1
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Clark-Cotton MR, Chen SA, Gomez A, Mulabagal AJ, Perry A, Malhotra V, Onishi M. Imaging-based screen identifies novel natural compounds that perturb cell and chloroplast division in Chlamydomonas reinhardtii. Mol Biol Cell 2025; 36:br14. [PMID: 40020179 PMCID: PMC12005104 DOI: 10.1091/mbc.e24-09-0425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2025] [Revised: 02/11/2025] [Accepted: 02/18/2025] [Indexed: 03/12/2025] Open
Abstract
Successful cell division requires faithful division and segregation of organelles into daughter cells. The unicellular alga Chlamydomonas reinhardtii has a single, large chloroplast whose division is spatiotemporally coordinated with furrowing. Cytoskeletal structures form in the same plane at the midzone of the dividing chloroplast (FtsZ) and the cell (microtubules), but how these structures are coordinated is not understood. Previous work showed that loss of F-actin blocks chloroplast division but not furrow ingression, suggesting that pharmacological perturbations can disorganize these events. In this study, we developed an imaging platform to screen natural compounds that perturb cell division while monitoring FtsZ and microtubules and identified 70 unique compounds. One compound, curcumin, has been proposed to bind to both FtsZ and tubulin proteins in bacteria and eukaryotes, respectively. In C. reinhardtii, where both targets coexist and are involved in cell division, curcumin at a specific dose range caused a severe disruption of the FtsZ ring in chloroplast while leaving the furrow-associated microtubule structures largely intact. Time-lapse imaging showed that loss of FtsZ and chloroplast division failure delayed the completion of furrowing but not the initiation, suggesting that the chloroplast division checkpoint proposed in other algae requires FtsZ or is absent altogether in C. reinhardtii.
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Affiliation(s)
| | - Sheng-An Chen
- Department of Biology, Duke University, Durham, NC 27708
| | - Aracely Gomez
- Project SEED, North Carolina Section, American Chemical Society, Chapel Hill, NC 27514
| | | | - Adriana Perry
- Project SEED, North Carolina Section, American Chemical Society, Chapel Hill, NC 27514
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2
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Hong J, Lee C, Papoulas O, Pan J, Takagishi M, Manzi N, Dickinson DJ, Horani A, Brody SL, Marcotte E, Park TJ, Wallingford JB. Molecular organization of the distal tip of vertebrate motile cilia. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2025:2025.02.19.639145. [PMID: 40027778 PMCID: PMC11870508 DOI: 10.1101/2025.02.19.639145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/05/2025]
Abstract
The beating of cilia on multi-ciliated cells (MCCs) is essential for normal development and homeostasis in animals. Unlike basal bodies or axonemes, the distal tips of MCC cilia remain poorly defined. Here, we characterize the molecular organization of the distal tip of vertebrate MCC cilia, revealing two distinct domains occupied by distinct protein constituents. Using frog, mouse, and human MCCs, we find that two largely uncharacterized proteins, Ccdc78 and Ccdc33 occupy a specialized region at the extreme distal tip, and these are required for the normal organization of other tip proteins, including Spef1, Cep104, and Eb3. Ccdc78 and Cccdc33 are also independently required for normal length regulation of MCC cilia. Mechanistically, Ccdc78 and Ccdc33 display robust microtubule-bundling activity both in vivo and in vitro . Thus, we reveal that two previously undefined proteins form a key module for organizing and stabilizing the distal tip of motile cilia in vertebrate MCC. We propose that these proteins represent potential disease loci for motile ciliopathies.
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3
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Zhang Y, He M, Pan J. Axonemal microtubule dynamics in the assembly and disassembly of cilia. Biochem Soc Trans 2025; 53:BST20240688. [PMID: 39889304 DOI: 10.1042/bst20240688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2024] [Revised: 11/28/2024] [Accepted: 12/23/2024] [Indexed: 02/02/2025]
Abstract
Cilia and eukaryotic flagella (exchangeable terms) function in cell motility and signaling, which are pivotal for development and physiology. Cilia dysfunction can lead to ciliopathies. Cilia are usually assembled in quiescent and/or differentiated cells and undergo disassembly when cells enter cell cycle or in response to environmental stresses. Cilia contain a microtubule-based structure termed axoneme that comprises nine outer doublet microtubules with or without a pair of central microtubules, which is ensheathed by the ciliary membrane. Regulation of the axonemal microtubule dynamics is tightly associated with ciliary assembly and disassembly. In this short review, we discuss recent findings on the regulation of axonemal microtubules by microtubule-binding proteins and microtubule modulating kinesins during ciliary assembly and disassembly.
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Affiliation(s)
- Yi Zhang
- MOE Key Laboratory of Protein Sciences,State Key Laboratory of Complex, Severe, and Rare Diseases, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
- Laboratory for Marine Biology and Biotechnology, Qingdao Marine Science and Technology Center, Qingdao, China
| | - Mu He
- School of Biomedical Sciences, The University of Hong Kong, Hongkong, China
| | - Junmin Pan
- MOE Key Laboratory of Protein Sciences,State Key Laboratory of Complex, Severe, and Rare Diseases, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
- Laboratory for Marine Biology and Biotechnology, Qingdao Marine Science and Technology Center, Qingdao, China
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4
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Saunders HAJ, van den Berg CM, Hoogebeen RA, Schweizer D, Stecker KE, Roepman R, Howes SC, Akhmanova A. A network of interacting ciliary tip proteins with opposing activities imparts slow and processive microtubule growth. Nat Struct Mol Biol 2025:10.1038/s41594-025-01483-y. [PMID: 39856351 DOI: 10.1038/s41594-025-01483-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Accepted: 01/03/2025] [Indexed: 01/27/2025]
Abstract
Cilia are motile or sensory organelles present on many eukaryotic cells. Their formation and function rely on axonemal microtubules, which exhibit very slow dynamics, but the underlying mechanisms are largely unexplored. Here we reconstituted in vitro the individual and collective activities of the ciliary tip module proteins CEP104, CSPP1, TOGARAM1, ARMC9 and CCDC66, which interact with each other and with microtubules and, when mutated in humans, cause ciliopathies such as Joubert syndrome. We show that CEP104, a protein with a tubulin-binding TOG domain, and its luminal partner CSPP1 inhibit microtubule growth and shortening. Another TOG-domain protein, TOGARAM1, overcomes growth inhibition imposed by CEP104 and CSPP1. CCDC66 and ARMC9 do not affect microtubule dynamics but act as scaffolds for their partners. Cryo-electron tomography demonstrated that, together, ciliary tip module members form plus-end-specific cork-like structures that reduce protofilament flaring. The combined effect of these proteins is very slow processive microtubule elongation, which recapitulates axonemal dynamics in cells.
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Affiliation(s)
- Harriet A J Saunders
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Cyntha M van den Berg
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Robin A Hoogebeen
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Donna Schweizer
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Kelly E Stecker
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
- Netherlands Proteomics Center, Utrecht, The Netherlands
| | - Ronald Roepman
- Department of Human Genetics, Research Institute for Medical Innovation, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Stuart C Howes
- Structural Biochemistry, Department of Chemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, Utrecht, The Netherlands
| | - Anna Akhmanova
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands.
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5
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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; 81:539-555. [PMID: 38224153 DOI: 10.1002/cm.21818] [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: 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 components 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 the 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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6
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Legal T, Parra M, Tong M, Black CS, Joachimiak E, Valente-Paterno M, Lechtreck K, Gaertig J, Bui KH. CEP104/FAP256 and associated cap complex maintain stability of the ciliary tip. J Cell Biol 2023; 222:e202301129. [PMID: 37756660 PMCID: PMC10522465 DOI: 10.1083/jcb.202301129] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 07/13/2023] [Accepted: 08/30/2023] [Indexed: 09/29/2023] Open
Abstract
Cilia are essential organelles that protrude from the cell body. Cilia are made of a microtubule-based structure called the axoneme. In most types of cilia, the ciliary tip is distinct from the rest of the cilium. Here, we used cryo-electron tomography and subtomogram averaging to obtain the structure of the ciliary tip of the ciliate Tetrahymena thermophila. We show that the microtubules at the tip are highly crosslinked with each other and stabilized by luminal proteins, plugs, and cap proteins at the plus ends. In the tip region, the central pair lacks typical projections and twists significantly. By analyzing cells lacking a ciliary tip-enriched protein CEP104/FAP256 by cryo-electron tomography and proteomics, we discovered candidates for the central pair cap complex and explained the potential functions of CEP104/FAP256. These data provide new insights into the function of the ciliary tip and the mechanisms of ciliary assembly and length regulation.
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Affiliation(s)
- Thibault Legal
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Québec, Canada
| | - Mireya Parra
- Department of Cellular Biology, University of Georgia, Athens, GA, USA
| | - Maxwell Tong
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Québec, Canada
| | - Corbin S. Black
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Québec, Canada
| | - Ewa Joachimiak
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology of the Polish Academy of Sciences, Warsaw, Poland
| | - Melissa Valente-Paterno
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Québec, Canada
| | - Karl Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, GA, USA
| | - Jacek Gaertig
- Department of Cellular Biology, University of Georgia, Athens, GA, USA
| | - Khanh Huy Bui
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Québec, Canada
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7
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Konjikusic MJ, Lee C, Yue Y, Shrestha BD, Nguimtsop AM, Horani A, Brody S, Prakash VN, Gray RS, Verhey KJ, Wallingford JB. Kif9 is an active kinesin motor required for ciliary beating and proximodistal patterning of motile axonemes. J Cell Sci 2023; 136:jcs259535. [PMID: 35531639 PMCID: PMC9357393 DOI: 10.1242/jcs.259535] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 04/27/2022] [Indexed: 03/19/2024] Open
Abstract
Most motile cilia have a stereotyped structure of nine microtubule outer doublets and a single central pair of microtubules. The central pair of microtubules are surrounded by a set of proteins, termed the central pair apparatus. A specific kinesin, Klp1 projects from the central pair and contributes to ciliary motility in Chlamydomonas. The vertebrate ortholog, Kif9, is required for beating in mouse sperm flagella, but the mechanism of Kif9/Klp1 function remains poorly defined. Here, using Xenopus epidermal multiciliated cells, we show that Kif9 is necessary for ciliary motility and the proper distal localization of not only central pair proteins, but also radial spokes and dynein arms. In addition, single-molecule assays in vitro reveal that Xenopus Kif9 is a long-range processive motor, although it does not mediate long-range movement in ciliary axonemes in vivo. Together, our data suggest that Kif9 is integral for ciliary beating and is necessary for proper axonemal distal end integrity.
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Affiliation(s)
- Mia J. Konjikusic
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
- Department of Pediatrics, Dell Pediatric Research Institute, 1400 Barbara Jordan Blvd, The University of Texas at Austin, Dell Medical School, Austin, TX 78712, USA
- Department of Nutritional Sciences, 200 W 24th Street, The University of Texas at Austin, Austin, TX 78712, USA
| | - Chanjae Lee
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Yang Yue
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | | | - Ange M. Nguimtsop
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Amjad Horani
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO 63130, USA
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Steven Brody
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Vivek N. Prakash
- Department of Physics, University of Miami, Coral Gables, FL 33146, USA
- Department of Biology and Department of Marine Biology and Ecology, University of Miami, Coral Gables, FL 33146,USA
| | - Ryan S. Gray
- Department of Pediatrics, Dell Pediatric Research Institute, 1400 Barbara Jordan Blvd, The University of Texas at Austin, Dell Medical School, Austin, TX 78712, USA
- Department of Nutritional Sciences, 200 W 24th Street, The University of Texas at Austin, Austin, TX 78712, USA
| | - Kristen J. Verhey
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - John B. Wallingford
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
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8
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Legal T, Tong M, Black C, Valente Paterno M, Gaertig J, Bui KH. Molecular architecture of the ciliary tip revealed by cryo-electron tomography. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.03.522627. [PMID: 36711791 PMCID: PMC9881849 DOI: 10.1101/2023.01.03.522627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Cilia are essential organelles that protrude from the cell body. Cilia are made of a microtubule-based structure called the axoneme. In most types of cilia, the ciliary tip is distinct from the rest of the cilium. Here, we used cryo-electron tomography and subtomogram averaging to obtain the structure of the ciliary tip of the ciliate Tetrahymena thermophila. We show the microtubules in the tip are highly cross-linked with each other and stabilised by luminal proteins, plugs and cap proteins at the plus ends. In the tip region, the central pair lacks the typical projections and twists significantly. By analysing cells lacking a ciliary tip-enriched protein CEP104/FAP256 by cryo-electron tomography and proteomics, we discovered candidates for the central pair cap complex and explain potential functions of CEP104/FAP256. These data provide new insights into the function of the ciliary tip and inform about the mechanisms of ciliary assembly and length regulation.
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Affiliation(s)
- T Legal
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Québec, Canada
| | - M Tong
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Québec, Canada
| | - C Black
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Québec, Canada
| | - M Valente Paterno
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Québec, Canada
| | - J Gaertig
- Department of Cellular Biology, University of Georgia, Athens, GA, United States of America
| | - K H Bui
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Québec, Canada
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9
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Petrova DP, Khabudaev KV, Bedoshvili YD, Likhoshway YV. Phylogeny and structural peculiarities of the EB proteins of diatoms. J Struct Biol 2021; 213:107775. [PMID: 34364984 DOI: 10.1016/j.jsb.2021.107775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 08/02/2021] [Accepted: 08/03/2021] [Indexed: 11/25/2022]
Abstract
The end-binding proteins are a family of microtubule-associated proteins; this family belongs to plus-end-tracking proteins (+TIPs) that regulate microtubule growth and stabilisation. Although the genes encoding EB proteins are found in all eukaryotic genomes, most studies of them have centred on one or another taxonomic group, without a broad comparative analysis. Here, we present a first phylogenetic analysis and a comparative analysis of domain structures of diatom EB proteins in comparison with other phyla of Chromista, red and green algae, as well as model organisms A. thaliana and H. sapiens. Phylogenetically, diatom EB proteins are separated into six clades, generally corresponding to the phylogeny of their respective organisms. The domain structure of this family is highly variable, but the CH and EBH domains responsible for binding tubulin and other MAPs are mostly conserved. Homologous modelling of the F. cylindrus EB protein shows that conserved motifs of the CH domain are positioned on the protein surface, which is necessary for their functioning. We hypothesise that high variance of the diatom C-terminal domain is caused by previously unknown interactions with a CAP-GLY motif of dynactin subunit p150. Our findings contribute to wider possibilities for further investigations of the cytoskeleton in diatoms.
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Affiliation(s)
- Darya P Petrova
- Limnological Institute, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia
| | - Kirill V Khabudaev
- Limnological Institute, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia
| | | | - Yelena V Likhoshway
- Limnological Institute, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia.
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10
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Doornbos C, Roepman R. Moonlighting of mitotic regulators in cilium disassembly. Cell Mol Life Sci 2021; 78:4955-4972. [PMID: 33860332 PMCID: PMC8233288 DOI: 10.1007/s00018-021-03827-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 03/03/2021] [Accepted: 03/27/2021] [Indexed: 02/07/2023]
Abstract
Correct timing of cellular processes is essential during embryological development and to maintain the balance between healthy proliferation and tumour formation. Assembly and disassembly of the primary cilium, the cell’s sensory signalling organelle, are linked to cell cycle timing in the same manner as spindle pole assembly and chromosome segregation. Mitotic processes, ciliary assembly, and ciliary disassembly depend on the centrioles as microtubule-organizing centres (MTOC) to regulate polymerizing and depolymerizing microtubules. Subsequently, other functional protein modules are gathered to potentiate specific protein–protein interactions. In this review, we show that a significant subset of key mitotic regulator proteins is moonlighting at the cilium, among which PLK1, AURKA, CDC20, and their regulators. Although ciliary assembly defects are linked to a variety of ciliopathies, ciliary disassembly defects are more often linked to brain development and tumour formation. Acquiring a better understanding of the overlap in regulators of ciliary disassembly and mitosis is essential in finding therapeutic targets for the different diseases and types of tumours associated with these regulators.
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Affiliation(s)
- Cenna Doornbos
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ronald Roepman
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands. .,Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.
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11
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Kiesel P, Alvarez Viar G, Tsoy N, Maraspini R, Gorilak P, Varga V, Honigmann A, Pigino G. The molecular structure of mammalian primary cilia revealed by cryo-electron tomography. Nat Struct Mol Biol 2020; 27:1115-1124. [PMID: 32989303 PMCID: PMC7610599 DOI: 10.1038/s41594-020-0507-4] [Citation(s) in RCA: 118] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 08/12/2020] [Indexed: 01/09/2023]
Abstract
Primary cilia are microtubule-based organelles that are important for signaling and sensing in eukaryotic cells. Unlike the thoroughly studied motile cilia, the three-dimensional architecture and molecular composition of primary cilia are largely unexplored. Yet, studying these aspects is necessary to understand how primary cilia function in health and disease. We developed an enabling method for investigating the structure of primary cilia isolated from MDCK-II cells at molecular resolution by cryo-electron tomography. We show that the textbook '9 + 0' arrangement of microtubule doublets is only present at the primary cilium base. A few microns out, the architecture changes into an unstructured bundle of EB1-decorated microtubules and actin filaments, putting an end to a long debate on the presence or absence of actin filaments in primary cilia. Our work provides a plethora of insights into the molecular structure of primary cilia and offers a methodological framework to study these important organelles.
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Affiliation(s)
- Petra Kiesel
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | | | - Nikolai Tsoy
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Riccardo Maraspini
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Peter Gorilak
- Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Vladimir Varga
- Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Alf Honigmann
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Gaia Pigino
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.
- Human Technopole, Milan, Italy.
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12
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Yamazoe T, Nagai T, Umeda S, Sugaya Y, Mizuno K. Roles of TOG and jelly-roll domains of centrosomal protein CEP104 in its functions in cilium elongation and Hedgehog signaling. J Biol Chem 2020; 295:14723-14736. [PMID: 32820051 DOI: 10.1074/jbc.ra120.013334] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 08/11/2020] [Indexed: 12/26/2022] Open
Abstract
Primary cilia are generated through the extension of the microtubule-based axoneme. Centrosomal protein 104 (CEP104) localizes to the tip of the elongating axoneme, and CEP104 mutations are linked to a ciliopathy, Joubert syndrome. Thus, CEP104 has been implicated in ciliogenesis. However, the mechanism by which CEP104 regulates ciliogenesis remains elusive. We report here that CEP104 is critical for cilium elongation but not for initiating ciliogenesis. We also demonstrated that the tumor-overexpressed gene (TOG) domain of CEP104 exhibits microtubule-polymerizing activity and that this activity is essential for the cilium-elongating activity of CEP104. Knockdown/rescue experiments showed that the N-terminal jelly-roll (JR) fold partially contributes to cilium-elongating activity of CEP104, but neither the zinc-finger region nor the SXIP motif is required for this activity. CEP104 binds to a centriole-capping protein, CP110, through the zinc-finger region and to a microtubule plus-end-binding protein, EB1, through the SXIP motif, indicating that the binding of CP110 and EB1 is dispensable for the cilium-elongating activity of CEP104. Moreover, CEP104 depletion does not affect CP110 removal from the mother centriole, which suggests that CEP104 functions after the removal of CP110. Last, we also showed that CEP104 is required for the ciliary entry of Smoothened and export of GPR161 upon Hedgehog signal activation and that the TOG domain plays a critical role in this activity. Our results define the roles of the individual domains of CEP104 in its functions in cilium elongation and Hedgehog signaling and should enhance our understanding of the mechanism underlying CEP104 mutation-associated ciliopathies.
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Affiliation(s)
- Takashi Yamazoe
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi, Japan
| | - Tomoaki Nagai
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi, Japan; Department of Biochemistry, Fukushima Medical University School of Medicine, Fukushima, Japan.
| | - Shinya Umeda
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi, Japan
| | - Yuko Sugaya
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi, Japan
| | - Kensaku Mizuno
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi, Japan; Institute of Liberal Arts and Sciences, Tohoku University, Kawauchi, Sendai, Miyagi, Japan.
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13
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Vitre B, Guesdon A, Delaval B. Non-ciliary Roles of IFT Proteins in Cell Division and Polycystic Kidney Diseases. Front Cell Dev Biol 2020; 8:578239. [PMID: 33072760 PMCID: PMC7536321 DOI: 10.3389/fcell.2020.578239] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 08/26/2020] [Indexed: 12/30/2022] Open
Abstract
Cilia are small organelles present at the surface of most differentiated cells where they act as sensors for mechanical or biochemical stimuli. Cilia assembly and function require the Intraflagellar Transport (IFT) machinery, an intracellular transport system that functions in association with microtubules and motors. If IFT proteins have long been studied for their ciliary roles, recent evidences indicate that their functions are not restricted to the cilium. Indeed, IFT proteins are found outside the ciliary compartment where they are involved in a variety of cellular processes in association with non-ciliary motors. Recent works also provide evidence that non-ciliary roles of IFT proteins could be responsible for the development of ciliopathies related phenotypes including polycystic kidney diseases. In this review, we will discuss the interactions of IFT proteins with microtubules and motors as well as newly identified non-ciliary functions of IFT proteins, focusing on their roles in cell division. We will also discuss the potential contribution of non-ciliary IFT proteins functions to the etiology of kidney diseases.
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14
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Establishing and regulating the composition of cilia for signal transduction. Nat Rev Mol Cell Biol 2020; 20:389-405. [PMID: 30948801 DOI: 10.1038/s41580-019-0116-4] [Citation(s) in RCA: 274] [Impact Index Per Article: 54.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The primary cilium is a hair-like surface-exposed organelle of the eukaryotic cell that decodes a variety of signals - such as odorants, light and Hedgehog morphogens - by altering the local concentrations and activities of signalling proteins. Signalling within the cilium is conveyed through a diverse array of second messengers, including conventional signalling molecules (such as cAMP) and some unusual intermediates (such as sterols). Diffusion barriers at the ciliary base establish the unique composition of this signalling compartment, and cilia adapt their proteome to signalling demands through regulated protein trafficking. Much progress has been made on the molecular understanding of regulated ciliary trafficking, which encompasses not only exchanges between the cilium and the rest of the cell but also the shedding of signalling factors into extracellular vesicles.
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15
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Cilia Distal Domain: Diversity in Evolutionarily Conserved Structures. Cells 2019; 8:cells8020160. [PMID: 30769894 PMCID: PMC6406257 DOI: 10.3390/cells8020160] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Revised: 01/25/2019] [Accepted: 02/13/2019] [Indexed: 12/12/2022] Open
Abstract
Eukaryotic cilia are microtubule-based organelles that protrude from the cell surface to fulfill sensory and motility functions. Their basic structure consists of an axoneme templated by a centriole/basal body. Striking differences in ciliary ultra-structures can be found at the ciliary base, the axoneme and the tip, not only throughout the eukaryotic tree of life, but within a single organism. Defects in cilia biogenesis and function are at the origin of human ciliopathies. This structural/functional diversity and its relationship with the etiology of these diseases is poorly understood. Some of the important events in cilia function occur at their distal domain, including cilia assembly/disassembly, IFT (intraflagellar transport) complexes' remodeling, and signal detection/transduction. How axonemal microtubules end at this domain varies with distinct cilia types, originating different tip architectures. Additionally, they show a high degree of dynamic behavior and are able to respond to different stimuli. The existence of microtubule-capping structures (caps) in certain types of cilia contributes to this diversity. It has been proposed that caps play a role in axoneme length control and stabilization, but their roles are still poorly understood. Here, we review the current knowledge on cilia structure diversity with a focus on the cilia distal domain and caps and discuss how they affect cilia structure and function.
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16
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Picariello T, Brown JM, Hou Y, Swank G, Cochran DA, King OD, Lechtreck K, Pazour GJ, Witman GB. A global analysis of IFT-A function reveals specialization for transport of membrane-associated proteins into cilia. J Cell Sci 2019; 132:jcs220749. [PMID: 30659111 PMCID: PMC6382014 DOI: 10.1242/jcs.220749] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 01/02/2019] [Indexed: 12/28/2022] Open
Abstract
Intraflagellar transport (IFT), which is essential for the formation and function of cilia in most organisms, is the trafficking of IFT trains (i.e. assemblies of IFT particles) that carry cargo within the cilium. Defects in IFT cause several human diseases. IFT trains contain the complexes IFT-A and IFT-B. To dissect the functions of these complexes, we studied a Chlamydomonas mutant that is null for the IFT-A protein IFT140. The mutation had no effect on IFT-B but destabilized IFT-A, preventing flagella assembly. Therefore, IFT-A assembly requires IFT140. Truncated IFT140, which lacks the N-terminal WD repeats of the protein, partially rescued IFT and supported formation of half-length flagella that contained normal levels of IFT-B but greatly reduced amounts of IFT-A. The axonemes of these flagella had normal ultrastructure and, as investigated by SDS-PAGE, normal composition. However, composition of the flagellar 'membrane+matrix' was abnormal. Analysis of the latter fraction by mass spectrometry revealed decreases in small GTPases, lipid-anchored proteins and cell signaling proteins. Thus, IFT-A is specialized for the import of membrane-associated proteins. Abnormal levels of the latter are likely to account for the multiple phenotypes of patients with defects in IFT140.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Tyler Picariello
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Jason M Brown
- Department of Biology, Salem State University, Salem, MA 01970, USA
| | - Yuqing Hou
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Gregory Swank
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Deborah A Cochran
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Oliver D King
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Karl Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Gregory J Pazour
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - George B Witman
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA 01655, USA
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17
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Composition, structure and function of the eukaryotic flagellum distal tip. Essays Biochem 2018; 62:815-828. [PMID: 30464008 PMCID: PMC6281473 DOI: 10.1042/ebc20180032] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 10/02/2018] [Accepted: 10/05/2018] [Indexed: 01/13/2023]
Abstract
Cilia and flagella are long extensions commonly found on the surface of eukaryotic cells. In fact, most human cells have a flagellum, and failure to correctly form cilia leads to a spectrum of diseases gathered under the name ‘ciliopathies’. The cilium distal tip is where it grows and signals. Yet, out of the flagellar regions, the distal tip is probably the least intensively studied. In this review, we will summarise the current knowledge on the diverse flagellar tip structures, the dynamicity and signalling that occurs here and the proteins localising to this important cellular region.
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18
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Membrane association and remodeling by intraflagellar transport protein IFT172. Nat Commun 2018; 9:4684. [PMID: 30409972 PMCID: PMC6224603 DOI: 10.1038/s41467-018-07037-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 10/14/2018] [Indexed: 01/03/2023] Open
Abstract
The cilium is an organelle used for motility and cellular signaling. Intraflagellar transport (IFT) is a process to move ciliary building blocks and signaling components into the cilium. How IFT controls the movement of ciliary components is currently poorly understood. IFT172 is the largest IFT subunit essential for ciliogenesis. Due to its large size, the characterization of IFT172 has been challenging. Using giant unilamellar vesicles (GUVs), we show that IFT172 is a membrane-interacting protein with the ability to remodel large membranes into small vesicles. Purified IFT172 has an architecture of two globular domains with a long rod-like protrusion, resembling the domain organization of coatomer proteins such as COPI-II or clathrin. IFT172 adopts two different conformations that can be manipulated by lipids or detergents: 1) an extended elongated conformation and 2) a globular closed architecture. Interestingly, the association of IFT172 with membranes is mutually exclusive with IFT57, implicating multiple functions for IFT172 within IFT. Cilia formation requires Intraflagellar transport (IFT) to move ciliary building blocks and signaling components into the cilium. Here authors use in vitro reconstitution and electron microscopy on IFT172 and reveal its ability to remodel large membrane surfaces into small vesicles.
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19
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Jenks AD, Vyse S, Wong JP, Kostaras E, Keller D, Burgoyne T, Shoemark A, Tsalikis A, de la Roche M, Michaelis M, Cinatl J, Huang PH, Tanos BE. Primary Cilia Mediate Diverse Kinase Inhibitor Resistance Mechanisms in Cancer. Cell Rep 2018; 23:3042-3055. [PMID: 29874589 PMCID: PMC6016080 DOI: 10.1016/j.celrep.2018.05.016] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 07/13/2017] [Accepted: 05/03/2018] [Indexed: 11/18/2022] Open
Abstract
Primary cilia are microtubule-based organelles that detect mechanical and chemical stimuli. Although cilia house a number of oncogenic molecules (including Smoothened, KRAS, EGFR, and PDGFR), their precise role in cancer remains unclear. We have interrogated the role of cilia in acquired and de novo resistance to a variety of kinase inhibitors, and found that, in several examples, resistant cells are distinctly characterized by an increase in the number and/or length of cilia with altered structural features. Changes in ciliation seem to be linked to differences in the molecular composition of cilia and result in enhanced Hedgehog pathway activation. Notably, manipulating cilia length via Kif7 knockdown is sufficient to confer drug resistance in drug-sensitive cells. Conversely, targeting of cilia length or integrity through genetic and pharmacological approaches overcomes kinase inhibitor resistance. Our work establishes a role for ciliogenesis and cilia length in promoting cancer drug resistance and has significant translational implications.
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Affiliation(s)
- Andrew D Jenks
- Division of Cancer Therapeutics, The Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
| | - Simon Vyse
- Division of Molecular Pathology, The Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
| | - Jocelyn P Wong
- Division of Molecular Pathology, The Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
| | - Eleftherios Kostaras
- Division of Cancer Therapeutics, The Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
| | - Deborah Keller
- FILM, Sir Alexander Fleming Building, South Kensington Campus, Imperial College London, Exhibition Road, London SW7 2AZ, UK
| | | | - Amelia Shoemark
- Imperial College London, London, UK Electron Microscopy Department, Royal Brompton and Harefield NHS Foundation Trust, London, UK
| | - Athanasios Tsalikis
- Division of Molecular Pathology, The Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
| | | | - Martin Michaelis
- Industrial Biotechnology Centre and School of Biosciences, University of Kent, Canterbury, UK
| | - Jindrich Cinatl
- Institute of Medical Virology, Goethe University Frankfurt, Paul-Ehrlich-Strasse 40, 60596 Frankfurt am Main, Germany
| | - Paul H Huang
- Division of Molecular Pathology, The Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
| | - Barbara E Tanos
- Division of Cancer Therapeutics, The Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK.
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20
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Reynolds MJ, Phetruen T, Fisher RL, Chen K, Pentecost BT, Gomez G, Ounjai P, Sui H. The Developmental Process of the Growing Motile Ciliary Tip Region. Sci Rep 2018; 8:7977. [PMID: 29789632 PMCID: PMC5964098 DOI: 10.1038/s41598-018-26111-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 05/01/2018] [Indexed: 11/09/2022] Open
Abstract
Eukaryotic motile cilia/flagella play vital roles in various physiological processes in mammals and some protists. Defects in cilia formation underlie multiple human disorders, known as ciliopathies. The detailed processes of cilia growth and development are still far from clear despite extensive studies. In this study, we characterized the process of cilium formation (ciliogenesis) by investigating the newly developed motile cilia of deciliated protists using complementary techniques in electron microscopy and image analysis. Our results demonstrated that the distal tip region of motile cilia exhibit progressive morphological changes as cilia develop. This developmental process is time-dependent and continues after growing cilia reach their full lengths. The structural analysis of growing ciliary tips revealed that B-tubules of axonemal microtubule doublets terminate far away from the tip end, which is led by the flagellar tip complex (FTC), demonstrating that the FTC might not directly mediate the fast turnover of intraflagellar transport (IFT).
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Affiliation(s)
- Matthew J Reynolds
- Wadsworth Center, New York State Department of Health, Albany, NY, 12201, USA
- Biology Department, University of Scranton, Scranton, PA, 18510, USA
| | - Tanaporn Phetruen
- Wadsworth Center, New York State Department of Health, Albany, NY, 12201, USA
- Department of Biology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Rebecca L Fisher
- Wadsworth Center, New York State Department of Health, Albany, NY, 12201, USA
| | - Ke Chen
- Wadsworth Center, New York State Department of Health, Albany, NY, 12201, USA
| | - Brian T Pentecost
- Wadsworth Center, New York State Department of Health, Albany, NY, 12201, USA
| | - George Gomez
- Biology Department, University of Scranton, Scranton, PA, 18510, USA
| | - Puey Ounjai
- Department of Biology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Haixin Sui
- Wadsworth Center, New York State Department of Health, Albany, NY, 12201, USA.
- Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, NY, 12201, USA.
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21
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Liu Y, Visetsouk M, Mynlieff M, Qin H, Lechtreck KF, Yang P. H +- and Na +- elicited rapid changes of the microtubule cytoskeleton in the biflagellated green alga Chlamydomonas. eLife 2017; 6:26002. [PMID: 28875932 PMCID: PMC5779235 DOI: 10.7554/elife.26002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 09/05/2017] [Indexed: 12/27/2022] Open
Abstract
Although microtubules are known for dynamic instability, the dynamicity is considered to be tightly controlled to support a variety of cellular processes. Yet diverse evidence suggests that this is not applicable to Chlamydomonas, a biflagellate fresh water green alga, but intense autofluorescence from photosynthesis pigments has hindered the investigation. By expressing a bright fluorescent reporter protein at the endogenous level, we demonstrate in real time discreet sweeping changes in algal microtubules elicited by rises of intracellular H+ and Na+. These results from this model organism with characteristics of animal and plant cells provide novel explanations regarding how pH may drive cellular processes; how plants may respond to, and perhaps sense stresses; and how organisms with a similar sensitive cytoskeleton may be susceptible to environmental changes.
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Affiliation(s)
- Yi Liu
- Department of Biological Sciences, Marquette University, Milwaukee, United States
| | - Mike Visetsouk
- Department of Biological Sciences, Marquette University, Milwaukee, United States
| | - Michelle Mynlieff
- Department of Biological Sciences, Marquette University, Milwaukee, United States
| | - Hongmin Qin
- Department of Biology, Texas A&M University, College Station, United States
| | - Karl F Lechtreck
- Department of Cellular Biology, University of Georgia, Athen, United States
| | - Pinfen Yang
- Department of Biological Sciences, Marquette University, Milwaukee, United States
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22
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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: 145] [Impact Index Per Article: 18.1] [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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23
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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: 1.1] [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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24
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Au FKC, Jia Y, Jiang K, Grigoriev I, Hau BKT, Shen Y, Du S, Akhmanova A, Qi RZ. GAS2L1 Is a Centriole-Associated Protein Required for Centrosome Dynamics and Disjunction. Dev Cell 2016; 40:81-94. [PMID: 28017616 DOI: 10.1016/j.devcel.2016.11.019] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2016] [Revised: 10/17/2016] [Accepted: 11/21/2016] [Indexed: 12/16/2022]
Abstract
Mitotic spindle formation and chromosome segregation require timely separation of the two duplicated centrosomes, and this process is initiated in late G2 by centrosome disjunction. Here we report that GAS2L1, a microtubule- and actin-binding protein, associates with the proximal end of mature centrioles and participates in centriole dynamics and centrosome disjunction. GAS2L1 attaches microtubules and actin to centrosomes, and the loss of GAS2L1 inhibits centrosome disjunction in G2 and centrosome splitting induced by depletion of the centrosome linker rootletin. Conversely, GAS2L1 overexpression induces premature centrosome separation, and this activity requires GAS2L1 association with actin, microtubules, and the microtubule end-binding proteins. The centrosome-splitting effect of GAS2L1 is counterbalanced by rootletin, reflecting the opposing actions of GAS2L1 and the centrosome linker. Our work reveals a GAS2L1-mediated centriole-tethering mechanism of microtubules and actin, which provide the forces required for centrosome dynamics and separation.
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Affiliation(s)
- Franco K C Au
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Yue Jia
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Kai Jiang
- Cell Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Ilya Grigoriev
- Cell Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Bill K T Hau
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Yuehong Shen
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Shengwang Du
- Department of Physics and Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Anna Akhmanova
- Cell Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Robert Z Qi
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
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25
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Taschner M, Lorentzen E. The Intraflagellar Transport Machinery. Cold Spring Harb Perspect Biol 2016; 8:cshperspect.a028092. [PMID: 27352625 DOI: 10.1101/cshperspect.a028092] [Citation(s) in RCA: 259] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Eukaryotic cilia and flagella are evolutionarily conserved organelles that protrude from the cell surface. The unique location and properties of cilia allow them to function in vital processes such as motility and signaling. Ciliary assembly and maintenance rely on intraflagellar transport (IFT), the bidirectional movement of a multicomponent transport system between the ciliary base and tip. Since its initial discovery more than two decades ago, considerable effort has been invested in dissecting the molecular mechanisms of IFT in a variety of model organisms. Importantly, IFT was shown to be essential for mammalian development, and defects in this process cause a number of human pathologies known as ciliopathies. Here, we review current knowledge of IFT with a particular emphasis on the IFT machinery and specific mechanisms of ciliary cargo recognition and transport.
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Affiliation(s)
- Michael Taschner
- Department of Structural Cell Biology, Max-Planck-Institute of Biochemistry, D-82152 Martinsried, Germany
| | - Esben Lorentzen
- Department of Structural Cell Biology, Max-Planck-Institute of Biochemistry, D-82152 Martinsried, Germany
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26
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Sloboda RD. Purification and Localization of Intraflagellar Transport Particles and Polypeptides. Methods Mol Biol 2016; 1365:119-37. [PMID: 26498782 DOI: 10.1007/978-1-4939-3124-8_6] [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: 01/21/2023]
Abstract
The growth and maintenance of almost all cilia and flagella are dependent on the proper functioning of the process of intraflagellar transport (IFT). This includes the primary cilia of most human cells that are in the Go phase of the cell cycle. The model system for the study of IFT is the flagella of the biflagellate green alga Chlamydomonas. It is in this organism that IFT was first discovered, and genetic data from a Chlamydomonas mutant first linked the process of IFT to polycystic kidney disease in humans. The information provided in this chapter addresses procedures to purify IFT particles from flagella and localize these particles, and their associated motor proteins, in flagella using light and electron microscopic approaches.
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Affiliation(s)
- Roger D Sloboda
- Department of Biological Sciences, Dartmouth College, Hanover, NH, 03755, USA.
- The Marine Biological Laboratory, Woods Hole, MA, 02543, USA.
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27
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Harris JA, Liu Y, Yang P, Kner P, Lechtreck KF. Single-particle imaging reveals intraflagellar transport-independent transport and accumulation of EB1 in Chlamydomonas flagella. Mol Biol Cell 2015; 27:295-307. [PMID: 26631555 PMCID: PMC4713132 DOI: 10.1091/mbc.e15-08-0608] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 11/20/2015] [Indexed: 12/20/2022] Open
Abstract
The microtubule (MT) plus-end tracking protein EB1 is present at the tips of cilia and flagella; end-binding protein 1 (EB1) remains at the tip during flagellar shortening and in the absence of intraflagellar transport (IFT), the predominant protein transport system in flagella. To investigate how EB1 accumulates at the flagellar tip, we used in vivo imaging of fluorescent protein-tagged EB1 (EB1-FP) in Chlamydomonas reinhardtii. After photobleaching, the EB1 signal at the flagellar tip recovered within minutes, indicating an exchange with unbleached EB1 entering the flagella from the cell body. EB1 moved independent of IFT trains, and EB1-FP recovery did not require the IFT pathway. Single-particle imaging showed that EB1-FP is highly mobile along the flagellar shaft and displays a markedly reduced mobility near the flagellar tip. Individual EB1-FP particles dwelled for several seconds near the flagellar tip, suggesting the presence of stable EB1 binding sites. In simulations, the two distinct phases of EB1 mobility are sufficient to explain its accumulation at the tip. We propose that proteins uniformly distributed throughout the cytoplasm like EB1 accumulate locally by diffusion and capture; IFT, in contrast, might be required to transport proteins against cellular concentration gradients into or out of cilia.
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Affiliation(s)
- J Aaron Harris
- Department of Cellular Biology, University of Georgia, Athens, GA 30602
| | - Yi Liu
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53233
| | - Pinfen Yang
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53233
| | - Peter Kner
- College of Engineering, University of Georgia, Athens, GA 30602
| | - Karl F Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, GA 30602
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Kubo T, Hirono M, Aikawa T, Kamiya R, Witman GB. Reduced tubulin polyglutamylation suppresses flagellar shortness in Chlamydomonas. Mol Biol Cell 2015; 26:2810-22. [PMID: 26085508 PMCID: PMC4571340 DOI: 10.1091/mbc.e15-03-0182] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 06/08/2015] [Indexed: 11/11/2022] Open
Abstract
Tubulin polyglutamylation is a posttranslational modification known to affect ciliary/flagellar motility and assembly. Investigation of Chlamydomonas mutants deficient in axonemal polyglutamylation shows that polyglutamylation functions by increasing tubulin turnover at the flagellar tip and reducing axonemal stability. Ciliary length control is an incompletely understood process essential for normal ciliary function. The flagella of Chlamydomonas mutants lacking multiple axonemal dyneins are shorter than normal; previously it was shown that this shortness can be suppressed by the mutation suppressor of shortness 1 (ssh1) via an unknown mechanism. To elucidate this mechanism, we carried out genetic analysis of ssh1 and found that it is a new allele of TPG2 (hereafter tpg2-3), which encodes FAP234 functioning in tubulin polyglutamylation in the axoneme. Similar to the polyglutamylation-deficient mutants tpg1 and tpg2-1, tpg2-3 axonemal tubulin has a greatly reduced level of long polyglutamate side chains. We found that tpg1 and tpg2-1 mutations also promote flagellar elongation in short-flagella mutants, consistent with a polyglutamylation-dependent mechanism of suppression. Double mutants of tpg1 or tpg2-1 and fla10-1, a temperature-sensitive mutant of intraflagellar transport, underwent slower flagellar shortening than fla10-1 at restrictive temperatures, indicating that the rate of tubulin disassembly is decreased in the polyglutamylation-deficient flagella. Moreover, α-tubulin incorporation into the flagellar tips in temporary dikaryons was retarded in polyglutamylation-deficient flagella. These results show that polyglutamylation deficiency stabilizes axonemal microtubules, decelerating axonemal disassembly at the flagellar tip and shifting the axonemal assembly/disassembly balance toward assembly.
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Affiliation(s)
- Tomohiro Kubo
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655 Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan
| | - Masafumi Hirono
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan
| | - Takumi Aikawa
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan
| | - Ritsu Kamiya
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan Department of Life Science, Faculty of Science, Gakushuin University, Tokyo 171-8588, Japan
| | - George B Witman
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655
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Alford LM, Mattheyses AL, Hunter EL, Lin H, Dutcher SK, Sale WS. The Chlamydomonas mutant pf27 reveals novel features of ciliary radial spoke assembly. Cytoskeleton (Hoboken) 2014; 70:804-18. [PMID: 24124175 DOI: 10.1002/cm.21144] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 09/10/2013] [Accepted: 09/12/2013] [Indexed: 01/05/2023]
Abstract
To address the mechanisms of ciliary radial spoke assembly, we took advantage of the Chlamydomonas pf27 mutant. The radial spokes that assemble in pf27 are localized to the proximal quarter of the axoneme, but otherwise are fully assembled into 20S radial spoke complexes competent to bind spokeless axonemes in vitro. Thus, pf27 is not defective in radial spoke assembly or docking to the axoneme. Rather, our results suggest that pf27 is defective in the transport of spoke complexes. During ciliary regeneration in pf27, radial spoke assembly occurs asynchronously from other axonemal components. In contrast, during ciliary regeneration in wild-type Chlamydomonas, radial spokes and other axonemal components assemble concurrently as the axoneme grows. Complementation in temporary dikaryons between wild-type and pf27 reveals rescue of radial spoke assembly that begins at the distal tip, allowing further assembly to proceed from tip to base of the axoneme. Notably, rescued assembly of radial spokes occurred independently of the established proximal radial spokes in pf27 axonemes in dikaryons. These results reveal that 20S radial spokes can assemble proximally in the pf27 cilium but as the cilium lengthens, spoke assembly requires transport. We postulate that PF27 encodes an adaptor or modifier protein required for radial spoke–IFT interaction.
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Abstract
The kinesin-4 motor protein Kif7 regulates Hedgehog signalling at cilia in mammals by controlling the activity of Gli transcription factors. Kif7 is now found to inhibit microtubule growth to restrict and coordinate the length of axonemal microtubules at the ciliary tip. Such Kif7-mediated organization of the ciliary tip compartment regulates Gli activity and is proposed to be required for correct Hedgehog signalling.
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31
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Subota I, Julkowska D, Vincensini L, Reeg N, Buisson J, Blisnick T, Huet D, Perrot S, Santi-Rocca J, Duchateau M, Hourdel V, Rousselle JC, Cayet N, Namane A, Chamot-Rooke J, Bastin P. Proteomic analysis of intact flagella of procyclic Trypanosoma brucei cells identifies novel flagellar proteins with unique sub-localization and dynamics. Mol Cell Proteomics 2014; 13:1769-86. [PMID: 24741115 DOI: 10.1074/mcp.m113.033357] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Cilia and flagella are complex organelles made of hundreds of proteins of highly variable structures and functions. Here we report the purification of intact flagella from the procyclic stage of Trypanosoma brucei using mechanical shearing. Structural preservation was confirmed by transmission electron microscopy that showed that flagella still contained typical elements such as the membrane, the axoneme, the paraflagellar rod, and the intraflagellar transport particles. It also revealed that flagella severed below the basal body, and were not contaminated by other cytoskeletal structures such as the flagellar pocket collar or the adhesion zone filament. Mass spectrometry analysis identified a total of 751 proteins with high confidence, including 88% of known flagellar components. Comparison with the cell debris fraction revealed that more than half of the flagellum markers were enriched in flagella and this enrichment criterion was taken into account to identify 212 proteins not previously reported to be associated to flagella. Nine of these were experimentally validated including a 14-3-3 protein not yet reported to be associated to flagella and eight novel proteins termed FLAM (FLAgellar Member). Remarkably, they localized to five different subdomains of the flagellum. For example, FLAM6 is restricted to the proximal half of the axoneme, no matter its length. In contrast, FLAM8 is progressively accumulating at the distal tip of growing flagella and half of it still needs to be added after cell division. A combination of RNA interference and Fluorescence Recovery After Photobleaching approaches demonstrated very different dynamics from one protein to the other, but also according to the stage of construction and the age of the flagellum. Structural proteins are added to the distal tip of the elongating flagellum and exhibit slow turnover whereas membrane proteins such as the arginine kinase show rapid turnover without a detectible polarity.
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Affiliation(s)
- Ines Subota
- From the ‡Trypanosome Cell Biology Unit, Institut Pasteur & CNRS URA2581
| | - Daria Julkowska
- From the ‡Trypanosome Cell Biology Unit, Institut Pasteur & CNRS URA2581
| | | | - Nele Reeg
- From the ‡Trypanosome Cell Biology Unit, Institut Pasteur & CNRS URA2581
| | - Johanna Buisson
- From the ‡Trypanosome Cell Biology Unit, Institut Pasteur & CNRS URA2581
| | - Thierry Blisnick
- From the ‡Trypanosome Cell Biology Unit, Institut Pasteur & CNRS URA2581
| | - Diego Huet
- From the ‡Trypanosome Cell Biology Unit, Institut Pasteur & CNRS URA2581
| | - Sylvie Perrot
- From the ‡Trypanosome Cell Biology Unit, Institut Pasteur & CNRS URA2581
| | - Julien Santi-Rocca
- From the ‡Trypanosome Cell Biology Unit, Institut Pasteur & CNRS URA2581
| | - Magalie Duchateau
- §Proteomics Platform, Institut Pasteur, ¶Structural Mass Spectrometry and Proteomics Unit, Institut Pasteur & CNRS UMR3528
| | - Véronique Hourdel
- §Proteomics Platform, Institut Pasteur, ¶Structural Mass Spectrometry and Proteomics Unit, Institut Pasteur & CNRS UMR3528
| | | | - Nadège Cayet
- ‖Imagopole Platform, Institut Pasteur, Paris, France
| | | | - Julia Chamot-Rooke
- §Proteomics Platform, Institut Pasteur, ¶Structural Mass Spectrometry and Proteomics Unit, Institut Pasteur & CNRS UMR3528
| | - Philippe Bastin
- From the ‡Trypanosome Cell Biology Unit, Institut Pasteur & CNRS URA2581,
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32
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Blacque OE, Sanders AAWM. Compartments within a compartment: what C. elegans can tell us about ciliary subdomain composition, biogenesis, function, and disease. Organogenesis 2014; 10:126-37. [PMID: 24732235 DOI: 10.4161/org.28830] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The primary cilium has emerged as a hotbed of sensory and developmental signaling, serving as a privileged domain to concentrate the functions of a wide number of channels, receptors and downstream signal transducers. This realization has provided important insight into the pathophysiological mechanisms underlying the ciliopathies, an ever expanding spectrum of multi-symptomatic disorders affecting the development and maintenance of multiple tissues and organs. One emerging research focus is the subcompartmentalised nature of the organelle, consisting of discrete structural and functional subdomains such as the periciliary membrane/basal body compartment, the transition zone, the Inv compartment and the distal segment/ciliary tip region. Numerous ciliopathy, transport-related and signaling molecules localize at these compartments, indicating specific roles at these subciliary sites. Here, by focusing predominantly on research from the genetically tractable nematode C. elegans, we review ciliary subcompartments in terms of their structure, function, composition, biogenesis and relationship to human disease.
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Affiliation(s)
- Oliver E Blacque
- School of Biomolecular and Biomedical Science; University College Dublin; Dublin, Ireland
| | - Anna A W M Sanders
- School of Biomolecular and Biomedical Science; University College Dublin; Dublin, Ireland
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33
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Kypri E, Christodoulou A, Maimaris G, Lethan M, Markaki M, Lysandrou C, Lederer CW, Tavernarakis N, Geimer S, Pedersen LB, Santama N. The nucleotide-binding proteins Nubp1 and Nubp2 are negative regulators of ciliogenesis. Cell Mol Life Sci 2014; 71:517-38. [PMID: 23807208 PMCID: PMC11113914 DOI: 10.1007/s00018-013-1401-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 06/03/2013] [Accepted: 06/06/2013] [Indexed: 12/12/2022]
Abstract
Nucleotide-binding proteins Nubp1 and Nubp2 are MRP/MinD-type P-loop NTPases with sequence similarity to bacterial division site-determining proteins and are conserved, essential proteins throughout the Eukaryotes. They have been implicated, together with their interacting minus-end directed motor protein KIFC5A, in the regulation of centriole duplication in mammalian cells. Here we show that Nubp1 and Nubp2 are integral components of centrioles throughout the cell cycle, recruited independently of KIFC5A. We further demonstrate their localization at the basal body of the primary cilium in quiescent vertebrate cells or invertebrate sensory cilia, as well as in the motile cilia of mouse cells and in the flagella of Chlamydomonas. RNAi-mediated silencing of nubp-1 in C. elegans causes the formation of morphologically aberrant and additional cilia in sensory neurons. Correspondingly, downregulation of Nubp1 or Nubp2 in mouse quiescent NIH 3T3 cells markedly increases the number of ciliated cells, while knockdown of KIFC5A dramatically reduces ciliogenesis. Simultaneous double silencing of Nubp1 + KIFC5A restores the percentage of ciliated cells to control levels. We document the normal ciliary recruitment, during these silencing regimes, of basal body proteins critical for ciliogenesis, namely CP110, CEP290, cenexin, Chibby, AurA, Rab8, and BBS7. Interestingly, we uncover novel interactions of Nubp1 with several members of the CCT/TRiC molecular chaperone complex, which we find enriched at the basal body and recruited independently of the Nubps or KIFC5A. Our combined results for Nubp1, Nubp2, and KIFC5A and their striking effects on cilium formation suggest a central regulatory role for these proteins, likely involving CCT/TRiC chaperone activity, in ciliogenesis.
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Affiliation(s)
- Elena Kypri
- Department of Biological Sciences, University of Cyprus, University Avenue 1, 1678 Nicosia, Cyprus
| | - Andri Christodoulou
- Department of Biological Sciences, University of Cyprus, University Avenue 1, 1678 Nicosia, Cyprus
| | - Giannis Maimaris
- Department of Biological Sciences, University of Cyprus, University Avenue 1, 1678 Nicosia, Cyprus
| | - Mette Lethan
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Maria Markaki
- Institute of Molecular Biology and Biotechnology, Crete, Greece
| | - Costas Lysandrou
- Department of Biological Sciences, University of Cyprus, University Avenue 1, 1678 Nicosia, Cyprus
| | | | | | | | - Lotte B. Pedersen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Niovi Santama
- Department of Biological Sciences, University of Cyprus, University Avenue 1, 1678 Nicosia, Cyprus
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34
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Abstract
Cilia and flagella are surface-exposed, finger-like organelles whose core consists of a microtubule (MT)-based axoneme that grows from a modified centriole, the basal body. Cilia are found on the surface of many eukaryotic cells and play important roles in cell motility and in coordinating a variety of signaling pathways during growth, development, and tissue homeostasis. Defective cilia have been linked to a number of developmental disorders and diseases, collectively called ciliopathies. Cilia are dynamic organelles that assemble and disassemble in tight coordination with the cell cycle. In most cells, cilia are assembled during growth arrest in a multistep process involving interaction of vesicles with appendages present on the distal end of mature centrioles, and addition of tubulin and other building blocks to the distal tip of the basal body and growing axoneme; these building blocks are sorted through a region at the cilium base known as the ciliary necklace, and then transported via intraflagellar transport (IFT) along the axoneme toward the tip for assembly. After assembly, the cilium frequently continues to turn over and incorporate tubulin at its distal end in an IFT-dependent manner. Prior to cell division, the cilia are usually resorbed to liberate centrosomes for mitotic spindle pole formation. Here, we present an overview of the main cytoskeletal structures associated with cilia and centrioles with emphasis on the MT-associated appendages, fibers, and filaments at the cilium base and tip. The composition and possible functions of these structures are discussed in relation to cilia assembly, disassembly, and length regulation.
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Affiliation(s)
- Lotte B Pedersen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark.
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35
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Larsen J, Grigoriev I, Akhmanova A, Pedersen LB. Analysis of microtubule plus-end-tracking proteins in cilia. Methods Enzymol 2013; 524:105-22. [PMID: 23498737 DOI: 10.1016/b978-0-12-397945-2.00007-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The microtubule (MT) plus-end-tracking proteins (+TIPs) belonging to the end binding (EB) protein family have been studied extensively in the context of cytoplasmic MTs and were shown to play pivotal roles in regulating MT dynamics and in recruiting other +TIPs to MT ends. Early studies in the green alga Chlamydomonas reinhardtii showed that EB1 localizes to the distal flagellum tip and the basal body, and subsequent studies using green fluorescent protein-tagged fusion proteins have demonstrated similar localization of EBs in other ciliated organisms, including mammalian cells as demonstrated here. Functional analysis of EBs in cultured mammalian cells revealed that EB1 and EB3 are required for biogenesis of primary cilia. Although mammalian EB3 localizes to the tip of some cilia and induces cilium elongation, EBs primarily seem to promote ciliogenesis via MT minus-end anchoring at the basal body, in turn facilitating vesicular trafficking to the cilium base. Moreover, mammalian EBs were shown to interact with several proteins implicated in MT minus-end anchoring and/or vesicular trafficking to cilia. Recent work suggests that apart from EBs, additional +TIPs may be present at the distal tip of cilia where they could regulate axoneme assembly, stability, or disassembly.
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Affiliation(s)
- Jesper Larsen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
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Satish Tammana TV, Tammana D, Diener DR, Rosenbaum J. Centrosomal protein CEP104 (Chlamydomonas FAP256) moves to the ciliary tip during ciliary assembly. J Cell Sci 2013; 126:5018-29. [PMID: 23970417 DOI: 10.1242/jcs.133439] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The ciliary tip has been implicated in ciliary assembly and disassembly, and signaling, yet information on its protein composition is limited. Using comparative, quantitative proteomics based on the fact that tip proteins will be approximately twice as concentrated in half-length compared with full-length flagella, we have identified FAP256 as a tip protein in Chlamydomonas. FAP256 localizes to the tips of both central pair and outer doublet microtubules (MTs) and it remains at the tip during flagellar assembly and disassembly. Similarly, its vertebrate counterpart, CEP104, localizes on the distal ends of both centrioles of nondividing cells until the mother centriole forms a cilium and then localizes at the tip of the elongating cilium. A null mutant of FAP256 in Chlamydomonas and RNAi in vertebrate cells showed that FAP256/CEP104 is required for ciliogenesis in a high percentage of cells. In those cells that could form cilia, there were structural deformities at the ciliary tips.
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Affiliation(s)
- Trinadh V Satish Tammana
- Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA
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37
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Bhogaraju S, Engel BD, Lorentzen E. Intraflagellar transport complex structure and cargo interactions. Cilia 2013; 2:10. [PMID: 23945166 PMCID: PMC3751104 DOI: 10.1186/2046-2530-2-10] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 07/05/2013] [Indexed: 11/10/2022] Open
Abstract
Intraflagellar transport (IFT) is required for the assembly and maintenance of cilia, as well as the proper function of ciliary motility and signaling. IFT is powered by molecular motors that move along the axonemal microtubules, carrying large complexes of IFT proteins that travel together as so-called trains. IFT complexes likely function as adaptors that mediate interactions between anterograde/retrograde motors and ciliary cargoes, facilitating cargo transport between the base and tip of the cilium. Here, we provide an up-to-date review of IFT complex structure and architecture, and discuss how interactions with cargoes and motors may be achieved.
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Affiliation(s)
- Sagar Bhogaraju
- Department of Structural Cell Biology, Max-Planck-Institute of Biochemistry, Am Klopferspitz 18, Martinsried, D-82152, Germany.
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Engel BD, Ishikawa H, Wemmer KA, Geimer S, Wakabayashi KI, Hirono M, Craige B, Pazour GJ, Witman GB, Kamiya R, Marshall WF. The role of retrograde intraflagellar transport in flagellar assembly, maintenance, and function. ACTA ACUST UNITED AC 2013; 199:151-67. [PMID: 23027906 PMCID: PMC3461521 DOI: 10.1083/jcb.201206068] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
An inducible dynein heavy chain 1b mutant reveals that robust retrograde intraflagellar transport is required for flagellar assembly and function but not the maintenance of flagellar length. The maintenance of flagellar length is believed to require both anterograde and retrograde intraflagellar transport (IFT). However, it is difficult to uncouple the functions of retrograde transport from anterograde, as null mutants in dynein heavy chain 1b (DHC1b) have stumpy flagella, demonstrating solely that retrograde IFT is required for flagellar assembly. We isolated a Chlamydomonas reinhardtii mutant (dhc1b-3) with a temperature-sensitive defect in DHC1b, enabling inducible inhibition of retrograde IFT in full-length flagella. Although dhc1b-3 flagella at the nonpermissive temperature (34°C) showed a dramatic reduction of retrograde IFT, they remained nearly full-length for many hours. However, dhc1b-3 cells at 34°C had strong defects in flagellar assembly after cell division or pH shock. Furthermore, dhc1b-3 cells displayed altered phototaxis and flagellar beat. Thus, robust retrograde IFT is required for flagellar assembly and function but is dispensable for the maintenance of flagellar length. Proteomic analysis of dhc1b-3 flagella revealed distinct classes of proteins that change in abundance when retrograde IFT is inhibited.
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Affiliation(s)
- Benjamin D Engel
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
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40
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Pan J, Seeger-Nukpezah T, Golemis EA. The role of the cilium in normal and abnormal cell cycles: emphasis on renal cystic pathologies. Cell Mol Life Sci 2012; 70:1849-74. [PMID: 22782110 DOI: 10.1007/s00018-012-1052-z] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Revised: 05/08/2012] [Accepted: 06/05/2012] [Indexed: 12/28/2022]
Abstract
The primary cilium protrudes from the cell surface and acts as a sensor for chemical and mechanical growth cues, with receptors for a number of growth factors (PDGFα, Hedgehog, Wnt, Notch) concentrated within the ciliary membrane. In normal tissues, the cilium assembles after cells exit mitosis and is resorbed as part of cell cycle re-entry. Although regulation of the cilium by cell cycle transitions has been appreciated for over 100 years, only recently have data emerged to indicate the cilium also exerts influence on the cell cycle. The resorption/protrusion cycle, regulated by proteins including Aurora-A, VHL, and GSK-3β, influences cell responsiveness to growth cues involving cilia-linked receptors; further, resorption liberates the ciliary basal body to differentiate into the centrosome, which performs discrete functions in S-, G2-, and M-phase. Besides these roles, the cilium provides a positional cue that regulates polarity of cell division, and thus directs cells towards fates of differentiation versus proliferation. In this review, we summarize the specific mechanisms mediating the cilia-cell cycle dialog. We then emphasize the examples of polycystic kidney disease (PKD), nephronopthisis (NPHP), and VHL-linked renal cysts as cases in which defects of ciliary function influence disease pathology, and may also condition response to treatment.
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Affiliation(s)
- Junmin Pan
- Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
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41
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Williamson SM, Silva DA, Richey E, Qin H. Probing the role of IFT particle complex A and B in flagellar entry and exit of IFT-dynein in Chlamydomonas. PROTOPLASMA 2012; 249:851-856. [PMID: 21853389 DOI: 10.1007/s00709-011-0311-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 08/07/2011] [Indexed: 05/31/2023]
Abstract
Mediating the transport of flagellar precursors and removal of turnover products, intraflagellar transport (IFT) is required for flagella assembly and maintenance. The IFT apparatus is composed of the anterograde IFT motor kinesin II, the retrograde IFT motor IFT-dynein, and IFT particles containing two complexes, A and B. In order to have a balanced two-way transportation, IFT-dynein has to be carried into flagella and transported to the flagellar tip by kinesin II, where it is activated to drive the retrograde IFT back to the flagellar base. In this study, we investigated the role of complex A and complex B in the flagellar entry and exit of IFT-dynein. We showed that regardless of the amount of complex A, IFT-dynein accumulated proportionally to the amount of complex B in the flagella of fla15/ift144 and fla17-1/ift139, two complex A temperature-sensitive mutants. Complex A was depleted from both cellular and flagellar compartments in fla15/ift144 mutant. However, in fla17-1/ift139 mutant, the flagellar level of complex A was at the wild-type level, which was in radical contrast to the significantly reduced cellular amount of complex A. These results support that complex A is not required for the flagellar entry of IFT-dynein, but might be essential for the lagellar exit of IFT-dynein. Additionally, we confirmed the essential role of IFT172, a complex B subunit, in the flagellar entry of IFT-dynein. These results indicate that complexes A and B play complementary but distinct roles for IFT-dynein, with complex B carrying IFT-dynein into the flagella while complex A mediates the flagellar exit of IFT-dynein.
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Affiliation(s)
- Shana M Williamson
- Department of Biology, Texas A&M University, College Station, TX 77843-3258, USA
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42
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May-Simera HL, Kelley MW. Cilia, Wnt signaling, and the cytoskeleton. Cilia 2012; 1:7. [PMID: 23351924 PMCID: PMC3555707 DOI: 10.1186/2046-2530-1-7] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Accepted: 05/02/2012] [Indexed: 12/14/2022] Open
Abstract
Primary cilia have recently been highlighted as key regulators in development and disease. This review focuses on current work demonstrating the broad role of cilia-related proteins in developmental signaling systems. Of particular consideration is the importance of the basal body region, located at the base of the cilium, in its role as a focal point for many signaling pathways and as a microtubule organizing center. As the cilium is effectively a microtubular extension of the cytoskeleton, investigating connections between the cilium and the cytoskeleton provides greater insight into signaling and cell function. Of the many signaling pathways associated with primary cilia, the most extensively studied in association with the cytoskeleton and cytoskeletal rearrangements are both canonical and non-canonical Wnt pathways. One of the key concepts currently emerging is a possible additional role for the traditionally 'cilia-related' proteins in other aspects of cellular processes. In many cases, disruption of such processes manifests at the level of the cilium. While the involvement of cilia and cilia-related proteins in signaling pathways is currently being unraveled, there is a growing body of evidence to support the notion that ciliary proteins are required not only for regulation of Wnt signaling, but also as downstream effectors of Wnt signaling. This review summarizes recent advances in our understanding of the involvement of cilia and basal body proteins in Wnt signaling pathways.
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Affiliation(s)
- Helen L May-Simera
- Laboratory of Cochlear Development, National Institute on Deafness and Other Communication Disorders, NIH, 35 Convent Drive, Bethesda, MD 20892, USA.
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Hsiao YC, Tuz K, Ferland RJ. Trafficking in and to the primary cilium. Cilia 2012; 1:4. [PMID: 23351793 PMCID: PMC3541539 DOI: 10.1186/2046-2530-1-4] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Accepted: 04/25/2012] [Indexed: 01/08/2023] Open
Abstract
Polarized vesicle trafficking is mediated by small GTPase proteins, such as Rabs and Arls/Arfs. These proteins have essential roles in maintaining normal cellular function, in part, through regulating intracellular trafficking. Moreover, these families of proteins have recently been implicated in the formation and function of the primary cilium. The primary cilium, which is found on almost every cell type in vertebrates, is an organelle that protrudes from the surface of the cell and functions as a signaling center. Interestingly, it has recently been linked to a variety of human diseases, collectively referred to as ciliopathies. The primary cilium has an exceptionally high density of receptors on its membrane that are important for sensing and transducing extracellular stimuli. Moreover, the primary cilium serves as a separate cellular compartment from the cytosol, providing for unique spatial and temporal regulation of signaling molecules to initiate downstream events. Thus, functional primary cilia are essential for normal signal transduction. Rabs and Arls/Arfs play critical roles in early cilia formation but are also needed for maintenance of ciliary function through their coordination with intraflagellar transport (IFT), a specialized trafficking system in primary cilia. IFT in cilia is pivotal for the proper movement of proteins into and out of this highly regulated organelle. In this review article, we explore the involvement of polarized vesicular trafficking in cilia formation and function, and discuss how defects in these processes could subsequently lead to the abnormalities observed in ciliopathies.
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Affiliation(s)
- Yi-Chun Hsiao
- Department of Biology, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.,Albany Medical College, Center for Neuropharmacology and Neuroscience, Albany, NY 12208, USA
| | - Karina Tuz
- Albany Medical College, Center for Neuropharmacology and Neuroscience, Albany, NY 12208, USA
| | - Russell J Ferland
- Albany Medical College, Center for Neuropharmacology and Neuroscience, Albany, NY 12208, USA.,Department of Neurology, Albany Medical College, Albany, NY 12208, USA
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Fisch C, Dupuis-Williams P. [The rebirth of the ultrastructure of cilia and flagella]. Biol Aujourdhui 2012; 205:245-67. [PMID: 22251859 DOI: 10.1051/jbio/2011023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Indexed: 11/14/2022]
Abstract
The sensory and motility functions of eukaryotic cilia and flagella are essential for cell survival in protozoans and for cell differentiation and homoeostasis in metazoans. Ciliary biology has benefited early on from the input of electron microscopy. Over the last decade, the visualization of cellular structures has greatly progressed, thus it becomes timely to review the ultrastructure of cilia and flagella. Briefly touching upon the typical features of a 9+2 axoneme, we dwell extensively on the transition zone, the singlet zone, the ciliary necklace, cap and crown. The relation of the singlet zone to sensory and/or motile function, the link of the ciliary cap to microtubule dynamics and to ciliary beat, the involvement of the ciliary crown in ovocyte and mucosal propulsion, and the role of the transition zone/the ciliary necklace in axonemal stabilization, autotomy and as a diffusion barrier will all be discussed.
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Affiliation(s)
- Cathy Fisch
- ATIGE Centriole et Pathologies Associées, INSERM/UEVE U829, 91000 Évry, France.
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Schrøder JM, Larsen J, Komarova Y, Akhmanova A, Thorsteinsson RI, Grigoriev I, Manguso R, Christensen ST, Pedersen SF, Geimer S, Pedersen LB. EB1 and EB3 promote cilia biogenesis by several centrosome-related mechanisms. J Cell Sci 2011; 124:2539-51. [PMID: 21768326 DOI: 10.1242/jcs.085852] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The microtubule (MT) plus-end-tracking protein EB1 is required for assembly of primary cilia in mouse fibroblasts, but the mechanisms involved and the roles of the related proteins EB2 and EB3 in ciliogenesis are unknown. Using protein depletion experiments and expression of dominant-negative constructs we show here that EB1 and EB3, but not EB2, are required for assembly of primary cilia in cultured cells. Electron microscopy and live imaging showed that cells lacking EB1 or EB3 are defective in MT minus-end anchoring at the centrosome and/or basal body, and possess abnormally short cilia stumps surrounded by vesicles. Further, GST pull-down assays, mass spectrometry and immunoprecipitation indicated that EB1 and EB3 interact with proteins implicated in MT minus-end anchoring or vesicular trafficking to the cilia base, suggesting that EB1 and EB3 promote ciliogenesis by facilitating such trafficking. In addition, we show that EB3 is localized to the tip of motile cilia in bronchial epithelial cells and affects the formation of centriole-associated rootlet filaments. Collectively, our findings indicate that EBs affect biogenesis of cilia by several centrosome-related mechanisms and support the idea that different EB1-EB3 dimer species have distinct functions within cells.
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Affiliation(s)
- Jacob M Schrøder
- Department of Biology, University of Copenhagen, Universitetsparken 13, DK-2100 Copenhagen, Denmark
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Taschner M, Bhogaraju S, Lorentzen E. Architecture and function of IFT complex proteins in ciliogenesis. Differentiation 2011; 83:S12-22. [PMID: 22118932 DOI: 10.1016/j.diff.2011.11.001] [Citation(s) in RCA: 149] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 10/31/2011] [Accepted: 11/03/2011] [Indexed: 01/25/2023]
Abstract
Cilia and flagella (interchangeable terms) are evolutionarily conserved organelles found on many different types of eukaryotic cells where they fulfill important functions in motility, sensory reception and signaling. The process of Intraflagellar Transport (IFT) is of central importance for both the assembly and maintenance of cilia, as it delivers building blocks from their site of synthesis in the cell body to the ciliary assembly site at the tip of the cilium. A key player in this process is the multi-subunit IFT-complex, which acts as an adapter between the motor proteins required for movement and the ciliary cargo proteins. Since the discovery of IFT more than 15 years ago, considerable effort has gone into the purification and characterization of the IFT complex proteins. Even though this has led to very interesting findings and has greatly improved our knowledge of the IFT process, we still know very little about the overall architecture of the IFT complex and the specific functions of the various subunits. In this review we will give an update on the knowledge of the structure and function of individual IFT proteins, and the way these proteins interact to form the complex that facilitates IFT.
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Affiliation(s)
- Michael Taschner
- Max-Planck-Institute of Biochemistry, Department of Structural Cell Biology, Am Klopferspitz 18, D-82152 Martinsried, Germany
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Abstract
Eukaryotic cilia and flagella perform motility and sensory functions which are essential for cell survival in protozoans, and to organism development and homoeostasis in metazoans. Their ultrastructure has been studied from the early beginnings of electron microscopy, and these studies continue to contribute to much of our understanding about ciliary biology. In the light of the progress made in the visualization of cellular structures over the last decade, we revisit the ultrastructure of cilia and flagella. We briefly describe the typical features of a 9+2 axoneme before focusing extensively on the transition zone, the ciliary necklace, the singlet zone, the ciliary cap and the ciliary crown. We discuss how the singlet zone is linked to sensory and/or motile function, the contribution of the ciliary crown to ovocyte and mucosal propulsion, and the relationship between the ciliary cap and microtubule growth and shortening, and its relation to ciliary beat. We further examine the involvement of the transition zone/the ciliary necklace in axonemal stabilization, autotomy and as a diffusion barrier.
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Lauwaet T, Smith AJ, Reiner DS, Romijn EP, Wong CCL, Davids BJ, Shah SA, Yates JR, Gillin FD. Mining the Giardia genome and proteome for conserved and unique basal body proteins. Int J Parasitol 2011; 41:1079-92. [PMID: 21723868 PMCID: PMC4521607 DOI: 10.1016/j.ijpara.2011.06.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 05/25/2011] [Accepted: 06/01/2011] [Indexed: 12/27/2022]
Abstract
Giardia lamblia is a flagellated protozoan parasite and a major cause of diarrhoea in humans. Its microtubular cytoskeleton mediates trophozoite motility, attachment and cytokinesis, and is characterised by an attachment disk and eight flagella that are each nucleated in a basal body. To date, only 10 giardial basal body proteins have been identified, including universal signalling proteins that are important for regulating mitosis or differentiation. In this study, we have exploited bioinformatics and proteomic approaches to identify new Giardia basal body proteins and confocal microscopy to confirm their localisation in interphase trophozoites. This approach identified 75 homologs of conserved basal body proteins in the genome including 65 not previously known to be associated with Giardia basal bodies. Thirteen proteins were confirmed to co-localise with centrin to the Giardia basal bodies. We also demonstrate that most basal body proteins localise to additional cytoskeletal structures in interphase trophozoites. This might help to explain the roles of the four pairs of flagella and Giardia-specific organelles in motility and differentiation. A deeper understanding of the composition of the Giardia basal bodies will contribute insights into the complex signalling pathways that regulate its unique cytoskeleton and the biological divergence of these conserved organelles.
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Affiliation(s)
- Tineke Lauwaet
- Department of Pathology, University of California San Diego, San Diego, CA 92103, USA.
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Aylett CH, Löwe J, Amos LA. New Insights into the Mechanisms of Cytomotive Actin and Tubulin Filaments. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2011; 292:1-71. [DOI: 10.1016/b978-0-12-386033-0.00001-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Life with eight flagella: flagellar assembly and division in Giardia. Curr Opin Microbiol 2010; 13:480-90. [PMID: 20580308 DOI: 10.1016/j.mib.2010.05.014] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Revised: 05/26/2010] [Accepted: 05/27/2010] [Indexed: 11/23/2022]
Abstract
Flagellar movement in Giardia, a common intestinal parasitic protist, is crucial to its survival in the host. Each axoneme is unique in possessing a long, cytoplasmic portion as well as a membrane-bound portion. Intraflagellar transport (IFT) is required for the assembly of membrane-bound regions, yet the cytoplasmic regions may be assembled by IFT-independent mechanisms. Steady-state axoneme length is maintained by IFT and by intrinsic and active microtubule dynamics. Following mitosis and before their segregation, giardial flagella undergo a multigenerational division cycle in which the parental eight flagella migrate and reposition to different cellular locations; eight new flagella are assembled de novo. Each daughter cell thus inherits four mature and four newly synthesized flagella.
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