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Viar GA, Pigino G. Tubulin posttranslational modifications through the lens of new technologies. Curr Opin Cell Biol 2024; 88:102362. [PMID: 38701611 DOI: 10.1016/j.ceb.2024.102362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 04/03/2024] [Accepted: 04/04/2024] [Indexed: 05/05/2024]
Abstract
The Tubulin Code revolutionizes our understanding of microtubule dynamics and functions, proposing a nuanced system governed by tubulin isotypes, posttranslational modifications (PTMs) and microtubule-associated proteins (MAPs). Tubulin isotypes, diverse across species, contribute structural complexity, and are thought to influence microtubule functions. PTMs encode dynamic information on microtubules, which are read by several microtubule interacting proteins and impact on cellular processes. Here we discuss recent technological and methodological advances, such as in genome engineering, live cell imaging, expansion microscopy, and cryo-electron microscopy that reveal new elements and levels of complexity of the tubulin code, including new modifying enzymes and nanopatterns of PTMs on individual microtubules. The Tubulin Code's exploration holds transformative potential, guiding therapeutic strategies and illuminating connections to diseases like cancer and neurodegenerative disorders, underscoring its relevance in decoding fundamental cellular language.
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Affiliation(s)
| | - Gaia Pigino
- Human Technopole, via Rita Levi Montalcini 1, Milan, Italy.
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2
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Cannariato M, Zizzi EA, Pallante L, Miceli M, Deriu MA. Mechanical communication within the microtubule through network-based analysis of tubulin dynamics. Biomech Model Mechanobiol 2024; 23:569-579. [PMID: 38060156 DOI: 10.1007/s10237-023-01792-5] [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: 07/24/2023] [Accepted: 11/11/2023] [Indexed: 12/08/2023]
Abstract
The identification of the mechanisms underlying the transfer of mechanical vibrations in protein complexes is crucial to understand how these super-assemblies are stabilized to perform specific functions within the cell. In this context, the study of the structural communication and the propagation of mechanical stimuli within the microtubule (MT) is important given the pivotal role of the latter in cell viability. In this study, we employed molecular modelling and the dynamical network analysis approaches to analyse the MT. The results highlight that β -tubulin drives the transfer of mechanical information between protofilaments (PFs), which is altered at the seam due to a different interaction pattern. Moreover, while the key residues involved in the structural communication along the PF are generally conserved, a higher diversity was observed for amino acids mediating the lateral communication. Taken together, these results might explain why MTs with different PF numbers are formed in different organisms or with different β -tubulin isotypes.
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Affiliation(s)
- Marco Cannariato
- PolitoBIOMed Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | - Eric A Zizzi
- PolitoBIOMed Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | - Lorenzo Pallante
- PolitoBIOMed Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | - Marcello Miceli
- PolitoBIOMed Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | - Marco A Deriu
- PolitoBIOMed Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy.
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3
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Abbaali I, Truong D, Day SD, Mushayeed F, Ganesh B, Haro-Ramirez N, Isles J, Nag H, Pham C, Shah P, Tomar I, Manel-Romero C, Morrissette NS. The tubulin database: Linking mutations, modifications, ligands and local interactions. PLoS One 2023; 18:e0295279. [PMID: 38064432 PMCID: PMC10707541 DOI: 10.1371/journal.pone.0295279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 11/20/2023] [Indexed: 12/18/2023] Open
Abstract
Microtubules are polymeric filaments, constructed of α-β tubulin heterodimers that underlie critical subcellular structures in eukaryotic organisms. Four homologous proteins (γ-, δ-, ε- and ζ-tubulin) additionally contribute to specialized microtubule functions. Although there is an immense volume of publicly available data pertaining to tubulins, it is difficult to assimilate all potentially relevant information across diverse organisms, isotypes, and categories of data. We previously assembled an extensive web-based catalogue of published missense mutations to tubulins with >1,500 entries that each document a specific substitution to a discrete tubulin, the species where the mutation was described and the associated phenotype with hyperlinks to the amino acid sequence and citation(s) for research. This report describes a significant update and expansion of our online resource (TubulinDB.bio.uci.edu) to nearly 18,000 entries. It now encompasses a cross-referenced catalog of post-translational modifications (PTMs) to tubulin drawn from public datasets, primary literature, and predictive algorithms. In addition, tubulin protein structures were used to define local interactions with bound ligands (GTP, GDP and diverse microtubule-targeting agents) and amino acids at the intradimer interface, within the microtubule lattice and with associated proteins. To effectively cross-reference these datasets, we established a universal tubulin numbering system to map entries into a common framework that accommodates specific insertions and deletions to tubulins. Indexing and cross-referencing permitted us to discern previously unappreciated patterns. We describe previously unlinked observations of loss of PTM sites in the context of cancer cells and tubulinopathies. Similarly, we expanded the set of clinical substitutions that may compromise MAP or microtubule-motor interactions by collecting tubulin missense mutations that alter amino acids at the interface with dynein and doublecortin. By expanding the database as a curated resource, we hope to relate model organism data to clinical findings of pathogenic tubulin variants. Ultimately, we aim to aid researchers in hypothesis generation and design of studies to dissect tubulin function.
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Affiliation(s)
- Izra Abbaali
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, United States of America
| | - Danny Truong
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, United States of America
| | - Shania Deon Day
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, United States of America
| | - Faliha Mushayeed
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, United States of America
| | - Bhargavi Ganesh
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, United States of America
| | - Nancy Haro-Ramirez
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, United States of America
| | - Juliet Isles
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, United States of America
| | - Hindol Nag
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, United States of America
| | - Catherine Pham
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, United States of America
| | - Priya Shah
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, United States of America
| | - Ishaan Tomar
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, United States of America
| | - Carolina Manel-Romero
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, United States of America
| | - Naomi S. Morrissette
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, United States of America
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4
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McKenna ED, Sarbanes SL, Cummings SW, Roll-Mecak A. The Tubulin Code, from Molecules to Health and Disease. Annu Rev Cell Dev Biol 2023; 39:331-361. [PMID: 37843925 DOI: 10.1146/annurev-cellbio-030123-032748] [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] [Indexed: 10/18/2023]
Abstract
Microtubules are essential dynamic polymers composed of α/β-tubulin heterodimers. They support intracellular trafficking, cell division, cellular motility, and other essential cellular processes. In many species, both α-tubulin and β-tubulin are encoded by multiple genes with distinct expression profiles and functionality. Microtubules are further diversified through abundant posttranslational modifications, which are added and removed by a suite of enzymes to form complex, stereotyped cellular arrays. The genetic and chemical diversity of tubulin constitute a tubulin code that regulates intrinsic microtubule properties and is read by cellular effectors, such as molecular motors and microtubule-associated proteins, to provide spatial and temporal specificity to microtubules in cells. In this review, we synthesize the rapidly expanding tubulin code literature and highlight limitations and opportunities for the field. As complex microtubule arrays underlie essential physiological processes, a better understanding of how cells employ the tubulin code has important implications for human disease ranging from cancer to neurological disorders.
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Affiliation(s)
- Elizabeth D McKenna
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland, USA;
| | - Stephanie L Sarbanes
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland, USA;
| | - Steven W Cummings
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland, USA;
| | - Antonina Roll-Mecak
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland, USA;
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, Bethesda, Maryland, USA
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5
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Carmona B, Marinho HS, Matos CL, Nolasco S, Soares H. Tubulin Post-Translational Modifications: The Elusive Roles of Acetylation. BIOLOGY 2023; 12:biology12040561. [PMID: 37106761 PMCID: PMC10136095 DOI: 10.3390/biology12040561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/27/2023] [Accepted: 04/03/2023] [Indexed: 04/29/2023]
Abstract
Microtubules (MTs), dynamic polymers of α/β-tubulin heterodimers found in all eukaryotes, are involved in cytoplasm spatial organization, intracellular transport, cell polarity, migration and division, and in cilia biology. MTs functional diversity depends on the differential expression of distinct tubulin isotypes and is amplified by a vast number of different post-translational modifications (PTMs). The addition/removal of PTMs to α- or β-tubulins is catalyzed by specific enzymes and allows combinatory patterns largely enriching the distinct biochemical and biophysical properties of MTs, creating a code read by distinct proteins, including microtubule-associated proteins (MAPs), which allow cellular responses. This review is focused on tubulin-acetylation, whose cellular roles continue to generate debate. We travel through the experimental data pointing to α-tubulin Lys40 acetylation role as being a MT stabilizer and a typical PTM of long lived MTs, to the most recent data, suggesting that Lys40 acetylation enhances MT flexibility and alters the mechanical properties of MTs, preventing MTs from mechanical aging characterized by structural damage. Additionally, we discuss the regulation of tubulin acetyltransferases/desacetylases and their impacts on cell physiology. Finally, we analyze how changes in MT acetylation levels have been found to be a general response to stress and how they are associated with several human pathologies.
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Affiliation(s)
- Bruno Carmona
- Centro de Química Estrutural, Institute of Molecular Sciences, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
- Escola Superior de Tecnologia da Saúde de Lisboa, Instituto Politécnico de Lisboa, Av. D. João II, Lote 4.69.01, 1990-096 Lisboa, Portugal
| | - H Susana Marinho
- Centro de Química Estrutural, Institute of Molecular Sciences, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
| | - Catarina Lopes Matos
- Centro de Química Estrutural, Institute of Molecular Sciences, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
| | - Sofia Nolasco
- Escola Superior de Tecnologia da Saúde de Lisboa, Instituto Politécnico de Lisboa, Av. D. João II, Lote 4.69.01, 1990-096 Lisboa, Portugal
- CIISA-Centro de Investigação Interdisciplinar em Sanidade Animal, Faculdade de Medicina Veterinária, Universidade de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
| | - Helena Soares
- Centro de Química Estrutural, Institute of Molecular Sciences, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
- Escola Superior de Tecnologia da Saúde de Lisboa, Instituto Politécnico de Lisboa, Av. D. João II, Lote 4.69.01, 1990-096 Lisboa, Portugal
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6
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Ferreira JL, Pražák V, Vasishtan D, Siggel M, Hentzschel F, Binder AM, Pietsch E, Kosinski J, Frischknecht F, Gilberger TW, Grünewald K. Variable microtubule architecture in the malaria parasite. Nat Commun 2023; 14:1216. [PMID: 36869034 PMCID: PMC9984467 DOI: 10.1038/s41467-023-36627-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 02/09/2023] [Indexed: 03/05/2023] Open
Abstract
Microtubules are a ubiquitous eukaryotic cytoskeletal element typically consisting of 13 protofilaments arranged in a hollow cylinder. This arrangement is considered the canonical form and is adopted by most organisms, with rare exceptions. Here, we use in situ electron cryo-tomography and subvolume averaging to analyse the changing microtubule cytoskeleton of Plasmodium falciparum, the causative agent of malaria, throughout its life cycle. Unexpectedly, different parasite forms have distinct microtubule structures coordinated by unique organising centres. In merozoites, the most widely studied form, we observe canonical microtubules. In migrating mosquito forms, the 13 protofilament structure is further reinforced by interrupted luminal helices. Surprisingly, gametocytes contain a wide distribution of microtubule structures ranging from 13 to 18 protofilaments, doublets and triplets. Such a diversity of microtubule structures has not been observed in any other organism to date and is likely evidence of a distinct role in each life cycle form. This data provides a unique view into an unusual microtubule cytoskeleton of a relevant human pathogen.
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Affiliation(s)
- Josie L Ferreira
- Centre for Structural Systems Biology, Hamburg, Germany
- Leibniz Institute for Virology (LIV), Hamburg, Germany
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- Institute of Structural and Molecular Biology, Birkbeck, University of London, London, UK
| | - Vojtěch Pražák
- Centre for Structural Systems Biology, Hamburg, Germany
- Leibniz Institute for Virology (LIV), Hamburg, Germany
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Daven Vasishtan
- Centre for Structural Systems Biology, Hamburg, Germany
- Leibniz Institute for Virology (LIV), Hamburg, Germany
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Marc Siggel
- Centre for Structural Systems Biology, Hamburg, Germany
- European Molecular Biology Laboratory, Hamburg, Germany
| | - Franziska Hentzschel
- Integrative Parasitology, Centre for Infectious Diseases, Heidelberg University Medical School, Heidelberg, Germany
- German Center for Infection Research, DZIF Partner Site Heidelberg, Heidelberg, Germany
| | - Annika M Binder
- Integrative Parasitology, Centre for Infectious Diseases, Heidelberg University Medical School, Heidelberg, Germany
| | - Emma Pietsch
- Centre for Structural Systems Biology, Hamburg, Germany
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- University of Hamburg, Hamburg, Germany
| | - Jan Kosinski
- Centre for Structural Systems Biology, Hamburg, Germany
- European Molecular Biology Laboratory, Hamburg, Germany
- Structural and Computational Biology Unit, EMBL, Heidelberg, Germany
| | - Friedrich Frischknecht
- Integrative Parasitology, Centre for Infectious Diseases, Heidelberg University Medical School, Heidelberg, Germany
- German Center for Infection Research, DZIF Partner Site Heidelberg, Heidelberg, Germany
| | - Tim W Gilberger
- Centre for Structural Systems Biology, Hamburg, Germany
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- University of Hamburg, Hamburg, Germany
| | - Kay Grünewald
- Centre for Structural Systems Biology, Hamburg, Germany.
- Leibniz Institute for Virology (LIV), Hamburg, Germany.
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK.
- University of Hamburg, Hamburg, Germany.
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7
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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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8
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O'Hagan R, Avrutis A, Ramicevic E. Functions of the tubulin code in the C. elegans nervous system. Mol Cell Neurosci 2022; 123:103790. [PMID: 36368428 DOI: 10.1016/j.mcn.2022.103790] [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: 06/30/2022] [Revised: 10/27/2022] [Accepted: 11/03/2022] [Indexed: 11/11/2022] Open
Abstract
Due to their elongated and polarized morphology, neurons rely on the microtubule (MT) cytoskeleton for their shape, as well as for efficient intracellular transport that maintains neuronal function, survival, and connectivity. Although all MTs are constructed from α- and β-tubulins that are highly conserved throughout eukaryotes, different MT networks within neurons exhibit different dynamics and functions. For example, molecular motors must be able to differentially recognize the axonal and dendritic MTs to deliver appropriate cargos to sensory endings and synaptic regions. The Tubulin Code hypothesis proposes that MTs can be specialized in form and function by chemical differences in their composition by inclusion of different α- and β-tubulins into the MT lattice, as well as differences in post-translational enzymatic modifications. The chemical differences encode information that allow MTs to regulate interactions with various microtubule-based molecular motors such as kinesins and dyneins as well as with structural microtubule-associated proteins (MAPs), which can, in turn, modify the function or stability of MTs. Here, we review studies involving C. elegans, a model organism with a relatively simple nervous system that is amenable to genetic analysis, that have contributed to our understanding of how the Tubulin Code can specialize neuronal MT networks to establish differences in neuronal morphology and function. Such studies have revealed molecules and mechanisms that are conserved in vertebrates and have the potential to inform our understanding of neurological diseases involving defects in the cytoskeleton and intracellular transport.
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Affiliation(s)
- Robert O'Hagan
- formerly at Biology Dept., Montclair State University, Montclair, NJ 07043, United States of America.
| | - Alexandra Avrutis
- formerly at Biology Dept., Montclair State University, Montclair, NJ 07043, United States of America
| | - Ema Ramicevic
- formerly at Biology Dept., Montclair State University, Montclair, NJ 07043, United States of America
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9
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Sexually dimorphic architecture and function of a mechanosensory circuit in C. elegans. Nat Commun 2022; 13:6825. [PMID: 36369281 PMCID: PMC9652301 DOI: 10.1038/s41467-022-34661-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 11/01/2022] [Indexed: 11/13/2022] Open
Abstract
How sensory perception is processed by the two sexes of an organism is still only partially understood. Despite some evidence for sexual dimorphism in auditory and olfactory perception, whether touch is sensed in a dimorphic manner has not been addressed. Here we find that the neuronal circuit for tail mechanosensation in C. elegans is wired differently in the two sexes and employs a different combination of sex-shared sensory neurons and interneurons in each sex. Reverse genetic screens uncovered cell- and sex-specific functions of the alpha-tubulin mec-12 and the sodium channel tmc-1 in sensory neurons, and of the glutamate receptors nmr-1 and glr-1 in interneurons, revealing the underlying molecular mechanisms that mediate tail mechanosensation. Moreover, we show that only in males, the sex-shared interneuron AVG is strongly activated by tail mechanical stimulation, and accordingly is crucial for their behavioral response. Importantly, sex reversal experiments demonstrate that the sexual identity of AVG determines both the behavioral output of the mechanosensory response and the molecular pathways controlling it. Our results present extensive sexual dimorphism in a mechanosensory circuit at both the cellular and molecular levels.
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10
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Kaulich E, Grundy LJ, Schafer WR, Walker DS. The diverse functions of the DEG/ENaC family: linking genetic and physiological insights. J Physiol 2022; 601:1521-1542. [PMID: 36314992 PMCID: PMC10148893 DOI: 10.1113/jp283335] [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: 07/06/2022] [Accepted: 10/25/2022] [Indexed: 11/06/2022] Open
Abstract
The DEG/ENaC family of ion channels was defined based on the sequence similarity between degenerins (DEG) from the nematode Caenorhabditis elegans and subunits of the mammalian epithelial sodium channel (ENaC), and also includes a diverse array of non-voltage-gated cation channels from across animal phyla, including the mammalian acid-sensing ion channels (ASICs) and Drosophila pickpockets. ENaCs and ASICs have wide ranging medical importance; for example, ENaCs play an important role in respiratory and renal function, and ASICs in ischaemia and inflammatory pain, as well as being implicated in memory and learning. Electrophysiological approaches, both in vitro and in vivo, have played an essential role in establishing the physiological properties of this diverse family, identifying an array of modulators and implicating them in an extensive range of cellular functions, including mechanosensation, acid sensation and synaptic modulation. Likewise, genetic studies in both invertebrates and vertebrates have played an important role in linking our understanding of channel properties to function at the cellular and whole animal/behavioural level. Drawing together genetic and physiological evidence is essential to furthering our understanding of the precise cellular roles of DEG/ENaC channels, with the diversity among family members allowing comparative physiological studies to dissect the molecular basis of these diverse functions.
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Affiliation(s)
- Eva Kaulich
- Neurobiology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, UK
| | - Laura J Grundy
- Neurobiology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, UK
| | - William R Schafer
- Neurobiology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, UK.,Department of Biology, KU Leuven, Leuven, Belgium
| | - Denise S Walker
- Neurobiology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, UK
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11
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Teoh JS, Dhananjay S, Neumann B. Mutation of the H12-helix of α-tubulin/MEC-12 disrupts the localization of neuronal mitochondria. MICROPUBLICATION BIOLOGY 2022; 2022:10.17912/micropub.biology.000659. [PMID: 36353120 PMCID: PMC9638805 DOI: 10.17912/micropub.biology.000659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 10/17/2022] [Accepted: 10/21/2022] [Indexed: 11/24/2022]
Abstract
Microtubules are essential components of the cytoskeleton that allow bi-lateral neuronal transport. Correct regulation of these complex intracellular transport processes is central to neuronal function. However, despite major advancements in our knowledge, we still lack a complete understanding on how neuronal transport is regulated. Here, we provide further evidence for the importance of the highly conserved N-terminal H12-helix of α-tubulin. We show that a mutation in this region results in the mistargeting of axonal mitochondria in Caenorhabditis elegans , thereby establishing the importance of the H12-helix in regulating mitochondrial transport in neurons.
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Affiliation(s)
- Jean-Sébastien Teoh
- Neuroscience Program, Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne VIC 3800 Australia
| | - Samiksha Dhananjay
- Neuroscience Program, Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne VIC 3800 Australia
| | - Brent Neumann
- Neuroscience Program, Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne VIC 3800 Australia.
,
Correspondence to: Brent Neumann (
)
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12
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Synaptic branch stability is mediated by non-enzymatic functions of MEC-17/αTAT1 and ATAT-2. Sci Rep 2022; 12:14003. [PMID: 35977998 PMCID: PMC9385713 DOI: 10.1038/s41598-022-18333-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 08/09/2022] [Indexed: 11/08/2022] Open
Abstract
Microtubules are fundamental elements of neuronal structure and function. They are dynamic structures formed from protofilament chains of α- and β-tubulin heterodimers. Acetylation of the lysine 40 (K40) residue of α-tubulin protects microtubules from mechanical stresses by imparting structural elasticity. The enzyme responsible for this acetylation event is MEC-17/αTAT1. Despite its functional importance, however, the consequences of altered MEC-17/αTAT1 levels on neuronal structure and function are incompletely defined. Here we demonstrate that overexpression or loss of MEC-17, or of its functional paralogue ATAT-2, causes a delay in synaptic branch extension, and defective synaptogenesis in the mechanosensory neurons of Caenorhabditis elegans. Strikingly, by adulthood, the synaptic branches in these animals are lost, while the main axon shaft remains mostly intact. We show that MEC-17 and ATAT-2 regulate the stability of the synaptic branches largely independently from their acetyltransferase domains. Genetic analyses reveals novel interactions between both mec-17 and atat-2 with the focal adhesion gene zyx-1/Zyxin, which has previously been implicated in actin remodelling. Together, our results reveal new, acetylation-independent roles for MEC-17 and ATAT-2 in the development and maintenance of neuronal architecture.
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Gasic I. Regulation of Tubulin Gene Expression: From Isotype Identity to Functional Specialization. Front Cell Dev Biol 2022; 10:898076. [PMID: 35721507 PMCID: PMC9204600 DOI: 10.3389/fcell.2022.898076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 05/11/2022] [Indexed: 12/14/2022] Open
Abstract
Genomes of higher eukaryotes encode a large tubulin gene superfamily consisting of at least six α and six β-tubulin isotypes. While some α and β-tubulin isotypes are ubiquitously expressed, others are cell-type specific. The subset of α and β-tubulins that is expressed in a given cell type is defined transcriptionally. But the precise mechanisms of how cells choose which α and β isotypes to express and at what level remain poorly understood. Differential expression of tubulin isotypes is particularly prominent during development and in specialized cells, suggesting that some isotypes are better suited for certain cell type-specific functions. Recent studies begin to rationalize this phenomenon, uncovering important differences in tubulin isotype behavior and their impact on the biomechanical properties of the microtubule cytoskeleton. I summarize our understanding of the regulation of tubulin isotype expression, focusing on the role of these complex regulatory pathways in building a customized microtubule network best suited for cellular needs.
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Affiliation(s)
- Ivana Gasic
- Department of Molecular and Cellular Biology, University of Geneva, Geneva, Switzerland
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14
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Drongitis D, Caterino M, Verrillo L, Santonicola P, Costanzo M, Poeta L, Attianese B, Barra A, Terrone G, Lioi MB, Paladino S, Di Schiavi E, Costa V, Ruoppolo M, Miano MG. Deregulation of microtubule organization and RNA metabolism in Arx models for lissencephaly and developmental epileptic encephalopathy. Hum Mol Genet 2022; 31:1884-1908. [PMID: 35094084 PMCID: PMC9169459 DOI: 10.1093/hmg/ddac028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 01/10/2022] [Accepted: 01/26/2022] [Indexed: 11/18/2022] Open
Abstract
X-linked lissencephaly with abnormal genitalia (XLAG) and developmental epileptic encephalopathy-1 (DEE1) are caused by mutations in the Aristaless-related homeobox (ARX) gene, which encodes a transcription factor responsible for brain development. It has been unknown whether the phenotypically diverse XLAG and DEE1 phenotypes may converge on shared pathways. To address this question, a label-free quantitative proteomic approach was applied to the neonatal brain of Arx knockout (ArxKO/Y) and knock-in polyalanine (Arx(GCG)7/Y) mice that are respectively models for XLAG and DEE1. Gene ontology and protein-protein interaction analysis revealed that cytoskeleton, protein synthesis and splicing control are deregulated in an allelic-dependent manner. Decreased α-tubulin content was observed both in Arx mice and Arx/alr-1(KO) Caenorhabditis elegans ,and a disorganized neurite network in murine primary neurons was consistent with an allelic-dependent secondary tubulinopathy. As distinct features of Arx(GCG)7/Y mice, we detected eIF4A2 overexpression and translational suppression in cortex and primary neurons. Allelic-dependent differences were also established in alternative splicing (AS) regulated by PUF60 and SAM68. Abnormal AS repertoires in Neurexin-1, a gene encoding multiple pre-synaptic organizers implicated in synaptic remodelling, were detected in Arx/alr-1(KO) animals and in Arx(GCG)7/Y epileptogenic brain areas and depolarized cortical neurons. Consistent with a conserved role of ARX in modulating AS, we propose that the allelic-dependent secondary synaptopathy results from an aberrant Neurexin-1 repertoire. Overall, our data reveal alterations mirroring the overlapping and variant effects caused by null and polyalanine expanded mutations in ARX. The identification of these effects can aid in the design of pathway-guided therapy for ARX endophenotypes and NDDs with overlapping comorbidities.
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Affiliation(s)
- Denise Drongitis
- Institute of Genetics and Biophysics ``Adriano Buzzati-Traverso'', National Research Council of Italy, 80131, Naples, Italy
| | - Marianna Caterino
- Department of Molecular Medicine and Medical Biotechnology, University of Naples “Federico II”, 80131 Naples, Italy
- CEINGE - Biotecnologie Avanzate s.c.a.r.l., 80145 Naples, Italy
| | - Lucia Verrillo
- Institute of Genetics and Biophysics ``Adriano Buzzati-Traverso'', National Research Council of Italy, 80131, Naples, Italy
| | - Pamela Santonicola
- Institute of Biosciences and BioResources, National Research Council of Italy, 80131, Naples, Italy
| | - Michele Costanzo
- Department of Molecular Medicine and Medical Biotechnology, University of Naples “Federico II”, 80131 Naples, Italy
- CEINGE - Biotecnologie Avanzate s.c.a.r.l., 80145 Naples, Italy
| | - Loredana Poeta
- Institute of Genetics and Biophysics ``Adriano Buzzati-Traverso'', National Research Council of Italy, 80131, Naples, Italy
- Department of Science, University of Basilicata, 85100 Potenza, Italy
| | - Benedetta Attianese
- Institute of Genetics and Biophysics ``Adriano Buzzati-Traverso'', National Research Council of Italy, 80131, Naples, Italy
| | - Adriano Barra
- Institute of Genetics and Biophysics ``Adriano Buzzati-Traverso'', National Research Council of Italy, 80131, Naples, Italy
| | - Gaetano Terrone
- Department of Translational Medicine, Child Neurology Unit, University of Naples “Federico II”, 80131 Naples, Italy
| | | | - Simona Paladino
- Department of Molecular Medicine and Medical Biotechnology, University of Naples “Federico II”, 80131 Naples, Italy
| | - Elia Di Schiavi
- Institute of Biosciences and BioResources, National Research Council of Italy, 80131, Naples, Italy
| | - Valerio Costa
- Institute of Genetics and Biophysics ``Adriano Buzzati-Traverso'', National Research Council of Italy, 80131, Naples, Italy
| | - Margherita Ruoppolo
- Department of Molecular Medicine and Medical Biotechnology, University of Naples “Federico II”, 80131 Naples, Italy
- CEINGE - Biotecnologie Avanzate s.c.a.r.l., 80145 Naples, Italy
| | - Maria Giuseppina Miano
- Institute of Genetics and Biophysics ``Adriano Buzzati-Traverso'', National Research Council of Italy, 80131, Naples, Italy
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15
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Chuang YC, Chen CC. Force From Filaments: The Role of the Cytoskeleton and Extracellular Matrix in the Gating of Mechanosensitive Channels. Front Cell Dev Biol 2022; 10:886048. [PMID: 35586339 PMCID: PMC9108448 DOI: 10.3389/fcell.2022.886048] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 04/19/2022] [Indexed: 01/16/2023] Open
Abstract
The senses of proprioception, touch, hearing, and blood pressure on mechanosensitive ion channels that transduce mechanical stimuli with high sensitivity and speed. This conversion process is usually called mechanotransduction. From nematode MEC-4/10 to mammalian PIEZO1/2, mechanosensitive ion channels have evolved into several protein families that use variant gating models to convert different forms of mechanical force into electrical signals. In addition to the model of channel gating by stretching from lipid bilayers, another potent model is the opening of channels by force tethering: a membrane-bound channel is elastically tethered directly or indirectly between the cytoskeleton and the extracellular molecules, and the tethering molecules convey force to change the channel structure into an activation form. In general, the mechanical stimulation forces the extracellular structure to move relative to the cytoskeleton, deforming the most compliant component in the system that serves as a gating spring. Here we review recent studies focusing on the ion channel mechanically activated by a tethering force, the mechanotransduction-involved cytoskeletal protein, and the extracellular matrix. The mechanosensitive channel PIEZO2, DEG/ENaC family proteins such as acid-sensing ion channels, and transient receptor potential family members such as NompC are discussed. State-of-the-art techniques, such as polydimethylsiloxane indentation, the pillar array, and micropipette-guided ultrasound stimulation, which are beneficial tools for exploring the tether model, are also discussed.
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Affiliation(s)
- Yu-Chia Chuang
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Chih-Cheng Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
- Neuroscience Program of Academia Sinica, Academia Sinica, Taipei, Taiwan
- Taiwan Mouse Clinic, BioTReC, Academia Sinica, Taipei, Taiwan
- *Correspondence: Chih-Cheng Chen,
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16
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Abstract
The microtubule cytoskeleton is assembled from the α- and β-tubulin subunits of the canonical tubulin heterodimer, which polymerizes into microtubules, and a small number of other family members, such as γ-tubulin, with specialized functions. Overall, microtubule function involves the collective action of multiple α- and β-tubulin isotypes. However, despite 40 years of awareness that most eukaryotes harbor multiple tubulin isotypes, their role in the microtubule cytoskeleton has remained relatively unclear. Various model organisms offer specific advantages for gaining insight into the role of tubulin isotypes. Whereas simple unicellular organisms such as yeast provide experimental tractability that can facilitate deeper access to mechanistic details, more complex organisms, such as the fruit fly, nematode and mouse, can be used to discern potential specialized functions of tissue- and structure-specific isotypes. Here, we review the role of α- and β-tubulin isotypes in microtubule function and in associated tubulinopathies with an emphasis on the advances gained using model organisms. Overall, we argue that studying tubulin isotypes in a range of organisms can reveal the fundamental mechanisms by which they mediate microtubule function. It will also provide valuable perspectives on how these mechanisms underlie the functional and biological diversity of the cytoskeleton.
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Affiliation(s)
- Emmanuel T Nsamba
- Genetics, Development, and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Mohan L Gupta
- Genetics, Development, and Cell Biology, Iowa State University, Ames, IA 50011, USA
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17
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Lu YM, Zheng C. The Expression and Function of Tubulin Isotypes in Caenorhabditis elegans. Front Cell Dev Biol 2022; 10:860065. [PMID: 35399537 PMCID: PMC8987236 DOI: 10.3389/fcell.2022.860065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Accepted: 02/28/2022] [Indexed: 11/13/2022] Open
Abstract
Microtubules, made from the polymerization of the highly conserved α/β-tubulin heterodimers, serve as important components of the cytoskeleton in all eukaryotic cells. The existence of multiple tubulin isotypes in metazoan genomes and a dazzling variety of tubulin posttranslational modifications (PTMs) prompted the “tubulin code” hypothesis, which proposed that microtubule structure and functions are determined by the tubulin composition and PTMs. Evidence for the tubulin code has emerged from studies in several organisms with the characterization of specific tubulins for their expression and functions. The studies of tubulin PTMs are accelerated by the discovery of the enzymes that add or remove the PTMs. In tubulin research, the use of simple organisms, such as Caenorhabditis elegans, has been instrumental for understanding the expression and functional specialization of tubulin isotypes and the effects of their PTMs. In this review, we summarize the current understanding of the expression patterns and cellular functions of the nine α-tubulin and six β-tubulin isotypes. Expression studies are greatly facilitated by the CRISPR/Cas9-mediated endogenous GFP knock-in reporters and the organism-wide single cell transcriptomic studies. Meanwhile, functional studies benefit from the ease of genetic manipulation and precise gene replacement in C. elegans. These studies identified both ubiquitously expressed tubulin isotypes and tissue-specific isotypes. The isotypes showed functional redundancy, as well as functional specificity, which is likely caused by the subtle differences in their amino acid sequences. Many of these differences concentrate at the C-terminal tails that are subjected to several PTMs. Indeed, tubulin PTM, such as polyglutamylation, is shown to modulate microtubule organization and properties in both ciliated and non-ciliated neurons. Overall, studies from C. elegans support the distinct expression and function patterns of tubulin isotypes and the importance of their PTMs and offer the promise of cracking the tubulin code at the whole-genome and the whole-organism level.
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18
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Functional roles of α 1-, α 2-, β 1-, β 2-tubulin in vegetative growth, microtubule assembly and sexual reproduction of Fusarium graminearum. Appl Environ Microbiol 2021; 87:e0096721. [PMID: 34378994 DOI: 10.1128/aem.00967-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The plant pathogen Fusarium graminearum contains two α-tubulin (α1 and α2) isotypes and two β-tubulin isotypes (β1 and β2). The functional roles of these tubulins in microtubule assembly are not clear. Previous studies showed that α1- and β2-tubulin deletion mutants showed severe growth defects and hypersensitivity to carbendazim, which have not been well explained. Here, we investigated the interaction between α- and β-tubulin of F. graminearum. Co-localization experiments demonstrated that β1- and β2-tubulin are co-localized. Co-immunoprecipitation experiment suggested that β1-tubulin binds to both α1- and α2-tubulin and β2-tubulin can also bind to α1- or α2-tubulin. Interestingly, deletion of α1-tubulin increased the interaction between β2-tubulin and α2-tubulin. Microtubule observation assays showed that deletion of α1-tubulin completely disrupted β1-tubulin-containing microtubules and significantly decreased β2-tubulin-containing microtubules. Deletion of α2-, β1- or β2-tubulin respectively had no obvious effect on the microtubule cytoskeleton. However, microtubules in α1- and β2-tubulin deletion mutants were easily depolymerized in the presence of carbendazim. The sexual reproduction assay indicates that α1- and β1-tubulin deletion mutants could not produce asci and ascospores. These results implied that α1-tubulin may be essential for the microtubule cytoskeleton. However, our Δα1-2×α2 mutant (α1-tubulin deletion mutant containing two copies of α2-tubulin) exhibited a normal microtubule network, growth and sexual reproduction. Interestingly, the Δα1-2×α2 mutant was still hypersensitive to carbendazim. In addition, both β1-tubulin and β2-tubulin were found to bind the mitochondrial outer membrane voltage-dependent anion channel (VDAC), indicating they could regulate the function of VDAC. Importance: In this study, we found that F. graminearum contains four different α-/β-tubulin heterodimers (α1-β1, α1-β2, α2-β1 and α2-β2) and they assemble together into a single microtubule. Moreover, α1-, α2-tubulins are functionally interchangeable in microtubule assembly, vegetative growth and sexual reproduction. These results provide more insights into functional roles of different tubulins of F. graminearum which could be helpful for purification of tubulin heterodimers and developing new tubulin-binding agents.
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19
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Nishida K, Tsuchiya K, Obinata H, Onodera S, Honda Y, Lai YC, Haruta N, Sugimoto A. Expression Patterns and Levels of All Tubulin Isotypes Analyzed in GFP Knock-In C. elegans Strains. Cell Struct Funct 2021; 46:51-64. [PMID: 33967119 PMCID: PMC10511039 DOI: 10.1247/csf.21022] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 04/28/2021] [Indexed: 11/11/2022] Open
Abstract
Most organisms have multiple α- and β-tubulin isotypes that likely contribute to the diversity of microtubule (MT) functions. To understand the functional differences of tubulin isotypes in Caenorhabditis elegans, which has nine α-tubulin isotypes and six β-tubulin isotypes, we systematically constructed null mutants and GFP-fusion strains for all tubulin isotypes with the CRISPR/Cas9 system and analyzed their expression patterns and levels in adult hermaphrodites. Four isotypes-α-tubulins TBA-1 and TBA-2 and β-tubulins TBB-1 and TBB-2-were expressed in virtually all tissues, with a distinct tissue-specific spectrum. Other isotypes were expressed in specific tissues or cell types at significantly lower levels than the broadly expressed isotypes. Four isotypes (TBA-5, TBA-6, TBA-9, and TBB-4) were expressed in different subsets of ciliated sensory neurons, and TBB-4 was inefficiently incorporated into mitotic spindle MTs. Taken together, we propose that MTs in C. elegans are mainly composed of four broadly expressed tubulin isotypes and that incorporation of a small amount of tissue-specific isotypes may contribute to tissue-specific MT properties. These newly constructed strains will be useful for further elucidating the distinct roles of tubulin isotypes.Key words: tubulin isotypes, microtubules, C. elegans.
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Affiliation(s)
- Kei Nishida
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Kenta Tsuchiya
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Hiroyuki Obinata
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Shizuka Onodera
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Yu Honda
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Yen-Cheng Lai
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Nami Haruta
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Asako Sugimoto
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
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20
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Jin P, Jan LY, Jan YN. Mechanosensitive Ion Channels: Structural Features Relevant to Mechanotransduction Mechanisms. Annu Rev Neurosci 2020; 43:207-229. [PMID: 32084327 DOI: 10.1146/annurev-neuro-070918-050509] [Citation(s) in RCA: 116] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Activation of mechanosensitive ion channels underlies a variety of fundamental physiological processes that require sensation of mechanical force. Different mechanosensitive channels adapt distinctive structures and mechanotransduction mechanisms to fit their biological roles. How mechanosensitive channels work, especially in animals, has been extensively studied in the past decade. Here we review key findings in the functional and structural characterizations of these channels and highlight the structural features relevant to the mechanotransduction mechanism of each specific channel.
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Affiliation(s)
- Peng Jin
- Department of Physiology, University of California, San Francisco, California 94158, USA;
| | - Lily Yeh Jan
- Department of Physiology, University of California, San Francisco, California 94158, USA; .,Department of Biochemistry and Biophysics and Howard Hughes Medical Institute, University of California, San Francisco, California 94158, USA
| | - Yuh-Nung Jan
- Department of Physiology, University of California, San Francisco, California 94158, USA; .,Department of Biochemistry and Biophysics and Howard Hughes Medical Institute, University of California, San Francisco, California 94158, USA
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21
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How Caenorhabditis elegans Senses Mechanical Stress, Temperature, and Other Physical Stimuli. Genetics 2019; 212:25-51. [PMID: 31053616 PMCID: PMC6499529 DOI: 10.1534/genetics.118.300241] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 03/04/2019] [Indexed: 12/30/2022] Open
Abstract
Caenorhabditis elegans lives in a complex habitat in which they routinely experience large fluctuations in temperature, and encounter physical obstacles that vary in size and composition. Their habitat is shared by other nematodes, by beneficial and harmful bacteria, and nematode-trapping fungi. Not surprisingly, these nematodes can detect and discriminate among diverse environmental cues, and exhibit sensory-evoked behaviors that are readily quantifiable in the laboratory at high resolution. Their ability to perform these behaviors depends on <100 sensory neurons, and this compact sensory nervous system together with powerful molecular genetic tools has allowed individual neuron types to be linked to specific sensory responses. Here, we describe the sensory neurons and molecules that enable C. elegans to sense and respond to physical stimuli. We focus primarily on the pathways that allow sensation of mechanical and thermal stimuli, and briefly consider this animal’s ability to sense magnetic and electrical fields, light, and relative humidity. As the study of sensory transduction is critically dependent upon the techniques for stimulus delivery, we also include a section on appropriate laboratory methods for such studies. This chapter summarizes current knowledge about the sensitivity and response dynamics of individual classes of C. elegans mechano- and thermosensory neurons from in vivo calcium imaging and whole-cell patch-clamp electrophysiology studies. We also describe the roles of conserved molecules and signaling pathways in mediating the remarkably sensitive responses of these nematodes to mechanical and thermal cues. These studies have shown that the protein partners that form mechanotransduction channels are drawn from multiple superfamilies of ion channel proteins, and that signal transduction pathways responsible for temperature sensing in C. elegans share many features with those responsible for phototransduction in vertebrates.
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22
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Ti SC, Alushin GM, Kapoor TM. Human β-Tubulin Isotypes Can Regulate Microtubule Protofilament Number and Stability. Dev Cell 2018; 47:175-190.e5. [PMID: 30245156 DOI: 10.1016/j.devcel.2018.08.014] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 06/28/2018] [Accepted: 08/20/2018] [Indexed: 10/28/2022]
Abstract
Cell biological studies have shown that protofilament number, a fundamental feature of microtubules, can correlate with the expression of different tubulin isotypes. However, it is not known if tubulin isotypes directly control this basic microtubule property. Here, we report high-resolution cryo-EM reconstructions (3.5-3.65 Å) of purified human α1B/β3 and α1B/β2B microtubules and find that the β-tubulin isotype can determine protofilament number. Comparisons of atomic models of 13- and 14-protofilament microtubules reveal how tubulin subunit plasticity, manifested in "accordion-like" distributed structural changes, can accommodate distinct lattice organizations. Furthermore, compared to α1B/β3 microtubules, α1B/β2B filaments are more stable to passive disassembly and against depolymerization by MCAK or chTOG, microtubule-associated proteins with distinct mechanisms of action. Mixing tubulin isotypes in different proportions results in microtubules with protofilament numbers and stabilities intermediate to those of isotypically pure filaments. Together, our findings indicate that microtubule protofilament number and stability can be controlled through β-tubulin isotype composition.
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Affiliation(s)
- Shih-Chieh Ti
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Gregory M Alushin
- Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
| | - Tarun M Kapoor
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
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23
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Abstract
Among the different types of cytoskeletal components, microtubules arguably accumulate the greatest diversity of post-translational modifications (PTMs). Acetylation of lysine 40 (K40) of α-tubulin has received particular attention because it is the only tubulin PTM to be found in the lumen of microtubules: most other tubulin PTMs are found at the outer surface of the microtubule. As a consequence, the enzyme catalyzing K40 acetylation needs to penetrate the narrow microtubule lumen to find its substrate. Acetylated microtubules have been considered to be stable, long-lived microtubules; however, until recently, there was little information about whether the longevity of these microtubules is the cause or the consequence of acetylation. Current advances suggest that this PTM helps the microtubule lattice to cope with mechanical stress, thus facilitating microtubule self-repair. These observations now shed new light on the structural integrity of microtubules, as well as on the mechanisms and biological functions of tubulin acetylation. Here, we discuss recent insights into how acetylation is generated in the lumen of microtubules, and how this 'hidden' PTM can control the properties and functions of microtubules.
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Affiliation(s)
- Carsten Janke
- Institut Curie, PSL Research University, CNRS UMR3348, F-91405 Orsay, France; Université Paris Sud, Université Paris-Saclay, CNRS UMR3348, F-91405 Orsay, France.
| | - Guillaume Montagnac
- Inserm U1170, Gustave Roussy Institute, Université Paris-Saclay, F-94800 Villejuif, France.
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Tang NH, Jin Y. Shaping neurodevelopment: distinct contributions of cytoskeletal proteins. Curr Opin Neurobiol 2018; 51:111-118. [PMID: 29574219 PMCID: PMC6066413 DOI: 10.1016/j.conb.2018.02.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 02/20/2018] [Accepted: 02/27/2018] [Indexed: 12/28/2022]
Abstract
Development of a neuron critically depends on the organization of its cytoskeleton. Cytoskeletal components, such as tubulins and actins, have the remarkable ability to organize themselves into filaments and networks to support specialized and compartmentalized functions. Alterations in cytoskeletal proteins have long been associated with a variety of neurodevelopmental disorders. This review focuses on recent findings, primarily from forward genetic screens in Caenorhabditis elegans that illustrate how different tubulin protein isotypes can play distinct roles in neuronal development and function. Additionally, we discuss studies revealing new regulators of the actin cytoskeleton, and highlight recent technological advances in in vivo imaging and functional dissection of the neuronal cytoskeleton.
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Affiliation(s)
- Ngang Heok Tang
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA.
| | - Yishi Jin
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA.
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25
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Miyasaka T, Shinzaki Y, Yoshimura S, Yoshina S, Kage-Nakadai E, Mitani S, Ihara Y. Imbalanced Expression of Tau and Tubulin Induces Neuronal Dysfunction in C. elegans Models of Tauopathy. Front Neurosci 2018; 12:415. [PMID: 29973863 PMCID: PMC6019497 DOI: 10.3389/fnins.2018.00415] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 05/31/2018] [Indexed: 12/12/2022] Open
Abstract
Tauopathy is a type of dementia defined by the accumulation of filamentous tau inclusions in neural cells. Most types of dementia in the elderly, including Alzheimer's disease, are tauopathies. Although it is believed that tau protein abnormalities and/or the loss of its functions results in neurodegeneration and dementia, the mechanism of tauopathy remains obscure. Loss of microtubules and/or tubulin is a known consequence of tau accumulating in neurons in Alzheimer's disease. In other words, there is an excess level of tau relative to tubulin in tauopathy neurons. To test whether this imbalance of tau and tubulin expression results in the neurotoxicity of tau, we developed several transgenic C. elegans lines that express human tau at various levels in pan-neurons. These worms showed behavioral abnormalities in a tau expression-dependent manner. The knockdown of a tubulin-specific chaperon, or a subset of tubulin, led to enhanced tau toxicity even in low-expressing tau-transgenic worms that showed no abnormal behaviors. In addition, the suppression of tau expression in tubulin knockdown worms rescued neuronal dysfunction. Thus, not only the overexpression of tau but also a reduction in tubulin can trigger the neurotoxicity of tau. Tau expressed in worms was also highly phosphorylated and largely bound to tubulin dimers rather than microtubules. Relative amount of tubulin-unbound tau was increased in high-expressing tau-transgenic worms showing tau toxicity. We further demonstrated that tau aggregation was inhibited by co-incubation of purified tubulin in vitro, meaning sufficient amounts of tubulin can protect against the formation of tau inclusions. These results suggest that the expression ratio of tau to tubulin may be a determinant of the tauopathy cascade.
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Affiliation(s)
- Tomohiro Miyasaka
- Department of Neuropathology, Faculty of Life and Medical Sciences, Doshisha University, Kyoto, Japan
| | - Yuki Shinzaki
- Department of Neuropathology, Faculty of Life and Medical Sciences, Doshisha University, Kyoto, Japan
| | - Satomi Yoshimura
- Department of Neuropathology, Faculty of Life and Medical Sciences, Doshisha University, Kyoto, Japan
| | - Sawako Yoshina
- Department of Physiology, School of Medicine, Tokyo Women’s Medical University, Tokyo, Japan
| | - Eriko Kage-Nakadai
- Department of Physiology, School of Medicine, Tokyo Women’s Medical University, Tokyo, Japan
- Graduate School of Human Life Science, Osaka City University, Osaka, Japan
| | - Shohei Mitani
- Department of Physiology, School of Medicine, Tokyo Women’s Medical University, Tokyo, Japan
| | - Yasuo Ihara
- Department of Neuropathology, Faculty of Life and Medical Sciences, Doshisha University, Kyoto, Japan
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26
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Chaaban S, Brouhard GJ. A microtubule bestiary: structural diversity in tubulin polymers. Mol Biol Cell 2018; 28:2924-2931. [PMID: 29084910 PMCID: PMC5662251 DOI: 10.1091/mbc.e16-05-0271] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 08/30/2017] [Accepted: 09/06/2017] [Indexed: 11/11/2022] Open
Abstract
Microtubules are long, slender polymers of αβ-tubulin found in all eukaryotic cells. Tubulins associate longitudinally to form protofilaments, and adjacent protofilaments associate laterally to form the microtubule. In the textbook view, microtubules are 1) composed of 13 protofilaments, 2) arranged in a radial array by the centrosome, and 3) built into the 9+2 axoneme. Although these canonical structures predominate in eukaryotes, microtubules with divergent protofilament numbers and higher-order microtubule assemblies have been discovered throughout the last century. Here we survey these noncanonical structures, from the 4-protofilament microtubules of Prosthecobacter to the 40-protofilament accessory microtubules of mantidfly sperm. We review the variety of protofilament numbers observed in different species, in different cells within the same species, and in different stages within the same cell. We describe the determinants of protofilament number, namely nucleation factors, tubulin isoforms, and posttranslational modifications. Finally, we speculate on the functional significance of these diverse polymers. Equipped with novel tubulin-purification tools, the field is now prepared to tackle the long-standing question of the evolutionary basis of microtubule structure.
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Affiliation(s)
- Sami Chaaban
- Department of Biology, McGill University, Montreal, QC H3A 1B1, Canada
| | - Gary J Brouhard
- Department of Biology, McGill University, Montreal, QC H3A 1B1, Canada
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27
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Pir GJ, Choudhary B, Mandelkow E. Caenorhabditis elegans models of tauopathy. FASEB J 2017; 31:5137-5148. [PMID: 29191965 DOI: 10.1096/fj.201701007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 09/20/2017] [Indexed: 12/14/2022]
Abstract
One of the hallmarks of the tauopathies, which include the neurodegenerative disorders, such as Alzheimer disease (AD), corticobasal degeneration, frontotemporal dementia, and progressive supranuclear palsy (PSP), is the abnormal accumulation of post-translationally modified, insoluble tau. The result is a loss of neurons, decreased mental function, and complete dependence of patients on others. Aggregation of tau, which under physiologic conditions is a highly soluble protein, is thought to be central to the pathogenesis of these diseases. Indeed one of the strongest lines of evidence is the MAPT gene polymorphisms that lead to the familial forms of tauopathy. Extensive research in animal models over the years has contributed some of the most important findings regarding the pathogenesis of these diseases. Despite this, the precise molecular mechanisms that lead to abnormal tau folding, accumulation, and spreading remain unknown. Owing to the fact that most of the biochemical pathways are conserved, Caenorhabditis elegans provides an alternative approach to identify cellular mechanisms and druggable genes that operate in such disorders. Many human genes implicated in neurodegenerative diseases have counterparts in C. elegans, making it an excellent model in which to study their pathogenesis. In this article, we review some of the important findings gained from C. elegans tauopathy models.-Pir, G. J., Choudhary, B., Mandelkow, E. Caenorhabditiselegans models of tauopathy.
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Affiliation(s)
- Ghulam Jeelani Pir
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany; .,Max-Planck-Institute for Metabolism Research-Cologne, Hamburg, Germany
| | - Bikash Choudhary
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.,Max-Planck-Institute for Metabolism Research-Cologne, Hamburg, Germany
| | - Eckhard Mandelkow
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.,Max-Planck-Institute for Metabolism Research-Cologne, Hamburg, Germany.,Caesar Research Center, Bonn, Germany
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28
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Wloga D, Joachimiak E, Fabczak H. Tubulin Post-Translational Modifications and Microtubule Dynamics. Int J Mol Sci 2017; 18:ijms18102207. [PMID: 29065455 PMCID: PMC5666887 DOI: 10.3390/ijms18102207] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 10/12/2017] [Accepted: 10/19/2017] [Indexed: 11/24/2022] Open
Abstract
Microtubules are hollow tube-like polymeric structures composed of α,β-tubulin heterodimers. They play an important role in numerous cellular processes, including intracellular transport, cell motility and segregation of the chromosomes during cell division. Moreover, microtubule doublets or triplets form a scaffold of a cilium, centriole and basal body, respectively. To perform such diverse functions microtubules have to differ in their properties. Post-translational modifications are one of the factors that affect the properties of the tubulin polymer. Here we focus on the direct and indirect effects of post-translational modifications of tubulin on microtubule dynamics.
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Affiliation(s)
- Dorota Wloga
- Laboratory of Cytoskeleton and Cilia Biology, Department of Cell Biology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Str., 02-093 Warsaw, Poland.
| | - Ewa Joachimiak
- Laboratory of Cytoskeleton and Cilia Biology, Department of Cell Biology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Str., 02-093 Warsaw, Poland.
| | - Hanna Fabczak
- Laboratory of Cytoskeleton and Cilia Biology, Department of Cell Biology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Str., 02-093 Warsaw, Poland.
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29
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Noma K, Goncharov A, Ellisman MH, Jin Y. Microtubule-dependent ribosome localization in C. elegans neurons. eLife 2017; 6:26376. [PMID: 28767038 PMCID: PMC5577916 DOI: 10.7554/elife.26376] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 08/01/2017] [Indexed: 01/23/2023] Open
Abstract
Subcellular localization of ribosomes defines the location and capacity for protein synthesis. Methods for in vivo visualizing ribosomes in multicellular organisms are desirable in mechanistic investigations of the cell biology of ribosome dynamics. Here, we developed an approach using split GFP for tissue-specific visualization of ribosomes in Caenorhabditis elegans. Labeled ribosomes are detected as fluorescent puncta in the axons and synaptic terminals of specific neuron types, correlating with ribosome distribution at the ultrastructural level. We found that axonal ribosomes change localization during neuronal development and after axonal injury. By examining mutants affecting axonal trafficking and performing a forward genetic screen, we showed that the microtubule cytoskeleton and the JIP3 protein UNC-16 exert distinct effects on localization of axonal and somatic ribosomes. Our data demonstrate the utility of tissue-specific visualization of ribosomes in vivo, and provide insight into the mechanisms of active regulation of ribosome localization in neurons.
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Affiliation(s)
- Kentaro Noma
- Division of Biological Sciences, Neurobiology Section, University of California, San Diego, San Diego, United States.,Howard Hughes Medical Institute, University of California, San Diego, San Diego, United States
| | - Alexandr Goncharov
- Division of Biological Sciences, Neurobiology Section, University of California, San Diego, San Diego, United States.,Howard Hughes Medical Institute, University of California, San Diego, San Diego, United States
| | - Mark H Ellisman
- National Center for Research in Biological Systems, Department of Neurosciences, School of Medicine, University of California, San Diego, San Diego, United States
| | - Yishi Jin
- Division of Biological Sciences, Neurobiology Section, University of California, San Diego, San Diego, United States.,Howard Hughes Medical Institute, University of California, San Diego, San Diego, United States
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30
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Wloga D, Joachimiak E, Louka P, Gaertig J. Posttranslational Modifications of Tubulin and Cilia. Cold Spring Harb Perspect Biol 2017; 9:cshperspect.a028159. [PMID: 28003186 DOI: 10.1101/cshperspect.a028159] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Tubulin undergoes several highly conserved posttranslational modifications (PTMs) including acetylation, detyrosination, glutamylation, and glycylation. These PTMs accumulate on a subset of microtubules that are long-lived, including those in the basal bodies and axonemes. Tubulin PTMs are distributed nonuniformly. In the outer doublet microtubules of the axoneme, the B-tubules are highly enriched in the detyrosinated, polyglutamylated, and polyglycylated tubulin, whereas the A-tubules contain mostly unmodified tubulin. The nonuniform patterns of tubulin PTMs may functionalize microtubules in a position-dependent manner. Recent studies indicate that tubulin PTMs contribute to the assembly, disassembly, maintenance, and motility of cilia. In particular, tubulin glutamylation has emerged as a key PTM that affects ciliary motility through regulation of axonemal dynein arms and controls the stability and length of the axoneme.
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Affiliation(s)
- Dorota Wloga
- Laboratory of Cytoskeleton and Cilia Biology, Department of Cell Biology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland
| | - Ewa Joachimiak
- Laboratory of Cytoskeleton and Cilia Biology, Department of Cell Biology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland
| | - Panagiota Louka
- Department of Cellular Biology, University of Georgia, Athens, Georgia 30602
| | - Jacek Gaertig
- Department of Cellular Biology, University of Georgia, Athens, Georgia 30602
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31
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Breuss MW, Leca I, Gstrein T, Hansen AH, Keays DA. Tubulins and brain development - The origins of functional specification. Mol Cell Neurosci 2017; 84:58-67. [PMID: 28347630 DOI: 10.1016/j.mcn.2017.03.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2016] [Revised: 02/28/2017] [Accepted: 03/05/2017] [Indexed: 10/19/2022] Open
Abstract
The development of the vertebrate central nervous system is reliant on a complex cascade of biological processes that include mitotic division, relocation of migrating neurons, and the extension of dendritic and axonal processes. Each of these cellular events requires the diverse functional repertoire of the microtubule cytoskeleton for the generation of forces, assembly of macromolecular complexes and transport of molecules and organelles. The tubulins are a multi-gene family that encode for the constituents of microtubules, and have been implicated in a spectrum of neurological disorders. Evidence is building that different tubulins tune the functional properties of the microtubule cytoskeleton dependent on the cell type, developmental profile and subcellular localisation. Here we review of the origins of the functional specification of the tubulin gene family in the developing brain at a transcriptional, translational, and post-transcriptional level. We remind the reader that tubulins are not just loading controls for your average Western blot.
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Affiliation(s)
- Martin W Breuss
- Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Ines Leca
- Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Dr Bohr-Gasse 7, Vienna 1030, Austria
| | - Thomas Gstrein
- Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Dr Bohr-Gasse 7, Vienna 1030, Austria
| | - Andi H Hansen
- Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Dr Bohr-Gasse 7, Vienna 1030, Austria; Institute of Science and Technology Austria, Klosterneuburg 3400, Austria
| | - David A Keays
- Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Dr Bohr-Gasse 7, Vienna 1030, Austria.
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32
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Abstract
Microtubules are key cytoskeletal elements of all eukaryotic cells and are assembled of evolutionarily conserved α-tubulin-β-tubulin heterodimers. Despite their uniform structure, microtubules fulfill a large diversity of functions. A regulatory mechanism to control the specialization of the microtubule cytoskeleton is the 'tubulin code', which is generated by (i) expression of different α- and β-tubulin isotypes, and by (ii) post-translational modifications of tubulin. In this Cell Science at a Glance article and the accompanying poster, we provide a comprehensive overview of the molecular components of the tubulin code, and discuss the mechanisms by which these components contribute to the generation of functionally specialized microtubules.
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Affiliation(s)
- Sudarshan Gadadhar
- Institut Curie, PSL Research University, CNRS UMR3348, Orsay F-91405, France.,Université Paris Sud, Université Paris-Saclay, CNRS UMR3348, Orsay F-91405, France
| | - Satish Bodakuntla
- Institut Curie, PSL Research University, CNRS UMR3348, Orsay F-91405, France.,Université Paris Sud, Université Paris-Saclay, CNRS UMR3348, Orsay F-91405, France
| | - Kathiresan Natarajan
- Institut Curie, PSL Research University, CNRS UMR3348, Orsay F-91405, France.,Université Paris Sud, Université Paris-Saclay, CNRS UMR3348, Orsay F-91405, France
| | - Carsten Janke
- Institut Curie, PSL Research University, CNRS UMR3348, Orsay F-91405, France .,Université Paris Sud, Université Paris-Saclay, CNRS UMR3348, Orsay F-91405, France
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33
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Honda Y, Tsuchiya K, Sumiyoshi E, Haruta N, Sugimoto A. Tubulin isotype substitution revealed that isotype combination modulates microtubule dynamics in C. elegans embryos. J Cell Sci 2017; 130:1652-1661. [PMID: 28302908 DOI: 10.1242/jcs.200923] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 03/13/2017] [Indexed: 12/14/2022] Open
Abstract
Microtubules (MTs) are polymers composed of α- and β-tubulin heterodimers that are generally encoded by genes at multiple loci. Despite implications of distinct properties depending on the isotype, how these heterodimers contribute to the diverse MT dynamics in vivo remains unclear. Here, by using genome editing and depletion of tubulin isotypes following RNAi, we demonstrate that four tubulin isotypes (hereafter referred to as α1, α2, β1 and β2) cooperatively confer distinct MT properties in Caenorhabditis elegans early embryos. GFP insertion into each isotype locus reveals their distinct expression levels and MT incorporation rates. Substitution of isotype coding regions demonstrates that, under the same isotype concentration, MTs composed of β1 have higher switching frequency between growth and shrinkage compared with MTs composed of β2. Lower concentration of β-tubulins results in slower growth rates, and the two α-tubulins distinctively affect growth rates of MTs composed of β1. Alteration of ratio and concentration of isotypes distinctively modulates both growth rate and switching frequency, and affects the amplitude of mitotic spindle oscillation. Collectively, our findings demonstrate that MT dynamics are modulated by the combination (ratio and concentration) of tubulin isotypes with distinct properties, which contributes to create diverse MT behaviors in vivo.
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Affiliation(s)
- Yu Honda
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Kenta Tsuchiya
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Eisuke Sumiyoshi
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Nami Haruta
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Asako Sugimoto
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
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34
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Krieg M, Stühmer J, Cueva JG, Fetter R, Spilker K, Cremers D, Shen K, Dunn AR, Goodman MB. Genetic defects in β-spectrin and tau sensitize C. elegans axons to movement-induced damage via torque-tension coupling. eLife 2017; 6. [PMID: 28098556 PMCID: PMC5298879 DOI: 10.7554/elife.20172] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 01/17/2017] [Indexed: 12/24/2022] Open
Abstract
Our bodies are in constant motion and so are the neurons that invade each tissue. Motion-induced neuron deformation and damage are associated with several neurodegenerative conditions. Here, we investigated the question of how the neuronal cytoskeleton protects axons and dendrites from mechanical stress, exploiting mutations in UNC-70 β-spectrin, PTL-1 tau/MAP2-like and MEC-7 β-tubulin proteins in Caenorhabditis elegans. We found that mechanical stress induces supercoils and plectonemes in the sensory axons of spectrin and tau double mutants. Biophysical measurements, super-resolution, and electron microscopy, as well as numerical simulations of neurons as discrete, elastic rods provide evidence that a balance of torque, tension, and elasticity stabilizes neurons against mechanical deformation. We conclude that the spectrin and microtubule cytoskeletons work in combination to protect axons and dendrites from mechanical stress and propose that defects in β-spectrin and tau may sensitize neurons to damage. DOI:http://dx.doi.org/10.7554/eLife.20172.001
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Affiliation(s)
- Michael Krieg
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, United States.,Department of Chemical Engineering, Stanford University, Stanford, United States
| | - Jan Stühmer
- Department of Informatics, Technical University of Munich, , Germany
| | - Juan G Cueva
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, United States
| | - Richard Fetter
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, United States
| | - Kerri Spilker
- Department of Biology, Stanford University, Stanford, United States
| | - Daniel Cremers
- Department of Informatics, Technical University of Munich, , Germany
| | - Kang Shen
- Department of Biology, Stanford University, Stanford, United States
| | - Alexander R Dunn
- Department of Chemical Engineering, Stanford University, Stanford, United States
| | - Miriam B Goodman
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, United States
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35
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Morley SJ, Qi Y, Iovino L, Andolfi L, Guo D, Kalebic N, Castaldi L, Tischer C, Portulano C, Bolasco G, Shirlekar K, Fusco CM, Asaro A, Fermani F, Sundukova M, Matti U, Reymond L, De Ninno A, Businaro L, Johnsson K, Lazzarino M, Ries J, Schwab Y, Hu J, Heppenstall PA. Acetylated tubulin is essential for touch sensation in mice. eLife 2016; 5. [PMID: 27976998 PMCID: PMC5158137 DOI: 10.7554/elife.20813] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2016] [Accepted: 11/29/2016] [Indexed: 01/11/2023] Open
Abstract
At its most fundamental level, touch sensation requires the translation of mechanical energy into mechanosensitive ion channel opening, thereby generating electro-chemical signals. Our understanding of this process, especially how the cytoskeleton influences it, remains unknown. Here we demonstrate that mice lacking the α-tubulin acetyltransferase Atat1 in sensory neurons display profound deficits in their ability to detect mechanical stimuli. We show that all cutaneous afferent subtypes, including nociceptors have strongly reduced mechanosensitivity upon Atat1 deletion, and that consequently, mice are largely insensitive to mechanical touch and pain. We establish that this broad loss of mechanosensitivity is dependent upon the acetyltransferase activity of Atat1, which when absent leads to a decrease in cellular elasticity. By mimicking α-tubulin acetylation genetically, we show both cellular rigidity and mechanosensitivity can be restored in Atat1 deficient sensory neurons. Hence, our results indicate that by influencing cellular stiffness, α-tubulin acetylation sets the force required for touch. DOI:http://dx.doi.org/10.7554/eLife.20813.001
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Affiliation(s)
- Shane J Morley
- EMBL Mouse Biology Unit, Monterotondo, Italy.,Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany
| | - Yanmei Qi
- Centre for Integrative Neuroscience, Tuebingen, Germany
| | - Loredana Iovino
- EMBL Mouse Biology Unit, Monterotondo, Italy.,Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany
| | | | - Da Guo
- Centre for Integrative Neuroscience, Tuebingen, Germany
| | - Nereo Kalebic
- EMBL Mouse Biology Unit, Monterotondo, Italy.,Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | | | | | | | | | | | | | | | | | | | - Ulf Matti
- European Molecular Biology Laboratory, Heidelberg, Germany
| | - Luc Reymond
- Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland
| | | | | | - Kai Johnsson
- Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland
| | | | - Jonas Ries
- European Molecular Biology Laboratory, Heidelberg, Germany
| | - Yannick Schwab
- European Molecular Biology Laboratory, Heidelberg, Germany
| | - Jing Hu
- Centre for Integrative Neuroscience, Tuebingen, Germany
| | - Paul A Heppenstall
- EMBL Mouse Biology Unit, Monterotondo, Italy.,Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany
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36
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Lockhead D, Schwarz EM, O'Hagan R, Bellotti S, Krieg M, Barr MM, Dunn AR, Sternberg PW, Goodman MB. The tubulin repertoire of C. elegans sensory neurons and its context-dependent role in process outgrowth. Mol Biol Cell 2016; 27:mbc.E16-06-0473. [PMID: 27654945 PMCID: PMC5170555 DOI: 10.1091/mbc.e16-06-0473] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 09/12/2016] [Accepted: 09/15/2016] [Indexed: 12/21/2022] Open
Abstract
Microtubules contribute to many cellular processes, including transport, signaling, and chromosome separation during cell division (Kapitein and Hoogenraad, 2015). They are comprised of αβ-tubulin heterodimers arranged into linear protofilaments and assembled into tubes. Eukaryotes express multiple tubulin isoforms (Gogonea et al., 1999), and there has been a longstanding debate as to whether the isoforms are redundant or perform specialized roles as part of a tubulin code (Fulton and Simpson, 1976). Here, we use the well-characterized touch receptor neurons (TRNs) of Caenorhabditis elegans to investigate this question, through genetic dissection of process outgrowth both in vivo and in vitro With single-cell RNA-seq, we compare transcription profiles for TRNs with those of two other sensory neurons, and present evidence that each sensory neuron expresses a distinct palette of tubulin genes. In the TRNs, we analyze process outgrowth and show that four tubulins (tba-1, tba-2, tbb-1, and tbb-2) function partially or fully redundantly, while two others (mec-7 and mec-12) perform specialized, context-dependent roles. Our findings support a model in which sensory neurons express overlapping subsets of tubulin genes whose functional redundancy varies between cell types and in vivo and in vitro contexts.
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Affiliation(s)
- Dean Lockhead
- *Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
| | - Erich M Schwarz
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
| | - Robert O'Hagan
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, NJ 08854
| | - Sebastian Bellotti
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, NJ 08854
| | - Michael Krieg
- *Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
| | - Maureen M Barr
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, NJ 08854
| | - Alexander R Dunn
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305 Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
| | - Paul W Sternberg
- Howard Hughes Medical Institute and Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Miriam B Goodman
- *Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
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37
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The growing landscape of tubulin acetylation: lysine 40 and many more. Biochem J 2016; 473:1859-68. [DOI: 10.1042/bcj20160172] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 03/29/2016] [Indexed: 11/17/2022]
Abstract
Tubulin heterodimers are the building block of microtubules, which are major elements of the cytoskeleton. Several types of post-translational modifications are found on tubulin subunits as well as on the microtubule polymer to regulate the multiple roles of microtubules. Acetylation of lysine 40 (K40) of the α-tubulin subunit is one of these post-translational modifications which has been extensively studied. We summarize the current knowledge about the structural aspects of K40 acetylation, the functional consequences, the enzymes involved and their regulation. Most importantly, we discuss the potential importance of the recently discovered additional acetylation acceptor lysines in tubulin subunits and highlight the urgent need to study tubulin acetylation in a more integrated perspective.
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38
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Miyasaka T, Xie C, Yoshimura S, Shinzaki Y, Yoshina S, Kage-Nakadai E, Mitani S, Ihara Y. Curcumin improves tau-induced neuronal dysfunction of nematodes. Neurobiol Aging 2015; 39:69-81. [PMID: 26923403 DOI: 10.1016/j.neurobiolaging.2015.11.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 11/09/2015] [Accepted: 11/11/2015] [Indexed: 12/12/2022]
Abstract
Tau is a key protein in the pathogenesis of various neurodegenerative diseases, which are categorized as tauopathies. Because the extent of tau pathologies is closely linked to that of neuronal loss and the clinical symptoms in Alzheimer's disease, anti-tau therapeutics, if any, could be beneficial to a broad spectrum of tauopathies. To learn more about tauopathy, we developed a novel transgenic nematode (Caenorhabditis elegans) model that expresses either wild-type or R406W tau in all the neurons. The wild-type tau-expressing worms exhibited uncoordinated movement (Unc) and neuritic abnormalities. Tau accumulated in abnormal neurites that lost microtubules. Similar abnormalities were found in the worms that expressed low levels of R406W-tau but were not in those expressing comparative levels of wild-type tau. Biochemical studies revealed that tau is aberrantly phosphorylated but forms no detergent-insoluble aggregates. Drug screening performed in these worms identified curcumin, a major phytochemical compound in turmeric, as a compound that reduces not only Unc but also the neuritic abnormalities in both wild-type and R406W tau-expressing worms. Our observations suggest that microtubule stabilization mediates the antitoxicity effect of curcumin. Curcumin is also effective in the worms expressing tau fragment, although it does not prevent the formation of tau-fragment dimers. These data indicate that curcumin improves the tau-induced neuronal dysfunction that is independent of insoluble aggregates of tau.
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Affiliation(s)
- Tomohiro Miyasaka
- Faculty of Medical and Life Sciences, Department of Neuropathology, Doshisha University, Kyotanabe-shi, Kyoto, Japan.
| | - Ce Xie
- Faculty of Medical and Life Sciences, Department of Neuropathology, Doshisha University, Kyotanabe-shi, Kyoto, Japan
| | - Satomi Yoshimura
- Faculty of Medical and Life Sciences, Department of Neuropathology, Doshisha University, Kyotanabe-shi, Kyoto, Japan
| | - Yuki Shinzaki
- Faculty of Medical and Life Sciences, Department of Neuropathology, Doshisha University, Kyotanabe-shi, Kyoto, Japan
| | - Sawako Yoshina
- Department of Physiology, Tokyo Women's Medical University School of Medicine, Shinjuku-ku, Tokyo, Japan
| | - Eriko Kage-Nakadai
- Department of Physiology, Tokyo Women's Medical University School of Medicine, Shinjuku-ku, Tokyo, Japan; Advanced Research Institute for Natural Science and Technology, Osaka City University, Sumiyoshi-ku, Osaka, Japan
| | - Shohei Mitani
- Department of Physiology, Tokyo Women's Medical University School of Medicine, Shinjuku-ku, Tokyo, Japan
| | - Yasuo Ihara
- Faculty of Medical and Life Sciences, Department of Neuropathology, Doshisha University, Kyotanabe-shi, Kyoto, Japan; Laboratory for Cognition and Aging, Graduate School of Brain Sciences, Doshisha University, Kizugawa-shi, Kyoto, Japan
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Penazzi L, Bakota L, Brandt R. Microtubule Dynamics in Neuronal Development, Plasticity, and Neurodegeneration. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 321:89-169. [PMID: 26811287 DOI: 10.1016/bs.ircmb.2015.09.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Neurons are the basic information-processing units of the nervous system. In fulfilling their task, they establish a structural polarity with an axon that can be over a meter long and dendrites with a complex arbor, which can harbor ten-thousands of spines. Microtubules and their associated proteins play important roles during the development of neuronal morphology, the plasticity of neurons, and neurodegenerative processes. They are dynamic structures, which can quickly adapt to changes in the environment and establish a structural scaffold with high local variations in composition and stability. This review presents a comprehensive overview about the role of microtubules and their dynamic behavior during the formation and maturation of processes and spines in the healthy brain, during aging and under neurodegenerative conditions. The review ends with a discussion of microtubule-targeted therapies as a perspective for the supportive treatment of neurodegenerative disorders.
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Affiliation(s)
- Lorène Penazzi
- Department of Neurobiology, University of Osnabrück, Osnabrück, Germany
| | - Lidia Bakota
- Department of Neurobiology, University of Osnabrück, Osnabrück, Germany
| | - Roland Brandt
- Department of Neurobiology, University of Osnabrück, Osnabrück, Germany
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Li L, Yang XJ. Tubulin acetylation: responsible enzymes, biological functions and human diseases. Cell Mol Life Sci 2015; 72:4237-55. [PMID: 26227334 PMCID: PMC11113413 DOI: 10.1007/s00018-015-2000-5] [Citation(s) in RCA: 133] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 07/22/2015] [Accepted: 07/24/2015] [Indexed: 12/28/2022]
Abstract
Microtubules have important functions ranging from maintenance of cell morphology to subcellular transport, cellular signaling, cell migration, and formation of cell polarity. At the organismal level, microtubules are crucial for various biological processes, such as viral entry, inflammation, immunity, learning and memory in mammals. Microtubules are subject to various covalent modifications. One such modification is tubulin acetylation, which is associated with stable microtubules and conserved from protists to humans. In the past three decades, this reversible modification has been studied extensively. In mammals, its level is mainly governed by opposing actions of α-tubulin acetyltransferase 1 (ATAT1) and histone deacetylase 6 (HDAC6). Knockout studies of the mouse enzymes have yielded new insights into biological functions of tubulin acetylation. Abnormal levels of this modification are linked to neurological disorders, cancer, heart diseases and other pathological conditions, thereby yielding important therapeutic implications. This review summarizes related studies and concludes that tubulin acetylation is important for regulating microtubule architecture and maintaining microtubule integrity. Together with detyrosination, glutamylation and other modifications, tubulin acetylation may form a unique 'language' to regulate microtubule structure and function.
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Affiliation(s)
- Lin Li
- Rosalind and Morris Goodman Cancer Research Center, Montreal, QC, H3A 1A3, Canada
- Department of Medicine, Montreal, QC, H3A 1A3, Canada
| | - Xiang-Jiao Yang
- Rosalind and Morris Goodman Cancer Research Center, Montreal, QC, H3A 1A3, Canada.
- Department of Medicine, Montreal, QC, H3A 1A3, Canada.
- Department of Biochemistry, McGill University, Montreal, QC, H3A 1A3, Canada.
- McGill University Health Center, Montreal, QC, H3A 1A3, Canada.
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41
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Dubey J, Ratnakaran N, Koushika SP. Neurodegeneration and microtubule dynamics: death by a thousand cuts. Front Cell Neurosci 2015; 9:343. [PMID: 26441521 PMCID: PMC4563776 DOI: 10.3389/fncel.2015.00343] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2015] [Accepted: 08/18/2015] [Indexed: 12/11/2022] Open
Abstract
Microtubules form important cytoskeletal structures that play a role in establishing and maintaining neuronal polarity, regulating neuronal morphology, transporting cargo, and scaffolding signaling molecules to form signaling hubs. Within a neuronal cell, microtubules are found to have variable lengths and can be both stable and dynamic. Microtubule associated proteins, post-translational modifications of tubulin subunits, microtubule severing enzymes, and signaling molecules are all known to influence both stable and dynamic pools of microtubules. Microtubule dynamics, the process of interconversion between stable and dynamic pools, and the proportions of these two pools have the potential to influence a wide variety of cellular processes. Reduced microtubule stability has been observed in several neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), Amyotrophic Lateral Sclerosis (ALS), and tauopathies like Progressive Supranuclear Palsy. Hyperstable microtubules, as seen in Hereditary Spastic Paraplegia (HSP), also lead to neurodegeneration. Therefore, the ratio of stable and dynamic microtubules is likely to be important for neuronal function and perturbation in microtubule dynamics might contribute to disease progression.
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Affiliation(s)
- Jyoti Dubey
- Department of Biological Sciences, Tata Institute of Fundamental Research Mumbai, India ; InStem Bangalore, India
| | - Neena Ratnakaran
- Department of Biological Sciences, Tata Institute of Fundamental Research Mumbai, India
| | - Sandhya P Koushika
- Department of Biological Sciences, Tata Institute of Fundamental Research Mumbai, India
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Breuss M, Morandell J, Nimpf S, Gstrein T, Lauwers M, Hochstoeger T, Braun A, Chan K, Sánchez Guajardo ER, Zhang L, Suplata M, Heinze KG, Elsayad K, Keays DA. The Expression of Tubb2b Undergoes a Developmental Transition in Murine Cortical Neurons. J Comp Neurol 2015; 523:2161-86. [PMID: 26105993 DOI: 10.1002/cne.23836] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 06/17/2015] [Accepted: 06/18/2015] [Indexed: 01/20/2023]
Abstract
The development of the mammalian brain requires the generation, migration, and differentiation of neurons, cellular processes that are dependent on a dynamic microtubule cytoskeleton. Mutations in tubulin genes, which encode for the structural subunits of microtubules, cause detrimental neurological disorders known as the tubulinopathies. The disease spectra associated with different tubulin genes are overlapping but distinct, an observation believed to reflect functional specification of this multigene family. Perturbation of the β-tubulin TUBB2B is known to cause polymicrogyria, pachygyria, microcephaly, and axon guidance defects. Here we provide a detailed analysis of the expression pattern of its murine homolog Tubb2b. The generation and characterization of BAC-transgenic eGFP reporter mouse lines has revealed that it is highly expressed in progenitors and postmitotic neurons during cortical development. This contrasts with the 8-week-old cortex, in which Tubb2b expression is restricted to macroglia, and expression is almost completely absent in mature neurons. This developmental transition in neurons is mirrored in the adult hippocampus and the cerebellum but is not a universal feature of Tubb2b; its expression persists in a population of postmitotic neurons in the 8-week-old retina. We propose that the dynamic spatial and temporal expression of Tubb2b reflects specific functional requirements of the microtubule cytoskeleton.
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Affiliation(s)
- Martin Breuss
- IMP-Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Vienna, 1030, Austria
| | - Jasmin Morandell
- IMP-Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Vienna, 1030, Austria
| | - Simon Nimpf
- IMP-Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Vienna, 1030, Austria
| | - Thomas Gstrein
- IMP-Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Vienna, 1030, Austria
| | - Mattias Lauwers
- IMP-Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Vienna, 1030, Austria
| | - Tobias Hochstoeger
- IMP-Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Vienna, 1030, Austria
| | - Andreas Braun
- IMP-Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Vienna, 1030, Austria.,Centre for Genomic Regulation (CRG), 08003, Barcelona, Spain
| | - Kelvin Chan
- Medical Scientist Training Program, Stony Brook University Medical Center, Stony Brook, New York, 11794
| | | | - Lijuan Zhang
- Advanced Microscopy, Campus Science Support Facilities (CSF), Vienna, 1030, Austria
| | - Marek Suplata
- Rudolf Virchow Center, DFG-Research Center for Experimental Biomedicine of the University of Würzburg, Würzburg, 97080, Germany
| | - Katrin G Heinze
- Rudolf Virchow Center, DFG-Research Center for Experimental Biomedicine of the University of Würzburg, Würzburg, 97080, Germany
| | - Kareem Elsayad
- Advanced Microscopy, Campus Science Support Facilities (CSF), Vienna, 1030, Austria
| | - David A Keays
- IMP-Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Vienna, 1030, Austria
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Renauld J, Johnen N, Thelen N, Cloes M, Thiry M. Spatio-temporal dynamics of β-tubulin isotypes during the development of the sensory auditory organ in rat. Histochem Cell Biol 2015. [DOI: 10.1007/s00418-015-1350-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Identification of nonviable genes affecting touch sensitivity in Caenorhabditis elegans using neuronally enhanced feeding RNA interference. G3-GENES GENOMES GENETICS 2015; 5:467-75. [PMID: 25575561 PMCID: PMC4349099 DOI: 10.1534/g3.114.015776] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Caenorhabditis elegans senses gentle touch along the body via six touch receptor neurons. Although genetic screens and microarray analyses have identified several genes needed for touch sensitivity, these methods miss pleiotropic genes that are essential for the viability, movement, or fertility of the animals. We used neuronally enhanced feeding RNA interference to screen genes that cause lethality or paralysis when mutated, and we identified 61 such genes affecting touch sensitivity, including five positive controls. We confirmed 18 genes by using available alleles, and further studied one of them, tag-170, now renamed txdc-9. txdc-9 preferentially affects anterior touch response but is needed for tubulin acetylation and microtubule formation in both the anterior and posterior touch receptor neurons. Our results indicate that neuronally enhanced feeding RNA interference screens complement traditional mutageneses by identifying additional nonviable genes needed for specific neuronal functions.
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Warburton-Pitt SRF, Silva M, Nguyen KCQ, Hall DH, Barr MM. The nphp-2 and arl-13 genetic modules interact to regulate ciliogenesis and ciliary microtubule patterning in C. elegans. PLoS Genet 2014; 10:e1004866. [PMID: 25501555 PMCID: PMC4263411 DOI: 10.1371/journal.pgen.1004866] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 10/31/2014] [Indexed: 12/14/2022] Open
Abstract
Cilia are microtubule-based cellular organelles that mediate signal transduction. Cilia are organized into several structurally and functionally distinct compartments: the basal body, the transition zone (TZ), and the cilia shaft. In vertebrates, the cystoprotein Inversin localizes to a portion of the cilia shaft adjacent to the TZ, a region termed the "Inversin compartment" (InvC). The mechanisms that establish and maintain the InvC are unknown. In the roundworm C. elegans, the cilia shafts of amphid channel and phasmid sensory cilia are subdivided into two regions defined by different microtubule ultrastructure: a proximal doublet-based region adjacent to the TZ, and a distal singlet-based region. It has been suggested that C. elegans cilia also possess an InvC, similarly to mammalian primary cilia. Here we explored the biogenesis, structure, and composition of the C. elegans ciliary doublet region and InvC. We show that the InvC is conserved and distinct from the doublet region. nphp-2 (the C. elegans Inversin homolog) and the doublet region genes arl-13, klp-11, and unc-119 are redundantly required for ciliogenesis. InvC and doublet region genes can be sorted into two modules-nphp-2+klp-11 and arl-13+unc-119-which are both antagonized by the hdac-6 deacetylase. The genes of this network modulate the sizes of the NPHP-2 InvC and ARL-13 doublet region. Glutamylation, a tubulin post-translational modification, is not required for ciliary targeting of InvC and doublet region components; rather, glutamylation is modulated by nphp-2, arl-13, and unc-119. The ciliary targeting and restricted localization of NPHP-2, ARL-13, and UNC-119 does not require TZ-, doublet region, and InvC-associated genes. NPHP-2 does require its calcium binding EF hand domain for targeting to the InvC. We conclude that the C. elegans InvC is distinct from the doublet region, and that components in these two regions interact to regulate ciliogenesis via cilia placement, ciliary microtubule ultrastructure, and protein localization.
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Affiliation(s)
- Simon R. F. Warburton-Pitt
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey, United States of America
| | - Malan Silva
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey, United States of America
| | - Ken C. Q. Nguyen
- Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx, New York, New York, United States of America
| | - David H. Hall
- Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx, New York, New York, United States of America
| | - Maureen M. Barr
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey, United States of America
- * E-mail:
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Hsu JM, Chen CH, Chen YC, McDonald KL, Gurling M, Lee A, Garriga G, Pan CL. Genetic analysis of a novel tubulin mutation that redirects synaptic vesicle targeting and causes neurite degeneration in C. elegans. PLoS Genet 2014; 10:e1004715. [PMID: 25392990 PMCID: PMC4230729 DOI: 10.1371/journal.pgen.1004715] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 08/27/2014] [Indexed: 11/24/2022] Open
Abstract
Neuronal cargos are differentially targeted to either axons or dendrites, and this polarized cargo targeting critically depends on the interaction between microtubules and molecular motors. From a forward mutagenesis screen, we identified a gain-of-function mutation in the C. elegans α-tubulin gene mec-12 that triggered synaptic vesicle mistargeting, neurite swelling and neurodegeneration in the touch receptor neurons. This missense mutation replaced an absolutely conserved glycine in the H12 helix with glutamic acid, resulting in increased negative charges at the C-terminus of α-tubulin. Synaptic vesicle mistargeting in the mutant neurons was suppressed by reducing dynein function, suggesting that aberrantly high dynein activity mistargeted synaptic vesicles. We demonstrated that dynein showed preference towards binding mutant microtubules over wild-type in microtubule sedimentation assay. By contrast, neurite swelling and neurodegeneration were independent of dynein and could be ameliorated by genetic paralysis of the animal. This suggests that mutant microtubules render the neurons susceptible to recurrent mechanical stress induced by muscle activity, which is consistent with the observation that microtubule network was disorganized under electron microscopy. Our work provides insights into how microtubule-dynein interaction instructs synaptic vesicle targeting and the importance of microtubule in the maintenance of neuronal structures against constant mechanical stress. Axons and dendrites are two classes of neuronal process that differ in their functions and molecular compositions. Proteins important for synaptic functions are mostly synthesized in the cell body and sorted differentially into the axon or dendrites. Microtubules in the axon and dendrite maintain their structural integrity and regulate polarized protein transport into these compartments. We identified a novel α-tubulin mutation in C. elegans that caused mistargeting of synaptic vesicles and induced progressive neurite swelling, which resulted in late-onset neurodegeneration. We showed that this tubulin mutation weakened microtubule network and abnormally increased microtubule affinity for dynein, a motor protein responsible for cargo sorting to the dendrite. This enhanced microtubule-dynein affinity is due to augmented negative charge at the carboxyl terminus of α-tubulin. Neurite swelling and neurodegeneration could be ameliorated by reduced physical activity, suggesting that recurrent mechanical strain from muscle contraction jeopardized neurite integrity in the long run. Mutations in α- and β-tubulins are found in human neurological diseases; our findings therefore contribute to understanding the pathogenic mechanism of human neurological diseases associated with tubulin mutations.
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Affiliation(s)
- Jiun-Min Hsu
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chun-Hao Chen
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yen-Chih Chen
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Kent L. McDonald
- Electron Microscope Laboratory, University of California, Berkeley, Berkeley, California, United States of America
| | - Mark Gurling
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, California, United States of America
| | - Albert Lee
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
| | - Gian Garriga
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, California, United States of America
| | - Chun-Liang Pan
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
- * E-mail:
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RHGF-1/PDZ-RhoGEF and retrograde DLK-1 signaling drive neuronal remodeling on microtubule disassembly. Proc Natl Acad Sci U S A 2014; 111:16568-73. [PMID: 25359212 DOI: 10.1073/pnas.1410263111] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Neurons remodel their connectivity in response to various insults, including microtubule disruption. How neurons sense microtubule disassembly and mount remodeling responses by altering genetic programs in the soma are not well defined. Here we show that in response to microtubule disassembly, the Caenorhabditis elegans PLM neuron remodels by retracting its synaptic branch and overextending the primary neurite. This remodeling required RHGF-1, a PDZ-Rho guanine nucleotide exchange factor (PDZ-RhoGEF) that was associated with and inhibited by microtubules. Independent of the myosin light chain activation, RHGF-1 acted through Rho-dependent kinase LET-502/ROCK and activated a conserved, retrograde DLK-1 MAPK (DLK-1/dual leucine zipper kinase) pathway, which triggered synaptic branch retraction and overgrowth of the PLM neurite in a dose-dependent manner. Our data represent a neuronal remodeling paradigm during development that reshapes the neural circuit by the coordinated removal of the dysfunctional synaptic branch compartment and compensatory extension of the primary neurite.
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Richardson CE, Spilker KA, Cueva JG, Perrino J, Goodman MB, Shen K. PTRN-1, a microtubule minus end-binding CAMSAP homolog, promotes microtubule function in Caenorhabditis elegans neurons. eLife 2014; 3:e01498. [PMID: 24569477 PMCID: PMC3932522 DOI: 10.7554/elife.01498] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
In neuronal processes, microtubules (MTs) provide structural support and serve as tracks for molecular motors. While it is known that neuronal MTs are more stable than MTs in non-neuronal cells, the molecular mechanisms underlying this stability are not fully understood. In this study, we used live fluorescence microscopy to show that the C. elegans CAMSAP protein PTRN-1 localizes to puncta along neuronal processes, stabilizes MT foci, and promotes MT polymerization in neurites. Electron microscopy revealed that ptrn-1 null mutants have fewer MTs and abnormal MT organization in the PLM neuron. Animals grown with a MT depolymerizing drug caused synthetic defects in neurite branching in the absence of ptrn-1 function, indicating that PTRN-1 promotes MT stability. Further, ptrn-1 null mutants exhibited aberrant neurite morphology and synaptic vesicle localization that is partially dependent on dlk-1. Our results suggest that PTRN-1 represents an important mechanism for promoting MT stability in neurons. DOI:http://dx.doi.org/10.7554/eLife.01498.001 Microtubules are tiny tubular structures made from many copies of proteins called tubulins. Microtubules have a number of important roles inside cells: they are part of the cytoskeleton that provides structural support for the cell; they help to pull chromosomes apart during cell division; and they guide the trafficking of proteins and molecules around inside the cell. Most microtubules are relatively unstable, undergoing continuous dis-assembly and re-assembly in response to the needs of the cell. The microtubules in the branches of nerve cells are an exception, remaining relatively stable over time. Now Richardson et al. and, independently, Marcette et al., have shown that a protein called PTRN-1 has an important role in stabilizing the microtubules in the nerve cells of nematode worms. By tagging the PTRN-1 proteins with fluorescent molecules, Richardson et al. were able to show that these proteins were present along the length of the microtubules within the nerve cells. Further work showed that the PTRN-1 proteins stabilize the microtubule filaments within the branches of these nerve cells and also hold them in position. Richardson et al. also found that worms that had been genetically modified to prevent them from producing PTRN-1 failed to traffic certain molecules to the synapses between nerve cells. Moreover, these mutants also had problems with the branching of their nerve cells; however, these defects were relatively mild, which suggests that other molecules and proteins act in parallel with PTRN-1 to stabilize microtubules in nerve cells. Further work should be able to identify these factors and elucidate how they work together to stabilize the microtubules in nerve cells. DOI:http://dx.doi.org/10.7554/eLife.01498.002
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Breuss M, Keays DA. Microtubules and neurodevelopmental disease: the movers and the makers. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 800:75-96. [PMID: 24243101 DOI: 10.1007/978-94-007-7687-6_5] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The development of the mammalian cortex requires the generation, migration and differentiation of neurons. Each of these cellular events requires a dynamic microtubule cytoskeleton. Microtubules are required for interkinetic nuclear migration, the separation of chromatids in mitosis, nuclear translocation during migration and the outgrowth of neurites. Their importance is underlined by the finding that mutations in a host of microtubule associated proteins cause detrimental neurological disorders. More recently, the structural subunits of microtubules, the tubulin proteins, have been implicated in a spectrum of human diseases collectively known as the tubulinopathies. This chapter reviews the discovery of microtubules, the role they play in neurodevelopment, and catalogues the tubulin isoforms associated with neurodevelopmental disease. Our focus is on the molecular and cellular mechanisms that underlie the pathology of tubulin-associated diseases. Finally, we reflect on whether different tubulin genes have distinct intrinsic functions.
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Affiliation(s)
- Martin Breuss
- Institute of Molecular Pathology, Dr. Bohr-Gasse 7, 1030, Vienna, Austria
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50
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Tatsumi H, Furuichi T, Nakano M, Toyota M, Hayakawa K, Sokabe M, Iida H. Mechanosensitive channels are activated by stress in the actin stress fibres, and could be involved in gravity sensing in plants. PLANT BIOLOGY (STUTTGART, GERMANY) 2014; 16 Suppl 1:18-22. [PMID: 24016318 DOI: 10.1111/plb.12095] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Accepted: 07/18/2013] [Indexed: 05/14/2023]
Abstract
Mechanosensitive (MS) channels are expressed in a variety of cells. The molecular and biophysical mechanism involved in the regulation of MS channel activities is a central interest in basic biology. MS channels are thought to play crucial roles in gravity sensing in plant cells. To date, two mechanisms have been proposed for MS channel activation. One is that tension development in the lipid bilayer directly activates MS channels. The second mechanism proposes that the cytoskeleton is involved in the channel activation, because MS channel activities are modulated by pharmacological treatments that affect the cytoskeleton. We tested whether tension in the cytoskeleton activates MS channels. Mammalian endothelial cells were microinjected with phalloidin-conjugated beads, which bound to stress fibres, and a traction force to the actin cytoskeleton was applied by dragging the beads with optical tweezers. MS channels were activated when the force was applied, demonstrating that a sub-pN force to the actin filaments activates a single MS channel. Plants may use a similar molecular mechanism in gravity sensing, since the cytoplasmic Ca(2+) concentration increase induced by changes in the gravity vector was attenuated by potential MS channel inhibitors, and by actin-disrupting drugs. These results support the idea that the tension increase in actin filaments by gravity-dependent sedimentation of amyloplasts activates MS Ca(2+) -permeable channels, which can be the molecular mechanism of a Ca(2+) concentration increase through gravistimulation. We review recent progress in the study of tension sensing by actin filaments and MS channels using advanced biophysical methods, and discuss their possible roles in gravisensing.
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Affiliation(s)
- H Tatsumi
- Nagoya University Graduate School of Medicine, Nagoya, Japan
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