1
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Sun Y, Yeam A, Kuo J, Iwamoto Y, Hu G, Drubin DG. The conserved protein adaptors CALM/AP180 and FCHo1/2 cooperatively recruit Eps15 to promote the initiation of clathrin-mediated endocytosis in yeast. PLoS Biol 2024; 22:e3002833. [PMID: 39316607 DOI: 10.1371/journal.pbio.3002833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Accepted: 09/05/2024] [Indexed: 09/26/2024] Open
Abstract
Clathrin-mediated endocytosis (CME) is a critical trafficking process that begins when an elaborate endocytic protein network is established at the plasma membrane. Interaction of early endocytic proteins with anionic phospholipids and/or cargo has been suggested to trigger CME initiation. However, the exact mechanism by which CME sites are initiated has not been fully elucidated. In the budding yeast Saccharomyces cerevisiae, higher levels of anionic phospholipids and cargo molecules exist in the newly formed daughter cell compared to the levels in the mother cell during polarized growth. Taking advantage of this asymmetry, we quantitatively compared CME proteins in S. cerevisiae mother versus daughter cells, observing differences in the dynamics and composition of key endocytic proteins. Our results show that CME site initiation occurs preferentially on regions of the plasma membrane with a relatively higher density of endocytic cargo and/or acidic phospholipids. Furthermore, our combined live cell-imaging and yeast genetics analysis provided evidence for a molecular mechanism in which CME sites are initiated when Yap1801 and Yap1802 (yeast CALM/AP180) and Syp1 (yeast FCHo1/2) coordinate with anionic phospholipids and cargo molecules to trigger Ede1 (yeast Eps15)-centric CME initiation complex assembly at the plasma membrane.
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Affiliation(s)
- Yidi Sun
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Albert Yeam
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Jonathan Kuo
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Yuichiro Iwamoto
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Gean Hu
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - David G Drubin
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
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2
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Kozlov MM, Taraska JW. Generation of nanoscopic membrane curvature for membrane trafficking. Nat Rev Mol Cell Biol 2023; 24:63-78. [PMID: 35918535 DOI: 10.1038/s41580-022-00511-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/20/2022] [Indexed: 11/09/2022]
Abstract
Curved membranes are key features of intracellular organelles, and their generation involves dynamic protein complexes. Here we describe the fundamental mechanisms such as the hydrophobic insertion, scaffolding and crowding mechanisms these proteins use to produce membrane curvatures and complex shapes required to form intracellular organelles and vesicular structures involved in endocytosis and secretion. For each mechanism, we discuss its cellular functions as well as the underlying physical principles and the specific membrane properties required for the mechanism to be feasible. We propose that the integration of individual mechanisms into a highly controlled, robust process of curvature generation often relies on the assembly of proteins into coats. How cells unify and organize the curvature-generating factors at the nanoscale is presented for three ubiquitous coats central for membrane trafficking in eukaryotes: clathrin-coated pits, caveolae, and COPI and COPII coats. The emerging theme is that these coats arrange and coordinate curvature-generating factors in time and space to dynamically shape membranes to accomplish membrane trafficking within cells.
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Affiliation(s)
- Michael M Kozlov
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
| | - Justin W Taraska
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
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3
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Smith SM, Smith CJ. Capturing the mechanics of clathrin-mediated endocytosis. Curr Opin Struct Biol 2022; 75:102427. [PMID: 35872561 DOI: 10.1016/j.sbi.2022.102427] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 06/13/2022] [Accepted: 06/16/2022] [Indexed: 02/01/2023]
Abstract
Clathrin-mediated endocytosis enables selective uptake of molecules into cells in response to changing cellular needs. It occurs through assembly of coat components around the plasma membrane that determine vesicle contents and facilitate membrane bending to form a clathrin-coated transport vesicle. In this review we discuss recent cryo-electron microscopy structures that have captured a series of events in the life cycle of a clathrin-coated vesicle. Both single particle analysis and tomography approaches have revealed details of the clathrin lattice structure itself, how AP2 may interface with clathrin within a coated vesicle and the importance of PIP2 binding for assembly of the yeast adaptors Sla2 and Ent1 on the membrane. Within cells, cryo-electron tomography of clathrin in flat lattices and high-speed AFM studies provided new insights into how clathrin morphology can adapt during CCV formation. Thus, key mechanical processes driving clathrin-mediated endocytosis have been captured through multiple techniques working in partnership.
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Affiliation(s)
- Sarah M Smith
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Corinne J Smith
- School of Life Sciences, University of Warwick, Coventry, UK.
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4
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Zaccai NR, Kadlecova Z, Dickson VK, Korobchevskaya K, Kamenicky J, Kovtun O, Umasankar PK, Wrobel AG, Kaufman JGG, Gray SR, Qu K, Evans PR, Fritzsche M, Sroubek F, Höning S, Briggs JAG, Kelly BT, Owen DJ, Traub LM. FCHO controls AP2's initiating role in endocytosis through a PtdIns(4,5)P 2-dependent switch. SCIENCE ADVANCES 2022; 8:eabn2018. [PMID: 35486718 PMCID: PMC9054013 DOI: 10.1126/sciadv.abn2018] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 03/11/2022] [Indexed: 06/14/2023]
Abstract
Clathrin-mediated endocytosis (CME) is the main mechanism by which mammalian cells control their cell surface proteome. Proper operation of the pivotal CME cargo adaptor AP2 requires membrane-localized Fer/Cip4 homology domain-only proteins (FCHO). Here, live-cell enhanced total internal reflection fluorescence-structured illumination microscopy shows that FCHO marks sites of clathrin-coated pit (CCP) initiation, which mature into uniform-sized CCPs comprising a central patch of AP2 and clathrin corralled by an FCHO/Epidermal growth factor potential receptor substrate number 15 (Eps15) ring. We dissect the network of interactions between the FCHO interdomain linker and AP2, which concentrates, orients, tethers, and partially destabilizes closed AP2 at the plasma membrane. AP2's subsequent membrane deposition drives its opening, which triggers FCHO displacement through steric competition with phosphatidylinositol 4,5-bisphosphate, clathrin, cargo, and CME accessory factors. FCHO can now relocate toward a CCP's outer edge to engage and activate further AP2s to drive CCP growth/maturation.
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Affiliation(s)
- Nathan R. Zaccai
- CIMR, University of Cambridge, Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Zuzana Kadlecova
- CIMR, University of Cambridge, Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | | | - Kseniya Korobchevskaya
- Kennedy Institute of Rheumatology, University of Oxford, Roosevelt Drive, Oxford OX3 7FY, UK
| | - Jan Kamenicky
- Czech Academy of Sciences, Institute of Information Theory and Automation, Pod Vodarenskou vezi 4, 182 08 Prague 8, Czech Republic
| | - Oleksiy Kovtun
- MRC LMB Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Perunthottathu K. Umasankar
- Intracellular Trafficking Laboratory, Transdisciplinary Biology Research Program, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, Kerala, India
| | - Antoni G. Wrobel
- CIMR, University of Cambridge, Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | | | - Sally R. Gray
- CIMR, University of Cambridge, Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Kun Qu
- MRC LMB Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | | | - Marco Fritzsche
- Kennedy Institute of Rheumatology, University of Oxford, Roosevelt Drive, Oxford OX3 7FY, UK
- Rosalind Franklin Institute, Harwell Campus, Didcot, UK
| | - Filip Sroubek
- Czech Academy of Sciences, Institute of Information Theory and Automation, Pod Vodarenskou vezi 4, 182 08 Prague 8, Czech Republic
| | - Stefan Höning
- Institute for Biochemistry I, Medical Faculty, University of Cologne, Joseph-Stelzmann-Straße 52, 50931 Cologne, Germany
| | - John A. G. Briggs
- MRC LMB Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
- Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Bernard T. Kelly
- CIMR, University of Cambridge, Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - David J. Owen
- CIMR, University of Cambridge, Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Linton M. Traub
- Department of Cell Biology, University of Pittsburgh School of Medicine, 3500 Terrace Street, Pittsburgh, PA, USA
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5
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Partlow EA, Cannon KS, Hollopeter G, Baker RW. Structural basis of an endocytic checkpoint that primes the AP2 clathrin adaptor for cargo internalization. Nat Struct Mol Biol 2022; 29:339-347. [PMID: 35347313 PMCID: PMC10116491 DOI: 10.1038/s41594-022-00749-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 02/16/2022] [Indexed: 11/08/2022]
Abstract
Clathrin-mediated endocytosis (CME) is the main route of internalization from the plasma membrane. It is known that the heterotetrameric AP2 clathrin adaptor must open to simultaneously engage membrane and endocytic cargo, yet it is unclear how transmembrane cargos are captured to catalyze CME. Using cryogenic-electron microscopy, we discover a new way in which mouse AP2 can reorganize to expose membrane- and cargo-binding pockets, which is not observed in clathrin-coated structures. Instead, it is stimulated by endocytic pioneer proteins called muniscins, which do not enter vesicles. Muniscin-engaged AP2 is primed to rearrange into the vesicle-competent conformation on binding the tyrosine cargo internalization motif (YxxΦ). We propose adaptor priming as a checkpoint to ensure cargo internalization.
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Affiliation(s)
- Edward A Partlow
- Department of Molecular Medicine, Cornell University, Ithaca, NY, USA
| | - Kevin S Cannon
- Department of Biochemistry and Biophysics, University of North Carolina (UNC) Chapel Hill School of Medicine, Chapel Hill, NC, USA
| | | | - Richard W Baker
- Department of Biochemistry and Biophysics, University of North Carolina (UNC) Chapel Hill School of Medicine, Chapel Hill, NC, USA.
- UNC Lineberger Comprehensive Cancer Center, University of North Carolina (UNC) Chapel Hill School of Medicine, Chapel Hill, NC, USA.
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6
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Ramesh ST, Navyasree KV, Sah S, Ashok AB, Qathoon N, Mohanty S, Swain RK, Umasankar PK. BMP2K phosphorylates AP-2 and regulates clathrin-mediated endocytosis. Traffic 2021; 22:377-396. [PMID: 34480404 DOI: 10.1111/tra.12814] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 08/31/2021] [Accepted: 09/01/2021] [Indexed: 01/29/2023]
Abstract
Phosphorylation of the central adaptor protein complex, AP-2 is pivotal for clathrin-mediated endocytosis (CME). Here, we uncover the role of an uncharacterized kinase (BMP-2 inducible kinase-BMP2K) in AP-2 phosphorylation. We demonstrate that BMP2K can phosphorylate AP-2 in vitro and in vivo. Functional impairment of BMP2K impedes AP-2 phosphorylation leading to defects in clathrin-coated pit (CCP) morphology and cargo internalization. BMP2K engages AP-2 via its extended C-terminus and this interaction is important for its CCP localization and function. Notably, endogenous BMP2K levels decline upon functional impairment of AP-2 indicating AP-2 dependent BMP2K stabilization in cells. Further, functional inactivation of BMP2K in zebrafish embryos yields gastrulation phenotypes which mirror AP-2 loss-of-function suggesting physiological relevance of BMP2K in vertebrates. Together, our findings propose involvement of a novel kinase in AP-2 phosphorylation and in the operation of CME.
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Affiliation(s)
- Shikha T Ramesh
- Intracellular Trafficking Laboratory, Transdisciplinary Biology Research Program, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, Kerala, India.,Centre for Doctoral Studies, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Kolaparamba V Navyasree
- Intracellular Trafficking Laboratory, Transdisciplinary Biology Research Program, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, Kerala, India.,Centre for Doctoral Studies, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Sneha Sah
- Intracellular Trafficking Laboratory, Transdisciplinary Biology Research Program, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, Kerala, India
| | - Anjitha B Ashok
- Intracellular Trafficking Laboratory, Transdisciplinary Biology Research Program, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, Kerala, India
| | - Nishada Qathoon
- Intracellular Trafficking Laboratory, Transdisciplinary Biology Research Program, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, Kerala, India
| | | | | | - Perunthottathu K Umasankar
- Intracellular Trafficking Laboratory, Transdisciplinary Biology Research Program, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, Kerala, India
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7
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Mishra R, Sengül GF, Candiello E, Schu P. Synaptic AP2 CCV life cycle regulation by the Eps15, ITSN1, Sgip1/AP2, synaptojanin1 interactome. Sci Rep 2021; 11:8007. [PMID: 33850201 PMCID: PMC8044098 DOI: 10.1038/s41598-021-87591-3] [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: 08/07/2020] [Accepted: 03/30/2021] [Indexed: 11/18/2022] Open
Abstract
The AP1/σ1B knockout causes impaired synaptic vesicle recycling and enhanced protein sorting into endosomes, leading to severe intellectual disability. These disturbances in synaptic protein sorting induce as a secondary phenotype the upregulation of AP2 CCV mediated endocytosis. Synapses contain canonical AP2 CCV and AP2 CCV with a more stable coat and thus extended life time. In AP1/σ1B knockout synapses, pool sizes of both CCV classes are doubled. Additionally, stable CCV of the knockout are more stabilised than stable wt CCV. One mechanism responsible for enhanced CCV stabilisation is the reduction of synaptojanin1 CCV levels, the PI-4,5-P2 phosphatase essential for AP2 membrane dissociation. To identify mechanisms regulating synaptojanin1 recruitment, we compared synaptojanin1 CCV protein interactome levels and CCV protein interactions between both CCV classes from wt and knockout mice. We show that ITSN1 determines synaptojanin1 CCV levels. Sgip1/AP2 excess hinders synaptojanin1 binding to ITSN1, further lowering its levels. ITSN1 levels are determined by Eps15, not Eps15L1. In addition, the data reveal that reduced amounts of pacsin1 can be counter balanced by its enhanced activation. These data exemplify the complexity of CCV life cycle regulation and indicate how cargo proteins determine the life cycle of their CCV.
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Affiliation(s)
- R Mishra
- Department of Cellular Biochemistry, University Medical Center, Georg-August University Göttingen, Humboldtallee 23, 37073, Göttingen, Germany
- Department of Clinical Neurosciences, John Van Geest Centre for Brain Repair, University of Cambridge, Cambridge, England, UK
| | - G F Sengül
- Department of Cellular Biochemistry, University Medical Center, Georg-August University Göttingen, Humboldtallee 23, 37073, Göttingen, Germany
| | - E Candiello
- Department of Cellular Biochemistry, University Medical Center, Georg-August University Göttingen, Humboldtallee 23, 37073, Göttingen, Germany
- Institute for Cancer Research and Treatment (IRCC), Turin, Italy
| | - P Schu
- Department of Cellular Biochemistry, University Medical Center, Georg-August University Göttingen, Humboldtallee 23, 37073, Göttingen, Germany.
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8
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Winkler J, De Meyer A, Mylle E, Storme V, Grones P, Van Damme D. Nanobody-Dependent Delocalization of Endocytic Machinery in Arabidopsis Root Cells Dampens Their Internalization Capacity. FRONTIERS IN PLANT SCIENCE 2021; 12:538580. [PMID: 33815429 PMCID: PMC8018273 DOI: 10.3389/fpls.2021.538580] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 02/23/2021] [Indexed: 05/08/2023]
Abstract
Plant cells perceive and adapt to an ever-changing environment by modifying their plasma membrane (PM) proteome. Whereas secretion deposits new integral membrane proteins, internalization by endocytosis removes membrane proteins and associated ligands, largely with the aid of adaptor protein (AP) complexes and the scaffolding molecule clathrin. Two AP complexes function in clathrin-mediated endocytosis at the PM in plant cells, the heterotetrameric AP-2 complex and the hetero-octameric TPLATE complex (TPC). Whereas single subunit mutants in AP-2 develop into viable plants, genetic mutation of a single TPC subunit causes fully penetrant male sterility and silencing single subunits leads to seedling lethality. To address TPC function in somatic root cells, while minimizing indirect effects on plant growth, we employed nanobody-dependent delocalization of a functional, GFP-tagged TPC subunit, TML, in its respective homozygous genetic mutant background. In order to decrease the amount of functional TPC at the PM, we targeted our nanobody construct to the mitochondria and fused it to TagBFP2 to visualize it independently of its bait. We furthermore limited the effect of our delocalization to those tissues that are easily accessible for live-cell imaging by expressing it from the PIN2 promoter, which is active in root epidermal and cortex cells. With this approach, we successfully delocalized TML from the PM. Moreover, we also show co-recruitment of TML-GFP and AP2A1-TagRFP to the mitochondria, suggesting that our approach delocalized complexes, rather than individual adaptor complex subunits. In line with the specific expression domain, we only observed minor effects on root growth, yet realized a clear reduction of endocytic flux in epidermal root cells. Nanobody-dependent delocalization in plants, here exemplified using a TPC subunit, has the potential to be widely applicable to achieve specific loss-of-function analysis of otherwise lethal mutants.
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Affiliation(s)
- Joanna Winkler
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Andreas De Meyer
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Evelien Mylle
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Veronique Storme
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Peter Grones
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Daniël Van Damme
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
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9
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Aridor M, Owen DJ. Linton Mark Traub (1962-2020). J Cell Biol 2021; 220:e202011169. [PMID: 33404605 PMCID: PMC7791343 DOI: 10.1083/jcb.202011169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Meir Aridor and David Owen discuss the life and achievements of Linton Traub, who passed away on October 19, 2020.
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Affiliation(s)
- Meir Aridor
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - David J. Owen
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
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10
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Schneider F, Sych T, Eggeling C, Sezgin E. Influence of nanobody binding on fluorescence emission, mobility, and organization of GFP-tagged proteins. iScience 2021; 24:101891. [PMID: 33364580 PMCID: PMC7753935 DOI: 10.1016/j.isci.2020.101891] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 11/02/2020] [Accepted: 12/01/2020] [Indexed: 12/22/2022] Open
Abstract
Advanced fluorescence microscopy studies require specific and monovalent molecular labeling with bright and photostable fluorophores. This necessity led to the widespread use of fluorescently labeled nanobodies against commonly employed fluorescent proteins (FPs). However, very little is known how these nanobodies influence their target molecules. Here, we tested commercially available nanobodies and observed clear changes of the fluorescence properties, mobility and organization of green fluorescent protein (GFP) tagged proteins after labeling with the anti-GFP nanobody. Intriguingly, we did not observe any co-diffusion of fluorescently labeled nanobodies with the GFP-labeled proteins. Our results suggest significant binding of the nanobodies to a non-emissive, likely oligomerized, form of the FPs, promoting disassembly into monomeric form after binding. Our findings have significant implications on the application of nanobodies and GFP labeling for studying dynamic and quantitative protein organization in the plasma membrane of living cells using advanced imaging techniques.
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Affiliation(s)
- Falk Schneider
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Taras Sych
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, 171 65 Solna, Sweden
| | - Christian Eggeling
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
- Institute of Applied Optics and Biophysics, Friedrich-Schiller-University Jena, Max-Wien Platz 4, 07743 Jena, Germany
- Leibniz Institute of Photonic Technology e.V., Albert-Einstein-Straße 9, 07745 Jena, Germany
- Jena Center of Soft Matters, Friedrich-Schiller-University Jena, Philosophenweg 7, 07743 Jena, Germany
| | - Erdinc Sezgin
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, 171 65 Solna, Sweden
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11
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Winkler J, De Meyer A, Mylle E, Storme V, Grones P, Van Damme D. Nanobody-Dependent Delocalization of Endocytic Machinery in Arabidopsis Root Cells Dampens Their Internalization Capacity. FRONTIERS IN PLANT SCIENCE 2021. [PMID: 33815429 DOI: 10.1101/2020.02.27.968446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Plant cells perceive and adapt to an ever-changing environment by modifying their plasma membrane (PM) proteome. Whereas secretion deposits new integral membrane proteins, internalization by endocytosis removes membrane proteins and associated ligands, largely with the aid of adaptor protein (AP) complexes and the scaffolding molecule clathrin. Two AP complexes function in clathrin-mediated endocytosis at the PM in plant cells, the heterotetrameric AP-2 complex and the hetero-octameric TPLATE complex (TPC). Whereas single subunit mutants in AP-2 develop into viable plants, genetic mutation of a single TPC subunit causes fully penetrant male sterility and silencing single subunits leads to seedling lethality. To address TPC function in somatic root cells, while minimizing indirect effects on plant growth, we employed nanobody-dependent delocalization of a functional, GFP-tagged TPC subunit, TML, in its respective homozygous genetic mutant background. In order to decrease the amount of functional TPC at the PM, we targeted our nanobody construct to the mitochondria and fused it to TagBFP2 to visualize it independently of its bait. We furthermore limited the effect of our delocalization to those tissues that are easily accessible for live-cell imaging by expressing it from the PIN2 promoter, which is active in root epidermal and cortex cells. With this approach, we successfully delocalized TML from the PM. Moreover, we also show co-recruitment of TML-GFP and AP2A1-TagRFP to the mitochondria, suggesting that our approach delocalized complexes, rather than individual adaptor complex subunits. In line with the specific expression domain, we only observed minor effects on root growth, yet realized a clear reduction of endocytic flux in epidermal root cells. Nanobody-dependent delocalization in plants, here exemplified using a TPC subunit, has the potential to be widely applicable to achieve specific loss-of-function analysis of otherwise lethal mutants.
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Affiliation(s)
- Joanna Winkler
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Andreas De Meyer
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Evelien Mylle
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Veronique Storme
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Peter Grones
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Daniël Van Damme
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
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12
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Soetens E, Ballegeer M, Saelens X. An Inside Job: Applications of Intracellular Single Domain Antibodies. Biomolecules 2020; 10:biom10121663. [PMID: 33322697 PMCID: PMC7764588 DOI: 10.3390/biom10121663] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 12/09/2020] [Accepted: 12/10/2020] [Indexed: 02/06/2023] Open
Abstract
Sera of camelid species contain a special kind of antibody that consists only of heavy chains. The variable antigen binding domain of these heavy chain antibodies can be expressed as a separate entity, called a single domain antibody that is characterized by its small size, high solubility and oftentimes exceptional stability. Because of this, most single domain antibodies fold correctly when expressed in the reducing environment of the cytoplasm, and thereby retain their antigen binding specificity. Single domain antibodies can thus be used to target a broad range of intracellular proteins. Such intracellular single domain antibodies are also known as intrabodies, and have proven to be highly useful tools for basic research by allowing visualization, disruption and even targeted degradation of intracellular proteins. Furthermore, intrabodies can be used to uncover prospective new therapeutic targets and have the potential to be applied in therapeutic settings in the future. In this review we provide a brief overview of recent advances in the field of intracellular single domain antibodies, focusing on their use as research tools and potential therapeutic applications. Special attention is given to the available methods that allow delivery of single domain antibodies into cells.
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Affiliation(s)
- Eline Soetens
- VIB-UGent Center for Medical Biotechnology, VIB, B-9052 Ghent, Belgium; (E.S.); (M.B.)
- Department of Biochemistry and Microbiology, Ghent University, B-9000 Ghent, Belgium
| | - Marlies Ballegeer
- VIB-UGent Center for Medical Biotechnology, VIB, B-9052 Ghent, Belgium; (E.S.); (M.B.)
- Department of Biochemistry and Microbiology, Ghent University, B-9000 Ghent, Belgium
| | - Xavier Saelens
- VIB-UGent Center for Medical Biotechnology, VIB, B-9052 Ghent, Belgium; (E.S.); (M.B.)
- Department of Biochemistry and Microbiology, Ghent University, B-9000 Ghent, Belgium
- Correspondence:
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de Beer MA, Giepmans BNG. Nanobody-Based Probes for Subcellular Protein Identification and Visualization. Front Cell Neurosci 2020; 14:573278. [PMID: 33240044 PMCID: PMC7667270 DOI: 10.3389/fncel.2020.573278] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 10/05/2020] [Indexed: 12/14/2022] Open
Abstract
Understanding how building blocks of life contribute to physiology is greatly aided by protein identification and cellular localization. The two main labeling approaches developed over the past decades are labeling with antibodies such as immunoglobulin G (IgGs) or use of genetically encoded tags such as fluorescent proteins. However, IgGs are large proteins (150 kDa), which limits penetration depth and uncertainty of target position caused by up to ∼25 nm distance of the label created by the chosen targeting approach. Additionally, IgGs cannot be easily recombinantly modulated and engineered as part of fusion proteins because they consist of multiple independent translated chains. In the last decade single domain antigen binding proteins are being explored in bioscience as a tool in revealing molecular identity and localization to overcome limitations by IgGs. These nanobodies have several potential benefits over routine applications. Because of their small size (15 kDa), nanobodies better penetrate during labeling procedures and improve resolution. Moreover, nanobodies cDNA can easily be fused with other cDNA. Multidomain proteins can thus be easily engineered consisting of domains for targeting (nanobodies) and visualization by fluorescence microscopy (fluorescent proteins) or electron microscopy (based on certain enzymes). Additional modules for e.g., purification are also easily added. These nanobody-based probes can be applied in cells for live-cell endogenous protein detection or may be purified prior to use on molecules, cells or tissues. Here, we present the current state of nanobody-based probes and their implementation in microscopy, including pitfalls and potential future opportunities.
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Affiliation(s)
- Marit A de Beer
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Ben N G Giepmans
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
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Zhang C, Ötjengerdes RM, Roewe J, Mejias R, Marschall ALJ. Applying Antibodies Inside Cells: Principles and Recent Advances in Neurobiology, Virology and Oncology. BioDrugs 2020; 34:435-462. [PMID: 32301049 PMCID: PMC7391400 DOI: 10.1007/s40259-020-00419-w] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
To interfere with cell function, many scientists rely on methods that target DNA or RNA due to the ease with which they can be applied. Proteins are usually the final executors of function but are targeted only indirectly by these methods. Recent advances in targeted degradation of proteins based on proteolysis-targeting chimaeras (PROTACs), ubiquibodies, deGradFP (degrade Green Fluorescent Protein) and other approaches have demonstrated the potential of interfering directly at the protein level for research and therapy. Proteins can be targeted directly and very specifically by antibodies, but using antibodies inside cells has so far been considered to be challenging. However, it is possible to deliver antibodies or other proteins into the cytosol using standard laboratory equipment. Physical methods such as electroporation have been demonstrated to be efficient and validated thoroughly over time. The expression of intracellular antibodies (intrabodies) inside cells is another way to interfere with intracellular targets at the protein level. Methodological strategies to target the inside of cells with antibodies, including delivered antibodies and expressed antibodies, as well as applications in the research areas of neurobiology, viral infections and oncology, are reviewed here. Antibodies have already been used to interfere with a wide range of intracellular targets. Disease-related targets included proteins associated with neurodegenerative diseases such as Parkinson's disease (α-synuclein), Alzheimer's disease (amyloid-β) or Huntington's disease (mutant huntingtin [mHtt]). The applications of intrabodies in the context of viral infections include targeting proteins associated with HIV (e.g. HIV1-TAT, Rev, Vif, gp41, gp120, gp160) and different oncoviruses such as human papillomavirus (HPV), hepatitis B virus (HBV), hepatitis C virus (HCV) and Epstein-Barr virus, and they have been used to interfere with various targets related to different processes in cancer, including oncogenic pathways, proliferation, cell cycle, apoptosis, metastasis, angiogenesis or neo-antigens (e.g. p53, human epidermal growth factor receptor-2 [HER2], signal transducer and activator of transcription 3 [STAT3], RAS-related RHO-GTPase B (RHOB), cortactin, vascular endothelial growth factor receptor 2 [VEGFR2], Ras, Bcr-Abl). Interfering at the protein level allows questions to be addressed that may remain unanswered using alternative methods. This review addresses why direct targeting of proteins allows unique insights, what is currently feasible in vitro, and how this relates to potential therapeutic applications.
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Affiliation(s)
- Congcong Zhang
- Georg-Speyer-Haus, Institute for Tumor Biology and Experimental Therapy, Frankfurt am Main, Germany
- German Cancer Consortium (DKTK), Partner Site Frankfurt/Mainz, Frankfurt am Main, Germany
- German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Rina M Ötjengerdes
- Hannover Medical School (MHH), Carl-Neuberg-Straße 1, 30625, Hannover, Germany
| | - Julian Roewe
- German Cancer Consortium (DKTK) Clinical Cooperation Unit (CCU) Neuroimmunology and Brain TumorImmunology (D170), German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Rebeca Mejias
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Andrea L J Marschall
- Technische Universität Braunschweig, Institute of Biochemistry, Biotechnology and Bioinformatics, Brunswick, Germany.
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Criscitiello MF, Kraev I, Lange S. Deiminated proteins in extracellular vesicles and serum of llama (Lama glama)-Novel insights into camelid immunity. Mol Immunol 2020; 117:37-53. [PMID: 31733447 PMCID: PMC7112542 DOI: 10.1016/j.molimm.2019.10.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 10/05/2019] [Accepted: 10/23/2019] [Indexed: 02/07/2023]
Abstract
Peptidylarginine deiminases (PADs) are phylogenetically conserved calcium-dependent enzymes which post-translationally convert arginine into citrulline in target proteins in an irreversible manner, causing functional and structural changes in target proteins. Protein deimination causes generation of neo-epitopes, affects gene regulation and also allows for protein moonlighting. Furthermore, PADs have been found to be a phylogenetically conserved regulator for extracellular vesicle (EVs) release. EVs are found in most body fluids and participate in cellular communication via transfer of cargo proteins and genetic material. In this study, post-translationally deiminated proteins in serum and serum-EVs are described for the first time in camelids, using the llama (Lama glama L. 1758) as a model animal. We report a poly-dispersed population of llama serum EVs, positive for phylogenetically conserved EV-specific markers and characterised by TEM. In serum, 103 deiminated proteins were overall identified, including key immune and metabolic mediators including complement components, immunoglobulin-based nanobodies, adiponectin and heat shock proteins. In serum, 60 deiminated proteins were identified that were not in EVs, and 25 deiminated proteins were found to be unique to EVs, with 43 shared deiminated protein hits between both serum and EVs. Deiminated histone H3, a marker of neutrophil extracellular trap formation, was also detected in llama serum. PAD homologues were identified in llama serum by Western blotting, via cross reaction with human PAD antibodies, and detected at an expected 70 kDa size. This is the first report of deiminated proteins in serum and EVs of a camelid species, highlighting a hitherto unrecognized post-translational modification in key immune and metabolic proteins in camelids, which may be translatable to and inform a range of human metabolic and inflammatory pathologies.
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Affiliation(s)
- Michael F Criscitiello
- Comparative Immunogenetics Laboratory, Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, 77843, USA; Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health Science Center, Texas A&M University, College Station, TX, 77843, USA.
| | - Igor Kraev
- Electron Microscopy Suite, Faculty of Science, Technology, Engineering and Mathematics, Open University, Milton Keynes, MK7 6AA, UK.
| | - Sigrun Lange
- Tissue Architecture and Regeneration Research Group, School of Life Sciences, University of Westminster, London W1W 6UW, UK.
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Endocytic Adaptor Proteins in Health and Disease: Lessons from Model Organisms and Human Mutations. Cells 2019; 8:cells8111345. [PMID: 31671891 PMCID: PMC6912373 DOI: 10.3390/cells8111345] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 10/24/2019] [Accepted: 10/25/2019] [Indexed: 12/11/2022] Open
Abstract
Cells need to exchange material and information with their environment. This is largely achieved via cell-surface receptors which mediate processes ranging from nutrient uptake to signaling responses. Consequently, their surface levels have to be dynamically controlled. Endocytosis constitutes a powerful mechanism to regulate the surface proteome and to recycle vesicular transmembrane proteins that strand at the plasma membrane after exocytosis. For efficient internalization, the cargo proteins need to be linked to the endocytic machinery via adaptor proteins such as the heterotetrameric endocytic adaptor complex AP-2 and a variety of mostly monomeric endocytic adaptors. In line with the importance of endocytosis for nutrient uptake, cell signaling and neurotransmission, animal models and human mutations have revealed that defects in these adaptors are associated with several diseases ranging from metabolic disorders to encephalopathies. This review will discuss the physiological functions of the so far known adaptor proteins and will provide a comprehensive overview of their links to human diseases.
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