1
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Kappelhoff S, Margheritis EG, Cosentino K. New insights into Gasdermin D pore formation. Biochem Soc Trans 2024; 52:681-692. [PMID: 38497302 DOI: 10.1042/bst20230549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 03/01/2024] [Accepted: 03/04/2024] [Indexed: 03/19/2024]
Abstract
Gasdermin D (GSDMD) is a pore-forming protein that perforates the plasma membrane (PM) during pyroptosis, a pro-inflammatory form of cell death, to induce the unconventional secretion of inflammatory cytokines and, ultimately, cell lysis. GSDMD is activated by protease-mediated cleavage of its active N-terminal domain from the autoinhibitory C-terminal domain. Inflammatory caspase-1, -4/5 are the main activators of GSDMD via either the canonical or non-canonical pathways of inflammasome activation, but under certain stimuli, caspase-8 and other proteases can also activate GSDMD. Activated GSDMD can oligomerize and assemble into various nanostructures of different sizes and shapes that perforate cellular membranes, suggesting plasticity in pore formation. Although the exact mechanism of pore formation has not yet been deciphered, cysteine residues are emerging as crucial modulators of the oligomerization process. GSDMD pores and thus the outcome of pyroptosis can be modulated by various regulatory mechanisms. These include availability of activated GSDMD at the PM, control of the number of GSDMD pores by PM repair mechanisms, modulation of the lipid environment and post-translational modifications. Here, we review the latest findings on the mechanisms that induce GSDMD to form membrane pores and how they can be tightly regulated for cell content release and cell fate modulation.
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Affiliation(s)
- Shirin Kappelhoff
- Department of Biology/Chemistry and Center for Cellular Nanoanalytics (CellNanOs), University of Osnabrück, Osnabrück, Germany
| | - Eleonora G Margheritis
- Department of Biology/Chemistry and Center for Cellular Nanoanalytics (CellNanOs), University of Osnabrück, Osnabrück, Germany
| | - Katia Cosentino
- Department of Biology/Chemistry and Center for Cellular Nanoanalytics (CellNanOs), University of Osnabrück, Osnabrück, Germany
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2
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Danial JSH, Jenner A, Garcia-Saez AJ, Cosentino K. Real-Time Growth Kinetics Analysis of Macromolecular Assemblies in Cells with Single Molecule Resolution. J Phys Chem A 2023; 127:3490-3496. [PMID: 37023388 DOI: 10.1021/acs.jpca.3c00368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
Abstract
Single molecule fluorescence microscopy has the unique advantage to provide real-time information on the spatiotemporal assembly of individual protein complexes in cellular membranes. This includes the assembly of proteins into oligomer species of numerous copy numbers. However, there is a need for improved tracing analysis of the real-time growth kinetics of these assemblies in cells with single molecule resolution. Here, we present an automated analysis software to accurately measure the real-time kinetics of assembly of individual high-order oligomer complexes. Our software comes with a simple Graphical User Interface (GUI), is available as a source code and an executable, and can analyze a full data set of several hundred to thousand molecules in less than 2 minutes. Importantly, this software is suitable for the analysis of intracellular protein oligomers, whose stoichiometry is usually more difficult to quantify due to variability in signal detection in the different areas of the cell. We validated our method with simulated ground-truth data and time-lapse images of diffraction-limited oligomeric assemblies of BAX and BAK proteins on mitochondria of cells undergoing apoptosis. Our approach provides the broad community of biologists with a fast, user-friendly tool to trace the compositional evolution of macromolecular assemblies, and potentially model their growth for a deeper understanding of the structural and biophysical mechanisms underlying their functions.
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Affiliation(s)
- John S H Danial
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom
- UK Dementia Research Institute, University of Cambridge, Cambridge CB2 1TN, United Kingdom
| | - Andreas Jenner
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), 50931 Cologne, Germany
| | - Ana J Garcia-Saez
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), 50931 Cologne, Germany
| | - Katia Cosentino
- Department of Biology/Chemistry and Center of Cellular Nanoanalytics (CellNanOs), University of Osnabrück, 49076 Osnabrück, Germany
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3
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Galic M, Ungermann C, Cosentino K. Highlight: on the past and the future of cellular microcompartments. Biol Chem 2023; 404:377-378. [PMID: 36951639 DOI: 10.1515/hsz-2023-0153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/24/2023]
Affiliation(s)
- Milos Galic
- Institute of Medical Physics and Biophysics and 'Cells in Motion' Interfaculty Centre, University of Münster, D-48149 Münster, Germany
| | - Christian Ungermann
- Department of Biology/Chemistry and Center for Cellular Nanoanalytics (CellNanOs), University of Osnabrück, D-49076 Osnabrück, Germany
| | - Katia Cosentino
- Department of Biology/Chemistry and Center for Cellular Nanoanalytics (CellNanOs), University of Osnabrück, D-49076 Osnabrück, Germany
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4
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Margheritis E, Kappelhoff S, Cosentino K. Pore-Forming Proteins: From Pore Assembly to Structure by Quantitative Single-Molecule Imaging. Int J Mol Sci 2023; 24:ijms24054528. [PMID: 36901959 PMCID: PMC10003378 DOI: 10.3390/ijms24054528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 02/11/2023] [Accepted: 02/21/2023] [Indexed: 03/03/2023] Open
Abstract
Pore-forming proteins (PFPs) play a central role in many biological processes related to infection, immunity, cancer, and neurodegeneration. A common feature of PFPs is their ability to form pores that disrupt the membrane permeability barrier and ion homeostasis and generally induce cell death. Some PFPs are part of the genetically encoded machinery of eukaryotic cells that are activated against infection by pathogens or in physiological programs to carry out regulated cell death. PFPs organize into supramolecular transmembrane complexes that perforate membranes through a multistep process involving membrane insertion, protein oligomerization, and finally pore formation. However, the exact mechanism of pore formation varies from PFP to PFP, resulting in different pore structures with different functionalities. Here, we review recent insights into the molecular mechanisms by which PFPs permeabilize membranes and recent methodological advances in their characterization in artificial and cellular membranes. In particular, we focus on single-molecule imaging techniques as powerful tools to unravel the molecular mechanistic details of pore assembly that are often obscured by ensemble measurements, and to determine pore structure and functionality. Uncovering the mechanistic elements of pore formation is critical for understanding the physiological role of PFPs and developing therapeutic approaches.
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5
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Barisch C, Holthuis JCM, Cosentino K. Membrane damage and repair: a thin line between life and death. Biol Chem 2023; 404:467-490. [PMID: 36810295 DOI: 10.1515/hsz-2022-0321] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 02/03/2023] [Indexed: 02/24/2023]
Abstract
Bilayered membranes separate cells from their surroundings and form boundaries between intracellular organelles and the cytosol. Gated transport of solutes across membranes enables cells to establish vital ion gradients and a sophisticated metabolic network. However, an advanced compartmentalization of biochemical reactions makes cells also particularly vulnerable to membrane damage inflicted by pathogens, chemicals, inflammatory responses or mechanical stress. To avoid potentially lethal consequences of membrane injuries, cells continuously monitor the structural integrity of their membranes and readily activate appropriate pathways to plug, patch, engulf or shed the damaged membrane area. Here, we review recent insights into the cellular mechanisms that underly an effective maintenance of membrane integrity. We discuss how cells respond to membrane lesions caused by bacterial toxins and endogenous pore-forming proteins, with a primary focus on the intimate crosstalk between membrane proteins and lipids during wound formation, detection and elimination. We also discuss how a delicate balance between membrane damage and repair determines cell fate upon bacterial infection or activation of pro-inflammatory cell death pathways.
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Affiliation(s)
- Caroline Barisch
- Molecular Infection Biology Division, Department of Biology and Center of Cellular Nanoanalytics, Osnabrück University, D-49076 Osnabrück, Germany
| | - Joost C M Holthuis
- Molecular Cell Biology Division, Department of Biology and Center of Cellular Nanoanalytics, Osnabrück University, D-49076 Osnabrück, Germany
| | - Katia Cosentino
- Molecular Cell Biophysics Division, Department of Biology and Center of Cellular Nanoanalytics, Osnabrück University, D-49076 Osnabrück, Germany
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6
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Chumpen Ramirez S, Gómez-Sánchez R, Verlhac P, Hardenberg R, Margheritis E, Cosentino K, Reggiori F, Ungermann C. --Atg9 interactions via its transmembrane domains are required for phagophore expansion during autophagy. Autophagy 2022:1-20. [PMID: 36354155 DOI: 10.1080/15548627.2022.2136340] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
During macroautophagy/autophagy, precursor cisterna known as phagophores expand and sequester portions of the cytoplasm and/or organelles, and subsequently close resulting in double-membrane transport vesicles called autophagosomes. Autophagosomes fuse with lysosomes/vacuoles to allow the degradation and recycling of their cargoes. We previously showed that sequential binding of yeast Atg2 and Atg18 to Atg9, the only conserved transmembrane protein in autophagy, at the extremities of the phagophore mediates the establishment of membrane contact sites between the phagophore and the endoplasmic reticulum. As the Atg2-Atg18 complex transfers lipids between adjacent membranes in vitro, it has been postulated that this activity and the scramblase activity of the trimers formed by Atg9 are required for the phagophore expansion. Here, we present evidence that Atg9 indeed promotes Atg2-Atg18 complex-mediated lipid transfer in vitro, although this is not the only requirement for its function in vivo. In particular, we show that Atg9 function is dramatically compromised by a F627A mutation within the conserved interface between the transmembrane domains of the Atg9 monomers. Although Atg9F627A self-interacts and binds to the Atg2-Atg18 complex, the F627A mutation blocks the phagophore expansion and thus autophagy progression. This phenotype is conserved because the corresponding human ATG9A mutant severely impairs autophagy as well. Importantly, Atg9F627A has identical scramblase activity in vitro like Atg9, and as with the wild-type protein enhances Atg2-Atg18-mediated lipid transfer. Collectively, our data reveal that interactions of Atg9 trimers via their transmembrane segments play a key role in phagophore expansion beyond Atg9's role as a lipid scramblase.Abbreviations: BafA1: bafilomycin A1; Cvt: cytoplasm-to-vacuole targeting; Cryo-EM: cryo-electron microscopy; ER: endoplasmic reticulum; GFP: green fluorescent protein; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MCS: membrane contact site; NBD-PE: N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine; PAS: phagophore assembly site; PE: phosphatidylethanolamine; prApe1: precursor Ape1; PtdIns3P: phosphatidylinositol-3-phosphate; SLB: supported lipid bilayer; SUV: small unilamellar vesicle; TMD: transmembrane domain; WT: wild type.
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Affiliation(s)
- Sabrina Chumpen Ramirez
- Osnabrück University, Department of Biology/Chemistry, Biochemistry section, Osnabrück, Germany
| | - Rubén Gómez-Sánchez
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Pauline Verlhac
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Ralph Hardenberg
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | | | - Katia Cosentino
- Osnabrück University, Department of Biology/Chemistry, Osnabrück, Germany.,Center of Cellular Nanoanalytic Osnabrück (CellNanOs), Osnabrück University, Osnabrück, Germany
| | - Fulvio Reggiori
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Department of Biomedicine, Aarhus University, Ole Worms Alle 4, 8000 Aarhus C, Aarhus, Denmark.,Aarhus Institute of Advanced Studies (AIAS), Aarhus University, Aarhus C, Denmark
| | - Christian Ungermann
- Osnabrück University, Department of Biology/Chemistry, Biochemistry section, Osnabrück, Germany.,Center of Cellular Nanoanalytic Osnabrück (CellNanOs), Osnabrück University, Osnabrück, Germany
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7
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Cosentino K, Hertlein V, Jenner A, Dellmann T, Gojkovic M, Peña-Blanco A, Dadsena S, Wajngarten N, Danial JSH, Thevathasan JV, Mund M, Ries J, Garcia-Saez AJ. The interplay between BAX and BAK tunes apoptotic pore growth to control mitochondrial-DNA-mediated inflammation. Mol Cell 2022; 82:933-949.e9. [PMID: 35120587 PMCID: PMC8901441 DOI: 10.1016/j.molcel.2022.01.008] [Citation(s) in RCA: 70] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 11/14/2021] [Accepted: 01/10/2022] [Indexed: 01/11/2023]
Abstract
BAX and BAK are key apoptosis regulators that mediate the decisive step of mitochondrial outer membrane permeabilization. However, the mechanism by which they assemble the apoptotic pore remains obscure. Here, we report that BAX and BAK present distinct oligomerization properties, with BAK organizing into smaller structures with faster kinetics than BAX. BAK recruits and accelerates BAX assembly into oligomers that continue to grow during apoptosis. As a result, BAX and BAK regulate each other as they co-assemble into the same apoptotic pores, which we visualize. The relative availability of BAX and BAK molecules thereby determines the growth rate of the apoptotic pore and the relative kinetics by which mitochondrial contents, most notably mtDNA, are released. This feature of BAX and BAK results in distinct activation kinetics of the cGAS/STING pathway with implications for mtDNA-mediated paracrine inflammatory signaling.
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Affiliation(s)
- Katia Cosentino
- Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany; Department of Biology/Chemistry and Center for Cellular Nanoanalytics (CellNanOs), University of Osnabrück, 49076 Osnabrück, Germany
| | - Vanessa Hertlein
- Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Andreas Jenner
- Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany; Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany
| | - Timo Dellmann
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany
| | - Milos Gojkovic
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany
| | - Aida Peña-Blanco
- Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Shashank Dadsena
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany
| | - Noel Wajngarten
- Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany
| | - John S H Danial
- Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Jervis Vermal Thevathasan
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Markus Mund
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Jonas Ries
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Ana J Garcia-Saez
- Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany; Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany.
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8
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Danial JSH, Quintana Y, Ros U, Shalaby R, Margheritis EG, Chumpen Ramirez S, Ungermann C, Garcia-Saez AJ, Cosentino K. Systematic Assessment of the Accuracy of Subunit Counting in Biomolecular Complexes Using Automated Single-Molecule Brightness Analysis. J Phys Chem Lett 2022; 13:822-829. [PMID: 35044771 PMCID: PMC8802318 DOI: 10.1021/acs.jpclett.1c03835] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 12/10/2021] [Indexed: 06/14/2023]
Abstract
Analysis of single-molecule brightness allows subunit counting of high-order oligomeric biomolecular complexes. Although the theory behind the method has been extensively assessed, systematic analysis of the experimental conditions required to accurately quantify the stoichiometry of biological complexes remains challenging. In this work, we develop a high-throughput, automated computational pipeline for single-molecule brightness analysis that requires minimal human input. We use this strategy to systematically quantify the accuracy of counting under a wide range of experimental conditions in simulated ground-truth data and then validate its use on experimentally obtained data. Our approach defines a set of conditions under which subunit counting by brightness analysis is designed to work optimally and helps in establishing the experimental limits in quantifying the number of subunits in a complex of interest. Finally, we combine these features into a powerful, yet simple, software that can be easily used for the analysis of the stoichiometry of such complexes.
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Affiliation(s)
- John S. H. Danial
- Interfaculty
Institute of Biochemistry, University of
Tübingen, Tübingen 72076, Germany
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Cambridge CB2 1EW, United Kingdom
- UK Dementia
Research Institute, University of Cambridge, Cambridge CB2 1EW, United Kingdom
| | - Yuri Quintana
- Interfaculty
Institute of Biochemistry, University of
Tübingen, Tübingen 72076, Germany
| | - Uris Ros
- Interfaculty
Institute of Biochemistry, University of
Tübingen, Tübingen 72076, Germany
- Institute
for Genetics and Cologne Excellence Cluster on Cellular Stress Responses
in Aging-Associated Diseases (CECAD), Cologne 50931, Germany
| | - Raed Shalaby
- Interfaculty
Institute of Biochemistry, University of
Tübingen, Tübingen 72076, Germany
- Institute
for Genetics and Cologne Excellence Cluster on Cellular Stress Responses
in Aging-Associated Diseases (CECAD), Cologne 50931, Germany
| | - Eleonora G. Margheritis
- Department
of Biology/Chemistry and Center for Cellular Nanoanalytics (CellNanOs), University of Osnabrück, Osnabrück 49076, Germany
| | - Sabrina Chumpen Ramirez
- Department
of Biology/Chemistry and Center for Cellular Nanoanalytics (CellNanOs), University of Osnabrück, Osnabrück 49076, Germany
| | - Christian Ungermann
- Department
of Biology/Chemistry and Center for Cellular Nanoanalytics (CellNanOs), University of Osnabrück, Osnabrück 49076, Germany
| | - Ana J. Garcia-Saez
- Interfaculty
Institute of Biochemistry, University of
Tübingen, Tübingen 72076, Germany
- Institute
for Genetics and Cologne Excellence Cluster on Cellular Stress Responses
in Aging-Associated Diseases (CECAD), Cologne 50931, Germany
| | - Katia Cosentino
- Interfaculty
Institute of Biochemistry, University of
Tübingen, Tübingen 72076, Germany
- Department
of Biology/Chemistry and Center for Cellular Nanoanalytics (CellNanOs), University of Osnabrück, Osnabrück 49076, Germany
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Cosentino K, Hermann E, von Kügelgen N, Unsay JD, Ros U, García-Sáez AJ. Force Mapping Study of Actinoporin Effect in Membranes Presenting Phase Domains. Toxins (Basel) 2021; 13:toxins13090669. [PMID: 34564674 PMCID: PMC8473010 DOI: 10.3390/toxins13090669] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 09/08/2021] [Accepted: 09/14/2021] [Indexed: 11/16/2022] Open
Abstract
Equinatoxin II (EqtII) and Fragaceatoxin C (FraC) are pore-forming toxins (PFTs) from the actinoporin family that have enhanced membrane affinity in the presence of sphingomyelin (SM) and phase coexistence in the membrane. However, little is known about the effect of these proteins on the nanoscopic properties of membrane domains. Here, we used combined confocal microscopy and force mapping by atomic force microscopy to study the effect of EqtII and FraC on the organization of phase-separated phosphatidylcholine/SM/cholesterol membranes. To this aim, we developed a fast, high-throughput processing tool to correlate structural and nano-mechanical information from force mapping. We found that both proteins changed the lipid domain shape. Strikingly, they induced a reduction in the domain area and circularity, suggesting a decrease in the line tension due to a lipid phase height mismatch, which correlated with proteins binding to the domain interfaces. Moreover, force mapping suggested that the proteins affected the mechanical properties at the edge, but not in the bulk, of the domains. This effect could not be revealed by ensemble force spectroscopy measurements supporting the suitability of force mapping to study local membrane topographical and mechanical alterations by membranotropic proteins.
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Danial JSH, Shalaby R, Cosentino K, Mahmoud MM, Medhat F, Klenerman D, Garcia Saez AJ. DeepSinse: deep learning based detection of single molecules. Bioinformatics 2021; 37:3998-4000. [PMID: 33964131 DOI: 10.1093/bioinformatics/btab352] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 04/14/2021] [Accepted: 05/06/2021] [Indexed: 11/14/2022] Open
Abstract
MOTIVATION Imaging single molecules has emerged as a powerful characterization tool in the biological sciences. The detection of these under various noise conditions requires the use of algorithms that are dependent on the end-user inputting several parameters, the choice of which can be challenging and subjective. RESULTS In this work, we propose DeepSinse, an easily-trainable and useable deep neural network that can detect single molecules with little human input and across a wide range of signal-to-noise ratios. We validate the neural network on the detection of single bursts in simulated and experimental data and compare its performance with the best-in-class, domain-specific algorithms. AVAILABILITY Ground truth ROI simulating code, neural network training, validation code, classification code, ROI picker, GUI for simulating, training and validating DeepSinse as well as pre-trained networks are all released under the MIT License on www.github.com/jdanial/DeepSinse.The dSTORM dataset processing code is released under the MIT License on www.github.com/jdanial/StormProcessor. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- John S H Danial
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom.,UK Dementia Research Institute, University of Cambridge, Cambridge, United Kingdom
| | - Raed Shalaby
- Institute of Genetics, University of Cologne, Cologne, Germany
| | - Katia Cosentino
- Department of Biology, University of Osnabruck, Osnabruck, Germany
| | - Marwa M Mahmoud
- Department of Computer Science, University of Cambridge, Cambridge, United Kingdom
| | - Fady Medhat
- Department of Computer Science, University of York, York, United Kingdom
| | - David Klenerman
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom.,UK Dementia Research Institute, University of Cambridge, Cambridge, United Kingdom
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Voskoboynikova N, Margheritis EG, Kodde F, Rademacher M, Schowe M, Budke-Gieseking A, Psathaki OE, Steinhoff HJ, Cosentino K. Evaluation of DIBMA nanoparticles of variable size and anionic lipid content as tools for the structural and functional study of membrane proteins. Biochim Biophys Acta Biomembr 2021; 1863:183588. [PMID: 33662362 DOI: 10.1016/j.bbamem.2021.183588] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 02/15/2021] [Accepted: 02/17/2021] [Indexed: 12/16/2022]
Abstract
Amphiphilic maleic acid-containing polymers allow for the direct extraction of membrane proteins into stable, homogenous, water-soluble copolymer/lipid nanoparticles without the use of detergents. By adjusting the polymer/lipid ratio, the size of the nanoparticles can be tuned at convenience for the incorporation of protein complexes of different size. However, an increase in the size of the lipid nanoparticles may correlate with increased sample heterogeneity, thus hampering their application to spectroscopic and structural techniques where highly homogeneous samples are desirable. In addition, size homogeneity can be affected by low liposome solubilization efficiency by DIBMA, which carries a negative charge, in the presence of high lipid charge density. In this work, we apply biophysical tools to characterize the size and size heterogeneity of large (above 15 nm) lipid nanoparticles encased by the diisobutylene/maleic acid (DIBMA) copolymer at different DIBMA/lipid ratios and percentages of anionic lipids. Importantly, for nanoparticle preparations in the diameter range of 40 nm or below, the size homogeneity of the DIBMA/lipid nanoparticles (DIBMALPs) remains unchanged. In addition, we show that anionic lipids do not affect the production, size and size homogeneity of DIBMALPs. Furthermore, they do not affect the overall lipid dynamics in the membrane, and preserve the functionality of an enclosed membrane protein. This work strengthens the suitability of DIBMALPs as universal, native-like lipid environments for functional studies of membrane proteins and provide useful insight on the suitability of these systems for those structural techniques requiring highly homogeneous sample preparations.
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Affiliation(s)
| | | | - Felix Kodde
- Department of Physics, University of Osnabrück, 49069 Osnabrück, Germany
| | - Malte Rademacher
- Department of Physics, University of Osnabrück, 49069 Osnabrück, Germany
| | - Maurice Schowe
- Department of Physics, University of Osnabrück, 49069 Osnabrück, Germany
| | - Annette Budke-Gieseking
- Department of Biology and Center for Cellular Nanoanalytics (CellNanOs), University of Osnabrück, Germany
| | - Olympia-Ekaterini Psathaki
- Department of Biology and Center for Cellular Nanoanalytics (CellNanOs), University of Osnabrück, Germany
| | | | - Katia Cosentino
- Department of Biology and Center for Cellular Nanoanalytics (CellNanOs), University of Osnabrück, Germany.
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12
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Kuwana T, King LE, Cosentino K, Suess J, Garcia-Saez AJ, Gilmore AP, Newmeyer DD. Mitochondrial residence of the apoptosis inducer BAX is more important than BAX oligomerization in promoting membrane permeabilization. J Biol Chem 2020; 295:1623-1636. [PMID: 31901077 PMCID: PMC7008371 DOI: 10.1074/jbc.ra119.011635] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 12/27/2019] [Indexed: 12/31/2022] Open
Abstract
Permeabilization of the mitochondrial outer membrane is a key step in the intrinsic apoptosis pathway, triggered by the release of mitochondrial intermembrane space proteins into the cytoplasm. The BCL-2-associated X apoptosis regulator (BAX) protein critically contributes to this process by forming pores in the mitochondrial outer membrane. However, the relative roles of the mitochondrial residence of BAX and its oligomerization in promoting membrane permeabilization are unclear. To this end, using both cell-free and cellular experimental systems, including membrane permeabilization, size-exclusion chromatography-based oligomer, and retrotranslocation assays, along with confocal microscopy analysis, here we studied two BAX C-terminal variants, T182I and G179P. Neither variant formed large oligomers when activated in liposomes. Nevertheless, the G179P variant could permeabilize liposome membranes, suggesting that large BAX oligomers are not essential for the permeabilization. However, when G179P was transduced into BAX/BCL2 agonist killer (BAK) double-knockout mouse embryonic fibroblasts, its location was solely cytoplasmic, and it then failed to mediate cell death. In contrast, T182I was inefficient in both liposome insertion and permeabilization. Yet, when transduced into cells, BAXT182I resided predominantly on mitochondria, because of its slow retrotranslocation and mediated apoptosis as efficiently as WT BAX. We conclude that BAX's mitochondrial residence in vivo, regulated by both targeting and retrotranslocation, is more significant for its pro-apoptotic activity than its ability to insert and to form higher-order oligomers in model membranes. We propose that this finding should be taken into account when developing drugs that modulate BAX activity.
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Affiliation(s)
- Tomomi Kuwana
- La Jolla Institute for Immunology, La Jolla, California 92037.
| | - Louise E King
- Wellcome Trust Centre for Cell/Matrix Research, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom M13 9PT
| | - Katia Cosentino
- Interfaculty Institute of Biochemistry, University of Tubingen, 72076 Tubingen, Germany
| | | | | | - Andrew P Gilmore
- Wellcome Trust Centre for Cell/Matrix Research, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom M13 9PT
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13
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Flores-Romero H, Landeta O, Ugarte-Uribe B, Cosentino K, García-Porras M, García-Sáez AJ, Basañez G. BFL1 modulates apoptosis at the membrane level through a bifunctional and multimodal mechanism showing key differences with BCLXL. Cell Death Differ 2018; 26:1880-1894. [PMID: 30560933 PMCID: PMC6748131 DOI: 10.1038/s41418-018-0258-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 11/13/2018] [Accepted: 11/27/2018] [Indexed: 12/17/2022] Open
Abstract
BFL1 is a relatively understudied member of the BCL2 protein family which has been implicated in the pathogenesis and chemoresistance of a variety of human cancers, including hematological malignancies and solid tumours. BFL1 is generally considered to have an antiapoptotic function, although its precise mode of action remains unclear. By quantitatively analyzing BFL1 action in synthetic membrane models and in cells, we found that BFL1 inhibits apoptosis through three distinct mechanisms which are similar but not identical to those of BCLXL, the paradigmatic antiapoptotic BCL2 family protein. Strikingly, alterations in lipid composition during apoptosis activate a prodeath function of BFL1 that is based on noncanonical oligomerization of the protein and breaching of the permeability barrier of the outer mitochondrial membrane (OMM). This lipid-triggered prodeath function of BFL1 is absent in BCLXL and also differs from that of the apoptotic effector BAX, which sets it apart from other BCL2 family members. Our findings support a new model in which BFL1 modulates apoptosis through a bifunctional and multimodal mode of action that is distinctly regulated by OMM lipids compared to BCLXL.
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Affiliation(s)
- Hector Flores-Romero
- Instituto Biofisika (CSIC, UPV/EHU), Parque Científico de la UPV/EHU, Barrio Sarriena s/n, Leioa, 48940, Bizkaia, Spain. .,Interfaculty Institute of Biochemistry, Eberhard Karls University Tübingen, Hoppe-Seyler-Str. 4, Tübingen, 72076, Germany.
| | - Olatz Landeta
- Instituto Biofisika (CSIC, UPV/EHU), Parque Científico de la UPV/EHU, Barrio Sarriena s/n, Leioa, 48940, Bizkaia, Spain.,Departmento de Bioquímica y Biología Molecular, Universidad del País Vasco (UPV/EHU), Barrio Sarriena s/n, Leioa, 48940, Bizkaia, Spain
| | - Begoña Ugarte-Uribe
- Interfaculty Institute of Biochemistry, Eberhard Karls University Tübingen, Hoppe-Seyler-Str. 4, Tübingen, 72076, Germany.,Departmento de Bioquímica y Biología Molecular, Universidad del País Vasco (UPV/EHU), Barrio Sarriena s/n, Leioa, 48940, Bizkaia, Spain
| | - Katia Cosentino
- Interfaculty Institute of Biochemistry, Eberhard Karls University Tübingen, Hoppe-Seyler-Str. 4, Tübingen, 72076, Germany
| | - Miguel García-Porras
- Instituto Biofisika (CSIC, UPV/EHU), Parque Científico de la UPV/EHU, Barrio Sarriena s/n, Leioa, 48940, Bizkaia, Spain
| | - Ana J García-Sáez
- Interfaculty Institute of Biochemistry, Eberhard Karls University Tübingen, Hoppe-Seyler-Str. 4, Tübingen, 72076, Germany
| | - Gorka Basañez
- Instituto Biofisika (CSIC, UPV/EHU), Parque Científico de la UPV/EHU, Barrio Sarriena s/n, Leioa, 48940, Bizkaia, Spain.
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14
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Dimou E, Cosentino K, Platonova E, Ros U, Sadeghi M, Kashyap P, Katsinelos T, Wegehingel S, Noé F, García-Sáez AJ, Ewers H, Nickel W. Single event visualization of unconventional secretion of FGF2. J Cell Biol 2018; 218:683-699. [PMID: 30470711 PMCID: PMC6363455 DOI: 10.1083/jcb.201802008] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 07/07/2018] [Accepted: 11/08/2018] [Indexed: 12/29/2022] Open
Abstract
FGF2 is a cell survival factor secreted by unconventional means. Dimou et al. visualize individual FGF2 translocation events at the plasma membrane by live cell TIRF microscopy, providing insight into the kinetics and the mechanism of this process. FGF2 is exported from cells by an unconventional secretory mechanism. Here, we directly visualized individual FGF2 membrane translocation events at the plasma membrane using live cell TIRF microscopy. This process was dependent on both PI(4,5)P2–mediated recruitment of FGF2 at the inner leaflet and heparan sulfates capturing FGF2 at the outer plasma membrane leaflet. By simultaneous imaging of both FGF2 membrane recruitment and the appearance of FGF2 at the cell surface, we revealed the kinetics of FGF2 membrane translocation in living cells with an average duration of ∼200 ms. Furthermore, we directly demonstrated FGF2 oligomers at the inner leaflet of living cells with a FGF2 dimer being the most prominent species. We propose this dimer to represent a key intermediate in the formation of higher FGF2 oligomers that form membrane pores and put forward a kinetic model explaining the mechanism by which membrane-inserted FGF2 oligomers serve as dynamic translocation intermediates during unconventional secretion of FGF2.
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Affiliation(s)
- Eleni Dimou
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - Katia Cosentino
- Interfaculty Institute of Biochemistry, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Evgenia Platonova
- Randall Division of Cell and Molecular Biophysics, King's College London, London, UK
| | - Uris Ros
- Interfaculty Institute of Biochemistry, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Mohsen Sadeghi
- Department of Mathematics and Computer Science, Free University Berlin, Berlin, Germany
| | - Purba Kashyap
- Institute for Chemistry and Biochemistry, Free University Berlin, Berlin, Germany
| | | | | | - Frank Noé
- Department of Mathematics and Computer Science, Free University Berlin, Berlin, Germany
| | - Ana J García-Sáez
- Interfaculty Institute of Biochemistry, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Helge Ewers
- Randall Division of Cell and Molecular Biophysics, King's College London, London, UK .,Institute for Chemistry and Biochemistry, Free University Berlin, Berlin, Germany
| | - Walter Nickel
- Heidelberg University Biochemistry Center, Heidelberg, Germany
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15
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Affiliation(s)
- Katia Cosentino
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Ana J García-Sáez
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
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16
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Fasanella A, Cosentino K, Beneduci A, Chidichimo G, Cazzanelli E, Barberi R, Castriota M. Thermal structural evolutions of DMPC-water biomimetic systems investigated by Raman Spectroscopy. Biochimica et Biophysica Acta (BBA) - Biomembranes 2018; 1860:1253-1258. [DOI: 10.1016/j.bbamem.2018.02.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 02/20/2018] [Accepted: 02/22/2018] [Indexed: 11/28/2022]
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17
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Cosentino K, García-Sáez AJ. Bax and Bak Pores: Are We Closing the Circle? Trends Cell Biol 2016; 27:266-275. [PMID: 27932064 DOI: 10.1016/j.tcb.2016.11.004] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 10/28/2016] [Accepted: 11/07/2016] [Indexed: 01/19/2023]
Abstract
Bax and its homolog Bak are key regulators of the mitochondrial pathway of apoptosis. On cell stress Bax and Bak accumulate at distinct foci on the mitochondrial surface where they undergo a conformational change, oligomerize, and mediate cytochrome c release, leading to cell death. The molecular mechanisms of Bax and Bak assembly and mitochondrial permeabilization have remained a longstanding question in the field. Recent structural and biophysical studies at several length scales have shed light on key aspects of Bax and Bak function that have shifted how we think this process occurs. These discoveries reveal an unexpected molecular mechanism in which Bax (and likely Bak) dimers assemble into oligomers with an even number of molecules that fully or partially delineate pores of different sizes to permeabilize the mitochondrial outer membrane (MOM) during apoptosis.
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Affiliation(s)
- Katia Cosentino
- Interfaculty Institute of Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany
| | - Ana J García-Sáez
- Interfaculty Institute of Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany; Max Planck Institute for Intelligent Systems, Heisenbergstr. 3, Stuttgart, Germany.
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18
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Salvador-Gallego R, Mund M, Cosentino K, Schneider J, Unsay J, Schraermeyer U, Engelhardt J, Ries J, García-Sáez AJ. Bax assembly into rings and arcs in apoptotic mitochondria is linked to membrane pores. EMBO J 2016; 35:389-401. [PMID: 26783362 DOI: 10.15252/embj.201593384] [Citation(s) in RCA: 212] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 12/01/2015] [Indexed: 11/09/2022] Open
Abstract
Bax is a key regulator of apoptosis that, under cell stress, accumulates at mitochondria, where it oligomerizes to mediate the permeabilization of the mitochondrial outer membrane leading to cytochrome c release and cell death. However, the underlying mechanism behind Bax function remains poorly understood. Here, we studied the spatial organization of Bax in apoptotic cells using dual-color single-molecule localization-based super-resolution microscopy. We show that active Bax clustered into a broad distribution of distinct architectures, including full rings, as well as linear and arc-shaped oligomeric assemblies that localized in discrete foci along mitochondria. Remarkably, both rings and arcs assemblies of Bax perforated the membrane, as revealed by atomic force microscopy in lipid bilayers. Our data identify the supramolecular organization of Bax during apoptosis and support a molecular mechanism in which Bax fully or partially delineates pores of different sizes to permeabilize the mitochondrial outer membrane.
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Affiliation(s)
- Raquel Salvador-Gallego
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany Max Planck Institute for Intelligent Systems, Stuttgart, Germany
| | - Markus Mund
- European Molecular Biology Laboratory, Heidelberg, Germany
| | - Katia Cosentino
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany Max Planck Institute for Intelligent Systems, Stuttgart, Germany
| | | | - Joseph Unsay
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany Max Planck Institute for Intelligent Systems, Stuttgart, Germany
| | - Ulrich Schraermeyer
- Core Facility for Electron Microscopy Section for Experimental Vitreoretinal Surgery, Universitätsklinikum Tübingen, Tübingen, Germany
| | | | - Jonas Ries
- European Molecular Biology Laboratory, Heidelberg, Germany
| | - Ana J García-Sáez
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany Max Planck Institute for Intelligent Systems, Stuttgart, Germany
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19
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Cosentino K, Ros U, García-Sáez AJ. Assembling the puzzle: Oligomerization of α-pore forming proteins in membranes. Biochim Biophys Acta 2015; 1858:457-466. [PMID: 26375417 DOI: 10.1016/j.bbamem.2015.09.013] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 08/26/2015] [Accepted: 09/09/2015] [Indexed: 12/21/2022]
Abstract
Pore forming proteins (PFPs) share the ability of creating pores that allow the passage of ions, proteins or other constituents through a wide variety of target membranes, ranging from bacteria to humans. They often cause cell death, as pore formation disrupts the membrane permeability barrier required for maintaining cell homeostasis. The organization into supramolecular complexes or oligomers that pierce the membrane is a common feature of PFPs. However, the molecular pathway of self-assembly and pore opening remains unclear. Here, we review the most recent discoveries in the mechanism of membrane oligomerization and pore formation of a subset of PFPs, the α-PFPs, whose pore-forming domains are formed by helical segments. Only now we are starting to grasp the molecular details of their function, mainly thanks to the introduction of single molecule microscopy and nanoscopy techniques. This article is part of a Special Issue entitled: Pore-forming toxins edited by Mauro Dalla Serra and Franco Gambale.
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Affiliation(s)
- Katia Cosentino
- Interfaculty Institute of Biochemistry (IFIB), University of Tübingen, Tübingen, Germany.,Max-Planck Institute for Intelligent Systems, Stuttgart, Germany
| | - Uris Ros
- Interfaculty Institute of Biochemistry (IFIB), University of Tübingen, Tübingen, Germany.,Max-Planck Institute for Intelligent Systems, Stuttgart, Germany.,Center for Protein Studies, Havana University, Havana, Cuba
| | - Ana J García-Sáez
- Interfaculty Institute of Biochemistry (IFIB), University of Tübingen, Tübingen, Germany.,Max-Planck Institute for Intelligent Systems, Stuttgart, Germany
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20
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Abstract
Atomic force microscopy (AFM) is a versatile, high-resolution imaging technique that allows visualization of biological membranes. It has sufficient magnification to examine membrane substructures and even individual molecules. AFM can act as a force probe to measure interactions and mechanical properties of membranes. Supported lipid bilayers are conventionally used as membrane models in AFM studies. In this protocol, we demonstrate how to prepare supported bilayers and characterize their structure and mechanical properties using AFM. These include bilayer thickness and breakthrough force. The information provided by AFM imaging and force spectroscopy help define mechanical and chemical properties of membranes. These properties play an important role in cellular processes such as maintaining cell hemostasis from environmental stress, bringing membrane proteins together, and stabilizing protein complexes.
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Affiliation(s)
- Joseph D Unsay
- Interfaculty Institute for Biochemistry; Max Planck Institute for Intelligent Systems; German Cancer Research Center;
| | - Katia Cosentino
- Interfaculty Institute for Biochemistry; Max Planck Institute for Intelligent Systems
| | - Ana J García-Sáez
- Interfaculty Institute for Biochemistry; Max Planck Institute for Intelligent Systems
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21
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Beneduci A, Cosentino K, Romeo S, Massa R, Chidichimo G. Effect of millimetre waves on phosphatidylcholine membrane models: a non-thermal mechanism of interaction. Soft Matter 2014; 10:5559-5567. [PMID: 24959858 DOI: 10.1039/c4sm00551a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The nonthermal biological effects of millimeter waves have been mainly attributed to the interaction with biological membranes. Several data on biomimetic membrane systems seem to support this conclusion. In this paper a mechanistic hypothesis is evaluated to explain such an interaction taking into account experimental NMR data on deuterium-labeled phospholipid vesicles. These data showed that millimeter waves induce a time and a hydration-dependent reduction of the water ordering around the phosphocholine headgroups. This effect is here interpreted as a change in membrane water partitioning, due to the coupling of the radiation with the fast rotational dynamics of bound water molecules, that results in a measurable relocation of water molecules from the inner to the outer binding regions of the membrane interface. When millimeter wave exposure is performed in the vicinity of the transition point, this effect can lead to an upward shift of the membrane phase transition temperature from the fluid to the gel phase. At a macroscopic level, this unique sensitivity may be explained by the universal dynamic behaviour of the membranes in the vicinity of the transition point, where a pretransitional increase of membrane area fluctuations, i.e., of the mean area per phospholipid headgroup, is observed. Exposure to millimeter waves increases the above fluctuations and enhances the second order character of the transition.
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Affiliation(s)
- Amerigo Beneduci
- Department of Chemistry and Chemical Technologies, University of Calabria, Arcavacata di Rende (CS), Italy.
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22
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Abstract
Besides their conventional role as energy suppliers for the cell, mitochondria in vertebrates are active regulators of apoptosis. They release apoptotic factors from the intermembrane space into the cytosol through a mechanism that involves the Bcl-2 protein family, mediating permeabilization of the outer mitochondrial membrane. Associated with this event, a number of additional changes affect mitochondria during apoptosis. They include loss of important mitochondrial functions, such as the ability to maintain calcium homeostasis and to generate ATP, as well as mitochondrial fragmentation and cristae remodeling. Moreover, the lipidic component of mitochondrial membranes undergoes important alterations in composition and distribution, which have turned out to be relevant regulatory events for the proteins involved in apoptotic mitochondrial damage.
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Affiliation(s)
- Katia Cosentino
- German Cancer Research Center, Heidelberg, Germany; Max-Planck Institute for Intelligent Systems, Stuttgart, Germany
| | - Ana J García-Sáez
- German Cancer Research Center, Heidelberg, Germany; Max-Planck Institute for Intelligent Systems, Stuttgart, Germany; Interfaculty Institute of Biochemistry (IFIB), University of Tübingen, Tübingen, Germany.
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23
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Abstract
Cardiolipin (CL) is a lipid with unique properties solely found in membranes generating electrochemical potential. It contains four acyl chains and tends to form nonlamellar structures, which are believed to play a key role in membrane structure and function. Indeed, CL alterations have been linked to disorders such as Barth syndrome and Parkinson's disease. However, the molecular effects of CL on membrane organization remain poorly understood. Here, we investigated the structure and physical properties of CL-containing membranes using confocal microscopy, fluorescence correlation spectroscopy, and atomic force microscopy. We found that the fluidity of the lipid bilayer increased and its mechanical stability decreased with CL concentration, indicating that CL decreases the packing of the membrane. Although the presence of up to 20% CL gave rise to flat, stable bilayers, the inclusion of 5% CL promoted the formation of flowerlike domains that grew with time. Surprisingly, we often observed two membrane-piercing events in atomic force spectroscopy experiments with CL-containing membranes. Similar behavior was observed with a lipid mixture mimicking the mitochondrial outer membrane composition. This suggests that CL promotes the formation of membrane areas with apposed double bilayers or nonlamellar structures, similar to those proposed for mitochondrial contact sites. All together, we show that CL induces membrane alterations that support the role of CL in facilitating bilayer structure remodeling, deformation, and permeabilization.
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Affiliation(s)
- Joseph D Unsay
- Max Planck Institute for Intelligent Systems , Heisenbergstr. 3, 70569 Stuttgart, Germany , and German Cancer Research Center , Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
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Beneduci A, Cosentino K, Chidichimo G. Millimeter Wave Radiations Affect Membrane Hydration in Phosphatidylcholine Vesicles. Materials (Basel) 2013; 6:2701-2712. [PMID: 28811403 PMCID: PMC5521226 DOI: 10.3390/ma6072701] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 06/20/2013] [Accepted: 07/02/2013] [Indexed: 11/23/2022]
Abstract
A clear understanding of the response of biological systems to millimeter waves exposure is of increasing interest for the scientific community due to the recent convincing use of these radiations in the ultrafast wireless communications. Here we report a deuterium nuclear magnetic resonance spectroscopy (2H-NMR) investigation on the effects of millimeter waves in the 53–78 GHz range on phosphocholine bio-mimetic membranes. Millimeter waves significantly affect the polar interface of the membrane causing a decrease of the heavy water quadrupole splitting. This effect is as important as inducing the transition from the fluid to the gel phase when the membrane exposure occurs in the neighborhood of the transition point. On the molecular level, the above effect can be well explained by membrane dehydration induced by the radiation.
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Affiliation(s)
- Amerigo Beneduci
- Department of Chemistry, University of Calabria, Via P. Bucci-Cubo 17/D, Arcavacata di Rende (CS) 87040, Italy.
| | - Katia Cosentino
- Department of Chemistry, University of Calabria, Via P. Bucci-Cubo 17/D, Arcavacata di Rende (CS) 87040, Italy.
- Adhesion and Inflammation, CNRS UMR 7333, INSERM U1067, Aix Marseille University, Luminy, Marseille 13009, France.
| | - Giuseppe Chidichimo
- Department of Chemistry, University of Calabria, Via P. Bucci-Cubo 17/D, Arcavacata di Rende (CS) 87040, Italy.
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25
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Cosentino K, Beneduci A, Ramundo-Orlando A, Chidichimo G. The influence of millimeter waves on the physical properties of large and giant unilamellar vesicles. J Biol Phys 2013; 39:395-410. [PMID: 23860916 PMCID: PMC3689357 DOI: 10.1007/s10867-012-9296-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Accepted: 12/17/2012] [Indexed: 11/26/2022] Open
Abstract
Exposure of cell membranes to an electromagnetic field (EMF) in the millimeter wave band (30-300 GHz) can produce a variety of responses. Further, many of the vibrational modes in complex biomolecules fall in the 1-100 GHz range. In addition to fundamental scientific interest, this may have applications in the development of diagnostic and therapeutic medical applications. In the present work, lipid vesicles of different size were used to study the effects of exposure to radiation at 52-72 GHz, with incident power densities (IPD) of 0.0035-0.010 mW/cm(2), on the chemical-physical properties of cell membranes. Large unilamellar vesicles (LUVs) were used to study the effect of the radiation on the physical stability of vesicles by dynamic light scattering. An inhibition of the aging processes (Ostwald ripening), which usually occur in these vesicles because of their thermodynamic instability, resulted. Giant unilamellar vesicles (GUVs) were used to study the effect of the radiation on membrane water permeability under osmotic stress by phase contrast microscopy. In this case, a decrease in the water membrane permeability of the irradiated samples was observed. We advance the hypothesis that both the above effects may be explained in terms of a change of the polarization states of water induced by the radiation, which causes a partial dehydration of the membrane and consequently a greater packing density (increased membrane rigidity).
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Affiliation(s)
- Katia Cosentino
- Department of Chemistry, University of Calabria, Via P. Bucci-Cubo 17/D, 87036, Arcavacata di Rende, CS, Italy.
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26
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27
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28
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Affiliation(s)
- B. M. Stidd
- Department of Biological Sciences, Western Illinois University, Macomb 61455
| | - K. Cosentino
- Department of Biological Sciences, Western Illinois University, Macomb 61455
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29
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Werner HJ, Cosentino K, Jolly HW, Carpenter CL. Electron microscopic observations of the fine structure of Trichophyton rubrum dark. J Invest Dermatol 1974; 63:423-4. [PMID: 4436601 DOI: 10.1111/1523-1747.ep12676592] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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