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Hilton BJ, Griffin JM, Fawcett JW, Bradke F. Neuronal maturation and axon regeneration: unfixing circuitry to enable repair. Nat Rev Neurosci 2024; 25:649-667. [PMID: 39164450 DOI: 10.1038/s41583-024-00849-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/19/2024] [Indexed: 08/22/2024]
Abstract
Mammalian neurons lose the ability to regenerate their central nervous system axons as they mature during embryonic or early postnatal development. Neuronal maturation requires a transformation from a situation in which neuronal components grow and assemble to one in which these components are fixed and involved in the machinery for effective information transmission and computation. To regenerate after injury, neurons need to overcome this fixed state to reactivate their growth programme. A variety of intracellular processes involved in initiating or sustaining neuronal maturation, including the regulation of gene expression, cytoskeletal restructuring and shifts in intracellular trafficking, have been shown to prevent axon regeneration. Understanding these processes will contribute to the identification of targets to promote repair after injury or disease.
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Affiliation(s)
- Brett J Hilton
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, British Columbia, Canada.
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada.
| | - Jarred M Griffin
- Laboratory for Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - James W Fawcett
- Department of Clinical Neurosciences, John van Geest Centre for Brain Repair, University of Cambridge, Cambridge, UK.
- Centre for Reconstructive Neuroscience, Institute for Experimental Medicine Czech Academy of Science (CAS), Prague, Czechia.
| | - Frank Bradke
- Laboratory for Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.
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2
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Kuijpers M, Nguyen PT, Haucke V. The Endoplasmic Reticulum and Its Contacts: Emerging Roles in Axon Development, Neurotransmission, and Degeneration. Neuroscientist 2024; 30:545-559. [PMID: 36960757 PMCID: PMC11420577 DOI: 10.1177/10738584231162810] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/25/2023]
Abstract
The neuronal endoplasmic reticulum (ER) consists of a dynamic, tubular network that extends all the way from the soma into dendrites, axons, and synapses. This morphology gives rise to an enormous membrane surface area that, through the presence of tethering proteins, lipid transfer proteins, and ion channels, plays critical roles in local calcium regulation, membrane dynamics, and the supply of ions and lipids to other organelles. Here, we summarize recent advances that highlight the various roles of the neuronal ER in axonal growth, repair, and presynaptic function. We review the variety of contact sites between the ER and other axonal organelles and describe their influence on neurodevelopment and neurotransmission.
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Affiliation(s)
- Marijn Kuijpers
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
| | - Phuong T Nguyen
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Volker Haucke
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
- Department of Biology, Chemistry, Pharmacy, Freie Universität Berlin, Berlin, Germany
- Charité - Universitätsmedizin Berlin, Charitéplatz 1, Berlin, Germany
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3
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Wolf D, Röder C, Sendtner M, Lüningschrör P. An Essential Role for Calnexin in ER-Phagy and the Unfolded Protein Response. Cells 2024; 13:1498. [PMID: 39273068 PMCID: PMC11394613 DOI: 10.3390/cells13171498] [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: 07/26/2024] [Revised: 08/24/2024] [Accepted: 09/03/2024] [Indexed: 09/15/2024] Open
Abstract
ER-phagy is a specialized form of autophagy, defined by the lysosomal degradation of ER subdomains. ER-phagy has been implicated in relieving the ER from misfolded proteins during ER stress upon activation of the unfolded protein response (UPR). Here, we identified an essential role for the ER chaperone calnexin in regulating ER-phagy and the UPR in neurons. We showed that chemical induction of ER stress triggers ER-phagy in the somata and axons of primary cultured motoneurons. Under basal conditions, the depletion of calnexin leads to an enhanced ER-phagy in axons. However, upon ER stress induction, ER-phagy did not further increase in calnexin-deficient motoneurons. In addition to increased ER-phagy under basal conditions, we also detected an elevated proteasomal turnover of insoluble proteins, suggesting enhanced protein degradation by default. Surprisingly, we detected a diminished UPR in calnexin-deficient early cortical neurons under ER stress conditions. In summary, our data suggest a central role for calnexin in orchestrating both ER-phagy and the UPR to maintain protein homeostasis within the ER.
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Affiliation(s)
- Daniel Wolf
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Versbacher Str. 5, 97078 Würzburg, Germany
| | - Chiara Röder
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Versbacher Str. 5, 97078 Würzburg, Germany
| | - Michael Sendtner
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Versbacher Str. 5, 97078 Würzburg, Germany
| | - Patrick Lüningschrör
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Versbacher Str. 5, 97078 Würzburg, Germany
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4
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Maciąg F, Chhikara A, Heine M. Calcium channel signalling at neuronal endoplasmic reticulum-plasma membrane junctions. Biochem Soc Trans 2024; 52:1617-1629. [PMID: 38934485 DOI: 10.1042/bst20230819] [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: 03/27/2024] [Revised: 05/22/2024] [Accepted: 06/07/2024] [Indexed: 06/28/2024]
Abstract
Neurons are highly specialised cells that need to relay information over long distances and integrate signals from thousands of synaptic inputs. The complexity of neuronal function is evident in the morphology of their plasma membrane (PM), by far the most intricate of all cell types. Yet, within the neuron lies an organelle whose architecture adds another level to this morphological sophistication - the endoplasmic reticulum (ER). Neuronal ER is abundant in the cell body and extends to distant axonal terminals and postsynaptic dendritic spines. It also adopts specialised structures like the spine apparatus in the postsynapse and the cisternal organelle in the axon initial segment. At membrane contact sites (MCSs) between the ER and the PM, the two membranes come in close proximity to create hubs of lipid exchange and Ca2+ signalling called ER-PM junctions. The development of electron and light microscopy techniques extended our knowledge on the physiological relevance of ER-PM MCSs. Equally important was the identification of ER and PM partners that interact in these junctions, most notably the STIM-ORAI and VAP-Kv2.1 pairs. The physiological functions of ER-PM junctions in neurons are being increasingly explored, but their molecular composition and the role in the dynamics of Ca2+ signalling are less clear. This review aims to outline the current state of research on the topic of neuronal ER-PM contacts. Specifically, we will summarise the involvement of different classes of Ca2+ channels in these junctions, discuss their role in neuronal development and neuropathology and propose directions for further research.
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Affiliation(s)
- Filip Maciąg
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University, Hanns-Dieter Hüsch Weg 15, 55128 Mainz, Germany
| | - Arun Chhikara
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University, Hanns-Dieter Hüsch Weg 15, 55128 Mainz, Germany
| | - Martin Heine
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University, Hanns-Dieter Hüsch Weg 15, 55128 Mainz, Germany
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5
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Koppers M, Özkan N, Nguyen HH, Jurriens D, McCaughey J, Nguyen DTM, Li CH, Stucchi R, Altelaar M, MacGillavry HD, Kapitein LC, Hoogenraad CC, Farías GG. Axonal endoplasmic reticulum tubules control local translation via P180/RRBP1-mediated ribosome interactions. Dev Cell 2024; 59:2053-2068.e9. [PMID: 38815583 PMCID: PMC11338522 DOI: 10.1016/j.devcel.2024.05.005] [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: 10/12/2022] [Revised: 01/31/2024] [Accepted: 05/09/2024] [Indexed: 06/01/2024]
Abstract
Local mRNA translation in axons is critical for the spatiotemporal regulation of the axonal proteome. A wide variety of mRNAs are localized and translated in axons; however, how protein synthesis is regulated at specific subcellular sites in axons remains unclear. Here, we establish that the axonal endoplasmic reticulum (ER) supports axonal translation in developing rat hippocampal cultured neurons. Axonal ER tubule disruption impairs local translation and ribosome distribution. Using nanoscale resolution imaging, we find that ribosomes make frequent contacts with axonal ER tubules in a translation-dependent manner and are influenced by specific extrinsic cues. We identify P180/RRBP1 as an axonally distributed ribosome receptor that regulates local translation and binds to mRNAs enriched for axonal membrane proteins. Importantly, the impairment of axonal ER-ribosome interactions causes defects in axon morphology. Our results establish a role for the axonal ER in dynamically localizing mRNA translation, which is important for proper neuron development.
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Affiliation(s)
- Max Koppers
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, the Netherlands.
| | - Nazmiye Özkan
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, the Netherlands
| | - Ha H Nguyen
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, the Netherlands
| | - Daphne Jurriens
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, the Netherlands
| | - Janine McCaughey
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, the Netherlands
| | - Dan T M Nguyen
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, the Netherlands
| | - Chun Hei Li
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, the Netherlands
| | - Riccardo Stucchi
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, the Netherlands; Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584 CH Utrecht, the Netherlands
| | - Maarten Altelaar
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584 CH Utrecht, the Netherlands
| | - Harold D MacGillavry
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, the Netherlands
| | - Lukas C Kapitein
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, the Netherlands
| | - Casper C Hoogenraad
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, the Netherlands; Department of Neuroscience, Genentech, Inc., South San Francisco, CA 94080, USA
| | - Ginny G Farías
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, the Netherlands.
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6
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Iavarone F, Zaninello M, Perrone M, Monaco M, Barth E, Gaedke F, Pizzo MT, Di Lorenzo G, Desiderio V, Sommella E, Merciai F, Salviati E, Campiglia P, Luongo L, De Leonibus E, Rugarli E, Settembre C. Fam134c and Fam134b shape axonal endoplasmic reticulum architecture in vivo. EMBO Rep 2024; 25:3651-3677. [PMID: 39039299 PMCID: PMC11316074 DOI: 10.1038/s44319-024-00213-7] [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: 02/09/2024] [Revised: 06/27/2024] [Accepted: 07/03/2024] [Indexed: 07/24/2024] Open
Abstract
Endoplasmic reticulum (ER) remodeling is vital for cellular organization. ER-phagy, a selective autophagy targeting ER, plays an important role in maintaining ER morphology and function. The FAM134 protein family, including FAM134A, FAM134B, and FAM134C, mediates ER-phagy. While FAM134B mutations are linked to hereditary sensory and autonomic neuropathy in humans, the physiological role of the other FAM134 proteins remains unknown. To address this, we investigate the roles of FAM134 proteins using single and combined knockouts (KOs) in mice. Single KOs in young mice show no major phenotypes; however, combined Fam134b and Fam134c deletion (Fam134b/cdKO), but not the combination including Fam134a deletion, leads to rapid neuromuscular and somatosensory degeneration, resulting in premature death. Fam134b/cdKO mice show rapid loss of motor and sensory axons in the peripheral nervous system. Long axons from Fam134b/cdKO mice exhibit expanded tubular ER with a transverse ladder-like appearance, whereas no obvious abnormalities are present in cortical ER. Our study unveils the critical roles of FAM134C and FAM134B in the formation of tubular ER network in axons of both motor and sensory neurons.
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Affiliation(s)
| | - Marta Zaninello
- Institute for Genetics, Faculty of Mathematics and Natural Sciences, University of Cologne, Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
- Center for Molecular Medicine, University of Cologne, Cologne, Germany
| | - Michela Perrone
- Department of Experimental Medicine, Division of Pharmacology, University of Campania "L. Vanvitelli", Naples, Italy
| | | | - Esther Barth
- Institute for Genetics, Faculty of Mathematics and Natural Sciences, University of Cologne, Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
| | - Felix Gaedke
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
| | | | | | - Vincenzo Desiderio
- Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Via L. Armanni 5, 80138, Naples, Italy
| | - Eduardo Sommella
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132, Fisciano, SA, 84084, Italy
| | - Fabrizio Merciai
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132, Fisciano, SA, 84084, Italy
| | - Emanuela Salviati
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132, Fisciano, SA, 84084, Italy
| | - Pietro Campiglia
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132, Fisciano, SA, 84084, Italy
| | - Livio Luongo
- Department of Experimental Medicine, Division of Pharmacology, University of Campania "L. Vanvitelli", Naples, Italy
| | - Elvira De Leonibus
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy.
- Institute of Biochemistry and Cell Biology, Monterotondo, Rome, Italy.
| | - Elena Rugarli
- Institute for Genetics, Faculty of Mathematics and Natural Sciences, University of Cologne, Cologne, Germany.
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany.
- Center for Molecular Medicine, University of Cologne, Cologne, Germany.
| | - Carmine Settembre
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy.
- Department of Clinical Medicine and Surgery, Federico II University, Naples, Italy.
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7
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Konno T, Parutto P, Crapart CC, Davì V, Bailey DMD, Awadelkareem MA, Hockings C, Brown AI, Xiang KM, Agrawal A, Chambers JE, Vander Werp MJ, Koning KM, Elfari LM, Steen S, Metzakopian E, Westrate LM, Koslover EF, Avezov E. Endoplasmic reticulum morphology regulation by RTN4 modulates neuronal regeneration by curbing luminal transport. Cell Rep 2024; 43:114357. [PMID: 38955182 DOI: 10.1016/j.celrep.2024.114357] [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: 02/14/2024] [Revised: 03/01/2024] [Accepted: 05/29/2024] [Indexed: 07/04/2024] Open
Abstract
Cell functions rely on intracellular transport systems distributing bioactive molecules with high spatiotemporal accuracy. The endoplasmic reticulum (ER) tubular network constitutes a system for delivering luminal solutes, including Ca2+, across the cell periphery. How the ER structure enables this nanofluidic transport system is unclear. Here, we show that ER membrane-localized reticulon 4 (RTN4/Nogo) is sufficient to impose neurite outgrowth inhibition in human cortical neurons while acting as an ER morphoregulator. Improving ER transport visualization methodologies combined with optogenetic Ca2+ dynamics imaging and in silico modeling, we observed that ER luminal transport is modulated by ER tubule narrowing and dilation, proportional to the amount of RTN4. Excess RTN4 limited ER luminal transport and Ca2+ release, while RTN4 elimination reversed the effects. The described morphoregulatory effect of RTN4 defines the capacity of the ER for peripheral Ca2+ delivery for physiological releases and thus may constitute a mechanism for controlling the (re)generation of neurites.
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Affiliation(s)
- Tasuku Konno
- UK Dementia Research Institute at University of Cambridge, Department of Clinical Neurosciences, Cambridge CB2 0AH, UK
| | - Pierre Parutto
- UK Dementia Research Institute at University of Cambridge, Department of Clinical Neurosciences, Cambridge CB2 0AH, UK
| | - Cécile C Crapart
- UK Dementia Research Institute at University of Cambridge, Department of Clinical Neurosciences, Cambridge CB2 0AH, UK
| | - Valentina Davì
- UK Dementia Research Institute at University of Cambridge, Department of Clinical Neurosciences, Cambridge CB2 0AH, UK
| | | | - Mosab Ali Awadelkareem
- UK Dementia Research Institute at University of Cambridge, Department of Clinical Neurosciences, Cambridge CB2 0AH, UK; Department of Neuroscience Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Colin Hockings
- UK Dementia Research Institute at University of Cambridge, Department of Clinical Neurosciences, Cambridge CB2 0AH, UK
| | - Aidan I Brown
- Department of Physics, University of California, San Diego, 9500 Gilman Dr. #0374, La Jolla, CA 92093-0374, USA; Department of Physics, Toronto Metropolitan University, Toronto, ON M5B 2K3, Canada
| | | | - Anamika Agrawal
- Department of Physics, University of California, San Diego, 9500 Gilman Dr. #0374, La Jolla, CA 92093-0374, USA
| | - Joseph E Chambers
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Molly J Vander Werp
- Department of Chemistry and Biochemistry, Calvin University, Grand Rapids, MI 49546, USA
| | - Katherine M Koning
- Department of Chemistry and Biochemistry, Calvin University, Grand Rapids, MI 49546, USA
| | - Louis Mounir Elfari
- Wellcome-MRC Cambridge Stem Cell Institute Advanced Imaging Facility, Puddicombe Way, Cambridge CB2 0AW, UK
| | - Sam Steen
- Department of Chemistry and Biochemistry, Calvin University, Grand Rapids, MI 49546, USA
| | - Emmanouil Metzakopian
- UK Dementia Research Institute at University of Cambridge, Department of Clinical Neurosciences, Cambridge CB2 0AH, UK
| | - Laura M Westrate
- Department of Chemistry and Biochemistry, Calvin University, Grand Rapids, MI 49546, USA
| | - Elena F Koslover
- Department of Physics, University of California, San Diego, 9500 Gilman Dr. #0374, La Jolla, CA 92093-0374, USA.
| | - Edward Avezov
- UK Dementia Research Institute at University of Cambridge, Department of Clinical Neurosciences, Cambridge CB2 0AH, UK.
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8
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Borisova E, Newman AG, Couce Iglesias M, Dannenberg R, Schaub T, Qin B, Rusanova A, Brockmann M, Koch J, Daniels M, Turko P, Jahn O, Kaplan DR, Rosário M, Iwawaki T, Spahn CMT, Rosenmund C, Meierhofer D, Kraushar ML, Tarabykin V, Ambrozkiewicz MC. Protein translation rate determines neocortical neuron fate. Nat Commun 2024; 15:4879. [PMID: 38849354 PMCID: PMC11161512 DOI: 10.1038/s41467-024-49198-w] [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: 05/27/2022] [Accepted: 05/24/2024] [Indexed: 06/09/2024] Open
Abstract
The mammalian neocortex comprises an enormous diversity regarding cell types, morphology, and connectivity. In this work, we discover a post-transcriptional mechanism of gene expression regulation, protein translation, as a determinant of cortical neuron identity. We find specific upregulation of protein synthesis in the progenitors of later-born neurons and show that translation rates and concomitantly protein half-lives are inherent features of cortical neuron subtypes. In a small molecule screening, we identify Ire1α as a regulator of Satb2 expression and neuronal polarity. In the developing brain, Ire1α regulates global translation rates, coordinates ribosome traffic, and the expression of eIF4A1. Furthermore, we demonstrate that the Satb2 mRNA translation requires eIF4A1 helicase activity towards its 5'-untranslated region. Altogether, we show that cortical neuron diversity is generated by mechanisms operating beyond gene transcription, with Ire1α-safeguarded proteostasis serving as an essential regulator of brain development.
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Affiliation(s)
- Ekaterina Borisova
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Germany
| | - Andrew G Newman
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Germany
| | - Marta Couce Iglesias
- Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195, Berlin, Germany
| | - Rike Dannenberg
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Germany
| | - Theres Schaub
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Germany
| | - Bo Qin
- Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195, Berlin, Germany
| | - Alexandra Rusanova
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Germany
- Tomsk National Research Medical Center of the Russian Academy of Sciences, Research Institute of Medical Genetics, Tomsk, Russia
| | - Marisa Brockmann
- Institute of Neurophysiology, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany
| | - Janina Koch
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Germany
| | - Marieatou Daniels
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Germany
| | - Paul Turko
- Institute of Integrative Neuroanatomy, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany
| | - Olaf Jahn
- Neuroproteomics Group, Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Hermann-Rein-Str. 3, 37075, Göttingen, Germany
- Translational Neuroproteomics Group, Department of Psychiatry and Psychotherapy, University Medical Center Göttingen, Georg-August-University, Von-Siebold-Str. 5, 37075, Göttingen, Germany
| | - David R Kaplan
- Program in Neurosciences and Mental Health, Hospital for Sick Children and Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Marta Rosário
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Germany
| | - Takao Iwawaki
- Medical Research Institute, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Kahoku, Ishikawa, 920-0293, Japan
| | - Christian M T Spahn
- Institute of Medical Physics and Biophysics, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany
| | - Christian Rosenmund
- Institute of Neurophysiology, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany
| | - David Meierhofer
- Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195, Berlin, Germany
| | - Matthew L Kraushar
- Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195, Berlin, Germany
| | - Victor Tarabykin
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Germany.
| | - Mateusz C Ambrozkiewicz
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Germany.
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9
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Zaninello M, Schlegel T, Nolte H, Pirzada M, Savino E, Barth E, Klein I, Wüstenberg H, Uddin T, Wolff L, Wirth B, Lehmann HC, Cioni JM, Langer T, Rugarli EI. CLUH maintains functional mitochondria and translation in motoneuronal axons and prevents peripheral neuropathy. SCIENCE ADVANCES 2024; 10:eadn2050. [PMID: 38809982 PMCID: PMC11135423 DOI: 10.1126/sciadv.adn2050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2023] [Accepted: 04/24/2024] [Indexed: 05/31/2024]
Abstract
Transporting and translating mRNAs in axons is crucial for neuronal viability. Local synthesis of nuclear-encoded mitochondrial proteins protects long-lived axonal mitochondria from damage; however, the regulatory factors involved are largely unknown. We show that CLUH, which binds mRNAs encoding mitochondrial proteins, prevents peripheral neuropathy and motor deficits in the mouse. CLUH is enriched in the growth cone of developing spinal motoneurons and is required for their growth. The lack of CLUH affects the abundance of target mRNAs and the corresponding mitochondrial proteins more prominently in axons, leading to ATP deficits in the growth cone. CLUH interacts with ribosomal subunits, translation initiation, and ribosome recycling components and preserves axonal translation. Overexpression of the ribosome recycling factor ABCE1 rescues the mRNA and translation defects, as well as the growth cone size, in CLUH-deficient motoneurons. Thus, we demonstrate a role for CLUH in mitochondrial quality control and translational regulation in axons, which is essential for their development and long-term integrity and function.
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Affiliation(s)
- Marta Zaninello
- Institute for Genetics, University of Cologne, Cologne 50931, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne 50931, Germany
| | - Tim Schlegel
- Institute for Genetics, University of Cologne, Cologne 50931, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne 50931, Germany
| | - Hendrik Nolte
- Max Planck Institute for Biology of Ageing, Cologne 50931, Germany
| | - Mujeeb Pirzada
- Institute for Genetics, University of Cologne, Cologne 50931, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne 50931, Germany
| | - Elisa Savino
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Esther Barth
- Institute for Genetics, University of Cologne, Cologne 50931, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne 50931, Germany
| | - Ines Klein
- Department of Neurology, University of Cologne, Cologne 50931, Germany
| | - Hauke Wüstenberg
- Department of Neurology, University of Cologne, Cologne 50931, Germany
| | - Tesmin Uddin
- Institute for Genetics, University of Cologne, Cologne 50931, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne 50931, Germany
| | - Lisa Wolff
- Institute of Human Genetics, University of Cologne, Cologne 50931, Germany
| | - Brunhilde Wirth
- Institute for Genetics, University of Cologne, Cologne 50931, Germany
- Institute of Human Genetics, University of Cologne, Cologne 50931, Germany
- Center for Molecular Medicine (CMMC), University of Cologne, Cologne 50931, Germany
- Center for Rare Diseases Cologne (CESEK), University Hospital of Cologne, Cologne 50937, Germany
| | - Helmar C. Lehmann
- Department of Neurology, University of Cologne, Cologne 50931, Germany
| | - Jean-Michel Cioni
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Thomas Langer
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne 50931, Germany
- Max Planck Institute for Biology of Ageing, Cologne 50931, Germany
| | - Elena I. Rugarli
- Institute for Genetics, University of Cologne, Cologne 50931, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne 50931, Germany
- Center for Molecular Medicine (CMMC), University of Cologne, Cologne 50931, Germany
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10
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Falahati H, Wu Y, De Camilli P. Ectopic Reconstitution of a Spine-Apparatus Like Structure Provides Insight into Mechanisms Underlying Its Formation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.16.589782. [PMID: 38659799 PMCID: PMC11042382 DOI: 10.1101/2024.04.16.589782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
The endoplasmic reticulum (ER) is a continuous cellular endomembrane network that displays focal specializations. Most notable examples of such specializations include the spine apparatus of neuronal dendrites, and the cisternal organelle of axonal initial segments. Both organelles exhibit stacks of smooth ER sheets with a narrow lumen and interconnected by a dense protein matrix. The actin-binding protein synaptopodin is required for their formation. Here, we report that expression in non-neuronal cells of a synaptopodin construct targeted to the ER is sufficient to generate stacked ER cisterns resembling the spine apparatus with molecular properties distinct from the surrounding ER. Cisterns within these stacks are connected to each other by an actin-based matrix that contains proteins also found at the spine apparatus of neuronal spines. These findings reveal a critical role of a synaptopodin-dependent actin matrix in generating cisternal stacks. These ectopically generated structures provide insight into spine apparatus morphogenesis.
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Affiliation(s)
- Hanieh Falahati
- HHMI; Departments of Neuroscience and Cell Biology; Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, 100 College Street, New Haven, 06511, CT, USA
| | - Yumei Wu
- HHMI; Departments of Neuroscience and Cell Biology; Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, 100 College Street, New Haven, 06511, CT, USA
| | - Pietro De Camilli
- HHMI; Departments of Neuroscience and Cell Biology; Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, 100 College Street, New Haven, 06511, CT, USA
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11
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Cremer T, Voortman LM, Bos E, Jongsma MLM, ter Haar LR, Akkermans JJLL, Talavera Ormeño CMP, Wijdeven RHM, de Vries J, Kim RQ, Janssen GMC, van Veelen PA, Koning RI, Neefjes J, Berlin I. RNF26 binds perinuclear vimentin filaments to integrate ER and endolysosomal responses to proteotoxic stress. EMBO J 2023; 42:e111252. [PMID: 37519262 PMCID: PMC10505911 DOI: 10.15252/embj.2022111252] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 06/28/2023] [Accepted: 07/03/2023] [Indexed: 08/01/2023] Open
Abstract
Proteotoxic stress causes profound endoplasmic reticulum (ER) membrane remodeling into a perinuclear quality control compartment (ERQC) for the degradation of misfolded proteins. Subsequent return to homeostasis involves clearance of the ERQC by endolysosomes. However, the factors that control perinuclear ER integrity and dynamics remain unclear. Here, we identify vimentin intermediate filaments as perinuclear anchors for the ER and endolysosomes. We show that perinuclear vimentin filaments engage the ER-embedded RING finger protein 26 (RNF26) at the C-terminus of its RING domain. This restricts RNF26 to perinuclear ER subdomains and enables the corresponding spatial retention of endolysosomes through RNF26-mediated membrane contact sites (MCS). We find that both RNF26 and vimentin are required for the perinuclear coalescence of the ERQC and its juxtaposition with proteolytic compartments, which facilitates efficient recovery from ER stress via the Sec62-mediated ER-phagy pathway. Collectively, our findings reveal a scaffolding mechanism that underpins the spatiotemporal integration of organelles during cellular proteostasis.
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Affiliation(s)
- Tom Cremer
- Department of Cell and Chemical BiologyLeiden University Medical CenterLeidenThe Netherlands
- Oncode Institute, Leiden University Medical CenterLeidenThe Netherlands
| | - Lenard M Voortman
- Department of Cell and Chemical BiologyLeiden University Medical CenterLeidenThe Netherlands
| | - Erik Bos
- Department of Cell and Chemical BiologyLeiden University Medical CenterLeidenThe Netherlands
| | - Marlieke LM Jongsma
- Department of Cell and Chemical BiologyLeiden University Medical CenterLeidenThe Netherlands
- Oncode Institute, Leiden University Medical CenterLeidenThe Netherlands
| | - Laurens R ter Haar
- Department of Cell and Chemical BiologyLeiden University Medical CenterLeidenThe Netherlands
| | - Jimmy JLL Akkermans
- Department of Cell and Chemical BiologyLeiden University Medical CenterLeidenThe Netherlands
- Oncode Institute, Leiden University Medical CenterLeidenThe Netherlands
| | - Cami MP Talavera Ormeño
- Department of Cell and Chemical BiologyLeiden University Medical CenterLeidenThe Netherlands
| | - Ruud HM Wijdeven
- Department of Cell and Chemical BiologyLeiden University Medical CenterLeidenThe Netherlands
- Oncode Institute, Leiden University Medical CenterLeidenThe Netherlands
- Alzheimer Center Amsterdam, Department of Neurology, Amsterdam NeuroscienceAmsterdam University Medical CenterAmsterdamThe Netherlands
| | - Jelle de Vries
- Department of Cell and Chemical BiologyLeiden University Medical CenterLeidenThe Netherlands
| | - Robbert Q Kim
- Department of Cell and Chemical BiologyLeiden University Medical CenterLeidenThe Netherlands
| | - George MC Janssen
- Department of Cell and Chemical BiologyLeiden University Medical CenterLeidenThe Netherlands
| | - Peter A van Veelen
- Department of Cell and Chemical BiologyLeiden University Medical CenterLeidenThe Netherlands
| | - Roman I Koning
- Department of Cell and Chemical BiologyLeiden University Medical CenterLeidenThe Netherlands
| | - Jacques Neefjes
- Department of Cell and Chemical BiologyLeiden University Medical CenterLeidenThe Netherlands
- Oncode Institute, Leiden University Medical CenterLeidenThe Netherlands
| | - Ilana Berlin
- Department of Cell and Chemical BiologyLeiden University Medical CenterLeidenThe Netherlands
- Oncode Institute, Leiden University Medical CenterLeidenThe Netherlands
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12
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Bai F, Bertram R, Karamched BR. A mathematical study of the efficacy of possible negative feedback pathways involved in neuronal polarization. J Theor Biol 2023; 571:111561. [PMID: 37331648 DOI: 10.1016/j.jtbi.2023.111561] [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: 03/01/2023] [Revised: 05/29/2023] [Accepted: 06/11/2023] [Indexed: 06/20/2023]
Abstract
Neuronal polarization, a process wherein nascent neurons develop a single long axon and multiple short dendrites, can occur within in vitro cell cultures without environmental cues. This is an apparently random process in which one of several short processes, called neurites, grows to become long, while the others remain short. In this study, we propose a minimum model for neurite growth, which involves bistability and random excitations reflecting actin waves. Positive feedback is needed to produce the bistability, while negative feedback is required to ensure that no more than one neurite wins the winner-takes-all contest. By applying the negative feedback to different aspects of the neurite growth process, we demonstrate that targeting the negative feedback to the excitation amplitude results in the most persistent polarization. Also, we demonstrate that there are optimal ranges of values for the neurite count, and for the excitation rate and amplitude that best maintain the polarization. Finally, we show that a previously published model for neuronal polarization based on competition for limited resources shares key features with our best-performing minimal model: bistability and negative feedback targeted to the size of random excitations.
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Affiliation(s)
- Fan Bai
- Department of Mathematics, Florida State University, Tallahassee FL 32306, United States
| | - Richard Bertram
- Department of Mathematics, Florida State University, Tallahassee FL 32306, United States; Program in Molecular Biophysics, Florida State University, Tallahassee FL 32306, United States; Program in Neuroscience, Florida State University, Tallahassee FL 32306, United States
| | - Bhargav R Karamched
- Department of Mathematics, Florida State University, Tallahassee FL 32306, United States; Program in Molecular Biophysics, Florida State University, Tallahassee FL 32306, United States; Program in Neuroscience, Florida State University, Tallahassee FL 32306, United States.
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13
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Smith G, Sweeney ST, O’Kane CJ, Prokop A. How neurons maintain their axons long-term: an integrated view of axon biology and pathology. Front Neurosci 2023; 17:1236815. [PMID: 37564364 PMCID: PMC10410161 DOI: 10.3389/fnins.2023.1236815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 07/06/2023] [Indexed: 08/12/2023] Open
Abstract
Axons are processes of neurons, up to a metre long, that form the essential biological cables wiring nervous systems. They must survive, often far away from their cell bodies and up to a century in humans. This requires self-sufficient cell biology including structural proteins, organelles, and membrane trafficking, metabolic, signalling, translational, chaperone, and degradation machinery-all maintaining the homeostasis of energy, lipids, proteins, and signalling networks including reactive oxygen species and calcium. Axon maintenance also involves specialised cytoskeleton including the cortical actin-spectrin corset, and bundles of microtubules that provide the highways for motor-driven transport of components and organelles for virtually all the above-mentioned processes. Here, we aim to provide a conceptual overview of key aspects of axon biology and physiology, and the homeostatic networks they form. This homeostasis can be derailed, causing axonopathies through processes of ageing, trauma, poisoning, inflammation or genetic mutations. To illustrate which malfunctions of organelles or cell biological processes can lead to axonopathies, we focus on axonopathy-linked subcellular defects caused by genetic mutations. Based on these descriptions and backed up by our comprehensive data mining of genes linked to neural disorders, we describe the 'dependency cycle of local axon homeostasis' as an integrative model to explain why very different causes can trigger very similar axonopathies, providing new ideas that can drive the quest for strategies able to battle these devastating diseases.
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Affiliation(s)
- Gaynor Smith
- Cardiff University, School of Medicine, College of Biomedical and Life Sciences, Cardiff, United Kingdom
| | - Sean T. Sweeney
- Department of Biology, University of York and York Biomedical Research Institute, York, United Kingdom
| | - Cahir J. O’Kane
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Andreas Prokop
- Manchester Academic Health Science Centre, Faculty of Biology, Medicine and Health, School of Biology, The University of Manchester, Manchester, United Kingdom
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14
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Best MN, Lim Y, Ferenc NN, Kim N, Min L, Wang DB, Sharifi K, Wasserman AE, McTavish SA, Siller KH, Jones MK, Jenkins PM, Mandell JW, Bloom GS. Extracellular Tau Oligomers Damage the Axon Initial Segment. J Alzheimers Dis 2023:JAD221284. [PMID: 37182881 DOI: 10.3233/jad-221284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
BACKGROUND In Alzheimer's disease (AD) brain, neuronal polarity and synaptic connectivity are compromised. A key structure for regulating polarity and functions of neurons is the axon initial segment (AIS), which segregates somatodendritic from axonal proteins and initiates action potentials. Toxic tau species, including extracellular oligomers (xcTauOs), spread tau pathology from neuron to neuron by a prion-like process, but few other cell biological effects of xcTauOs have been described. OBJECTIVE Test the hypothesis that AIS structure is sensitive to xcTauOs. METHODS Cultured wild type (WT) and tau knockout (KO) mouse cortical neurons were exposed to xcTauOs, and quantitative western blotting and immunofluorescence microscopy with anti-TRIM46 monitored effects on the AIS. The same methods were used to compare TRIM46 and two other resident AIS proteins in human hippocampal tissue obtained from AD and age-matched non-AD donors. RESULTS Without affecting total TRIM46 levels, xcTauOs reduce the concentration of TRIM46 within the AIS and cause AIS shortening in cultured WT, but not TKO neurons. Lentiviral-driven tau expression in tau KO neurons rescues AIS length sensitivity to xcTauOs. In human AD hippocampus, the overall protein levels of multiple resident AIS proteins are unchanged compared to non-AD brain, but TRIM46 concentration within the AIS and AIS length are reduced in neurons containing neurofibrillary tangles. CONCLUSION xcTauOs cause partial AIS damage in cultured neurons by a mechanism dependent on intracellular tau, thereby raising the possibility that the observed AIS reduction in AD neurons in vivo is caused by xcTauOs working in concert with endogenous neuronal tau.
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Affiliation(s)
- Merci N Best
- Department of Biology, University of Virginia, Charlottesville, VA, USA
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
| | - Yunu Lim
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Nina N Ferenc
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Nayoung Kim
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Lia Min
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Dora Bigler Wang
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Kamyar Sharifi
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Anna E Wasserman
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Sloane A McTavish
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Karsten H Siller
- Research Computing, University of Virginia, Charlottesville, VA, USA
| | - Marieke K Jones
- Claude Moore Health Sciences Library, University of Virginia, Charlottesville, VA, USA
| | - Paul M Jenkins
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Psychiatry, University of Michigan Medical School, Ann Arbor, MI, USA
| | - James W Mandell
- Department of Pathology, University of Virginia, Charlottesville, VA, USA
| | - George S Bloom
- Department of Biology, University of Virginia, Charlottesville, VA, USA
- Department of Cell Biology, University of Virginia, Charlottesville, VA, USA
- Department of Neuroscience, University of Virginia, Charlottesville, VA, USA
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15
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De Vincentiis S, Baggiani M, Merighi F, Cappello V, Lopane J, Di Caprio M, Costa M, Mainardi M, Onorati M, Raffa V. Low Forces Push the Maturation of Neural Precursors into Neurons. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023:e2205871. [PMID: 37058009 DOI: 10.1002/smll.202205871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Revised: 03/15/2023] [Indexed: 06/19/2023]
Abstract
Mechanical stimulation modulates neural development and neuronal activity. In a previous study, magnetic "nano-pulling" is proposed as a tool to generate active forces. By loading neural cells with magnetic nanoparticles (MNPs), a precise force vector is remotely generated through static magnetic fields. In the present study, human neural stem cells (NSCs) are subjected to a standard differentiation protocol, in the presence or absence of nano-pulling. Under mechanical stimulation, an increase in the length of the neural processes which showed an enrichment in microtubules, endoplasmic reticulum, and mitochondria is found. A stimulation lasting up to 82 days induces a strong remodeling at the level of synapse density and a re-organization of the neuronal network, halving the time required for the maturation of neural precursors into neurons. The MNP-loaded NSCs are then transplanted into mouse spinal cord organotypic slices, demonstrating that nano-pulling stimulates the elongation of the NSC processes and modulates their orientation even in an ex vivo model. Thus, it is shown that active mechanical stimuli can guide the outgrowth of NSCs transplanted into the spinal cord tissue. The findings suggest that mechanical forces play an important role in neuronal maturation which could be applied in regenerative medicine.
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Affiliation(s)
| | - Matteo Baggiani
- Department of Biology, Università di Pisa, Pisa, 56127, Italy
| | | | - Valentina Cappello
- Center for Materials Interfaces, Istituto Italiano di Tecnologia, Pontedera, 56025, Italy
| | - Jakub Lopane
- Department of Biology, Università di Pisa, Pisa, 56127, Italy
| | - Mariachiara Di Caprio
- Laboratory of Biology "Bio@SNS", Scuola Normale Superiore, Piazza dei Cavalieri 7, Pisa, 56126, Italy
| | - Mario Costa
- Neuroscience Institute, National Research Council, via Giuseppe Moruzzi 1, Pisa, 56124, Italy
| | - Marco Mainardi
- Neuroscience Institute, National Research Council, via Giuseppe Moruzzi 1, Pisa, 56124, Italy
| | - Marco Onorati
- Department of Biology, Università di Pisa, Pisa, 56127, Italy
| | - Vittoria Raffa
- Department of Biology, Università di Pisa, Pisa, 56127, Italy
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16
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Iwanski MK, Kapitein LC. Cellular cartography: Towards an atlas of the neuronal microtubule cytoskeleton. Front Cell Dev Biol 2023; 11:1052245. [PMID: 37035244 PMCID: PMC10073685 DOI: 10.3389/fcell.2023.1052245] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 02/28/2023] [Indexed: 04/11/2023] Open
Abstract
Microtubules, one of the major components of the cytoskeleton, play a crucial role during many aspects of neuronal development and function, such as neuronal polarization and axon outgrowth. Consequently, the microtubule cytoskeleton has been implicated in many neurodevelopmental and neurodegenerative disorders. The polar nature of microtubules is quintessential for their function, allowing them to serve as tracks for long-distance, directed intracellular transport by kinesin and dynein motors. Most of these motors move exclusively towards either the plus- or minus-end of a microtubule and some have been shown to have a preference for either dynamic or stable microtubules, those bearing a particular post-translational modification or those decorated by a specific microtubule-associated protein. Thus, it becomes important to consider the interplay of these features and their combinatorial effects on transport, as well as how different types of microtubules are organized in the cell. Here, we discuss microtubule subsets in terms of tubulin isotypes, tubulin post-translational modifications, microtubule-associated proteins, microtubule stability or dynamicity, and microtubule orientation. We highlight techniques used to study these features of the microtubule cytoskeleton and, using the information from these studies, try to define the composition, role, and organization of some of these subsets in neurons.
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Affiliation(s)
| | - Lukas C. Kapitein
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
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17
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Han K, Huang S, Kong J, Yang Y, Shi L, Ci Y. A novel fluorescent endoplasmic reticulum marker for super-resolution imaging in live cells. FEBS Lett 2023; 597:693-701. [PMID: 36694281 DOI: 10.1002/1873-3468.14581] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 01/06/2023] [Accepted: 01/09/2023] [Indexed: 01/26/2023]
Abstract
Endoplasmic reticulum (ER) is a highly complicated and dynamic organelle that actively changes its shape and communicates with other organelles. Visualization of ER in live cells is of great importance to understand cellular activities. Here, we designed a novel ER marker, RR-mNeonGreen, which comprised an N-terminal ER retention signal, a bright fluorescent protein (mNeonGreen), and a C-terminal transmembrane region. Colocalization of RR-mNeonGreen with mCherry-KDEL verified that RR-mNeonGreen perfectly labeled the ER. RR-mNeonGreen showed better continuity of ER tubules when imaged by super-resolution microscopy. Moreover, RR-mNeonGreen is competent for live-cell imaging of ER dynamics and tracing of the interaction between ER and mitochondria at high spatiotemporal resolution. In summary, RR-mNeonGreen is a novel ER marker for super-resolution live-cell imaging with multiple merits.
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Affiliation(s)
- Kai Han
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, China
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, China
| | - Shuhan Huang
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, China
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, China
| | - Jie Kong
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, China
| | - Yang Yang
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, China
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, China
| | - Lei Shi
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, China
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, China
| | - Yali Ci
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, China
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, China
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18
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The interconnection of endoplasmic reticulum and microtubule and its implication in Hereditary Spastic Paraplegia. Comput Struct Biotechnol J 2023; 21:1670-1677. [PMID: 36860342 PMCID: PMC9968982 DOI: 10.1016/j.csbj.2023.02.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 02/14/2023] [Accepted: 02/14/2023] [Indexed: 02/22/2023] Open
Abstract
The endoplasmic reticulum (ER) and microtubule (MT) network form extensive contact with each other and their interconnection plays a pivotal role in ER maintenance and distribution as well as MT stability. The ER participates in a variety of biological processes including protein folding and processing, lipid biosynthesis, and Ca2+ storage. MTs specifically regulate cellular architecture, provide routes for transport of molecules or organelles, and mediate signaling events. The ER morphology and dynamics are regulated by a class of ER shaping proteins, which also provide the physical contact structure for linking of ER and MT. In addition to these ER-localized and MT-binding proteins, specific motor proteins and adaptor-linking proteins also mediate bidirectional communication between the two structures. In this review, we summarize the current understanding of the structure and function of ER-MT interconnection. We further highlight the morphologic factors which coordinate the ER-MT network and maintain the normal physiological function of neurons, with their defect causing neurodegenerative diseases such as Hereditary Spastic Paraplegia (HSP). These findings promote our understanding of the pathogenesis of HSP and provide important therapeutic targets for treatment of these diseases.
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19
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Yperman K, Kuijpers M. Neuronal endoplasmic reticulum architecture and roles in axonal physiology. Mol Cell Neurosci 2023; 125:103822. [PMID: 36781033 DOI: 10.1016/j.mcn.2023.103822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 02/06/2023] [Accepted: 02/08/2023] [Indexed: 02/13/2023] Open
Abstract
The endoplasmic reticulum (ER) is the largest membrane compartment within eukaryotic cells and is emerging as a key coordinator of many cellular processes. The ER can modulate local calcium fluxes and communicate with other organelles like the plasma membrane. The importance of ER in neuronal processes such as neurite growth, axon repair and neurotransmission has recently gained much attention. In this review, we highlight the importance of the ER tubular network in axonal homeostasis and discuss how the generation and maintenance of the thin tubular ER network in axons and synapses, requires a cooperative effort of ER-shaping proteins, cytoskeleton and autophagy processes.
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Affiliation(s)
- Klaas Yperman
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany
| | - Marijn Kuijpers
- Department of Molecular Neurobiology, Donders Institute for Brain, Cognition and Behaviour and Faculty of Science, Radboud University, 6525 AJ Nijmegen, the Netherlands.
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20
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Konietzny A, Wegmann S, Mikhaylova M. The endoplasmic reticulum puts a new spin on synaptic tagging. Trends Neurosci 2023; 46:32-44. [PMID: 36428191 DOI: 10.1016/j.tins.2022.10.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 10/12/2022] [Accepted: 10/31/2022] [Indexed: 11/23/2022]
Abstract
The heterogeneity of the endoplasmic reticulum (ER) makes it a versatile platform for a broad range of homeostatic processes, ranging from calcium regulation to synthesis and trafficking of proteins and lipids. It is not surprising that neurons use this organelle to fine-tune synaptic properties and thereby provide specificity to synaptic inputs. In this review, we discuss the mechanisms that enable activity-dependent ER recruitment into dendritic spines, with a focus on molecular mechanisms that mediate transport and retention of the ER in spines. The role of calcium signaling in spine ER, synaptopodin 'tagging' of active synapses, and the formation of the spine apparatus (SA) are highlighted. Finally, we discuss the role of liquid-liquid phase separation as a possible driving force in these processes.
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Affiliation(s)
- Anja Konietzny
- AG Optobiology, Institute of Biology, Humboldt Universität zu Berlin, Berlin, Germany; Guest Group 'Neuronal Protein Transport', Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Susanne Wegmann
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - Marina Mikhaylova
- AG Optobiology, Institute of Biology, Humboldt Universität zu Berlin, Berlin, Germany; Guest Group 'Neuronal Protein Transport', Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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21
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Falconieri A, De Vincentiis S, Cappello V, Convertino D, Das R, Ghignoli S, Figoli S, Luin S, Català-Castro F, Marchetti L, Borello U, Krieg M, Raffa V. Axonal plasticity in response to active forces generated through magnetic nano-pulling. Cell Rep 2022; 42:111912. [PMID: 36640304 PMCID: PMC9902337 DOI: 10.1016/j.celrep.2022.111912] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 11/16/2022] [Accepted: 12/12/2022] [Indexed: 12/30/2022] Open
Abstract
Mechanical force is crucial in guiding axon outgrowth before and after synapse formation. This process is referred to as "stretch growth." However, how neurons transduce mechanical input into signaling pathways remains poorly understood. Another open question is how stretch growth is coupled in time with the intercalated addition of new mass along the entire axon. Here, we demonstrate that active mechanical force generated by magnetic nano-pulling induces remodeling of the axonal cytoskeleton. Specifically, the increase in the axonal density of microtubules induced by nano-pulling leads to an accumulation of organelles and signaling vesicles, which, in turn, promotes local translation by increasing the probability of assembly of the "translation factories." Modulation of axonal transport and local translation sustains enhanced axon outgrowth and synapse maturation.
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Affiliation(s)
| | - Sara De Vincentiis
- Department of Biology, Università di Pisa, 56127 Pisa, Italy,The Barcelona Institute of Science and Technology, Institut de Ciències Fotòniques, ICFO, 08860 Castelldefels, Spain
| | - Valentina Cappello
- Center for Materials Interfaces, Istituto Italiano di Tecnologia, 56025 Pontedera, Italy
| | - Domenica Convertino
- Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, 56127 Pisa, Italy
| | - Ravi Das
- The Barcelona Institute of Science and Technology, Institut de Ciències Fotòniques, ICFO, 08860 Castelldefels, Spain
| | | | - Sofia Figoli
- Department of Biology, Università di Pisa, 56127 Pisa, Italy
| | - Stefano Luin
- National Enterprise for NanoScience and NanoTechnology (NEST) Laboratory, Scuola Normale Superiore, 56127 Pisa, Italy
| | - Frederic Català-Castro
- The Barcelona Institute of Science and Technology, Institut de Ciències Fotòniques, ICFO, 08860 Castelldefels, Spain
| | - Laura Marchetti
- Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, 56127 Pisa, Italy,Department of Pharmacy, Università di Pisa, 56126 Pisa, Italy
| | - Ugo Borello
- Department of Biology, Università di Pisa, 56127 Pisa, Italy
| | - Michael Krieg
- The Barcelona Institute of Science and Technology, Institut de Ciències Fotòniques, ICFO, 08860 Castelldefels, Spain
| | - Vittoria Raffa
- Department of Biology, Università di Pisa, 56127 Pisa, Italy.
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22
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Swope RD, Hertzler JI, Stone MC, Kothe GO, Rolls MM. The exocyst complex is required for developmental and regenerative neurite growth in vivo. Dev Biol 2022; 492:1-13. [PMID: 36162553 PMCID: PMC10228574 DOI: 10.1016/j.ydbio.2022.09.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 09/13/2022] [Accepted: 09/19/2022] [Indexed: 11/30/2022]
Abstract
The exocyst complex is an important regulator of intracellular trafficking and tethers secretory vesicles to the plasma membrane. Understanding of its role in neuron outgrowth remains incomplete, and previous studies have come to different conclusions about its importance for axon and dendrite growth, particularly in vivo. To investigate exocyst function in vivo we used Drosophila sensory neurons as a model system. To bypass early developmental requirements in other cell types, we used neuron-specific RNAi to target seven exocyst subunits. Initial neuronal development proceeded normally in these backgrounds, however, we considered this could be due to residual exocyst function. To probe neuronal growth capacity at later times after RNAi initiation, we used laser microsurgery to remove axons or dendrites and prompt regrowth. Exocyst subunit RNAi reduced axon regeneration, although new axons could be specified. In control neurons, a vesicle trafficking marker often concentrated in the new axon, but this pattern was disrupted in Sec6 RNAi neurons. Dendrite regeneration was also severely reduced by exocyst RNAi, even though the trafficking marker did not accumulate in a strongly polarized manner during normal dendrite regeneration. The requirement for the exocyst was not limited to injury contexts as exocyst subunit RNAi eliminated dendrite regrowth after developmental pruning. We conclude that the exocyst is required for injury-induced and developmental neurite outgrowth, but that residual protein function can easily mask this requirement.
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Affiliation(s)
- Rachel D Swope
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, University Park, PA, 16802, USA
| | - J Ian Hertzler
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, University Park, PA, 16802, USA
| | - Michelle C Stone
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, University Park, PA, 16802, USA
| | - Gregory O Kothe
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, University Park, PA, 16802, USA
| | - Melissa M Rolls
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, University Park, PA, 16802, USA.
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23
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Burute M, Jansen KI, Mihajlovic M, Vermonden T, Kapitein LC. Local changes in microtubule network mobility instruct neuronal polarization and axon specification. SCIENCE ADVANCES 2022; 8:eabo2343. [PMID: 36332030 PMCID: PMC9635826 DOI: 10.1126/sciadv.abo2343] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 09/15/2022] [Indexed: 06/16/2023]
Abstract
The polarization of neurons into axons and dendrites depends on extracellular cues, intracellular signaling, cytoskeletal rearrangements, and polarized transport, but the interplay between these processes during polarization remains unresolved. Here, we show that axon specification is determined by differences in microtubule network mobility between neurites, regulated by Rho guanosine triphosphatases (GTPases) and extracellular cues. In developing neurons, retrograde microtubule flow prevents the entry of the axon-selective motor protein Kinesin-1 into most neurites. Using inducible assays to control microtubule network flow, we demonstrate that local inhibition of microtubule mobility is sufficient to guide Kinesin-1 into a specific neurite, whereas long-term global inhibition induces the formation of multiple axons. We furthermore show that extracellular mechanical cues and intracellular Rho GTPase signaling control the local differences in microtubule network flow. These results reveal a novel cytoskeletal mechanism for neuronal polarization.
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Affiliation(s)
- Mithila Burute
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands
| | - Klara I. Jansen
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands
| | - Marko Mihajlovic
- Department of Pharmaceutical Sciences, Utrecht Institute for Pharmaceutical Sciences (UIPS), Science for Life, Utrecht University, Universiteitsweg 99, 3508 TB Utrecht, Netherlands
| | - Tina Vermonden
- Department of Pharmaceutical Sciences, Utrecht Institute for Pharmaceutical Sciences (UIPS), Science for Life, Utrecht University, Universiteitsweg 99, 3508 TB Utrecht, Netherlands
| | - Lukas C. Kapitein
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands
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24
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Scharrenberg R, Richter M, Johanns O, Meka DP, Rücker T, Murtaza N, Lindenmaier Z, Ellegood J, Naumann A, Zhao B, Schwanke B, Sedlacik J, Fiehler J, Hanganu-Opatz IL, Lerch JP, Singh KK, de Anda FC. TAOK2 rescues autism-linked developmental deficits in a 16p11.2 microdeletion mouse model. Mol Psychiatry 2022; 27:4707-4721. [PMID: 36123424 PMCID: PMC9734055 DOI: 10.1038/s41380-022-01785-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 09/02/2022] [Accepted: 09/05/2022] [Indexed: 12/14/2022]
Abstract
The precise development of the neocortex is a prerequisite for higher cognitive and associative functions. Despite numerous advances that have been made in understanding neuronal differentiation and cortex development, our knowledge regarding the impact of specific genes associated with neurodevelopmental disorders on these processes is still limited. Here, we show that Taok2, which is encoded in humans within the autism spectrum disorder (ASD) susceptibility locus 16p11.2, is essential for neuronal migration. Overexpression of de novo mutations or rare variants from ASD patients disrupts neuronal migration in an isoform-specific manner. The mutated TAOK2α variants but not the TAOK2β variants impaired neuronal migration. Moreover, the TAOK2α isoform colocalizes with microtubules. Consequently, neurons lacking Taok2 have unstable microtubules with reduced levels of acetylated tubulin and phosphorylated JNK1. Mice lacking Taok2 develop gross cortical and cortex layering abnormalities. Moreover, acute Taok2 downregulation or Taok2 knockout delayed the migration of upper-layer cortical neurons in mice, and the expression of a constitutively active form of JNK1 rescued these neuronal migration defects. Finally, we report that the brains of the Taok2 KO and 16p11.2 del Het mouse models show striking anatomical similarities and that the heterozygous 16p11.2 microdeletion mouse model displayed reduced levels of phosphorylated JNK1 and neuronal migration deficits, which were ameliorated upon the introduction of TAOK2α in cortical neurons and in the developing cortex of those mice. These results delineate the critical role of TAOK2 in cortical development and its contribution to neurodevelopmental disorders, including ASD.
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Affiliation(s)
- Robin Scharrenberg
- Institute of Developmental Neurophysiology, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany
| | - Melanie Richter
- Institute of Developmental Neurophysiology, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany.
| | - Ole Johanns
- Institute of Developmental Neurophysiology, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany
| | - Durga Praveen Meka
- Institute of Developmental Neurophysiology, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany
| | - Tabitha Rücker
- Institute of Developmental Neurophysiology, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany
| | - Nadeem Murtaza
- Krembil Research Institute, Donald K. Johnson Eye Institute, University Health Network, 60 Leonard Ave, Toronto, ON, M5T 0S8, Canada
- Faculty of Medicine, University of Toronto, Medical Sciences Building, 1 King's College Cir, Toronto, ON, M5S 1A8, Canada
- Department of Biochemistry and Biomedical Sciences, Faculty of Health Sciences, McMaster University, Hamilton, ON, L8S 4A9, Canada
| | - Zsuzsa Lindenmaier
- Mouse Imaging Centre, Hospital for Sick Children, Toronto, ON, M5T 3H7, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, ON, M5S 1A1, Canada
| | - Jacob Ellegood
- Mouse Imaging Centre, Hospital for Sick Children, Toronto, ON, M5T 3H7, Canada
| | - Anne Naumann
- Institute of Developmental Neurophysiology, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany
| | - Bing Zhao
- Institute of Developmental Neurophysiology, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany
| | - Birgit Schwanke
- Institute of Developmental Neurophysiology, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany
| | - Jan Sedlacik
- Department of Neuroradiology, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Jens Fiehler
- Department of Neuroradiology, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Ileana L Hanganu-Opatz
- Institute of Developmental Neurophysiology, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany
| | - Jason P Lerch
- Mouse Imaging Centre, Hospital for Sick Children, Toronto, ON, M5T 3H7, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, ON, M5S 1A1, Canada
- Wellcome Centre for Integrative Neuroimaging, The University of Oxford, Oxford, OX3 9DU, UK
| | - Karun K Singh
- Krembil Research Institute, Donald K. Johnson Eye Institute, University Health Network, 60 Leonard Ave, Toronto, ON, M5T 0S8, Canada
- Faculty of Medicine, University of Toronto, Medical Sciences Building, 1 King's College Cir, Toronto, ON, M5S 1A8, Canada
| | - Froylan Calderon de Anda
- Institute of Developmental Neurophysiology, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany.
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25
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Costa AC, Sousa MM. The Role of Spastin in Axon Biology. Front Cell Dev Biol 2022; 10:934522. [PMID: 35865632 PMCID: PMC9294387 DOI: 10.3389/fcell.2022.934522] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 06/07/2022] [Indexed: 12/05/2022] Open
Abstract
Neurons are highly polarized cells with elaborate shapes that allow them to perform their function. In neurons, microtubule organization—length, density, and dynamics—are essential for the establishment of polarity, growth, and transport. A mounting body of evidence shows that modulation of the microtubule cytoskeleton by microtubule-associated proteins fine tunes key aspects of neuronal cell biology. In this respect, microtubule severing enzymes—spastin, katanin and fidgetin—a group of microtubule-associated proteins that bind to and generate internal breaks in the microtubule lattice, are emerging as key modulators of the microtubule cytoskeleton in different model systems. In this review, we provide an integrative view on the latest research demonstrating the key role of spastin in neurons, specifically in the context of axonal cell biology. We focus on the function of spastin in the regulation of microtubule organization, and axonal transport, that underlie its importance in the intricate control of axon growth, branching and regeneration.
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Affiliation(s)
- Ana Catarina Costa
- Nerve Regeneration Group, Instituto de Biologia Molecular e Celular (IBMC), Instituto de Investigação e Inovação Em Saúde (i3S), University of Porto, Porto, Portugal
- Graduate Program in Molecular and Cell Biology, Instituto de Ciências Biomédicas Abel Salazar (ICBAS), University of Porto, Porto, Portugal
- *Correspondence: Ana Catarina Costa, ; Monica Mendes Sousa,
| | - Monica Mendes Sousa
- Nerve Regeneration Group, Instituto de Biologia Molecular e Celular (IBMC), Instituto de Investigação e Inovação Em Saúde (i3S), University of Porto, Porto, Portugal
- *Correspondence: Ana Catarina Costa, ; Monica Mendes Sousa,
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26
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Khan S. Endoplasmic Reticulum in Metaplasticity: From Information Processing to Synaptic Proteostasis. Mol Neurobiol 2022; 59:5630-5655. [PMID: 35739409 DOI: 10.1007/s12035-022-02916-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 06/05/2022] [Indexed: 11/29/2022]
Abstract
The ER (endoplasmic reticulum) is a Ca2+ reservoir and the unique protein-synthesizing machinery which is distributed throughout the neuron and composed of multiple different structural domains. One such domain is called EMC (endoplasmic reticulum membrane protein complex), pleiotropic nature in cellular functions. The ER/EMC position inside the neurons unmasks its contribution to synaptic plasticity via regulating various cellular processes from protein synthesis to Ca2+ signaling. Since presynaptic Ca2+ channels and postsynaptic ionotropic receptors are organized into the nanodomains, thus ER can be a crucial player in establishing TMNCs (transsynaptic molecular nanocolumns) to shape efficient neural communications. This review hypothesized that ER is not only involved in stress-mediated neurodegeneration but also axon regrowth, remyelination, neurotransmitter switching, information processing, and regulation of pre- and post-synaptic functions. Thus ER might not only be a protein-synthesizing and quality control machinery but also orchestrates plasticity of plasticity (metaplasticity) within the neuron to execute higher-order brain functions and neural repair.
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Affiliation(s)
- Shumsuzzaman Khan
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, USA.
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27
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Deng C, Reinhard S, Hennlein L, Eilts J, Sachs S, Doose S, Jablonka S, Sauer M, Moradi M, Sendtner M. Impaired dynamic interaction of axonal endoplasmic reticulum and ribosomes contributes to defective stimulus-response in spinal muscular atrophy. Transl Neurodegener 2022; 11:31. [PMID: 35650592 PMCID: PMC9161492 DOI: 10.1186/s40035-022-00304-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 04/28/2022] [Indexed: 11/19/2022] Open
Abstract
Background Axonal degeneration and defects in neuromuscular neurotransmission represent a pathological hallmark in spinal muscular atrophy (SMA) and other forms of motoneuron disease. These pathological changes do not only base on altered axonal and presynaptic architecture, but also on alterations in dynamic movements of organelles and subcellular structures that are not necessarily reflected by static histopathological changes. The dynamic interplay between the axonal endoplasmic reticulum (ER) and ribosomes is essential for stimulus-induced local translation in motor axons and presynaptic terminals. However, it remains enigmatic whether the ER and ribosome crosstalk is impaired in the presynaptic compartment of motoneurons with Smn (survival of motor neuron) deficiency that could contribute to axonopathy and presynaptic dysfunction in SMA. Methods Using super-resolution microscopy, proximity ligation assay (PLA) and live imaging of cultured motoneurons from a mouse model of SMA, we investigated the dynamics of the axonal ER and ribosome distribution and activation. Results We observed that the dynamic remodeling of ER was impaired in axon terminals of Smn-deficient motoneurons. In addition, in axon terminals of Smn-deficient motoneurons, ribosomes failed to respond to the brain-derived neurotrophic factor stimulation, and did not undergo rapid association with the axonal ER in response to extracellular stimuli. Conclusions These findings implicate impaired dynamic interplay between the ribosomes and ER in axon terminals of motoneurons as a contributor to the pathophysiology of SMA and possibly also other motoneuron diseases. Supplementary Information The online version contains supplementary material available at 10.1186/s40035-022-00304-2.
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Affiliation(s)
- Chunchu Deng
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, 97078, Würzburg, Germany
| | - Sebastian Reinhard
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-University Wuerzburg, 97074, Würzburg, Germany
| | - Luisa Hennlein
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, 97078, Würzburg, Germany
| | - Janna Eilts
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-University Wuerzburg, 97074, Würzburg, Germany
| | - Stefan Sachs
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-University Wuerzburg, 97074, Würzburg, Germany
| | - Sören Doose
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-University Wuerzburg, 97074, Würzburg, Germany
| | - Sibylle Jablonka
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, 97078, Würzburg, Germany
| | - Markus Sauer
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-University Wuerzburg, 97074, Würzburg, Germany
| | - Mehri Moradi
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, 97078, Würzburg, Germany.
| | - Michael Sendtner
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, 97078, Würzburg, Germany.
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28
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Zamponi E, Meehl JB, Voeltz GK. The ER ladder is a unique morphological feature of developing mammalian axons. Dev Cell 2022; 57:1369-1382.e6. [PMID: 35609616 DOI: 10.1016/j.devcel.2022.05.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 03/28/2022] [Accepted: 05/02/2022] [Indexed: 11/25/2022]
Abstract
The endoplasmic reticulum (ER) confronts a challenge to accommodate long, smooth ER tubules into the structural complexity of the axonal compartment. Here, we describe a morphological feature for the axonal ER network in developing neurons we termed the ER ladder. Axonal ER ladders are composed of rungs that wrap tightly around the microtubule bundle and dynamic rails, which slide across microtubules. We found that the ER-shaping protein Reticulon 2 determines the architecture and dynamics of the axonal ER ladder by modulating its interaction with microtubules. Moreover, we show that ER ladder depletion impairs the trafficking of associated vesicular axonal cargoes. Finally, we demonstrate that stromal interaction molecule 1 (Stim1) localizes to ER rungs and translocates to ER-plasma membrane contact sites upon depletion of luminal Ca2+. Our findings uncover fundamental insights into the structural and functional organization of the axonal ER network in developing mammalian neurons.
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Affiliation(s)
- Emiliano Zamponi
- Department of Molecular, Cellular & Developmental Biology, University of Colorado Boulder, Boulder, CO 80309, USA; Howard Hughes Medical Institute, Boulder, CO 80309, USA
| | - Janet B Meehl
- Department of Molecular, Cellular & Developmental Biology, University of Colorado Boulder, Boulder, CO 80309, USA; Howard Hughes Medical Institute, Boulder, CO 80309, USA
| | - Gia K Voeltz
- Department of Molecular, Cellular & Developmental Biology, University of Colorado Boulder, Boulder, CO 80309, USA; Howard Hughes Medical Institute, Boulder, CO 80309, USA.
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29
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A role for endoplasmic reticulum dynamics in the cellular distribution of microtubules. Proc Natl Acad Sci U S A 2022; 119:e2104309119. [PMID: 35377783 PMCID: PMC9169640 DOI: 10.1073/pnas.2104309119] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The endoplasmic reticulum (ER) and the microtubule (MT) cytoskeleton form a coextensive, dynamic system that pervades eukaryotic cells. The shape of the ER is generated by a set of evolutionarily conserved membrane proteins that are able to control ER morphology and dynamics independently of MTs. Here we uncover that the molecular machinery that determines ER network dynamics can influence the subcellular distribution of MTs. We show that active control of local ER tubule junction density by ER tethering and fusion is important for the spatial organization of the combined ER–MT system. Our work suggests that cells might alter ER junction dynamics to drive formation of MT bundles, which are important structures, e.g., in migrating cells or in neuronal axons. The dynamic distribution of the microtubule (MT) cytoskeleton is crucial for the shape, motility, and internal organization of eukaryotic cells. However, the basic principles that control the subcellular position of MTs in mammalian interphase cells remain largely unknown. Here we show by a combination of microscopy and computational modeling that the dynamics of the endoplasmic reticulum (ER) plays an important role in distributing MTs in the cell. Specifically, our physics-based model of the ER–MT system reveals that spatial inhomogeneity in the density of ER tubule junctions results in an overall contractile force that acts on MTs and influences their distribution. At steady state, cells rapidly compensate for local variability of ER junction density by dynamic formation, release, and movement of ER junctions across the ER. Perturbation of ER junction tethering and fusion by depleting the ER fusogens called atlastins disrupts the dynamics of junction equilibration, rendering the ER–MT system unstable and causing the formation of MT bundles. Our study points to a mechanical role of ER dynamics in cellular organization and suggests a mechanism by which cells might dynamically regulate MT distribution in, e.g., motile cells or in the formation and maintenance of neuronal axons.
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30
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Nedozralova H, Basnet N, Ibiricu I, Bodakuntla S, Biertümpfel C, Mizuno N. In situ cryo-electron tomography reveals local cellular machineries for axon branch development. J Biophys Biochem Cytol 2022; 221:213057. [PMID: 35262630 PMCID: PMC8916118 DOI: 10.1083/jcb.202106086] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 11/23/2021] [Accepted: 01/31/2022] [Indexed: 01/02/2023] Open
Abstract
Neurons are highly polarized cells forming an intricate network of dendrites and axons. They are shaped by the dynamic reorganization of cytoskeleton components and cellular organelles. Axon branching allows the formation of new paths and increases circuit complexity. However, our understanding of branch formation is sparse due to the lack of direct in-depth observations. Using in situ cellular cryo-electron tomography on primary mouse neurons, we directly visualized the remodeling of organelles and cytoskeleton structures at axon branches. Strikingly, branched areas functioned as hotspots concentrating organelles to support dynamic activities. Unaligned actin filaments assembled at the base of premature branches accompanied by filopodia-like protrusions. Microtubules and ER comigrated into preformed branches to support outgrowth together with accumulating compact, ∼500-nm mitochondria and locally clustered ribosomes. We obtained a roadmap of events supporting the hypothesis of local protein synthesis selectively taking place at axon branches, allowing them to serve as unique control hubs for axon development and downstream neural network formation.
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Affiliation(s)
- Hana Nedozralova
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Martinsried, Germany.,Laboratory of Structural Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Nirakar Basnet
- Laboratory of Structural Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Iosune Ibiricu
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Satish Bodakuntla
- Laboratory of Structural Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Christian Biertümpfel
- Laboratory of Structural Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Naoko Mizuno
- Laboratory of Structural Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD.,National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD
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31
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Host cytoskeletal vimentin serves as a structural organizer and an RNA-binding protein regulator to facilitate Zika viral replication. Proc Natl Acad Sci U S A 2022; 119:2113909119. [PMID: 35193960 PMCID: PMC8872754 DOI: 10.1073/pnas.2113909119] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/04/2022] [Indexed: 01/15/2023] Open
Abstract
We discovered a dual role of vimentin underlying Zika virus (ZIKV) replication. The vimentin network reorganizes to surround the replication complex. Depletion of vimentin resulted in drastic segregation of viral proteins and subsequent defective infection, indicating its function as an “organizer” that ensures the concentration of all necessary factors for high replication efficacy. With omics analysis, we prove that vimentin also functions as a “regulator” that dominates RNA-binding proteins during infection. These two roles complement one another to make an integrated view of vimentin in regulating ZIKV infection. Collectively, our study fills the long-term gap in our knowledge of the cellular function of intermediate filaments in addition to structural support and provides a potential target for ZIKV therapy. Emerging microbe infections, such as Zika virus (ZIKV), pose an increasing threat to human health. Investigations on ZIKV replication have revealed the construction of replication complexes (RCs), but the role of cytoskeleton in this process is largely unknown. Here, we investigated the function of cytoskeletal intermediate filament protein vimentin in the life cycle of ZIKV infection. Using advanced imaging techniques, we uncovered that vimentin filaments undergo drastic reorganization upon viral protein synthesis to form a perinuclear cage-like structure that embraces and concentrates RCs. Genetic removal of vimentin markedly disrupted the integrity of RCs and resulted in fragmented subcellular dispersion of viral proteins. This led to reduced viral genome replication, viral protein production, and release of infectious virions, without interrupting viral binding and entry. Furthermore, mass spectrometry and RNA-sequencing screens identified interactions and interplay between vimentin and hundreds of endoplasmic reticulum (ER)-resident RNA-binding proteins. Among them, the cytoplasmic-region of ribosome receptor binding protein 1, an ER transmembrane protein that directly binds viral RNA, interacted with and was regulated by vimentin, resulting in modulation of ZIKV replication. Together, the data in our work reveal a dual role for vimentin as a structural element for RC integrity and as an RNA-binding-regulating hub during ZIKV infection, thus unveiling a layer of interplay between Zika virus and host cell.
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Foster HE, Ventura Santos C, Carter AP. A cryo-ET survey of microtubules and intracellular compartments in mammalian axons. J Cell Biol 2022; 221:e202103154. [PMID: 34878519 PMCID: PMC7612188 DOI: 10.1083/jcb.202103154] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 09/28/2021] [Accepted: 11/16/2021] [Indexed: 12/16/2022] Open
Abstract
The neuronal axon is packed with cytoskeletal filaments, membranes, and organelles, many of which move between the cell body and axon tip. Here, we used cryo-electron tomography to survey the internal components of mammalian sensory axons. We determined the polarity of the axonal microtubules (MTs) by combining subtomogram classification and visual inspection, finding MT plus and minus ends are structurally similar. Subtomogram averaging of globular densities in the MT lumen suggests they have a defined structure, which is surprising given they likely contain the disordered protein MAP6. We found the endoplasmic reticulum in axons is tethered to MTs through multiple short linkers. We surveyed membrane-bound cargos and describe unexpected internal features such as granules and broken membranes. In addition, we detected proteinaceous compartments, including numerous virus-like capsid particles. Our observations outline novel features of axonal cargos and MTs, providing a platform for identification of their constituents.
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TREX1 Deficiency Induces ER Stress-Mediated Neuronal Cell Death by Disrupting Ca 2+ Homeostasis. Mol Neurobiol 2022; 59:1398-1418. [PMID: 34997539 PMCID: PMC8882114 DOI: 10.1007/s12035-021-02631-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 11/01/2021] [Indexed: 11/09/2022]
Abstract
TREX1 is an exonuclease that degrades extranuclear DNA species in mammalian cells. Herein, we show a novel mechanism by which TREX1 interacts with the BiP/GRP78 and TREX1 deficiency triggers ER stress through the accumulation of single-stranded DNA and activates unfolded protein response (UPR) signaling via the disruption of the TREX1-BiP/GRP78 interaction. In TREX1 knockdown cells, the activation of ER stress signaling disrupted ER Ca2+ homeostasis via the ERO1α-IP3R1-CaMKII pathway, leading to neuronal cell death. Moreover, TREX1 knockdown dysregulated the Golgi-microtubule network through Golgi fragmentation and decreased Ac-α-tubulin levels, contributing to neuronal injury. These alterations were also observed in neuronal cells harboring a TREX1 mutation (V91M) that has been identified in hereditary spastic paraplegia (HSP) patients in Korea. Notably, this mutation leads to defects in the TREX1-BiP/GRP78 interaction and mislocalization of TREX1 from the ER and possible disruption of the Golgi-microtubule network. In summary, the current study reveals TREX1 as a novel regulator of the BiP/GRP78 interaction and shows that TREX1 deficiency promotes ER stress-mediated neuronal cell death, which indicates that TREX1 may hold promise as a therapeutic target for neurodegenerative diseases such as HSP.
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34
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Moving the ER tip by tip. Dev Cell 2021; 56:3305-3306. [PMID: 34932946 DOI: 10.1016/j.devcel.2021.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Endoplasmic reticulum (ER) and microtubule (MT) interactions have been observed in different cell types. However, how these interactions are regulated remains unknown. In this issue of Developmental Cell, Nourbakhsh et al. show that an ER-localized kinase, TAOK2, catalyzes the dynamic tethering of the ER tip to the MT tip.
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Nourbakhsh K, Ferreccio AA, Bernard MJ, Yadav S. TAOK2 is an ER-localized kinase that catalyzes the dynamic tethering of ER to microtubules. Dev Cell 2021; 56:3321-3333.e5. [PMID: 34879262 PMCID: PMC8699727 DOI: 10.1016/j.devcel.2021.11.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 09/17/2021] [Accepted: 11/15/2021] [Indexed: 01/07/2023]
Abstract
The endoplasmic reticulum (ER) depends on extensive association with the microtubule (MT) cytoskeleton for its structure and mitotic inheritance. However, mechanisms that underlie coupling of ER membranes to MTs are poorly understood. We have identified thousand and one amino acid kinase 2 (TAOK2) as a pleiotropic protein kinase that mediates tethering of ER to MTs. In human cells, TAOK2 localizes in distinct ER subdomains via transmembrane helices and an adjacent amphipathic region. Through its C-terminal tail, TAOK2 directly binds MTs, coupling ER membranes to the MT cytoskeleton. In TAOK2 knockout cells, although ER-membrane dynamics are increased, movement of ER along growing MT plus ends is disrupted. ER-MT tethering is tightly regulated by catalytic activity of TAOK2, perturbation of which leads to defects in ER morphology, association with MTs, and cell division. Our study identifies TAOK2 as an ER-MT tether and reveals a kinase-regulated mechanism for control of ER dynamics.
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Affiliation(s)
- Kimya Nourbakhsh
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Amy A Ferreccio
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Matthew J Bernard
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Smita Yadav
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA; Institute of Stem Cell and Regenerative Medicine, Seattle, WA 98109, USA.
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ER proteins decipher the tubulin code to regulate organelle distribution. Nature 2021; 601:132-138. [PMID: 34912111 PMCID: PMC8732269 DOI: 10.1038/s41586-021-04204-9] [Citation(s) in RCA: 73] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 11/03/2021] [Indexed: 11/08/2022]
Abstract
Organelles move along differentially modified microtubules to establish and maintain their proper distributions and functions1,2. However, how cells interpret these post-translational microtubule modification codes to selectively regulate organelle positioning remains largely unknown. The endoplasmic reticulum (ER) is an interconnected network of diverse morphologies that extends promiscuously throughout the cytoplasm3, forming abundant contacts with other organelles4. Dysregulation of endoplasmic reticulum morphology is tightly linked to neurologic disorders and cancer5,6. Here we demonstrate that three membrane-bound endoplasmic reticulum proteins preferentially interact with different microtubule populations, with CLIMP63 binding centrosome microtubules, kinectin (KTN1) binding perinuclear polyglutamylated microtubules, and p180 binding glutamylated microtubules. Knockout of these proteins or manipulation of microtubule populations and glutamylation status results in marked changes in endoplasmic reticulum positioning, leading to similar redistributions of other organelles. During nutrient starvation, cells modulate CLIMP63 protein levels and p180-microtubule binding to bidirectionally move endoplasmic reticulum and lysosomes for proper autophagic responses.
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Fuchs J, Eickholt BJ. Precursor types predict the stability of neuronal branches. J Cell Sci 2021; 134:273430. [PMID: 34766183 PMCID: PMC8714070 DOI: 10.1242/jcs.258983] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 11/03/2021] [Indexed: 11/20/2022] Open
Abstract
Branches are critical for neuron function, generating the morphological complexity required for functional networks. They emerge from different, well-described, cytoskeletal precursor structures that elongate to branches. While branches are thought to be maintained by shared cytoskeletal regulators, our data from mouse hippocampal neurons indicate that the precursor structures trigger alternative branch maintenance mechanisms with differing stabilities. Whereas branches originating from lamellipodia or growth cone splitting events collapse soon after formation, branches emerging from filopodia persist. Furthermore, compared to other developing neurites, axons stabilise all branches and preferentially initiate branches from filopodia. These differences explain the altered stability of branches we observe in neurons lacking the plasma membrane protein phospholipid phosphatase-related protein 3 (PLPPR3, also known as PRG2) and in neurons treated with netrin-1. Rather than altering branch stability directly, PLPPR3 and netrin-1 boost a 'filopodia branch programme' on axons, thereby indirectly initiating more long-lived branches. In summary, we propose that studies on branching should distinguish overall stabilising effects from effects on precursor types, ideally using multifactorial statistical models, as exemplified in this study.
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Affiliation(s)
- Joachim Fuchs
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Molecular Biology and Biochemistry, Virchowweg 6, 10117 Berlin, Germany
| | - Britta J Eickholt
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Molecular Biology and Biochemistry, Virchowweg 6, 10117 Berlin, Germany
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Deng C, Moradi M, Reinhard S, Ji C, Jablonka S, Hennlein L, Lüningschrör P, Doose S, Sauer M, Sendtner M. Dynamic remodeling of ribosomes and endoplasmic reticulum in axon terminals of motoneurons. J Cell Sci 2021; 134:272552. [PMID: 34668554 DOI: 10.1242/jcs.258785] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 10/14/2021] [Indexed: 12/23/2022] Open
Abstract
In neurons, the endoplasmic reticulum (ER) forms a highly dynamic network that enters axons and presynaptic terminals and plays a central role in Ca2+ homeostasis and synapse maintenance; however, the underlying mechanisms involved in regulation of its dynamic remodeling as well as its function in axon development and presynaptic differentiation remain elusive. Here, we used high-resolution microscopy and live-cell imaging to investigate rapid movements of the ER and ribosomes in axons of cultured motoneurons after stimulation with brain-derived neurotrophic factor. Our results indicate that the ER extends into axonal growth cone filopodia, where its integrity and dynamic remodeling are regulated mainly by actin and the actin-based motor protein myosin VI (encoded by Myo6). Additionally, we found that in axonal growth cones, ribosomes assemble into 80S subunits within seconds and associate with the ER in response to extracellular stimuli, which describes a novel function of axonal ER in dynamic regulation of local translation. This article has an associated First Person interview with Chunchu Deng, joint first author of the paper.
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Affiliation(s)
- Chunchu Deng
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Mehri Moradi
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Sebastian Reinhard
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-University Würzburg, 97074 Würzburg, Germany
| | - Changhe Ji
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Sibylle Jablonka
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Luisa Hennlein
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Patrick Lüningschrör
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Sören Doose
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-University Würzburg, 97074 Würzburg, Germany
| | - Markus Sauer
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-University Würzburg, 97074 Würzburg, Germany
| | - Michael Sendtner
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
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39
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Zheng H. Partnership in action: The endoplasmic reticulum regulates the cytoskeleton. JOURNAL OF PLANT PHYSIOLOGY 2021; 266:153540. [PMID: 34619556 DOI: 10.1016/j.jplph.2021.153540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 09/28/2021] [Accepted: 09/28/2021] [Indexed: 06/13/2023]
Abstract
The endoplasmic reticulum (ER) and the cytoskeleton are functionally linked in living cells. Past research has focused on how the cytoskeleton regulates ER dynamics. How the ER may contribute to cytoskeletal dynamics has been overlooked. In this commentary, I examined how the ER mediates actin and microtubule dynamics in plant cells.
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Affiliation(s)
- Huanquan Zheng
- Department of Biology, McGill University, 1205 Dr Penfield Avenue, Montreal, H3A 1B1, Canada.
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40
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ER Morphology in the Pathogenesis of Hereditary Spastic Paraplegia. Cells 2021; 10:cells10112870. [PMID: 34831093 PMCID: PMC8616106 DOI: 10.3390/cells10112870] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 10/18/2021] [Accepted: 10/20/2021] [Indexed: 12/18/2022] Open
Abstract
The endoplasmic reticulum (ER) is the most abundant and widespread organelle in cells. Its peculiar membrane architecture, formed by an intricate network of tubules and cisternae, is critical to its multifaceted function. Regulation of ER morphology is coordinated by a few ER-specific membrane proteins and is thought to be particularly important in neurons, where organized ER membranes are found even in the most distant neurite terminals. Mutation of ER-shaping proteins has been implicated in the neurodegenerative disease hereditary spastic paraplegia (HSP). In this review we discuss the involvement of these proteins in the pathogenesis of HSP, focusing on the experimental evidence linking their molecular function to disease onset. Although the precise biochemical activity of some ER-related HSP proteins has been elucidated, the pathological mechanism underlying ER-linked HSP is still undetermined and needs to be further investigated.
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41
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Liu Q, Zhang G, Ji Z, Lin H. Molecular and cellular mechanisms of spastin in neural development and disease (Review). Int J Mol Med 2021; 48:218. [PMID: 34664680 PMCID: PMC8547542 DOI: 10.3892/ijmm.2021.5051] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 09/29/2021] [Indexed: 12/26/2022] Open
Abstract
Spastin is a microtubule (MT)‑severing enzyme identified from mutations of hereditary spastic paraplegia in 1999 and extensive studies indicate its vital role in various cellular activities. In the past two decades, efforts have been made to understand the underlying molecular mechanisms of how spastin is linked to neural development and disease. Recent studies on spastin have unraveled the mechanistic processes of its MT‑severing activity and revealed that spastin acts as an MT amplifier to mediate its remodeling, thus providing valuable insight into the molecular roles of spastin under physiological conditions. In addition, recent research has revealed multiple novel molecular mechanisms of spastin in cellular biological pathways, including endoplasmic reticulum shaping, calcium trafficking, fatty acid trafficking, as well as endosomal fission and trafficking. These processes are closely involved in axonal and dendritic development and maintenance. The current review presents recent biological advances regarding the molecular mechanisms of spastin at the cellular level and provides insight into how it affects neural development and disease.
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Affiliation(s)
- Qiuling Liu
- Department of Orthopedics, The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong 510630, P.R. China
| | - Guowei Zhang
- Department of Orthopedics, The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong 510630, P.R. China
| | - Zhisheng Ji
- Department of Orthopedics, The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong 510630, P.R. China
| | - Hongsheng Lin
- Department of Orthopedics, The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong 510630, P.R. China
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42
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Sun J, Harion R, Naito T, Saheki Y. INPP5K and Atlastin-1 maintain the nonuniform distribution of ER-plasma membrane contacts in neurons. Life Sci Alliance 2021; 4:4/11/e202101092. [PMID: 34556534 PMCID: PMC8507493 DOI: 10.26508/lsa.202101092] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 09/03/2021] [Accepted: 09/11/2021] [Indexed: 02/04/2023] Open
Abstract
In neurons, the ER extends throughout all cellular processes, forming multiple contacts with the plasma membrane (PM) to fine-tune neuronal physiology. However, the mechanisms that regulate the distribution of neuronal ER-PM contacts are not known. Here, we used the Caenorhabditis elegans DA9 motor neuron as our model system and found that neuronal ER-PM contacts are enriched in soma and dendrite and mostly absent in axons. Using forward genetic screen, we identified that the inositol 5-phosphatase, CIL-1 (human INPP5K), and the dynamin-like GTPase, ATLN-1 (human Atlastin-1), help to maintain the non-uniform, somatodendritic enrichment of neuronal ER-PM contacts. Mechanistically, CIL-1 acts upstream of ATLN-1 to maintain the balance between ER tubules and sheets. In mutants of CIL-1 or ATLN-1, ER sheets expand and invade into the axon. This is accompanied by the ectopic formation of axonal ER-PM contacts and defects in axon regeneration following laser-induced axotomy. As INPP5K and Atlastin-1 have been linked to neurological disorders, the unique distribution of neuronal ER-PM contacts maintained by these proteins may support neuronal resilience during the onset and progression of these diseases.
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Affiliation(s)
- Jingbo Sun
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Raihanah Harion
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Tomoki Naito
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Yasunori Saheki
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore .,Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
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43
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Bodakuntla S, Nedozralova H, Basnet N, Mizuno N. Cytoskeleton and Membrane Organization at Axon Branches. Front Cell Dev Biol 2021; 9:707486. [PMID: 34540830 PMCID: PMC8440873 DOI: 10.3389/fcell.2021.707486] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 08/06/2021] [Indexed: 11/13/2022] Open
Abstract
Axon branching is a critical process ensuring a high degree of interconnectivity for neural network formation. As branching occurs at sites distant from the soma, it is necessary that axons have a local system to dynamically control and regulate axonal growth. This machinery depends on the orchestration of cellular functions such as cytoskeleton, subcellular transport, energy production, protein- and membrane synthesis that are adapted for branch formation. Compared to the axon shaft, branching sites show a distinct and dynamic arrangement of cytoskeleton components, endoplasmic reticulum and mitochondria. This review discusses the regulation of axon branching in the context of cytoskeleton and membrane remodeling.
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Affiliation(s)
- Satish Bodakuntla
- Laboratory of Structural Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, United States
| | - Hana Nedozralova
- Laboratory of Structural Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, United States
| | - Nirakar Basnet
- Laboratory of Structural Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, United States
| | - Naoko Mizuno
- Laboratory of Structural Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, United States.,National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, United States
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44
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Garcia-Pardo ME, Simpson JC, O'Sullivan NC. A novel automated image analysis pipeline for quantifying morphological changes to the endoplasmic reticulum in cultured human cells. BMC Bioinformatics 2021; 22:427. [PMID: 34496765 PMCID: PMC8425006 DOI: 10.1186/s12859-021-04334-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 08/24/2021] [Indexed: 11/10/2022] Open
Abstract
Background In mammalian cells the endoplasmic reticulum (ER) comprises a highly complex reticular morphology that is spread throughout the cytoplasm. This organelle is of particular interest to biologists, as its dysfunction is associated with numerous diseases, which often manifest themselves as changes to the structure and organisation of the reticular network. Due to its complex morphology, image analysis methods to quantitatively describe this organelle, and importantly any changes to it, are lacking. Results In this work we detail a methodological approach that utilises automated high-content screening microscopy to capture images of cells fluorescently-labelled for various ER markers, followed by their quantitative analysis. We propose that two key metrics, namely the area of dense ER and the area of polygonal regions in between the reticular elements, together provide a basis for measuring the quantities of rough and smooth ER, respectively. We demonstrate that a number of different pharmacological perturbations to the ER can be quantitatively measured and compared in our automated image analysis pipeline. Furthermore, we show that this method can be implemented in both commercial and open-access image analysis software with comparable results. Conclusions We propose that this method has the potential to be applied in the context of large-scale genetic and chemical perturbations to assess the organisation of the ER in adherent cell cultures. Supplementary Information The online version contains supplementary material available at 10.1186/s12859-021-04334-x.
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Affiliation(s)
- M Elena Garcia-Pardo
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland
| | - Jeremy C Simpson
- Cell Screening Laboratory, UCD School of Biology and Environmental Science, University College Dublin, Dublin 4, Ireland
| | - Niamh C O'Sullivan
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland.
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45
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Intertwined and Finely Balanced: Endoplasmic Reticulum Morphology, Dynamics, Function, and Diseases. Cells 2021; 10:cells10092341. [PMID: 34571990 PMCID: PMC8472773 DOI: 10.3390/cells10092341] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/02/2021] [Accepted: 09/04/2021] [Indexed: 02/07/2023] Open
Abstract
The endoplasmic reticulum (ER) is an organelle that is responsible for many essential subcellular processes. Interconnected narrow tubules at the periphery and thicker sheet-like regions in the perinuclear region are linked to the nuclear envelope. It is becoming apparent that the complex morphology and dynamics of the ER are linked to its function. Mutations in the proteins involved in regulating ER structure and movement are implicated in many diseases including neurodegenerative diseases such as Alzheimer’s, Parkinson’s, and amyotrophic lateral sclerosis (ALS). The ER is also hijacked by pathogens to promote their replication. Bacteria such as Legionella pneumophila and Chlamydia trachomatis, as well as the Zika virus, bind to ER morphology and dynamics-regulating proteins to exploit the functions of the ER to their advantage. This review covers our understanding of ER morphology, including the functional subdomains and membrane contact sites that the organelle forms. We also focus on ER dynamics and the current efforts to quantify ER motion and discuss the diseases related to ER morphology and dynamics.
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46
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Özkan N, Koppers M, van Soest I, van Harten A, Jurriens D, Liv N, Klumperman J, Kapitein LC, Hoogenraad CC, Farías GG. ER - lysosome contacts at a pre-axonal region regulate axonal lysosome availability. Nat Commun 2021; 12:4493. [PMID: 34301956 PMCID: PMC8302662 DOI: 10.1038/s41467-021-24713-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 07/01/2021] [Indexed: 11/16/2022] Open
Abstract
Neuronal function relies on careful coordination of organelle organization and transport. Kinesin-1 mediates transport of the endoplasmic reticulum (ER) and lysosomes into the axon and it is increasingly recognized that contacts between the ER and lysosomes influence organelle organization. However, it is unclear how organelle organization, inter-organelle communication and transport are linked and how this contributes to local organelle availability in neurons. Here, we show that somatic ER tubules are required for proper lysosome transport into the axon. Somatic ER tubule disruption causes accumulation of enlarged and less motile lysosomes at the soma. ER tubules regulate lysosome size and axonal translocation by promoting lysosome homo-fission. ER tubule - lysosome contacts often occur at a somatic pre-axonal region, where the kinesin-1-binding ER-protein P180 binds microtubules to promote kinesin-1-powered lysosome fission and subsequent axonal translocation. We propose that ER tubule - lysosome contacts at a pre-axonal region finely orchestrate axonal lysosome availability for proper neuronal function.
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Affiliation(s)
- Nazmiye Özkan
- Cell Biology, Neurobiology and Biophysics. Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Max Koppers
- Cell Biology, Neurobiology and Biophysics. Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Inge van Soest
- Cell Biology, Neurobiology and Biophysics. Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Alexandra van Harten
- Cell Biology, Neurobiology and Biophysics. Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Daphne Jurriens
- Cell Biology, Neurobiology and Biophysics. Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Nalan Liv
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Judith Klumperman
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Lukas C Kapitein
- Cell Biology, Neurobiology and Biophysics. Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Casper C Hoogenraad
- Cell Biology, Neurobiology and Biophysics. Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Ginny G Farías
- Cell Biology, Neurobiology and Biophysics. Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands.
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47
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Sharoar MG, Zhou J, Benoit M, He W, Yan R. Dynactin 6 deficiency enhances aging-associated dystrophic neurite formation in mouse brains. Neurobiol Aging 2021; 107:21-29. [PMID: 34371284 DOI: 10.1016/j.neurobiolaging.2021.07.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 06/17/2021] [Accepted: 07/07/2021] [Indexed: 11/25/2022]
Abstract
Formation of Reticulon 3 (RTN3)-immunoreactive dystrophic neurites (RIDNs) occurs early during the growth of amyloid plaques in Alzheimer's disease (AD) brains. We have shown that RIDNs in AD and aging mouse brains are composed of abnormally clustered tubular endoplasmic reticulum (ER) and degenerating mitochondria. To understand RTN3-mediated abnormal tubular ER clustering, we aimed to identify proteins that interact with RTN3 and impact accumulation of tubular ER in RIDNs. We found that the N-terminal domain of RTN3, which is unique among RTN family members, specifically interacted with dynactin 6 (DCTN6), a protein involved in dynein-mediated retrograde transport of cargo vesicles. DCTN6 protein levels decrease with aging in the hippocampal regions of WT mice. We found that DCTN6 deficiency enhanced RTN3 protein levels, high molecular weight RTN3 levels, and hippocampus-specific RIDN formation in aging brains of transgenic mice overexpressing RTN3. Our results suggest that the DCTN6-RTN3 interaction mediates tubular ER trafficking in axons, and a DCTN6 deficiency in the hippocampus impairs axonal ER trafficking, leading to abnormal ER accumulation and RIDN formation in brains of aging mice.
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Affiliation(s)
- Md Golam Sharoar
- Department of Neuroscience, University of Connecticut Health, Farmington, CT., USA.
| | - John Zhou
- Department of Neuroscience, University of Connecticut Health, Farmington, CT., USA; Molecular Medicine Graduate Program, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH., USA
| | - Marc Benoit
- Department of Neuroscience, University of Connecticut Health, Farmington, CT., USA
| | - Wanxia He
- Department of Neuroscience, University of Connecticut Health, Farmington, CT., USA; Molecular Medicine Graduate Program, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH., USA
| | - Riqiang Yan
- Department of Neuroscience, University of Connecticut Health, Farmington, CT., USA
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48
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Morphological Heterogeneity of the Endoplasmic Reticulum within Neurons and Its Implications in Neurodegeneration. Cells 2021; 10:cells10050970. [PMID: 33919188 PMCID: PMC8143122 DOI: 10.3390/cells10050970] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 04/13/2021] [Accepted: 04/19/2021] [Indexed: 12/19/2022] Open
Abstract
The endoplasmic reticulum (ER) is a multipurpose organelle comprising dynamic structural subdomains, such as ER sheets and tubules, serving to maintain protein, calcium, and lipid homeostasis. In neurons, the single ER is compartmentalized with a careful segregation of the structural subdomains in somatic and neurite (axodendritic) regions. The distribution and arrangement of these ER subdomains varies between different neuronal types. Mutations in ER membrane shaping proteins and morphological changes in the ER are associated with various neurodegenerative diseases implying significance of ER morphology in maintaining neuronal integrity. Specific neurons, such as the highly arborized dopaminergic neurons, are prone to stress and neurodegeneration. Differences in morphology and functionality of ER between the neurons may account for their varied sensitivity to stress and neurodegenerative changes. In this review, we explore the neuronal ER and discuss its distinct morphological attributes and specific functions. We hypothesize that morphological heterogeneity of the ER in neurons is an important factor that accounts for their selective susceptibility to neurodegeneration.
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49
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Koppers M, Farías GG. Organelle distribution in neurons: Logistics behind polarized transport. Curr Opin Cell Biol 2021; 71:46-54. [PMID: 33706233 DOI: 10.1016/j.ceb.2021.02.004] [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: 12/14/2020] [Revised: 01/26/2021] [Accepted: 02/04/2021] [Indexed: 12/20/2022]
Abstract
Highly polarized neurons need to carefully regulate the distribution of organelles and other cargoes into their two morphologically and functionally distinct domains, the somatodendritic and axonal compartments, to maintain proper neuron homeostasis. An outstanding question in the field is how organelles reach their correct destination. Long-range transport along microtubules, driven by motors, ensures a fast and controlled availability of organelles in axons and dendrites, but it remains largely unclear what rules govern their transport into the correct compartment. Here, we review the emerging concepts of polarized cargo trafficking in neurons, highlighting the role of microtubule organization, microtubule-associated proteins, and motor proteins and discuss compartment-specific inclusion and exclusion mechanisms as well as the regulation of correct coupling of cargoes to motor proteins.
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Affiliation(s)
- Max Koppers
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht 3584 CH, the Netherlands
| | - Ginny G Farías
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht 3584 CH, the Netherlands.
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50
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Axonal Organelles as Molecular Platforms for Axon Growth and Regeneration after Injury. Int J Mol Sci 2021; 22:ijms22041798. [PMID: 33670312 PMCID: PMC7918155 DOI: 10.3390/ijms22041798] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 02/06/2021] [Accepted: 02/08/2021] [Indexed: 02/06/2023] Open
Abstract
Investigating the molecular mechanisms governing developmental axon growth has been a useful approach for identifying new strategies for boosting axon regeneration after injury, with the goal of treating debilitating conditions such as spinal cord injury and vision loss. The picture emerging is that various axonal organelles are important centers for organizing the molecular mechanisms and machinery required for growth cone development and axon extension, and these have recently been targeted to stimulate robust regeneration in the injured adult central nervous system (CNS). This review summarizes recent literature highlighting a central role for organelles such as recycling endosomes, the endoplasmic reticulum, mitochondria, lysosomes, autophagosomes and the proteasome in developmental axon growth, and describes how these organelles can be targeted to promote axon regeneration after injury to the adult CNS. This review also examines the connections between these organelles in developing and regenerating axons, and finally discusses the molecular mechanisms within the axon that are required for successful axon growth.
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