1
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Fu G, Augspurger K, Sakizadeh J, Reck J, Bower R, Tritschler D, Gui L, Nicastro D, Porter ME. The MBO2/FAP58 heterodimer stabilizes assembly of inner arm dynein b and reveals axoneme asymmetries involved in ciliary waveform. Mol Biol Cell 2024; 35:ar72. [PMID: 38568782 PMCID: PMC11151096 DOI: 10.1091/mbc.e23-11-0439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 03/05/2024] [Accepted: 03/26/2024] [Indexed: 04/05/2024] Open
Abstract
Cilia generate three-dimensional waveforms required for cell motility and transport of fluid, mucus, and particles over the cell surface. This movement is driven by multiple dynein motors attached to nine outer doublet microtubules that form the axoneme. The outer and inner arm dyneins are organized into 96-nm repeats tandemly arrayed along the length of the doublets. Motility is regulated in part by projections from the two central pair microtubules that contact radial spokes located near the base of the inner dynein arms in each repeat. Although much is known about the structures and protein complexes within the axoneme, many questions remain about the regulatory mechanisms that allow the cilia to modify their waveforms in response to internal or external stimuli. Here, we used Chlamydomonas mbo (move backwards only) mutants with altered waveforms to identify at least two conserved proteins, MBO2/CCDC146 and FAP58/CCDC147, that form part of a L-shaped structure that varies between doublet microtubules. Comparative proteomics identified additional missing proteins that are altered in other motility mutants, revealing overlapping protein defects. Cryo-electron tomography and epitope tagging revealed that the L-shaped, MBO2/FAP58 structure interconnects inner dynein arms with multiple regulatory complexes, consistent with its function in modifying the ciliary waveform.
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Affiliation(s)
- Gang Fu
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Katherine Augspurger
- Department of Genetics, Cell Biology, and Genetics, University of Minnesota, Minneapolis, MN 55455
| | - Jason Sakizadeh
- Department of Genetics, Cell Biology, and Genetics, University of Minnesota, Minneapolis, MN 55455
| | - Jaimee Reck
- Department of Genetics, Cell Biology, and Genetics, University of Minnesota, Minneapolis, MN 55455
| | - Raqual Bower
- Department of Genetics, Cell Biology, and Genetics, University of Minnesota, Minneapolis, MN 55455
| | - Douglas Tritschler
- Department of Genetics, Cell Biology, and Genetics, University of Minnesota, Minneapolis, MN 55455
| | - Long Gui
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Daniela Nicastro
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Mary E. Porter
- Department of Genetics, Cell Biology, and Genetics, University of Minnesota, Minneapolis, MN 55455
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2
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Weijman JF, Vuolo L, Shak C, Pugnetti A, Mukhopadhyay AG, Hodgson LR, Heesom KJ, Roberts AJ, Stephens DJ. Roles for CEP170 in cilia function and dynein-2 assembly. J Cell Sci 2024; 137:jcs261816. [PMID: 38533689 PMCID: PMC11112123 DOI: 10.1242/jcs.261816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 03/19/2024] [Indexed: 03/28/2024] Open
Abstract
Primary cilia are essential eukaryotic organelles required for signalling and secretion. Dynein-2 is a microtubule-motor protein complex and is required for ciliogenesis via its role in facilitating retrograde intraflagellar transport (IFT) from the cilia tip to the cell body. Dynein-2 must be assembled and loaded onto IFT trains for entry into cilia for this process to occur, but how dynein-2 is assembled and how it is recycled back into a cilium remain poorly understood. Here, we identify centrosomal protein of 170 kDa (CEP170) as a dynein-2-interacting protein in mammalian cells. We show that loss of CEP170 perturbs intraflagellar transport and hedgehog signalling, and alters the stability of dynein-2 holoenzyme complex. Together, our data indicate a role for CEP170 in supporting cilia function and dynein-2 assembly.
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Affiliation(s)
- Johannes F. Weijman
- Cell Biology Laboratories, School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK
| | - Laura Vuolo
- Cell Biology Laboratories, School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK
| | - Caroline Shak
- Cell Biology Laboratories, School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK
| | - Anna Pugnetti
- Cell Biology Laboratories, School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK
| | | | - Lorna R. Hodgson
- Wolfson Bioimaging Facility, Faculty of Life Sciences, University Walk, University of Bristol, Bristol BS8 1TD, UK
| | - Kate J. Heesom
- Proteomics Facility, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK
| | - Anthony J. Roberts
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
| | - David J. Stephens
- Cell Biology Laboratories, School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK
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3
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Hwang J, Yanagisawa H, Davis KC, Hunter EL, Fox LA, Jimenez AR, Goodwin RE, Gordon SA, Stuart CDE, Bower R, Porter ME, Dutcher SK, Sale WS, Lechtreck KF, Alford LM. Assembly of FAP93 at the proximal axoneme in Chlamydomonas cilia. Cytoskeleton (Hoboken) 2024. [PMID: 38224153 DOI: 10.1002/cm.21818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 11/27/2023] [Accepted: 11/29/2023] [Indexed: 01/16/2024]
Abstract
To identify proteins specific to the proximal ciliary axoneme, we used iTRAQ to compare short (~2 μm) and full-length (~11 μm) axonemes of Chlamydomonas. Known compoents of the proximal axoneme such as minor dynein heavy chains and LF5 kinase as well as the ciliary tip proteins FAP256 (CEP104) and EB1 were enriched in short axonemes whereas proteins present along the length of the axoneme were of similar abundance in both samples. The iTRAQ analysis revealed that FAP93, a protein of unknown function, and protein phosphatase 2A (PP2A) are enriched in the short axonemes. Consistently, immunoblots show enrichment of FAP93 and PP2A in short axonemes and immunofluorescence confirms the localization of FAP93 and enrichment of PP2A at the proximal axoneme. Ciliary regeneration reveals that FAP93 assembles continuously but more slowly than other axonemal structures and terminates at 1.03 μm in steady-state axonemes. The length of FAP93 assembly correlates with ciliary length, demonstrating ciliary length-dependent assembly of FAP93. Dikaryon rescue experiments show that FAP93 can assemble independently of IFT transport. In addition, FRAP analysis of GFP-tagged FAP93 demonstrates that FAP93 is stably anchored in axoneme. FAP93 may function as a scaffold for assembly of other specific proteins at the proximal axoneme.
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Affiliation(s)
- Juyeon Hwang
- Department of Cell Biology, Emory University, Atlanta, Georgia, USA
| | | | - Keira C Davis
- Department of Cell Biology, Emory University, Atlanta, Georgia, USA
- College of Arts & Sciences, Clayton State University, Morrow, Georgia, USA
| | - Emily L Hunter
- Department of Cell Biology, Emory University, Atlanta, Georgia, USA
- Science Communication Group, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Laura A Fox
- Department of Cell Biology, Emory University, Atlanta, Georgia, USA
| | - Ariana R Jimenez
- Division of Natural Sciences, Oglethorpe University, Atlanta, Georgia, USA
| | - Reagan E Goodwin
- Division of Natural Sciences, Oglethorpe University, Atlanta, Georgia, USA
| | - Sarah A Gordon
- Division of Natural Sciences, Oglethorpe University, Atlanta, Georgia, USA
| | | | - Raqual Bower
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota, USA
| | - Mary E Porter
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota, USA
| | - Susan K Dutcher
- Department of Genetics, Washington University St. Louis, St. Louis, Missouri, USA
| | - Winfield S Sale
- Department of Cell Biology, Emory University, Atlanta, Georgia, USA
| | - Karl F Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Lea M Alford
- Division of Natural Sciences, Oglethorpe University, Atlanta, Georgia, USA
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4
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Saravanan S, Trischler D, Bower R, Porter M, Lechtreck K. In vivo imaging reveals independent intraflagellar transport of the nexin-dynein regulatory complex subunits DRC2 and DRC4. Mol Biol Cell 2023; 34:br2. [PMID: 36598807 PMCID: PMC9930527 DOI: 10.1091/mbc.e22-11-0524] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 12/19/2022] [Accepted: 12/23/2022] [Indexed: 01/05/2023] Open
Abstract
Many axonemal proteins enter cilia and flagella on intraflagellar transport (IFT) trains, which move bidirectionally along the axonemal microtubules. Certain axonemal substructures including the radial spokes and outer dynein arms are preassembled in the cell body and transported as multisubunit complexes into flagella by IFT. Here, we used in vivo imaging to analyze the transport and assembly of DRC2 and DRC4, two core subunits of the nexin-dynein regulatory complex (N-DRC). Tagged DRC2 moved by IFT in mutants lacking DRC4 and vice versa, showing that they do not depend on each other for IFT. Simultaneous imaging of tagged DRC2 and DRC4, expressed from transgenes that rescue a corresponding double mutant, mostly showed transport on separate IFT trains, but occasional cotransports were also observed. The results demonstrate that DRC2 and DRC4 are transported largely independently of each other into flagella. These studies suggest that the N-DRC assembles onto the axoneme by the stepwise addition of subunits.
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Affiliation(s)
- Sahana Saravanan
- Department of Cellular Biology, University of Georgia, Athens, GA 30602
| | - Douglas Trischler
- Department of Genetics, Cell Biology, and Development, University of Minnesota Medical School, Minneapolis, MN 55455
| | - Raqual Bower
- Department of Genetics, Cell Biology, and Development, University of Minnesota Medical School, Minneapolis, MN 55455
| | - Mary Porter
- Department of Genetics, Cell Biology, and Development, University of Minnesota Medical School, Minneapolis, MN 55455
| | - Karl Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, GA 30602
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5
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van den Hoek H, Klena N, Jordan MA, Alvarez Viar G, Righetto RD, Schaffer M, Erdmann PS, Wan W, Geimer S, Plitzko JM, Baumeister W, Pigino G, Hamel V, Guichard P, Engel BD. In situ architecture of the ciliary base reveals the stepwise assembly of intraflagellar transport trains. Science 2022; 377:543-548. [PMID: 35901159 DOI: 10.1126/science.abm6704] [Citation(s) in RCA: 53] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The cilium is an antenna-like organelle that performs numerous cellular functions, including motility, sensing, and signaling. The base of the cilium contains a selective barrier that regulates the entry of large intraflagellar transport (IFT) trains, which carry cargo proteins required for ciliary assembly and maintenance. However, the native architecture of the ciliary base and the process of IFT train assembly remain unresolved. In this work, we used in situ cryo-electron tomography to reveal native structures of the transition zone region and assembling IFT trains at the ciliary base in Chlamydomonas. We combined this direct cellular visualization with ultrastructure expansion microscopy to describe the front-to-back stepwise assembly of IFT trains: IFT-B forms the backbone, onto which bind IFT-A, dynein-1b, and finally kinesin-2 before entry into the cilium.
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Affiliation(s)
- Hugo van den Hoek
- Biozentrum, University of Basel, 4056 Basel, Switzerland.,Helmholtz Pioneer Campus, Helmholtz Munich, 85764 Neuherberg, Germany.,Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Nikolai Klena
- Department of Molecular and Cellular Biology, Section of Biology, University of Geneva, 1211 Geneva, Switzerland.,Human Technopole, 20157 Milan, Italy
| | - Mareike A Jordan
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Gonzalo Alvarez Viar
- Human Technopole, 20157 Milan, Italy.,Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Ricardo D Righetto
- Biozentrum, University of Basel, 4056 Basel, Switzerland.,Helmholtz Pioneer Campus, Helmholtz Munich, 85764 Neuherberg, Germany
| | - Miroslava Schaffer
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | | | - William Wan
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Stefan Geimer
- Cell Biology and Electron Microscopy, University of Bayreuth, 95447 Bayreuth, Germany
| | - Jürgen M Plitzko
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Wolfgang Baumeister
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Gaia Pigino
- Human Technopole, 20157 Milan, Italy.,Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Virginie Hamel
- Department of Molecular and Cellular Biology, Section of Biology, University of Geneva, 1211 Geneva, Switzerland
| | - Paul Guichard
- Department of Molecular and Cellular Biology, Section of Biology, University of Geneva, 1211 Geneva, Switzerland
| | - Benjamin D Engel
- Biozentrum, University of Basel, 4056 Basel, Switzerland.,Helmholtz Pioneer Campus, Helmholtz Munich, 85764 Neuherberg, Germany
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6
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Qiu H, Tsurumi Y, Katoh Y, Nakayama K. Combinations of deletion and missense variations of the dynein-2 DYNC2LI1 subunit found in skeletal ciliopathies cause ciliary defects. Sci Rep 2022; 12:31. [PMID: 34997029 PMCID: PMC8742128 DOI: 10.1038/s41598-021-03950-0] [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: 07/07/2021] [Accepted: 12/13/2021] [Indexed: 12/11/2022] Open
Abstract
Cilia play crucial roles in sensing and transducing extracellular signals. Bidirectional protein trafficking within cilia is mediated by the intraflagellar transport (IFT) machinery containing IFT-A and IFT-B complexes, with the aid of kinesin-2 and dynein-2 motors. The dynein-2 complex drives retrograde trafficking of the IFT machinery after its transportation to the ciliary tip as an IFT cargo. Mutations in genes encoding the dynein-2-specific subunits (DYNC2H1, WDR60, WDR34, DYNC2LI1, and TCTEX1D2) are known to cause skeletal ciliopathies. We here demonstrate that several pathogenic variants of DYNC2LI1 are compromised regarding their ability to interact with DYNC2H1 and WDR60. When expressed in DYNC2LI1-knockout cells, deletion variants of DYNC2LI1 were unable to rescue the ciliary defects of these cells, whereas missense variants, as well as wild-type DYNC2LI1, restored the normal phenotype. DYNC2LI1-knockout cells coexpressing one pathogenic deletion variant together with wild-type DYNC2LI1 demonstrated a normal phenotype. In striking contrast, DYNC2LI1-knockout cells coexpressing the deletion variant in combination with a missense variant, which mimics the situation of cells of compound heterozygous ciliopathy individuals, demonstrated ciliary defects. Thus, DYNC2LI1 deletion variants found in individuals with skeletal ciliopathies cause ciliary defects when combined with a missense variant, which expressed on its own does not cause substantial defects.
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Affiliation(s)
- Hantian Qiu
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Yuta Tsurumi
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan.,General Research Institute, Hoyu Co., Ltd., Nagakute, Aichi, 480-1136, Japan
| | - Yohei Katoh
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Kazuhisa Nakayama
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan.
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7
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Lechtreck KF, Liu Y, Dai J, Alkhofash RA, Butler J, Alford L, Yang P. Chlamydomonas ARMC2/PF27 is an obligate cargo adapter for intraflagellar transport of radial spokes. eLife 2022; 11:74993. [PMID: 34982025 PMCID: PMC8789290 DOI: 10.7554/elife.74993] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 01/03/2022] [Indexed: 12/19/2022] Open
Abstract
Intraflagellar transport (IFT) carries proteins into flagella but how IFT trains interact with the large number of diverse proteins required to assemble flagella remains largely unknown. Here, we show that IFT of radial spokes in Chlamydomonas requires ARMC2/PF27, a conserved armadillo repeat protein associated with male infertility and reduced lung function. Chlamydomonas ARMC2 was highly enriched in growing flagella and tagged ARMC2 and the spoke protein RSP3 co-migrated on anterograde trains. In contrast, a cargo and an adapter of inner and outer dynein arms moved independently of ARMC2, indicating that unrelated cargoes distribute stochastically onto the IFT trains. After concomitant unloading at the flagellar tip, RSP3 attached to the axoneme whereas ARMC2 diffused back to the cell body. In armc2/pf27 mutants, IFT of radial spokes was abolished and the presence of radial spokes was limited to the proximal region of flagella. We conclude that ARMC2 is a cargo adapter required for IFT of radial spokes to ensure their assembly along flagella. ARMC2 belongs to a growing class of cargo-specific adapters that enable flagellar transport of preassembled axonemal substructures by IFT.
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Affiliation(s)
- Karl F Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, United States
| | - Yi Liu
- Department of Biological Sciences, Marquette University, Milwaukee, United States
| | - Jin Dai
- Department of Cellular Biology, University of Georgia, Athens, United States
| | - Rama A Alkhofash
- Department of Cellular Biology, University of Georgia, Athens, United States
| | - Jack Butler
- Department of Cellular Biology, University of Georgia, Athens, United States
| | - Lea Alford
- Division of Natural Sciences,, Oglethorpe University, Atlanta, United States
| | - Pinfen Yang
- Department of Biological Sciences, Marquette University, Milwaukee, United States
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8
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De-Castro ARG, Rodrigues DRM, De-Castro MJG, Vieira N, Vieira C, Carvalho AX, Gassmann R, Abreu CMC, Dantas TJ. WDR60-mediated dynein-2 loading into cilia powers retrograde IFT and transition zone crossing. J Cell Biol 2022; 221:212746. [PMID: 34739033 PMCID: PMC8576871 DOI: 10.1083/jcb.202010178] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 09/20/2021] [Accepted: 10/13/2021] [Indexed: 12/30/2022] Open
Abstract
The dynein-2 motor complex drives retrograde intraflagellar transport (IFT), playing a pivotal role in the assembly and functions of cilia. However, the mechanisms that regulate dynein-2 motility remain poorly understood. Here, we identify the Caenorhabditis elegans WDR60 homologue, WDR-60, and dissect the roles of this intermediate chain using genome editing and live imaging of endogenous dynein-2/IFT components. We find that loss of WDR-60 impairs dynein-2 recruitment to cilia and its incorporation onto anterograde IFT trains, reducing retrograde motor availability at the ciliary tip. Consistent with this, we show that fewer dynein-2 motors power WDR-60–deficient retrograde IFT trains, which move at reduced velocities and fail to exit cilia, accumulating on the distal side of the transition zone. Remarkably, disrupting the transition zone’s NPHP module almost fully restores ciliary exit of underpowered retrograde trains in wdr-60 mutants. This work establishes WDR-60 as a major contributor to IFT, and the NPHP module as a roadblock to dynein-2 passage through the transition zone.
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Affiliation(s)
- Ana R G De-Castro
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Diogo R M Rodrigues
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - Maria J G De-Castro
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Neide Vieira
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Cármen Vieira
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Ana X Carvalho
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Reto Gassmann
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Carla M C Abreu
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Tiago J Dantas
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
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9
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Wingfield JL, Mekonnen B, Mengoni I, Liu P, Jordan M, Diener D, Pigino G, Lechtreck K. In vivo imaging shows continued association of several IFT-A, IFT-B and dynein complexes while IFT trains U-turn at the tip. J Cell Sci 2021; 134:271904. [PMID: 34415027 DOI: 10.1242/jcs.259010] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 08/12/2021] [Indexed: 01/05/2023] Open
Abstract
Flagellar assembly depends on intraflagellar transport (IFT), a bidirectional motility of protein carriers, the IFT trains. The trains are periodic assemblies of IFT-A and IFT-B subcomplexes and the motors kinesin-2 and IFT dynein. At the tip, anterograde trains are remodeled for retrograde IFT, a process that in Chlamydomonas involves kinesin-2 release and train fragmentation. However, the degree of train disassembly at the tip remains unknown. Here, we performed two-color imaging of fluorescent protein-tagged IFT components, which indicates that IFT-A and IFT-B proteins from a given anterograde train usually return in the same set of retrograde trains. Similarly, concurrent turnaround was typical for IFT-B proteins and the IFT dynein subunit D1bLIC-GFP but severance was observed as well. Our data support a simple model of IFT turnaround, in which IFT-A, IFT-B and IFT dynein typically remain associated at the tip and segments of the anterograde trains convert directly into retrograde trains. Continuous association of IFT-A, IFT-B and IFT dynein during tip remodeling could balance protein entry and exit, preventing the build-up of IFT material in flagella.
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Affiliation(s)
- Jenna L Wingfield
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Betlehem Mekonnen
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Ilaria Mengoni
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Peiwei Liu
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Mareike Jordan
- Max Planck Institute of Molecular Cell Biology and Genetics, D-01307 Dresden, Germany
| | - Dennis Diener
- Max Planck Institute of Molecular Cell Biology and Genetics, D-01307 Dresden, Germany
| | - Gaia Pigino
- Max Planck Institute of Molecular Cell Biology and Genetics, D-01307 Dresden, Germany.,Human Technopole, Via Cristina Belgioioso 171, 20157 Milan, Italy
| | - Karl Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
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10
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Abstract
The intraflagellar transport (IFT) system is a remarkable molecular machine used by cells to assemble and maintain the cilium, a long organelle extending from eukaryotic cells that gives rise to motility, sensing and signaling. IFT plays a critical role in building the cilium by shuttling structural components and signaling receptors between the ciliary base and tip. To provide effective transport, IFT-A and IFT-B adaptor protein complexes assemble into highly repetitive polymers, called IFT trains, that are powered by the motors kinesin-2 and IFT-dynein to move bidirectionally along the microtubules. This dynamic system must be precisely regulated to shuttle different cargo proteins between the ciliary tip and base. In this Cell Science at a Glance article and the accompanying poster, we discuss the current structural and mechanistic understanding of IFT trains and how they function as macromolecular machines to assemble the structure of the cilium.
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Affiliation(s)
- Mareike A Jordan
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Pfotenhauerstraße 108, 01307 Dresden, Germany
| | - Gaia Pigino
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Pfotenhauerstraße 108, 01307 Dresden, Germany.,Human Technopole, Via Cristina Belgioioso 171, 20157 Milan, Italy
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11
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Fort C, Collingridge P, Brownlee C, Wheeler G. Ca 2+ elevations disrupt interactions between intraflagellar transport and the flagella membrane in Chlamydomonas. J Cell Sci 2021; 134:jcs.253492. [PMID: 33495279 DOI: 10.1242/jcs.253492] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 01/05/2021] [Indexed: 01/29/2023] Open
Abstract
The movement of ciliary membrane proteins is directed by transient interactions with intraflagellar transport (IFT) trains. The green alga Chlamydomonas has adapted this process for gliding motility, using retrograde IFT motors to move adhesive glycoproteins in the flagella membrane. Ca2+ signalling contributes directly to the gliding process, although uncertainty remains over the mechanism through which it acts. Here, we show that flagella Ca2+ elevations initiate the movement of paused retrograde IFT trains, which accumulate at the distal end of adherent flagella, but do not influence other IFT processes. On highly adherent surfaces, flagella exhibit high-frequency Ca2+ elevations that prevent the accumulation of paused retrograde IFT trains. Flagella Ca2+ elevations disrupt the IFT-dependent movement of microspheres along the flagella membrane, suggesting that Ca2+ acts by directly disrupting an interaction between retrograde IFT trains and flagella membrane glycoproteins. By regulating the extent to which glycoproteins on the flagella surface interact with IFT motor proteins on the axoneme, this signalling mechanism allows precise control of traction force and gliding motility in adherent flagella.
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Affiliation(s)
- Cecile Fort
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK
| | - Peter Collingridge
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK
| | - Colin Brownlee
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK.,School of Ocean and Earth Science, University of Southampton, Southampton SO14 3ZH, UK
| | - Glen Wheeler
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK
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12
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Zhu X, Wang J, Li S, Lechtreck K, Pan J. IFT54 directly interacts with kinesin-II and IFT dynein to regulate anterograde intraflagellar transport. EMBO J 2020; 40:e105781. [PMID: 33368450 DOI: 10.15252/embj.2020105781] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 11/30/2020] [Accepted: 12/04/2020] [Indexed: 12/31/2022] Open
Abstract
The intraflagellar transport (IFT) machinery consists of the anterograde motor kinesin-II, the retrograde motor IFT dynein, and the IFT-A and -B complexes. However, the interaction among IFT motors and IFT complexes during IFT remains elusive. Here, we show that the IFT-B protein IFT54 interacts with both kinesin-II and IFT dynein and regulates anterograde IFT. Deletion of residues 342-356 of Chlamydomonas IFT54 resulted in diminished anterograde traffic of IFT and accumulation of IFT motors and complexes in the proximal region of cilia. IFT54 directly interacted with kinesin-II and this interaction was strengthened for the IFT54Δ342-356 mutant in vitro and in vivo. The deletion of residues 261-275 of IFT54 reduced ciliary entry and anterograde traffic of IFT dynein with accumulation of IFT complexes near the ciliary tip. IFT54 directly interacted with IFT dynein subunit D1bLIC, and deletion of residues 261-275 reduced this interaction. The interactions between IFT54 and the IFT motors were also observed in mammalian cells. Our data indicate a central role for IFT54 in binding the IFT motors during anterograde IFT.
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Affiliation(s)
- Xin Zhu
- MOE Key Laboratory of Protein Sciences, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong Province, China
| | - Jieling Wang
- MOE Key Laboratory of Protein Sciences, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Shufen Li
- MOE Key Laboratory of Protein Sciences, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Karl Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, GA, USA
| | - Junmin Pan
- MOE Key Laboratory of Protein Sciences, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong Province, China
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13
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Webb S, Mukhopadhyay AG, Roberts AJ. Intraflagellar transport trains and motors: Insights from structure. Semin Cell Dev Biol 2020; 107:82-90. [PMID: 32684327 PMCID: PMC7561706 DOI: 10.1016/j.semcdb.2020.05.021] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 05/19/2020] [Accepted: 05/26/2020] [Indexed: 11/17/2022]
Abstract
Intraflagellar transport (IFT) sculpts the proteome of cilia and flagella; the antenna-like organelles found on the surface of virtually all human cell types. By delivering proteins to the growing ciliary tip, recycling turnover products, and selectively transporting signalling molecules, IFT has critical roles in cilia biogenesis, quality control, and signal transduction. IFT involves long polymeric arrays, termed IFT trains, which move to and from the ciliary tip under the power of the microtubule-based motor proteins kinesin-II and dynein-2. Recent top-down and bottom-up structural biology approaches are converging on the molecular architecture of the IFT train machinery. Here we review these studies, with a focus on how kinesin-II and dynein-2 assemble, attach to IFT trains, and undergo precise regulation to mediate bidirectional transport.
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Affiliation(s)
- Stephanie Webb
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London, United Kingdom
| | - Aakash G Mukhopadhyay
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London, United Kingdom
| | - Anthony J Roberts
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London, United Kingdom.
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14
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Vuolo L, Stevenson NL, Mukhopadhyay AG, Roberts AJ, Stephens DJ. Cytoplasmic dynein-2 at a glance. J Cell Sci 2020; 133:133/6/jcs240614. [DOI: 10.1242/jcs.240614] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
ABSTRACT
Cytoplasmic dynein-2 is a motor protein complex that drives the movement of cargoes along microtubules within cilia, facilitating the assembly of these organelles on the surface of nearly all mammalian cells. Dynein-2 is crucial for ciliary function, as evidenced by deleterious mutations in patients with skeletal abnormalities. Long-standing questions include how the dynein-2 complex is assembled, regulated, and switched between active and inactive states. A combination of model organisms, in vitro cell biology, live-cell imaging, structural biology and biochemistry has advanced our understanding of the dynein-2 motor. In this Cell Science at a Glance article and the accompanying poster, we discuss the current understanding of dynein-2 and its roles in ciliary assembly and function.
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Affiliation(s)
- Laura Vuolo
- Cell Biology Laboratories, School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK
| | - Nicola L. Stevenson
- Cell Biology Laboratories, School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK
| | - Aakash G. Mukhopadhyay
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, London WC1E 7HX, UK
| | - Anthony J. Roberts
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, London WC1E 7HX, UK
| | - David J. Stephens
- Cell Biology Laboratories, School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK
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15
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Mijalkovic J, van Krugten J, Oswald F, Acar S, Peterman EJG. Single-Molecule Turnarounds of Intraflagellar Transport at the C. elegans Ciliary Tip. Cell Rep 2019; 25:1701-1707.e2. [PMID: 30428341 DOI: 10.1016/j.celrep.2018.10.050] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 04/13/2018] [Accepted: 10/12/2018] [Indexed: 11/17/2022] Open
Abstract
Cilia are microtubule-based sensing hubs that rely on intraflagellar transport (IFT) for their development, maintenance, and function. Kinesin-2 motors transport IFT trains, consisting of IFT proteins and cargo, from ciliary base to tip. There, trains turn around and are transported back by IFT dynein. The mechanism of tip turnaround has remained elusive. Here, we employ single-molecule fluorescence microscopy of IFT components in the tips of phasmid cilia of living C. elegans. Analysis of the trajectories reveals that while motor proteins and IFT-A particle component CHE-11 mostly turn around immediately, the IFT-B particle component OSM-6 pauses for several seconds. Our data indicate that IFT trains disassemble into at least IFT-A, IFT-B, IFT-dynein, and OSM-3 complexes at the tip, where OSM-6 is temporarily retained or undergoes modification, prior to train reassembly and retrograde transport. The single-molecule approach used here is a valuable tool to study how directional switches occur in microtubule-based transport processes.
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Affiliation(s)
- Jona Mijalkovic
- LaserLaB and Department of Physics and Astronomy, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, the Netherlands
| | - Jaap van Krugten
- LaserLaB and Department of Physics and Astronomy, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, the Netherlands
| | - Felix Oswald
- LaserLaB and Department of Physics and Astronomy, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, the Netherlands
| | - Seyda Acar
- LaserLaB and Department of Physics and Astronomy, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, the Netherlands
| | - Erwin J G Peterman
- LaserLaB and Department of Physics and Astronomy, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, the Netherlands.
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16
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Scaffold subunits support associated subunit assembly in the Chlamydomonas ciliary nexin-dynein regulatory complex. Proc Natl Acad Sci U S A 2019; 116:23152-23162. [PMID: 31659045 DOI: 10.1073/pnas.1910960116] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The nexin-dynein regulatory complex (N-DRC) in motile cilia and flagella functions as a linker between neighboring doublet microtubules, acts to stabilize the axonemal core structure, and serves as a central hub for the regulation of ciliary motility. Although the N-DRC has been studied extensively using genetic, biochemical, and structural approaches, the precise arrangement of the 11 (or more) N-DRC subunits remains unknown. Here, using cryo-electron tomography, we have compared the structure of Chlamydomonas wild-type flagella to that of strains with specific DRC subunit deletions or rescued strains with tagged DRC subunits. Our results show that DRC7 is a central linker subunit that helps connect the N-DRC to the outer dynein arms. DRC11 is required for the assembly of DRC8, and DRC8/11 form a subcomplex in the proximal lobe of the linker domain that is required to form stable contacts to the neighboring B-tubule. Gold labeling of tagged subunits determines the precise locations of the previously ambiguous N terminus of DRC4 and C terminus of DRC5. DRC4 is now shown to contribute to the core scaffold of the N-DRC. Our results reveal the overall architecture of N-DRC, with the 3 subunits DRC1/2/4 forming a core complex that serves as the scaffold for the assembly of the "functional subunits," namely DRC3/5-8/11. These findings shed light on N-DRC assembly and its role in regulating flagellar beating.
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17
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Abstract
Cells from all three domains of life on Earth utilize motile macromolecular devices that protrude from the cell surface to generate forces that allow them to swim through fluid media. Research carried out on archaea during the past decade or so has led to the recognition that, despite their common function, the motility devices of the three domains display fundamental differences in their properties and ancestry, reflecting a striking example of convergent evolution. Thus, the flagella of bacteria and the archaella of archaea employ rotary filaments that assemble from distinct subunits that do not share a common ancestor and generate torque using energy derived from distinct fuel sources, namely chemiosmotic ion gradients and FlaI motor-catalyzed ATP hydrolysis, respectively. The cilia of eukaryotes, however, assemble via kinesin-2-driven intraflagellar transport and utilize microtubules and ATP-hydrolyzing dynein motors to beat in a variety of waveforms via a sliding filament mechanism. Here, with reference to current structural and mechanistic information about these organelles, we briefly compare the evolutionary origins, assembly and tactic motility of archaella, flagella and cilia.
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Affiliation(s)
- Shahid Khan
- Molecular Biology Consortium, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
| | - Jonathan M Scholey
- Department of Molecular and Cell Biology, University of California @ Davis, CA 95616, USA.
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18
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Lin J, Le TV, Augspurger K, Tritschler D, Bower R, Fu G, Perrone C, O’Toole ET, Mills KV, Dymek E, Smith E, Nicastro D, Porter ME. FAP57/WDR65 targets assembly of a subset of inner arm dyneins and connects to regulatory hubs in cilia. Mol Biol Cell 2019; 30:2659-2680. [PMID: 31483737 PMCID: PMC6761771 DOI: 10.1091/mbc.e19-07-0367] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 08/22/2019] [Accepted: 08/29/2019] [Indexed: 01/19/2023] Open
Abstract
Ciliary motility depends on both the precise spatial organization of multiple dynein motors within the 96 nm axonemal repeat and the highly coordinated interactions between different dyneins and regulatory complexes located at the base of the radial spokes. Mutations in genes encoding cytoplasmic assembly factors, intraflagellar transport factors, docking proteins, dynein subunits, and associated regulatory proteins can all lead to defects in dynein assembly and ciliary motility. Significant progress has been made in the identification of dynein subunits and extrinsic factors required for preassembly of dynein complexes in the cytoplasm, but less is known about the docking factors that specify the unique binding sites for the different dynein isoforms on the surface of the doublet microtubules. We have used insertional mutagenesis to identify a new locus, IDA8/BOP2, required for targeting the assembly of a subset of inner dynein arms (IDAs) to a specific location in the 96 nm repeat. IDA8 encodes flagellar-associated polypeptide (FAP)57/WDR65, a highly conserved WD repeat, coiled coil domain protein. Using high resolution proteomic and structural approaches, we find that FAP57 forms a discrete complex. Cryo-electron tomography coupled with epitope tagging and gold labeling reveal that FAP57 forms an extended structure that interconnects multiple IDAs and regulatory complexes.
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Affiliation(s)
- Jianfeng Lin
- Departments of Cell Biology and Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Thuc Vy Le
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455
| | - Katherine Augspurger
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455
| | - Douglas Tritschler
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455
| | - Raqual Bower
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455
| | - Gang Fu
- Departments of Cell Biology and Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Catherine Perrone
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455
| | - Eileen T. O’Toole
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309
| | - Kristyn VanderWaal Mills
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455
| | - Erin Dymek
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755
| | - Elizabeth Smith
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755
| | - Daniela Nicastro
- Departments of Cell Biology and Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Mary E. Porter
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455
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19
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Structure of the dynein-2 complex and its assembly with intraflagellar transport trains. Nat Struct Mol Biol 2019; 26:823-829. [PMID: 31451806 PMCID: PMC6774794 DOI: 10.1038/s41594-019-0286-y] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 07/24/2019] [Indexed: 12/12/2022]
Abstract
Dynein-2 assembles with polymeric intraflagellar transport (IFT) trains to form a transport machinery that is crucial for cilia biogenesis and signaling. Here we recombinantly expressed the ~1.4-MDa human dynein-2 complex and solved its cryo-EM structure to near-atomic resolution. The two identical copies of the dynein-2 heavy chain are contorted into different conformations by a WDR60-WDR34 heterodimer and a block of two RB and six LC8 light chains. One heavy chain is steered into a zig-zag conformation, which matches the periodicity of the anterograde IFT-B train. Contacts between adjacent dyneins along the train indicate a cooperative mode of assembly. Removal of the WDR60-WDR34-light chain subcomplex renders dynein-2 monomeric and relieves autoinhibition of its motility. Our results converge on a model in which an unusual stoichiometry of non-motor subunits controls dynein-2 assembly, asymmetry, and activity, giving mechanistic insight into the interaction of dynein-2 with IFT trains and the origin of diverse functions in the dynein family.
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20
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Grotjahn DA, Lander GC. Setting the dynein motor in motion: New insights from electron tomography. J Biol Chem 2019; 294:13202-13217. [PMID: 31285262 DOI: 10.1074/jbc.rev119.003095] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Dyneins are ATP-fueled macromolecular machines that power all minus-end microtubule-based transport processes of molecular cargo within eukaryotic cells and play essential roles in a wide variety of cellular functions. These complex and fascinating motors have been the target of countless structural and biophysical studies. These investigations have elucidated the mechanism of ATP-driven force production and have helped unravel the conformational rearrangements associated with the dynein mechanochemical cycle. However, despite decades of research, it remains unknown how these molecular motions are harnessed to power massive cellular reorganization and what are the regulatory mechanisms that drive these processes. Recent advancements in electron tomography imaging have enabled researchers to visualize dynein motors in their transport environment with unprecedented detail and have led to exciting discoveries regarding dynein motor function and regulation. In this review, we will highlight how these recent structural studies have fundamentally propelled our understanding of the dynein motor and have revealed some unexpected, unifying mechanisms of regulation.
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Affiliation(s)
- Danielle A Grotjahn
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California 92037
| | - Gabriel C Lander
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California 92037.
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21
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Vuolo L, Stevenson NL, Heesom KJ, Stephens DJ. Dynein-2 intermediate chains play crucial but distinct roles in primary cilia formation and function. eLife 2018; 7:39655. [PMID: 30320547 PMCID: PMC6211827 DOI: 10.7554/elife.39655] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 10/14/2018] [Indexed: 12/16/2022] Open
Abstract
The dynein-2 microtubule motor is the retrograde motor for intraflagellar transport. Mutations in dynein-2 components cause skeletal ciliopathies, notably Jeune syndrome. Dynein-2 contains a heterodimer of two non-identical intermediate chains, WDR34 and WDR60. Here, we use knockout cell lines to demonstrate that each intermediate chain has a distinct role in cilium function. Using quantitative proteomics, we show that WDR34 KO cells can assemble a dynein-2 motor complex that binds IFT proteins yet fails to extend an axoneme, indicating complex function is stalled. In contrast, WDR60 KO cells do extend axonemes but show reduced assembly of dynein-2 and binding to IFT proteins. Both proteins are required to maintain a functional transition zone and for efficient bidirectional intraflagellar transport. Our results indicate that the subunit asymmetry within the dynein-2 complex is matched with a functional asymmetry between the dynein-2 intermediate chains. Furthermore, this work reveals that loss of function of dynein-2 leads to defects in transition zone architecture, as well as intraflagellar transport. Almost all cells in the human body are covered in tiny hair-like structures known as primary cilia. These structures act as antennae to receive signals from outside the cell that regulate how the body grows and develops. The cell has to deliver new proteins and other molecules to precise locations within its cilia to ensure that they work properly. Each cilium is separated from the rest of the cell by a selective barrier known as the transition zone, which controls the movement of molecules to and from the rest of the cell. Dynein-2 is a motor protein that moves other proteins and cell materials within cilia. It includes two subunits known as WDR34 and WDR60. The genes that produce these subunits are mutated in Jeune and short rib polydactyly syndromes that primarily affect how the skeleton forms. However, little is known about the roles the individual subunits play within the motor protein. Vuolo et al. used a gene editing technique called CRISPR-Cas9 to remove one or both of the genes encoding the dynein-2 subunits from human cells. The experiments show that the two subunits have very different roles in cilia. WDR34 is required for cells to build a cilium whereas WDR60 is not. Instead, WDR60 is needed to move proteins and other materials within an established cilium. Unexpectedly, the experiments suggest that dynein-2 is also required to maintain the transition zone. This work provides the foundations for future studies on the role of dynein-2 in building and maintaining the structure of cilia. This could ultimately help to develop new treatments to reduce the symptoms of Jeune syndrome and other diseases caused by defects in cilia.
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Affiliation(s)
- Laura Vuolo
- Cell Biology Laboratories, School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Nicola L Stevenson
- Cell Biology Laboratories, School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Kate J Heesom
- Proteomics Facility, Faculty of Biomedical Sciences, University of Bristol, Bristol, United Kingdom
| | - David J Stephens
- Cell Biology Laboratories, School of Biochemistry, University of Bristol, Bristol, United Kingdom
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22
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Jordan MA, Diener DR, Stepanek L, Pigino G. The cryo-EM structure of intraflagellar transport trains reveals how dynein is inactivated to ensure unidirectional anterograde movement in cilia. Nat Cell Biol 2018; 20:1250-1255. [PMID: 30323187 DOI: 10.1038/s41556-018-0213-1] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Accepted: 09/11/2018] [Indexed: 02/03/2023]
Abstract
Movement of cargos along microtubules plays key roles in diverse cellular processes, from signalling to mitosis. In cilia, rapid movement of ciliary components along the microtubules to and from the assembly site is essential for the assembly and disassembly of the structure itself1. This bidirectional transport, known as intraflagellar transport (IFT)2, is driven by the anterograde motor kinesin-23 and the retrograde motor dynein-1b (dynein-2 in mammals)4,5. However, to drive retrograde transport, dynein-1b must first be delivered to the ciliary tip by anterograde IFT6. Although, the presence of opposing motors in bidirectional transport processes often leads to periodic stalling and slowing of cargos7, IFT is highly processive1,2,8. Using cryo-electron tomography, we show that a tug-of-war between kinesin-2 and dynein-1b is prevented by loading dynein-1b onto anterograde IFT trains in an autoinhibited form and by positioning it away from the microtubule track to prevent binding. Once at the ciliary tip, dynein-1b must transition into an active form and engage microtubules to power retrograde trains. These findings provide a striking example of how coordinated structural changes mediate the behaviour of complex cellular machinery.
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Affiliation(s)
- Mareike A Jordan
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Dresden, Germany
| | - Dennis R Diener
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Dresden, Germany
| | - Ludek Stepanek
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Dresden, Germany
| | - Gaia Pigino
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Dresden, Germany.
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23
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Roberts AJ. Emerging mechanisms of dynein transport in the cytoplasm versus the cilium. Biochem Soc Trans 2018; 46:967-982. [PMID: 30065109 PMCID: PMC6103457 DOI: 10.1042/bst20170568] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2018] [Revised: 06/13/2018] [Accepted: 06/18/2018] [Indexed: 02/08/2023]
Abstract
Two classes of dynein power long-distance cargo transport in different cellular contexts. Cytoplasmic dynein-1 is responsible for the majority of transport toward microtubule minus ends in the cell interior. Dynein-2, also known as intraflagellar transport dynein, moves cargoes along the axoneme of eukaryotic cilia and flagella. Both dyneins operate as large ATP-driven motor complexes, whose dysfunction is associated with a group of human disorders. But how similar are their mechanisms of action and regulation? To examine this question, this review focuses on recent advances in dynein-1 and -2 research, and probes to what extent the emerging principles of dynein-1 transport could apply to or differ from those of the less well-understood dynein-2 mechanoenzyme.
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Affiliation(s)
- Anthony J Roberts
- Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London, U.K.
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24
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Chlamydomonas Basal Bodies as Flagella Organizing Centers. Cells 2018; 7:cells7070079. [PMID: 30018231 PMCID: PMC6070942 DOI: 10.3390/cells7070079] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 07/09/2018] [Accepted: 07/10/2018] [Indexed: 11/17/2022] Open
Abstract
During ciliogenesis, centrioles convert to membrane-docked basal bodies, which initiate the formation of cilia/flagella and template the nine doublet microtubules of the flagellar axoneme. The discovery that many human diseases and developmental disorders result from defects in flagella has fueled a strong interest in the analysis of flagellar assembly. Here, we will review the structure, function, and development of basal bodies in the unicellular green alga Chlamydomonas reinhardtii, a widely used model for the analysis of basal bodies and flagella. Intraflagellar transport (IFT), a flagella-specific protein shuttle critical for ciliogenesis, was first described in C. reinhardtii. A focus of this review will be on the role of the basal bodies in organizing the IFT machinery.
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25
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Bower R, Tritschler D, Mills KV, Heuser T, Nicastro D, Porter ME. DRC2/CCDC65 is a central hub for assembly of the nexin-dynein regulatory complex and other regulators of ciliary and flagellar motility. Mol Biol Cell 2017; 29:137-153. [PMID: 29167384 PMCID: PMC5909927 DOI: 10.1091/mbc.e17-08-0510] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 11/13/2017] [Accepted: 11/15/2017] [Indexed: 02/01/2023] Open
Abstract
DRC2 is a subunit of the nexin–dynein regulatory complex linked to primary ciliary dyskinesia. Little is known about the impact of drc2 mutations on axoneme composition and structure. We used proteomic and structural approaches to reveal that DRC2 coassembles with DRC1 to attach the N-DRC to the A-tubule and mediate interactions with other regulatory structures. The nexin–dynein regulatory complex (N-DRC) plays a central role in the regulation of ciliary and flagellar motility. In most species, the N-DRC contains at least 11 subunits, but the specific function of each subunit is unknown. Mutations in three subunits (DRC1, DRC2/CCDC65, DRC4/GAS8) have been linked to defects in ciliary motility in humans and lead to a ciliopathy known as primary ciliary dyskinesia (PCD). Here we characterize the biochemical, structural, and motility phenotypes of two mutations in the DRC2 gene of Chlamydomonas. Using high-resolution proteomic and structural approaches, we find that the C-terminal region of DRC2 is critical for the coassembly of DRC2 and DRC1 to form the base plate of N-DRC and its attachment to the outer doublet microtubule. Loss of DRC2 in drc2 mutants disrupts the assembly of several other N-DRC subunits and also destabilizes the assembly of several closely associated structures such as the inner dynein arms, the radial spokes, and the calmodulin- and spoke-associated complex. Our study provides new insights into the range of ciliary defects that can lead to PCD.
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Affiliation(s)
- Raqual Bower
- Department of Genetics, Cell Biology, and Development, University of Minnesota Medical School, Minneapolis, MN 55455
| | - Douglas Tritschler
- Department of Genetics, Cell Biology, and Development, University of Minnesota Medical School, Minneapolis, MN 55455
| | - Kristyn VanderWaal Mills
- Department of Genetics, Cell Biology, and Development, University of Minnesota Medical School, Minneapolis, MN 55455
| | - Thomas Heuser
- Biology Department and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454.,Vienna Biocenter Core Facilities, 1030 Vienna, Austria
| | - Daniela Nicastro
- Biology Department and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454.,Departments of Cell Biology and Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Mary E Porter
- Department of Genetics, Cell Biology, and Development, University of Minnesota Medical School, Minneapolis, MN 55455
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26
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Chien A, Shih SM, Bower R, Tritschler D, Porter ME, Yildiz A. Dynamics of the IFT machinery at the ciliary tip. eLife 2017; 6:28606. [PMID: 28930071 PMCID: PMC5662288 DOI: 10.7554/elife.28606] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 09/12/2017] [Indexed: 12/15/2022] Open
Abstract
Intraflagellar transport (IFT) is essential for the elongation and maintenance of eukaryotic cilia and flagella. Due to the traffic jam of multiple trains at the ciliary tip, how IFT trains are remodeled in these turnaround zones cannot be determined by conventional imaging. Using PhotoGate, we visualized the full range of movement of single IFT trains and motors in Chlamydomonas flagella. Anterograde trains split apart and IFT complexes mix with each other at the tip to assemble retrograde trains. Dynein-1b is carried to the tip by kinesin-II as inactive cargo on anterograde trains. Unlike dynein-1b, kinesin-II detaches from IFT trains at the tip and diffuses in flagella. As the flagellum grows longer, diffusion delays return of kinesin-II to the basal body, depleting kinesin-II available for anterograde transport. Our results suggest that dissociation of kinesin-II from IFT trains serves as a negative feedback mechanism that facilitates flagellar length control in Chlamydomonas.
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Affiliation(s)
- Alexander Chien
- Biophysics Graduate Group, University of California, Berkeley, Berkeley, United States
| | - Sheng Min Shih
- Physics Department, University of California, Berkeley, Berkeley, United States
| | - Raqual Bower
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, United States
| | - Douglas Tritschler
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, United States
| | - Mary E Porter
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, United States
| | - Ahmet Yildiz
- Biophysics Graduate Group, University of California, Berkeley, Berkeley, United States.,Physics Department, University of California, Berkeley, Berkeley, United States.,Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
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27
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Prevo B, Scholey JM, Peterman EJG. Intraflagellar transport: mechanisms of motor action, cooperation, and cargo delivery. FEBS J 2017; 284:2905-2931. [PMID: 28342295 PMCID: PMC5603355 DOI: 10.1111/febs.14068] [Citation(s) in RCA: 131] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 02/20/2017] [Accepted: 03/23/2017] [Indexed: 02/06/2023]
Abstract
Intraflagellar transport (IFT) is a form of motor-dependent cargo transport that is essential for the assembly, maintenance, and length control of cilia, which play critical roles in motility, sensory reception, and signal transduction in virtually all eukaryotic cells. During IFT, anterograde kinesin-2 and retrograde IFT dynein motors drive the bidirectional transport of IFT trains that deliver cargo, for example, axoneme precursors such as tubulins as well as molecules of the signal transduction machinery, to their site of assembly within the cilium. Following its discovery in Chlamydomonas, IFT has emerged as a powerful model system for studying general principles of motor-dependent cargo transport and we now appreciate the diversity that exists in the mechanism of IFT within cilia of different cell types. The absence of heterotrimeric kinesin-2 function, for example, causes a complete loss of both IFT and cilia in Chlamydomonas, but following its loss in Caenorhabditis elegans, where its primary function is loading the IFT machinery into cilia, homodimeric kinesin-2-driven IFT persists and assembles a full-length cilium. Generally, heterotrimeric kinesin-2 and IFT dynein motors are thought to play widespread roles as core IFT motors, whereas homodimeric kinesin-2 motors are accessory motors that mediate different functions in a broad range of cilia, in some cases contributing to axoneme assembly or the delivery of signaling molecules but in many other cases their ciliary functions, if any, remain unknown. In this review, we focus on mechanisms of motor action, motor cooperation, and motor-dependent cargo delivery during IFT.
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Affiliation(s)
- Bram Prevo
- Department of Cellular & Molecular Medicine, University of California San Diego, CA, USA
- Ludwig Institute for Cancer Research, San Diego, CA, USA
| | - Jonathan M Scholey
- Department of Molecular & Cell Biology, University of California Davis, CA, USA
| | - Erwin J G Peterman
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit, Amsterdam, The Netherlands
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28
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Wang L, Gu L, Meng D, Wu Q, Deng H, Pan J. Comparative Proteomics Reveals Timely Transport into Cilia of Regulators or Effectors as a Mechanism Underlying Ciliary Disassembly. J Proteome Res 2017; 16:2410-2418. [DOI: 10.1021/acs.jproteome.6b01048] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Limei Wang
- MOE
Key Laboratory of Protein Sciences, Tsinghua-Peking Center for Life
Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Lixiao Gu
- MOE
Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Dan Meng
- Tianjin
Key Laboratory of Food and Biotechnology, School of Biotechnology
and Food Science, Tianjin University of Commerce, Tianjin 300134, China
| | - Qiong Wu
- MOE
Key Laboratory of Protein Sciences, Tsinghua-Peking Center for Life
Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Haiteng Deng
- MOE
Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Junmin Pan
- MOE
Key Laboratory of Protein Sciences, Tsinghua-Peking Center for Life
Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
- Laboratory
for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong Province 266237, China
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29
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Wingfield JL, Mengoni I, Bomberger H, Jiang YY, Walsh JD, Brown JM, Picariello T, Cochran DA, Zhu B, Pan J, Eggenschwiler J, Gaertig J, Witman GB, Kner P, Lechtreck K. IFT trains in different stages of assembly queue at the ciliary base for consecutive release into the cilium. eLife 2017; 6. [PMID: 28562242 PMCID: PMC5451262 DOI: 10.7554/elife.26609] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 05/16/2017] [Indexed: 12/13/2022] Open
Abstract
Intraflagellar transport (IFT) trains, multimegadalton assemblies of IFT proteins and motors, traffic proteins in cilia. To study how trains assemble, we employed fluorescence protein-tagged IFT proteins in Chlamydomonas reinhardtii. IFT-A and motor proteins are recruited from the cell body to the basal body pool, assembled into trains, move through the cilium, and disperse back into the cell body. In contrast to this ‘open’ system, IFT-B proteins from retrograde trains reenter the pool and a portion is reused directly in anterograde trains indicating a ‘semi-open’ system. Similar IFT systems were also observed in Tetrahymena thermophila and IMCD3 cells. FRAP analysis indicated that IFT proteins and motors of a given train are sequentially recruited to the basal bodies. IFT dynein and tubulin cargoes are loaded briefly before the trains depart. We conclude that the pool contains IFT trains in multiple stages of assembly queuing for successive release into the cilium upon completion. DOI:http://dx.doi.org/10.7554/eLife.26609.001
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Affiliation(s)
- Jenna L Wingfield
- Department of Cellular Biology, University of Georgia, Athens, United States
| | - Ilaria Mengoni
- Department of Cellular Biology, University of Georgia, Athens, United States
| | - Heather Bomberger
- Department of Cellular Biology, University of Georgia, Athens, United States.,College of Engineering, University of Georgia, Athens, United States
| | - Yu-Yang Jiang
- Department of Cellular Biology, University of Georgia, Athens, United States
| | - Jonathon D Walsh
- Department of Genetics, University of Georgia, Athens, United States
| | - Jason M Brown
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, United States.,Department of Biology, Salem State University, Salem, United States
| | - Tyler Picariello
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, United States
| | - Deborah A Cochran
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, United States
| | - Bing Zhu
- MOE Key Laboratory of Protein Sciences, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Junmin Pan
- MOE Key Laboratory of Protein Sciences, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | | | - Jacek Gaertig
- Department of Cellular Biology, University of Georgia, Athens, United States
| | - George B Witman
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, United States
| | - Peter Kner
- College of Engineering, University of Georgia, Athens, United States
| | - Karl Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, United States
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30
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Lechtreck KF, Van De Weghe JC, Harris JA, Liu P. Protein transport in growing and steady-state cilia. Traffic 2017; 18:277-286. [PMID: 28248449 DOI: 10.1111/tra.12474] [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: 07/29/2016] [Revised: 02/22/2017] [Accepted: 02/22/2017] [Indexed: 12/18/2022]
Abstract
Cilia and eukaryotic flagella are threadlike cell extensions with motile and sensory functions. Their assembly requires intraflagellar transport (IFT), a bidirectional motor-driven transport of protein carriers along the axonemal microtubules. IFT moves ample amounts of structural proteins including tubulin into growing cilia likely explaining its critical role for assembly. IFT continues in non-growing cilia contributing to a variety of processes ranging from axonemal maintenance and the export of non-ciliary proteins to cell locomotion and ciliary signaling. Here, we discuss recent data on cues regulating the type, amount and timing of cargo transported by IFT. A regulation of IFT-cargo interactions is critical to establish, maintain and adjust ciliary length, protein composition and function.
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Affiliation(s)
- Karl F Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, Georgia
| | | | | | - Peiwei Liu
- Department of Cellular Biology, University of Georgia, Athens, Georgia
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31
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Mijalkovic J, Prevo B, Oswald F, Mangeol P, Peterman EJG. Ensemble and single-molecule dynamics of IFT dynein in Caenorhabditis elegans cilia. Nat Commun 2017; 8:14591. [PMID: 28230057 PMCID: PMC5331336 DOI: 10.1038/ncomms14591] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 01/13/2017] [Indexed: 12/14/2022] Open
Abstract
Cytoplasmic dyneins drive microtubule-based, minus-end directed transport in eukaryotic cells. Whereas cytoplasmic dynein 1 has been widely studied, IFT dynein has received far less attention. Here, we use fluorescence microscopy of labelled motors in living Caenorhabditis elegans to investigate IFT-dynein motility at the ensemble and single-molecule level. We find that while the kinesin composition of motor ensembles varies along the track, the amount of dynein remains relatively constant. Remarkably, this does not result in directionality changes of cargo along the track, as has been reported for other opposite-polarity, tug-of-war motility systems. At the single-molecule level, IFT-dynein trajectories reveal unexpected dynamics, including diffusion at the base, and pausing and directional switches along the cilium. Stochastic simulations show that the ensemble IFT-dynein distribution depends upon the probability of single-motor directional switches. Our results provide quantitative insight into IFT-dynein dynamics in vivo, shedding light on the complex functioning of dynein motors in general.
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Affiliation(s)
- Jona Mijalkovic
- Department of Physics and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, De Boelelaan 1081, Amsterdam 1081 HV, The Netherlands
| | - Bram Prevo
- Department of Physics and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, De Boelelaan 1081, Amsterdam 1081 HV, The Netherlands
| | - Felix Oswald
- Department of Physics and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, De Boelelaan 1081, Amsterdam 1081 HV, The Netherlands
| | - Pierre Mangeol
- Department of Physics and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, De Boelelaan 1081, Amsterdam 1081 HV, The Netherlands
| | - Erwin J. G. Peterman
- Department of Physics and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, De Boelelaan 1081, Amsterdam 1081 HV, The Netherlands
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