.3390/toxins8030067] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 02/26/2016] [Accepted: 02/26/2016] [Indexed: 11/23/2022] Open
Abstract
Cholesterol is an essential structural component of cellular membranes in eukaryotes. Cholesterol in the exofacial leaflet of the plasma membrane is thought to form membrane nanodomains with sphingolipids and specific proteins. Additionally, cholesterol is found in the intracellular membranes of endosomes and has crucial functions in membrane trafficking. Furthermore, cellular cholesterol homeostasis and regulation of de novo synthesis rely on transport via both vesicular and non-vesicular pathways. Thus, the ability to visualize and detect intracellular cholesterol, especially in the plasma membrane, is critical to understanding the complex biology associated with cholesterol and the nanodomains. Perfringolysin O (PFO) theta toxin is one of the toxins secreted by the anaerobic bacteria Clostridium perfringens and this toxin forms pores in the plasma membrane that causes cell lysis. It is well understood that PFO recognizes and binds to cholesterol in the exofacial leaflets of the plasma membrane, and domain 4 of PFO (D4) is sufficient for the binding of cholesterol. Recent studies have taken advantage of this high-affinity cholesterol-binding domain to create a variety of cholesterol biosensors by using a non-toxic PFO or the D4 in isolation. This review highlights the characteristics and usefulness of, and the principal findings related to, these PFO-derived cholesterol biosensors.
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Affiliation(s)
- Masashi Maekawa
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, 209 Victoria Street, 6th Floor, Toronto, ON M5S 1T8, Canada.
| | - Yanbo Yang
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, 209 Victoria Street, 6th Floor, Toronto, ON M5S 1T8, Canada.
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada.
| | - Gregory D Fairn
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, 209 Victoria Street, 6th Floor, Toronto, ON M5S 1T8, Canada.
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada.
- Department of Surgery, University of Toronto, Toronto, ON M5T 1P5, Canada.
- Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada.
- Institute for Biomedical Engineering and Science Technology (IBEST), Ryerson University and St. Michael's Hospital, Toronto, ON M5B 2K3, Canada.
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