1
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Pattipeiluhu R, Zeng Y, Hendrix MMRM, Voets IK, Kros A, Sharp TH. Liquid crystalline inverted lipid phases encapsulating siRNA enhance lipid nanoparticle mediated transfection. Nat Commun 2024; 15:1303. [PMID: 38347001 PMCID: PMC10861598 DOI: 10.1038/s41467-024-45666-5] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 01/31/2024] [Indexed: 02/15/2024] Open
Abstract
Efficient cytosolic delivery of RNA molecules remains a formidable barrier for RNA therapeutic strategies. Lipid nanoparticles (LNPs) serve as state-of-the-art carriers that can deliver RNA molecules intracellularly, as exemplified by the recent implementation of several vaccines against SARS-CoV-2. Using a bottom-up rational design approach, we assemble LNPs that contain programmable lipid phases encapsulating small interfering RNA (siRNA). A combination of cryogenic transmission electron microscopy, cryogenic electron tomography and small-angle X-ray scattering reveals that we can form inverse hexagonal structures, which are present in a liquid crystalline nature within the LNP core. Comparison with lamellar LNPs reveals that the presence of inverse hexagonal phases enhances the intracellular silencing efficiency over lamellar structures. We then demonstrate that lamellar LNPs exhibit an in situ transition from a lamellar to inverse hexagonal phase upon interaction with anionic membranes, whereas LNPs containing pre-programmed liquid crystalline hexagonal phases bypass this transition for a more efficient one-step delivery mechanism, explaining the increased silencing effect. This rational design of LNPs with defined lipid structures aids in the understanding of the nano-bio interface and adds substantial value for LNP design, optimization and use.
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Affiliation(s)
- Roy Pattipeiluhu
- Supramolecular and Biomaterials Chemistry, Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The Netherlands
- Department of Cell and Chemical Biology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC, Leiden, The Netherlands
- BioNTech SE, An der Goldgrube 12, 55131, Mainz, Germany
| | - Ye Zeng
- Supramolecular and Biomaterials Chemistry, Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The Netherlands
| | - Marco M R M Hendrix
- Self-Organizing Soft Matter, Department of Chemical Engineering and Chemistry & Institute of Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
| | - Ilja K Voets
- Self-Organizing Soft Matter, Department of Chemical Engineering and Chemistry & Institute of Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
| | - Alexander Kros
- Supramolecular and Biomaterials Chemistry, Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The Netherlands.
| | - Thomas H Sharp
- Department of Cell and Chemical Biology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC, Leiden, The Netherlands.
- School of Biochemistry, University of Bristol, Bristol, BS8 1TD, United Kingdom.
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2
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Dijkstra DJ, van de Bovenkamp FS, Abendstein L, Zuijderduijn R, Pool J, Kramer CSM, Slot LM, Drijfhout JW, de Vor L, Gelderman KA, Rooijakkers SHM, Zaldumbide A, Vidarsson G, Sharp TH, Parren PWHI, Trouw LA. Human anti-C1q autoantibodies bind specifically to solid-phase C1q and enhance phagocytosis but not complement activation. Proc Natl Acad Sci U S A 2023; 120:e2310666120. [PMID: 38048459 PMCID: PMC10723154 DOI: 10.1073/pnas.2310666120] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 10/27/2023] [Indexed: 12/06/2023] Open
Abstract
Autoantibodies directed against complement component C1q are commonly associated with autoimmune diseases, especially systemic lupus erythematosus. Importantly, these anti-C1q autoantibodies are specific for ligand-bound, solid-phase C1q and do not bind to fluid-phase C1q. In patients with anti-C1q, C1q levels are in the normal range, and the autoantibodies are thus not depleting. To study these human anti-C1q autoantibodies at the molecular level, we isolated C1q-reactive B cells and recombinantly produced nine monoclonal antibodies (mAbs) from four different healthy individuals. The isolated mAbs were of the IgG isotype, contained extensively mutated variable domains, and showed high affinity to the collagen-like region of C1q. The anti-C1q mAbs exclusively bound solid-phase C1q in complex with its natural ligands, including immobilized or antigen-bound IgG, IgM or CRP, and necrotic cells. Competition experiments reveal that at least 2 epitopes, also targeted by anti-C1q antibodies in sera from SLE patients, are recognized. Electron microscopy with hexameric IgG-C1q immune complexes demonstrated that multiple mAbs can interact with a single C1q molecule and identified the region of C1q targeted by these mAbs. The opsonization of immune complexes with anti-C1q greatly enhanced Fc-receptor-mediated phagocytosis but did not increase complement activation. We conclude that human anti-C1q autoantibodies specifically bind neo-epitopes on solid-phase C1q, which results in an increase in Fc-receptor-mediated effector functions that may potentially contribute to autoimmune disease immunopathology.
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Affiliation(s)
- Douwe J. Dijkstra
- Department of Immunology, Leiden University Medical Center, Leiden2300 RC, The Netherlands
| | - Fleur S. van de Bovenkamp
- Department of Immunology, Leiden University Medical Center, Leiden2300 RC, The Netherlands
- Lava Therapeutics, Utrecht3584 CM, The Netherlands
| | - Leoni Abendstein
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden2300 RC, The Netherlands
| | - Rob Zuijderduijn
- Department of Immunology, Leiden University Medical Center, Leiden2300 RC, The Netherlands
| | - Jos Pool
- Department of Immunology, Leiden University Medical Center, Leiden2300 RC, The Netherlands
| | - Cynthia S. M. Kramer
- Department of Immunology, Leiden University Medical Center, Leiden2300 RC, The Netherlands
| | - Linda M. Slot
- Department of Rheumatology, Leiden University Medical Center, Leiden2300 RC, The Netherlands
| | - Jan W. Drijfhout
- Department of Immunology, Leiden University Medical Center, Leiden2300 RC, The Netherlands
| | - Lisanne de Vor
- Department of Medical Microbiology, University Medical Center, Utrecht3584 CX, The Netherlands
| | | | - Suzan H. M. Rooijakkers
- Department of Medical Microbiology, University Medical Center, Utrecht3584 CX, The Netherlands
| | - Arnaud Zaldumbide
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden2300 RC, The Netherlands
| | - Gestur Vidarsson
- Department of Experimental Immunohematology, Sanquin Research, Amsterdam1066 CX, The Netherlands
| | - Thomas H. Sharp
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden2300 RC, The Netherlands
| | - Paul W. H. I. Parren
- Department of Immunology, Leiden University Medical Center, Leiden2300 RC, The Netherlands
- Gyes BV, Naarden1411 DC, The Netherlands
| | - Leendert A. Trouw
- Department of Immunology, Leiden University Medical Center, Leiden2300 RC, The Netherlands
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3
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Last MGF, Noteborn WEM, Voortman LM, Sharp TH. Super-resolution fluorescence imaging of cryosamples does not limit achievable resolution in cryoEM. J Struct Biol 2023; 215:108040. [PMID: 37918761 DOI: 10.1016/j.jsb.2023.108040] [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: 03/20/2023] [Revised: 10/27/2023] [Accepted: 10/30/2023] [Indexed: 11/04/2023]
Abstract
Correlated super-resolution cryo-fluorescence and cryo-electron microscopy (cryoEM) has been gaining popularity as a method to investigate biological samples with high resolution and specificity. A concern in this combined method (called SR-cryoCLEM), however, is whether and how fluorescence imaging prior to cryoEM acquisition is detrimental to sample integrity. In this report, we investigated the effect of high-dose laser light (405, 488, and 561 nm) irradiation on apoferritin samples prepared for cryoEM with excitation wavelengths commonly used in fluorescence microscopy, and compared these samples to controls that were kept in the dark. We found that laser illumination, of equal duration and intensity as used in cryo-single molecule localization microscopy (cryoSMLM) and in the presence of high concentrations of fluorescent protein, did not affect the achievable resolution in cryoEM, with final reconstructions reaching resolutions of ∼ 1.8 Å regardless of the laser illumination. The finding that super-resolution fluorescence imaging of cryosamples prior to cryoEM data acquisition does not limit the achievable resolution suggests that super-resolution cryo-fluorescence microscopy and in situ structural biology using cryoEM are entirely compatible.
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Affiliation(s)
- Mart G F Last
- Department of Cell and Chemical Biology, Leiden University Medical Centre, 2300 RC Leiden, The Netherlands
| | - Willem E M Noteborn
- Netherlands Centre for Electron Nanoscopy, Leiden University, 2333 AL Leiden, The Netherlands
| | - Lenard M Voortman
- Department of Cell and Chemical Biology, Leiden University Medical Centre, 2300 RC Leiden, The Netherlands
| | - Thomas H Sharp
- Department of Cell and Chemical Biology, Leiden University Medical Centre, 2300 RC Leiden, The Netherlands.
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4
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Last MGF, Voortman LM, Sharp TH. scNodes: a correlation and processing toolkit for super-resolution fluorescence and electron microscopy. Nat Methods 2023; 20:1445-1446. [PMID: 37596472 DOI: 10.1038/s41592-023-01991-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/20/2023]
Affiliation(s)
- Mart G F Last
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - Lenard M Voortman
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - Thomas H Sharp
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, the Netherlands.
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5
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Zeng Y, Shen M, Pattipeiluhu R, Zhou X, Zhang Y, Bakkum T, Sharp TH, Boyle AL, Kros A. Efficient mRNA delivery using lipid nanoparticles modified with fusogenic coiled-coil peptides. Nanoscale 2023; 15:15206-15218. [PMID: 37671560 DOI: 10.1039/d3nr02175k] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/07/2023]
Abstract
Gene delivery has great potential in modulating protein expression in specific cells to treat diseases. Such therapeutic gene delivery demands sufficient cellular internalization and endosomal escape. Of various nonviral nucleic acid delivery systems, lipid nanoparticles (LNPs) are the most advanced, but still, are very inefficient as the majority are unable to escape from endosomes/lysosomes. Here, we develop a highly efficient gene delivery system using fusogenic coiled-coil peptides. We modified LNPs, carrying EGFP-mRNA, and cells with complementary coiled-coil lipopeptides. Coiled-coil formation between these lipopeptides induced fast nucleic acid uptake and enhanced GFP expression. The cellular uptake of coiled-coil modified LNPs is likely driven by membrane fusion thereby omitting typical endocytosis pathways. This direct cytosolic delivery circumvents the problems commonly observed with the limited endosomal escape of mRNA. Therefore fusogenic coiled-coil peptide modification of existing LNP formulations to enhance nucleic acid delivery efficiency could be beneficial for several gene therapy applications.
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Affiliation(s)
- Ye Zeng
- Department of Supramolecular & Biomaterials Chemistry, Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands.
| | - Mengjie Shen
- Department of Supramolecular & Biomaterials Chemistry, Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands.
| | - Roy Pattipeiluhu
- Department of Supramolecular & Biomaterials Chemistry, Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands.
| | - Xuequan Zhou
- Department of Supramolecular & Biomaterials Chemistry, Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands.
| | - Yun Zhang
- Department of Supramolecular & Biomaterials Chemistry, Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands.
| | - Thomas Bakkum
- Department of Supramolecular & Biomaterials Chemistry, Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands.
| | - Thomas H Sharp
- Department of Cell and Chemical Biology, Section Electron Microscopy, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
| | - Aimee L Boyle
- Department of Supramolecular & Biomaterials Chemistry, Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands.
| | - Alexander Kros
- Department of Supramolecular & Biomaterials Chemistry, Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands.
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6
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Abendstein L, Dijkstra DJ, Tjokrodirijo RTN, van Veelen PA, Trouw LA, Hensbergen PJ, Sharp TH. Complement is activated by elevated IgG3 hexameric platforms and deposits C4b onto distinct antibody domains. Nat Commun 2023; 14:4027. [PMID: 37419978 PMCID: PMC10328927 DOI: 10.1038/s41467-023-39788-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [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: 11/16/2022] [Accepted: 06/29/2023] [Indexed: 07/09/2023] Open
Abstract
IgG3 is unique among the IgG subclasses due to its extended hinge, allotypic diversity and enhanced effector functions, including highly efficient pathogen neutralisation and complement activation. It is also underrepresented as an immunotherapeutic candidate, partly due to a lack of structural information. Here, we use cryoEM to solve structures of antigen-bound IgG3 alone and in complex with complement components. These structures reveal a propensity for IgG3-Fab clustering, which is possible due to the IgG3-specific flexible upper hinge region and may maximise pathogen neutralisation by forming high-density antibody arrays. IgG3 forms elevated hexameric Fc platforms that extend above the protein corona to maximise binding to receptors and the complement C1 complex, which here adopts a unique protease conformation that may precede C1 activation. Mass spectrometry reveals that C1 deposits C4b directly onto specific IgG3 residues proximal to the Fab domains. Structural analysis shows this to be caused by the height of the C1-IgG3 complex. Together, these data provide structural insights into the role of the unique IgG3 extended hinge, which will aid the development and design of upcoming immunotherapeutics based on IgG3.
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Affiliation(s)
- Leoni Abendstein
- Department of Cell and Chemical Biology, Leiden University Medical Center, 2300 RC, Leiden, The Netherlands
| | - Douwe J Dijkstra
- Department of Immunology, Leiden University Medical Center, 2333 ZA, Leiden, The Netherlands
| | - Rayman T N Tjokrodirijo
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA, Leiden, The Netherlands
| | - Peter A van Veelen
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA, Leiden, The Netherlands
| | - Leendert A Trouw
- Department of Immunology, Leiden University Medical Center, 2333 ZA, Leiden, The Netherlands
| | - Paul J Hensbergen
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA, Leiden, The Netherlands
| | - Thomas H Sharp
- Department of Cell and Chemical Biology, Leiden University Medical Center, 2300 RC, Leiden, The Netherlands.
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7
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Last MGF, Tuijtel MW, Voortman LM, Sharp TH. Selecting optimal support grids for super-resolution cryogenic correlated light and electron microscopy. Sci Rep 2023; 13:8270. [PMID: 37217690 DOI: 10.1038/s41598-023-35590-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 05/20/2023] [Indexed: 05/24/2023] Open
Abstract
Cryogenic transmission electron microscopy (cryo-TEM) and super-resolution fluorescence microscopy are two popular and ever improving methods for high-resolution imaging of biological samples. In recent years, the combination of these two techniques into one correlated workflow has gained attention as a promising route towards contextualizing and enriching cryo-TEM imagery. A problem that is often encountered in the combination of these methods is that of light-induced damage to the sample during fluorescence imaging that renders the sample structure unsuitable for TEM imaging. In this paper, we describe how absorption of light by TEM sample support grids leads to sample damage, and we systematically explore the importance of parameters of grid design. We explain how, by changing the grid geometry and materials, one can increase the maximum illumination power density in fluorescence microscopy by up to an order of magnitude. Finally, we demonstrate the significant improvements in super-resolution image quality that are enabled by the selection of support grids that are optimally suited for correlated cryo-microscopy.
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Affiliation(s)
- Mart G F Last
- Department of Cell and Chemical Biology, Leiden University Medical Centre, 2300 RC, Leiden, The Netherlands
| | - Maarten W Tuijtel
- Department of Molecular Sociology, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438, Frankfurt Am Main, Germany
| | - Lenard M Voortman
- Department of Cell and Chemical Biology, Leiden University Medical Centre, 2300 RC, Leiden, The Netherlands
| | - Thomas H Sharp
- Department of Cell and Chemical Biology, Leiden University Medical Centre, 2300 RC, Leiden, The Netherlands.
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8
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Ji C, Shen H, Su C, Li Y, Chen S, Sharp TH, Xiao J. Plasmodium falciparum has evolved multiple mechanisms to hijack human immunoglobulin M. Nat Commun 2023; 14:2650. [PMID: 37156765 PMCID: PMC10167334 DOI: 10.1038/s41467-023-38320-z] [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] [Received: 11/02/2022] [Accepted: 04/25/2023] [Indexed: 05/10/2023] Open
Abstract
Plasmodium falciparum causes the most severe malaria in humans. Immunoglobulin M (IgM) serves as the first line of humoral defense against infection and potently activates the complement pathway to facilitate P. falciparum clearance. A number of P. falciparum proteins bind IgM, leading to immune evasion and severe disease. However, the underlying molecular mechanisms remain unknown. Here, using high-resolution cryo-electron microscopy, we delineate how P. falciparum proteins VAR2CSA, TM284VAR1, DBLMSP, and DBLMSP2 target IgM. Each protein binds IgM in a different manner, and together they present a variety of Duffy-binding-like domain-IgM interaction modes. We further show that these proteins interfere directly with IgM-mediated complement activation in vitro, with VAR2CSA exhibiting the most potent inhibitory effect. These results underscore the importance of IgM for human adaptation of P. falciparum and provide critical insights into its immune evasion mechanism.
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Affiliation(s)
- Chenggong Ji
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
- Changping Laboratory, Beijing, PR China
| | - Hao Shen
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Chen Su
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Yaxin Li
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Shihua Chen
- Joint Graduate Program of Peking-Tsinghua-NIBS, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Thomas H Sharp
- Department of Cell and Chemical Biology, Section Electron Microscopy, Leiden University Medical Center, 2300, RC, Leiden, The Netherlands
| | - Junyu Xiao
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China.
- Changping Laboratory, Beijing, PR China.
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China.
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9
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Last MGF, Voortman LM, Sharp TH. Measuring cryo-TEM sample thickness using reflected light microscopy and machine learning. J Struct Biol 2023; 215:107965. [PMID: 37100102 DOI: 10.1016/j.jsb.2023.107965] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 03/29/2023] [Accepted: 04/14/2023] [Indexed: 04/28/2023]
Abstract
In cryo-transmission electron microscopy (cryo-TEM), sample thickness is one of the most important parameters that governs image quality. When combining cryo-TEM with other imaging methods, such as light microscopy, measuring and controlling the sample thickness to ensure suitability of samples becomes even more critical due to the low throughput of such correlated imaging experiments. Here, we present a method to assess the sample thickness using reflected light microscopy and machine learning that can be used prior to TEM imaging of a sample. The method makes use of the thin-film interference effect that is observed when imaging narrow-band LED light sources reflected by thin samples. By training a neural network to translate such reflection images into maps of the underlying sample thickness, we are able to accurately predict the thickness of cryo-TEM samples using a light microscope. We exemplify our approach using mammalian cells grown on TEM grids, and demonstrate that the thickness predictions are highly similar to the measured sample thickness. The open-source software described herein, including the neural network and algorithms to generate training datasets, is freely available at github.com/bionanopatterning/thicknessprediction. With the recent development of in situ cellular structural biology using cryo-TEM, there is a need for fast and accurate assessment of sample thickness prior to high-resolution imaging. We anticipate that our method will improve the throughput of this assessment by providing an alternative method to screening using cryo-TEM. Furthermore, we demonstrate that our method can be incorporated into correlative imaging workflows to locate intracellular proteins at sites ideal for high-resolution cryo-TEM imaging.
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Affiliation(s)
- Mart G F Last
- Department of Cell and Chemical Biology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
| | - Lenard M Voortman
- Department of Cell and Chemical Biology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
| | - Thomas H Sharp
- Department of Cell and Chemical Biology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands.
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10
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Pattipeiluhu R, Arias-Alpizar G, Basha G, Chan KYT, Bussmann J, Sharp TH, Moradi MA, Sommerdijk N, Harris EN, Cullis PR, Kros A, Witzigmann D, Campbell F. Anionic Lipid Nanoparticles Preferentially Deliver mRNA to the Hepatic Reticuloendothelial System. Adv Mater 2022; 34:e2201095. [PMID: 35218106 PMCID: PMC9461706 DOI: 10.1002/adma.202201095] [Citation(s) in RCA: 56] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Indexed: 05/04/2023]
Abstract
Lipid nanoparticles (LNPs) are the leading nonviral technologies for the delivery of exogenous RNA to target cells in vivo. As systemic delivery platforms, these technologies are exemplified by Onpattro, an approved LNP-based RNA interference therapy, administered intravenously and targeted to parenchymal liver cells. The discovery of systemically administered LNP technologies capable of preferential RNA delivery beyond hepatocytes has, however, proven more challenging. Here, preceded by comprehensive mechanistic understanding of in vivo nanoparticle biodistribution and bodily clearance, an LNP-based messenger RNA (mRNA) delivery platform is rationally designed to preferentially target the hepatic reticuloendothelial system (RES). Evaluated in embryonic zebrafish, validated in mice, and directly compared to LNP-mRNA systems based on the lipid composition of Onpattro, RES-targeted LNPs significantly enhance mRNA expression both globally within the liver and specifically within hepatic RES cell types. Hepatic RES targeting requires just a single lipid change within the formulation of Onpattro to switch LNP surface charge from neutral to anionic. This technology not only provides new opportunities to treat liver-specific and systemic diseases in which RES cell types play a key role but, more importantly, exemplifies that rational design of advanced RNA therapies must be preceded by a robust understanding of the dominant nano-biointeractions involved.
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Affiliation(s)
- Roy Pattipeiluhu
- Supramolecular and Biomaterials Chemistry, Leiden Institute of Chemistry, Leiden University, Leiden, 2333 CC, The Netherlands
- BioNanoPatterning, Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, 2333 RC, The Netherlands
| | - Gabriela Arias-Alpizar
- Supramolecular and Biomaterials Chemistry, Leiden Institute of Chemistry, Leiden University, Leiden, 2333 CC, The Netherlands
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden University, Leiden, 2333 CC, The Netherlands
| | - Genc Basha
- NanoMedicines Research Group, Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, V6T 1Z3, Canada
| | - Karen Y T Chan
- NanoMedicines Research Group, Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, V6T 1Z3, Canada
| | - Jeroen Bussmann
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden University, Leiden, 2333 CC, The Netherlands
| | - Thomas H Sharp
- BioNanoPatterning, Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, 2333 RC, The Netherlands
| | - Mohammad-Amin Moradi
- Materials and Interface Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Eindhoven, 5600 MB, The Netherlands
| | - Nico Sommerdijk
- Department of Biochemistry, Institute of Molecular Life Sciences, Radboud University Medical Center, Nijmegen, 6500 HB, The Netherlands
| | - Edward N Harris
- Department of Biochemistry, University of Nebraska, Lincoln, NE, 68588, USA
| | - Pieter R Cullis
- NanoMedicines Research Group, Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, V6T 1Z3, Canada
- NanoMedicines Innovation Network (NMIN), University of British Columbia, Vancouver, V6T 1Z3, Canada
- NanoVation Therapeutics Inc., 2405 Wesbrook Mall 4th Floor, Vancouver, V6T 1Z3, Canada
| | - Alexander Kros
- Supramolecular and Biomaterials Chemistry, Leiden Institute of Chemistry, Leiden University, Leiden, 2333 CC, The Netherlands
| | - Dominik Witzigmann
- NanoMedicines Research Group, Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, V6T 1Z3, Canada
- NanoMedicines Innovation Network (NMIN), University of British Columbia, Vancouver, V6T 1Z3, Canada
- NanoVation Therapeutics Inc., 2405 Wesbrook Mall 4th Floor, Vancouver, V6T 1Z3, Canada
| | - Frederick Campbell
- Supramolecular and Biomaterials Chemistry, Leiden Institute of Chemistry, Leiden University, Leiden, 2333 CC, The Netherlands
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11
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Noone DP, van der Velden TT, Sharp TH. Cryo-Electron Microscopy and Biochemical Analysis Offer Insights Into the Effects of Acidic pH, Such as Occur During Acidosis, on the Complement Binding Properties of C-Reactive Protein. Front Immunol 2022; 12:757633. [PMID: 34975846 PMCID: PMC8716467 DOI: 10.3389/fimmu.2021.757633] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 11/22/2021] [Indexed: 11/15/2022] Open
Abstract
The pentraxin family of proteins includes C-reactive protein (CRP), a canonical marker for the acute phase inflammatory response. As compared to normal physiological conditions in human serum, under conditions associated with damage and inflammation, such as acidosis and the oxidative burst, CRP exhibits modulated biochemical properties that may have a structural basis. Here, we explore how pH and ligand binding affect the structure and biochemical properties of CRP. Cryo-electron microscopy was used to solve structures of CRP at pH 7.5 or pH 5 and in the presence or absence of the ligand phosphocholine (PCh), which yielded 7 new high-resolution structures of CRP, including pentameric and decameric complexes. Structures previously derived from crystallography were imperfect pentagons, as shown by the variable angles between each subunit, whereas pentameric CRP derived from cryoEM was found to have C5 symmetry, with subunits forming a regular pentagon with equal angles. This discrepancy indicates flexibility at the interfaces of monomers that may relate to activation of the complement system by the C1 complex. CRP also appears to readily decamerise in solution into dimers of pentamers, which obscures the postulated binding sites for C1. Subtle structural rearrangements were observed between the conditions tested, including a putative change in histidine protonation that may prime the disulphide bridges for reduction and enhanced ability to activate the immune system. Enzyme-linked immunosorbent assays showed that CRP had markedly increased association to the C1 complex and immunoglobulins under conditions associated with acidosis, whilst a reduction in the Ca2+ concentration lowered this pH-sensitivity for C1q, but not immunoglobulins, suggesting different modes of binding. These data suggest a model whereby a change in the ionic nature of CRP and immunological proteins can make it more adhesive to potential ligands without large structural rearrangements.
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Affiliation(s)
- Dylan P Noone
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, Netherlands
| | - Tijn T van der Velden
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, Netherlands
| | - Thomas H Sharp
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, Netherlands
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12
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Mei H, Boom J, El Abdellaoui S, Abdelmohsen K, Munk R, Martindale JL, Kloet S, Kielbasa SM, Sharp TH, Gorospe M, Raz V. Alternative polyadenylation utilization results in ribosome assembly and mRNA translation deficiencies in a model for muscle aging. J Gerontol A Biol Sci Med Sci 2022; 77:1130-1140. [PMID: 35245938 PMCID: PMC9159670 DOI: 10.1093/gerona/glac058] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Indexed: 11/15/2022] Open
Abstract
Aging-associated muscle wasting is regulated by multiple molecular processes, whereby aberrant mRNA processing regulation induces muscle wasting. The poly(A)-binding protein nuclear 1 (PABPN1) regulates polyadenylation site (PAS) utilization, in the absence of PABPN1 the alternative PAS (APA) is utilized. Reduced PABPN1 levels induce muscle wasting where the expression of cellular processes regulating protein homeostasis, the ubiquitin-proteasome system, and translation, are robustly dysregulated. Translation is impacted by mRNA levels, but PABPN1 impact on translation is not fully understood. Here we show that a persistent reduction in PABPN1 levels led to a significant loss of translation efficiency. RNA sequencing of rRNA-depleted libraries from polysome traces revealed reduced mRNA abundance across ribosomal fractions, as well as reduced levels of small RNAs. We show that the abundance of translated mRNAs in the polysomes correlated with PAS switches at the 3'-UTR. Those mRNAs are enriched in cellular processes that are essential for proper muscle function. This study suggests that the effect of PABPN1 on translation efficiency impacts protein homeostasis in aging-associated muscle atrophy.
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Affiliation(s)
- Hailiang Mei
- Sequencing Analysis Support Core, Leiden University Medical Centre, Leiden, The Netherlands
| | - Jasper Boom
- Sequencing Analysis Support Core, Leiden University Medical Centre, Leiden, The Netherlands
| | - Salma El Abdellaoui
- Department of Human Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Kotb Abdelmohsen
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Rachel Munk
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Jennifer L Martindale
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Susan Kloet
- Department of Human Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Szymone M Kielbasa
- Sequencing Analysis Support Core, Leiden University Medical Centre, Leiden, The Netherlands
| | - Thomas H Sharp
- Department of Cell and Chemical Biology, Leiden University Medical Centre, Leiden The Netherlands
| | - Myriam Gorospe
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Vered Raz
- Department of Human Genetics, Leiden University Medical Centre, Leiden, The Netherlands
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13
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Abstract
DNA origami nanostructures generally require a single scaffold strand of specific length, combined with many small staple strands. Ideally, the length of the scaffold strand should be dictated by the size of the designed nanostructure. However, synthesizing arbitrary-length single-stranded DNA in sufficient quantities is difficult. Here, we describe a straightforward and accessible method to produce defined-length ssDNA scaffolds using PCR and subsequent selective enzymatic digestion with T7 exonuclease. This approach produced ssDNA with higher yields than other methods and without the need for purification, which significantly decreased the time from PCR to obtaining pure DNA origami. Furthermore, this enabled us to perform true one-pot synthesis of defined-size DNA origami nanostructures. Additionally, we show that multiple smaller ssDNA scaffolds can efficiently substitute longer scaffolds in the formation of DNA origami.
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Affiliation(s)
- Willem E M Noteborn
- Department of Cell and Chemical Biology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
| | - Leoni Abendstein
- Department of Cell and Chemical Biology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
| | - Thomas H Sharp
- Department of Cell and Chemical Biology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
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14
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Lubbers R, Oostindie SC, Dijkstra DJ, Parren PWHI, Verheul MK, Abendstein L, Sharp TH, de Ru A, Janssen GMC, van Veelen PA, van den Bremer ETJ, Bleijlevens B, de Kreuk BJ, Beurskens FJ, Trouw LA. Carbamylation reduces the capacity of IgG for hexamerization and complement activation. Clin Exp Immunol 2019; 200:1-11. [PMID: 31853959 PMCID: PMC7066385 DOI: 10.1111/cei.13411] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/11/2019] [Indexed: 02/06/2023] Open
Abstract
Carbamylation is a post‐translational modification that can be detected on a range of proteins, including immunoglobulin (Ig)G, in several clinical conditions. Carbamylated IgG (ca‐IgG) was reported to lose its capacity to trigger complement activation, but the mechanism remains unclear. Because C1q binds with high affinity to hexameric IgG, we analyzed whether carbamylation of IgG affects binding of C1q, hexamerization and complement‐dependent cytotoxicity (CDC). Synovial tissues of rheumatoid arthritis (RA) patients were analyzed for the presence of ca‐IgG in vivo. Synovial tissues from RA patients were analyzed for the presence of ca‐IgG using mass spectrometry (MS). Monomeric or hexameric antibodies were carbamylated in vitro and quality in solution was controlled. The capacity of ca‐IgG to activate complement was analyzed in enzyme‐linked immunosorbent (ELISAs) and cellular CDC assays. Using MS, we identified ca‐IgG to be present in the joints of RA patients. Using in vitro carbamylated antibodies, we observed that ca‐IgG lost its capacity to activate complement in both solid‐phase and CDC assays. Mixing ca‐IgG with non‐modified IgG did not result in effective inhibition of complement activation by ca‐IgG. Carbamylation of both monomeric IgG and preformed hexameric IgG greatly impaired the capacity to trigger complement activation. Furthermore, upon carbamylation, the preformed hexameric IgG dissociated into monomeric IgG in solution, indicating that carbamylation influences both hexamerization and C1q binding. In conclusion, ca‐IgG can be detected in vivo and has a strongly reduced capacity to activate complement which is, in part, mediated through a reduced ability to form hexamers.
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Affiliation(s)
- R Lubbers
- Department Rheumatology, Leiden University Medical Center, Leiden, the Netherlands
| | - S C Oostindie
- Genmab, Utrecht, the Netherlands.,Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, the Netherlands
| | - D J Dijkstra
- Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, the Netherlands
| | - P W H I Parren
- Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, the Netherlands.,Lava Therapeutics, Utrecht, the Netherlands
| | - M K Verheul
- Department Rheumatology, Leiden University Medical Center, Leiden, the Netherlands
| | - L Abendstein
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - T H Sharp
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - A de Ru
- Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, the Netherlands
| | - G M C Janssen
- Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, the Netherlands
| | - P A van Veelen
- Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, the Netherlands
| | | | | | | | | | - L A Trouw
- Department Rheumatology, Leiden University Medical Center, Leiden, the Netherlands.,Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, the Netherlands
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15
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Gros P, Boyle AL, Diebolder CA, Kros A, Koster AJ, Sharp TH. Cryo-electron tomography reveals early steps of complement activation by IgM. Mol Immunol 2018. [DOI: 10.1016/j.molimm.2018.06.081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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16
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Ugurlar D, Howes SC, de Kreuk BJ, Koning RI, de Jong RN, Beurskens FJ, Schuurman J, Koster AJ, Sharp TH, Parren PWHI, Gros P. Structures of C1-IgG1 provide insights into how danger pattern recognition activates complement. Science 2018; 359:794-797. [PMID: 29449492 DOI: 10.1126/science.aao4988] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 01/10/2018] [Indexed: 01/10/2023]
Abstract
Danger patterns on microbes or damaged host cells bind and activate C1, inducing innate immune responses and clearance through the complement cascade. How these patterns trigger complement initiation remains elusive. Here, we present cryo-electron microscopy analyses of C1 bound to monoclonal antibodies in which we observed heterogeneous structures of single and clustered C1-immunoglobulin G1 (IgG1) hexamer complexes. Distinct C1q binding sites are observed on the two Fc-CH2 domains of each IgG molecule. These are consistent with known interactions and also reveal additional interactions, which are supported by functional IgG1-mutant analysis. Upon antibody binding, the C1q arms condense, inducing rearrangements of the C1r2s2 proteases and tilting C1q's cone-shaped stalk. The data suggest that C1r may activate C1s within single, strained C1 complexes or between neighboring C1 complexes on surfaces.
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Affiliation(s)
- Deniz Ugurlar
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands
| | - Stuart C Howes
- Section of Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center, Einthovenweg 20, 2300 RC Leiden, Netherlands
| | | | - Roman I Koning
- Section of Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center, Einthovenweg 20, 2300 RC Leiden, Netherlands.,NeCEN, Gorlaeus Laboratories, Leiden University, 2333 CC Leiden, Netherlands
| | | | | | | | - Abraham J Koster
- Section of Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center, Einthovenweg 20, 2300 RC Leiden, Netherlands.,NeCEN, Gorlaeus Laboratories, Leiden University, 2333 CC Leiden, Netherlands
| | - Thomas H Sharp
- Section of Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center, Einthovenweg 20, 2300 RC Leiden, Netherlands.
| | - Paul W H I Parren
- Genmab, Yalelaan 60, 3584 CM Utrecht, Netherlands. .,Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, Netherlands
| | - Piet Gros
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands.
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17
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Tong C, Liu T, Saez Talens V, Noteborn WEM, Sharp TH, Hendrix MMRM, Voets IK, Mummery CL, Orlova VV, Kieltyka RE. Squaramide-Based Supramolecular Materials for Three-Dimensional Cell Culture of Human Induced Pluripotent Stem Cells and Their Derivatives. Biomacromolecules 2018; 19:1091-1099. [PMID: 29528623 PMCID: PMC5894061 DOI: 10.1021/acs.biomac.7b01614] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2017] [Revised: 02/18/2018] [Indexed: 02/06/2023]
Abstract
Synthetic hydrogel materials can recapitulate the natural cell microenvironment; however, it is equally necessary that the gels maintain cell viability and phenotype while permitting reisolation without stress, especially for use in the stem cell field. Here, we describe a family of synthetically accessible, squaramide-based tripodal supramolecular monomers consisting of a flexible tris(2-aminoethyl)amine (TREN) core that self-assemble into supramolecular polymers and eventually into self-recovering hydrogels. Spectroscopic measurements revealed that monomer aggregation is mainly driven by a combination of hydrogen bonding and hydrophobicity. The self-recovering hydrogels were used to encapsulate NIH 3T3 fibroblasts as well as human-induced pluripotent stem cells (hiPSCs) and their derivatives in 3D. The materials reported here proved cytocompatible for these cell types with maintenance of hiPSCs in their undifferentiated state essential for their subsequent expansion or differentiation into a given cell type and potential for facile release by dilution due to their supramolecular nature.
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Affiliation(s)
- Ciqing Tong
- Department
of Supramolecular and Biomaterials Chemistry, Leiden Institute of
Chemistry, Leiden University, P.O. Box 9502, 2300 RA, Leiden, The Netherlands
| | - Tingxian Liu
- Department
of Supramolecular and Biomaterials Chemistry, Leiden Institute of
Chemistry, Leiden University, P.O. Box 9502, 2300 RA, Leiden, The Netherlands
| | - Victorio Saez Talens
- Department
of Supramolecular and Biomaterials Chemistry, Leiden Institute of
Chemistry, Leiden University, P.O. Box 9502, 2300 RA, Leiden, The Netherlands
| | - Willem E. M. Noteborn
- Department
of Supramolecular and Biomaterials Chemistry, Leiden Institute of
Chemistry, Leiden University, P.O. Box 9502, 2300 RA, Leiden, The Netherlands
| | - Thomas H. Sharp
- Department
of Molecular Cell Biology, Section Electron Microscopy, Leiden University Medical Center, 2300 RC, Leiden, The Netherlands
| | - Marco M. R. M. Hendrix
- Institute
for Complex Molecular Systems, Eindhoven
University of Technology, P.O. Box 513, 5600 MD, Eindhoven, The Netherlands
| | - Ilja K. Voets
- Institute
for Complex Molecular Systems, Eindhoven
University of Technology, P.O. Box 513, 5600 MD, Eindhoven, The Netherlands
| | - Christine L. Mummery
- Department
of Anatomy and Embryology, Leiden University
Medical Center, Leiden University, Einthovenweg 20, 2333 ZC, Leiden, The Netherlands
| | - Valeria V. Orlova
- Department
of Anatomy and Embryology, Leiden University
Medical Center, Leiden University, Einthovenweg 20, 2333 ZC, Leiden, The Netherlands
| | - Roxanne E. Kieltyka
- Department
of Supramolecular and Biomaterials Chemistry, Leiden Institute of
Chemistry, Leiden University, P.O. Box 9502, 2300 RA, Leiden, The Netherlands
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18
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Xue X, Wu J, Ricklin D, Forneris F, Di Crescenzio P, Schmidt CQ, Granneman J, Sharp TH, Lambris JD, Gros P. Regulator-dependent mechanisms of C3b processing by factor I allow differentiation of immune responses. Nat Struct Mol Biol 2017; 24:643-651. [PMID: 28671664 DOI: 10.1038/nsmb.3427] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 06/02/2017] [Indexed: 12/26/2022]
Abstract
The complement system labels microbes and host debris for clearance. Degradation of surface-bound C3b is pivotal to direct immune responses and protect host cells. How the serine protease factor I (FI), assisted by regulators, cleaves either two or three distant peptide bonds in the CUB domain of C3b remains unclear. We present a crystal structure of C3b in complex with FI and regulator factor H (FH; domains 1-4 with 19-20). FI binds C3b-FH between FH domains 2 and 3 and a reoriented C3b C-terminal domain and docks onto the first scissile bond, while stabilizing its catalytic domain for proteolytic activity. One cleavage in C3b does not affect its overall structure, whereas two cleavages unfold CUB and dislodge the thioester-containing domain (TED), affecting binding of regulators and thereby determining the number of cleavages. These data explain how FI generates late-stage opsonins iC3b or C3dg in a context-dependent manner, to react to foreign, danger or healthy self signals.
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Affiliation(s)
- Xiaoguang Xue
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Jin Wu
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Daniel Ricklin
- Department of Pathology &Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Federico Forneris
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Patrizia Di Crescenzio
- Department of Pathology &Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Christoph Q Schmidt
- Department of Pathology &Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Institute of Pharmacology of Natural Products and Clinical Pharmacology, Ulm University, Ulm, Germany
| | - Joke Granneman
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Thomas H Sharp
- Section Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - John D Lambris
- Department of Pathology &Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Piet Gros
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Utrecht, the Netherlands
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19
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Sharp TH, Koster AJ, Gros P. Imaging complement activation step-by-step on liposomes by phase-plate cryo-electron tomography. Immunobiology 2016. [DOI: 10.1016/j.imbio.2016.06.155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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20
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Sharp TH, Faas FGA, Koster AJ, Gros P. Imaging complement by phase-plate cryo-electron tomography from initiation to pore formation. J Struct Biol 2016; 197:155-162. [PMID: 27663685 DOI: 10.1016/j.jsb.2016.09.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [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: 05/24/2016] [Revised: 08/17/2016] [Accepted: 09/13/2016] [Indexed: 10/21/2022]
Abstract
Phase plates in cryo-electron tomography (cryoET) improve contrast, increasing the ability to discern separate molecules and molecular complexes in dense biomolecular environments. Here, we applied this new technology to the activation of the human complement system. Binding of C1 to antigen-antibody complexes initiates a cascade of proteolytic events that deposits molecules onto adjacent surfaces and terminates with the formation of membrane-attack-complex (MAC) pores in the targeted membranes. We imaged steps in this process using a Volta phase plate mounted on a Titan Krios equipped with a Falcon-II direct electron detector. The data show patches of single-layer antibodies on the surface and C1 bound to antibody platforms, with ca. ∼4% of instances where C1r and C1s proteases have dissociated from C1, and potentially instances of C1 transiently interacting with its substrate C4 or product C4b. Next, extensive deposition of C4b and C3b molecules is apparent, although individual molecules cannot always be properly distinguished with the current methods. Observations of MAC pores include formation of both single and composite pores, and instances of potential soluble-MAC dissociation upon failure of membrane insertion. Overall, application of the Volta phase plate cryoET markedly improved the contrast in the tomograms, which allowed for individual components to be more readily interpreted. However, variability in the phase shift induced by the phase-plate during the course of an experiment, together with incomplete sampling during tomogram acquisition, limited the interpretability of the resulting tomograms. Our studies exemplify the potential in studying molecular processes with complex spatial topologies by phase-plate cryoET.
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Affiliation(s)
- Thomas H Sharp
- Section Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands.
| | - Frank G A Faas
- Section Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
| | - Abraham J Koster
- Section Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands; NeCEN, Gorlaeus Laboratories, Leiden University, 2333 CC Leiden, The Netherlands
| | - Piet Gros
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
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21
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Sharp TH, Koster AJ, Gros P. Heterogeneous MAC Initiator and Pore Structures in a Lipid Bilayer by Phase-Plate Cryo-electron Tomography. Cell Rep 2016; 15:1-8. [PMID: 27052168 DOI: 10.1016/j.celrep.2016.03.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [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: 01/19/2016] [Revised: 02/09/2016] [Accepted: 02/24/2016] [Indexed: 02/07/2023] Open
Abstract
Pore formation in membranes is important for mammalian immune defense against invading bacteria. Induced by complement activation, the membrane attack complex (MAC) forms through sequential binding and membrane insertion of C5b6, C7, C8, and C9. Using cryo-electron tomography with a Volta phase plate and subtomogram averaging, we imaged C5b-7, C5b-8, and C5b-9 complexes and determined the C5b-9 pore structure in lipid bilayers. The in situ C5b-9 pore structure at 2.3-nm resolution reveals a 10- to 11.5-nm cone-shaped pore starting with C5b678 and multiple copies of C9 that is poorly closed, yielding a seam between C9 and C6 substituting for the shorter β strands in C6 and C7. However, large variations of composite pore complexes are apparent in subtomograms. Oligomerized initiator complexes C5b-7 and C5b-8 show stages of membrane binding, deformation, and perforation that yield ∼3.5-nm-wide pores. These data indicate a dynamic process of pore formation that likely adapts to biological membranes under attack.
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Affiliation(s)
- Thomas H Sharp
- Section Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, the Netherlands.
| | - Abraham J Koster
- Section Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, the Netherlands; NeCEN, Gorlaeus Laboratories, Leiden University, 2333 CC Leiden, the Netherlands
| | - Piet Gros
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research and Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands.
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22
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Mora NL, Bahreman A, Valkenier H, Li H, Sharp TH, Sheppard DN, Davis AP, Kros A. Targeted anion transporter delivery by coiled-coil driven membrane fusion. Chem Sci 2016; 7:1768-1772. [PMID: 28936326 PMCID: PMC5592372 DOI: 10.1039/c5sc04282h] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 01/06/2016] [Indexed: 01/11/2023] Open
Abstract
Synthetic anion transporters (anionophores) have potential as biomedical research tools and therapeutics. However, the efficient and specific delivery of these highly lipophilic molecules to a target cell membrane is non-trivial. Here, we investigate the delivery of a powerful anionophore to artificial and cell membranes using a coiled-coil-based delivery system inspired by SNARE membrane fusion proteins. Incorporation of complementary lipopeptides into the lipid membranes of liposomes and cell-sized giant unilamellar vesicles (GUVs) facilitated the delivery of a powerful anionophore into GUVs, where its anion transport activity was monitored in real time by fluorescence microscopy. Similar results were achieved using live cells engineered to express a halide-sensitive fluorophore. We conclude that coiled-coil driven membrane fusion is a highly efficient system to deliver anionophores to target cell membranes.
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Affiliation(s)
- Nestor Lopez Mora
- Leiden Institute of Chemistry , Leiden University , 2300 RA Leiden , The Netherlands .
| | - Azadeh Bahreman
- Leiden Institute of Chemistry , Leiden University , 2300 RA Leiden , The Netherlands .
| | - Hennie Valkenier
- School of Chemistry , University of Bristol Cantock's Close , Bristol BS8 1TS , UK .
| | - Hongyu Li
- School of Physiology, Pharmacology and Neuroscience , University of Bristol Biomedical Sciences Building , University Walk , Bristol BS8 1TD , UK
| | - Thomas H Sharp
- Department of Molecular Cell Biology , Section Electron Microscopy , Leiden University Medical Center , 2300 RC Leiden , The Netherlands
| | - David N Sheppard
- School of Physiology, Pharmacology and Neuroscience , University of Bristol Biomedical Sciences Building , University Walk , Bristol BS8 1TD , UK
| | - Anthony P Davis
- School of Chemistry , University of Bristol Cantock's Close , Bristol BS8 1TS , UK .
| | - Alexander Kros
- Leiden Institute of Chemistry , Leiden University , 2300 RA Leiden , The Netherlands .
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23
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Burgess NC, Sharp TH, Thomas F, Wood CW, Thomson AR, Zaccai NR, Brady RL, Serpell LC, Woolfson DN. Modular Design of Self-Assembling Peptide-Based Nanotubes. J Am Chem Soc 2015. [DOI: 10.1021/jacs.5b03973] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Natasha C. Burgess
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1TS, United Kingdom
- Bristol Centre
for Functional Nanomaterials, University of Bristol, Tyndall Avenue, Bristol, BS8 1FD, United Kingdom
| | - Thomas H. Sharp
- Section
Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Franziska Thomas
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1TS, United Kingdom
| | - Christopher W. Wood
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1TS, United Kingdom
- School
of Biochemistry, University of Bristol, Medical Sciences Building, University
Walk, Bristol, BS8 1TD, United Kingdom
| | - Andrew R. Thomson
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1TS, United Kingdom
| | - Nathan R. Zaccai
- School
of Biochemistry, University of Bristol, Medical Sciences Building, University
Walk, Bristol, BS8 1TD, United Kingdom
| | - R. Leo Brady
- School
of Biochemistry, University of Bristol, Medical Sciences Building, University
Walk, Bristol, BS8 1TD, United Kingdom
| | - Louise C. Serpell
- School
of Life Sciences, University of Sussex, Falmer, Brighton, East Sussex, BN1 9QG, United Kingdom
| | - Derek N. Woolfson
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1TS, United Kingdom
- School
of Biochemistry, University of Bristol, Medical Sciences Building, University
Walk, Bristol, BS8 1TD, United Kingdom
- BrisSynBio, University of Bristol, Life Sciences Building, Tyndall
Avenue, Bristol, BS8 1TQ, United Kingdom
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24
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Pronker MF, Bos TGAA, Sharp TH, Thies-Weesie DME, Janssen BJC. Olfactomedin-1 Has a V-shaped Disulfide-linked Tetrameric Structure. J Biol Chem 2015; 290:15092-101. [PMID: 25903135 PMCID: PMC4463452 DOI: 10.1074/jbc.m115.653485] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Indexed: 11/06/2022] Open
Abstract
Olfactomedin-1 (Olfm1; also known as noelin and pancortin) is a member of the olfactomedin domain-containing superfamily and a highly expressed neuronal glycoprotein important for nervous system development. It binds a number of secreted proteins and cell surface-bound receptors to induce cell signaling processes. Using a combined approach of x-ray crystallography, solution scattering, analytical ultracentrifugation, and electron microscopy we determined that full-length Olfm1 forms disulfide-linked tetramers with a distinctive V-shaped architecture. The base of the “V” is formed by two disulfide-linked dimeric N-terminal domains. Each of the two V legs consists of a parallel dimeric disulfide-linked coiled coil with a C-terminal β-propeller dimer at the tips. This agrees with our crystal structure of a C-terminal coiled-coil segment and β-propeller combination (Olfm1coil-Olf) that reveals a disulfide-linked dimeric arrangement with the β-propeller top faces in an outward exposed orientation. Similar to its family member myocilin, Olfm1 is stabilized by calcium. The dimer-of-dimers architecture suggests a role for Olfm1 in clustering receptors to regulate signaling and sheds light on the conformation of several other olfactomedin domain family members.
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Affiliation(s)
- Matti F Pronker
- From the Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research and
| | - Trusanne G A A Bos
- From the Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research and
| | - Thomas H Sharp
- Section Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
| | - Dominique M E Thies-Weesie
- Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute of Nanomaterials Science, Department of Chemistry, Faculty of Science, Utrecht University, 3584 CH Utrecht, The Netherlands and
| | - Bert J C Janssen
- From the Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research and
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25
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Fletcher JM, Harniman RL, Barnes FRH, Boyle AL, Collins A, Mantell J, Sharp TH, Antognozzi M, Booth PJ, Linden N, Miles MJ, Sessions RB, Verkade P, Woolfson DN. Self-assembling cages from coiled-coil peptide modules. Science 2013; 340:595-9. [PMID: 23579496 DOI: 10.1126/science.1233936] [Citation(s) in RCA: 388] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
An ability to mimic the boundaries of biological compartments would improve our understanding of self-assembly and provide routes to new materials for the delivery of drugs and biologicals and the development of protocells. We show that short designed peptides can be combined to form unilamellar spheres approximately 100 nanometers in diameter. The design comprises two, noncovalent, heterodimeric and homotrimeric coiled-coil bundles. These are joined back to back to render two complementary hubs, which when mixed form hexagonal networks that close to form cages. This design strategy offers control over chemistry, self-assembly, reversibility, and size of such particles.
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Affiliation(s)
- Jordan M Fletcher
- School of Chemistry, Cantock's Close, University of Bristol, Bristol BS8 1TS, UK
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26
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Corcionivoschi N, Alvarez LAJ, Sharp TH, Strengert M, Alemka A, Mantell J, Verkade P, Knaus UG, Bourke B. Mucosal reactive oxygen species decrease virulence by disrupting Campylobacter jejuni phosphotyrosine signaling. Cell Host Microbe 2013; 12:47-59. [PMID: 22817987 DOI: 10.1016/j.chom.2012.05.018] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2012] [Revised: 03/16/2012] [Accepted: 05/21/2012] [Indexed: 12/22/2022]
Abstract
Reactive oxygen species (ROS) play key roles in mucosal defense, yet how they are induced and the consequences for pathogens are unclear. We report that ROS generated by epithelial NADPH oxidases (Nox1/Duox2) during Campylobacter jejuni infection impair bacterial capsule formation and virulence by altering bacterial signal transduction. Upon C. jejuni invasion, ROS released from the intestinal mucosa inhibit the bacterial phosphotyrosine network that is regulated by the outer-membrane tyrosine kinase Cjtk (Cj1170/OMP50). ROS-mediated Cjtk inactivation results in an overall decrease in the phosphorylation of C. jejuni outer-membrane/periplasmic proteins, including UDP-GlcNAc/Glc 4-epimerase (Gne), an enzyme required for N-glycosylation and capsule formation. Cjtk positively regulates Gne by phosphorylating an active site tyrosine, while loss of Cjtk or ROS treatment inhibits Gne activity, causing altered polysaccharide synthesis. Thus, epithelial NADPH oxidases are an early antibacterial defense system in the intestinal mucosa that modifies virulence by disrupting bacterial signaling.
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Affiliation(s)
- Nicolae Corcionivoschi
- National Children's Research Centre, Our Lady's Children's Hospital Crumlin, Dublin, Ireland
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27
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Boyle AL, Bromley EHC, Bartlett GJ, Sessions RB, Sharp TH, Williams CL, Curmi PMG, Forde NR, Linke H, Woolfson DN. Squaring the circle in peptide assembly: from fibers to discrete nanostructures by de novo design. J Am Chem Soc 2012; 134:15457-67. [PMID: 22917063 DOI: 10.1021/ja3053943] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The design of bioinspired nanostructures and materials of defined size and shape is challenging as it pushes our understanding of biomolecular assembly to its limits. In such endeavors, DNA is the current building block of choice because of its predictable and programmable self-assembly. The use of peptide- and protein-based systems, however, has potential advantages due to their more-varied chemistries, structures and functions, and the prospects for recombinant production through gene synthesis and expression. Here, we present the design and characterization of two complementary peptides programmed to form a parallel heterodimeric coiled coil, which we use as the building blocks for larger, supramolecular assemblies. To achieve the latter, the two peptides are joined via peptidic linkers of variable lengths to produce a range of assemblies, from flexible fibers of indefinite length, through large colloidal-scale assemblies, down to closed and discrete nanoscale objects of defined stoichiometry. We posit that the different modes of assembly reflect the interplay between steric constraints imposed by short linkers and the bulk of the helices, and entropic factors that favor the formation of many smaller objects as the linker length is increased. This approach, and the resulting linear and proteinogenic polypeptides, represents a new route for constructing complex peptide-based assemblies and biomaterials.
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Affiliation(s)
- Aimee L Boyle
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
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28
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Abstract
Membrane traffic between organelles is essential for a multitude of processes that maintain cell homeostasis. Many steps in these tightly regulated trafficking pathways take place in microdomains on the membranes of organelles, which require analysis at nanometer resolution. Electron microscopy (EM) can visualize these processes in detail and is mainly responsible for our current view of morphology on the subcellular level. This review discusses how EM can be applied to solve many questions of intracellular membrane traffic, with a focus on the endosomal system. We describe the expansion of the technique from purely morphological analysis to cryo-immuno-EM, correlative light electron microscopy (CLEM), and 3D electron tomography. In this review we go into some technical details of these various techniques. Furthermore, we provide a full protocol for immunolabeling on Lowicryl sections of high-pressure frozen cells as well as a detailed description of a simple CLEM method that can be applied to answer many membrane trafficking questions. We believe that these EM-based techniques are important tools to expand our understanding of the molecular details of endosomal sorting and intracellular membrane traffic in general.
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Affiliation(s)
- Jan R T van Weering
- Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol BS81TD, United Kingdom
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29
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Easter A, Sharp TH, Valentin JP, Pollard CE. Pharmacological validation of a semi-automated in vitro hippocampal brain slice assay for assessment of seizure liability. J Pharmacol Toxicol Methods 2007; 56:223-33. [PMID: 17600733 DOI: 10.1016/j.vascn.2007.04.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2007] [Accepted: 04/16/2007] [Indexed: 12/22/2022]
Abstract
INTRODUCTION Drug-induced seizures are a serious, life-threatening adverse drug reaction (ADR) that can result in the failure of drugs to be licensed for clinical use or withdrawn from the market. Seizure liability of potential drugs is traditionally assessed using animal models run during the later phases of the drug discovery process. Given the low throughput, high animal usage and high compound requirement associated with these assays, it would be advantageous to identify higher throughput, in vitro models that could be used to give an earlier assessment of seizure liability. The hippocampal brain slice is one possibility but conventionally allows recording from only one slice at a time. The aim of this study was to validate a semi-automated system (Slicemaster, Scientifica UK Ltd) which allows concurrent electrophysiological recording from multiple brain slices. METHODS Conventional electrophysiological recording techniques were used to record electrically evoked synaptic activity from rat hippocampal brain slices. Population spikes (PS) were evoked at 30 s intervals by electrical stimulation of the Schaffer collateral pathway and were recorded using extracellular electrodes positioned in the CA1 cell body layer. Responses were quantified as PS areas (the area above and below the 0 mV line). The effects of eight validation compounds known to cause seizures in vivo and/or in the clinic were assessed. RESULTS Seven out of eight compounds evoked a concentration-dependent increase in population spike (PS) area that was statistically significant at higher concentrations (P<0.05; ANOVA). At the highest test concentration the percentage effects (mean+/-s.e.m.), relative to vehicle, were: picrotoxin 212.9+/-28.8, pentylenetrazole (PTZ) 181.4+/-24.7, 4-AP 328.9+/-48.6, aminophylline 124.5+/-5.9, chlorpromazine 122.1+/-9.8, SNC-80 132.1+/-12.6 and penicillin 174.7+/-14.1. Physostigmine had no significant effect on PS area although a concentration-dependent change in the morphology of the response was evident. DISCUSSION All validation compounds evoked a statistically significant effect on synaptic activity in the rat hippocampal slice. Although similar effects have been described previously, this is the first time that the effects of a pharmacologically diverse set of compounds have been assessed using a standardised brain slice assay. Given the low compound usage and relatively high throughput associated with this assay, the hippocampal brain slice assay may facilitate earlier testing of convulsant liability than is currently possible using in vivo models.
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Affiliation(s)
- A Easter
- Safety Assessment UK, AstraZeneca R&D Alderley Park, Macclesfield, SK10 4TG, UK.
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30
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Sharp TH, Crofts TH. Death with dignity: the physician's civil liability. Bayl Law Rev 1975; 27:86-108. [PMID: 11660890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/17/2023]
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