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Stempels FC, Janssens MH, Ter Beest M, Mesman RJ, Revelo NH, Ioannidis M, van den Bogaart G. Novel and conventional inhibitors of canonical autophagy differently affect LC3-associated phagocytosis. FEBS Lett 2022; 596:491-509. [PMID: 35007347 DOI: 10.1002/1873-3468.14280] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [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: 09/07/2021] [Revised: 12/06/2021] [Accepted: 12/23/2021] [Indexed: 11/09/2022]
Abstract
In autophagy, LC3-positive autophagophores fuse and encapsulate the autophagic cargo in a double-membrane structure. In contrast, lipidated LC3 (LC3-II) is directly formed at the phagosomal membrane in LC3-associated phagocytosis (LAP). In this study, we dissected the effects of autophagy inhibitors on LAP. SAR405, an inhibitor of VPS34, reduced levels of LC3-II and inhibited LAP. In contrast, the inhibitors of endosomal acidification bafilomycin A1 and chloroquine increased levels of LC3-II, due to reduced degradation in acidic lysosomes. However, while bafilomycin A1 inhibited LAP, chloroquine did not. Finally, EACC, which inhibits the fusion of autophagosomes with lysosomes, promoted LC3 degradation possibly by the proteasome. Targeting LAP with small molecule inhibitors is important given its emerging role in infectious and autoimmune diseases.
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Affiliation(s)
- Femmy C Stempels
- Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | - Maaike H Janssens
- Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | - Martin Ter Beest
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Rob J Mesman
- Department of Microbiology, RIBES, Faculty of Science, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Natalia H Revelo
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Melina Ioannidis
- Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | - Geert van den Bogaart
- Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands.,Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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2
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Muntjewerff EM, Meesters LD, van den Bogaart G, Revelo NH. Reverse Signaling by MHC-I Molecules in Immune and Non-Immune Cell Types. Front Immunol 2020; 11:605958. [PMID: 33384693 PMCID: PMC7770133 DOI: 10.3389/fimmu.2020.605958] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [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: 09/14/2020] [Accepted: 11/13/2020] [Indexed: 12/16/2022] Open
Abstract
Major histocompatibility complex (MHC) molecules are well-known for their role in antigen (cross-) presentation, thereby functioning as key players in the communication between immune cells, for example dendritic cells (DCs) and T cells, or immune cells and their targets, such as T cells and virus-infected or tumor cells. However, much less appreciated is the fact that MHC molecules can also act as signaling receptors. In this process, here referred to as reverse MHC class I (MHC-I) signaling, ligation of MHC molecules can lead to signal-transduction and cell regulatory effects in the antigen presenting cell. In the case of MHC-I, reverse signaling can have several outcomes, including apoptosis, migration, induced or reduced proliferation and cytotoxicity towards target cells. Here, we provide an overview of studies showing the signaling pathways and cell outcomes upon MHC-I stimulation in various immune and non-immune cells. Signaling molecules like RAC-alpha serine/threonine-protein kinase (Akt1), extracellular signal-regulated kinases 1/2 (ERK1/2), and nuclear factor-κB (NF-κB) were common signaling molecules activated upon MHC-I ligation in multiple cell types. For endothelial and smooth muscle cells, the in vivo relevance of reverse MHC-I signaling has been established, namely in the context of adverse effects after tissue transplantation. For other cell types, the role of reverse MHC-I signaling is less clear, since aspects like the in vivo relevance, natural MHC-I ligands and the extended downstream pathways are not fully known.The existing evidence, however, suggests that reverse MHC-I signaling is involved in the regulation of the defense against bacterial and viral infections and against malignancies. Thereby, reverse MHC-I signaling is a potential target for therapies against viral and bacterial infections, cancer immunotherapies and management of organ transplantation outcomes.
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Affiliation(s)
- Elke M Muntjewerff
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - Luca D Meesters
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - Geert van den Bogaart
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands.,Department of Molecular Microbiology and Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
| | - Natalia H Revelo
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
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3
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Revelo NH, ter Beest M, van den Bogaart G. Membrane trafficking as an active regulator of constitutively secreted cytokines. J Cell Sci 2019; 133:133/5/jcs234781. [DOI: 10.1242/jcs.234781] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 08/19/2019] [Indexed: 01/02/2023] Open
Abstract
ABSTRACT
Immune-cell activation by inflammatory stimuli triggers the transcription and translation of large amounts of cytokines. The transport of newly synthesized cytokines to the plasma membrane by vesicular trafficking can be rate-limiting for the production of these cytokines, and immune cells upregulate their exocytic machinery concomitantly with increased cytokine expression in order to cope with the increasing demand for trafficking. Whereas it is logical that trafficking is rate-limiting for regulated secretion where an intracellular pool of molecules is waiting to be released, the reason for this is not obvious for constitutively secreted cytokines, such as interleukin-6 (IL-6), interleukin-12 (IL-12) and tumor necrosis factor-α (TNF-α). These constitutively secreted cytokines are primarily regulated at the transcriptional and/or translational level but mounting evidence presented here shows that cells might also increase or decrease the rate of post-Golgi cytokine trafficking to modulate their production. Therefore, in this Hypothesis, we ask the question: why is there a need to limit the trafficking of constitutively secreted cytokines? We propose a model where cells monitor and adjust their production rate of cytokines by sensing the intracellular level of cytokines while they are in transit to the plasma membrane. This self-regulation of cytokine production could prevent an overshooting response of acute-phase cytokines, such as IL-6, IL-12 and TNF-α, upon acute infection.
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Affiliation(s)
- Natalia H. Revelo
- Tumor Immunology Lab, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, 6500HB Nijmegen, The Netherlands
| | - Martin ter Beest
- Tumor Immunology Lab, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, 6500HB Nijmegen, The Netherlands
| | - Geert van den Bogaart
- Tumor Immunology Lab, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, 6500HB Nijmegen, The Netherlands
- Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747AG Groningen, The Netherlands
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Verboogen DRJ, Revelo NH, ter Beest M, van den Bogaart G. Interleukin-6 secretion is limited by self-signaling in endosomes. J Mol Cell Biol 2019; 11:144-157. [PMID: 30016456 PMCID: PMC6392102 DOI: 10.1093/jmcb/mjy038] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [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: 12/04/2017] [Revised: 05/04/2018] [Accepted: 07/12/2018] [Indexed: 12/13/2022] Open
Abstract
Cells producing cytokines often express the receptor for the same cytokine, which makes them prone to autocrine signaling. How cytokine release and signaling are regulated in the same cell is not understood. In this study, we demonstrate that signaling by exogenous and self-synthesized inflammatory cytokine interleukin-6 (IL-6) within endosomal compartments acts as a cellular brake that limits the synthesis of IL-6. Our data show that IL-6 is internalized by dendritic cells and signals from endosomal compartments containing the IL-6 receptor. Newly synthesized IL-6 also traffics via these endosomal compartments and signals in transit to the plasma membrane. This allows activation of STAT3 which in turn limits toll-like receptor 4 stimulant lipopolysaccharide (LPS) triggered transcription of IL-6. Long-term exposure to LPS removes this brake via inhibition of STAT3 by increased expression of suppressor of cytokine signaling 3 and results in fully fledged IL-6 production. This transient regulation could prevent excessive IL-6 production during early infections.
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Affiliation(s)
- Daniëlle R J Verboogen
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Natalia H Revelo
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Martin ter Beest
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Geert van den Bogaart
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, Groningen, The Netherlands
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Abstract
The soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein family is of vital importance for organelle communication. The complexing of cognate SNARE members present in both the donor and target organellar membranes drives the membrane fusion required for intracellular transport. In the endocytic route, SNARE proteins mediate trafficking between endosomes and phagosomes with other endosomes, lysosomes, the Golgi apparatus, the plasma membrane, and the endoplasmic reticulum. The goal of this review is to provide an overview of the SNAREs involved in endosomal and phagosomal trafficking. Of the 38 SNAREs present in humans, 30 have been identified at endosomes and/or phagosomes. Many of these SNAREs are targeted by viruses and intracellular pathogens, which thereby reroute intracellular transport for gaining access to nutrients, preventing their degradation, and avoiding their detection by the immune system. A fascinating picture is emerging of a complex transport network with multiple SNAREs being involved in consecutive trafficking routes.
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Affiliation(s)
- Ilse Dingjan
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; and Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen , Groningen , The Netherlands
| | - Peter T A Linders
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; and Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen , Groningen , The Netherlands
| | - Danielle R J Verboogen
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; and Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen , Groningen , The Netherlands
| | - Natalia H Revelo
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; and Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen , Groningen , The Netherlands
| | - Martin Ter Beest
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; and Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen , Groningen , The Netherlands
| | - Geert van den Bogaart
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; and Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen , Groningen , The Netherlands
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Abstract
We recently identified a key role for SWAP70 as the tethering factor stabilizing F-actin filaments on the surface of phagosomes in human dendritic cells by interacting both with Rho-family GTPases and the lipid phosphatidylinositol (3,4)-bisphosphate. In this study, we aimed to investigate whether this role of SWAP70 was general among immune phagocytes. Our data reveal that SWAP70 is recruited to early phagosomes of macrophages and dendritic cells from both human and mouse. The putative inhibitor of SWAP70 sanguinarine blocked phagocytosis and F-actin polymerization, supporting a key role for SWAP70 in phagocytosis as demonstrated previously with knock-down. Moreover, SWAP70 was recently shown to sequester the F-actin severing protein cofilin and we investigated this relationship in phagocytosis. Our data show an increased activation of cellular cofilin upon siRNA knockdown of SWAP70. Finally, we explored whether SWAP70 would be recruited to the immune synapse between dendritic cells and T cells required for antigen presentation, as the formation of such synapses depends on F-actin. However, we observed that SWAP70 was depleted at immune synapses and specifically was recruited to phagosomes. Our data support an essential and specific role for SWAP70 in tethering and stabilizing F-actin to the phagosomal surface in a wide range of phagocytes.
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Affiliation(s)
- Maksim V Baranov
- a Department of Tumor Immunology , Radboud University Medical Center, Radboud Institute for Molecular Life Sciences , Nijmegen , The Netherlands
| | - Natalia H Revelo
- a Department of Tumor Immunology , Radboud University Medical Center, Radboud Institute for Molecular Life Sciences , Nijmegen , The Netherlands
| | - Daniëlle R J Verboogen
- a Department of Tumor Immunology , Radboud University Medical Center, Radboud Institute for Molecular Life Sciences , Nijmegen , The Netherlands
| | - Martin Ter Beest
- a Department of Tumor Immunology , Radboud University Medical Center, Radboud Institute for Molecular Life Sciences , Nijmegen , The Netherlands
| | - Geert van den Bogaart
- a Department of Tumor Immunology , Radboud University Medical Center, Radboud Institute for Molecular Life Sciences , Nijmegen , The Netherlands
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7
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Richter KN, Revelo NH, Seitz KJ, Helm MS, Sarkar D, Saleeb RS, D'Este E, Eberle J, Wagner E, Vogl C, Lazaro DF, Richter F, Coy-Vergara J, Coceano G, Boyden ES, Duncan RR, Hell SW, Lauterbach MA, Lehnart SE, Moser T, Outeiro TF, Rehling P, Schwappach B, Testa I, Zapiec B, Rizzoli SO. Glyoxal as an alternative fixative to formaldehyde in immunostaining and super-resolution microscopy. EMBO J 2018; 37:139-159. [PMID: 29146773 PMCID: PMC5753035 DOI: 10.15252/embj.201695709] [Citation(s) in RCA: 149] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 09/25/2017] [Accepted: 10/06/2017] [Indexed: 12/02/2022] Open
Abstract
Paraformaldehyde (PFA) is the most commonly used fixative for immunostaining of cells, but has been associated with various problems, ranging from loss of antigenicity to changes in morphology during fixation. We show here that the small dialdehyde glyoxal can successfully replace PFA Despite being less toxic than PFA, and, as most aldehydes, likely usable as a fixative, glyoxal has not yet been systematically tried in modern fluorescence microscopy. Here, we tested and optimized glyoxal fixation and surprisingly found it to be more efficient than PFA-based protocols. Glyoxal acted faster than PFA, cross-linked proteins more effectively, and improved the preservation of cellular morphology. We validated glyoxal fixation in multiple laboratories against different PFA-based protocols and confirmed that it enabled better immunostainings for a majority of the targets. Our data therefore support that glyoxal can be a valuable alternative to PFA for immunostaining.
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Affiliation(s)
- Katharina N Richter
- Department of Neuro- and Sensory Physiology, University of Göttingen Medical Center, Göttingen, Germany
- Cluster of Excellence Nanoscale Microscopy and Molecular Physiology of the Brain, Göttingen, Germany
| | - Natalia H Revelo
- Department of Neuro- and Sensory Physiology, University of Göttingen Medical Center, Göttingen, Germany
| | - Katharina J Seitz
- Department of Neuro- and Sensory Physiology, University of Göttingen Medical Center, Göttingen, Germany
- International Max Planck Research School Molecular Biology, Göttingen, Germany
| | - Martin S Helm
- Department of Neuro- and Sensory Physiology, University of Göttingen Medical Center, Göttingen, Germany
- International Max Planck Research School Molecular Biology, Göttingen, Germany
| | | | - Rebecca S Saleeb
- Edinburgh Super-Resolution Imaging Consortium, Institute of Biological Chemistry, Biophysics, and Bioengineering, Heriot-Watt University, Edinburgh, UK
| | - Elisa D'Este
- Department of NanoBiophotonics, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
| | - Jessica Eberle
- Department of Neural Systems, Max-Planck-Institute for Brain Research, Frankfurt am Main, Germany
| | - Eva Wagner
- Heart Research Center Göttingen, Department of Cardiology & Pulmonology, University Medical Center Göttingen, Göttingen, Germany
- German Center for Cardiovascular Research (DZHK) Site Göttingen
| | - Christian Vogl
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Max-Planck-Institute for Experimental Medicine, Auditory Neuroscience Group, Göttingen, Germany
| | - Diana F Lazaro
- Department of Experimental Neurodegeneration, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Center for Biostructural Imaging of Neurodegeneration University Medical Center Göttingen, Göttingen, Germany
- Max-Planck-Institute for Experimental Medicine, Göttingen, Germany
| | - Frank Richter
- International Max Planck Research School Molecular Biology, Göttingen, Germany
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Javier Coy-Vergara
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
| | - Giovanna Coceano
- Department of Applied Physics and Science for Life Laboratory, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Edward S Boyden
- Departments of Brain and Cognitive Science and Biological Engineering, MIT Media Lab and McGovern Institute, Cambridge, MA, USA
| | - Rory R Duncan
- Edinburgh Super-Resolution Imaging Consortium, Institute of Biological Chemistry, Biophysics, and Bioengineering, Heriot-Watt University, Edinburgh, UK
| | - Stefan W Hell
- Department of NanoBiophotonics, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
| | - Marcel A Lauterbach
- Department of Neural Systems, Max-Planck-Institute for Brain Research, Frankfurt am Main, Germany
| | - Stephan E Lehnart
- Heart Research Center Göttingen, Department of Cardiology & Pulmonology, University Medical Center Göttingen, Göttingen, Germany
- German Center for Cardiovascular Research (DZHK) Site Göttingen
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Max-Planck-Institute for Experimental Medicine, Auditory Neuroscience Group, Göttingen, Germany
| | - Tiago F Outeiro
- Department of Experimental Neurodegeneration, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Center for Biostructural Imaging of Neurodegeneration University Medical Center Göttingen, Göttingen, Germany
- Max-Planck-Institute for Experimental Medicine, Göttingen, Germany
| | - Peter Rehling
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
- Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
| | - Blanche Schwappach
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
| | - Ilaria Testa
- Department of Applied Physics and Science for Life Laboratory, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Bolek Zapiec
- Max Planck Research Unit for Neurogenetics, Frankfurt am Main, Germany
| | - Silvio O Rizzoli
- Department of Neuro- and Sensory Physiology, University of Göttingen Medical Center, Göttingen, Germany
- Cluster of Excellence Nanoscale Microscopy and Molecular Physiology of the Brain, Göttingen, Germany
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8
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Baranov MV, Revelo NH, Dingjan I, Maraspini R, Ter Beest M, Honigmann A, van den Bogaart G. SWAP70 Organizes the Actin Cytoskeleton and Is Essential for Phagocytosis. Cell Rep 2017; 17:1518-1531. [PMID: 27806292 PMCID: PMC5149533 DOI: 10.1016/j.celrep.2016.10.021] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [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: 04/25/2016] [Revised: 09/05/2016] [Accepted: 10/06/2016] [Indexed: 10/25/2022] Open
Abstract
Actin plays a critical role during the early stages of pathogenic microbe internalization by immune cells. In this study, we identified a key mechanism of actin filament tethering and stabilization to the surface of phagosomes in human dendritic cells. We found that the actin-binding protein SWAP70 is specifically recruited to nascent phagosomes by binding to the lipid phosphatidylinositol (3,4)-bisphosphate. Multi-color super-resolution stimulated emission depletion (STED) microscopy revealed that the actin cage surrounding early phagosomes is formed by multiple concentric rings containing SWAP70. SWAP70 colocalized with and stimulated activation of RAC1, a known activator of actin polymerization, on phagosomes. Genetic ablation of SWAP70 impaired actin polymerization around phagosomes and resulted in a phagocytic defect. These data show a key role for SWAP70 as a scaffold for tethering the peripheral actin cage to phagosomes.
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Affiliation(s)
- Maksim V Baranov
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands
| | - Natalia H Revelo
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands
| | - Ilse Dingjan
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands
| | - Riccardo Maraspini
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Martin Ter Beest
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands
| | - Alf Honigmann
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Geert van den Bogaart
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands.
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9
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Dingjan I, Verboogen DR, Paardekooper LM, Revelo NH, Sittig SP, Visser LJ, Mollard GFV, Henriet SS, Figdor CG, Ter Beest M, van den Bogaart G. Lipid peroxidation causes endosomal antigen release for cross-presentation. Sci Rep 2016; 6:22064. [PMID: 26907999 PMCID: PMC4764948 DOI: 10.1038/srep22064] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [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: 07/09/2015] [Accepted: 02/05/2016] [Indexed: 02/07/2023] Open
Abstract
Dendritic cells (DCs) present foreign antigen in major histocompatibility complex (MHC) class I molecules to cytotoxic T cells in a process called cross-presentation. An important step in this process is the release of antigen from the lumen of endosomes into the cytosol, but the mechanism of this step is still unclear. In this study, we show that reactive oxygen species (ROS) produced by the NADPH-oxidase complex NOX2 cause lipid peroxidation, a membrane disrupting chain-reaction, which in turn results in antigen leakage from endosomes. Antigen leakage and cross-presentation were inhibited by blocking ROS production or scavenging radicals and induced when using a ROS-generating photosensitizer. Endosomal antigen release was impaired in DCs from chronic granulomatous disease (CGD) patients with dysfunctional NOX2. Thus, NOX2 induces antigen release from endosomes for cross-presentation by direct oxidation of endosomal lipids. This constitutes a new cellular function for ROS in regulating immune responses against pathogens and cancer.
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Affiliation(s)
- Ilse Dingjan
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, 6525 GA, the Netherlands
| | - Daniëlle Rj Verboogen
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, 6525 GA, the Netherlands
| | - Laurent M Paardekooper
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, 6525 GA, the Netherlands
| | - Natalia H Revelo
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, 6525 GA, the Netherlands
| | - Simone P Sittig
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, 6525 GA, the Netherlands
| | - Linda J Visser
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, 6525 GA, the Netherlands
| | | | - Stefanie Sv Henriet
- Department of Pediatrics, Radboud University Medical Center, Nijmegen, 6525 GA, the Netherlands
| | - Carl G Figdor
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, 6525 GA, the Netherlands
| | - Martin Ter Beest
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, 6525 GA, the Netherlands
| | - Geert van den Bogaart
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, 6525 GA, the Netherlands
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10
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Verboogen DR, Dingjan I, Revelo NH, Visser LJ, ter Beest M, van den Bogaart G. The dendritic cell side of the immunological synapse. Biomol Concepts 2016; 7:17-28. [DOI: 10.1515/bmc-2015-0028] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 11/18/2015] [Indexed: 12/19/2022] Open
Abstract
AbstractImmune responses are initiated by the interactions between antigen-presenting cells (APCs), such as dendritic cells (DCs), with responder cells, such as T cells, via a tight cellular contact interface called the immunological synapse. The immunological synapse is a highly organized subcellular structure that provides a platform for the presentation of antigen in major histocompatibility class I and II complexes (MHC class I and II) on the surface of the APC to receptors on the surface of the responder cells. In T cells, these contacts lead to highly polarized membrane trafficking that results in the local release of lytic granules and in the delivery and recycling of T cell receptors at the immunological synapse. Localized trafficking also occurs at the APC side of the immunological synapse, especially in DCs where antigen loaded in MHC class I and II is presented and cytokines are released specifically at the synapse. Whereas the molecular mechanisms underlying polarized membrane trafficking at the T cell side of the immunological synapse are increasingly well understood, these are still very unclear at the APC side. In this review, we discuss the organization of the APC side of the immunological synapse. We focus on the directional trafficking and release of membrane vesicles carrying MHC molecules and cytokines at the immunological synapses of DCs. We hypothesize that the specific delivery of MHC and the release of cytokines at the immunological synapse mechanistically resemble that of lytic granule release from T cells.
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Affiliation(s)
- Danielle R.J. Verboogen
- 1Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands
| | - Ilse Dingjan
- 1Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands
| | - Natalia H. Revelo
- 1Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands
| | - Linda J. Visser
- 1Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands
| | - Martin ter Beest
- 1Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands
| | - Geert van den Bogaart
- 1Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands
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11
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Abstract
mCLING is a fixable endocytosis marker that can be combined with immunolabeling techniques to study the molecular composition of trafficking organelles. mCLING can be used both in cultured cells and in tissue if critical sample preparation steps, such as fixation, are correctly performed. This unit describes protocols for the application of mCLING and for the subsequent sample processing. We include immunostaining protocols and embedding procedures for confocal and high-resolution microscopy.
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Affiliation(s)
- Natalia H Revelo
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen.,Department of Tumor Immunology, Institute for Molecular Life Sciences, Radboud University Medical Center
| | - Silvio O Rizzoli
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen
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12
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Jung S, Maritzen T, Wichmann C, Jing Z, Neef A, Revelo NH, Al-Moyed H, Meese S, Wojcik SM, Panou I, Bulut H, Schu P, Ficner R, Reisinger E, Rizzoli SO, Neef J, Strenzke N, Haucke V, Moser T. Disruption of adaptor protein 2μ (AP-2μ) in cochlear hair cells impairs vesicle reloading of synaptic release sites and hearing. EMBO J 2015; 34:2686-702. [PMID: 26446278 DOI: 10.15252/embj.201591885] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [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: 04/24/2015] [Accepted: 09/04/2015] [Indexed: 11/09/2022] Open
Abstract
Active zones (AZs) of inner hair cells (IHCs) indefatigably release hundreds of vesicles per second, requiring each release site to reload vesicles at tens per second. Here, we report that the endocytic adaptor protein 2μ (AP-2μ) is required for release site replenishment and hearing. We show that hair cell-specific disruption of AP-2μ slows IHC exocytosis immediately after fusion of the readily releasable pool of vesicles, despite normal abundance of membrane-proximal vesicles and intact endocytic membrane retrieval. Sound-driven postsynaptic spiking was reduced in a use-dependent manner, and the altered interspike interval statistics suggested a slowed reloading of release sites. Sustained strong stimulation led to accumulation of endosome-like vacuoles, fewer clathrin-coated endocytic intermediates, and vesicle depletion of the membrane-distal synaptic ribbon in AP-2μ-deficient IHCs, indicating a further role of AP-2μ in clathrin-dependent vesicle reformation on a timescale of many seconds. Finally, we show that AP-2 sorts its IHC-cargo otoferlin. We propose that binding of AP-2 to otoferlin facilitates replenishment of release sites, for example, via speeding AZ clearance of exocytosed material, in addition to a role of AP-2 in synaptic vesicle reformation.
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Affiliation(s)
- SangYong Jung
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany Collaborative Research Center 889, University of Göttingen, Göttingen, Germany Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Tanja Maritzen
- Leibniz Institut für Molekulare Pharmakologie (FMP), Berlin, Germany NeuroCure Cluster of Excellence & Collaborative Research Center 958, Freie Universität Berlin, Berlin, Germany
| | - Carolin Wichmann
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Zhizi Jing
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany Auditory Systems Physiology Group, InnerEarLab, Department of Otolaryngology, University Medical Center Göttingen, Göttingen, Germany
| | - Andreas Neef
- Bernstein Group Biophysics of Neural Computation, Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany
| | - Natalia H Revelo
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Göttingen, Germany
| | - Hanan Al-Moyed
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Sandra Meese
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany Department of Molecular Structural Biology, Institute for Microbiology and Genetics, University of Göttingen, Göttingen, Germany
| | - Sonja M Wojcik
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Iliana Panou
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
| | - Haydar Bulut
- Leibniz Institut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Peter Schu
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Ralf Ficner
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany Department of Molecular Structural Biology, Institute for Microbiology and Genetics, University of Göttingen, Göttingen, Germany
| | - Ellen Reisinger
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany Molecular Biology of Cochlear Neurotransmission Group, InnerEarLab, Department of Otolaryngology, University Medical Center Göttingen, Göttingen, Germany
| | - Silvio O Rizzoli
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Göttingen, Germany Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, Göttingen, Germany
| | - Jakob Neef
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany Collaborative Research Center 889, University of Göttingen, Göttingen, Germany Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Nicola Strenzke
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany Auditory Systems Physiology Group, InnerEarLab, Department of Otolaryngology, University Medical Center Göttingen, Göttingen, Germany
| | - Volker Haucke
- Leibniz Institut für Molekulare Pharmakologie (FMP), Berlin, Germany NeuroCure Cluster of Excellence & Collaborative Research Center 958, Freie Universität Berlin, Berlin, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany Collaborative Research Center 889, University of Göttingen, Göttingen, Germany Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, Göttingen, Germany
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13
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Abstract
The increasing interest in "seeing" the molecular environment in biological systems has led to the recent quest for breaking the diffraction barrier in far-field fluorescence microscopy. The first nanoscopy method successfully applied to conventional biological probes was stimulated emission depletion microscopy (STED). It is based on a physical principle that instantly delivers diffraction-unlimited images, with no need for further computational processing: the excitation laser beam is overlaid with a doughnut-shaped depleting beam that switches off previously excited fluorophores, thereby resulting in what is effectively a smaller imaging volume. In this chapter we give an overview of several applications of STED microscopy to biological questions. We explain technical aspects of sample preparation and image acquisition that will help in obtaining good diffraction-unlimited pictures. We also present embedding techniques adapted for ultrathin sectioning, which allow optimal 3D resolutions in virtually all biological preparations.
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Affiliation(s)
- Natalia H Revelo
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Humboldtallee 23, Göttingen, Germany,
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14
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Pech U, Revelo NH, Seitz KJ, Rizzoli SO, Fiala A. Optical dissection of experience-dependent pre- and postsynaptic plasticity in the Drosophila brain. Cell Rep 2015; 10:2083-95. [PMID: 25818295 DOI: 10.1016/j.celrep.2015.02.065] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 01/24/2015] [Accepted: 02/26/2015] [Indexed: 01/18/2023] Open
Abstract
Drosophila represents a key model organism for dissecting neuronal circuits that underlie innate and adaptive behavior. However, this task is limited by a lack of tools to monitor physiological parameters of spatially distributed, central synapses in identified neurons. We generated transgenic fly strains that express functional fluorescent reporters targeted to either pre- or postsynaptic compartments. Presynaptic Ca(2+) dynamics are monitored using synaptophysin-coupled GCaMP3, synaptic transmission is monitored using red fluorescent synaptophysin-pHTomato, and postsynaptic Ca(2+) dynamics are visualized using GCaMP3 fused with the postsynaptic matrix protein, dHomer. Using two-photon in vivo imaging of olfactory projection neurons, odor-evoked activity across populations of synapses is visualized in the antennal lobe and the mushroom body calyx. Prolonged odor exposure causes odor-specific and differential experience-dependent changes in pre- and postsynaptic activity at both levels of olfactory processing. The approach advances the physiological analysis of synaptic connections across defined groups of neurons in intact Drosophila.
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Affiliation(s)
- Ulrike Pech
- Department of Molecular Neurobiology of Behavior, Johann-Friedrich-Blumenbach-Institute for Zoology and Anthropology, Georg-August-University Göttingen, Julia-Lermontowa-Weg 3, 37077 Göttingen, Germany
| | - Natalia H Revelo
- Department of Neuro- and Sensory Physiology, University of Göttingen Medical Center, Humboldtallee 23, 37073 Göttingen, Germany
| | - Katharina J Seitz
- Department of Neuro- and Sensory Physiology, University of Göttingen Medical Center, Humboldtallee 23, 37073 Göttingen, Germany
| | - Silvio O Rizzoli
- Department of Neuro- and Sensory Physiology, University of Göttingen Medical Center, Humboldtallee 23, 37073 Göttingen, Germany
| | - André Fiala
- Department of Molecular Neurobiology of Behavior, Johann-Friedrich-Blumenbach-Institute for Zoology and Anthropology, Georg-August-University Göttingen, Julia-Lermontowa-Weg 3, 37077 Göttingen, Germany.
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15
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Revelo NH, Kamin D, Truckenbrodt S, Wong AB, Reuter-Jessen K, Reisinger E, Moser T, Rizzoli SO. A new probe for super-resolution imaging of membranes elucidates trafficking pathways. ACTA ACUST UNITED AC 2014; 205:591-606. [PMID: 24862576 PMCID: PMC4033769 DOI: 10.1083/jcb.201402066] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [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] [Indexed: 11/22/2022]
Abstract
mCLING is a novel membrane probe for the study of membrane trafficking with demonstrated value in both live and fixed cells across a wide range of biological systems. The molecular composition of the organelles involved in membrane recycling is difficult to establish as a result of the absence of suitable labeling tools. We introduce in this paper a novel probe, named membrane-binding fluorophore-cysteine-lysine-palmitoyl group (mCLING), which labels the plasma membrane and is taken up during endocytosis. It remains attached to membranes after fixation and permeabilization and can therefore be used in combination with immunostaining and super-resolution microscopy. We applied mCLING to mammalian-cultured cells, yeast, bacteria, primary cultured neurons, Drosophila melanogaster larval neuromuscular junctions, and mammalian tissue. mCLING enabled us to study the molecular composition of different trafficking organelles. We used it to address several questions related to synaptic vesicle recycling in the auditory inner hair cells from the organ of Corti and to investigate molecular differences between synaptic vesicles that recycle actively or spontaneously in cultured neurons. We conclude that mCLING enables the investigation of trafficking membranes in a broad range of preparations.
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Affiliation(s)
- Natalia H Revelo
- Department of Neuro- and Sensory Physiology; European Neuroscience Institute; and InnerEarLab and Molecular Biology of Cochlear Neurotransmission Group, Department of Otolaryngology; University Medical Center Göttingen, 37099 Göttingen, GermanyDepartment of Neuro- and Sensory Physiology; European Neuroscience Institute; and InnerEarLab and Molecular Biology of Cochlear Neurotransmission Group, Department of Otolaryngology; University Medical Center Göttingen, 37099 Göttingen, Germany International Max Planck Research School for Neurosciences, 37077 Göttingen, Germany Collaborative Research Center 889 and Cluster of Excellence Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, 37099 Göttingen, Germany
| | - Dirk Kamin
- Department of Neuro- and Sensory Physiology; European Neuroscience Institute; and InnerEarLab and Molecular Biology of Cochlear Neurotransmission Group, Department of Otolaryngology; University Medical Center Göttingen, 37099 Göttingen, GermanyDepartment of Neuro- and Sensory Physiology; European Neuroscience Institute; and InnerEarLab and Molecular Biology of Cochlear Neurotransmission Group, Department of Otolaryngology; University Medical Center Göttingen, 37099 Göttingen, Germany
| | - Sven Truckenbrodt
- Department of Neuro- and Sensory Physiology; European Neuroscience Institute; and InnerEarLab and Molecular Biology of Cochlear Neurotransmission Group, Department of Otolaryngology; University Medical Center Göttingen, 37099 Göttingen, GermanyDepartment of Neuro- and Sensory Physiology; European Neuroscience Institute; and InnerEarLab and Molecular Biology of Cochlear Neurotransmission Group, Department of Otolaryngology; University Medical Center Göttingen, 37099 Göttingen, Germany International Max Planck Research School for Molecular Biology, 37077 Göttingen, Germany
| | - Aaron B Wong
- Department of Neuro- and Sensory Physiology; European Neuroscience Institute; and InnerEarLab and Molecular Biology of Cochlear Neurotransmission Group, Department of Otolaryngology; University Medical Center Göttingen, 37099 Göttingen, Germany International Max Planck Research School for Neurosciences, 37077 Göttingen, Germany Collaborative Research Center 889 and Cluster of Excellence Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, 37099 Göttingen, Germany
| | - Kirsten Reuter-Jessen
- Department of Neuro- and Sensory Physiology; European Neuroscience Institute; and InnerEarLab and Molecular Biology of Cochlear Neurotransmission Group, Department of Otolaryngology; University Medical Center Göttingen, 37099 Göttingen, Germany Collaborative Research Center 889 and Cluster of Excellence Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, 37099 Göttingen, Germany
| | - Ellen Reisinger
- Department of Neuro- and Sensory Physiology; European Neuroscience Institute; and InnerEarLab and Molecular Biology of Cochlear Neurotransmission Group, Department of Otolaryngology; University Medical Center Göttingen, 37099 Göttingen, Germany Collaborative Research Center 889 and Cluster of Excellence Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, 37099 Göttingen, Germany
| | - Tobias Moser
- Department of Neuro- and Sensory Physiology; European Neuroscience Institute; and InnerEarLab and Molecular Biology of Cochlear Neurotransmission Group, Department of Otolaryngology; University Medical Center Göttingen, 37099 Göttingen, Germany Collaborative Research Center 889 and Cluster of Excellence Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, 37099 Göttingen, Germany Collaborative Research Center 889 and Cluster of Excellence Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, 37099 Göttingen, Germany
| | - Silvio O Rizzoli
- Department of Neuro- and Sensory Physiology; European Neuroscience Institute; and InnerEarLab and Molecular Biology of Cochlear Neurotransmission Group, Department of Otolaryngology; University Medical Center Göttingen, 37099 Göttingen, GermanyDepartment of Neuro- and Sensory Physiology; European Neuroscience Institute; and InnerEarLab and Molecular Biology of Cochlear Neurotransmission Group, Department of Otolaryngology; University Medical Center Göttingen, 37099 Göttingen, Germany Collaborative Research Center 889 and Cluster of Excellence Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, 37099 Göttingen, Germany Collaborative Research Center 889 and Cluster of Excellence Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, 37099 Göttingen, Germany
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16
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Abstract
Styryl (FM) dyes have been used for more than two decades to investigate exo- and endocytosis in conventional synapses. However, they are difficult to use in the inner hair cells of the auditory pathway (IHCs), as FM dyes appear to penetrate through mechanotransducer channels into the cytosol of IHCs, masking endocytotic uptake. To solve this problem we applied to IHCs the FM dye photo-oxidation technique, which renders the dyes into electron microscopy markers. Photo-oxidation allowed the unambiguous identification of labeled organelles, despite the presence of FM dye in the cytosol. This enabled us to describe the morphologies of several organelles that take up membrane in IHCs, both at rest and during stimulation. At rest, endosome-like organelles were detected in the region of the cuticular plate. Larger tubulo-cisternal organelles dominated the top and nuclear regions. Finally, the basal region, where the IHC active zones are located, contained few labeled organelles. Stimulation increased significantly membrane trafficking in the basal region, inducing the appearance of labeled vesicles and cistern-like organelles. The latter were replaced by small, synaptic-like vesicles during recovery after stimulation. In contrast, no changes in membrane trafficking were induced by stimulation in the cuticular plate region or in the top and nuclear regions. We conclude that synaptic vesicle recycling takes place mostly in the basal region of the IHCs. Other organelles participate in abundant constitutive membrane trafficking throughout the rest of the IHC volume.
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Affiliation(s)
- Dirk Kamin
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Göttingen, Germany
- STED Microscopy of Synaptic Function, European Neuroscience Institute, Göttingen, Germany
- * E-mail: (SOR); (DK)
| | - Natalia H. Revelo
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Göttingen, Germany
- STED Microscopy of Synaptic Function, European Neuroscience Institute, Göttingen, Germany
- International Max Planck Research School Neurosciences, Göttingen, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
| | - Silvio O. Rizzoli
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Göttingen, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Cluster of Excellence Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, Göttingen, Germany
- * E-mail: (SOR); (DK)
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17
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Regen T, van Rossum D, Scheffel J, Kastriti ME, Revelo NH, Prinz M, Brück W, Hanisch UK. CD14 and TRIF govern distinct responsiveness and responses in mouse microglial TLR4 challenges by structural variants of LPS. Brain Behav Immun 2011; 25:957-70. [PMID: 20951794 DOI: 10.1016/j.bbi.2010.10.009] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Revised: 10/06/2010] [Accepted: 10/08/2010] [Indexed: 12/23/2022] Open
Abstract
Toll-like receptor (TLR) 4 responds to a range of agonists in infection and injury, but is best known for the recognition of bacterial lipopolysaccharides (LPS). Assembly in heterologous receptor complexes as well as signaling through both MyD88 and TRIF adaptor proteins, as unmatched by other TLRs, could underlie its versatile response options, probably also in a cell type-dependent manner. We show that microglia, the CNS macrophages, react to diverse LPS variants, including smooth (S) and rough (R) LPS chemotypes, with cytokine/chemokine induction, MHC I expression and suppression of myelin phagocytosis. The TLR4 co-receptor CD14 was shown in peritoneal macrophages to be essential for S-LPS effects and the link of both S- and R-LPS to TRIF signaling. In contrast, cd14(-/-) microglia readily respond to S- and R-LPS, suggesting an a priori high(er) sensitivity to both chemotypes, while CD14 confers increased S- and R-LPS potencies and compensates for their differences. Importantly, CD14 controls the magnitude and shapes the profile of cyto/chemokine production, this influence being itself regulated by critical LPS concentrations. Comparing reactive phenotypes of microglia with deficiencies in CD14, MyD88 and TRIF (cd14(-/-), myd88(-/-), and trif(lps2)), we found that distinct signaling routes organize for individual functions in either concerted or non-redundant fashion and that CD14 has contributions beyond the link to TRIF. Modulation of response profiles by key cytokines finally reveals that the microglial TLR4 can differentiate between the class of LPS structures and a self-derived agonist, fibronectin. It thus proves as a sophisticated decision maker in infectious and non-infectious CNS challenges.
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Affiliation(s)
- Tommy Regen
- Institute of Neuropathology, University of Göttingen, Germany
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