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David S, Pinter K, Nguyen KK, Lee DS, Lei Z, Sokolova Y, Sheets L, Kindt KS. Kif1a and intact microtubules maintain synaptic-vesicle populations at ribbon synapses in zebrafish hair cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.20.595037. [PMID: 38903095 PMCID: PMC11188139 DOI: 10.1101/2024.05.20.595037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/22/2024]
Abstract
Sensory hair cells of the inner ear utilize specialized ribbon synapses to transmit sensory stimuli to the central nervous system. This sensory transmission necessitates rapid and sustained neurotransmitter release, which relies on a large pool of synaptic vesicles at the hair-cell presynapse. Work in neurons has shown that kinesin motor proteins traffic synaptic material along microtubules to the presynapse, but how new synaptic material reaches the presynapse in hair cells is not known. We show that the kinesin motor protein Kif1a and an intact microtubule network are necessary to enrich synaptic vesicles at the presynapse in hair cells. We use genetics and pharmacology to disrupt Kif1a function and impair microtubule networks in hair cells of the zebrafish lateral-line system. We find that these manipulations decrease synaptic-vesicle populations at the presynapse in hair cells. Using electron microscopy, along with in vivo calcium imaging and electrophysiology, we show that a diminished supply of synaptic vesicles adversely affects ribbon-synapse function. Kif1a mutants exhibit dramatic reductions in spontaneous vesicle release and evoked postsynaptic calcium responses. Additionally, we find that kif1a mutants exhibit impaired rheotaxis, a behavior reliant on the ability of hair cells in the lateral line to respond to sustained flow stimuli. Overall, our results demonstrate that Kif1a-based microtubule transport is critical to enrich synaptic vesicles at the active zone in hair cells, a process that is vital for proper ribbon-synapse function. Key points Kif1a mRNAs are present in zebrafish hair cellsLoss of Kif1a disrupts the enrichment of synaptic vesicles at ribbon synapsesDisruption of microtubules depletes synaptic vesicles at ribbon synapsesKif1a mutants have impaired ribbon-synapse and sensory-system function.
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2
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Matsubayashi HT, Mountain J, Takahashi N, Deb Roy A, Yao T, Peterson AF, Saez Gonzalez C, Kawamata I, Inoue T. Non-catalytic role of phosphoinositide 3-kinase in mesenchymal cell migration through non-canonical induction of p85β/AP2-mediated endocytosis. Nat Commun 2024; 15:2612. [PMID: 38521786 PMCID: PMC10960865 DOI: 10.1038/s41467-024-46855-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 03/13/2024] [Indexed: 03/25/2024] Open
Abstract
Class IA phosphoinositide 3-kinase (PI3K) galvanizes fundamental cellular processes such as migration, proliferation, and differentiation. To enable these multifaceted roles, the catalytic subunit p110 utilizes the multi-domain, regulatory subunit p85 through its inter SH2 domain (iSH2). In cell migration, its product PI(3,4,5)P3 generates locomotive activity. While non-catalytic roles are also implicated, underlying mechanisms and their relationship to PI(3,4,5)P3 signaling remain elusive. Here, we report that a disordered region of iSH2 contains AP2 binding motifs which can trigger clathrin and dynamin-mediated endocytosis independent of PI3K catalytic activity. The AP2 binding motif mutants of p85 aberrantly accumulate at focal adhesions and increase both velocity and persistency in fibroblast migration. We thus propose the dual functionality of PI3K in the control of cell motility, catalytic and non-catalytic, arising distinctly from juxtaposed regions within iSH2.
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Affiliation(s)
- Hideaki T Matsubayashi
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.
- Center for Cell Dynamics, Institute of Basic Biomedical Sciences, Johns Hopkins University, Baltimore, MD, USA.
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Tohoku, Japan.
| | - Jack Mountain
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- Center for Cell Dynamics, Institute of Basic Biomedical Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Nozomi Takahashi
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Tohoku, Japan
| | - Abhijit Deb Roy
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- Center for Cell Dynamics, Institute of Basic Biomedical Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Tony Yao
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- Center for Cell Dynamics, Institute of Basic Biomedical Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Amy F Peterson
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- Center for Cell Dynamics, Institute of Basic Biomedical Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Cristian Saez Gonzalez
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- Center for Cell Dynamics, Institute of Basic Biomedical Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Ibuki Kawamata
- Department of Robotics, Tohoku University, Tohoku, Japan
- Natural Science Division, Ochanomizu University, Kyoto, Japan
- Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Takanari Inoue
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.
- Center for Cell Dynamics, Institute of Basic Biomedical Sciences, Johns Hopkins University, Baltimore, MD, USA.
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3
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Jamecna D, Höglinger D. The use of click chemistry in sphingolipid research. J Cell Sci 2024; 137:jcs261388. [PMID: 38488070 DOI: 10.1242/jcs.261388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2024] Open
Abstract
Sphingolipid dysregulation is involved in a range of rare and fatal diseases as well as common pathologies including cancer, infectious diseases or neurodegeneration. Gaining insights into how sphingolipids are involved in these diseases would contribute much to our understanding of human physiology, as well as the pathology mechanisms. However, scientific progress is hampered by a lack of suitable tools that can be used in intact systems. To overcome this, efforts have turned to engineering modified lipids with small clickable tags and to harnessing the power of click chemistry to localize and follow these minimally modified lipid probes in cells. We hope to inspire the readers of this Review to consider applying existing click chemistry tools for their own aspects of sphingolipid research. To this end, we focus here on different biological applications of clickable lipids, mainly to follow metabolic conversions, their visualization by confocal or superresolution microscopy or the identification of their protein interaction partners. Finally, we describe recent approaches employing organelle-targeted and clickable lipid probes to accurately follow intracellular sphingolipid transport with organellar precision.
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Affiliation(s)
- Denisa Jamecna
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69118 Heidelberg, Germany
| | - Doris Höglinger
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69118 Heidelberg, Germany
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4
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Cepeda AP, Ninov M, Neef J, Parfentev I, Kusch K, Reisinger E, Jahn R, Moser T, Urlaub H. Proteomic Analysis Reveals the Composition of Glutamatergic Organelles of Auditory Inner Hair Cells. Mol Cell Proteomics 2024; 23:100704. [PMID: 38128648 PMCID: PMC10832297 DOI: 10.1016/j.mcpro.2023.100704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 11/08/2023] [Accepted: 12/18/2023] [Indexed: 12/23/2023] Open
Abstract
In the ear, inner hair cells (IHCs) employ sophisticated glutamatergic ribbon synapses with afferent neurons to transmit auditory information to the brain. The presynaptic machinery responsible for neurotransmitter release in IHC synapses includes proteins such as the multi-C2-domain protein otoferlin and the vesicular glutamate transporter 3 (VGluT3). Yet, much of this likely unique molecular machinery remains to be deciphered. The scarcity of material has so far hampered biochemical studies which require large amounts of purified samples. We developed a subcellular fractionation workflow combined with immunoisolation of VGluT3-containing membrane vesicles, allowing for the enrichment of glutamatergic organelles that are likely dominated by synaptic vesicles (SVs) of IHCs. We have characterized their protein composition in mice before and after hearing onset using mass spectrometry and confocal imaging and provide a fully annotated proteome with hitherto unidentified proteins. Despite the prevalence of IHC marker proteins across IHC maturation, the profiles of trafficking proteins differed markedly before and after hearing onset. Among the proteins enriched after hearing onset were VAMP-7, syntaxin-7, syntaxin-8, syntaxin-12/13, SCAMP1, V-ATPase, SV2, and PKCα. Our study provides an inventory of the machinery associated with synaptic vesicle-mediated trafficking and presynaptic activity at IHC ribbon synapses and serves as a foundation for future functional studies.
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Affiliation(s)
- Andreia P Cepeda
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Momchil Ninov
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany; Department of Clinical Chemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Jakob Neef
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany; Auditory Neuroscience & Synaptic Nanophysiology Group Max-Planck-Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Iwan Parfentev
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Kathrin Kusch
- Functional Auditory Genomics Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Ellen Reisinger
- Gene Therapy for Hearing Impairment and Deafness, Department for Otolaryngology, Head & Neck Surgery, University Hospital Tübingen, Tübingen, Germany
| | - Reinhard Jahn
- Laboratory of Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany.
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany; Auditory Neuroscience & Synaptic Nanophysiology Group Max-Planck-Institute for Multidisciplinary Sciences, Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany.
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany; Department of Clinical Chemistry, University Medical Center Göttingen, Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany.
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5
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Gifford LB, Melikyan GB. HIV-1 Capsid Uncoating Is a Multistep Process That Proceeds through Defect Formation Followed by Disassembly of the Capsid Lattice. ACS NANO 2024; 18:2928-2947. [PMID: 38241476 PMCID: PMC10832047 DOI: 10.1021/acsnano.3c07678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 01/17/2024] [Accepted: 01/17/2024] [Indexed: 01/21/2024]
Abstract
The HIV-1 core consists of a cone-shaped capsid shell made of capsid protein (CA) hexamers and pentamers encapsulating the viral genome. HIV-1 capsid disassembly, referred to as uncoating, is important for productive infection; however, the location, timing, and regulation of uncoating remain controversial. Here, we employ amber codon suppression to directly label CA. In addition, a fluid phase fluorescent probe is incorporated into the viral core to detect small defects in the capsid lattice. This double-labeling strategy enables the visualization of uncoating of single cores in vitro and in living cells, which we found to always proceed through at least two distinct steps─the formation of a defect in the capsid lattice that initiates gradual loss of CA below a detectable level. Importantly, intact cores containing the fluid phase and CA fluorescent markers enter and uncoat in the nucleus, as evidenced by a sequential loss of both markers, prior to establishing productive infection. This two-step uncoating process is observed in different cells, including a macrophage line. Notably, the lag between the release of fluid phase marker and terminal loss of CA appears to be independent of the cell type or reverse transcription and is much longer (>5-fold) for nuclear capsids compared to cell-free cores or cores in the cytosol, suggesting that the capsid lattice is stabilized by capsid-binding nuclear factors. Our results imply that intact HIV-1 cores enter the cell nucleus and that uncoating is initiated through a localized defect in the capsid lattice prior to a global loss of CA.
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Affiliation(s)
- Levi B. Gifford
- Department
of Pediatrics, Emory University School of
Medicine, Atlanta, Georgia 30322, United States
| | - Gregory B. Melikyan
- Department
of Pediatrics, Emory University School of
Medicine, Atlanta, Georgia 30322, United States
- Children’s
Healthcare of Atlanta, Atlanta, Georgia 30322, United States
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6
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Wu LG, Chan CY. Membrane transformations of fusion and budding. Nat Commun 2024; 15:21. [PMID: 38167896 PMCID: PMC10761761 DOI: 10.1038/s41467-023-44539-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 12/15/2023] [Indexed: 01/05/2024] Open
Abstract
Membrane fusion and budding mediate fundamental processes like intracellular trafficking, exocytosis, and endocytosis. Fusion is thought to open a nanometer-range pore that may subsequently close or dilate irreversibly, whereas budding transforms flat membranes into vesicles. Reviewing recent breakthroughs in real-time visualization of membrane transformations well exceeding this classical view, we synthesize a new model and describe its underlying mechanistic principles and functions. Fusion involves hemi-to-full fusion, pore expansion, constriction and/or closure while fusing vesicles may shrink, enlarge, or receive another vesicle fusion; endocytosis follows exocytosis primarily by closing Ω-shaped profiles pre-formed through the flat-to-Λ-to-Ω-shape transition or formed via fusion. Calcium/SNARE-dependent fusion machinery, cytoskeleton-dependent membrane tension, osmotic pressure, calcium/dynamin-dependent fission machinery, and actin/dynamin-dependent force machinery work together to generate fusion and budding modes differing in pore status, vesicle size, speed and quantity, controls release probability, synchronization and content release rates/amounts, and underlies exo-endocytosis coupling to maintain membrane homeostasis. These transformations, underlying mechanisms, and functions may be conserved for fusion and budding in general.
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Affiliation(s)
- Ling-Gang Wu
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA.
| | - Chung Yu Chan
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
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7
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Chen H, Fang Q, Benseler F, Brose N, Moser T. Probing the role of the C 2F domain of otoferlin. Front Mol Neurosci 2023; 16:1299509. [PMID: 38152587 PMCID: PMC10751786 DOI: 10.3389/fnmol.2023.1299509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 11/07/2023] [Indexed: 12/29/2023] Open
Abstract
Afferent synapses of cochlear inner hair cells (IHCs) employ a unique molecular machinery. Otoferlin is a key player in this machinery, and its genetic defects cause human auditory synaptopathy. We employed site-directed mutagenesis in mice to investigate the role of Ca2+ binding to the C2F domain of otoferlin. Substituting two aspartate residues of the C2F top loops, which are thought to coordinate Ca2+-ions, by alanines (OtofD1841/1842A) abolished Ca2+-influx-triggered IHC exocytosis and synchronous signaling in the auditory pathway despite substantial expression (~60%) of the mutant otoferlin in the basolateral IHC pole. Ca2+ influx of IHCs and their resting membrane capacitance, reflecting IHC size, as well as the number of IHC synapses were maintained. The mutant otoferlin showed a strong apex-to-base abundance gradient in IHCs, suggesting impaired protein targeting. Our results indicate a role of the C2F domain in otoferlin targeting and of Ca2+ binding by the C2F domain for IHC exocytosis and hearing.
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Affiliation(s)
- Han Chen
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Auditory Neuroscience and Synaptic Nanophysiology Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Göttingen Graduate Center for Neurosciences, Biophysics and Molecular Biosciences, University of Göttingen, Göttingen, Germany
| | - Qinghua Fang
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Auditory Neuroscience and Synaptic Nanophysiology Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Fritz Benseler
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Nils Brose
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, Göttingen, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Auditory Neuroscience and Synaptic Nanophysiology Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, Göttingen, Germany
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8
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Wang UTT, Tian X, Liou YH, Lee SP, Hu HT, Lu CH, Lin PT, Cheng YJ, Chen P, Chen BC. Protein and lipid expansion microscopy with trypsin and tyramide signal amplification for 3D imaging. Sci Rep 2023; 13:21922. [PMID: 38081848 PMCID: PMC10713663 DOI: 10.1038/s41598-023-48959-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 12/01/2023] [Indexed: 12/18/2023] Open
Abstract
Expansion microscopy, whereby the relative positions of biomolecules are physically increased via hydrogel expansion, can be used to reveal ultrafine structures of cells under a conventional microscope. Despite its utility for achieving super-resolution imaging, expansion microscopy suffers a major drawback, namely reduced fluorescence signals caused by excessive proteolysis and swelling effects. This caveat results in a lower photon budget and disfavors fluorescence imaging over a large field of view that can cover an entire expanded cell, especially in 3D. In addition, the complex procedures and specialized reagents of expansion microscopy hinder its popularization. Here, we modify expansion microscopy by deploying trypsin digestion to reduce protein loss and tyramide signal amplification to enhance fluorescence signal for point-scanning-based imaging. We name our new methodology TT-ExM to indicate dual trypsin and tyramide treatments. TT-ExM may be applied for both antibody and lipid staining. TT-ExM displayed enhanced protein retention for endoplasmic reticulum and mitochondrial markers in COS-7 cell cultures. Importantly, TT-ExM-based lipid staining clearly revealed the complex 3D membrane structures in entire expanded cells. Through combined lipid and DNA staining, our TT-ExM methodology highlighted mitochondria by revealing their DNA and membrane structures in cytoplasm, as well as the lipid-rich structures formed via phase separation in nuclei at interphase. We also observed lipid-rich chromosome matrices in the mitotic cells. These high-quality 3D images demonstrate the practicality of TT-ExM. Thus, readily available reagents can be deployed in TT-ExM to significantly enhance fluorescence signals and generate high-quality and ultrafine-resolution images under confocal microscopy.
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Affiliation(s)
- Ueh-Ting Tim Wang
- Affiliated Senior High School of National Taiwan Normal University, Taipei, 106348, Taiwan
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Xuejiao Tian
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
- Nano Science and Technology Program, Taiwan International Graduate Program, Academia Sinica and National Tsing Hua University, Taipei, 11529, Taiwan
- Department of Engineering and System Science, National Tsing Hua University, Hsinchu, 300, Taiwan
| | - Yae-Huei Liou
- Institute of Molecular Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - Sue-Ping Lee
- Institute of Molecular Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - Hsiao-Tang Hu
- Institute of Molecular Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - Chieh-Han Lu
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
- Institute and Undergraduate Program of Electro-Optical Engineering, National Taiwan Normal University, Taipei, 116, Taiwan
| | - Po-Ting Lin
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Ya-Jen Cheng
- Institute of Molecular Biology, Academia Sinica, Taipei, 11529, Taiwan
- Neuroscience Program, NPAS, Academia Sinica, Taipei, 11529, Taiwan, ROC
| | - Peilin Chen
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Bi-Chang Chen
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan.
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9
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Matsubayashi H, Mountain J, Yao T, Peterson A, Roy AD, Inoue T. Non-catalytic role of phosphoinositide 3-kinase in mesenchymal cell migration through non-canonical induction of p85β/AP-2-mediated endocytosis. RESEARCH SQUARE 2023:rs.3.rs-2432041. [PMID: 36712095 PMCID: PMC9882665 DOI: 10.21203/rs.3.rs-2432041/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Class IA phosphoinositide 3-kinase (PI3K) galvanizes fundamental cellular processes such as migration, proliferation, and differentiation. To enable multifaceted roles, the catalytic subunit p110 utilizes a multi-domain, regulatory subunit p85 through its inter SH2 domain (iSH2). In cell migration, their product PI(3,4,5)P3 generates locomotive activity. While non-catalytic roles are also implicated, underlying mechanisms and its relationship to PI(3,4,5)P3 signaling remain elusive. Here, we report that a disordered region of iSH2 contains previously uncharacterized AP-2 binding motifs which can trigger clathrin and dynamin-mediated endocytosis independent of PI3K catalytic activity. The AP-2 binding motif mutants of p85 aberrantly accumulate at focal adhesions and upregulate both velocity and persistency in fibroblast migration. We thus propose the dual functionality of PI3K in the control of cell motility, catalytic and non-catalytic, arising distinctly from juxtaposed regions within iSH2.
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10
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Affiliation(s)
- Sven Truckenbrodt
- Convergent Research, E11 Bio. 1600 Harbor Bay Parkway, Alameda, California94502, United States
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11
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Matsubayashi HT, Mountain J, Yao T, Peterson AF, Deb Roy A, Inoue T. Non-catalytic role of phosphoinositide 3-kinase in mesenchymal cell migration through non-canonical induction of p85β/AP-2-mediated endocytosis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2022.12.31.522383. [PMID: 36712134 PMCID: PMC9881872 DOI: 10.1101/2022.12.31.522383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Class IA phosphoinositide 3-kinase (PI3K) galvanizes fundamental cellular processes such as migration, proliferation, and differentiation. To enable multifaceted roles, the catalytic subunit p110 utilizes a multidomain, regulatory subunit p85 through its inter SH2 domain (iSH2). In cell migration, their product PI(3,4,5)P3 generates locomotive activity. While non-catalytic roles are also implicated, underlying mechanisms and its relationship to PI(3,4,5)P3 signaling remain elusive. Here, we report that a disordered region of iSH2 contains previously uncharacterized AP-2 binding motifs which can trigger clathrin and dynamin-mediated endocytosis independent of PI3K catalytic activity. The AP-2 binding motif mutants of p85 aberrantly accumulate at focal adhesions and upregulate both velocity and persistency in fibroblast migration. We thus propose the dual functionality of PI3K in the control of cell motility, catalytic and non-catalytic, arising distinctly from juxtaposed regions within iSH2.
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Affiliation(s)
- Hideaki T. Matsubayashi
- Department of Cell Biology, School of Medicine, Johns Hopkins University
- Center for Cell Dynamics, Institute of Basic Biomedical Sciences, Johns Hopkins University
| | - Jack Mountain
- Department of Cell Biology, School of Medicine, Johns Hopkins University
- Center for Cell Dynamics, Institute of Basic Biomedical Sciences, Johns Hopkins University
| | - Tony Yao
- Department of Cell Biology, School of Medicine, Johns Hopkins University
- Center for Cell Dynamics, Institute of Basic Biomedical Sciences, Johns Hopkins University
| | - Amy F. Peterson
- Department of Cell Biology, School of Medicine, Johns Hopkins University
- Center for Cell Dynamics, Institute of Basic Biomedical Sciences, Johns Hopkins University
| | - Abhijit Deb Roy
- Department of Cell Biology, School of Medicine, Johns Hopkins University
- Center for Cell Dynamics, Institute of Basic Biomedical Sciences, Johns Hopkins University
| | - Takanari Inoue
- Department of Cell Biology, School of Medicine, Johns Hopkins University
- Center for Cell Dynamics, Institute of Basic Biomedical Sciences, Johns Hopkins University
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12
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Gao G, Guo S, Zhang Q, Zhang H, Zhang C, Peng G. Kiaa1024L/Minar2 is essential for hearing by regulating cholesterol distribution in hair bundles. eLife 2022; 11:e80865. [PMID: 36317962 PMCID: PMC9714970 DOI: 10.7554/elife.80865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 10/31/2022] [Indexed: 12/05/2022] Open
Abstract
Unbiased genetic screens implicated a number of uncharacterized genes in hearing loss, suggesting some biological processes required for auditory function remain unexplored. Loss of Kiaa1024L/Minar2, a previously understudied gene, caused deafness in mice, but how it functioned in the hearing was unclear. Here, we show that disruption of kiaa1024L/minar2 causes hearing loss in the zebrafish. Defects in mechanotransduction, longer and thinner hair bundles, and enlarged apical lysosomes in hair cells are observed in the kiaa1024L/minar2 mutant. In cultured cells, Kiaa1024L/Minar2 is mainly localized to lysosomes, and its overexpression recruits cholesterol and increases cholesterol labeling. Strikingly, cholesterol is highly enriched in the hair bundle membrane, and loss of kiaa1024L/minar2 reduces cholesterol localization to the hair bundles. Lowering cholesterol levels aggravates, while increasing cholesterol levels rescues the hair cell defects in the kiaa1024L/minar2 mutant. Therefore, cholesterol plays an essential role in hair bundles, and Kiaa1024L/Minar2 regulates cholesterol distribution and homeostasis to ensure normal hearing.
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Affiliation(s)
- Ge Gao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan UniversityShanghaiChina
| | - Shuyu Guo
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan UniversityShanghaiChina
| | - Quan Zhang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan UniversityShanghaiChina
| | - Hefei Zhang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan UniversityShanghaiChina
| | - Cuizhen Zhang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan UniversityShanghaiChina
| | - Gang Peng
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan UniversityShanghaiChina
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13
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Aber ER, Griffey CJ, Davies T, Li AM, Yang YJ, Croce KR, Goldman JE, Grutzendler J, Canman JC, Yamamoto A. Oligodendroglial macroautophagy is essential for myelin sheath turnover to prevent neurodegeneration and death. Cell Rep 2022; 41:111480. [PMID: 36261002 PMCID: PMC9639605 DOI: 10.1016/j.celrep.2022.111480] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 07/25/2022] [Accepted: 09/19/2022] [Indexed: 12/23/2022] Open
Abstract
Although macroautophagy deficits are implicated across adult-onset neurodegenerative diseases, we understand little about how the discrete, highly evolved cell types of the central nervous system use macroautophagy to maintain homeostasis. One such cell type is the oligodendrocyte, whose myelin sheaths are central for the reliable conduction of action potentials. Using an integrated approach of mouse genetics, live cell imaging, electron microscopy, and biochemistry, we show that mature oligodendrocytes require macroautophagy to degrade cell autonomously their myelin by consolidating cytosolic and transmembrane myelin proteins into an amphisome intermediate prior to degradation. We find that disruption of autophagic myelin turnover leads to changes in myelin sheath structure, ultimately impairing neural function and culminating in an adult-onset progressive motor decline, neurodegeneration, and death. Our model indicates that the continuous and cell-autonomous maintenance of the myelin sheath through macroautophagy is essential, shedding insight into how macroautophagy dysregulation might contribute to neurodegenerative disease pathophysiology. Oligodendrocytes assemble myelin and support the axons they myelinate. Aber et al. report that oligodendrocytes coordinate autophagy and endocytosis to turn over myelin. The absence of oligodendroglial autophagy causes myelin abnormalities, behavioral dysfunction, glial and neurodegeneration, and death, demonstrating the importance of this process for a healthy CNS.
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Affiliation(s)
- Etan R Aber
- Doctoral Program in Neurobiology and Behavior, Medical Scientist Training Program, Columbia University, New York, NY 10032, USA; Department of Neurology, Columbia University, New York, NY 10032, USA
| | - Christopher J Griffey
- Doctoral Program in Neurobiology and Behavior, Medical Scientist Training Program, Columbia University, New York, NY 10032, USA; Department of Neurology, Columbia University, New York, NY 10032, USA
| | - Tim Davies
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA; Department of Biosciences, Durham University, Durham DH1 3LE, UK
| | - Alice M Li
- Department of Neurology and Neuroscience, Yale University, New Haven, CT 06515, USA; Interdepartmental Neuroscience Program, Yale School of Medicine, New Haven, CT 06510, USA
| | - Young Joo Yang
- Graduate Program in Pathobiology and Molecular Medicine, Columbia University, New York, NY 10032, USA
| | - Katherine R Croce
- Department of Neurology, Columbia University, New York, NY 10032, USA; Graduate Program in Pathobiology and Molecular Medicine, Columbia University, New York, NY 10032, USA
| | - James E Goldman
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Jaime Grutzendler
- Department of Neurology and Neuroscience, Yale University, New Haven, CT 06515, USA
| | - Julie C Canman
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Ai Yamamoto
- Department of Neurology, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA.
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14
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An SJ, Stagi M, Gould TJ, Wu Y, Mlodzianoski M, Rivera-Molina F, Toomre D, Strittmatter SM, De Camilli P, Bewersdorf J, Zenisek D. Multimodal imaging of synaptic vesicles with a single probe. CELL REPORTS METHODS 2022; 2:100199. [PMID: 35497490 PMCID: PMC9046237 DOI: 10.1016/j.crmeth.2022.100199] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 02/11/2022] [Accepted: 03/28/2022] [Indexed: 05/17/2023]
Abstract
A complete understanding of synaptic-vesicle recycling requires the use of multiple microscopy methods to obtain complementary information. However, many currently available probes are limited to a specific microscopy modality, which necessitates the use of multiple probes and labeling paradigms. Given the complexity of vesicle populations and recycling pathways, having new single-vesicle probes that could be used for multiple microscopy techniques would complement existing sets of tools for studying vesicle function. Here, we present a probe based on the membrane-binding C2 domain of cytosolic phospholipase A2 (cPLA2) that fulfills this need. By conjugating the C2 domain with different detectable tags, we demonstrate that a single, modular probe can allow synaptic vesicles to be imaged at multiple levels of spatial and temporal resolution. Moreover, as a general endocytic marker, the C2 domain may also be used to study membrane recycling in many cell types.
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Affiliation(s)
- Seong J. An
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Massimiliano Stagi
- Program in Cellular Neuroscience, Neurodegeneration & Repair, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA
- Kavli Institute of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Molecular Physiology & Cell Signalling, Institute of Systems, Molecular & Integrative Biology, University of Liverpool, Liverpool 69 3BX, UK
| | - Travis J. Gould
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Physics and Astronomy, Bates College, Lewiston, ME 04240, USA
| | - Yumei Wu
- Program in Cellular Neuroscience, Neurodegeneration & Repair, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA
- Kavli Institute of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Michael Mlodzianoski
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Biomedical Engineering, Yale University School of Medicine, New Haven, CT 06510, USA
- Kavli Institute of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Felix Rivera-Molina
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Derek Toomre
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Stephen M. Strittmatter
- Program in Cellular Neuroscience, Neurodegeneration & Repair, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA
- Kavli Institute of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Pietro De Camilli
- Program in Cellular Neuroscience, Neurodegeneration & Repair, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA
- Kavli Institute of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Joerg Bewersdorf
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Biomedical Engineering, Yale University School of Medicine, New Haven, CT 06510, USA
- Kavli Institute of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
| | - David Zenisek
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06510, USA
- Program in Cellular Neuroscience, Neurodegeneration & Repair, Yale University School of Medicine, New Haven, CT 06510, USA
- Kavli Institute of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
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15
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Wang X, Sun M, Chan CY, Wu LG. Phospholipase A 2-based probes to study vesicle trafficking. CELL REPORTS METHODS 2022; 2:100206. [PMID: 35497501 PMCID: PMC9046444 DOI: 10.1016/j.crmeth.2022.100206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Vesicle exo- and endocytosis mediate important biological functions, including synaptic transmission. In this issue of Cell Reports Methods, Seong J. An et al. found that the fluorescently tagged C2 domain of phospholipase A2 binds to membrane phosphatidylcholine and thus labels vesicle membrane, allowing for super-resolution and electron microscopic visualization of vesicle trafficking.
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Affiliation(s)
- Xin Wang
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bldg. 35, Rm. 2B-1012, Bethesda, MD 20892, USA
| | - Min Sun
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bldg. 35, Rm. 2B-1012, Bethesda, MD 20892, USA
| | - Chung Yu Chan
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bldg. 35, Rm. 2B-1012, Bethesda, MD 20892, USA
| | - Ling-Gang Wu
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bldg. 35, Rm. 2B-1012, Bethesda, MD 20892, USA
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16
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Vogl C, Neef J, Wichmann C. Methods for multiscale structural and functional analysis of the mammalian cochlea. Mol Cell Neurosci 2022; 120:103720. [DOI: 10.1016/j.mcn.2022.103720] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 02/13/2022] [Accepted: 03/08/2022] [Indexed: 01/11/2023] Open
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17
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Insights into HIV uncoating from single-particle imaging techniques. Biophys Rev 2022; 14:23-32. [PMID: 35340594 PMCID: PMC8921429 DOI: 10.1007/s12551-021-00922-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 11/23/2021] [Indexed: 01/13/2023] Open
Abstract
Human immunodeficiency virus (HIV) is the most extensively researched human pathogen. Despite this massive scientific endeavour, several fundamental viral processes remain enigmatic. One such critical process is uncoating-the event that releases the viral genome from the proteinaceous shell of the capsid during infection. While this process is conceptually simple, the molecular underpinnings, timing, regulation, and cellular location of uncoating remain contentious. This review describes the hurdles that have limited our understanding in this area and presents recently deployed in vitro and in cellulo techniques that have been developed expressly with the aim of directly visualising capsid uncoating at the single-particle level and understanding the mechanics behind this essential aspect of HIV infection.
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18
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Guzikowski NJ, Kavalali ET. Nano-Organization at the Synapse: Segregation of Distinct Forms of Neurotransmission. Front Synaptic Neurosci 2022; 13:796498. [PMID: 35002671 PMCID: PMC8727373 DOI: 10.3389/fnsyn.2021.796498] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Accepted: 11/19/2021] [Indexed: 01/01/2023] Open
Abstract
Synapses maintain synchronous, asynchronous, and spontaneous modes of neurotransmission through distinct molecular and biochemical pathways. Traditionally a single synapse was assumed to have a homogeneous organization of molecular components both at the active zone and post-synaptically. However, recent advancements in experimental tools and the further elucidation of the physiological significance of distinct forms of release have challenged this notion. In comparison to rapid evoked release, the physiological significance of both spontaneous and asynchronous neurotransmission has only recently been considered in parallel with synaptic structural organization. Active zone nanostructure aligns with postsynaptic nanostructure creating a precise trans-synaptic alignment of release sites and receptors shaping synaptic efficacy, determining neurotransmission reliability, and tuning plasticity. This review will discuss how studies delineating synaptic nanostructure create a picture of a molecularly heterogeneous active zone tuned to distinct forms of release that may dictate diverse synaptic functional outputs.
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Affiliation(s)
- Natalie J Guzikowski
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States.,Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, United States
| | - Ege T Kavalali
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States.,Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, United States
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19
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Show your true color: Mammalian cell surface staining for tracking cellular identity in multiplexing and beyond. Curr Opin Chem Biol 2021; 66:102102. [PMID: 34861482 DOI: 10.1016/j.cbpa.2021.102102] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 10/18/2021] [Accepted: 10/27/2021] [Indexed: 12/23/2022]
Abstract
Fluorescence microscopy revolutionized cell biology and changed requirements for dyes towards higher brightness, novel capacities, and specific targets. With the need for multiplexing assays in high-throughput methodologies, surface staining gained particular interest because it allows rapid application of exogenous stains to track cellular identity in mixed populations. Indeed, the last decade has enriched the toolbox of general lipid stains, fluorescent lipid analogues, sugar-binding lectins, and protein-specific antibodies enabling the first rationally designed plasma membrane-specific dyes. Still, multiple challenges exist, and the unique properties of each dye must be considered when selecting a staining approach for a specific application. Recent advances are also promising that future dyes will provide ultimate brightness and photostability in diverse colors and reduced sizes for high-resolution imaging.
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20
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Abstract
Fluorescence imaging techniques play a pivotal role in our understanding of the nervous system. The emergence of various super-resolution microscopy methods and specialized fluorescent probes enables direct insight into neuronal structure and protein arrangements in cellular subcompartments with so far unmatched resolution. Super-resolving visualization techniques in neurons unveil a novel understanding of cytoskeletal composition, distribution, motility, and signaling of membrane proteins, subsynaptic structure and function, and neuron-glia interaction. Well-defined molecular targets in autoimmune and neurodegenerative disease models provide excellent starting points for in-depth investigation of disease pathophysiology using novel and innovative imaging methodology. Application of super-resolution microscopy in human brain samples and for testing clinical biomarkers is still in its infancy but opens new opportunities for translational research in neurology and neuroscience. In this review, we describe how super-resolving microscopy has improved our understanding of neuronal and brain function and dysfunction in the last two decades.
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Affiliation(s)
- Christian Werner
- Department of Biotechnology & Biophysics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Markus Sauer
- Department of Biotechnology & Biophysics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Christian Geis
- Section Translational Neuroimmunology, Department of Neurology, Jena University Hospital, Am Klinikum 1, 07747 Jena, Germany
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21
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Preformed Ω-profile closure and kiss-and-run mediate endocytosis and diverse endocytic modes in neuroendocrine chromaffin cells. Neuron 2021; 109:3119-3134.e5. [PMID: 34411513 DOI: 10.1016/j.neuron.2021.07.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 06/02/2021] [Accepted: 07/23/2021] [Indexed: 01/29/2023]
Abstract
Transformation of flat membrane into round vesicles is generally thought to underlie endocytosis and produce speed-, amount-, and vesicle-size-specific endocytic modes. Visualizing depolarization-induced exocytic and endocytic membrane transformation in live neuroendocrine chromaffin cells, we found that flat membrane is transformed into Λ-shaped, Ω-shaped, and O-shaped vesicles via invagination, Λ-base constriction, and Ω-pore constriction, respectively. Surprisingly, endocytic vesicle formation is predominantly from not flat-membrane-to-round-vesicle transformation but calcium-triggered and dynamin-mediated closure of (1) Ω profiles formed before depolarization and (2) fusion pores (called kiss-and-run). Varying calcium influxes control the speed, number, and vesicle size of these pore closures, resulting in speed-specific slow (more than ∼6 s), fast (less than ∼6 s), or ultrafast (<0.6 s) endocytosis, amount-specific compensatory endocytosis (endocytosis = exocytosis) or overshoot endocytosis (endocytosis > exocytosis), and size-specific bulk endocytosis. These findings reveal major membrane transformation mechanisms underlying endocytosis, diverse endocytic modes, and exocytosis-endocytosis coupling, calling for correction of the half-a-century concept that the flat-to-round transformation predominantly mediates endocytosis after physiological stimulation.
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22
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Broichhagen J, Kilian N. Chemical Biology Tools To Investigate Malaria Parasites. Chembiochem 2021; 22:2219-2236. [PMID: 33570245 PMCID: PMC8360121 DOI: 10.1002/cbic.202000882] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/10/2021] [Indexed: 02/06/2023]
Abstract
Parasitic diseases like malaria tropica have been shaping human evolution and history since the beginning of mankind. After infection, the response of the human host ranges from asymptomatic to severe and may culminate in death. Therefore, proper examination of the parasite's biology is pivotal to deciphering unique molecular, biochemical and cell biological processes, which in turn ensure the identification of treatment strategies, such as potent drug targets and vaccine candidates. However, implementing molecular biology methods for genetic manipulation proves to be difficult for many parasite model organisms. The development of fast and straightforward applicable alternatives, for instance small-molecule probes from the field of chemical biology, is essential. In this review, we will recapitulate the highlights of previous molecular and chemical biology approaches that have already created insight and understanding of the malaria parasite Plasmodium falciparum. We discuss current developments from the field of chemical biology and explore how their application could advance research into this parasite in the future. We anticipate that the described approaches will help to close knowledge gaps in the biology of P. falciparum and we hope that researchers will be inspired to use these methods to gain knowledge - with the aim of ending this devastating disease.
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Affiliation(s)
- Johannes Broichhagen
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP)Robert-Roessle-Strasse 1013125BerlinGermany
| | - Nicole Kilian
- Centre for Infectious DiseasesParasitologyHeidelberg University HospitalIm Neuenheimer Feld 32469120HeidelbergGermany
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23
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Manchanda A, Bonventre JA, Bugel SM, Chatterjee P, Tanguay R, Johnson CP. Truncation of the otoferlin transmembrane domain alters the development of hair cells and reduces membrane docking. Mol Biol Cell 2021; 32:1293-1305. [PMID: 33979209 PMCID: PMC8351550 DOI: 10.1091/mbc.e20-10-0657] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Release of neurotransmitter from sensory hair cells is regulated by otoferlin. Despite the importance of otoferlin in the auditory and vestibular pathways, the functional contributions of the domains of the protein have not been fully characterized. Using a zebrafish model, we investigated a mutant otoferlin with a stop codon at the start of the transmembrane domain. We found that both the phenotype severity and the expression level of mutant otoferlin changed with the age of the zebrafish. At the early developmental time point of 72 h post fertilization, low expression of the otoferlin mutant coincided with synaptic ribbon deficiencies, reduced endocytosis, and abnormal transcription of several hair cell genes. As development proceeded, expression of the mutant otoferlin increased, and both synaptic ribbons and hair cell transcript levels resembled wild type. However, hair cell endocytosis deficits and abnormalities in the expression of GABA receptors persisted even after up-regulation of mutant otoferlin. Analysis of membrane-reconstituted otoferlin measurements suggests a function for the transmembrane domain in liposome docking. We conclude that deletion of the transmembrane domain reduces membrane docking, attenuates endocytosis, and results in developmental delay of the hair cell.
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Affiliation(s)
- Aayushi Manchanda
- Molecular and Cellular Biology Program, Oregon State University, Corvallis, OR 97333
| | - Josephine A Bonventre
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97333
| | - Sean M Bugel
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR 97333
| | - Paroma Chatterjee
- Molecular and Cellular Biology Program, Oregon State University, Corvallis, OR 97333
| | - Robyn Tanguay
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR 97333
| | - Colin P Johnson
- Molecular and Cellular Biology Program, Oregon State University, Corvallis, OR 97333.,Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97333
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24
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Harper CB, Smillie KJ. Current molecular approaches to investigate pre-synaptic dysfunction. J Neurochem 2021; 157:107-129. [PMID: 33544872 DOI: 10.1111/jnc.15316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 12/19/2022]
Abstract
Over the course of the last few decades it has become clear that many neurodevelopmental and neurodegenerative disorders have a synaptic defect, which contributes to pathogenicity. A rise in new techniques, and in particular '-omics'-based methods providing large datasets, has led to an increase in potential proteins and pathways implicated in synaptic function and related disorders. Additionally, advancements in imaging techniques have led to the recent discovery of alternative modes of synaptic vesicle recycling. This has resulted in a lack of clarity over the precise role of different pathways in maintaining synaptic function and whether these new pathways are dysfunctional in neurodevelopmental and neurodegenerative disorders. A greater understanding of the molecular detail of pre-synaptic function in health and disease is key to targeting new proteins and pathways for novel treatments and the variety of new techniques currently available provides an ideal opportunity to investigate these functions. This review focuses on techniques to interrogate pre-synaptic function, concentrating mainly on synaptic vesicle recycling. It further examines techniques to determine the underlying molecular mechanism of pre-synaptic dysfunction and discusses methods to identify molecular targets, along with protein-protein interactions and cellular localization. In combination, these techniques will provide an expanding and more complete picture of pre-synaptic function. With the application of recent technological advances, we are able to resolve events with higher spatial and temporal resolution, leading research towards a greater understanding of dysfunction at the presynapse and the role it plays in pathogenicity.
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Affiliation(s)
- Callista B Harper
- Centre for Discovery Brain Sciences, University of Edinburgh, Scotland, UK
| | - Karen J Smillie
- Centre for Discovery Brain Sciences, University of Edinburgh, Scotland, UK
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25
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Ivanova D, Imig C, Camacho M, Reinhold A, Guhathakurta D, Montenegro-Venegas C, Cousin MA, Gundelfinger ED, Rosenmund C, Cooper B, Fejtova A. CtBP1-Mediated Membrane Fission Contributes to Effective Recycling of Synaptic Vesicles. Cell Rep 2021; 30:2444-2459.e7. [PMID: 32075774 PMCID: PMC7034063 DOI: 10.1016/j.celrep.2020.01.079] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 12/12/2019] [Accepted: 01/22/2020] [Indexed: 01/08/2023] Open
Abstract
Compensatory endocytosis of released synaptic vesicles (SVs) relies on coordinated signaling at the lipid-protein interface. Here, we address the synaptic function of C-terminal binding protein 1 (CtBP1), a ubiquitous regulator of gene expression and membrane trafficking in cultured hippocampal neurons. In the absence of CtBP1, synapses form in greater density and show changes in SV distribution and size. The increased basal neurotransmission and enhanced synaptic depression could be attributed to a higher vesicular release probability and a smaller fraction of release-competent SVs, respectively. Rescue experiments with specifically targeted constructs indicate that, while synaptogenesis and release probability are controlled by nuclear CtBP1, the efficient recycling of SVs relies on its synaptic expression. The ability of presynaptic CtBP1 to facilitate compensatory endocytosis depends on its membrane-fission activity and the activation of the lipid-metabolizing enzyme PLD1. Thus, CtBP1 regulates SV recycling by promoting a permissive lipid environment for compensatory endocytosis.
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Affiliation(s)
- Daniela Ivanova
- RG Presynaptic Plasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany; Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany; Molecular Psychiatry, Department of Psychiatry and Psychotherapy, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Cordelia Imig
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, German
| | - Marcial Camacho
- Institute of Neurophysiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Annika Reinhold
- Institute of Neurophysiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Debarpan Guhathakurta
- Molecular Psychiatry, Department of Psychiatry and Psychotherapy, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | | | - Michael A Cousin
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, EH9 9XD Edinburgh, UK
| | - Eckart D Gundelfinger
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany; Center for Behavioral Brain Science and Medical Faculty, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Christian Rosenmund
- Institute of Neurophysiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Benjamin Cooper
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, German
| | - Anna Fejtova
- RG Presynaptic Plasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany; Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany; Molecular Psychiatry, Department of Psychiatry and Psychotherapy, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
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26
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Effertz T, Moser T, Oliver D. Recent advances in cochlear hair cell nanophysiology: subcellular compartmentalization of electrical signaling in compact sensory cells. Fac Rev 2021; 9:24. [PMID: 33659956 PMCID: PMC7886071 DOI: 10.12703/r/9-24] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In recent years, genetics, physiology, and structural biology have advanced into the molecular details of the sensory physiology of auditory hair cells. Inner hair cells (IHCs) and outer hair cells (OHCs) mediate two key functions: active amplification and non-linear compression of cochlear vibrations by OHCs and sound encoding by IHCs at their afferent synapses with the spiral ganglion neurons. OHCs and IHCs share some molecular physiology, e.g. mechanotransduction at the apical hair bundles, ribbon-type presynaptic active zones, and ionic conductances in the basolateral membrane. Unique features enabling their specific function include prestin-based electromotility of OHCs and indefatigable transmitter release at the highest known rates by ribbon-type IHC active zones. Despite their compact morphology, the molecular machineries that either generate electrical signals or are driven by these signals are essentially all segregated into local subcellular structures. This review provides a brief account on recent insights into the molecular physiology of cochlear hair cells with a specific focus on organization into membrane domains.
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Affiliation(s)
- Thomas Effertz
- InnerEarLab, Department of Otorhinolaryngology, University Medical Center Göttingen, 37099 Göttingen, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37099 Göttingen, Germany
- Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, 37075 Göttingen, Germany
- Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
- Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, 37075 Göttingen, Germany
| | - Dominik Oliver
- Institute for Physiology and Pathophysiology, Philipps University, Deutschhausstraße 2, 35037 Marburg, Germany
- Center for Mind, Brain and Behavior (CMBB), Universities of Marburg and Giessen, Germany
- DFG Research Training Group, Membrane Plasticity in Tissue Development and Remodelling, GRK 2213, Philipps University, Marburg, Germany
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Zila V, Margiotta E, Turoňová B, Müller TG, Zimmerli CE, Mattei S, Allegretti M, Börner K, Rada J, Müller B, Lusic M, Kräusslich HG, Beck M. Cone-shaped HIV-1 capsids are transported through intact nuclear pores. Cell 2021; 184:1032-1046.e18. [PMID: 33571428 PMCID: PMC7895898 DOI: 10.1016/j.cell.2021.01.025] [Citation(s) in RCA: 153] [Impact Index Per Article: 51.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 11/20/2020] [Accepted: 01/19/2021] [Indexed: 12/14/2022]
Abstract
Human immunodeficiency virus (HIV-1) remains a major health threat. Viral capsid uncoating and nuclear import of the viral genome are critical for productive infection. The size of the HIV-1 capsid is generally believed to exceed the diameter of the nuclear pore complex (NPC), indicating that capsid uncoating has to occur prior to nuclear import. Here, we combined correlative light and electron microscopy with subtomogram averaging to capture the structural status of reverse transcription-competent HIV-1 complexes in infected T cells. We demonstrated that the diameter of the NPC in cellulo is sufficient for the import of apparently intact, cone-shaped capsids. Subsequent to nuclear import, we detected disrupted and empty capsid fragments, indicating that uncoating of the replication complex occurs by breaking the capsid open, and not by disassembly into individual subunits. Our data directly visualize a key step in HIV-1 replication and enhance our mechanistic understanding of the viral life cycle.
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Affiliation(s)
- Vojtech Zila
- Department of Infectious Diseases, Virology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Erica Margiotta
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany; Collaboration for joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Beata Turoňová
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany
| | - Thorsten G Müller
- Department of Infectious Diseases, Virology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Christian E Zimmerli
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany
| | - Simone Mattei
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany; Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, 8092 Zurich, Switzerland; European Molecular Biology Laboratory, Imaging Center, 69117 Heidelberg, Germany
| | - Matteo Allegretti
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany
| | - Kathleen Börner
- Department of Infectious Diseases, Virology, University of Heidelberg, 69120 Heidelberg, Germany; German Center for Infection Research, partner site Heidelberg, 69120 Heidelberg, Germany
| | - Jona Rada
- Department of Infectious Diseases, Virology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Barbara Müller
- Department of Infectious Diseases, Virology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Marina Lusic
- Department of Infectious Diseases, Virology, University of Heidelberg, 69120 Heidelberg, Germany; German Center for Infection Research, partner site Heidelberg, 69120 Heidelberg, Germany
| | - Hans-Georg Kräusslich
- Department of Infectious Diseases, Virology, University of Heidelberg, 69120 Heidelberg, Germany; German Center for Infection Research, partner site Heidelberg, 69120 Heidelberg, Germany.
| | - Martin Beck
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany; Max Planck Institute of Biophysics, Department of Molecular Sociology, 60438 Frankfurt, Germany.
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28
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Imaging Viral Infection by Fluorescence Microscopy: Focus on HIV-1 Early Stage. Viruses 2021; 13:v13020213. [PMID: 33573241 PMCID: PMC7911428 DOI: 10.3390/v13020213] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/28/2021] [Accepted: 01/28/2021] [Indexed: 12/15/2022] Open
Abstract
During the last two decades, progresses in bioimaging and the development of various strategies to fluorescently label the viral components opened a wide range of possibilities to visualize the early phase of Human Immunodeficiency Virus 1 (HIV-1) life cycle directly in infected cells. After fusion of the viral envelope with the cell membrane, the viral core is released into the cytoplasm and the viral RNA (vRNA) is retro-transcribed into DNA by the reverse transcriptase. During this process, the RNA-based viral complex transforms into a pre-integration complex (PIC), composed of the viral genomic DNA (vDNA) coated with viral and host cellular proteins. The protective capsid shell disassembles during a process called uncoating. The viral genome is transported into the cell nucleus and integrates into the host cell chromatin. Unlike biochemical approaches that provide global data about the whole population of viral particles, imaging techniques enable following individual viruses on a single particle level. In this context, quantitative microscopy has brought original data shedding light on the dynamics of the viral entry into the host cell, the cytoplasmic transport, the nuclear import, and the selection of the integration site. In parallel, multi-color imaging studies have elucidated the mechanism of action of host cell factors implicated in HIV-1 viral cycle progression. In this review, we describe the labeling strategies used for HIV-1 fluorescence imaging and report on the main advancements that imaging studies have brought in the understanding of the infection mechanisms from the viral entry into the host cell until the provirus integration step.
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29
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Chakraborty MP, Bhattacharyya S, Roy S, Bhattacharya I, Das R, Mukherjee A. Selective targeting of the inactive state of hematopoietic cell kinase (Hck) with a stable curcumin derivative. J Biol Chem 2021; 296:100449. [PMID: 33617879 PMCID: PMC7946438 DOI: 10.1016/j.jbc.2021.100449] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 02/05/2021] [Accepted: 02/18/2021] [Indexed: 11/29/2022] Open
Abstract
Hck, a Src family nonreceptor tyrosine kinase (SFK), has recently been established as an attractive pharmacological target to improve pulmonary function in COVID-19 patients. Hck inhibitors are also well known for their regulatory role in various malignancies and autoimmune diseases. Curcumin has been previously identified as an excellent DYRK-2 inhibitor, but curcumin's fate is tainted by its instability in the cellular environment. Besides, small molecules targeting the inactive states of a kinase are desirable to reduce promiscuity. Here, we show that functionalization of the 4-arylidene position of the fluorescent curcumin scaffold with an aryl nitrogen mustard provides a stable Hck inhibitor (Kd = 50 ± 10 nM). The mustard curcumin derivative preferentially interacts with the inactive conformation of Hck, similar to type-II kinase inhibitors that are less promiscuous. Moreover, the lead compound showed no inhibitory effect on three other kinases (DYRK2, Src, and Abl). We demonstrate that the cytotoxicity may be mediated via inhibition of the SFK signaling pathway in triple-negative breast cancer and murine macrophage cells. Our data suggest that curcumin is a modifiable fluorescent scaffold to develop selective kinase inhibitors by remodeling its target affinity and cellular stability.
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Affiliation(s)
- Manas Pratim Chakraborty
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur Campus, Mohanpur, India
| | - Sudipta Bhattacharyya
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur Campus, Mohanpur, India
| | - Souryadip Roy
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur Campus, Mohanpur, India
| | - Indira Bhattacharya
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur Campus, Mohanpur, India
| | - Rahul Das
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur Campus, Mohanpur, India; Centre for Advanced Functional Materials, Indian Institute of Science Education and Research Kolkata, Mohanpur Campus, Mohanpur, India.
| | - Arindam Mukherjee
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur Campus, Mohanpur, India; Centre for Advanced Functional Materials, Indian Institute of Science Education and Research Kolkata, Mohanpur Campus, Mohanpur, India.
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30
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Götz R, Kunz TC, Fink J, Solger F, Schlegel J, Seibel J, Kozjak-Pavlovic V, Rudel T, Sauer M. Nanoscale imaging of bacterial infections by sphingolipid expansion microscopy. Nat Commun 2020; 11:6173. [PMID: 33268771 PMCID: PMC7710728 DOI: 10.1038/s41467-020-19897-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 11/05/2020] [Indexed: 12/20/2022] Open
Abstract
Expansion microscopy (ExM) enables super-resolution imaging of proteins and nucleic acids on conventional microscopes. However, imaging of details of the organization of lipid bilayers by light microscopy remains challenging. We introduce an unnatural short-chain azide- and amino-modified sphingolipid ceramide, which upon incorporation into membranes can be labeled by click chemistry and linked into hydrogels, followed by 4× to 10× expansion. Confocal and structured illumination microscopy (SIM) enable imaging of sphingolipids and their interactions with proteins in the plasma membrane and membrane of intracellular organelles with a spatial resolution of 10–20 nm. As our functionalized sphingolipids accumulate efficiently in pathogens, we use sphingolipid ExM to investigate bacterial infections of human HeLa229 cells by Neisseria gonorrhoeae, Chlamydia trachomatis and Simkania negevensis with a resolution so far only provided by electron microscopy. In particular, sphingolipid ExM allows us to visualize the inner and outer membrane of intracellular bacteria and determine their distance to 27.6 ± 7.7 nm. Imaging of lipid bilayers using light microscopy is challenging. Here the authors label cells using a short chain click-compatible ceramide to visualize mammalian and bacterial membranes with expansion microscopy.
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Affiliation(s)
- Ralph Götz
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Tobias C Kunz
- Department of Microbiology, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Julian Fink
- Institute for Organic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Franziska Solger
- Department of Microbiology, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Jan Schlegel
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Jürgen Seibel
- Institute for Organic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Vera Kozjak-Pavlovic
- Department of Microbiology, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Thomas Rudel
- Department of Microbiology, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
| | - Markus Sauer
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
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31
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Matteau D, Lachance J, Grenier F, Gauthier S, Daubenspeck JM, Dybvig K, Garneau D, Knight TF, Jacques P, Rodrigue S. Integrative characterization of the near-minimal bacterium Mesoplasma florum. Mol Syst Biol 2020; 16:e9844. [PMID: 33331123 PMCID: PMC7745072 DOI: 10.15252/msb.20209844] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 11/02/2020] [Accepted: 11/03/2020] [Indexed: 12/11/2022] Open
Abstract
The near-minimal bacterium Mesoplasma florum is an interesting model for synthetic genomics and systems biology due to its small genome (~ 800 kb), fast growth rate, and lack of pathogenic potential. However, fundamental aspects of its biology remain largely unexplored. Here, we report a broad yet remarkably detailed characterization of M. florum by combining a wide variety of experimental approaches. We investigated several physical and physiological parameters of this bacterium, including cell size, growth kinetics, and biomass composition of the cell. We also performed the first genome-wide analysis of its transcriptome and proteome, notably revealing a conserved promoter motif, the organization of transcription units, and the transcription and protein expression levels of all protein-coding sequences. We converted gene transcription and expression levels into absolute molecular abundances using biomass quantification results, generating an unprecedented view of the M. florum cellular composition and functions. These characterization efforts provide a strong experimental foundation for the development of a genome-scale model for M. florum and will guide future genome engineering endeavors in this simple organism.
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Affiliation(s)
- Dominick Matteau
- Département de biologieUniversité de SherbrookeSherbrookeQCCanada
| | | | - Frédéric Grenier
- Département de biologieUniversité de SherbrookeSherbrookeQCCanada
| | - Samuel Gauthier
- Département de biologieUniversité de SherbrookeSherbrookeQCCanada
| | | | - Kevin Dybvig
- Department of GeneticsUniversity of Alabama at BirminghamBirminghamALUSA
| | - Daniel Garneau
- Département de biologieUniversité de SherbrookeSherbrookeQCCanada
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32
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Snider CE, Chandra M, McDonald NA, Willet AH, Collier SE, Ohi MD, Jackson LP, Gould KL. Opposite Surfaces of the Cdc15 F-BAR Domain Create a Membrane Platform That Coordinates Cytoskeletal and Signaling Components for Cytokinesis. Cell Rep 2020; 33:108526. [PMID: 33357436 PMCID: PMC7775634 DOI: 10.1016/j.celrep.2020.108526] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 11/02/2020] [Accepted: 11/24/2020] [Indexed: 12/15/2022] Open
Abstract
Many eukaryotes assemble an actin- and myosin-based cytokinetic ring (CR) on the plasma membrane (PM) for cell division, but how it is anchored there remains unclear. In Schizosaccharomyces pombe, the F-BAR protein Cdc15 links the PM via its F-BAR domain to proteins in the CR’s interior via its SH3 domain. However, Cdc15’s F-BAR domain also directly binds formin Cdc12, suggesting that Cdc15 may polymerize a protein network directly adjacent to the membrane. Here, we determine that the F-BAR domain binds Cdc12 using residues on the face opposite its membrane-binding surface. These residues also bind paxillin-like Pxl1, promoting its recruitment with calcineurin to the CR. Mutation of these F-BAR domain residues results in a shallower CR, with components localizing ~35% closer to the PM than in wild type, and aberrant CR constriction. Thus, F-BAR domains serve as oligomeric membrane-bound platforms that can modulate the architecture of an entire actin structure. Multiple F-BAR domains link actin structures to membrane. Snider et al. show that the flat Cdc15 F-BAR domain utilizes opposite surfaces to bind the plasma membrane and cytokinetic ring proteins simultaneously. Disrupting Cdc15 F-BAR domain’s interaction with proteins results in an overall compression of the entire cytokinetic ring architecture.
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Affiliation(s)
- Chloe E Snider
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Mintu Chandra
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Nathan A McDonald
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Alaina H Willet
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Scott E Collier
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Melanie D Ohi
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Lauren P Jackson
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Kathleen L Gould
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232, USA.
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33
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Lämmle CA, Varady A, Müller TG, Sturtzel C, Riepl M, Mathes B, Eichhorst J, Sporbert A, Lehmann M, Kräusslich HG, Distel M, Broichhagen J. Photocaged Hoechst Enables Subnuclear Visualization and Cell Selective Staining of DNA in vivo. Chembiochem 2020; 22:548-556. [PMID: 32974998 PMCID: PMC7894298 DOI: 10.1002/cbic.202000465] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 09/17/2020] [Indexed: 12/19/2022]
Abstract
Selective targeting of DNA by means of fluorescent labeling has become a mainstay in the life sciences. While genetic engineering serves as a powerful technique and allows the visualization of nucleic acid by using DNA‐targeting fluorescent fusion proteins in a cell‐type‐ and subcellular‐specific manner, it relies on the introduction of foreign genes. On the other hand, DNA‐binding small fluorescent molecules can be used without genetic engineering, but they are not spatially restricted. Herein, we report a photocaged version of the DNA dye Hoechst33342 (pcHoechst), which can be uncaged by using UV to blue light for the selective staining of chromosomal DNA in subnuclear regions of live cells. Expanding its application to a vertebrate model organism, we demonstrate uncaging in epithelial cells and short‐term cell tracking in vivo in zebrafish. We envision pcHoechst as a valuable tool for targeting and interrogating DNA with precise spatiotemporal resolution in living cells and wild‐type organisms.
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Affiliation(s)
- Carina A Lämmle
- Department of Chemical Biology, Max Planck Institute for Medical Research, Jahnstr. 29, 69120, Heidelberg, Germany
| | - Adam Varady
- St. Anna Children's Cancer Research Institute, Innovative Cancer Models, Zimmermannplatz 10, 1090, Vienna, Austria
| | - Thorsten G Müller
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Im Neuenheimer Feld 344, 69120, Heidelberg, Germany
| | - Caterina Sturtzel
- St. Anna Children's Cancer Research Institute, Innovative Cancer Models, Zimmermannplatz 10, 1090, Vienna, Austria.,Zebrafish Platform Austria for preclinical drug screening (ZANDR), Zimmermannplatz 10, 1090, Vienna, Austria
| | - Michael Riepl
- St. Anna Children's Cancer Research Institute, Innovative Cancer Models, Zimmermannplatz 10, 1090, Vienna, Austria
| | - Bettina Mathes
- Department of Chemical Biology, Max Planck Institute for Medical Research, Jahnstr. 29, 69120, Heidelberg, Germany
| | - Jenny Eichhorst
- Department of Molecular Pharmacology and Cell Biology, Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Straße 10, 13125, Berlin, Germany
| | - Anje Sporbert
- Advanced Light Microscopy, Max Delbrück Centrum for Molecular Medicine Berlin in the Helmholtz Association, Robert-Rössle-Straße 10, 13125, Berlin, Germany
| | - Martin Lehmann
- Department of Molecular Pharmacology and Cell Biology, Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Straße 10, 13125, Berlin, Germany
| | - Hans-Georg Kräusslich
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Im Neuenheimer Feld 344, 69120, Heidelberg, Germany
| | - Martin Distel
- St. Anna Children's Cancer Research Institute, Innovative Cancer Models, Zimmermannplatz 10, 1090, Vienna, Austria.,Zebrafish Platform Austria for preclinical drug screening (ZANDR), Zimmermannplatz 10, 1090, Vienna, Austria
| | - Johannes Broichhagen
- Department of Chemical Biology, Max Planck Institute for Medical Research, Jahnstr. 29, 69120, Heidelberg, Germany.,Department of Chemical Biology, Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Straße 10, 13125, Berlin, Germany
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34
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Brenna S, Altmeppen HC, Mohammadi B, Rissiek B, Schlink F, Ludewig P, Krisp C, Schlüter H, Failla AV, Schneider C, Glatzel M, Puig B, Magnus T. Characterization of brain-derived extracellular vesicles reveals changes in cellular origin after stroke and enrichment of the prion protein with a potential role in cellular uptake. J Extracell Vesicles 2020; 9:1809065. [PMID: 32944194 PMCID: PMC7480459 DOI: 10.1080/20013078.2020.1809065] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Revised: 07/28/2020] [Accepted: 08/09/2020] [Indexed: 02/06/2023] Open
Abstract
Extracellular vesicles (EVs) are important means of intercellular communication and a potent tool for regenerative therapy. In ischaemic stroke, transient blockage of a brain artery leads to a lack of glucose and oxygen in the affected brain tissue, provoking neuronal death by necrosis in the core of the ischaemic region. The fate of neurons in the surrounding penumbra region depends on the stimuli, including EVs, received during the following hours. A detailed characterization of such stimuli is crucial not only for understanding stroke pathophysiology but also for new therapeutic interventions. In the present study, we characterize the EVs in mouse brain under physiological conditions and 24 h after induction of transient ischaemia in mice. We show that, in steady-state conditions, microglia are the main source of small EVs (sEVs), whereas after ischaemia the main sEV population originates from astrocytes. Brain sEVs presented high amounts of the prion protein (PrP), which were further increased after stroke. Moreover, EVs were enriched in a proteolytically truncated PrP fragment (PrP-C1). Because of similarities between PrP-C1 and certain viral surface proteins, we studied the cellular uptake of brain-derived sEVs from mice lacking (PrP-KO) or expressing PrP (WT). We show that PrP-KO-sEVs are taken up significantly faster and more efficiently than WT-EVs by primary neurons. Furthermore, microglia and astrocytes engulf PrP-KO-sEVs more readily than WT-sEVs. Our results provide novel information on the relative contribution of brain cell types to the sEV pool in murine brain and indicate that increased release of sEVs by astrocytes together with elevated levels of PrP in sEVs may play a role in intercellular communication at early stages after stroke. In addition, amounts of PrP (and probably PrP-C1) in brain sEVs seem to contribute to regulating their cellular uptake.
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Affiliation(s)
- Santra Brenna
- Neurology Department, Experimental Research in Stroke and Inflammation, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Hermann C. Altmeppen
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Behnam Mohammadi
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Björn Rissiek
- Neurology Department, Experimental Research in Stroke and Inflammation, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Florence Schlink
- Neurology Department, Experimental Research in Stroke and Inflammation, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Peter Ludewig
- Neurology Department, Experimental Research in Stroke and Inflammation, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christoph Krisp
- Institute of Clinical Chemistry and Laboratory Medicine, Mass Spectrometric Proteomics University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Hartmut Schlüter
- Institute of Clinical Chemistry and Laboratory Medicine, Mass Spectrometric Proteomics University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Antonio Virgilio Failla
- UKE Microscopy Imaging Facility, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Carola Schneider
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Markus Glatzel
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Berta Puig
- Neurology Department, Experimental Research in Stroke and Inflammation, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Tim Magnus
- Neurology Department, Experimental Research in Stroke and Inflammation, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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35
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Wen G, Vanheusden M, Acke A, Valli D, Neely RK, Leen V, Hofkens J. Evaluation of Direct Grafting Strategies via Trivalent Anchoring for Enabling Lipid Membrane and Cytoskeleton Staining in Expansion Microscopy. ACS NANO 2020; 14:7860-7867. [PMID: 32176475 DOI: 10.1021/acsnano.9b09259] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Super-resolution fluorescence microscopy is a key tool in the elucidation of biological fine structures, providing insights into the distribution and interactions of biomolecular complexes down to the nanometer scale. Expansion microscopy is a recently developed approach for achieving nanoscale resolution on a conventional microscope. Here, biological samples are embedded in an isotropically swollen hydrogel. This physical expansion of the sample allows imaging with resolutions down to the tens-of-nanometers. However, because of the requirement that fluorescent labels are covalently bound to the hydrogel, standard, small-molecule targeting of fluorophores has proven incompatible with expansion microscopy. Here, we show a chemical linking approach that enables direct, covalent grafting of a targeting molecule and fluorophore to the hydrogel in expansion microscopy. We show application of this series of molecules in the antibody-free targeting of the cell cytoskeleton and in an example of lipid membrane staining for expansion microscopy. Furthermore, using this trivalent linker strategy, we demonstrate the benefit of introducing fluorescent labels post-expansion by visualizing an immunostaining through fluorescent oligonucleotide hybridization after expanding the polymer. Our probes allow different labeling approaches that are compatible with expansion microscopy.
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Affiliation(s)
- Gang Wen
- Department of Chemistry, KU Leuven, Leuven, 3001, Belgium
| | | | - Aline Acke
- Department of Chemistry, KU Leuven, Leuven, 3001, Belgium
| | - Donato Valli
- Department of Chemistry, KU Leuven, Leuven, 3001, Belgium
| | - Robert K Neely
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Volker Leen
- Department of Chemistry, KU Leuven, Leuven, 3001, Belgium
| | - Johan Hofkens
- Department of Chemistry, KU Leuven, Leuven, 3001, Belgium
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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36
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Collot M, Boutant E, Fam KT, Danglot L, Klymchenko AS. Molecular Tuning of Styryl Dyes Leads to Versatile and Efficient Plasma Membrane Probes for Cell and Tissue Imaging. Bioconjug Chem 2020; 31:875-883. [PMID: 32053748 DOI: 10.1021/acs.bioconjchem.0c00023] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The plasma membrane (PM) plays a major role in many biological processes; therefore, its proper fluorescence staining is required in bioimaging. Among the commercially available PM probes, styryl dye FM1-43 is one of the most widely used. In this work, we demonstrated that fine chemical modifications of FM1-43 can dramatically improve the PM staining. The newly developed probes, SP-468 and SQ-535, were found to display enhanced photophysical properties (reduced cross-talk, higher brightness, improved photostability) and, unlike FM1-43, provided excellent and immediate PM staining in 5 different mammalian cell types including neurons (primary culture and tissue imaging). Taking advantage of these features, we successfully used SP-468 in STED super resolution neuronal imaging. Additionally, we showed that the new probes displayed differences in their internalization pathways compared to their parent FM1-43. Finally, we showed that the new probes kept the ability to stain the PM of plant cells. Overall, this work presents new useful probes for PM imaging in cells and tissues and provides insights on the molecular design of new PM targeting molecules.
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Affiliation(s)
- Mayeul Collot
- Laboratoire de Bioimagerie et Pathologies, UMR 7021, CNRS, University of Strasbourg, FR 67401 Illkirch, France
| | - Emmanuel Boutant
- Laboratoire de Bioimagerie et Pathologies, UMR 7021, CNRS, University of Strasbourg, FR 67401 Illkirch, France
| | - Kyong Tkhe Fam
- Laboratoire de Bioimagerie et Pathologies, UMR 7021, CNRS, University of Strasbourg, FR 67401 Illkirch, France
| | - Lydia Danglot
- Université de Paris, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, "Membrane Traffic in Healthy and Diseased Brain", F 75014 Paris, France
| | - Andrey S Klymchenko
- Laboratoire de Bioimagerie et Pathologies, UMR 7021, CNRS, University of Strasbourg, FR 67401 Illkirch, France
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Gupta A, Rivera-Molina F, Xi Z, Toomre D, Schepartz A. Endosome motility defects revealed at super-resolution in live cells using HIDE probes. Nat Chem Biol 2020; 16:408-414. [PMID: 32094922 PMCID: PMC7176048 DOI: 10.1038/s41589-020-0479-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 01/15/2020] [Indexed: 12/13/2022]
Abstract
We report new lipid-based, high-density, environmentally sensitive (HIDE) probes that accurately and selectively image endo-lysosomes and their dynamics at super-resolution for extended times. Treatment of live cells with the small molecules DiIC16TCO or DiIC16’TCO followed by in situ tetrazine ligation reaction with the silicon-rhodamine dye SiR-Tz generates the HIDE probes DiIC16-SiR and DiIC16’-SiR in the endo-lysosomal membrane. These new probes support the acquisition of super-resolution videos of organelle dynamics in primary cells for more than 7 minutes with no detectable change in endosome structure or function. Using DiIC16-SiR and DiIC16’-SiR, we describe the first direct evidence of endosome motility defects in cells from patients with Niemann-Pick Type-C disease. In wild-type fibroblasts, the probes reveal distinct but rare inter-endosome kiss-and-run events that cannot be observed using confocal methods. Our results shed new light on the role of NPC1 in organelle motility and cholesterol trafficking.
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Affiliation(s)
- Aarushi Gupta
- Department of Chemistry, Yale University, New Haven, CT, USA
| | - Felix Rivera-Molina
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
| | - Zhiqun Xi
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
| | - Derek Toomre
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA.
| | - Alanna Schepartz
- Department of Chemistry, Yale University, New Haven, CT, USA. .,Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, USA. .,Department of Chemistry, University of California, Berkeley, CA, USA.
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Moser T, Grabner CP, Schmitz F. Sensory Processing at Ribbon Synapses in the Retina and the Cochlea. Physiol Rev 2020; 100:103-144. [DOI: 10.1152/physrev.00026.2018] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
In recent years, sensory neuroscientists have made major efforts to dissect the structure and function of ribbon synapses which process sensory information in the eye and ear. This review aims to summarize our current understanding of two key aspects of ribbon synapses: 1) their mechanisms of exocytosis and endocytosis and 2) their molecular anatomy and physiology. Our comparison of ribbon synapses in the cochlea and the retina reveals convergent signaling mechanisms, as well as divergent strategies in different sensory systems.
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Affiliation(s)
- Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany; Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, Göttingen, Germany; Synaptic Nanophysiology Group, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany; and Institute for Anatomy and Cell Biology, Department of Neuroanatomy, Medical School, Saarland University, Homburg, Germany
| | - Chad P. Grabner
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany; Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, Göttingen, Germany; Synaptic Nanophysiology Group, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany; and Institute for Anatomy and Cell Biology, Department of Neuroanatomy, Medical School, Saarland University, Homburg, Germany
| | - Frank Schmitz
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany; Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, Göttingen, Germany; Synaptic Nanophysiology Group, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany; and Institute for Anatomy and Cell Biology, Department of Neuroanatomy, Medical School, Saarland University, Homburg, Germany
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39
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Abstract
The HIV-1 capsid performs essential functions during early viral replication and is an interesting target for novel antivirals. Thus, understanding molecular and structural details of capsid function will be important for elucidating early HIV-1 (and retroviral in general) replication in relevant target cells and may also aid antiviral development. Here, we show that HIV-1 capsids stay largely intact during transport to the nucleus of infected T cells but appear to uncoat upon entry into the nucleoplasm. These results support the hypothesis that capsids protect the HIV-1 genome from cytoplasmic defense mechanisms and target the genome toward the nucleus. A protective role of the capsid could be a paradigm that also applies to other viruses. Our findings raise the question of how reverse transcription of the HIV-1 genome is accomplished in the context of the capsid structure and whether the process is completed before the capsid is uncoated at the nuclear pore. HIV-1 infects host cells by fusion at the plasma membrane, leading to cytoplasmic entry of the viral capsid encasing the genome and replication machinery. The capsid eventually needs to disassemble, but time and location of uncoating are not fully characterized and may vary depending on the host cell. To study the fate of the capsid by fluorescence and superresolution (STED) microscopy, we established an experimental system that allows discrimination of subviral structures in the cytosol from intact virions at the plasma membrane or in endosomes without genetic modification of the virus. Quantitative microscopy of infected SupT1-R5 cells revealed that the CA signal on cytosolic HIV-1 complexes corresponded to ∼50% of that found in virions at the cell surface, in agreement with dissociation of nonassembled CA molecules from entering capsids after membrane fusion. The relative amount of CA in postfusion complexes remained stable until they reached the nuclear pore complex, while subviral structures in the nucleus of infected cells lacked detectable CA. An HIV-1 variant defective in binding of the host protein cleavage and polyadenylation specificity factor 6 (CPSF6) exhibited accumulation of CA-positive subviral complexes close to the nuclear envelope without loss of infectivity; STED microscopy revealed direct association of these complexes with nuclear pores. These results support previous observations indicating capsid uncoating at the nuclear pore in infected T-cell lines. They suggest that largely intact HIV-1 capsids dock at the nuclear pore in infected SupT1-R5 cells, with CPSF6 being a facilitator of nucleoplasmic entry in this cell type, as has been observed for infected macrophages.
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Manchanda A, Chatterjee P, Bonventre JA, Haggard DE, Kindt KS, Tanguay RL, Johnson CP. Otoferlin Depletion Results in Abnormal Synaptic Ribbons and Altered Intracellular Calcium Levels in Zebrafish. Sci Rep 2019; 9:14273. [PMID: 31582816 PMCID: PMC6776657 DOI: 10.1038/s41598-019-50710-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 09/13/2019] [Indexed: 01/10/2023] Open
Abstract
The protein otoferlin plays an essential role at the sensory hair cell synapse. Mutations in otoferlin result in deafness and depending on the species, mild to strong vestibular deficits. While studies in mouse models suggest a role for otoferlin in synaptic vesicle exocytosis and endocytosis, it is unclear whether these functions are conserved across species. To address this question, we characterized the impact of otoferlin depletion in zebrafish larvae and found defects in synaptic vesicle recycling, abnormal synaptic ribbons, and higher resting calcium concentrations in hair cells. We also observed abnormal expression of the calcium binding hair cell genes s100s and parvalbumin, as well as the nogo related proteins rtn4rl2a and rtn4rl2b. Exogenous otoferlin partially restored expression of genes affected by endogenous otoferlin depletion. Our results suggest that in addition to vesicle recycling, depletion of otoferlin disrupts resting calcium levels, alters synaptic ribbon architecture, and perturbs transcription of hair cells specific genes during zebrafish development.
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Affiliation(s)
- Aayushi Manchanda
- Molecular and Cellular Biology Program, Oregon State University, Corvallis, Oregon, USA
| | - Paroma Chatterjee
- Molecular and Cellular Biology Program, Oregon State University, Corvallis, Oregon, USA
| | - Josephine A Bonventre
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon, USA
| | - Derik E Haggard
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, Oregon, USA
| | - Katie S Kindt
- National Institute of Deafness and Other Communication Disorders (NIDCD), NIH, Maryland, USA
| | - Robert L Tanguay
- Molecular and Cellular Biology Program, Oregon State University, Corvallis, Oregon, USA.,Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, Oregon, USA
| | - Colin P Johnson
- Molecular and Cellular Biology Program, Oregon State University, Corvallis, Oregon, USA. .,Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon, USA.
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Reshetniak S, Rizzoli SO. Interrogating Synaptic Architecture: Approaches for Labeling Organelles and Cytoskeleton Components. Front Synaptic Neurosci 2019; 11:23. [PMID: 31507402 PMCID: PMC6716447 DOI: 10.3389/fnsyn.2019.00023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 08/02/2019] [Indexed: 01/06/2023] Open
Abstract
Synaptic transmission has been studied for decades, as a fundamental step in brain function. The structure of the synapse, and its changes during activity, turned out to be key aspects not only in the transfer of information between neurons, but also in cognitive processes such as learning and memory. The overall synaptic morphology has traditionally been studied by electron microscopy, which enables the visualization of synaptic structure in great detail. The changes in the organization of easily identified structures, such as the presynaptic active zone, or the postsynaptic density, are optimally studied via electron microscopy. However, few reliable methods are available for labeling individual organelles or protein complexes in electron microscopy. For such targets one typically relies either on combination of electron and fluorescence microscopy, or on super-resolution fluorescence microscopy. This review focuses on approaches and techniques used to specifically reveal synaptic organelles and protein complexes, such as cytoskeletal assemblies. We place the strongest emphasis on methods detecting the targets of interest by affinity binding, and we discuss the advantages and limitations of each method.
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Affiliation(s)
- Sofiia Reshetniak
- Institute for Neuro- and Sensory Physiology, Center for Biostructural Imaging of Neurodegeneration (BIN), University Medical Center Göttingen, Göttingen, Germany
- International Max Planck Research School for Molecular Biology, Göttingen, Germany
| | - Silvio O. Rizzoli
- Institute for Neuro- and Sensory Physiology, Center for Biostructural Imaging of Neurodegeneration (BIN), University Medical Center Göttingen, Göttingen, Germany
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Huber MC, Schreiber A, Schiller SM. Minimalist Protocell Design: A Molecular System Based Solely on Proteins that Form Dynamic Vesicular Membranes Embedding Enzymatic Functions. Chembiochem 2019; 20:2618-2632. [PMID: 31183952 DOI: 10.1002/cbic.201900283] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Indexed: 12/24/2022]
Abstract
Life in its molecular context is characterized by the challenge of orchestrating structure, energy and information processes through compartmentalization and chemical transformations amenable to mimicry of protocell models. Here we present an alternative protocell model incorporating dynamic membranes based on amphiphilic elastin-like proteins (ELPs) rather than phospholipids. For the first time we demonstrate the feasibility of combining vesicular membrane formation and biocatalytic activity with molecular entities of a single class: proteins. The presented self-assembled protein-membrane-based compartments (PMBCs) accommodate either an anabolic reaction, based on free DNA ligase as an example of information transformation processes, or a catabolic process. We present a catabolic process based on a single molecular entity combining an amphiphilic protein with tobacco etch virus (TEV) protease as part of the enclosure of a reaction space and facilitating selective catalytic transformations. Combining compartmentalization and biocatalytic activity by utilizing an amphiphilic molecular building block with and without enzyme functionalization enables new strategies in bottom-up synthetic biology, regenerative medicine, pharmaceutical science and biotechnology.
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Affiliation(s)
- Matthias C Huber
- Zentrum für Biosystemanalyse (ZBSA), Albert-Ludwigs-Universität Freiburg, Habsburgerstrasse 49, 79104, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Schänzlestrasse 1, 79085, Freiburg, Germany
| | - Andreas Schreiber
- Zentrum für Biosystemanalyse (ZBSA), Albert-Ludwigs-Universität Freiburg, Habsburgerstrasse 49, 79104, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Schänzlestrasse 1, 79085, Freiburg, Germany
| | - Stefan M Schiller
- Zentrum für Biosystemanalyse (ZBSA), Albert-Ludwigs-Universität Freiburg, Habsburgerstrasse 49, 79104, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Schänzlestrasse 1, 79085, Freiburg, Germany
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Schänzlestrasse 18, 79104, Freiburg, Germany
- Cluster of Excellence livMatS @ FIT, Freiburg Center for Interactive Materials and Bioinspired Technologies, University of Freiburg, Georges-Köhler-Allee 105, 79110, Freiburg, Germany
- IMTEK Department of Microsystems Engineering, University of Freiburg, Georges-Köhler-Allee 103, 79110, Freiburg, Germany
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Abstract
Exosomes have been implicated in intercellular communication in cancer and neurodegenerative disorders. We explored their function in brain development. Proteomic analysis demonstrated that exosomes from isogenic control cultures contain neurodevelopmental signaling proteins, which are lacking in exosomes from MECP2 loss-of-function (MECP2LOF) cultures. Treating MECP2LOF neural cultures with control exosomes rescues neurodevelopmental deficits, increasing neurogenesis, synaptogenesis, and network activity. Exosomes function similarly in vivo: injecting purified exosomes into the lateral ventricles of P4 mouse brains increased hippocampal neurogenesis. These findings significantly advance the field by demonstrating that neural exosomes contain diverse protein cargo predicted to affect multiple outcome measures of neural development and that exosomes signal between cells in developing neural circuits to promote neural circuit development and function. Exosomes are thought to be released by all cells in the body and to be involved in intercellular communication. We tested whether neural exosomes can regulate the development of neural circuits. We show that exosome treatment increases proliferation in developing neural cultures and in vivo in dentate gyrus of P4 mouse brain. We compared the protein cargo and signaling bioactivity of exosomes released by hiPSC-derived neural cultures lacking MECP2, a model of the neurodevelopmental disorder Rett syndrome, with exosomes released by isogenic rescue control neural cultures. Quantitative proteomic analysis indicates that control exosomes contain multiple functional signaling networks known to be important for neuronal circuit development. Treating MECP2-knockdown human primary neural cultures with control exosomes rescues deficits in neuronal proliferation, differentiation, synaptogenesis, and synchronized firing, whereas exosomes from MECP2-deficient hiPSC neural cultures lack this capability. These data indicate that exosomes carry signaling information required to regulate neural circuit development.
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44
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Harasztosi C, Gummer AW. Different rates of endocytic activity and vesicle transport from the apical and synaptic poles of the outer hair cell. HNO 2019; 67:449-457. [PMID: 31073640 PMCID: PMC6538584 DOI: 10.1007/s00106-019-0674-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Background Intense endocytic activity at the apex of outer hair cells (OHCs)—the electromechanical cells of the cochlea—has been demonstrated using the vital plasma-membrane marker FM1-43 and confocal laser-scanning microscopy. Vesicular traffic toward the cell nucleus to distinct locations of the endoplasmic reticulum has also been shown. Objective The current study characterizes the dynamics of endocytic activity, as well as apicobasal and basoapical trafficking, using a local perfusion technique that we recently developed and published to visualize bidirectional trafficking in isolated bipolar cells. Materials and methods The fluorescent plasma-membrane markers FM1-43 (10 µM) and FM4-64 (10 µM), together with a fluid-phase marker, Lucifer yellow (50 µM), were used to label endocytosed vesicles in isolated OHCs of the guinea pig cochlea. Targets of endocytosed vesicles were examined with a fluorescent marker of subsurface cisternae, DiOC6 (0.87 µM). Single- and two-photon confocal laser-scanning microscopy was used to visualize labeled vesicles. Results The plasma-membrane markers presented more intense vesicle internalization at the synaptic pole than at the apical pole of the OHC. Intracellular basoapical vesicle trafficking was faster than apicobasal trafficking. Vesicles endocytosed at the synaptic pole were transcytosed to the endoplasmic reticulum system. An intracellular Lucifer yellow signal was not detected. Conclusion The larger endocytic fluorescent signals in the synaptic pole and the faster basoapical trafficking imply that membrane internalization and vesicle trafficking are more efficient at the synaptic pole than at the apical pole of the OHC.
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Affiliation(s)
- C Harasztosi
- Section of Physiological Acoustics and Communication, Faculty of Medicine, Eberhard Karls University Tübingen, Elfriede-Aulhorn-Str. 5, 72076, Tübingen, Germany
| | - A W Gummer
- Section of Physiological Acoustics and Communication, Faculty of Medicine, Eberhard Karls University Tübingen, Elfriede-Aulhorn-Str. 5, 72076, Tübingen, Germany.
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Richter KN, Patzelt C, Phan NTN, Rizzoli SO. Antibody-driven capture of synaptic vesicle proteins on the plasma membrane enables the analysis of their interactions with other synaptic proteins. Sci Rep 2019; 9:9231. [PMID: 31239503 PMCID: PMC6592915 DOI: 10.1038/s41598-019-45729-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Accepted: 06/13/2019] [Indexed: 01/07/2023] Open
Abstract
Many organelles from the secretory pathway fuse to the plasma membrane, to exocytose different cargoes. Their proteins are then retrieved from the plasma membrane by endocytosis, and the organelles are re-formed. It is generally unclear whether the organelle proteins colocalize when they are on the plasma membrane, or whether they disperse. To address this, we generated here a new approach, which we tested on synaptic vesicles, organelles that are known to exo- and endocytose frequently. We tagged the synaptotagmin molecules of newly exocytosed vesicles using clusters of primary and secondary antibodies targeted against the luminal domains of these molecules. The antibody clusters are too large for endocytosis, and thus sequestered the synaptotagmin molecules on the plasma membrane. Immunostainings for other synaptic molecules then revealed whether they colocalized with the sequestered synaptotagmin molecules. We suggest that such assays may be in the future extended to other cell types and other organelles.
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Affiliation(s)
- Katharina N Richter
- Institute for Neuro- and Sensory Physiology, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany.
| | - Christina Patzelt
- Institute for Neuro- and Sensory Physiology, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
| | - Nhu T N Phan
- Institute for Neuro- and Sensory Physiology, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
| | - Silvio O Rizzoli
- Institute for Neuro- and Sensory Physiology, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany.
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Viral Transfer of Mini-Otoferlins Partially Restores the Fast Component of Exocytosis and Uncovers Ultrafast Endocytosis in Auditory Hair Cells of Otoferlin Knock-Out Mice. J Neurosci 2019; 39:3394-3411. [PMID: 30833506 DOI: 10.1523/jneurosci.1550-18.2018] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 10/24/2018] [Accepted: 11/02/2018] [Indexed: 01/06/2023] Open
Abstract
Transmitter release at auditory inner hair cell (IHC) ribbon synapses involves exocytosis of glutamatergic vesicles during voltage activation of L-type Cav1.3 calcium channels. At these synapses, the fast and indefatigable release of synaptic vesicles by IHCs is controlled by otoferlin, a six-C2-domain (C2-ABCDEF) protein that functions as a high-affinity Ca2+ sensor. The molecular events by which each otoferlin C2 domain contributes to the regulation of the synaptic vesicle cycle in IHCs are still incompletely understood. Here, we investigate their role using a cochlear viral cDNA transfer approach in vivo, where IHCs of mouse lacking otoferlin (Otof -/- mice of both sexes) were virally transduced with cDNAs of various mini-otoferlins. Using patch-clamp recordings and membrane capacitance measurements, we show that the viral transfer of mini-otoferlin containing C2-ACEF, C2-EF, or C2-DEF partially restores the fast exocytotic component in Otof -/- mouse IHCs. The restoration was much less efficient with C2-ACDF, underlining the importance of the C2-EF domain. None of the mini-otoferlins tested restored the sustained component of vesicle release, explaining the absence of hearing recovery. The restoration of the fast exocytotic component in the transduced Otof -/- IHCs was also associated with a recovery of Ca2+ currents with normal amplitude and fast time inactivation, confirming that the C-terminal C2 domains of otoferlin are essential for normal gating of Cav1.3 channels. Finally, the reintroduction of the mini-otoferlins C2-EF, C2-DEF, or C2-ACEF allowed us to uncover and characterize for the first time a dynamin-dependent ultrafast endocytosis in IHCs.SIGNIFICANCE STATEMENT Otoferlin, a large six-C2-domain protein, is essential for synaptic vesicle exocytosis at auditory hair cell ribbon synapses. Here, we show that the viral expression of truncated forms of otoferlin (C2-EF, C2-DEF, and C2-ACEF) can partially rescue the fast and transient release component of exocytosis in mouse hair cells lacking otoferlin, yet cannot sustain exocytosis after long repeated stimulation. Remarkably, these hair cells also display a dynamin-dependent ultrafast endocytosis. Overall, our study uncovers the pleiotropic role of otoferlin in the hair cell synaptic vesicle cycle, notably in triggering both ultrafast exocytosis and endocytosis and recruiting synaptic vesicles to the active zone.
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Kroll J, Jaime Tobón LM, Vogl C, Neef J, Kondratiuk I, König M, Strenzke N, Wichmann C, Milosevic I, Moser T. Endophilin-A regulates presynaptic Ca 2+ influx and synaptic vesicle recycling in auditory hair cells. EMBO J 2019; 38:e100116. [PMID: 30733243 PMCID: PMC6396150 DOI: 10.15252/embj.2018100116] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 12/17/2018] [Accepted: 12/20/2018] [Indexed: 12/20/2022] Open
Abstract
Ribbon synapses of cochlear inner hair cells (IHCs) operate with high rates of neurotransmission; yet, the molecular regulation of synaptic vesicle (SV) recycling at these synapses remains poorly understood. Here, we studied the role of endophilins-A1-3, endocytic adaptors with curvature-sensing and curvature-generating properties, in mouse IHCs. Single-cell RT-PCR indicated the expression of endophilins-A1-3 in IHCs, and immunoblotting confirmed the presence of endophilin-A1 and endophilin-A2 in the cochlea. Patch-clamp recordings from endophilin-A-deficient IHCs revealed a reduction of Ca2+ influx and exocytosis, which we attribute to a decreased abundance of presynaptic Ca2+ channels and impaired SV replenishment. Slow endocytic membrane retrieval, thought to reflect clathrin-mediated endocytosis, was impaired. Otoferlin, essential for IHC exocytosis, co-immunoprecipitated with purified endophilin-A1 protein, suggestive of a molecular interaction that might aid exocytosis-endocytosis coupling. Electron microscopy revealed lower SV numbers, but an increased occurrence of coated structures and endosome-like vacuoles at IHC active zones. In summary, endophilins regulate Ca2+ influx and promote SV recycling in IHCs, likely via coupling exocytosis to endocytosis, and contributing to membrane retrieval and SV reformation.
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Affiliation(s)
- Jana Kroll
- Synaptic Vesicle Dynamics Group, European Neuroscience Institute (ENI), University Medical Center Göttingen, Göttingen, Germany
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience, InnerEarLab and Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Göttingen Graduate School for Neuroscience and Molecular Biosciences, University of Göttingen, Göttingen, Germany
| | - Lina M Jaime Tobón
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Göttingen Graduate School for Neuroscience and Molecular Biosciences, University of Göttingen, Göttingen, Germany
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, Göttingen, Germany
| | - Christian Vogl
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, Göttingen, Germany
- Presynaptogenesis and Intracellular Transport in Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Jakob Neef
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, Göttingen, Germany
| | - Ilona Kondratiuk
- Synaptic Vesicle Dynamics Group, European Neuroscience Institute (ENI), University Medical Center Göttingen, Göttingen, Germany
| | - Melanie König
- Synaptic Vesicle Dynamics Group, European Neuroscience Institute (ENI), University Medical Center Göttingen, Göttingen, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
| | - Nicola Strenzke
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, Göttingen, Germany
- Auditory Systems Physiology Group and InnerEarLab, Department of Otolaryngology, University of Göttingen Medical Center, Göttingen, Germany
| | - Carolin Wichmann
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience, InnerEarLab and Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, Göttingen, Germany
| | - Ira Milosevic
- Synaptic Vesicle Dynamics Group, European Neuroscience Institute (ENI), University Medical Center Göttingen, Göttingen, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
| | - Tobias Moser
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, Göttingen, Germany
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MemBright: A Family of Fluorescent Membrane Probes for Advanced Cellular Imaging and Neuroscience. Cell Chem Biol 2019; 26:600-614.e7. [PMID: 30745238 DOI: 10.1016/j.chembiol.2019.01.009] [Citation(s) in RCA: 98] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 10/07/2018] [Accepted: 01/15/2019] [Indexed: 12/30/2022]
Abstract
The proper staining of the plasma membrane (PM) is critical in bioimaging as it delimits the cell. Herein, we developed MemBright, a family of six cyanine-based fluorescent turn-on PM probes that emit from orange to near infrared when reaching the PM, and enable homogeneous and selective PM staining with excellent contrast in mono- and two-photon microscopy. These probes are compatible with long-term live-cell imaging and immunostaining. Moreover, MemBright label neurons in a brighter manner than surrounding cells, allowing identification of neurons in acute brain tissue sections and neuromuscular junctions without any use of transfection or transgenic animals. In addition, MemBright probes were used in super-resolution imaging to unravel the neck of dendritic spines. 3D multicolor dSTORM in combination with immunostaining revealed en-passant synapse displaying endogenous glutamate receptors clustered at the axonal-dendritic contact site. MemBright probes thus constitute a universal toolkit for cell biology and neuroscience biomembrane imaging with a variety of microscopy techniques. VIDEO ABSTRACT.
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Bullen A, Anderson L, Bakay W, Forge A. Localized disorganization of the cochlear inner hair cell synaptic region after noise exposure. Biol Open 2019; 8:bio.038547. [PMID: 30504133 PMCID: PMC6361218 DOI: 10.1242/bio.038547] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The prevalence and importance of hearing damage caused by noise levels not previously thought to cause permanent hearing impairment has become apparent in recent years. The damage to, and loss of, afferent terminals of auditory nerve fibres at the cochlear inner hair cell has been well established, but the effects of noise exposure and terminal loss on the inner hair cell are less known. Using three-dimensional structural studies in mice we have examined the consequences of afferent terminal damage on inner hair cell morphology and intracellular structure. We identified a structural phenotype in the pre-synaptic regions of these damaged hair cells that persists for four weeks after noise exposure, and demonstrates a specific dysregulation of the synaptic vesicle recycling pathway. We show evidence of a failure in regeneration of vesicles from small membrane cisterns in damaged terminals, resulting from a failure of separation of small vesicle buds from the larger cisternal membranes.
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Jelínková A, Malínská K, Petrášek J. Using FM Dyes to Study Endomembranes and Their Dynamics in Plants and Cell Suspensions. Methods Mol Biol 2019; 1992:173-187. [PMID: 31148038 DOI: 10.1007/978-1-4939-9469-4_11] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
FM (Fei-Mao) styryl dyes are commonly used for the fluorescence imaging of plasma membrane (PM) and endocytosis in vivo. Thanks to their amphiphilic character, these dyes are incorporated in the outer leaflet of the PM lipid bilayer and emit fluorescence in its hydrophobic environment. The endocytic pathway of FM dye uptake starts with rapid PM staining and continues in PM invaginations and membrane vesicles during endocytosis, followed by staining of trans-Golgi network (TGN) and ending in tonoplast (vacuolar membrane). FM dyes do not stain endoplasmic reticulum and nuclear membrane. The time-lapse fluorescence microscopy could track endocytic vesicles and characterize the rate of endocytosis in vivo. On the other hand, fixable FM dyes (FX) can be used for the visualization of particular steps in the FM dye uptake in situ. Staining with FM dyes and subsequent microscopic observations could be performed on both tissue and cellular level. Here, we describe simple procedures for the effective FM dye staining and destaining in root tip of Arabidopsis thaliana seedlings and suspension-cultured tobacco cells.
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Affiliation(s)
- Adriana Jelínková
- Institute of Experimental Botany of the Czech Academy of Sciences, Prague, Czech Republic.
| | - Kateřina Malínská
- Institute of Experimental Botany of the Czech Academy of Sciences, Prague, Czech Republic
| | - Jan Petrášek
- Institute of Experimental Botany of the Czech Academy of Sciences, Prague, Czech Republic
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
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