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Shendrik P, Golani G, Dharan R, Schwarz US, Sorkin R. Membrane Tension Inhibits Lipid Mixing by Increasing the Hemifusion Stalk Energy. ACS NANO 2023; 17:18942-18951. [PMID: 37669531 PMCID: PMC7615193 DOI: 10.1021/acsnano.3c04293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Accepted: 08/23/2023] [Indexed: 09/07/2023]
Abstract
Fusion of biological membranes is fundamental in various physiological events. The fusion process involves several intermediate stages with energy barriers that are tightly dependent on the mechanical and physical properties of the system, one of which is membrane tension. As previously established, the late stages of fusion, including hemifusion diaphragm and pore expansions, are favored by membrane tension. However, a current understanding of how the energy barrier of earlier fusion stages is affected by membrane tension is lacking. Here, we apply a newly developed experimental approach combining micropipette-aspirated giant unilamellar vesicles and optically trapped membrane-coated beads, revealing that membrane tension inhibits lipid mixing. We show that lipid mixing is 6 times slower under a tension of 0.12 mN/m compared with tension-free membranes. Furthermore, using continuum elastic theory, we calculate the dependence of the hemifusion stalk formation energy on membrane tension and intermembrane distance and find the increase in the corresponding energy barrier to be 1.6 kBT in our setting, which can explain the increase in lipid mixing time delay. Finally, we show that tension can be a significant factor in the stalk energy if the pre-fusion intermembrane distance is on the order of several nanometers, while for membranes that are tightly docked, tension has a negligible effect.
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Affiliation(s)
- Petr Shendrik
- School
of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
- Center
of Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Gonen Golani
- Institute
for Theoretical Physics and BioQuant Center for Quantitative Biology, Heidelberg University, 69120, Heidelberg, Germany
| | - Raviv Dharan
- School
of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
- Center
of Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Ulrich S. Schwarz
- Institute
for Theoretical Physics and BioQuant Center for Quantitative Biology, Heidelberg University, 69120, Heidelberg, Germany
| | - Raya Sorkin
- School
of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
- Center
of Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv, 6997801, Israel
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2
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Singh A, Kukal S, Kanojia N, Singh M, Saso L, Kukreti S, Kukreti R. Lipid Mediated Brain Disorders: A Perspective. Prostaglandins Other Lipid Mediat 2023; 167:106737. [PMID: 37086954 DOI: 10.1016/j.prostaglandins.2023.106737] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 04/10/2023] [Accepted: 04/18/2023] [Indexed: 04/24/2023]
Abstract
The brain, one of the most resilient organs of the body is highly enriched in lipid content, suggesting the essential role of lipids in brain physiological activities. Lipids constitute an important structural part of the brain and act as a rich source of metabolic energy. Besides, lipids in their bioactive form (known as bioactive lipids) play an essential signaling and regulatory role, facilitating neurogenesis, synaptogenesis, and cell-cell communication. Brain lipid metabolism is thus a tightly regulated process. Any alteration/dysregulation of lipid metabolism greatly impact brain health and activity. Moreover, since central nervous system (CNS) is the most metabolically active system and lacks an efficient antioxidative defence system, it acts as a hub for the production of reactive oxygen species (ROS) and subsequent lipid peroxidation. These peroxidation events are reported during pathological changes such as neuronal tissue injury and inflammation. Present review is a modest attempt to gain insights into the role of dysregulated bioactive lipid levels and lipid oxidation status in the pathogenesis and progression of neurodegenerative disorders. This may open up new avenues exploiting lipids as the therapeutic targets for improving brain health, and treatment of nervous system disorders.
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Affiliation(s)
- Anju Singh
- Department of Chemistry, Ramjas College, University of Delhi, Delhi 110007, India; Nucleic Acids Research Lab, Department of Chemistry, University of Delhi (North Campus), Delhi 110007, India
| | - Samiksha Kukal
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology (IGIB), Mall Road, Delhi 110007, India; Academy of Scientific and Innovative Research (AcSIR), CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB) Campus, Delhi 110007, India
| | - Neha Kanojia
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology (IGIB), Mall Road, Delhi 110007, India; Academy of Scientific and Innovative Research (AcSIR), CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB) Campus, Delhi 110007, India
| | - Mahak Singh
- Department of Chemistry, Ramjas College, University of Delhi, Delhi 110007, India
| | - Luciano Saso
- Department of Physiology and Pharmacology "Vittorio Erspamer", Sapienza University of Rome, P. le Aldo Moro 5, 00185 Rome, Italy
| | - Shrikant Kukreti
- Nucleic Acids Research Lab, Department of Chemistry, University of Delhi (North Campus), Delhi 110007, India
| | - Ritushree Kukreti
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology (IGIB), Mall Road, Delhi 110007, India; Academy of Scientific and Innovative Research (AcSIR), CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB) Campus, Delhi 110007, India.
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3
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Klein S, Golani G, Lolicato F, Lahr C, Beyer D, Herrmann A, Wachsmuth-Melm M, Reddmann N, Brecht R, Hosseinzadeh M, Kolovou A, Makroczyova J, Peterl S, Schorb M, Schwab Y, Brügger B, Nickel W, Schwarz US, Chlanda P. IFITM3 blocks influenza virus entry by sorting lipids and stabilizing hemifusion. Cell Host Microbe 2023; 31:616-633.e20. [PMID: 37003257 DOI: 10.1016/j.chom.2023.03.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 11/15/2022] [Accepted: 03/06/2023] [Indexed: 04/03/2023]
Abstract
Interferon-induced transmembrane protein 3 (IFITM3) inhibits the entry of numerous viruses through undefined molecular mechanisms. IFITM3 localizes in the endosomal-lysosomal system and specifically affects virus fusion with target cell membranes. We found that IFITM3 induces local lipid sorting, resulting in an increased concentration of lipids disfavoring viral fusion at the hemifusion site. This increases the energy barrier for fusion pore formation and the hemifusion dwell time, promoting viral degradation in lysosomes. In situ cryo-electron tomography captured IFITM3-mediated arrest of influenza A virus membrane fusion. Observation of hemifusion diaphragms between viral particles and late endosomal membranes confirmed hemifusion stabilization as a molecular mechanism of IFITM3. The presence of the influenza fusion protein hemagglutinin in post-fusion conformation close to hemifusion sites further indicated that IFITM3 does not interfere with the viral fusion machinery. Collectively, these findings show that IFITM3 induces lipid sorting to stabilize hemifusion and prevent virus entry into target cells.
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Affiliation(s)
- Steffen Klein
- Schaller Research Group, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany; BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany
| | - Gonen Golani
- BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany; Institute for Theoretical Physics, Heidelberg University, 69120 Heidelberg, Germany
| | - Fabio Lolicato
- Heidelberg University Biochemistry Center, Heidelberg University, 69120 Heidelberg, Germany; Department of Physics, University of Helsinki, Helsinki, Finland
| | - Carmen Lahr
- Schaller Research Group, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany; BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany
| | - Daniel Beyer
- Heidelberg University Biochemistry Center, Heidelberg University, 69120 Heidelberg, Germany
| | - Alexia Herrmann
- Heidelberg University Biochemistry Center, Heidelberg University, 69120 Heidelberg, Germany
| | - Moritz Wachsmuth-Melm
- Schaller Research Group, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany; BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany
| | - Nina Reddmann
- Schaller Research Group, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany; BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany
| | - Romy Brecht
- Schaller Research Group, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany; BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany
| | - Mehdi Hosseinzadeh
- Schaller Research Group, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany; BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany
| | - Androniki Kolovou
- Schaller Research Group, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany; BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany
| | - Jana Makroczyova
- Schaller Research Group, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany; BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany
| | - Sarah Peterl
- Schaller Research Group, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany; BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany
| | - Martin Schorb
- Electron Microscopy Core Facility, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Yannick Schwab
- Electron Microscopy Core Facility, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Britta Brügger
- Heidelberg University Biochemistry Center, Heidelberg University, 69120 Heidelberg, Germany
| | - Walter Nickel
- Heidelberg University Biochemistry Center, Heidelberg University, 69120 Heidelberg, Germany
| | - Ulrich S Schwarz
- BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany; Institute for Theoretical Physics, Heidelberg University, 69120 Heidelberg, Germany
| | - Petr Chlanda
- Schaller Research Group, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany; BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany.
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4
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Iriondo MN, Etxaniz A, Varela YR, Ballesteros U, Lázaro M, Valle M, Fracchiolla D, Martens S, Montes LR, Goñi FM, Alonso A. Effect of ATG12-ATG5-ATG16L1 autophagy E3-like complex on the ability of LC3/GABARAP proteins to induce vesicle tethering and fusion. Cell Mol Life Sci 2023; 80:56. [PMID: 36729310 PMCID: PMC9894987 DOI: 10.1007/s00018-023-04704-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 01/19/2023] [Accepted: 01/20/2023] [Indexed: 02/03/2023]
Abstract
In macroautophagy, the autophagosome (AP) engulfs portions of cytoplasm to allow their lysosomal degradation. AP formation in humans requires the concerted action of the ATG12 and LC3/GABARAP conjugation systems. The ATG12-ATG5-ATG16L1 or E3-like complex (E3 for short) acts as a ubiquitin-like E3 enzyme, promoting LC3/GABARAP proteins anchoring to the AP membrane. Their role in the AP expansion process is still unclear, in part because there are no studies comparing six LC3/GABARAP family member roles under the same conditions, and also because the full human E3 was only recently available. In the present study, the lipidation of six members of the LC3/GABARAP family has been reconstituted in the presence and absence of E3, and the mechanisms by which E3 and LC3/GABARAP proteins participate in vesicle tethering and fusion have been investigated. In the absence of E3, GABARAP and GABARAPL1 showed the highest activities. Differences found within LC3/GABARAP proteins suggest the existence of a lipidation threshold, lower for the GABARAP subfamily, as a requisite for tethering and inter-vesicular lipid mixing. E3 increases and speeds up lipidation and LC3/GABARAP-promoted tethering. However, E3 hampers LC3/GABARAP capacity to induce inter-vesicular lipid mixing or subsequent fusion, presumably through the formation of a rigid scaffold on the vesicle surface. Our results suggest a model of AP expansion in which the growing regions would be areas where the LC3/GABARAP proteins involved should be susceptible to lipidation in the absence of E3, or else a regulatory mechanism would allow vesicle incorporation and phagophore growth when E3 is present.
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Affiliation(s)
- Marina N Iriondo
- Instituto Biofisika (UPV/EHU, CSIC), University of the Basque Country, 48940, Leioa, Spain
- Department of Biochemistry and Molecular Biology, University of the Basque Country, 48940, Leioa, Spain
| | - Asier Etxaniz
- Instituto Biofisika (UPV/EHU, CSIC), University of the Basque Country, 48940, Leioa, Spain
- Department of Biochemistry and Molecular Biology, University of the Basque Country, 48940, Leioa, Spain
| | - Yaiza R Varela
- Instituto Biofisika (UPV/EHU, CSIC), University of the Basque Country, 48940, Leioa, Spain
- Department of Biochemistry and Molecular Biology, University of the Basque Country, 48940, Leioa, Spain
| | - Uxue Ballesteros
- Instituto Biofisika (UPV/EHU, CSIC), University of the Basque Country, 48940, Leioa, Spain
- Department of Biochemistry and Molecular Biology, University of the Basque Country, 48940, Leioa, Spain
| | - Melisa Lázaro
- CIC bioGUNE, Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 800, 48160, Derio, Bizkaia, Spain
| | - Mikel Valle
- CIC bioGUNE, Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 800, 48160, Derio, Bizkaia, Spain
| | - Dorotea Fracchiolla
- Max Perutz Labs, University of Vienna, Vienna BioCenter, Dr. Bohr-Gasse 9, 1030, Vienna, Austria
| | - Sascha Martens
- Max Perutz Labs, University of Vienna, Vienna BioCenter, Dr. Bohr-Gasse 9, 1030, Vienna, Austria
| | - L Ruth Montes
- Instituto Biofisika (UPV/EHU, CSIC), University of the Basque Country, 48940, Leioa, Spain
- Department of Biochemistry and Molecular Biology, University of the Basque Country, 48940, Leioa, Spain
| | - Félix M Goñi
- Instituto Biofisika (UPV/EHU, CSIC), University of the Basque Country, 48940, Leioa, Spain
- Department of Biochemistry and Molecular Biology, University of the Basque Country, 48940, Leioa, Spain
| | - Alicia Alonso
- Instituto Biofisika (UPV/EHU, CSIC), University of the Basque Country, 48940, Leioa, Spain.
- Department of Biochemistry and Molecular Biology, University of the Basque Country, 48940, Leioa, Spain.
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5
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Warner JM, An D, Stratton BS, O'Shaughnessy B. A hemifused complex is the hub in a network of pathways to membrane fusion. Biophys J 2023; 122:374-385. [PMID: 36463406 PMCID: PMC9892611 DOI: 10.1016/j.bpj.2022.12.003] [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: 03/01/2022] [Revised: 06/25/2022] [Accepted: 11/30/2022] [Indexed: 12/12/2022] Open
Abstract
Membrane fusion is a critical step for many essential processes, from neurotransmission to fertilization. For over 40 years, protein-free fusion driven by calcium or other cationic species has provided a simplified model of biological fusion, but the mechanisms remain poorly understood. Cation-mediated membrane fusion and permeation are essential in their own right to drug delivery strategies based on cell-penetrating peptides or cation-bearing lipid nanoparticles. Experimental studies suggest calcium drives anionic membranes to a hemifused intermediate that constitutes a hub in a network of pathways, but the pathway selection mechanism is unknown. Here we develop a mathematical model that identifies the network hub as a highly dynamic hemifusion complex. Multivalent cations drive expansion of this high-tension hemifusion interface between interacting vesicles during a brief transient. The fate of this interface determines the outcome, either fusion, dead-end hemifusion, or vesicle lysis. The model reproduces the unexplained finding that calcium-driven fusion of vesicles with planar membranes typically stalls at hemifusion, and we show the equilibrated hemifused state is a novel lens-shaped complex. Thus, membrane fusion kinetics follow a stochastic trajectory within a network of pathways, with outcome weightings set by a hemifused complex intermediate.
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Affiliation(s)
- Jason M Warner
- Department of Chemical Engineering, Columbia University, New York, New York
| | - Dong An
- Department of Chemical Engineering, Columbia University, New York, New York
| | | | - Ben O'Shaughnessy
- Department of Chemical Engineering, Columbia University, New York, New York.
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6
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Krasnobaev VD, Batishchev OV. The Role of Lipid Domains and Physical Properties of Membranes in the Development of Age-Related Neurodegenerative Diseases. BIOCHEMISTRY (MOSCOW), SUPPLEMENT SERIES A: MEMBRANE AND CELL BIOLOGY 2022. [DOI: 10.1134/s199074782209001x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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7
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Lipid Microenvironment Modulates the Pore-Forming Ability of Polymyxin B. Antibiotics (Basel) 2022; 11:antibiotics11101445. [PMID: 36290103 PMCID: PMC9598075 DOI: 10.3390/antibiotics11101445] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/18/2022] [Accepted: 10/19/2022] [Indexed: 11/17/2022] Open
Abstract
The ability of polymyxin B, an antibiotic used to treat infections caused by multidrug-resistant Gram-negative bacteria as a last-line therapeutic option, to form ion pores in model membranes composed of various phospholipids and lipopolysaccharides was studied. Our data demonstrate that polymyxin B predominantly interacts with negatively charged lipids. Susceptibility decreases as follows: Kdo2-Lipid A >> DOPG ≈ DOPS >> DPhPG ≈ TOCL ≈ Lipid A. The dimer and hexamer of polymyxin B are involved in the pore formation in DOPG(DOPS)- and Kdo2-Lipid A-enriched bilayers, respectively. The pore-forming ability of polymyxin B significantly depends on the shape of membrane lipids, which indicates that the antibiotic produces toroidal lipopeptide-lipid pores. Small amphiphilic molecules diminishing the membrane dipole potential and inducing positive curvature stress were shown to be agonists of pore formation by polymyxin B and might be used to develop innovative lipopeptide-based formulations.
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8
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Krasnobaev VD, Galimzyanov TR, Akimov SA, Batishchev OV. Lysolipids regulate raft size distribution. Front Mol Biosci 2022; 9:1021321. [PMID: 36275621 PMCID: PMC9581197 DOI: 10.3389/fmolb.2022.1021321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 09/20/2022] [Indexed: 11/13/2022] Open
Abstract
The lipid matrix of cellular membranes, directly and indirectly, regulates many vital functions of the cell. The diversity of lipids in membranes leads to the formation of ordered domains called rafts, which play a crucial role in signal transduction, protein sorting and other cellular processes. Rafts are believed to impact the development of different neurodegenerative diseases, such as Alzheimer’s, Parkinson’s, Huntington’s ones, amyotrophic lateral sclerosis, some types of cancer, etc. These diseases correlate with the change in the membrane lipid composition resulting from an oxidative stress, age-related processes, dysfunction of proteins, and many others. In particular, a lot of studies report a significant rise in the level of lysolipids. Physicochemical properties of rafts are determined by membrane composition, in particular, by the content of lysolipids. Lysolipids may thus regulate raft-involving processes. However, the exact mechanism of such regulation is unknown. Although studying rafts in vivo still seems to be rather complicated, liquid-ordered domains are well observed in model systems. In the present study, we used atomic force microscopy (AFM) to examine how lysophospholipids influence the liquid-ordered domains in model ternary membranes. We demonstrated that even a small amount of lysolipids in a membrane significantly impacts domain size depending on the saturation of the lysolipid hydrocarbon tails and the amount of cholesterol. The mixture with the bigger relative fraction of cholesterol was more susceptible to the action of lysolipids. This data helped us to generalize our previous theoretical model of the domain size regulation by lipids with particular molecular shape expanding it to the case of lysolipids and dioleoylglycerol.
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Affiliation(s)
- Vladimir D. Krasnobaev
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia
- Moscow Institute of Physics and Technology (National Research University), Dolgoprudny, Russia
| | - Timur R. Galimzyanov
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia
| | - Sergey A. Akimov
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia
| | - Oleg V. Batishchev
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia
- *Correspondence: Oleg V. Batishchev,
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9
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Enoki TA, Feigenson GW. Improving our picture of the plasma membrane: Rafts induce ordered domains in a simplified model cytoplasmic leaflet. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183995. [PMID: 35753393 DOI: 10.1016/j.bbamem.2022.183995] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 06/09/2022] [Accepted: 06/13/2022] [Indexed: 01/06/2023]
Abstract
By study of asymmetric membranes, models of the cell plasma membrane (PM) have improved, with more realistic properties of the asymmetric lipid composition of the membrane being explored. We used hemifusion of symmetric giant unilamellar vesicles (GUVs) with a supported lipid bilayer (SLB) to engineer bilayer leaflets of different composition. During hemifusion, only the outer leaflets of GUV and SLB are connected, exchanging lipids by simple diffusion. aGUVs were detached from the SLB for study. In general these aGUVs are formed with one leaflet that phase-separates into Ld (liquid disordered) + Lo (liquid ordered) phases, and another leaflet with lipid composition that would form a single fluid phase in a symmetric bilayer. We observed that ordered phases of either Lo or Lβ (gel phase) induce an ordered domain in the apposed fluid leaflet that lacks high melting lipids. Results suggest both an inter-leaflet and an intra-leaflet redistribution of cholesterol. We used C-Laurdan spectral images to investigate the lipid packing/order of aGUVs, finding that cholesterol partitions into the induced ordered domains. We suggest this behavior to be commonplace, that when Ld + Lo phase separation occurs in a cell PM exoplasmic leaflet, an induced order domain forms in the cytoplasmic leaflet.
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Affiliation(s)
- Thais A Enoki
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA.
| | - Gerald W Feigenson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
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10
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Rahman MM, Garudadri T, Das S. Role of Surface Tension in Microrobot Penetration in Membranes. ... INTERNATIONAL CONFERENCE ON MANIPULATION AUTOMATION AND ROBOTICS AT SMALL SCALES (MARSS). INTERNATIONAL CONFERENCE ON MANIPULATION AUTOMATION AND ROBOTICS AT SMALL SCALES 2022; 2022:10.1109/marss55884.2022.9870474. [PMID: 37521089 PMCID: PMC10387354 DOI: 10.1109/marss55884.2022.9870474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/01/2023]
Abstract
cell-membrane fusion using microrobots can be a useful technique for delivering bioactive compounds to cellular systems. The role of membrane curvature and lipid ordering in the cell membrane penetration process is well known. However, once the fusion into the cell membrane is already initiated, the fluid dynamics of microrobot penetration based on tension difference of the microrobot solution and membrane curvature at the fusion pore has not been explored yet. Here, we demonstrate how surface tension difference among merging interfaces plays role in microrobot droplet penetration into a liquid bath, mimicking cell membrane fusion. The maximum penetration of a microrobot droplet into a liquid bath depends on the positive difference of surface tension between the droplet and liquid bath, longitudinal curvature of the bridge region, and the size of the droplet.
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Affiliation(s)
- Md Mahmudur Rahman
- Department of Mechanical Engineering, University of Delaware, Newark, DE 19716 USA. He is now with Department of Mechanical Engineering, Georgia Southern University, Statesboro, GA 30458 USA
| | | | - Sambeeta Das
- Department of Mechanical Engineering, University of Delaware, Newark, DE 19716 USA
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11
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Ballesteros U, Etxaniz A, Iriondo MN, Varela YR, Lázaro M, Viguera AR, Montes LR, Valle M, Goñi FM, Alonso A. Autophagy protein LC3C binding to phospholipid and interaction with lipid membranes. Int J Biol Macromol 2022; 212:432-441. [PMID: 35618088 DOI: 10.1016/j.ijbiomac.2022.05.129] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 05/16/2022] [Accepted: 05/17/2022] [Indexed: 01/18/2023]
Abstract
Autophagy is a process in which parts of the eukaryotic cell are selectively degraded in the lysosome. The materials to be catabolized are first surrounded by a double-membrane structure, the autophagosome. Autophagosome generation is a complex event, in which many proteins are involved. Among the latter, yeast Atg8 or its mammalian orthologues are essential in autophagosome membrane elongation, shaping and closure. A subfamily of the human Atg8 orthologues is formed by the proteins LC3A, LC3B, and LC3C. Previous studies suggest that, at variance with the other two, LC3C does not participate in cardiolipin-mediated mitophagy. The present study was devoted to exploring the binding of LC3C to lipid vesicles, bilayers and monolayers, and the ensuing protein-dependent perturbing effects, in the absence of the mitochondrial lipid cardiolipin. All Atg8 orthologues are covalently bound to a phospholipid prior to their involvement in autophagosome elongation. In our case, a mutant in the C-terminal amino acid, LC3C G126C, together with the use of a maleimide-derivatized phosphatidyl ethanolamine, ensured LC3C lipidation, up to 100% under certain conditions. Ultracentrifugation, surface pressure measurements, spectroscopic and cryo-electron microscopic techniques revealed that lipidated LC3C induced vesicle aggregation (5-fold faster in sonicated than in large unilamellar vesicles) and inter-vesicular lipid mixing (up to 82%), including inner-monolayer lipid mixing (up to 32%), consistent with in vitro partial vesicle fusion. LC3C was also able to cause the release of 80-90% vesicular aqueous contents. The data support the idea that LC3C would be able to help in autophagosome elongation/fusion in autophagy phenomena.
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Affiliation(s)
- Uxue Ballesteros
- Instituto Biofisika (CSIC, UPV/EHU) and Department of Biochemistry, University of the Basque Country, 48940 Leioa, Spain
| | - Asier Etxaniz
- Instituto Biofisika (CSIC, UPV/EHU) and Department of Biochemistry, University of the Basque Country, 48940 Leioa, Spain
| | - Marina N Iriondo
- Instituto Biofisika (CSIC, UPV/EHU) and Department of Biochemistry, University of the Basque Country, 48940 Leioa, Spain
| | - Yaiza R Varela
- Instituto Biofisika (CSIC, UPV/EHU) and Department of Biochemistry, University of the Basque Country, 48940 Leioa, Spain
| | - Melisa Lázaro
- CIC bioGUNE, Basque Research & Technology Alliance (BRTA), Bizkaia Technology Park, Building 800, 48160 Derio, Bizkaia, Spain
| | - Ana R Viguera
- Instituto Biofisika (CSIC, UPV/EHU) and Department of Biochemistry, University of the Basque Country, 48940 Leioa, Spain
| | - L Ruth Montes
- Instituto Biofisika (CSIC, UPV/EHU) and Department of Biochemistry, University of the Basque Country, 48940 Leioa, Spain
| | - Mikel Valle
- CIC bioGUNE, Basque Research & Technology Alliance (BRTA), Bizkaia Technology Park, Building 800, 48160 Derio, Bizkaia, Spain
| | - Félix M Goñi
- Instituto Biofisika (CSIC, UPV/EHU) and Department of Biochemistry, University of the Basque Country, 48940 Leioa, Spain
| | - Alicia Alonso
- Instituto Biofisika (CSIC, UPV/EHU) and Department of Biochemistry, University of the Basque Country, 48940 Leioa, Spain.
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12
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Joardar A, Pattnaik GP, Chakraborty H. Mechanism of Membrane Fusion: Interplay of Lipid and Peptide. J Membr Biol 2022; 255:211-224. [PMID: 35435451 PMCID: PMC9014786 DOI: 10.1007/s00232-022-00233-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 03/25/2022] [Indexed: 11/26/2022]
Abstract
Membrane fusion is an essential process for the survival of eukaryotes and the entry of enveloped viruses into host cells. A proper understanding of the mechanism of membrane fusion would provide us a handle to manipulate several biological pathways, and design efficient vaccines against emerging and re-emerging viral infections. Although fusion proteins take the central stage in catalyzing the process, role of lipid composition is also of paramount importance. Lipid composition modulates membrane organization and dynamics and impacts the lipid–protein (peptide) interaction. Moreover, the intrinsic curvature of lipids has strong impact on the formation of stalk and hemifusion diaphragm. Detection of transiently stable intermediates remains the bottleneck in the understanding of fusion mechanism. In order to circumvent this challenge, analytical methods can be employed to determine the kinetic parameters from ensemble average measurements of observables, such as lipid mixing, content mixing, and content leakage. The current review aims to present an analytical method that would aid our understanding of the fusion mechanism, provides a better insight into the role of lipid shape, and discusses the interplay of lipid and peptide in membrane fusion.
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Affiliation(s)
- Ankita Joardar
- School of Chemistry, Sambalpur University, Jyoti Vihar, Burla, Odisha, 768019, India
| | | | - Hirak Chakraborty
- School of Chemistry, Sambalpur University, Jyoti Vihar, Burla, Odisha, 768019, India.
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13
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Trenti F, Sandron T, Guella G, Lencioni V. Insect cold-tolerance and lipidome: Membrane lipid composition of two chironomid species differently adapted to cold. Cryobiology 2022; 106:84-90. [DOI: 10.1016/j.cryobiol.2022.03.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 03/07/2022] [Accepted: 03/18/2022] [Indexed: 11/30/2022]
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14
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Nieto-Garai JA, Contreras FX, Arboleya A, Lorizate M. Role of Protein-Lipid Interactions in Viral Entry. Adv Biol (Weinh) 2022; 6:e2101264. [PMID: 35119227 DOI: 10.1002/adbi.202101264] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 12/19/2021] [Indexed: 12/25/2022]
Abstract
The viral entry consists of several sequential events that ensure the attachment of the virus to the host cell and the introduction of its genetic material for the continuation of the replication cycle. Both cellular and viral lipids have gained a wider focus in recent years in the field of viral entry, as they are found to play key roles in different steps of the process. The specific role is summarized that lipids and lipid membrane nanostructures play in viral attachment, fusion, and immune evasion and how they can be targeted with antiviral therapies. Finally, some of the limitations of techniques commonly used for protein-lipid interactions studies are discussed, and new emerging tools are reviewed that can be applied to this field.
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Affiliation(s)
- Jon Ander Nieto-Garai
- Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, University of the Basque Country, Leioa, E-48940, Spain
| | - Francesc-Xabier Contreras
- Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, University of the Basque Country, Leioa, E-48940, Spain.,Instituto Biofisika (UPV/EHU, CSIC), University of the Basque Country, Leioa, E-48940, Spain.,Ikerbasque, Basque Foundation for Science, Bilbao, 48013, Spain
| | - Aroa Arboleya
- Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, University of the Basque Country, Leioa, E-48940, Spain.,Instituto Biofisika (UPV/EHU, CSIC), University of the Basque Country, Leioa, E-48940, Spain.,Fundación Biofísica Bizkaia/Biofisika Bizkaia Fundazioa (FBB), Barrio Sarriena s/n, Leioa, E-48940, Spain
| | - Maier Lorizate
- Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, University of the Basque Country, Leioa, E-48940, Spain.,Instituto Biofisika (UPV/EHU, CSIC), University of the Basque Country, Leioa, E-48940, Spain
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15
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Iriondo MN, Etxaniz A, Antón Z, Montes LR, Alonso A. Molecular and mesoscopic geometries in autophagosome generation. A review. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183731. [PMID: 34419487 DOI: 10.1016/j.bbamem.2021.183731] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 08/12/2021] [Accepted: 08/15/2021] [Indexed: 01/18/2023]
Abstract
Autophagy is an essential process in cell self-repair and survival. The centre of the autophagic event is the generation of the so-called autophagosome (AP), a vesicle surrounded by a double membrane (two bilayers). The AP delivers its cargo to a lysosome, for degradation and re-use of the hydrolysis products as new building blocks. AP formation is a very complex event, requiring dozens of specific proteins, and involving numerous instances of membrane biogenesis and architecture, including membrane fusion and fission. Many stages of AP generation can be rationalised in terms of curvature, both the molecular geometry of lipids interpreted in terms of 'intrinsic curvature', and the overall mesoscopic curvature of the whole membrane, as observed with microscopy techniques. The present contribution intends to bring together the worlds of biophysics and cell biology of autophagy, in the hope that the resulting cross-pollination will generate abundant fruit.
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Affiliation(s)
- Marina N Iriondo
- Instituto Biofisika (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, 48940 Leioa, Spain
| | - Asier Etxaniz
- Instituto Biofisika (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, 48940 Leioa, Spain
| | - Zuriñe Antón
- Instituto Biofisika (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, 48940 Leioa, Spain
| | - L Ruth Montes
- Instituto Biofisika (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, 48940 Leioa, Spain
| | - Alicia Alonso
- Instituto Biofisika (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, 48940 Leioa, Spain.
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16
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Tanguy E, Wolf A, Wang Q, Chasserot-Golaz S, Ory S, Gasman S, Vitale N. Phospholipase D1-generated phosphatidic acid modulates secretory granule trafficking from biogenesis to compensatory endocytosis in neuroendocrine cells. Adv Biol Regul 2021; 83:100844. [PMID: 34876384 DOI: 10.1016/j.jbior.2021.100844] [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: 11/01/2021] [Revised: 11/22/2021] [Accepted: 11/24/2021] [Indexed: 11/16/2022]
Abstract
Calcium-regulated exocytosis is a multi-step process that allows specialized secretory cells to release informative molecules such as neurotransmitters, neuropeptides, and hormones for intercellular communication. The biogenesis of secretory vesicles from the Golgi cisternae is followed by their transport towards the cell periphery and their docking and fusion to the exocytic sites of the plasma membrane allowing release of vesicular content. Subsequent compensatory endocytosis of the protein and lipidic constituents of the vesicles maintains cell homeostasis. Despite the fact that lipids represent the majority of membrane constituents, little is known about their contribution to these processes. Using a combination of electrochemical measurement of single chromaffin cell catecholamine secretion and electron microscopy of roof-top membrane sheets associated with genetic, silencing and pharmacological approaches, we recently reported that diverse phosphatidic acid (PA) species regulates catecholamine release efficiency by controlling granule docking and fusion kinetics. The enzyme phospholipase D1 (PLD1), producing PA from phosphatidylcholine, seems to be the major responsible of these effects in this model. Here, we extended this work using spinning disk confocal microscopy showing that inhibition of PLD activity also reduced the velocity of granules undergoing a directed motion. Furthermore, a dopamine β-hydroxylase (DβH) internalization assay revealed that PA produced by PLD is required for an optimal recovery of vesicular membrane content by compensatory endocytosis. Thus, among numerous roles that have been attributed to PA our work gives core to the key regulatory role in secretion that has been proposed in different cell models. Few leads to explain these multiple functions of PA along the secretory pathway are discussed.
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Affiliation(s)
- Emeline Tanguy
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000, Strasbourg, France
| | - Alexander Wolf
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000, Strasbourg, France
| | - Qili Wang
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000, Strasbourg, France
| | - Sylvette Chasserot-Golaz
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000, Strasbourg, France
| | - Stéphane Ory
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000, Strasbourg, France
| | - Stéphane Gasman
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000, Strasbourg, France
| | - Nicolas Vitale
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000, Strasbourg, France.
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17
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Axmann M, Plochberger B, Mikula M, Weber F, Strobl WM, Stangl H. Plasma Membrane Lipids: An Important Binding Site for All Lipoprotein Classes. MEMBRANES 2021; 11:membranes11110882. [PMID: 34832111 PMCID: PMC8622984 DOI: 10.3390/membranes11110882] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 11/12/2021] [Accepted: 11/12/2021] [Indexed: 12/23/2022]
Abstract
Cholesterol is one of the main constituents of plasma membranes; thus, its supply is of utmost importance. This review covers the known mechanisms of cholesterol transfer from circulating lipoprotein particles to the plasma membrane, and vice versa. To achieve homeostasis, the human body utilizes cellular de novo synthesis and extracellular transport particles for supply of cholesterol and other lipids via the blood stream. These lipoprotein particles can be classified according to their density: chylomicrons, very low, low, and high-density lipoprotein (VLDL, LDL, and HDL, respectively). They deliver and receive their lipid loads, most importantly cholesterol, to and from cells by several redundant routes. Defects in one of these pathways (e.g., due to mutations in receptors) usually are not immediately fatal. Several redundant pathways, at least temporarily, compensate for the loss of one or more of them, but the defects trigger systemic diseases, such as atherosclerosis later on. Recently, intracellular membrane–membrane contact sites were shown to be involved in intracellular cholesterol transfer and the plasma membrane itself has been proposed to act as a binding site for lipoprotein-mediated cargo unloading.
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Affiliation(s)
- Markus Axmann
- School of Medical Engineering and Applied Social Sciences, University of Applied Sciences Upper Austria, Garnisonstrasse 21, 4020 Linz, Austria; (M.A.); (B.P.); (F.W.)
| | - Birgit Plochberger
- School of Medical Engineering and Applied Social Sciences, University of Applied Sciences Upper Austria, Garnisonstrasse 21, 4020 Linz, Austria; (M.A.); (B.P.); (F.W.)
| | - Mario Mikula
- Center for Pathobiochemistry and Genetics, Institute for Medical Genetics, Medical University of Vienna, Währingerstrasse 10, 1090 Vienna, Austria;
| | - Florian Weber
- School of Medical Engineering and Applied Social Sciences, University of Applied Sciences Upper Austria, Garnisonstrasse 21, 4020 Linz, Austria; (M.A.); (B.P.); (F.W.)
| | - Witta Monika Strobl
- Center for Pathobiochemistry and Genetics, Institute for Medical Chemistry, Medical University of Vienna, Währingerstrasse 10, 1090 Vienna, Austria;
| | - Herbert Stangl
- Center for Pathobiochemistry and Genetics, Institute for Medical Chemistry, Medical University of Vienna, Währingerstrasse 10, 1090 Vienna, Austria;
- Correspondence:
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18
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Haque ME, Akther M, Azam S, Kim IS, Lin Y, Lee YH, Choi DK. Targeting α-synuclein aggregation and its role in mitochondrial dysfunction in Parkinson's disease. Br J Pharmacol 2021; 179:23-45. [PMID: 34528272 DOI: 10.1111/bph.15684] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Revised: 08/17/2021] [Accepted: 08/25/2021] [Indexed: 11/28/2022] Open
Abstract
Lewy bodies that contain aggregated α-synuclein (α-syn) in the dopaminergic (DA) neuron are the main culprit behind neurodegeneration in Parkinson's disease (PD). Besides, mitochondrial dysfunction has a well established and prominent role in the pathogenesis of PD. However, the exact mechanism by which α-syn causes dopaminergic neuronal loss was unclear. Recent evidence suggests that aggregated α-syn localises in the mitochondria and contributes to oxidative stress-mediated apoptosis in neurons. Therefore, the involvement of aggregated α-syn in mitochondrial dysfunction-mediated neuronal loss has made it an emerging drug target for the treatment of PD. However, the exact mechanism by which α-syn permeabilises through the mitochondrial membrane and affects the electron transport chain remains under investigation. In the present study, we describe mitochondria-α-syn interactions and how α-syn aggregation modulates mitochondrial homeostasis in PD pathogenesis. We also discuss recent therapeutic interventions targeting α-syn aggregation that may help researchers to design novel therapeutic treatments for PD.
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Affiliation(s)
- Md Ezazul Haque
- Department of Applied Life Science, Graduate School, BK21 Program, Konkuk University, Chungju, Republic of Korea
| | - Mahbuba Akther
- Department of Applied Life Science, Graduate School, BK21 Program, Konkuk University, Chungju, Republic of Korea
| | - Shofiul Azam
- Department of Applied Life Science, Graduate School, BK21 Program, Konkuk University, Chungju, Republic of Korea
| | - In-Su Kim
- Department of Biotechnology, College of Biomedical and Health Science, Research Institute of Inflammatory Disease (RID), Konkuk University, Chungju, Republic of Korea
| | - Yuxi Lin
- Research Center for Bioconvergence Analysis, Korea Basic Science Institute, Ochang, Chung Buk, Republic of Korea
| | - Young-Ho Lee
- Research Center for Bioconvergence Analysis, Korea Basic Science Institute, Ochang, Chung Buk, Republic of Korea.,Department of Bio-analytical Science, University of Science and Technology, Daejeon, Republic of Korea.,Graduate School of Analytical Science and Technology, Chungnam National University, Daejeon, Republic of Korea.,Research Headquarters, Korea Brain Research Institute, Daegu, Republic of Korea
| | - Dong-Kug Choi
- Department of Applied Life Science, Graduate School, BK21 Program, Konkuk University, Chungju, Republic of Korea.,Department of Biotechnology, College of Biomedical and Health Science, Research Institute of Inflammatory Disease (RID), Konkuk University, Chungju, Republic of Korea
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19
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Zhang J, Pinello JF, Fernández I, Baquero E, Fedry J, Rey FA, Snell WJ. Species-specific gamete recognition initiates fusion-driving trimer formation by conserved fusogen HAP2. Nat Commun 2021; 12:4380. [PMID: 34282138 PMCID: PMC8289870 DOI: 10.1038/s41467-021-24613-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 06/15/2021] [Indexed: 12/02/2022] Open
Abstract
Recognition and fusion between gametes during fertilization is an ancient process. Protein HAP2, recognized as the primordial eukaryotic gamete fusogen, is a structural homolog of viral class II fusion proteins. The mechanisms that regulate HAP2 function, and whether virus-fusion-like conformational changes are involved, however, have not been investigated. We report here that fusion between plus and minus gametes of the green alga Chlamydomonas indeed requires an obligate conformational rearrangement of HAP2 on minus gametes from a labile, prefusion form into the stable homotrimers observed in structural studies. Activation of HAP2 to undergo its fusogenic conformational change occurs only upon species-specific adhesion between the two gamete membranes. Following a molecular mechanism akin to fusion of enveloped viruses, the membrane insertion capacity of the fusion loop is required to couple formation of trimers to gamete fusion. Thus, species-specific membrane attachment is the gateway to fusion-driving HAP2 rearrangement into stable trimers. HAP2 is essential for gamete fusion during fertilization and is conserved among eukaryotes. Here the authors show that species-specific adhesion between Chlamydomonas plus and minus gametes initiates HAP2 to undergo a fusogenic conformational change into homotrimers via a molecular mechanism akin to that of enveloped viruses.
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Affiliation(s)
- Jun Zhang
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, USA
| | - Jennifer F Pinello
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, USA
| | - Ignacio Fernández
- Unité de Virologie Structurale, Virology Department and CNRS UMR 3569, Institut Pasteur, Paris, France
| | - Eduard Baquero
- Unité de Virologie Structurale, Virology Department and CNRS UMR 3569, Institut Pasteur, Paris, France
| | - Juliette Fedry
- Unité de Virologie Structurale, Virology Department and CNRS UMR 3569, Institut Pasteur, Paris, France
| | - Félix A Rey
- Unité de Virologie Structurale, Virology Department and CNRS UMR 3569, Institut Pasteur, Paris, France
| | - William J Snell
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, USA.
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20
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Dabral D, van den Bogaart G. The Roles of Phospholipase A 2 in Phagocytes. Front Cell Dev Biol 2021; 9:673502. [PMID: 34179001 PMCID: PMC8222813 DOI: 10.3389/fcell.2021.673502] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Accepted: 05/11/2021] [Indexed: 12/21/2022] Open
Abstract
Phagocytic cells, such as macrophages, neutrophils, and dendritic cells, ingest particles larger than about 0.5 μM and thereby clear microbial pathogens and malignant cells from the body. These phagocytic cargoes are proteolytically degraded within the lumen of phagosomes, and peptides derived from them are presented on Major Histocompatibility Complexes (MHC) for the activation of T cells. Mammalian PLA2 isozymes belong to a large family of enzymes that cleave phospholipids at the second position of the glycerol backbone, releasing a free fatty acid and a lysolipid moiety. In human macrophages, at least 15 different PLA2 forms are expressed, and expression of many of these is dependent on pathogenic stimulation. Intriguing questions are why so many PLA2 forms are expressed in macrophages, and what are the functional consequences of their altered gene expression after encountering pathogenic stimuli. In this review, we discuss the evidence of the differential roles of different forms of PLA2 in phagocytic immune cells. These roles include: lipid signaling for immune cell activation, initial phagocytic particle uptake, microbial action for the killing and degradation of ingested microbes, and the repair of membranes induced by oxygen radicals. We also discuss the roles of PLA2 in the subsequent digestion of ingested phagocytic cargoes for antigen presentation to T cells.
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Affiliation(s)
- Deepti Dabral
- Department of Molecular Immunology and Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
| | - Geert van den Bogaart
- Department of Molecular Immunology and Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
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21
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Sapp KC, Beaven AH, Sodt AJ. Spatial extent of a single lipid's influence on bilayer mechanics. Phys Rev E 2021; 103:042413. [PMID: 34005918 DOI: 10.1103/physreve.103.042413] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Accepted: 03/25/2021] [Indexed: 11/07/2022]
Abstract
To what spatial extent does a single lipid affect the mechanical properties of the membrane that surrounds it? The lipid composition of a membrane determines its mechanical properties. The shapes available to the membrane depend on its compositional material properties, and therefore, the lipid environment. Because each individual lipid species' chemistry is different, it is important to know its range of influence on membrane mechanical properties. This is defined herein as the lipid's mechanical extent. Here, a lipid's mechanical extent is determined by quantifying lipid redistribution and the average curvature that lipid species experience on fluctuating membrane surfaces. A surprising finding is that, unlike unsaturated lipids, saturated lipids have a complicated, nonlocal effect on the surrounding surface, with the interaction strength maximal at a finite length-scale. The methodology provides the means to substantially enrich curvature-energy models of membrane structures, quantifying what was previously only conjecture.
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Affiliation(s)
- Kayla C Sapp
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland 20847, USA
| | - Andrew H Beaven
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland 20847, USA.,National Institute of General Medical Sciences, Bethesda, Maryland 20892, USA
| | - Alexander J Sodt
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland 20847, USA
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22
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Beaven AH, Arnarez C, Lyman E, Bennett WFD, Sodt AJ. Curvature Energetics Determined by Alchemical Simulation on Four Topologically Distinct Lipid Phases. J Phys Chem B 2021; 125:1815-1824. [PMID: 33570958 PMCID: PMC9069320 DOI: 10.1021/acs.jpcb.0c09458] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The relative curvature energetics of two lipids are tested using thermodynamic integration (TI) on four topologically distinct lipid phases. Simulations use TI to switch between choline headgroup lipids (POPC; that prefers to be flat) and ethanolamine headgroup lipids (POPE; that prefer, for example, the inner monolayer of vesicles). The thermodynamical moving of the lipids between planar, inverse hexagonal (HII), cubic (QII; Pn3m space group), and vesicle topologies reveals differences in material parameters that were previously challenging to access. The methodology allows for predictions of two important lipid material properties: the difference in POPC/POPE monolayer intrinsic curvature (ΔJ0) and the difference in POPC/POPE monolayer Gaussian curvature modulus (Δκ̅m), both of which are connected to the energetics of topological variation. Analysis of the TI data indicates that, consistent with previous experiment and simulation, the J0 of POPE is more negative than POPC (ΔJ0 = -0.018 ± 0.001 Å-1). The theoretical framework extracts significant differences in κ̅m of which POPE is less negative than POPC by 2.0 to 4.0 kcal/mol. The range of these values is determined by considering subsets of the simulations, and disagreement between these subsets suggests separate mechanical parameters at very high curvature. Finally, the fit of the TI data to the model indicates that the position of the pivotal plane of curvature is not constant across topologies at high curvature. Overall, the results offer insights into lipid material properties, the limits of a single HC model, and how to test them using simulation.
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Affiliation(s)
- Andrew H Beaven
- Unit on Membrane Chemical Physics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, United States.,Postdoctoral Research Associate Program, National Institute of General Medical Sciences, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Clément Arnarez
- Department of Physics and Astronomy, Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Edward Lyman
- Department of Physics and Astronomy, Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - W F Drew Bennett
- Biosciences and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Alexander J Sodt
- Unit on Membrane Chemical Physics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, United States
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23
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Nieto‐Garai JA, Arboleya A, Otaegi S, Chojnacki J, Casas J, Fabriàs G, Contreras F, Kräusslich H, Lorizate M. Cholesterol in the Viral Membrane is a Molecular Switch Governing HIV-1 Env Clustering. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:2003468. [PMID: 33552873 PMCID: PMC7856888 DOI: 10.1002/advs.202003468] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 10/13/2020] [Indexed: 05/07/2023]
Abstract
HIV-1 entry requires the redistribution of envelope glycoproteins (Env) into a cluster and the presence of cholesterol (chol) in the viral membrane. However, the molecular mechanisms underlying the specific role of chol in infectivity and the driving force behind Env clustering remain unknown. Here, gp41 is demonstrated to directly interact with chol in the viral membrane via residues 751-854 in the cytoplasmic tail (CT751-854). Super-resolution stimulated emission depletion (STED) nanoscopy analysis of Env distribution further demonstrates that both truncation of gp41 CT751-854 and depletion of chol leads to dispersion of Env clusters in the viral membrane and inhibition of virus entry. This work reveals a direct interaction of gp41 CT with chol and indicates that this interaction is an important orchestrator of Env clustering.
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Affiliation(s)
- Jon Ander Nieto‐Garai
- Instituto Biofisika (UPV/EHU, CSIC)University of the Basque CountryLeioaE‐48940Spain
- Fundación Biofísica Bizkaia/Biofisika Bizkaia Fundazioa (FBB)Barrio Sarriena s/nLeioaE‐48940Spain
| | - Aroa Arboleya
- Instituto Biofisika (UPV/EHU, CSIC)University of the Basque CountryLeioaE‐48940Spain
- Fundación Biofísica Bizkaia/Biofisika Bizkaia Fundazioa (FBB)Barrio Sarriena s/nLeioaE‐48940Spain
| | - Sara Otaegi
- Instituto Biofisika (UPV/EHU, CSIC)University of the Basque CountryLeioaE‐48940Spain
- Department of Biochemistry and Molecular BiologyFaculty of Science and TechnologyUniversity of the Basque CountryLeioaE‐48940Spain
| | | | - Josefina Casas
- Research Unit on BioActive Molecules. Department of Biological ChemistryInstitute for Advanced Chemistry of Catalonia (IQAC‐CSIC)BarcelonaCatalonia08034Spain
- Liver and Digestive Diseases Networking Biomedical Research Center (CIBEREHD) ISCIIMadrid28029Spain
| | - Gemma Fabriàs
- Research Unit on BioActive Molecules. Department of Biological ChemistryInstitute for Advanced Chemistry of Catalonia (IQAC‐CSIC)BarcelonaCatalonia08034Spain
- Liver and Digestive Diseases Networking Biomedical Research Center (CIBEREHD) ISCIIMadrid28029Spain
| | - F‐Xabier Contreras
- Instituto Biofisika (UPV/EHU, CSIC)University of the Basque CountryLeioaE‐48940Spain
- Department of Biochemistry and Molecular BiologyFaculty of Science and TechnologyUniversity of the Basque CountryLeioaE‐48940Spain
- IkerbasqueBasque Foundation for ScienceBilbao48013Spain
| | - Hans‐Georg Kräusslich
- Department of Infectious DiseasesVirologyUniversitätsklinikum HeidelbergHeidelberg69120Germany
| | - Maier Lorizate
- Instituto Biofisika (UPV/EHU, CSIC)University of the Basque CountryLeioaE‐48940Spain
- Department of Biochemistry and Molecular BiologyFaculty of Science and TechnologyUniversity of the Basque CountryLeioaE‐48940Spain
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24
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Rahman MM, Williams SJ. Membrane tension may define the deadliest virus infection. COLLOID AND INTERFACE SCIENCE COMMUNICATIONS 2021; 40:100338. [PMID: 34722169 PMCID: PMC8544801 DOI: 10.1016/j.colcom.2020.100338] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 11/06/2020] [Accepted: 11/08/2020] [Indexed: 05/23/2023]
Abstract
This manuscript describes the potentially significant role of interfacial tension in viral infection. Our hypothesis is based on evidence from drop coalescence hydrodynamics. A change in membrane tension can trigger fusion between the vesicle and cell such that genetic material, like viral RNA, can subsequently be transported to the cell interior. In other cases, RNA may reside near the cell membrane inside the cell, which could make their removal energetically unfavorable because of hydrodynamic interactions between membrane and RNA. Interfacial tension of the virus membrane can be modulated by temperature, among many other factors, of the mucosa layer. We discuss our hypothesis within the scope of recent SARS-CoV-2 studies where temperature-dependent membrane surface tension could be impacted through different atmospheric conditions, air conditioning systems, and the use of masks.
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Affiliation(s)
| | - Stuart J Williams
- Department of Mechanical Engineering, University of Louisville, KY, USA
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25
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Tanguy E, Wolf A, Montero-Hadjadje M, Gasman S, Bader MF, Vitale N. Phosphatidic acid: Mono- and poly-unsaturated forms regulate distinct stages of neuroendocrine exocytosis. Adv Biol Regul 2020; 79:100772. [PMID: 33288473 DOI: 10.1016/j.jbior.2020.100772] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 11/16/2020] [Accepted: 11/25/2020] [Indexed: 10/22/2022]
Abstract
Lipids have emerged as important actors in an ever-growing number of key functions in cell biology over the last few years. Among them, glycerophospholipids are major constituents of cellular membranes. Because of their amphiphilic nature, phospholipids form lipid bilayers that are particularly useful to isolate cellular content from the extracellular medium, but also to define intracellular compartments. Interestingly, phospholipids come in different flavors based on their fatty acyl chain composition. Indeed, lipidomic analyses have revealed the presence in cellular membranes of up to 50 different species of an individual class of phospholipid, opening the possibility of multiple functions for a single class of phospholipid. In this review we will focus on phosphatidic acid (PA), the simplest phospholipid, that plays both structural and signaling functions. Among the numerous roles that have been attributed to PA, a key regulatory role in secretion has been proposed in different cell models. We review here the evidences that support the idea that mono- and poly-unsaturated PA control distinct steps in hormone secretion from neuroendocrine cells.
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Affiliation(s)
- Emeline Tanguy
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000 Strasbourg, France
| | - Alexander Wolf
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000 Strasbourg, France
| | - Maité Montero-Hadjadje
- Normandie Univ, UNIROUEN, INSERM, U1239, Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale de Normandie, 76000, Rouen, France
| | - Stéphane Gasman
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000 Strasbourg, France
| | - Marie-France Bader
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000 Strasbourg, France
| | - Nicolas Vitale
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000 Strasbourg, France.
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26
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Akimov SA, Kondrashov OV, Zimmerberg J, Batishchev OV. Ectodomain Pulling Combines with Fusion Peptide Inserting to Provide Cooperative Fusion for Influenza Virus and HIV. Int J Mol Sci 2020; 21:ijms21155411. [PMID: 32751407 PMCID: PMC7432320 DOI: 10.3390/ijms21155411] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 07/24/2020] [Accepted: 07/28/2020] [Indexed: 12/18/2022] Open
Abstract
Enveloped viruses include the most dangerous human and animal pathogens, in particular coronavirus, influenza virus, and human immunodeficiency virus (HIV). For these viruses, receptor binding and entry are accomplished by a single viral envelope protein (termed the fusion protein), the structural changes of which trigger the remodeling and merger of the viral and target cellular membranes. The number of fusion proteins required for fusion activity is still under debate, and several studies report this value to range from 1 to 9 for type I fusion proteins. Here, we consider the earliest stage of viral fusion based on the continuum theory of membrane elasticity. We demonstrate that membrane deformations induced by the oblique insertion of amphipathic fusion peptides mediate the lateral interaction of these peptides and drive them to form into a symmetric fusion rosette. The pulling force produced by the structural rearrangements of the fusion protein ectodomains gives additional torque, which deforms the membrane and additionally stabilizes the symmetric fusion rosette, thus allowing a reduction in the number of fusion peptides needed for fusion. These findings can resolve the large range of published cooperativity indices for HIV, influenza, and other type I fusion proteins.
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Affiliation(s)
- Sergey A. Akimov
- Laboratory of Bioelectrochemistry, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy Prospekt, 119071 Moscow, Russia; (O.V.K.); (O.V.B.)
- Correspondence: ; Tel.: +7-495-955-4776
| | - Oleg V. Kondrashov
- Laboratory of Bioelectrochemistry, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy Prospekt, 119071 Moscow, Russia; (O.V.K.); (O.V.B.)
| | - Joshua Zimmerberg
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA;
| | - Oleg V. Batishchev
- Laboratory of Bioelectrochemistry, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy Prospekt, 119071 Moscow, Russia; (O.V.K.); (O.V.B.)
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27
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Akimov SA, Molotkovsky RJ, Kuzmin PI, Galimzyanov TR, Batishchev OV. Continuum Models of Membrane Fusion: Evolution of the Theory. Int J Mol Sci 2020; 21:E3875. [PMID: 32485905 PMCID: PMC7312925 DOI: 10.3390/ijms21113875] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 05/24/2020] [Accepted: 05/27/2020] [Indexed: 12/18/2022] Open
Abstract
Starting from fertilization, through tissue growth, hormone secretion, synaptic transmission, and sometimes morbid events of carcinogenesis and viral infections, membrane fusion regulates the whole life of high organisms. Despite that, a lot of fusion processes still lack well-established models and even a list of main actors. A merger of membranes requires their topological rearrangements controlled by elastic properties of a lipid bilayer. That is why continuum models based on theories of membrane elasticity are actively applied for the construction of physical models of membrane fusion. Started from the view on the membrane as a structureless film with postulated geometry of fusion intermediates, they developed along with experimental and computational techniques to a powerful tool for prediction of the whole process with molecular accuracy. In the present review, focusing on fusion processes occurring in eukaryotic cells, we scrutinize the history of these models, their evolution and complication, as well as open questions and remaining theoretical problems. We show that modern approaches in this field allow continuum models of membrane fusion to stand shoulder to shoulder with molecular dynamics simulations, and provide the deepest understanding of this process in multiple biological systems.
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Affiliation(s)
- Sergey A. Akimov
- Laboratory of Bioelectrochemistry, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy Prospekt, 119071 Moscow, Russia; (R.J.M.); (P.I.K.); (T.R.G.); (O.V.B.)
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28
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Enoki TA, Feigenson GW. Asymmetric Bilayers by Hemifusion: Method and Leaflet Behaviors. Biophys J 2019; 117:1037-1050. [PMID: 31493862 DOI: 10.1016/j.bpj.2019.07.054] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 06/13/2019] [Accepted: 07/08/2019] [Indexed: 01/03/2023] Open
Abstract
We describe a new method to prepare asymmetric giant unilamellar vesicles (aGUVs) via hemifusion. Hemifusion of giant unilamellar vesicles and a supported lipid bilayer, triggered by calcium, promotes the lipid exchange of the fused outer leaflets mediated by lipid diffusion. We used different fluorescent dyes to monitor the inner and the outer leaflets of the unsupported aGUVs. We confirmed that almost all newly exchanged lipids in the aGUVs are found in the outer leaflet of these asymmetric vesicles. In addition, we test the stability of the aGUVs formed by hemifusion in preserving their contents during the procedure. For aGUVs prepared from the hemifusion of giant unilamellar vesicles composed of 1,2-distearoyl-sn-glycero-3-phosphocholine/1,2-dioleoyl-sn-glycero-3-phosphocholine/cholesterol = 0.39/0.39/0.22 and a supported lipid bilayer of 1,2-dioleoyl-sn-glycero-3-phosphocholine/cholesterol = 0.8/0.2, we observed the exchanged lipids to alter the bilayer properties. To access the physical and chemical properties of the asymmetric bilayer, we monitored the dye partition coefficients of individual leaflets and the generalized polarization of the fluorescence probe 6-dodecanoyl-2-[ N-methyl-N-(carboxymethyl)amino] naphthalene, a sensor for the lipid packing/order of its surroundings. For a high percentage of lipid exchange (>70%), the dye partition indicates induced-disordered and induced-ordered domains. The induced domains have distinct lipid packing/order compared to the symmetric liquid-disordered and liquid-ordered domains.
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Affiliation(s)
- Thais A Enoki
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York.
| | - Gerald W Feigenson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York
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29
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Jung JH. Synaptic Vesicles Having Large Contact Areas with the Presynaptic Membrane are Preferentially Hemifused at Active Zones of Frog Neuromuscular Junctions Fixed during Synaptic Activity. Int J Mol Sci 2019; 20:ijms20112692. [PMID: 31159267 PMCID: PMC6600287 DOI: 10.3390/ijms20112692] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 05/23/2019] [Accepted: 05/29/2019] [Indexed: 12/29/2022] Open
Abstract
Synaptic vesicles dock on the presynaptic plasma membrane of axon terminals and become ready to fuse with the presynaptic membrane or primed. Fusion of the vesicle membrane and presynaptic membrane results in the formation of a pore between the membranes, through which the vesicle’s neurotransmitter is released into the synaptic cleft. A recent electron tomography study on frog neuromuscular junctions fixed at rest showed that there is no discernible gap between or merging of the membrane of docked synaptic vesicles with the presynaptic membrane, however, the extent of the contact area between the membrane of docked synaptic vesicles and the presynaptic membrane varies 10-fold with a normal distribution. The study also showed that when the neuromuscular junctions are fixed during repetitive electrical nerve stimulation, the portion of large contact areas in the distribution is reduced compared to the portion of small contact areas, suggesting that docked synaptic vesicles with the largest contact areas are greatly primed to fuse with the membrane. Furthermore, the finding of several hemifused synaptic vesicles among the docked vesicles was briefly reported. Here, the spatial relationship of 81 synaptic vesicles with the presynaptic membrane at active zones of the neuromuscular junctions fixed during stimulation is described in detail. For the most of the vesicles, the combined thickness of each of their contact sites was not different from the sum of the membrane thicknesses of the vesicle membrane and presynaptic membrane, similar to the docked vesicles at active zones of the resting neuromuscular junctions. However, the combined membrane thickness of a small portion of the vesicles was considerably less than the sum of the membrane thicknesses, indicating that the membranes at their contact sites were fixed in a state of hemifusion. Moreover, the hemifused vesicles were found to have large contact areas with the presynaptic membrane. These findings support the recently proposed hypothesis that, at frog neuromuscular junctions, docked synaptic vesicles with the largest contact areas are most primed for fusion with the presynaptic membrane, and that hemifusion is a fusion intermediate step of the vesicle membrane with the presynaptic membrane for synaptic transmission.
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Affiliation(s)
- Jae Hoon Jung
- Department of Biology, Texas A&M University, College Station, TX 77845, USA.
- Department of Physics, Stanford University School of Humanities and Sciences, Stanford, CA 94309, USA.
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30
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Arachidonic acid and lysophosphatidylcholine inhibit multiple late steps of regulated exocytosis. Biochem Biophys Res Commun 2019; 515:261-267. [PMID: 31126681 DOI: 10.1016/j.bbrc.2019.05.106] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Accepted: 05/15/2019] [Indexed: 02/05/2023]
Abstract
The canonical Phospholipase A2 (PLA2) metabolites lysophosphatidylcholine (LPC) and arachidonic acid (ARA) affect regulated exocytosis in a wide variety of cells and are proposed to directly influence membrane merger owing to their respective spontaneous curvatures. According to the Stalk-pore hypothesis, negative curvature ARA inhibits and promotes bilayer merger upon introduction into the distal or proximal monolayers, respectively; in contrast, with positive curvature, LPC has the opposite effects. Using fully primed, release-ready native cortical secretory vesicles (CV), well-established fusion assays and standardized lipid analyses, we show that exogenous ARA and LPC, as well as their non-metabolizable analogous, ETYA and ET-18-OCH3, inhibit the docking/priming and membrane merger steps, respectively, of regulated exocytosis.
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31
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Dabral D, Coorssen JR. Combined targeted Omic and Functional Assays Identify Phospholipases A₂ that Regulate Docking/Priming in Calcium-Triggered Exocytosis. Cells 2019; 8:cells8040303. [PMID: 30986994 PMCID: PMC6523306 DOI: 10.3390/cells8040303] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Revised: 03/24/2019] [Accepted: 03/28/2019] [Indexed: 12/12/2022] Open
Abstract
The fundamental molecular mechanism underlying the membrane merger steps of regulated exocytosis is highly conserved across cell types. Although involvement of Phospholipase A₂ (PLA₂) in regulated exocytosis has long been suggested, its function or that of its metabolites-a lyso-phospholipid and a free fatty acid-remain somewhat speculative. Here, using a combined bioinformatics and top-down discovery proteomics approach, coupled with lipidomic analyses, PLA₂ were found to be associated with release-ready cortical secretory vesicles (CV) that possess the minimal molecular machinery for docking, Ca2+ sensing and membrane fusion. Tightly coupling the molecular analyses with well-established quantitative fusion assays, we show for the first time that inhibition of a CV surface calcium independent intracellular PLA₂ and a luminal secretory PLA₂ significantly reduce docking/priming in the late steps of regulated exocytosis, indicating key regulatory roles in the critical step(s) preceding membrane merger.
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Affiliation(s)
- Deepti Dabral
- Molecular Physiology and Molecular Medicine Research Group, School of Medicine, Western Sydney University, Campbelltown Campus, NSW 2560, Australia.
| | - Jens R Coorssen
- Department of Health Sciences, Faculty of Applied Health Sciences and Department of Biological Sciences, Faculty of Mathematics & Science, Brock University, St. Catharines, ON L2S 3A1, Canada.
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32
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Fusion assays for model membranes: a critical review. ADVANCES IN BIOMEMBRANES AND LIPID SELF-ASSEMBLY 2019. [DOI: 10.1016/bs.abl.2019.09.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
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33
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Nieto-Garai JA, Glass B, Bunn C, Giese M, Jennings G, Brankatschk B, Agarwal S, Börner K, Contreras FX, Knölker HJ, Zankl C, Simons K, Schroeder C, Lorizate M, Kräusslich HG. Lipidomimetic Compounds Act as HIV-1 Entry Inhibitors by Altering Viral Membrane Structure. Front Immunol 2018; 9:1983. [PMID: 30233582 PMCID: PMC6131562 DOI: 10.3389/fimmu.2018.01983] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 08/13/2018] [Indexed: 12/16/2022] Open
Abstract
The envelope of Human Immunodeficiency Virus type 1 (HIV-1) consists of a liquid-ordered membrane enriched in raft lipids and containing the viral glycoproteins. Previous studies demonstrated that changes in viral membrane lipid composition affecting membrane structure or curvature can impair infectivity. Here, we describe novel antiviral compounds that were identified by screening compound libraries based on raft lipid-like scaffolds. Three distinct molecular structures were chosen for mode-of-action studies, a sterol derivative (J391B), a sphingosine derivative (J582C) and a long aliphatic chain derivative (IBS70). All three target the viral membrane and inhibit virus infectivity at the stage of fusion without perturbing virus stability or affecting virion-associated envelope glycoproteins. Their effect did not depend on the expressed envelope glycoproteins or a specific entry route, being equally strong in HIV pseudotypes carrying VSV-G or MLV-Env glycoproteins. Labeling with laurdan, a reporter of membrane order, revealed different membrane structure alterations upon compound treatment of HIV-1, which correlated with loss of infectivity. J582C and IBS70 decreased membrane order in distinctive ways, whereas J391B increased membrane order. The compounds' effects on membrane order were reproduced in liposomes generated from extracted HIV lipids and thus independent both of virion proteins and of membrane leaflet asymmetry. Remarkably, increase of membrane order by J391B required phosphatidylserine, a lipid enriched in the HIV envelope. Counterintuitively, mixtures of two compounds with opposite effects on membrane order, J582C and J391B, did not neutralize each other but synergistically inhibited HIV infection. Thus, altering membrane order, which can occur by different mechanisms, constitutes a novel antiviral mode of action that may be of general relevance for enveloped viruses and difficult to overcome by resistance development.
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Affiliation(s)
- Jon Ander Nieto-Garai
- Departamento de Bioquímica y Biología Molecular, Instituto Biofisika (CSIC, UPV/EHU), Universidad del País Vasco, Bilbao, Spain
| | - Bärbel Glass
- Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, Heidelberg, Germany
| | | | | | | | - Beate Brankatschk
- JADO Technologies, Dresden, Germany.,Membrane Biochemistry Group, Paul-Langerhans-Institute Dresden, Helmholtz Zentrum München at the University Hospital and Faculty of Medicine Carl Gustav Carus, Dresden, Germany
| | - Sameer Agarwal
- JADO Technologies, Dresden, Germany.,Department of Chemistry, Technische Universität Dresden, Dresden, Germany
| | - Kathleen Börner
- Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, Heidelberg, Germany
| | - F Xabier Contreras
- Departamento de Bioquímica y Biología Molecular, Instituto Biofisika (CSIC, UPV/EHU), Universidad del País Vasco, Bilbao, Spain.,Ikerbasque, Basque Foundation for Science, Bilbao, Spain
| | - Hans-Joachim Knölker
- JADO Technologies, Dresden, Germany.,Department of Chemistry, Technische Universität Dresden, Dresden, Germany
| | - Claudia Zankl
- JADO Technologies, Dresden, Germany.,Department of Chemistry, Technische Universität Dresden, Dresden, Germany
| | - Kai Simons
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Cornelia Schroeder
- JADO Technologies, Dresden, Germany.,Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Department of Anatomy, Medical Faculty Carl-Gustav-Carus, Technische Universität Dresden, Dresden, Germany
| | - Maier Lorizate
- Departamento de Bioquímica y Biología Molecular, Instituto Biofisika (CSIC, UPV/EHU), Universidad del País Vasco, Bilbao, Spain
| | - Hans-Georg Kräusslich
- Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, Heidelberg, Germany
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34
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Gardner JM, Abrams CF. Lipid flip-flop vs. lateral diffusion in the relaxation of hemifusion diaphragms. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1452-1459. [DOI: 10.1016/j.bbamem.2018.04.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 03/29/2018] [Accepted: 04/17/2018] [Indexed: 10/17/2022]
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35
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Gardner JM, Abrams CF. Rate of hemifusion diaphragm dissipation and ability to form three-junction bound HD determined by lipid composition. J Chem Phys 2018; 147:134903. [PMID: 28987088 DOI: 10.1063/1.4994320] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Though the hemifusion diaphragm (HD) is widely accepted as an intermediate in bilayer membrane fusion, lipid contributions toward HD stability and dynamics are still not fully understood. In this paper, we study large, binary, protein-free HD systems at varying compositions of negative intrinsic curvature (NIC) lipids using molecular dynamics (MD) simulations of a solvent-free coarse-grained lipid model. Under MD, initially created HDs are found to relax to three major end states depending on the composition and lipid intrinsic curvature. Low compositions of NIC lipids or weak intrinsic curvature result in double-bilayer end states, and moderate compositions of moderate to strong NIC lipids result in metastable fusion pores. Importantly, high compositions of moderate NIC lipids result in a metastable HD that persists beyond μs time scales. NIC lipids stabilize the HD by filling the junction core around the HD. Sorting of NIC lipids toward the three-junction region occurs in fused-endpoint systems, but no significant sorting was seen in systems that end in a double bilayer indicating that high line tension at the triple junction drives HD dissipation faster than sorting can enrich that junction enough to lower that line tension. The appearance of three end states dependent on the NIC lipid composition highlights the necessity of NIC lipids for non-leaky fusion.
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Affiliation(s)
- Jasmine M Gardner
- Department of Chemical and Biological Engineering, Drexel University, 3141 Chestnut St., Philadelphia, Pennsylvania 19104, USA
| | - Cameron F Abrams
- Department of Chemical and Biological Engineering, Drexel University, 3141 Chestnut St., Philadelphia, Pennsylvania 19104, USA
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36
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Pozo Devoto VM, Falzone TL. Mitochondrial dynamics in Parkinson's disease: a role for α-synuclein? Dis Model Mech 2018; 10:1075-1087. [PMID: 28883016 PMCID: PMC5611962 DOI: 10.1242/dmm.026294] [Citation(s) in RCA: 115] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 07/13/2017] [Indexed: 12/13/2022] Open
Abstract
The distinctive pathological hallmarks of Parkinson's disease are the progressive death of dopaminergic neurons and the intracellular accumulation of Lewy bodies enriched in α-synuclein protein. Several lines of evidence from the study of sporadic, familial and pharmacologically induced forms of human Parkinson's disease also suggest that mitochondrial dysfunction plays an important role in disease progression. Although many functions have been proposed for α-synuclein, emerging data from human and animal models of Parkinson's disease highlight a role for α-synuclein in the control of neuronal mitochondrial dynamics. Here, we review the α-synuclein structural, biophysical and biochemical properties that influence relevant mitochondrial dynamic processes such as fusion-fission, transport and clearance. Drawing on current evidence, we propose that α-synuclein contributes to the mitochondrial defects that are associated with the pathology of this common and progressive neurodegenerative disease. Summary: The authors review the α-synuclein structural, biophysical and biochemical properties that influence relevant mitochondrial physiological processes such as fusion-fission, transport and clearance, and propose that α-synuclein contributes to the mitochondrial defects that are associated with Parkinson's disease.
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Affiliation(s)
- Victorio M Pozo Devoto
- Instituto de Biología Celular y Neurociencias, IBCN (UBA-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155, Buenos Aires, CP1121, Argentina.,International Clinical Research Center (ICRC), St. Anne's University Hospital, CZ-65691, Brno, Czech Republic
| | - Tomas L Falzone
- Instituto de Biología Celular y Neurociencias, IBCN (UBA-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155, Buenos Aires, CP1121, Argentina .,Instituto de Biología y Medicina Experimental, IBYME-CONICET, Vuelta de Obligado 2490, Buenos Aires, CP1428, Argentina
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37
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Vanegas JM, Heinrich F, Rogers DM, Carson BD, La Bauve S, Vernon BC, Akgun B, Satija S, Zheng A, Kielian M, Rempe SB, Kent MS. Insertion of Dengue E into lipid bilayers studied by neutron reflectivity and molecular dynamics simulations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1216-1230. [PMID: 29447917 DOI: 10.1016/j.bbamem.2018.02.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 02/08/2018] [Accepted: 02/09/2018] [Indexed: 02/01/2023]
Abstract
The envelope (E) protein of Dengue virus rearranges to a trimeric hairpin to mediate fusion of the viral and target membranes, which is essential for infectivity. Insertion of E into the target membrane serves to anchor E and possibly also to disrupt local order within the membrane. Both aspects are likely to be affected by the depth of insertion, orientation of the trimer with respect to the membrane normal, and the interactions that form between trimer and membrane. In the present work, we resolved the depth of insertion, the tilt angle, and the fundamental interactions for the soluble portion of Dengue E trimers (sE) associated with planar lipid bilayer membranes of various combinations of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-rac-glycerol (POPG), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE), and cholesterol (CHOL) by neutron reflectivity (NR) and by molecular dynamics (MD) simulations. The results show that the tip of E containing the fusion loop (FL) is located at the interface of the headgroups and acyl chains of the outer leaflet of the lipid bilayers, in good agreement with prior predictions. The results also indicate that E tilts with respect to the membrane normal upon insertion, promoted by either the anionic lipid POPG or CHOL. The simulations show that tilting of the protein correlates with hydrogen bond formation between lysines and arginines located on the sides of the trimer close to the tip (K246, K247, and R73) and nearby lipid headgroups. These hydrogen bonds provide a major contribution to the membrane anchoring and may help to destabilize the target membrane.
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Affiliation(s)
- Juan M Vanegas
- Sandia National Laboratories, Albuquerque, NM, United States
| | - Frank Heinrich
- National Institute of Standards and Technology Center for Neutron Research, Gaithersburg, MD, United States; Department of Physics, Carnegie Mellon University, Pittsburgh, PA, United States
| | - David M Rogers
- Sandia National Laboratories, Albuquerque, NM, United States
| | - Bryan D Carson
- Sandia National Laboratories, Albuquerque, NM, United States
| | - Sadie La Bauve
- Sandia National Laboratories, Albuquerque, NM, United States
| | - Briana C Vernon
- Sandia National Laboratories, Albuquerque, NM, United States
| | - Bulent Akgun
- National Institute of Standards and Technology Center for Neutron Research, Gaithersburg, MD, United States
| | - Sushil Satija
- National Institute of Standards and Technology Center for Neutron Research, Gaithersburg, MD, United States
| | - Aihua Zheng
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Margaret Kielian
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Susan B Rempe
- Sandia National Laboratories, Albuquerque, NM, United States
| | - Michael S Kent
- Sandia National Laboratories, Albuquerque, NM, United States.
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38
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Chesarino NM, Compton AA, McMichael TM, Kenney AD, Zhang L, Soewarna V, Davis M, Schwartz O, Yount JS. IFITM3 requires an amphipathic helix for antiviral activity. EMBO Rep 2017; 18:1740-1751. [PMID: 28835547 DOI: 10.15252/embr.201744100] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 07/18/2017] [Accepted: 07/25/2017] [Indexed: 12/31/2022] Open
Abstract
Interferon-induced transmembrane protein 3 (IFITM3) is a cellular factor that blocks virus fusion with cell membranes. IFITM3 has been suggested to alter membrane curvature and fluidity, though its exact mechanism of action is unclear. Using a bioinformatic approach, we predict IFITM3 secondary structures and identify a highly conserved, short amphipathic helix within a hydrophobic region of IFITM3 previously thought to be a transmembrane domain. Consistent with the known ability of amphipathic helices to alter membrane properties, we show that this helix and its amphipathicity are required for the IFITM3-dependent inhibition of influenza virus, Zika virus, vesicular stomatitis virus, Ebola virus, and human immunodeficiency virus infections. The homologous amphipathic helix within IFITM1 is also required for the inhibition of infection, indicating that IFITM proteins possess a conserved mechanism of antiviral action. We further demonstrate that the amphipathic helix of IFITM3 is required to block influenza virus hemagglutinin-mediated membrane fusion. Overall, our results provide evidence that IFITM proteins utilize an amphipathic helix for inhibiting virus fusion.
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Affiliation(s)
- Nicholas M Chesarino
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, USA
| | - Alex A Compton
- Virus & Immunity Unit, Department of Virology, Institut Pasteur, Paris, France.,CNRS URA 3015, Paris, France.,HIV Dynamics and Replication Program, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
| | - Temet M McMichael
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, USA
| | - Adam D Kenney
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, USA
| | - Lizhi Zhang
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, USA
| | - Victoria Soewarna
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, USA
| | - Matthew Davis
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, USA
| | - Olivier Schwartz
- Virus & Immunity Unit, Department of Virology, Institut Pasteur, Paris, France.,CNRS URA 3015, Paris, France
| | - Jacob S Yount
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, USA
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39
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Dabral D, Coorssen JR. Phospholipase A 2: Potential roles in native membrane fusion. Int J Biochem Cell Biol 2017; 85:1-5. [PMID: 28131878 DOI: 10.1016/j.biocel.2017.01.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Revised: 12/29/2016] [Accepted: 01/22/2017] [Indexed: 12/22/2022]
Abstract
Membrane fusion is a fundamental molecular mechanism by which two apposed membrane bilayers coalesce in rapid, transient steps that enable the successive merging of the outer and inner leaflets allowing lipid intermixing and subsequent mixing of the two previously separate compartments. The actual membrane merger mechanism - fusion, by definition - is conceptualized to be protein- or lipid-centric. According to the widely vetted stalk-pore hypothesis, membrane fusion proceeds via high curvature lipid intermediates. By cleaving membrane phospholipids at the sn-2 position, Phospholipase A2 generates metabolites that exert spontaneous curvature stress (both negative and positive) on the membrane, thus influencing local membrane bending by altering the packing and conformation of lipids and proteins, respectively. Such changes could potentially modulate priming and attachment/docking steps that precede fusion, as well as the membrane merger steps per se.
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Affiliation(s)
- Deepti Dabral
- Molecular Physiology, and Molecular Medicine Research Group, School of Medicine, Western Sydney University, Campbelltown Campus, Penrith, NSW 2751, Australia
| | - Jens R Coorssen
- Faculty of Graduate Studies and the Departments of Health Sciences and Biological Sciences, Brock University,St. Catharines, ON L2S 3A1, Canada.
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40
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Kuhn P, Eyer K, Dittrich PS. A microfluidic device for the delivery of enzymes into cells by liposome fusion. Eng Life Sci 2017; 18:149-156. [PMID: 29416447 DOI: 10.1002/elsc.201600150] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Liposomes are versatile carriers of drugs or biomolecules and are ideally suited to transport molecules into cells. However, mechanistic studies to understand and improve the fusion of liposomes with cell membranes and endosomes are difficult. Here, we report a method that allows for stable coimmobilization of liposomes and living cells, thereby bringing the membranes into close contact, which is essential for membrane fusion. The small unilamellar liposomes are tethered to the surface by a linker so that no modification of the liposome membrane for cell binding is required. The cells are positioned above the liposomes by posts that are integrated into the microfluidic device, and a pH drop induces the fusion of the cell-liposome membranes. Both membrane fusion and release of molecules into the cytosol are visualized by fluorescence dequenching assays. Furthermore, we proved the efficient delivery of the enzyme β-galactosidase into the cells when a fusogenic liposome composition was used. The device could be used for fusion studies but is also a versatile means for cell transfection.
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Affiliation(s)
- Phillip Kuhn
- Department of Chemistry and Applied Biosciences, Eth Zurich, Zurich, Switzerland
| | - Klaus Eyer
- Department of Chemistry and Applied Biosciences, Eth Zurich, Zurich, Switzerland
| | - Petra S Dittrich
- Department of Chemistry and Applied Biosciences, Eth Zurich, Zurich, Switzerland.,Department of Biosystems Science and Engineering, ETH Zurich, Zurich, Switzerland
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41
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Paxman J, Hunt B, Hallan D, Zarbock SR, Woodbury DJ. Drunken Membranes: Short-Chain Alcohols Alter Fusion of Liposomes to Planar Lipid Bilayers. Biophys J 2017; 112:121-132. [PMID: 28076803 PMCID: PMC5232861 DOI: 10.1016/j.bpj.2016.11.3205] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 11/18/2016] [Accepted: 11/30/2016] [Indexed: 12/31/2022] Open
Abstract
Although the effects of ethanol on protein receptors and lipid membranes have been studied extensively, ethanol's effect on vesicles fusing to lipid bilayers is not known. To determine the effect of alcohols on fusion rates, we utilized the nystatin/ergosterol fusion assay to measure fusion of liposomes to a planar lipid bilayer (BLM). The addition of ethanol excited fusion when applied on the cis (vesicle) side, and inhibited fusion on the trans side. Other short-chain alcohols followed a similar pattern. In general, the inhibitory effect of alcohols (trans) occurs at lower doses than the excitatory (cis) effect, with a decrease of 29% in fusion rates at the legal driving limit of 0.08% (w/v) ethanol (IC50 = 0.2% v/v, 34 mM). Similar inhibitory effects were observed with methanol, propanol, and butanol, with ethanol being the most potent. Significant variability was observed with different alcohols when applied to the cis side. Ethanol and propanol enhanced fusion, butanol also enhanced fusion but was less potent, and low doses of methanol mildly inhibited fusion. The inhibition by trans addition of alcohols implies that they alter the planar membrane structure and thereby increase the activation energy required for fusion, likely through an increase in membrane fluidity. The cis data are likely a combination of the above effect and a proportionally greater lowering of the vesicle lysis tension and hydration repulsive pressure that combine to enhance fusion. Alternate hypotheses are also discussed. The inhibitory effect of ethanol on liposome-membrane fusion is large enough to provide a possible biophysical explanation of compromised neuronal behavior.
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Affiliation(s)
- Jason Paxman
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, Utah
| | - Brady Hunt
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, Utah
| | - David Hallan
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, Utah
| | - Samuel R Zarbock
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, Utah
| | - Dixon J Woodbury
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, Utah.
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42
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Oleinick A, Svir I, Amatore C. 'Full fusion' is not ineluctable during vesicular exocytosis of neurotransmitters by endocrine cells. Proc Math Phys Eng Sci 2017; 473:20160684. [PMID: 28265193 PMCID: PMC5312129 DOI: 10.1098/rspa.2016.0684] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 11/17/2016] [Indexed: 11/12/2022] Open
Abstract
Vesicular exocytosis is an essential and ubiquitous process in neurons and endocrine cells by which neurotransmitters are released in synaptic clefts or extracellular fluids. It involves the fusion of a vesicle loaded with chemical messengers with the cell membrane through a nanometric fusion pore. In endocrine cells, unless it closes after some flickering ('Kiss-and-Run' events), this initial pore is supposed to expand exponentially, leading to a full integration of the vesicle membrane into the cell membrane-a stage called 'full fusion'. We report here a compact analytical formulation that allows precise measurements of the fusion pore expansion extent and rate to be extracted from individual amperometric spike time courses. These data definitively establish that, during release of catecholamines, fusion pores enlarge at most to approximately one-fifth of the radius of their parent vesicle, hence ruling out the ineluctability of 'full fusion'.
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Affiliation(s)
| | | | - Christian Amatore
- Ecole Normale Supérieure-PSL Research University, Département de Chimie, Sorbonne Universités-UPMC Paris 06, CNRS UMR 8640 PASTEUR, 24 rue Lhomond, 75005 Paris, France
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43
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Rabe M, Aisenbrey C, Pluhackova K, de Wert V, Boyle AL, Bruggeman DF, Kirsch SA, Böckmann RA, Kros A, Raap J, Bechinger B. A Coiled-Coil Peptide Shaping Lipid Bilayers upon Fusion. Biophys J 2016; 111:2162-2175. [PMID: 27851940 PMCID: PMC5113151 DOI: 10.1016/j.bpj.2016.10.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 09/08/2016] [Accepted: 10/06/2016] [Indexed: 12/19/2022] Open
Abstract
A system based on two designed peptides, namely the cationic peptide K, (KIAALKE)3, and its complementary anionic counterpart called peptide E, (EIAALEK)3, has been used as a minimal model for membrane fusion, inspired by SNARE proteins. Although the fact that docking of separate vesicle populations via the formation of a dimeric E/K coiled-coil complex can be rationalized, the reasons for the peptides promoting fusion of vesicles cannot be fully explained. Therefore it is of significant interest to determine how the peptides aid in overcoming energetic barriers during lipid rearrangements leading to fusion. In this study, investigations of the peptides' interactions with neutral PC/PE/cholesterol membranes by fluorescence spectroscopy show that tryptophan-labeled K∗ binds to the membrane (KK∗ ∼6.2 103 M-1), whereas E∗ remains fully water-solvated. 15N-NMR spectroscopy, depth-dependent fluorescence quenching, CD-spectroscopy experiments, and MD simulations indicate a helix orientation of K∗ parallel to the membrane surface. Solid-state 31P-NMR of oriented lipid membranes was used to study the impact of peptide incorporation on lipid headgroup alignment. The membrane-immersed K∗ is found to locally alter the bilayer curvature, accompanied by a change of headgroup orientation relative to the membrane normal and of the lipid composition in the vicinity of the bound peptide. The NMR results were supported by molecular dynamics simulations, which showed that K reorganizes the membrane composition in its vicinity, induces positive membrane curvature, and enhances the lipid tail protrusion probability. These effects are known to be fusion relevant. The combined results support the hypothesis for a twofold role of K in the mechanism of membrane fusion: 1) to bring opposing membranes into close proximity via coiled-coil formation and 2) to destabilize both membranes thereby promoting fusion.
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Affiliation(s)
- Martin Rabe
- Leiden Institute of Chemistry - Supramolecular and Biomaterials Chemistry, Leiden University, Leiden, the Netherlands.
| | | | - Kristyna Pluhackova
- Computational Biology, Department of Biology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Vincent de Wert
- Leiden Institute of Chemistry - Supramolecular and Biomaterials Chemistry, Leiden University, Leiden, the Netherlands
| | - Aimee L Boyle
- Leiden Institute of Chemistry - Supramolecular and Biomaterials Chemistry, Leiden University, Leiden, the Netherlands
| | - Didjay F Bruggeman
- Leiden Institute of Chemistry - Supramolecular and Biomaterials Chemistry, Leiden University, Leiden, the Netherlands
| | - Sonja A Kirsch
- Computational Biology, Department of Biology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Rainer A Böckmann
- Computational Biology, Department of Biology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Alexander Kros
- Leiden Institute of Chemistry - Supramolecular and Biomaterials Chemistry, Leiden University, Leiden, the Netherlands
| | - Jan Raap
- Leiden Institute of Chemistry - Supramolecular and Biomaterials Chemistry, Leiden University, Leiden, the Netherlands
| | - Burkhard Bechinger
- Université de Strasbourg/CNRS UMR7177, Institut de Chimie, Strasbourg, France.
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44
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Landajuela A, Hervás JH, Antón Z, Montes LR, Gil D, Valle M, Rodriguez JF, Goñi FM, Alonso A. Lipid Geometry and Bilayer Curvature Modulate LC3/GABARAP-Mediated Model Autophagosomal Elongation. Biophys J 2016; 110:411-422. [PMID: 26789764 DOI: 10.1016/j.bpj.2015.11.3524] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 11/14/2015] [Accepted: 11/30/2015] [Indexed: 11/29/2022] Open
Abstract
Autophagy, an important catabolic pathway involved in a broad spectrum of human diseases, implies the formation of double-membrane-bound structures called autophagosomes (AP), which engulf material to be degraded in lytic compartments. How APs form, especially how the membrane expands and eventually closes upon itself, is an area of intense research. Ubiquitin-like ATG8 has been related to both membrane expansion and membrane fusion, but the underlying molecular mechanisms are poorly understood. Here, we used two minimal reconstituted systems (enzymatic and chemical conjugation) to compare the ability of human ATG8 homologs (LC3, GABARAP, and GATE-16) to mediate membrane fusion. We found that both enzymatically and chemically lipidated forms of GATE-16 and GABARAP proteins promote extensive membrane tethering and fusion, whereas lipidated LC3 does so to a much lesser extent. Moreover, we characterize the GATE-16/GABARAP-mediated membrane fusion as a phenomenon of full membrane fusion, independently demonstrating vesicle aggregation, intervesicular lipid mixing, and intervesicular mixing of aqueous content, in the absence of vesicular content leakage. Multiple fusion events give rise to large vesicles, as seen by cryo-electron microscopy observations. We also show that both vesicle diameter and selected curvature-inducing lipids (cardiolipin, diacylglycerol, and lyso-phosphatidylcholine) can modulate the fusion process, smaller vesicle diameters and negative intrinsic curvature lipids (cardiolipin, diacylglycerol) facilitating fusion. These results strongly support the hypothesis of a highly bent structural fusion intermediate (stalk) during AP biogenesis and add to the growing body of evidence that identifies lipids as important regulators of autophagy.
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Affiliation(s)
- Ane Landajuela
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain
| | - Javier H Hervás
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain
| | - Zuriñe Antón
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain
| | - L Ruth Montes
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain
| | - David Gil
- Structural Biology Unit, Center for Cooperative Research in Biosciences, CIC bioGUNE, Derio, Spain
| | - Mikel Valle
- Structural Biology Unit, Center for Cooperative Research in Biosciences, CIC bioGUNE, Derio, Spain
| | - J Francisco Rodriguez
- Departmento de Biología Molecular y Celular, Centro Nacional de Biotecnología-CSIC, Cantoblanco, Madrid, Spain
| | - Felix M Goñi
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain
| | - Alicia Alonso
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain.
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45
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Vadakkan KI. Neurodegenerative disorders share common features of "loss of function" states of a proposed mechanism of nervous system functions. Biomed Pharmacother 2016; 83:412-430. [PMID: 27424323 DOI: 10.1016/j.biopha.2016.06.042] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 06/07/2016] [Accepted: 06/25/2016] [Indexed: 12/11/2022] Open
Abstract
Neurodegenerative disorders are highly heterogeneous for the locations affected and the nature of the aggregated proteins. Nearly 80% of the neurodegenerative disorders occur sporadically, indicating that certain factors must combine to initiate the degenerative changes. The contiguous extension of degenerative changes from cell to cell, the association with viral fusion proteins, loss of dendritic spines (postsynaptic terminals), and the eventual degeneration of cells indicate the presence of a unique mechanism for inter-cellular spread of pathology. It is not known whether the "loss of function" states of the still unknown normal nervous system operations can lead to neurodegenerative disorders. Here, the possible loss of function states of a proposed normal nervous system function are examined. A reversible inter-postsynaptic functional LINK (IPL) mechanism, consisting of transient inter-postsynaptic membrane (IPM) hydration exclusion and partial to complete IPM hemifusions, was proposed as a critical step necessary for the binding process and the induction of internal sensations of higher brain functions. When various findings from different neurodegenerative disorders are systematically organized and examined, disease features match the effects of loss of function states of different IPLs. Changes in membrane composition, enlargement of dendritic spines by dopamine and viral fusion proteins are capable of altering the IPLs to form IPM fusion. The latter can lead to the observed lateral spread of pathology, inter-neuronal cytoplasmic content mixing and abnormal protein aggregation. Since both the normal mechanism of reversible IPM hydration exclusion and the pathological process of transient IPM fusion can evade detection, testing their occurrence may provide preventive and therapeutic opportunities for these disorders.
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46
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Keidel A, Bartsch TF, Florin EL. Direct observation of intermediate states in model membrane fusion. Sci Rep 2016; 6:23691. [PMID: 27029285 PMCID: PMC4814778 DOI: 10.1038/srep23691] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 03/09/2016] [Indexed: 12/28/2022] Open
Abstract
We introduce a novel assay for membrane fusion of solid supported membranes on silica beads and on coverslips. Fusion of the lipid bilayers is induced by bringing an optically trapped bead in contact with the coverslip surface while observing the bead's thermal motion with microsecond temporal and nanometer spatial resolution using a three-dimensional position detector. The probability of fusion is controlled by the membrane tension on the particle. We show that the progression of fusion can be monitored by changes in the three-dimensional position histograms of the bead and in its rate of diffusion. We were able to observe all fusion intermediates including transient fusion, formation of a stalk, hemifusion and the completion of a fusion pore. Fusion intermediates are characterized by axial but not lateral confinement of the motion of the bead and independently by the change of its rate of diffusion due to the additional drag from the stalk-like connection between the two membranes. The detailed information provided by this assay makes it ideally suited for studies of early events in pure lipid bilayer fusion or fusion assisted by fusogenic molecules.
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Affiliation(s)
- Andrea Keidel
- Center for Nonlinear Dynamics and Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA
| | - Tobias F. Bartsch
- Center for Nonlinear Dynamics and Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA
- Howard Hughes Medical Institute and Laboratory of Sensory Neuroscience, The Rockefeller University, New York, New York, 10065, USA
| | - Ernst-Ludwig Florin
- Center for Nonlinear Dynamics and Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA
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47
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Chavarha M, Loney RW, Rananavare SB, Hall SB. Hydrophobic surfactant proteins strongly induce negative curvature. Biophys J 2016; 109:95-105. [PMID: 26153706 DOI: 10.1016/j.bpj.2015.05.030] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Revised: 04/23/2015] [Accepted: 05/28/2015] [Indexed: 01/31/2023] Open
Abstract
The hydrophobic surfactant proteins SP-B and SP-C greatly accelerate the adsorption of vesicles containing the surfactant lipids to form a film that lowers the surface tension of the air/water interface in the lungs. Pulmonary surfactant enters the interface by a process analogous to the fusion of two vesicles. As with fusion, several factors affect adsorption according to how they alter the curvature of lipid leaflets, suggesting that adsorption proceeds via a rate-limiting structure with negative curvature, in which the hydrophilic face of the phospholipid leaflets is concave. In the studies reported here, we tested whether the surfactant proteins might promote adsorption by inducing lipids to adopt a more negative curvature, closer to the configuration of the hypothetical intermediate. Our experiments used x-ray diffraction to determine how the proteins in their physiological ratio affect the radius of cylindrical monolayers in the negatively curved, inverse hexagonal phase. With binary mixtures of dioleoylphosphatidylethanolamine (DOPE) and dioleoylphosphatidylcholine (DOPC), the proteins produced a dose-related effect on curvature that depended on the phospholipid composition. With DOPE alone, the proteins produced no change. With an increasing mol fraction of DOPC, the response to the proteins increased, reaching a maximum 50% reduction in cylindrical radius at 5% (w/w) protein. This change represented a doubling of curvature at the outer cylindrical surface. The change in spontaneous curvature, defined at approximately the level of the glycerol group, would be greater. Analysis of the results in terms of a Langmuir model for binding to a surface suggests that the effect of the lipids is consistent with a change in the maximum binding capacity. Our findings show that surfactant proteins can promote negative curvature, and support the possibility that they facilitate adsorption by that mechanism.
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Affiliation(s)
- Mariya Chavarha
- Department of Biochemistry & Molecular Biology, Oregon Health & Science University, Portland, Oregon; Department of Medicine, Oregon Health & Science University, Portland, Oregon; Department of Physiology & Pharmacology, Oregon Health & Science University, Portland, Oregon
| | - Ryan W Loney
- Department of Biochemistry & Molecular Biology, Oregon Health & Science University, Portland, Oregon; Department of Medicine, Oregon Health & Science University, Portland, Oregon; Department of Physiology & Pharmacology, Oregon Health & Science University, Portland, Oregon
| | | | - Stephen B Hall
- Department of Biochemistry & Molecular Biology, Oregon Health & Science University, Portland, Oregon; Department of Medicine, Oregon Health & Science University, Portland, Oregon; Department of Physiology & Pharmacology, Oregon Health & Science University, Portland, Oregon.
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48
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Liu X, Quinton D, Hu L, Amatore C, Delacotte J, Lemaître F, Guille-Collignon M. More Transparency in BioAnalysis of Exocytosis: Coupling of Electrochemistry and Fluorescence Microscopy at ITO Electrodes. BIO WEB OF CONFERENCES 2016. [DOI: 10.1051/bioconf/20160601004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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49
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Ibarguren M, Bomans PHH, Ruiz-Mirazo K, Frederik PM, Alonso A, Goñi FM. Thermally-induced aggregation and fusion of protein-free lipid vesicles. Colloids Surf B Biointerfaces 2015; 136:545-52. [PMID: 26454544 DOI: 10.1016/j.colsurfb.2015.09.047] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 08/21/2015] [Accepted: 09/24/2015] [Indexed: 12/11/2022]
Abstract
Membrane fusion is an important phenomenon in cell biology and pathology. This phenomenon can be modeled using vesicles of defined size and lipid composition. Up to now fusion models typically required the use of chemical (polyethyleneglycol, cations) or enzymatic catalysts (phospholipases). We present here a model of lipid vesicle fusion induced by heat. Large unilamellar vesicles consisting of a phospholipid (dioleoylphosphatidylcholine), cholesterol and diacylglycerol in a 43:57:3 mol ratio were employed. In this simple system, fusion was the result of thermal fluctuations, above 60 °C. A similar system containing phospholipid and cholesterol but no diacylglycerol was observed to aggregate at and above 60 °C, in the absence of fusion. Vesicle fusion occurred under our experimental conditions only when (31)P NMR and cryo-transmission electron microscopy of the lipid mixtures used in vesicle preparation showed non-lamellar lipid phase formation (hexagonal and cubic). Non-lamellar structures are probably the result of lipid reassembly of the products of individual fusion events, or of fusion intermediates. A temperature-triggered mechanism of lipid reassembly might have occurred at various stages of protocellular evolution.
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Affiliation(s)
- Maitane Ibarguren
- Unidad de Biofísica (Centro Mixto CSIC, UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, Apto. 644, 48080 Bilbao, Spain.
| | - Paul H H Bomans
- Soft Matter CryoTEM Research Unit, Laboratory for Materials and Interface Chemistry, P.O. Box 513, 5600MB Eindhoven, The Netherlands.
| | - Kepa Ruiz-Mirazo
- Unidad de Biofísica (Centro Mixto CSIC, UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, Apto. 644, 48080 Bilbao, Spain; Logic and Philosophy of Science Department, University of the Basque Country, Spain.
| | - Peter M Frederik
- Soft Matter CryoTEM Research Unit, Laboratory for Materials and Interface Chemistry, P.O. Box 513, 5600MB Eindhoven, The Netherlands.
| | - Alicia Alonso
- Unidad de Biofísica (Centro Mixto CSIC, UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, Apto. 644, 48080 Bilbao, Spain.
| | - Félix M Goñi
- Unidad de Biofísica (Centro Mixto CSIC, UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, Apto. 644, 48080 Bilbao, Spain.
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50
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Lete MG, Sot J, Gil D, Valle M, Medina M, Goñi FM, Alonso A. Histones cause aggregation and fusion of lipid vesicles containing phosphatidylinositol-4-phosphate. Biophys J 2015; 108:863-871. [PMID: 25692591 DOI: 10.1016/j.bpj.2014.12.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 12/07/2014] [Accepted: 12/09/2014] [Indexed: 12/13/2022] Open
Abstract
In a previous article, we demonstrated that histones (H1 or histone octamers) interact with negatively charged bilayers and induce extensive aggregation of vesicles containing phosphatidylinositol-4-phosphate (PIP) and, to a lesser extent, vesicles containing phosphatidylinositol (PI). Here, we found that vesicles containing PIP, but not those containing PI, can undergo fusion induced by histones. Fusion was demonstrated through the observation of intervesicular mixing of total lipids and inner monolayer lipids, and by ultrastructural and confocal microscopy studies. Moreover, in both PI- and PIP-containing vesicles, histones caused permeabilization and release of vesicular aqueous contents, but the leakage mechanism was different (all-or-none for PI and graded release for PIP vesicles). These results indicate that histones could play a role in the remodeling of the nuclear envelope that takes place during the mitotic cycle.
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Affiliation(s)
- Marta G Lete
- Unidad de Biofísica (CSIC, UPV/EHU), Universidad del País Vasco, Leioa, Spain; Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain
| | - Jesus Sot
- Unidad de Biofísica (CSIC, UPV/EHU), Universidad del País Vasco, Leioa, Spain; Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain
| | - David Gil
- Structural Biology Unit, Center for Cooperative Research in Biosciences, CIC bioGUNE, Derio, Spain
| | - Mikel Valle
- Structural Biology Unit, Center for Cooperative Research in Biosciences, CIC bioGUNE, Derio, Spain
| | - Milagros Medina
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, Zaragoza, Spain; Instituto de Biocomputación y Física de Sistemas Complejos, Unidad Asociada BIFI-IQFR, Universidad de Zaragoza, Zaragoza, Spain
| | - Felix M Goñi
- Unidad de Biofísica (CSIC, UPV/EHU), Universidad del País Vasco, Leioa, Spain; Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain
| | - Alicia Alonso
- Unidad de Biofísica (CSIC, UPV/EHU), Universidad del País Vasco, Leioa, Spain; Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain.
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